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Biomedical subjects

S Morris

Publications and source records attributed to S Morris.

At least 37 records · Page 2Linked to original sources
PubMed2001

Neuroendocrine regulation of osmoregulation and the evolution of air-breathing in decapod crustaceans.

Gills are the primary organ for salt transport, but in land crabs they are removed from water and thus ion exchanges, as well as CO(2) and ammonia excretion, are compromised. Urinary salt loss is minimised in land crabs by redirecting the urine across the gills where salt reabsorption occurs. Euryhaline marine crabs utilise apical membrane branchial Na(+)/H(+) and Cl(-)/HCO(3)(-) exchange powered by a basal membrane Na(+)/K(+)-ATPase, but in freshwater crustaceans an apical V-ATPase provides for electrogenic uptake of Cl(-) in exchange for HCO(3)(-). The HCO(3)(-) is provided by carbonic anhydrase facilitating CO(2) excretion while NH(4)(+) can substitute for K(+) in the basal ATPase and for H(+) in the apical exchange. Gecarcinid land crabs and the terrestrial anomuran Birgus latro can lower the NaCl concentration of the urine to 5 % of that of the haemolymph as it passes across the gills. This provides a filtration-reabsorption system analogous to the vertebrate kidney. Crabs exercise hormonal control over branchial transport processes. Aquatic hyper-regulators release neuroamines from the pericardial organs, including dopamine and 5-hydroxytryptamine (5-HT), which via a cAMP-mediated phosphorylation stimulate Na(+)/K(+)-ATPase activity and NaCl uptake. Freshwater species utilise a V-ATPase, and additional mechanisms of control have been suggested. Crustacean hyperglycaemic hormone (CHH) has now also been confirmed to have effects on hydromineral regulation, and a putative role for neuropeptides in salt and water balance suggests that current models for salt regulation are probably incomplete. In a terrestrial crabs there may be controls on both active uptake and diffusive loss. The land crab Gecarcoidea natalis drinking saline water for 3 weeks reduced net branchial Na(+) uptake but not Na(+)/K(+)-ATPase activity, thus implying a reduction in diffusive Na(+) loss. Further, in G. natalis Na(+) uptake and Na(+)/K(+)-ATPase were stimulated by 5-HT independently of cAMP. Conversely, in the anomuran B. latro, branchial Na(+) and Cl(-) uptake and Na(+)/K(+)-ATPase are inhibited by dopamine, mediated by cAMP. There has been a multiple evolution of a kidney-type system in terrestrial crabs capable of managing salt, CO(2) and NH(3) movements.

Air↗
PubMed2001

The future of journals: where will electronic publishing take us?

Journals provide much that is of immense value to the researcher and practitioner. Yet the economics of journals are unsustainable; the amount of publishable research is increasing more rapidly than the funds available to buy it. Various alternative models are emerging, none of them without problems. The way forward is not clear, but change is inevitable.

Copyright↗
PubMed2001

Ecology and behavior of Gecarcoidea natalis, the Christmas Island red crab, during the annual breeding migration.

The terrestrial crab Gecarcoidea natalis is endemic to the forests of Christmas Island but must migrate each year to the coast to breed. During 1993 and 1995, radio-tracking, mark and recapture, and counting methods were used to establish the routes, walking speeds, direction of travel, and destinations of migrating crabs, as well as crab numbers and distribution. The density of crabs ranged from 0.09 to 0.57 crabs per square meter, which gave a population estimate of 43.7 million adult crabs on the island. During the dry season the crabs were relatively inactive but on arrival of the wet season immediately began their migration. The crabs generally walked in straight lines, and most crabs from around the Island traveled toward the northwest shore instead of simply walking toward the nearest shore. The maximum recorded distance walked by a red crab in one day was 1460 m, but the mean was 680 m per day in 1993 and 330 m in 1995. Comparing the 1993 and 1995 study seasons, there was a 3-week difference in the timing of the start of the migration, but the spawning date was fixed by the lunar phase and took place 17 to 18 days after mating. In 1993, late rain prompted a "rushed" migration and crabs walked directly to their shore destinations; in contrast, in 1995 most crabs made stops of 1 to 7 days during the downward migration. By giving the crabs a chance to feed along the way and minimizing the time that the population was concentrated near the shore, these stops may be important in ensuring that the animals have enough food after the long dry season. Furthermore, this behavior implies that the crabs are able to judge how far away they are from the shore during the migration.

Animals↗
PubMed2001

Metabolic status and respiratory physiology of Gecarcoidea natalis, the Christmas Island red crab, during the annual breeding migration.

With the arrival of the monsoonal rains and after months of inactivity during the dry season, the terrestrial crab Gecarcoidea natalis embarks on its annual breeding migration to the coast. The physiological demands of the migration were assessed by determining respiratory gases in the hemolymph, key metabolites, and energy stores in G. natalis during two migratory seasons. At the end of each day of migration the pulmonary hemolymph PO2 decreased by 1-2.5 kPa, but the hemocyanin remained saturated with O2 and the venous reserve was largely unchanged (O2 > 0.4 mmol x l(-1)). The breeding migration of red crabs was accomplished without recourse to anaerobiosis, even though at times walking speeds (up to 6.2 +/- 0.5 m x min(-1)) exceeded those that promoted anaerobiosis in non-migrating crabs and in crabs exercised in the laboratory. In contrast to all previous studies, at the end of each day of migrating, red crabs experienced an alkalosis (up to 0.1 pH units) rather than any acidosis. This alkalosis was removed overnight when the crabs were inactive. Although there were seasonal fluctuations in the glycogen, glucose, and triglyceride stores, crabs engaging in the migration did not draw on these stores and must have fed along the way. In contrast, crabs returning from breeding activities on the shore terraces had significantly depleted glycogen stores. Additionally, in 1993, the male crabs returning from the breeding activities on the terraces were dehydrated and experienced a decrease in muscle tissue water of 11%. In contrast to the breeding migration per se, fighting for burrows in which breeding occurs produced severe anaerobiosis in males, especially the victors: after 135 s of combat, the maximum L-lactate concentration in the hemolymph was 35 mmol x l(-1). It appears that burrowing, courtship, and mating are more demanding than the migration itself. Furthermore, the data provide evidence that the metabolic responses of migrating individuals of G. natalis might be different from those at other times of the year.

Animals↗
PubMed2001

Catchment management and the Great Barrier Reef.

Pollution of coastal regions of the Great Barrier Reef is dominated by runoff from the adjacent catchment. Catchment land-use is dominated by beef grazing and cropping, largely sugarcane cultivation, with relatively minor urban development. Runoff of sediment, nutrients and pesticides is increasing and for nitrogen is now four times the natural amount discharged 150 years ago. Significant effects and potential threats are now evident on inshore reefs, seagrasses and marine animals. There is no effective legislation or processes in place to manage agricultural pollution. The Great Barrier Reef Marine Park Act does not provide effective jurisdiction on the catchment. Queensland legislation relies on voluntary codes and there is no assessment of the effectiveness of the codes. Integrated catchment management strategies, also voluntary, provide some positive outcomes but are of limited success. Pollutant loads are predicted to continue to increase and it is unlikely that current management regimes will prevent this. New mechanisms to prevent continued degradation of inshore ecosystems of the Great Barrier Reef World Heritage Area are urgently needed.

Agriculture↗
PubMed2001

Markers of low level arsenic exposure for evaluating human cancer risks in a US population.

Epidemiologic studies conducted in the US have not previously detected an association between regional drinking water arsenic concentrations and corresponding cancer occurrence or mortality rates. To improve our estimation of cancer risk and arsenic exposure in the USA, we have investigated the reliability of several exposure markers. In the current study, we specifically evaluated the long-term reproducibility of tap water and toenail concentrations of arsenic, and the relation between water, toenail, and urinary measurement. Subjects included 99 controls in our case-control study on whom we requested a household tap water sample and toenail clipping three to five years apart. Additionally, participants were asked to provide a first morning void sample at the second interview. Tap water arsenic concentrations ranged from undetectable (<0.01 microg/L) to 66.6 microg/L. We found a significant correlation between both replicate water and toenail samples (intraclass correlation coefficient = 0.85, 95% confidence interval = 0.79-0.89 for water, and intraclass correlation coefficient = 0.60, 95% confidence interval = 0.48-0.70 for toenails). The inter-method correlations for water, urinary and toenail arsenic were all statistically significant (r = 0.35, p = 0.0024 for urine vs water; r = 0.33, p = 0.0016 for toenail vs water and r = 0.36, p = 0.0012 for urine vs toenails). Thus, we found both toenail and water measurements of arsenic reproducible over a three- to five-year period. Our data suggest that biologic markers may provide reliable estimates of internal dose of low level arsenic exposure that can be used to assess cancer risk.

Aged↗
PubMed2001

Associations between adverse events in childhood and chronic widespread pain in adulthood: are they explained by differential recall?

OBJECTIVE: Clinic based studies suggest that adverse events in childhood may predispose to chronic pain in adult life. These have been conducted on highly selected groups, and it is unknown whether these relationships hold in the general population and to what extent the increased rate of adverse childhood events in persons with pain is an artefact of differential reporting. We examined the hypothesis that chronic widespread pain was associated with reports of adverse experiences in childhood and whether any observed relationships could be explained by differential recall. METHODS: A cross sectional population based screening survey was conducted. Subjects completed a questionnaire that included assessments of pain and psychological state. In total, 296 subjects who had demonstrated psychological distress were randomly selected and had a detailed interview, which included an assessment of 14 adverse childhood experiences. Medical records relating to childhood were also examined for those subjects. RESULTS: The prevalence of self-reported adverse childhood experiences was greatest in adult subjects with current chronic widespread pain. Exposure to illness in family members, parental loss, operations, and abuse were all associated with increased, but nonsignificant, odds of having chronic widespread pain versus those without such exposures. However the only statistically significant association was with childhood hospitalizations. From medical record information the associations of hospitalizations (OR 5.1, 95% CI 2.0-13.0) and operations (OR 3.0, 95% CI 1.2-7.2) with pain previously noted were partly explained by differential recall between subjects with and without pain: hospitalizations, OR 2.2, 95% CI 0.9-5.5; operations, OR 1.2, 95% CI 0.5-3.4. CONCLUSION: Although several reported adverse events in childhood were observed to be associated with chronic widespread pain in adulthood, only reports of hospitalizations were significantly associated. Validation of self-reported exposures suggests that there was differential recall of past events among those with and without pain, and this differential recall explained the association between hospitalizations and current chronic pain. Such differential recall may explain other observations of an association between reports of adverse childhood events and chronic pain in adulthood.

Adult↗
PubMed2000

Respiratory gas transport, metabolic status, and locomotor capacity of the Christmas Island red crab Gecarcoidea natalis assessed in the field with respect to dichotomous seasonal activity levels.

Red crabs, Gecarcoidea natalis, exhibit seasonal activity patterns: low activity during the dry season when they shelter in burrows to avoid dehydration, and high activity during the wet season. Red crabs were examined in situ in the rainforest of Christmas Island to determine if there were underlying seasonal differences in the capacity for exercise and associated metabolism. During both seasons, free-ranging (FR) crabs engaged in their normal activities and, together with crabs induced to exercise for 5 min, were sampled for haemolymph and muscle tissue. Respiratory gases in the haemolymph and key metabolites were measured to assess differences in metabolic status of FR and exercised crabs. Actively foraging FR crabs during the wet season exhibited a relative haemolymph hypoxia (2.9 kPa) and accumulated an extra 3 mmol. litre(-1) of CO(2) compared to the relatively inactive FR crabs during the dry season. Wet-season crabs appeared to be in a state of relative respiratory acidosis compared to dry-season animals. This hypercapnia may arise as a consequence of a relative hypoventilation in animals with a relatively higher metabolic rate during the wet season. Oxygenation of pulmonary and arterial haemolymph was similar and remained high after 5 min of exercise, indicating that the gills and lungs functioned similarly in gas exchange in both FR and exercised crabs. During exercise, venous O(2) reserves decreased and red crabs experienced a mixed respiratory/metabolic acidosis. Similar changes, after 5 min of enforced exercise, in metabolite concentrations, pH and respiratory gas status in the haemolymph during both sampling seasons suggest that the crabs maintain similar capacity to increase exercise during the wet and the dry seasons, despite the differences in underlying physiological status. This is important since after prolonged inactivity during the dry season, with the arrival of moonsoonal rains, red crabs must engage in their annual breeding migration.

Animals↗
PubMed2000

The immunogenicity of single and combination DNA vaccines against tuberculosis.

DNA immunization is a promising new approach for the development of novel tuberculosis vaccines. In this study, the immune responses following the administration of single and combination tuberculosis DNA vaccines were evaluated. Single DNA vaccines encoding the MPT-63 and MPT-83 tuberculosis antigens evoked partial protection against an aerogenic challenge with M. tuberculosis Erdman in the mouse model of pulmonary tuberculosis. Immunization with a multivalent combination DNA vaccine (containing the ESAT-6, MPT-64, MPT-63, and KatG constructs) generated immune responses that indicated an absence of antigenic competition since antigen-specific cell-mediated and humoral responses were detected to each component of the mixture. More importantly, the combination vaccine elicited a strong protective response relative to the protection evoked by live BCG vaccine.

Aerosols↗
PubMed2000

Zotepine for schizophrenia.

BACKGROUND: Typical antipsychotic drugs are widely used as first line treatment for people with schizophrenia. The atypical class of antipsychotic drugs, however, is making important inroads into this approach and zotepine is one such compound. It is a dopamine antagonist and claimed to be to be particularly effective for negative symptoms OBJECTIVES: To determine the effects of zotepine compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and related psychoses. SEARCH STRATEGY: Electronic searches of Biological Abstracts (1980-1999), CINAHL (1982-1999), The Cochrane Library (Issue 1, 1999), The Cochrane Schizophrenia Group's Register (January 1999), EMBASE (1980-1999), Dialog Corporation Datastar service (1999), MEDLINE (1966-1999), and PsycLIT (1974-1999) were undertaken. References of all identified studies were searched for further trials. Knoll Pharmaceuticals and authors of trials were contacted. SELECTION CRITERIA: All randomised clinical trials that compared zotepine to other treatments for people with schizophrenia or other psychoses were included. DATA COLLECTION AND ANALYSIS: Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were independently extracted. Data were excluded if loss to follow up was greater than 50%. For homogeneous dichotomous data the relative risk (RR), 95% confidence interval (CI) and, where appropriate, the number needed to treat (NNT) and numbers needed to harm (NNH), were calculated on an intention-to-treat basis. For continuous data, weighted mean differences were calculated (WMD). All data were inspected for heterogeneity. MAIN RESULTS: All outcomes were short term (4-12 weeks). Limited data suggest that zotepine is an antipsychotic, at least as effective as typical drugs. Mental state measures of 'no clinically important improvement' favour zotepine when compared to other active drugs (n=356, RR 0.8 CI 0.7-0.9, NNT 7 CI 4-22). About one third of people in both zotepine and control groups left the studies before trial completion. Zotepine may result in less movement disorder adverse effects than typical antipsychotic drugs. Trials have not highlighted clear differences between zotepine and other atypical drugs. REVIEWER'S CONCLUSIONS: Zotepine may be a valuable addition to the increasing ranks of atypical antipsychotic drugs. More data from already existing studies is urgently needed to increase the confidence in the findings of this review. New data from well planned, conducted and reported long term pragmatic randomised trials are necessary. Otherwise clinical use of zotepine will be based on speculation on the meaning of the findings of short explanatory trials for everyday practice.

Antipsychotic Agents↗
PubMed2000

The association between chronic widespread pain and mental disorder: a population-based study.

OBJECTIVE: Patients with chronic widespread pain (CWP) have been reported to have a greater prevalence of mental disorders and somatization than that found in the general population, but the true association between CWP and mental disorders is unknown. In this study, we investigated whether there is an increased prevalence of mental disorder in people with CWP from the general population. We also describe the psychiatric diagnoses associated with CWP. METHODS: In a population-based case-control study, 1,953 subjects (75% of a random sample of individuals age 18-65 years) completed a questionnaire that included a pain assessment and the 12-item General Health Questionnaire (GHQ-12). Of 710 subjects scoring >1 on the GHQ-12, 301 were assessed further using a structured psychiatric interview and detailed assessment of medical records to identify cases of mental disorder, in accordance with criteria of the 10th edition of the International Classification of Diseases. The association between CWP and mental disorder was modeled using logistic regression, adjusting for possible confounders including age, sex, and nonresponders. RESULTS: We estimated the overall population prevalence of mental illness to be 11.9%. The odds of having a mental disorder for subjects with versus those without CWP were 3.18 (95% confidence interval 1.97-5.11). Most subjects with mental disorders were diagnosed as having mood and anxiety disorders. Only 3 cases of somatoform disorders were identified, and all were associated with pain. CONCLUSION: This study, although unable to demonstrate a cause-and-effect relationship, showed that 16.9% of those with CWP were estimated to have a psychiatric diagnosis, suggesting that these disorders should be identified and treated.

Adolescent↗
PubMed2000

Swimming eliminates the weight gain and abdominal fat associated with ovariectomy in the retired breeder rat despite high-fat diet selection.

The effects of swim-training on choice of dietary fat, carbohydrate or protein, weight gain, energy intake, and energy efficiency were examined in ovariectomized and sham-operated retired breeder rats. After a 3 week training period of increased duration, rats swam for 75 min per session (5 days per week) for 4 weeks. Ovariectomized rats gained more weight than sham rats, while swimming reduced weight gain and abdominal fat. As a percentage of total intake, macronutrient choices (weight and energy) were similar for all groups, ovariectomized animals consumed more food and more energy, compared with sham animals. All rats freely chose the majority of their food (g) as carbohydrate and the majority of energy (kJ) as fat. Results indicate that a moderate intensity training program of swimming prevented the weight gain following ovariectomy in older rats despite their excessive caloric intake of fat.

Adipose Tissue↗
PubMed2000

Utilization of docosahexaenoic acid from intravenous egg yolk phospholipid.

Docosahexaenoic acid (DHA, 22:6n-3) is provided directly to human premature infants during parenteral nutrition from the egg yolk fraction of an intravenous fat emulsion. This study aimed to determine whether the high egg yolk phospholipid content of Intralipid 10% (IL 10%, Pharmacia, Uppsala, Sweden) relative to the standard emulsion Intralipid 20% (IL 20%, Pharmacia) could be a strategy to increase the delivery of DHA to the developing brain. Male, Large White piglets were randomly selected from sows 3 d after birth. Piglets were assigned to receive a 9-d continuous intravenous infusion commencing 5 d after birth of either Intralipid (IL) 10%, IL 20%, or Lipofundin S 20% (LFS; B. Braun, Melsungen, Germany). There were four piglets in each treatment group. IL 10% provides twice as much DHA as IL 20%, while LFS provides no DHA. Protein and other nutrients were provided enterally using a low-fat milk formula. After 9 d, animals were killed, and the fatty acid compositions of blood, liver, and cerebral cortex were analyzed. IL 10% infusion approximately doubled the amount of plasma phospholipid DHA (microg/mL of plasma) in comparison to IL 20%. However, red blood cells, liver, and cerebral cortex phospholipid DHA levels were indistinguishable between these two groups. LFS was associated with reduced levels of DHA in plasma, red blood cell and liver phospholipids in comparison to IL 20%. We conclude that infusion of additional phospholipid is an ineffective strategy for increasing DHA delivery to piglet tissues. This may be due to the formation of inert phospholipid particles in plasma. The data do not support the concept of using IL 10% as a means of providing additional DHA to premature human infants.

Animals↗
PubMed2000

Reversal of caffeine withdrawal by ingestion of a soft beverage.

Followlng regular use, acute cessation of caffeine is associated with a characteristic withdrawal syndrome. Despite this, caffeine remains popular with its consumers. The aim of this study was to examine the physiologic and psychologic effects of small caffeine doses, administered in the form of a market-leading soft drink, on healthy women who were acutely withdrawn from caffeine. After 48-h abstinence and overnight fast, 11 healthy (22 to 40 years) female volunteers, all regular caffeine users (daily consumption 143 to 773 mg) consumed using a double-blind. randomized, controlled cross-over design either 2 tins of regular or caffeine-free Diet Coke. On both visits a Mars bar was eaten to prevent hypoglycaemia. Thus, the caffeine load was 76 or 10 mg respectively. Following ingestion of regular Diet Coke, there was a l0% fall in middle cerebral artery velocity (95% CI [6%-l4%], p < 0.005 versus caffeine free) and improvement in feelings of pleasure (p < 0.046) and energy (p < 0.037). Intellectual function (4-choice reaction time) was unaffected by caffeine status. On both visits, ingestion of Diet Coke induced a pressor response (maximum rise in systolic pressure +15+/- 2 mm Hg with caffeine and +l2 +/- 2 mm Hg with caffeine-free beverage, both p < 0.001 compared with baseline). In conclusion, in women acutely withdrawn from caffeine, ingestion of a popular soft beverage containing modest amounts of caffeine is associated with demonstrable physiologic and psychologic effects.

Adult↗
PubMed2000

Use of complementary and alternative medicine among Dominican emergency department patients.

This small, pilot study examined presenting complaint, brief health history, use of complementary and alternative medicine (CAM), and sociodemographic characteristics, among patients attending the emergency department (ED) of a large urban hospital. The sample (n = 50) was primarily Dominican and of low socioeconomic status. Almost half had used CAM for their presenting complaint or another health problem during the past year, most commonly in the form of medicinal plants made into herbal teas. CAM users were more likely to be female, longer-term residents of the United States, and to have also used religious practices for health problems. Subjects who had used CAM for any problem other than the presenting complaint during the past year rated its effectiveness higher than subjects who had used CAM for their presenting complaint. In conclusion, it is likely that a significant proportion of Dominican ED patients use CAM, suggesting that they should be asked about their CAM use during triage.

Adult↗