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Biomedical subjects

S Bennett

Publications and source records attributed to S Bennett.

At least 73 records · Page 4Linked to original sources
PubMed1998

Charged beads enhance cutaneous wound healing in rhesus non-human primates.

Enhanced cutaneous wound healing by positively charged cross-linked diethylaminoethyl dextran beads (CLDD) was studied in a standardized incisional wound model in 20 adult and 20 geriatric Macaca mulatta (rhesus) partitioned equally over five time periods. Physiologic saline served as a control. Soft-tissue linear incisions were prepared between and 1 cm inferior to the scapulae. There were four incisions per rhesus; each incision was 1.5 cm long with 1 cm of undisturbed tissue between incisions, and both the experimental CLDD and physiologic saline treatments were administered to each rhesus. The incision treatments were either CLDD and soft-tissue closure with 4-0 BioSyn sutures or sterile physiologic saline and closure with 4-0 BioSyn sutures. The hypothesis was CLDD would enhance cutaneous wound repair. Verification of the hypothesis consisted of clinical examinations and histologic and tensiometric evaluations on biopsy specimens at 10 and 15 days, whereas 5-day and 2- and 4-month groups were assessed clinically and biopsy specimens were assessed histologically. The clinical course of healing for all groups was unremarkable. At 10 days, incisions in adult rhesus treated with CLDD had a 30-percent greater tensile strength compared with the physiologic saline-treated incisions (p = 0.01), whereas for geriatric rhesus, the CLDD treatment proved to be 15 percent greater in tensile strength compared with the physiologic saline cohort (p = 0.11). By day 15, incisions in adult rhesus were 26 percent stronger than the saline treatment group (p = 0.07), and the difference was 36 percent (p = 0.02) for the geriatric rhesus. From 5 through 15 days, histologic observations revealed a gradual decrease in quantity and integrity of CLDD, with no remnants of CLDD at either 2 or 4 months. Macrophages and multinucleated giant cells were localized in the dermis and were associated with the CLDD. These cells decreased commensurately with the decrease of CLDD beads. The data suggest that CLDD can enhance significantly the tensile properties of healing cutaneous wounds in both adult and geriatric rhesus. Moreover, if the wound healing is enhanced in geriatric patients, this finding may be clinically germane to conditions where wound healing is compromised, such as in diabetics and patients on steroids.

Animals↗
PubMed1998

High incidence of asymptomatic malara infections in a birth cohort of children less than one year of age in Ghana, detected by multicopy gene polymerase chain reaction.

The incidence of Plasmodium falciparum infection has been followed in a birth cohort of 71 infants in southern Ghana, an area of perennial malaria transmission. Parasite DNA detection established the presence of a high rate of infection in newborns (13.6%), a low level of infection from two to 26 weeks (1.5-9.7%) and a steadily increasing parasite rate from 26 weeks of age. The median age to first infection was 42 weeks. Five cases of fever (temperature > or = 37.5 degrees C) and parasite density greater than 1,000 parasites/microl of blood, all in children more than 18 weeks of age, were considered possible cases of clinical malaria. The risk of infection was almost three times higher in the wet season than in the dry season and increased significantly from the age of 18 weeks. The level of malaria-specific IgG at birth was positively correlated with risk of infection in children 6-12 months of age, indicating that maternally derived anti-malarial IgG is correlated with exposure to malaria infection. There was no association between malaria-specific IgG at birth and risk of infection in children 0-6 months of age. However, infants do appear to possess mechanisms to limit parasite growth and a role for maternal antibody cannot be ruled out.

Adult↗
PubMed1998

Growth factor involvement in progression of prostate cancer.

Understanding how the regulation of growth factor pathways alters during prostate cancer (PC) progression may enable researchers to develop targeted therapeutic strategies for advanced disease. PC progression involves the shifting of cells from androgen-dependent growth to an androgen-independent state, sometimes with the loss or mutation of the androgen receptors in PC cells. Both autocrine and paracrine pathways are up-regulated in androgen-independent tumors and may replace androgens as primary growth stimulatory factors in cancer progression. Our discussion focuses on growth factor families that maintain homeostasis between epithelial and stromal cells in the normal prostate and that undergo changes as PC progresses, often making stromal cells redundant. These growth factors include fibroblast growth factor, insulin-like growth factors, epidermal growth factor, transforming growth factor alpha, retinoic acid, vitamin D3, and the transforming growth factor beta families. We review their role in normal prostate development and in cancer progression, using evidence from clinical specimens and models of PC cell growth.

Animals↗
PubMed1997

Statistical analysis of highly skewed immune response data.

This paper considers methods of statistical analysis for highly skewed immune response data. Observations from population studies of immunological variables are rarely normally distributed between individuals; typically the distribution shows extreme levels of skewness. In some situations, skewness remains considerable even after transforming the data. Using resampling techniques, applied to several actual datasets of ELISA assay data, we consider the robustness of normal parametric methods, e.g. t tests and linear regression. Despite the skewness of the transformed data, we demonstrate that such methods are quite robust depending on the number of observations, type of analysis and severity of skewness. We also illustrate how bootstrap resampling can be used to provide a valid alternative method of analysis that can be used either for checking normal parametric analysis or as a direct method of analysis. We illustrate this combined approach by analysing real data to test for association between human serum antibodies to malaria merozoite surface proteins, MSP1 and MSP2, and resistance to clinical malaria, and confirm the protective effect of antibodies to MSP1 and demonstrated a similar protective effect for some antibodies to MSP2.

Animals↗
PubMed1997

Why can't most people draw what they see?

The study presented a theoretical and empirical approach to the adult drawing process. Four possible sources of drawing inaccuracies were described: misperception of the object, inability to make good representational decisions, deficient motor skills, and misperception of the drawing. In four studies the degree to which the latter three sources contributed to drawing inaccuracies was assessed. The results suggest that (a) motor coordination is a very minimal source of drawing inaccuracies, (b) the artist's decision-making process is a relatively minor source of drawing inaccuracies, and (c) the artist's misperception of his or her work is not a source of drawing inaccuracies. These results suggest that the artist's misperception of the object is the major source of drawing errors.

Art↗
PubMed1997

The effects of life stressors and daily stressors on stuttering.

This study systemically documented the effect of perceived daily stress on subjective and objective measures of disfluencies in 12 adults who stuttered and 12 adults who did not stutter. Subjects participated in a prospective research study for 22 consecutive days. Measures of life stress, daily stress, and self-ratings of fluency were obtained. Subjects were trained in rating their fluency levels (self-ratings of fluency) and perceived daily stress levels (frequency and perceived impact of daily stressors). Results revealed a significantly higher number of daily stressors endorsed by subjects who stutter. Subjects who stuttered also displayed a significantly greater number of disfluencies and higher self-ratings of disfluencies on "high-stress" days. No significant differences were found between the mean total scores for life stress or impact scores for daily stress for the two groups. These data suggest that day-to-day variations in stuttering could be related to multiple, minor, daily stressors in some persons who stutter. Implications for treatments involving cognitive restructuring and desensitization are discussed.

Adolescent↗
PubMed1997

Follow-up of Gambian children recruited to a pilot safety and immunogenicity study of the malaria vaccine SPf66.

A pilot safety and immunogenicity trial of the malaria vaccine SPf66 was undertaken in The Gambia in 1993. One hundred and fifty infants aged 6-11 months were immunized with either 0.5 mg or 1.0 mg of SPf66 produced either in Colombia or in the USA or with a control vaccine. Children who received SPf66 experienced more clinical attacks of malaria than did children in the control group during the first period of surveillance and the difference in incidence between children who had received high dose Colombian vaccine and the control children was statistically significant at the 5% level. During the 1995 malaria transmission season, 127 children from the original cohort of 150 were observed. During 18 weeks of intensive surveillance, the incidence of clinical malaria was again higher among children who had received SPf66 than among children who had received inactivated polio vaccine (6.23 vs 4.89 clinical attacks per 1000 days at risk), the effect being most marked among children who were in the high dose groups, but differences between groups were now no longer statistically significant.

Child↗
PubMed1997

Skill acquisition in sport: some applications of an evolving practice ecology.

This paper builds on recent theoretical concerns regarding traditional conceptualizations of the skill acquisition process. The implications for the process of practice in sport contexts are explored with reference to the information-processing approach to motor behaviour and the newer ecological paradigm. Issues are raised with current principles of practice based on traditional theoretical ideas. A practice strategy that gives greater weight to the guided exploration of the practice workspace jointly defined by the properties of the individual's subsystems, the specific task and the environment is advocated. Such a constraints-led perspective supersedes previous distinctions between rudimentary and voluntary skills. Sports scientists, coaches, teachers and movement rehabilitation therapists are invited to review current practices in the light of recent theoretical advances from the ecological perspective.

Adaptation, Physiological↗
PubMed1997

Plasmodium vivax: a cause of malnutrition in young children.

We studied the aetiology of malnutrition in a cohort of 1511 children < 10 years old in Espiritu Santo, Vanuatu. Malnutrition was categorized using standard anthropometric criteria as: underweight [weight-for-age (WA) Z score < -2], wasting [weight-for-height (WH) Z < -2], or stunting [height-for-age (HA) Z < -2]. On multiple logistic regression analysis, the only factors significantly associated with wasting were age < 5 years [OR (95% CI) 1.8 (1.2-2.9), p = 0.01] and having suffered one or more episodes of clinical P. vivax malaria in the 6 months preceding nutritional assessment [OR 2.4 (1.3-4.4), p = 0.006]. The incidence of P. vivax infection was significantly higher during the 6 months preceding assessment in underweight vs. non-underweight children [incidence rate ratio (IRR) 2.6 (1.5-4.4), p < or = 0.0001). These groups had similar incidences of clinical P. falciparum infection during the same period [IRR 1.1 (0.57-2.1) p = 0.8] and of either species during the 6 months following assessment [IRR P. vivax 1.3 (0.9-2.0) p = 0.2; IRR P. falciparum 1.3 (0.9-1.9) p = 0.2]. In these children, P. vivax malaria was a major predictor of acute malnutrition; P. falciparum was not. Wasting neither predisposed to nor protected against malaria of either species. Although P. vivax malaria is generally regarded as benign, it may produce considerable global mortality through malnutrition.

Age Factors↗
PubMed1997

Effects of methylphenidate on preschool children with ADHD: cognitive and behavioral functions.

OBJECTIVE: To report on implications for methylphenidate treatment of this very young age group and the need to examine factors related to achieving compliance. METHOD: Thirty-one children with attention-deficit hyperactivity disorder (ADHD), aged 4 to 6 years, participated in a double-blind, placebo-controlled study using placebo, 0.3 mg/kg, and 0.5 mg/kg of methylphenidate twice per day. RESULTS: Improvements related to medication were obtained on cognitive tests of attention and impulsivity as well as behaviors assessed by parent rating scales. In an interactive setting with their mothers, attentional abilities and the children's ability to work more productively also showed improvement. However, no changes were obtained with respect to the children's tendency to comply with parental requests. Side effects increased slightly with the high dosage of medication but remained mild. CONCLUSION: The results suggest that methylphenidate can be used to improve the functioning of preschool-age children with ADHD, in a manner similar to their school-age counterparts.

Attention Deficit Disorder with Hyperactivity↗
PubMed1997

Quantification of the relative contribution of major histocompatibility complex (MHC) and non-MHC genes to human immune responses to foreign antigens.

Understanding the extent to which genetic factors influence the immune response is important in the development of subunit vaccines. Associations with HLA gene polymorphisms appear insufficient to explain the range of variation in immune responses to vaccines and to infections by major pathogens. In this study of Gambian twins we report that regulation of the immune response to a variety of antigens from Plasmodium falciparum and Mycobacterium tuberculosis is controlled by factors which are encoded by genes that lie both within and outside the major histocompatibility complex (MHC). We define the relative contribution of these genes, which varies for different antigens. The cumulative genetic contribution of non-MHC genes to the total phenotypic variance exceeds that of the MHC-encoded genes.

Antibody Formation↗
PubMed1997

Neonatal pain response to heel stick vs venepuncture for routine blood sampling.

Neonatal pain response and adverse effects and maternal anxiety were assessed in 27 infants who were randomly allocated to venepuncture or heel stick. Pain was assessed by nurses using the Neonatal Infant Pain Scale (NIPS) and a three point scale for the mothers. NIPS scores were higher in the heel stick group compared with the venepuncture group. Maternal anxiety was higher before the procedure while perception of an infant's pain was lower in the venepuncture group compared with the heel stick group. Venepuncture is less painful than heel stick in newborn infants undergoing routine blood sampling.

Anxiety↗
PubMed1997

A supervised learning network based on adaptive resonance theory.

A neural network architecture, fuzzy ART with logistic discrimination (ART-LD), is introduced as a method of realising the pattern recognition task in a supervised learning manner. The system is formed by the hierarchical organisation of two network modules: a fuzzy ART and a logistic discrimination. The learning consists of two separate stages. Firstly, the fuzzy ART module self-organises the input patterns into category clusters, whose operations are governed by fuzzy set theory and "competitive learning" dynamics that ensure fast and stable learning. Then the outputs, which can be interpreted as fuzzy memberships of an input pattern to the encoded categories, provide the spatial distance information that is generalised by the subsequent logistic discrimination to give the final prediction. Examples are presented, and the generalisation capabilities of ART-LD are demonstrated through two simulated and one real classification problem.

Artificial Intelligence↗