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Biomedical subjects

M Davies

Publications and source records attributed to M Davies.

At least 163 records · Page 9Linked to original sources
PubMed1998

Differential regulation of matrix metalloproteinases and their inhibitors in human glomerular epithelial cells in vitro.

The present study examines the effect of transforming growth factor-beta1 (TGF-beta1) and interleukin-1beta (IL-1beta) on the regulation of gelatinase A, gelatinase B, tissue inhibitor of metalloproteinase-I (TIMP-I) and TIMP-II in human glomerular epithelial cells (GEC). The addition of TGF-beta1 resulted in the increased production and secretion of both gelatinase A (72-kD type IV collagenase) and gelatinase B (92-kD type IV collagenase), in a dose- and time-dependent manner. In contrast, the addition of IL-1beta to GEC resulted in the stimulation of secretion of gelatinase B but not gelatinase A. When the secretion of the regulatory inhibitors was examined, IL-1beta or TGF-beta1 both resulted in an increased secretion of TIMP-I, whereas the secretion of TIMP-II was downregulated. Such results demonstrate an independent and opposite regulation of the enzymes and their inhibitors. Of particular interest was the observation of the differential regulation of gelatinase A and its specific inhibitor TIMP-II (which binds to the latent form of this enzyme) in response to TGF-beta1. These results for the first time indicate that in human GEC, matrix metalloproteinases (MMP), as well as their specific inhibitors, are independently regulated by different cytokines. MMP and their regulatory tissue inhibitors (TIMP) play an important role in tissue remodeling. The results of the present study serve to emphasize both the complex regulation of matrix metabolism in the glomerulus and the potential pathologic role of an imbalance between the proteinases and their inhibitors in various forms of glomerular disease.

Base Sequence↗
PubMed1998

Evaluation of individual subjects in the analog classroom setting: I. Examples of graphical and statistical procedures for within-subject ranking of responses to different delivery patterns of methylphenidate.

In this article, we describe graphical and statistical methods developed to evaluate the response patterns of individual children with attention deficit hyperactivity disorder (ADHD) to different conditions of treatment with stimulant medication. We used data from an investigation of drug delivery patterns to demonstrate these methods. Thirty-one children with ADHD participated in a double-blind crossover study of four conditions (three patterns of delivery of methylphenidate and a placebo control). In each condition, the children were evaluated across an 11-hour (7:00 a.m. to 6:00 p.m.) laboratory school day, and ratings of classroom behavior were obtained at regular intervals across the day. Graphical procedures were developed to display, for each individual, time courses of multiple measures of behavior taken across each double-blind test day. Expert clinicians judged these graphs and used this information to rank-order the test days from best to worst. A within-subject variant of Kendall's W was used to evaluate, for each subject, whether the rankings of these multidimensional graphs were reliable (concordant) across judges. A generalized kappa statistic was used to evaluate, for each condition, the reliability of the judges' rankings across subjects. Friedman's analysis of variance of ranks was used to evaluate, for the study, whether the conditions differed in terms of the average (consensus) rank assigned by the judges.

Attention Deficit Disorder with Hyperactivity↗
PubMed1998

Evaluation of individual subjects in the analog classroom setting: II. Effects of dose of amphetamine (Adderall).

Multiple dependent variables were graphed for 29 subjects who participated in a double-blind evaluation of 4 doses of Adderall, plus positive (methylphenidate) and placebo control conditions. Five judges ranked the conditions for each subject, and analyses of individual subjects indicated that these rankings were concordant (reliable) across judges. Consensus rankings were assigned to each subject, and an analysis of these ranks showed that the conditions differed significantly. The choice of best conditions were judged to be across 3 doses of Adderall (10, 15, and 20 mg). This confirms the clinical impression of individual differences in optimal dose of stimulant medication. The methodological, graphical, and statistical methods presented in this article provide a systematic, reliable procedure for evaluating relative response of individuals to different doses of stimulant medication.

Amphetamine↗
PubMed1998

Effects of propofol and pentobarbital on ligand binding to GABAA receptors suggest a similar mechanism of action.

The GABAA receptor is allosterically modulated by a number of anesthetics and barbiturates. We have examined the effects of propofol and pentobarbital on the binding of the receptor agonist [3H]muscimol and the benzodiazepine modulators [3H]flunitrazepam and [3H]Ro15-4513 to bovine brain membranes. Both agents potentiated the binding of [3H]muscimol (5 nM), with EC50 values of 18.7 and 276 microM, respectively. The binding of [3H]muscimol is heterogeneous, suggesting the presence of both high (Kd approximately 10 nM) and low (Kd approximately 0.1-1.0 microM) affinity sites. The major effect of both propofol and pentobarbital was to increase the affinity of the lower affinity sites without changing the total binding capacity. In contrast, the steroid anesthetic alphaxalone did not affect the affinity of these sites, suggesting that this drug has distinct effects on the GABAA receptor. Propofol and pentobarbital also increased the binding of the benzodiazepine agonist [3H]flunitrazepam and decreased the binding of the inverse agonist [3H]Ro15-4513. The results of these studies demonstrate that propofol and pentobarbital modulate the binding of ligands to the GABAA receptor in a similar manner, suggesting that these drugs may have a common mechanism of action.

Allosteric Site↗
PubMed1998

Cognitive functioning in adults with Williams syndrome.

This paper reports the results of cognitive, linguistic, and academic assessments in a representative sample of 62 adults with Williams syndrome. The average age of the group was 26 years and their mean full scale IQ was 61. Differences between Verbal and Performance IQ, and between receptive and expressive language skills, were smaller than generally found in studies of children with this condition. However, an examination of subtest scores revealed an almost identical cognitive profile to that found in children. Skills in other areas, such as reading, spelling, arithmetic, and social adaptation remained at a low level, with functioning generally being around a 6-8-year age equivalent. The consistency of reports on intellectual abilities in both child and adult studies of individuals with Williams syndrome lends increased support to the notion of a syndrome specific pattern of cognitive, linguistic, and adaptive functioning.

Adolescent↗
PubMed1997

Overexpression of autocrine TGF-beta 1 suppresses the growth of spindle epithelial cells in vitro and in vivo in the rat 4NQO model of oral carcinogenesis.

We examined the effect of the stable transfection of latent TGF-beta 1 cDNA, under the control of a cytomegalovirus promoter in the expression vector pcDNA3, into a 4NQO-induced clonal rat oral keratinocyte cell line that formed undifferentiated spindle cell tumours following subcutaneous transplantation to athymic mice. Test cells containing latent TGF-beta 1 cDNA produced a 2.3-fold increase in TGF-beta 1 protein compared to pcDNA3 controls as demonstrated by ELISA. Neutralisation experiments indicated that the majority of the protein was in the latent form. Untransfected and transfected (containing either TGF-beta 1 cDNA or pcDNA3) cell lines were keratin negative and vimentin positive. Cells transfected with TGF-beta 1 were inhibited more than pcDNA3 controls when cultured in an anchorage dependent or independent environment. Subcutaneous transplantation of cells overproducing TGF-beta 1 resulted in tumours of significantly smaller volume than vector-only controls. Further, orthotopic transplantation of cells containing TGF-beta 1 cDNA to the floor of the mouth in athymic mice markedly inhibited the development of pulmonary metastases compared to vector-only controls. Both test and control cell lines in athymic mice formed undifferentiated tumours with a complete absence of keratin elaboration. Subcutaneous xenografts were recultured and cells containing the TGF-beta 1 cDNA produced a similar amount of TGF-beta 1 peptide as the cells containing pcDNA3 only. The production of TGF-beta 1 by both of the xenograft-derived cell lines was significantly less than the parent, pre-transplanted cell lines and the untransfected cell line. All of the cell lines were inhibited by exogenous TGF-beta 1. Our results demonstrate that autocrine TGF-beta 1 functions as a tumour suppressor in vitro and in vivo in 4NQO-induced spindle tumour cells that are growth inhibited by the ligand. Furthermore, tumour formation in athymic mice is associated with selection for a cell phenotype with diminished autocrine TGF-beta 1 production.

4-Nitroquinoline-1-oxide↗
PubMed1997

Latex allergy.

Explore the source record for details and available documents.

Anesthesia, Dental↗
PubMed1997

Relationships between frequency and quantity of marijuana use and last year proxy dependence among adolescents and adults in the United States.

The association between levels of marijuana use and last year dependence is investigated in a nationally representative sample of adolescents and adults, who used marijuana within the last year (n = 9284). Data are aggregated from three surveys (1991-1993) of the National Household Survey on Drug Abuse. A proxy measure of DSM-IV dependence criteria was developed from self-reported symptoms of dependence and drug-related problems. Both frequency and quantity of marijuana use within the last year are linearly associated with the logit of the probability of being dependent on marijuana. The associations vary significantly by age but not gender. Adolescents are dependent at a lower frequency and quantity of use than adults: the differences diverge as level of use increases. Twice as many adolescents as adults who used marijuana near-daily or daily within the last year were identified as being dependent (35% versus 18%). Frequency and quantity of use each retained a unique effect on dependence, but frequency appeared to be more important than quantity in predicting last year dependence. These results provide insight into the processes underlying the age and sex differentials observed in the prevalence of marijuana dependence. The implications of the findings for the epidemiology of marijuana use and dependence are discussed.

Adolescent↗
PubMed1997

Independence and adaptive behavior in adults with Williams syndrome.

This study describes the adjustment of 70 adults with Williams syndrome, in terms of self-help skills, independence, and occupational levels. Although the overall mean IQ of the group (62.00) was within the mild mental handicap range, relatively few individuals were able to attain a high level of independence or cope with the demands of employment. Adaptive behavior scores were significantly below chronological age. Outcome measures were compared with available data on other groups of adults of similar age and level of intellectual impairment. Implications for the community care of adults with Williams syndrome are discussed.

Activities of Daily Living↗
PubMed1997

Multisomatoform disorder. An alternative to undifferentiated somatoform disorder for the somatizing patient in primary care.

BACKGROUND: For clinical or research use in primary care, the DSM-IV diagnostic criteria for somatization disorder are too restrictive, while the criteria for undifferentiated somatoform disorder are overly inclusive. In this article, we examine the validity of multisomatoform disorder, defined as 3 or more medically unexplained, currently bothersome physical symptoms plus a long (> or = 2 years) history of somatization. METHODS: Data from the Primary Care Evaluation of Mental Disorders Study of 1000 patients from 4 primary care sites were analyzed. The outcomes assessed were 6 domains of health-related quality of life, using the 20-item Short-Form General Health Survey; self-reported disability days and health care use; satisfaction with care; and physician-rated difficulty of the encounter. RESULTS: Multisomatoform disorder was diagnosed in 82 (8.2%) of the 1000 patients who were enrolled in the Primary Care Evaluation of Mental Disorders Study. Compared with mood and anxiety disorders, multisomatoform disorder was associated with comparable impairment in health-related quality of life, more self-reported disability days and clinic visits, and greater clinician-perceived patient difficulty. CONCLUSIONS: Multisomatoform disorder may be a valid diagnosis and potentially more useful than the DSM-IV diagnosis of undifferentiated somatoform disorder. Also, because multisomatoform disorder has a large and independent effect on impairment, its diagnosis should not be precluded simply because of a coexisting mood or anxiety disorder.

Adolescent↗
PubMed1997

Neuroendocrine response to fenfluramine challenge in boys. Associations with aggressive behavior and adverse rearing.

BACKGROUND: There is evidence of relationships among serotonin, aggressive behavior, and a childhood history of socially adverse-rearing conditions. This study examines the prolactin response to fenfluramine hydrochloride challenge in young boys who show clinically significant aggressive behavior or who are raised in a social environment that is conducive to the development of chronic aggression. METHODS: A series of 34 younger brothers of convicted delinquents underwent standardized psychiatric and observation-based assessments of their social-rearing environments that were conducted during home visits. Approximately 2 years later, these boys underwent a reassessment of psychiatric status and an assessment of central serotonergic activity using the fenfluramine challenge procedure. RESULTS: Increasing degrees of aggressive behavior at either assessment were positively correlated with the prolactin response to fenfluramine challenge. Furthermore, adverse-rearing circumstances that were conducive to the development of aggressive behavior also exhibited positive correlations with the prolactin response. This association between adverse rearing and the prolactin response was statistically independent of that between aggression and the prolactin response. CONCLUSION: In young boys, aggressive behavior and social circumstances that are conducive to the development of aggressive behavior are positively correlated with a marker of central serotonergic activity.

Aggression↗
PubMed1997

Quantification of vitamin D receptor mRNA in tissue sections demonstrates the relative limitations of in situ-reverse transcriptase-polymerase chain reaction.

In situ-reverse transcriptase-polymerase chain reaction (IS-RT-PCR) is a recently described technique that is used to localize low levels of mRNA within cells and tissue sections. One of the major criticisms levelled at this technique is that positive results may be meaningless, as amplification is required to demonstrate the transcripts of interest. The use of IS-RT-PCR to demonstrate mRNA for receptors for 1,25-dihydroxyvitamin D3 (VDR) in sections of human kidney and bone has previously been described. To ascertain whether the levels of VDR mRNA detected following IS-RT-PCR were transcriptionally significant, computerized image analysis was used to determine the mean silver grain density in human kidney and bone cells following conventional in situ hybridization and after various cycles of IS-RT-PCR. Only a few cycles of PCR were needed to produce an optimum signal, but amplification of signal following IS-RT-PCR was found to be relatively inefficient. Following the optimum number of cycles of IS-RT-PCR in kidney sections, there was a less than four-fold increase in signal. Similarly, in bone, the optimum signal detected was only approximately five times greater than that found with conventional in situ hybridization. These results clearly demonstrate that the increase in signal following IS-RT-PCR follows a more linear pattern and is relatively inefficient, compared with the usual exponential increase with conventional solution phase RT-PCR.

Bone and Bones↗
PubMed1997

Do individuals with Williams syndrome have bizarre semantics? Evidence for lexical organization using an on-line task.

Williams syndrome, a neurodevelopmental disorder, has attracted a great deal of debate concerning the purported intactness of language in the face of other serious cognitive deficits. As more in-depth studies of specific aspects of WS language have emerged, the notion of a preserved language module has been seriously challenged. Although WS vocabulary scores are often impressive, several investigators have claimed the WS semantics are aberrant. All studies hitherto have been based on off-line experiments which necessarily involve metalinguistic processes. This clearly affects the performance of individuals with cognitive deficits. We report here an on-line study probing the semantic structure of the WS lexicon, using a task-semantic priming-which minimises metalinguistic demands. We show that WS subjects display the same taxonomic/category and thematic/functional priming effects as normal controls. The results are discussed in terms of the differences between receptive and expressive language, as well as the fact that although semantic memory and the automatic access to semantic information for individual words is normal in WS, the integration of semantic information into sentence comprehension may be abnormal. The importance of online tasks to highlight such differences is stressed.

Adolescent↗
PubMed1997

Microanalysis of adolescent suicide attempters and ideators during the acute suicidal episode.

OBJECTIVE: To compare psychological and event-related contingencies that characterize and differentiate adolescent suicidal ideation and attempts. METHOD: Thirty-five ideators and 32 attempters (aged 12 to 17 years) consecutively referred to the suicide disorders clinic were evaluated with a semistructured interview about current and past emotional, cognitive, and behavioral states. RESULTS: Before the precipitant stressor (baseline), attempters reported significantly more hopelessness than ideators (odds ratio [OR] = 4.2, p < .05). During the suicidal episode, attempters, relative to ideators, spent more time ideating (OR = 4.3, p < .05), were more likely to isolate themselves (OR = 5.8, p < .01), and were less likely to tell anyone what they were thinking (OR = 4.5, p < .05). In contrast, ideators reported significantly more residual anger after the episode than did attempters (OR = 4.0, p < .05). All the episodes of ideation and attempts were preceded by a stress event. No differences were found between the groups on Beck Depression inventory scores. CONCLUSIONS: Preexisting hopelessness, a tendency toward isolation, not talking about ideation, and longer length of time ideating during suicidal episodes discriminated suicide attempters from suicide ideators. Knowledge of these factors may be helpful in preventive and treatment efforts with suicidal adolescents.

Adolescent Psychiatry↗