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G S Smith

Publications and source records attributed to G S Smith.

At least 19 recordsLinked to original sources
PubMed1995

Terephthalic acid: a dosimeter for the detection of hydroxyl radicals in vitro.

Hydroxylation reactions of aromatic compounds have been used to detect hydroxyl radicals produced by gamma irradiation and ultrasound. The present study investigated the suitability of terephthalic acid (THA) as a hydroxyl radical dosimeter for general use in biologically relevant reactions. Hydroxyl radicals were generated by: (1) irradiating THA with a 254 nm ultraviolet light; (2) irradiating with gamma rays from a cesium source; and (3) generating hydroxyl radicals with 1 mM H2O2 and 10 microM Cu+2. In each of the three experiments, a fluorescent product was generated which exhibited identical fluorescent excitation and emission spectra. THA is non-fluorescent, eliminating the problem of a high initial background. Because THA has four identical ring hydrogens, only one mono-hydroxylated isomer was formed. The hydrogen peroxide reaction was dependent on the presence of a metal and cupric ions were effective in enhancing the reaction. With a Cu+2 concentration of 10 microM, the reaction was linear between 0-30 mM H2O2. Catalase abolished the reaction at a concentration of 100 micrograms/ml and the effects could still be observed at 10 ng/ml, consistent with the very high rate at which catalase destroys hydrogen peroxide. Tertbutyl- hydroperoxide did not generate any fluorescence in this system which makes THA a very specific detector of hydroxyl radicals.

Free Radicals↗
PubMed1995

Childhood burns in Ghana: epidemiological characteristics and home-based treatment.

The objectives of this research were to study the epidemiological characteristics and home-based treatment of childhood burns in the Ashanti Region of Ghana. Children aged 0-5 years with a burn history were identified through a community-based, multisite survey. A standard questionnaire was administered to mothers of 630 of these children to elicit information on their sociodemographic characteristics and the circumstances of the burn event. Ninety-two per cent of the burns occurred in the home, particularly in the kitchen (51 per cent) and the house yard (36 per cent), with most of them happening in the late morning and around the evening meal. The main causes of the burns were scalds (45 per cent), contact with a hot object (34 per cent) and flame (20 per cent). 'Cool' water was applied to the burned area in 30 per cent of cases. Otherwise, treatment with a traditional preparation was the most popular first-aid choice. Since a considerable proportion of burns happened between meals when children 'play with fire' in the house yard, the provision of alternative play activities and community play areas may reduce the incidence of burns to these children. Secondly, we recommend that education on first-aid management of burns be intensified, with special emphasis on alternatives to the use of traditional preparations.

Age Distribution↗
PubMed1995

Epidemiology and practice of emergency medicine in a developing country.

STUDY OBJECTIVE: To analyze the emergency medicine system in a developing country and identify areas of need and potential collaboration. DESIGN: Convenience sample surveys of all emergency visits over a 2-week period, hospital admission and health department statistics, and interviews with government officials, health providers, and EMS managers. SETTING: Port of Spain General Hospital, Trinidad and Tobago. RESULTS: The ED has more than 100,000 visits per year. No records are kept. No physician in this study had emergency medicine training; only one had completed any residency. The survey included 3,710 patients: 40.5% were admitted, and .3% died. Injuries accounted for 41.6% of all visits, asthma 7.8%. The mean time elapsed before a patient was seen was .5 hour; mean time to discharge, 1.9 hours. In only 9% of patients were laboratory tests performed. Prehospital providers had limited equipment and training. CONCLUSION: The ED and prehospital systems provide high-volume and often high-acuteness care. Barriers to improved care include limited specialized training and lack of medical records.

Adolescent↗
PubMed1995

International comparisons of injury mortality in the elderly: issues and differences between New Zealand and the United States.

BACKGROUND: International comparisons of mortality rates for injury, as for other conditions, can suggest priorities for further research and intervention. However, variability in the assignment of underlying cause, especially among the elderly, may lead to difficulty in interpreting cross-national differences in death rates. Despite similarities between the two countries, the injury death rate for ages < or = 65 in New Zealand is substantially higher than the United States rate. The objective of this study was to investigate possible reasons for this difference. METHODS: We used data not previously reported for New Zealand to calculate the cause-specific injury death rates for ages > or = 65, compared them with US rates, and examined other injury rates that could help explain the observed difference. RESULTS: The New Zealand death rate from falls for ages > or = 65 was nearly three times the US rate (92 versus 32 per 100,000), causing the death rate for all injuries in this age group to be 34% higher in New Zealand (153 versus 114 per 100,000). However, hospitalization rates for both falls and hip fractures are similar for the two countries. CONCLUSIONS: The substantially higher fall injury death rates for older New Zealanders are not fully explained by differences in the incidence of falls resulting in injury nor the case fatality rate for fall-related injury. US injury death rates based on underlying cause of death might be similar to New Zealand rates, and thus substantially higher, if subjected to comparable procedures for the completion and coding of death certificates. As in studies of other conditions, international comparisons of injury death rates based on underlying cause, especially in studies of the elderly, must consider variation between countries in death certification and coding practices.

Accidental Falls↗
PubMed1995

Risk factors for childhood burns: a case-control study of Ghanaian children.

STUDY OBJECTIVE: To study risk factors for childhood burns in order to identify possible preventive strategies. DESIGN: Case-control design with pair matching of controls to cases in relation to age, sex, and area of residence. The cases and controls were identified by a community based, multisite survey. The effects of host and socioenvironmental variables reported by mothers were investigated in a multivariate analysis using conditional logistic regression. SETTING: A developing country setting the Ashanti Region in Ghana. PARTICIPANTS: These comprised 610 cases aged 0-5 years who had been burned (as evidenced by a visible scar) and 610 controls with no burn history. MAIN RESULTS: The presence of a pre-existing impairment in a child was the strongest risk factor in this population (OR = 6.71; 95% CI 2.78, 16.16). Other significant risk factor included: sibling death from a burn (OR = 4.41; 95% CI 1.16, 16.68); history of burn in a sibling (OR = 1.79; 95% CI 1.24, 2.58); and storage of a flammable substance in the home (OR = 1.51; 95% CI 1.03; 2.21). Maternal education had a protective effect against childhood burns, although this effect was not strong (OR = 0.76; 95% CI 0.55, 1.05). CONCLUSIONS: Community programmes to ensure adequate child supervision and general child wellbeing, particularly for those with impairments, as well as parental education about burns are recommended, to reduce childhood burns in this region of Ghana. The public should bed advised against storing flammable substances in the home.

Burns↗
PubMed1995

Improving the E coding of hospitalizations for injury: do hospital records contain adequate documentation?

OBJECTIVES: Incomplete external cause of injury (E) coding limits the usefulness of hospital discharge data sets for injury surveillance and research. Hospital medical records were examined to determine whether they contained adequate cause of injury documentation to allow for more complete E coding of injury discharges. METHODS: Medical records for a sample of discharges involving a principal diagnosis of injury from the Uniform Hospital Discharge Data Set for Rhode Island were selected. We assigned E codes to these discharges and compared our E codes with those of the discharge data set. RESULTS: Documentation of cause of injury in the medical records was sufficient to allow assignment of a specific E code to 70% of the injuries for which no E codes or vague E codes were submitted on the Uniform Hospital Discharge Data Set. It was estimated that specific cause of injury documentation is available in the medical records of 80% of all injury discharges in Rhode Island; for approximately 90%, an E code describing at least the broad cause of injury could be assigned. CONCLUSIONS: Rates of E coding can be substantially increased by making better use of existing documentation in medical records.

Abstracting and Indexing↗
PubMed1995

Relative rates of fracture of the hip in the United States. Geographic, sex, and age variations.

We studied the Medicare data from 1984 through 1987 for 687,850 fractures of the hip that had occurred in the United States. Our purpose was to determine the geographic, sex-specific, and age-interval variations in the relative risk of fracture of the hip in elderly white individuals. The rates of cervical, trochanteric, and subtrochanteric fracture, and the over-all rate of fracture at any of the three levels, increased with age, were greater for women than for men, and were higher in the Southern part of the country. However, there were regional, sex, and age variations. The ratio of cervical to trochanteric fractures was significantly higher in the East South Central region and lower in the Middle Atlantic and New England regions (p < 0.05). These were the same areas with the highest and lowest over-all rates, respectively, of fracture of the hip. The ratio of cervical to trochanteric fractures decreased from 1.52 in women who were sixty-five to sixty-nine years old to 0.81 in women who were at least eighty-five years old, but it stayed at approximately 1.00 for the corresponding age-groups of men. The ratio of fracture of the hip in women to fracture of the hip in men varied depending on the level of the fracture.

Age Factors↗
PubMed1995

Protective effect of a 21-aminosteroid against hemorrhage-induced ischemia-reperfusion injury in the rat stomach: role of lipid peroxidation.

We investigated the role that lipid peroxidation plays in a hemorrhage-induced ischemia-reperfusion model of gastric injury. Rats were pretreated with an inhibitor of this process, a 21-aminosteroid (U-74389G, 10 mg/kg), or an appropriate control solution intravenously 15 min prior to 20 min of ischemia, followed by 20 min of reperfusion. Results indicated that U-74389G pretreatment significantly attenuated gastric damage compared with corresponding control animals (19.8 vs. 176.8 mm2, p < .001). Enaldehyde levels (picomoles/mg protein), a biochemical index of lipid peroxidation, paralleled these injury findings (12 vs 960, p < .001). Histologically, U-74389G pretreatment almost completely prevented gastric injury compared to control stomachs. Additional studies revealed that lipid peroxidation preceded the formation of gastric damage, and injury occurred predominantly during reperfusion, because animals subjected to ischemia alone without reperfusion failed to develop appreciable injury or enhanced enaldehyde formation. Further, if U-74389G was given intravenously after ischemia, but prior to reperfusion, gastric injury and enaldehyde formation were similarly attenuated. Our findings are consistent with the hypothesis that lipid peroxidation likely plays an important role in hemorrhage-induced ischemia-reperfusion injury to the stomach.

Animals↗
PubMed1995

Serotonergic modulation of striatal dopamine measured with positron emission tomography (PET) and in vivo microdialysis.

Positron emission tomography and in vivo microdialysis were used to study serotonin's role in modulating striatal dopamine. Serial PET studies were performed in adult female baboons at baseline and following drug treatment, using the dopamine (D2) selective radiotracer, 11C-raclopride. The serotonergic system was manipulated by administration of the selective 5-HT reuptake inhibitor, citalopram, or by serotonergic (5-HT2) receptor blockade (using altanserin, a 5-HT2 antagonist). 11C-Raclopride time-activity data from striatum and cerebellum were combined with plasma arterial input functions and analyzed by calculating a distribution volume as described previously (Logan et al., 1990). Additionally, in vivo microdialysis studies were performed in awake freely moving rats using similar pharmacologic challenges plus SR 46349B, a new highly selective 5-HT2 receptor antagonist. Altanserin and SR 46349B increased extracellular striatal dopamine concentrations (35% and 910%, respectively) while altanserin decreased striatal 11C-raclopride binding (37%). Citalopram, however, decreased extracellular striatal dopamine concentrations (50%) and increased 11C-raclopride binding (33%). These data demonstrate that 5-HT-selective drugs produce changes in striatal dopamine that can be measured noninvasively with PET. Furthermore, the PET data obtained from anesthetized baboons is consistent with in vivo microdialysis data obtained from awake and freely moving rats. Finally, these studies have implications for understanding the therapeutic efficacy of atypical neuroleptics and their utility for treating schizophrenia and affective disorders.

Animals↗
PubMed1994

Distribution of messenger RNAs encoding enkephalin, substance P, somatostatin, galanin, vasoactive intestinal polypeptide, neuropeptide Y, and calcitonin gene-related peptide in the midbrain periaqueductal grey in the rat.

The midbrain periaqueductal grey matter (PAG) has numerous functional roles that include mediating nociceptive inhibition and integrating behavioural and physiological responses to potentially threatening or stressful stimuli. Underlying these behaviours is the diverse interconnectivity of this region, and it is possible that neurochemical subdivisions within the PAG reflect the functional properties of the different PAG regions. In this study, using in situ hybridization, we have investigated the distribution in the rat PAG of the messenger ribonucleic acids (mRNAs) encoding seven neuropeptides: enkephalin (ENK), substance P (SP), somatostatin (SST), galanin (GAL), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP). Each peptide mRNA had a distinct topographical distribution in the PAG. Preproenkephalin A (ENK) mRNA-expressing cells were found at all levels of the PAG in three distinct longitudinal columns. Preprotachykinin A (SP)-expressing cells were found at all levels of the PAG, principally in the Edinger-Westphal nucleus and the lateral and dorsal PAG. There was a column of neurons producing mRNA-encoding somatostatin that extended along the rostrocaudal extent of the ventrolateral PAG; there were also labelled cells in the dorsal and dorsolateral subdivisions at some levels of the PAG. Galanin mRNA-producing neurones were limited to the dorsal raphe nucleus and to a second population in the ventral border of the aqueduct. VIP mRNA-producing neurones were found in very localized regions of the PAG, including the cell-sparse region immediately ventral to the aqueduct and the ventral part of the dorsal raphe nucleus. NPY mRNA-producing neurones were localized mainly in some cells of the Edinger-Westphal nucleus and dorsal raphe nucleus. CGRP mRNA-expressing neurons were limited to the oculomotor and trochlear nucleus. The results showed a topographical distribution of neuropeptides over the rostrocaudal extent of the PAG that is compatible with the emerging theory that the anatomical and functional specificity of the PAG is expressed in the form of longitudinally arranged neuronal columns that extend for varying distances along the rostrocaudal axis of the midbrain PAG.

Animals↗
PubMed1994

Effects of graded levels of bentonite on serum clinical profiles, metabolic hormones, and serum swainsonine concentrations in lambs fed locoweed (Oxytropis sericea).

To determine which clay minerals have the potential to bind swainsonine, an in vitro screening procedure was conducted. Twenty compounds were screened in one replicated in vitro trial. A commercially available bentonite bound approximately 10% swainsonine and was chosen for use in a subsequent lamb feeding trial. Twenty fine-wool lambs (30.5 +/- .7 kg) were assigned to one of five treatments (four lambs/treatment). Treatments included 1) positive control, 100% sorghum sudangrass hay, 2) 85% sorghum sudangrass:15% locoweed (Oxytropis sericea, 430 ppm [DM basis] of swainsonine) +0 g of bentonite, 3) Treatment 2 + 14 g of bentonite, 4) Treatment 2 + 28 g of bentonite, and 5) Treatment 2 + 42 g of bentonite. Lambs were fed the experimental diets for 35 d and were then fed the positive control diet for an additional 21 d. Lambs were weighted and blood was collected via jugular venipuncture weekly from d 0 through 56. On d 35, additional blood samples were collected 1, 2, 4, and 8 h after feeding. Weekly blood samples were analyzed for serum clinical chemistry profiles, and additional blood samples collected on d 35 were analyzed for serum metabolic hormones and serum swainsonine concentrations. Within 1 wk, serum alkaline phosphatase and glutamic oxaloacetic transaminase activities increased markedly (P < .05) in lambs fed locoweed. Serum insulin, growth hormone, and prolactin concentrations were not affected by feeding locoweed, but serum triiodothyronine and thyroxine concentrations were decreased by approximately 50% (P < .05) in lambs fed locoweed.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1992

Two populations of cells that express preprocholecystokinin mRNA in ventral periaqueductal grey.

Cells expressing preprocholecystokinin (CCK) mRNA in the rat midbrain periaqueductal grey area and Edinger-Westphal nucleus were analysed using in situ hybridization combined with liquid emulsion techniques. Semi-quantitative image analysis revealed that there were two populations of cells which expressed CCK mRNA. The first group of cells were large and heavily labelled and were confined to the Edinger-Westphal nucleus. The second group of cells were small and lightly labelled and were found scattered throughout ventral parts of the anterior periaqueductal grey.

Animals↗
PubMed1992

Psychoactive substance dependence among trauma center patients.

INTRODUCTION: The practice of assessing only trauma patients with elevated blood alcohol concentrations (BACs) or positive drug screens for psychoactive substance use disorders (PSUDs) was evaluated. METHODS: Twenty-four BAC-negative (BAC-) (BAC, 0) and 21 BAC-positive (BAC+) (BAC, greater than or equal to 22 mmol/L or 100 mg/dL; mean, 41 mmol/L; range, 24.3 to 79 mmol/L) adult trauma patients were evaluated for alcoholism and other PSUDs using the Structured Clinical Interview (SCI) from the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM-III-R). Approximately half were vehicular crash victims and 78% were men. RESULTS: A total of 64 PSUDs were diagnosed in 31 (68.9%) of the 45 patients; all but one was for dependence (vs abuse). Of the BAC+ patients, 14 (66.7%) met DSM-III-R criteria for alcohol dependence, 11 (78.6%) of whom also had other PSUDs not related to alcohol. Two other BAC+ patients had nonalcohol PSUDs. Of the BAC- patients, 11 (45.8%) had alcohol dependence, six (54.5%) of whom also had nonalcohol PSUDs. Another four BAC- patients had nonalcohol PSUDs. Overall, 76.2% of the BAC+ patients and 62.5% of the BAC- patients had a diagnosis of psychoactive substance dependence. CONCLUSION: All patients admitted to trauma centers should be assessed for alcoholism and other PSUDs.

Alcoholism↗
PubMed1992

Topography of cross-sectional and longitudinal glucose metabolic deficits in Alzheimer's disease. Pathophysiologic implications.

Positron emission tomographic studies of cerebral glucose metabolism have shown high diagnostic specificity in distinguishing among the degenerative dementias and differentiating between Alzheimer's disease (AD) and normal aging. The current investigation was undertaken to characterize the regional glucose metabolic deficits in AD, using cross-sectional and longitudinal study designs. All subjects met the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for AD (n = 45) or were normal (n = 20), and the AD subjects were subdivided into incipient and mild AD and moderate plus moderately severe subgroups based on the Global Deterioration Scale. The subjects underwent a non-contrast computed tomographic scan and a positron emission tomographic (PETT VI) scan. The AD subjects (n = 14) and normal control subjects (n = 15) received evaluations 2 to 3 years after baseline study. The brain regions that show glucose metabolic deficits cross-sectionally (temporal and parietal association areas, with lesser degrees of deficit in subcortical gray matter structures), over the stages of AD, also show further deficits longitudinally within the same AD subjects. The reduction in glucose metabolism is greater than would be expected from the degree of brain atrophy. The glucose metabolic deficits are discussed in the context of neuropathologic findings and neurotransmitter deficits in AD.

Aged↗
PubMed1992

Protective effect of dimethylthiourea against mucosal injury in rat stomach. Implications for hydroxyl radical mechanism.

The present study was undertaken to determine whether dimethylthiourea (DMTU), a hydroxyl radical scavenger, could prevent gastric injury in the rat stomach induced by various noxious agents. Fasted rats (N = 6-8/group) were given a 1-ml oral bolus of saline or DMTU over the dose range 10-500 mg/kg. After 30 min, animals received 1 ml of 100% ethanol orally and were sacrificed 5 min later. At sacrifice, stomachs were harvested and the degree of macroscopic damage was assessed by planimetry. In selected animals, specimens of gastric mucosa were also processed for histology. Saline pretreatment prior to ethanol exposure resulted in 22.5% injury to the glandular epithelium when assessed macroscopically. DMTU pretreatment prevented such injury in a dose-related fashion with only 2% of the mucosa showing injury with a 500 mg/kg dose (P less than 0.01 vs control). Although the superficial injury involving surface mucous cells induced by ethanol was not altered by DMTU, the deep damage to gastric glands was almost completely prevented. Other experiments in which DMTU was given intraperitoneally demonstrated similar protective effects against ethanol injury. Additional studies showed that indomethacin did not prevent the protective effects of oral or intraperitoneal DMTU, excluding a role for endogenous prostaglandins, and that DMTU was equally protective when administered within minutes or as long as 2 hr prior to ethanol exposure. Furthermore, DMTU was also shown to be protective against gastric injury induced by concentrated acid or base. In in vitro studies in which hydroxyl radicals were actually generated, DMTU was noted to scavenge the hydroxyl radical in a dose-related fashion. The ability of DMTU to prevent gastric injury by three different damaging agents suggests that the hydroxyl radical may play a major role in the pathogenesis of such injury and that DMTU mediated its protective action by scavenging this radical species.

Animals↗