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D Naidoo

Publications and source records attributed to D Naidoo.

34 records · Page 2Linked to original sources
PubMed1995

Electrical resistance and macromolecular permeability of retinal capillary endothelial cells in vitro.

This study was undertaken to examine the ability of retinal capillary endothelial cells to retain blood-retinal barrier properties in vitro. Second passage bovine retinal capillary endothelial cells were grown to confluence on polycarbonate filters in two chamber systems coated with laminin, fibronectin and type IV collagen. The electrical resistances, permeability of 3H-insulin and expression of blood-brain barrier related enzymes by retinal cells was observed and compared with bovine aortic endothelial cells and bovine fibroblasts. The electrical resistance of retinal cells rose over the first week of culture, peaking after 5-9 days in culture. In eleven separate experiments (n = 5 for each experiment) the average peak resistance of retinal endothelial cells ranged from 89.3-186.6 with a mean average of 129.0 ohm.cm2. In one of these experiments, the peak electrical resistance of retinal cells was 149.0 +/- 10.3 compared with 34.8 +/- 6.8 for aortic cells and 37.8 +/- 3.8 ohm.cm2 for fibroblasts. The permeability coefficients of inulin were: retinal cells 0.17 +/- 0.09, aortic cells 3.47 +/- 1.58 (p = 0.015), fibroblasts 3.93 +/- 0.78 (p = 0.002) x 10(-6) cm/sec. Retinal cells expressed significantly higher activities of gamma-glutamyl transpeptidase and alkaline phosphatase than the other cell types. Treatment of the monolayers with the calcium ionophore, A23187, resulted in a reversible increase in permeability as has been described for peripheral vascular endothelium. We conclude that BRCEC retain at least some of their specialised barrier properties in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1994

Neonatal plasma vitamin K1 levels following oral and intramuscular administration of vitamin K1.

Vitamin K1 levels were measured by high performance liquid chromatography in cord blood (n = 33) and at the age of 97-120 h after administration of 2 mg of vitamin K1 orally (n = 88) or 1 mg of vitamin K1 by im injection (n = 88). Vitamin K1 levels were less than 0.05 micrograms/l in cord blood. The mean (range), SEM, mode and median values (micrograms/l) for the infants given oral vitamin K1 were 17.99 (1-56), 1.25, 8 and 15.5 and those for the infants given im vitamin K1 15.83 (2-57), 1.01, 11 and 14, respectively. The t-test showed no significant difference in the mean values (p = 0.09) in the infants given oral or im vitamin K.

Administration, Oral↗
PubMed1993

A simple collection method for saliva in children: potential for home monitoring of carbamazepine therapy.

We have developed a method of monitoring plasma concentrations of antiepileptic drugs which uses salivary samples, and is suitable for home monitoring in children. To validate the method, paired plasma and saliva samples from 39 children aged between 2 and 15 years were assayed for carbamazepine and its active metabolite, carbamazepine-10,11-epoxide by h.p.l.c. The method uses a gauze-wrapped cotton ball with attached string, to absorb saliva which is then separated using a syringe and plunger. There was no adsorption of CBZ and CBZ-E and they were stable over 1 month in a domestic freezer. Plasma and salivary free CBZ and CBZ-E concentrations were highly correlated (r2 = 0.99 and 0.98, respectively).

Adolescent↗
PubMed1992

Interferon induction in porcine leukocytes with transmissible gastroenteritis virus.

Leukocytes were harvested from the peripheral blood, mesenteric lymph node and small intestinal lamina propria from groups of three piglets before, and 1, 2 and 3 weeks after infection with virulent transmissible gastroenteritis virus (TGEV) at 2 weeks of age. The donor piglets developed clinical signs of transmissible gastroenteritis which persisted for up to 3 days, and they developed peak serum titres of TGEV-neutralizing antibodies 2 weeks post-infection. The leukocytes were cultured in the presence of pokeweed mitogen (PWM), various dilutions of purified TGEV, or control media for 3 or 5 days, and the culture supernatants were tested for antiviral activity in MDBK cells challenged with vesicular stomatitis virus. The antiviral activity was characterized as porcine interferon (IFN)-alpha or porcine IFN-tau on the basis of its stability at pH 2.0 and neutralization by anti-human IFN-alpha antibodies. Viability of the leukocytes in culture, determined by trypan blue exclusion, was highest for the peripheral blood leukocytes and lowest for the mesenteric lymph node leukocytes. There were no consistent differences in antiviral activity between cultures incubated for 3 or 5 days. Porcine IFN-alpha was found in the supernatants of the leukocyte cultures stimulated with TGEV antigen, harvested before or after infection of the donor piglets with TGEV. Porcine IFN-tau was demonstrated in the supernatants of the leukocyte cultures stimulated with PWM, more frequently when the leukocytes were harvested post-infection. This was the first demonstration of IFN induction in vitro in leukocytes from porcine gut-associated lymphoid tissue.

Animals↗
PubMed1992

Transmissible gastroenteritis virus antibody production in vitro by porcine peripheral blood leukocytes.

The purpose of this study was to demonstrate the in vitro production of transmissible gastroenteritis virus (TGEV)-specific antibodies by peripheral blood leukocytes (PBL) harvested from piglets infected with TGEV. Piglets were infected with the virulent Purdue strain of TGEV and at intervals postinfection their PBL were cultivated in the presence of TGEV antigen, control antigen or pokeweed mitogen (PWM). The culture supernatants were tested for TGEV antibodies by a fixed cell enzyme immunoassay. Antibodies were never found in the supernatants of unprimed PBL cultures from control piglets, nor in cultures stimulated with control antigen, and antibodies were produced more frequently in response to stimulation of primed PBL with viral antigen than with PWM. In PBL cultures stimulated with viral antigen, TGEV antibodies of the IgG class were produced more frequently than IgA class antibodies. Optimal antibody responses were produced by PBL harvested two weeks after infection and cultivated at a concentration of 10(7) cells/mL for five days.

Animals↗
PubMed1988

Allopurinol dosage selection: relationships between dose and plasma oxipurinol and urate concentrations and urinary urate excretion.

1. Allopurinol usage in 50 patients of a city teaching hospital was surveyed. 2. The plasma concentrations of oxipurinol and uric acid and the urinary production of uric acid were examined. 3. The daily doses of allopurinol ranged from 50 to 1200 mg but 83% of patients were taking 300 mg daily. 4. A wide range of plasma oxipurinol concentrations was observed from 2.8 to 55.8 mg l-1 with a mean +/- s.d. of 15.2 +/- 11.7 mg l-1. 5. The population studied included a high proportion of patients with renal impairment and creatinine clearance was a significant determinant of oxipurinol concentrations (P less than 0.005). 6. There was no significant correlation between plasma urate and plasma oxipurinol concentrations and only a few plasma urates were above the upper limit of the reference range of the laboratory. 7. It was apparent that many patients were taking unnecessarily high daily doses of allopurinol and that renal status was not always considered when deciding dosage regimens of allopurinol.

Adult↗
PubMed1983

Cyclosporin A associated nephrotoxicity in the first 100 days after allogeneic bone marrow transplantation: three distinct syndromes.

Thirty-six patients received allogeneic (34) or syngeneic (two) bone marrow transplants as treatment for severe aplastic anaemia or acute leukaemia. Nineteen of the allogeneic recipients received methotrexate (MTX) and 15 received cyclosporin A (CyA) as the predominant immunosuppressive agent to minimize graft-versus-host disease (GVHD) post transplant. In the first 100 d post transplant renal dysfunction was much less frequent in the MTX recipients than in the CyA recipients who exhibited three distinct syndromes of nephrotoxicity: most commonly. CyA recipients developed asymptomatic azotaemia, proteinuria, urinary casts, impaired urinary concentrating ability and hypertension. Secondly, two CyA recipients developed acute reversible renal failure precipitated by systemic bacterial infection which required dialysis and in which the kidney was the sole target organ; thirdly, two recipients of HLA-genotypically non-identical grafts developed a rapidly progressive fatal syndrome with multiple organ involvement including lung, brain and kidney which clinically and histologically resembled thrombotic thrombocytopenic purpura.

Acute Kidney Injury↗
PubMed1975

Ascorbate status of patients with porphyria cutanea tarda symptomatica and its effect on porphyrin metabolism.

The ascorbate status and the effect of loading doses of ascorbic acid (1,5 g per day by mouth for 7 days) on the porphyric process were studied in 7 black men with porphyria cutanea tarda symptomatica. It was found that the ascorbate stores were depleted in these patients as judged by serum and leucocyte ascorbate levels. Temporary repletion of the ascorbate stores was effected by the loading doses of ascorbic acid: Serum iron concentrations increased in 6 patients; urinary iron excretion showed small peaks a few days after ascorbic acid therapy commenced; haemoglobin concentration was not affected; excessive amounts of oxalate were excreted in the urine; neither total urinary porphyrin excretion nor the composition of the urinary porphyrins was affected in a way which could be related to ascorbate therapy. Further evidence that ascorbate depletion is not important in the induction of porphyria was found when the ascorbate status of siderotic rats, rendered porphyric by hexachlorobenzene-feeding, was examined. Stores of ascorbate and the oxidative catabolism of ascorbate were not different in the prophyric rats as compared with normal litter mates.

Adult↗