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Biomedical subjects

S R Clark

Publications and source records attributed to S R Clark.

At least 19 recordsLinked to original sources
PubMed2006

Dark-state cooling of atoms by superfluid immersion.

We propose and analyze a scheme to cool atoms in an optical lattice to ultralow temperatures within a Bloch band and away from commensurate filling. The protocol is inspired by ideas from dark-state laser cooling but replaces electronic states with motional levels and spontaneous emission of photons by emission of phonons into a Bose-Einstein condensate, in which the lattice is immersed. In our model, achievable temperatures correspond to a small fraction of the Bloch bandwidth and are much lower than the reservoir temperature. This is also a novel realization of an open quantum optical system, where known tools are combined with new ideas involving cooling via a reservoir.

Journal Article↗
PubMed2001

RpoN of Rhizobium leguminosarum bv. viciae strain VF39SM plays a central role in FnrN-dependent microaerobic regulation of genes involved in nitrogen fixation.

The rpoN gene, which codes for the alternative transcription factor sigma54, was cloned and sequenced from Rhizobium leguminosarum strain VF39SM. Construction of a rpoN mutant allowed analysis of the role of RpoN as a transcriptional regulator of genes carrying lacZ reporter fusions. Analysis of a rpoN::lacZ transcriptional fusion in the rpoN background revealed that this gene was negatively autoregulated. Site-directed mutagenesis was used to demonstrate that this autoregulation was dependent on a reverse complement RpoN binding site located upstream of the rpoN gene. rpoN was shown to be required for full microaerobic expression of both copies of fixGHIS, as well as of fixNOQP, despite the absence of apparent rpoN binding sites upstream of fixG. Moreover, rpoN was found to be required for full microaerobic expression of fnrN, which in turn is absolutely required for microaerobic induction of fixGHIS. This suggests that the reduced fixG::lacZ expression seen in the rpoN background is due to the dependence of fnrN expression on RpoN.

Bacterial Proteins↗
PubMed2001

Exercise for patients with fibromyalgia: risks versus benefits.

Although exercise in the form of stretching, strength maintenance, and aerobic conditioning is generally considered beneficial to patients with fibromyalgia (FM), there is no reliable evidence to explain why exercise should help alleviate the primary symptom of FM, namely pain. Study results are varied and do not provide a uniform consensus that exercise is beneficial or what type, intensity, or duration of exercise is best. Patients who suffer from exercise-induced pain often do not follow through with recommendations. Evidence-based prescriptions are usually inadequate because most are based on methods designed for persons without FM and, therefore, lack individualization. A mismatch between exercise intensity and level of conditioning may trigger a classic neuroendocrine stress reaction. This review considers the adverse and beneficial effects of exercise. It also provides a patient guide to exercise that takes into account the risks and benefits of exercise for persons with FM.

Exercise Therapy↗
PubMed1997

Hypothalamic-pituitary-insulin-like growth factor-I axis dysfunction in patients with fibromyalgia.

OBJECTIVE: To investigate the serum levels of insulin-like growth factor-I (IGF-I) in patients with fibromyalgia (FM) compared to healthy controls and patients with other rheumatic diseases, and to explore possible etiologic mechanisms of low IGF-I levels in patients with FM. METHODS: Five hundred patients with FM and 152 controls (74 healthy blood donors, 26 myofascial pain patients and 52 patients with other rheumatic diseases) were studied. All had measurements of acid extracted serum IGF-I. A subset of 90 patients with FM were evaluated for clinical features that might explain low IGF-I levels. Twenty-five patients with FM underwent growth hormone (GH) provocation testing with l-dopa and clonidine. RESULTS: The mean serum IGF-I level in patients with FM was 138 +/- 56 ng/ml and in controls 215 +/- 86 ng/ml (p = 0.00000000001). Low levels of IGF-I were not due to depression, tricyclic medications, nonsteroidal antiinflammatory drugs, poor aerobic conditioning, obesity, or pain level. Patients with focal myofascial pain syndromes had normal IGF-I levels (236 +/- 68), as did most patients with other rheumatic disorders, unless they had concomitant FM. Patients with FM with initially normal levels often had a rapid decline of IGF-I over 1 to 2 years. Most patients with FM with low IGF-I levels failed to secrete GH after stimulation with clonidine and l-dopa. CONCLUSION: Many, but not all, patients with FM have low levels of IGF-I that cannot be explained by clinical associations. These results suggest that low IGF-I levels in patients with FM are a secondary phenomenon due to hypothalamic-pituitary-GH axis dysfunction.

Adult↗
PubMed1997

Implications of socio-cultural contexts for the ethics of clinical trials.

BACKGROUND: Health technology assesment (HTA) requires scientifically rigorous experimentation involving patients as subjects. HTA itself is required so that treatment given to patients will be both effective and efficient; this requirement is itself ethical in nature. At the same time it is essential that the methods used in HTA are ethically sound. Most healthcare researchers agree that the most effective and soundest method for assessing treatments is the randomised controlled trial (RCT). However, some researchers believe that the RCT is unethical, either in essence, or for use in some forms of medical research and HTA. Furthermore, many patients seem unable to understand the principles and purposes of the RCT, a factor which is highly detrimental for the validity of informed consent. Informed consent is the key to the ethics of medical research, both in most theories and in all codes of research conduct. Many RCTs therefore risk being unethical in practice, even if ethical in principle. AIM OF REPORT: To survey the main objections to the RCT and its alternatives. To assess the philosophical and methodological basis of these objections, and of the methods recommended for addressing them. To identify areas where objections are founded in social or cultural factors normally overlooked in ethical argument about the RCT methodology. To identify alternative arguments or methods which might resolve ethical conflicts in this area. HOW THE RESEARCH WAS CONDUCTED: The methods used were adapted from systematic reviews in medicine. Systematic searches of Medline, Psychlit and Sociofile CD-ROM databases; hand-searches of the major journals in general medicine and surgery, medical ethics and philosophy; and searches of books were carried out. The literature survey was restricted to articles published or abstracted in English. A database of the most relevant and useful materials was compiled, and is accessible on the Internet (http://www.liv.ac.uk/sdthomps/page1.html). RESEARCH FINDINGS: UNDERSTANDING RCTS AND THEIR ALTERNATIVES: There is some evidence of difficulty in understanding the aims and methods of RCTs, and some disquiet about elements of the RCT methodologies. These objections are well known and much discussed, and concern the use of placebo, the continuation of trials after significant differentials in benefit or harm are apparent, and randomisation. CULTURAL OR RELIGIOUS OBJECTIONS: There was an absence of evidence of cultural or religious objections to randomisation, placebo or other kinds of controlled prospective trials. This most likely reflects an absence of research rather than absence of objections. (ABSTRACT TRUNCATED)

Cultural Diversity↗
PubMed1996

Group treatment of fibromyalgia: a 6 month outpatient program.

OBJECTIVE: To evaluate the impact of a 6 month group therapy program on the treatment of patients with fibromyalgia (FM). Since FM is a common problem in rheumatology practice, a program was designed to treat patients in a group setting using allied health professionals. METHODS: The FM group (15 to 25 patients) met once a week for 6 months. The average session lasted 90 min and consisted of formal lectures, group sessions emphasizing behavior modification, stress reduction techniques, strategies to improve fitness and flexibility and support sessions for spouses/significant others. The 2 major outcome measures were the fibromyalgia impact questionnaire (FIQ) and the total tender point score. Secondary outcome measures were the quality of life scale, questionnaires to assess coping strategies and attitudes to illness, an index of aerobic conditioning, flexibility, distance walked in 6 min., Beck depression and Beck anxiety questionnaires. Patients were followed 2 years and compared to a group of patients outside the program. RESULTS: Between 1989 and 1993 170 patients were evaluated and 104 patients completed the program. At the end of the 6 months 73 (70%) of patients had <11 tender points and FIQ improved 25%. Having a pain profile on MMPI or having major depression, did not predict poorer outcome. Thirty-three patients followed for 2 years after the program continue to show improvement. A control group of 29 patients who never entered the program showed no significant improvement. CONCLUSION: The group treatment of patients with FM in an outpatient setting shows promise; a more formal controlled study is needed to confirm this impression.

Adolescent↗
PubMed1994

Assessing depression in fibromyalgia patients.

PURPOSE: This study investigated the relationships among four methods of detecting depression in patients with fibromyalgia. METHODS: Data were obtained from 100 women (mean age 43 years) who had been diagnosed with fibromyalgia. Instruments included a computerized Diagnostic Interview Schedule (C-DIS), Beck Depression Inventory (BDI), an adjusted "disease-free" BDI (BDI-A), and Minnesota Multiphasic Personality Inventory depression subscale (MMPI-D). Chance-corrected concordance, sensitivity, specificity, and accuracy among the four methods were calculated. RESULTS: The C-DIS detected 22% and BDI-A 29% with current major depression. The BDI and MMPI-D yielded higher estimates of 55% of the 44%, respectively. Agreement on the diagnosis among the four methods was significantly greater than chance. When compared with the C-DIS, the BDI was the most sensitive instrument and the BDI-A most specific.

Adult↗
PubMed1993

Fibromyalgia and quality of life: a comparative analysis.

The quality of life of women with fibromyalgia was explored and compared to the quality of life of women with rheumatoid arthritis, osteoarthritis, permanent ostomies, chronic obstructive pulmonary disease, insulin dependent diabetes, and healthy controls. The women with fibromyalgia consistently scored among the lowest in all domains measured. These results suggest that fibromyalgia may adversely affect quality of life to an extent not previously recognized.

Adult↗
PubMed1992

Low levels of somatomedin C in patients with the fibromyalgia syndrome. A possible link between sleep and muscle pain.

OBJECTIVE: Fibromyalgia is a common syndrome of musculoskeletal pain and fatigue. Lacking distinctive tissue or laboratory correlations, it has often been considered a form of "psychogenic rheumatism." In the present study, the notion that the stage-4 sleep anomaly typically seen in the fibromyalgia syndrome may disrupt growth hormone secretion was tested. Because growth hormone has a very short half-life, serum levels of somatomedin C were measured; somatomedin C is the major mediator of growth hormone's anabolic actions and is a prerequisite for normal muscle homeostasis. METHODS: Serum levels of somatomedin C were measured in 70 female fibromyalgia patients and 55 healthy controls, using a peptide-specific radioimmunoassay. RESULTS: Significantly lower levels of somatomedin C were observed in the fibromyalgia patients compared with controls (mean +/- SD 124.7 +/- 47 ng/ml versus 175.2 +/- 60 ng/ml; P = 0.000001). These results could not be explained by concomitant therapy or by weight, and in a subset of 21 patients in whom this was investigated, there was no correlation with various indices of disease activity. CONCLUSION: These findings indicate that there is a distinctive disruption of the growth hormone-somatomedin C neuroendocrine axis in a majority of fibromyalgia patients. It is hypothesized that this abnormality may explain the link between disturbed sleep and predisposition to muscle pain.

Adult↗
PubMed1992

A comparison of pain perceptions in women with fibromyalgia and rheumatoid arthritis: relationship to depression and pain extent.

Two studies were conducted to characterize the pain of fibromyalgia syndrome (FMS); to compare it to rheumatoid arthritis (RA) pain; and to examine the relationships between depression, pain extent, and pain description. Two methods of administering the McGill Pain Questionnaire (MPQ) were used. When the MPQ was administered in the standard manner, FMS pain could not be distinguished from RA pain. When participants were allowed to select as many words from an adapted MPQ as they wished, significant differences in word choice emerged. Depression and pain extent were major predictors of group differences in the evaluation of pain. However, depression scores contributed only 50% of the explanation for the differences in pain extent, with group membership contributing the other 50%. These findings suggest that the character and extent of pain in FMS are at least partially due to peripheral sensory components and not simply centrally controlled pain amplification secondary to depression.

Adult↗
PubMed1992

Perforated ulcers related to smoking "crack" cocaine.

This article describes four patients with perforated gastroduodenal ulcers related to smoking "crack" cocaine. All patients came to the hospital with acute abdominal pain; only one patient had a history of ulcer disease. Only one patient had an elevated white blood cell count, and two patients had depressed white blood cell counts. In three patients, the x ray showed that pneumoperitoneum was present. Upon surgical exploration of the abdomen, all patients were found to have extensive peritoneal contamination. Operative repair consisted of omental patching with or without primary closure of the perforation. A history of cocaine smoking should be sought in patients with unexplained abdominal pain or pneumoperitoneum. In patients with acute abdominal pain and a history of smoking cocaine, a perforated gastroduodenal ulcer may be present, despite normal or low white blood cell counts and the lack of pneumoperitoneum on x-ray examination.

Adult↗
PubMed1991

Symptoms of Raynaud's syndrome in patients with fibromyalgia. A study utilizing the Nielsen test, digital photoplethysmography, and measurements of platelet alpha 2-adrenergic receptors.

Twenty-nine female patients with fibromyalgia were questioned about symptoms of cold intolerance and Raynaud's syndrome; objective documentation of cold-induced vasospasm was obtained by a Nielsen test. Twelve patients (41%) had abnormal Nielsen test results, and 11 patients (38%) had elevated levels of platelet alpha 2-adrenergic receptors. There was a positive correlation between the percentage of change in finger systolic pressure on cooling (Nielsen test) and the number of alpha 2-adrenergic receptors. There was poor correlation between Raynaud's syndrome symptoms and an abnormal Nielsen test result. Digital photoplethysmography showed a normal waveform in 2 of 3 patients. We hypothesize that a subgroup of patients with fibromyalgia syndrome have an up-regulation of alpha 2-adrenergic receptors as a cause of their exaggerated reaction to cold.

Adult↗
PubMed1991

Fibrin glue sealing of pancreatic injuries, resections, and anastomoses.

Fibrin glue made with highly concentrated human fibrinogen and clotting factors was evaluated as a means of preventing pancreatic fistulas in 15 patients operated on for traumatic and nontraumatic conditions. Fibrin glue was applied directly to penetrating pancreatic injuries, pancreatic suture and staple lines in patients treated by partial resection, and pancreaticointestinal anastomoses. Postoperatively, no patient developed pancreatic fistulas, pancreatic abscesses, or pseudocysts. Fibrin glue sealing of pancreatic injuries, resections, and anastomoses may aid in preventing fistulas after pancreatic surgery. Additional potential uses include the sealing of pancreatic biopsy sites and occlusion of the pancreatic duct in pancreatic transplantation.

Anastomosis, Surgical↗
PubMed1991

The fibromyalgia impact questionnaire: development and validation.

An instrument has been developed to assess the current health status of women with the fibromyalgia syndrome. The Fibromyalgia Impact Questionnaire (FIQ) is a brief 10-item, self-administered instrument that measures physical functioning, work status, depression, anxiety, sleep, pain, stiffness, fatigue, and well being. We describe its development and validation. This initial assessment indicates that the FIQ has sufficient evidence of reliability and validity to warrant further testing in both research and clinical situations.

Adult↗
PubMed1991

Spraying of aerosolized fibrin glue in the treatment of nonsuturable hemorrhage.

In the present report, the authors describe the use of aerosolized fibrin glue (FG) to achieve hemostasis in patients with nonsuturable hemorrhage. The multicomponent FG was sprayed on bleeding tissues with a dual chamber spray head that allowed simultaneous application and mixing of fibrinogen and thrombin on the tissue surface. Sterile propellant gas was passed through tubing to the spray head and independently controlled, allowing for drying of the tissue surface immediately before FG application. This technique was found to be effective in achieving hemostasis of parenchymal organs, retroperitoneal surfaces, and skin graft donor sites. Additional potential applications of this technique include the control of hemorrhage from mediastinal and pleural surfaces.

Aerosols↗
PubMed1990

Techniques of splenic preservation using fibrin glue.

Fibrin glue (FG) was used to achieve hemostasis of 16 splenic injuries in 14 patients. The etiologies of injury included five gunshot wounds, two stab wounds, four iatrogenic injuries, and five patients with blunt splenic trauma. The intraoperative blood loss averaged 1.8 +/- 2.4 (SD) liters and patients were transfused 3 +/- 2 units of blood perioperatively. The amount of FG required to achieve splenic hemostasis averaged 11 +/- 8 ml and varied directly with the grade of injury. One patient with a splenic hilar vascular injury (Grade V) underwent splenectomy following failure to achieve complete hemostasis despite the use of 25 ml of FG. All other splenic injuries were successfully managed using less than 25 ml of FG. Postoperative computerized tomographic (CT) scanning, performed in ten patients, was negative for rebleeding or abscess formation. The overall splenic salvage rate was 86%. FG was effective in achieving hemostasis of both superficial and deep splenic injuries. Its use as an adjunct in trauma surgery should result in increased splenic salvage rates compared with that obtained using conventional surgical techniques.

Adult↗
PubMed1989

Aerobic fitness in patients with fibrositis. A controlled study of respiratory gas exchange and 133xenon clearance from exercising muscle.

Aerobic fitness was evaluated in 25 women with fibrositis, by having them exercise to volitional exhaustion on an electronically braked cycle ergometer. Compared with published standards, greater than 80% of the fibrositis patients were not physically fit, as assessed by maximal oxygen uptake. Compared with matched sedentary controls, fibrositis patients accurately perceived their level of exertion in relation to oxygen consumption and attained a similar level of lactic acidosis, as assessed by their respiratory quotient and ventilatory threshold. Exercising muscle blood flow was estimated by 133xenon clearance in a subgroup of 16 fibrositis patients and compared with that in 16 matched sedentary controls; the fibrositis patients exhibited reduced 133xenon clearance. These results indicate a need to include aerobic fitness as a matched variable in future controlled studies of fibrositis and suggest that the "detraining phenomenon" may be of relevance to the etiopathogenesis of the disease.

Adult↗