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Biomedical subjects

F Clark

Publications and source records attributed to F Clark.

At least 19 recordsLinked to original sources
PubMed2002

Host location, survival and fecundity of the Oriental rat flea Xenopsylla cheopis (Siphonaptera: Pulicidae) in relation to black rat Rattus rattus (Rodentia: Muridae) host age and sex.

Host choice and fecundity are two factors that may contribute to the variation in flea counts observed when assessing the potential risk of flea-borne transmission of pathogens from rodents to humans. Using the black rat, Rattus rattus Linnaeus, as host the effects of age and sex on host choice and fecundity of the Oriental rat flea, Xenopsylla cheopis Rothschild, were examined experimentally at 25 degrees C and 80% rh. During the first two days of emergence from cocoons, female fleas dominated the sex ratio by 4:1 but from the third day onwards this switched to a male-dominated sex ratio of 4:1. The sex of the flea did not influence their host-seeking behaviour. Newly emerged fleas of both sexes were not influenced by the rat's presence and at seven days old both sexes demonstrated similar levels of attraction toward the rat host. The sex of the rat did not affect flea host-seeking behaviour. There was a 50-70% decline in the initial number of adult fleas during the first week after their release onto a rat host, and this decline was greatest on juvenile rats. Flea fecundity was also significantly lower on juvenile rat hosts but no differences due to the sex of the rat were observed. This experimental study supports the hypothesis that differences in flea count due to host sex, reported in field surveys, result from sexual differences in host behaviour and not from discriminatory host-seeking behaviour by X. cheopis. Differences in flea count due to host age may be affected by differences in X. cheopis fecundity, which may itself be mediated by host behaviour such as grooming.

Animals↗
PubMed2001

Human GC-AG alternative intron isoforms with weak donor sites show enhanced consensus at acceptor exon positions.

It has been previously observed that the intrinsically weak variant GC donor sites, in order to be recognized by the U2-type spliceosome, possess strong consensus sequences maximized for base pair formation with U1 and U5/U6 snRNAs. However, variability in signal strength is a fundamental mechanism for splice site selection in alternative splicing. Here we report human alternative GC-AG introns (for the first time from any species), and show that while constitutive GC-AG introns do possess strong signals at their donor sites, a large subset of alternative GC-AG introns possess weak consensus sequences at their donor sites. Surprisingly, this subset of alternative isoforms shows strong consensus at acceptor exon positions 1 and 2. The improved consensus at the acceptor exon can facilitate a strong interaction with U5 snRNA, which tethers the two exons for ligation during the second step of splicing. Further, these isoforms nearly always possess alternative acceptor sites and exhibit particularly weak polypyrimidine tracts characteristic of AG-dependent introns. The acceptor exon nucleotides are part of the consensus required for the U2AF(35)-mediated recognition of AG in such introns. Such improved consensus at acceptor exons is not found in either normal or alternative GT-AG introns having weak donor sites or weak polypyrimidine tracts. The changes probably reflect mechanisms that allow GC-AG alternative intron isoforms to cope with two conflicting requirements, namely an apparent need for differential splice strength to direct the choice of alternative sites and a need for improved donor signals to compensate for the central mismatch base pair (C-A) in the RNA duplex of U1 snRNA and the pre-mRNA. The other important findings include (i) one in every twenty alternative introns is a GC-AG intron, and (ii) three of every five observed GC-AG introns are alternative isoforms.

Alternative Splicing↗
PubMed2001

Regional analgesia in the intensive care unit. Principles and practice.

Nociception is a complicated process, and only in recent years have the neural pathways and mediators of pain transmission been unraveled. Several regional anesthetic interventions, most notably epidural drug delivery, can interrupt nociception and provide safe and effective pain control in critically ill patients while substantially reducing the need for systemic medications. This article discusses the possibilities for regional control of the neurobiology of nociception and describes the arsenal of regional anesthetic techniques available to the intensivist. Used wisely, regional techniques can provide excellent pain control and may have a significant role in improving overall patient outcome. Regional analgesia offers the best opportunity to provide substantial analgesia without significant central opioid effects. Well-conducted regional analgesia can reduce many of the unpleasant or potentially problematic side effects observed when traditional intravenous medications are used exclusively for pain control.

Analgesia↗
PubMed2001

Embedding health-promoting changes into the daily lives of independent-living older adults: long-term follow-up of occupational therapy intervention.

The Well Elderly Study was a randomized trial in independent-living older adults that found significant health, function, and quality of life benefits attributable to a 9-month program in preventive occupational therapy (OT). All participants completing the trial were followed for an additional 6 months without further intervention and then reevaluated using the same battery of instruments. Long-term benefit attributable to preventive OT was found for the quality of interaction scale of the Functional Status Questionnaire and for six of eight scales on the RAND SF-36: physical functioning, role functioning, vitality, social functioning, role emotional, and general mental health (p<.05). Approximately 90% of the therapeutic gain observed following OT treatment was retained in follow-up. The finding of a sustained effect for preventive OT is of great public health relevance given the looming health care cost crisis associated with our nation's expanding elderly population.

Activities of Daily Living↗
PubMed2001

Discovery of a novel murine type C retrovirus by data mining.

Analysis of genomic and expression data allows both identification and characterization of novel retroviruses. We describe a recombinant type C murine retrovirus, similar to the Mus dunni endogenous retrovirus, with VL30-like long terminal repeats and murine leukemia virus-like coding sequences. This virus is present in multiple copies in the mouse genome and expressed in a range of mouse tissues.

Amino Acid Sequence↗
PubMed2000

Derivation and pilot assessment of a health promotion program for Mandarin-speaking Chinese older adults.

As the percentage of older adults of diverse ethnicities increases in the United States, the call for culturally sensitive health care service strategies that target the special needs of older people grows. The present report describes methods used to adapt a health care program so that it would better meet the needs of a group of well, older Mandarin-speaking Chinese residents of Los Angeles. The specific qualitative research procedures that we used to adapt the treatment program are described, along with the particular adaptations that emerged. Additionally, outcomes from a randomized pilot experiment are presented that are consistent with the notion that the adapted program was effective in reducing health-related declines among older Mandarin-speaking men and women. The overall outcome of this project is in agreement with other reports in the health care literature that address the importance of providing culturally sensitive health care service for elders.

Aged↗
PubMed1999

Psychometric properties of a Chinese translation of the SF-36 health survey questionnaire in the Well Elderly Study.

OBJECTIVES: To evaluate the psychometric properties of a Chinese translation of the 36-item Short Form Health Survey (SF-36) in the Well Elderly Study--a randomized clinical trial designed to evaluate the effectiveness of preventive occupational therapy services specifically tailored for multiethnic, independent-living, older adults. METHODS: Translation and back-translation procedures were used to obtain appropriate meanings for the SF-36 survey questions and to ensure face, functional, and conceptual equivalence. RESULTS: Statistical analyses demonstrated satisfactory reliability and validity, with the results generally similar to those reported for older Anglo adults. DISCUSSION: As the percentage of older adults of diverse ethnicity increases, the need for health care research and service strategies that can effectively include multiple ethnicities becomes paramount. The results of this study suggest that a Chinese-translated SF-36 can be used to assess multiple dimensions of health in a Mandarin-speaking population of older adults.

Aged↗
PubMed1999

Effects of feeding on the circadian rhythm of Ceratophyllus s. sciurorum (Siphonaptera: Ceratophyllidae).

Circadian rhythm in newly emerged blood-fed individuals of the flea Ceratophyllus s. sciurorum was studied in a constant environment, using an insect activity monitor. The results of trials run continuously over seven days confirmed the finding that C. s. sciurorum has a self-sustaining clock. Statistical tests confirm that feeding weakens the rhythm but does not eliminate it. There was a significant difference in the mean activity between the fed and unfed fleas, reflecting the difference in the number of hours over which this activity took place. A possible commercial application for the monitor and also for the method of analysis is discussed.

Animals↗
PubMed1998

Occupation in lifestyle redesign: the Well Elderly Study Occupational Therapy Program.

This article describes an innovative preventive occupational therapy intervention for well older adults, the Well Elderly Treatment Program. In a previously reported large-scale randomized effectiveness study, this intervention was found to be highly successful in enhancing the physical and mental health, occupational functioning, and life satisfaction of multicultural, community-dwelling elders. In this article, the philosophical background, manner of development, topical content, methods of program delivery, and mechanisms underlying the program's positive effects are discussed, along with implications for occupational therapy practice. The treatment was based on application of occupational science theory and research and emphasized the therapeutic process of lifestyle redesign in enabling the participants to actively and strategically select an individualized pattern of personally satisfying and health-promoting occupations. The wide-ranging effectiveness of the program supports the occupational therapy profession's emphasis on occupation in affecting health and positions practitioners to extend their services to the realm of preventive interventions.

Aged↗
PubMed1997

A circadian rhythm of locomotor activity in newly emerged Ceratophyllus sciurorum.

Circadian rhythm in newly emerged individuals of the Red Squirrel (Scuirus vulgaris) flea C.s.sciurorum was studied in a constant environment, using an insect activity monitor. Trials were run over 7 days using two start times (08.00 and 17.00 hours). The results show that, regardless of start time, the fleas display a 24 h activity rhythm. The presence of a rhythm under constant conditions gives a strong indication that C.s.sciurorum has a self-sustaining clock which is started by disturbance and is most likely to be linked to host activity patterns.

Animals↗
PubMed1997

The psychopathic individual: a lack of responsiveness to distress cues?

In this study, we investigated the psychophysiological responsiveness of psychopathic individuals to distress cues and to threatening and neutral stimuli. Eighteen psychopathic individuals and 18 incarcerated control individuals, identified using the Revised Psychopathy Checklist (Hare, 1991, The Hare Psychopathy Checklist-Revised, Toronto: Multi-Health Systems), were shown slides of these three types of stimuli, and their electrodermal responses were recorded. The psychopathic individuals showed (relative to the controls) reduced electrodermal responses to the distress cues. In contrast, the two groups did not differ in their electrodermal responses to the threatening stimuli and to the neutral stimuli. The results are interpreted within the Violence Inhibition Mechanism model (Blair, 1995, Cognition, 57, 1-29) of the psychopathic individual.

Adult↗
PubMed1996

The incidence of diabetes mellitus in an English community: a 20-year follow-up of the Whickham Survey.

The original Whickham Survey documented the prevalence of diabetes and lipid disorders in a sample of 2779 adults aged 18 years and over, which matched the British population structure. The aim of the 20-year follow-up study was to determine the incidence and natural history of diabetes. Outcomes in terms of morbidity and mortality at follow-up were determined in over 97% of the original population. Ninety-four subjects had been identified and treated for diabetes since the first survey, including 17 subjects identified as having a fasting plasma glucose > or = 7.8 mmol l-1 at follow-up. The incidence of diabetes for the total population was 2.2 1000-1 year-1 (95% confidence interval 1.8, 2.6). The risk factors identified at first survey were corrected for age, cut-off at the 95 centile and entered into a log linear model. Those which strongly predicted development of diabetes in the total population were fasting blood glucose (odds ratio (OR) (with 95% confidence intervals) = 2.3 (1.5, 3.5)) and body mass index (OR = 2.2 (1.5, 3.3)) in men, and fasting blood glucose (OR = 2.6 (1.7, 4.1)) and fasting serum triglyceride (OR = 2.8 (1.8, 4.4)) in women. A logit model has enabled the calculation of the probability of developing diabetes 20 years later. It was the characteristics of becoming older such as obesity, hypertriglyceridaemia, and raised fasting blood glucose, rather than age itself, which were associated with the development of diabetes.

Adult↗
PubMed1996

The development of ischemic heart disease in relation to autoimmune thyroid disease in a 20-year follow-up study of an English community.

The original Whickham Survey documented risk factors for cardiovascular disease and the prevalence of thyroid disorders in a sample of 2779 adults that closely matched the British population. A 20-year follow-up study has determined outcomes in terms of morbidity and mortality from ischemic heart disease in over 97% of the original survey population. Analysis of deaths from all causes and from ischemic heart disease showed no association with antithyroid antibody status identified at first survey. A multiple logistic regression using the development of ischemic heart disease in the total population at follow-up as the dependent variable found that the significant predictor variables for men were age, cholesterol, mean arterial blood pressure, smoking history, and skinfold thickness index. For women only age, cholesterol, and mean arterial blood pressure were significant. The presence of autoimmune thyroid disease, as defined by either hypothyroidism, positive antithyroid antibodies, or raised serum thyrotropin at first survey, was not significant. A retrospective cohort study of a subsample of women identified at first survey with positive antithyroid antibodies or raised serum thyrotropin and closely matched controls found no significant association with mortality or development of ischemic heart disease. There is no evidence from this study to suggest that evidence of autoimmune thyroid disease identified 20 years ago is associated with an increased risk of ischemic heart disease.

Adolescent↗