Search PubMed⌕ Search

Biomedical subjects

W Ernst

Publications and source records attributed to W Ernst.

At least 19 recordsLinked to original sources
PubMed1991

The toxicity of chlorothalonil to aquatic fauna and the impact of its operational use on a pond ecosystem.

Chlorothalonil is a fungicide whose heavy use in eastern Canada gives it the potential for significant aquatic contamination. Laboratory bioassays and field treatments of a pond system were undertaken to determine the toxic effects of chlorothalonil on aquatic fauna. The 96-h LC50 of technical chlorothalonil for rainbow trout (Oncorhynchus mykiss) was 76 micrograms/L and was not significantly different (p less than 0.05) from that of the formulated product (Bravo 500). The 96-h LC50 of Bravo 500 for blue mussels (Mytilus edulis) and clams (Mya arenaria) was 5.9 mg/L and 35.0 mg/L respectively, while its 48-h LC50 to Daphnia magna was between 130 micrograms/L and 200 micrograms/L. Chlorothalonil exposure of Daphnia to concentrations as low as 32 micrograms/L significantly (p less than 0.05) increased the time to production of first young, but there were no delayed effects on number of young produced or growth at concentrations of 180 micrograms/L or less. Chlorothalonil was initially accumulated by blue mussels to concentrations approximately ten times greater than exposure concentrations; however, tissue concentrations returned to the same level as exposure concentrations within 96 h. Spraying of ponds resulted in mortality of caged water boatmen (Sigara alternata) and threespine stickleback (Gasterosteus aculeatus) which could be related to chlorothalonil exposure, however, caddisfly larvae (Limnephilus sp.), freshwater clams (Psidium sp.), water beetles (Haliplus sp.), scud (Gamarus spp.) and midge larvae (Chironomidae) did not suffer substantial chlorothalonil-induced mortality. Changes in endemic benthic invertebrate abundance after sprays were not remarkable or related to treatment. Faunal impacts in the pond were generally of a smaller magnitude than were predicted by bioassay results.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

High density microcarrier culture with a new device which allows oxygenation and perfusion of microcarrier cultures.

A novel system useful for aeration and cell retention in continuous perfused microcarrier cultures is described. The system is based on a vibrating cage that separates cells and microcarriers from the oxygenation chamber and allows gas bubble free oxygen transfer. In the cultivation of monkey kidney cells (VERO) on gelatin coated microcarriers, using different concentrations (5, 10 and 15 g Cytodex 3/liter) cell densities up to 10(7) cells per ml were obtained. The described system is scaleable.

Animals↗
PubMed1989

[Immunohistochemical analysis of graft rejection in formalin fixed kidney biopsies].

One hundred and five formalin fixed renal allograft biopsies with a graft survival of more than 12 months have been examined by histological and immunohistochemical methods. 51 cases of vascular and 41 cases of tubulointerstitial allograft rejections were diagnosed by conventional light microscopy. 13 cases showed a combined type of rejection. The vascular and the interstitial type contain on average 64 respectively 79 CD 45 positive cells/mm2 surface of section. A mean of 70 cells/mm2 has been calculated for the combined type of rejection. The corresponding mean values of MT 1 positive T-lymphocytes are 46 in the vascular type, 52 in the combined type and 60 cells/mm2 in the tubulointerstitial type of allograft rejection. Apparently because of the great ranges there are no statistically significant differences between the observations in the different types of rejection. His equal for the concentration of Mac 387 positive macrophages and as well for the content of L26 positive B-lymphocytes in the different types of rejection. The concentrations of HLA-DR expressing cells in the interstitium are determined with a monoclonal anti-HLA-DR antibody, which detects a fixation resistant epitope of the DR-molecule. There is an average of DR positive cells/mm2 of 79 in vascular and 107 in interstitial rejection. The combined type of rejection contains 86 cell/mm2 on average, so that there is a statistically significant positive correlation, if you will order the observations in sequence of vascular, combined and interstitial type of rejection. In this case the observations of interstitial and vascular rejections differ statistically significant as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Surface↗
PubMed1976

Increased plasma noradrenaline concentrations in essential hypertension and their decrease after long-term treatment with a beta-receptor-blocking agent (prindolol).

1. Plasma noradrenaline was measured in fifty-nine patients with mild to severe essential hypertension and in fifteen normotensive control subjects under basal and orthostatic conditions. 2. In patients with essential hypertension mean plasma noradrenaline concentrations were significantly higher than in control subjects under basal and orthostatic conditions. 3. In patients with essential hypertension basal diastolic blood pressure correlated closely with the corresponding plasma noradrenaline concentrations. 4. Long-term treatment with prindolol of patients with essential hypertension led to a significant fall in diastolic and systolic blood pressure and heart rate and to a significant decrease in plasma noradrenaline concentrations under basal and orthostatic conditions. 5. The adrenergic response to upright posture, reflected by an increase in plasma noradrenaline, was not abolished by prindolol. 6. It is concluded that the anti-hypertensive effect of prindolol in patients with essential hypertension is at least partially mediated by a decrease of sympathetic nervous activity.

Adolescent↗
PubMed1976

Plasma noradrenaline levels in regular haemodialysis patients.

Plasma concentrations of noradrenaline (NA), adrenaline (A) and renin (R) were measured in 29 regular haemodialysis patients (RHP) [13 normotensive, 10 hypertensive, 6 binephrectomised] and in 15 healthy control subjects (C) under various physiological conditions: supine-standing-walking. RHP had significant higher plasma levels of noradrenaline and adrenaline in the mean than C. All RHP responded to passive orthostasis with a significant increase in diastolic blood pressure, heart rate and plasma NA. In contrast to C, plasma NA did not drop after two hours of active orthostasis. Hypertensive RHP had significant higher plasma concentrations of R and A than normotensives. It is concluded that the sympathetic nervous system (SNS) plays a minor role in hypertensive blood pressure regulation of RHP. The adequate response to passive orthostasis in RHP with regard to diastolic blood pressure, heart rate and plasma NA indicates and intact function of the SNS under this condition. Hypertension in RHP not controllable by salt and volume depletion can be attributed to elevated levels of R, which in turn may stimulate adrenaline release from the adrenals. The mechanisms responsible for the elevated levels of circulating catecholamines remain unclear: an inhibition of re-uptake, disturbances in enzymatic metabolism or/and abolished renal clearance are suggested.

Adult↗