Study of the identification of enterotoxigenic Escherichia coli by LT-DNA gene hybridization

Reference strains of enterotoxigenic Escherichia coli (ETEC), non-ETEC, and other enteropathogenic bacteria were used to prove the reliability of LT-DNA gene hybridization. In the test, LT-DNA gene hybridization was compared with plate immunohemolytic test (PIHT) in identifying LT-ETEC. The results obtained by both methods showed no significant differences. 791 strains of E. coli isolated from 1,875 children with acute diarrhea in Taiyuan Children's Hospital were examined for LT-ETEC by LT-DNA gene hybridization and PIHT. 289 strains examined by LT-DNA gene hybridization were LT positive, while 205 strains examined by PIHT were LT positive. Three different assays were done: colony hybridization, PIHT and fecal direct blot hybridization on each of 74 fecal specimens from children with acute diarrhea. It was found that identification of LT-ETEC using fecal direct blot hybridization is a simple, sensitive and more practical method.

Protective effects of an adenosine deaminase inhibitor on ischemia-reperfusion injury in isolated perfused rat heart

We tested the effect of the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl)adenosine (EHNA) on ischemia-reperfusion injury in isolated perfused rat heart. In the ischemia-reperfusion group (n = 10), ventricular fibrillation occurred within 3 min of reperfusion after the 40-min ischemic period. The incidence of ventricular fibrillation was 90% with a mean duration of 3.15 +/- 0.97 (SE) min. Resting tension increased significantly. By contrast, the incidence of ventricular fibrillation after reperfusion in the EHNA-treated (5 microM) group (n = 10) was 20% (P less than 0.01), and the duration was 0.30 +/- 0.21 min (P less than 0.01). Resting tension was significantly lower and around the normal level in the EHNA-treated group (P less than 0.01). Contraction amplitude and heart rate recovered to nearly normal compared with the ischemia-reperfusion group (P less than 0.01). Coronary flow was greater in the EHNA-treated group (P less than 0.01). It is concluded that EHNA protects the heart, possibly by accumulation of adenosine that benefits the hearts and by blocking the xanthine oxidase pathway for free radical generation.

Synthesis and anti-HIV-1 activity of 2'-"up"-fluoro analogues of active anti-AIDS nucleosides 3'-azido-3'-deoxythymidine (AZT) and 2',3'-dideoxycytidine (DDC)

1-(3-Azido-2,3-dideoxy-2-fluoro-beta-D-arabinofuranosyl)thymine (6, F-AZT) and 1-(2,3-dideoxy-2-fluoro-beta-D-threopentofuranosyl)cytosine (12, F-DDC) were synthesized from the potent antiherpes virus nucleosides 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)thymine (1, FMAU) and 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine (FIAC) in the hope that introduction of a 2-"up"-fluoro substituent might potentiate the anti-HIV activity of AZT and DDC. FMAU (1) was converted in three steps into 2,3'-anhydro-1-(2-fluoro-2-deoxy-5-O-trityl-beta-D-lyxofuranosyl)thymine (4), which when treated with NaN3 followed by detritylation afforded 6. F-DDC was prepared by two methods. Tritylation of FIAC followed by treatment of the product with thiocarbonyldimidazole afforded the 5'-O-trityl-3'-O-(imidazolyl)thiocarbonyl nucleoside 9. Upon radical reduction of 9 with Bu3SnH and AIBN, 5'-O-trityl-DDC 10 was obtained. Compound 10 was detritylated to give 12, which (when obtained by this procedure) resisted crystallization, but the diacetate 12' was obtained in crystalline form. Alternatively, FAC (14) was converted into N4,O5'-dibenzoyl derivative 15, which was treated with thiocarbonyldiimidazole. Reduction of 16 with Bu3SnH/AIBN followed by debenzoylation afforded 12, which was obtained in crystalline form. F-AZT did not exhibit any significant activity against the human immunodeficiency virus (HIV) in vitro. F-DDC, however, showed activity against HIV-1, but the therapeutic index is much inferior to that of AZT.

[Alterations in the sorbitol pathway and Na(+)-K(+)-ATPase activity of peripheral nerve of alloxan-induced diabetic rats]

Sorbitol pathway activity, myo-inositol content and ouabain-sensitive and ouabain-resistant ATPase activities were measured in homogenates of the sciatic nerve from alloxan-induced diabetic rats for 4, 8 and 12 weeks. Compared with the age-matched control, glucose, fructose and sorbitol contents of the sciatic nerve from diabetic rats for 4, 8 and 12 weeks were increased respectively to a level of 3-4 fold, 3-5 fold and 6-9 fold of those of the control rats. Myo-inositol was reduced approximately 50%. There was a significant decrease (P less than 0.01) in total ATPase, ouabain-sensitive and ouabain-resistant ATPase activities. These changes could be relevant to the development of diabetic neuropathy.

[Pathologic features of conduction system in myocardial infarction]

Coronary artery disease and myocardial infarction are frequently associated with major conduction abnormalities, but the correlation between the vascular disease and the specific conduction system is not obvious. Anyhow, in cases of acute occlusive vascular disease, the correlation might be more obvious. 31 cases of acute coronary arterial occlusion with myocardial infarction were studied correlating with ECG changes as well as pathologic lesions present in the conduction system. Results showed that histologic changes of the conductive system were usually related with the condition of blood supply and the site and size of the infarction. Additionally, the area of the damaged conductive tissue should be large enough to produce ECG changes. Otherwise the functional changes might be compensated or recovered. Myofibrillar degeneration was obtained in the conduction tissue in the majority of the cases reported, and its clinical significance remains to be clarified.

[Analysis of blood vessel invasion by cells of thyroid follicular carcinoma using image processing combined with immunohistochemistry]

By means of image processing combined with immunohistochemistry, we determined the nuclear morphometric parameters, DNA content and thyroglobulin content in angio-invasive cell and noninvasive cell groups in 5 cases of thyroid follicular carcinoma. The results showed that the two cell groups are quite different from each other. Morphologically, angio-invasive cells showed smaller nuclear size and irregular nuclear shape. DNA content in invasive cells was far more than in noninvasive cells. In addition, invasive cells contain more thyroglobulin than non-invasive cells.