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Biomedical subjects

S Lamb

Publications and source records attributed to S Lamb.

At least 19 recordsLinked to original sources
PubMed1997

Cellular mechanisms of cyclic nucleotide-induced vasorelaxation.

PURPOSE: Endothelial-derived vasorelaxants such as prostacyclin and nitric oxide (NO) induce vascular smooth muscle relaxation through activation of cyclic nucleotide-dependent cellular signalling pathways. However, the specific events that lead to dissociation of actin and myosin and relaxation are not known. The purpose of this investigation was to determine the late phase signaling events that modulate vascular smooth muscle relaxation. METHODS: Fresh bovine carotid artery smooth muscle (BCASM) contractile responses were determined in a muscle bath under Ca(2+)-containing and Ca(2+)-free conditions. Physiologic responses were correlated with phosphorylation events using whole cell phosphorylation and two-dimensional gel electrophoresis. RESULTS: Cyclic nucleotide-dependent vasorelaxation can occur without detectable changes in intracellular Ca2+ concentrations. However, vascular smooth muscles that had been precontracted with the phosphatase inhibitor calyculin were refractory to relaxation. Vascular smooth muscle relaxation was associated with an increase in the phosphorylation of two 20 kDa proteins under Ca(2+)-containing and Ca(2+)-free conditions. CONCLUSIONS: These results suggest that Ca(2+)-independent mechanisms may also modulate vascular smooth muscle relaxation. Two possible late phase signaling mechanisms include phosphatase activation and an increase in the phosphorylation of two 20 kDa phosphoproteins.

Animals↗
PubMed1996

Nitric oxide is an autocrine feedback inhibitor of vascular smooth muscle contraction.

BACKGROUND: Substances that increase intracellular calcium ([Ca2+]i), such as potassium chloride and serotonin, are known to induce vascular smooth muscle (VSM) contraction. One form of nitric oxide synthase, which converts L-arginine to nitric oxide, exists as a Ca(2+)-calmodulin dependent enzyme. The objective of this study was to determine whether agonists that induce VSM contraction by increasing [Ca2+]i might also activate Ca(2+)-calmodulin dependent nitric oxide synthase in VSM. METHODS: Strips of bovine carotid arterial smooth muscle denuded of endothelium were equilibrated in a physiologic muscle bath. A maximal contractile response to high extracellular potassium chloride and serotonin was established. The strips were then preincubated with NG-monomethyl-L-arginine (L-NMMA), a structural analog of L-arginine and specific inhibitor of nitric oxide synthase, and again treated with either KCl or 5-hydroxytryptamine. RESULTS: The contractile responses of muscle strips to KCl or 5-hydroxytryptamine were significantly greater in muscle strips pretreated with L-NMMA than responses in the absence of L-NMMA (p < 0.02, Student's t test). To determine whether this response was Ca2+ dependent, phorbolester-induced contractions in Ca(2+)-free conditions were examined. No difference was noted in the magnitude of Ca(2+)-free, phorbol ester-induced contractions in the presence and absence of L-NMMA. CONCLUSIONS: These data thus suggest that Ca(2+)-calmodulin dependent nitric oxide synthase is functionally present in VSM and may function as an autocrine regulatory mechanism of VSM contraction.

Animals↗
PubMed1996

Data initiatives: HEDIS and the New England Business Coalition.

The New England Business Coalition is a group of 15 health maintenance organizations, large employers, and health care purchasers operating in the New England area. Formally launched in 1994, the coalition's mission is to standardize health care reporting, improve quality, and allow for comparison of managed health care plans for the participating organizations. The National Committee for Quality Assurance (NCQA) and its measurement instrument, the Health Plan Employer Data Information Set (HEDIS) became involved in the coalition's reporting project in 1992 to help the participating plans fulfill their mission of standardization, quality improvement, and comparative evaluation. In the past 5 years, HEDIS has undergone change and development to meet the needs of both health care plans and purchasers who use the HEDIS information to make decisions about health care for employers. Changes enacted within HEDIS have been brought about with the input of HEDIS users such as the New England Business Coalition, a pilot report card project, and a nationally based HEDIS users group. Future enhancements to HEDIS will result in added value for HEDIS users as development and change continue to meet the evolving needs of plans and purchasers.

Databases, Factual↗
PubMed1993

Competency assessment of primary care physicians as part of a peer review program.

OBJECTIVE: To design and test a program that assesses clinical competence as a second stage in a peer review process and to determine the program's reliability. DESIGN AND SETTING: A three-cohort study of Ontario primary care physicians. PARTICIPANTS: Reference physicians (n = 26) randomly drawn from the Hamilton, Ontario, area; volunteer, self-referred physicians (n = 20); and physicians referred by the licensing body (n = 37) as a result of a disciplinary hearing or peer review. MAIN OUTCOME MEASURES: Standardized patients, structured oral examinations, chart-stimulated recall, objective structured clinical examination, and multiple-choice examination. RESULTS: Test reliability was high, ranging from 0.73 to 0.91, and all tests discriminated among subgroups. Demographic variables relating to the final category were age, Canadian or foreign graduates, and whether or not participants were certified in family medicine. CONCLUSIONS: The study demonstrated the feasibility, reliability, and validity of a multicomponent examination in the peer review process.

Adult↗
PubMed1991

Acts without agents: an analysis of linguistic avoidance in journal articles on men who batter women.

Articles on abuse of women by men were surveyed in eleven journals across four disciplines. Introductory sections from 46 articles were coded for linguistic choices--such as use of the passive voice, nominalization, and diffuse terminology--that obscure the attribution of responsibility. In half or more of the references to abuse, sentence structure and language were deemed problematic, with diffusion of responsibility the most frequent strategy of avoidance. Professional and gender biases were found, with articles by social workers less likely, and articles with male authors more likely, to contain problematic writing.

Family Therapy↗
PubMed1991

Radiosurgery: a nursing perspective.

The term radiosurgery, originally applied to three-dimensional stereotactic irradiation of small intracranial targets with low-energy x-rays, has more recently been applied to widely differing techniques and radiation sources. These include gamma units using cobalt-60; beams of protons, helium ions and neutrons; and modified cobalt-60 or linear accelerator units. These techniques allow delivery of a high dose of radiation in a single fraction to a small and well-defined intracranial volume, without delivering significant radiation to adjacent normal tissue. The most usual targets for radiosurgery are arteriovenous malformations. It is occasionally used for acoustic neuromas and primary or metastatic brain malignancies as well. Although radiosurgery is not a new procedure, its use is becoming more widespread. Nurses, as critical members of radiosurgery teams, must be informed about all aspects of the procedures and associated nursing care skills.

Brain Neoplasms↗
PubMed1988

Pediatric Symptom Checklist: screening school-age children for psychosocial dysfunction.

The Pediatric Symptom Checklist (PSC) is a 35-item screening questionnaire that is completed by parents and designed to help pediatricians in outpatient practice identify school-age children with difficulties in psychosocial functioning. The current study assessed the validity of the PSC by screening 300 children in two pediatric practices, a middle-class group practice and an urban health maintenance organization. Validity was established by comparing the results of PSC screening of 48 children with in-depth interview assessments and pediatricians' ratings. Results indicate that the PSC has a specificity of 0.68 and a sensitivity of 0.95. The screening process was well accepted by parents and pediatricians. Several children whose pediatricians' ratings had indicated adequate functioning were identified by the PSC as having substantial psychosocial dysfunction and requiring further evaluation.

Child↗
PubMed1988

Developing reliable assessment in case-managed geriatric long term care programs.

Analyses of frail elderly populations and their service needs are increasingly important in shaping future policies for long term care (LTC) financing and service delivery. Because assessment information on elderly LTC clients generates essential data bases on programs and the population, it is important that the data be reliable. This article describes a method for obtaining reliable assessment data in multisite programs involving many clinical assessors. Regular reliability checks showed marked improvement over time and generally high levels of interrater reliability.

Activities of Daily Living↗
PubMed1987

Pulsed Doppler frequency and carotid stenosis.

Two hundred and forty-two internal carotid arteries (ICA) were evaluated by independently interpreted arteriography and pulsed Doppler spectrum analysis using ultrasonic arteriography to evaluate the ability of peak systolic frequency (PSF) to predict the degree of internal carotid stenosis. Mean PSF in the 129 (53.3%) high grade ICA stenoses of greater than 50% diameter reduction was 6.55 +/- 0.14 (SEM) khz, while mean PSF in the 113 (46.7%) low grade (less than 50% diameter reduction) stenoses was 3.38 +/- 0.12 (SEM) kHz (P less than 0.0001). Receiver-operator characteristic (ROC) analysis revealed that PSFs of 4.5 kHz (sensitivity 87%, specificity 88%) and 5.0 kHz (sensitivity 83%, specificity 93%) were best for identifying a 50% diameter stenosis. Positive predictive value of 5.0 kHz was 93% (107/115) and negative predictive value was 82.7% (105/127). Linear regression analysis of PSF in kHz versus percentage diameter reduction yielded the equation: % stenosis = 10.7 (PSF) - 4.1 (r = 0.76). A nonlinear equation was also derived: % stenosis = 61.9 - 33.5 (PSF) + 8.7 (PSF)2 - 0.5 (PSF)3 (r = 0.77). Based on this analysis peak systolic frequency criteria measured by pulsed Doppler spectrum analysis appear to be useful for distinguishing high grade from low grade stenoses. Both the linear and nonlinear equations further suggest that PSF can more precisely quantitate the degree of ICA luminal narrowing.

Carotid Artery Diseases↗
PubMed1987

Brachytherapy of recurrent tumors of the skull base and spine with iodine-125 sources.

Thirteen patients with recurrent, previously irradiated tumors of the skull base or spine were reirradiated with 125I sources implanted interstitially using microsurgical or stereotactic techniques. Patients harbored difficult, end-stage recurrences of chordoma, meningioma, malignant meningioma, fibrosarcoma, invasive pituitary adenoma, and malignant schwannoma. In two other patients with malignant meningioma, the dose of external radiation was augmented by implanting 125I sources during the initial operation for excision of the lesion or at a separate surgical procedure after conventional teletherapy. Microsurgical implantation of 125I sources into basal tumors was limited by the difficulties inherent in operating in this region; it is not possible to visualize the entire tumor that requires implantation. Three of five chordomas stabilized or regressed; these patients probably benefited from the procedure. Two patients with recurrent malignant meningiomas had long term remission after interstitial brachytherapy. Interstitial 125I brachytherapy for recurrent tumors at the base of skull or adjacent to the spine can be more successful only if more aggressive surgical exposures of these regions are attempted. Implantation of sources for a "boost" dose, either microsurgically during the initial surgical resection of the lesion before conventional teletherapy or stereotactically after conventional teletherapy, may be a valuable adjunct to external irradiation for the control of potentially devastating tumors (such as chordomas and malignant meningiomas) before they recur with the severe consequences seen in the patients reported here.

Adenoma↗
PubMed1987

Treatment of chronic pain by deep brain stimulation: long term follow-up and review of the literature.

Since the senior author's (J.E.A.) first report in 1972 of the use of deep brain stimulation (DBS) to control chronic pain, electrodes for DBS have been implanted in 141 patients. Of reported series, this one has the largest number of patients and the longest period of follow-up. The mean age of patients in this study was 51.2 years. The mean length of follow-up was 80 months. Patients had experienced pain for a mean period of 65 months before DBS was attempted; all patients had exhausted other medical and surgical therapies. For the purposes of this study, pain states were characterized as being either nociceptive or deafferentation in nature. Nociceptive pain was treated primarily by stimulation of the periaqueductal or periventricular gray, and deafferentation pain was treated primarily by stimulation of the sensory thalamus. Eighty-four patients were treated for deafferentation pain, which included the thalamic pain syndrome (25 cases), peripheral neuropathic pain (16 cases), anesthesia dolorosa (12 cases), paraplegia pain (11 cases), postcordotomy dyesthesia (5 cases), phantom limb pain (5 cases), thoracic neuralgia (4 cases), and miscellaneous pain states (6 cases). We treated 57 patients with nociceptive pain states, 51 for low back and skeletal pain and 6 for pain from the invasion of cancer. Initial relief of pain was obtained by 83 patients (59%). After the mean follow-up period of 80 months, 42 patients (31%) continued to obtain significant pain relief with DBS. Some pain states, particularly anesthesia dolorosa and paraplegia pain, did not seem to respond to DBS. Major complications of therapy included wound infection (12%) and intracranial hemorrhage (3.5%); there was one death in the series (0.7%).(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1986

Quality control aspects of pulmonary function testing in the Multiple Risk Factor Intervention Trial.

Pulmonary function testing was used in MRFIT to monitor the presence of airways disease and to assess changes in pulmonary function over time. The pulmonary function indices that were measured were FEV1, FVC, and MMEF, (FEF25-75). Quality control of technician training, equipment maintenance, data collection, and data measurement were essential to ensure that results, over time and from various clinics, could be compared. Based on the MRFIT experience, it is strongly recommended that centralized training in testing techniques and spirometer maintenance take place before a clinical trial begins, and periodically throughout a trial. Such training, combined with quality control follow-up, should prevent the loss of data due to inadequate spirometer maintenance and invalid testing procedures.

Allied Health Personnel↗