Biomedical subjects

J M Mitchell

Publications and source records attributed to J M Mitchell.

100 records · Page 6Linked to original sources

PubMedDate not supplied

Validity testing of the accuPINCH THC test.

Self-contained drug-testing kits are currently being marketed for a variety of drugs of abuse. These tests are designed to provide rapid access to test results without the need for laboratory facilities. This report describes a validity study of the accuPINCH THC test, a self-contained test for cannabinoids in urine. Three healthy male volunteers with a history of marijuana use participated in the clinical study. Each subject smoked one, two, or four marijuana cigarettes (2.6% THC) on each test day. Urine samples were collected and incorporated into a specimen set consisting of 178 clinical samples, 72 urine samples containing known amounts of drug, and 50 drug-free urine samples. The specimen set was randomized and analyzed under blind conditions by the accuPINCH test and by gas chromatography-mass spectrometry (GC-MS) for 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH). AccuPINCH results were interpreted independently by three readers as positive at either two calibration points (positive A < 100 ng/mL THCCOOH; positive B > or = 100 ng/mL THCCOOH) or negative. Concordance analysis was performed by comparison of the accuPINCH results with GC-MS. In addition, the effects of changes in sample turbidity, temperature, and assay reading time on test outcome were assessed. For the clinical samples, positive B results were associated exclusively with THCCOOH concentrations greater than or equal to 15 ng/mL, whereas positive A and negative results were obtained at all concentrations. All drug-free urine samples were interpreted as either negative or positive A. The test demonstrated relatively low cross-reactivity with THC and other cannabinoids.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Simultaneous identification and quantitation of codeine and morphine in urine by capillary gas chromatography and mass spectroscopy.

An analytical procedure for simultaneous determination of codeine and morphine in urine is described. The detection of codeine and morphine is based on liquid-liquid extraction and derivatization to the acetylated compounds. The acetylated codeine and morphine are separated by capillary gas chromatography and identified mass spectrometrically by selected ion monitoring (SIM). Quantitative determination was carried out by SIM using nalorphine as internal standard. Excellent linearity was obtained over a concentration range of 25 to 800 ng/mL. The overall recovery for codeine and morphine in the extraction was found to be 58% and 40%, respectively. The on-column sensitivity for both compounds was 2 ng at a peak-to-noise ratio of 5:1. The derivatives, acetylcodeine, diacetylmorphine, and diacetylnalorphine were stable at room temperature for 72 hr.

Codeine↗

PubMedDate not supplied

Vibration perception threshold: influence of age, height, sex, and smoking, and calculation of accurate centile values.

Vibration perception threshold (VPT) is increasingly used as a measure of large nerve fibre function in studies of patients with diabetes and in other disorders. In order to establish the influence of age, height, sex, and smoking on VPT values in the normal population and to allow the calculation of accurate age-related percentile charts, 1365 healthy volunteers were studied using a biothesiometer. Measurements were made bilaterally on thumbs, great toes, and over medial malleoli. Multivariate regression analysis confirmed age to be the major determinant of VPT levels at all sites (p less than 0.001). Height was a significant factor for toes and ankles (p less than 0.001) but not thumbs. Sex had no overall effect at toe or thumb but there were differences regarding ankle VPT (p less than 0.01). Log transformation of VPT data produced a linear relationship with age at all sites except at the thumbs in elderly females where there was significant deviation from this model (p less than 0.001) and inverse square root transformation was more appropriate. Smoking had no effect on VPT levels. Age-related centile charts were produced for each site and an easy-to-use computer program was developed to calculate centile values based on raw VPT data, age, height, and sex.

Age Factors↗

PubMedDate not supplied

Effects of HMO market penetration on physicians' work effort and satisfaction.

We investigate whether geographic variations in health maintenance organization (HMO) market penetration are associated with three aspects of physicians' practices: number of hours worked per year, number of patients seen per week, and satisfaction with the current practice. Based on multivariate regression analysis of data for 4,373 patient care physicians (under age forty-five) from a national random sample surveyed in 1991, we estimate that a doubling of the average level of HMO penetration is associated with statistically significant differences of 4 percent fewer annual hours, 13.7 percent fewer patients seen per week, and a 20 percent greater likelihood of not being very satisfied with one's current practice.

Adult↗

PubMedDate not supplied

Effects of case management and new drugs on Medicaid AIDS spending.

This study evaluates the effects of Florida's participation in the Medicaid acquired immunodeficiency syndrome (AIDS) home and community-based waiver and the use of recently developed AIDS drugs on spending per Medicaid beneficiary. We find that monthly Medicaid spending for waiver non-participants was significantly higher than was spending for waiver nonparticipants. The major reason for the cost difference is that nonwaiver enrollees incurred significantly higher inpatient costs than did those enrolled in the waiver. Although waiver enrollees had higher drug spending, these represent only a fraction of the higher inpatient costs incurred by nonwaiver enrollees. Thus, it appears that adherence to appropriate medications reduces the need for inpatient care. The case management approach of the AIDS waiver may have similar effects for persons with other chronic diseases.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Validation of the LacTek test applied to spiked extracts of tissue samples: determination of performance characteristics.

LacTek tests are competitive enzyme-linked immunosorbent assays intended for rapid detection of antimicrobial residues in bovine milk. In this study, the LacTek test protocol was modified for use with extracts of bovine tissue to detect beta-lactam, tetracycline, and sulfamethazine residues. Test performance characteristics--precision, accuracy, ruggedness, practicability, and analytical specificity and sensitivity--were investigated. Results suggest that LacTek tests can be easily adapted to detect antimicrobial residues in extracts of lean ground beef. However, positive samples may not contain residues at violative concentrations (i.e., Canadian maximum residue limits), and therefore, additional analysis would be required for final confirmation and quantitation (e.g., chromatography).

Animals↗

PubMedDate not supplied

Serum ceruloplasmin concentrations in rats with primary and transplanted sarcomas induced by nickel subsulfide.

Ceruloplasmin (CPN) concentrations were measured by p-phenylenediamine oxidase assay in serums from (a) 30 control Fischer rats; (b) 5 rats with primary sarcomas induced by i.m. injection of nickel subsulfide (alpha Ni3S2), and (c) 12 rats at intervals up to six weeks after s.c. transplantation of four alpha Ni3S2-induced sarcomas. Serum CPN concentrations were not significantly increased in rats with primary sarcomas (mean = 0.38 g per liter) (S.D. +/- 0.05), versus 0.35 g per liter (S.D. +/- 0.04) in controls. In contrast, serum CPN concentrations were increased within 11 to 21 days in all rats with transplanted sarcomas. Maximum concentrations of serum CPN occurred at 31 to 34 days after tumor transplantation, (mean = 0.56 +/- 0.05 g per liter), equivalent to 1.6 +/- 0.2 times the initial CPN concentrations in serums obtained prior to treatment (P less than 0.001). The development of hyperceruloplasminemia in rats with transplanted sarcomas and not in rats with primary sarcomas is attributed to greatly enhanced growth-rates of the transplanted neoplasms.

Animals↗

PubMedDate not supplied

Induction of renal cancers in rats by intrarenal injection of nickel subsulfide.

The carcinogenicity of nickel subsulfide (alpha Ni3S2) was studied following intrarenal (i.r.) injection in rats. Within 100 weeks after i.r. injection of 5 mg of alpha Ni3S2, renal cancers were found in 64 percent of Wistar-Lewis rats, 50 percent of NIH Black rats, 28 percent of Fischer rats and 0 percent of Long-Evans rats. These findings demonstrate significant differences in susceptibilities of the four rat strains to alpha Ni3S2-induction of renal cancers. No renal cancers were found in male Fischer rats that received i.r. injection of alpha Ni3S2 in dosages of 0.6, 1.2 or 2.5 mg. In male Fischer rats that received i.r. injection of alpha Ni3S2 in dosages of 5 or 10 mg, the incidences of renal cancers were 28 percent and 75 percent, respectively. These findings demonstrate a dose response relationship for alpha Ni3S2-induction of renal cancers. In male Fischer rats that received i.r. injection of 10 mg of alpha Ni3S2 combined with 6.9 mg of Mn dust, the incidence of renal cancers was 32 percent, which differed significantly from the corresponding incidences of 75 percent and 0 percent in rats that received i.r. injections of only alpha Ni3S2 (10 mg) or Mn dust (6.9 mg). These findings demonstrate that alpha Ni3S2-induction of renal cancers is inhibited by simultaneous administration of manganese dust. The 54 renal tumors that were found in this study were all malignant, and distant metastases were present in 69 percent of tumor-bearing rats. The histogenesis of alpha Ni3S2-induced renal tumors from epithelial or mesenchymal progenitor cells could not be definitely established.

Animals↗

PubMedDate not supplied

Effects of nickel chloride and nickel carbonyl upon glucose metabolism in rats.

Hyperglycemia, hyperglucagonemia and hyperinsulinemia were observed in fasting rats at 0.5 hr after ip injection of NiCl2 (68 mumole per kg). Infusion of somatostatin iv (0.5 mg per rat) did not prevent Ni(II)-mediated hyperglycemia, hyperglucagonemia or hyperinsulinemia. Exposure of rats to inhalation of Ni(CO)4 (1.2 to 6.4 mumole per liter of air per 15 min) caused acute hyperglycemia, similar to that observed after ip injection of NiCl2. Hyperglycemia induced by NiCl2 and Ni(CO)4 was not associated with inhibition of erythrocyte glycolysis measured in vitro by erythrocyte uptake of 1-14C-glucose and release of 14CO2. These findings indicate that Ni-induced hyperglycemia may be mediated by increased pancreatic release of glucagon, but that Ni stimulation of glucagon release differs from stimulation of glucagon release by arginine or epinephrine, since the Ni effect is not antagonized by somatostatin.

Animals↗

PubMedDate not supplied

Breast cancer treatment choice and mastectomy length of stay: a comparison of HMO and other privately insured women.

This study uses hospital discharge abstract data from five states (Massachusetts, New York, New Jersey, Maryland, and California) for two years (1988 and 1991) to investigate whether enrollment in an HMO affects nonelderly breast cancer patients' treatment choice (breast-conserving surgery or mastectomy) and hospital length of stay for women who have a mastectomy. Since HMO insurance creates financial incentives that differ from other types of insurance coverage, it is important to assess whether the type of insurance coverage affects the care received by breast cancer patients. Although the results vary from state to state, they suggest that HMO enrollees are less likely to receive breast-conserving surgery (relative odds =.93). However, an unambiguous interpretation of this findings requires better data on patients' opportunity costs and preferences, which also may vary with type of insurance coverage. Among women who had a mastectomy, HMO enrollment was generally associated with a 4.5% shorter average length of stay and a greater likelihood of a short stay (one or two days, relative odds = 1.21-1.29). A much higher proportion of mastectomy patients in California than in other states had a short stay. Follow-up of these women may indicate whether short stays lead to adverse long-term health effects.

Adult↗