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Biomedical subjects

G Berg

Publications and source records attributed to G Berg.

At least 217 records · Page 12Linked to original sources
PubMed1982

A method for concentrating viruses recovered from sewage sludges.

Buffered 10% beef extract eluates of primary, activated, and anaerobic mesophilically digested sludges were concentrated 20-fold by the Katzenelson organic flocculation procedure after diluting the beef extract in the eluates to a final concentration of 3%. The weighted mean recovery of virions from the concentrates was approximately 58% of the numbers present in the unconcentrated buffered 10% beef extract eluates. Flocculation of eluates that contained buffered 10% beef extract at times produced poor flocs. Application of the Katzenelson procedure to the diluted buffered 10% beef extract procedure for recovering virions from sludges permits an economy in the number of cell cultures required for assays of virions in beef extract eluates that is necessary in most laboratories.

Animals↗
PubMed1982

Effects of selective beta-adrenergic agonists on spontaneous contractions, cAMP levels and phosphodiesterase activity in myometrial strips from pregnant women treated with terbutaline.

The beta-adrenergic receptor function in terms of cAMP production and phosphodiesterase activity has been studied in myometrial strips taken from pregnant women at cesarean sections. The material consists of 10 patients treated with terbutaline for threatening premature delivery and an untreated control group of 10 patients. The basal levels of cAmP were lower and the cAMP production after receptor stimulation in vitro less in myometrial strips taken from terbutaline-treated women compared to the untreated control group. The phosphodiesterase activity was higher in myometrial strips taken from terbutaline-treated women, indicating a faster rate of degradation of cAMP in these women.

Cyclic AMP↗
PubMed1982

Dopaminergic modulation of aldosterone secretion in the rhesus monkey: evidence that dopamine affects the late pathway of aldosterone biosynthesis by inhibiting the conversion of corticosterone to 18-hydroxycorticosterone.

This study was designed to investigate the role of dopaminergic mechanisms in the control of aldosterone secretion. Six rhesus monkeys received metoclopramide (1.25 mg, iv), with 5% dextrose (vehicle) or with dopamine (4 micrograms/kg . min) infusions begun 60 min before the administration of the dopamine antagonists. Metoclopramide, in the presence of vehicle, increased plasma aldosterone concentrations from 4.5 +/- 0.5 ng/dl to a maximum of 26 +/- 4.1 ng/dl and PRL concentrations from 8.1 +/- 1.3 ng/ml to a maximum of 118.4 +/- 7.6 ng/ml. Dopamine infusion inhibited the aldosterone and PRL responses to metoclopramide. The administration of metoclopramide resulted in a rise in plasma 18-hydroxycorticosterone from 10.4 +/- 1.5 ng/dl to a maximum concentration of 41 +/- 4.2 ng/dl. The aldosterone and 18-hydroxycorticosterone responses displayed a parallel time course, with significant responses of both occurring 5 min after metoclopramide administration. Plasma concentrations of electrolytes, PRA, plasma cortisol, 11-deoxycorticosterone, corticosterone, and 18-hydroxy-11-deoxycorticosterone were not altered by metoclopramide. The results of this investigation demonstrate that aldosterone and PRL responses to metoclopramide are mediated by their antagonist activities at dopamine receptors. Rather than simply affecting secretion, dopaminergic mechanisms appear to modulate the late pathway of adrenal glomerulosa biosynthesis of aldosterone. A parallel time course of stimulation of 18-hydroxycorticosterone and aldosterone secretion, with no change in other aldosterone precursors, strongly suggests that dopamine modulates the activity of the glomerulosa 18-hydroxylase enzyme.

18-Hydroxycorticosterone↗
PubMed1982

Dopaminergic modulation of 18-hydroxycorticosterone secretion in man.

This study was designed to investigate mechanisms of dopaminergic control of corticosteroid secretion and to determine on which step in the aldosterone biosynthetic pathway dopamine exerts its effects. Plasma concentrations of electrolytes, PRA, plasma cortisol, 11-deoxycorticosterone, corticosterone (18-OHB), and 18-hydroxy-11-deoxycorticosterone were not altered by the iv administration of 10 mg metoclopramide in six healthy male volunteers. Metoclopramide increased plasma aldosterone from 6.3 +/- 0.9 ng/dl to a maximum of 23.0 +/- 3.4 ng/dl, plasma 18-OHB from 11.4 +/- 1.1 ng/dl to a maximum level of 42.8 +/- 4.4 ng/dl, and PRL from 9.9 +/- 1.4 ng/ml to a maximum of 71.0 +/- 5.5 ng/ml. The aldosterone and 18-OHB responses displayed a parallel time course, with significant responses of both occurring with 5 min after metoclopramide administration. Dopamine infusions (3 micrograms/kg . min) begun 60 min before the administration of metoclopramide markedly decreased the 18-OHB as well as the aldosterone and PRL responses to the dopamine antagonist. A parallel time course of stimulation of 18-OHB and aldosterone secretion with no change in other aldosterone precursors suggests that dopamine may modulate the activity of the glomerulosa 18-hydroxylase enzyme. Thus, rather than simply affecting aldosterone secretion, dopaminergic mechanisms appear to modulate the biosynthesis of aldosterone.

18-Hydroxycorticosterone↗
PubMed1982

Dopaminergic control of 18-hydroxycorticosterone responses to posture, isometric exercise, and diuretic administration in normal man.

This study investigates dopaminergic mechanisms involved in the control of corticosteroid secretion in man. The responses of plasma 18-hydroxycorticosterone (18-OHB) and aldosterone levels to upright posture and isometric handgrip exercise and furosemide administration as well as PRA and catecholamine responses to posture and exercise were evaluated in six normal subjects with and without bromocriptine (BEC) treatment. To evaluate the role of PRL suppression by BEC in affecting corticosteroid responses, we evaluated the effect of BEC on plasma 18-OHB and aldosterone responses to 20 mg furosemide in two subjects with autoimmune hypoprolactinemia. BEC (2.5 mg, three times a day for 4 days) markedly suppressed basal levels of 18-OHB, but not aldosterone, in the six normal subjects as well as the two subjects with autoimmune hypoprolactinemia. BEC also suppressed the 18-OHB and aldosterone responses to upright posture, isometric exercise, and furosemide administration without altering electrolytes, PRA, or plasma cortisol levels. Additionally, BEC suppressed basal levels of PRL, norepinephrine, and epinephrine as well as norepinephrine and blood pressure responses to upright posture and isometric exercise in the normal subjects. These results offer additional evidence that dopaminergic mechanisms modulate the secretion of 18-OHB and aldosterone, perhaps indirectly via inhibitory effects of dopaminergic pathways on catecholamine secretion.

18-Hydroxycorticosterone↗
PubMed1982

Is the relaxing effect of beta-adrenergic agonists on the human myometrium only transitory?

The beta-adrenergic receptor function in myometrial strips taken from pregnant women at cesarean section was studied. The material consisted of myometrial strips from 10 patients treated with terbutaline for threatening premature parturition and an untreated control group of 10 patients. The basal cAMP levels were lower and the cAMP production after receptor stimulation in vitro was less in myometrial strips taken from terbutaline-treated women than in the untreated control group. The phosphodiesterase activity was greater in myometrial strips taken from terbutaline-treated women, indicating a faster rate of degradation of cAMP in these women. Studies on the beta-adrenergic receptor function in leukocytes from venous blood samples during treatment with terbutaline for preterm labor demonstrated a gradual decline in receptor function, as shown by a successive reduction in cAMP production after stimulation with a beta-adrenergic agonist in vitro. The results presented may explain the merely temporary inhibitory effect on uterine contractions often obtained during treatment with beta-mimetics. It is suggested that intermittent usage or combined treatment with drugs inhibiting phosphodiesterase activity might improve the results in the treatment and prevention of premature birth.

Cyclic AMP↗
PubMed1982

[Changes in the spatial organization of DNA molecules induced by anthracycline antibiotics].

The optical properties of the mesophases modeling the condensed state of cell DNA molecules formed from the complexes of 7-anthracycline antibiotics with double-stranded low-molecular DNA and polynucleotides were studied. The parameters of the antibiotic binding to the DNA during formation of the mesophases (0.3 M NaCl, 150 mg/ml of polyethylene glycol) are presented. It was found that the CD mesophase spectrum formed from the complex of DNA-antibiotic was characterized by the presence of intensive negative bands in the region of absorption of the chromophores of both DNA and antibiotic. This is indicative of regular spiral organization of the DNA mesophase. Binding of the antibiotic to DNA and polynucleotides was accompanied by changing of the band negative mark (at definite levels of the DNA molecule filling with the antibiotic) in the CD mesophase spectrum to the positive one. It was shown that with respect to the mesophases formed from the complexes of DNA with iremycin and aclacinomycin A no changing in the band marks was observed. Consequently, antibiotics may be conditionally divided into 2 groups. The antibiotics of the first group induce changes in the spin direction of the DNA mesophase, while the antibiotics of the second group had no such effect. It was demonstrated that antibiotic binding with the AT-rich sequences induce more pronounced changes in the mesophase properties than that with the GC-rich sequences. Possible causes of the mark changing in the spin of the DNA mesophase during the DNA binding with antharcyclines are discussed. Biological significance of the phenomenon is still unclear.

Aclarubicin↗
PubMed1981

Immuno-electron-microscopic identification of O-antigen-bearing oligodendroglial cells in vitro.

Monoclonal antibodies to cell-surface antigens of oligodendrocytes (Sommer and Schachner 1980; Schachner et al. 1980) were used to identify this cell type by immuno-electron microscopy in monolayer cultures of fetal and early postnatal mouse cerebellum. The ultrastructural features of antigen-positive cells confirm that they are immature and mature oligodendrocytes, but not neurons, astrocytes or fibroblasts or fibroblast-like cells. Type I oligodendrocytes are the immature ones with a relatively large amount of moderately electron-lucent cytoplasm, clusters of ribosomes and complex networks of rough endoplasmic reticulum. Large numbers of mitochondria and microtubules, but not intermediate-sized filaments are seen in these cells. They comprise more than 90% of all 0-antigen-positive cells. Type II cells comprise only approximately 5% of all 0-antigen-positive cells. They are characterized by a limited amount of electron-dense cytoplasm, which appears more compact and granular than in type I cells. The rough endoplasmic reticulum is distributed evenly throughout the cytoplasm. Microtubules and mitochondria are present, but more difficult to distinguish due to the compactness of the cytoplasm. Type II cells display the more mature ultrastructural features of oligodendrocytes.

Animals↗
PubMed1981

A method for recovering viruses from sludges.

Primary, activated, and anaerobic mesophilically digested sludges were salted with MgCl2 (divalent cations) or AlCl3 (trivalent cations) and acidified to bind indigenous unadsorbed virions to the sludge solids; the sludges were centrifuged, and the adsorbed virions were eluted from the solids with buffered 10% beef extract. The elution yields with this procedure were superior to those obtained from sludges that had been salted or acidified only. Homogenization of sludges prior to other treatment did not increase the numbers of virions recovered.

Aluminum↗
PubMed1981

Operated hypospadiacs: late follow-up. Social, sexual, and psychological adaptation.

Thirty-four adult men operated upon for hypospadias in childhood and 36 controls were examined by interview and psychological tests. During childhood hypospadiacs had enuresis, showed shyness, and were mobbed more often than controls. Hypospadiac's sexual debut, but not the first ejaculation, was delayed. Most hypospadiacs had a satisfactory sexual life, albeit restricted to fewer partners. Socially, hypospadiacs showed normal adjustment but had less qualified professions than controls. Hypospadiacs showed a more doubtful sexual identity and greater castration anxiety combined with lesser utilization of cognitive and emotional resources than controls. Early operated hypospadiacs had a more infantile sexual identity than those operated later (less than 5 yr).

Adaptation, Psychological↗
PubMed1981

Mineralocorticoid response to low dose adrenocorticotropin infusion.

The adrenocorticoid responses to low dose ACTH of plasma aldosterone (aldo), corticosterone (B), 11-deoxycorticosterone (DOC), 18-hydroxycorticosterone (18-OHB), 18-hydroxycorticosterone (18-OH-DOC), and cortisol (F) were compared. Alpha ACTH-)1-24) was infused beginning at 0800 h at increasing rates from 12.5-200 mIU/30 min in supine normal subjects under the following conditions: 1) regular Na (120 meq) diet, 2) low Na (10 meq) diet, 3) dexamethasone preadministration (0.5 mg every 6 h for 48 h), and 4) night study (2000 h; 120 meq Na intake). Plasma 18-OH-DOC and B demonstrated quantitatively the greatest responses to ACTH, while DOC and 18-OHB responses were intermediate. Increments in aldo and F were least after ACTH and were maximum at 50 mIU/30 min ACTH, whereas other corticosteroids demonstrated linear responses up to infusion rates of 200 mIU/30 min. All corticosteroids, however, were similar in their threshold responses to ACTH which were at infusion rates of approximately 7-9 mIU/30 min. Na restriction enhanced aldo and 18-OHB responses to ACTH 2- to 3-fold but did not alter the other corticosteroid responses. Dexamethasone pretreatment augmented aldo, 18-OHB, and F responses but did not change the responsitivity of the other corticosteroids to ACTH. Adrenal corticosteroid responses to ACTH were not significantly different between 0800 and 2000 h in subjects on 120-meq Na intake. Thus, corticosteroids show markedly different responses to physiological doses of ACTH, which may have more importance in their regulation than heretofore proposed. Dexamethasone pretreatment enhances aldo, 18-OHB, and F responses to ACTH but does not affect the responses of other corticosteroids. Contrary to reports in experimental animals, corticosteroid responses to ACTH in man do not differ from day to night.

18-Hydroxycorticosterone↗
PubMed1980

The uricosuric action of protein in man.

In 8 subjects, the oral protein supply is modified in periods of 3 days each. With increasing protein intake, a decrease of the serum uric acid levels results as well as a significant increase in uric acid excretion and uric acid clearance. On the basis of the data obtained, it may be assumed that protein has a uricosuric action.

Dietary Proteins↗
PubMed1980

The structure of newly synthesized intracellular thyroglobulin molecules.

Thyroglobulin molecules from normal rats and rats treated with propylthiouracil (PTU) were studied in the electron microscope by the negative staining technique. Intracellular molecules were prepared from exocytotic vesicles, and extracellular molecules from the high-speed centrifugation supernatant. In accord with our previous findings, extracellular thyroglobulin molecules from normal glands had an ovoid conformation, whereas extracellular molecules from PTU-treated glands had a different, cylindrical shape. Thyroglobulin molecules from exocytotic vesicles were of the ovoid variety in normal as well as in PTU-exposed thyroids. Two interpretations are discussed. One would be that PTU exerts a non-physiological effect on ovoid molecules in connection with exocytosis of thyroglobulin. The other interpretation is that thyroglobulin molecules normally undergo 2 transformations (ovoid-cylinder-ovoid) during the process of exocytosis; PTU would inhibit the second transformation and cause accumulation of cylinders in the colloid.

Animals↗