Search PubMed⌕ Search

Biomedical subjects

D C Martin

Publications and source records attributed to D C Martin.

At least 19 recordsLinked to original sources
PubMed2001

Outcomes of pain center treatment in Washington State workers' compensation.

BACKGROUND: Injured workers with chronic pain who have failed conventional therapies often receive treatment at pain centers. This study evaluated the effect of pain center treatment on time loss status of Washington State injured workers. The primary hypothesis was that treatment at a pain center would lead to a reduction in the probability of a worker's receiving time loss benefits at a 2-year follow-up. METHODS: A population-based retrospective cohort study was performed on 2,032 Washington State workers' compensation patients who underwent pain center evaluations. Subjects who received pain center treatment were compared to those who were evaluated but not treated with respect to time loss status at 2-year follow-up. RESULTS: Univariate analysis revealed that at 2-year follow-up, 35% of treated subjects were receiving time loss payments vs. 40% of evaluated only subjects (P < 0.05). Subjects who were younger, female, and less chronic were more likely to undergo pain center treatment and were less likely to be on time loss at 2-year follow-up. In multivariate analyses, which statistically controlled baseline differences between the two groups, there was no difference between treated subjects and evaluated only subjects. CONCLUSIONS: There was no evidence that pain center treatment alters 2-year time loss status of already disabled workers.

Adult↗
PubMed2001

Surface modification of neural recording electrodes with conducting polymer/biomolecule blends.

The interface between micromachined neural microelectrodes and neural tissue plays an important role in chronic in vivo recording. Electrochemical polymerization was used to optimize the surface of the metal electrode sites. Electrically conductive polymers (polypyrrole) combined with biomolecules having cell adhesion functionality were deposited with great precision onto microelectrode sites of neural probes. The biomolecules used were a silk-like polymer having fibronectin fragments (SLPF) and nonapeptide CDPGYIGSR. The existence of protein polymers and peptides in the coatings was confirmed by reflective microfocusing Fourier transform infrared spectroscopy (FTIR). The morphology of the coating was rough and fuzzy, providing a high density of bioactive sites for interaction with neural cells. This high interfacial area also helped to lower the impedance of the electrode site and, consequently, to improve the signal transport. Impedance spectroscopy showed a lowered magnitude and phase of impedance around the biologically relevant frequency of 1 kHz. Cyclic voltammetry demonstrated the intrinsic redox reaction of the doped polypyrrole and the increased charge capacity of the coated electrodes. Rat glial cells and human neuroblastoma cells were seeded and cultured on neural probes with coated and uncoated electrodes. Glial cells appeared to attach better to polypyrrole/SLPF-coated electrodes than to uncoated gold electrodes. Neuroblastoma cells grew preferentially on and around the polypyrrole/CDPGYIGSR-coated electrode sites while the polypyrrole/CH(3)COO(-)-coated sites on the same probe did not show a preferential attraction to the cells. These results indicate that we can adjust the chemical composition, morphology, electronic transport, and bioactivity of polymer coatings on electrode surfaces on a multichannel micromachined neural probe by controlling electrochemical deposition conditions.

Animals↗
PubMed2001

Surface characterization of porous, biocompatible protein polymer thin films.

Genetically engineered protein polymer coatings are intended to improve the performance of implantable neural prosthetic devices. To facilitate device integration with tissue, three-dimensionally structured protein polymer films were deposited on the devices using electrostatic atomization and gas-evolution foaming. Periodic features and the length-scale dependence of the surface roughness were identified in topographic data collected using scanning probe microscopy. Using the power spectral density of surface data, the influence of process parameters on the surface roughness of protein polymer thin films was examined. Details of surface topography are known to influence biological behavior, and the method presented was capable of quantifying the evolution of surface features at biologically relevant length scales. This study provides a means for the quantitative exploration of the effects of topography on the performance of these devices and on biocompatibility in general.

Biocompatible Materials↗
PubMed2001

Comparing human skeletal muscle architectural parameters of cadavers with in vivo ultrasonographic measurements.

The purpose of this study was to document and compare the architectural parameters (fibre bundle length, angle of pennation) of human skeletal muscle in cadaveric specimens and live subjects. The medial (MG) and lateral (LG) gastrocnemius, and posterior (PS) and anterior (AS) soleus were examined bilaterally in 5 cadavers (mean age 72.6, range 65-83 y) and 9 live subjects (mean age 76.3, range 70-92 y). Data were obtained from direct measurement of cadaveric specimens and from ultrasonographic scans of the live subjects. In cadaveric muscle, fibre bundles were isolated; their length was measured in millimetres and pennation angles were recorded in degrees. In live muscle, similar measurements were taken from ultrasonographic scans of relaxed and contracted muscle. For the scans of relaxed muscle, subjects were positioned prone with the foot at a 90 degrees angle to the leg, and for scans of contracted muscle, subjects were asked to sustain full plantarflexion during the scanning process. Fibre bundle length and angle of pennation were compared at matched locations in both groups. It was found that the relationship between cadaveric and in vivo values for fibre length and angle of pennation varied between muscle parts. The cadaveric architectural parameters did not tend to lie consistently towards either extreme of relaxation or contraction. Rather, within MG, PS and AS, cadaveric fibre bundle lengths lay between those for relaxed and contracted in vivo muscle. Similarly both the anterior and posterior cadaveric fibre angles of pennation lay between the in vivo values within LG and PS. In summary, architectural characteristics of cadaveric muscle differ from both relaxed and contracted in vivo muscle. Therefore, when developing models of skeletal muscle based on cadaveric studies, the architectural differences between live and cadaveric tissue should be taken into consideration.

Aged↗
PubMed2001

Comparing methods to identify general internal medicine clinic patients with chronic heart failure.

OBJECTIVES: Identification of patients with left ventricular systolic dysfunction is the first step in identifying which patients may benefit from clinical practice guidelines. The purpose of this study was to develop and validate a computerized tool using clinical information that is commonly available to identify patients with left ventricular systolic dysfunction (LVSD). METHODS: We performed a cross-sectional study of patients seen in a Department of Veterans Affairs General Internal Medicine Clinic who had echocardiography or radionuclide ventriculography performed as part of their clinical care. RESULTS: We identified 2246 subjects who had at least one cardiac imaging study. A total of 778 (34.6%) subjects met study criteria for LVSD. Subjects with LVSD were slightly older than subjects without LVSD (70 years vs 68 years, P =.00002) but were similar with regard to sex and race. Subjects with LVSD were more likely to have prescriptions for angiotensin-converting enzyme (ACE) inhibitors, carvedilol, digoxin, loop diuretics, hydralazine, nitrates, and angiotensin II receptor antagonists. Of the variables included in the final predictive model, ACE inhibitors, loop diuretics, and digoxin exerted the greatest predictive power. Discriminant analysis demonstrated that models containing pharmacy information were consistently more accurate (75% accurate [65% sensitivity, 81% specificity]) than those models that contained only International Classification of Diseases, 9th revision (ICD-9), codes, including ICD-9 codes for congestive heart failure (72% accurate [80% sensitivity, 68% specificity]). CONCLUSIONS: We demonstrated that an automated, computer-driven algorithm identifying LVSD permits simple, rapid, and timely identification of patients with congestive heart failure by use of only routinely collected data. Future research is needed to develop accurate electronic identification of heart failure and other common chronic conditions.

Aged↗
PubMed2001

Serum levels of TCDD and dioxin-like chemicals in Rhesus monkeys chronically exposed to dioxin: correlation of increased serum PCB levels with endometriosis.

Humans and animals are exposed daily to a complex mixture of polyhalogenated aromatic hydrocarbons (PHAHs). Previous work has shown that exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is associated with a dose-dependent increase in the incidence and severity of endometriosis in the rhesus monkey. Dioxin-like chemicals can also exert effects in combination with TCDD via the aryl hydrocarbon receptor. This study demonstrates that the serum levels of TCDD and specific dioxin-like PHAH congeners were increased in TCDD-treated animals with endometriosis 13 years after the TCDD exposure. Nine TCDD-exposed and 6 unexposed female rhesus monkeys were evaluated for serum content of relevant compounds and for endometriosis by surgical laparoscopy. Additional studies were done on 4 animals that died 7 to 11 years after exposure to TCDD and 4 lead-treated animals with no history of PHAH treatment. For TCDD-exposed and unexposed animals, TCDD exposure correlated with an increased serum TCDD concentration. Furthermore, TCDD exposure and an elevated serum TCDD concentration were associated with increased serum levels of triglycerides, 1,2,3,6,7,8-hexachlorodibenzofuran, 3,3',4,4'-tetrachlorobiphenyl (TCB) and 3,3'4,4',5-pentachlorobiphenyl (PnCB). Importantly, the animals with elevated serum levels of 3,3',4,4'-TCB, 3,3',4,4',5-PnCB and an increased total serum TEQ had a high prevalence of endometriosis, and the severity of disease correlated with the serum concentration of 3,3,',4,4'-TCB. Increased serum concentrations of coplanar PCBs were also present in lead-treated animals. Implications of these findings for human health and the prevalence of endometriosis in humans will be discussed.

Animals↗
PubMed2001

Increased tumor necrosis factor-alpha production by peripheral blood leukocytes from TCDD-exposed rhesus monkeys.

Previous work has shown that exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is associated with a dose-dependent increase in the incidence and severity of endometriosis in the rhesus monkey. Studies also suggest that immune mechanisms participate in TCDD-mediated toxicity and the pathogenesis of endometriosis. Thirteen years after TCDD treatment was terminated, we characterized the phenotypic distribution of peripheral blood mononuclear cells (PBMC) from TCDD-exposed and -unexposed rhesus monkeys and determined the ability of these cells to produce cytokines and exert cytolytic activity against NK and T-cell-sensitive cell lines. We also determined whether elevated serum levels of TCDD, dioxin-like PHAH congeners, and triglycerides correlated with changes in PBMC phenotype or function. For all animals, TCDD exposure correlated with increased PBMC tumor necrosis factor-alpha (TNF-alpha) secretion in response to stimulation by T-cell mitogen and decreased cytolytic activity against NK-sensitive target cells. Furthermore, increased production of this cytokine by PHA-stimulated leukocytes was associated with elevated serum triglyceride levels. Leukocyte TNF-alpha secretion in response to viral antigen and PBMC production of interferon gamma (IFNgamma), IL-6, and IL-10 following exposure to mitogen or antigen were unaffected by previous TCDD treatment. Although TCDD exposure was not associated with changes in PBMC surface antigen expression, elevated serum concentrations of TCDD, 1,2,3,6,7,8-hexachlorodibenzofuran and 3,3',4,4',5-pentachlorobiphenyl correlated with increased numbers of CD3+/CD25- and CD3-/CD25+ leukocytes and enhanced secretion of TNF-alpha by mitogen-stimulated PBMC. These findings indicate that TCDD-exposed rhesus monkeys with endometriosis exhibit long-term alterations in systemic immunity associated with elevated serum levels of specific PHAH congeners.

Animals↗
PubMed2001

Regional variations in health status.

CONTEXT: Knowledge about variations in the health status of patients seeking primary care in different parts of the United States is limited. OBJECTIVE: To examine regional variations in the physical and mental health of patients receiving primary care in the largest integrated health care system in the United States which is operated by the Department of Veteran Affairs (VA). STUDY DESIGN AND SETTING: We performed a mailed, cross sectional survey of 54,844 patients who were enrolled in seven VA General Internal Medicine clinics. RESULTS: Among the 30,690 patients who returned an initial set of screening questionnaires, the prevalence of common chronic conditions varied by as much as 60% among the seven clinics. Moreover, patients' general health (measured by the SF-36) also varied significantly in a pattern that mirrored the observed differences in the prevalence of chronic conditions. After adjustment for important comorbid illnesses and sociodemographic factors, geographic site accounted for a small percentage of the explained variance in patient assessed health status. CONCLUSIONS: The substantial differences in the health of patients enrolled in different VA primary clinics have important implications for the evaluation of clinical performance and health outcomes. Most of these differences can be attributed to sociodemographic and comorbid factors.

Chronic Disease↗
PubMed2000

Estimates of smoking-attributable deaths at ages 15-54, motherless or fatherless youths, and resulting Social Security costs in the United States in 1994.

BACKGROUND: Deaths of parents often harm their children, taxpayers, and society, for decades. So we estimated the smoking-attributable (SA) counts and percentages (SA%) of U.S. 1994 deaths at child-rearing ages; youths (ages <18) left motherless or fatherless; and resulting Social Security Survivors Insurance taxes. DESIGN: U.S. 1994 age/sex/education-specific total and SA death counts were estimated using death certificate data and standard CDC SAMMEC methods (with added injury mortality), respectively. We separately summed (a) total and (b) SA age/sex/education-specific death counts times their average number of youths per adult (cumulative fertility, adjusted for infant mortality). We then multiplied the SA and total bereft youth counts by their average duration of Survivors Insurance, and calculated the SA cost of youth Survivors Insurance. RESULTS: In 1994, smoking caused an estimated 44,000 male and 19,000 female U.S. deaths at ages 15-54, leaving 31,000 fatherless and 12,000 motherless youths. On December 31, 1994, the SA prevalences [count (SA%)] of fatherless or motherless youths were an estimated 220,000 (17%) and 86,000 (16%), respectively. Resulting Survivors Insurance costs were about $1.4 (sensitivity range: $0.58-3.7) billion in 1994. CONCLUSIONS: Smoking causes many U.S. deaths at ages 15-54, youth bereavements, and Survivors Insurance costs. Reductions in smoking may greatly reduce those deaths, bereavements, and taxpayer and societal costs.

Adolescent↗
PubMed2000

Fire injuries, disasters, and costs from cigarettes and cigarette lights: a global overview.

BACKGROUND: Fires cause 1% of the global burden of disease. Fire (includes explosion) disasters have immense health, social, and environmental costs. We will provide initial estimates of overall U. S. and global fire tolls from smoking. METHODS: We tabulated and summarized smoking-related fire and disaster tolls from published documents. We compared those tolls to U.S. fire, burn, and fire death rates per billion cigarettes extrapolated globally. Smoking-attributable percentages of adult and child access to cigarette lighter and match ignitions (lights), and resultant fires, burns, and deaths ignited by young children, were estimated from likely smoking-attributable lights usage. Cigarette plus cigarette lights fire tolls were multiplied times published and estimated fire costs. RESULTS: Smoking is the leading cause of residential or total fire death in all eight countries with available statistics. Smoking is a leading cause of fires in many more countries. Cigarettes cause numerous fire disasters. Cigarette lights cause an estimated 100,000 U.S. and one million global, child-playing fires per year. Cigarette lights fire injuries likely rival U.S., and possibly global, cigarette fire injury numbers. Smoking causes an estimated 30% of U. S. and 10% of global fire death burdens. Smoking's estimated U.S. and global fire costs were $6.95 (sensitivity range $5.34-22.8) and $27.2 (sensitivity range $8.2-89.2) billion, respectively, in 1998 U. S. dollars. CONCLUSIONS: Smoking likely causes large global fire tolls. U.S. fire tolls have fallen when smoking decreased. Further reducing smoking can substantially reduce fire and disaster tolls.

Accidents↗
PubMed2000

Sonographic studies of human soleus and gastrocnemius muscle architecture: gender variability.

The purpose of this study was to establish if there are gender differences in muscle architecture in relaxed human soleus and gastrocnemius muscles of normal, live subjects. Ultrasonography was used to measure fiber bundle length, muscle thickness, and angles of pennation in a total of ten predetermined sites in the medial and lateral heads of gastrocnemius and the anterior and posterior soleus in 19 males and 16 females. Percentage differences between males and females for each parameter were recorded. Gender differences were statistically analyzed using multivariate analysis of variance. In the gastrocnemius and soleus muscles of males and females the differences between the overall fiber bundle length, angle of pennation and muscle thickness were statistically significant (P < 0.05). Overall, females were found to have longer average muscle fiber bundle length and males thicker muscles and larger angles of pennation. The greatest percentage differences of the architectural parameters between males and females were in the posterior soleus: 13% difference in fiber length and 26% difference in angle of pennation in the midline of posterior soleus and 26% difference in muscle thickness of the lateral part of posterior soleus. No correlation was found between leg length and fiber length, angle of pennation or muscle thickness. Fiber length (decreased), angle of pennation (greater) and muscle thickness (greater) of most parts of the gastrocnemius and soleus muscles were significantly different in males and females. Leg length of males and females did not correlate to these architectural parameters.

Adult↗
PubMed2000

Smoking as a risk factor for accident death: a meta-analysis of cohort studies.

This meta-analysis discusses the consistency, strength, dose-response, independence, and generalizability of published cohort data on accident death relative risks in smokers. To locate data, three authors independently searched MEDLINE, and bibliographies of the pertinent studies found, for data which allowed estimation of an appropriate cigarette smoker accident death relative risk (and 95% confidence interval). Relative risks and dose-response were summarized by fixed effects and Poisson modeling, respectively. Four pertinent cohort studies including eight populations were located. Cigarette smoking predicted summary accident death relative risks of 1.51 (95% confidence interval 1.27-1.78) versus never smokers and 1.35 (1.17-1.57) versus ex-smokers. Summary dose-response trends were significant (P = 0.0000) versus never or least smoking referents. In individual studies, the smoking/accident death association persisted after adjustment or, in effect stratification, for age, race, sex, and occupation; occupation and time period; or numerous cardiac risk factors. This meta-analysis found significant, consistent, dose-response, often strong and independent (of age, race, and sex), prospective associations of smoking with accident death, internationally. Further studies and warnings of the smoking/accident death associations seem merited.

Accidents↗
PubMed2000

Fluconazole for the prevention and treatment of tinea gladiatorum.

BACKGROUND: Tinea gladiatorum is a common problem in competitive wrestling. It impacts on a wrestler's ability to compete. Several methods have been advocated to prevent these infections; however, no well-designed study of pharmacologic prophylaxis has been conducted. METHODS: In a double blind placebo-controlled trial during the 1998 to 1999 regular wrestling season, wrestlers were randomized to receive 100 mg of fluconazole once weekly or placebo once weekly. Those not involved in the study were treated as a second control group. The effects of prophylaxis were also examined by assessing treatment of clinical infections with fluconazole 200 mg weekly for 4 weeks. RESULTS: There was a significantly smaller incidence of infection in those given fluconazole (6%) than in those receiving placebo (22%) and those not involved in the prophylaxis phase (18%) (P<0.05). There was also a significant reduction in the total number of infections in the fluconazole group (P<0.05). Prophylaxis with fluconazole did not impact on the severity of disease, if contracted, when compared with the placebo prophylaxis participants who contracted tinea corporis. Of 21 wrestlers with tinea infections and positive cultures, 14 were able to have their isolates identified as Trichophyton tonsurans. CONCLUSIONS: Fluconazole is effective and safe for primary prevention of tinea gladiatorum. We must now define when and in what population prophylaxis would be warranted.

Adolescent↗
PubMed2000

Injury death excesses in smokers: a 1990-95 United States national cohort study.

OBJECTIVES: Assess injury death relative risks (RR), dose-response, and attributable fractions for current cigarette smokers (smokers) in a recent representative sample of the United States population without and with adjustment for (a) demographic and (b) additional behavioral risk factors. SETTING: United States. METHODS: National Health Interview Survey (NHIS) adult (ages 18+ years) interviewees from 1990 or 1991 were followed through 1995. Referents had never smoked a total of 100 cigarettes. Relative risks were estimated with Stata software's Cox proportional hazard regressions, using NHIS final weights and primary sampling units. The resulting RR and published data were used to estimate population smoking attributable fractions of injury deaths in the United States. RESULTS: The crude, age-race-gender adjusted, and fully (demographic plus educational attainment, marital status, alcohol use level, and seat belt use) adjusted RRs for injury death in smokers were 1.86 (95% confidence interval (CI) 1.30 to 2.66), 1.60 (CI 1.12 to 2.29), and 1.42 (CI 0.99 to 2.05) respectively. Those RRs correspond to United States injury death smoking attributable fractions of 18%, 13%, and 9%, respectively. Those smoker/ injury death RRs each showed a significant dose response relationship (p<0.030). Smokers' unadjusted unintentional injury, motor vehicle crash, and suicide RRs were 1.87 (CI 1.22 to 2.86), 2.14 (CI 1.12 to 4.11), and 2.17 (CI 1.02 to 4.62), respectively. CONCLUSIONS: Smokers in the United States have significant dose-response excesses of injury death, independent of age, race, gender, alcohol use, seat belt use, education, and marital status. This supports earlier studies suggesting that smoking may be a leading contributor to injuries and injury may be a leading burden from smoking, both nationally and globally.

Accidents, Traffic↗
PubMed2000

Chronic recording of regenerating VIIIth nerve axons with a sieve electrode.

A micromachined silicon substrate sieve electrode was implanted within transected toadfish (Opsanus tau) otolith nerves. High fidelity, single unit neural activity was recorded from seven alert and unrestrained fish 30 to 60 days after implantation. Fibrous coatings of genetically engineered bioactive protein polymers and nerve guide tubes increased the number of axons regenerating through the electrode pores when compared with controls. Sieve electrodes have potential as permanent interfaces to the nervous system and to bridge missing connections between severed or damaged nerves and muscles. Recorded impulses might also be amplified and used to control prosthetic devices.

Animals↗
PubMed2000

Wrestling mats: are they a source of ringworm infections?

OBJECTIVE: To determine if the fungal molds (dermatophytes) responsible for causing ringworm could be isolated from a section of wrestling mat during the 1998-1999 season. DESIGN AND SETTING: A 2-part study was conducted. The first phase involved a culture evaluation of material taken from wrestling mats at 8 local high schools. The second phase was a bench laboratory study to determine if the fungus and molds could be grown from a wrestling mat in an optimal setting. SUBJECTS: We obtained material from areas of the practice mats of 8 high school wrestling teams at monthly intervals during the wrestling season. A 0.61-m (2-ft)x 0.31-m (1-ft) area of mat from 1 of the schools was used for the laboratory phase of the study. MEASUREMENTS: We cultured samples taken from each school's wrestling mats for growth of dermatophytes and used a questionnaire to determine the mat-washing habits and policies of each school. Also, wrestlers from the 8 schools were screened weekly by the designated team physician and certified athletic trainer. Any suspicious lesions were cultured for fungi. RESULTS: No dermatophytes were grown from the swab specimens taken at the 8 schools, and no dermatophytes were isolated from a section of mat evaluated in optimal laboratory conditions. CONCLUSIONS: It is unlikely that wrestling mats are a source of ringworm infections in wrestlers.

Journal Article↗