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Biomedical subjects

J A Janssen

Publications and source records attributed to J A Janssen.

12 recordsLinked to original sources
PubMed1992

Comparison of sublethal and lethal criteria for nine different chemicals in standardized toxicity tests using the earthworm Eisenia andrei.

In this study, the effects of nine different chemicals on the survival, growth, and reproduction of the earthworm species Eisenia andrei were determined using a recently developed method. Earthworms were exposed for 3 weeks to the test chemicals in an artificial soil substrate. Additional data on the acute toxicity of these chemicals were derived from the literature. For some chemicals, cocoon production was the most sensitive parameter (cadmium, chromium, paraquat, fentin, benomyl, phenmedipham), while for others cocoon hatchability was most sensitive (pentachlorophenol, parathion, carbendazim). In the case of parathion, growth of the worms seemed to be even more sensitive than reproduction. As an overall parameter for the effect on earthworm reproduction, the total number of juveniles produced per worm appeared to be a useful parameter. Differences between (acute) LC50 values and the lowest NOEC value for effects on growth and reproduction were different for each chemical. Difference was greatest for cadmium (a factor of greater than 100) and smallest for fentin, benomyl, and pentachlorophenol (a factor of 5-6).

Animals↗
PubMed1992

Plasma prorenin as an early marker of microvascular disease in patients with diabetes mellitus.

To test the hypothesis that a high plasma prorenin can be used as an early marker of microvascular complications in patients with diabetes mellitus plasma prorenin was measured in 44 patients with urinary albumin excretion between 30 and 300 mg/24 h (microalbuminuria) and 120 patients with urinary albumin excretion below 30 mg/24 h (normoalbuminuria). A high plasma prorenin was associated with diabetic retinopathy, particularly the proliferative type, serum creatinine and the 24 h urinary albumin excretion rate. Plasma prorenin was not correlated with age, duration of diabetes, glycosylated hemoglobin, blood glucose, and blood pressure. The association between elevated plasma prorenin and retinopathy remained significant after adjustment for serum creatinine and albumin excretion. Independent of the presence or absence of microalbuminuria, the mean plasma level of prorenin was not above normal in patients without retinopathy and was 2 to 3 times normal in patients with proliferative retinopathy. Thus retinopathy appears to be an important determinant of abnormally high plasma prorenin. Angiotensin converting enzyme (ACE) was elevated in the patients with diabetes mellitus as compared to control subjects but the plasma levels of ACE in diabetics with normoalbuminuria was not significantly different from the group with microalbuminuria. Plasma prorenin was not associated with ACE. A plasma level of prorenin of 225 mU/L had a sensitivity of 0.84 and a specificity of 0.82 for detecting the presence of microalbuminuria.

Adult↗
PubMed1991

Bronchial asthma improved after removal of a phaeochromocytoma.

It is uncommon for bronchial asthma to be a symptom of phaeochromocytoma. We describe a patient with a phaeochromocytoma who presented with worsening of her asthma and persistent dyspnoea between attacks. She had markedly elevated levels of catecholamines. After surgical resection of the phaeochromocytoma there was a lasting improvement of the bronchial asthma. We hypothesize that worsening of bronchial asthma in phaeochromocytoma patients may be due to catecholamine-induced deterioration of asthma.

Adrenal Gland Neoplasms↗
PubMed1989

[Hypercalcemia in sarcoidosis].

In a 56-year-old man hypercalcaemia and kidney function impairment were the presenting symptoms of sarcoidosis. The diagnosis was supported by the finding of elevated 1,25-dihydroxyvitamin D levels and of a cluster of epithelioid macrophages in aspirated bone marrow. By exclusion of other granulomatous diseases and a favourable reaction of the hypercalcaemia and renal function to treatment with prednisone the diagnosis was confirmed. The relationship between the autonomous extrarenal production of 1,25-dihydroxyvitamin D and the hypercalcaemia is discussed.

Calcitriol↗
PubMed1989

[The effect of immunoscintigraphy with monoclonal antibodies on assays of hormones and tumor markers. This is not the end of the matter!].

The use of monoclonal antibodies in medicine for in-vivo diagnostic methods and for therapeutic purposes will increase in the future. Although monoclonal antibodies possess a high specificity, the animal origin of these antibodies remains a problem. Repeated administration of animal monoclonal antibodies (in vivo) may induce the formation of human antibodies against these monoclonal antibodies. Because animal monoclonal antibodies are also used in laboratory assays (in vitro), the presence of human antibodies against these animal monoclonal antibodies may cause spuriously elevated or depressed results of these assays. The clinician should be alert to this possibility. A case history is presented to demonstrate the problem.

Aged↗
PubMed1987

Study of the molecular mechanism of decreased liver synthesis of albumin in inflammation.

Hypoalbuminemia in inflammatory disorders is not an infrequent finding. However, little is known about albumin synthesis in these patients. In the present study we have measured the albumin synthesis in four patients with inflammatory diseases using the [14C]carbonate technique. Because inflammation causes a decreased albumin synthesis and this decreased synthesis could not be related to a reduced amino acid supply, we have also examined the possible molecular mechanisms of reduced albumin synthesis during inflammation using in vivo and in vitro experiments in rats. In rats with turpentine-induced inflammation, serum albumin concentration and liver albumin mRNa level were markedly decreased. These changes could not be reproduced by administration of fibrinogen-, or fibrin-degradation products, or several hormones, such as corticosteroids, growth hormone, and adrenaline. However, monocytic products, especially interleukin 1, postulated to be important mediators of the inflammatory response, reduced albumin synthesis and liver albumin messenger RNA content but not total protein synthesis in rats in vivo and in primary cultures of rat hepatocytes. These findings suggest that monocytic products play an important role in reduced albumin synthesis during inflammation.

Adult↗
PubMedDate not supplied

Politics of AIDS.

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Acquired Immunodeficiency Syndrome↗