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Biomedical subjects

J A Lott

Publications and source records attributed to J A Lott.

108 records · Page 6Linked to original sources
PubMed1978

A technique for determining the probability of abnormality.

Histograms of the results of quantitative clinical laboratory analyses are usually broadly skewed because some of the patients have normal values with respect to the analyte being measured while values for others are below or above normal. We describe a technique for calculating the maximum possible number of individuals in a patient population who will give normal values and, by difference, the minimum possible number of those who will give below-normal and above-normal values. The technique permits estimation of the probability that any given result represents a member of a particular subpopulation, as well as selection of decision limits for patient classification, and estimates the degree of change required for a subject with a normal value to start giving below- or above-normal values.

Adult↗
PubMed1978

Biochemical changes in a porcine model of acute pancreatitis.

Pancreatitis was induced in 11 miniature pigs by infusing a bile salt-trypsin solution into the pancreatic duct. Seven animals served as sham-operated controls. Serum ionized calcium, total calcium, albumin, total protein, inorganic phosphorus, urea nitrogen, magnesium, insulin, glucagon, and hematocrit were determined every six to 12 h over a period of one week in both test and control animals. We observed significant decreases in ionized and total calcium, modest decreases in albumin, and significant increases in the inorganic phosphorus, urea nitrogen, and hematocrit in the pancreatitic pigs. The latter two findings were consistent with early acute hypovolemia. Glucagon and insulin appeared to play no role in the hypocalcemia. Glucagon concentrations increased to the same degree in both test and control animals, probably as a result of the stress of being handled and operated on. The highest concentrations of inorganic phosphorus and the lowest concentrations of both ionized and total calcium were seen 18 h after the induction of pancreatitis in the test animals. These findings suggest that parathyrin (parathormone) was not being secreted in adequate amounts, or that the target organs were unresponsive to parathyrin.

Animals↗
PubMed1978

Factors affecting measurement of total alkaline phosphatase activity in human serum, especially wavelength accuracy.

Serum alkaline phosphatase estimations by the Selected Method [Clin. Chem. 21, 1988 (1975)] are very sensitive to small errors in the wavelength setting of the spectrophotometer. With a setting error as small as 3 nm, results can be too low by as much as 23%. The product of the reaction, 4-nitrophenol, can be prepared in very pure form and can be used to check both the wavelength and absorbance accuracy of a spectrophotometer. The molar absorptivity for 4-nitrophenol obtained in the instrument being used should be used in calculating alkaline phosphatase activities.

Alkaline Phosphatase↗
PubMed1978

An interlaboratory comparison of analyses of clinical specimens.

A pilot study was conducted to identify some of the benefits and limitations of making interlaboratory comparisons of clinical assays. Sixteen laboratories that participated in a regional quality control program and used similar instrumentation each provided analyses of specimens from three male and three female healthy subjects, 25 male and 25 female clinical subjects, and several control specimens. Analysis of the data revealed that the derived normal ranges agreed well with those provided by the instrument manufacturer, and that for some analytes the laboratories produced comparable clinical assays. The control specimens were found to be indicators of the presence of analytic bias that affected the clinical assays, but they did not always correctly indicate the kind or magnitude of bias. Using pattern recognition technics, it was shown that a laboratory's clinical assays had characteristic distributions that were apparently related to the populations served, as well as to analytic precision. The results demonstrate that useful information may be gleaned from interlaboratory surveys of clinical assays.

Blood Chemical Analysis↗
PubMed1977

Practical problems in clinical enzymology.

It is possible to carry out precise determinations of the activity of the clinically important serum enzymes with continuous monitoring (kinetic) methods. Care must be taken that the induction period has passed before the first measurement is taken and that the reading is taken from the zero-order, linear part of the curve. Special precautions must be taken with highly active sera that are also turbid. There are no suitable enzyme standards available at present; therefore, standardization of the instrument is of utmost importance. The instrument must be able to produce the theoretical molar absorptivity of the substrate or cofactor. The instrument must be calibrated for wavelength and absorbance accuracy with nationally accepted standards. Some reference methods are beginning to appear; if widely adopted, they should improve the interlaboratory comparability of enzyme assays. Instrument and method standardization plus well-characterized enzyme standards, when available, will reduce the variability of intra- and interlaboratory enzyme assays.

Alanine Transaminase↗
PubMed1977

Impact of posture on the "reference range" for serum proteins and calcium.

The impact of water shifts due to changes in posture has been reinvestigated for serum protein and calcium concentrations in a young, healthy population. We found that generaly accepted normal ranges for total serum protein, and to a lesser degree for total serum calcium, are not acceptable as a reference range for a hospitalized population that is predominantly in a supine position. Our data indicate a smaller biological variability for total protein and calcium for a reference population in the recumbent posture as compared to the same population in the upright position.

Adult↗
PubMed1975

Evaluation of Trinder's glucose oxidase method for measuring glucose in serum and urine.

Trinder's method for glucose has nearly all the attributes of an ideal automated colorimetric glucose oxidase procedure. The chemicals used in the color reaction with peroxidase are readily available, the solutions are stable and can be prepared by the user, the method is highly specific and largely free of interferences, the sensitivity can be adjusted by the user to cover a wide range of glucose concentrations, and the reagents are not hazardous. We found very good agreement between results by this method and by the hexokinase and Beckman Glucose Analyzer methods. The method has been modified and adapted to the AutoAnalyzer I and SMA 6/60 (Technicon) with manifolds that give very little interaction between specimens. A study of the method by the simplex technique revealed that the glucose oxidase activity in the reagent is the most critical variable.

Animals↗
PubMedDate not supplied

Use of continuous quality improvement to identify barriers in the management of hypertension.

We have made great strides in understanding the pathophysiology and medical management of hypertension, yet barriers to effective blood pressure control remain. The process of identifying the barriers within the health care system may be as important as the barriers themselves. Our primary purpose was to apply the widely accepted tool, Continuous Quality Improvement (CQI), to identify barriers to the management of hypertension. We wanted to identify the most important factors and (or) persons in effective blood pressure control and to compare costs, satisfaction, and blood pressure control among subgroups of patients to identify those most likely to benefit from interventions. We recruited patients with essential hypertension who came to a university-based clinic staffed by family physicians and residents; 181 patients with hypertension were identified and asked at the time of their visit to complete a questionnaire relating to the management of their blood pressure. Twenty-five physicians and 8 medical assistants were also asked to complete a similar questionnaire regarding their perceptions of barriers to blood pressure management. All other information came from the patients' medical records. Blood pressure control was based on a reading taken on the date the questionnaire was completed. Student's t test was used to determine if statistically significant differences existed in blood pressure control, patient satisfaction, and total costs for certain subgroups; regression analysis was used to determine correlations. We had completed questionnaires from 91 patients, 89 physicians, and 79 staff. The physicians and staff were of course involved; however, we found that the patients' gestalt was extremely important in blood pressure control. Our patients perceived that lifestyle modifications such as exercise and weight loss were the greatest barrier to better blood pressure control. The cost of certain antihypertensive drugs was an obstacle for some patients. African Americans had poorer blood pressure control, and their satisfaction of care was significantly lower than that of other races. Our patients taught us that the 2 major barriers to blood pressure control were changes in lifestyle and reducing the cost of medications. We also found that our African American patients showed the poorest blood pressure control and the greatest dissatisfaction with their care. We surmise that the greatest benefit of any intervention would be expected in this population. We demonstrated that CQI can be used to identify barriers to hypertension management and subgroups of patients likely to benefit from interventions.

Adult↗