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Biomedical subjects

B J White

Publications and source records attributed to B J White.

At least 37 records · Page 2Linked to original sources
PubMed1989

Variant nucleolus organizing regions and the risk of Down syndrome.

In order to determine whether nucleolus organizing region (NOR) heteromorphisms of the acrocentric chromosomes could identify individuals at risk for having offspring with trisomy 21, a comparison was made between 43 parents of individuals with Down syndrome and 39 controls. NORs, as visualized by silver staining, were analyzed by mean number per cell, average size, total NOR "mass" per cell (designated mean score per cell) and by mean number of acrocentric chromosome satellite associations per cell. No "double NOR" variants (dNOR) were found in either the control or study group in contrast to observations of others (Jackson-Cook et al. 1985). The risk for having a child with trisomy correlated with a higher frequency of associations and number of NORs per cell, but slightly lower average NOR size. Although these group differences were statistically significant, specific types of NOR variants such as enlarged or dNORs were not associated with the risk of having trisomy 21 offspring. The constancy of NOR mass per cell in our control and study groups indicates that NOR activity remains constant, even though distribution of the rRNA genes (variation in number and size of NORs on the 10 acrocentrics) may vary.

Adult↗
PubMed1989

The structure of the shell and polar plugs of the egg of the whipworm, Trichuris trichiura (Nematoda: Trichuridae) from the Samango monkey (Cercopithecus albogularis).

The structure of the shell of the egg of Trichuris trichiura was examined using light microscopy as well as scanning and transmission electron microscopy. The results confirmed its three-layered structure and provided evidence that the cores of the polar plugs, which could be seen to be extensions of the shell's middle layer, could be lost en bloc, either mechanically or chemically, and in this way probably provided an exit for the first stage larva at hatching.

Animals↗
PubMed1989

Airway obstruction after autologous reimplantation of the porcine lobe.

Bronchiolitis obliterans (irreversible small airway obstruction) is a late complication of heart-lung transplantation. Chronic immune rejection is believed to be the major cause of this complication. Our hypothesis was that denervation might contribute to airway obstruction. To test this hypothesis in the absence of immune rejection, we performed a lobectomy of the upper lobe of the left lung and autologous reimplantation of the lower lobe of the left lung in 13 growing pigs. To serve as age-matched controls, six other pigs had sham left thoracotomy and nine others had a lobectomy of the upper lobe of the left lung alone. Nine to 10 weeks after operation, the animals were anesthetized and the lungs mechanically ventilated. The lobes were then isolated in vivo to measure differential transrespiratory mechanics and volumes. Dynamic compliance was significantly lower in the reimplanted lobe than it was in the contralateral right lung. This was the case after lobectomy of the upper lobe of the left lung or sham thoracotomy. Dynamic resistance was significantly higher in the reimplanted lobe than it was in the contralateral right lung and in the left lung after sham thoracotomy. Measurements of extravascular lung water, dry lobe weight, alveolar cross-sectional area, and volumetric proportions of lung parenchyma and alveolar spaces did not demonstrate abnormal structural growth after reimplantation. We conclude that lobectomy of the upper lobe of the left lung and autologous reimplantation of the left lower lobe leads to adverse changes in flow-dependent measurements of airway patency. Changes in bronchomotor regulation imposed by denervation may contribute to airway obstruction after heart-lung transplantation.

Airway Obstruction↗
PubMed1987

Modification of glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides with the 2',3'-dialdehyde derivative of NADP+ (oNADP+).

Glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides is irreversibly inactivated by the 2,3'-dialdehyde of NADP+ (oNADP+) in the absence of substrate. The inactivation is first order with respect to NADP+ concentration and follows saturation kinetics, indicating that the enzyme initially forms a reversible complex with the inhibitor followed by covalent modification (KI = 1.8 mM). NADP+ and NAD+ protect the enzyme from inactivation by oNADP+. The pK of inactivation is 8.1. oNADP+ is an effective coenzyme in assays of glucose-6-phosphate dehydrogenase (Km = 200 microM). Kinetic evidence and binding studies with [14C] oNADP+ indicate that one molecule of oNADP+ binds per subunit of glucose-6-phosphate dehydrogenase when the enzyme is completely inactivated. The interaction between oNADP+ and the enzyme does not generate a Schiff's base, or a conjugated Schiff's base, but the data are consistent with the formation of a dihydroxymorpholino derivative.

Amino Acids↗
PubMed1987

Cerebral metabolism, anatomy, and cognition in monozygotic twins discordant for dementia of the Alzheimer type.

One pair of monozygotic twins discordant for dementia of the Alzheimer type (DAT) was studied using neuropsychological testing, quantitative x-ray computed tomography (QCT) and magnetic resonance imaging (MRI) of the brain. Cerebral glucose metabolism was measured using positron emission tomography (PET) and 2-[18-F]fluoro-2-deoxy-D-glucose (FDG). The affected twin had a seven year history of progressive cognitive impairment and was severely demented. Neuropsychological testing of the affected twin demonstrated marked deficits in all areas of cognitive function. The asymptomatic twin showed some impairment on tests of perceptual organisation and delayed recall. The affected twin had loss of gray matter and ventricular enlargement on QCT and MRI compared with healthy controls (p less than 0.05). He also had frontal and parietal lobe hypometabolism and increased asymmetry of metabolism on PET compared to both his twin and healthy age-matched controls (p less than 0.05). PET, QCT, and MRI distinguished changes in the twin with DAT compared with his brother and healthy controls. Although the subtle neuropsychological abnormalities of the asymptomatic twin may be signs of early DAT, they were not accompanied by any changes in regional cerebral metabolism or brain structure.

Alzheimer Disease↗
PubMed1984

Balanced rearrangement of chromosomes 2, 5, and 13 in a family with duplication 5q and fetal loss.

We have studied a family in which a mother and daughter (the proposita) had the karyotype 46,XX,ins(2;5),t(5;13). The mother had four spontaneous abortions, a mentally retarded son with duplication (5q), and a daughter who died at 3 months. The proposita had a phenotypically abnormal abortus. Rearrangements involving several chromosomes are very rare. Observations on this family are consistent with the predicted high likelihood of reproductive loss.

Abnormalities, Multiple↗
PubMed1984

Androgen receptor abnormalities in identical twins with oligospermia. Clinical and biochemical studies.

Identical twin brothers presented with oligospermia, small testes, normal male phenotypes, elevated serum luteinizing hormone levels, and normal or elevated serum testosterone levels. Both men had low to low-normal cytosol androgen receptor binding capacity in cultured fibroblasts from pubic skin biopsy specimens. Qualitative abnormalities of cellular androgen receptors were suggested by low-normal or low nuclear androgen uptake in fibroblasts from both brothers as well as abnormal thermolability and subnormal molybdate stabilization of androgen receptors from one brother. In vivo androgen sensitivity was assessed in one twin following administration of testosterone or the non-aromatizable androgen fluoxymesterone. Fluoxymesterone suppressed serum luteinizing hormone and serum testosterone/estradiol-binding globulin, and although testosterone suppressed both serum luteinizing hormone and serum follicle-stimulating hormone, the suppression of serum luteinizing hormone by testosterone was subnormal. Both subjects showed marked exaggeration of the serum 17-hydroxyprogesterone increase after administration of human chorionic gonadotropin, despite normal serum testosterone increases, suggesting a block in testicular 17,20-desmolase, which converts 17-hydroxyprogesterone to testosterone. These studies suggest that oligospermia and block of the enzyme 17,20-desmolase may be the earliest manifestations of androgen resistance, and the finding of the syndrome of oligospermia, normal male phenotype, and androgen receptor abnormalities in identical twins indicates a genetic etiology of this disorder.

17-alpha-Hydroxyprogesterone↗
PubMed1984

Familial premature ovarian failure.

Premature menopause, ovarian failure younger than 40 years of age, is relatively rare but may preclude childbearing for some women who delay attempts at fertility. We present five kindreds in which a genetic association for premature ovarian failure is strongly suggested. Transmission is either autosomal or (less likely) X-linked dominant in these examples. Chromosomal abnormalities, history of diseases, and toxic chemical or viral exposures previously associated with premature ovarian failure could not be demonstrated in these women. This suggests that these kindreds all represent familial idiopathic premature ovarian failure. These data support the need for menopausal histories on both sides of the family for women seeking to postpone reproduction, as well as for patients with ovarian failure.

Adult↗
PubMed1983

Down's syndrome in adults: brain metabolism.

The cerebral metabolic rate for glucose, as measured with positron emission tomography and fluorine-18-labeled 2-deoxy-D-glucose, was significantly higher in four healthy young subjects with trisomy 21 syndrome (Down's syndrome) than the mean rate in healthy young controls. The rate of cerebral glucose utilization in the frontal lobe of a 51-year-old subject with Down's syndrome was significantly lower than the rate in the young subjects with this syndrome, but approximated the rate in middle-aged controls. Thus glucose utilization by the brain appears to be excessive in young adults with Down's syndrome but may decline with age in some brain regions.

Adult↗
PubMed1983

The syndrome of anosmia with hypogonadotropic hypogonadism: a genetic study of 18 new families and a review.

Among 18 NIH probands with anosmia and hypogonadotropic hypogonadism (AHH), seven had affected relatives and three had consanguineous parents. Both sexes were equally affected and parents were phenotypically normal. Parental age was not increased. Cleft lip and palate occurred in both eugonadal and hypogonadal persons, a previously reported association that may represent variable expression of AHH. Diabetes mellitus, usually insulin-dependent, was frequent in probands and their families. Other common traits included obesity, cryptorchidism, and hearing loss. All probands were chromosomally normal. The frequency of some dermatoglyphic traits of probands differed from normal, but no trait was unique to AHH. Segregation analysis of our proband sibships was consistent with a hypothesis of autosomal-recessive inheritance with variable expression. However, genetic heterogeneity was apparent when previous reports of familial AHH were surveyed. An X-linked or male sex-limited autosomal-dominant form with unilateral renal agenesis, mental retardation, and hypotelorism has been observed. The infrequent reports of direct male-to-male transmission limit characterization of an autosomal-dominant form of AHH. Our phenotypic analysis suggests that the traits of mental retardation, renal anomalies, hypotelorism, diabetes, and hearing loss may help to distinguish various forms of AHH, whereas cryptorchidism, clefts, and obesity appear in several types of families. At present, genetic counseling is dependent upon establishing inheritance pattern after examination for the known associated anomalies.

Chromosome Banding↗
PubMed1983

Erythropoiesis in the fetal trisomy 19 mouse. I. Characterization of erythrocyte populations in peripheral blood.

Changes in the type, size, and relative percentage of different erythrocyte populations in the peripheral blood of individual trisomy 19 and normal littermate mouse fetuses were studied from 12 gestational days to term. Large nucleated erythrocytes of yolk-sac origin comprise the first population of cells and are gradually diluted out of the circulation by nonnucleated erythrocytes of hepatic origin. This transition occurs between 12 and 16 gestational days. The rate of decline of the nucleated erythrocytes in the trisomic animals lagged by approximately 1 day behind the normal littermates, so that they did not completely disappear from the peripheral circulation until day 17. A slight decrease in size of the nonnucleated erythrocytes which occurs with increasing gestational age was also delayed by approximately 1 day in the trisomic fetuses. These observations are consistent with an hypothesis that one effect of the murine trisomy 19 genome is to retard by 1 day the growth and development of the affected animal.

Animals↗
PubMed1982

Growth characteristics of the murine trisomy 19 thymus.

Development of the trisomy 19 mouse thymus was studied by (1) evaluation of cell and nuclear counts and volume distributions and (2) examination of the in vivo cell cycle characteristics using flow cytometry. Direct preparations of thymuses from affected animals and their normal littermates at 17, 18, 19 gestational days, and at term were used. Cell numbers in aliquots from the trisomic thymus suspensions were always significantly less than those in the normal animals. There were no differences in cellular or nuclear volumes between the two groups. However, the populations of cells in the trisomic suspensions showed a lag in the normally occurring transition from a larger to a smaller size. DNA distribution histograms from these suspensions were generated using a TPS-1 Cell Sorter, and percentages of cells in different phases of the cell cycle were estimated using computer analysis. The resulting graphs and numerical data from the trisomic mice, when compared with the normals, showed consistent increases in the relative numbers of cells in the S and G2 + M phases of the cell cycle. Because growth retardation is a major feature of trisomy 19, as well as in other murine trisomies, these results suggest that cell cycle alterations may, in part, contribute to the reduced cell number, delayed development, and smaller size of the trisomic animals.

Animals↗
PubMed1981

Cytogenetic studies of familial and sporadic Alzheimer disease.

We present cytogenetic findings in 7 familial and 5 sporadic Alzheimer disease (AD) patients and 34 unaffected relatives, spouses, and normal controls. Our study was prompted by reports of increased chromosome abnormalities in patients and family members at risk for AD. Coded peripheral blood chromosome preparations were evaluated for aneuploidy, aberration rates, and banding patterns. Statistical analyses of our results showed no increase in aneuploidy or aberrations in AD patients, their relatives, or normals. Chromosome loss or gain in aneuploid cells was not specific except in two individuals. These two older persons studied, one with AD and one unaffected, were observed to have increased sex chromosome aneuploidy. This finding was attributed to aging and was not considered to be an effect of AD.

Adult↗
PubMed1981

Familial Alzheimer's disease in two kindreds of the same geographic and ethnic origin. A clinical and genetic study.

Alzheimer's disease (AD) occurred in 37 individuals from two kindreds of Jewish ancestry with a mode of transmission suggesting an autosomal dominant genetic trait. Both kindreds originated from Byelorussia and spoke the Lithuanian dialect of Yiddish. In one of the two families one case of pathologically confirmed AD occurred with clinical and neuropathological signs of Parkinson's disease. In the other family one case of amyotrophic lateral sclerosis and one case of Down's syndrome occurred, both without clinical or pathological signs of AD. In the single kindred tested, a study of the chromosome 6 markers HLA, Bf and GLO failed to reveal a correlation between the transmission of AD and the segregation of these markers. The association of increased aneuploidy of peripheral blood chromosomes with AD was not confirmed in either of these families. Genetic differences between the familial and the sporadic form of AD are discussed.

Adult↗
PubMed1980

Gonadal dysgenesis with mosaicism and a nonfluorescent Y chromosome: report of two cases with correlation of clinical, pathologic, and cytogenetic findings.

Two phenotypic girls with nonfluorescent Y chromosome mosaicism and histologic streak gonads were presented. H-Y antigen (a Y chromosome--determined antigen) was negative in both patients. Electron microscopic findings of "streak gonads" were presented for the first time. The authors recommend bilateral gonadectomy in patients with nonfluorescent Y chromosomes and correlation between the histologic findings and H-Y antigen status.

Adolescent↗