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Biomedical subjects

J A White

Publications and source records attributed to J A White.

At least 19 recordsLinked to original sources
PubMed1992

Genetic linkage evidence for a familial Alzheimer's disease locus on chromosome 14.

Linkage analysis was used to search the genome for chromosomal regions harboring familial Alzheimer's disease genes. Markers on chromosome 14 gave highly significant positive lod scores in early-onset non-Volga German kindreds; a Zmax of 9.15 (theta = 0.01) was obtained with the marker D14S43 at 14q24.3. One early-onset family yielded a lod score of 4.89 (theta = 0.0). When no assumptions were made about age-dependent penetrance, significant results were still obtained (Zmax = 5.94, theta = 0.0), despite the loss of power to detect linkage under these conditions. Results for the Volga German families were either negative or nonsignificant for markers in this region. Thus, evidence indicates a familial Alzheimer's disease locus on chromosome 14.

Alzheimer Disease↗
PubMed1992

The parameter identification problem for the somatic shunt model.

The somatic shunt model, a generalized version of the Rall equivalent cylinder model, is used commonly to describe the passive electrotonic properties of neurons. Procedures for determining the parameters of the somatic shunt model that best describe a given neuron typically rely on the response of the cell to a small step of hyperpolarizing current injected by an intrasomatic recording electrode. In this study it is shown that the problem of estimating model parameters for the somatic shunt model using physiological data is ill-posed, in that very small errors in measured data can lead to large and unpredictable errors in parameter estimates. If the somatic shunt is assumed to be a real property of the intact neuron, the effects of these errors are not severe when predicting EPSP waveshapes resulting from synaptic input at a given location. However, if the somatic shunt is assumed to be a consequence of a leakage pathway around the recording electrode, and a correction for the shunt is applied, then the instability of the inverse problem can introduce large errors in estimates of EPSP waveshape as a function of synaptic location in the intact cell. Morphological constraints can be used to improve the accuracy of the inversion procedure in terms of both parameter estimates and predicted EPSP responses.

Mathematics↗
PubMed1992

Cooperativity of SV40 T antigen and ras in progressive stages of transformation of human fibroblasts.

Human diploid fibroblasts immortalized by SV40 T antigen provide an experimental system for studying the progression and synergism in transformation by secondary oncogenes. We have utilized the human fibroblast line HAL, which was immortalized with an orgin-defective SV40 genome encoding a temperature-sensitive T antigen, to study the cooperativity between SV40 T antigen and the ras oncogene in the progression of transformation. This study demonstrates that HAL cells possess characteristic growth patterns, requiring 10% serum, are anchorage dependent, and express a temperature-sensitive T antigen. HAL cells rely on the normal functioning of T antigen for continual growth and therefore do not proliferate at 39 degrees C. Three new derivatives of the HAL cell line were generated by microinjection of the ras oncogene. The cell line v-ras-HAL was derived by microinjection of HAL cells with v-Ha-ras DNA. The cell lines c-rasSVneo-HAL and c-rasLTRhygro-HAL were established by microinjection of HAL cells with the plasmids pSV2neoT24 or fpHVT24, respectively, wherein the ras gene is transcriptionally regulated by the cellular promoter and driven by either the SV40 enhancer or an upstream LTR enhancer. The three ras containing cell lines grow in reduced serum concentrations (0 to 5%), are anchorage independent, and express both T antigen and ras p21. The v-ras-HAL and c-rasSVneo-HAL cell lines are still dependent upon the normal functioning of T antigen for continual growth at 39 degrees C, however the c-rasLTRhygro-HAL cell line does proliferate at 39 degrees C in 10% serum-containing medium. Therefore, we propose that neither v-Ha-ras nor c-ras can replace T antigen at 39 degrees C; rather T antigen and ras cooperate in progressive stages of transformation of human fibroblasts.

Antigens, Polyomavirus Transforming↗
PubMed1992

Daily energy expenditure in free-living children: comparison of heart-rate monitoring with the doubly labeled water (2H2(18)O) method.

Total energy expenditure (TEE) was measured simultaneously in 36 free-living children aged 7, 9, 12, and 15 y over 10-15 d by the doubly labeled water (DLW) method and for 2-3 separate days by heart-rate (HR) monitoring. The 95% confidence limits of agreement (mean difference +/- 2SD) were -1.99 to +1.44 MJ/d. HR TEE discrepancies ranged from -16.7% to +18.8% with 23 values lying within +/- 10% of DLW TEE estimates. Boys and girls spent 462 +/- 108 and 318 +/- 120 min/d, respectively, in total physical activity (P less than 0.01). Time spent in moderate and vigorous physical activity (MVPA) was 68 +/- 37 min/d by younger children (7-9 y) and 34 +/- 24 min/d by older children (12-15 y) (P less than 0.001). Younger boys engaged in MVPA (91 +/- 33 min/d) and vigorous physical activity (VPA) (35 +/- 15 min/d) significantly longer than younger girls (MVPA, 39 +/- 16 min/d, P less than 0.001; VPA, 10 +/- 4 min/d, P less than 0.01) as did older boys (MVPA, 52 +/- 21 min/d; VPA, 30 +/- 18 min/d) compared with older girls (MVPA, 15 +/- 10 min/d; VPA, 8 +/- 5 min/d). HR monitoring provides a close estimation of the TEE of population groups and objective assessment of associated patterns of physical activity.

Adolescent↗
PubMed1992

Linkage and mutational analysis of familial Alzheimer disease kindreds for the APP gene region.

A large number of familial Alzheimer disease (FAD) kindreds were examined to determine whether mutations in the amyloid precursor protein (APP) gene could be responsible for the disease. Previous studies have identified three mutations at APP codon 717 which are pathogenic for Alzheimer disease (AD). Samples from affected subjects were examined for mutations in exons 16 and 17 of the APP gene. A combination of direct sequencing and single-strand conformational polymorphism analysis was used. Sporadic AD and normal controls were also examined by the same methods. Five sequence variants were identified. One variant at APP codon 693 resulted in a Glu-->Gly change. This is the same codon as the hereditary cerebral hemorrhage with amyloidosis-Dutch type Glu-->Gln mutation. Another single-base change at APP codon 708 did not alter the amino acid encoded at this site. Two point mutations and a 6-bp deletion were identified in the intronic sequences surrounding exon 17. None of the variants could be unambiguously determined to be responsible for FAD. The larger families were also analyzed by testing for linkage of FAD to a highly polymorphic short tandem repeat marker (D21S210) that is tightly linked to APP. Highly negative LOD scores were obtained for the family groups tested, and linkage was formally excluded beyond theta = .10 for the Volga German kindreds, theta = .20 for early-onset non-Volga Germans, and theta = .10 for late-onset families. LOD scores for linkage of FAD to markers centromeric to APP (D21S1/S11, D21S13, and D21S215) were also negative in the three family groups. These studies show that APP mutations account for AD in only a small fraction of FAD kindreds.

Adult↗
PubMed1992

Primary immunodeficiencies.

Primary immunodeficiencies are rare immune system disorders that present with recurrent and chronic infections of the head and neck. Otitis media, sinusitis, and upper respiratory tract infections develop frequently and present in early childhood. The purpose of this report is to classify and define the primary immunodeficiencies as well as to examine the clinical manifestations, evaluation, and treatment of these disorders.

Diagnosis, Differential↗
PubMed1992

Eagle's syndrome: the Ochsner experience.

Eagle fully described the syndrome that bears his name in 1948. He noted that the typical patient had undergone tonsillectomy in the past. Although reported in the literature, the carotid artery syndrome is frequently overlooked in patients manifesting craniofacial or pharyngeal pain but who have not undergone tonsillectomy. Cases representative of the variety of patients with Eagle's syndrome treated at the Ochsner Clinic Department of Otolaryngology are presented. The diversity of symptoms and its rather uncommon occurrence often make the diagnosis of Eagle's syndrome elusive. The anatomy and embryology of the stylohyoid complex is discussed, as well as the symptoms, differential diagnosis, workup, and treatment of Eagle's syndrome. We hope to refamiliarize the clinician with this condition in order that it be considered in the assessment of patients with craniofacial pain.

Adult↗
PubMed1992

Obstructive sleep apnea.

Obstructive sleep apnea represents a common disorder with potentially high morbidity and mortality. Its clinical significance and treatment options have not been fully defined. Excessive daytime sleepiness and the cardiovascular complications of obstructive sleep apnea constitute a significant public health problem. Clinical features and treatment are discussed.

Female↗
PubMed1991

Linkage of an Alzheimer disease susceptibility locus to markers on human chromosome 21.

We assessed linkage between Alzheimer disease (AD) and restriction fragment length polymorphisms (RFLPs) from human chromosome 21 in 8 families selected because of multiple occurrences of AD and large size. Sib-pair analysis demonstrated significant evidence for linkage between 2 markers (D21S1 and D21S11) and disease. Two markers, D21S13 and D21S52, did not yield evidence in favor of linkage to disease and a 5th, D21S16, was uninformative. The results confirm that a susceptibility locus for Alzheimer disease is located on chromosome 21. In contrast to other investigators who demonstrated linkage between AD and chromosome 21 loci, we found evidence in favor of linkage in both late- (greater than age 65) and early-onset families.

Alzheimer Disease↗
PubMed1991

Differential expression of two genes for 1-aminocyclopropane-1-carboxylate synthase in tomato fruits.

1-Aminocyclopropane-1-carboxylate synthase (ACC synthase; S-adenosyl-L-methionine methylthioadenosine-lyase, EC 4.4.1.14) is the regulated enzyme in the biosynthetic pathway of the plant hormone ethylene. A full-length cDNA encoding this enzyme has been cloned from tomato fruits [Van Der Straeten, D., Van Wiemeersch, L., Goodman, H. M. & Van Montagu, M. Proc. Natl. Acad. Sci. USA (1990) 87, 4859-4863]. We report here the complete nucleotide and derived amino acid sequences of a cDNA encoding a second isoform of ACC synthase from tomato fruits. The cDNAs coding for both isoforms contain highly conserved regions that are surrounded by regions of low homology, especially at the 5' and 3' ends. Gene-specific probes were constructed to examine the expression of transcripts encoding the two ACC synthase isoforms under two conditions of enhanced ethylene formation--namely, during fruit ripening and in response to mechanical stress (wounding). The level of mRNA encoding both isoforms, ACC synthase 1 and 2, increased during ripening. In contrast, wounding caused an increase in only the level of mRNA coding for ACC synthase 1. Blot analysis of genomic DNA digested with restriction enzymes confirmed that ACC synthase 1 and 2 are encoded by different genes.

Amino Acid Sequence↗
PubMed1991

Gross efficiency responses to exercise conditioning in adult males of various ages.

This study investigated gross efficiency changes in a group of 60 adult males (mean age 39.2 +/- 1.2 years) resulting from endurance training and age-related responses to such training in sub-groups (each n = 20) of younger (30.7 +/- 0.7 years), intermediate (38.3 +/- 0.5 years) and older (48.6 +/- 1.1 years) subjects. Gross efficiency (%) was calculated from work output, oxygen consumption and RER energy equivalents following 10 min standard cycle ergometry exercise at 100 W and 50 rev min-1. Measurements were made at pre-, mid- and post-8 months of training, which involved progressive walking/jogging activities designed to enhance endurance capacity. In the total group, VO2 decreased pre- to post-training from 2.15 +/- 0.02 to 1.93 +/- 0.01 1 min-1 (P less than 0.01). In the sub-groups, both the younger and older subjects showed a significantly reduced VO2, from 2.17 +/- 0.01 to 1.98 +/- 0.04 1 min-1 and 2.05 +/- 0.08 to 1.86 +/- 0.03 1 min-1 respectively (P less than 0.05), but no significant changes were noted at mid-training. In the intermediate age subjects, while there were trends towards a reduced VO2, none was significant. The ANOVA revealed increased mean gross efficiency in the total group from pre- (14.3 +/- 0.1%) to post- (15.5 +/- 0.2%) (P less than 0.05) but not at mid-training (14.8 +/- 0.2%). While similar trends were observed in the sub-groups, gross efficiency increases were not significant, although changes in gross efficiency were reflected in VO2. The findings suggest that during standardized exercise, oxygen cost may be reduced and gross efficiency increased in adult males following endurance training and that such changes may take place over a variety of age ranges.

Adult↗
PubMed1991

Keloids.

Keloids are a benign proliferative growth of dermal collagen usually resulting from an excessive tissue response to skin trauma in predisposed individuals. Herein is a review of the history, epidemiology, clinical evaluation, histopathology, immunological theories of progression, and treatment of keloids.

Adult↗
PubMed1978

Management of blunt pancreatic trauma. A report of 3 cases.

Three cases in which the sole injury was a major pancreatic laceration secondary to closed abdominal injury are presented, and the literature on major closed injuries of the pancreas is reviewed. The diagnosis, surgical management and complications of closed injuries of the pancreas are discussed. Delay in diagnosis, inadequate surgery and failure to recognize common complications of pancreatic injury are responsible for the current high mortality rates for this form of closed abdominal trauma.

Adult↗
PubMed1978

Serum insulin and glucose response to graded exercise in adults. Part I: the influence of fitness status.

The effect of acute exercise upon serum immunoreactive insulin levels (IRI) and serum glucose concentrations (GC) was studied in groups of middle-aged men of contrasting physical fitness status. Two groups of subjects, one active and one sedentary (both N = 11, mean age 44 years), performed a graded cycle ergometer exercise test in the post-absorptive state. Venous blood samples were taken at rest, during low and high work intensities, and after recovery. The response of serum IRI to exercise was similar in both groups of subjects with significant increases observed during exercise followed by a return to resting values during recovery. However, the magnitude of serum IRI response was lower in the active group. In contrast, the sedentary group demonstrated little or no change in serum GC during exercise, whereas significant increases in serum GC were observed during exercise in the active group.

Adult↗
PubMed1978

Serum insulin and glucose response to graded exercise in adults. Part II. The effect of exercise conditioning.

The effect of conditioning to severe exercise upon serum immunoreactive insulin levels (IRI) and serum glucose concentrations (GC) was studied in active and sedentary groups of middle-aged men. The responses of serum IRI and serum GC were determined during graded cycle ergometer exercise which required similar low and high relative work intensities, before (pre) and after (post) a four month physical fitness programme. Both groups demonstrated a marked decline in serum IRI during high intensity exercise from pre to post tests, and a tendency to maintain serum, GC (sedentary group) or elevate serum GC (active group) during exercise, following the conditioning programme. The data provides evidence of a bi-directional response of serum IRI and serum GC to graded exercise, with only minor modifications in the response patterns resulting from exercise conditioning.

Blood Glucose↗