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Biomedical subjects

J Blackburn

Publications and source records attributed to J Blackburn.

At least 19 recordsLinked to original sources
PubMed2006

CD 95 mediated apoptosis in embryogenesis: implication in tooth development.

INTRODUCTION: Understanding of apoptotic mechanisms involved in tissue shaping is of particular interest because of possible targeted modulation of the development of organ structures such as teeth. Research of CD 95 mediated apoptosis has been focused particularly on cell death in the immune system and related disorders. However, CD 95 mediated apoptosis is also involved in embryogenesis of many organs as the kidney, the lung, the intestine and tissue networks such as the nervous system. DESIGN: Narrative review. RESULTS: This review briefly summarizes the current knowledge of CD 95 mediated apoptosis in embryogenesis with possible implication in tooth development. CD 95 receptor and CD 95 ligand are found at early stages of tooth development. The data suggest some positive correlations with dental apoptosis distribution, particularly in the primary enamel knot where apoptosis occurs during elimination of this structure. CD 95 deficient (lpr) adult mouse tooth phenotype, however, did not show any alterations in final tooth pattern and morphology. CONCLUSION: To date studies of apoptotic machinery during tooth development show spatial localization of many of the components together with precise and localized timing of cell death. There is still much to be learned about the regulation and importance of apoptosis in tooth development. Nevertheless, the involvement of apoptotic regulatory mechanisms interplaying with other molecules participates to the cellular cross-talk in developing tissues, which opens possible targeted modulations as suggested, e.g. for future molecular dentistry.

Animals↗
PubMed2001

Prevalence of odontoclastic resorptive lesions in a population of clinically healthy cats.

The prevalence of odontoclastic resorptive lesions (ORLs) was determined in a clinically healthy cat population (228 cats) using both clinical (oral examination) and radiographic (full-mouth series with intraorally positioned dental film) methods. The overall prevalence rate was 29 per cent (mean age of the cat population 4.9 years). The mandibular third premolars (307, 407) were the most commonly affected tooth and the pattern of ORL development was symmetrical in most cats. The risk of having ORLs was found to increase with increasing age and cats with clinically and radiographically missing teeth were more likely to have the condition. Neutering, gender, age at neutering or mean whole mouth gingivitis index did not affect the prevalence of ORLs.

Age Distribution↗
PubMed2001

Molecular genetic heterogeneity in autosomal dominant drusen.

OBJECTIVE: Autosomal dominant drusen is of particular interest because of its phenotypic similarity to age related macular degeneration. Currently, mutation R345W of EFEMP1 and, in a single pedigree, linkage to chromosome 6q14 have been causally related to the disease. We proposed to investigate and quantify the roles of EFEMP1 and the 6q14 locus in dominant drusen patients from the UK and USA. DESIGN: Molecular genetic analysis. PARTICIPANTS: Ten unrelated families and 17 young drusen patients. MAIN OUTCOME MEASURES: Exons 1 and 2 of EFEMP1 were characterised by 5' rapid amplification of cDNA ends and direct sequencing. Exons 1-12 of EFEMP1 were then investigated for mutation by direct sequencing. A HpaII restriction digest test was constructed to detect the EFEMP1 R345W mutation. Marker loci spanning the two dominant drusen linked loci were used to generate haplotype data. RESULTS: Only seven of the 10 families (70%) and one of the 17 sporadic patients (6%) had the R345W mutation. The HpaII restriction digest test was found to be a reliable and quick method for detecting this. No other exonic or splice site mutation was identified. Of the three families without EFEMP1 mutation, two were linked to the 2p16 region. CONCLUSIONS: EFEMP1 R345W accounts for only a proportion of the dominant drusen phenotype. Importantly, other families linked to chromosome 2p16 raise the possibility of EFEMP1 promoter sequence mutation or a second dominant drusen gene at this locus. Preliminary haplotype data suggest that the disease gene at the 6q14 locus is responsible for only a minority of dominant drusen cases.

Adult↗
PubMed2000

Plastic wrapping of cot mattresses: results from a pilot study.

AIM: To assess the prevalence of plastic wrapping of cot mattresses and their thickness. METHODS: Mothers of infants less than six months attending Plunket clinics in Central Auckland were interviewed. The thickness of the plastic was measured. RESULTS: 99 of 110 (90%) mothers invited to participate were visited at home. The sample was socioeconomically advantaged. Most infants were breastfed and few slept prone. The prevalence of plastic wrapped cot mattresses was 23.2%, of which sixteen (out of 23) used BabeSafe and seven used other types. The mean thickness of the BabeSafe was 0.15 mm (range 0.12-0.19 mm) and the other types were 0.10 mm (range 0.04-0.13 mm). One sample of plastic was 0.04 mm. CONCLUSION: Thin plastic wrapping is being used and is potentially dangerous.

Adult↗
PubMed2000

The duty to warn and protect--impact on practice.

OBJECTIVE: To discuss the concepts of the duty to protect and the associated threat to confidentiality and their impact on practice for Canadian psychiatrists. METHOD: We review these concepts and provide a synthesis of legal cases impacting psychiatric practice. CONCLUSION: The onus is on the psychiatrist to make him or herself aware of the current state of the legal obligation with respect to duty to protect. The evolving concept of duty to protect has and will continue to have significant impact on the practice of psychiatry.

Canada↗
PubMed1992

Mechanical properties of microcallus in human cancellous bone.

Until now, the mechanical properties of the microcalluses that form in human cancellous bone have been unexplained. We measured the microhardnesses of microcalluses in cancellous bone, of the trabeculae within the microcalluses, of the trabeculae adjacent to microcalluses, and of trabeculae lacking microcalluses in a human tibia and femur. We observed no important differences between materials at the four different sites. Because the microhardness of bone is very closely related to its stiffness, this finding indicates that microcalluses are likely to stiffen the trabeculae in which they are formed, even though they may surround unhealed fractures of the cancellous trabeculae.

Adult↗
PubMed1992

The development of a radiometric assay for monocyte phagocytosis and killing.

Monocyte and macrophage phagocytosis and killing has an important role in host defence against infectious microorganisms. Established methods for investigating these activities in vitro are time-consuming, expensive and prone to subjective error. An in vitro assay has been developed which measures monocyte phagocytosis and killing of Candida albicans. In this system, monocyte function is assessed by a radiometric assay based on the incorporation of [3H]uridine into viable yeast cells. This technique allows the simultaneous but independent measurement of the average number of yeast cells ingested by monocytes and the percentage of the ingested organisms killed within a defined incubation period. These tests can be carried out on a single sample of peripheral blood, are relatively easy to perform, and provide objective results within 24 h of receipt of the specimen. This method gave consistent results when monocyte-enriched harvests were obtained by four different separation techniques. This assay could prove a valuable tool for the investigation of monocyte function in individuals with recurrent infections to determine the contribution this makes to their clinical condition. It may also be used to investigate in vitro the influence of cytokines and other chemical agents on monocyte function.

Blood↗
PubMed1988

A survey of hospital pharmacy research in Canada.

During the past two years, the CSHP Research Committee was given the tasks of evaluating the present status of hospital pharmacy research and developing positive recommendations for future action. In order to determine the specific needs and interests of Canadian hospital pharmacists, a survey of the CSHP membership was conducted in April of 1987. Two hundred and twenty-two members (13.1%) responded to the survey. Fifty-six percent (124) of the respondents had completed one or more research projects and 30 percent (66) served as supervisors of at least one research study. Clinical drug studies, particularly DUR and pharmacokinetic projects, were the focus of most of the present research efforts. In addition to DUR and pharmacokinetics, the most popular "wish to do" research topics included pharmaceutics, cost benefit/analysis and other pharmacy practice research topics. The survey respondents indicated a strong desire for CSHP to sponsor research similar to the Workload Measurement Study. The Canadian Society of Hospital Pharmacists was also requested to provide educational programs and other methods of information dissemination for training in the field of research methodology.

Canada↗
PubMed1986

Effect of glucose on amphetamine-induced motor behavior.

The effect of 1 g/kg D-glucose on amphetamine-induced increases in activity; stereotypy; and rotation in rats with unilateral 6-OHDA lesions of nigro-striatal neurons was examined. The amphetamine dose-response curve for stereotypy was shifted to the right by glucose but retained the same slope as the control curve, suggesting that glucose competes for amphetamine or dopamine receptors that mediate this behavior. The slope of the dose-response curve for activity was significantly decreased by glucose, suggesting that glucose reduces activity levels in a manner that is non-competitive with the action of amphetamine or dopamine. Amphetamine-induced turning was unaffected by glucose at all doses tested. These data suggest that the effect of amphetamine on each of the three motor behaviors may be mediated by different dopamine-containing neurons, or by different post-synaptic dopamine receptors. The findings are also consistent with other data suggesting that glucose antagonizes dopamine function, but they suggest that this antagonism may not be uniform over all dopaminergic neurons or receptor types.

Amphetamine↗
PubMed1985

Comparative immunohistologic studies in an adoptive transfer model of acute rat cardiac allograft rejection.

It has been shown that fulminant acute rejection of rat cardiac allografts across a full haplotype disparity may occur as a direct result of adoptive transfer of sensitized W3/25+ MRC OX8- SIg- T helper/DTH syngeneic spleen cells to sublethally irradiated recipients. In order to establish the immunohistologic parameters of this form of rejection, allografts and recipient lymphoid tissue were analyzed using a panel of monoclonal antibodies of known cellular distribution. These data were compared with those obtained following reconstitution of irradiated allograft recipients with unseparated sensitized spleen cells, with unreconstituted irradiated donor recipient pairs, with unmodified first-set rejection, and with induced myocardial infarction of syngeneic heart grafts transplanted to normal and to sublethally irradiated recipients. Rejecting cardiac allografts transplanted to all reconstituted irradiated recipients were characterized by extensive infiltration with MRC OX8+ (T cytotoxic-suppressor, natural killer) cells even when this subset was virtually excluded from the reconstituting inocula. A similar proportional accumulation of MRC OX8+ cells observed at the infarct margins of syngeneic heart grafts transplanted to irradiated unreconstituted recipients greatly exceeded that present in normal nonirradiated controls. These data provide evidence that under conditions of heavy recipient irradiation, MRC OX8+ cells may be sequestered within heart grafts in response to nonspecific injury unrelated to the rejection process. Although there was no significant degree of MRC OX8+ cellular repopulation within organized secondary lymphoid tissues of irradiated animals over the study period, the density of ileal mucosal MRC OX8+ lymphocytes approximated normal at 7 days post-irradiation, raising the possibility that these cells could share a common origin with those sequestered within the heart grafts. Carbon+ MRC OX6+ macrophages were a significant component of the infiltrate in all rejecting cardiac allografts, as well as in all infarcted syngeneic heart grafts--providing further evidence that macrophage "activation" with expression of class II determinants may occur in response to nonspecific injury. In unmodified first-set rejection there was an intense B cell reaction in recipient spleens and lymph nodes. In the adoptive transfer model, marked B cell expansion was exclusively confined to the parathymic lymph nodes of irradiated allograft recipients reconstituted with the sensitized W3/25+, MRC OX8-, SIg- T helper/DTH donor cell inocula.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Pulmonary lymphangiomyomatosis.

Lymphangiomyomatosis is an interesting disease with distinctive clinical and histopathologic findings. We report herein two additional cases of lymphangiomyomatosis, including one with clinical improvement after therapy with progesterone. This case is of particular significance in view of the patient's negative sex steroid receptor analysis. These findings open new avenues for future considerations in the therapy of this unusual but interesting disease.

Adult↗
PubMed1982

"No two fields ever grow grass the same way": assessment of conservation abilities in the elderly.

Within the past ten years, standard cognitive assessment procedures, including Piagetian tasks, have often been used with the elderly. The present paper examines several possible difficulties in interpreting the results of studied which employ Piagetian tasks, especially conservation tasks, with older individuals. First, it is noted that Piaget's clinical method allows more flexibility in the assessment of competence than do the more quantifiable, American techniques. However, most of the research studies suggesting a cognitive decline with age have utilized rigid assessment procedures. Second, the paper examines the possibility of task misinterpretation by the elderly. Examples from recent research, in which older persons stressed reality-based problem solving strategies rather than the more abstract strategies traditionally associated with Piagetian tasks, are provided. The possibility of cognitive change instead of cognitive decline with age is discussed, and the importance of utilizing procedures which can measure this change is stressed.

Aged↗
PubMed1981

The effect of a thirty per cent reduction in physician fees on Medicaid surgery rates in Massachusetts.

In this paper, we use an interrupted time series analysis to assess the effect of a 30 per cent reduction in the Medicaid reimbursement fee for physician services on the rate at which eight elective surgical procedures were performed in the Massachusetts Medicaid population. Tonsillectomy/adenoidectomy is the only procedure in which there was a statistically significant decline in the rate of surgery in most areas of the state following the fee cut. There is some evidence of an increase in the rate of disc surgeries/spinal fusions. The rate of other procedures increased in some areas of the state and decreased in other areas in the period after the fee cut.

Adenoidectomy↗
PubMed1980

Training cognitive functioning in the elderly--inability to replicate previous findings.

This study was designed to replicate Hornblum and Overton's study which trained conservation ability in elderly women [1]. Thirty-four elderly women volunteers were given a pretest battery of area and volume conservation tasks; participants also completed an extensive life history questionnaire. Conservation scores were the highest yet recorded by elderly participants. Thirty-two women received perfect conservation scores; only two were "partial conservers"; no participant was a "nonconserver." Consequently, training was not implemented. These women had high levels of education, good health, adequate income, satisfying leisure activities, and positive attitudes about aging. Advanced chronological age does not guarantee poor conservation performance. The mechanism(s) whereby life history variables influence cognitive functioning needs to be determined.

Aged↗