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Biomedical subjects

J Savory

Publications and source records attributed to J Savory.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Measurement of lipid peroxidation products in rabbit brain and organs (response to aluminum exposure).

A method was developed for measuring the concentration of lipid peroxidation products in rabbit brain, heart, lung, liver, and kidney tissue. Specimens were homogenized in cold buffer, acidified, and heated to near boiling in the presence of thiobarbituric acid in order to form the malondialdehyde-thiobarbiturate adduct. After centrifugation, the supernatant was injected onto a reversed-phase high pressure liquid chromatography (HPLC) column, and the effluent was monitored for absorbance at 532 nm. Absorbances were compared to a standard curve constructed from absorbance data for tetraethoxypropane standards, which yield stoichiometric amounts of the malondialdehyde-thiobarbiturate adduct. Results were expressed as nmol of adduct per gram (dry weight) of tissue. Hippocampus had significantly greater concentrations of lipid peroxidation products (79.0 +/- 15.7 nmol per g) than did brainstem (52.1 +/- 13.8 nmol per g), but there was no significant increase in lipid peroxidation in aluminum treated rabbit brains when compared with controls. Aluminum intoxication appeared, however, to stimulate lipid peroxidation in heart, lung, liver, and kidney. Aluminum accumulation in brain and organ tissue of treated rabbits was confirmed by atomic absorption spectrophotometry of an acid digest of the homogenate. These results are in contrast to previous studies which demonstrated an increase in lipid peroxidation products in rat brains following oral administration of aluminum hydroxide.

Aluminum↗
PubMedDate not supplied

Adaptation of EMIT drug assays to a random-access automated clinical analyzer.

Enzyme multiplied immunoassay technique (EMIT) assays for theophylline, carbamazepine, phenytoin, phenobarbital, valproic acid, acetaminophen, gentamicin and tobramycin, have been adapted to the Technicon RA-1000 random access analyzer. Working reagents are stable for a period of at least one week, and calibration need only be performed when preparing fresh reagents. Between-day precision ranged from 2.2 to 5.5 percent and correlations with similar EMIT assays performed on a centrifugal analyzer were satisfactory. Excellent results were obtained on proficiency testing samples when analyzed for theophylline, phenobarbital, phenytoin and acetaminophen. The procedures have been adapted to emergency testing of these four drugs.

Autoanalysis↗
PubMedDate not supplied

Optimization and evaluation of cardiac enzymes and isoenzymes measured on a random access analyzer.

Four serum enzymes and isoenzymes used in the diagnosis of acute myocardial infarction (AMI), lactate dehydrogenase LD and LD-1, creatine kinase (CK), and CK-MB have been adapted to the Technicon RA-1000 automated clinical chemistry analyzer. Analytical parameters have been adjusted to provide clinically acceptable precision for all four assays. Correlations with centrifugal analyzer procedures gave correlation coefficients ranging from 0.998 to 0.999. A limited clinical study of the CK-MB assay indicated that a discriminant value of 13 U per L could separate AMI from non-AMI patients.

Autoanalysis↗
PubMedDate not supplied

Measurement and diagnostic value of cerebrospinal fluid enzymes.

The diagnostic value of cerebrospinal fluid (CSF) enzyme activities in neurological disorders has been evaluated most extensively with the enzymes aspartate aminotransferase (ASAT), lactate dehydrogenase (LDH), creatine kinase (CK) and lysozyme. Methods use for performing the assays have been similar to those employed for serum analysis. Reference intervals for these enzymes in the CSF are given from several sources and demonstrate much lower activities than in serum. Studies of these CSF enzymes in cerebral infarction, brain tumors, central nervous system (CNS) infections and acute brain injury and reviewed.

Adult↗
PubMedDate not supplied

New kinetic procedure for the measurement of conjugated bilirubin with a centrifugal analyzer.

A procedure has been developed for the automated measurement of conjugated bilirubin in serum with a centrifugal analyzer. The conjugated bilirubin is measured by a fixed time kinetic method which monitors the reaction between conjugated bilirubin and diazotized sulfanilic acid at 550 nm. Results are calculated based on a comparison of the reagent blank-corrected absorbance changes between 15 seconds and 75 seconds for sample vs changes in an empirical standard. The standard used is N-(1-naphthyl) ethylene diamine dihydrochloride (NEDC) which reacts with diazotized sulfanilic acid at a rate comparable to conjugated bilirubin. The standard is calibrated by comparison with a modified Jendrassik and Grof procedure using a serum blank-corrected centrifugal analyzer reference method. The method is linear to 150 mg per 1 with a sensitivity of 3.0 milliabsorbance units per 1.0 mg per 1 of conjugated bilirubin using a 35 mul sample volume. Within-run precision is 1 percent for elevated concentrations of bilirubin. Hemolysis introduces a negative interference, the nature of which is discussed.

Bilirubin↗
PubMedDate not supplied

Improved method for the measurement of pregnanetriol in urine.

A procedure for the measurement of pregnanetriol in urine by gas chromatography is described. The internal standard is added to the standards, controls and unknowns prior to the enzymatic hydrolysis of the steroid conjugates. Next, the hydrolyzed steroids are extracted from urine and converted to the volatile trimethylsilyl ether derivatives prior to gas chromatography. The initial addition of the internal standard appears to compensate for all procedural losses in this rather complex procedure. The intra- and interassay coefficients of variation at a level of 1.3 mg per liter were 5.3% and 11.8%, respectively. The method is linear to a pregnanetriol:internal standard ratio of 0.871. The analytical recovery for the method was 103 +/- 10.2%.

Chromatography, Gas↗
PubMedDate not supplied

Secondary hyperparathyroidism in chronic renal failure.

The metabolic bone disease associated with chronic renal failure has been described collectively by the terms "renal osteodystrophy" or "renal-glomerular-osteodystrophy" and consists of osteomalacia, osteitis fibrosa, and osteosclerosis. The skeletal abnormalities may occur either alone or in combination with one another. An increased concentration of circulating immunoreactive-parathyroid hormone (i-PTH) is a recognized feature of patients with chronic renal failure, and the values are usually much higher than those found in patients with primary hyperparathyroidism associated with a parathyroid adenoma. It must, however, be recognized that the high circulatory concentrations of parathyroid hormone found in patients with chronic renal failure are of immunoassayable material which may or may not be of biological significance in respect of activity. A disturbance in the homeostatic control mechanism governing parathyroid hormone, the secretion rate, its metabolism, and target organ resistance to its action are of major importance in the pathogenesis of some aspects of the metabolic bone disease in patients with chronic renal failure. The pathogenesis of the secondary hyperparathyroidism of chronic renal failure, however, also involves disturbances in cholecalciferol metabolism, phosphate retention, and the uremic state per se.

Calcium↗
PubMedDate not supplied

Vitamin D metabolism and chronic liver disease.

In recent years, considerable developments have taken place in the understanding of the vitamin D compounds which allows them, or at least their metabolites, to be classified as hormones. The liver has, for many years, entered into any consideration of the normal control of vitamin D status and metabolism in a number of roles. The main importance of the liver in vitamin D metabolism is now recognized to be the critical role it plays in the hydroxylation pathway and consequent formation of biologically active metabolites. Because the liver plays a critical central role in vitamin D metabolism, and possibly determines the overall efficiency of utilization, it may be expected that disorders of vitamin D metabolism, with associated clinical sequelae in the form of metabolic bone disease and hypocalcemia, and clinical features of patients with chronic disorders of liver function. The serum concentration 25-hydroxyvitamin D (25-OHD) is generally accepted as reflecting total body vitamin D status in patients with normal renal function. Low serum 25-OHD concentrations have been reported in patients with a variety of hepatic disorders including: symptomatic primary biliary cirrhosis, alcoholic liver disease, chronic active liver disease, and large bile-duct obstruction owing to carcinoma or stones. The mechanisms for the low circulating serum 25-OHD concentrations in patients with chronic liver disease are complex and multifactorial. The disturbances in vitamin D metabolism in patients with chronic liver disease and biliary disease are associated with disturbances in calcium homeostasis and together they present clinically as hepatic osteodystrophy. The latter consists of osteomalacia, possibly sometimes complicated by secondary hyperparathyroidism, osteoporosis, and periosteal new bone formation.

24,25-Dihydroxyvitamin D 3↗
PubMedDate not supplied

Prostaglandins and cancer.

This paper reviews the role of prostaglandins (PGs) in cancer. Specific topics of discussion include: (1) the potential use of PGs as tumor markers, (2) PG mediation of hypercalcemia of cancer, and (3) the use of PG synthesis inhibitors in cancer therapy.

Animals↗
PubMedDate not supplied

Frequency of calcium binding by monoclonal immunoglobulins in multiple myeloma.

Total and ionized calcium and other related parameters were measured in 34 patients with multiple myeloma. Hypercalcemia was not a major feature of the group of patients studied with only three patients exhibiting marked increases in total (Ca total) and ionized (Ca++) calcium concentrations. The Ca++/Ca total ratio was also maintained within relatively narrow limits. No major differences were found in the calcium fractions of patients with different types of multiple myeloma. Serum immunoreactive parathyroid hormone showed no consistent relationship with either the total or ionized calcium concentration. There were no correlations between increased total protein or reduced serum albumin concentrations and changes in total and ionized calcium fractions or Ca++/Ca total ratios. These results imply that in this group of myeloma patients, there was no significant binding of calcium by the monoclonal immunoglobulins.

Antibodies, Monoclonal↗
PubMedDate not supplied

Enzymatic assay for creatinine with fixed-time kinetics on a centrifugal analyzer.

A method is described for enzymatic measurement of serum creatinine using a centrifugal analyzer. The method employs fixed-time kinetics and a true serum blank. The method required 100 microliters of serum and is linear to 90 mg per L. Day-to-day precision studies revealed a standard deviation (coefficient of variation) of less than +/- 0.5 mg per L (7.4 percent) at a mean creatinine concentration of 6 mg per L and +/- 0.5 mg per L (1.8 percent) at a mean value of 28 mg per L. The method was free of interferences from acetoacetic acid, ascorbic acid, bilirubin, and hemoglobin. The speed, precision, and accuracy of the method suggest that it represents a useful alternative to methods using the alkaline picrate procedure.

Amidohydrolases↗
PubMedDate not supplied

Cerebrospinal fluid polyamines in childhood leukemia.

Cerebrospinal fluid (CSF) polyamines were measured in children with acute lymphocytic leukemia or non-Hodgkin's lymphoma in various stages of the disease ranging from complete remission to active central nervous system (CNS) involvement. Polyamines were analyzed by ion exchange chromatography with o- pthalaldehyde fluorimetric detection. Putrescine concentrations in random CSF samples obtained from leukemic patients with and without CNS involvement were not significantly different. Spermidine levels were generally higher in patients without CNS leukemia than in patients with the disease. In serial CSF specimens from an individual patient, spermidine levels correlated well with clinical status, being high in the active stages of the disease and low in remission. Thus, CSF polyamines appear to be of limited value as a screening test for early detection of CNS leukemia; however, they may offer an additional means of evaluating CNS leukemia and its response to therapy.

Adolescent↗