Search PubMed⌕ Search

Biomedical subjects

N Lasker

Publications and source records attributed to N Lasker.

At least 37 records · Page 2Linked to original sources
PubMed1986

[3H]ouabain binding of red blood cells in whites and blacks.

In a previous study, we demonstrated that the red blood cell Na+ concentration and Na+,K+-ATPase activity are sex-dependent and race-dependent: a higher intracellular Na+ concentration in blacks and men was associated with a lower Na+,K+-ATPase activity. To examine whether the low Na+,K+-ATPase activity is due to a decreased number of enzyme units, altered structure of the enzyme, or the presence of an endogenous digoxinlike substance, ouabain binding studies were performed on the same subject group. The measurements included displacement of [3H]ouabain from its specific binding sites by unlabeled ouabain or potassium. The results demonstrate that groups with lower enzyme activity manifest lower numbers of total specific ouabain binding sites on the surface of the red blood cell (mean +/- SD: blacks, 654 +/- 24.4; whites, 806 +/- 18.3; women, 806 +/- 26.9; men, 728 +/- 21.2). Other kinetic parameters of [3H]ouabain displacement appear to be the same among the groups. The respective red blood cell Na+ and K+ concentrations were negatively and positively correlated with the number of ouabain binding sites. Our findings suggest that the lower activity of red blood cell Na+,K+-ATPase in blacks and men is a function of a lower number of Na+-K+ pump units. The results also indicate that sex and race should be considered when red blood cell ouabain binding is examined.

Adenosine Triphosphatases↗
PubMed1985

Race and sex differences in erythrocyte Na+, K+, and Na+-K+-adenosine triphosphatase.

Several reports indicate that erythrocytes (RBCs) from blacks and men have higher sodium concentrations than those from whites and women. One possible mechanism to explain this finding is a difference in the activity of Na+-K+-ATPase. To explore this possibility, we have studied the Na+ and K+ kinetics of RBC Na+-K+-ATPase and RBC Na+ and K+ concentrations in 37 normotensive blacks and whites, both males and females. The maximal initial reaction velocity (Vmax) values for RBC Na+-K+-ATPase were lower in blacks and men as compared with whites and women. Higher RBC Na+ levels were observed in blacks and males vs. whites and females. Significant inverse correlations were noted between the Na+-K+-ATPase activity and RBC Na+ concentrations. These findings indicate that cellular Na+ homeostasis is different in blacks and men as compared with whites and women. Since higher RBC Na+ concentrations have also been observed in patients with essential hypertension as compared with normotensive subjects, the higher intracellular Na+ concentrations in blacks and men may contribute to the greater predisposition of these groups to essential hypertension.

Adult↗
PubMed1985

Erythrocyte sodium/potassium adenosine triphosphatase in thyroid disease and nonthyroidal illness.

Thyroid hormone is known to modulate cell membrane sodium/potassium adenosine triphosphatase (Na/K-ATPase). To determine whether the activity of this enzyme differed in patients with nonthyroidal illness with low levels of circulating thyroid hormones and patients with documented clinical hypothyroidism, we measured Na/K-ATPase activity in red blood cells from patients with hypo- and hyperthyroidism, patients with nonthyroid disease with and without reduced circulating levels of thyroid hormone, and normal subjects. We also assessed whether the activity of this enzyme reflects decreased thyroid hormone action at the cellular level in patients with nonthyroidal illness. Hyperthyroidism was associated with decreased and hypothyroidism with increased erythrocyte Na/K-ATPase activity [142 +/- 24 (+/- SE) and 371 +/- 37 nmol Pi/mg X h; P less than 0.05 and P less than 0.01 compared to normal]. Enzyme activity in cells from patients with nonthyroidal illness and low levels of circulating T3 was significantly higher than that in cells from normal subjects (289 +/- 11 vs. 223 +/- 16 nmol Pi/mg X h; P less than 0.01), but was not significantly different from that in cells from hypothyroid patients. Red cell Na/K-ATPase activity in patients with nonthyroidal illness and normal thyroid function tests (185 +/- 38 nmol Pi/mg X h was indistinguishable from normal values. These data confirm that hyperthyroid patients have decreased red cell Na/K-ATPase activity and provide direct evidence that erythrocyte ATPase activity is increased in hypothyroid patients. The change in enzyme activity in patients with nonthyroidal illness and decreased circulating T3 levels was comparable to that in hypothyroidism. These results suggest that since red cell Na/K-ATPase activity does not distinguish between ill patients with low thyroid function tests and those with hypothyroidism, tissue hypothyroidism may exist in the former group of patients.

Adolescent↗
PubMed1983

Platelet associated IgG in uremia.

Platelet-associated IgG (PAIgG) levels, a useful adjunct for the evaluation of patients with immunologic mediated thrombocytopenia, were obtained in 36 patients with end stage renal disease undergoing maintenance hemodialysis. Twenty-five of the 36 had elevated PAIgG. Nine of the 36 were thrombocytopenic and only 3 of the 9 had elevated PAIgG. Fifteen patients in the group admitted to recent substance abuse. All but one had elevated PAIgG and only one patient was thrombocytopenic. In contrast to patients with idiopathic immune thrombocytopenic purpura (ITP), a direct relationship was not found between PAIgG and total platelet protein (TPP) in the uremic group. It can be concluded that PAIgG values in patients with uremia are difficult to interpret since elevated PAIgG values are found in the majority of uremic patients with normal platelets counts.

Blood Platelets↗
PubMed1978

Accelerated atherosclerosis in chronic-dialysis patients--another look.

Actuarial statistics of 53 dialysis patients treated between 1965 and 1976 are reviewed. It is suggested that dialysis did not accelerate atherosclerosis over the observed time period. It appears as though a fundamental change in the dialysis population has occurred and there are too few long-term dialysis patients available to establish whether dialysis does accelerate atherosclerosis.

Adult↗
PubMed1978

Importance of aliphatic amines in uremia.

Five main aspects were addressed: 1)The demonstration that creatinine is an endogenous precursor of dimethylamine (DMA) in chronic renal failure. 2) The size of the body amine pool measured in transplant patients suggests sequestration in some intracellular compartment. This illustrates the possible error in directly relating serum concentrations to neurological toxicity. 3) Bacterial overgrowth and increased generation of duodenal DMA in the small intestine becomes apparent at a serum creatinine above 8 mg/dl. Two cases show that bacterial overgrowth preceded the increased duodenal DMA. 4)Clinical toxicity is demonstrated by i) correlation of abnormal neurobehavioral parameters with serum amine levels, and ii) by improvement with administration of nonabsorbable broad spectrum antibiotics. Results with adsorption agents are inconclusive. 5) Preliminary tests of behavior modification in a rat model by direct instillation of amines into the brain are positive for TMA but negative for DMA, but no DMA entry into brain cells is demonstrated in the latter. The generation of aliphatic amines represents only one part of a spectrum of alteration induced by proximal intestinal bacterial enzyme action that occurs in renal failure. It is possible that some bacterial activity is beneficial and that the net clinical result is a balance between the "good" and the "evil" bacterial effects.

Animals↗
PubMed1976

Malignant lymphoma with "myeloma kidney" acute renal failure.

The first cases of malignant lymphoma with a "myeloma kidney" type of acute renal failure are presented. With appropriate therapy, both patients regained partial renal function; the first after three months of dialysis. It is suggested that the term paraproteinemic nephropathy is preferable to "myeloma kidney."

Acute Kidney Injury↗
PubMed1975

Peritoneal reactions to particulate matter in peritoneal dialysis solutions.

Peritoneal dialysis solutions were chemically injected into the peritoneal cavity of mice. A high percentage of the injected animals showed particulate matter in the peritoneal membranes associated with an inflammatory reaction. This was prevented by final filtration of the solutions through 0.22 and 0.45 mu filters. It is recommended that all chronic peritoneal dialysis be performed through a final filter.

Animals↗
PubMedDate not supplied

Pelvocalyceal thickening in HIV-associated nephropathy.

BACKGROUND: Previously reported causes of renal pelvocalyceal thickening (PCT) include infection, acute tubular necrosis and obstruction. This study was performed to evaluate the significance of PCT noted sonographically in patients with hyperechoic native kidneys. METHODS: We evaluated sonograms of 178 consecutive patients with hyperechoic native (excluding small and hydronephrotic) kidneys for the presence of PCT, and reviewed medical charts of patients with this finding. We also reviewed sonograms of two control groups: 20 consecutive patients with nephrosis unrelated to human immunodeficiency virus (HIV) infection who underwent renal biopsy, and 30 consecutive patients with severe hypoalbuminemia unrelated to kidney disease. RESULTS: PCT was observed in 20 study patients with hyperechoic kidneys. HIV-associated nephropathy (HIVAN) was diagnosed in 15 patients (14 with bilateral PCT) in whom previously reported causes of this appearance were excluded. PCT was not observed in control patients. CONCLUSION: Renal PCT can occur in patients with HIVAN in the absence of HIV-related complications. PCT in HIVAN does not merely reflect nonspecific nephrosis or hypoalbuminemia. HIVAN should be considered if PCT is noted sonographically in hyperechoic kidneys, even in patients not clinically suspected of harboring HIV infection.

AIDS-Associated Nephropathy↗