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Biomedical subjects

B Wolf

Publications and source records attributed to B Wolf.

At least 343 records · Page 19Linked to original sources
PubMed1980

A modified isolated retina-nerve preparation for pharmacological analysis of mammalian photoreceptor function.

A modified isolated retina-optic nerve preparation is described that is suitable for the pharmacologic analysis of photoreceptor activity and other aspects of retinal function. The preparation, which emphasizes the extracellular recording of photoreceptor activity, is particularly suited for experiments of long duration with frequent manipulation of the solution environment of the tissue preparation. Control of the experimental variables, such as intensity of light stimuli, drug concentration and exposure time to drug, temperature, etc, offers considerable advantage to the investigator. Also of considerable advantage to the investigator is that a good index of photoreceptor function is attainable without the necessity of microelectrode penetration of the photoreceptor layer. Some interesting aspects of the retina as a tissue for study are pointed out that make it an inviting target for pharmacologic analysis.

Animals↗
PubMed1980

Psychomotor development in 65 home-reared children with cri-du-chat syndrome.

The psychomotor development of 65 noninstitutionalized individuals with cri-du-chat syndrome was examined through parental questionnaire responses and supporting medical records. Social quotients determined by a Vineland Maturity Scale ranged from 6 to 85, the ages at which developmental milestones were attained varied from the upper limits of normal to six years delayed. Achievement levels were influenced favorably by the early introduction of special education, and were affected adversely by the presence of an unbalanced translocation. This study suggests that many children with cri-du-chat syndrome can attain developmental and social skills normally seen in 5- to 6-year-old children, although their linguistic abilities are seldom as advanced. Contrary to the commonly portrayed clinical picture of severe mental retardation and bedridden debilitation, the older home-reared cri-du-chat child was usually ambulatory, had a moderate degree of independence in self-care skills, and was able to communicate either verbally or through gestural sign language. Physicians and parents should be aware of the full range of psychomotor potential of the child with cri-du-chat syndrome in order to make informed decisions concerning institutional placement.

Achievement↗
PubMed1980

Ultrasonography and nephrotomography in the presymptomatic diagnosis of dominantly inherited (adult-onset) polycystic kidney disease.

Results of an ongoing four-year study evaluating the role of ultrasonography, nephrotomography, and routine excretory urography in the presymptomatic diagnosis of adult polycystic kidney disease (APKD) are reported. Of 39 asymptomatic individuals who were at risk for APKD, 16 had abnormal studies-eight had bilateral renal cysts withouthepatic cysts on both imaging studies, four had bilateral renal cysts on both imaging studies and hepatic cysts on at least one imaging study, two children who did not have sonographic studies had bilateral renal cysts on nephrotomography, and two children who had a normal nephrotomography had unilateral renal cysts on ultrasonography. Consequently, children of adults with known APKD can be identified as presymptomatic by gray scale ultrasonography, nephrotomography, and/or excretory urography. Gray scale ultrasonography alone is sufficient for family screening for APKD.

Adolescent↗
PubMed1980

Dysautonomia in an infant with secondary hyperammonemia due to propionyl coenzyme A carboxylase deficiency.

A male infant who had vomiting and coma in the absence of ketoacidosis was initially thought to have dysautonomia because of abnormal responses to methacholine and histamine, as well as abnormal urinary catecholamine excretion. Following an episode of hyperammonemia, a liver biopsy was performed which revealed a partial deficiency of carbamyl phosphate synthetase activity. The patient was treated with a protein-restricted diet supplemented with a mixture of ketoacid analogues of the essential amino acids, which precipitated ketosis and acidosis. A primary deficiency of propionyl coenzyme A (CoA) carboxylase was subsequently demonstrated. Because disorders of propionate metabolism may not initially present with ketoacidosis, we recommend examination of both plasma and urine for metabolites of this pathway, as well as direct measurement of propionyl CoA carboxylase activity in peripheral blood leukocytes, before performing a liver biopsy to evaluate urea cycle enzyme activities, and particularly before adding keto acid/amino acid mixtures to a protein-restricted diet.

Acyl Coenzyme A↗
PubMed1980

Kinetic analysis of genetic complementation in heterokaryons of propionyl CoA carboxylase-deficient human fibroblasts.

We studied genetic complementation of propionyl CoA carboxylase (PCC) deficiency in cultures of polyethylene glycol (PEG)-induced heterokaryons, using mutant fibroblast lines assigned to five mutant classes, designated bio, pcc A, pcc B, pcc C, and pcc BC. By measuring PCC activity directly in extracts of fused cells or indirectly in intact cells by [1-14C]propionate utilization, we confirmed the nonlinear nature of the PCC deficiency complementation map described by Gravel et al. [1]. When we studied the kinetics of complementation, we detected three distinct patterns using the [1-14C]propionate utilization assay. When either pcc A or pcc C lines were fused to bio cells, 14C-fixation increased to half of the maximally restored values within 4 hrs. In pcc A x pcc C crosses or in pcc A x pcc B crosses, however, complementation was much slower. In fusions between pcc B and pcc C cells, a third pattern was elicited; complementation was incomplete, maximum restoration of PCC activity begin less than 20% of that observed in other complementing crosses. From these data and previous biochemical evidence, we suggest (1) that the bio and pcc mutations affect different genes; (2) that complementation between pcc A and either pcc B, pcc C, or pcc BC lines is intergenic and involves subunit exchange and synthesis of new PCC molecules; and (3) that complementation between pcc B and pcc C mutants is interallelic.

Carbon-Carbon Ligases↗
PubMed1980

Genetics of propionic acidemia in a Mennonite-Amish kindred.

A large Mennonite kindred was found to have propionic acidemia (complementation group pcc C) in at least four different sibships. Even within this kindred and this complementation group (where etiology may be assumed to be identical), there is a wide range of symptoms exhibited by homozygous pcc C-deficient individuals. The inbreeding coefficients (f) for the affected sibships ranged from 4.776 X 10(3) to 2.003 X 10(-2). Data from this study strongly support the single-locus autosomal recessive mode of inheritance. Three couples were found to be common in the ancestry (9--11 generations ago) of all eight parents of the four affected sibships. Relative likelihoods for a member of each of those couples to have been the early carrier of the defective allele were calculated at 1539, 278, and 1. Thus, one couple was designated the most likely earliest-known transmitter of the pcc-deficient allele.

Adult↗
PubMed1979

Biochemical characterization of mutant propionyl CoA carboxylases from two minor genetic complementation groups.

We have biochemically characterized several parameters of propionyl CoA carboxylase (PCC) activity in fibroblast extracts from PCC-deficient patients belonging to the two minor genetic complementation groups with those of the two major complementation pccB and pccBC. Comparison of PCC's from these groups with those of the two major complementation groups, pcc A and pcc C, has demonstrated that PCCs from both the pcc B and pcc BC groups closely resemble each other as well as PCC from the pcc C group. These results further support the hypothesis that the pcc B and pcc BC lines are interallelic with respect to pcc C and consequently that the structural mutations in the PCCs from these groups involve the same subunit.

Alleles↗
PubMed1979

Evaluation of biotin responsiveness in cultured fibroblasts from patients with propionic acidemia: absence of response by structurally altered carboxylases.

We have demonstrated that, although propionyl CoA carboxylase (PCC) activity is deficient in fibroblast extracts from PCC-deficient patients belonging to the two major and two minor genetic complementation groups, the activity of another biotin-dependent carboxylase, beta-methylcrotonyl CoA carboxylase (betaMCC), is normal. Moreover, betaMCC activity is stimulated when the fibroblasts are cultured in high concentrations of biotin, in the same way that it is in normal fibroblasts, whereas the depressed PCC activity remains essentially unchanged. Because these results are parallel with the in vivo failure of high-dose biotin to stimulate PCC activity in peripheral blood leukocytes, we conclude that the biotin responsiveness of PCC in cultured fibroblasts from patients with PCC deficiency may be used to predict or confirm biotin responsiveness in vivo.

Biotin↗
PubMed1979

Essential arginine residues in the active sites of propionyl CoA carboxylase and beta-methylcrotonyl CoA carboxylase.

At least one arginine residue is essential for substrate binding in or near the active sites of propionyl CoA carboxylase (PCC) and beta-methylcrotonyl CoA carboxylase (beta MCC) in cultured human fibroblasts. This conclusion is based on studies of enzyme inhibition by phenylglyoxal, a reagent which specifically modifies arginine residues. Human fibroblast PCC both in extracts and in a 20-fold purified preparation was nearly completely protected from phenylglyoxal inhibition following incubation with propionyl CoA or ATP. It appears that a phosphate group from either ATP or the CoA moiety of propionyl CoA reacts with the essential arginine residue(s). beta MCC which was similarly inhibited by phenylglyoxal was protected by beta-methylcrotonyl CoA and ATP. Thus phenylglyoxal may be used to label specific arginine residues within the active sites of previously sequenced carboxylases.

Acyl Coenzyme A↗