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Biomedical subjects

H J Kramer

Publications and source records attributed to H J Kramer.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Biotransformation rates of Ugilec 141 (tetrachlorobenzyltoluenes) in rat and trout microsomes.

In vitro biotransformation rates of tetrachlorobenzyltoluene (TCBT) isomers 3,3',4,4'-Cl4-2-Me (TCBT 87), 3,3',4,4'-Cl4-5-Me (TCBT 88), and 3,3',4',5-Cl4-4-Me (TCBT 94) were determined using trout and rat hepatic microsomes. The disappearance of the TCBTs from the in vitro system followed first-order kinetics. The estimated biotransformation constants (k) for the rat ranged from 0.96 to 4.14 h(-1). Biotransformation rates for trout microsomes were much lower and ranged from 0.009 to 0.017 h(-1).

Animals↗
PubMedDate not supplied

Transesophageal echocardiographic findings in blue toe syndrome exacerbated by anticoagulation.

The role of anticoagulation in the blue toe syndrome is unresolved. We describe the sonographic appearance of atherosclerotic plaques in the thoracic aorta imaged by transesophageal echocardiography in 2 patients with blue toe syndrome who had reembolization while taking therapeutic levels of anticoagulants. The findings of complex atheromas associated with mobile highly echodense linear structures by transesophageal echocardiography may be predictive of reembolization in patients with blue toe syndrome who are taking anticoagulants.

Aged↗
PubMedDate not supplied

Acute ischemic renal failure: review of experimental studies on pathophysiology and potential protective interventions.

More than 70% of acute renal failure in man is of circulatory nature and results from hypoxic injury to the kidney. Since intrarenal hemodynamic and metabolic events cannot be accurately assessed in human acute renal failure, various experimental models of renal hypoperfusion or complete interruption of renal blood supply, such as norepinephrine-induced acute renal failure or clamping of the renal artery, have been employed to obtain more direct insight into the pathophysiological events and consequences of hypoxia, although none of these models may truly mimic human acute renal failure. In addition, the severity of experimental acute renal failure, that is, oliguric or nonoliguric acute renal failure resulting from renal hypoperfusion, depends not only on the model employed but also largely on the experimental conditions. In the hemodynamic models a vascular component is incriminated in the initial phase, and persistent tubular tissue dysfunction in the maintenance phase of ischemic acute renal failure. Hypoxic vascular injury will lead to vasoconstriction; a decrease in glomerular filtration pressure, glomerular capillary surface area, and permeability; and thus to a decrease in glomerular filtration rate. In contrast to previous concepts which incriminated the renal cortex as the main target tissue of hypoxic injury, in recent years attention has been focused on impaired medullary perfusion as the most prominent pathophysiological event leading to the decrease in total renal blood flow and glomerular filtration rate. Medullary congestion may result from hypoxic cell swelling with vascular compression.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMedDate not supplied

Ouabain-like factors in human urine: identification of a Na-K-ATPase inhibitor as vanadium-diascorbate adduct.

We investigated endogenous Na-K-ATPase inhibitors, i.e. ouabain-like factors(OLFs), in the urine of salt-loaded healthy subjects. During an intake of > 30g NaCl/day 24h-urines were collected, lyophilized, redissolved and acidified to pH 3.5. With gelchromatography the inhibitory activity eluted in a post-salt fraction FIV from Sephadex G-25. When this fraction was again passed through Sephadex G-10, one of three OLFs eluted in the early subfractions FIV/1-2 close to H-ouabain and cross-reacted strongly with a ouabain antibody (NEN). Two additional OLFs with Mr around 400 eluted in a late subfraction FIV/8 which resolved after reverse-phase HPLC into a more polar OLF- (water phase) and a more apolar OLF-2 (20% acetonitrile). Only the more apolar OLF-2 cross-reacted with digoxin and ouabain antibodies. OLF-1 and OLF-2 purified to single compounds by preparative thin layer chromatography inhibited Na-K-ATPase with IC50 of around 1.5 x 10(-5) M and 1.5 x 10(-4) M, respectively. Identification of OLF-2 was first attempted because most material was available for further processing. Data from mass-spectroscopy, nuclear magnetic resonance (1H-NMR) and infrared spectroscopy characterized OLF-2 as structurally unrelated to ouabain but resembling ascorbic acid derivatives, i.e. vanadium (V) diascorbates (Mr 403) with similar elution times from RP-HPLC as OLF-2. They inhibited the enzyme in its E2-configuration with IC50 of 9 x 10(-5) M and 2 x 10(-6) M for V(IV)- and V(V)-diascorbate, respectively. OLF-1, OLF-2 and V-diascorbate raise intracellular free calcium in inner medullary collecting duct and vascular smooth muscle cells which also contract in vitro. V-diascorbate was also natriuretic in a bioassay. We suggest that V-diascorbates represent one of several OLFs excreted in human urine.

Adult↗