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f011c191-b6ac-4d75-8320-3551b108397f
| 0 |
Further studies on the fertility promoting factor from human seminal plasma. A small molecular weight substance from human seminal plasma has been further purified by chromatography. The fertility promoting action of this factor on epididymal sperm has been confirmed in mouse in vitro and in vivo. Experimental evidence indicates that the factor acts on the sperm and not on the eggs. Its possible mode of action is by improving the motility and survival of the epididymal sperm.
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2c1dc9e7-1dc3-4526-8ccb-f5e187535182
| 0 |
The presence of paternal H-2 antigens on hybrid mouse blastocysts during experimental delay of implantation and the disappearance of these antigens after onset of implantation. The presence of paternal H-2 antigens on hybrid mouse blastocysts before and during implantation was investigated by means of the isotope anti-globulin technique. It was found that experimentally delayed blastocysts possess paternal H-2 antigens whereas these antigens can no longer be detected 14 hours after estradiol activation of delayed blastocysts.
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25dfd545-69ca-410c-815b-073450968829
| 0 |
Effect of copper and plastic intra-uterine devices on the fibrinolytic activity of the endometrium in the rat. The effect of copper and plastic intrauterine devices (IUD) on the fibrinolytic activity of the endometrium was studied in the rat. A copper or a plastic device was placed in one of the uterine horns, while the other horn served as a control.
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25dfd545-69ca-410c-815b-073450968829
| 1 |
Biopsy specimens were obtained from both horns and examined histochemically. The copper concentration was determined by atomic absorption spectroscopy. The fibrinolytic activity of the control horn was found to be localized to small vessels in the outer layer of the uterine wall, while that of the endometrium was low.
|
25dfd545-69ca-410c-815b-073450968829
| 2 |
Plastic as well as copper IUDs increased the fibrinolytic activity which, in contrast with what was seen in the controls, was localized to the endometrium. Compared with the effect of the plastic device, the increase in the fibrinolytic activity induced by the copper device was more widespread in the endometrial area and was accompanied by an increase in the concentration of copper.
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25dfd545-69ca-410c-815b-073450968829
| 3 |
These findings might help to explain why the contraceptive effect of IUDs is more reliable when they are partly coated with copper.
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f29071a5-3787-479d-bc60-deaa9003422e
| 0 |
Participation of vitamin A in the maturation of rabbit spermatozoa. Vitamin A concentration was fluorometrically measured in epididymal and ejaculated rabbit spermatozoa and in some of the sperm cells subcellular components. The concentration of vitamin A in the epididymal cells was about one-half that observed in the ejaculated spermatozoa (2.68
|
f29071a5-3787-479d-bc60-deaa9003422e
| 1 |
as against 1.05 mug/10(8) cells) and seemed to be the same in the sperms obtained from both the head and the tail of the epididymus. The concentration of vitamin A was also found to be significantly higher in the seminal plasma than in the epididymal secretion (0.06
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f29071a5-3787-479d-bc60-deaa9003422e
| 2 |
as against 0.039 mug/mg protein respectively). Practically all the vitamin A was found in the fractions obtained by treatment with hypotonic MgCl2 (acrosomal region) and/or with hyamine and dithiothreitol (plasma membrane). It was concluded that the sudden increase in the sperm concentration of vitamin A that occurs upon ejaculation may be required for the stabilization of the acrosomal and plasma membranes.
|
f599c40c-45fe-4342-b7da-e75b2f3b0c7f
| 0 |
Evaluation of d-norgestrel 1.0 mg as a post-coital contraceptive. Two hundred and ninety-eight women were followed for 2578 months (2739 'bleeding intervals') of treatment with d-Norgestrel 1.0 mg given as a post-coital oral contraceptive. Fourteen pregnancies were recorded (general failure rate, 6.5 per 100 woman/years);
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f599c40c-45fe-4342-b7da-e75b2f3b0c7f
| 1 |
at least 6 of these patients did not miss any tablet (corrected failure rate, 2.8). The acceptability rates (life table method) were 0.58 and 0.40 after 6 and 12 months of follow-up. The most important medical reason for drop-out was cycle irregularities. The cycle pattern is deeply disturbed by this method of oral contraception.
|
2eca1b58-ca1b-4581-9e44-73cd693606ff
| 0 |
"Genital dyscrinism" as a cause of subfertility in mice of the CBA strain. Following four generations of inbred mating (brother-sister) in three direct lineages of CBA strain mice, sterility appeared which from that generation forward became more frequent. The genital organs in animals of both sexes were altered.
|
2eca1b58-ca1b-4581-9e44-73cd693606ff
| 1 |
There was a noticeable occurrence of cysts in the ovaries of female animals already following the third month; in mice approximately one year of age this condition was followed by cystic glandular hyperplasia of the endometrium, sometimes complicated by disturbances in blood circulation, inflammation or even malignancy. In some female animals, manifesting, due to cysts, completely degenerated ovaries, the rest of the genital system was severely atrophic.
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2eca1b58-ca1b-4581-9e44-73cd693606ff
| 2 |
Male animals frequently showed severe atrophy of the seminiferous epithelium along with preserved interstitial cells and hypertrophic seminal vesicles. These pathological changes represent an independent nosologic unit, for which the label "genital dyscrinism" has been proposed. The authors have considered an endocrine mechanism as the possible cause of these pathological changes which are presumed to be genetically conditioned.
|
84293033-5f5b-4ba6-827c-a605ff8f7ea9
| 0 |
Motility of the rat oviductal tract isolated in different stages of the sex cycle. Effects of catecholamines. Physiological and pharmacological characteristics of the spontaneous motility of rat oviductal tracts (the coiled oviduct plus its mesosalpinx), isolated in proestrus, estrus or metestrus, are described. The initial contractile tension (recorded following isolation) was comparable in the three stages of the cycle, but its decrement with time was greater in metestrus than in proestrus;
|
84293033-5f5b-4ba6-827c-a605ff8f7ea9
| 1 |
the opposite being observed regarding the rate of contractions. Norepinephrine and phenylephrine depress motility in proestrus and metestrus, but not in estrus. The inhibition of motility during proestrus, produced by added norepinephrine, phenylephrine or isoproterenol was not modified by phenotolamine but was abolished by propranolol. During estrus, norepinephrine and phenylephrine inhibited tubal contractions of preparations incubated with phentolamine, whereas it produced a distinct stimulation in the presence of propranolol.
|
84293033-5f5b-4ba6-827c-a605ff8f7ea9
| 2 |
It is concluded that: (a) the rat mesosalpinx might play some role in the motility of the whole isolated oviductal tract; (b) there are variations in the decrement with time of contractile tension and frequency of contractions in different stages of the sex cycle; (c) the effects of catecholamines upon the rat oviductal tract also varies within the cycle, probably due to influences imposed by sex hormones.
|
8b16c619-e9ba-4452-b547-c979f7df0aa9
| 0 |
The effect of prostaglandins and prostaglandin inhibitors on spermatogenesis. The effect of the prostaglandin inhibitors, aspirin and indomethacin and of prostaglandins PGE1 and PGE2 on spermatogenesis in the mature male mouse has been studied. Aspirin at 100 mg/kg and at 200 mg/kg, and indomethacin at 1.0 mg/kg given orally twice a day for fifteen days produced a marked increase in spermatogenesis.
|
8b16c619-e9ba-4452-b547-c979f7df0aa9
| 1 |
The number of step 7 spermatids increased significantly over controls at about the same rate in all three groups. No significant changes in seminal vesicle weight or testicular weight was noted, although testicular weight did show an increase. Administration of prostaglandins E1 and E2 subcutaneously in doses of either 2 mg/kg or 3 mg/kg once a day for fifteen days produced a marked decrease in spermatogenesis.
|
8b16c619-e9ba-4452-b547-c979f7df0aa9
| 2 |
Step 7 spermatids decreased significantly at both dosage levels of PGE2 and at the higher dosage level of PGE1. Spermatocyte showed a significant decrease at the higher dose of PGE2. Testicular weight showed a significant decrease at the higher dose of PGE2. Seminal vesicle weight showed a significant decrease at the lower dose of PGE1 and at the higher dose of PGE2.
|
8b16c619-e9ba-4452-b547-c979f7df0aa9
| 3 |
Epididymal weight decreased at the higher dose of PGE2. Increased numbers of exfoliated immature germ cells and mature spermatozoa were observed in the epididymus of both the PGE1 and PGE2 treated animals.
|
5ae792d6-3141-4f7a-8e64-dd294e239fe5
| 0 |
Low fertility rate in vasovasostomized males and its possible immunologic mechanism. Contradictory views have been expressed about the role of the various antisperm antibodies which develop after vasoligation. The present study was conducted in 50 normal fertile males, 50 vasectomized subjects and 25 subjects after recanalization of their vas deferens in order to investigate the development of various anti-sperm antibodies after vasectomy, along with their incidence, their persistence after successful relief of vaso-obstruction by vasovasostomy and their role in the causation of infertility in vasoanatomized normospermia males.
|
5ae792d6-3141-4f7a-8e64-dd294e239fe5
| 1 |
Sperm agglutinating, immobilizing and haemagglutinating antibodies showed rises in titres with increase during the post-vasectomy period, indicating continuous antigenic stimulus. Age, post-operative complications and blood group did not seem to alter the results. 86% of subjects developed antisperm agglutinins, mostly tail-to-tail type (54.5
|
5ae792d6-3141-4f7a-8e64-dd294e239fe5
| 2 |
%), 1-12 years after vasoligation, while only 2% of fertile men had circulating spermagglutinins. A lower incidence of positive sperm in the immobilization test than in the agglutination test suggests either that different antibodies are detected by these two tests or these tests have differing sensitivities. Of the 25 vasovasostomized subject, 13 (52%) cases became normospermic and 4 (16%) oligospermic while 8 (32%) remained azoospermics.
|
5ae792d6-3141-4f7a-8e64-dd294e239fe5
| 3 |
Except for 3 oligospermic subjects, all had circulating spermagglutinins. Among the 13 normospermic vasovasostomized persons, a significant correlation was found between the titres of circulating antisperm agglutinins and autoagglutination of spermatozoa in their ejaculates; and also between the sperm immobilization values of their sera and the degree of their sperm motility.
|
5ae792d6-3141-4f7a-8e64-dd294e239fe5
| 4 |
Three normospermic recanalized men, having low levels of sperm agglutinins and haemagglutinins with normal seminogram and no sperm immobilizing antibody, successfully impregnated their wives. Another 10 vasovasotomized infertile subjects had sperm agglutinins in significant titre; 5 showed positive sperm immobilization values, a similar number showed autoagglutination of sperm, while a decreased degree of motility of sperms was noted in 6 cases.
|
5ae792d6-3141-4f7a-8e64-dd294e239fe5
| 5 |
Thus there was a significant correlation between the titres of anti-sperm antibodies and autoagglutination of spermatozoa, which might be an important cause of male infertility after successful anatomic relief of vasoobstruction. Histological studies of testicular biopsy showed normal spermatogenesis in azoospermic recanalized subjects, although they had high levels of antisperm antibodies.
|
5ae792d6-3141-4f7a-8e64-dd294e239fe5
| 6 |
This suggests that these antibodies do not affect normal spermatogenesis, and sperm counts.
|
ef90342a-7f84-4514-9978-d3648bd3d8f4
| 0 |
Studies on urinary arylsulphatase activity in vitamin A deficient rats. Urinary arylsulphatases (E.C.3.1.6.1) A and B were increased in male rats fasted for 24 hours. Excretion of non dialysable protein nitrogen decreased whereas creatinine excretion increased. On refeeding diet arylsulphatase A activity was restored to normal whereas arylsulphatase B was not normalised.
|
ef90342a-7f84-4514-9978-d3648bd3d8f4
| 1 |
A single oral supplementation of vitamin A acetate (20 000 IU) to rats fasted for 24 hours resulted in a significant reduction of both arylsulphatase A and B eventhough no further reduction of protein nitrogen excretion was evident. In vitamin A deficient male rats significant reduction in urinary excretion of both arylsulphatases A and B occured.
|
ef90342a-7f84-4514-9978-d3648bd3d8f4
| 2 |
In a smaller number of female rats depression of only arylsulphatase A was observed. This effect of vitamin A deficiency leading to reduced urinary arylsulphatase activity was evident even at the "weight plateau" stage when no reduction in food intake or growth had occurred. These results suggest a possible direct or indirect role for vitamin A on urinary excretion pattern of arylsulphatases presumably released from lysosomes of tissues.
|
64190c77-0694-4bcd-adb2-7d861a5aa4d3
| 0 |
Effect of long-term starvation on the rat liver lysosomes. The effect of 120- and 240-h starvation on rats hepatocytes ultrastructure and particularly the changes of the lysosomes were studied. Eelectronmicroscopically and cytochemically there have been observed diminution of the number of mitochondria and degranulation and vacuolzation of the ER.
|
64190c77-0694-4bcd-adb2-7d861a5aa4d3
| 1 |
At the same time Golgi complex was hypertrophied and the number of lysosomes was much increased, mainly those of the autophagic type. Biochemically was shown, that the activity of some acid hydrolases (beta-glucosidase, alpha- and beta-galactosidases, beta-N-acetylglucosaminidase, beta-glucuronidase and arylsulphatases A and B) in the liver of starved rats was markedly expressed.
|
64190c77-0694-4bcd-adb2-7d861a5aa4d3
| 2 |
The sedimentation properties of the lysosomes and the lysosomal membrane stability was damaged as well. The data received have been discussed in the light of the reconstructive role of lysosomes.
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d849d44d-3d89-4081-b4cd-adfcf988d875
| 0 |
Hypogastric carotid bypass for Takayasu's disease. Two cases of Takayasu's disease are presented which were successfully resolved by a Dacron graft from the right hypogastric artery to the right internal carotid artery. We recommend this bypass procedure of connecting the hypogastric artery to one of the aortic branches. Medical treatment with antibiotics, steroids and anti-coagulants has not been satisfactory.
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e4904717-af1f-4116-9385-c52356b44e19
| 0 |
Psychopharmacology research ward. Ten years' experience. The differences between the results of controlled clinical research and the experiences of the practitioners can be attributed to a certain extent to the artificiality of the setting in which controlled studies are performed. The system developed in the wards of the Department of Psychopharmacology of the Institute of Psychiatry in Prague is an attempt to overcome some of these difficulties.
|
e4904717-af1f-4116-9385-c52356b44e19
| 1 |
Certain similarities exist between this system called continuous controlled trial and 'silent' trial proposed by Ross et al. The main characteristics of the system are: (1) all patients admitted to the ward are assigned to the trial without exception; (2) the trial goes on continuously without interruption for more than 10 years;
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e4904717-af1f-4116-9385-c52356b44e19
| 2 |
(3) except that the patients do not know the quality of drugs administered they do not realize any difference between this research setting and the usual routine treatment. The advantages of this system are: reduction of artificiality; the possibility to perform early clinical trials in controlled conditions and to shorten the usual three-phase testing of a new drug;
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e4904717-af1f-4116-9385-c52356b44e19
| 3 |
the possibility to perform long-term, longitudinal studies with individual patients admitted several times in double-blind conditions.
|
32c0beaa-c52f-443d-9ce9-64b0c5e678a2
| 0 |
[Comparative study of three psychotropics for treatment of depressions]. The effect of three anti-depressive psychotropes (Clorimipramine, Doxepine and Dibenzepine) was studied in 107 depressed patients. In each patient the mean value of twelve symptoms was evaluated and compared weekly (for 4 weeks), by statistical methods.
|
32c0beaa-c52f-443d-9ce9-64b0c5e678a2
| 1 |
In addition, the effect of each drug was analysed in personality stratus. A thymeretic and thymoanaleptic rapid action on 'corporality' and 'endotimic-vital' layer was found with Clorimipramine. Doxepine acts rapidly with sedative and anxiolitic actions on reactive symptoms related with personality super-structures having long term anti-depressive effects.
|
32c0beaa-c52f-443d-9ce9-64b0c5e678a2
| 2 |
Dibenzepine has a thymeretic rapid and intensive action and a slow thymoanaleptic effect on the same personality stratus of Clorimipramine.
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f728c09d-d0e6-480e-b8ef-749a9162ac48
| 0 |
Properties of rat lens phosphofructokinase. Two interconvertible forms of phosphofructokinase (PFK) have been eluted from a DEAE-cellulose column from the supernatant fraction of rat lens homogenates centrifuged at 96,000 x g for 1 hour at 0 to 4 degrees C. The interconversion can be manipulated by a change in the pH of the extracting and eluting buffers.
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f728c09d-d0e6-480e-b8ef-749a9162ac48
| 1 |
PFK-I is the dominant form at pH between 7.4 to 7.05, while PFK-II dominates at pH 7.4 to 8.2. PFK-II is believed to be the functional form; it is inhibited by high concentrations of ATP and the inhibitory effect is enhanced by more acidic pH.
|
f728c09d-d0e6-480e-b8ef-749a9162ac48
| 2 |
Fructose-6-phosphate counteracts ATP inhibition, but the most potent de-inhibitors are ADP and AMP. Among the inorganic ions tested, sulfate, phosphate, ammonium, and potassium also de-inhibit, whereas calcium further inhibits the enzyme. The behavior of PFK under physiologic conditions and the significance of the presence of two forms of PFK in the lens are discussed.
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275f75c7-2536-4a92-8ae6-86dd2ca4f04a
| 0 |
Effects of pregnancy on the development of acute uremic syndrome in the rat. We evaluated the contributory role which gestational metabolic adaptions may play in the development of acute uremic syndrome in rats by studying the effects of nephrectomy in pregnant and nonpregnant animals. Whereas no significant differences in creatinine and uric acid concentrations were found between control and pregnant rats, urea concentrations were significantly lower in the pregnant animals before, as well as well as 6, 12 and 24 h after, bilateral nephrectomy.
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275f75c7-2536-4a92-8ae6-86dd2ca4f04a
| 1 |
It is suggested that creatinine production, which is related to muscle mass, is not altered during late gestation, whereas urea synthesis, which is affected by catabolic and anabolic factors, is significantly reduced.
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2f2e5444-05ed-4ccb-9d18-0ae0a44be9e0
| 0 |
Blood-gas analysis and the assessment of acid-base status. In this article the more common kinds of acid-base disorders have been discussed. To accurately assess the kind of acid-base disturbance found in a patient, the clinician must know the arterial pH, PaCO2, and the [HCO-3] in arterial blood. Acid-base disturbances are associated with fluid and electrolyte disturbances. Potassium balance is often upset in acid-base disturbances. Accurate determination of K+ balance requires serial or repeated determinations of plasma K+ concentration as well as careful clinical monitoring.
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4d789744-a173-4afe-800f-cb6ca26c52f6
| 0 |
Intracellular distinction between peroxidase and catalase in exocrine cells of rat lacrimal gland: a biochemical and cytochemical study. The lacrimal gland (Glandula orbitalis externa) of rat contains both peroxidase and catalase and was used as a model for biochemical and cytochemical distinction between peroxidase and catalase. Both enzymes were isolated by ammonium sulfate precipitation from tissue homogenates, and the effects of fixation with glutaraldehyde and various conditions of incubation were investigated colorimetrically using DAB as hydrogen donor.
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4d789744-a173-4afe-800f-cb6ca26c52f6
| 1 |
The lacrimal gland peroxidase is strongly inhibited by glutaraldehyde treatment. In contrast, for catalase the fixation with glutaraldehyde is the prerequistie for demonstration of its peroxidatic activity. The maximal peroxidatic activity was obtained after treatment of catalase with 3% glutaraldehyde, higher concentrations being inhibitory. For lacrimal gland peroxidase, the maximal rate of oxidation of DAB is at pH 6.5
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4d789744-a173-4afe-800f-cb6ca26c52f6
| 2 |
, whereas for catalase it is at pH 10.5. The optimal concentration of H2O2 for lacrimal gland peroxidase is at 10(-3)M and for peroxidatic activity of catalase at 10(-1)M. These optimal conditions obtained biochemically were applied to tissue sections of rat lacrimal gland.
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4d789744-a173-4afe-800f-cb6ca26c52f6
| 3 |
After the fixation of tissue with a low concentration of glutaraldehyde and incubation in the DAB medium at neutral pH containing 10(-3)M H2O2 (Peroxidase medium), the reaction product was localized in the cisternae of the rough endoplasmic reticulum, in elements of the Golgi apparatus, and in secretory granules. After the fixation of tissue with 3% glutaraldehyde and incubation in the DAB-medium containing 10(-1)M H2O2 and at pH 10.5
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4d789744-a173-4afe-800f-cb6ca26c52f6
| 4 |
(catalase medium), the staining in the endoplasmic reticulum, the Golgi-apparatus and in secretory granules was completely inhibited and reaction product was localized exclusively in small (0.2-0.5 mu) particles similar to small peroxisomes described in various other cell-types.
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c923e170-41f3-4c71-abb3-35e9312297a4
| 0 |
Arterial blood-gas interpretations in the respiratory intensive-care unit. The role of the nurse in the respiratory intensive-care unit requires increased sophistication as our knowledge of the patient becomes more complex. This expanded role should include a thorough understanding of disturbances in acid-base balance, the relationship of PaCO2 to ventilation, the difference in acute and chronic respiratory problems, and the causes and treatment of hypoxemia. The ability to analyze and evaluate blood-gas determinations is simply one more important tool the nurse may utilize in the care and treatment of the critically ill patient.
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42982d73-e45b-4609-9000-8a8a67ee16cf
| 0 |
Antimycin A fermentation. II. Fermentation in aerated-agitated fermenters. Fermentation characteristics, previously studied in shake flasks, were reproduced in aerated-agitated fermenters, using three strains of Streptomyces sp. which had been selected for their high antimycin A productivity in shake flasks. Fermentation in fermenters was run in three stages.
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42982d73-e45b-4609-9000-8a8a67ee16cf
| 1 |
The medium consisted of soy flour, glucose, ammonium sulfate and calcium carbonate; initial pH was 7.2 approximately 7.5, and temperature 25 degrees C. The course of fermentation was then modified to encourage maximal growth and eliminate the intermediate lag period observed in shake flasks. Useful corrections included continuous addition of soybean oil at 1.25
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42982d73-e45b-4609-9000-8a8a67ee16cf
| 2 |
%/day and maintenance of pH at 6 by addition of ammonium hydroxide on demand. The ammonium hydroxide added also served as a rapidly utilized nitrogen source and could not be replace by NaOH or KOH. Under optimal conditions antimycin A was produced at constant rate from the second to the sixth day, when maximum yields of more than 9 g/liter were attained.
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42982d73-e45b-4609-9000-8a8a67ee16cf
| 3 |
A procedure for antimycin A extraction is described.
|
04d4fd1a-04fc-40d5-bac6-1293f5ac6986
| 0 |
Nutritionally defined conditions for germination of Streptomyces viridochromogenes spores. Spores of Streptomyces viridochromogenes were removed from the surface of solid media with glass beads and suspended in a buffer-detergent solution. Addition of yeast extract and glucose resulted in rapid loss of refractility of the spores. Appearance of germ tubes followed.
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04d4fd1a-04fc-40d5-bac6-1293f5ac6986
| 1 |
Germination was accompanied by a decrease in the optical density (OD) of the suspension. The OD decrease was used as an assay for germination. A defined germination medium (DGM) comprised of L-alanine, L-glutamic acid, adenosine, para-aminobenzoic acid, and calcium and magnesium ions provided a germination rate nearly equal to that of complex media.
|
04d4fd1a-04fc-40d5-bac6-1293f5ac6986
| 2 |
The germination rate was essentially the same if D-alanine and D-glutamate replaced the L-isomers. The optimum pH and temperature for germination were 7.0 and 35 C. Germination was absolutely dependent on the presence of CO2. Spores harvested after growth for longer periods than the usual time (10 days) became less germinable in DGM.
|
04d4fd1a-04fc-40d5-bac6-1293f5ac6986
| 3 |
The same was observed for spores grown at 37 C as compared with 30 C. Spores incubated in DGM for various time periods before being transferred to a buffer solution did not continue to germinate. Spores harvested after growth of eight species of Streptomyces did not show a decrease in OD when incubated in yeast extract medium.
|
04d4fd1a-04fc-40d5-bac6-1293f5ac6986
| 4 |
Another strain of S. viridochromogenes did exhibit an OD decrease in the medium. Comparative properties of spores of streptomycetes, fungi, and bacilli are discussed.
|
02d2006c-8e21-4dcc-842e-f773e8883207
| 0 |
Effect of pH on competence development and deoxyribonucleic acid uptake in Streptococcus sanguis (Wicky). Streptococcus sanguis (Wicky) cells, strain WE4, developed little or no competence and failed to autolyze in permissive conditions when treated with competence factor (CF) below PH 7.0. This lack of activity was directly correlated with the inability of the cells to bind or take up CF at pH values of 5.5
|
02d2006c-8e21-4dcc-842e-f773e8883207
| 1 |
, 6.0, and 6.5. On the other hand, competent cells bound deoxyribonucleic acid molecules maximally below pH 7.0 and transformed maximally at pH 6.5. Deoxyribonucleic acid was optimally bound to cells in a deoxyribonuclease-resistant form at pH values between 7.0 and 8.5. Concomitant with this binding, undefined acid-soluble DNA fragments appeared in the culture menstrua.
|
02d2006c-8e21-4dcc-842e-f773e8883207
| 2 |
CF binding and uptake by cells was not only influenced by low pH but also by low temperature. At 0 C, WE4 cells bound only 4% of the input CF and took up less than 1% into a trypsin-insensitive state compared to cells treated at 37 C.
|
02d2006c-8e21-4dcc-842e-f773e8883207
| 3 |
Cells treated with CF at 0 C did not autolyze when transferred to permissive conditions. The results presented in this report extend earlier findings that showed that competence development and autolysis are related to the uptake of CF.
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681cd47e-2acf-46b7-9e08-eacc14e2c37f
| 0 |
Control of inositol biosynthesis in Saccharomyces cerevisiae: properties of a repressible enzyme system in extracts of wild-type (Ino+) cells. Inositol biosynthesis was studied in soluble, cell extracts of a wild-type (Ino) strain of Saccharomyces cerevisiae. Two reactions were detected: (i) conversion of D-glucose-6-phosphate to a phosphorylated form of inositol, presumably inositol-1-phosphate (IP synthethase, EC5.5.1.4
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681cd47e-2acf-46b7-9e08-eacc14e2c37f
| 1 |
), and (ii) conversion of phosphorylated inositol to inositol (IP phosphatase, EC3.1.3.25). The in vitro rate of conversion of glucose-6-phosphate to inositol was proportional to incubaion time and enzyme concentration. The pH optimum was 7.0. The synthesis of inositol required oxidized nicotinamide adenine dinucleotide (NAD) and was stimulated byNH4C1 and MgC12.
|
681cd47e-2acf-46b7-9e08-eacc14e2c37f
| 2 |
NADP substituted poorly for NAD, and NADH inhibitedthe reaction. Phosphorylated inositol accumulated in the absence of MgC12, suggesting that inositol-phosphate is an intermediate in the pathway and that Mg ions stimulate the dephosphorylation of inositol-phosphate. IP synthetase was inhibited approximately 20% in the presence of inositol in the reaction mixture at concentrations exceeding 1 mM.
|
681cd47e-2acf-46b7-9e08-eacc14e2c37f
| 3 |
The enzyme was repressed approximately 50-fold when inositol was present in the growth medium at concentrations exceeding 50 muM. IP synthetase reached the fully repressed level approximately 10 h after the addition of inositol to logarithmic cultures grown in the absence of inositol. The specific activity of the enzyme increased with time in logarithmically growing cultures lacking inositol andapproached the fully depressed level as the cells entered stationary phase.
|
f0bec9e3-1eae-4d1a-9d40-e418afc0ab25
| 0 |
Heat activation of Streptomyces viridochromogenes spores. The lag period preceding germination of Streptomyces viridochromogenes spores during incubation in a defined germination medium was completely eliminated by a gentle heat shock. The rate of germination was not affected. The optimum pH for activation extended from 6.0 to 9.6. The time of heating required for maximum activation was 1 min at 60 C, 2 to 5 min at 55 C, 20 min at 50 C, and 40 to 50 min at 45 C.
|
f0bec9e3-1eae-4d1a-9d40-e418afc0ab25
| 1 |
Activated spores had the same temperature and pH optima and nutritional requirements for germination as unactivated spores. Activated spores deactivated during incubation for 8 h at 25 C and were activated again by a second heat shock. Spores that had been aged for 4 weeks or longer did not germinate in the defined germination medium unless they were first heat activated.
|
8bc5425c-d16e-4200-a6cc-5046f83bb333
| 0 |
Glucose transport in isolated prosthecae of Asticcacaulis biprosthecum. Active transport of glucose in prosthecae isolated from cells of Asticcacaulis biprosthecum was stimulated by the non-physiological electron donor N, N, N', N'-tetramethyl-p-phenylenediamine dihydrochloride. Glucose uptake was mediated by two transport systems; the apparent Km of the high-affinity system was 1.8
|
8bc5425c-d16e-4200-a6cc-5046f83bb333
| 1 |
muM and that of the low-affinity system was 34 muM. Free glucose accumulated within prosthecae at a concentration 60 to 200 times above that present externally, depending on the Km of the system being observed. The glucose transport system in prosthecae was stereospecific for D-glucose, and neither methyl alpha-D-glucopyranoside nor 2-deoxyglucose was transported.
|
8bc5425c-d16e-4200-a6cc-5046f83bb333
| 2 |
Uptake of glucose was inhibited by N-ethylmaleimide (NEM) and p-chloromercuribenzoate (PCMB), and the inhibition by PCMB but not by NEM was reversed by dithiothreitol. Glucose uptake was also inhibited by the uncoupling agents 5-chloro-3-t-butyl-2'-nitrosalicylanilide (S-13), 5-chloro-3-(p-chlorophenyl)-4'-chlorosalicylanilide (S-6), and carbonyl-cyanide m-chlorophenylhydrazone (CCCP) and by the respiratory inhibitor KCN.
|
8bc5425c-d16e-4200-a6cc-5046f83bb333
| 3 |
Efflux of glucose from preloaded prosthecae was induced by PCMB and KCN, but not by S-13 or CCCP. Glucose uptake was not affected by arsenate or an inhibitor of membrane-bound adenosine triphosphatases, N, N'-dicyclohexylcarbodiimide. The lack of inhibition by these two compounds, combined with the extremely low levels of adenosine 5'-triphosphate present in prosthecae, indicates that adenosine 5'-triphosphate is not involved in the transport of glucose by prosthecae.
|
e62f65ea-8d43-49fc-a909-e4fe6140c427
| 0 |
Defective synthesis of lipid intermediates for peptidoglycan formation in a stabilized L-form of Streptococcus pyogenes. Membrane preparations obtained from a stabilized L-form of Streptococcus pyogenes are incapable of synthesizing peptidoglycan from uridine-5'-diphospho-N-acetyl-D-muramyl-L-Ala-D-iso-Glu-L-Lys-D-Ala-D-Ala and uridine-5'-diphospho-N-acetyl-D-glucosamine, in contrast with similar preparations from the parental streptococcus.
|
e62f65ea-8d43-49fc-a909-e4fe6140c427
| 1 |
Furthermore, 50-fold higher levels of lipid intermediates which serve as membrane-bound substrates for peptidoglycan synthesis are synthesized in reaction mixtures containing streptococcal membranes than with similar preparations from the L-form. These observations suggest that the inability of this stabilized L-form to form a cell wall in vivo lies, at least in part, in its failure to synthesize significant quantities of the lipid substrates for peptidoglycan synthesis.
|
98761c64-0e99-49a8-9ff6-69c4da410d67
| 0 |
Protonmotive force as the source of energy for adenosine 5'-triphosphate synthesis in Escherichia coli. Net synthesis of adenosine 5'-triphosphate (ATP) in energy-depleted cells of Escherichia coli was observed when an inwardly directed protonmotive force was artificially imposed. In wild-type cells, ATP synthesis occurred whether the protonmotive force was dominated by the membrane potential (negative inside) or the pH gradient (alkaline inside).
|
98761c64-0e99-49a8-9ff6-69c4da410d67
| 1 |
Formation of ATP did not occur unless the protonmotive force exceeded a value of 200 mV. Under these conditions, no ATP synthesis was found when cells were exposed to an inhibitor of the membrane-bound Ca2+- and Mg2+- stimulated adenosine triphosphatase (EC 3.6.1.3), dicyclohexylcarbodiimide, or to a proton conductor, carbonylcyanide-p-trifluoromethoxyphenyl-hydrazone.
|
98761c64-0e99-49a8-9ff6-69c4da410d67
| 2 |
Adenosine triphosphatase-negative mutants failed to show ATP synthesis in response to either a membrane potential or a pH gradient. ATP synthesis driven by a protonmotive force was observed in a cytochrome-deficient mutant. These observations are consistent with the chemiosmotic hypothesis of Mitchell (1961, 1966, 1974).
|
8069adc3-1a78-41b9-a085-11198b248a12
| 0 |
Inhibition of dimethyl ether and methane oxidation in Methylococcus capsulatus and Methylosinus trichosporium. Metal-chelating or -binding agents inhibited the oxidation of dimethyl ether and methane, but not methanol, by cell suspensions of Methylococcus capsulatus and Methylosinus trichosporium. Evidence suggests that the involvement of metal-containing enzymatic systems in the initial step of oxidation of dimethyl ether and methane.
|
c35c0ef7-7a73-43f4-93c2-f2b1092ddeb0
| 0 |
Effect of colicin K on a membrane-associated, energy-linked function. The purpose of this work was in investigate the capability of cell extracts of Escherichia coli and E. coli treated with colicin K to catalyze the following energy-dependent reverse transhydrogenase reaction: NADP + NADH + ATP in equilibrium NADPH + NAD +ADP + Pi.
|
c35c0ef7-7a73-43f4-93c2-f2b1092ddeb0
| 1 |
Under anaerobic conditions this reaction requires the presence of a specific portion of the electron transport chain, a functional energy coupling system, including an adenosine triphosphatase, enzyme, and ATP as energy source. The ATP-linked reaction was partially inhibited in French press extracts of E. coli K-12 C600 cells that had been pretreated with colicin K but not in extracts from similarly treated cells of a colicin-tolerant mutant.
|
c35c0ef7-7a73-43f4-93c2-f2b1092ddeb0
| 2 |
Ultracentrifugation of extracts yielded particulate fractions competent in catalyzing the reaction; this reaction is substantially inhibited in fractions from colicin-treated cells. The extent of inhibition increased with increasing concentration of colicin. Supernatants also supported ATP-linked formation of NADPH, but this reaction was insensitive to the colicin effect.
|
c35c0ef7-7a73-43f4-93c2-f2b1092ddeb0
| 3 |
A comparison between the requirement of the reaction in supernatant and particulate fractions suggests that the reaction in the supernatant is different from the one inhibited by colicin. The ATP-hydrolyzing ability of particulate fractions from the control or treated bacteria was identical. Likewise, the electron transport chain was not affected by colicin treatment, as evidenced from lack of effect on NADH oxidase, succinic dehydrogenase, and NADPH-NAD transhydrogenase.
|
c35c0ef7-7a73-43f4-93c2-f2b1092ddeb0
| 4 |
It is concluded that colicin K interferes with the coupling of ATP the utilization of the intermediate for the ATP-linked transdehydrogenase reaction.
|
4bf3cbde-23c7-45fd-b023-83fbb696b111
| 0 |
Ribonucleic acid synthesized in meiotic cells of Saccharomyces cerevisiae: effect of culture medium pH. Pulse-labeled ribonucleic acid (RNA) was extracted from polysomes of sporulating cells of Saccharomyces cerevisiae and characterized in sucrose gradients and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Transfer RNA, ribosomal RNA, and heterodisperse RNA, presumed to be messenger RNA, were synthesized during a 20-min pulse at T4 and T6 when labeling was performed in sporulation medium adjusted to pH 6.0
|
4bf3cbde-23c7-45fd-b023-83fbb696b111
| 1 |
. Furthermore, ribosomal RNA was processed into functional ribosomes during the pulse. The specific activity of pulse-labeled RNA of cells labeled in sporulation medium where the pH was unadjusted at T4 (pH 7.8) and T9 (pH 8.6) was 20- to 50-fold lower than RNA from cells labeled at pH 6.0
|
4bf3cbde-23c7-45fd-b023-83fbb696b111
| 2 |
. The low specific activity resulted from a 50-fold reduction in uptake of labeled precursors when the medium pH was greater than 7.2. However, heterodisperse RNA ranging from 4-17S in size and transfer RNA were synthesized during the pulse at T4 (pH 7.8),but the low specific activity of ribosomal RNA prevented a thorough analysis of its synthesis.
|
4bf3cbde-23c7-45fd-b023-83fbb696b111
| 3 |
Cellular impermeability at T9 (pH 8.6) resulted in minimal uptake of label, and an analysis of pulse-labeled transcripts was impossible. A comparison of the percantage of polysomal material indicate, however, that these cells were at least as active in translation as cells pulse-labeled at pH 6.0
|
4bf3cbde-23c7-45fd-b023-83fbb696b111
| 4 |
.
|
5c810761-a34c-45e1-863a-b376541bc4cb
| 0 |
An enzyme common to histidine and aromatic amino acid biosynthesis in Bacillus subtilis. Two transaminases exist for tyrosine and phenylalanine synthesis in Bacillus subtilis. One enzyme is also responsible for the transamination of imidazole acetol phosphate to histidinol phosphate, an obligatory reaction in the synthesis of histidine. The gene involved in the synthesis of this enzyme lies in the middle of a cluster of genes, all of which are concerned with the synthesis of the aromatic amino acids.
|
5c810761-a34c-45e1-863a-b376541bc4cb
| 1 |
The other gene has not yet been mapped. Mutants have been isolated that lack one or the other enzyme activity. These mutants are prototrophic for tyrosine and phenylalanine. However, both classes of mutants are more sensitive than the wild-type strain to the phenylalanine analogue, fluorophenylalanine, suggesting that each of these mutants synthesizes less phenylalanine than does the wild-type strain.
|
5c810761-a34c-45e1-863a-b376541bc4cb
| 2 |
The two enzymes can be separated from one another by ion-exchange chromatography and glycerol-gradient centrifugation. The significance of the observation that an enzyme of histidine synthesis also plays a role in the synthesis of the aromatic acids is considered in light of cross-pathways regulation between the two pathways.
|
cbfa38a8-4f6e-4ac6-8737-d981ba40cc48
| 0 |
Regulation of Chorismate mutase-prephenate dehydratase and prephenate dehydrogenase from alcaligenes eutrophus. Highly purified enzymes from Alcaligenes eutrophus H 16 were used for kinetic studies. Chorismate mutase was feedback inhibited by phenylalanine. In the absence of the inhibitor, the double-reciprocal plot was linear, yielding a Km for chorismate of 0.2
|
cbfa38a8-4f6e-4ac6-8737-d981ba40cc48
| 1 |
mM. When phenylalanine was present, a pronounced deviation from the Michaelis-Menten hyperbola occurred. The Hill coefficient (n) was 1.7, and Hill plots of velocity versus inhibitor concentrations resulted in a value of n' = 2.3, indicating positive cooperativity. Chorismate mutase was also inhibited by prephenate, which caused downward double-reciprocal plots and a Hill coefficient of n = 0.7
|
cbfa38a8-4f6e-4ac6-8737-d981ba40cc48
| 2 |
, evidence for negative cooperativity. The pH optimum of chorismate mutase ranged from 7.8 to 8.2; its temperature optimum was 47 C. Prephenate dehydratase was competitively inhibited by phenylalanine and activated by tyrosine. Tyrosine stimulated its activity up to 10-fold and decreased the Km for prephenate, which was 0.67
|
cbfa38a8-4f6e-4ac6-8737-d981ba40cc48
| 3 |
mM without effectors. Tryptophan inhibited the enzyme competitively. Its inhibition constant (Ki = 23 muM) was almost 10-fold higher than that determined for phenylalanine (Ki = 2.6 muM). The pH optimum of prephenate dehydratase was pH 5.7; the temperature optimum was 48 C. Prephenate dehydrogenase was feedback inhibited by tyrosine.
|
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