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Biomedical subjects

C Brown

Publications and source records attributed to C Brown.

At least 19 recordsLinked to original sources
PubMed1992

Serratia marcescens endocarditis in a horse.

Serratia marcescens was the causative agent of bacterial endocarditis in a 2-year-old Arabian stallion. The horse was treated with broad-spectrum antibiotics for 1 month. The horse died several months after treatment was discontinued. To our knowledge, Serratia marcescens has not been reported as the cause of bacterial endocarditis in horses; however, multiple cases of bacterial endocarditis attributable to Serratia marcescens have been documented in human beings. The bacteria is most commonly isolated in immune-compromised patients.

Animals↗
PubMed1992

A glycine250--> aspartate substitution in the alpha-subunit of hexosaminidase A causes juvenile-onset Tay-Sachs disease in a Lebanese-Canadian family.

The mutation causing juvenile Tay-Sachs disease (TSD) in two sibs of Lebanese-Maronite origin is described. An mRNA-containing extract of cultured fibroblasts obtained from one of the probands was used as a template to amplify the coding sequence of the hexosaminidase A (Hex A) alpha-subunit. Sequencing of amplified cDNA fragments revealed a single alteration, guanine to adenine at nt 749 creating a G250D mutation. The mutation introduces a new recognition site for the restriction enzyme Eco RV, permitting identification of heterozygotes for this allele following PCR amplification and Eco RV digestion of exon 7 sequences from genomic DNA templates. In order to test the effect of this substitution, an in vitro mutagenized cDNA construct was introduced into a mammalian expression vector and transfected into monkey Cos-1 cells separately or along with a beta-cDNA expression vector. When the mutant alpha-cDNA was the only gene introduced into COS cells no enzymatic activity above endogenous COS cell activity was detected. Cotransfection of normal alpha-cDNA and beta-cDNA followed by immunoprecipitation of human Hex A resulted in 20-fold increase in the ratio between positive and negative (mock transfection) control values. This allowed the detection of some residual activity (12% of the positive control) when the mutant alpha-cDNA replaced its wild-type counterpart. The predicted protein environment in which the mutation occurs is compared to that of the adult-onset Tay-Sachs disease mutation caused by a Gly269-->Ser substitution in exon 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

An unidentified Toxoplasma-like tissue cyst-forming coccidium in a cat (Felis catus).

An unidentified coccidium was found in the brain and the heart of a 6-year-old female cat. Tissue cysts measured 40-130 x 40-112 microns and contained hundreds of bradyzoites measuring 4.2-5.2 x 1.2-1.8 microns. The cyst wall was 0.26-0.53 microns thick. Tissue cysts reacted positively with anti-Toxoplasma gondii serum but not with anti-Neospora caninum serum in an immunohistochemical test. Ultrastructurally, the cyst was aseptate and contained banana-shaped bradyzoites. Micronemes and rhoptries in bradyzoites were unlike those found in T. gondii bradyzoites. In the unidentified coccidium, the micronemes were arranged in rows and the rhoptries extended from the anterior tip to the posterior end.

Animals↗
PubMed1992

Age-associated changes and sex differences in urinary 6-sulphatoxymelatonin circadian rhythm in the rat.

The circadian rhythm of 6-sulphatoxymelatonin (aMT6s) excretion has been determined in male and female rats at 3 weeks and at 2, 8, 14 and 20 months of age. All animals have a pronounced circadian pattern of aMT6s excretion under a 12 hour dark: 12 hour light cycle. A significant increase in aMT6s excretion is observed from 3 weeks to 14 months followed by a decrease at 20 months. There is a highly significant correlation between aMT6s excretion and body weight (r = 0.73 for female rats and r = 0.74 for male rats; p values are all less than 0.001). Thus, a decrease in aMT6s excretion associated with increasing age occurs when body weight is taken into consideration. aMT6s excretion is higher in males at 3 weeks and at 2 and 8 months of ages. Urinary testosterone in male rats and estradiol in female rats increase from 3 weeks to 8 months and decrease at older ages. These data suggest that increase of body weight from 3 weeks to 14 months is an important factor responsible for the age-related alteration. The sex differences in aMT6s excretion in younger rats may be associated with their sex hormonal milieu.

Age Factors↗
PubMed1992

Do different fluorochrome labels give equivalent histomorphometric information?

Substances that bind calcium are given to determine where and how fast bone is forming. Several vital dyes are used (tetracycline, calcein, alizarin, xylenol), but it is not known whether the histomorphometric results they provide are equivalent. This work tests whether different fluorochrome labels give the same results when they are quantitatively measured. Twelve-week-old rats (n = 58) were divided into six groups and given double labels IP of calcein, tetracycline HCl, alizarin complexone, or xylenol using a 1-7-1 scheme. Two other groups received either calcein followed by tetracycline, or tetracycline followed by calcein. Our results show that (a) tetracycline hydrochloride leads to a significant underestimation of mineralizing surface when given as the second label, probably because of its weak fluorescence; (b) there were no differences among any of the non-tetracycline labels for any of the histomorphometric measurements; (c) there was no evidence of osteoblast suppression with any label; and (d) there was no evidence that tetracycline caused increased osteoblast resting periods.

Animals↗
PubMed1992

Engaging patients with alcohol problems in treatment: the first consultation.

This paper considers the impact of the first consultation at a specialist alcohol clinic on patients' perceptions of their drink problem and on their expectations of help from three sources: an alcohol clinic, general practitioners and Alcoholics Anonymous. At intake, males had higher expectations than females of help from the alcohol clinic while people in manual occupations and those in the 'less heavy' drinking category had higher expectations of general practitioner help than other patients. Change was found to occur during the first clinic consultation so that by the end of the session patients had raised their rating of problem severity and their expectations of help from the three sources examined. Overall, patient perceptions of the clinic assessment session were positive. The study highlights the importance of obtaining a full understanding of the process of engagement in treatment and indicates the potential of a clinical assessment to effect change in patient attitudes.

Adult↗
PubMed1992

The use of services for alcohol problems: general practitioner and specialist alcohol clinic.

A sample of 40 patients referred to a specialist alcohol clinic were given a full assessment by a clinician and then randomly allocated to one of two groups. The first group received continuing care from the clinic. The second group were returned to the management of their general practitioners who were offered specialist support in caring for their patients. Patients and general practitioners were followed-up 6 months after the clinic assessment. This paper reports on the uptake of clinic and general practice services by patients and examines the possible factors associated with continuing attendance, including patient attributes, service activity, patients' self-assessments of their drink problem and their expectations of help from services. Qualitative data is used to examine patients' perceptions and experiences of clinic and general practice-based care for drinking problems. The findings highlight some of the difficulties reported by patients in receiving help for their problems particularly from general practitioners.

Adult↗
PubMed1992

DNA probe technology: implications for service planning in Britain.

For certain genetic conditions DNA testing identifies carriers and determines the risk status of foetuses, thus helping parents to make more informed prenatal decisions. Data, collected from three genetic centres in England and Wales from August 1986 to July 1990, are used to describe trends in demand for DNA testing, the impact of DNA tests on carrier risk assessment, and the use of DNA tests in relation to pregnancy outcome. Altogether the data include 23,388 subjects and 681 pregnancies in 8738 families divided into five cohorts by year of entry and referral. The most frequent gene disorders referred to the genetic centres are currently being tested or will soon be tested. For these disorders the initial high level of activity has declined and may have reached steady state. Demand for DNA services is high for cystic fibrosis and Duchenne muscular dystrophy, intermediate for Huntington's disease, and low for adult polycystic kidney disease, phenylketonuria and tuberous sclerosis. Based on these findings we suggest that demand for DNA tests will be high in serious, untreatable and slow progressing conditions with early onset; intermediate for conditions affecting intellect and neurological integrity with later onset; and low for treatable, late-onset conditions, or those for which there is evidence of heterogeneity, and variable penetrance. It would be helpful to assess the extent to which this view of demand is confirmed when the new disorders being DNA tested are considered and for the pattern of activity of DNA testing for some types of cancer. Since no DNA centre could offer a fully comprehensive testing service, it is recommended that a structure is created to audit overall activity, assist in policy formulation, and influence supraregional service organisation, in order that the spread of DNA services be planned as effectively as possible. This structure would facilitate monitoring of the evolution of contract specifications agreed by commissioners and providers on a regional basis.

Adolescent↗
PubMed1992

Persistent diarrhea associated with AIDS.

Chronic diarrhea and wasting are very common manifestations of AIDS in adults in developing countries. Etiologic studies show that protozoa (including Cryptosporidium parvum, Isospora belli, and Enterocytozoon bieniusi) and Mycobacterium avium-intracellulara are the most frequently identified pathogens. Limited data in children suggest that common enteric pathogens are equally as likely in HIV+ and HIV- babies. Preliminary analysis of an ongoing longitudinal study of 469 babies born to mothers with known HIV serostatus in Kinshasa, Zaire, reveals progression of acute to persistent diarrhea is six times greater in HIV+ compared to HIV- babies, and 3.5 times greater in HIV- babies born of HIV+ mothers in comparison to HIV- babies with HIV- mothers. HIV+ babies were also at greater risk than HIV- babies to have recurrent episodes of diarrhea (RR = 2.3). Fifty percent of the deaths were due to acute or persistent diarrhea, and were strongly associated with HIV infection. Efforts to improve child survival in AIDS infected populations will need to address HIV infections in both mothers and infants.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Neurological complications of HIV-1-seropositive internal medicine inpatients in Kinshasa, Zaire.

Because little was known about the prevalence of neurological complications of human immunodeficiency virus type 1 (HIV-1) infection in Africa, we conducted a cross-sectional study among consecutive admissions to the internal medicine wards of Mama Yemo Hospital in Kinshasa, Zaire. Of the 196 patients studied, 104 (53%) were HIV-1 seropositive, of whom 50 (48%) had stage 3 and 49 (47%) had stage 4 HIV-1 infection according to the provisional WHO staging criteria for HIV infection. Neuropsychiatric abnormalities were present in 43 (41%) of 104 HIV-1-seropositive patients. Of the HIV-1-seropositive patients, 9 (8.7%; 95% confidence interval, 4-16%) were diagnosed as having possible HIV-1-associated dementia complex, 1 (1%) as having possible HIV-1 myelopathy, and 3 (2.7%) as having possible HIV-1-associated minor cognitive/motor disorder. Definitive diagnoses could not be made because there were no facilities for neuroimaging and neuropathology. Meningitis caused by cryptococcus was diagnosed in six (5.6%) and by Mycobacterium avium in two (2%) of the HIV-1 seropositive patients. Acute onset hemiplegia, believed to be due to stroke, was present in four (4%) of the HIV-1-seropositive patients. The prevalence of other central nervous system opportunistic infections and mass lesions, especially toxoplasmic encephalitis, could not be assessed. In this population of Zairian inpatients, the prevalence of neurological complications of HIV-1 infection was similar to that observed in industrialized countries among patients with advanced HIV disease.

Adult↗
PubMed1992

Scombroid fish poisoning. Underreporting and prevention among noncommercial recreational fishers.

Food-borne diseases, including those caused by seafood products, are common and greatly underreported sources of morbidity. In this article we review the epidemiology of scombroid fish poisoning and its possible relationship to the noncommercial and recreational catch and sale of fish. More than 20% of all fish sold in the United States is caught by sport fishers, and outbreaks of scombroid fish poisoning have involved improperly handled fish from private catches. We report an outbreak of scombroid fish poisoning among recreational fishers in California. The unregulated sale of recreationally caught fish for consumption and the prevention of scombrotoxism are discussed from the perspectives of public health agencies, clinicians, and the fishing public. Scientific and policy issues that require further attention are high-lighted.

Adult↗
PubMed1992

Diagnosis of HIV infection with instrument-free assays as an alternative to the ELISA and western blot testing strategy: an evaluation in Central Africa.

The efficiency of an alternative instrument-free testing strategy was evaluated using a membrane-based rapid screening assay (HIVCHEK and its new version HIVCHEK1 + 2) in serial combination with a particle agglutination assay (SERODIA-HIV). Among 1,054 Zairian individuals at high risk of HIV infection, 573 were Western blot-positive for HIV-1 (54.4%) and none were Western blot-positive for HIV-2. In this group, the sensitivities of the serial combination HIVCHEK plus SERODIA-HIV and HIVCHEK1 + 2 plus SERODIA-HIV were 98.1 and 98.2%, respectively, and the specificities were 99.6 and 99.5% compared with HIV-1 Western blot. The positive predictive values were 99.6% for HIVCHEK plus SERODIA-HIV and 99.5% for HIVCHEK1 + 2 plus SERODIA-HIV; the negative predictive values were 97.8 and 97.9%, respectively. Among 1,495 pregnant women, 90 were Western blot-positive for HIV-1 (6.0%), and 54 of 1,510 blood donors were HIV-1 Western blot-positive (3.6%). None were positive for HIV-2. The sensitivities of HIVCHEK plus SERODIA-HIV and HIVCHEK1 + 2 plus SERODIA-HIV in these groups were 98.6 and 99.3%, respectively, and the specificities were 99.8 and 99.7%. The positive and negative predictive values of HIVCHEK plus SERODIA-HIV were 96.6 and 99.9%, respectively, and they were 94.1 and 99.9%, respectively, for HIVCHEK1 + 2 plus SERODIA-HIV. These instrument-free testing strategies are efficient alternatives for serodiagnosis of HIV-1 infection, although their cost should be further reduced.

AIDS Serodiagnosis↗
PubMed1991

Vitronectin: effects on keratinocyte motility and inhibition of collagen-induced motility.

Epibolin, a plasma protein, was initially purified on the basis of its ability to enhance spreading of keratinocytes. It is now known that epibolin is identical to serum spreading factor, S protein, and vitronectin, and the current name for the protein is vitronectin. Studies of vitronectin on cultured keratinocytes showed that it caused spreading and epiboly but not cellular adhesion to the substratum. In studies with other types of cells, vitronectin increased migration of several types of cells in a Boyden chamber. Because some agents that enhance spreading and adhesion, such as collagen and fibronectin, also increase motility, we tested whether vitronectin increased motility of keratinocytes. By photographing and quantitating motility of keratinocytes plated on a bed of colloidal gold particles, we determined that vitronectin increased local movement of keratinocytes in a concentration-dependent fashion, resulting in clearing of gold particles in a circular pattern around the cells, but did not cause the production of tracks found in cultures plated on collagen or fibronectin. The small increases in clearing of the gold particles that occurred in the presence of vitronectin were abolished by antibody to vitronectin. Furthermore, the marked increase in motility produced by type I collagen was significantly reduced when the keratinocytes were treated with vitronectin. Antibody to vitronectin also abrogated the vitronectin-induced reduction in collagen-stimulated motility, confirming that this action was specific for vitronectin. Serum, which contains vitronectin, stimulated motility in a fashion identical to purified vitronectin, but serum lacking vitronectin was inactive. These studies show that vitronectin causes a localized increase in movement associated with spreading resulting in a halo around individual cells, that vitronectin does not enhance directional motility of keratinocytes in this assay but in contrast antagonizes such motility produced by collagen, and that vitronectin is the factor in serum responsible for this effect. The findings with vitronectin and collagen show that these agents stimulate different types of motility. The roles in wound healing of agents stimulating different types of motility are unclear and require further study.

Blood Physiological Phenomena↗
PubMed1991

Correlation between dermal interstitial immunoglobulin G and hypergammaglobulinemia.

The diffuse dermal immunofluorescence (DDIF) observed in human skin biopsies that is produced by fluorochrome-conjugated antisera reactive with human immunoglobulin G (IgG) has commonly been viewed in the past as an artifact of direct immunofluorescence microscopy. However, it has been our belief that DDIF, which has been observed in 14% of the biopsies processed in our laboratory, might represent an in vivo phenomenon of excess unbound dermal interstitial immunoglobulin G reflective of elevated serum IgG levels. To examine this hypothesis, we carried out a blinded prospective study of the frequency of DDIF in two groups of age- and sex-matched patients that differed with respect to the presence or absence of serum hypergammaglobulinemia (gamma globulin greater than 2.5 mg/100 ml). The subjective intensity of DDIF and the fluorescein-isothiocyanate (FITC) conjugated anti-human IgG antibody titer at which point DDIF disappeared were both compared with serum gamma globulin levels. Also, the amount of IgG that could be extracted from biopsy specimens by an overnight phosphate-buffered saline (PBS) elution procedure was quantified by solid-phase immunoassay. We noted a trend of increased DDIF intensity with increasing serum gamma globulin levels. In addition, there was a relatively weak but significant positive correlation between DDIF endpoint titers and serum gamma globulin levels (p = 0.05, r = 0.429). The strongest positive statistical correlation observed in the study was between the quantities of IgG that could be eluted from skin biopsies and serum gamma globulin levels (p = 0.01, r = 0.599). These findings suggest that DDIF is a true biologic phenomenon reflective of elevated serum gamma globulin levels and demonstrate that simple overnight elution of unbound dermal IgG can unmask the presence of disease-related, specifically-bound IgG.

Adult↗
PubMed1979

Apamin blocks certain neurotransmitter-induced increases in potassium permeability.

Apamin is a neurotoxic polypeptide of known structure isolated from bee venom. Shuba and coworkers have recently shown that it abolishes the hyperpolarising action of externally-applied ATP on visceral smooth muscle (guinea pig stomach and taenia coli) as well as the hyperpolarisation (inhibitory junction potential) that follows stimulation of the non-adrenergic inhibitory nerve supply to these tissues. As it has been proposed that ATP is the neurotransmitter involved in the latter response, Vladimirova and Shuba tentatively concluded that apamin is a specific postsynaptic blocking agent of this non-adrenergic, possibly 'purinergic', inhibition. We have confirmed the important observation that nanomolar concentrations of apamin reduce inhibition by ATP and by non-adrenergic nerve stimulation, but further experiments suggest that, rather than acting as a specific blocker of ATP receptors, apamin inhibits the increase in potassium permeability caused by a number of agents, including ATP.

Adenosine Triphosphate↗
PubMed1979

Endometrial cancer and estrogen use. Report of a large case-control study.

Our case-control study of the relation between estrogen use and endometrial cancer involved 451 cases and 888 controls. The overall risk of endometrial carcinoma was sixfold for estrogen users as compared with nonusers; long-term users (greater than five years) had a 15-fold risk. Excess risk was present for both diethylstilberstrol and conjugated estrogens. The risk associated with cyclic use was as great as that for continuous use. Increased risk was associated with estrogen use for all histologic grades of the tumor. The risk of advanced-stage carcinoma was fourfold for estrogen users, but rhe confidence interval was wide, and this question requires further study. Finally, this investigation contradicts the speculation that the association between this cancer and estrogen use can be explained by swifter diagnosis for estrogen users, misclassification of estrogen-related hyperplasia or treatment of early symptoms of the tumor with estrogen.

Clinical Trials as Topic↗