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Biomedical subjects

D Nguyen

Publications and source records attributed to D Nguyen.

At least 145 records · Page 8Linked to original sources
PubMed1988

Interlaboratory comparison of antisera and immunoassays for benzo[a]pyrene-diol-epoxide-I-modified DNA.

An interlaboratory comparison of immunoassays using antisera elicited against benzo[a]pyrene-diol-epoxide-modified DNA (BPDE-I-DNA) was carried out resulting in standardization of antisera, competitors and assay conditions. The assays used included competitive enzyme-linked immunosorbent assays (ELISA) with color and fluorescence endpoint detection and an ultrasensitive enzyme radioimmunoassay (USERIA) with a radioactive endpoint. Three different antisera were compared, two of which were obtained from different rabbits immunized with the same BPDE-I-DNA and a third from an animal immunized with another BPDE-I-DNA sample. Samples of standardized BPDE-I-DNA with high (36 pmol adduct/microgram DNA; 1.2 adducts/10(2) nucleotides) and low (4.5 fmol/microgram DNA; 1.5 adducts/10(6) nucleotides) modification levels were prepared and used in each laboratory. The antisera were all elicited against DNAs modified to a high extent, and it was therefore not surprising that they detected adducts in a slightly modified DNA sample with lower efficiency than those in highly modified DNA samples. The discrepancy of antibody recognition between the highly and slightly modified samples varied between 1.4- and 11.2-fold depending on the antiserum and assay. To ascertain the quantitative capability of the immunoassays, the modification level of DNA isolated from mouse keratinocytes treated with [3H]benzo[a]pyrene was determined by radioactivity and immunoassay. These results indicated that when a biological sample is assayed against a BPDE-I-DNA standard modified in the same range as the biological samples (4.5 fmol/microgram), quantitative recovery of adducts is achieved by immunoassay. These studies resulted in the realization that interlaboratory differences in immunoassay procedure can have significant consequences for data comparison and that where possible it is preferable for laboratories to use the same antisera and modified DNA standards.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1988

Effects of dietary electrolyte supplementation on gentamicin nephrotoxicity.

The effects of electrolyte supplementation via drinking solutions on gentamicin-induced nephrotoxicity were studied in rats. Four groups of animals were injected with gentamicin, 120 mg/kg daily for 5 days and were studied 2-4 days after the last injection. Electrolyte supplements were begun before the gentamicin injections and were continued throughout the study. The drinking solutions were tap water, NaCl, NaCl + KCl, or NaHCO3 + KHCO3 + diamox. At the end of the study, blood urea nitrogen (BUN) and serum creatinine were markedly increased only in the group receiving tap water. Nevertheless, 24 hour creatinine clearance in awake rats and inulin clearance in anesthetized rats were found to be severely reduced in all gentamicin-treated animals. However, the rats receiving NaHCO3 + KHCO3 + diamox had significantly higher creatinine clearance than all other experimental groups. Proximal intratubular free-flow pressure, measured by micropuncture, and internal proximal diameters were significantly increased above normal controls in all groups, but were least abnormal in the rats receiving HCO3- and diamox. Semiquantitative histologic evaluation revealed significantly less tubular necrosis and cast formation in this group than in all the other experimental groups. The observations suggest that dietary sodium, potassium, and chloride supplements, even accompanied by large fluid intake, provide relatively little protection against gentamicin nephrotoxicity. In contrast, HCO3- and diamox supplements resulted in significant, albeit incomplete, protection of GFR and renal histology.

Animals↗
PubMed1988

The effect of bearing tumours on the ability of mice to reject bone marrow transplants.

To examine the possible relationship between the cells mediating resistance to tumour cells and those mediating rejection of foreign bone marrow transplants (BMT), the effect of tumour-bearing on BMT rejection has been measured by means of the spleen colony assay. Moderate doses (less than 5.0 X 10(6] of bone marrow cells from DBA/2 strain mice, which normally produce few haemopoietic spleen colonies in gamma-irradiated (950R) CBA/J strain mice, gave numerous (confluent) colonies when given soon after injection of Ehrlich ascites tumour (EAT) cells. Transfusion of [3H]UdR-labelled DBA/2 bone marrow cells demonstrated that the increased spleen colony formation in tumour-bearing mice was not due simply to changes in the total number of injected cells homing to the spleen. Injection of EAT ascites fluid alone, given to CBA/J mice before 950R + BMT, transiently reduced spleen colony development, the effect being more marked when fluid from older tumors was used. Supernatant fluid from EAT cells grown in vitro also depressed growth of BMT in vivo. The results reveal two processes in progress in mice bearing an ascites tumour: (1) an early reduction in the natural resistance to BMT allowing successful grafting and spleen colony formation, and (2) a progressive production by the tumour cells of short-acting soluble factors tending to suppress the proliferation of colony forming bone marrow cells in the transplant. The effect of the tumour-bearing state in weakening the natural resistance to foreign BMT strongly suggests that both tumour and foreign marrow graft resistance are mediated by the same or closely related effector cells.

Animals↗
PubMed1988

In situ hybridization analysis of macrophage-derived tumor necrosis factor and interleukin-1 mRNA.

Tumor necrosis factor (TNF) and interleukin-1 (IL-1) play an intimate role in the initiation and maintenance of inflammatory reactions due to their pluripotent activities. In this paper, we describe the use of an in situ hybridization analysis as an effective means to probe for TNF and IL-1 mRNA levels in primary macrophage cultures and macrophage cell lines. A significant increase in lipopolysaccharide (LPS)-induced TNF mRNA accumulation was demonstrated by in situ hybridization using either a 35S-labeled synthetic oligonucleotide (30-mer) complementary to TNF mRNA or a 35S-randomly primed labeled TNF DNA probe. An augmentation in TNF mRNA accumulation, as assessed by increasing grains/cell, was demonstrated over a wide concentration range of LPS. This accumulation was shown using both immunologically elicited primary macrophage cultures and the macrophage cell line RAW 264.7. Interestingly, the RAW 264.7 constitutively produced TNF in the absence of specific stimulus and this tonic production was observed at the molecular level via in situ hybridization analysis. Specificity of the in situ hybridization technique was shown by a complete loss in binding of 35S-probe after either RNase digestion or competition with "cold-labeled" probe. beta-actin served as a 35S-labeled control probe where the number of actin-specific grains/cell was not altered by stimulating macrophages with LPS. IL-1 alpha mRNA was also increased by LPS stimulation of macrophages as assessed by in situ hybridization. The LPS-dependent increase in macrophage mRNA for TNF and IL-1 alpha, as assessed by in situ hybridization, was confirmed by classical Northern blot analysis as well as the production of biologically-active protein.

Animals↗
PubMed1987

DMSO potentiates aminonucleoside of puromycin nephrosis in rats.

Dimethyl sulphoxide (DMSO), 3 g/kg body weight, administered daily by the intraperitoneal route, potentiated the proteinuria and formation of tubular casts in aminonucleoside of puromycin (PA) induced nephrosis in Sprague-Dawley rats. The effect was evident at 4 as well as 8-9 days following PA administration. In the absence of PA, DMSO did not induce proteinuria or cast formation. The mechanism by which DMSO enhanced proteinuria and cast formation is not known.

Animals↗
PubMed1987

Evidence against increased glomerular pressure initiating diabetic nephropathy.

Studies were carried out to determine whether exaggerated glomerular hydraulic pressure (PG) initiates the development of glomerular pathology and proteinuria in insulin-dependent diabetic rats. Normotensive (WKY) and hypertensive rats (SHR) were made diabetic by streptozotocin injection. One group of SHR diabetic rats was treated with antihypertensive drugs to reduce blood pressure. One week after onset of diabetes, micropuncture determinations of PG, measured by stopped-flow technique, revealed that PG was higher in WKY diabetics than in non-diabetic WKY controls, and that PG was even higher in SHR diabetics (P less than 0.05). Similarly prepared groups of animals were followed for six months, approximately one fifth to one third of the expected life span of these rats. Tail systolic blood-pressure measurements documented continuous severe systolic-hypertension in SHR diabetics, normal pressure in the WKY diabetics and hypotension in the SHR diabetics treated continuously with antihypertensive drugs. Urinary protein excretion, measured monthly, was statistically the same in all groups, with no evidence of a progressive rise in the SHR diabetics. PG measured in two rats from each group after four months of diabetes was similar to values found after one week of diabetes. Semiquantitative histologic scoring of glomerular mesangial expansion after six months of diabetes failed to demonstrate any significant difference between the normotensive WKY diabetics and the hypertensive SHR diabetics. These observations suggest that elevated PG does not in itself initiate glomerular pathology or proteinuria in diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Prostacyclin and thromboxane A2 in septic shock: species differences.

Prostacyclin and thromboxane A2 have been implicated as mediators of septic shock. Correlations between the human prostanoid response to sepsis and experimental paradigms are poorly understood. The purpose of this study was to compare changes in plasma levels of prostaglandin 6-keto-F1 alpha (PGI) and thromboxane B2 (TxB) during septic shock in Sprague-Dawley rats, domestic pigs, mongrel dogs, and man. Severe sepsis followed by septic shock (systolic BP less than 90 mmHg) was induced in rats by inoculation of 1.0 X 10(9) Aeromonas hydrophila, in pigs by graded IV infusion of 1.0 X 10(9)/ml A. hydrophila; and in dogs by an IV bolus injection of 5.0 X 10(9)/ml Escherichia coli. Plasma PGI and TxB (pg/ml) were measured by radioimmunoassay in control, septic, and septic shock experimental blood samples, and in normal controls, severly septic, and septic shock (systolic BP less than 90 mmHg) S.I.C.U. patients. Control, septic, and septic shock TxB levels in the dog and the pig were significantly greater than in the rat and man. PGI levels in the dog were significantly greater than in other species. TxB increased significantly in murine sepsis and PGI increased significantly in sepsis and septic shock. TxB increased during porcine sepsis and septic shock. In man, both PGI and TxB were significantly increased in severe sepsis, compared to normal controls, but only PGI was significantly higher in septic shock versus normotensive sepsis. Patterns of change in TxB/PGI ratios were similar for all species studied. Changes in PGI in the porcine septic experiments most closely paralleled those observed clinically.

Animals↗
PubMed1985

Culture shock--a review of Vietnamese culture and its concepts of health and disease.

Misunderstandings of Vietnamese culture and beliefs have led to many unfortunate incidents in the United States, including court cases for child abuse and even suicide. These can be avoided by an awareness of the cultural background of the Vietnamese, their philosophy of life and the influence of religion and beliefs on their personalities, both as individual persons and as members of extended family units. The Vietnamese concepts of health and disease are presented, along with brief descriptions of certain folk medicines that are frequently misconstrued by American physicians.

Asian↗
PubMed1984

Gonorrhea in pregnancy and in the newborn.

Prevalence rates of gonorrhea in pregnancy range from 0.2 to 15 percent. Pharyngeal gonorrhea is more frequent in some prenatal populations. A degree of protection against pelvic inflammatory disease occurs in pregnancy, but there is an increased risk for disseminated gonococcal infection. Maternal gonococcal infection is associated with ectopic pregnancy, prematurity and ophthalmia neonatorum. Prompt and aggressive treatment is required for ophthalmia neonatorum.

Anti-Bacterial Agents↗
PubMed1981

Intestinal parasites in Indochinese immigrants.

Fifty-two percent of 419 recent Indochinese refugees, most of whom were studied because they had symptoms, signs, or hematologic findings suggestive of parasitism, had intestinal parasites. The frequency of parasitism was comparable in Vietnamese vs. other Indochinese (Cambodians and Laotians), but other Indochinese were more often found to have multiple parasites. The most common parasite in Vietnamese was Ascaris lumbricoides, hookworm was the most common parasite in Cambodians and Laotians, and opisthorchid flukes were only found in Laotians. Age and sex were not related to infection except for Giardia, which has more prevalent in children. Based on public or personal health hazards and treatability, 33% of patients had parasites judged to warrant therapy, even in a clinically normal host.

Ambulatory Care Facilities↗
PubMed1979

Size of the pool of alveolar neutrophils in normal rabbit lungs.

Morphometric methods and two unique characteristics of neutrophils enabled us to measure the size of the pool of neutrophils in alveoli of rabbit lungs. Rabbit lungs contained an estimated 6.11 x 10(4) alveolar neutrophils/g wet wt of lungs, and 9.57 x 10(5) alveolar neutrophils/rabbit. Lung lavage was successful in removing an average of 42.2% of the neutrophils in the air containing spaces of the lungs. An average of 2.5 +/- 3.5 (SD)% of the cells in the lung washes were neutrophils, but an average of 10.23 +/- 5.0 (SD)% of the cells that were free in the alveolus were neutrophils. Studies of the interaction of alveolar macrophages and neutrophils in vitro showed that neither cell phagocytoses or destroys the other in significant quantities; however, alveolar macrophages containing neutrophils have been observed.

Animals↗
PubMedDate not supplied

Slipped capital femoral epiphysis: rationale for the technique of percutaneous in situ fixation.

In pinning a slipped capital femoral epiphysis (SCFE), the position of the pin within the center of the femoral head is important for two reasons. The pin may disrupt the lateral epiphyseal artery and cause avascular necrosis (AVN), or pin penetration in certain locations may go unrecognized on radiographs. To place the pin accurately, the surgeon must be aware of where the femoral head lies in relation to the femoral neck and the shaft. Radiographs of models and of patients in various positions support the view that the femoral head in most cases of chronic SCFE rotates around the axis of the femoral neck and does not slip inferiorly. Therefore, the starting point for an in situ fixation device is the anterior femoral neck, the exact location depending on the amount of slipping.

Bone Nails↗
PubMedDate not supplied

Reinfusion of mediastinal blood in CABG patients: impact on homologous transfusions and rate of re-exploration.

BACKGROUND: Reinfusion of mediastinal shed blood after cardiac surgery has been used in some centers to reduce exposure to homologous blood transfusions. The method has not been widely applied mostly because some studies have failed to demonstrate a significant benefit. METHODS: A group of 675 consecutive patients undergoing first-time, isolated coronary artery bypass surgery (CABG) was studied. Prospective data was collected on the first 375 patients receiving autotransfusion (ATS) of mediastinal shed blood. The charts of 338 patients immediately preceding the institution of the ATS program at our institution (NO ATS group) were retrospectively reviewed. Transfusion of homologous blood products and rate of re-exploration for bleeding were closely monitored. RESULTS: The two groups were identical. The net blood loss was significantly less in the ATS group than in the NO ATS group (1013 +/- 431 cc vs 1371 +/- 631 cc, p < 0.0001). Rate of exploration for postoperative bleeding was 1.5% in the ATS group and 5.0% in the NO ATS group (p < 0.01). In the ATS group, 51.9% of patients were not exposed to any homologous blood product (vs 17.8% in the NO ATS group, p < 0.0001). The ATS patients received on the average 2.9 +/- 7.2 units of blood products versus 6.4 +/- 9.7 units in the NO ATS group (p < 0.0001). CONCLUSION: Reinfusion of mediastinal shed blood significantly reduces exposure to homologous blood transfusions and rate of reexploration. The ATS system reduces the number of re-explorations for coagulopathy-related postoperative hemorrhage.

Blood Loss, Surgical↗