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Biomedical subjects

B J White

Publications and source records attributed to B J White.

At least 19 recordsLinked to original sources
PubMed1992

Gonadotropin suppression for the treatment of karyotypically normal spontaneous premature ovarian failure: a controlled trial.

OBJECTIVE: To determine if gonadotropin suppression improves ovarian follicle function or ovulation rates in patients with karyotypically normal spontaneous premature ovarian failure. DESIGN: Prospective, double-blind, placebo-controlled, crossover trial. SETTING: Tertiary care research institution. INTERVENTIONS: Two intervention phases lasting 4 months each: one placebo phase, and one treatment phase during which each patient received daily subcutaneous injections of 300 micrograms of the gonadotropin-releasing hormone agonist (GnRH-a) deslorelin. During both phases, patients took a standardized estrogen (E) replacement regimen. PATIENTS, PARTICIPANTS: Twenty-six patients with karyotypically normal spontaneous premature ovarian failure ranging in age from 18 to 39 years. MAIN OUTCOME MEASURES: We measured serum estradiol (E2) and progesterone (P) levels weekly during the 2 months after each intervention. We defined a serum E2 greater than 50 pg/mL (184 pmol/L) as evidence for ovarian follicle function and a serum P greater than 3.0 ng/mL (9.5 nmol/L) as evidence for ovulation. RESULTS: The GnRH-a therapy did not significantly enhance recovery of ovarian follicle function or the chance of ovulation. The power to detect a 40% and a 33% ovulation success rate with therapy was 0.95 and 0.83, respectively. We found evidence for ovarian follicle function in 11 of 23 women (48%), and 4 women (17%) ovulated. CONCLUSIONS: Patients with karyotypically normal spontaneous premature ovarian failure treated with E replacement did not benefit from the additional gonadotropin suppression achieved with GnRH-a. Because these patients have a significant possibility of spontaneous remission, attempts to induce ovulation should be limited to controlled trials designed to determine safety and effectiveness.

Adult↗
PubMed1992

Studies in a kindred with parathyroid carcinoma.

We report a family with primary hyperparathyroidism in four patients in two generations with apparent autosomal dominant transmission. A fifth member was probably affected. Two cases had definite parathyroid carcinoma (PC), and two had parathyroid adenoma with atypical features that could represent an early stage of cancer. In each of our patients, one parathyroid gland was abnormal. Five other parathyroid glands (in two patients) were normal in histology and size. There was no evidence of neoplasia in other tissues. Constitutional karyotypes were normal in all four patients. We identified three chromosomal abnormalities (a reciprocal translocation between chromosomes 3 and 4, trisomy 7, and a pericentric inversion in chromosome 9) in cultured PC tissue from one patient. These chromosomal changes are of unclear significance. Analyses on tumor DNA from one case of PC and one of atypical adenoma showed no evidence of ras gene mutations, PTH gene rearrangement, or allelic loss from chromosome 11q13 (locus of the gene for multiple endocrine neoplasia type 1). This family shows susceptibility to cancer without antecedent hyperplasia in all parathyroids. It could help identify a novel tumor susceptibility gene.

Adenoma↗
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↗
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↗
PubMed1979

H-Y antigen mosaicism in the gonad of a 46,XX true hermaphrodite.

To clarify the mechanism for the coexistence of ovarian and testicular tissue in the 46,XX true hermaphrodite, we studied a 20-year-old phenotypic male with gynecomastia and elevated serum concentrations of estradiol in whom an ovotestis was discovered upon scrotal exploration. Y chromosomal material could not be detected by fluorescent Y-body analysis or Giemsa-banding technics in cells cultured from peripheral blood, breast or forearm skin or the ovarian or testicular portions of the ovotestis. However, serologic testing, using the sperm cytotoxicity assay, revealed that cells cultured from the testicular portion of the ovotestis were H-Y antigen positive whereas cells cultured from the ovarian portion were H-Y antigen negative. These observations indicate that the ovotestis arises from an H-Y+/H-Y- mosaic primordium.

Adult↗
PubMed1979

Cytogenetic studies of a male with sporadic intestinal lymphangiectasia: 45,X/46,XY mosaicism with pseudo- and hyperdiploid subpopulations in cultured tissues.

45,X/46,XY mosaicism was found in peripheral blood, bone marrow, and tissue cultures of an adult male with intestinal lymphangiectasia (IL). Turner phenotype was not present; his meiotic metaphase analysis was normak, and his dermatoglyphics resembled those of his family. Ten separate tissue culture lines from three biopsies of skin and thyroid gland contained 45,X cells (14.8 to 78.3%). Autosomal aneuploidy, resulting in pseudo- or hyperdiploidy, was also present in 4.3 to 41.6% of the cells. A hyperdiploid clone with a 47,X,+10,+18 karyotype was found in 22.6% of cells in one line. A second hyperdiploid clone with a 48,X,+2,+18,+18 karyotype occurred in 7.6% of cells from another line containing a total of 41.6% pseudo- and hyperdiploid cells. Such clonal abnormalities were not typical of tissue cultures from other patients done in our laboratory. Growth of our patient's tissue cultures was subnormal, and none proliferated beyond the fourth subculture. The significance of this observation remains to be determined. Our results do not allow us to conclude whether our patient's mosaicism of somatic tissues arose during embryogenesis, or whether it originated post-natally. The secondary immunodeficiency which occurs in IL may explain persistence of cells with unusual combinations of autosomal aneuploidy in our patient's tissues.

Adult↗
PubMed1978

Dermatoglyphic and radiographic findings in a mother and daughter with pseudohypoparathyroidism.

The dermatoglyphic features of a mother and daughter with pseudohypoparathyroidism were compared with those of 19 other reported PHP cases and with findings typical of 45,X Turner syndrome. Our observations included large patterns with a predominance of whorls, unusual accidental patterns on the third fingers, elevated total and absolute finger ridge counts, extralimital digital triradii, intermediately placed axial triradii, and a single complete transverse palmar crease. With barium-coated hand radiographs, the positions of the palmar digital triradii were compared with those of the underlying metacarpal and carpal bones. Normally, the fourth digital triradii (c) are superficial to the epiphyseal region of the proximal phalanx, near the fourth M-P joint. In our cases, the c triradii were distal to the proximal phalanx, near the fourth M-P joint. In our cases, the c triradii were distal to the M-P joint, adjacent to the diaphysis of the proximal phalanx. These findings, related to post-natal differences in growth potential of osseous structures and overlying dermal ridge tissues in this disease, may also be relevant to other syndromes with abnormal development of the hand. The need for further delineation of PHP dermatoglyphics and comparison of findings with data from Turner syndrome and normals is stressed.

Adult↗
PubMed1976

M-plasty techniques.

Conventional closure of surgical defects in skin may cause unsightly protrusions (dog ears). Fusiform excisions with angles of 30 degrees or less reduce protrusion but may require excision of larger volumes and lengths of healthy skin and subcutaneous tissue than may be desirable. M-plasties reduce these requirements while still allowing use of 30 degrees angles at maximum. Applications and technical details are described and illustrated.

Dermatologic Surgical Procedures↗
PubMed1976

Genetic mapping of xthA, the structural gene for exonuclease III in Escherichia coli K-12.

The genes xthA, pncA, and pabB were ordered relative to others by two- and three-factor transductional crosses with bacteriophage P1. The genes studied span 2 min (2%) of the genetic map of Escherichia coli K-12 in the clockwise sequence pheS-pfkB-xthA-pncA-gap-pabB-fadD. Eleven independently derived xth mutations were examined; all were known to affect exonuclease III and its associated endonuclease II activity, and all were mapped in the xthA region. pncA mutations were found to confer resistance to 6-aminonicotinamide, whereas some pheS mutations are known to specify resistance to p-fluorphenylalanine. xth mutations were readily transferred into other strains by selecting for these co-transducible drug resistance markers.

6-Aminonicotinamide↗