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Biomedical subjects

C P Brown

Publications and source records attributed to C P Brown.

At least 19 recordsLinked to original sources
PubMed1999

Utilizing hemodynamic delay and dispersion to detect fMRI signal change without auditory interference: the behavior interleaved gradients technique.

A major problem associated with the use of functional magnetic resonance imaging (fMRI) is the attendant gradient noise, which causes undesirable auditory system stimulation. A method is presented here that delays data acquisition to a period immediately after task completion, utilizing the physiological delay and dispersion between neuronal activity and its resulting hemodynamic lag. Subjects performed finger movements with the gradients off, followed by a rest period with the gradients on. This resulted in task-related signals comparable to those obtained with concurrent task performance and image data acquisition. This behavior interleaved gradients technique may be particularly useful for the studies involving auditory stimulation or overt verbal responses.

Acoustic Stimulation↗
PubMed1998

Influence of Neotyphodium coenophialum on copper concentration in tall fescue.

Poor performance of livestock that graze tall fescue (Festuca arundinacea Schreb.) has been associated with the endophyte fungus Neotyphodium coenophialum [Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). Recent evidence suggests lowered Cu status and a depression of Cu-related immune function in steers that graze endophyte-infected (E+) tall fescue. Greenhouse and field studies investigated relationships between the endophyte and Cu concentrations in tall fescue. Seventeen infected 'Kenhy' clones were divided, and one plant of each pair was treated three times with Benomyl to remove the endophyte (E-). Plants were watered with nutrient solution in a greenhouse for 6 mo before sampling. Copper concentrations were greater (P < .001) in E- than in E+ clones (3.4 vs 2.8 microg/g; SE, .06). In the second greenhouse experiment, genetically similar E+ and E- 'Kentucky'-31 (KY-31) and 'Georgia Jessup' were grown from seed and fertilized with nutrient solution to produce mature plants. Copper concentrations were higher (P < .05) in E- than in E+ tall fescue (8.6 vs 7.6 microg/g; SE, .3). In a field plot experiment in Texas, E+ and E- KY-31 were grown with 0, 50, and 100% replacement of potential evapotranspiration. By September, Cu concentrations were higher (P < .05) in E- than in E+ tall fescue (7.3 vs 6.6 microg/g; SE, .2). In pasture experiments, KY-31 E+ (> 70% infection level) and E- (< 5% infection level) tall fescue were grown in Virginia at two locations with three rates of N fertilizer. Copper concentrations were higher (P < .05) in E- than in E+ tall fescue (4.8 vs 4.5 microg/g; SE, .1) and increased (P < .01) linearly in response to N. Our data demonstrate that the presence of the endophyte is associated with lower Cu concentrations in tall fescue, which may contribute to lowered Cu status in animals and thus contribute to the etiology of fescue toxicity.

Acremonium↗
PubMed1997

Effects of sex and MK-801 on auditory-processing deficits associated with developmental microgyric lesions in rats.

Neonatally induced microgyric lesions produce defects in rapid auditory processing in adult male rats. Given that females across species are less susceptible to the deleterious effects of neural injury and that treatment with neuroprotective agents at the time of injury can reduce neural damage, the authors tested the effects of sex and neuroprotectant exposure on the behavioral consequences of microgyric lesions in rats. Results showed that sham but not microgyric males were able to perform the task at the fastest rate of stimulus presentation. Microgyric females, in contrast, discriminated at all stimulus conditions and did not differ from female shams. Microgyric males treated with MK-801 had reduced cortical damage and performed the discrimination at the fastest condition. Results suggest that females are less susceptible to the behavioral effects of neocortical microgyria and that MK-801 may ameliorate the behavioral consequences of these lesions in male rats.

Animals↗
PubMed1995

Prevalence of enteric parasitic infection among HIV-infected attendees of an inner city AIDS clinic.

One hundred individuals confirmed to be infected with the human immunodeficiency virus (HIV), volunteered to participate in a pilot study comparing clinical status and enteric parasite burden with race, age, CD4 levels, risk factors and sexual practice. The prevalence of enteric parasites was 55 (55%) for Giardia lamblia, 6 (6%) for Cryptosporidium, 10 (10%) for Isospora belli and 3 (3%) for Entamoeba histolytica. There was no associations between demographic variables and the presence of parasites. The presence of giardia was significantly associated with anal-penile sex (P = .017), with an odds ratio of 2.9. A logistic regression model was used to explain the presence of any parasite by a number of sexual practices. The only practice found to be significant was anal-penile sex, which substantially increased the likelihood of the presence of the parasites. In this regression, 38.5% of pairs were concordant and 12.2% were discordant. These findings differed from surveys conducted in similar populations. The significance of this will be discussed in the context of medical service provision to this and similar populations.

Adult↗
PubMed1994

Corn supplementation of lambs grazing alfalfa.

We investigated the effects of supplementing Rambouillet x Suffolk wether lambs grazing irrigated 'Cimarron' alfalfa (Medicago sativa L.) with three levels (0 [C0], 123 [C123], and 247 [C247] g of DM.lamb-1.d-1) of cracked corn. Each treatment group also received 190 g of a supplement designed to prevent bloat. Replicated pastures (three per treatment) grown on a fine, mixed, thermic Torretic Paleustoll soil were grazed rotationally (forage plus supplement allowance of 6.5% of BW/d) by lambs for 85 d during spring 1992. Supplemental corn levels were analyzed as single degree of freedom contrasts for linear and quadratic effects. At the start of the experiment, lambs weighed 30.7 +/- .32 kg. Average daily gains for C0 C123, and C247 were 141, 154, and 169 g/d, respectively. Lamb production per hectare increased quadratically (P < .01) with increasing corn level (C0 [716 kg of lamb/ha], C123 [816 kg of lamb/ha], and C247 [964 kg of lamb/ha]). Supplementation with C247 vs C0 increased carcass weights (11%), dressing percentage (6%), and backfat thickness (30%). Plasma urea N (PUN) concentrations did not differ (P > .10) between C0 and C123 after 27 d of corn supplementation, but after 75 d PUN concentrations between C0 and C123 had decreased (P < .10) by 11%. For C247, PUN concentrations after 27 and 75 d of corn supplementation had decreased (P < .10) by 17 and 18%, respectively, compared with C0. Plasma urea N concentrations increased (P < .01) linearly (r2 = .93) with an increase in digestible CP:DE ratio (DP:DE).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1994

HIV-1 seroprevalence in an inner-city public hospital.

In a hospital-based seroprevalence survey for human immunodeficiency virus type 1 (HIV-1) infection, a stratified sampling method based on age and gender was used to collect 5429 blood samples at an inner-city hospital. Sentinel Hospital Surveillance System (SHSS) criteria developed by the Centers for Disease Control and Prevention were used to classify patient diagnoses into two categories by the likelihood of being associated with HIV-1 infection. The two categories were those with high likelihood of association with HIV-1 (SHSS-ineligible) and those with low likelihood of association with HIV-1 infection (SHSS-eligible). Of the 5429 blood samples, 4262 were SHSS-eligible and 1167 were SHSS-ineligible. After personal identifies were removed, specimens were tested by ELISA and confirmed by Western blot analysis. The overall prevalence rate of HIV-1 infection was 0.98%. The seroprevalence rate was almost 2.6 times higher in high-association patients compared with low-association patients (1.89% versus 0.73%, P < .001). Results from this study indicate a high unsuspected HIV-1 seroprevalence rate in a subpopulation (SHSS-eligible) considered to have diagnoses with low likelihood of association with HIV-1 infection. These patients may better approximate HIV-1 seroprevalence in the general population of the area served by the hospital than would a sample of all patients. Monitoring HIV-1 seroprevalence in the SHSS-eligible group will be a useful measure for community serosurveillance for HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Functional lateralization for auditory temporal processing in male and female rats.

In 3 studies adult male rats showed significantly better discrimination of tone sequences with the right ear than with the left ear. This result parallels similar findings of left-hemisphere specialization for auditory temporal processing in humans and nonhuman primates. Furthermore, because clinical evidence supports a link between specialization of the left hemisphere for auditory temporal processing and for speech processing, these results may reflect evolutionary precursors to left-hemisphere language specialization. Because male rats showed a stronger ear advantage than female rats, the findings may relate to evidence of a stronger right ear advantage in men than in women. Finally, results suggest that neonatal handling enhances lateralization for auditory temporal processing in both sexes. Combined results implicate neuroendocrine mechanisms as important factors in the development of lateralization for auditory temporal processing.

Animals↗
PubMed1993

Developmental language disorders: evidence for a basic processing deficit.

Although there is still some disagreement whether developmental reading and language disorders are neurologically based, recent research provides increasing evidence that these disorders may be due to both abnormal cerebral lateralization patterns and neurological pathology at the cellular level. Technological advances in the field of neuroscience have led to increasing knowledge about brain-behavior relationships, particularly in the area of higher cognitive functions. Hypotheses about the underlying causes of the functional deficits characterizing developmental language and reading disorders are now focusing on specific neurological processing mechanisms, the disruption of which may be at the heart of these disorders.

Adolescent↗
PubMed1992

A novel technique for immunohistoperoxidase staining of unfixed whole joints of small animals.

A method has been developed to cut unfixed and undecalcified sections of rat paws from animals with adjuvant arthritis and to stain them by a biotin-avidin immunoperoxidase technique. Good tissue integrity and morphology throughout the immunohistochemical procedure were retained if the sections were first mounted on transparent sellotape. The method is illustrated with two monoclonal antibodies (mAb) and is generally applicable with any mAb or polyclonal antibody and with joints from other small animals. For rats with adjuvant arthritis it was found important to block endogenous peroxidase before immunostaining. Complete inhibition of this enzyme without loss of antigenicity was best achieved after application of the mAb and biotinylated anti-IgG conjugate to the unfixed tissue sections.

Animals↗
PubMed1990

A dental care programme for occasional dental attenders.

This study investigated the provision of dental care to primary schools in which many children were irregular or occasional dental attenders. The dental care programme was targeted at 9- to 11-year-old children in the two test schools, and comprised a series of dental health education lessons, followed by the offer of dental treatment within the school. This treatment was carried out using portable equipment set up in the medical room or spare classroom. Children in the control schools received a traditional school dental inspection and the offer of clinic-based treatment. The results showed that simple operative treatment could be satisfactorily provided on school premises, and by removing many barriers to dental care, could be considered appropriate in circumstances where there is a 'core, of children not receiving this care.

Child↗
PubMed1989

Cancer rate differentials between blacks and whites of three metropolitan areas.

This article presents a comparison of the cancer incidence and mortality rates for the populations of the metropolitan areas of Los Angeles, Atlanta, and Nashville. The results reveal that cancer of the lung, prostate, breast, and cervix should be of major concern to all, but especially to blacks and residents of Nashville. The findings have specific implications for the prevention of cancer in the black population of the United States.

Black People↗
PubMed1984

The excursion of the tendon of flexor pollicis longus and its relation to dynamic splintage.

In a cadaveric study the excursion of the flexor pollicis longus tendon has been measured over the proximal phalanx and metacarpal bones in relation to the angles of flexion of the interphalangeal (IP) and metacarpophalangeal (MP) joints. A small amount of tendon excursion is noted (1.3 mm for 10 degrees of IP joint flexion alone, 1.6 mm for 10 degrees of MP joint motion alone). It is emphasized that there is no tendon excursion over the proximal phalanx on MP joint motion. The significance of these measurements is considered in relation to current techniques of dynamic mobilization after tendon repair. Fixation of the MP joint and mobilization of the IP joint alone can achieve on an average a 70% increase in tendon excursion at the repair site over the proximal phalanx in comparison with dynamic splintage allowing free motion of both joints. The increase in excursion is greater in patients with more mobile MP joints.

Finger Joint↗
PubMed1983

Tissue and subcellular distribution of enzymes inactivating leupeptin.

Leupeptin, a proteinase inhibitor obtained from culture filtrates of Streptomyces sp., has been proposed as a valuable agent for the restriction of proteolysis in vivo. We have previously shown that mammalian tissues possess an enzymic system that is capable of inactivating leupeptin (Beynon RJ, Brown CP & Butler PE, 1981, Acta Biol. Med. Germ. 40, 1539-1546). This paper demonstrates the ubiquitous distribution of the inactivating system throughout mammalian tissues and provides evidence for the location of the enzyme(s) in the soluble fraction of the cell.

Animals↗