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Biomedical subjects

K Hoffmann

Publications and source records attributed to K Hoffmann.

At least 307 records · Page 17Linked to original sources
PubMed1982

Enzyme activities and protein concentration in the intraocular fluids of ten mammals.

An attempt was made to establish normal values for the total protein concentrations and the enzyme activities of LDH, MDH and PGI in the intraocular fluids of rats, guinea pigs, rabbits, cats, dogs, sheep, cattle, pigs, horses and humans. Remarkably little species differences were noted in 9 of the 10 mammals with vitreal enzyme activities falling into a narrow range between 8.4 U/l (PGI, horse) and 92.4 U/l (MDH, guinea pig). All species obeyed the sequence aqueous less than vitreous less than serum with exception of the rat, where vitreous activities surpassed serum at least two-fold. The very low enzyme activities in the aqueous and vitreous humors demand special precautions against contaminations which can either derive from post-mortem storage or inadequate sampling procedures. Conversely elevated enzyme activities could be used as probes for pathological processes or as a check for a clean preparation.

Animals↗
PubMed1981

Two-month follow-up of the changes in vitreal constituents after argon laser coagulation of the retina in rabbits.

The response of the vitreous after panretinal argon laser photocoagulation was followed over a period of 60 days. Two phases can be discerned. An an immediate reaction to the disturbance of the blood-retinal barrier at the site of the pigment epithelium the total protein content and malate dehydrogenase activity rise sharply within 3 days, 4- to 5-fold above a normal. The more protracted increase of lysosomal enzyme activities which reach their peak heigh after 14 days only, can be attributed to the action and proliferation of phagocytic cells. 2 months after treatment all parameters have returned to their normal levels.

Acetylcholinesterase↗
PubMed1980

Acute cardiovascular reactions after cigarette smoking.

The effect of cigarette smoking on the cardiovascular system was determined in the following way: Two cigarettes of relatively high (1.54 mg) and very low (0.08 mg) nicotine content were smoked and compared to sham smoking. After inhalation under standardized conditions there was a relatively high increase of the plasma nicotine levels and a subsequent exponential decrease. Two hours after smoking the levels were still elevated. After 2 low nicotine cigarettes there was a significant small short-term increase. The changes of the pulse rate were directly related to the nicotine levels and the pulse pressure transit time from the heart to the calf and the digital blood flow was indirectly related to them. The regulation of these parameters is exactly related with the nicotine levels probably through the release of catecholamines. The cardiovascular reactions after smoking may indicate the additional myocardial work load after cigarettes of different nicotine content.

Adult↗
PubMed1980

[Enophthalmos with limitation of bulbar motility as a rare clinical symptom of metastasizing carcinoma of the breast (author's transl)].

A 57-year-old woman presented with a ptosis of her left eye four weeks prior to surgery for scirrhous carcinoma of the breast. Six months later she had blurred vision in her left eye, and double vision occurred three months subsequently. The diagnosis was enophthalmus and ophthalmoplegia. The suspected diagnosis of a distant metastasis of the scirrhous carcinoma of the breast was confirmed by biopsy. The orbital symptoms were a rare first sign not only of a metastatic process, but also of the carcinoma itself.

Adenocarcinoma, Scirrhous↗
PubMed1980

[Diabetic retinitis in children and adolescents and its relationship to regulation (author's transl)].

Ninety diabetics between eight and 18 years of age, whose diabetes is controlled very carefully, were examined by fluorescein angiography in order to investigate the incidence and severity of diabetic retinitis. At 21% the percentage was markedly lower than that found by other workers, who control metabolism much less stringently. Also the severity of the retinitis was found to be much less pronounced in our examinations than in those carried out by other groups. Our results show that besides disposition the control of diabetes plays a decisive role in the development of diabetic retinitis in young diabetics.

Adolescent↗
PubMed1980

Theophylline reduces the activity of cerebroside-sulfotransferase, a key enzyme in myelination, in cell cultures from newborn mouse brain.

Theophylline, a drug used in neonatology for the treatment of apnea, affects cholesterol synthesis if administered in concentrations of 10(-4) M (a concentration found in serum of treated patients) for 24 hr to dissociated brain cell cultures. The rate-limiting enzyme of cholesterol synthesis, beta-hydroxy-beta-methylglutaryl-coenzyme A reductase (EC 1.1.1.34), is lowered to 45% 48 hr after removal of theophylline. At the same time, cholesterol content of the cells is lowered to 73%. Inasmuch as the phospholipid content of the cells remains stable, the treatment changes the cholesterol phospholipid ratio. Concomitant to this effect, the activity of cerebroside-sulfotransferase (EC 2.8.2.11) is lowered to 60% of control values. We postulate that these two effects are linked to each other by means of modulation of the cerebroside-sulfotransferase activity by membrane lipids.

Animals↗
PubMed1979

Photoperiodic effects in the Djungarian hamster: one minute of light during darktime mimics influence of long photoperiods on testicular recrudescence, body weight and pelage colour.

In male Djungarian hamsters (Phodopus sungorus) short photoperiods (L/D 8/16) with additional 1- or 5-min light-pulses 8 h after light-off were as effective as long photoperiods (L/D 16/8) in stimulating testicular recrudescence, increase in body weight and moult into summer pelage. The results are discussed with regard to the hypothesis that the pattern of melatonin release from the pineal gland is important in mediating photoperiodic effects in mammals.

Animals↗
PubMed1979

Influence of reduced cholesterol synthesis on the activity of cerebroside sulfotransferase in cultured glioblastoma cells treated with estradiol.

Cultured glioblastoma cells were inoculated with estradiol in concentrations of 0.5--10 microliter/ml medium in order to check the effect of this hormone on the activity of cerebroside sulfotransferase, an enzyme whose activity is strongly related to myelination. Thereby we could show that the cerebroside-sulfotransferase activity increases to a value of 200% of normal. Concomitant to this effect, the cholesterol content of the membrane bearing cerebroside sulfotransferase activity decreases to 60% of normal. The effect is fully reversible: after 48 h, cholesterol synthesis as well as cerebroside sulfotransferase activity reach normal values again. We suggest that cerebroside sulfotransferase activity is modulated by the changing cholesterol/phospholipid ratio in the cells during the inoculation period.

Animals↗