Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Laboratory Procedures”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed2005

Reinforcing effects of oral Delta9-THC in male marijuana smokers in a laboratory choice procedure.

RATIONALE: Oral Delta-9-tetrahydrocannabinol (Delta(9)-THC; Marinol) is medically available for the treatment of nausea associated with cancer chemotherapy and for wasting syndromes related to HIV/AIDS. Little is known about its reinforcing effects. OBJECTIVE: This study was conducted to characterize the reinforcing effects of oral Delta(9)-THC in experienced marijuana smokers under controlled laboratory conditions. METHODS: Ten healthy male marijuana users completed this 17-day residential study. On days 2, 6, 10, and 14, at 0900 h, participants received a "sample" oral dose of Delta(9)-THC (0, 10, 20 mg) and an alternative reinforcer, a 2 US dollars voucher (redeemable for cash at study's end). Over the next 3 days, they had 11 opportunities to self-administer either the sampled dose of Delta(9)-THC or to receive a 2 US dollars voucher. RESULTS: Participants chose active Delta(9)-THC (10 and 20 mg) more often than placebo (<two selections vs approximately four selections, respectively). However, they chose active Delta(9)-THC on less than 50% of choice opportunities. Both active Delta(9)-THC doses produced significant increases in "positive" subjective effects, impaired psychomotor performance, and increased heart rate, relative to the placebo conditions. CONCLUSION: These data indicate that oral Delta(9)-THC may have modest abuse liability in experienced marijuana smokers.

Administration, Oral↗
PubMed2003

Adolescents with atopic disorders have an attenuated cortisol response to laboratory stress.

BACKGROUND: Patients with allergic disorders have been noted to have variations in cortisol patterns under natural conditions as well as a differential cortisol response to stress. OBJECTIVE: The main goal of this study was to examine hypothalamic-pituitary-adrenal (HPA) axis differences in atopic adolescents. METHODS: Subjects were a community sample of 202 adolescents (52% male; mean age, 16.2 years). Atopic status was determined by skin testing and clinical history. Saliva samples for cortisol assay were obtained 4 times during a "typical day" and at 4 time points during laboratory procedures. RESULTS: One third of the sample (33%) had a clinical atopic disorder, primarily allergic rhinitis; 39% had positive skin test results without clinical symptoms; and 27% had no signs or symptoms of allergic disorders. There were no significant effects of atopic status on home cortisol patterns. Presence of clinical atopy was significantly (P <.05) associated with lower cortisol levels in response to laboratory stressors. CONCLUSIONS: Adolescents with a history of atopic illnesses had an attenuated cortisol response to the stress of laboratory procedures compared with adolescents with positive skin test results alone or nonatopic adolescents. An attenuated cortisol response to a stressor may help us understand the link between stress and exacerbation of atopic illness.

Adolescent↗
PubMed1981

Alloys for crown and bridgework.

The requirements of alloys for metal-ceramic crowns and bridgework are examined. The functional requirements and manipulative behaviour and cost of cheaper alternatives to high gold alloys are discussed. All types use--high gold, reduced gold, silver palladium and base metal--appear to function satisfactorily in the mouth. Nickel and beryllium do not appear to be health hazards. Dental laboratory procedures and materials must be chosen to suit the type of alloy employed, although all alloy types appear suitable for crown and bridgework. The cost of alloy must be carefully examined in the context of total cost to the patient, and the use of alternatives to gold alloys in many cases may not warrant the required changes to laboratory procedures, but the saving is real, and can make permanent restorations available to greater proportion of the community.

Biocompatible Materials↗
PubMed1979

[Carcinoembryonic antigen: Comparison of radioimmunoassay and enzyme immunoassay in postoperative surveillance of patients with carcinoma of the colon or rectum (author's transl)].

In the recent time measurement of carcinoembryonic antigen (CEA) has gained increasing importance in post-operative surveillance of patients having been operated upon because of colorectal carcinomas. Simple routine laboratory procedures are needed therefore. CEA was measured in 230 patients; it is demonstrated, that the results obtained by conventional radioimmunoassay are accurate and precise. In addition the specimens were measured by an enzyme immunoassay. Results of both assays coincided rather well. Since the enzyme immunoassay is much easier to perform it is to be prefered as a routine laboratory procedure.

Carcinoembryonic Antigen↗
PubMed2001

Influence of laboratory homogenization procedures on trace element content of food samples: an ICP-MS study on soft and durum wheat.

Sample contamination as a consequence of abrasion of grinding tools during the homogenization of food materials to be analysed for trace elements was addressed. The possible release of 15 trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn, V, Zn) from six different grinding and milling devices, operating either continuously or discontinuously, was evaluated. All the devices were commercially available and were representative of models usually employed in food and agricultural laboratories. Wheat grains belonging to one soft and one durum cultivar were used as test material. The determination of the analyte concentrations in subsamples submitted to the different preparation treatments was performed by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). Accordingly, a suitable digestion method was developed and the ArC+ interference affecting Cr determination was evaluated and corrected. Statistical differences with respect to the control were detected for 10 elements (Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb) and in most cases contamination of the samples was traced back to the composition of the grinding equipment. None of the investigated devices was contamination-free with respect to all of the quantified elements. Abrasion of the grinding tools was higher with durum wheat than with soft wheat as a consequence of their different hardiness.

Analysis of Variance↗
PubMed1998

Microbial toxicity in soil medium.

A laboratory procedure using the respirometer was developed to measure microbial toxicity in soils of organic chemicals. The procedure was tested with Polytox, a commercial microbial test culture, on 35 organic chemicals. The test protocol was reproducible with a mean standard deviation of 0.08 mg chemical/g of soil for eight chemicals. The assays were also carried out at different moisture-holding capacities of soil. Correlation between toxicity tests done in aqueous medium and soil for Polytox test culture was statistically significant and yielded an r2 of 0.816. Details of the laboratory procedure and test results are presented together with comparisons of toxicity of chemicals in the soil medium with that in aqueous medium for the same test organism. A few practical applications are discussed.

Bacteria, Aerobic↗
PubMed1998

The diagnostic accuracy of bedside and laboratory coagulation: procedures used to monitor the anticoagulation status of patients treated with heparin.

We evaluated the diagnostic accuracy of three bedside coagulation procedures, the Hemochron activated whole-blood clotting time (ACT) (International Technidyne, Edison, NJ), the CoaguChek Plus (Boehringer Mannheim, Indianapolis, Ind) activated partial thromboplastin time (APTT) and the TAS (Cardiovascular Diagnostics, Raleigh, NC) APTT, before removal of arterial sheaths, in patients who received heparin therapy during percutaneous coronary angioplasty. As part of the postprocedure care, nurses performed bedside coagulation tests, removed the sheaths when appropriate coagulation criteria were met, and collected samples for laboratory APTT determinations and heparin assays performed with an automated chromogenic anti-Xa assay. Patients with heparin concentrations of 0.3 U/mL or more were classified as anticoagulated and those with concentrations less than 0.3 U/mL, as not anticoagulated. Analysis of the receiver operator characteristic (ROC) curve was used to rank the performance of the methods. Areas under the ROC curves +/- SE for the laboratory APTT, CoaguChek Plus APTT, Hemochron ACT, and TAS APTT were 0.978 +/- 0.016, 0.872 +/- 0.044, 0.797 +/- 0.039, and 0.795 +/- 0.048, respectively. At cutoff values for the tests that provide greatest safety for the patients (no false-negative results), the false-positive rates for the laboratory, CoaguChek Plus, Hemochron, and TAS methods were 15%, 27%, 62%, and 100%, respectively. The laboratory APTT demonstrated the highest diagnostic accuracy in this application; however, turnaround time for the test (50% of the results were reported in excess of 77 minutes) was inadequate for clinical decision making. To meet this requirement, we developed a point-of-care program using the whole blood APTT performed on the CoaguChek Plus analyzer.

Aged↗
PubMed2000

Health care costs of heart failure: results from a randomised study of patient education.

BACKGROUND: Heart failure is a serious syndrome with a bad prognosis. Hospitalisation is common and readmittance rate is high; factors which influence the cost of care and treatment. Only scarce data on detailed patient materials regarding health care costs are known. AIMS: To describe in detail the health care costs for heart failure patients. METHODS: Costs for patients (n=108) who completed a randomised education trial were studied for 6 months after hospital discharge. Costs for hospital stay, out-patient visits, diagnostic tests and procedures, laboratory analyses and drug treatment were calculated. Official unit prices list used to reimburse providers of cross-boundary health services and prices for drugs in the Swedish Drug Compendium were employed. RESULTS: The total cost for a heart failure patient was approximately 20000 SEK (2564 US$, 7.80 SEK=1 US$) for 6 months. There was a 27-fold variation between patients. There was no relation between age or sex and cost. In decreasing order cost for hospitalisation was followed by costs for out-patient visits, diagnostic tests and procedures, laboratory analyses and drugs. CONCLUSION: Hospitalisation was the largest part of the total cost and there was a large inter-individual variation. Efforts to reduce the economic burden should be focused on hospitalisation. Due to skewed distribution, individual data must be considered in the analysis of the efforts.

Adult↗
PubMed1986

Descriptive epidemiology of missed cases of phenylketonuria and congenital hypothyroidism.

We conducted a structured telephone survey of state public health laboratory directors of neonatal screening programs to determine the extent of the problem of missed cases of phenylketonuria (PKU) and congenital hypothyroidism. A total of 76 missed cases were reported--43 PKU and 33 congenital hypothyroidism. We looked at the following characteristics of the missed cases: the stage at which the miss occurred, which included specimen collection, laboratory procedures, or follow-up; the size of the program; the type of screening program; the age of the infant at the time of screening; and any legal action that resulted from the miss. The 76 missed cases probably represent an underascertainment of the true number, yet we believe that our data provide an overview of some of the problems associated with mass neonatal screening. There was one missed case of PKU for every 70 cases detected, and one missed case of congenital hypothyroidism for every 120 cases detected; in other words, two congenital hypothyroidism cases were missed for every 1 million infants screened. Regarding the stage of screening in which the miss occurred, 14% occurred during specimen collection, 45% during the laboratory procedures stage, 16% during follow-up, 11% were the result of biologic variation, and in 14% the stage could not be identified. We conclude that neonatal screening programs have been highly successful but that there may be additional safeguards to be developed, tested, and implemented when practical.

Clinical Laboratory Techniques↗
PubMed1981

Myelin basic protein, oligoclonal bands, and IgG in cerebrospinal fluid as indicators of multiple sclerosis.

There currently are three clinical laboratory procedures for use with cerebrospinal fluid that assist in the diagnosis of multiple sclerosis: measurement of myelin basic protein and IgG, and demonstration of an oligoclonal band. We compared characteristics of these procedures, using CSF samples from 166 patients identified as having (54 patients) or not having (112 patients) multiple sclerosis. We find that oligoclonal band demonstration is the most useful single test in helping to establish the presence of multiple sclerosis; IgG quantitation is the least helpful. Myelin basic protein should be quantitated for following the activity of multiple sclerosis; it may be applied only selectively in the context of screening. The incidence of false-positive results reinforces the view that the diagnosis of multiple sclerosis must be made in clinical context. These laboratory procedures are not suitable for use as screening tests.

Electrophoresis, Agar Gel↗
PubMed1988

Comparison of discriminant analysis procedures in laboratory differentiation of hypercalcemia.

Logistic, linear, and quadratic discriminant analyses were compared in their ability to differentiate hypercalcemic patients with primary hyperparathyroidism from those with malignancy. Linear and quadratic discriminant analyses were performed by use of both untransformed and logarithmically transformed data. Application of principal components analysis with varimax rotation was helpful in revealing the underlying relationships between variables. All discriminant methods identified serum albumin as the best single discriminating test, with the log-quadratic discriminant analysis classifying 81% of patients correctly. The combination of albumin, carboxy-terminal parathyroid hormone, and chloride improved classification accuracy (92% by use of log-quadratic discriminant analysis). Logistic discriminant analysis, using all 20 variables, gave a classification accuracy of 100%. Quadratic discriminant analysis gave better classification than linear discriminant analysis, and both methods performed better when log-transformed data were used. Logistic discriminant analysis followed by discrimination procedures using log-transformed data yielded the highest classification accuracy and reliability of the methods used.

Humans↗
PubMed1997

Longevity of fixed partial dentures.

STATEMENT OF PROBLEM: The anticipated length of service and reasons for replacement of fixed partial dentures (FPDs) are a frequent inquiry by patients. Previous reports have provided limited information on material and techniques used in restoration or standards in evaluations of restorations at delivery. PURPOSE: This study determined the reasons for failure and length of service for FPDs delivered with specific clinical, radiographic, and laboratory procedures. METHODS: A clinical and retrospective chart review was conducted on all patients with FPDs who were treated in the prosthodontic clinic at the University of Iowa Hospital for routine dental hygiene recalls during a 6-month period. Fifty patients were examined with a total of 89 FPDs. Of the 89 FPDs, 13, or 15%, were identified as failures or had been replaced because of failure. Dental caries was the most frequent cause of failure (38%), followed by periapical involvements (15%), perforated occlusal surfaces (15%), fractured post and cores (8%), defective margins (8%), fractured teeth (7%), and porcelain failures (8%). The mean length of service for failed FPDs ranged from 16.0 years, because of failure from dental caries, to 4.1 years, because of a fractured post and core. RESULTS: A linear regression model of years in service against number of failed FPDs indicated that the number of years in service provided no information on predictability of failure for FPDs. CONCLUSIONS: This study supported previous reports of dental caries as the primary cause for failure of FPDs, but specific radiographic, clinical, and laboratory procedures can increase the length of service of these restorations.

Adult↗
PubMed2002

The unsatisfactory ThinPrep Pap Test: missed opportunity for disease detection?

Cervical cytology specimens classified as "unsatisfactory for interpretation" represent a potential source of undetected disease. This prospective study analyzed the potential benefits of a laboratory procedure to reprocess unsatisfactory ThinPrep Pap Tests (Cytyc, Boxborough, MA). All unsatisfactory ThinPrep samples were reprocessed using a glacial acetic acid wash. The study period unsatisfactory rate was compared with that for the previous 12 months. The initial unsatisfactory rate was 1.3% (197/15,154). Of the unsatisfactory ThinPrep samples, 55.8% (110/197) had residual material for reprocessing. After reprocessing, 67.3% (74/110) were reclassified as "satisfactory" or "satisfactory but limited by," and the final unsatisfactory rate was 0.8% (123/15,154), a 62% decrease. Compared with the previous 12-month rate of 0.9% (209/23,730), this was a 12% reduction. Seven (6.4%) of 110 initially classified as unsatisfactory contained an epithelial abnormality (atypical squamous cells of undetermined significance, 3; atypical glandular cells of undetermined significance, 2; low-grade squamous intraepithelial lesion, 1; squamous cell carcinoma, 1) on the reprocessed slide. Reprocessing of unsatisfactory ThinPrep slides yielded additional cellular abnormalities that otherwise would have been undetected. The present study confirms that reprocessing of unsatisfactory ThinPrep slides is a beneficial laboratory procedure.

Acetic Acid↗
PubMed1994

Disk diffusion susceptibility testing of dermatophytes with allylamines.

BACKGROUND: Allylamines are a newly developed group of drugs possessing a broad spectrum of activity against a wide range of fungi. With the advent of new antifungal drugs, susceptibility testing of fungi is receiving increased attention as important laboratory procedures for aiding in the selection of appropriate drug therapy. METHODS: In vitro susceptibility testing of 43 clinical isolates of dermatophytes which included Microsporum sp., (18) Trichophyton sp., (23) and Epidermophyton floccosum (2) were carried out against the two allylamine derivatives, naftifine and terbinafine, by agar dilution and disk diffusion methods. RESULTS: Terbinafine was found to be more active minimal inhibitory concentration (MIC range < or = 0.0001-0.1 micrograms/mL), inhibiting 50% (MIC 50) and 90% (MIC 90) of the isolates at 0.01 and 0.1 micrograms/mL, respectively. The MIC 50s and MIC 90s of naftifine were 0.1 micrograms/mL (MIC range 0.001-0.5 micrograms/mL). Both the drugs showed good correlation between the MIC and sizes of zones of inhibition around the disks. Regression analysis was used to measure the degree of correlation between the MIC values and matched averaged zones of inhibition; the correlation coefficients for both terbinafine and naftifine were -0.6841 (P < 0.001) and -0.5455 (P < 0.001), respectively. CONCLUSIONS: The allylamines, naftifine and terbinafine, could be used successfully for susceptibility testing of dermatophytes by the disk diffusion method. With proper standardization of the test conditions, in vitro susceptibility testing of filamentous fungi by disk diffusion would become a useful laboratory procedure in the near future for determining the best drug therapy.

Agar↗
PubMed2001

Testing and analytical procedures for laboratory studies involving nonresponders during a limited observation period: an illustration using male sexual behavior in rats.

In many laboratory studies, a subpopulation of subjects fails to exhibit the response under investigation during the period of observation. For example, within any population of male rats, there is significant variation in the expression of sexual behavior in the presence of a receptive female. Some males may never display the full sequence of behaviors leading to ejaculation within the typical time frame of the testing session, with the resulting lack of behavioral response presenting problems in the analysis of the data. Conventional strategies range from screening such males from the study or dropping them from the analysis to constructing new variables based on estimates from existing parameters or increasing the length of the test session to capture sexual responses in a greater portion of males. Herein, we present an alternative strategy for analyzing data where outcomes are absent due to the limited observation period. Survival regression analysis enables inclusion of all subjects in the analysis whether or not they have shown the behavior of interest. Use of such a strategy not only has potential to reveal new results but also guards against bias from excluding nonresponders from the study or dropping more males from one experimental condition than another. Furthermore, this procedure can be helpful in generating the conditional probability (increase, decrease, or constant) of the response with the passage of time based on the hazard function and in estimating parameters for establishing an optimal behavioral test length for future studies.

Analysis of Variance↗
PubMed2005

Recommendations for a toxicological screening ERG procedure in laboratory animals.

Electroretinography, using laboratory animals, is a commonly used technique for determining the retinal toxicity of chemical agents. In this paper, guidelines for performing this test are provided. The physiologic basis for visual testing is presented with attention to inter-species differences. Technical aspects of animal recordings are reviewed, including animal preparation, stimulation, signal conditioning, recording and data analysis. Finally, suggested protocols for recording in diurnal and nocturnal species are presented.

Animals↗