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Biomedical subjects

G Peters

Publications and source records attributed to G Peters.

At least 325 records · Page 18Linked to original sources
PubMed1979

[Antibacterial in-vitro activity of pipemidic acid and nalidixic acid (author's transl)].

The in-vitro activity of nalidixic acid and pipemidic acid was investigated in a combined study in 450 freshly isolated bacterial strains using the agar dilution test. Gram-positive cocci were resistant to both substances except for a few pipemidic acid sensitive staphylococci. Both substances had good antibacterial activity in the gram-negative spectrum. However, the MIC values of pipemidic acid were generally clearly lower than those of nalidixic acid. Only pipemidic acid showed activity against Pseudomonas aeruginosa. Thus the in-vitro results showed that pipemidic acid has clear-cut and valuable advantages for the treatment of urinary tract infections when compared with nalidixic acid.

Anti-Bacterial Agents↗
PubMed1979

The role of circulating renin in drinking in response to isoprenaline.

1. In nephrectomized rats, S.C. (0.12 mg. kg body wt.(-1)) or intracerebroventricular (I.C.V.: 0.03 mg. kg(-1)), isoprenaline failed to elicit drinking. However, when preceded (5-20 min) by a non-dipsogenic dose of I.V. pig renin, S.C. isoprenaline induced a marked, and I.C.V. isoprenaline a smaller drinking response. 2 hr after I.V. renin, S.C. isoprenaline no longer caused drinking.2. Pig renin did not enhance drinking in response to 0.12 mg. kg(-1) isoprenaline S.C. in intact or sham-operated rats.3. Isoprenaline (0.12 mg. kg body wt.(-1), S.C.) caused a larger fall of blood pressure in unanaesthetized nephrectomized than in intact unanaesthetized rats, but it was not the resulting hypotension that interfered with the nephrectomized rats' ability to drink, since intact rats with similar falls in blood pressure drank avidly in response to large doses of isoprenaline.4. Since the rate of inactivation of pig renin in nephrectomized rats was not modified by isoprenaline, drinking in nephrectomized animals in response to renin+isoprenaline was not attributable to increased plasma renin levels.5. Since isoprenaline induces drinking in the presence of circulating renin, but in the absence of renin release from kidneys, renin plays a permissive role in isoprenaline-induced drinking. Angiotensin and isoprenaline may interact at the level of intracranial receptors.

Animals↗
PubMed1979

RNA-directed DNA synthesis in Moloney murine leukemia virus: interaction between the primer tRNA and the genome RNA.

Initiation of RNA-directed DNA synthesis in virions of Moloney murine leukemia virus requires a cellular tRNAPro as primer. The site(s) on the Moloney murine leukemia virus genome RNA at which functional primer molecules are bound and at which purified tRNAPro hybridizes has been located near (within 20%) the 5' end of the genome. A relatively stable duplex (temperature at which 50% dissociation has occurred, 76 degrees C) is formed between the amino acid acceptor stem of the tRNAPro and a complementary sequence in the Moloney murine leukemia virus 35S RNA. The interaction involves 19 base pairs, extending from the penultimate nucleotide at the 3' end of the tRNAPro but apparently not including the 3'-terminal adenosine residue. In most respects, the interaction between primer and template in Moloney murine leukemia virus parallels the situation in the avian leukosis-sarcoma viruses.

Animals↗
PubMed1978

Temperature-dependent growth and regression of epidermal tumors in the european eel (Anguilla anguilla L.).

The population of eels in the Elbe estuary showed a high rate of affliction with epidermal papillomas. Distinct seasonal fluctuations were observed in the frequency of occurrence and tumor size. In spring and autumn, the frequency was low, and the tumors were relatively small. In summer, the tumors reached a maximum in both frequency and size. A distinct influence of water temperature on tumor growth was demonstrated experimentally. Summer temperatures of 15--22 degrees C caused very rapid growth. In the field and in the laboratory, the tumors exhibited a fourfold increase in average volume within 3 months. These fast-growing neoplasms had certain relatively uniform histologic features. The tumor cells were separated by wide intercellular spaces. The basal layer was composed of tall columnar cells, while the surface layer was composed of slightly flattened cells. Winter water temperatures (5--10 degrees C) inhibited tumor growth and even caused tumor regression. In 3 months, the papillomas shrank to half of their initial size. Histologic and ultrastructural examinations revealed signs of tissue degeneration: necrobiotic processes in the epidermal region, cellular and nuclear polymorphisms, dissolution of membranes, loss of cell integrity, and loosening and reduction in size of the basal cell layer.

Anguilla↗
PubMed1978

Interactions between volume expansion or diuretics and compensatory adaptation.

Glomerular filtration rate, urine flow, and Na excretion were measured 3--4 h after unilateral nephrectomy (1/2Nex) or sham operation in unanesthetized rats infused with isotonic saline (0.05--0.75 ml/min) and additionally injected with acetazolamind (20 mg/kg i.p.) or furosemide (5 mg/kg i.p., or 0.2 mg/kg i.v., or 2.0 mg/kg i.v.) or with both agents. Glomerular filtration rate of unilaterally nephrectomized rats averaged 50% of controls. Under all experimental conditions investigated, absolute water and Na excretions were similar in 1/2Nex and sham-operated rats. The fractional excretion (FE) of water and Na was increased 1.5- to 2.2-fold in 1/2Nex animals. The diuretic effects of volume expansion, of the two diuretic agents, and of contralateral nephrectomy consistently were additive. The "compensatory" increase of FESa following contralateral nephrectomy entailed a proportional increase of the diuretic effects of agents given subsequently. Urinary furosemide excretion 15 min after intravenous injection in unilaterally nephrectomized rats was smaller than in controls. The additivity of the diuretic effects of contralateral nephrectomy ("compensatory adaptation") and volume expansion and/or diuretic agents appears to be partly explained by different sites of action.

Adaptation, Physiological↗
PubMed1978

Activity spectrum of micrococcal and staphylococcal phages.

The activity spectrum of 4 polyvalent Staph. aureus-phages, of 22 phages from coagulase negative staphylococci and of 64 micrococcal phages was established on 20 Staph. aureus-strains, 116 coagulase-negative staphylococci and 142 micrococci. Staphylococcal phages showed to be only active on strains of the genus Staphylococcus and on cocci related to this genus. Micrococcal phages on the other hand lysed only micrococci.

Bacteriophage Typing↗
PubMed1978

[Neuropathological aspects of chronic diseases].

Practically all diseases of bodily organs may lead to quantitatively and qualitatively differing alterations of the central and periphal nervous system. These are connected to the basic disease on one side, to compications on the other. The preliminary condition for the appearance of encephalopathies following bodily diseases lies mostly in a disturbance of the blood-brain and blood-liquor barrier. No close correlation exists usually between psychiatric and nervous syndromes and pathomorphological findings. However, the findings are often characteristical, although not specifical. Especially the findings in uraemia, liver diseases, rheumatic and so-called pararheumatic diseases (collagenoses) are discussed.

Blood-Brain Barrier↗
PubMed1978

Serological investigations on the polylysogeny of micrococci.

Specific antisera against 11 micrococcal phages could be produced by immunization of rabbits. Using the neutralisation test all antisera were tested against their homologous and heterologous phages. The corresponding K-values were calculated. It could be demonstrated that phages coming from the same micrococcal donor strain can be of different genetical relationship. Therefore it was concluded that micrococci can be not only lysogenic but also polylysogenic.

Bacteriophages↗
PubMed1977

Geographic variations in tumor prevalence among marine fish populations.

A global epidemiological study on the frequency of skin papillomas among various flatfish species (Pleuronectids), papillomas of eels and the virus induced lymphocystis disease has revealed particular distribution patterns. Skin papillomas are prevalent among at least 20 flatfish species of the northern Pacific Ocean, Bering Sea, Sea of Okhotsk, and Japan Sea but appear to be absent from the Atlantic, North Sea, and the Caribbean Sea. The opposite is found for lymphocystis, which is common among flatfish species of the Atlantic shores of Europe and North America. Similarly the skin papillomas of eels are restricted to relatively small region along the European coast extending from the Baltic countries to Denmark, Germany and Holland. Superimposed on this global distribution pattern are local variations in tumor prevalences which can vary from about 58% to 0.01%. The geographic distribution pattern points to the existence of areas around the globe in which flatfish or eels are able to develop skin papillomas. Outside these areas of "potential skin papilloma risk," flatfish and eel populations are not afflicted with papillomas even if they inhabit estuaries or rivers with a high man-made or naturally-occurring pollution.

Animals↗
PubMed1977

Low-molecular-weight RNAs of Moloney murine leukemia virus: identification of the primer for RNA-directed DNA synthesis.

The small RNAs of Moloney murine leukemia virus (M-MuLV) were fractionated into at least 15 species by two-dimensional polyacrylamide gel electrophoresis. The pattern of small RNAs is significantly different from that of Rous sarcoma virus. A subset of the virion small RNAs is associated with the genome RNA in the 70S complex. One of the associated molecules, a cellular tRNA, is tightly bound to the genome RNA and serves as the major primer for M-MuLV RNA-directed DNA synthesis in vitro.

DNA, Viral↗
PubMed1976

[Physiological and pathological aging of the brain].

Also in the old age, the capability for a meaningful arrangement of life is dependent on the functional integrity of the brain. The processes of senile involution occurring physiologically do not exclude such a possibility. In normal aging, the reduction in the number of nerve cells and dendritic spines is small compared to pathological aging. There are no indications for transitions between normal and pathological aging. Senile dementia is an optionally occurring disease requiring an endogenous component for its manifestation. The psychic peculiarities occurring in the course of normal aging result mainly from environmental factors (i.e. psychic and social injuries). They need multidimentional treatment.

Adjustment Disorders↗
PubMed1976

[Urinary mercury excretion in professional users of an antiseptic soap containing 0,04% phenylmercury borate].

Concentrations of mercury and of creatinine were measured under blind conditions in 84 samples of urine from 48 regularly using a liquid soap containing 0.04% phenylmercuric borate plus 3% hexachlorophene for hand disinfection ("users"), and in 138 urine samples of 80 subjects disinfecting their hands with a soap containing only hexachlorophene ("controls"). The concentration of mercury in the urine of users was 27+/-3 mug/1 (mean +/- SE), and in controls 8+/-1 mug/1; calculated total 24 h urinary mercury excretions were 27+/-2 mug/24 h users and 9+/-1 mug/24 h in controls. Women excreted slightly more mercury than men both in the user group and the control group. In both controls and users from whom a second urine sample was obtained after a 2-week interval the concentration of mercury was consistently lower in the second sample. No correlation was found between urinary excretion of mercury and frequency of handwashings or reported intake of mercury-containing food. No difference was found in the numbers of different types of urinary cells or urine pH as between users and controls. It is concluded 1) that regular hand disinfection with a liquid soap containing 0.04% phenylmercuric borate enhanced urinary excretion of mercury indicating an increase in total daily absorption of 30-100 mug Hg/24 h, 2) that the absorption of mercury from the phenylmercuric borate-containing soap occurred partly by transfer from the hands to the oral cavity, 3) that, though nontoxic in themselves, the additional amounts of mercury absorbed through the use of mercury contained in skin disinfectants are potentially dangerous due to as yet unknown interactions with other toxic or pathogenic factors.

Borates↗
PubMed1976

Renal excretion of uric acid in the rat: a micropuncture and microperfusion study.

Free-flow micropuncture experiments were done in rats of three strains infused with small amounts of urate [plasma urate (P urate) = 95 +/- 8 muM]. Urate concentrations in tubular fluid were measured by an accurate chemical fluorometric ultramicromethod. In fluid from surface glomeruli, the glomerular fluid-to-plasma urate ratio [GF/P) urate] was 0.99 +/- 0.03 (n=11), i.e., lower than expected for total ultrafiltrability of plasma urate. Along proximal convolutions, net reabsorption of 55% of filtered urate was demonstrated. Small amounts of urate may have been reabsorbed between late proximal and early distal sites. Net transepithelial movements of urate did not occur in distal tubules or collecting ducts. In microperfusion experiments on proximal tubules, both a reabsorptive flow of urate (loss of perfused [2-14C]urate) and a secretory flow (entrance of cold urate into perfusate) of the same order of magnitude were demonstrated. Neither flow was influenced by simultaneous water movements. Microperfusion of Henle's loops indicated a significant but very small net reabsorption.

Aminohippuric Acids↗