Evaluation of polymerase chain reaction and adenosine deaminase assay for the diagnosis of tuberculous effusions in children.

AIM: To evaluate and compare the utility of polymerase chain reaction (PCR) for the diagnosis of tuberculous effusions in children. METHODS: PCR, adenosine deaminase (ADA) activity and absolute lymphocyte count (ALC) were evaluated in the fluid of 31 tuberculous (20 pleural, 8 ascites and 3 pericardial) and 24 non-tuberculous (10 transudtative ascites, 8 empyema thoracis, 3 malignant pleural and 3 pyopericardium) effusions. RESULTS: Fluid PCR for Mycobacterium tuberculosis was positive in 74% of tuberculous effusions, whereas it was falsely positive in 13% of the non-tuberculous group. The mean fluid ADA and ALC values were significantly higher in tuberculous effusions than in non-tuberculous effusions (p<0.001). The sensitivity and specificity of PCR, ADA (> or =38 IU/l) and ALC (> or =275/mm3) were 74% and 88%, 81% and 75%, and 90% and 83%, respectively, in diagnosing tuberculous effusions. The sensitivity of PCR, ADA and ALC was 100%, 100% and 88%, respectively, for confirmed tuberculous effusions. When the two tests were combined (either/or positive), the sensitivity increased (90-100%) at the expense of specificity. When both the tests were positive, then the specificity markedly increased (92-96%), but sensitivity of the tests decreased. CONCLUSION: Fluid PCR alone should not be relied on as a single test; rather, combined analysis with either ADA or ALC could be more useful in the diagnosis of tuberculous effusions in children.     

Modulation by dietary vitamin E of I-compounds (putative indigenous DNA modifications) in rat liver and kidney

I(indigenous)-compounds are age-related, carcinogen adduct-like, putative indigenous DNA modifications detectable by 32P-postlabeling assay in untreated animals. To investigate the origins of these DNA derivatives, we examined the effects of dietary vitamin E, a natural antioxidant, on I-compounds of rat liver and kidney DNA. Weanling female Sprague-Dawley rats were fed Draper's diets containing 0, 100, 1000, or 10,000 mg/kg alpha-tocopheryl acetate for 6 mo. The DNA from four individual rats of each group was analyzed by a nuclease P1-enhanced version of the 32P-postlabeling assay for DNA adducts. The amount of vitamin E in the liver was measured by high performance liquid chromatography. Rats fed vitamin E-deficient diet (0 mg/kg) showed identical profiles and similar levels of I-compounds as those fed the 100 mg/kg diet. Most I-spots were significantly intensified and one tissue-specific extra spot was found in both liver and kidney DNA of rats fed the 1000 or 10,000 mg/kg vitamin E diet. However, one of the five major I-spots detected in the kidney was weaker in the 1000 and 10,000 mg/kg groups than in the 0 and 100 mg/kg groups. These results show that formation of most I-compounds was not affected by vitamin E-deficient diet, and that long-term feeding of diet containing high levels of vitamin E may cause metabolic alterations leading to an increased formation of DNA-reactive (potentially mutagenic or carcinogenic) electrophiles.     

Effect of vitamin A deficiency on oxalate uptake by rat intestinal brush border membrane vesicles (BBMV) and its contribution towards urolithiasis

The intestinal uptake of [14C]oxalate, [14C]glyoxylate, and [14C]glycolate are studied in brush border membrane vesicles (BBMV) isolated from vitamin A-deficient and pair-fed control rats. The data obtained indicate that oxalate and its precursors are transported across the BBMV by passive diffusion. The intestinal uptake of glyoxylate and glycolate remains unaltered in vitamin A deficiency, while uptake rate of oxalate was significantly increased (p less than 0.01) in vitamin A-deficient rats as compared to pair-fed controls. In conclusion, the results indicate that vitamin A deficiency leads to hyperabsorption of oxalate through the gut.     

Cytokines and growth factors in keratinocytes and sweat glands in chronic venous leg ulcers. An immunohistochemical study

The role of growth factors and cytokines in the impaired healing of chronic leg ulcers remains uncertain. The aim of this study was to determine whether changes in the amount and location of cytokines and growth factors may be associated with impaired healing in chronic leg ulcers. Biopsies from leg ulcers of 21 patients and from normal skin of nine healthy volunteers were examined immunohistochemically for selected growth factors and cytokines. Greater staining intensity was found in keratinocytes at the edges of ulcers compared to normal skin, or skin adjacent to the ulcers. Staining at the ulcer edge was more intense in nonhealing ulcers for only vascular endothelial growth factor and platelet-derived growth factor, whereas staining in the adjacent skin was more intense for all factors in the nonhealing phase. For all factors staining was cytoplasmic, suggesting production in these areas. This study shows up-regulation of the production of cytokines and growth factors in keratinocytes of chronic leg ulcers that is greater when the ulcers are nonhealing.     

Inhibition of Calcium Oxalate Monohydrate (COM) crystal growth by pyrophosphate,citrate and rat urine

Summary An assay system for the measurement of the rate of Calcium Oxalate Monohydrate (COM) seed crystal growth in a metastable solution of calcium chloride and sodium oxalate containing traces of ¹⁴C-oxalic acid was used to assess the inhibitory activity of pyrophosphate (10^–5 M-10^–4 M), citrate (10^–4 M-10^–3 M) and urines of normal and pyridoxine deficient rats. Both pyrophosphate and citrate were strong inhibitors of COM crystal growth and caused a 50% decrease in crystal growth rate at 1.50×10^–5 M and 2.85×10^–4 M respectively. Normal rat urine strongly inhibited the COM crystal growth, while pyridoxine deficient animals showed a significant (p< 0.01) decrease in mean inhibitory activity as compared to pair-fed controls. A lowered urinary inhibitory potential accompanied with hyperoxaluria and hypercalciuria, which is known to be associated with pyridoxine deficiency, may be a contributory risk of calcium oxalate crystallization and stone formation.