Biomedical subjects

David Stone

Publications and source records attributed to David Stone.

25 records · Page 2Linked to original sources

PubMed2004

Toward the effective surveillance of hypospadias.

Concern about apparent increases in the prevalence of hypospadias--a congenital male reproductive-tract abnormality--in the 1960s to 1980s and the possible connection to increasing exposures to endocrine-disrupting chemicals have underlined the importance of effective surveillance of hypospadias prevalence in the population. We report here the prevalence of hypospadias from 1980 to 1999 in 20 regions of Europe with EUROCAT (European Surveillance of Congenital Anomalies) population-based congenital anomaly registers, 14 of which implemented a guideline to exclude glanular hypospadias. We also report data from the England and Wales National Congenital Anomaly System (NCAS). Our results do not suggest a continuation of rising trends of hypospadias prevalence in Europe. However, a survey of the registers and a special validation study conducted for the years 1994-1996 in nine EUROCAT registers as well as NCAS identified a clear need for a change in the guidelines for registration of hypospadias. We recommend that all hypospadias be included in surveillance, but that information from surgeons be obtained to verify location of the meatus, and whether surgery was performed, in order to interpret trends. Investing resources in repeated special surveys may be more cost-effective than continuous population surveillance. We conclude that it is doubtful whether we have had the systems in place worldwide for the effective surveillance of hypospadias in relation to exposure to potential endocrine-disrupting chemicals.

Confounding Factors, Epidemiologic↗

PubMed2004

Retrospective case series of suspected intentional paraquat poisonings: diagnostic findings and risk factors for death.

We investigated a cluster of canine poisonings around the 4th of July weekend in 2003 in dogs that visited a local park. Medical records review and personal interviews were performed on 17 suspect cases; 14 dogs met the case definition criteria. The 13/14 dogs were allowed off-leash at some point during their visit to the park; 7 owners noted their dog had either eaten something at the park or vomited up meat-like material within 1 h after their walk. Eleven of the 14 dogs died or were euthanized. Urine samples from 4 dogs were positive for trace amounts of paraquat and 1 vomitus sample tested positive. Tachypnea was a significant risk factor for death of the dogs. Oral or gastrointestinal ulcers were significantly correlated with recovery.

Animals↗

PubMed2003

Cyclic mechanical stretching of human tendon fibroblasts increases the production of prostaglandin E2 and levels of cyclooxygenase expression: a novel in vitro model study.

Prostaglandin E(2) (PGE(2)) is a known inflammatory mediator of tendinitis, for which mechanical loading on tendons is believed to be one of the most prominent causation factors. Previous in vitro studies have shown that cyclic mechanical stretching of cells can cause changes in cell morphology and alteration of both DNA and protein syntheses. In our study, a novel system was used whereby tendon fibroblasts are cultured on microgrooved silicone surfaces and are subjected to cyclic uniaxial stretching along their long axes to mimic in vivo conditions. Using this unique model system, the cell shape and alignment can be controlled. Further, this study was designed to test the hypotheses that PGE(2) production increases in a stretching magnitude-dependent manner and that cyclooxygenase (COX) is responsible for the increased PGE(2) production in tendon fibroblasts. Human patellar tendon fibroblasts were cultured on the microgrooved silicone membranes and cyclically stretched at 4%, 8%, or 12% of nominal dish length for 24 hr. PGE(2) production was found to be increased 1.7-fold at 8% cyclic stretching and 2.2-fold at 12% cyclic stretching compared with nonstretched controls. In addition, human tendon fibroblasts had increased expression of both COX-1 and COX-2 for all three applied stretching magnitudes, with the exception of COX-1 at 4% cyclic stretching. Also, cellular PGE(2) production, after 8% cyclic stretching, was significantly decreased with the addition of indomethacin (25 microM), a COX competitive inhibitor, compared with stretched cells without indomethacin treatment. These findings suggest that the increase in PGE(2) production by the human tendon fibroblasts is stretching magnitude-dependent, and that the increase in COX expression contributes to the increased production of PGE(2) after cyclic stretching. As PGE(2) is a known inflammatory mediator of tendinitis, the contribution of COX-1 and COX-2 to PGE(2) production and their roles in tendon inflammation are clearly indicated.

Adult↗

PubMed2002

Pediatric violence-related injuries in Boston: results of a city-wide emergency department surveillance program.

CONTEXT: Violence-related injuries among children are common, but age-based incidence data are not easily available. OBJECTIVES: To describe injuries due to violence in a population-based case series of children and to estimate injury incidence. DESIGN: Prospective surveillance of children residing in Boston, Mass, who received pediatric emergency department treatment for violence-related injury during a 4-year period beginning April 15, 1995. SETTING: Pediatric emergency departments in Boston. PATIENTS: Children aged 3 through 18 years who came to a hospital emergency department between April 1995 and April 1999. Violence-related injuries were defined as those resulting from a situation of conflict involving 2 or more persons with intent to harm, as assessed by health care personnel caring for the patients. Self-inflicted injuries and injuries caused by child abuse (including any injury resulting from a conflict with a parent or guardian) were excluded. Homicides of Boston children aged 3 through 18 years who were killed during the study period were included based on police data. MAIN OUTCOME MEASURE: Population-based violence-related injury rates. RESULTS: There were 2035 injury-related visits caused by violence, which reflects a rate of 52.7 (95% confidence interval, 50.5-54.9) per 10 000 person-years. Most injuries were relatively minor; 6.4% of visits resulted in admission. The youth violence-related injury rate in Boston declined at an average rate of 12% annually during the period studied. CONCLUSION: Pediatric emergency department monitoring of violence-related injury in Boston suggests that childhood injuries due to violence declined during the late 1990s.

Academic Medical Centers↗

PubMed2002

Differential hippocampal expression of glutamic acid decarboxylase 65 and 67 messenger RNA in bipolar disorder and schizophrenia.

BACKGROUND: Expression of messenger RNA (mRNA) for the gamma-aminobutyric acid (GABA)-synthesizing enzyme, glutamic acid decarboxylase (GAD), in the prefrontal cortex and the number of GABAergic neurons in the hippocampus are reduced in schizophrenia and bipolar disorder. We tested the hypothesis that the expression of the 2 isoforms, one 65 kd (GAD(65)) and the other 67 kd (GAD(67)), is differentially affected in the hippocampus in schizophrenia and bipolar disorder. METHODS: Hippocampal sections from 15 subjects in 3 groups (control subjects and subjects with schizophrenia and bipolar disorder) were studied using an in situ hybridization protocol with sulfur 35-labeled complementary riboprobes for GAD(65) and GAD(67) mRNA. Emulsion-dipped slides were analyzed for the density of GAD mRNA-positive neurons in 4 sectors of the hippocampus and for the cellular expression level of both GAD mRNAs. RESULTS: The density of GAD(65) and GAD(67) mRNA-positive neurons was decreased by 45% and 43%, respectively, in subjects with bipolar disorder, but only 14% and 4%, respectively, in subjects with schizophrenia. The decreased density of GAD(65) mRNA-positive neurons in subjects with bipolar disorder was significant in sectors CA2/3 and dentate gyrus, and that of GAD(67) mRNA-positive neurons was significant in CA4, but not other hippocampal sectors. Cellular GAD(65) mRNA expression was significantly decreased in subjects with bipolar disorder, particularly in CA4, but not in schizophrenic subjects. Cellular GAD(67) mRNA expression was normal in both groups. CONCLUSION: We have found a region-specific deficit of GAD(65) and GAD(67) mRNA expression in bipolar disorder.

Adult↗

PubMed2002

A biologically active VEGF construct in vitro: implications for bioengineering-improved prosthetic vascular grafts.

Prosthetic arterial grafts are unable to develop an intact endothelial lining after implantation, predisposing them to fail. Strategies have been sought to enhance endothelialization using growth factors and cytokines. This study assessed the biologic activity of vascular endothelial growth factor (VEGF) covalently linked to bovine serum albumin (BSA). Native and modified VEGF were assayed for endothelial cell migration and proliferation. Migration assays were performed comparing the effects of 2% fetal bovine serum (FBS), 50 ng/mL, 100 ng/mL, and 200 ng/mL of native VEGF and VEGF-BSA. Proliferation assays were performed by using Alamar Blue comparing cellular growth in 1% FBS, 10% FBS, 100 ng/mL unbound VEGF, and 100 ng/mL VEGF-BSA. VEGF is a potent chemotactic agent for endothelial cells in both unbound and bound states. Native VEGF solutions (50 ng/mL, 100 ng/mL, and 200 ng/mL) stimulated 23.9 cells/high power field (HPF), 35.3 cells/HPF, and 49.1 cells/HPF (p < 0.005). VEGF-BSA solutions stimulated 25.9 cells/HPF, 39.1 cells/HPF, and 69.0 cells/HPF (p < 0.001). VEGF-BSA and native VEGF supported similar increased cellular proliferation compared with 1% FBS media (p < 0.002). Modified VEGF retains its chemotactic and proliferative properties in vitro. These findings suggest that bare prosthetic surfaces lined with VEGF bound to a "basecoat" albumin may support endothelial cell proliferation and migration and thereby offer new strategies to improve graft patency.

Blood Vessel Prosthesis↗

PubMed2002

Trends in detoxification enzymes and heavy metal accumulation in ground beetles (Coleoptera: Carabidae) inhabiting a gradient of pollution.

Non-specfic carboxylesterase and glutathione S-transferase activity was measured in the ground beetle, Pterosthicus oblongopunctatus (Coleoptera: Carabidae), from five sites along a gradient of heavy metal pollution. A previous study determined that beetles from the two most polluted sites (site codes OLK2 and OLK3) were more susceptible to additional stressors compared with beetles from the reference site (Stone et al., Environ. Pollut. 113, 239-244 2001), suggesting the possibility of physiological impairment. Metal body burdens in ground beetles from five sites along the gradient ranged from 79 to 201 microg/g Zn, 0.174 to 8.66 microg/g Pb and 1.14 to 10.8 microg/g Cd, whereas Cu seemed to be efficiently regulated regardless of metal levels in the soil. Beetle mid- and hindguts were homogenized and the soluble fraction containing glutathione S-transferase (GST) and carboxylesterase (CaE) was assayed using kinetic analyses. Significantly higher levels of GST were found only in female beetles from the most polluted sites (OLK2 and OLK3; P=0.049, P<0.001, respectively) compared with the reference site (OLK7). In addition, OLK3 females had significantly higher levels of CaE compared with the reference beetles (P=0.01). Male beetles did not differ in enzyme activity along the metal gradient. Overall, obvious trends in detoxification enzymes were not detected in ground beetles in association with metal body burdens.

Animals↗