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Biomedical subjects

J Brown

Publications and source records attributed to J Brown.

At least 613 records · Page 34Linked to original sources
PubMed1992

Impact of hemodialysis on left and right ventricular Doppler diastolic filling indices.

Hemodialysis is associated with acute reduction in intravascular volume. To assess the impact of volume reduction on left and right ventricular diastolic filling indexes obtained by Doppler echocardiography, 24 patients on chronic hemodialysis were consecutively studied before, during, and immediately after one hemodialysis session. Twenty four normal sex and age-matched volunteers served as a control group. Study patients had abnormal diastolic indexes when compared to controls. At 2 hours of dialysis (mid dialysis) there was a significant decrease in peak early mitral flow velocity (E), no change in peak atrial filling velocity (A), and a reduction in the E/A ratio. The deceleration time of the mitral E wave also was prolonged compared to baseline. Similar findings were observed with respect to right ventricular filling indices. These changes occurred during the first 2 hours of dialysis and remained unaltered at end dialysis. When patients were subdivided according to weight loss, only the group that lost 1 or more kilograms had significant changes in the Doppler parameters of the left and right ventricle, as well as reduction of the left ventricular dimensions. These findings suggest that preload reduction is the main mechanism that accounts for acute changes in Doppler diastolic indices observed during hemodialysis.

Analysis of Variance↗
PubMed1992

The validity of instruments measuring tic severity in Tourette's syndrome.

By using four different scales that measure tic severity in Tourette's syndrome, three independent judges concurrently evaluated their validity and interjudge reliability in 20 affected individuals. The Yale Global Tic Severity Scale, Tourette's Syndrome Severity Scale, Tourette's Syndrome-Clinical Global Impression Scale, and the Hopkins Motor and Vocal Tic Scale were equally effective in determining overall severity and showed good interrater reliability. Both historical information and direct observation of the subject were shown to have a significant contribution towards the overall assessment of tic severity. With all instruments, tic symptom ratings were shown to be independent of those for either attention-deficit hyperactivity disorder or obsessive-compulsive disorder. A 67% incidence of behavioral problems and social difficulties was identified by the Child Behavior Checklist. Nevertheless, associations with tic severity were limited to areas showing interference with social relationships and school adjustments. These results extend the understanding of Tourette's syndrome severity scales and provide additional information necessary for the development of a unified rating scale.

Adolescent↗
PubMed1992

Intracellular regulation of cell adhesion to extracellular matrix components in murine B16 melanoma cells.

The involvement of signal transduction systems in the initial attachment of two murine B16 melanoma clones of differing metastatic potential to extracellular matrix components was examined to learn more of the early events in cell-matrix interaction. Clones of high and low metastatic capacity attached similarly in the absence of any stimulators, exhibiting a two phase time course of attachment with 100% attachment by 60 min. A slight difference in attachment characteristics between the clones was seen in response to phorbol ester stimulation, which significantly inhibited attachment of the low metastatic clone but which had no effect on the highly metastatic clone. Total protein kinase C activity and distribution was similar for both clones. Attachment of both clones was severely reduced, however, if intracellular calcium was elevated or intracellular calmodulin inhibited. This study suggests that signal transduction mechanisms are involved in melanoma cell attachment to matrix proteins and offers an approach to pharmacological manipulation of these cell-matrix interactions which may be relevant to reducing metastatic spread.

Animals↗
PubMed1992

Self-reports by alcohol and drug abuse inpatients: factors affecting reliability and validity.

The reliability and validity of self-report data regarding substance abuse has often been questioned. To determine how best to enhance the veracity of self-report, three factors which might affect self-report veracity were examined: alcohol status at time of interview; level of cognitive functioning; and method of self-report data collection. Subjects were 234 admissions to an inpatient substance abuse treatment unit. Self-report data were collected via both personal interview on the day of admission and and questionnaire within the first week of stay. Self-reports concerned use of alcohol, cocaine, and marijuana in the days preceding admission. Test-retest reliability for the questionnaire data produced reliability coefficients of 0.88, 0.91, and 0.88, for alcohol, cocaine, and marijuana, respectively. Variation in inter-test interval had virtually no effect upon reliability coefficients. Interview data were compared to toxicologic analyses of blood and urine samples collected on admission. Overall, this comparison showed self-reports to be valid, with a 97% agreement between verbal report and laboratory data for alcohol, 93% for cocaine, and 84% for marijuana. The comparison of interview data with questionnaire responses also showed self-reports to be valid: 90% agreement for alcohol, 93% for cocaine, and 81% for marijuana. Level of cognitive function did not influence the validity of self-reports for any of the three substances. Recent consumption of alcohol also had no statistically significant effect on the validity of self-reported marijuana use, regardless of the operational form of validity tested. However, BAC-negative subjects produced a significantly greater validity coefficient for self-reported cocaine use (kappa = 0.87) than did BAC-positive patients (kappa = 0.43), when interview data were compared with toxicologic measures. A similar finding was not uncovered when interview and questionnaire data were compared. An interaction between admission alcohol status and cognitive function was uncovered for cocaine self-reports when interview data was compared with toxicologic measures. The rate of agreement for alcohol-negative subjects is quite high for both cognitively impaired and unimpaired subjects (M = 93% and M = 94%, respectively) as well as for alcohol-positive, cognitively unimpaired subjects (M = 94%), but not for alcohol-positive, cognitively impaired subjects (M = 67%). Results are discussed in terms of threats to the validity of self-report and strategies for the optimization of response accuracy.

Adult↗
PubMed1992

Human monoclonal antibodies against Plasmodium falciparum: production, stabilization and characterization.

Nine human monoclonal antibodies (MoAbs) recognizing 7 different antigenic structures of blood-stages of the human malarial parasite P. falciparum (Pf) were produced by Epstein-Barr virus transformed B-cell lines (EBV-TCL) with or without fusion to the lymphoblastoid cell line KR4. The peripheral blood B-lymphocytes were obtained from 8 Gambian donors immune to Pf malaria. Two of the EBV-TCL could be expanded and maintained for more than 6 months but neither one could be cloned. Six additional EBV-TCL were stabilized after fusion with the KR4 lymphoblastoid cell line. All resulting hybridomas permitted easy cloning. Some of the MoAbs produced distinct fluorescent staining patterns of asexual Pf blood-stage parasites when using high-resolution digitized video-intensified fluorescence microscopy. Antigens on 195 kD and 155 kD proteins were recognized by 3 and 1 MoAb, respectively, using Western blotting and immunoprecipitation techniques.

Animals↗
PubMed1992

Partial trisomy 19p: case report and natural history.

Partial trisomy 19p was noted in an infant delivered at 39 weeks gestation with intrauterine growth retardation (IUGR), bilateral club feet, renal abnormalities, hearing deficit, and multiple dysmorphic features. Chromosomes obtained following amniocentesis at 32 weeks gestation revealed that the fetus was partially trisomic for 19p and partially monosomic for a portion of the terminal band of 3q, having inherited a derivative chromosome 3 from her father [46,XX,-3,+der(3)t(3;19)(q29;p13.2)pat]. The father was found to be the carrier of a balanced translocation between chromosomes 3 and 19 [46,XY,t(3;19)(q29;p13.2)]. The only other case of partial trisomy 19p previously reported was an infant with partial trisomy 19p and partial monosomy 13q who died at 59 days of age. This report by Byrne et al. [(Am J Hum Genet 1980: 32:64A] is similar to our case with respect to IUGR, small palpebral fissures, and ear anomalies.

Adult↗
PubMed1992

Screening infants for hearing loss--an economic evaluation.

STUDY OBJECTIVE: The aim was to carry out an economic evaluation of the programme implemented in one district health authority for the screening of infants for hearing loss. DESIGN: The approach taken was a cost-effectiveness analysis using the methodology of decision analysis to model the options appraised: (1) the conventional screening policy was for a health visitor and colleague to screen at 8-9 months, and at 10 months for each child to be seen again by a clinical medical officer for a developmental assessment plus hearing screen if necessary; (2) the alternative policy was for screening to take place at 10 months only if concern is expressed (or if there is a clinical indication) at the developmental assessment; the introduction of a "clue list" was considered; (3) the third option was no screening. MAIN RESULTS: The annual expected cost per unit output was pounds 20.57 for the conventional screening policy, between pounds 11.13 and pounds 11.23 for the alternative policy, and pounds 11.27 for the third option of no screening. Introducing the "clue list" under the alternative screening policy is likely to raise the cost per unit output, but the effects are uncertain. CONCLUSIONS: The results suggest that the alternative screening policy is more cost-effective than the conventional policy, but has little advantage over not screening at all. The effects of introducing a clue list need further investigation.

Cost-Benefit Analysis↗
PubMed1992

An intrachromosomal insertion causing 5q22 deletion and familial adenomatous polyposis coli in two generations.

We report familial adenomatous polyposis coli (FAPC) with epidermoid cysts, osteomata, and areas of congenital hypertrophy of the retinal pigment epithelium (CHRPEs) in a male patient and his maternal aunt, both of whom suffered a mild to moderate degree of mental handicap. Both had an interstitial deletion of the long arm of chromosome 5 (del(5)(q22q23.2)). Two other normal family members had the underlying direct insertion of chromosome 5(dir ins(5)(q31.3q22q23.2)). Molecular genetic and fluorescent hybridisation studies have shown that loci D5S37 and D5S98 are outside the deletion whereas loci detected by probes EF5.44 and YN5.48 are lost. As expected, the molecular analyses indicate loss of one allele at the MCC and APC loci. The APC gene is located within band 5q22. Familial direct insertions should be considered as a cause of recurrent microdeletion syndromes.

Adenomatous Polyposis Coli↗
PubMed1992

Renal receptors for atrial and C-type natriuretic peptides in the rat.

Receptors for alpha-atrial natriuretic peptide (alpha-ANP) and C-type natriuretic peptide [CNP-(1-22)] were quantified in kidneys from adult Wistar rats by in vitro autoradiography. 125I-labeled alpha-ANP (100 pM) bound reversibly to glomeruli, outer medullary vasa recta, and inner medulla with an apparent dissociation constant (Kd) of 3-6 nM. The presence of 10 microM des-[Gln18,Ser19,Gly20,Leu21,Gly22]ANP-(4- 23) (C-ANP), a specific ligand of the ANPR-C subtype of alpha-ANP receptor, inhibited approximately 50% of the glomerular binding of 125I-alpha-ANP, and this moiety of glomerular binding was also inhibited by CNP-(1-22) with an apparent inhibitory constant (Ki) of 10.47 +/- 7.59 nM. C-ANP and CNP-(1-22) showed little affinity for the medullary binding sites of alpha-ANP. 125I-[Tyr0]CNP-(1-22) (110 pM) bound solely to glomeruli and was competitively displaced by increasing concentrations of [Tyr0]CNP-(1-22) with an apparent Kd of 1.42 +/- 0.48 nM. Binding of increasing concentrations (25 pM to 1 nM) of 125I-[Tyr0]CNP-(1-22) in the presence or absence of 1 microM [Tyr0]CNP-(1-22) also demonstrated a high affinity (Kd of 0.41 +/- 0.07 nM) for the glomerular binding of 125I-[Tyr0]CNP-(1-22). Bound 125I-[Tyr0]CNP-(1-22) could be displaced by excess alpha-ANP and excess CNP-(1-22), both with high affinities. The glomerular binding of 125I-[Tyr0]CNP-(1-22) was also prevented by 10 microM C-ANP. Guanosine 3',5'-cyclic monophosphate produced by isolated glomeruli was measured by radioimmunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The effect of chewing gum use on in situ enamel lesion remineralization.

Two independent cross-over studies investigated the possibility of enhanced early enamel lesion remineralization with the use of chewing gum. The first study involved a sorbitol-containing chewing gum, and the second, which had an identical protocol, tested a sucrose-containing chewing gum. In each study, 12 volunteers wore in situ appliances on which were mounted enamel sections containing artificial caries lesions. Subjects brushed twice daily for two min with a 1100-ppm-F (NaF) dentifrice (control and test) and in the test phase chewed five sticks of gum per day for 20 min after meals and snacks. Microradiographs of the enamel lesions were made at baseline and at the end of the seven-week experimental period. In the sugar-free gum study, the weighted mean total mineral loss (delta z) difference [(wk7-wk0) x (-1)] was 788 vol.% min. x micron for the gum, corresponding to remineralization of 18.2%, vs. the control value of 526 vol.% min. x micron, 12.1% remineralization (p = 0.07). There were no significant differences for the surface-zone (p = 0.20) and lesion-body (p = 0.28) values. In the sucrose-containing gum study, the delta z difference was 743 vol.% min. x micron for the gum, corresponding to a remineralization of 18.3%, vs. the control value of 438 vol.% min. x micron, 10.8% remineralization (p = 0.08). The surface-zone values were not significantly different (p = 0.55). For the lesion body, however, the sucrose-containing gum value of 6.11 vol.% min. was significantly different (p = 0.01) from that of the control (2.81 vol.% min.).

Adult↗
PubMed1992

Acute changes in haematological parameters on cessation of smoking.

Cigarette smoking is known to affect many haematological parameters but little is known of their rate of return to normal on withdrawal of cigarettes. Two groups of chronic smokers were studied whilst smoking and in the 2 weeks after cessation. A rapid return towards normal was found in the elevated haemoglobin concentration, packed cell volume, red cell count, white cell count, neutrophil count, lymphocyte count and platelet count, indicating that at least some of the abnormalities in these parameters are an acute, reversible effect of cigarette smoking rather than being a response to tissue damage.

Adult↗
PubMed1992

Improving the diet of under fives in a deprived inner city practice.

This paper reports the introduction of a programme of dietary education to a selected group of young mothers living in a deprived inner city area. The programme was devised by a general practitioner and practice health visitors in collaboration with two hospital dietitians. A diary was used to provide data on diet, food choice, shopping habits, eating together, and planning and frequency of meals. These were included in a list of twelve 'desirable' food groups and three organisational skills, thus providing an individual syllabus for teaching, and a means of assessing the intervention. At the start of the study milk, fruit, vegetables and protein containing iron were common dietary omissions. However, the results show that these foods were an established part of the children's diets following the intervention. The dietary diaries provided a successful means of analysis, and the teaching programme is continuing in this practice. The limitations of such a small study are acknowledged, and a long-term controlled study is suggested.

Adult↗
PubMed1992

Chemiluminescent detection of DNA on nylon membranes.

Two types of nonradioactive DNA detection systems were optimized for use with nylon membranes in Southern transfers. A luminol substrate system (consisting of an enhanced chemiluminescent reaction utilizing luminol enzyme substrate) was used with peroxidase-labeled probe DNA, and a dioxetane-based substrate was used with alkaline phosphatase/antibody and digoxigenin-labeled probe DNA. Chemiluminescence was detected by autoradiography. Methods for reprobing the membranes were also optimized for both systems; blots could be reprobed at least ten times. Results showed that excellent sensitivity and low background can be achieved on both amphoteric and positively charged nylon membranes, using either detection system.

Alkaline Phosphatase↗
PubMed1992

Pick's disease.

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Age of Onset↗
PubMed1992

A prospective cytogenetic study of 36 cases of DiGeorge syndrome.

Cytogenetic analysis was carried out in a prospective series of 36 children with DiGeorge syndrome. High-resolution banding (> 850 bands/haploid set) was achieved in 30 cases. Monosomy 22q11.21-->q11.23 was found in 9 of these 30 cases. In each of these cases monosomy 22q11.21-->q11.23 resulted from an interstitial deletion and not from a translocation. No other chromosome abnormalities were seen.

Child↗
PubMed1992

Screening for neuroblastoma in the northern region of England. Laboratory aspects.

Our pilot study for neuroblastoma screening started in 1986. The study has progressed through several phases, with use of several analytical methods to a procedure based primarily on the use of automated gas chromatography mass spectrometry. The northern region of England has a relatively static population of approximately 3.5 million, with an annual birth rate of 41,000. The region consists of 16 administrative health districts. In 4 years, we have screened 20,829 infants from four health districts. In this program, we screen all children at 6 months of age. A urine sample is collected on filter paper by a health visitor, either at the time of the infant's routine clinic visit or during the health visitor's follow-up visit at home. In the laboratory, the sample is dried and processed for analysis of homovanillic acid (HVA) and vanillylmandelic acid (VMA), using a benchtop Hewlett Packard gas chromatograph mass spectrometer. The results are related to the creatinine content of the urine. Using cut-off limits of 39 micrograms/mg of creatinine for HVA and 25 micrograms/mg of creatinine for VMA, 2,537 infants (12.2%) required a second paper sample and 527 infants (2.5%) were observed with a liquid urine collection. Of these, the conditions of nine infants with elevated levels of HVA or VMA were investigated clinically for the possible presence of neuroblastoma. Two infants were found to have neuroblastoma; the other seven showed no evidence of tumor. In addition, there were three children who, when screened at 6 months of age, had normal levels of HVA and VMA but in whom neuroblastoma subsequently developed.

Biomarkers, Tumor↗