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Biomedical subjects

M G Brown

Publications and source records attributed to M G Brown.

At least 19 recordsLinked to original sources
PubMed2000

Educating future physicians for Ontario: phase II.

In 1990, a collaborative project was launched to determine what the people of Ontario expect of their physicians and how the programs that prepare future physicians should be changed in response. The project, called Educating Future Physicians for Ontario (EFPO), brought together the five Ontario medical schools, the Council of Ontario Faculties of Medicine (COFM); a nonprofit, charitable organization, Associated Medical Services (AMS); and the Ontario Ministry of Health. The first phase ran for five years and was described in the November 1998 issue of Academic Medicine. After an external review, the project was continued for a second phase (EFPO II) for four more years until December 1998; that second phase is the topic of this article. EFPO II (1) focused more on residents' education; (2) emphasized four of the EFPO I-created physician roles in project activities; (3) maintained the province-wide, inter-institutional medical education framework of phase I, but fostered greater involvement of the seven sites (five medical schools and two regional health centers) in project activities; (4) stressed five project components (e.g., needs assessment and community partnerships) and worked for collaboration among components at all sites; (5) enhanced the original EFPO I Fellowship Program by adding residents and community fellows to the existing fellowships and by initiating leadership development activities, all of which bode well for the future leadership of medical education in Ontario. Students and residents played a vital role in EPFO II. Most of EFPO II's objectives were met, but the overall view of external reviewers was that the project was less successful than EFPO I. For example, the impact on clinical education, especially residency education, was less than anticipated. On the other hand, the project helped encourage the wide adoption of the eight physician roles that originated in EFPO I and advanced faculty development and assessment activities based on these roles. A third phase of EFPO concerning continuing medical education was planned, but support was not available. However, one of the funders will continue to support the successful fellowship and leadership program and the provincial education network for the next three years. Overall, the two phases of EFPO substantially modified medical education in Ontario to make it more responsive to evolving social needs.

Education, Medical↗
PubMed1999

Localization on a physical map of the NKC-linked Cmv1 locus between Ly49b and the Prp gene cluster on mouse chromosome 6.

The Cmv1 locus controls NK cell-mediated resistance to infection with murine CMV. Our recent genetic analysis of backcross mice demonstrated that the NK gene complex (NKC)-linked Cmv1 locus should reside between the Ly49 and Prp gene clusters on distal mouse chromosome 6. We have aligned yeast artificial chromosome (YAC) inserts in a contig spanning the interval between the Ly49 and Prp gene clusters. This YAC contig includes 13 overlapping YAC inserts that span more than 2 megabases (Mb) in C57BL/6 (B6) mice. Since we have identified genomic clones that span the Ly49-Prp gene region, we hypothesize that at least one should contain the Cmv1 locus. To narrow the Cmv1 critical region, we developed novel NKC genetic markers and used these to genotype informative backcross and intra-NKC recombinant congenic mouse DNA samples. These data suggest that Cmv1 resides on a single YAC insert within an interval that corresponds to a physical distance of approximately 390 kb. This high resolution, integrated physical and genetic NKC map will facilitate identification of Cmv1 and other NKC-linked loci that regulate NK cell-mediated immunity.

Animals↗
PubMed1999

Spectroscopic determination of the water pair potential.

A polarizable water pair potential was determined by fitting a potential form to microwave, terahertz, and mid-infrared (D2O)2 spectra through a rigorous calculation of the water dimer eigenstates. It accurately reproduces most ground state vibration-rotation-tunneling spectra and yields excellent second viral coefficients. The calculated dimer structure and dipole moment are very close to those determined from microwave spectroscopy and high-level ab initio calculations. The dimer binding energy and acceptor switching and donor-acceptor interchange tunneling barriers are in excellent agreement with recent ab initio theory, as are cyclic water trimer and tetramer structures and binding energies.

Algorithms↗
PubMed1999

Rubella susceptibility in Jamaican women, 1996.

The 1995 rubella outbreak in Jamaica indicated a need to survey the susceptibility rate in Jamaican antenatal women at risk. In this 1996 study, 389 women in the reproductive age group were investigated for rubella antibodies. In the public sector urban group (A), rubella susceptibility was 20.2%, while in a private sector urban clinic (B) practising routine rubella surveillance and recommending postpartum immunization in seronegatives, the susceptibility rate was 13.8%. The latter rate was significantly lower than that in the rural group (C) (35.9%; p < 0.001). The overall susceptibility rate was 21.3%. Rubella susceptibility has improved overall in women of childbearing age compared with levels in the prevaccine year of 1968. A significant thrust in rubella prevention will still be required before the next rubella epidemic in order to reduce the risk of congenital rubella syndrome.

Adolescent↗
PubMed1998

Clinical outcomes of four patients with microdeletion in the long arm of chromosome 2.

We present clinical outcome, through several years of follow-up, of 4 mentally retarded patients, each with a small interstitial deletion in the long arm of chromosome 2, within a region on which clinical reports are infrequent. Our patient 1 was found to have del(2)(q22.3q23.3); patients 2 and 3, del(2)(q23.3q24.2); and patient 4, del(2) (q24.2q31). By comparison of our cases with each other and with those previously published with comparable interstitial deletion, we attempted to identify characteristic clinical findings. Short neck with excessive cervical skin was seen with monosomy of chromosome 2 bands q22.3-q23.3, while hypertrichosis and a peculiar high pitched cry were seen with monosomy of chromosome 2 bands q23.3-q24.2. As suggested by Moller et al. [1984: Hum Genet 68:77-86], a cleft between the first and second toes was seen with monosomy of chromosome 2 bands q24.2-q31. In addition, seizure disorder was present in patients 1 and 4 (with the more proximal and distal deletions, respectively).

Adult↗
PubMed1998

Murine Nkg2d and Cd94 are clustered within the natural killer complex and are expressed independently in natural killer cells.

Natural killer (NK) cells express C-type lectin-like receptors, encoded in the NK gene complex, that interact with major histocompatibility complex class I and either inhibit or activate functional activity. Human NK cells express heterodimers consisting of CD94 and NKG2 family molecules, whereas murine NK cells express homodimers belonging to the Ly-49 family. The corresponding orthologues for other species, however, have not been described. In this report, we used probes derived from the expressed sequence tag database to clone C57BL/6-derived cDNAs homologous to human NKG2-D and CD94. Among normal tissues, murine NKG2-D and CD94 transcripts are highly expressed only in activated NK cells, including both Ly-49A+ and Ly-49A- subpopulations. Additionally, mNKG2-D is expressed in murine NK cell clones KY-1 and KY-2, whereas mCD94 expression is observed only in KY-1 cells but not KY-2. Last, we have finely mapped the physical location of the Cd94 (centromeric) and Nkg2d (telomeric) genes between Cd69 and the Ly49 cluster in the NK complex. Thus, these data indicate the expanding complexity of the NK complex and the corresponding repertoire of C-type lectin-like receptors on murine NK cells.

Amino Acid Sequence↗
PubMed1998

DNA cross-linker-induced G2/M arrest in group C Fanconi anemia lymphoblasts reflects normal checkpoint function.

Cells from individuals with Fanconi anemia (FA) arrest excessively in the G2/M cell cycle compartment after exposure to low doses of DNA cross-linking agents. The relationship of this abnormality to the fundamental genetic defect in such cells is unknown, but many investigators have speculated that the various FA genes directly regulate cell cycle checkpoints. We tested the hypothesis that the protein encoded by the FA group C complementing gene (FAC) functions to control a cell cycle checkpoint and that cells from group C patients (FA[C]) have abnormalities of cell cycle regulation directly related to the genetic mutation. We found that retroviral transduction of FA(C) lymphoblasts with wild-type FAC cDNA resulted in normalization of the cell cycle response to low-dose mitomycin C (MMC). However, when DNA damage was quantified in terms of cytogenetic damage or cellular cytotoxicity, we found similar degrees of G2/M arrest in response to equitoxic amounts of MMC in FA(C) cells as well as in normal lymphoblasts. Similar results were obtained using isogenic pairs of uncorrected, FAC- or mock-corrected (neo only) FA(C) cell lines. To test the function of other checkpoints we examined the effects of hydroxyurea (HU) and ionizing radiation on cell cycle kinetics of FA(C) and normal lymphoblasts as well as with isogenic pairs of uncorrected, FAC-corrected, or mock-corrected FA(C) cell lines. In all cases the cell cycle response of FA(C) and normal lymphoblasts to these two agents were identical. Based on these studies we conclude that the aberrant G2/M arrest that typifies the response of FA(C) cells to low doses of cross-linking agents does not represent an abnormal cell cycle response but instead represents a normal cellular response to the excessive DNA damage that results in FA(C) cells following exposure to low doses of cross-linking agents.

Caffeine↗
PubMed1998

Hospital-based psychiatric service utilization and morbidity in multiple sclerosis.

BACKGROUND: Despite the common association of psychiatric morbidity and multiple sclerosis (MS), population-based prevalence estimates of these disorders are limited. Such estimates are of particular importance to those conducting trials of interventions for the treatment of MS. This study examined the prevalence of bipolar disorder, depression, and attempted suicide among hospital service utilizers in Nova Scotia and compared these measures for the MS and non-MS population. METHODS: Data regarding diagnosis and utilization were extracted from two linked databases which included all hospital separation records for Nova Scotia over a 3 year period (1992/93-1994/95). RESULTS: The prevalence of bipolar disorder in hospitalized MS patients was 1.97% and depression was 4.27%. These rates were significantly higher than the 0.92% and 2.04%, respectively, for the non-MS hospital utilizers. These diagnoses also accounted for more than half of the primary diagnostic codes for psychiatric service separations by MS patients. The proportion of total hospital utilization which was accounted for by psychiatric services did not differ between MS and non-MS utilizers. While suicide attempts were rare, the estimated frequency of suicide attempts in the total MS population was more than three times that of the general population. CONCLUSIONS: Bipolar disorder and depression were twice as prevalent in hospitalized MS patients as in the general population of hospital utilizers while the estimated frequency of suicide attempts was at least three times greater. These results illustrate that psychiatric morbidity and service utilization are important considerations in the care of MS patients.

Bipolar Disorder↗
PubMed1998

Educating future physicians for Ontario.

In 1987, Ontario's physicians conducted a strike, ultimately not successful, over the issue of "extra billing." The fact that the Ontario public did not support this action reflected a major gap between the profession's view of itself and the public's view of the profession. In 1990, the province's five medical schools launched a collaborative project to determine more specifically what the people of Ontario expect of their physicians, and how the programs that prepare future physicians should be changed in response. The authors report on the first five years of that ongoing project. Consumer groups were asked to state their views concerning the current roles of physicians, future trends that would affect these roles, changes in roles they wished to see, and suggestions for changes in medical education. Methods used included focus groups, key informant interviews, an extensive literature review, and surveys, including a survey of health professionals. Concurrently, inter-university working groups prepared tools and strategies for strengthening faculty development, assessing student performance, and preparing future leadership for Ontario's medical education system. Eight specific physician roles were identified: medical expert, communicator, collaborator, health advocate, learner, manager ("gatekeeper"), scholar, and "physician as person." Educational strategies to help medical students learn to assume these eight roles were then incorporated into the curricula of the five participating medical schools. The authors conclude that the project shows that it is feasible to learn specifically what society expects of its physicians, to integrate this knowledge into the process of medical education reform, and to implement major curriculum changes through a collaborative, multi-institutional consortium within a single geopolitical jurisdiction.

Consumer Behavior↗
PubMed1997

A 2-Mb YAC contig and physical map of the natural killer gene complex on mouse chromosome 6.

We have constructed a physical map of a > 2-Mb region on mouse chromosome 6 that contains the natural killer gene complex (NKC). The map comprises a contig of 14 overlapping yeast artificial chromosomes onto which we positioned 25 NKC markers. NKC genetically linked genes encode > 17 proteins that directly control innate NK cell-mediated tumor lysis and disease resistance. Herein we show that Nkrp1 genes are clustered in a region flanked by A2m and Cd69 genes and that most Ly49 genes are clustered in a distal region -1 Mb distant. Importantly, syntenic intervals of mouse chromosome 6 and human chromosome 12p that include the NKC are conserved. NKC species conservation suggests that the human NKC may contain orthologues for the mouse viral disease resistance genes, Cmv1 and Rmp1. The high-resolution NKC map will facilitate investigation of NKC gene regulation and identification of phenotypically defined gene products that confer NK cell defense against viral pathogens.

Animals↗
PubMed1997

The Cmv1 host resistance locus is closely linked to the Ly49 multigene family within the natural killer cell gene complex on mouse chromosome 6.

Natural killer (NK) cells play important roles in controlling tumor cells and against a range of infectious organisms. Recent studies of mouse NK cell surface receptors, which may be involved in the specificity of NK cells, have shown that many of these molecules are encoded by the Ly49 and Ly55 (Nkrp1) multigene families that map to distal mouse chromosome 6. Also mapping to this NK cell gene complex (NKC) is the resistance locus, Cmv1, which is involved in genetically determined resistance to murine cytomegalovirus (MCMV). The aim of this study was to localize Cmv1 more precisely in relation to other NKC loci by generating a high-resolution genetic map of the region. We have analyzed 1250 backcross mice comprising panels of 700 (BALB/c x C57BL/6J)F1 x BALB/c and 550 (A/J x C57BL/6J)F1 x A/J progeny. A total of 25 polymorphic genes or microsatellite markers were analyzed over a region of 10 map units from D6Mit134 to D6Mit59. The Cmv1 phenotypes of mice recombinant in this interval were tested by infection with MCMV. The results obtained indicate that the functionally important NKC region is a tightly linked cluster of loci spanning at least 0.4 map units. Furthermore, Cmv1 maps distal to, but very closely linked to, the Ly49 multigene family (< 0.2 map units), suggesting that MCMV resistance may be conferred by MHC class I-specific NK cell receptors.

Animals↗
PubMed1997

The natural killer gene complex: a genetic basis for understanding natural killer cell function and innate immunity.

The natural killer gene complex encodes proteins, some of which are structurally unrelated, that impact on NK-cell function. Detailed analyses have indicated that these molecules are involved in NK-cell recognition, activation, and inhibition. The importance of this genomic region is highlighted by studies indicating that NKC-associated genes significantly influence NK cell-mediated innate host defense against life-threatening pathogens and that the NKC is conserved among diverse species. Thus, further elucidation of the NKC and its gene products will provide a genetic basis for understanding innate immunity and NK-cell activity at the molecular level.

Animals↗
PubMed1995

Interstitial deletions of the short arm of chromosome 4 in patients with a similar combination of multiple minor anomalies and mental retardation.

Interstitial deletions of chromosome 4 have been described rarely and have had variable presentations. We describe the phenotypic characteristics associated with interstitial deletion of the p14-16 region of chromosome 4 in 7 patients with multiple minor anomalies in common, and with mental retardation. A review of published cases of interstitial deletions of the short arm of chromosome 4 is provided. These deletions present a distinct phenotype which is different from that of Wolf-Hirschhorn syndrome.

Abnormalities, Multiple↗
PubMed1995

Prenatal diagnosis of chromosome 15 abnormalities in the Prader-Willi/Angelman syndrome region by traditional and molecular cytogenetics.

With improvements in culturing and banding techniques, amniotic fluid studies now achieve a level of resolution at which the Prader-Willi syndrome (PWS) and Angelman syndrome (AS) region may be questioned. Chromosome 15 heteromorphisms, detected with Q- and R-banding and used in conjunction with PWS/AS region-specific probes, can confirm a chromosome deletion and establish origin to predict the clinical outcome. We report four de novo cases of an abnormal-appearing chromosome 15 in amniotic fluid samples referred for advanced maternal age or a history of a previous chromosomally abnormal child. The chromosomes were characterized using G-, Q-, and R-banding, as well as isotopic and fluorescent in situ hybridization of DNA probes specific for the proximal chromosome 15 long arm. In two cases, one chromosome 15 homolog showed a consistent deletion of the ONCOR PWS/AS region A and B. In the other two cases, one of which involved an inversion with one breakpoint in the PWS/AS region, all of the proximal chromosome 15 long arm DNA probes used in the in situ hybridization were present on both homologs. Clinical follow-up was not available on these samples, as in all cases the parents chose to terminate the pregnancies. These cases demonstrate the ability to prenatally diagnose chromosome 15 abnormalities associated with PWS/AS. In addition, they highlight the need for a better understanding of this region for accurate prenatal diagnosis.

Adult↗
PubMed1995

Laparoscopic 'physiological' antireflux procedure: preliminary results of a prospective symptomatic and objective study.

The 'physiological' antireflux procedure has been shown to be as effective as Nissen fundoplication in reflux control, but with a significant reduction in the incidence of mechanical complications. This technique was attempted laparoscopically in 26 patients in a prospective study involving independent symptomatic, manometric and pH assessment performed before operation and at a mean of 5.5 months after operation. The procedure was successfully completed laparoscopically in 23 (88 per cent) patients. Mean hospital stay was 3.8 days and mean time to return to work 1.8 weeks. There was neither mortality nor reoperation; 91 per cent of patients obtained symptomatic relief (82 per cent Visick grade 1). There was no gas-bloat or inability to belch or vomit. All 14 patients who underwent objective testing had a normal oesophageal pH profile, the mean percentage total time that pH < 4 falling from 11.0 to 1.1 (P < 0.001). Lower oesophageal sphincter characteristics, including relaxation, were similar to control values. These preliminary results suggest symptomatic and objective results comparable to those following open surgery, but with the benefits of a shorter hospital stay and time off work. In addition to a lower incidence of mechanical complications, the relative ease of performance of this procedure confers an additional advantage over Nissen fundoplication when performed laparoscopically.

Adolescent↗