PubMed Health⌕ Search

Biomedical subjects

J Field

Publications and source records attributed to J Field.

At least 55 records · Page 3Linked to original sources
PubMed1999

Helping behaviour in facultatively eusocial hover wasps: an experimental test of the subfertility hypothesis.

A candidate explanation for the evolution of eusociality is that helpers are physiologically constrained such that helping is their only realistic option. We tested this subfertility hypothesis in a species of facultatively eusocial hover wasp (Hymenoptera, Stenogastrinae: Liostenogaster flavolineata) by seeing whether helpers that were forced to nest on their own were able to mature their own eggs. One focal helper was left alone on each of 22 nests, from which all other adult wasps (including the dominant) were permanently removed. After 18 days, all but one of the 19 focal helpers that remained on their nests had ovarian development and insemination status characteristic of dominants, and the majority had probably laid eggs. This was in striking contrast to the reproductive status of other helpers removed from the same nests at the start of the experiment. These results provide convincing experimental evidence that females do not become helpers because of some unconditional physiological constraint. There is currently no unequivocal support for the subfertility hypothesis in facultatively eusocial Hymenoptera lacking morphological castes. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Changes in weight, fluid balance and serum albumin in patients referred for nutritional support.

BACKGROUND AND AIMS: Starvation and injury impair the excretion of an excess sodium and water load, resulting in oedema and hypoalbuminaemia, which may have adverse effects on gastrointestinal physiology. We have retrospectively assessed clinical signs and fluid balance in 44 adult patients referred for nutritional support for >== 10 days. METHODS: Clinical evidence of oedema was noted. Oedematous patients were managed with a low sodium (0-50 mmol/day), low volume (2 l/day) feed. Some also received albumin and a diuretic. Body weight was recorded daily and serum albumin three times weekly. The lowest recorded weight during nutritional support and the weight at the time of discharge were correlated with serum albumin concentration. RESULTS: The 21 patients with oedema had acute surgical conditions and complications such as sepsis while the 23 non-oedematous patients had chronic conditions with gradual nutritional depletion. During nutritional support the mean (SEM) weight in kg of the oedematous patients fell from 79.3 (2.9) to 69.2 (3.2) (P>> 0.00001) and subsequently rose to 70.1 (3.2) (P= 0.005). Corresponding values for the non-oedematous patients were 61.4 (4.0), 60.2 (3.9) (P>> 0.05) and 61.2 (3.7) (P= 0.002) respectively. Weight reduction reflected negative salt and water balance and correlated with a rise in serum albumin (r = -0.61 for oedematous and r = -0.65 for non-oedematous patients) largely reflecting reversal of previous dilution. CONCLUSION: These findings have important implications for the salt and water content of perioperative fluid and nutritional prescriptions. They also emphasize the dilutional component of hypoalbuminaemia in these patients.

Albumins↗
PubMed1999

The SH3 domain of the S. cerevisiae Cdc25p binds adenylyl cyclase and facilitates Ras regulation of cAMP signalling.

Cdc25 and Ras are two proteins required for cAMP signalling in the budding yeast Saccharomyces cerevisiae. Cdc25 is the guanine nucleotide exchange protein that activates Ras. Ras, in turn, activates adenylyl cyclase. Cdc25 has a Src homology 3 (SH3) domain near the N-terminus and a catalytic domain in the C-terminal region. We find that a point mutation in the SH3 domain attenuates cAMP signalling in response to glucose feeding. Furthermore, we demonstrate, by using recombinant adenylyl cyclase and Cdc25, that the SH3 domain of Cdc25 can bind directly to adenylyl cyclase. Binding was specific, because the SH3 domain of Abp1p (actin-binding protein 1), which binds the 70,000 Mr subunit of adenylyl cyclase, CAP/Srv2, failed to bind adenylyl cyclase. A binding site for Cdc25-SH3 localised to the C-terminal catalytic region of adenylyl cyclase. Finally, pre-incubation with Ras enhanced the SH3-bound adenylyl cyclase activity. These studies suggest that a direct interaction between Cdc25 and adenylyl cyclase promotes efficient assembly of the adenylyl cyclase complex.

Adenylyl Cyclases↗
PubMed1999

Algodystrophy and its association with Dupuytren's disease.

Seventy-two patients were examined 9 weeks after sustaining a Colles' fracture of the wrist for evidence of algodystrophy. They were examined 18 months later for evidence of Dupuytren's disease to determine the incidence of the association between the two conditions. Forty-one per cent of all patients had evidence of Dupuytren's disease at 18 months following Colles' fracture. Sixty-seven per cent of patients with algodystrophy had evidence of Dupuytren's disease compared with 19% of patients who showed no features of algodystrophy.

Aged↗
PubMed1999

Prescribing of beta-2 agonists and inhaled steroids in England: trends between 1992 and 1998, and association with material deprivation, chronic illness and asthma mortality rates.

BACKGROUND: British Thoracic Society guidelines published in 1990, revised in 1993 and 1997, recommended that general practitioners should make greater use of inhaled steroids in the management of asthma. British Thoracic Society guidelines have also been published on the management of chronic obstructive pulmonary disease. The objective of this study was to examine trends in the prescribing of beta-2 agonists and inhaled steroids in England between 1992 and 1998, and to investigate the variation at health authority level in the use of these drugs. METHODS: This was an observational study using prescribing analysis and cost (PACT) data, mortality data and data from the 1991 Census for all 100 health authorities in England. RESULTS: The number of defined daily doses of beta-2 agonists prescribed per quarter increased by 20 per cent, from 142 million to 170 million between June 1992 and March 1998. The number of defined daily doses of inhaled steroids prescribed per quarter increased by 78 per cent during the same period, from 69.9 million to 124.7 million. The ratio of inhaled steroids to beta-2 agonists increased from 0.49 to 0.73. The number of items per 1000 specific therapeutic group age-sex related prescribing units (STAR-PUs) in 1997 in health authorities in England varied from 41 to 115 for beta-2 agonists and from 24 to 68 for inhaled steroids. The ratio of the number of items of inhaled steroids to beta-2 agonists varied from 0.50 to 0.70. At health authority level, prescribing rates were most strongly associated with the percentage of patients reporting chronic illness (correlation coefficient 0.82 for beta-2 agonists and 0.72 for inhaled steroids). There were significant negative correlations between the ratio of inhaled steroids to beta-2 agonists and both Jarman deprivation scores (r = -0.51) and chronic illness (r = -0.38). There were no significant associations between health authority prescribing rates and death rates from asthma in people aged 5-44 years. CONCLUSIONS: Prescribing of inhaled steroids has risen more quickly than that of beta-2 agonists between 1992 and 1998, resulting in a marked increase in the ratio of inhaled steroids to beta-2 agonists. At health authority level, there remains a wide variation in the use of beta-2 agonists and inhaled steroids.

Administration, Inhalation↗
PubMed1999

Chitinase secretion by encysting Entamoeba invadens and transfected Entamoeba histolytica trophozoites: localization of secretory vesicles, endoplasmic reticulum, and Golgi apparatus.

Entamoeba histolytica, the protozoan parasite that phagocytoses bacteria and host cells, has a vesicle/vacuole-filled cytosol like that of macrophages. In contrast, the infectious cyst form has four nuclei and a chitin wall. Here, anti-chitinase antibodies identified hundreds of small secretory vesicles in encysting E. invadens parasites and in E. histolytica trophozoites overexpressing chitinase under an actin gene promoter. Abundant small secretory vesicles were also identified with antibodies to the surface antigen Ariel and with a fluorescent substrate of cysteine proteinases. Removal of an N-terminal signal sequence directed chitinase to the cytosol. Addition of a C-terminal KDEL peptide, identified on amebic BiP, retained chitinase in a putative endoplasmic reticulum, which was composed of a few vesicles of mixed sizes. A putative Golgi apparatus, which was Brefeldin A sensitive and composed of a few large, perinuclear vesicles, was identified with antibodies to ADP-ribosylating factor and to epsilon-COP. We conclude that the amebic secretory pathway is similar to those of other eukaryotic cells, even if its appearance is somewhat different.

ADP-Ribosylation Factors↗
PubMed1999

Signals from the Ras, Rac, and Rho GTPases converge on the Pak protein kinase in Rat-1 fibroblasts.

Ras plays a key role in regulating cellular proliferation, differentiation, and transformation. Raf is the major effector of Ras in the Ras > Raf > Mek > extracellular signal-activated kinase (ERK) cascade. A second effector is phosphoinositide 3-OH kinase (PI 3-kinase), which, in turn, activates the small G protein Rac. Rac also has multiple effectors, one of which is the serine threonine kinase Pak (p65(Pak)). Here we show that Ras, but not Raf, activates Pak1 in cotransfection assays of Rat-1 cells but not NIH 3T3 cells. We tested agents that activate or block specific components downstream of Ras and demonstrate a Ras > PI 3-kinase > Rac/Cdc42 > Pak signal. Although these studies suggest that the signal from Ras through PI 3-kinase is sufficient to activate Pak, additional studies suggested that other effectors contribute to Pak activation. RasV12S35 and RasV12G37, two effector mutant proteins which fail to activate PI 3-kinase, did not activate Pak when tested alone but activated Pak when they were cotransfected. Similarly, RacV12H40, an effector mutant that does not bind Pak, and Rho both cooperated with Raf to activate Pak. A dominant negative Rho mutant also inhibited Ras activation of Pak. All combinations of Rac/Raf and Ras/Raf and Rho/Raf effector mutants that transform cells cooperatively stimulated ERK. Cooperation was Pak dependent, since all combinations were inhibited by kinase-deficient Pak mutants in both transformation assays and ERK activation assays. These data suggest that other Ras effectors can collaborate with PI 3-kinase and with each other to activate Pak. Furthermore, the strong correlation between Pak activation and cooperative transformation suggests that Pak activation is necessary, although not sufficient, for cooperative transformation of Rat-1 fibroblasts by Ras, Rac, and Rho.

3T3 Cells↗
PubMed1999

Intraosseous ganglion cysts of the ankle: a report of three cases with long-term follow-up.

Three cases of intraosseous ganglion cysts of the ankle are presented with an average follow-up of 68 months (range, 48-78 months). Review of the literature revealed 251 cases of intraosseous ganglion cysts, with 75 located in the ankle and a recurrence rate of 6.1%. In the three cases presented, a satisfactory long-term result was obtained with bone graft and curettage in two cases and currettage alone in one case. No recurrences or complications occurred.

Adult↗
PubMed1999

Teenage fertility and life chances.

Teenage mothers and their children face poorer prospects in life than do women who delay motherhood until later in life. Moreover, patterns of early childbearing tend to be repeated in subsequent generations. Therefore, an understanding of the factors associated with early fertility is important for the prevention of adverse consequences. This paper uses data from the National Survey of Sexual Attitudes and Lifestyles to explore these associations. Early sexual intercourse is an important predictor of early fertility, as is poor educational attainment, although it is not clear to what extent pregnancy acts to thwart academic ambitions, or to what extent poor educational performance leads to a need to seek personal fulfilment in other than academic goals. Thus, interventions designed to influence age at first intercourse and to improve educational performance both have potential in terms of impacting on teenage pregnancy rates. Family background also exerts a powerful influence on teenage fertility. Young people for whom one or both parents are absent are more likely to become parents early in life. However, the most important factor of family life determining the chances of teenage motherhood appear to be the quality of communication about sexual matters with the home. In terms of outcomes, teenage mothers are more likely to live in social housing, are less likely to be in paid employment and have larger than average sized families. Certain areas of the country, notably the older, run-down industrial areas, have higher rates of teenage motherhood than the newer, more prosperous areas. Because most of these effects are independent of one another, there is potential merit in intervening to prevent unintended conception at several points in a young woman's life. Primary preventive efforts are needed to reduce the rates at which teenage pregnancy occurs in this country. Yet, if the cycle of deprivation that means the children of young mothers themselves enter parenthood early is to be broken, then efforts must also be made to mitigate the effects of teenage fertility for both mother and child.

Adolescent↗
PubMed1998

A role for Pak protein kinases in Schwann cell transformation.

Neurofibromatosis type 1 (NF1), a common autosomal dominant disorder caused by loss of the NF1 gene, is characterized clinically by neurofibromas and more rarely by neurofibrosarcomas. Neurofibromin, the protein encoded by NF1, possesses an intrinsic GTPase accelerating activity for the Ras proto-oncogene. Through this activity, it is a negative regulator of Ras. The Pak protein kinase is a candidate for a downstream signaling protein that may mediate Ras signals because it is activated by Rac and Cdc42, two small G proteins required for Ras signaling. Here, we use Pak mutants to explore the role of Pak in Ras signaling in Schwann cells, the cells affected in NF1. Whereas an activated Pak mutant does not transform cells, dominant negative Pak mutants are potent inhibitors of Ras transformation of rat Schwann cells and of a neurofibrosarcoma cell line from an NF1 patient. Although activated Pak stimulated jun-N-terminal kinase, inhibition of Ras transformation by dominant negative Pak did not require inhibition of jun-N-terminal kinase. Instead, the Pak mutants appeared to inhibit transformation by preventing Ras activation of the ERK/mitogen-activated protein kinase cascade. These results have implications for our understanding of NF1 because a neurofibrosarcoma cell line derived from a patient with NF1 was reverted by stable expression of the Pak dominant negative mutants.

Animals↗
PubMed1998

General practitioner's perceptions of the route to evidence based medicine: a questionnaire survey.

OBJECTIVES: To determine the attitude of general practitioners towards evidence based medicine and their related educational needs. DESIGN: A questionnaire study of general practitioners. SETTING: General practice in the former Wessex region, England. SUBJECTS: Randomly selected sample of 25% of all general practitioners (452), of whom 302 replied. MAIN OUTCOME MEASURES: Respondents' attitude towards evidence based medicine, ability to access and interpret evidence, perceived barriers to practising evidence based medicine, and best method of moving from opinion based to evidence based medicine. RESULTS: Respondents mainly welcomed evidence based medicine and agreed that its practice improves patient care. They had a low level of awareness of extracting journals, review publications, and databases (only 40% knew of the Cochrane Database of Systematic Reviews), and, even if aware, many did not use them. In their surgeries 20% had access to bibliographic databases and 17% to the world wide web. Most had some understanding of the technical terms used. The major perceived barrier to practising evidence based medicine was lack of personal time. Respondents thought the most appropriate way to move towards evidence based general practice was by using evidence based guidelines or proposals developed by colleagues. CONCLUSION: Promoting and improving access to summaries of evidence, rather than teaching all general practitioners literature searching and critical appraisal, would be the more appropriate method of encouraging evidence based general practice. General practitioners who are skilled in accessing and interpreting evidence should be encouraged to develop local evidence based guidelines and advice.

Attitude of Health Personnel↗
PubMed1998

Effects of bile duct ligation on hepatic expression of female-specific CYP2C12 in male and female rats.

Gender differences in hepatic sex steroid and drug metabolism result from hormonal regulation of specific cytochrome P450 genes (CYP). In male rats, bile duct ligation (BDL) is associated with down-regulation of the male-specific genes, CYP2C11 and CYP3A2, together with a decrease in serum testosterone levels and a two- to three-fold increase in serum estradiol concentrations. We anticipated that if estrogen is responsible for down-regulation of male-specific CYPs in BDL male rats, the female-specific CYP2C12, which is not normally present in adult male rat liver, should be up-regulated. We examined this proposal by determining the profile of hepatic cytochrome P450 enzymes in female rats subjected to BDL, and by seeking evidence for expression of CYP2C12 in male rats that do not normally express this gene. In female rats killed 5 days after BDL, total cytochrome P450 content and NADPH-cytochrome P450-reductase (P450-reductase) were decreased to 74% and 58% of control, respectively. Microsomal enzyme activities attributable to CYP2A1, CYP2C6, and CYP2E1 were 50% to 60% of control, but ethylmorphine N-demethylase, which in female liver is catalyzed by CYP2C12 and to a lesser extent CYP2C6, was significantly less affected (81% of control). Likewise, levels of CYP2C6 and P450-reductase proteins were decreased in proportion to the corresponding enzyme activities (50% to 60%), while CYP2C12 protein (and mRNA levels) were not altered in BDL female rat liver. In sham-operated male rats, transcripts for CYP2C12 were rarely detected, but mRNA levels rose to appreciable levels within 24 hours of BDL, and CYP2C12 protein was expressed in hepatic microsomes of BDL male rats. Administration of estradiol to male rats produced a similar elevation of CYP2C12 mRNA, to values approximately 40% of female rats. It is concluded that CYP2C12 is up-regulated in male rats with cholestasis caused by BDL, while CYP2C12 protein is preserved in female rats when other microsomal proteins are decreased. These changes may be related to the increase in serum estradiol levels that result from altered hepatic steroid metabolism. The results demonstrate that activities of individual drug-metabolizing enzymes in liver disease can be determined by dysregulation of the constitutive expression of hepatic CYP genes.

Animals↗
PubMed1998

Safe driving education programs at school: lessons from New Zealand.

The self-reported driving and passenger behaviours of senior high school students in Auckland, New Zealand, were assessed prior to and about four months after a school-based program for driver education. The intervention group (n = 176) received a program of 10, one-hour sessions dealing with knowledge, attitudes and judgements relating to safe driving. A control group (n = 146) did not receive any formal driving safety education. Analyses of pre-treatment and follow-up questionnaire responses revealed that both the intervention and control groups showed significant improvements in knowledge about safe driving over time. Males reported more risky attitudes and behaviours than females throughout the study. There were no significant differences between the intervention and control groups on any measures. In discussing these findings, particular attention is paid to the program content and the social context in which such interventions are carried out.

Adolescent↗
PubMed1998

Puffer fish poisoning.

Regarded by many as a delicacy, puffer fish (Lagocephalus scleratus) is a lethal source of food poisoning with a high mortality. It contains tetrodotoxin which can cause death by muscular paralysis, respiratory depression, and circulatory failure. A case of mild intoxication is reported and the literature reviewed.

Adult↗
PubMed1998

New Zealand children's involvement in home activities that carry a burn or scald risk.

OBJECTIVES: The self reported involvement of elementary schoolchildren from Auckland, New Zealand was measured from home activities that carry a burn or scald risk. METHOD: A survey was conducted with 421 children aged 7-13 years. The survey asked children whether they carried out specific home activities involving hot water, fire, or appliances that carry a burn risk. It also measured their knowledge of the three basic fire safety messages taught to New Zealand schoolchildren by the fire service. RESULTS: The results showed that although involvement levels increased with age, the majority of even the youngest children reported carrying out a number of the risky activities, such as preparing hot drinks, running their own baths, or using a microwave without help. No gender differences were found in the number of risky activities engaged in. Significant ethnic differences were found, with higher risk involvement by indigenous Maori and children of Pacific Island descent than children of European or Asian descent. Each of the three fire safety messages were correctly identified by between 79%-91% of the children. CONCLUSIONS: Investigation of children's involvement in household activities that carry an injury risk may help in the design of prevention strategies, including school based education. Prevention efforts need to acknowledge the ages at which children begin to undertake specific household tasks, including those that involve care for younger siblings, and be attuned to the needs of different ethnic groups.

Age Factors↗
PubMed1997

Psychological distress associated with algodystrophy.

We have carried out a prospective study of the level of psychological distress in patients with Colles' fractures. Those who developed algodystrophy did not show increased distress before the onset of the condition.

Aged↗
PubMed1997

Algodystrophy is an early complication of Colles' fracture. What are the implications?

One hundred patients who had sustained a Colles' fracture were observed for features of algodystrophy at 1, 5, 9 and 12 weeks following injury. The diagnosis of algodystrophy was possible as soon as 1 week after fracture. Early diagnosis has important clinical implications: the aetiological factors may become apparent and different treatment modalities be identified; furthermore, early treatment can be started, limiting the morbidity of the condition. It is proposed that patients with features of algodystrophy require physiotherapy after a Colles' fracture. Those without features may not.

Aged↗