Distribution of C14-labelled arteether in kidneys and livers of experimental mice after intramuscular injection.

To study the distribution and localization of oil-soluble arteether in experimental mice, we injected C14-labelled arteether (20 microCi/kg body weight) intramuscularly and measured radioactivity in the blood, kidney, and liver. The labelled arteether distributed and localized more to the kidney (819,180.4 +/- 34,134 dpm/cm3) than the liver (288,628.9 +/- 54,954 dpm/cm3) 4 hours post-injection. The main localization of labelled arteether was in the kidney cortex rather than the medulla (p < 0.05). However, the distribution of radioactivity was homogeneous in the liver. The terminal half-life of labelled arteether in the blood was 1.8 hours. The blood:kidney:liver ratio was 1:5:2. These findings show that labelled arteether was distributed quickly and localized in the cytoplasmic cortex of the kidney and homogeneously in the liver.

Caffeine, quercetin and alizarin stimulate the exhalation of metabolic products of [14C]-N-nitrosodiethylamine in mice.

Naturally occurring plant products belonging to different chemical classes namely alizarin, an anthraquinone, caffeine, a methylxanthine derivative and quercetin, a flavonol were studied for their effect on elimination of metabolites of [14C]-N-nitrosodiethylamine (14C-NDEA) through respiration in mice. Treatment with caffeine, quercetin and alizarin at doses of 200, 9 and 9 microg/ml respectively, in drinking water enhanced the exhalation of 14CO2, one of the major end products of NDEA metabolism. Radioactive CO2 exhaled in 60 min increased by 2, 1.61 and 1.4-folds in animals treated with caffeine, quercetin and alizarin for 8 weeks respectively. This increase in exhalation in caffeine-treated animals was achieved even in 2 weeks. These compounds had no adverse effects on the absorption of radioactive NDEA from the gut of the animals as shape and time of 14CO2 peak was similar in i.p. and orally administered [14C-NDEA]. Increased detoxification/elimination of the carcinogen could be one of the mechanisms for the anticarcinogenic properties of these phytochemicals in lung tumorigenesis induced by orally administered NDEA.

14C-urea breath test for assessment of gastric Helicobacter pylori colonization and eradication.

BACKGROUND AND OBJECTIVE: Urea breath test (UBT) is a reliable noninvasive technique for detecting gastric Helicobacter pylori colonization. 14C isotope-based test requires simple equipment and is inexpensive. We studied the utility of 14C-UBT in diagnosis of gastric H. pylori infection. METHODS: Presence of H. pylori was studied using antral histology and culture in patients with rapid urease test (RUT)-positive peptic ulcer. 14C-UBT was performed using a 185-kBq dose. Radioactivity in 15-min breath samples was measured using a beta-scintillation counter and result expressed as % dose recovered/mmol CO2. H. pylori was considered positive when any two tests were positive. All tests were repeated one month after completion of H. pylori eradication therapy. RESULTS: Among 41 patients (duodenal ulcer 36, gastric ulcer 5), H. pylori was detected by histology in 23 (56%) and by culture in 27 (66%). Overall, H. pylori was detected in 28 (68%) patients. Follow-up assessment was possible in 28 patients: 26 cleared the infection (all three tests negative). Mean 14C recovery values at 15 minutes associated with H. pylori-positive status were significantly higher (12.3 [SD 6.8] x 10(-3); n=30; p<0.001) than those associated with H. pylori-negative status (2.1 [0.9] x 10(-3); n=26). Using receiver-operating-characteristic analysis of 15-minute 14C recovery values, a cut-off of 6.5x10(-3) gave the best separation of H. pylori-positive and -negative cases. 14C-UBT had 93% sensitivity, 96% specificity and 95% accuracy. CONCLUSION: 14C-UBT appears to be a reliable noninvasive test for diagnosis of H. pylori infection.

Evaluation of the BACTEC radiometric method in the early diagnosis of tuberculosis.

A comparison of the BACTEC radiometric method with the conventional culture and drug susceptibility testing methods on isolates from clinical specimens in pulmonary and extrapulmonary tuberculosis, childhood TB and TB in HIV-infected individuals was undertaken. In the case of pulmonary TB, the rate of isolation of positive cultures was significantly faster with the BACTEC method, with 87 per cent of the positives being obtained by 7 days, and 96 per cent by 14 days. However, while there was no difference in the total number of positive cultures by the two methods in smear positive pulmonary tuberculosis, in smear negative pulmonary TB, the BACTEC method yielded more number of positive cultures. In extrapulmonary TB, HIV-TB and childhood TB, although the BACTEC method did not yield additional positives, the detection of positives was considerably faster than by the conventional methods, in which the degree of growth was also scanty. The agreement in drug susceptibility tests was 94 per cent for streptomycin and isoniazid, 99 per cent for rifampicin and 91 per cent for ethambutol. Further, most of the drug susceptibility test results became available within 8 days by the BACTEC method. By facilitating early diagnosis, the BACTEC method may prove to be cost effective in a population with a high prevalence of tuberculosis, particularly in the extrapulmonary and paucibacillary forms of the disease.

Normal limits of 14C-urea breath test.

BACKGROUND/AIMS: 14C-urea breath test has been widely used for diagnosis of Helicobacter pylori (H. pylori) infection. There is no general agreement on the cutoff values for determination of H. pylori negative subjects. We studied baseline values in subjects who were proved to be H. pylori negative and calculated the cutoff value of normalcy. A comparison of this test with other tests for diagnosis of H. pylori infection was also done. PATIENTS AND METHODS: 12 patients (mean age 34 +/- 14, range 22-65 years; 8 men) of non-ulcer dyspepsia were studied, who were proved to be H. pylori negative by rapid urease test, Gram's staining, histopathology and culture of gastric mucosal biopsies obtained four each from the antrum, body and fundus of the stomach. The controls included 12 patients (mean age 40 +/- 13, range 22-65 years, 9 men), who were positive for H. pylori on culture or combination of rapid urease test and histopathology or rapid urease test and Gram's stain. 14C-urea breath test was performed using 5 uCi of 14C-urea dissolved in 300 ml of water. Breath samples were collected once before ingestion of 14C urea and subsequently at 5, 15 and 30 minutes after ingestion and 14C-contents in the breath samples measured. Results were expressed as 14 CO2/mmol CO2 exhaled as percent of administered urea. RESULTS: The mean +/- SD 14-C value in H. pylori negative vs H. pylori positive patients at 5 minutes, 15 minutes and 30 minutes were found to be 0.003 +/- 0.003 vs 0.064 +/- 0.042 (p < 0.001), 0.002 +/- 0.001 vs 0.056 +/- 0.039 (p < 0.001) and 0.001 +/- 0.002 vs 0.041 +/- 0.026 (p < 0.001) respectively. The mean values of 14C-urea breath test were significantly lower in H. pylori negative patients as compared to H. pylori positive patients. Using receiver operating characteristic (ROC) analysis of the data, the cutoff values obtained were 0.01, 0.007 and 0.009 at 5 minutes, 15 minutes and 30 minutes respectively. CONCLUSIONS: 14C-urea breath test levels at 5, 15 and 30 minutes intervals are significantly lower in H. pylori negative patients as compared to H. pylori positive patients. This test has high sensitivity and specificity in detecting H. pylori infection.

Effect of catechin on intestinal lipid metabolism.

On analysing the effect of catechin on intestinal lipid metabolism, an increase in the concentration of cholesterol in the duodenum and jejunum was observed along with an increase in the HMGCoA reductase activity. In the in vitro experiments also it was found that cholesterol and free fatty acid (FFA) levels were increased in these two regions. Binding of catechin with cholesterol in the lumen, reduces the availability of cholesterol for absorption which may in turn stimulate cholesterol biosynthesis and a rise in the HMGCoA reductase activity. These alterations produced by catechin may also be related to the degradation of cholesterol to bile acids, as endogenous cholesterol is the preferred substrate for bile acid synthesis.

The 13C urea breath test to assess Helicobacter pylori infection in school children.

BACKGROUND: The 13C urea breath test was used in this study to establish it as a diagnostic tool as well as to assess the prevalence of Helicobactor pylori in a group of school children. METHODS AND RESULTS: In a group of 50 children studied, 82% were found to be positive for H. pylori by this test. The influence of diet in modifying the results of the test was also assessed. Relatively small errors were seen if adequate precautions were taken. CONCLUSION: Epidemiological studies are required to further quantify the magnitude of the prevalence of H. pylori in the Indian setting.

Rat epididymal sperm exhibit on dithiothreitol treatment in vitro quantifiable differences in patterns of light scatter, uptake of 14C-iodoacetamide and binding of ethidium bromide to DNA.

The extent to which chromatin of rat caput (CAP), corpus (COR), cauda (CAU) spermatozoa undergo condensation and compaction is known to be a function of progressive increase in the formation of inter- as well as intra-protamine disulphide bridges during their transit through the epididymis. Relative compaction undergone by the nuclear chromatin of these sperm populations was studied by monitoring their susceptibility to in vitro decondensation induced by varying concentrations (0, 0.01, 1, 5, 10, 50 mM) of disulphide reducing agent, dithiothreitol (DTT) after an initial exposure to 0.01% papain. Following this treatment and staining with the nucleic acid specific fluorochrome, ethidium bromide (EB), it was observed that irrespective of the epididymal region from which they were collected, spermatozoa exhibited DTT dose-dependent (a) increase in nuclear size as seen under fluorescence microscopic examination, (b) decrease in flow cytometrically quantifiable light scatter parameters--forward scatter (FSc, 'nuclear size') and side scatter (SSc, nuclear 'granularity'), (c) increase in individual cell EB binding when analyzed by DNA flow cytometry, and (d) increase in thiol specific 14C-iodoacetamide (14C-IA) uptake. The decrease in both FSc and SSc occurring in spite of actual increase in nuclear size has been attributed to increase in translucency of spermatozoan nuclei consequent to decondensation. The FSc, SSc and EB bindability were studied by monitoring both the channels of maximal cell concentration detected in the flow cytograms as well as by digitally quantitating the numbers of cells within specific channels (1-64, 65-128, 129-192 and 193-256) of the flow cytogram. The latter indicated a measure of the variability in the response of populations of sperm within each sample to DTT induced decondensation. At any given concentration of DTT, especially between 5-10 mM, the differences observed between sperms of different regions were consistent and significant (P < 0.01-P < 0.001), maximal changes being shown by CAP and minimal by CAU sperm, COR sperm appearing in between. The effective concentration of DTT required to elicit 50% of maximal (i.e. that exhibited by CAP sperm when taken as 100%) effect (ED50) varied significantly among CAP, COR and CAU sperms for each of the parameters studied (P < 0.01-P < 0.001). It is concluded that the differences observed among the three epididymal sperm populations are due to differences in the extent of susceptibility to decondensation in vitro and that this is dependent upon the variation in the -S-S-content of their chromatin during different stages of epididymal transit. All the parameters used (with the exception of fluorescence microscopy) can be quantified and as all of them show a similar dose dependency to DTT treatment, any one of these parameters can be conveniently used to determine the mature/immature status of the sperms voided. Application of such a method to determine the quality of sperms voided by man appears feasible.

The use of combustion technique of tissue processing for the study of the distribution of 14C-salicylate in rats after oral administration.

The distribution of 14C-salicylate (150 mg/kg, orally) in rat tissues was studied, at different time intervals upto 2 hr. A fairly rapid distribution was noted and a peak level was found to occur at 30 min after administration of the labelled drug in all the tissue studied. The combustion technique was used for tissue processing to determine the radioactivity as compared to the digestion method of tissue processing utilised by Sturman et al. (5) for their studies. The combustion technique was found to be more sensitive, as at a dose of 150 mg/kg (0.5 ml containing 5 uCi) administered orally, there was a greater level of radioactivity in all tissues as compared to the levels found by Sturman et al. (5) for a dose of 200 mg/kg (0.2 ml containing 2 uCi) administered intraperitoneally.