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Biomedical subjects

R J Elin

Publications and source records attributed to R J Elin.

At least 163 records · Page 9Linked to original sources
PubMed1980

Effect of magnesium deficiency on erythrocyte aging in rats.

Rats placed on a magnesium-deficient diet show decreased erythrocyte magnesium concentration, shortened erythrocyte survival, and erythrocyte membrane ultrastructure defects and become progressively anemic. Whether these pathologic processes are due to abnormal erythropoiesis or occur in the peripheral circulation is unknown. In the present study, magnesium and hemoglobin concentrations, reticulocyte count, erythrocyte pyrophosphatase, and pyruvate kinase activities were determined at weekly intervals for 6 weeks in whole blood and age-dependent erythrocyte fractions isolated from inbred Fisher rats fed a diet deficient in magnesium or the same diet with added magnesium. Freeze-fracture electron microscopic examinations were performed on age-dependent erythrocyte fractions to evaluate the membrane defect. The youngest red cells from magnesium-deficient rats were similar to those of control animals with respect to erythrocyte magnesium concentrations, pyrophosphatase activities, and membrane morphology. The older erythrocyte fractions from magnesium-deficient rats showed significant decreases in magnesium concentrations, pyrophosphatase activity, and the presence of membrane abnormalities. Thus, new erythrocytes produced in magnesium-deficient rats appear to be normal but rapidly develop biochemical and morphologic abnormalities with aging in a magnesium-deficient plasma environment.

Animals↗
PubMed1979

A program for residency training in clinical pathology.

The goals, organization, components, instruction approaches, and the continuing assessment of a clinical pathology residency program are described. This program emphasizes training by rotation in the services of the clinical laboratory, application and interpretation of laboratory data for patient care, laboratory management, teaching conferences, and research and development.

Humans↗
PubMed1979

Microbiology subsystem of a total, dedicated laboratory computer system.

The computer system used by the Microbiology Service of the Clinical Pathology Department, Clinical Center, National Institutes of Health is discussed. This microbiology subsystem is a part of a dedicated on-line laboratory computer system used by the entire department. The laboratory computer is connected on-line to a hospital computer which provides patient admission, transfer, and discharge data. Mark sense worksheets and cathode ray tube terminals are used for result entry and correction. Cumulative patient reports are printed. Results for both active and completed accessions can be easily retrieved on cathode ray terminals in the laboratory. All laboratory data are archived on magnetic tape from which a research data base and microfiched laboratory records are generated. The manner in which the system is integrated in the routine operation of the microbiology laboratory is emphasized. In addition, some of the costs, benefits, liabilities, and pitfalls associated with the introduction of the computer in the laboratory are reviewed. Finally, we have presented our concept of some of the future enhancements to our present system and some of the directions in which any future microbiology system might develop.

Computers↗
PubMed1978

Lack of specificity of the limulus lysate test in the diagnosis of pyogenic arthritis.

The diagnosis of pyogenic arthritis may be difficult to confirm since culture results are sometimes negative. This study attempted to evaluate the utility of the limulus lysate assay for the early detection of pyogenic arthritis due to gram-negative organisms. Seven-one specimens of synovial fluid from 46 patients were evaluated for reactivity in the limulus test, pyrogenic responses in rabbits, total white blood cell count, total neutrophil count, total red blood cell count, and protein and glucose concentrations. All patients with culture-proven septic arthritis or presumptive septic arthritis had joint fluid specimens that yielded a positive result in the limulus assay (12 patients). However, 52.9% of patients (18 of 34) who had a nonseptic cause for their joint effusion also had a joint fluid specimen that was positive in the limulus test. A positive limulus test result showed a significant correlation with an elevated total white blood cell count (P less than 0.0005), an elevated absolute neutrophil count (P less than 0.0005), and a decreased concentration of glucose (P less than 0.005) in synovial fluid, and the production of fever in rabbits after injection of synovial fluid (P less than 0.05). Thus, this study suggests that a positive result in the limulus test on joint fluid is nonspecific for a septic process, but a negative result would be evidence against it.

Arthritis, Infectious↗
PubMed1978

The pyrogenicity of the synthetic adjuvant muramyl dipeptide and two structural analogues.

The pyrogenic efect of the synthetic adjuvant N-acetylmuramyl-L-alanine-D-isoglutamine, also known as muramyl dipeptide (MDP), was studied in rabbits. MDP induced biphasic fevers in rabbits, but two structural analogues, N-acetylmuramyl-L-alanine-D-glutamic acid (MDPA) and the dimethylester of MDPA, were 10 times less pyrogenic. This finding was supported by studies in which MDP and its analogues released leukocytic pyrogen (LP) from rabbit phagocytic cells in vitro. In addition, MDP released LP from human phagocytes. Human phagocytes, however, required a 10-fold greater concentration of MDP than did rabbit cells. The structural analogues were similarly less effective than the parent molecule in releasing LP from human cells. All preparations of MDP were negative in the limulus amebocyte lysate test and failed to show pyrogenic cross-tolerance with bacterial endotoxin. Thus MDP, which is a pyrogenic molecule, is also able to release LP from rabbit phagocytes and to a lesser degree from human phagocytes, but does not cause gelation of limulus amebocyte lysate.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1978

Changes in human serum amyloid A and C-reactive protein after etiocholanolone-induced inflammation.

Secondary amyloidosis is a complication of diseases characterized by recurrent acute inflammation. In this study, a standardized stimulus which induced fever and inflammation was given to six normal subjects (19-24 yr old) to follow the fluctuation in concentration of serum amyloid A (SAA), the precursor of the secondary amyloid fibril protein. After a single intramuscular injection of etiocholanolone (0.3 mg/kg), blood samples were drawn twice a day for 12 days for determination of SAA by solid phase radioimmunoassay. From a base line of <100 mug/ml, the SAA concentration began rising within 12 h to a maximum value at about 48 h of 1,350-1,800 mug/ml in three males and 380-900 mug/ml in three females and returned to base line by 4-5 days. The SAA response showed a similar time response to C-reactive protein (CRP), a well-documented acute phase protein which was assayed semiquantitatively by capillary tube precipitin reaction. CRP, but not SAA, showed a quantitative correlation with the amount of fever induced by etiocholanolone. One subject exhibited a second rise in SAA and CRP concentrations after acute over-indulgence with alcohol, suggesting that acute liver damage may have caused an acute phase reaction. Thus, a controlled episode of fever and inflammation produced a prompt and prolonged elevation of SAA and CRP concentrations. Unlike SAA, CRP has not been implicated in the pathogenesis of amyloidosis, although its relationship to the P component of amyloid has recently been established.

Amyloid↗
PubMed1978

Nitroblue tetrazolium and Limulus assays for bacteremia after dental extraction: effect of topical antiseptics.

Bacteremia that occurs after dental extraction is common. This study assessed the effect of topical antisepsis on the incidence and magnitude of post-extraction bacteremia. On hundred patients scheduled for elective tooth extraction were randomized among four groups: contr-l, mouthrinsing with sodium-p-toluene sulfonchloramide (chloramine-T), toothbrushing with chloramine-T, and irrigation with Lugol's solution. The results showed that 84% of the control group and 59% of the treatment groups had positive blood cultures (290 organisms isolated) after dental extraction. The duration and magnitude of these bacteremias were diminutive as documented by the six serial blood cultures taken for each patient, colony counts per milliliter of blood, and nitroblue tetrazolium and Limulus assays. Brushing the teeth or rinsing the mouth with chloramine-T before dental extraction significantly reduced the incidence of bacteremia (P less than .025) and the number of different organisms recovered from each patient (P less than .05). Thus, topical treatment with chloramine-T is a simple and effective means of reducing the incidence of postextraction bacteremia.

Adolescent↗
PubMed1978

Survival of normal and magnesium-deficient erythrocytes in rats: effect of magnesium-deficient diet vs. splenectomy.

Magnesium deficiency in rats causes anemia, the mechanism of which is unknown. The effect of dietary magnesium, splenectomy, and magnesium content of erythrocytes on erythrocyte survival was studied in Fisher rats. Half of the animals were splenectomized, the remainder sham-splenectomized; each group was subdivided, and some were placed on a magnesium-deficient diet, the rest on a control diet. After 6 weeks, each of the four subgroups was divided, half were given 51Cr-labeled red cells from magnesium-deficient rats, the remainder, labeled normal red cells. The survival functions of the labeled erythrocytes were fitted to a mathematical model composed of both first-order and accelerating components. The results show that the most important factor influencing erythrocyte survival was dietary magnesium intake. The magnesium content of the transfused red cells affected erythrocyte survival only in the rats fed the control diet, whereas splenectomy affected erythrocyte survival only in rats receiving the magnesium-deficient diet. The accelerating component of the survival function was increased eightfold in the animals fed the magnesium-deficient diet, whereas much smaller changes occurred in the first-order components.

Animals↗
PubMed1977

Effect of induced fever on serum iron and ferritin concentrations in man.

Previous reports have shown that endotoxin decreases serum iron in experimental animals. In this study fever was produced in nine female and nine male normal subjects in order to define the temporal and quantitative changes in serum iron and ferritin concentrations. Six volunteers were randomly given bacterial endotoxin (5 ng/kg) or saline intravenously and received the alternative compound a week later. Serial blood samples were drawn at 4-hr intervals for a 24-hr period, beginning when the compound was administered, for the determination of serum iron and ferritin concentrations. The same study was performed with intramuscular etiocholanolone (0.3 mg/kg) or the vehicle, propylene glycol, as a control, but the first blood sample was obtained 9 hr after the compound was given. In addition, blood samples were obtained at 12-hr intervals in six volunteers for 11 days after an intramuscular injection of etiocholanolone. The results showed a significant increase (p less than 0.005 for etiocholanolone, P less than 0.01 for endotoxin) in serum ferritin and a significant decrease (p less than 0.005 for etiocholanolone, p less than 0.001 for endotoxin) in serum iron for both pyrogenic compounds compared with the control compounds. However, the amount of fever and the changes in the iron parameters were greater with etiocholanolone. One episode of induced fever with etiocholanolone effected changes in serum ferritin and iron concentrations that lasted 10 days. Thus this study demonstrated that a single episode of fever in man produced rapid and prolonged changes in serum iron and ferritin concentrations.

Adult↗
PubMed1977

Detection of endotoxin in cerebrospinal and joint fluids by limulus assay.

Cerebrospinal fluid (CSF) and joint fluid from 81 patients were studied for the presence of endotoxin using the limulus assay. All fluids that grew Gram-negative organisms had a positive limulus test. However, one sample of CSF and one of joint fluid, both very purulent, that contained Gram-positive organisms also gave positive limulus assays. All culturally negative fluids had a negative limulus assay. Thus, a positive limulus assay with CSF or joint fluid is indicative of bacterial infection probably caused by Gram-negative organisms and can be an extremely useful diagnostic adjunct.

Adult↗
PubMed1977

Erythrocyte membrane plaques from rats with magnesium deficiency.

This study investigated the anemia of dietary magnesium deficiency in inbred Fisher white rats using freeze-fracture electron microscopy. The plasma membranes of erythrocytes from animals receiving two different magnesium-deficient and control diets were observed at weekly or biweekly intervals for 6 wk. The earliest changes were small plaques on the external surface (ES) and fracture face (PF) of erythrocyte plasma membranes, which occurred after 2 wk of either magnesium-deficient diet. These plaques persisted and increased in size with progressive magnesium deficiency. When fully developed, the plaques consisted of round or oval elevations approximately 30-50 nm in diameter outlined by a narrow raised border. The surface of the plaques was smooth and devoid of intramembranous particles. Incubation of erythrocytes from magnesium-deficient rats in a physiologic solution containing 2 meq/liter magnesium for 1 hr at 37degrees C did not alter the appearance of the plaques. Erythrocytes from control rats, obtained during the same time periods, showed no plaques. Thus, a deficiency of magnesium in rats altered erythrocyte membrane structure.

Animals↗
PubMed1976

Nonspecific resistance to infection induced in mice by a water-soluble adjuvant derived from Mycobacterium smegmatis.

The effect of a nontoxic, water-soluble adjuvant (Neo-WSA) from delipidated cells of Mycobacterium smegmatis on the susceptibility of mice to infection with four challenge organisms was studied. An intravenous dose of 1 mg of Neo-WSA per mouse 24 hr before challenge enhanced resistance to infection with a fungus (Candida albicans), a gram-negative bacterium (Klebsiella pneumoniae), and a gram-positive bacterium (Streptococcus pneumoniae). Protection by Neo-WSA was not significant when the mice were challenged with a malarial parasite. Plasmodium berghei. When 1 mg of Neo-WSA was given intravenously to mice 10 min before challenge with C. albicans, protection was significant, but when the same dose was given two or six days prior to challenge, mice were not protected. The concentration of iron in serum had not changed significantly 1 or 24 hr after the intravenous injection of 1 mg of Neo-WSA. Thus Neo-WSA is capable of inducing nonspecific resistance to certain experimental infections in mice. The protection afforded by administration of Neo-WSA 10 min before challenge, the lack of protection afforded by administration of Neo-WSA six days before challenge, and the lack of significant change in the serum iron concentration clearly separate this compound from bacterial endotoxins, which are classical inducers of nonspecific resistance to infection.

Adjuvants, Immunologic↗