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Biomedical subjects

J A Brown

Publications and source records attributed to J A Brown.

At least 19 recordsLinked to original sources
PubMed1995

A mutation in the Schizosaccharomyces pombe rae1 gene causes defects in poly(A)+ RNA export and in the cytoskeleton.

A collection of fission yeast Schizosaccharomyces pombe conditional mutants was screened for defective nucleocytoplasmic transport of poly(A)+ RNA by fluorescence in situ hybridization. We identified a temperature-sensitive mutant that accumulated poly(A)+ RNA in the nucleus and have named it rae1-1, for ribonucleic acid export. All rae1-1 cells exhibit the defect in poly(A)+ RNA export within 30 min following a shift to the non-permissive temperature. In addition, in the rae1-1 mutant, actin and tubulin become disorganized, and cells undergo an irreversible cycle arrest. Results from experiments in which rae1-1 cells were arrested in various phases of the cell division cycle and then shifted to nonpermissive temperature suggest that cells are particularly vulnerable to loss of rae1 function during G2/M. However, the inability to export RNA from the nucleus to the cytoplasm was not limited to a particular phase of the cell division cycle. The rae1 gene was isolated by complementation and encodes a predicted protein of 352 amino acids with four beta-transducin/WD40 repeats.

Actins↗
PubMed1995

B7-1 and B7-2 costimulatory molecules activate differentially the Th1/Th2 developmental pathways: application to autoimmune disease therapy.

CD4 T helper precursor cells mature along two alternative pathways, Th1 and Th2. Here we show that these pathways are differentially activated by two costimulatory molecules, B7-1 and B7-2. Using anti-B7 antibodies, this developmental step was manipulated both in vitro and in vivo in experimental allergic encephalomyelitis (EAE). Anti-B7-1 reduced the incidence of disease while anti-B7-2 increased disease severity. Neither antibody affected overall T cell induction but rather altered cytokine profile. Administration of anti-B7-1 at immunization resulted in predominant generation of Th2 clones whose transfer both prevented induction of EAE and abrogated established disease. Since co-treatment with anti-IL-4 antibody prevented disease amelioration, costimulatory molecules may directly affect initial cytokine secretion. Thus, interaction of B7-1 and B7-2 with shared counterreceptors CD28 and CTLA-4 results in very different outcomes in clinical disease by influencing commitment of precursors to a Th1 or Th2 lineage.

Amino Acid Sequence↗
PubMed1995

Activation of class II MHC genes requires both the X box region and the class II transactivator (CIITA).

CIITA, a gene that can complement a transcriptional mutation of the major histocompatibility complex (MHC) class II genes, was tested for its ability to function as a coactivator, CIITA cDNA clones isolated showed alternative RNA splicing, but only one splice site combination was able to restore class II MHC gene expression. DNA-mediated transfection experiments showed that CIITA directs its activity through the X box element; the presence of CIITA leads to the formation of a higher order complex at the X box region; and CIITA contains a potent activation domain. These findings support the hypothesis that CIITA directly interacts with the MHC class II-specific transcription factors and is required for expression.

Alternative Splicing↗
PubMed1995

Regulation of manganese peroxidase gene transcription by hydrogen peroxide, chemical stress, and molecular oxygen.

The expression of manganese peroxidase (MnP) in nitrogen-limited cultures of the lignin-degrading fungus Phanerochaete chrysosporium is regulated at the level of gene transcription by H2O2 and various chemicals, including ethanol, sodium arsenite, and 2,4-dichlorophenol, as well as by Mn(II) and heat shock. Northern (RNA) blot analysis demonstrates that the addition of 1.0 mM H2O2 to 5-day-old cultures grown in the absence of Mn results in the appearance of mnp mRNA within 15 min. Higher levels of mnp mRNA are obtained with simultaneous induction by Mn and H2O2 than with H2O2 alone. Although neither MnP activity nor associated protein is detectable in H2O2-induced cultures grown in the absence of Mn, simultaneous induction with Mn and H2O2 results in a 1.6-fold increase in MnP activity compared with the MnP activity resulting from Mn induction alone. In the presence of Mn, purging of low-nitrogen cultures with 100% O2, in contrast to incubation under air, results in an increase in the accumulation of mnp mRNA and a 13-fold increase in MnP activity on day 5. However, in contrast to the effects of H2O2 and heat shock, O2 purging of Mn-deficient cultures results in negligible accumulation of mnp mRNA.

Biodegradation, Environmental↗
PubMed1995

Glomerular actions of arginine vasotocin in the in situ perfused trout kidney.

Recent measurements of plasma arginine vasotocin (AVT) in teleost fish suggest circulating concentrations of 10(-10)-10(-12)M. Previous studies of the renal actions of AVT in vivo suggest both diuretic and antidiuretic effects, but at unknown circulating concentrations. We have investigated the renal actions of 10(-9) and 10(-11) M AVT in vitro using an in situ perfused kidney preparation of rainbow trout (oncorhynchus mykiss). AVT increased vascular resistance (56%), reduced perfusate flow (P < 0.001), and increased interrenal aortic pressure (P < 0.001). AVT resulted in dose-dependent decreases in urine flow rates, glomerular filtration rates, and tubular transport maxima for glucose. AVT at 10(-11) M reduced relative free water clearances (P < 0.01), but urine/plasma inulin ratios were unchanged, whereas 10(-9)M AVT reduced urine/plasma inulin ratios (P < 0.01) and increased relative free water clearances (P < 0.05). The filtering population of glomeruli was reduced by both 10(-11) and 10(-9)M AVT to approximately one-third of the glomeruli, and a similar population of arterially perfused but nonfiltering glomeruli emerged. These results demonstrate that physiological concentrations of AVT have potent glomerular antidiuretic action in the trout, reducing the number of functional glomeruli, and imply reduced individual nephron filtration rates.

Animals↗
PubMed1995

Posterior plating of the cervical spine.

A retrospective review of 36 patients treated with posterior cervical plating and autogenous iliac crest bone graft was performed to evaluate the results of posterior cervical plating in terms of fusion, outcome, technique, and complications. Numerous methods of cervical stabilization have been described with varying fusion rates and complications. Compared to wiring techniques, there is little information concerning the results of posterior cervical plating. Thirty-six patients with cervical instability underwent posterior plating with lateral mass screw fixation. Twenty-two had acute traumatic instability, four had late traumatic instability, six had metastatic disease, and four had postlaminectomy spondylotic instability. A Minerva brace was worn postoperatively for 3 months and fusion was assessed by bone incorporation on plain films, stable dynamic flexion-extension views, and absence of neck pain. Postoperative MRI and CT imaging was assessed in those patients who underwent these modalities. Fusion occurred at an average of 3 months in all patients. One patient demonstrated postoperative neurologic deterioration, but this resolved with subsequent decompression. Six patients had loosening of short, unicortical screws, but this did not affect the fusion result in five of these patients. The use of titanium implants allowed operative CT and MR imaging without the excessive artifact associated with stainless steel implants. Posterior cervical plating with lateral mass fixation and bone grafting offers a reliable method of achieving fusion. Bicortical lateral mass screws are less likely to loosen than unicortical screws, and no major complications occurred.

Adolescent↗
PubMed1994

Aneuploidy and aneusomy of chromosome 7 detected by fluorescence in situ hybridization are markers of poor prognosis in prostate cancer.

Fluorescence in situ hybridization is a new methodology which can be used to detect cytogenetic anomalies within interphase tumor cells. We used this technique to identify nonrandom numeric chromosomal alterations in tumor specimens from the poorest prognosis patients with pathological stages T2N0M0 and T3N0M0 prostate carcinomas. Among 1368 patients treated by radical prostatectomy, 25 study patients were ascertained who died most quickly from progressive prostate carcinoma within 3 years of diagnosis and surgery. Tumors from 25 control patients who survival for more than 5 years and who were matched for age, tumor histological grade, and pathological stage also were evaluated. The tumors from all 25 (100%) poor prognosis patients and from 11 of 25 (44%) control patients were found to be aneuploid by fluorescence in situ hybridization (P < 0.0001). Alterations of chromosome 7 were observed in 24 of the tumors (96%) from the poor prognosis patients versus 3 tumors (12%) from the control group (P < 0.0001). Moreover, a characteristic aneuploidy pattern with multiple abnormal chromosomes and a hypertetrasomic population was generally found in tumors from the poor prognosis patients. This preliminary study suggests that fluorescence in situ hybridization studies of prostate cancer specimens may help to identify those patients at highest risk for early cancer death.

Aged↗
PubMed1994

Potential markers of prostate cancer aggressiveness detected by fluorescence in situ hybridization in needle biopsies.

Fluorescence in situ hybridization (FISH) with centromere-specific probes for chromosomes 7, 8, 11, and 12 was used to evaluate multiple 18-gauge needle biopsy cores from 50 randomly selected radical prostatectomy specimens. FISH analysis detected 26 diploid (52%), 7 tetraploid (14%), and 17 aneuploid tumors (34%). The FISH results were concordant with flow cytometric (FCM) DNA content measurements of the corresponding prostatectomy specimens for 31 tumors. For the 19 FISH/FCM discordant tumors, FISH was more sensitive than FCM for detecting ploidy anomalies. Common numerical chromosome alterations were gains of chromosomes 7 and 8, which were found in 13 (76%) and 10 (59%) aneuploid tumors, respectively. Gain of chromosome 7 was strongly associated with higher Gleason score (> or = 8) (P < 0.0001) and with advanced tumor pathological stages (stages T3 + T4; P < 0.01). Gain of chromosome 8 also correlated with higher Gleason score (P < 0.01). FISH showed intratumoral ploidy heterogeneity in 3 of 41 (7%) studied tumors. Among 17 noncancerous adjacent tissue specimens, chromosome alterations were observed in one, which contained high-grade prostatic intraepithelial neoplasia. Combined FISH and fluorescent leukocyte common antigen staining showed that infiltrating leukocytes do not contribute to the observed gains of chromosomes 7 and 8 in prostate cancer tissue. These results demonstrate that (a) FISH analysis of prostate needle biopsy-sized specimens can be a practical, sensitive method for determination of nuclear ploidy and numerical chromosome alterations; and (b) gains of chromosomes 7 and 8 are common numerical alterations of prostate cancer cells and may be potential markers of tumor behavior and patient prognosis.

Biopsy, Needle↗
PubMed1994

Catabolic hormones alone fail to reproduce the stress-induced efflux of amino acids.

OBJECTIVE: To determine the impact of catabolic hormones on the pattern of amino acid efflux from human skeletal muscle during stress. DESIGN: Cohort analytical study. SETTING: Burn intensive care unit and clinical research facility at a university hospital. PATIENTS: Five patients with severe burns and five healthy volunteers of similar size and age. INTERVENTIONS AND MEASUREMENTS: The net balance of amino acids across the leg was determined in five healthy volunteers prior to and following a 2-hour infusion of the catabolic hormones epinephrine, cortisol, and glucagon into the femoral artery. These results were compared with amino acid net balance measurements in five severely burned patients. RESULTS: Hormonal simulation of stress in the normal volunteers increased glutamine efflux from the leg to an extent similar to that of the burn patients. Alanine efflux, however, was not affected by the hormonal infusion. Because alanine efflux constituted a major proportion of the total peripheral amino acid catabolism in the burn patients, there was significantly less total amino acid nitrogen loss from the healthy volunteers receiving the stress hormones. CONCLUSIONS: Catabolic hormones alone fail to reproduce the stress-induced pattern and quantity of amino acid efflux from human skeletal muscle. This discrepancy is largely due to an unresponsiveness of alanine to hormonally induced muscle protein catabolism.

Adult↗
PubMed1994

Comparative genomic hybridization, allelic imbalance, and fluorescence in situ hybridization on chromosome 8 in prostate cancer.

Due to problems with primary tumor cell culture, conventional cytogenetics has yielded little insightful information on chromosomal alterations in prostate cancer. The primary aim of this study was to define the ability of comparative genomic hybridization (CGH) to detect and map genetic deletions in prostate tumors. A secondary aim was to apply multiple assays to individual tumors as a means of deciphering the mechanisms of genetic alterations in prostate cancer. CGH results were compared with allelic imbalance measurements at 29 distinct loci on chromosome 8 in 18 specimens (17 malignant and 1 benign). CGH detected no changes in cases where all informative PCR/RFLP loci were retained and detected all p arm deletions consisting of at least two loci. We estimate that in this study, the smallest deletions detected by CGH were approximately 20-30 cM. Physical mapping of subchromosomal arm deletions by CGH correlated well with allelic imbalance mapping by PCR/RFLP: The data agreed at 88% of loci on 8p and 92% of loci on 8q. Fluorescence in situ hybridization (FISH) with multiple centromere probes and DNA content flow cytometry (FCM) also was performed on selected specimens. FISH revealed two cases of chromosome 8 aneusomy. In these two cases and three others, CGH showed simultaneous p arm deletion and q arm gain, suggesting isochromosome 8q formation. Together, these data suggested that, simple chromosomal aberrations were responsible for allelic losses on 8p and allelic gains on 8q in a significant number of prostate tumors. We also used CGH to examine relative DNA sequence copy number throughout the genome. Changes frequently associated with 8p loss include gains of 8q and losses of 13q, 16p, 16q, 17p, 17q, 20q, and Y. Cases with 8p loss exhibited five times the number of alterations as did cases without 8p loss.

Alleles↗
PubMed1994

Durable remissions following prolonged plasma exchange in thrombotic thrombocytopenic purpura.

We evaluated the efficacy of prolonged plasma exchange (PEX) for attaining durable remissions in thrombotic thrombocytopenic purpura (TTP). A recent review using steroids or PEX in initial management showed an 80% response rate but produced a relapse rate of 67-84%. Records of 50 patients starting PEX treatment for TTP/HUS were reviewed to identify and select those whose course of treatment had ended over 1 year earlier, whether or not the result was satisfactory. Records were evaluated for outcome, especially remission associated with treatment by "prolonged" plasma exchange. "Prolonged" was defined as continuing PEX beyond the stage where a normal platelet count was attained and until evidence of hemolysis was "minimal or at least compensated." If disease activity as judged by the criteria of hemolysis became accelerated or resumed, PEX was increased by volume of FFP (e.g., from 3 to 4 L) or rate (from less than daily to daily). Of 50 consecutive patients treated by PEX for TTP/HUS there were 40 cases after which at least one year had passed since the end of treatment. These 40 patients were evaluated for the results of treatment by PEX. Eight failed to achieve remission, dying in hospital within 1 month of admission. Twenty-eight achieved remission, sustained for 1 year or more in all. These are the reasons for our enthusiasm about this report. Four achieved remission lasting less than 1 year. Splenectomy was performed to obtain a sustained remission in one patient following administration of three 2 mg doses of vincristine and two relapses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Characterisation of angiotensin II binding to glomeruli from rainbow trout Oncorhynchus mykiss adapted to fresh water and seawater.

Specific binding of 125I-[Asn1, Val5]-angiotensin II to isolated glomeruli of freshwater-adapted and seawater-adapted rainbow trout, Oncorhynchus mykiss, reached a plateau after 20 min at 10 degrees and was displaced by nonradiolabelled [Asn1, Val5]-angiotensin II. Seawater adaptation increased the rate of dissociation of 125I-[Asn1, Val5]-angiotensin II from putative receptors. Competitive binding experiments revealed a single population of high-affinity receptors with a KD 0.3-0.4 x 10(-10) M, which was unchanged by seawater adaptation. Seawater adaptation did, however, reduce the density (Bmax) of the binding sites, which may reflect down-regulation by the higher plasma concentration of angiotensin II in seawater-adapted trout.

Adaptation, Physiological↗
PubMed1994

Persistence of Mycobacterium bovis in cattle.

Badgers represent a wildlife reservoir for bovine tuberculosis in Britain, which persists in the south west despite almost 20 years of badger control. The influence of landscape structure on patterns of badger urinatory behaviour may be one reason for the localized persistence of the disease in cattle within the region.

Animals↗
PubMed1994

Chromosomal aneusomies detected by fluorescent in situ hybridization analysis in clinically localized prostate carcinoma.

Fluorescent in situ hybridization using 12 chromosome enumeration probes (for chromosomes 4, 6, 7, 8, 9, 10, 11, 12, 17, 18, X and Y) was used to evaluate fresh tumor touch preparations from 40 randomly selected radical prostatectomy specimens. Of the tumors 16 (40%) contained chromosomal aneusomies. Chromosome 8 was aneusomic in 9 tumors (23%). Gain of chromosome 7 was observed in 8 tumors (20%). Chromosome 17 was aneusomic in 4 cases, and chromosomes 10, 11, 12, 18 and Y were each aneusomic twice. Loss of chromosome 9 was observed in 1 tumor. Chromosomes 4, 6, and X were never aneusomic. The percentage of monosomy 17 nuclei was 2 to 4 times the amount noted with the other autosomes for tumor and benign tissue. Computer analysis demonstrated that these signals contained twice the signal density and were significantly different (p < 0.0001) than the single diploid chromosome 17 signals. This result is consistent with homologous pairing of chromosome 17 in benign and neoplastic prostate tissue. Anomalies of chromosomes 8 and/or 7 were present in 14 of the 16 cases (88%) aneusomic by fluorescent in situ hybridization. High grade tumors were more likely to be aneuploid on fluorescent in situ hybridization (p < 0.001). Tumors with chromosome 8 aneusomies were of higher stage (p < 0.05). Fluorescent in situ hybridization is more sensitive than flow cytometry for the detection of aneusomy/aneuploidy. The prognostic relevance of these findings will require further investigation.

Aneuploidy↗
PubMed1994

The 5' flanking region of the rat beta 3-adrenergic receptor gene: divergence with the human gene and implications for species-specific gene expression.

beta 3-adrenergic receptor mRNAs exhibit species-specific expression (human vs. rodent) in distinct anatomical regions and appear to be expressed abundantly within rodent adipose tissue, but only at low levels within corresponding human tissues. In order to determine the genetic basis of the differential expression of the rat and human beta 3-adrenergic receptor genes, we cloned and sequence the rat gene and compared the 5' flanking regions of the two genes to identify potential discriminators in transcriptional regulation. We have found that the rat and human beta 3-adrenergic receptor 5' flanking regions are only 67% similar, unlike the close sequence similarity observed between the coding blocks (> 90%) and also observed between species for the 5' flanking regions of other beta-adrenergic receptor subtype genes (> 90%). In addition, the rat beta 3-adrenergic receptor gene lacks the four potential cAMP responsive elements identified within the 5' flanking region of the human receptor gene. The striking divergence in regulatory sequences between the rat and human beta 3-adrenergic receptor genes may potentially explain the differences in species-specific expression and tissue localization of the rat and human receptor mRNAs.

Animals↗
PubMed1994

Exercise-induced upper extremity rhabdomyolysis and myoglobinuria in shipboard military personnel.

During a 6-month Amphibious Task Force deployment to the Mediterranean Sea, five sailors and Marines were admitted to the ship's ward with severe upper extremity pain, elevated serum muscle enzymes, and a urinalysis dip positive for blood in the absence of microscopic hematuria-a finding highly suggestive of myoglobinuria. Each patient had begun a vigorous upper-extremity work-out program in the ship's weight room 1 to 3 days prior to development of symptoms. All responded well to vigorous intravenous hydration, mannitol diuresis, alkalinization of the urine, and skeletal muscle rest. No patient developed acute tubular necrosis. With increasing emphasis on physical fitness and body building, this condition is likely to become more frequent. The most important preventive measure is gradual conditioning. Awareness of this entity and early aggressive management are necessary to avoid the potentially severe complication of renal failure.

Adult↗
PubMed1994

Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays.

We selected 68 children who reported benefit from individually chosen sheets of coloured plastic placed upon the page when reading, and who used these regularly without prompting. These children viewed text illuminated by coloured light in an apparatus that allowed the separate manipulation of hue (colour) and saturation (depth of colour), at constant luminance. Many of the children reported improvements in perception when the light had a chromaticity within a limited range, which was different for each individual. A pair of plastic spectacle lenses ('experimental' lenses) was dyed so as to provide the appropriate chromaticity under conventional white (F3) fluorescent light. An additional pair was prepared having very similar colour but with a chromaticity outside the range in which perception was reported to improve ('control' lenses). Each pair was provided for 1 month in random order. The children kept diaries (36 completed) recording symptoms of eye-strain and headache. The children and those responsible for their assessment were unable reliably to distinguish 'experimental' from 'control' lenses. Nevertheless, symptoms were less frequent on days when the 'experimental' lenses were worn (P < 0.003).

Adolescent↗