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Biomedical subjects

B Young

Publications and source records attributed to B Young.

At least 91 records · Page 5Linked to original sources
PubMed1996

Narcolepsy secondary to fourth ventricular subependymoma.

BACKGROUND: Secondary (symptomatic) narcolepsy is rare. We report a subependymoma of the fourth ventricle associated with narcolepsy. The patient was a 50-year old woman with a long history of narcolepsy who died of colonic carcinoma with no cerebral metastasis. She was positive for HLA-DR2. At autopsy there was a tumour dorsal to the fourth ventricle which involved the midbrain tectum and rostral pons. Histologic examination of the tumour confirmed it to be a subependymoma. METHODS: Review of the previous cases of secondary narcolepsy was made with particular reference to the anatomical location of the lesions. RESULTS: Most of the lesions were found around the third ventricle and rostral brainstem. CONCLUSIONS: Knowing the anatomical localization of the pathological changes in secondary narcolepsy could be important in improving our understanding of its pathogenesis.

Cerebral Ventricle Neoplasms↗
PubMed1996

Analytical performance testing of an atrazine immunoassay system.

A rigorous performance evaluation of an enzyme immunoassay (EIA) kit for the determination of atrazine in water samples was undertaken. Eleven individual batches of samples containing standards and spiked drinking waters were analysed and precision, bias and limit of detection were measured using statistical analysis. The technique was shown to be capable of achieving performance criteria (a total standard deviation of less than 5% or 2.5 ng, whichever is the greater) demanded of modern analytical systems and achieved a limit of detection of 9.2 ng l-1. There was no statistically significant bias measured for drinking water samples. Interference tests showed that the atrazine immunoassay was not significantly affected in the pH range 4.0-8.0 or by drinking water matrix components (anions, cations and chlorination by-products), even at their maximum allowable concentrations. There was a small extent of cross-reaction with simazine and atrazine degradation products, but given the persistence of atrazine, through its resistance to hydrolysis, breakdown products are likely to be present at much lower concentrations than the parent compound in drinking water. Simazine may potentially be more problematic, so it would be prudent to monitor a proportion of samples for simazine to determine the extent to which this may be contributing to the 'atrazine' measured in drinking water samples using the EIA kit.

Atrazine↗
PubMed1996

Zinc supplementation is associated with improved neurologic recovery rate and visceral protein levels of patients with severe closed head injury.

Sixty-eight patients were entered into a randomized, prospective, double-blinded controlled trial of supplemental zinc versus standard zinc therapy to study the effects of zinc supplementation on neurologic recovery and nutritional/metabolic status after severe closed head injury. One month after injury, the mortality rates in the standard zinc group and the zinc-supplemented group were 26 and 12%, respectively. Glasgow Coma Scale (GCS) scores of the zinc-supplemented group exceeded the adjusted mean GCS score of the standard group at day 28 (p = 0.03). Mean motor GCS score levels of the zinc-supplemented group were significantly higher on days 15 and 21 than those of the control group (p = 0.005, p = 0.02). This trend continued on day 28 of the study (p = 0.09). The groups did not differ in serum zinc concentration, weight, energy expenditure, or total urinary nitrogen excretion after hospital admission. Mean 24-h urine zinc levels were significantly higher in the zinc-supplemented group at days 2 (p = 0.0001) and 10 (p = 0.01) after injury. Mean serum prealbumin concentrations were significantly higher in the zinc-supplemented group (p = 0.003) at 3 weeks after injury. A similar pattern was found for mean serum retinol binding protein level (p = 0.01). A significantly larger number of patients in the standard zinc group had craniotomies for evacuation of hematoma; thus a bias may have been present. The results of this study indicate that zinc supplementation during the immediate postinjury period is associated with improved rate of neurologic recovery and visceral protein concentrations for patients with severe closed head injury.

Adolescent↗
PubMed1996

Nuclear genes associated with a single Brassica CMS restorer locus influence transcripts of three different mitochondrial gene regions.

Previous studies have shown that the mitochondrial orf224/atp6 gene region is correlated with the Polima (pol) cytoplasmic male sterility (CMS) of Brassica napus. We now extend this correlation by showing that the effects of nuclear fertility restoration on orf224/atp6 transcripts cosegregate with the pol restorer gene Rfp1 in genetic crosses. We also show, however, that the recessive rfp1 allele, or a very tightly linked gene, acts as a dominant gene, designated Mmt (modifier of mitochondrial transcripts), in controlling the presence of additional smaller transcripts of the nad4 gene and a gene possibly involved in cytochrome c biogenesis. A common sequence, TTGTGG, maps immediately downstream of the 5' termini of both of the transcripts specific to plants with the Mmt gene and may serve as a recognition motif in generation of these transcripts. A similar sequence, TTGTTG, that may be recognized by the product of the alternate allele (or haplotype), Rfp1, is found within orf224 just downstream of the major 5' transcript terminus specific to fertility restored plants. Our results suggest that Rfp1/ Mmt is a novel nuclear genetic locus that affects the expression of multiple mitochondrial gene regions, with different alleles or haplotypes exerting specific effects on different mitochondrial genes.

Base Sequence↗
PubMed1996

Prediction of outcome in patients with anoxic coma: a clinical and electrophysiologic study.

OBJECTIVE: To evaluate and compare the predictive powers of clinical examination, electroencephalography (EEG), and studies of short-latency somatosensory evoked potentials in determining the prognosis in anoxic coma. DESIGN: Prospective case series of patients in anoxic coma, whose prognoses were uncertain based on previously established clinical criteria. The clinical features, EEG, and somatosensory evoked potentials results were correlated with outcome. SETTING: A 40-bed intensive care unit in a university teaching hospital. PATIENTS: Thirty-four consecutive patients admitted over a 2-yr period with anoxic coma as the principal diagnosis. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Twenty-seven (79%) patients never recovered consciousness and seven (21%) patients made a good recovery. One of six patients whose pupillary reflexes were present but whose other cranial nerve reflexes were absent on day 1 recovered, but none of the seven patients with these features still present on day 3 survived. None of the patients with motor responses of extension to painful stimuli or worse on days 1 or 3 recovered. The EEGs were classified into benign, uncertain, and malignant categories. The results of both EEG and somatosensory evoked potentials studies were strongly associated with outcome. With malignant EEG, the sensitivity was 74%, the specificity was 71%, and the positive predictive value was 90% [corrected] for the prediction of no recovery (death or persistent vegetative state). However, two patients with an initially malignant EEG eventually made a good recovery. The sensitivity for low amplitude or absent somatosensory evoked potentials for prediction of no recovery was 66%. There were no falsely pessimistic predictions with somatosensory evoked potentials, as all 18 patients with absent or low-amplitude responses had no recovery (specificity and positive predictive value were 100%). EEG and somatosensory evoked potentials studies were complementary to clinical examination in the determination of prognosis. Using a combined clinical and electrophysiologic approach, 63% of patients who had no recovery could be identified by day 3. Repeat EEG and somatosensory evoked potentials studies were of value in patients whose prognoses were uncertain, as their evolution invariably correlated with outcome. CONCLUSIONS: Based on the present data and a literature review, we propose that clinical examination combined with the results of EEG and somatosensory evoked potentials can be used to establish an early, definitive prognosis in a significant proportion of patients in anoxic coma. On day 3 or thereafter, patients with motor response of extension to pain or worse and malignant EEG, or those patients with flexor posturing or worse and bilaterally absent cortical somatosensory evoked potentials invariably have poor outcome. However, some patients with initially malignant EEG and normal somatosensory evoked potentials may recover and should be supported until their prognoses become more definitive.

Adolescent↗
PubMed1996

An analysis of perioperative surgical mortality and morbidity in the asymptomatic carotid atherosclerosis study. ACAS Investigators. Asymptomatic Carotid Atherosclerosis Study.

BACKGROUND AND PURPOSE: Our aim was to determine the perioperative morbidity and mortality rates of patients in the surgical arm of the multi-institutional, prospective, randomized Asymptomatic Carotid Atherosclerosis Study (ACAS). METHODS: Of 828 patients with carotid stenosis of 60% or more randomized to the surgical arm of ACAS, 721 underwent carotid endarterectomy (CEA). To qualify for participation, surgeons were required to have performed at least 12 CEAs per year with a combined neurological morbidity and mortality rate no greater than 3% for asymptomatic patients and 5% for symptomatic patients. Clinical centers had to demonstrate arteriographic morbidity less than 1% and mortality less than 0.1% per year. Primary events were stroke and death in the period between randomization and 30 days after surgery; secondary events were transient ischemic attack and myocardial infarction occurring in the same period. RESULTS: Of the 721 patients who underwent CEA, 1 died and 10 others had strokes within 30 days (1.5%). Of the 415 who underwent arteriography after randomization but before CEA, 5 (1.2%) suffered transient ischemic attack or stroke caused by arteriography. Thus, a nearly equal risk of stroke was associated with both CEA and carotid arteriography. In addition, 6 transient ischemic attacks and 3 myocardial infarctions could be directly linked to CEA, for a total CEA event rate of 2.6%. CONCLUSIONS: Patients with asymptomatic internal carotid artery stenosis exceeding 60% reduction in diameter who are acceptable candidates for elective operation may be considered for CEA if the combined arteriographic and surgical complication rates are 3% or less.

Anesthesia↗
PubMed1996

Effectiveness of individual and dyadic training protocols: the influence of trainee interaction anxiety.

The present study focuses on the consequences of the social dynamics that are created whenever two or more individuals are brought together for the purpose of training. An investigation of the role of individual differences in interaction anxiety on training outcomes demonstrated that the comparative effectiveness of dyadic versus individual protocols for computer-based training is moderate by trainees' level of interaction anxiety. Specifically, assignment to a dyadic protocol adversely affected the performance of high-interaction-anxiety participants but appeared to be advantageous for low-interaction-anxiety participants. Implications are discussed for changing the design and implementation of computer-based protocols for training groups and individuals in military and industrial training centers.

Adult↗
PubMed1996

Kaposi's sarcoma versus bacillary angiomatosis.

Persons with acquired immune deficiency syndrome (AIDS) are subject to a host of pathologic entities secondary to a depressed immune system. Kaposi's sarcoma frequently presents in this immunocompromised population and, therefore, diagnosis seems clinically straightforward. However, because of the prevalence of a strikingly similar infectious disease known as bacillary angiomatosis, skin biopsy of one or more lesions is crucial.

AIDS-Related Opportunistic Infections↗
PubMed1996

Demographics of brain metastasis.

Brain metastases are the most common intracranial tumor, significantly out-numbering primary brain tumors. The apparent increase in the ratio of brain metastases to primary tumors may be the result of a number of factors, including the possibility of a CNS "pharmacologic sanctuary," an aging population, and improved imaging studies. Among adults, the most common origins of brain metastasis include primary tumors of the lung, breast, skin (melanoma), and gastrointestinal tract. Among patients under 21 years of age, brain metastases most often arise from the sarcomas and germ cell tumors.

Adolescent↗
PubMed1995

Characterization of a t(10;11)(p13-14;q14-21) in the monoblastic cell line U937.

Previous analysis of the monoblastic cell line U937 has shown that several sublines contain a rearranged chromosome arm 11q. In order to determine the true nature of the rearrangement, fluorescence in situ hybridization (FISH) was carried out with various combinations of single copy anonymous markers, clones containing genes, a chromosome 10 paint, and an 11 centromere specific sequence. The rearrangement was deduced to be a reciprocal translocation between chromosomes 10 and 11 described as t(10;11)(p13-14;q14-21). The breakpoint on chromosome 11 is telomeric to the INT2 gene and the pHS11 probe at 11q13, and centromeric to the marker D11S36 localized to 11q14.3-q22.1 and the MLL gene at 11q23. Similar translocations have been reported in various acute leukemias, principally of the monocytic lineage, and also in T-cell precursor acute lymphocytic leukemias. Further characterization of the genetic rearrangements in U937 may lead to the isolation of genes important in leukemogenesis and provide an in vitro system for their study.

Chromosome Mapping↗
PubMed1995

3D conformal radiotherapy in the sagittal plane for centrally located thoracic tumors.

One hundred patients, recently treated at the University of California, San Francisco (UCSF) with radiotherapy for lung and esophageal cancer, were studied. Three subsets of these patients were defined based on tumor location to test how commonly the use of three-dimensional (3D) conformal radiotherapy (3DCRT) could improve significantly the delivery of high dosages. Comparisons were made between isodose distributions and dose volume histograms (DVHs) of patients' prior computed tomography (CT)-based treatment plans and newly generated 3D-based treatment plans. The use of beam angles outside the conventional horizontal plane did not significantly improve the dose distribution for patients if a peripheral mass was the target volume. Patients with a target volume involving the central thorax represented a subset (> 40% of the patients) who would have benefited the most from the use of nonconventional beam angles. In these patients, sagittal coplanar beams (sagittal Y technique) reduced the dose to 30% of the lung volume from 30% to 5%. Doses to the spinal cord and heart were slightly higher than with conventional techniques but were within the tolerance of normal tissues. The sagittal Y technique allows an escalation in total dose to the tumor without increasing dose to normal tissues beyond their tolerance.

Esophageal Neoplasms↗
PubMed1995

Colorectal carcinomas show frequent allelic loss on the long arm of chromosome 17 with evidence for a specific target region.

Allelic loss is a common mechanism of inactivation of tumour-suppressor genes in colorectal carcinomas. A number of known or putative tumour-suppressor genes including NF1, BRCA1, NME1, NME2 and prohibitin are present on the long arm of chromosome 17, and this region has not been extensively analysed in colorectal tumours. In this study 72 colorectal carcinomas were examined for allelic loss at eight loci on chromosome 17. Allelic loss was frequent both at the p53 locus, which is known to be important in colorectal carcinoma, and also telomeric to p53 on 17p. Allelic loss continued to be present in more than 50% of cases in the pericentromeric region and on proximal 17q to the marker LEW101 (D17S40) at 17q22-23. The most telomeric markers on 17q showed lower rates of allelic loss. Analysis of cases with partial deletions which did not include the p53 locus showed a common region of overlap of the deletions centred on D17S40. This suggests the target of allelic loss on 17q is a tumour-suppressor gene in this region.

Alleles↗
PubMed1995

Histopathology of the lung following intratracheal challenge with live Pseudomonas aeruginosa in intestinally immunized rats.

This paper examines the histology of rat lungs following intestinal immunization with killed mucoid Pseudomonas aeruginosa and subsequent pulmonary challenge with live P. aeruginosa. The lungs of non-immune challenged rats developed a confluent haemorrhagic pneumonitis with degeneration and sloughing of the mucosa of the airways; perivascular infiltration with mononuclear cells was apparent 1-2 h post-challenge; some neutrophils were present by 2 h post-challenge; by 12 h post-challenge oedema and intra-alveolar haemorrhage were prominent and Gram-negative organisms were seen in large quantities. In contrast, immunized challenged animals showed a pronounced neutrophilic response 1-2 h post challenge; by 12 h post-challenge patchy abscesses were apparent with resolving inflammation and no organisms visible. The findings suggest that intestinal immunization prevents the development of fatal P. aeruginosa infections in the lung by accelerating the recruitment of polymorphonuclear neutrophils.

Animals↗
PubMed1995

Modulation of experimental mesangial proliferative nephritis by interferon-gamma.

The observation that interferon-gamma (IFN-gamma) inhibits cell proliferation and collagen synthesis of a variety of cell types in culture has suggested that IFN-gamma may be useful in the treatment of fibroproliferative diseases. We administered recombinant IFN-gamma subcutaneously (10(5) U/kg/day for 3 days) to rats, beginning one day after the induction of mesangial proliferative nephritis with anti-Thy 1 antibody. IFN-gamma reduced glomerular (primarily mesangial) cell proliferation by 44% at days 2 and 4 compared to vehicle injected control rats with anti-Thy 1 nephritis (that is, proliferating cells that excluded the macrophage marker, ED-1, P < 0.001). Despite the inhibition of mesangial cell proliferation, IFN-gamma did not reduce the overall extracellular matrix deposition (by silver stain) or deposition of type IV collagen or laminin (by immunostaining) at 4 or 7 days, and glomerular type IV collagen and laminin mRNA levels were increased (1.4 and 1.7-fold) at 4 days relative to controls. The inability of IFN-gamma treatment to reduce mesangial matrix expansion may relate to the fact that IFN-gamma treated rats had a twofold increase in glomerular macrophages (that is, ED-1 positive cells, P < 0.001 at 2 and 4 days) with an increase in oxidant producing cells (day 2, P < 0.05) and a 1.6-fold increase in glomerular TGF-beta mRNA expression (4 days). This suggests that the effect of IFN-gamma to inhibit mesangial cell proliferation in glomerulonephritis may be offset by the ability of IFN-gamma to increase glomerular macrophages and TGF-beta expression. These data also show that IFN-gamma can partly dissociate the mesangial proliferative response from the extracellular matrix expansion in glomerulonephritis.

Animals↗
PubMed1995

The pathogenesis of tubulointerstitial disease associated with glomerulonephritis: the glomerular cytokine theory.

Numerous studies have suggested that tubulointerstitial disease has a major impact on the overall function and prognosis of glomerular disease. The mechanism by which tubulointerstitial disease develops in patients with glomerular and other diseases is unknown. In this review, we discuss the hypothesis that factors released from injured glomeruli act on tubules and interstitial cells to induce expression of chemotactic and adhesive factors that attract mononuclear cells into the interstitium. Evidence is provided that osteopontin is one candidate leukocyte adhesive factor involved in this process, but others are likely involved. The recruited leukocytes (primarily macrophages) then release inflammatory mediators that injure tubular cells and activate interstitial fibroblasts, resulting in tubulointerstitial injury with eventual fibrosis.

Animals↗