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Biomedical subjects

L D White

Publications and source records attributed to L D White.

At least 19 recordsLinked to original sources
PubMed2004

Comparative genomic hybridisation using a proximal 17p BAC/PAC array detects rearrangements responsible for four genomic disorders.

BACKGROUND: Proximal chromosome 17p is a region rich in low copy repeats (LCRs) and prone to chromosomal rearrangements. Four genomic disorders map within the interval 17p11-p12: Charcot-Marie-Tooth disease type 1A, hereditary neuropathy with liability to pressure palsies, Smith-Magenis syndrome, and dup(17)(p11.2p11.2) syndrome. While 80-90% or more of the rearrangements resulting in each disorder are recurrent, several non-recurrent deletions or duplications of varying sizes within proximal 17p also have been characterised using fluorescence in situ hybridisation (FISH). METHODS: A BAC/PAC array based comparative genomic hybridisation (array-CGH) method was tested for its ability to detect these genomic dosage differences and map breakpoints in 25 patients with recurrent and non-recurrent rearrangements. RESULTS: Array-CGH detected the dosage imbalances resulting from either deletion or duplication in all the samples examined. The array-CGH approach, in combination with a dependent statistical inference method, mapped 45/46 (97.8%) of the analysed breakpoints to within one overlapping BAC/PAC clone, compared with determinations done independently by FISH. Several clones within the array that contained large LCRs did not have an adverse effect on the interpretation of the array-CGH data. CONCLUSIONS: Array-CGH is an accurate and sensitive method for detecting genomic dosage differences and identifying rearrangement breakpoints, even in LCR-rich regions of the genome.

Centromere↗
PubMed2001

vvd is required for light adaptation of conidiation-specific genes of Neurospora crassa, but not circadian conidiation.

con-10 and con-6 are two of the conidiation (con) genes of Neurospora crassa that were identified based on their preferential expression during macroconidiophore development. They are also regulated by several other environmental stimuli independent of development, including a transient induction by light. We identified an allele of vivid (vvd) in a mutant screen designed to obtain strains with altered expression of con-10. vvd mutants display enhanced carotenoid pigmentation in response to light. In addition, con-10 and con-6 show a heightened response to photoinduction. We tested the function of the light-responsive circadian clock in the vvd mutant and found no major defect in the circadian rhythm of conidiation or light regulation of a key clock component, frequency (frq). We conclude that vvd is primarily involved in a process of light-dependent gene repression, called light adaptation. Although a number of gene products are known to control light induction in fungi, vvd is the first gene shown to have a role in adaptation to constant light.

Carotenoids↗
PubMed2001

Differential patterns of nerve growth factor, brain-derived neurotrophic factor and neurotrophin-3 mRNA and protein levels in developing regions of rat brain.

The present studies were undertaken to characterize the regional and temporal patterns of neurotrophin messenger RNA and protein levels for beta-nerve growth factor, brain-derived neurotrophic factor and neurotrophin-3 in the developing CNS. We have examined the levels of these neurotrophin messenger RNAs with ribonuclease protection assays and corresponding protein levels with enzyme-linked immunosorbent assays in the developing Long-Evans rat hippocampus, neocortex and cerebellum on postnatal days 1, 7, 14, 21, and 92. In addition, immunohistochemistry was used to localize the neurotrophins in these developing brain regions. Results indicated that in neocortex and hippocampus, messenger RNA for both nerve growth factor and brain-derived neurotrophic factor increased in an age-dependent manner, reaching a plateau by postnatal day 14. In the neocortex, nerve growth factor and brain-derived neurotrophic factor protein levels both peaked at postnatal day 14. In hippocampus, nerve growth factor protein peaked at postnatal day 7 while brain-derived neurotrophic factor peaked at postnatal day 14. In cerebellum, nerve growth factor messenger RNA levels were flat, while nerve growth factor protein peaked at postnatal day 7. Brain-derived neurotrophic factor messenger RNA increased in an age-dependent manner while the pattern for its protein levels was mixed. Neurotrophin-3 messeger RNA levels increased in an age-dependent manner in hippocampus, peaked at postnatal day14 in cerebellum, and no changes occurred in neocortex. Neurotrophin-3 protein was at its peak at postnatal day 1 and thereafter decreased at other postnatal days in all three brain regions. Results of neurotrophin immunohistochemistry often paralleled and complemented enzyme-linked immunosorbent assay data, demonstrating specific cell groups containing neurotrophin proteins in these regions. Within each region, patterns with regard to messenger RNA and respective protein levels for each neurotrophin were unique. No consistent relationship between patterns of neurotrophin messenger RNAs and their cognate proteins was observed between regions. The different regional patterns for neurotrophin messengerRNA and protein levels in each brain region indicate that messenger RNA studies of neurotrophin messenger RNA must be augmented by protein determination to fully characterize spatial and temporal neurotrophin distribution.

Aging↗
PubMed2001

Qualitative and quantitative estimates of apoptosis from birth to senescence in the rat brain.

Apoptosis is crucial for proper development of the CNS, wherein a significant percentage of all central neurons produced during early ontogeny die by apoptosis. To characterize the pattern of developmental programmed cell death, we assayed rat brainstem, neocortex, hippocampus, and cerebellum from birth through senescence. Quantitatively, using an ELISA for oligonucleosomal DNA fragments, we demonstrated that PND1 brainstem, neocortex, and hippocampus have the highest levels of fragmented DNA compared to older ages. Cerebellum displayed a large peak at PND10 and a smaller peak at PND21. Low levels were observed throughout adulthood and into senescence, which was corroborated qualitatively by agarose gel and TUNEL data. These data provide a temporal and regional baseline for further studies of the effects of perturbations of cell death during neural development. Quantitative and qualitative changes in these regional profiles of apoptosis due to environmental insults during early ontogeny may alter neuron number and function later in life.

Aging↗
PubMed1997

Effects of chronic prenatal hypoxia on tyrosine hydroxylase and phenylethanolamine N-methyltransferase messenger RNA and protein levels in medulla oblongata of postnatal rat.

Catecholamines are a class of neurotransmitters involved in central nervous system autonomic control. Both acute and chronic hypoxia create alterations in ventilation and blood pressure via catecholamine release, although the mechanisms of these alterations are unknown. The enzymes tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) catalyze the rate-limiting step in the catecholamine pathway and production of epinephrine, respectively. Both have been colocalized with Fos protein in metabolic mapping studies of the O2-chemosensory pathway of adult and early postnatal rat. Thus, catecholamines are putative neurotransmitters in a subset of second and higher order respiratory neurons. To characterize the effects of prenatal hypoxia on subsequent TH and PNMT gene and protein expression, pregnant rats were placed in moderate hypoxia (10% O2) from gestational d 18 until birth. Northern and Western analyses of dorsal (catecholaminergic/adrenergic cell group 2) and ventral (catecholaminergic/adrenergic cell group 1) medullary tissue of postnatal (P) age P0, P3, P7, P10, and P14 pups were then done to examine changes in TH and PNMT mRNA and protein compared with normoxia-reared controls. Compared with controls, pups exposed to maternal hypoxia during pregnancy had lower levels of TH mRNA and protein at birth in dorsal medulla and higher levels of TH mRNA the first postnatal week in the ventral medulla. Pups that had been hypoxic in utero showed significantly lower levels of PNMT protein during the second postnatal week in dorsal medulla than did controls. Prenatal hypoxia-induced changes in levels of enzymes responsible for catecholamine synthesis may later be manifest as developmental deficiencies in neuronal function. This may compromise responses to acute hypoxic challenges during early postnatal life and contribute to autonomic nervous system disorders of the newborn such as apnea and sudden infant death syndrome.

Age Factors↗
PubMed1996

Molecular analysis of a spontaneous insertion mutation near the alcohol dehydrogenase gene of Drosophila melanogaster.

The structural integrity of the Adh gene in several isogenic lines of Drosophila melanogaster was tested by Southern blot analysis using a 4.75 kilobase (kb) genomic clone of Alcohol dehydrogenase (Adh) as a probe. One line, RI22, III, showed evidence of a spontaneous insertion mutation 5' to the adult enhancer in an area previously indicated as a putative larval enhancer region. The inserted allele was present at an approximate frequency of 50% in relation to the uninserted wildtype allele. Isogenic lines were constructed of both homozygous mutant and wildtype flies, allowing the comparison of a spontaneous insertion mutant allele and it's direct wildtype ancestral allele. The inserted sequence is a 296 basepair (bp) truncated jockey retroposable element. The sequence and distribution of the element as well as it's proximity to the Adh gene are discussed.

Alcohol Dehydrogenase↗
PubMed1996

An eye color gene for the detection of transgenic non-drosophilid insects.

A genetic marker for identifying transgenic Musca domestica by changes in eye color is described. The Drosophila melanogaster tryptophan oxygenase gene, vermilion (v), was tested for its ability to genetically complement the mutant tryptophan oxygenase gene in houseflies homozygous for green (ge). The v cDNA, placed under the control of the hsp82 promoter of D. pseudoobscura was transiently expressed in M. domestica embryos homozygous for the tryptophan oxygenase gene, ge, resulting in the rescue of adult eye color. The use of a gene from D. melanogaster to complement an eye color mutant in Musca provides the opportunity to develop a gene vector system for M. domestica and a select group of other non-drosophilid insects in which homologous mutations exist.

Animals↗
PubMed1996

Insertion of the retroposable element, jockey, near the Adh gene of Drosophila melanogaster is associated with altered gene expression.

The alcohol dehydrogenase (Adh) gene of Drosophila melanogaster is well suited to be a gene expression reporter system. Adh produces a measurable phenotype at both the enzyme and mRNA levels. We recovered a spontaneous transposable element (TE) insertion mutation near the Adh gene. The insertion is a truncated retroposable element, jockey, inserted upstream of the adult Adh enhancer region. Comparisons between the Adhjockey allele and its direct wild-type ancestral allele were made in an isogenic background (i.e. identical cis and trans factors). Differences in Adhjockey expression compared with the wild-type can be attributed solely to the presence of the jockey element. This jockey insertion results in a decrease in adult mRNA transcript levels in the Adhjockey homozygous lines relative to the wild-type counterpart and accounts for a correlated decrease in alcohol dehydrogenase (ADH) enzyme activity. The larval ADH activity levels are not detectably different.

Alcohol Dehydrogenase↗
PubMed1994

Ontogeny of the O2-sensitive pathway in medulla oblongata of postnatal rat.

Fos protein, the product of the immediate early gene c-fos, has been used as a metabolic marker to map the O2 chemosensory pathway activated by hypoxia in the adult rat (Erickson and Millhorn, Brain Res. 567: 11-24, 1991). The current study provides evidence that the O2 chemoreceptor pathway develops during the first postnatal month. Rats at postnatal ages (P) 3, 7, 10, 14, 21, and 28 days were exposed for 3 h to 21% (control) or 10% (hypoxia) O2. Pups were transcardially fixed, brain stems were frozen, sectioned, then reacted with Fos primary antibody, a secondary antibody, avidin-biotin peroxidase, then Ni-DAB as chromogen. Cells showing Fos-like immunoreactivity (Fos-LI) under control and hypoxic conditions were counted in the nucleus tractus solitarii (NTS) and the ventrolateral medulla (VLM). In both areas there was initially a low basal level of Fos-LI, a peak at P10 and a decline to P28. At all ages there was a significant increase in the number of Fos-LI cells in pups exposed to hypoxia. The high basal level of Fos expression at P10 and the high induced level at P14 may correlate with periods of terminal differentiation and maximum synaptogenesis, respectively.

Aging↗
PubMed1993

Expression of cross-reactive idiotypes at the basement membrane zone in patients with bullous pemphigoid.

The purpose of the present study was to determine whether tissue-bound anti-basement membrane zone (BMZ) autoantibodies in patients with bullous pemphigoid (BP) express a cross-reactive idiotype. We assayed 34 skin biopsies from 26 patients with BP and nine biopsies from control subjects, including normal subjects and patients with epidermolysis bullosa acquisita for the presence of a cross-reactive idiotype at the BMZ. Perilesional split-skin biopsies were assayed for the presence of immunoreactants, immunoglobulin G, and complement and for reactivity with a monoclonal anti-idiotypic antibody specific for a circulating anti-BMZ antibody, anti-Id 3-17. Anti-Id 3-17 bound in a linear band to the BMZ in 12 of 26 patients with BP (46%) and in 0 of 9 control subjects. In serial biopsy specimens, the presence or absence of cross-reactive idiotype at the BMZ in six patients was stable during the disease course. This cross-reactive idiotype has been previously identified in the serum of 36% of patients with BP; however, in this study, no correlation was noted between the presence of the cross-reactive idiotype in skin and serum of individual patients. Because cross-reactive idiotypes occur as a consequence of restricted variable-region gene utilization, the demonstration of a cross-reactive idiotype at the BMZ previously identified in the serum of patients with BP supports the hypothesis that circulating and tissue-bound autoantibodies in this disease arise from a common genetic origin.

Antibodies, Anti-Idiotypic↗
PubMed1991

Detection of cross-reactive idiotypes in the serum of patients with bullous pemphigoid.

To further characterize the circulating antibasement membrane zone (antiBMZ) antibodies present in the sera of patients with bullous pemphigoid (BP), we have generated a mouse monoclonal anti-idiotypic antibody (antiId 3-17) specific for an IgG antiBMZ antibody. AntiId 3-17 is specific for an idiotype expressed on antiBMZ IgG in the serum of a patient with BP, and not expressed on pooled normal human IgG or IgG from patients with other autoimmune skin diseases. AntiId 3-17 binds to non-reduced, but not reduced, antiBMZ IgG on immunoblot, suggesting that the idiotype is composed of a conformational epitope expressed on native antibody. By a competitive inhibition ELISA, antiId 3-17 detects a cross-reactive idiotype (CRI) expressed in 18 of 50 (36%) of the sera of patients with BP, but in the sera of only 1 of 50 (2%) normal blood bank controls (p less than 0.001, Fisher's exact test) and 1 of 12 (8%) patients with pemphigus (p = 0.005). Thus, antiId 3-17 recognizes a public idiotype on a native antiBMZ antibody from a patient with BP, which is expressed in the sera of 36% of the unrelated patients with BP studied.

Antibodies, Anti-Idiotypic↗
PubMed1990

Comparison of the natural history of new onset and exacerbated chronic ischemic heart disease. The Chest Pain Study Group.

To compare the natural history of patients with new onset ischemic heart disease with that of patients with exacerbations of chronic ischemic heart disease, short- and long-term outcomes of 3,465 emergency room patients with acute ischemic heart disease at four community and three university hospitals were evaluated. Acute myocardial infarction was diagnosed in 598 (33%) of the 1,835 patients with a prior history of infarction or angina and 934 (57%) of the 1,630 without such a history (p less than 0.001). Patients with new onset ischemic heart disease with acute myocardial infarction were more likely than patients with infarction and exacerbated chronic ischemic heart disease to have Q wave infarction (57% versus 36%) and to receive thrombolytic therapy (11% versus 5%); they also had higher maximal creatine kinase levels (1,088 +/- 1,299 versus 733 +/- 906 U/liter) (p less than 0.0001 for all three). After adjustment for differences in clinical presentation and initial triage, patients with new onset ischemic heart disease with acute myocardial infarction were less likely than the comparison group to have congestive complications (odds ratio 0.63, 95% confidence interval 0.47 to 0.84, p less than 0.01) but not less likely to have arrhythmic, ischemic or overall complications. Among patients with angina without acute myocardial infarction, patients with new onset ischemic heart disease were less likely to have recurrent ischemic pain and congestive heart failure. In multivariate analysis of long-term follow-up data on 457 patients from one hospital, patients with new onset ischemic heart disease had better cardiovascular survival rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1977

Trace metal contamination of evacuated blood collection tubes.

A study was undertaken to investigate the magnitude of potential trace metal contamination contributed by various commercial evacuated blood tubes to blood samples under experimental conditions. None of the tubes tested contributed significant Cu contamination whereas the 1% nitric acid and human blood leaching data clearly indicate that Zn, Pb and Cd contamination of blood samples can be a significant problem with certain blood collection tubes under normal handling, shipping and storage conditions. The implications of these experimental findings are discussed. It is recommended that several of the evacuated blood tubes be leach tested prior to use with blood or plasma and the eluate analyzed for potential trace metal contamination problems.

Blood Chemical Analysis↗
PubMed1976

Arsenic trioxide absorption and excretion in industry.

1. A study of 24 smelter workers routinely exposed to arsenic trioxide was conducted to evaluate some characteristics of its absorption and excretion. A statistically significant correlation was found between airborne arsenic trioxide concentrations below 300 mug/m3 and urinary arsenic values below 500 mug/liter. These men wore personal monitors for five consecutive work days and were determined to have been exposed to average airborne arsenic concentrations of 53 mug/m3 (70 mug/m3 of arsenic trioxide) which increased their urinary arsenic values from 152 mug/liter to 200 mug/liter (an average gain on 32%). 2. The background average urinary arsenic value for adult males not exposed to arsenic trioxide in industry was determined to be 52.6 mug/liter for 204 men during preemployment examinations. 3. After removal from industrial arsenic trioxide exposure, the rate of fall in urinary arsenic values varies with the magnitude of the urinary arsenic level. An initial decrease of 9.5% per day was measured for workers having urinary arsenic values below 200 mug/liter. The initial decrease is about 21% per day for workers with urinary arsenic values over 600 mug/liter. 4. It was determined that arsenic in seafood can alter, in a dramatic fashion, the urinary arsenic values determined for smelter workers within 24 hours following consumption. It is recommended, therefore, that the absorption of arsenic trioxide due to industrial exposure is best evaluated from urine samples collected at least two days after seafood has been eaten.

Adult↗