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David Marsh

Publications and source records attributed to David Marsh.

11 recordsLinked to original sources
PubMed2006

Predictors of non-fatal overdose among a cohort of polysubstance-using injection drug users.

BACKGROUND: Non-fatal overdose is a major determinant of morbidity among injection drug users (IDU). We sought to evaluate factors associated with non-fatal overdose among IDU in Vancouver. METHODS: We examined non-fatal overdose among participants in the Vancouver Injection Drug Users Study. Correlates of non-fatal overdose occurring between 1996 and 2004 were identified using generalized estimating equations (GEE). RESULTS: There were 1587 participants included in this analysis, including 576 (36%) women. At baseline, 750 (47%) reported a history of non-fatal overdose. In total, 985 reports of non-fatal overdose were made during follow-up by 519 (32.7%) participants. In multivariate GEE analyses, factors independently associated with non-fatal overdose included: heroin injection (AOR=2.67), cocaine injection (AOR=2.01), benzodiazepine use (AOR=2.00), requiring help injecting (AOR=1.58), binge drug use (AOR=1.52), homelessness (AOR=1.38), alcohol use (AOR=1.32), street injecting (AOR=1.22), non-injectable opiate use (AOR=1.16), speedball use (AOR=1.15), and recent incarceration (AOR=1.14). Younger age (AOR=0.99) and methadone use (AOR=0.51) were protective. CONCLUSIONS: We found that non-fatal overdose was common among local IDU. Non-fatal overdose was associated with several factors that may be amenable to intervention, including opiate and stimulant use, and the characteristic of requiring help with injecting. These findings indicate the need for the ongoing development of structural interventions to address this common cause of morbidity among IDU.

Adolescent↗
PubMed2006

Nonadherent cell population of human marrow culture is a complementary source of mesenchymal stem cells (MSCs).

To obtain enough quantity of osteogenic cells is a challenge for successful cell therapy in bone defect treatment, and cell numbers were usually achieved by culturing bone marrow cells in a relatively long duration. This study reports a simple and cost-effective method to enhance the number of mesenchymal stem cells (MSCs) by collecting and replating the nonadherent cell population of marrow MSCs culture. Bone marrow MSCs were isolated from 11 patients, cultured at a density of 1 x 10(5)/cm(2) to 1 x 10(6)/cm(2) in flasks. For the first three times of media change, the floating cells were centrifuged and replated in separate flasks. The total number of cells in both the primary and replating flasks were counted at day 21. Cell proliferation rate, potentials for osteogenic, chondrognenic, and adipogenic differentiation were examined in both cell types in vitro. In vivo osteogenic potentials of the cells were also tested in mice implantation model. The results showed that MSCs derived from nonadherent cell population of marrow cell cultures have similar cell proliferation and differentiation potentials as the originally attached MSCs in vitro. When implanted with hydroxyapatite/tricalcium phosphate (HA-TCP) materials subcutaneously in serve combined immune deficiency (SCID) mice, newly formed bony tissues were found in both cell type groups with osteocalcin expression. We have obtained 36.6% (20.70%-44.97%) more MSCs in the same culture period when the nonadherent cell populations were collected. The findings confirmed that the nonadherent cell population in the bone marrow culture is a complementary source of MSCs, collecting these cells is a simple and cost-effective way to increase MSCs numbers and reduce the time required for culturing MSCs for clinical applications.

Animals↗
PubMed2005

Factors associated with methadone maintenance therapy use among a cohort of polysubstance using injection drug users in Vancouver.

We identified methadone maintenance therapy (MMT) use during follow-up interviews and examined associations between MMT use and socio-demographic and drug-related variables using generalized estimating equations (GEE). Of the 1587 participants recruited into this cohort, 170 (11%) were enrolled in MMT at baseline and additional 498 (31%) initiated MMT during follow-up. Of those ever enrolled in MMT, 406 (61%) ceased MMT and re-initiated MMT on more than one occasion. The median treatment duration was 14.4 months. Factors that were negatively and significantly associated with MMT use in multivariate analyses included: Aboriginal ethnicity (adjusted odds ratio [AOR] = 0.40); recent incarceration (AOR = 0.79); sex trade involvement (AOR = 0.87); syringe lending (AOR = 0.72); heroin injection (AOR = 0.64), whereas female gender (AOR = 2.47), HIV positivity (AOR = 1.57), and crack cocaine smoking (AOR = 1.23) were positively and significantly associated with being on MMT. Unstable housing, syringe borrowing, non-fatal overdose, cocaine injection, and residence in Vancouver's Downtown Eastside were not associated with MMT use in multivariate analyses. Our study demonstrates high rates of initiation of and retention in MMT among local IDUs. While the use of MMT was associated with reductions in heroin use and HIV risk behavior, barriers to Aboriginal IDUs were evident, and the association with increased crack cocaine use deserves further study.

Adult↗
PubMed2005

Systemic recruitment of osteoblastic cells in fracture healing.

We hypothesise that following a bone fracture there is systemic recruitment of bone forming cells to a fracture site. A rabbit ulnar osteotomy model was adapted to trace the movement of osteogenic cells. Bone marrow mesenchymal stem cells from 41 NZW rabbits were isolated, culture-expanded and fluorescently labelled. The labelled cells were either re-implanted into the fracture gap (Group A); into a vein (Group B); or into a remote tibial bone marrow cavity 48 h after the osteotomy (Group C) or 4 weeks before the osteotomy was established (Group D), and a control group (Group E) had no labelled cells given. To quantify passive leakage of cells to an injury site, inert beads were also co-delivered in Group B. Samples of the fracture callus tissue and various organs were harvested at discrete sacrifice time-points to trace and quantify the labelled cells. At 3 weeks following osteotomy, the number of labelled cells identified in the callus of Group C, was significantly greater than following IV delivery, Group B, and there was no difference in the number of labelled cells in the callus tissues, between Groups C and A, indicating the labelled bone marrow cells were capable of migrating to the fracture sites from the remote bone marrow cavity. Significantly fewer inert beads than labelled cells were identified in Group B callus, suggesting some of the bone-forming cells were actively recruited and selectively chosen to the fracture site, rather than passively leaked into the circulation and to bone injury site. This investigation supports the hypothesis that some osteoblasts involved in fracture healing were systemically mobilised and recruited to the fracture from remote bone marrow sites.

Animals↗
PubMed2005

Surfing new territory: club-drug use and risky sex among Hispanic men who have sex with men recruited on the Internet.

The Internet presents unique and growing opportunities for conducting HIV/ STD research. This article reports on the first 171 participants enrolled in an ongoing study examining use of the Internet to recruit Hispanic men who have sex with men (HMSM) living in an AIDS epicenter to participate in community-based studies. First, it describes initial success with chatroom recruitment. Second, it compares the demographic, psychosocial, and sexual risk practices among HMSM recruited through the Internet who had used club drugs in the last 6 months and those who had not. In 2 months, 211 hours were spent recruiting in chatrooms; 735 chatroom users were engaged. Researchers used a scripted dialogue to describe the study and to invite chatroom users to visit the study's community sites for screening and enrollment. One hundred and seventy-six men came to the community sites; 172 (98%) were eligible and completed an audio-computer assisted self-interview. In the last 6 months, 48.5% of the sample had used club drugs [defined as cocaine, crystal methamphetamines (crystal), amyl nitrites (poppers), Ecstasy, gamma-hydroxybutyrate (GHB), ketamine (Special K), and Viagra]. The proportion of men reporting use of each drug was: cocaine (15.8%), crystal (11.7%), poppers (31.6%), Ecstasy (14%), GHB (3.5%), Special K (3.5%), and Viagra (19.3%). In multivariate analyses, having higher number of sex partners, having higher social isolation scores, and having engaged in unprotected receptive anal intercourse were significantly associated with club-drug use. These initial findings suggest that high-risk HMSM can be successfully recruited through chatroom dialogues to participate in community-based HIV studies. The alarmingly high rates of club-drug use and risky sexual practices among HMSM underscore the need for effective HIV preventive interventions for this population.

Adult↗
PubMed2004

Orthogeriatric care in patients with fractures of the proximal femur.

How are we to cope with the complex problems that now surround elderly patients with fractures? What are these problems and what systems should be in place to address them? No matter how successful we may be in treatment of osteoporosis and prevention of falls, it is inevitable that a massive worldwide increase in incidence of fragility fractures will occur in the next 50 years. It is crucial that we upgrade our systems to cope with this, if severe disruption of health services is to be avoided. This review considers the topics of falls, osteoporosis, and impact modification. We review the major medical issues that should be addressed in delivering hospital care that is efficient and of high quality. Various models for organizing the necessary liaison between fracture staff and medical or geriatric staff are examined and the current literature regarding orthogeriatric care is reviewed. We propose that the model of continuous orthogeriatric care, as practiced in Belfast, may be the way forward in addressing the complex problems associated with elderly patients with fractures. A system of ongoing audit of treatment outcomes and the journey of care for elderly patients with fractures of the proximal femur is necessary as a monitoring tool in developing the optimal system for orthogeriatric liaison.

Accidental Falls↗
PubMed2003

The effect of providing fansidar (sulfadoxine-pyrimethamine) in schools on mortality in school-age children in Malawi.

Malaria is a major cause of death in school-age (5-18 years) children in Malawi. Save the Children Federation helped schools in Mangochi District, Malawi, to obtain pupil-treatment kits, which enabled teachers to dispense sulfadoxine-pyrimethamine tablets according to national guidelines. The overall and malaria-specific mortality rates were calculated for the 3 years before and 2 years after the intervention was introduced; rates dropped from 2.2 to 1.44 deaths/1000 student-years and from 1.28 to 0.44 deaths/1000 student-years, respectively. School-based interventions could play a part in mitigating malaria.

Adolescent↗
PubMed2003

Impact of methadone program philosophy changes on early treatment outcomes.

This paper describes the consequences of changing from methadone maintenance treatment focussed primarily on elimination of all illicit drug use and social reintegration to patient-centred care. Counselling (formerly mandatory) became optional, patients were retained in treatment despite continued illicit drug use, the ceiling on methadone doses was removed, patient input became a part of methadone prescribing and the number of patients in treatment more than doubled. Across three cohorts (before, during and after the program was redesigned) the mean daily dose of methadone increased (50.4 mg +/- 2.5, 72.6 mg +/- 2.4, 92.2 mg +/- 4.0, respectively). The number of physician visits increased linearly with cohort while the number of therapist visits was unchanged overall. Two-year treatment retention was not significantly different (73%, 69% and 67%, respectively). In all three cohorts there was a significant reduction in opioid and benzodiazepine use but not cocaine use over the first six months of treatment.

Adult↗
PubMed2002

Changing patient characteristics with increased methadone maintenance availability.

Over the past several years there have been repeated calls for expansion of availability of methadone maintenance in several jurisdictions. Important stakeholders in the expansion of methadone maintenance treatment (MMT) are existing treatment providers. This study describes the impact of the rapid expansion in treatment availability in Ontario on the long-standing MMT program of the Centre for Addiction and Mental Health (CAMH). This expansion occurred through enlarging existing treatment programs, the provision of MMT in private physicians' offices and the establishment of new clinics. With expansion in the community, demand for the clinic-based treatment of the CAMH MMT program did not drop, in fact the patient population was able to continue to grow. There was a broadening of the patient profile in the program including patients who were better educated, more likely to be employed and less likely to be currently injecting (although with a significant history of past injection drug use). Moreover, in the face of these changes, excellent treatment retention was maintained. This suggests that the expansion in treatment availability did not impact negatively on the existing program but rather enabled access for a group of higher functioning opioid dependent patients who were previously being deterred from treatment entry by the large waiting lists and the need for priority access for pregnant and HIV positive heroin users. These findings should provide encouragement for MMT providers in jurisdictions anticipating or undergoing expansion of treatment availability.

Adult↗
PubMed2002

Cell proliferation and apoptosis during fracture healing.

This study investigated the relation between cell proliferation and apoptosis during fracture healing in a mouse femoral fracture model. Left femoral osteotomies were performed in 30 mature male CFLP mice immobilized with uniplanar external fixators. Six animals were killed on days 2, 4, 8, 16, and 24 postfracture for examination. Localization of cell proliferation was examined using immunohistochemistry with proliferating cell nuclear antigen (PCNA) monoclonal antibody. Apoptotic cells were visualized with the terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end-labeling (TUNEL) method. Images of each time-specific specimen were captured. The total callus area, the positively labeled cells by PCNA, and TUNEL per high-power field were quantified. Cell proliferation and apoptosis were found coexisting during the entire period of study. In the early phases of fracture healing (days 2-8), PCNA-positive labeling was predominant and peaked at day 8 and the TUNEL-positive labeling was minimal. In later stages of fracture healing (days 16-24), PCNA expression declined at day 16 as callus ossification and remodeling spread within the fracture site and apoptosis was the dominant cell activity with the TUNEL-positive labeling peaking at day 16 and declining sharply at day 24. These cell activities were reflected by the change of fracture callus, where there was a continuous increase in total callus area to day 16 and subsequent decrease at day 24. This study indicated that cell proliferation and apoptosis are coupled events during fracture repair, cell proliferation is active at the early stages, and apoptosis is active during the phase of callus remodeling.

Animals↗