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Biomedical subjects

C Brown

Publications and source records attributed to C Brown.

At least 289 records · Page 16Linked to original sources
PubMed1995

Speech perception in children using the advanced Speak speech-processing strategy.

The Speak speech-processing strategy, developed by the University of Melbourne and commercialized by Cochlear Pty Limited for use in the new Spectra 22 speech processor, has been shown to provide improved speech perception for adults in both quiet and noisy situations. The present study evaluated the ability of children experienced in the use of the Multipeak (Mpeak) speech-processing strategy (implemented in the Nucleus Minisystem-22 cochlear implant) to adapt to and benefit from the advanced Speak speech-processing strategy (implemented in the Nucleus Spectra 22 speech processor). Twelve children were assessed using Mpeak and Speak over a period of 8 months. All of the children had over 1 year's previous experience with Mpeak, and all were able to score significantly on open-set word and sentence tests using the cochlear implant alone. Children were assessed with both live-voice and recorded speech materials, including Consonant-Nucleus-Consonant monosyllabic words and Speech Intelligibility Test sentences. Assessments were made in both quiet and in noise. Assessments were made at 3-week intervals to investigate the ability of the children to adapt to the new speech-processing strategy. For most of the children, a significant advantage was evident when using the Speak strategy as compared with Mpeak. For 4 of the children, there was no decrement in speech perception scores immediately following fitting with Speak. Eight of the children showed a small (10% to 20%) decrement in speech perception scores for between 3 and 6 weeks following the changeover to Speak. After 24 weeks' experience with Speak, 11 of the children had shown a steady increase in speech perception scores, with final Speak scores higher than for Mpeak. Only 1 child showed a significant decrement in speech perception with Speak, which did not recover to original Mpeak levels.

Adolescent↗
PubMed1995

Influence of four diets containing approximately 11% protein (dry weight) on uric acid, sodium urate, and ammonium urate urine activity product ratios of healthy beagles.

Urine activity product ratios of uric acid (APRua), sodium urate (APRna), and ammonium urate (APRau), and urinary excretion of 10 metabolites were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of consumption of 4 diets containing approximately 11% protein (dry weight) and various protein sources: a 72% moisture, casein-based diet; a 10% moisture, egg-based diet; a 72% moisture, chicken-based diet; and a 71% moisture, chicken-based, liver-flavored diet. Significantly (P < 0.05) higher APRua, APRna, and APRau were observed when dogs consumed the egg-based diet, compared with the other 3 diets; there were no differences in these ratios among the other 3 diets. Twenty-four-hour urinary excretions of chloride, potassium, phosphorus, and oxalic acid were significantly (P < 0.05) higher when dogs consumed the egg-based diet. Twenty-four-hour urinary excretions of sodium were significantly (P < 0.05) higher when dogs consumed the egg-based diet, compared with the casein-based diet and the chicken-based, liver-flavored diet, but were not significantly different between the egg-based diet and chicken-based diet. Twenty-four-hour urine volume was similar when dogs consumed the 4 diets. Twenty-four-hour endogenous creatinine clearance was significantly (P < 0.05) lower when dogs consumed the casein-based diet; there were no differences among the other 3 diets. Although consumption of all diets was associated with production of alkaline urine, the 24-hour urine pH was significantly (P < 0.05) higher when dogs consumed the egg-based diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

Diet effect on activity product ratios of uric acid, sodium urate, and ammonium urate in urine formed by healthy beagles.

Urine activity product ratios of uric acid, sodium urate, and ammonium urate and urinary excretion of metabolites were determined in 24-hour samples produced by 6 healthy Beagles during periods of consumption of a low-protein, casein-based diet (diet A) and a high-protein, meat-based diet (diet B). Comparison of effects of diet A with those of diet B revealed: significantly lower activity product ratios of uric acid (P = 0.025), sodium urate (P = 0.045), and ammonium urate (P = 0.0045); significantly lower 24-hour urinary excretion of uric acid (P = 0.002), ammonia (P = 0.0002), sodium (P = 0.01), calcium (P = 0.005), phosphorus (P = 0.0003), magnesium (P = 0.01), and oxalic acid (P = 0.004); significantly (P = 0.0001) higher 24-hour urine pH; and significantly (P = 0.01) lower endogenous creatinine clearance. These results suggest that consumption of diet A minimizes changes in urine that predispose dogs to uric acid, sodium urate, and ammonium urate urolithiasis.

Animals↗
PubMed1994

Crystallization and preliminary X-ray analysis of the Fab fragment of a human monoclonal IgM rheumatoid factor (2A2).

Crystals of the Fab fragment of a human monoclonal IgM rheumatoid factor have been obtained and are suitable for X-ray structure determination. This molecule, derived from the synovial B cells of a patient with rheumatoid arthritis, is an autoantibody with specificity for IgG Fc. The crystals have space group P2(1), cell dimensions a = 69.0 A, b = 76.6 A, c = 98.8 A and beta = 90.6 degrees, and diffract to a resolution of at least 2.8 A.

Antibodies, Monoclonal↗
PubMed1994

Mdj1p, a novel chaperone of the DnaJ family, is involved in mitochondrial biogenesis and protein folding.

Mdj1p, a novel member of the DnaJ family, is a heat shock protein that is associated with the inner membrane of mitochondria of Saccharomyces cerevisiae. Disruption of the MDJ1 gene resulted in a petite phenotype, loss of mitochondrial DNA, and inviability at 37 degrees C. Import of precursor proteins was not affected by a lack of Mdj1p, but folding of newly imported proteins was markedly impaired. The efficiency of refolding of a tester protein, dihydrofolate reductase, was significantly reduced in mitochondria lacking Mdj1p after incubation at elevated temperature. We conclude that Mdj1p is an important mitochondrial chaperone that participates in the folding of newly imported proteins and in the protection of proteins against heat denaturation and aggregation.

Amino Acid Sequence↗
PubMed1994

Physical activity and risk of breast cancer in the Framingham Heart Study.

The authors analyzed data from the Framingham Heart Study to evaluate the association between physical activity and breast cancer risk. Physical activity was ascertained by a physician-administered questionnaire from 2,321 women at the fourth biennial examination conducted in 1954-1956. Breast cancers were identified by self-report, surveillance of admissions to Framingham Union Hospital, and review of death records; all but one were histologically confirmed. During 28 years of follow-up, 117 breast cancer cases were diagnosed among the 2,307 women with data on physical activity and reproductive history (a potential confounder). Analysis was performed using Cox proportional hazards models with age as the underlying time variable. Models were adjusted for age at physical activity assessment, menopausal status, age at first pregnancy, parity, education, occupation, and alcohol ingestion. We observed a gradient of increasing risk of breast cancer with increasing physical activity (trend p = 0.06). The relative risk for women in the highest versus lowest activity quartile was 1.6 (95% confidence interval 0.9-3.0; p = 0.13). Although both moderate-to-heavy leisure and occupational activities were associated with an increased risk, the association was marginally significant only for leisure activity (p = 0.06). Our findings do not support a protective effect of physical activity during adulthood for breast cancer, but suggest an increased risk among more active women.

Adult↗
PubMed1994

Primary structure and function of a second essential member of the heterooligomeric TCP1 chaperonin complex of yeast, TCP1 beta.

A role for heterooligomeric TCP1 complex as a chaperonin in the eukaryotic cytosol has recently been suggested both by structural similarities with other chaperonins and by in vitro experiments showing it to mediate ATP-dependent folding of actin, tubulin, and luciferase. Here we present the primary structure of a second subunit of the complex and present genetic and functional analyses. The TCP1 beta amino acid sequence, predicted from the cloned gene, bears 35% identity to TCP1, termed here TCP1 alpha, containing the same highly conserved residues found in the collective sequence of chaperonins. The predicted product was identified as the fastest-migrating species of the TCP1 complex purified from soluble extracts of yeast. The TCP1 beta gene, like TCP1 alpha, is essential. Strains containing lethal disruptions of either gene could not be rescued by additional copies of the other. Spores bearing disruption of either gene germinated as single, large-budded cells. Similarly, large-budded cells were observed following shift to 37 degrees C of strains carrying temperature-sensitive mutations in either TCP1 alpha or TCP1 beta. The arrested cells contained replicated DNA present in single nuclear masses, associated with abnormal tubulin staining patterns, supporting the assertion that mitotic spindle formation and function are impaired. We conclude that TCP1 beta supplies an essential function that partially overlaps with that of TCP1 alpha in acting as a molecular chaperone in tubulin and spindle biogenesis.

Alleles↗
PubMed1994

The relation of reported alcohol ingestion to plasma levels of estrogens and androgens in premenopausal women (Maryland, United States).

We undertook a cross-sectional study in 107 premenopausal women in Maryland (United States) of alcohol intake and hormonal status in order to evaluate whether plasma hormone levels might mediate the reported positive relation between alcohol ingestion and breast cancer risk. Alcohol ingestion was estimated using a drinking pattern questionnaire, a food frequency questionnaire, and seven-day food records. Fasting blood specimens were collected on days 5-7, 12-15, and 21-23 of each participant's menstrual cycle and pooled to create follicular, midcycle, and luteal phase samples, respectively, for analysis. Estrone, estrone sulfate, estradiol, androstenedione, and dehydroepiandrosterone sulfate (DHEAS) in plasma were measured by radioimmunoassay, and sex-hormone binding globulin (SHBG) was measured by an immunoradiometric assay. After adjusting for age, weight, and total energy intake, alcohol ingestion was not associated with plasma estrogens in the follicular, midcycle, or luteal phases of the menstrual cycle, nor with the level of SHBG or DHEAS in plasma averaged from the three phases of the cycle. Alcohol, however, was significantly positively associated with the average level of plasma androstenedione. Based on these cross-sectional findings among premenopausal women, the increased risk of breast cancer related to alcohol ingestion does not appear to be mediated by elevated plasma estrogen levels. Androstenedione, however, may mediate the alcohol/breast cancer-association.

Adult↗
PubMed1994

Symptoms, health and illness behaviour in cystic fibrosis.

A health diary was administered for 28 consecutive days over 3 non-consecutive months to 53 children and adolescents with Cystic Fibrosis (age 11-17 years). Response rates were 96% for the first, 84% for the second and 58% for the third month. Ill health actions such as missing school or staying in bed, ranged from 0 to 21% of diary days and showed an apparent seasonal variation being highest in the month of May. Analysis of variance demonstrated significant association between health actions, use of additional medicines and disease severity although no such associations were found for worries and concerns and overall assessment of the day. Most were not very bothered by symptoms or complaints, the highest visual analogue score on a scale of 0-10 in a single patient was 2.4 for coughing. A striking finding was the disparity between perceived vulnerability and subsequent experience with predictions of common symptoms such as cough and shortness of breath scoring 4-5 times higher than actually experienced. These children and adolescents were coping very successfully with their disease although the disparity between perceived vulnerability and subsequent experience indicates some uncertainty about the effects of the disease and/or lack of understanding about medical therapy.

Activities of Daily Living↗
PubMed1994

Anti-A60 immunoglobulin G in the serodiagnosis of tuberculosis in HIV-seropositive and seronegative patients.

OBJECTIVE: A60 is a high molecular weight mycobacterial antigen complex. The detection of immunoglobulin (Ig) G antibodies to A60 has been advocated as a reasonably sensitive and specific test for active tuberculosis (TB). We aimed to compare the sensitivity of this test among HIV-seropositive and HIV-seronegative patients with pulmonary TB. METHODS: The presence and concentration of anti-A60 IgG antibodies was assessed by enzyme-linked immunosorbent assay in 208 HIV-seropositive and 91 HIV-seronegative Zaïrian patients with smear-positive pulmonary TB. The relationship between anti-A60 IgG levels and HIV serostatus, CD4+ lymphocyte counts, presence of clinical AIDS, and tuberculin skin test results was verified. RESULTS: Only 36.5% of the HIV-seropositive, compared with 69.2% of the HIV-seronegative patients had a positive anti-A60 IgG test (P < 0.00001). Among HIV-seropositive patients, anti-A60 IgG levels did not differ according to CD4+ lymphocyte counts, presence of clinical AIDS, or tuberculin skin test results. CONCLUSIONS: Among patients with pulmonary TB, the sensitivity of testing for anti-A60 IgG was much lower among HIV-seropositive than among HIV-seronegative patients, even from the early stages of HIV-related immunodeficiency. This limits the utility of anti-A60 IgG-antibody testing in the diagnosis of TB among HIV-infected patients.

AIDS-Related Opportunistic Infections↗
PubMed1994

Dexterity testing as a predictor of oral care ability.

OBJECTIVE: To examine a spectrum of elderly people to determine if hand function/dexterity measures can predict oral care ability. DESIGN: A series of dental, hand function, and dexterity measures were assessed by blinded examiners. Plaque scores were used as the criterion standard to assess plaque removal ability. PATIENTS: A convenience sample of 52, predominately male, elderly patients were recruited from the patient population of the Portland Veteran Affairs Medical Center and a community nursing home. Entry into the study required that the patient be able to give consent, be age 65 or older, have a minimum of six contiguous teeth or a minimum of 12 teeth total, be medically stable, have grossly adequate vision, and be able to hear and understand spoken instructions. OUTCOME MEASURES: The primary outcome measure was plaque score, as defined by the Turesky modification of the Quigley-Hein index. This was related to four dexterity tests (Jebsen-Taylor Hand Function test, Nine-hole Peg test, Box and Block test, Toothbrushing Ability test), a grip strength measure, and a cognitive measure (Allen Cognitive Level Test). RESULTS: Oral hygiene was significantly impaired among institutionalized elderly compared with outpatient elderly (P < 0.001), as was dexterity (P < 0.001). All dexterity tests correlated significantly with plaque score (Spearman rho: 0.49-0.77; P < 0.000). Forward stepwise regression analysis identified the Toothbrushing Ability Test (P < 0.0001) and the time spent brushing (P = 0.007) as the most significant predictors of plaque score. CONCLUSIONS: Results suggest oral hygiene ability is decreased among long term care residents, that dexterity tests can help identify patients unable to perform adequate oral self-care, and that these tests could be used to estimate brushing ability among elderly compromised patients.

Aged↗
PubMed1994

Effects of light on T-cells in HIV-infected subjects are not dependent on history of seasonal affective disorder.

In order to evaluate the effect of light on helper- and suppressor-T-cell counts in HIV-infected individuals, with and without a history of seasonal affective disorder (SAD), we treated 35 subjects with 45 min of light therapy in the morning, in a crossover design involving two 2 week treatment conditions: visible white light (half-peak band width, 530-620 nm; 10,000 lux) and visible red light (half-peak band width, 615-685 nm; 175 lux). We found small but significant differences between the two treatment conditions, with higher CD4 and CD8 levels during the white, as compared with the red, condition. There were no differences between baseline and treatment conditions. Both light treatment conditions were associated with significant mood improvements in the SAD, but not the non-SAD, subjects. There was no evidence that the higher cell counts seen under the bright light conditions were mediated by the effects of light on mood or on plasma cortisol levels. While the size of the light effect on T-cells renders questionable the potential therapeutic value of this treatment modality for HIV, the finding is of theoretical interest and is reassuring for those HIV-infected individuals who require light treatment for other reasons.

Adult↗
PubMed1994

Exposure to ambient light in patients with winter seasonal affective disorder.

In a study of the quantitative relationship between ambient light and depression in winter seasonal affective disorder, 13 outpatients and 13 normal comparison subjects each wore a light monitor for 1 week. The patients and normal subjects showed similar light exposure profiles; among the patients, severity of depression was inversely related to photoperiod, and there was a trend toward a correlation between greater severity of depression and later time of onset of morning light exposure. These findings suggest that vulnerability to short photoperiods may be related to depression in winter seasonal affective disorder.

Adult↗