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Biomedical subjects

B Taylor

Publications and source records attributed to B Taylor.

At least 19 recordsLinked to original sources
PubMed1997

Homozygous inactivation of the NF1 gene in bone marrow cells from children with neurofibromatosis type 1 and malignant myeloid disorders.

BACKGROUND: The risk of malignant myeloid disorders in young children with neurofibromatosis type 1 is 200 to 500 times the normal risk. The gene for neurofibromatosis type 1 (NF1) encodes neurofibromin, a protein that negatively regulates signals transduced by Ras proteins. Genetic and biochemical data support the hypothesis that NF1 functions as a tumor-suppressor gene in immature myeloid cells, but inactivation of both NF1 alleles has not been demonstrated in leukemic cells from patients with neurofibromatosis type 1. METHODS: Using an in vitro transcription and translation system, we screened bone marrow samples from 18 children with neurofibromatosis type 1 and myeloid disorders for NF1 mutations that cause a truncated protein. Mutations were confirmed by direct sequencing of genomic DNA from the patients, and from their affected parents, in cases of familial neurofibromatosis type 1. RESULTS: Specimens from 9 of the 18 children contained abnormal peptide fragments, and truncating mutations of the NF1 gene were found in specimens from 8 of these children. The normal NF1 allele was absent in bone marrow samples from five of the eight children. We detected the same mutation in DNA from the affected parent of each child with familial neurofibromatosis type 1. CONCLUSIONS: Both alleles of the NF1 gene are inactivated in leukemic cells in some patients with neurofibromatosis type 1. NF1 appears to function as a tumor-suppressor gene in immature myeloid cells.

Bone Marrow↗
PubMed1997

Big battles for small gains: a cautionary note for teaching reflective processes in nursing and midwifery practice.

Since 1988, Australian university nursing courses have adopted the processes of educationalists in embracing reflective practitioner concepts and strategies. The assumption underlying reflective practice appears uniformly to be that if practitioners reflect on and in their practice worlds they can develop ways of changing them. This paper will outline some cautionary points in teaching reflective processes for use in nursing practice, given that they have been processes intent on mobilizing change in densely impacted hegemonic structures in healthcare organizations. To demonstrate that the limits of reflective practice may constitute big battles for small gains, a research project undertaken with practising midwives will be used as a case in point.

Curriculum↗
PubMed1997

Adolescents' attitudes to general practice in north London.

A questionnaire-based survey, undertaken in North London state secondary schools, illustrated some stumbling blocks and a lack of knowledge that is likely to inhibit an effective use of general practice among 12-18 year olds. A review of the current arrangements and some adjustment of current services might increase the likelihood of achieving Health of the Nation targets for teenage pregnancies, and may also improve health care for this important and vulnerable section of the population.

Adolescent↗
PubMed1996

Induction of programmed cell death and immunosuppression by exogenous sphingolipids are separate processes.

Gangliosides are highly immunosuppressive molecules but the mechanism(s) by which they act upon cells remains to be fully defined. Several metabolic products of exogenous gangliosides, including ceramide, have recently been suggested as second messengers in programmed cell death (PCD). Therefore, we have probed the role of gangliosides and ceramides in the induction of PCD and in the inhibition of in vitro lymphoproliferation. PCD was caused only by exogenous ceramides with short fatty acyl groups-d18:1-C2:0 (C2-ceramide, where d18:1 is sphingosine and C2:O is an acetyl group) and d18:1-C6:0 (C6-ceramide, where C6:O is a hexanoyl group). None of the gangliosides studied induced PCD, including naturally occurring GM3, synthetic d18:1-C18:0 GM3 (C18-Cer GM3, where C18:0 is a stearoyl group), or even d18:1-C2:0 GM3 (C2-Cer GM3), which itself contains a PCD-causing ceramide. However, these gangliosides were highly immunosuppressive, inhibiting antigen-induced lymphoproliferation at micromolar concentrations. We conclude that exogenous sphingolipids cause inhibition of lymphoproliferation and PCD by two separate and distinct mechanisms of action.

Apoptosis↗
PubMed1996

Quantitative morphology of physiologically identified and intracellularly labeled neurons from the guinea-pig laterodorsal tegmental nucleus in vitro.

Mesopontine cholinergic neurons have been implicated in the initiation and maintenance of rapid eye movement sleep via their efferent connections to the thalamus and the medial pontine reticular formation. As a first step toward understanding how these modulatory neurons integrate synaptic input, we have investigated the dendritic architecture of laterodorsal tegmental nucleus neurons. The principal cells of the guinea-pig laterodorsal tegmental nucleus were identified electrophysiologically in a brain slice preparation, then were intracellularly injected with biocytin and reconstructed using a computer-aided tracing system. The somata were large (27 +/- 3 microns; n = 11) and gave rise to an average of 4.8 primary dendrites which, in most cases, emerged from the soma in a pattern that was radially symmetric in the plane of the slice. Primary dendrites had an average of 3.7 endings. A single axon arose from either the soma or a proximal dendrite and exited the nucleus with a medial and/or lateral trajectory. Some axons also gave rise to a local terminal plexus composed of fine fibers bearing numerous punctate swellings that ramified profusely within the neuron's dendritic field. Total dendritic area averaged about 10(5) microns2, and therefore the average contribution of the soma to the total surface area (20%) was significantly larger than the values reported for many other cell types. Dendritic diameters were non-uniform in three respects. Some processes were sparsely spiny. Most processes were varicose, with the degree of varicosity increasing substantially in secondary and tertiary dendritic segments. There was also a large degree of taper in dendritic processes; those processes with a non-negative taper had an average diameter decrease of 40 +/- 25%. Dendritic processes deviated from the criteria necessary for a Rall equivalent cylinder approximation due to non-uniformity in morphotonic path length, failure to conform to the Rall 3/2 branching rule and non-uniformity of dendritic diameter. An analysis was done to assess the impact of dendritic varicosities on the extraction of cable parameters for these cells. Voltage traces were simulated by solving the cable equation for a varicose dendrite and then membrane parameters were recovered using an equivalent cylinder model. Errors in the extracted values of specific membrane conductance and specific membrane capacitance were quite small (< or = 5%), while larger errors were seen for electrotonic length (< or = 21%) and intracellular resistivity (< or = 5%). These data indicate that the principal cells of the laterodorsal tegmental nucleus, while possessing a relatively simple dendritic structure in terms of number and branchiness of dendrites, display a heterogeneity of dendritic process types. Processes range from smooth to markedly varicose, and can be aspiny or sparsely spiny. The possibility that the dendritic varicosities function as sites of either electrical or chemical compartmentalization is discussed. The degree of error resulting from a Rall equivalent cylinder approximation in light of these varicosities indicated that a generalized cable model approach may prove more effective in estimating their cable parameters.

Animals↗
PubMed1996

Enhancement of proxy appointment for older persons: physician counselling in the ambulatory setting.

OBJECTIVE: To determine the effectiveness of physician-initiated counselling on the rate of health care proxy appointment. DESIGN: Observational study of an intervention in a convenience sample. SETTING: A geriatric outpatient clinic in a tertiary care teaching hospital, New York, New York. PARTICIPANTS: A total of 687 patients enrolled in the geriatric clinic during the study period March 1991 through June 1993. INTERVENTION: Physician counselling about the New York State Health Care Proxy Law, distribution of educational materials and healthcare proxy forms, and reminders in 331 of 466 eligible patients. MEASUREMENTS: Rate of healthcare proxy appointment in eligible and counselled groups; predictors of appointment and non-appointment; time elapsed from counselling to appointment; reasons for non-appointment; characteristics of the proxy appointment process. RESULTS: A healthcare proxy was appointed for 31.5% of patients eligible for counselling and for 44% of patients who actually received the intervention, compared with a 2.3% proxy appointment rate at baseline. Eighty-one percent of the patients completing the proxy appointment process did so at or before their third clinic return visit after the counselling intervention. Of the counselled patients who did not appoint a proxy, 25% explicitly declined, and 75% had not come to a decision by the end of the study period. Proxy completion was associated with ethnicity, education, and more frequent clinic visits. Of those who appointed a proxy, 97% had good or fair comprehension of the procedure, 92% discussed the appointment with their designees, 63% appointed a daughter or son, and 80% discussed their wishes for care at the end of life with their proxy. CONCLUSIONS: Physician counselling of older outpatients is an effective means of increasing healthcare proxy appointments.

Advance Care Planning↗
PubMed1996

Social work with transport disabled persons: a wayfinding perspective in health care.

Transport disabled persons confront extensive architectural and psychosocial barriers during their travel to community based health care services by mass transit. The current health care reform movement affords social work an opportunity to consolidate its expertise with this population. The Certificate of Need program is a method with which social work can provide service to people with transportation disabilities. Social work can also continue its use of the Americans with Disabilities Act and the Urban Mass Transportation Act to assist people with transport disabilities to access community based health care services.

Delivery of Health Care↗
PubMed1996

1995 Roussel Lecture. Management of adenocarcinoma of the head of the pancreas: 10 questions for the 1990s.

Carcinoma of the head of the pancreas is a lethal condition because it presents clinically late in the disease and because of its unfavourable biologic course. Surgical approaches have become progressively more aggressive in recent years, without a significant increase in long-term survival. Controversy persists as to the appropriate surgical procedure for this disease, nonoperative or operative palliation, and and future prospects for management. This review considers questions often posed by clinicians and offers answers based on a literature reivew and the experience of the hepatobiliary service at the Toronto Hospital, Toronto General Division.

Adenocarcinoma↗
PubMed1996

Adjusting to criminal victimization: the correlates of postcrime distress.

This article explores the correlates of immediate and short-term psychological distress among victims of burglary, robbery, and nonsexual assault. A panel design was employed. Crime victims were interviewed within 1 month following the incident and again 3 months later. Four sets of predictors were examined: demographics, previctimization adjustment and stress, features of the crime incident, and victims' perceptions. Measures of distress included a range of standard indices of adjustment and symptomatology. Demographic characteristics and victim perceptions accounted for the greatest proportions of variance in the outcome measures at Time 1 and Time 2. The strongest predictors of psychological adjustment at the end of 3 months included adjustment after 1 month, education, victim injury, victims' beliefs that their lives had been endangered during the crime episode, and victims' appraisals of the world as meaningful. Implications for treatment and directions for future studies are discussed.

Adaptation, Psychological↗
PubMed1996

Laparoscopic versus open appendectomy: a prospective randomized trial of 81 patients.

OBJECTIVE: To compare the efficacy of laparoscopic appendectomy (LA) and open appendectomy (OA) in the treatment of acute appendicitis. DESIGN: A prospective randomized trial. SETTING: A university teaching hospital. PATIENTS: Eighty-one patients with a diagnosis of acute appendicitis were prospectively randomized to undergo either LA or OA. The two groups were matched for age and sex. INTERVENTIONS: LA or OA. MAIN OUTCOME MEASURES: Number of days in hospital and time to full recovery. RESULTS: The mean hospital stay for LA was 3.23 days compared with 3.03 days for OA (p < 0.001). The mean number of narcotic injections required for patients in the LA group was 4.05 compared with 5.58 for patients in the OA group (p < 0.001). The mean time to complete recovery for patients in the LA group was 9.0 days compared with 16.2 days for patients in the OA group (p < 0.001). The mean operative time for LA was 73.8 minutes compared with 45.0 minutes for OA (p < 0.001). Three patients in the LA group had intra-abdominal abscesses (p > 0.25). No significant difference in wound infection rates was demonstrated (p > 0.05). Similarly, pain scores at 7 and 28 days showed no significant difference (p > 0.05). CONCLUSIONS: With LA significantly fewer narcotic injections are required and there is a more rapid return to normal activities. LA takes longer to perform and was associated with three intra-abdominal abscesses. In cases of simple acute appendicitis the hospital stay for LA is significantly shorter.

Adult↗
PubMed1995

Interdigitation of nitric oxide synthase-, tyrosine hydroxylase-, and serotonin-containing neurons in and around the laterodorsal and pedunculopontine tegmental nuclei of the guinea pig.

The topography of neurons containing nitric oxide synthase (NOS) and monoamines was investigated in the guinea pig mesopontine tegmentum. NOS-containing neurons were identified with NADPH-diaphorase (NADPH-d) histochemistry, and monoamine-containing neurons were identified with tyrosine hydroxylase (TH) and serotonin (5-HT) immunocytochemistry. The distribution of NADPH-d positive cells was centered on the laterodorsal tegmental (LDT) and pedunculopontine tegmental (PPT) nuclei. Diaphorase-containing cells had a mean soma diameter of 23.0 +/- 4.1 microns (n = 160) and were distributed inhomogeneously, with numerous cells found within densely packed clusters. A nearest-neighbor analysis revealed that these cells were closely spaced, with up to 20% within one cell diameter and more than 50% within two cell diameters of a neighboring NADPH-d cell. Within the LDT and PPT, NADPH-d positive cells were mixed with smaller, diaphorase-negative cells (diam: 12.8 +/- 3.3 microns; n = 182; P << 0.01). TH-containing cells were not organized into a compact LC as in rat and their distribution more closely resembled that observed in cat. On average, TH-containing cells (diam: 21.2 +/- 4.8 microns; n = 160) were smaller than NADPH-d cells (P < 0.01). 5-HT-containing cells were mainly located in the raphe nuclei, as in other species. 5-HT-containing cells (diam: 18.2 +/- 4.4 microns; n = 161) were smaller on average than both the NADPH-d (P < 0.01) and TH-containing cells (P < 0.01). An analysis of the overlap in soma distributions revealed that TH-containing cells were largely interdigitated with NADPH-d containing cells. As much as 78% of the area occupied by the NADPH-d cells of LDT was contained within the area occupied by TH cells. Substantial numbers of TH and 5-HT immunoreactive processes were seen in both LDT and PPT. Varicose 5-HT and TH-containing fibers, as well as thicker, possibly dendritic processes containing TH were often seen in close apposition to NADPH-d containing somata and proximal dendrites. These results support the hypothesis that NADPH-d cells of both the PPT and LDT receive input from TH and 5-HT cells. Moreover, the clustered substructure of LDT and PPT and the extensive overlap of NADPH-d and TH-containing somata raise the possibility that the membrane permeable messenger nitric oxide plays a role in modulating TH-containing somata and their processes as well as 5-HT-containing processes in the LDT and PPT.

Animals↗
PubMed1995

An event recorder for infant feeding research.

An Event Recorder program was developed for the HP 48 calculator to record the durational events associated with breastfeeding behavior. The Event Recorder menu structure is flexible and allows for the recording of response variables such as menstrual history and fertility symptoms. A Windows program was written in Visual C++ to give a graphical representation of the time-series data and to extract useful measures of breastfeeding activity from the raw data for each 24-h day postpartum. These time varying covariates include the mean and median bout length, median interbout interval, breastfeeding frequency and total 24-h suckling duration. The HP 48 calculator has proven to be a robust instrument for the self-recording of breastfeeding data collected as part of a prospective study on the factors that maintain postpartum amenorrhea. We have found also that the behavioral data collected are easily transferred electronically each month when our field workers make home visits.

Breast Feeding↗
PubMed1995

A standardized patient program in a mandatory geriatrics clerkship for medical students.

This article describes the development and implementation of a new standardized patient program in a required geriatrics clinical clerkship for fourth-year medical students. A student survey was also conducted to provide evaluations of the program and to determine the frequency with which students' clinical skills are directly evaluated by faculty. Thirty-six percent reported never having been observed while obtaining a history and 24% having been observed only once; 26% had never been observed while completing a physical examination and 39% had been observed only once. The implementation of a standardized patient program provided students with direct feedback on their clinical skills and was rated positively, (good, very good, or outstanding) by 76% of the students.

Clinical Clerkship↗