Biomedical subjects

R H Peters

Publications and source records attributed to R H Peters.

At least 19 recordsLinked to original sources

PubMed2001

The influence of seam height on lost-time injury and fatality rates at small underground bituminous coal mines.

Due to variations in the thickness of U.S. coal seams, there is great variability in the height of the roof where underground miners work. Restrictions imposed by low seam heights have important safety consequences. As the height of their workplace decreases, miners must stoop, duck walk, or crawl, and their vision, posture, and mobility become increasingly restricted. Low seam height also places important restrictions on the design of mobile equipment and other mining machinery. Using the employment and injury data reported to the Mine Safety and Health Administration (MSHA) from 1990 to 1996, small underground bituminous coal mines with less than 50 employees were stratified by average coal seam height according to the following categories: low (< or =42"), medium (43"-60"), and high (> or =61"). Injury rates for both nonfatal days lost and fatality cases were examined by seam height and leading type of injury incidents. The leading types of incidents associated with fatalities were roof falls and powered haulage equipment. In comparison to high-seam mines, miners working in low or medium seams are at higher risk of being killed by powered haulage equipment, roof bolting machines, and falls of unsupported roof. The leading types of incidents associated with nonfatal injuries were handling materials and powered haulage. As mining height decreases, miners are at increasingly higher risk of having a nonfatal injury from incidents involving roof bolting machines, load-haul-dump equipment, personnel carriers, and powered haulage conveyors. As mining height increases, miners are at increasingly higher risk of having a nonfatal injury from slips and falls and incidents involving shuttle cars and roof and rib falls. Knee injuries are a particularly severe problem in low-seam mines. The rate of injuries to miners while crawling or kneeling is 10 times higher in low seams than in high seams.

Absenteeism↗

PubMed2000

Effectiveness of screening instruments in detecting substance use disorders among prisoners.

This study examined the effectiveness of several screening instruments in detecting substance use disorders among prison inmates. A sample of 400 male inmates were administered eight different substance abuse screening instruments and the Structured Clinical Interview for DSM-IV (SCID-IV), Version 2.0, Substance Abuse Disorders module. The latter was used as a diagnostic criterion measure to determine the presence of substance use disorders. Based on positive predictive value, sensitivity, and overall accuracy, the Texas Christian University Drug Screen, the Simple Screening Instrument, and a combined instrument-Alcohol Dependence Scale/Addiction Severity Index-Drug Use section were found to be the most effective in identifying substance abuse and dependence disorders.

Adolescent↗

PubMed2000

Development of substance abuse problems among drug-involved offenders. Evidence for the telescoping effect.

PURPOSE: The present study was designed to evaluate gender differences in the development of substance abuse disorders among drug-involved offenders and to determine whether women in this population exhibit a telescoping effect (i.e., acceleration in the progression from substance use to substance abuse), which has been observed in other setting. METHOD: Participants consisted of 160 polysubstance-abusing individuals (118 men, 42 women) who were admitted to two Florida drug court programs. Data were obtained from the Addiction Severity Index, intake interviews, and archival court records. RESULTS: Female and male offenders differed significantly in the developmental trajectory of their addiction. Women offenders initiated alcohol and marijuana use significantly later in life than their male cohorts but began using cocaine earlier in the course of their addiction. Women also reported more problems related to cocaine use and significantly more prior treatment episodes. Women were found to have a shorter latency from first use of cocaine to cocaine abuse. Findings are consistent with those of previous studies examining gender differences among individuals referred for substance abuse treatment. Future directions for research and implications for treatment planning are discussed.

Analysis of Variance↗

PubMed1998

Low prevalence of coronary artery spasm in patients with normal coronary angiograms and unexplained ventricular fibrillation.

AIMS: The aetiology of ventricular fibrillation in patients without identifiable structural heart disease is unknown. Recently, high prevalence of silent ischaemia due to coronary artery spasm has been reported in such patients. However, in at least one report, all patients had non-critical coronary artery lesions. Identification of coronary artery spasm as the underlying aetiology of ventricular fibrillation has important therapeutic implications. METHODS AND RESULTS: We performed ergonovine provocation tests in 18 patients (14 males, and four females; mean age, 36 years) with documented ventricular fibrillation in the absence of identifiable structural heart disease who had undergone aborted sudden death. In group I (n = 7) ergonovine provocation tests were performed at a mean interval of 31 months (range 21-42 months) after the index episode. These patients had already received an implantable cardioverter defibrillator, after failed electrophysiologically guided antiarrhythmic therapy. In group II (n = 11) the ergonovine provocation test was performed prospectively as part of the diagnostic evaluation. All patients were off antiarrhythmic drugs, calcium entry or beta-adrenoceptor blockers at the time of the ergonovine provocation test. Ergonovine was administered intravenously as a bolus injection, beginning with 0.05 mg followed every 3 min by incremental doses up to a cumulative maximum dose of 0.45 mg. Predefined end-points were (1) recording of ischaemic ST segment shifts of > or = 1 mm in at least two corresponding leads of the 12-lead electrocardiogram; (2) induction of ventricular tachycardia or ventricular fibrillation; and (3) administration of a cumulative dose of 0.45 mg. A positive response to ergonovine was seen in only one patient (5%) in group I in whom there developed ST segment elevation without angina and a short burst of rapid ventricular tachycardia. CONCLUSIONS: This study found a low prevalence of coronary artery spasm in patients with aborted sudden death resulting from documented ventricular fibrillation and non-apparent underlying heart disease. All patients had normal coronary angiograms and a negative history for spontaneous episodes of chest pain. The mechanism of arrhythmogenesis in such patients remains largely unknown.

Adult↗

PubMed1998

Prevalence of DSM-IV substance abuse and dependence disorders among prison inmates.

The study examined the 30-day and lifetime prevalence of DSM-IV alcohol and drug disorders among state prison inmates. A sample of 400 inmates consecutively admitted to a state prison reception center were assessed for alcohol and drug disorders using the Structured Clinical Interview for DSM-IV (SCID-IV). Test-retest reliabilities were calculated for the SCID-IV. Lifetime substance abuse or dependence disorders were detected among 74% of inmates, including over half who were dependent on alcohol or drugs. For the 30 days prior to incarceration, over half of the sample were diagnosed as having substance abuse or dependence disorders, including 46% who were dependent on alcohol or drugs. Black inmates were significantly less likely to be diagnosed as alcohol dependent than whites or Hispanics. The high rates of substance use disorders are consistent with previous findings from other studies conducted in correctional settings and reflect the need to expand treatment capacity in prisons.

Adolescent↗

PubMed1997

Treating prison inmates with co-occurring disorders: an integrative review of existing programs.

The tremendous growth in state and federal correctional populations has focused greater attention on the needs of mentally ill and substance abusing inmates. Although an estimated 3-11% of prison inmates have co-occurring mental health (psychotic and major mood) disorders and substance abuse disorders, few treatment programs are described in the literature and there is little available information regarding effective treatment strategies for this population. The current study provides an integrative review of seven 'dual diagnosis' treatment programs that recently have been developed in state and federal prisons. Many of these have evolved from existing substance abuse treatment programs and approaches. Key program components include an extended assessment period, orientation/motivational activities, psychoeducational groups, cognitive-behavioral interventions such as restructuring of 'criminal thinking errors', self-help groups, medication monitoring, relapse prevention, and transition into institution or community-based aftercare facilities. Many programs use therapeutic community approaches that are modified to provide (a) greater individual counseling and support, (b) less confrontation, (c) smaller staff caseloads, and (d) cross-training of staff. Research is underway in three of the seven sites to examine the effectiveness of these new programs.

Adult↗

PubMed1997

Cystic fibrosis transmembrane conductance regulator mediates the cyclic adenosine monophosphate-induced fluid secretion but not the inhibition of resorption in mouse gallbladder epithelium.

We have studied the physiological role of the cystic fibrosis (CF) gene product (cystic fibrosis transmembrane conductance regulator [CFTR]) in gallbladder epithelium using a knockout mouse model for CF. We found that normal mouse gallbladder epithelium expresses functional CFTR as shown by reverse-transcription polymerase chain reaction (RT-PCR) analysis and Ussing chamber experiments. Gallbladders from Cftr -/- mice were structurally intact as shown by microscopic and physiological parameters but lacked the cyclic adenosine monophosphate (cAMP)-induced chloride current observed in normal gallbladders. In fluid transport measurements, normal and Cftr -/- gallbladders were equally active in basal resorption. The addition of forskolin, which activates CFTR anion channel activity through the cAMP system, resulted in net fluid secretion in normal gallbladders. In contrast, Cftr -/- gallbladders were unable to secrete fluid while a complete inhibition of resorption by forskolin was observed. We conclude that, in normal mouse gallbladder epithelium, cAMP-induced fluid secretion involves simultaneous inhibition of apical sodium chloride resorption and activation of CFTR. Our data support the hypothesis that gallbladder disease in CF is at least in part caused by a deficient secretory response to the endogenous cAMP-linked hormones VIP and secretin.

Animals↗

PubMed1996

A delta F508 mutation in mouse cystic fibrosis transmembrane conductance regulator results in a temperature-sensitive processing defect in vivo.

The most prevalent mutation (delta F508) in cystic fibrosis patients inhibits maturation and transfer to the plasma membrane of the mutant cystic fibrosis transmembrane conductance regulator (CFTR). We have analyzed the properties of a delta F508 CFTR mouse model, which we described recently. We show that the mRNA levels of mutant CFTR are normal in all tissues examined. Therefore the reduced mRNA levels reported in two similar models may be related to their intronic transcription units. Maturation of mutant CFTR was greatly reduced in freshly excised oviduct, compared with normal. Accumulation of mutant CFTR antigen in the apical region of jejunum crypt enterocytes was not observed, in contrast to normal mice. In cultured gallbladder epithelial cells from delta F508 mice, CFTR chloride channel activity could be detected at only two percent of the normal frequency. However, in mutant cells that were grown at reduced temperature the channel frequency increased to over sixteen percent of the normal level at that temperature. The biophysical characteristics of the mutant channel were not significantly different from normal. In homozygous delta F508 mice we did not observe a significant effect of genetic background on the level of residual chloride channel activity, as determined by the size of the forskolin response in Ussing chamber experiments. Our data show that like its human homologue, mouse delta F508-CFTR is a temperature sensitive processing mutant. The delta F508 mouse is therefore a valid in vivo model of human delta F508-CFTR. It may help us to elucidate the processing pathways of complex membrane proteins. Moreover, it may facilitate the discovery of new approaches towards therapy of cystic fibrosis.

Animals↗

PubMed1996

Multicentre evaluation of the Thrombotest International Sensitivity Index used with a steel ball coagulometer.

AIM: To compare the International Sensitivity Index (ISI) of the Thrombotest reagent used with a steel ball coagulometer (KC) to the ISI of the same reagent used with the manual (tilt tube) technique. METHODS: The study was carried out by eight laboratories using their own KC instrument and method of testing. All laboratories used the same batch of Thrombotest to determine the clotting times of fresh blood samples from 20 local healthy volunteers and 60 patients on long term oral anticoagulant therapy. KC clotting times were plotted against manual clotting times on double logarithmic scales. Orthogonal regression lines were calculated to assess the ISI. RESULTS: In two laboratories the ISI of the KC method was lower than that of the manual method; these differences, however, were 2% or less. In the other laboratories no clinically important differences were observed between ISI values obtained. However, the clotting times determined with the KC methods were shorter than the manual values. CONCLUSIONS: The ISI of Thrombotest determined with the KC methods was very similar to the manual value. Therefore, use of the ISI value supplied by the manufacturer without adjustment is justified. The mean normal prothrombin time, however, must be determined locally.

Anticoagulants↗

PubMed1996

CFTR expression and mucin secretion in cultured mouse gallbladder epithelial cells.

Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) in humans is frequently associated with progressive liver disease, which appears to result from obstruction of biliary ducts with mucous material. CFTR in the liver is expressed in the biliary epithelium. With the use of a mouse model for cystic fibrosis (CF) we have studied the relationship between CFTR expression and glycoprotein secretion in primary culture of mouse gallbladder epithelial cells (MGBC) MGBC in culture maintain a well-differentiated phenotype as shown by microscopy. The cells produce CFTR mRNA to levels comparable to the intact tissue. With patch-clamp analysis we could frequently observe a linear protein kinase A-regulated Cl- channel that shows all the major characteristics of human CFTR, although its conductance is lower (5 pS compared with 8 pS). MGBC in culture produce and secrete high molecular weight glycoproteins (HMG) in a time-dependent and temperature-sensitive manner. Secretion of HMG was not stimulated significantly by either adenosine 3',5'-cyclic monophosphate (cAMP), Ca2+, or protein kinase C agonists in this system. High concentrations (3 mM) of extracellular ATP stimulated secretion threefold, but low concentrations (0.3 mM) had no effect. Approximately one-third of the HMG produced and secreted consisted of mucin. Cultured MGBC from CFTR-deficient mice produced and secreted mucin to a similar extent as normal cells. We conclude that cultured mouse gallbladder cells are a convenient model to study both CFTR function and mucin secretion. In this system, we found no evidence for a direct link between mucin secretion and CFTR activity, as has been suggested for other cell types.

Animals↗

PubMed1995

A mouse model for the cystic fibrosis delta F508 mutation.

Most cystic fibrosis (CF) patients produce a mutant form (delta F508) of the cystic fibrosis transmembrane conductance regulator (CFTR), which is not properly processed in normal cells but is active as a chloride channel in several experimental systems. We used a double homologous recombination ('Hit and Run') procedure to generate a mouse model for the delta F508 mutation. Targeted embryonic stem (ES) cells (Hit clones) were found; of these either 80 or 20% of the clones had lost the delta F508 mutation, depending on the distance between the linearization site in the targeting construct and the delta F508 mutation. Correctly targeted clones underwent a second selection step resulting in ES cell clones (Run clones) heterozygous for the delta F508 mutation with an efficiency of 2-7%. Chimeric mice were generated and offspring homozygous for the delta F508 mutation showed electrophysiological abnormalities in nasal epithelium, gallbladder and in the intestine, and histological abnormalities in the intestine, typical of CF. Our data suggest that the delta F508 mice have residual delta F508 CFTR activity which would explain the mild pathology of the delta F508 mice. The delta F508 mouse may provide a useful model for the study of the processing defect of delta F508 CFTR and for the development of novel therapeutic approaches based on circumvention of the processing block.

Animals↗

PubMed1994

[Use of sumatriptan (Imigran) in a female patient with coronary spasm].

Sumatriptan (Imigran), an effective drug against symptoms of migraine may cause a sensation of thoracic oppression. In some patients, this is accompanied by ECG alterations. In such cases, the underlying mechanism is probably coronary spasm, although this has never been demonstrated angiographically. The case is described of a young woman who was hospitalized after resuscitation because of ventricular fibrillation. One week previously, after subcutaneous administration of sumatriptan, she had had chest pains for half an hour. A spasm provocation test during coronary angiography gave a positive result. The patient was treated with a calcium antagonist following which she remained free of symptoms. In patients with chest pain after administration of sumatriptan, it is necessary to use this drug cautiously; spasm of the coronary arteries as a cause should be excluded.

Adult↗

PubMed1994

Bradycardia dependent QT prolongation and ventricular fibrillation following catheter ablation of the atrioventricular junction with radiofrequency energy.

Recurrent ventricular fibrillation was observed in a 67-year-old woman following catheter ablation of the AV junction using radiofrequency energy. This serious complication has been reported following direct current energy ablation of the AV junction, but not after using radiofrequency energy. This life-threatening arrhythmia seemed pause and bradycardia dependent. It was followed by QTc prolongation of the QRS escape rhythm 1 day after the procedure. Ventricular arrhythmias were suppressed by rapid ventricular pacing.

Aged↗

PubMed1993

Unfavorable outcome in patients with primary electrical disease who survived an episode of ventricular fibrillation.

BACKGROUND: Prognosis in patients with ventricular tachyarrhythmia without structural heart disease (primary electrical disease) has been described as excellent. However, prognosis may be less favourable in the subgroup surviving an episode of ventricular fibrillation. METHODS AND RESULTS: We prospectively followed 19 consecutive patients (age, 13 to 66 years; mean age, 33 years) who had survived an episode of documented ventricular fibrillation. Structural heart disease, preexcitation, and long QT syndromes were excluded by thorough cardiologic evaluation. All patients underwent 24-hour Holter monitoring, exercise testing, and programmed electrical stimulation according to a standardized protocol. Holter monitoring revealed episodes of ventricular tachyarrhythmia in 5 patients. Exercise testing reproducibly provoked ventricular tachycardia in 2 patients. Baseline programmed electrical stimulation yielded inducibility of rapid ventricular tachyarrhythmia in 10 patients (53%) and noninducibility in 9 (47%). Nine patients were discharged on antiarrhythmic drug therapy. A defibrillator was implanted in 10 patients. During 43-month follow-up (range, 5 to 85 months; median, 41 months), major arrhythmic events recurred in 7 patients (37%). Four of these patients had noninducibility at baseline programmed electrical stimulation. Two patients on antiarrhythmic drugs had recurrent cardiac arrest: one died suddenly and the other was successfully resuscitated from ventricular fibrillation and subsequently underwent defibrillator implantation. In the other 5 patients, termination of (pre)syncopal episodes was associated with defibrillator shocks. Termination of ventricular fibrillation was documented by Holter recording in one of these patients. Specific markers predictive of a recurrent event could not be identified, although 6 of 7 patients with recurrent events had experienced at least one episode of cardiac arrest or (pre)syncope before the index episode. CONCLUSIONS: Patients with primary electrical disease presenting with ventricular fibrillation are at high risk of recurrence of major arrhythmic events during long-term follow-up. Noninducibility at baseline study does not predict an uneventful course. Also, early defibrillator implantation should be considered in these patients.

Adult↗

PubMed1992

Bacterial arthritis in a district hospital.

Between 1977 and 1988 in the Enschede hospital 72 patients were seen with bacterial arthritis of one or more joints. Staphylococcus aureus was most frequently the causative agent (52%) and the knee was the most frequently infected joint (42%); the mortality rate was 11%. Complete restoration of pre-existent function was seen in 52% of the affected joints. In patients with severe deterioration of joint function after the bacterial infection, the period between the first symptoms and start of treatment (mean 30 days) was significantly longer than in patients with no or moderately deteriorated joint function (mean 10 days). The primary focus was mostly a skin infection, predominantly localized on the lower extremities. Half of all cases of bacterial arthritis occurred in patients with rheumatoid arthritis (RA). We therefore conclude that patients with RA and skin infections, especially if localized on legs or feet, should be treated without delay and that one should not hesitate to prescribe antibiotics. Erythrocyte sedimentation rate (ESR) was less than 20 mm after one hour in 13% and blood leucocyte count less than 10 x 10(9)/liter in 55% of all patients, showing that a normal ESR and/or blood leucocyte count do not exclude bacterial arthritis. In 4 out of 9 patients with infected prosthetic joints the infection resulted in loosening of the joint, before antibiotic treatment was started. In the other 5 patients bacterial arthritis recurred, in one patient resulting in loosening of the joint, only shortly after stopping long-term successful antibiotic treatment (6-24 months). Thus, we feel that lifelong treatment with antibiotics is a reasonable alternative in cases, where the risk of surgery is very high.

Adolescent↗

PubMed1992

Referral and screening for substance abuse treatment in jails.

As jails and prisons have become filled to capacity with inmates arrested and convicted for drug-related offenses, efforts have intensified to reduce subsequent drug use, drug-related crime, and recidivism among this population. Faced with the drug abuse epidemic; treatment resources in the community have expanded more quickly than in detention and corrections facilities. Many large jails and prisons do not presently have a substance abuse treatment program despite clear evidence of widespread drug and alcohol dependence problems among inmate populations. Where substance abuse treatment resources are available, administrators face difficult choices in determining which inmates will receive services. This paper provides a discussion of issues related to referral and screening procedures for in-jail substance abuse treatment programs. Referral and screening systems implemented in several jails across the country are reviewed.

Attitude to Health↗

PubMed1992

Plasma testosterone concentration in adult male rats following acquisition of copulation-illness associations.

Prior research has identified stimuli and procedures that elicit increments in plasma testosterone in copulating male rats. In the present experiment, we demonstrate that associative inhibition of copulatory behaviors in male rats is not correlated with and cannot be attributed to a conditioned suppression of testosterone. Each male rat was paired with an inaccessible estrous female for 7 min and was then given an opportunity to copulate. Two groups received an injection of either lithium chloride (LiCl; 0.3 M, 20 ml/kg, IP) or saline (0.3 M, 20 ml/kg, IP) immediately after each of 11 pairings spaced at 3- to 4-day intervals. A third group received a noncontingent injection of LiCl 24 h after each pairing. After an initial screening for copulatory behaviors, a fourth group received only handling comparable to that received by the other three groups. Rats that received contingent LiCl gradually ceased to copulate; rats that received either noncontingent LiCl or saline remained vigorous copulators. Male rats were returned to their home cages on Trial 12 after 7-min exposure to an inaccessible female. Blood was collected by decapitation 38 min later. Testosterone levels, measured by radioimmunoassay, were significantly higher for saline than for handled control rats. Testosterone levels for handled control rats, however, were comparable to those of copulating and noncopulating rats that had received either noncontingent or contingent LiCl, respectively.

Animals↗

PubMed1992

Effects of yohimbine and idazoxan on motor behaviors in male rats.

Yohimbine, an alpha 2 adrenergic antagonist, facilitates copulatory behaviors in male rats. This facilitation may reflect nonspecific activation of behavior rather than a more selective activation of copulatory behaviors. The present experiments assessed the effects of yohimbine on locomotor behaviors at a dose (2.0 mg/kg) known to facilitate sexual behaviors. Experiment 1 used a computer pattern-recognition system to classify motor behaviors into specific acts and act groups. Male albino rats were tested in three conspecific conditions: estrous female, anestrous female, or no conspecific. Yohimbine decreased locomotor activity in all three conspecific conditions. Experiment 2 examined the effects of yohimbine (2.0 mg/kg) and amphetamine (1.0 mg/kg) on locomotor behavior in a photocell-equipped activity measurement system. Amphetamine increased and yohimbine decreased locomotor activity. Experiment 3 used the computer pattern-recognition system to compare the effects of yohimbine and idazoxan, another alpha 2 adrenergic antagonist, on motor behaviors. Yohimbine and idazoxan both decreased activity but produced different patterns of behavioral change. The facilitatory effects of yohimbine on copulatory behaviors at a dose of 2.0 mg/kg are apparently not mediated by nonspecific activation of behavior.

Adrenergic alpha-Antagonists↗