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Biomedical subjects

R Hamer

Publications and source records attributed to R Hamer.

At least 19 recordsLinked to original sources
PubMed2006

SPINE bioinformatics and data-management aspects of high-throughput structural biology.

SPINE (Structural Proteomics In Europe) was established in 2002 as an integrated research project to develop new methods and technologies for high-throughput structural biology. Development areas were broken down into workpackages and this article gives an overview of ongoing activity in the bioinformatics workpackage. Developments cover target selection, target registration, wet and dry laboratory data management and structure annotation as they pertain to high-throughput studies. Some individual projects and developments are discussed in detail, while those that are covered elsewhere in this issue are treated more briefly. In particular, this overview focuses on the infrastructure of the software that allows the experimentalist to move projects through different areas that are crucial to high-throughput studies, leading to the collation of large data sets which are managed and eventually archived and/or deposited.

Computational Biology↗
PubMed2006

Honing the in silico toolkit for detecting protein disorder.

Not all proteins form well defined three-dimensional structures in their native states. Some amino-acid sequences appear to strongly favour the disordered state, whereas some can apparently transition between disordered and ordered states under the influence of changes in the biological environment, thereby playing an important role in processes such as signalling. Although important biologically, for the structural biologist disordered regions of proteins can be disastrous even preventing successful structure determination. The accurate prediction of disorder is therefore important, not least for directing the design of expression constructs so as to maximize the chances of successful structure determination. Such design criteria have become integral to the construct-design strategies of laboratories within the Structural Proteomics In Europe (SPINE) consortium. This paper assesses the current state of the art in disorder prediction in terms of prediction reliability and considers how best to use these methods to guide construct design. Finally, it presents a brief discussion as to how methods of prediction might be improved in the future.

Algorithms↗
PubMed2001

Determinants of information technology outsourcing among health maintenance organizations.

We analyze the determinants of HMO information technology outsourcing using two studies. Study 1 examines the effect of asset specificity on outsourcing for development and operation activities, using HMO specific fixed effects to control for differences between HMOs. Study 2 regresses the HMO specific fixed effects from Study 1, which measure an HMO's propensity to outsource, on HMO characteristics. The data comes from a 1995 InterStudy survey about information technology organization of HMOs. While HMOs split roughly equally in outsourcing information technology development activities, they are extremely unlikely to outsource the day-to-day operation of information systems. The greater an HMO's information technology capability and the complexity of information systems supported, the less likely is an HMO to outsource. While HMOs less than two years old, for-profit HMOs, local or Blue Cross-affiliated HMOs, and mixed HMOs are more likely to outsource, federally qualified HMOs are less likely to outsource. Policy and managerial implications for the adoption and diffusion of new ways of organizing information technology, such as application service providers (ASPs), are discussed.

Decision Making, Organizational↗
PubMed2000

The diffusion of information technology among health maintenance organizations.

This article examines the information technology functions, staffing and cost, services provided, and advanced technologies among health maintenance organizations (HMOs) using a national sample of HMOs from mid-1995. HMOs have a well-developed capability to use data from administrative functions, such as claims processing. Nationally affiliated HMOs and HMOs in markets with greater HMO penetration support more IT functions. Relatively little work has been completed integrating clinical with administrative systems.

Data Collection↗
PubMed2000

Controlled human exposure to methyl tertiary butyl ether in gasoline: symptoms, psychophysiologic and neurobehavioral responses of self-reported sensitive persons.

The 1990 Clean Air Act mandated oxygenation of gasoline in regions where carbon monoxide standards were not met. To achieve this standard, methyl tertiary butyl ether (MTBE) was increased to 15% by volume during winter months in many locations. Subsequent to the increase of MTBE in gasoline, commuters reported increases in symptoms such as headache, nausea, and eye, nose, and throat irritation. The present study compared 12 individuals selected based on self-report of symptoms (self-reported sensitives; SRSs) associated with MTBE to 19 controls without self-reported sensitivities. In a double-blind, repeated measures, controlled exposure, subjects were exposed for 15 min to clean air, gasoline, gasoline with 11% MTBE, and gasoline with 15% MTBE. Symptoms, odor ratings, neurobehavioral performance on a task of driving simulation, and psychophysiologic responses (heart and respiration rate, end-tidal CO(2), finger pulse volume, electromyograph, finger temperature) were measured before, during, and immediately after exposure. Relative to controls, SRSs reported significantly more total symptoms when exposed to gasoline with 15% MTBE than when exposed to gasoline with 11% MTBE or to clean air. However, these differences in symptoms were not accompanied by significant differences in neurobehavioral performance or psychophysiologic responses. No significant differences in symptoms or neurobehavioral or psychophysiologic responses were observed when exposure to gasoline with 11% MTBE was compared to clean air or to gasoline. Thus, the present study, although showing increased total symptoms among SRSs when exposed to gasoline with 15% MTBE, did not support a dose-response relationship for MTBE exposure nor the symptom specificity associated with MTBE in epidemiologic studies.

Adult↗
PubMed1998

Life after infertility treatment: a long-term investigation of marital and sexual function.

After leaving in-vitro fertilization (IVF) treatment, both successful and unsuccessful women are generally lost to follow-up. In order to assess overall life satisfaction as well as marital and sexual adjustment after the completion of infertility treatment, three groups of women were studied: group 1 (n = 41), successful IVF women; group 2 (n = 16), unsuccessful IVF women who adopted; and group 3 (n = 18), unsuccessful IVF women who remained childless. All women who had completed a minimum of three IVF cycles between the years 1982 and 1993 were invited to participate in a 'life after infertility' follow-up study. Those who agreed were mailed a lengthy questionnaire which included questions about their reproductive history and infertility treatment, the impact of infertility on their marital and sexual relationship and their final thoughts about treatment. Four standardized questionnaires were also administered. Results revealed that women who became biological mothers through IVF were significantly more satisfied with their lives than women who were unsuccessful in IVF and remained childless (F = 8.62, P < 0.001). Childless women reported that infertility had exerted a significantly greater negative impact on their marriages than that reported by the other two groups. There were no significant differences, however, between the three groups on the standardized measures of marital and sexual satisfaction.

Female↗
PubMed1998

Trust me: technical and institutional determinants of health maintenance organizations shifting risk to physicians.

This paper examines the factors that influence a Health Maintenance Organization (HMO) to shift risk to doctors through an incentive arrangement called capitation, where physicians are paid a fixed amount per patient for a period of time for any and all medical services required by the patient. Multispecialty-medical-group (Group) HMOs are more likely to shift risk than Independent Physician Associations (IPA) HMOs. Within IPA HMOs, larger enrollment per physician is positively associated with more risk shifting. We find that institutional factors signaling legitimacy play an important role in determining risk shifting. For-profit HMOs are less likely to shift risk, which we interpret as reflecting consumer distrust of for-profit HMOs. However, for-profit HMOs that are federally qualified, which we interpret as a signal of legitimacy, are more likely to shift risk.

Capitation Fee↗
PubMed1997

Respiratory sinus arrhythmia versus neck/trapezius EMG and incentive inspirometry biofeedback for asthma: a pilot study.

This pilot study compared biofeedback to increase respiratory sinus arrhythmia (RSA) with EMG and incentive inspirometry biofeedback in asthmatic adults. A three-group design (Waiting List Control n = 5, RSA biofeedback n = 6, and EMG biofeedback n = 6) was used. Six sessions of training were given in each of the biofeedback groups. In each of three testing sessions, five min. of respiratory resistance and EKG were obtained before and after a 20-min biofeedback session. Additional five-min epochs of data were collected at the beginning and end of the biofeedback period (or, in the control group, self-relaxation). Decreases in respiratory impedance occurred only in the RSA biofeedback group. Traub-Hering-Mayer (THM) waves (.03-.12 Hz) in heart period increased significantly in amplitude during RSA biofeedback. Subjects did not report significantly more relaxation during EMG or RSA biofeedback than during the control condition. However, decreases in pulmonary impedance, across groups, were associated with increases in relaxation. The results are consistent with Vaschillo's theory that RSA biofeedback exercises homeostatic autonomic reflex mechanisms through increasing the amplitude of cardiac oscillations. However, deep breathing during RSA biofeedback is a possible alternate explanation.

Adolescent↗
PubMed1997

Serotonin reuptake inhibitor-induced sexual dysfunction and its treatment: a large-scale retrospective study of 596 psychiatric outpatients.

In the present study, a large-scale retrospective case review was undertaken to assess the incidence and type of sexual dysfunctions associated with serotonin reuptake inhibitor (SRI) therapy, in addition to the effects of three pharmacological antidotes (yohimbine, amantadine, cyproheptadine) on SRI-induced sexual dysfunctions. A retrospective chart review was conducted on 596 patients treated with SRIs in an outpatient psychiatric practice between July 1991 and September 1994. Patients who reported new-onset sexual dysfunction during this time were categorized as having SRI-induced sexual dysfunctions. Sexual difficulties were characterized by type and duration, and the background characteristics and psychiatric diagnoses of all patients were recorded. Psychiatric outcome and sexual functioning at follow-up were independently assessed by a single psychiatrist by means of a 4-point rating scale. Sexual dysfunction symptoms were clearly associated with SRI administration in 97 (16.3%) cases. The most common problems reported were orgasmic delay or anorgasmia and hypoactive sexual desire. Sexual difficulties were more frequent among men (23.4%) and married patients of both sexes (22.3%), whereas psychiatric diagnosis and type of SRI were unrelated to the occurrence of sexual problems. Of the patients with sexual dysfunction, 45 (46.4%) opted for a trial of antidote therapy with yohimbine, amantadine, or cyproheptadine. All three antidotes were found to be safe and relatively effective, although yohimbine was significantly more effective than amantadine or cyproheptadine in reversing SRI-induced sexual dysfunction.

Adult↗
PubMed1997

When exercise goes awry: exertional rhabdomyolysis.

Exertional rhabdomyolysis occurs when exercise, often of the eccentric type, damages myofibrils and sarcolemma, with release of the enzyme creatine kinase and pigmented myoglobin into the serum. Severe muscle soreness and dark urine are the hallmark symptoms, and renal failure may develop. Formerly a disease of military recruits, it is now seen more often in exercisers. Although a genetic trait may predispose, the illness probably can be avoided by common sense behavior such as a gradual increase in exercise intensity, proper hydration before, during, and after exercise, and avoiding exercise in extremely hot or humid environments.

Adult↗
PubMed1997

HMO financial arrangements with rural physicians.

The growth of managed care in general suggests that a substantially larger number of rural primary care physicians will be asked to enter into risk-bearing contracts with Health Maintenance Organizations (HMOs) in the near future. This article describes the different types of payment and risk-sharing arrangements that exist between HMOs and primary care physicians and presents survey data relating to their prevalence in rural areas. Also, it describes in detail the payment arrangements used by four HMOs that contract with rural primary care physicians. The concluding discussion highlights policy issues regarding risk-sharing arrangements that are especially pertinent in rural settings.

Capitation Fee↗
PubMed1997

The Lie/Bet Questionnaire for screening pathological gamblers.

A 2-item questionnaire was derived from 10 DSM-IV criteria for pathological gambling. Subjects were 362 men, 191 classified as pathological gamblers and 171 as nonproblem-gambling controls. The two items were significant in sensitivity and negative predictive value and significant in specificity and positive predictive value.

Adolescent↗
PubMed1997

Study results show decline in HMO operating margins.

In the early 1990s, virtually all HMOs reported healthy profits, especially in markets with low managed care penetration. However, a recent survey has revealed that HMO operating margins experienced sharp declines in 1995. Some reasons for these declines include: more competition as the healthcare marketplace has become more saturated with HMOs; aggressive price negotiations by employers; and rising HMO medical and administrative expenses. The study also revealed that all types of HMOs experienced operating margin declines, demonstrating that organizational structure was an unlikely contributing factor.

Contract Services↗
PubMed1992

An enzyme-linked immunosorbent assay (ELISA) for von Willebrand factor antigen (vWf-Ag) in canine plasma.

A quantitative enzyme-linked immunosorbent assay (ELISA) has been developed to measure canine von Willebrand factor antigen (vWf-Ag) in plasma of the dog. A vWf-Ag antiserum was raised in rabbits and purified by preabsorption with the low molecular weight vWf-Ag-deficient fraction of canine cryoprecipitate, followed by affinity chromatography on protein-A Sepharose. The rabbit anticanine vWf-Ag IgG was used to bind the vWf-Ag of the test plasmas to the solid phase and to prepare the enzyme-antibody conjugate in ELISA. Normal rat serum was used as blocking agent. The standard curve was linear (r2 greater than 0.98) and reproducible after logit-log transformation. The interassay coefficient of variation (CV) in test plasmas with various vWf-Ag concentrations was never greater than 7.7%. Assayed values in dilutions of pooled normal canine plasma added to canine vWf-Ag-deficient plasma were linear between 0 and 100% (r2 = 0.99) and indicated excellent analytical recovery of vWf-Ag. In 18 dogs with various internal diseases, including von Willebrand's disease and haemophilia A, the coefficient of correlation between the results of the ELISA and those of electroimmunodiffusion (EID) was 0.93.

Animals↗
PubMed1989

How is the NaCl signal transmitted in NaCl-induced hypertension?

Is the NaCl signal perceived as a small increase in the concentration of NaCl in extracellular fluid? We used 8 g NaCl/100 g soluble nutrients and fed only a hypertonic (1.4% NaCl) or a hypotonic (0.45% NaCl) drink to Dahl salt-sensitive (DS) rats. After 12 weeks, 11 rats receiving the hypertonic drink had a mean blood pressure of 195 mm Hg versus 195 mm Hg in 12 rats receiving the hypotonic drink. Thus, the high-NaCl signal seems unrelated to a higher NaCl concentration in extracellular fluid, thereby suggesting volume signals. Most volume controls are near the third brain ventricle (3V). As a working hypothesis, high dietary NaCl may swell the tissues surrounding 3V, which is slitlike. Such swelling would partially close the upper part of the slit and cause ependymal cells and nerve fibers on opposite walls to touch, possibly leading to hypertension in susceptible humans or rats. To test this, we stereotaxically blocked the aqueduct with inert silicone to produce hydrocephalus of 3V in DS rats and thus prevent ependymal cells and nerve fibers from touching. After blocking or sham-blocking the aqueduct, either a 6% NaCl diet or a 0.23% NaCl diet was started. Intra-arterial blood pressure was taken after 6 weeks. A group of 28 sham-blocked rats and a group of 29 blocked rats, all fed a 0.23% low NaCl diet, had equal blood pressures averaging 130 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Changes in the pH and volume of gastric contents during pregnancy and labor].

We measured the volume and pH of gastric contents of 97 patients after induction of anaesthesia. The patients were divided into 3 groups: group I (N = 39): elective cesarean section, group II (N = 44): elective gynecological surgery, group III (N = 14): emergency cesarean section. The study was undertaken to ascertain whether pregnancy and labour would modify the volume and mean pH of gastric contents. Mean pH of gastric contents in the 3 groups were respectively 2.57; +/- 0.23; 3.21 +/- 0.29; and 2.77 +/- 0.42. There were no significant differences between the groups: Pregnancy and labour do not influence gastric pH. As far as gastric volume is concerned there is a significant difference between Group I and III (p less than 0.01) and Group II and III (p less than 0.01).

Anesthesia, General↗