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Biomedical subjects

N Pollock

Publications and source records attributed to N Pollock.

18 recordsLinked to original sources
PubMed1998

In vitro microtubule-based organelle transport in wild-type Dictyostelium and cells overexpressing a truncated dynein heavy chain.

The transport of vesicular organelles along microtubules has been well documented in a variety of systems, but the molecular mechanisms underlying this process are not well understood. We have developed a method for preparing extracts from Dictyostelium discoideum which supports high levels of bidirectional, microtubule-based vesicle transport in vitro. This organelle transport assay was also adapted to observe specifically the motility of vesicles in the endocytic pathway. Vesicle transport can be reconstituted by recombining a high-speed supernatant with KI-washed organelles, which do not move in the absence of supernatant. Furthermore, a microtubule affinity-purified motor fraction supports robust bidirectional movement of the salt-washed organelles. The plus and minus end-directed transport activities can be separated by exploiting differences in their affinities for microtubules in the presence of 0.3 M KCl. We also used our assay to examine organelle transport in a strain of Dictyostelium overexpressing a 380-kDa C-terminal fragment of the cytoplasmic dynein heavy chain, which displays an altered microtubule pattern (380-kDa cells; [Koonce and Samso, Mol. Biol. Cell 7:935-948, 1996]). We have found that the frequency and velocity of minus end-directed membrane organelle movements were significantly reduced in 380-kDa cells relative to wild-type cells, while the frequency and velocity of plus end-directed movements were equivalent in the two cell types. The 380-kDa C-terminal fragment cosedimented with membrane organelles, although its affinity was significantly lower than that of native dynein. An impaired membrane-microtubule interaction may be responsible for the altered microtubule patterns in the 380-kDa cells.

Animals↗
PubMed1997

Gender and comorbid psychopathology in adolescents with alcohol dependence.

OBJECTIVE: Although several mental disorders have been shown to be common in adolescents with substance use disorders, prior studies have not specifically focused on alcohol dependence and have not had sufficient sample sizes to examine gender effects. This study contrasts mental disorder diagnoses and symptoms between a sample of adolescents with alcohol dependence and a community control sample of adolescents and incorporates gender analyses. METHOD: Adolescents (aged 14 years 0 months to 18 years 0 months) with alcohol dependence (females: n = 55; males: n = 78) and community-dwelling control adolescents without substance use disorders (females: n = 44; males: n = 42) were assessed by means of a semistructured interview for DSM-III-R. RESULTS: While cannabis and hallucinogen use disorders were common in the alcohol dependence group, females and males had similar rates. Conduct disorder (CD), oppositional defiant disorder, attention-deficit hyperactivity disorder, major depression (MD), and posttraumatic stress disorder (PTSD) had significantly higher rates in the alcohol dependence than in the community control group. Depression and PTSD symptoms were more strongly associated with alcohol dependence in females than in males. A configural frequency analysis showed that CD and MD tended to occur together in both female and male adolescents with alcohol dependence. CONCLUSIONS: While alcohol-dependent females and males similarly exhibited more comorbid disorders than control adolescents, gender affects the relationship of alcohol dependence to MD and PTSD. Rather than reflecting distinct types, the comorbid disorders of CD and MD jointly characterize many adolescents with alcohol dependence.

Adolescent↗
PubMed1997

A comparison of intensive neurodevelopmental therapy plus casting and a regular occupational therapy program for children with cerebral palsy.

The purpose of this research was to evaluate the combined effect of intensive neurodevelopmental therapy (NDT) and casting in improving hand function, quality of upper-extremity movement and range of motion in children aged between 18 months and 4 years with cerebral palsy (CP). A randomized crossover design was used to evaluate the difference between intensive NDT plus casting and a less intensive regular occupational therapy (OT) program. Blinded assessments of hand function, quality of upper-extremity movement, and parents' perception of hand-function performance were carried out at baseline, 4 months (end of first intervention period), 6 months (after a 2-month 'washout' period), and 10 months (end of second intervention period). Analysis of the outcomes revealed no significant differences in hand function, quality of upper-extremity movement, or parents' perception of hand-function performance between the two treatment groups-intensive NDT plus casting or regular OT programs. There does not appear to be any beneficial effect of an increased amount of therapy for the children in this study.

Activities of Daily Living↗
PubMed1993

Client-centered assessment.

When occupational therapists assess function or occupational performance, they must consider each person's unique needs and abilities, as well as the environmental and social factors that may be affecting the clients' performance. Therefore, occupational therapists must use evaluation tools that are individualized and sensitive to the clients' varying needs and situations. One approach to individualized evaluation is the use of a client-centered process of setting goals and assessing change. This paper describes the development of a methodology for a client-centered assessment currently being used in Canada, the Canadian Occupational Performance Measure (COPM). The conceptual model, administration and scoring procedures, and preliminary feedback to the COPM are described.

Activities of Daily Living↗
PubMed1993

Risks to hearing from a rock concert.

We measured noise exposure and temporary threshold shift (TTS) from a rock concert for 22 volunteers, using dosimetry, questionnaires, and audiometry. Most (81%) participants showed TTS of 10 dB or more 5 to 25 minutes after exposure; of these, 76% showed continued TTS at 40 to 60 minutes. Family physicians should counsel patients about the risks of recreational noise.

Adolescent↗
PubMed1992

Propofol is a 'safe' anaesthetic agent in malignant hyperthermia susceptible patients.

In this study we investigated in vitro and in vivo effects of propofol in malignant hyperthermia susceptible (MHS) patients in order to assess the safety of propofol infusion as a non-triggering anaesthetic technique for diagnostic and therapeutic procedures. In vitro, human MHS muscle samples were exposed to propofol and changes in (a) baseline tension and (b) contracture tension on exposure to halothane and caffeine were measured. In vivo, (a) anaesthesia was induced in ten muscle biopsy positive MHS patients with propofol 2.5 mg/kg and (b) anaesthesia was produced in five muscle biopsy positive MHS patients with infusions of propofol up to 10 mg/kg/hr. In vitro, human MHS muscle did not develop contractures with propofol alone. Propofol had no significant effect on contracture development in response to halothane and caffeine. In vivo, no evidence of an MH response was detected following induction or maintenance of anaesthesia with propofol. Our results and literature review are in agreement that propofol is a 'safe' induction and maintenance agent in MHS patients. Propofol can be used for muscle biopsy anaesthesia because it does not alter the sensitivity of diagnostic muscle biopsy testing.

Adolescent↗
PubMed1992

Reliability and construct validity of the Clinical Observations of Motor and Postural Skills.

The Clinical Observations of Motor and Postural Skills (COMPS) is a screening tool for children with motor incoordination. A study of reliability (test-retest, interrater, and internal consistency) and construct validity with 132 children, both with and without developmental coordination disorder, is reported here. Test-retest reliability over 2 weeks was high: .92 for a group of 48 children. Interrater reliability for occupational therapists experienced in pediatrics was also excellent: .87 for a group of 72 children. Internal consistency of the COMPS was high, particularly when one of the seven items (Schilder's arm extension) was deleted. The test discriminates well between children with and without motor problems and has many properties of a good screening test.

Child↗
PubMed1991

Play deprivation in children with physical disabilities: the role of the occupational therapist in preventing secondary disability.

Self-initiated free play experiences are vital for the normal growth and development of all children. In this paper, children with physical disabilities who are deprived of normal play opportunities are viewed as having a second disability that hinders their potential for independent behavior and performance. Physical, social, personal, and environmental barriers that may limit the play experiences of children with physical disabilities are delineated. Studies of the interactions of these children during play are discussed, and a case is made for the promotion of active, free play in the home, the school, and the community. As facilitators of this process, occupational therapists must consider a variety of factors, including the unique capabilities of the child, the influence of parent-child and peer relationships, the role of other caregiving adults, the adaptation of toys and materials, and the impact of the environment and setting.

Caregivers↗
PubMed1990

Occupational performance measures: a review based on the guidelines for the client-centred practice of occupational therapy.

In 1987, Health and Welfare Canada and the Canadian Association of Occupational Therapists Task Force recommended that work go forward to develop an outcome measure for occupational therapy which reflects the Occupational Performance Model. The first step in this process was to review critically those outcome measures which assess occupational performance and that are currently available in the literature. This paper will present the review process, describe in more detail eight assessments that fulfilled many of the review criteria, discuss the limitations of these measures using the "Guidelines for the Client-centred Practice of Occupational Therapy as the framework, and make recommendations for the development of a new outcome measure for use in occupational therapy.

Activities of Daily Living↗
PubMed1990

The Canadian occupational performance measure: an outcome measure for occupational therapy.

The Canadian Association of Occupational Therapists, in collaboration with Health and Welfare Canada have developed and published a conceptual model for occupational therapy, the Occupational Performance model. This paper describes the development of an outcome measure, The Canadian Occupational Performance Measure (COPM), which is designed to be used with these guidelines for client-centred clinical practice. The COPM is an outcome measure designed for use by occupational therapists to assess client outcomes in the areas of self-care, productivity and leisure. Using a semi-structured interview, the COPM is a five step process which measures individual, client-identified problem areas in daily function. Two scores, for performance and satisfaction with performance are obtained. This paper describes the rationale and development of the COPM as well as information about its use for therapists.

Canada↗
PubMed1985

Incidence of hepatitis A virus (HAV) infection in rural Liberia.

To provide background for future hepatitis A vaccine trials, sera were collected from 0- to 4-year-old Liberian infants and their mothers on two occasions an average of 14.75 months apart and tested for antibody to hepatitis A virus (anti-HAV). The prevalence of anti-HAV rose from 2.5% in infants 0-6 months of age to 70% in children 3-4 years of age and did not differ between male and female infants. The annual incidence of new infections was slightly lower in the first year of life (35%) than in the subsequent 3 years, when it averaged 45%. The presence of HBV infection did not affect the incidence of HAV seroconversion. No clinical hepatitis was recognized in the subjects who seroconverted. Dual hepatitis A and B virus infection were observed; these were all clinically inapparent. The extraordinary incidence of HAV infection documented in the present study offers an opportunity for vaccine efficacy trials requiring minimal numbers of subjects.

Adolescent↗
PubMed1981

Epidemiology of hepatitis B infection in Liberian infants.

To provide background for a hepatitis B vaccine efficacy trial, sera were collected from 0- to 4-year-old Liberian infants and their mothers, on two occasions an average of 14.75 months apart, and tested for serological markers of hepatitis B virus infection. The prevalence of the hepatitis B surface antigen (HBsAg) was 2.9% in the 0- to 6-month age group and 23% in infants 3 to 4 years of age. HBsAg persisted for the 14.75-month average follow-up period in 80.8% of the infants tested. The annual incidence of development of HBsAg was 18.9% for infants less than 1 year of age and 13.6% in infants 3 to 4 years of age. Infants born to HBsAg carrier mothers had significantly higher age-specific prevalence and incidence of hepatitis B virus infection. However, it was estimated that only a minor proportion of hepatitis B infections in Liberia are derived by vertical transmission from carrier mothers.

Adolescent↗