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Biomedical subjects

W Kuhl

Publications and source records attributed to W Kuhl.

At least 55 records · Page 3Linked to original sources
PubMed1984

Cross-reacting material in Gaucher disease fibroblasts.

Glucocerebrosidase is the enzyme that is deficient in Gaucher diseases. Four monoclonal antibodies reacting with at least two different epitopes of this enzyme have been produced. The amounts of glucocerebrosidase in fibroblasts of patients with all three types of Gaucher disease were investigated by radioiodinating two of the antibodies and measuring their binding to fibroblast extracts immobilized on nitrocellulose filters. The amount of glucocerebrosidase antigen was decreased in all cases of Gaucher disease, particularly in the fibroblasts of patients with the more severe neuronopathic forms of the disorder, types II and III. The catalytic activity was reduced to a greater extent than the amount of antigen in all cases, so that the specific activity of the residual enzyme was found to be diminished. Although measurements in individual cases were quite reproducible and the amount of antigen detected by monoclonal antibodies reacting with different epitopes was quite similar, there was considerable variation between patients. This finding is consistent with the apparent within-type genetic heterogeneity of Gaucher disease, even within the Ashkenazi Jewish population in which it is most prevalent.

Antibodies, Monoclonal↗
PubMed1983

Sodium-potassium-ATPase activity is influenced by ethnic origin and not by obesity.

Previous investigations have suggested that red-cell ouabain binding (an indirect measure of sodium-potassium-ATPase activity) is lower in severely obese patients than in normal controls. We now confirm that ouabain binding measures sodium-potassium-ATPase activity, and we demonstrate that the level of this activity is genetically determined. The activity of this enzyme differs in various ethnic and racial groups, relatively high levels being encountered in non-Jewish white subjects, particularly those with some Scandinavian ancestry. On the other hand, black, Asian, and Jewish white subjects have lower sodium-potassium-ATPase activity. In contrast, no difference was found in red-cell sodium-potassium-ATPase activity between severely obese and normal persons, nor could we confirm a putative effect of food intake on the level of the red-cell enzyme. We suggest that in most earlier studies in which differences were found between normal and severely obese persons, those differences could have been due to differences in the ethnic origins of the obese and control populations.

Diet↗
PubMed1983

Metabolic compensation for profound erythrocyte adenylate kinase deficiency. A hereditary enzyme defect without hemolytic anemia.

A child with hemolytic anemia was found to have severe erythrocyte adenylate kinase (AK) deficiency, but an equally enzyme-deficient sibling had no evidence of hemolysis. No residual enzyme activity was found in erythrocytes by spectrophotometric methods that could easily have detected 0.1% of normal activity. However, concentrated hemolysates were shown to have the capacity to generate small amounts of ATP and AMP from ADP after prolonged incubation. Hemolysates could also catalyze the transfer of labeled gamma-phosphate from ATP to ADP. Intact erythrocytes were able to transfer phosphate from the gamma-position of ATP to the beta-position, albeit at a rate substantially slower than normal. They could also incorporate 14C-labeled adenine into ADP and ATP. Thus, a small amount of residual AK-like activity representing about 1/2,000 of the activity normally present could be documented in the deficient erythrocytes. The residual activity was not inhibited by N-ethylmaleimide, which completely abolishes the activity of the normal AK1 isozyme of erythrocytes. The minute amount of residual activity in erythrocytes could represent a small amount of the AK2 isozyme, which has not been thought to be present in erythrocytes, or the activity of erythrocyte guanylate kinase with AMP substituting as substrate for GMP. Peripheral blood leukocytes, cultured skin fibroblasts, and transformed lymphoblasts from the deficient subject manifested about 17, 24, and 74%, respectively, of the activity of the concurrent controls. This residual activity is consistent with the existence of genetically independent AK isozyme, AK2, which is known to exist in these tissues. The cause of hemolysis in the proband was not identified. Possibilities include an unrelated enzyme deficiency or other erythrocyte enzyme defect and intraction of another unidentified defect with AK deficiency.

Adenine↗
PubMed1982

The osmotic fragility of erythrocytes after prolonged liquid storage and after reinfusion.

Although it is recognized that red cells lose membrane during storage, estimation of the osmotic fragility of erythrocytes has not previously proven to be a useful measurement of the storage lesion. Erythrocytes from blood stored in CPD-A2 were found to have a markedly increased osmotic fragility. A major portion of this increase was found to be due to accumulation of lactate, which is only slowly transported from within erythrocytes and which therefore exerts a strong osmotic effect in the usual osmotic fragility test. After an hour's incubation in a large volume of iso-osmotic buffer, the osmotic fragility curve of stored erythrocytes was much more nearly normal. Such cells were found to have a volume 5%--8% greater than that of normal cells, indicating that even after removal of lactate more osmotically active material was present in the stored erythrocytes than in fresh cells. Most of this differences can be accounted for by substitution of chloride ion for 2,3-DPG, since chloride exerts approximately 3.7 times the osmotic effect of 2,3-DPG per unit charge. In addition to the shift in osmotic fragility produced by the increased intracellular osmotically active material, a "fragile tail" of red cells was also present. Stored erythrocytes were labeled with 51Cr and reinfused into the volunteer donors. The osmotic fragility of the reinfused cells was estimated using a technique of sequential osmotic hemolysis that permitted accurate estimation of osmotic fragility of transfused cells using very small amounts of 51Cr. The osmotic fragility of the reinfused cells became less than those of fresh cells after 24 hr and was exactly the same as those of fresh cells after 4 days. The fragile tail disappeared at a rate that approximated the rate of loss of nonviable erythrocytes from the circulation as measured by 51Cr. These findings are consistent with the preferential destruction of a subpopulation of red cells with a diminished surface area.

Adenine↗
PubMed1981

A common mutant EcoRI restriction endonuclease site in the 5' flanking portion of the human alpha-globin gene.

A mutant EcoRI endonuclease restriction site has been identified in 3 of 37 Black subjects and in 2 sibs of one of these persons. This mutation was not encountered in 13 Whites. It is located approximately 6 kilobases "inside" the normal site in the 5' flanking sequence of the alpha-globin chain complex. The shortened alpha-globin gene-bearing segment produced in the EcoRI digest produces a restriction map similar to that observed for the common alpha-globin gene deletion observed in the Black population. However, the restriction map with BamHI is normal, confirming that all four alpha loci are present.

Base Sequence↗
PubMed1981

The effect of alpha-thalassemia on the expression of the beta-thalassemia/HPFH heterozygote in a black family.

A 2-yr-old black girl presented with a thalassemic clinical picture and was found to have nearly 100% fetal hemoglobin in her red cells. Pedigree analysis indicated that she was a heterozygote for the hereditary persistence of fetal hemoglobin gene and for a beta O-thalassemia gene. A brother, who also had nearly 100% fetal hemoglobin in his red cells, manifested, in contrast to his sister, no anemia and only minimal splenomegaly. Examination of the family's alpha-globin loci using the restriction endonuclease Eco Rl demonstrated that the brother had a single alpha-locus deletion that he had inherited from his mother. The mild clinical manifestations of this boy are consistent with the often expressed view that excess alpha chains may contribute significantly to the hematologic manifestation of beta-thalassemia.

Black People↗
PubMed1980

Guanosine triphosphatase activity in human erythrocyte membranes.

Human red cell membranes have the capacity to hydrolyze enzymatically GTD to GDP. The reaction requires magnesium, is not appreciably affected by sodium, potassium or calcium, and is not inhibited by ouabain. Kinetic analysis suggests that there are two separate enzymes in membranes which cleave GTP, a 'high Km' GTPase and a 'low Km' GTPase. Both enzymes are also ATPases, with an approximately equal affinity for GTP and ATP. GTPase activity did not extract from the membrane with spectrin and was not inactivated by antispectrin antibody. Activity was partially destroyed by 0.5% Triton X-100. It seems probable that the low Km GTPase is the sodium- and potassium-independent ATPase of red cell membranes. The identity of the high Km enzyme is not clear.

Adenosine Triphosphatases↗
PubMed1980

[Peripheral vestibular vertigo (author's transl)].

In 88 patients with benign paroxysmal postural vertigo and repeated attacks of vestibular vertigo the clinical and electronystagmographic findings were evaluated in a retrospective study. After an interval of at least two years 16 patients with paroxysmal postural vertigo were symptom-free 39 had rare or (and) tolerable vertigo, 30 frequent and (or) disturbing recurrent postural vertigo. Five patients showed transition into spontaneous recurrent attacks of vertigo. Out of 37 patients with single vestibular vertigo after an interval of at least 4 weeks 9 had unilateral caloric unresponsiveness, 11 hyporesponsiveness, 11 spontaneous nystagmus and 6 normal findings. 58 patients with recurrent vestibular vertigo could be differentiated into two groups: 29 with signs of labyrinthine damage and 29 with persistent normal findings in the interval even after many years of the disease. The two groups were significantly different in their age of manifestation. It is thus justified to separate functional from organic vestibulopathies. Not even in the group of organic vestibulopathy was there any clear-cut evidence of general vascular disease as the underlying cause.

Adult↗
PubMed1979

Incorporation of glucocerebrosidase into Gaucher's disease monocytes in vitro.

Several carriers were evaluated for use in the delivery of exogenous glucocerebrosidase to monocytes from Gaucher's disease patients. Only gamma globulin-coated, resealed erythrocytes proved to be an effective vehicle for enzyme delivery. Glucocerebrosidase added in this manner normalized intracellular enzyme levels for at least 18 hr. In this model system for the study of enzyme replacement therapy, soluble enzyme, enzyme in uncoated resealed erythrocytes, and enzyme incorporated into liposomes were ineffective.

Cells, Cultured↗
PubMed1978

Existence of only a single functional pool of adenosine triphosphate in human erythrocytes.

The question of whether separate "membrane" and "soluble" pools of ATP exist in erythrocytes has been examined. Phosphoglycerate kinase (EC 2.7.2.3)-derived ("membrane") ATP was labeled by short-term incubation with inorganic [32P]phosphate. Pyruvate kinase (EC 2.7.1.40)-derived ("soluble")ATP is not labeled under these circumstances. The specific activity of the gamma-phosphate of "soluble" ATP was then evaluated by the addition of 2-deoxyglucose and measurement of the specific activity of 2-deoxyglucose-6-[32P]phosphate formed. This specific activity was essentially the same as the overall specific activity of erythrocyte ATP gama-phosphate, indicating that no functional pools of phosphoglycerate kinase-derived and pyruvate kinase-derived ATP exist in erythrocytes.

Adenosine Triphosphate↗
PubMed1978

An assay for terminal deoxynucleotidyl transferase in leukocytes and bone marrow.

A modified technic for the assay of terminal transferase activity in leukocytes and bone marrow is presented. 3H-deoxyadenosine-5' -triphosphate serves as nucleotide donor and (dA)10 as primer. The reaction product is collected as a trichloroacetic acid precipitate, which is dissolved for radioactive quantitation. All reagents are commercially available, and the procedure has been designed to minimize cost and to provide low blank values. Excellent linearity between enzymatic concentration and activity and between time and activity is observed. Because the assay is carried out at conditions approaching the optimum for the enzyme, the measured activities are more than ten times those observed with previous methods.

Bone Marrow↗
PubMed1978

Acid hydrolases in normal B and T blood lymphocytes.

B and T lymphocytes were separated by means of the spontaneous sheep red blood cell rosette formation technique from 3 normal donors. The following acid hydrolases were biochemically determined on separated B and T lymphocytes: acid phosphatase, beta-glucuronidase, beta-galactosidase, beta-hexosaminidase, alpha-arabinosidase, alpha-galactosidase, alpha-mannosidase, alpha-glucosidase, and pH 4.0 and pH 5.0 beta-glucosidase. The activities of most of the acid hydrolases including acid phosphatase and beta-glucuronidase were found to be slightly decreased in B lymphocytes when compared to T lymphocytes. However, alpha-mannosidase activity was found to be significantly higher in the B lymphocytes than in the T lymphocytes and offers the possibility of using this enzyme as a B lymphocyte marker.

B-Lymphocytes↗