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Biomedical subjects

J Stoltz

Publications and source records attributed to J Stoltz.

17 recordsLinked to original sources
PubMed2005

Prevalence and correlates of hepatitis C infection among users of North America's first medically supervised safer injection facility.

BACKGROUND: North America's first medically supervised safer injection facility (SIF) for illicit drug users was opened in Vancouver, Canada on 22 September 2003. We examined the prevalence and correlates of hepatitis C (HCV) infection among a representative cohort of SIF users. METHODS: Users of the Vancouver SIF were selected at random and asked to enrol in the Scientific Evaluation of Supervised Injecting (SEOSI) cohort. At baseline, venous blood samples were collected and an interviewer-administered questionnaire was performed. Participants who were HCV-positive were compared with HCV-negative subjects using bivariate and logistic regression analyses. RESULTS: Between 1 December 2003 and 30 July 2004, 691 participants were enrolled into the SEOSI cohort, among whom 605 (87.6%) were HCV-positive at baseline. Factors independently associated with HCV infection in logistic regression analyses included: involvement with the sex trade [adjusted odds ratio (AOR) 3.7, 95% confidence interval (CI) 2.1-6.1], history of borrowing syringes (AOR 1.8, 95%CI 1.1-2.9), and history of incarceration (AOR 2.6, 95%CI 1.5-4.4). Daily heroin use was protective against HCV infection (AOR 0.6, 95%CI 0.3-0.9). CONCLUSION: The SIF has attracted injection drug users with a high burden of HCV infection and a substantial proportion of uninfected individuals. Although cross-sectional, this study provides some insight into historical risks for HCV infection among this population, and prospective follow-up of this cohort will be useful to determine if use of the SIF is associated with reduced risk behaviour and HCV incidence.

Canada↗
PubMed2005

Locally differentiated cryptic pigmentation in the freshwater isopod Asellus aquaticus.

A repeated pattern of background colour matching in animals is an indication that pigmentation may be cryptic. Here, we examine the relationship between pigmentation of the freshwater isopod Asellus aquaticus and background darkness in 29 lakes, wetlands and ponds in Southern Sweden. The results show that Asellus pigmentation was correlated with substrate darkness across all localities. In seven localities, in which two contrasting substrate types were noted, Asellus populations were differentiated with respect to pigmentation. These findings thus provide phenomenological support for cryptic pigmentation in Asellus. Pigmentation generally increased with body size, but the relationship between pigmentation and size differed among localities, possibly as a result of differences in correlational selection on pigmentation and size. Selection thus appears to have resulted in local differentiation over a small spatial scale, even within lakes and wetlands. This differentiation is a likely cause behind elevated phenotype variation noted in localities with two substrate types, suggesting that habitat heterogeneity promotes genetic diversity.

Adaptation, Physiological↗
PubMed2000

Ex vivo expanded peripheral blood progenitor cells provide rapid neutrophil recovery after high-dose chemotherapy in patients with breast cancer.

Ex vivo expanded peripheral blood progenitor cells (PBPCs) have been proposed as a source of hematopoietic support to decrease or eliminate the period of neutropenia after high-dose chemotherapy. CD34 cells were selected from rhG-CSF mobilized PBPCs from patients with breast cancer and were cultured for 10 days in defined media containing 100 ng/mL each of rhSCF, rhG-CSF, and PEG-rhMGDF in 1 L Teflon bags at 20 000 cells/mL. After culture the cells were washed and reinfused on day 0 of transplantation. On day +1, cohort 1 patients (n = 10) also received an unexpanded CD34-selected PBPC product. These patients engrafted neutrophils (absolute neutrophil count, >500/microL) in a median of 6 (range, 5-14) days. Cohort 2 patients (n = 11), who received expanded PBPCs only, engrafted neutrophils in a median of 8 (range, 4-16) days. In comparison, the median time to neutrophil engraftment in a historical control group of patients (n = 100) was 9 days (range, 7-30 days). All surviving patients are now past the 15-month posttransplantation stage with no evidence of late graft failure. The total number of nucleated cells harvested after expansion culture was shown to be the best predictor of time to neutrophil engraftment, with all patients receiving more than 4 x 10(7) cells/kg, engrafting neutrophils by day 8. No significant effect on platelet recovery was observed in any patient. These data demonstrate that PBPCs expanded under the conditions defined can shorten the time to engraftment of neutrophils compared with historical controls and that the rate of engraftment is related to the dose of expanded cells transplanted.

Antigens, CD↗
PubMed2000

Bovine beta-lactoglobulin receptors on transformed mammalian cells (hybridomas MARK-3): characterization by flow cytometry.

Flow cytometry was used to demonstrate the presence of beta-lactoglobulin (betaLG) receptors on living murine hybridoma MARK-3 cells using a fluorescein isothiocyanate-betaLG conjugate (FITC-betaLG: molar ratio of 5:1). A site occupation curve was produced using a shift in the mean channel fluorescence at various concentrations of FITC-betaLG. The binding of labelled ligand was concentration dependent and was inhibited by unlabelled betaLG. The on-rate constant was 3.2x10(2) M(-1) min(-1) and the off-rate constant was 0.002 min(-1). Scatchard plot analysis gave a dissociation constant (K(d)) of 44+/-21x10(-7) and 39+/-24x10(-5) M (n=3). Flow cytometry indicated that at least 15% of the FITC-betaLG were internalized for 5 min and that internalization was temperature- and time-dependent. The internalization was confirmed by 3-D fluorescence microscopy (CELLScan system).

Animals↗
PubMed2000

[Determination of polymorphonuclear neutrophil adhesion receptors. Effect of pre-analytic factors].

UNLABELLED: Polymorphonuclear neutrophil (PMN) adherence receptors expression varies with leukocyte activation state. Their quantification need accurate and inter-laboratories reproducible methods, without artefactual activation. OBJECTIVE: The aim of this study was to study the influence of cell preparation on PMN adherence receptors expression. MATERIALS AND METHODS: It was proposed to quantify, using immunolabeling standard (QIFIKIT(R), Dako), surface expression of the main adherence receptors (L-selectin and B(2) integrins), from different preparations of PMN: total blood collected with EDTA, isolated PMN by density gradient Polymorphprep(TM) 1,113 (Nycomed Pharma) and formaldehyde fixed PMN. RESULTS: A decrease of all receptors was noted after isolation and fixation of PMN, in comparison with whole blood PMN analysis. These results differed from data previously reported since, in these studies, activated phenotypes (increased of B(2) integrins) were observed after isolation and fixation methods. CONCLUSION: The present study provides strong evidence that pre-analytical conditions are sources of biological variations and thus extreme care must be taken in the interpretation of results. It underlines the interest of consensual practices for these pre-analytic and analytic parameters in order to compare results in multicenter and longitudinal studies.

CD18 Antigens↗
PubMed1999

Adhesion Probability of Colloidal Particles with Repulsive Soft Interaction.

Computer simulations of the irreversible adhesion of charged colloidal particles at a solid/liquid interface are performed to determine whether the distribution of particles in the vicinity of a preadsorbed (also charged) one follows the Boltzmann law applied to an a priori uniform adhesion probability, as first assumed by Adamczyk et al. (J. Colloid Interface Sci. 140, 123 (1990)). If true, this would indicate that the whole information on the deposition process is contained in the potential energy distribution on the adsorbing surface. In general, diffusion in a field of force and the irreversibility of the process induce significant deviations from the Boltzmann-weighted uniform adhesion density. Nevertheless, it is shown that for particles characterized by a small gravitational energy this procedure leads to a reasonable first approximation of the distribution of the particles over the adsorbing surface. This observation thus demonstrates the validity of Adamczyk's assumption and extends its range of applicability to the case of a weak gravitational field. Copyright 1999 Academic Press.

Journal Article↗
PubMed1998

Relationship between race start characteristics and risk of catastrophic injury in thoroughbreds: 78 cases (1992).

OBJECTIVE: To investigate relationships of several racehorse characteristics and race conditions with risk of a catastrophic musculoskeletal injury (CMI) resulting in euthanasia in Thoroughbreds during racing in California in 1992. DESIGN: Retrospective longitudinal study. ANIMALS: Thoroughbreds that incurred CMI during racing and all California race entrants in 1992. PROCEDURE: Necropsy records were reviewed, and race start information was obtained. Incidence risk of CMI/1,000 race entrants was estimated. Relationships between CMI during racing and race-meet, entrant age and sex, race type and length, and racing surface type and condition were evaluated by use of logistic regression. RESULTS: Incidence risk of CMI was 1.7/1,000 entrants. A higher risk of CMI was found at 2 fair race-meets, with incidence risks of 4.9 and 5.5/1,000 entrants. Risk of injury in male horses was 1.7 times greater than that in female horses, and influence of age on risk depended on race type. Risk of injury for horses 2 to 5 years old was two times greater for claiming horses than for maiden horses. Race length or racing surface type (dirt vs turf) or condition (fast, muddy, yielding) were not significantly associated with risk of CMI. CLINICAL IMPLICATIONS: Incidence of CMI was similar among 12 of 14 major and fair race-meets and among various race lengths and racing surface types and conditions, whereas incidence of CMI was influenced by entrant age and sex as well as race type. Investigators should consider controlling for age and sex, race-meet, and race type whenever possible in studies of risk of CMI.

Age Factors↗
PubMed1998

Hoof size, shape, and balance as possible risk factors for catastrophic musculoskeletal injury of Thoroughbred racehorses.

OBJECTIVE: To evaluate hoof size, shape, and balance as risk factors for catastrophic musculoskeletal injuries (CMI), including suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) in Thoroughbred racehorses. ANIMALS: 95 Thoroughbred racehorses that died between 1994 and 1996. PROCEDURE: 38 quantitative measures of hoof size, shape, and balance were obtained from orthogonal digital images of the hoof and were compared between case horses with forelimb CMI (70), SAF (43), and CDY (10) injuries and control horses whose death was unrelated to the musculoskeletal system (non-CMI, 25). Comparison of group means between cases and controls was done using ANOVA, and multivariable logistic regression was used to estimate odds ratios. RESULTS: Odds of CMI were 0.62 times lower for a 5mm increase in ground surface width difference and 0.49 times lower for a 100-mm2 increase in sole area difference. Odds of SAF were 6.75 times greater with a 10 degrees increase in toe-heel angle difference and 0.58 times lower with a 100-mm2 increase in sole area difference. Odds of CDY were 0.26 times lower with a 3 degrees increase in toe angle, 0.15 times lower with a 5-mm increase in lateral ground surface width, and 0.35 times lower with a 100-mm2 increase in sole area difference. CLINICAL RELEVANCE: Decreasing the difference between toe and heel angles should decrease risk of SAF for Thoroughbred racehorses and should be considered in addition to increasing toe angle alone to help prevent catastrophic injury. Trimming the hoof to perfect mediolateral symmetry may not be a sound approach to avoiding injury.

Animals↗
PubMed1996

Fatal musculoskeletal injuries incurred during racing and training in thoroughbreds.

OBJECTIVE: To characterize and contrast data from Thoroughbreds that incurred a fatal musculoskeletal injury (FMI; injury resulting in death or euthanasia) during racing or training and data from all California race entrants during a 9-month period in 1991. DESIGN: Case-control study. ANIMALS: Thoroughbreds that incurred a FMI during racing or training at a California race-meet and all California race entrants from January through June and October through December 1991. PROCEDURE: Age and sex were compared with chi 2 and Fisher's exact tests among horses fatally injured while racing and training. A log-linear model was fit to assess the relationship between race-meet and age and sex of California race entrants. Incidence risk of racing FMI was estimated per 1,000 race entrants, and the relationship between the occurrence of FMI during racing with race-meet, age, and sex was evaluated by logistic regression. RESULTS: Injury type and sex-specific age distributions differed among the horses fatally injured during racing and training. Age and sex distributions of the race entrants were not independent and varied among race-meets. Overall incidence risk of racing FMI was estimated at 1.7/1,000 race entrants. Risk of racing FMI in male horses was about twofold that in female horses, and in 4-year-olds was twofold that in 3-year-olds. CLINICAL IMPLICATIONS: Age and sex-related differences in risk of incurring a FMI during racing should be considered when comparing fatal injury rates among race-meets.

Age Distribution↗
PubMed1996

Golf for the senior player.

In no other sport does the senior player enjoy as much opportunity to participate and compete at various skill levels as in golf. No other sport encourages as much mixed competition. Because of their spending power, equipment and travel packages are often geared to the senior player. Advancing medical technology and specialized instruction effectively combat the physical effects of aging. These and other factors will ensure the continued popularity of the game of golf.

Exercise↗
PubMed1994

Causes of death in racehorses over a 2 year period.

Necropsies were performed on 496 horses that had a fatal injury or illness at a California racetrack during the period February 20th 1990 to March 1st 1992. The primary cause of death was categorised by breed, activity at time of injury or illness and organ system affected. Most of the submissions were Thoroughbred horses (432) and Quarter Horses (46). Most of the injuries occurred while racing (42%) and in training sessions (39%); with fewer non-exercise (12%) and accident (7%) related injuries or illnesses. Musculoskeletal injuries accounted for 83% of the Thoroughbred and 80% of the Quarter Horse submissions. The Thoroughbred horses incurred 306 fractures with 263 in the limbs and 90% of those in the forelimbs. The proximal sesamoid bone(s), third metacarpal bone and humerus were the most common bones fractured in Thoroughbred horses and Quarter Horses. Other major causes of death included respiratory, digestive and multi-organ system disorders.

Age Factors↗
PubMed1992

An association between complete and incomplete stress fractures of the humerus in racehorses.

Twenty-one horses had a complete unilateral humeral fracture during race training or racing at a California racetrack during the period 24 February 1990 to 10 July 1991. Fractures occurred approximately equally in left and right limbs, and in males and females. Most fractures occurred during training, and in 2- and 3-year-old horses. Only 5 of 16 Thoroughbred horses with known racing records had previously raced more than once, and their mean time between races was less than the time between their last race and fracture (P = 0.07). Ten of 13 humeri studied further had gross evidence of periosteal callus bridging one portion of the fracture line, indicative of a pre-existing stress fracture.

Animals↗
PubMed1992

[Drug modification of post-traumatic edema of the extremities by the proteinase inhibitor aprotinin. An animal experiment study].

Posttraumatic edema remains a serious problem in traumatology. Unrecognized or improperly treated, edema poses a threat to the survival of any extremity, particularly the hand, where a number of intricate functional structures are at stake. This study, as well as other recent clinical and experimental work, show that aprotinin, a proteinase inhibitor, is valuable in the treatment of posttraumatic edema, provided it is given as early as possible and in an adequate dosage.

Animals↗
PubMed1988

[Effect of adjuvant infusion therapy of low molecular weight dextrans (Infukoll M 40) and deproteinized hemoderivate (Actovegin) in Fontaine stage IV chronic arterial occlusive diseases].

A selected group of 18 patients (among them 16 diabetics) with chronic disorders of arterial blood flow at Stage IV according to Fontaine received treatment by a standardised therapeutic scheme. None of the cases was suitable for reconstruction by vascular surgery. Infusion treatment, using Infukoll M 40 and Actovegin, was to be checked for its capability of providing sufficient improvement in blood flow and thus eliminating the need for imminent high-level amputation. Evaluation was undertaken on the basis of clinical and laboratory-chemical parameters. The rate of above-knee amputation was reduced by 14 per cent. Hence, the above therapeutic concept has proved to be suitable for treatment of Stage IV chronic arterial occlusion.

Adult↗