Search PubMed⌕ Search

Biomedical subjects

S Stuart

Publications and source records attributed to S Stuart.

At least 37 records · Page 2Linked to original sources
PubMed1993

Assessment and optimization of kinetic methods for angiotensin-converting enzyme in plasma.

In the kinetic angiotensin-converting enzyme (ACE) method, a practical and optimal buffer is 80 mmol/L borate buffer at pH 8.2 (37 degrees C). A lag phase is detected in the reaction, and a 5-min incubation of substrate and plasma is suggested before the kinetic measurement. The substrate, N-[3-(2-furyl)acryloyl]-L-phenylalanylglycylglycine (FAPGG), concentration is maximized at 1.0 mmol/L and the measurement wavelength is at 345 nm to ensure linearity of measurement. The proposed procedure uses a 1:9 plasma-to-reagent volume ratio. The linear range of the assay extends to approximately 170 U/L, representing a 25% substrate hydrolysis. The FAPGG absorptivity is determined by measuring the difference in absorbance between 1.0 mmol/L FAPGG and the product solutions. The wavelength fidelity is checked by noting the expected absorbance value of the FAPGG solution, and a 1.0-nm deviation from 345 nm alters the absorbance by 15.5%. The precision of ACE assays at approximately 60 and 100 U/L is 3.5% and 2.4% within batch and 2.9% and 2.6% between batch, respectively. The reference interval (2.5th to 97.5th percentiles) is 41-139 U/L, and there is no difference between values for men and women.

Boric Acids↗
PubMed1992

Stability of the CK-MB isoenzyme on routine storage.

Unlike earlier studies on the stability of the CK-MB isoenzyme carried out on control sera and on semi-purified and purified CK isoenzymes, we have studied the stability of CK-MB measured electrophoretically in patient sera under different laboratory storage conditions. The values obtained if the test was done immediately were significantly higher than those done on stored samples. There was no difference between specimens stored at -20 degrees C overnight or kept at room temperature (RT) for a few hours, but values were significantly lower (p less than 0.005) in specimens left at RT for 6 h and then stored overnight at 4 degrees C. To determine the effects of longer storage, further specimens stored either at -20 degrees C or at 4 degrees C for up to 4 days were also tested for CK-MB stability by electrophoresis and by immunoinhibition and immunoenzymetric methods. The immunological methods were included in the study to assess method dependency of CK-MB stability. CK-MB was stable at -20 degrees C by all methods, but at 4 degrees C, CK-MB was stable only by immunological and not by electrophoretic (p less than 0.005) measurement. Specimens stored under adverse conditions (4-6 days at RT) showed 50% deterioration of CK-MB when measured electrophoretically but only about 20% when measured immunologically.

Creatine Kinase↗
PubMed1992

Are personality assessments valid in acute major depression?

A number of recent studies indicate that identification of Axis II comorbidity in depressed patients may influence both the initial treatment plan and subsequent prognosis. Nevertheless, the validity of personality disorder diagnoses may be compromised by the effects of the patients' depression on historical recall, which distort presentation of their premorbid strengths and liabilities. These problems are illustrated in this study of 53 acutely depressed unipolar outpatients, with (N = 14) or without (N = 39) personality disorder diagnoses as defined by the Personality Disorder Examination (PDE). We found that: 1) pretreatment PDE diagnoses had no significant associations with any measure of demography, symptomatic status, illness course, or treatment response; and 2) pretreatment PDE diagnoses typically were not confirmed when patients were reassessed following effective treatment with cognitive behavior therapy. These findings provide strong empirical support for the wisdom of deferring definitive assessment of Axis II until an acute depressive disorder has been optimally treated.

Acute Disease↗
PubMed1992

Identification of developmental disabilities and health problems among individuals under child protective services.

Although a relation between child abuse and developmental disabilities has been established, information about the health and developmental status of children referred to child protective services is not adequately obtained. Case records of 150 children identified to child protective services were reviewed in order to determine the availability of health and developmental information. A screening protocol was developed for the purpose of reviewing case records that has potential for use by child protective services workers.

Adolescent↗
PubMed1991

Estimation and characterization of the potential renal organ donor pool in Pennsylvania. Report of the Pennsylvania Statewide Donor Study.

The Pennsylvania Statewide Donor Study evaluated deaths under the age of 66 occurring in 149 participating hospitals in 1987. After elimination of 6146 patients from 11,983 based upon ICD-9 code criteria, an on-site medical record review was performed on 5603 patients. Each patient was assessed for organ donor suitability based upon brain death and medical suitability criteria--and, after a series of eliminations, 453 patients were found to have a moderate or higher potential as acceptable organ donors. An estimation of the organ donor rate was placed between 38.3 and 55.2 donors per million population per year, depending upon the stringency of organ donor criteria. Educational efforts targeted at physicians, patient's families and transplant surgeons will be necessary, however, to attain this maximal rate.

Adult↗
PubMed1991

Urine hydroxyproline: a potential error in quantification and a proposed procedure for its measurement.

A modification of the colorimetric method of Bergman and Loxley for the measurement of urinary hydroxyproline using external aqueous hydroxyproline standards instead of individual internal standards is described. We show that this modification leads to an underestimation (average 32%) of hydroxyproline because suppression of colour development occurs in urine samples but not in aqueous standards. Use of an internal standard for each urine test corrects for this suppression. Recovery of hydroxyproline (250 mumol/L) added to 12 patient urine samples averaged 99% and the overall imprecision for the assay was then less than 5%. Modifications to the original hydrolysis and colour development procedures allow linearity to 1500 mumol/L. Details of our procedure are given.

Colorimetry↗
PubMed1991

Measurement of porphobilinogen in urine by a simple resin method with use of a surrogate standard.

In this method for urinary porphobilinogen (PBG), urine is added to Bio-Rad AG1-X2 (200-400 mesh) acetate resin under alkaline conditions and mixed. After two water washes, the adsorbed PBG is eluted with acid and reacted with Ehrlich's reagent (p-dimethylaminobenzaldehyde). Quantification is by comparison of the color developed with that of a PBG standard similarly treated or of a calibrated methyl red solution. The precision of assay of PBG at 20 and 50 mumol/L is 1.4% and 0.9% within-batch and 4% and 3.9% between-batch, respectively. The analytical recovery is about 90%, a proportion that appears to be inherent in the resin method. The proposed method (y) agreed well with the method of Mauzerall and Granick (x; J Biol Chem 1956;19:435-46), yielding the regression equation y = 0.957x + 2.9 (r = 0.993, n = 26). Good agreement was achieved with results determined from the PBG and the methyl red standards. The proposed method is inexpensive, simple to perform, and suitable for routine and emergency use.

Acetates↗
PubMed1990

Limited heterogeneity of rearranged T-cell receptor V alpha transcripts in brains of multiple sclerosis patients.

The identification of activated T cells in the brain of individuals with multiple sclerosis (MS) indicates that these cells are critical in the pathogenesis of this disease. In an attempt to elucidate the nature of the lymphocytic infiltration, we used the polymerase chain reaction to amplify T-cell antigen receptor (TCR) V alpha sequences from transcripts derived from MS brain lesions. In each of three MS brains, only two to four rearranged TCR V alpha transcripts were detected. No V alpha transcripts could be found in control brains. Sequence analysis of transcripts encoded by the V alpha 12.1 region showed rearrangements to a limited number of J alpha region segments. These results imply that TCR V alpha gene expression in MS brain lesions is restricted.

Base Sequence↗
PubMed1988

Ward and laboratory assessment of two second-generation blood-glucose monitoring systems.

We present an assessment of two blood-glucose monitoring systems--the Ames Glucostix reagent strips read on the Glucometer II and the Boehringer-Mannheim BM-Test-Glycemie 20-800 test strips read on the Reflolux II meter. Many nurses in the wards and a technologist in the laboratory assessed the systems. All operators achieved good precision with both systems at various glucose levels, the coefficients of variation for the technologist being less than 8% and those for the nurses being less than 11%. The Boehringer-Mannheim system gave good agreement with the laboratory values, with a mean bias of +0.14 mmol/L and limits of agreement between -1.38 mmol/L and +1.66 mmol/L. The Ames system gave poorer agreement, with a bias of +0.80 mmol/L and limits of agreement between -2.12 mmol/L and +3.72 mmol/L. Our study shows that both systems are capable of providing clinically-acceptable results when used by trained personnel. Although it took longer to use, the operators unanimously preferred the Boehringer-Mannheim system because generally it was easier to handle. This is due to a smaller amount of blood being needed which is easier to apply and to remove from the strip, and the cleaning material is not as likely to be left on the strip. Also, strip insertion is easier and there is sufficient time for this after the removal of blood.

Blood Glucose↗
PubMed1988

Replication program of active and inactive multigene families in mammalian cells.

In a comprehensive study, the temporal replication of tissue-specific genes and flanking sequences was compared in nine cell lines exhibiting different tissue-specific functions. Some of the rules we have determined for the replication of these tissue specific genes include the following. (i) Actively transcribed genes usually replicate during the first quarter of the S phase. (ii) Some immunoglobulin genes replicate during the first half of S phase even when no transcriptional activity is detected but appear to replicate even earlier in cell lines where they are transcribed. (iii) Nontranscribed genes can replicate during any interval of S phase. (iv) Multigene families arranged in clusters of 250 kilobases or less define a temporal compartment comprising approximately one-quarter of S phase. While these rules, and others that are discussed, apply to the tissue-specific genes studied here, all tissue-specific genes may not follow this pattern. In addition, housekeeping genes did not follow some of these rules. These results provide the first molecular evidence that the coordinate timing of replication of contiguous sequences within a multigene family is a general property of the mammalian genome. The relationship between replication very early during S phase and the transcriptional activity within a chromosomal domain is discussed.

Animals↗
PubMed1988

Structure and function of Fc receptors on macrophages and lymphocytes.

Cell surface receptors for the Fc portion of immunoglobulin confer on most cells of the immune system the ability to communicate with the humoral antibody response. These Fc receptors are known to be particularly important for the function of various effector cells, such as macrophages, since they are involved in mediating a variety of activities including endocytosis, antibody-dependent cellular cytotoxicity, and triggering the release of potent inflammatory agents. Over the past few years, a considerable amount has been learned about the structure and functions of the Fc receptors expressed by murine and human cells, due to the availability of specific anti-receptor antibodies and the isolation of Fc receptor cDNA clones. In general, these receptors are transmembrane proteins whose extracellular domains contain two immunoglobulin-like regions and are thus members of the immunoglobulin gene family. Their domain structure consists of a glycosylated extracellular domain, a single membrane-spanning segment, and a relatively long cytoplasmic domain. The cytoplasmic tails exhibit a surprising degree of variation in length and amino acid sequence. This review summarizes some recent information concerning the structure and expression of the Fc receptors found on murine and human macrophages and lymphocytes. Particular attention is paid to the functional activities of these receptors, and the possible relationship between receptor function and receptor structure.

Animals↗