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Biomedical subjects

M Black

Publications and source records attributed to M Black.

At least 91 records · Page 5Linked to original sources
PubMed1995

Restriction enzyme-mediated integration elevates transformation frequency and enables co-transfection of Toxoplasma gondii.

This report describes the use of restriction enzyme-mediated integration (REMI) to increase the transformation frequency and allow co-transfection of several unselected constructs under the selection of a single selectable marker. We found that while BamHI (the enzyme used to originally demonstrate REMI (Schiestl, R.H. and Petes, T.D. (1991) Integration of DNA fragments by illegitimate recombination in Saccharomyces cerevisiae. Proc. Nati. Acad. Sci. USA 88, 7585-7589) increased the number of transformants by 2-5-fold over the control without added enzyme, NotI proved to be a further 29-46-times more effective in enhancing stable transformation. This simple technique was used in the transformation of three non-selective markers (two modified membrane proteins and beta-galactosidase) with a selectable construct expressing chloramphenicol acetyltransferase. Following chloramphenicol selection, four out of ten independent transformants stably acquired all four constructs with at least two expressing all four genes at the protein level. These results demonstrate that REMI may be used in the efficient stable transformation and co-transfection of this and perhaps other protozoan parasites.

Animals↗
PubMed1995

What makes a therapy? Some parameters of therapeutic intervention in aphasia.

It has often been assumed that detailed analyses of aphasic impairments would be both necessary and sufficient for the development of remediation programmes. In this paper, we argue that the analysis of the impairment is a necessary but not sufficient precondition for therapy. Adequate remediation programmes require the development of an independent theory of therapy that provides a detailed specification of the different components of the therapeutic process. Therapy can be shown to have as many interacting components as the impairment itself. In this paper, we try to identify some of the components of the therapy process by comparing different therapy programmes that have been employed in the remediation of 'mapping deficits' in agrammatism.

Aphasia↗
PubMed1995

Development of a culturally, theoretically and developmentally based survey instrument for assessing risk behaviors among African-American early adolescents living in urban low-income neighborhoods.

The creation of developmentally and culturally appropriate data-gathering instruments is necessary as health researchers and interventionists expand their investigations to community-based minority adolescent populations. The creation of such instruments is a complex process, requiring the integration of multiple data-gathering and analytic approaches. Recent efforts have delineated several issues to be considered in survey design for minority populations: community collaboration; problem conceptualization; application of the presumed model of behavioral change; and dialect and format of delivery. This paper describes the process of creating a culturally and developmentally appropriate, theoretically grounded instrument for use in monitoring the impact of an AIDS educational intervention on the behavior and health outcomes of urban African-American pre-adolescents and early adolescents. Three phases of research were involved: preliminary (and ongoing) ethnographic research including extensive participant observation, as well as, focus group and individual interviews with 65 youths; construction and testing of the preliminary instrument involving two waves of pilot testing (N1 = 57; N2 = 45); and, finalization of the instrument including reliability testing and assessment of tool constructs and selection of the mode of delivery (involving 2 additional waves of pilot testing (N3 = 91; N4 = 351). The essential role played by the community in all phases of instrument development is underscored.

Adolescent↗
PubMed1995

Symmetry and synkinesis during rehabilitation of unilateral facial paralysis.

We evaluated biofeedback rehabilitation in patients with severe chronic unilateral facial paralysis, who had intact facial-motor innervation (House grades 3 to 5). Recovery of facial function was characterized (1) by grading facial movement symmetry, and (2) by counting the number of muscles exhibiting synkinesis during maximal execution of selected facial movements (e.g., smiling). Facial function in 21 patients typically improved by one House grade. Facial symmetry recovered rapidly during the first 5 months of treatment, and then improved more slowly. However, during this latter period, examination of the relationship between symmetry and synkinesis (visualized by a graph plotting symmetry grades on the x-axis, against the number of synkinetic muscles on the y-axis) indicated that overall facial control was improving even when House grading suggested that it was not. Such information should aid facial retraining and may clarify understanding of underlying rehabilitation mechanisms.

Adult↗
PubMed1995

Minimizing synkinesis during rehabilitation of the paralyzed face: preliminary assessment of a new small-movement therapy.

Neuromuscular rehabilitation can reduce the severity of chronic facial paralysis, but complete recovery is frequently impeded by synkinesis. We evaluated whether or not such synkinesis could be minimized by preventing its possible reinforcement during rehabilitation. We compared "standard" therapy, which uses the appearance of synkinesis to guide rehabilitation, with a new "small-movement" therapy, which uses smaller movements that should minimize possible subthreshold reinforcement of synkinesis. Ten subjects who had had facial paralysis for 0.5 to 27 years were randomly assigned to either therapy group. Blinded assessments were performed before and after ten 1-hour treatments given over a 1-month interval. Facial movements in both groups were significantly more symmetric after treatment. Although synkinesis tended to be reduced in the small-movement group, this reduction was not significant. The new therapy was at least as good as the standard one, and it may be better. Further studies are required to demonstrate this.

Adolescent↗
PubMed1995

Adenoid cystic carcinoma of the head and neck: a clinicopathologic study of 37 cases.

The records of 37 patients with histopathologically confirmed adenoid cystic carcinoma, who presented to McGill University's Department of Otolaryngology between 1956 and 1990, were reviewed to determine factors influencing local failure, distant metastases, and survival. Of the 37 cases, 12 developed local recurrences. Local failure was seen an average of 3.5 years following initial treatment, 62% of which were seen prior to 2 years. No statistically significant advantage was found for the use of postoperative radiotherapy in the prevention of local recurrences. Thirteen cases presented with or subsequently developed distant metastases. The mean interval between initial treatment and the appearance of distant disease was 8.1 years. A comparison of survival in patients with negative versus positive surgical margins was carried out. Survival at 15 years with negative margins remained 100%, while with positive margins, only 35% survived. Disease-free survival with negative and positive margins at 10 years was 80% and 31.1%, respectively. The effect of positive margins on survival was statistically significant with a p values between .01 and .001. The aim of this study was to demonstrate the importance of negative surgical margins with regard to survival. The results suggest that negative margins at initial resection significantly improve long-term disease-free survival.

Actuarial Analysis↗
PubMed1995

High dose interferon alpha-2b therapy for chronic hepatitis C: an open label study of the response and predictors of response.

OBJECTIVES: The current recommended dose of interferon (IFN) for chronic hepatitis C is 3 million units (m.u.) 3 times a wk for 6 months, although the optimal dose is uncertain. In an open label cohort format, we evaluated the response rate at 6 months, the relapse rate at 12 months, the predictors of response, and adverse effects in 34 patients (mean age 42.4 +/- 2.4 yr) with chronic hepatitis C who were treated with 5 m.u. IFN 3 times a wk for 6 months. RESULTS: Twenty-nine patients (85%) responded either totally (TR) or partially (PR), and five (15%) showed no response (NR). Of 18 TR, eight (45%) showed a sustained response (SR), and nine (50%) patients relapsed at 12 months of follow-up with an overall SR rate of 24%. Despite the high frequency of side effects (17-70%), all patients completed the treatment. Of interest, two of three PR treated for an additional 3-6 months with 7.5 m.u. of IFN became TR at 12 months. Univariate and multivariate analysis demonstrated that the known duration of hepatitis and/or abnormal ALT elevation was longer in responders (43.5 +/- 9.1 months) compared with NR (8.2 +/- 1.4 months) (p = 0.018). Age, alcohol abuse, mode of acquisition, transaminase levels, and liver histology did not differ significantly between responders and NR. HCV-RNA in serum by RT-PCR assay was performed in six TR and four PR pretreatment, immediately posttreatment, and 3-6 months later. Five TR showed disappearance of viral RNA posttreatment with reappearance at low concentrations in two patients who relapsed. In four PR, viral RNA was detectable at low concentrations posttreatment. CONCLUSIONS: 1) Higher dose IFN therapy yields higher response rates at 6 months than the dose currently recommended with acceptable toxicity, but does not improve the sustained response rate; 2) the only predictor of a favorable response in this study was a longer known duration of hepatitis/abnormal ALT elevations; 3) serum HCV-RNA levels often disappear with a total response and may be used to monitor the response to treatment and relapse.

Adult↗
PubMed1994

Sexual abuse: developmental differences in children's behavior and self-perception.

Developmental differences in behavior and self-perception were examined in a group of 44 preschool and school-age children referred for evaluation of sexual abuse and 41 comparison children with no history of sexual abuse, matched on age and gender, and from a similar socioeconomic background. Children suspected of having been sexually abused were rated by their parents as having more internalizing and externalizing problems than comparison children. When children rated their self-competence and social acceptance, there were no group differences between children based on their abuse status; however, there was significant within-group variation among the children suspected of having been sexually abused. Preschool children had elevated scores of perceived competence and social acceptance, and school-age children had depressed scores. There were no age differences among the children in the comparison group. The results suggest that among children suspected of abuse, not only does their self-perception vary by their developmental level, but preschool children may respond with elevated perceptions of themselves. Focusing on individual differences in children's response to suspicions of sexual abuse enables us to identify risk and protective factors that contribute to the psychological outcomes of child sexual abuse.

Child↗
PubMed1994

Operating characteristics of 18 different continuous-flow jet nebulizers with beclomethasone dipropionate liposome aerosol.

A study of 18 different commercially available continuous-flow, jet nebulizers was performed with a standard liposomal formulation of beclomethasone dipropionate (Bec-DP) prepared with dilauroyl phosphatidylcholine (Bec-DLPC). The analysis compared the total Bec-DP output from aqueous suspensions of Bec-DLPC containing an initial starting reservoir concentration of 0.5 mg/ml. Aerosols from each nebulizer tested were characterized by the mass median aerodynamic diameter, geometric standard deviation, drug output, and the predicted percentage regional deposition of inhaled Bec-DLPC liposomes within the human respiratory tract. These data can provide a basis for the selection of commercially available jet nebulizers for use with glucocorticoid liposome aerosols for treatment of asthma and other inflammatory lung diseases.

Aerosols↗
PubMed1994

Social influences on the sexual behavior of youth at risk for HIV exposure.

OBJECTIVES: Adolescents are increasingly at risk for infection with human immunodeficiency virus (HIV) and other sexually transmitted diseases, especially in poor urban minority communities. To aid the design of interventions in these communities, this study investigated the role of knowledge, attitudes, perceived parental monitoring, and peer behavior in the onset and progression of sexual behavior in children at risk for exposure to HIV. METHODS: A computerized personal interview was administered to 300 African-American 9- to 15-year-old children living in six public housing developments in a large US city. RESULTS: Although children's knowledge about the hazards of sex increased with age, their sexual activity also increased (from 12% sexually experienced at 9 years of age to more than 80% experienced at 15 years of age). Parental monitoring appeared able to influence sexual activity. However, the perceived behavior of friends was associated with the rate at which sexual activity progressed with age and the degree to which condom use was maintained with age. CONCLUSIONS: The early onset and prevalence of sexual behavior and the importance of peer group influence call for early interventions that simultaneously influence the parents and peers in children's social networks.

Adolescent↗
PubMed1994

DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates.

We describe "universal" DNA primers for polymerase chain reaction (PCR) amplification of a 710-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from 11 invertebrate phyla: Echinodermata, Mollusca, Annelida, Pogonophora, Arthropoda, Nemertinea, Echiura, Sipuncula, Platyhelminthes, Tardigrada, and Coelenterata, as well as the putative phylum Vestimentifera. Preliminary comparisons revealed that these COI primers generate informative sequences for phylogenetic analyses at the species and higher taxonomic levels.

Amino Acid Sequence↗
PubMed1994

Functional imaging of head and neck tumors using positron emission tomography.

Positron emission tomography (PET) is an imaging modality that generates in vivo maps of tissue radioactivity originating from a labelled substrate of glucose metabolism: 18-fluorine labelled deoxy-glucose (FDG). This study was undertaken to evaluate PET in the detection of head and neck malignancies, and to determine its effectiveness in diagnosing recurrent cancer in operated or irradiated fields. PET revealed that each biopsy-proven tumour is an area of increased radioactivity. Tumour radioactivity ranged from 130% to 300% above that of the cerebellum, and up to 650% above the contralateral, normal side. By basing the maps on tissue metabolic function, PET proved capable of distinguishing tumour (increased radioactivity) from scar tissue (reduced radioactivity). Its application may facilitate the diagnosis of recurrent tumours amid the fibrosis and distortion of normal architecture in operated, irradiated fields.

Adult↗
PubMed1994

Sexual practices and intentions among preadolescent and early adolescent low-income urban African-Americans.

OBJECTIVE: To assess the sexual practices and the social and intrapersonal influences on sexual practices and intentions which have an impact on the risk for acquired immunodeficiency syndrome among pre- and early adolescent, low-income African-American youths. DESIGN: Cross-sectional cohort study conducted in nine recreation centers serving three public housing developments in an eastern city. PARTICIPANTS: Three hundred fifty-one African-American youths 9 to 15 years of age. OUTCOME MEASURES: Past and intended sexual intercourse, and past and intended condom use determined by a risk assessment instrument delivered aurally and visually via a "talking" MacIntosh computer. RESULTS: The median age was 11 years; 35% of youths had had sexual intercourse and 20% of virgins thought it likely that they would become sexually active in the next six months. Age and male gender were correlated with sexual activity. Of sexually active youths 62% had used a condom during their last episode of coitus and 60% expected to do so at the next episode. Among sexually active youths, 24% of boys and 35% of girls had had anal intercourse. Rates of foreplay (nonpenetrative sex) were low even among sexually active youths. The median number of sexual partners in the past six months was two. Social influences from parents, peers, and partners in an intimate relationship were important for all four sexual outcomes both by univariate analysis and after logistic regression. IMPLICATIONS: A high percentage of the low-income, urban African-American pre- and early adolescents in this study are engaging or intending to engage in high-risk sexual behaviors. Acquired immunodeficiency syndrome reduction interventions for early adolescents should incorporate the importance of social influences from multiple sources.

Acquired Immunodeficiency Syndrome↗
PubMed1993

War and peace.

Mary Black describes the superhuman effort required to evacuate patients from the shattered city of Sarajevo. But, she says, what its people really need is an end to the fighting.

Refugees↗