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Biomedical subjects

G Long

Publications and source records attributed to G Long.

At least 37 records · Page 2Linked to original sources
PubMed1994

Determination of sertraline and desmethylsertraline in human serum using copolymeric bonded-phase extraction, liquid chromatography and gas chromatography-mass spectrometry.

The determination of the new antidepressant drug sertraline and its main metabolite, desmethylsertraline, in human serum is described. A new solid-phase extraction method employing the dual functionality Clean Screen cartridge is presented followed by reversed-phase liquid chromatographic (LC) analysis. The sample preparation yielded extremely clean extracts and absolute recoveries in excess of 90% for both drugs from human serum. The response of the LC system was linear over the concentration range 0.01-2.5 mg/l for both sertraline and desmethylsertraline with a limit of detection of 0.01 mg/l. A gas chromatographic-mass spectrometric (GC-MS) system is also described should confirmation of the drugs be necessary.

1-Naphthylamine↗
PubMed1994

Confirmation of benzodiazepines in urine as trimethylsilyl derivatives using gas chromatography-mass spectrometry.

A confirmation procedure for the identification and quantitation of various benzodiazepines in urine is presented. The urine sample is first hydrolyzed enzymatically because of the glucuronide conjugation of some benzodiazepine metabolites, then extracted using bonded-phase columns. After elution into an organic solvent, the samples are evaporated, converted to the trimethylsilyl ether derivatives and analyzed by electron ionization GC-MS. Quantitation was performed using selected-ion monitoring for each benzodiazepine using prazepam as the internal standard. The method provides excellent linearity and sensitivity for the trimethylsilyl derivatives.

Benzodiazepines↗
PubMed1994

Isolated renal mucormycosis.

OBJECTIVE: To report a case of isolated renal mucormycosis in a previously healthy man, and to briefly review the literature relating to this rare condition. CLINICAL FEATURES: An 18-year-old man presented with a two-month history of fevers followed by two weeks of severe left loin pain. Initial treatment with antibiotics failed and abdominal computed tomography and renal perfusion scans were requested, demonstrating a non-functioning left kidney. INTERVENTION AND OUTCOME: Nephrectomy was performed, the histology of which was consistent with mucormycosis. Amphotericin B was administered for one month. The patient made a complete recovery and no underlying disorder was found. CONCLUSIONS: This man is believed to be the first reported Australian with isolated renal mucormycosis, and only the second person worldwide in whom an identifiable underlying disorder was absent.

Adolescent↗
PubMed1994

Measurement of long-range2 13C-1H coupling constants of 95% uniformly 13C-labeled polysaccharide from Streptococcus mitis J22.

The coaggregation of Streptococcus mitis strain J22 in the early stages of dental plaque formation has been shown to result from interaction of cell wall polysaccharides with lectins on the surface of other oral bacterial species. This bacterium was grown in a medium containing 13C as the sole carbon source. We have isolated the lectin receptor polysaccharide from this strain with full enrichment in 13C and have determined a number of two-bond and three-bond 13C-1H coupling constants from measurements of the offsets in two-dimensional homonuclear nmr spectra [exclusive correlated spectroscopy (E-COSY) method]. A scheme for reliable extraction of these coupling constants from homonuclear Hartmann-Hahn and nuclear Overhauser effect spectroscopy spectra is tested in model compounds. We interpret the three-bond coupling across the glycosidic linkage in terms of dihedral angles in order to provide conformational information to supplement molecular modeling and nuclear Overhauser effect data. We show that the E-COSY method works well even for coupling constants smaller than the nmr line width and that a number of the 3JCH across the glycosidic linkage are in the range of 1-2 Hz, which is much smaller than many previously reported values.

Carbohydrate Conformation↗
PubMed1994

The Classroom Communication Ease Scale. Development of a self-report questionnaire for mainstreamed deaf students.

This study describes efforts to develop a self-report psychological scale (CCES: Classroom Communication Ease Scale) to provide information about the extent to which mainstreamed deaf students think that they communicate effectively with teachers and peers, as well as how they feel about their communication experiences in mainstreamed classrooms. Data obtained from administration of the CCES to 50 deaf students enrolled in baccalaureate programs at a postsecondary technical institution were subjected to Rasch rating scale analysis. Fit of data to the measurement model resulted in a set of 42 items that empirically define the concept of "communication ease" in its cognitive aspects and a set of 21 items that elaborate the concept further in terms of its affective aspects.

Adolescent↗
PubMed1992

Reading comprehension test item difficulty as a function of cognitive processing variables.

This study reports the results of a componential analysis of items comprising Sections A and C of Form Z of the reading comprehension portions of the California Achievement Tests (CAT) (Tiegs & Clark, 1963). A set of problem components or attributes characterizing the test items in terms of manifest content, psychologically salient features, and processing demands was developed, including methods for their quantification. The contributions of these components to task difficulty were then evaluated using linear regression methodology. Item difficulty indices were transformations of the familiar proportion-correct item score, obtained from data gathered during the spring of 1989 from 158 deaf examinees. Variation in the item difficulty values was substantially accounted for in terms of a small number of predictor variables (R2 greater than or equal to .90). Implications of the results for construct validity and interpretation of test scores are discussed.

Cognition↗
PubMed1992

Serum erythropoietin levels and blood component therapy after autologous bone marrow transplantation: implications for erythropoietin therapy in this setting.

To determine the potential impact of recombinant human erythropoietin (EPO) therapy in patients undergoing autologous bone marrow transplantation (BMT) and colony-stimulating factor therapy, we assayed endogenous serum EPO levels and noted blood transfusion requirements in relapsed non-Hodgkin's lymphoma patients treated with high-dose chemo-radiation therapy and autologous BMT. Hematocrit and reticulocyte counts were determined daily, and hematocrit was maintained in the 25-30% range by transfusion according to criteria established by our hospital transfusion committee. EPO levels were measured by radioimmunoassay and were determined at baseline, throughout therapy, and 2 and 3 months after BMT. Serum EPO levels increased more than 25-fold above baseline in most subjects after initiating chemoradiation therapy. No correlation was noted between serum EPO and hematocrit, reticulocyte count or serum creatinine. Total red blood cell units transfused ranged from 4 to 15 (mean 7.7). Mean total donor exposures (red blood cell plus platelet units transfused) were 83.6 units (range 16-175). Serum EPO levels increased early in the course of preparation for autologous BMT and remained elevated for at least 2-3 weeks thereafter although at a lower level. Red blood cell transfusions were required despite very high EPO levels after BMT. Red cell transfusions, moreover, accounted for only 9.2% (69 of 746) of total donor exposures and only 5.8% (42 of 746) of donor exposures during the interval when pharmacologic doses of erythropoietin might be of benefit. In contrast to the potential benefit of colony-stimulating factors such as G-CSF and GM-CSF in BMT, our study suggests limited value for erythropoietin therapy in this setting.

Adult↗
PubMed1991

Effect of cilazapril in hypertensive patients with renal impairment.

The aim of the study was to evaluate the clinical and renal hemodynamic effects of cilazapril in 10 hypertensive patients with moderate-to-severe chronic renal failure (creatinine clearance 14-50 ml/min). After 2 weeks of placebo, cilazapril 0.5 mg/day was given, and the dose was increased up to 5 mg/day if sitting diastolic blood pressure (SDBP) was not normalized (less than or equal to 90 mm Hg). Once a normal SDBP value was achieved, the patients remained on the given dose regimen for 6 months. After this period SDBP decreased from 107 +/- 2 to 95 +/- 2 mm Hg (p less than 0.001). At the end of treatment, glomerular filtration rate (GFR) remained unchanged in five patients, improved in four patients, and slightly decreased in one patient, the slope from baseline being 0.137 and the variation of GFR per unit of GFR at baseline being between -0.20 and 0.47. Likewise, effective renal plasma flow increased not significantly, showing considerable variability. Urinary protein excretion was reduced significantly from 2.51 +/- 0.75 to 0.51 +/- 0.10 g/L (p less than 0.05), suggesting that converting enzyme inhibition may exert a renal protective effect. In conclusion, it appears that cilazapril does not induce functional damage in the kidney of predialysis hypertensives.

Adult↗
PubMed1991

Students' perceptions of communication ease and engagement. How they relate to academic success.

The extent to which students' self-perceptions of communication ease and engagement relate to their academic achievement was assessed in a study of 95 high school students enrolled in a large urban school for the deaf. Four dimensions of classroom communication were measured: students' understanding of teachers, students' understanding of peers, and positive and negative feelings about communication at school. Engagement, the extent students report being excited and actively involved in the classroom, predicted only teacher-assigned grades when the variance of background variables such as residual hearing and IQ was removed. However, communication ease made a significant contribution to the prediction of the three standardized achievement test scores, as well as grades, when background variance was removed. The results suggest that students are more likely to learn if they perceive themselves as being effective in communicating and have positive feelings about the communication that occurs.

Adolescent↗
PubMed1991

Effects of ACE inhibition on renal haemodynamics in essential hypertension and hypertension associated with chronic renal failure.

Angiotensin II has many actions in the kidney, including regulation and distribution of renal circulation and glomerular filtration, as well as effects on mesangial contraction and on the filtration coefficient. The reduction in circulating and intrarenal angiotensin II by angiotensin converting enzyme (ACE) inhibitors in essential hypertension is associated with a significant increase in renal blood flow and a decrease in filtration fraction, without changes in glomerular filtration rate. In addition, administration of ACE inhibitors can reduce proximal sodium reabsorption via changes in peritubular hydrostatic and oncotic forces resulting from the fall in postglomerular capillary resistance. In severe hypertension the state of the renal vasculature does not allow ACE inhibition to induce similar haemodynamic changes and, therefore, it cannot contribute to renal sodium handling that requires the recruitment of alternate mechanisms. In spite of this, ACE inhibitors may exert a protective effect on the renal function of patients with severe hypertension as well as in those with renal impairment, by lowering systemic and, probably, intraglomerular pressure, reducing proteinuria and slowing the progression of renal failure.

Adolescent↗
PubMed1985

Dose-response toxicity studies on tributoxyethyl phosphate orally administered to Sprague-Dawley rats.

The response of the peripheral nervous system to various dose levels of tributoxyethyl phosphate (TBOP) was investigated in Sprague-Dawley rats. Groups of randomized female and male rats (10 rats/gender/dose level) were administered a single oral dose of TBOP (1.0 to 3.2 g/kg for females; 1.0 to 9.0 g/kg for males). Physiological parameters were measured in surviving rats three weeks following TBOP administration. A significant reduction (p less than 0.05) in caudal nerve conduction velocity (NCV) was observed in both female and male rats. Light and electron microscopic examination of sciatic nerve sections showed degenerative changes in both myelinated and unmyelinated fibers of female (2.0 g/kg) and male (6.8 g/kg) groups. Advanced degeneration was observed only in the highest dose level of both genders (3.2 g/kg for females; 8.0 and 9.0 g/kg for males). Although similar morphological changes were observed in both genders, females were more susceptible than males to the toxic effects of this compound.

Administration, Oral↗
PubMed1984

Induction of electrophysiological and morphological changes in Sprague-Dawley rats fed tributoxyethyl phosphate.

The effects of a widely used trialkyl phosphate (TP), tributoxyethyl phosphate (TBOP), on the peripheral nervous system of Sprague-dawley (SD) rats were investigated. Male and female SD rats were administered this chemical by gavage over a period of 18 weeks (low dose: 0.25 ml kg-1; high dose: 0.50 ml kg-1). Electrophysiological changes observed at 18 weeks in all test animals included a significant reduction (P less than 0.001) in nerve conduction velocity and an important increase (P less than 0.001) of both relative (RRP) and absolute refractory period (ARP). Light and electron microscopic examination of sciatic nerve from all test animals showed the presence of degenerating myelin sheaths accompanied by axonal swelling. An advanced stage of degeneration was indicated by the presence of lamellated electron dense inclusions in unmyelinated nerve fibres.

Animals↗