Species differences in the hydrolysis of 2-cyanoethylene oxide, the epoxide metabolite of acrylonitrile

The carcinogenic effects of acrylonitrile in rats are believedto be mediated by its DNA-reactive epoxide metabolite, 2-cyanoethyleneoxide (CEO). Previous studies have shown that conjugation withglutathione is the major detoxication pathway for both acrylonitrileand CEO. This study investigated the role of epoxide hydrolasein the hydrolysis of CEO by HPLC analysis of the products from[2,3-¹⁴C]CEO. CEO is a relatively stable epoxide with a half-lifeof 99 min at 37°C in sodium phosphate buffer (0.1 M), pH7.3. Incubation with hepatic microsomes or cytosols from maleF-344 rats or B6C3F1 mice did not enhance the rate of hydrolysisof CEO (0.69 nmol/min). Human hepatic microsomes significantlyincreased the rate of hydrolysis of CEO, whereas human hepaticcytosols did not. Human hepatic microsomal hydrolysis activitywas heat-sensitive and potently inhibited by 1,1,1-trichloropropeneoxide (IC₅₀ of 23 µM), indicating that epoxide hydrolasewas the catalyst. The hydrolysis of CEO catalyzed by hepaticmicrosomes from six individuals exhibited normal saturationkinetics with K_M ranging from 0.6 to 3.2 mM and V _max from 8.3to 18.8 nmol hydrolysis products/min/mg protein. Pretreatmentof rodents with phenobarbital or acetone induced hepatic microsomalhydrolysis activity toward CEO, whereas treatment with ß-naphthoflavone,dexamethasone or acrylonitrile itself was without effect. Thesedata show that humans possess an additional detoxication pathwayfor CEO that is not active in rodents (but is inducible). Thepresence of an active epoxide hydrolase hydrolysis activitytoward CEO in humans should be considered in assessments ofcancer risk from acrylonitrile exposure.     

Detection of Human T-Lymphotropic Virus (HTLV) tax Sequences in New York City Blood Donors Seronegative for HTLV Types 1 and 2

A potential public health concern is the reported detection of the human T-lymphotropic virus (HTLV) tax gene in the lymphocytes of up to 11% of a low-risk group of New York City blood donors (NYBD). This study aimed to independently confirm the prevalence of HTLV tax sequences in 293 NYBD. All NYBD tested negative for antibodies to HTLV types 1 and 2 and HTLV Tax. HTLV tax sequences were not detected in the NYBD lymphocytes. These data demonstrate the lack of HTLV-1 tax in this group of NYBD at low risk for HTLV infection.     

Primer sensitivity: can it influence the results in Enterococcus faecalis prevalence studies?

BACKGROUND/OBJECTIVE: Recent polymerase chain reaction (PCR)-based studies have shown significant variability in the prevalence of Enterococcus faecalis cases with nonhealing endodontic infections. This variability may be, at least in part, due to the differences in sensitivities of the primers used. The purpose of this study was to compare the sensitivity of 3 sets of PCR primers which have been reported in the endodontic literature. METHODS: The 3 primers sets used were: group 1) tuf gene-based primers with genus-level specificity; and groups 2 and 3) 16S rDNA-based primers that were E. faecalis specific. Three strains of E. faecalis at concentrations of 10(2)-10(8) cells/mL were included in this study. RESULTS: The PCR amplification of E. faecalis strains with the 3 primer pairs showed that group 1 primers consistently had the highest sensitivity, followed by group 2 and group 3 (P<.0001). CONCLUSION: A tuf-based PCR identification assay followed by direct sequencing would yield accurate and consistent prevalence rates of E. faecalis in endodontic infections.     

Susceptibility of diverse primary HIV isolates with varying co-receptor specificity's to CXCR4 antagonistic compounds

The chemokine receptors CCR5 and CXCR4 are an obvious target for HIV therapies. Two compounds, T-22 and AMD-3100, have been shown to inhibit infection of CXCR4-using HIV-1 isolates. The specificity of T-22 and AMD-3100 was further confirmed by their ability to block entry of HIV-1 in GHOST-CXCR4 transfected cells with no effect on viral entry in the GHOST-CCR5 cells. The ability of T-22 to block replication of diverse HIV-1 isolates (group M, subtypes A, B, D, E, and F as well as group O) and HIV-2 primary isolates with varying coreceptor specificities ranging from exclusive CCR5 usage to multiple coreceptor usage was examined in detail. T-22 was found to be highly effective (>90%) at blocking infection of diverse HIV-1 (subtypes A-F, and group O) and HIV-2 isolates that use multiple coreceptors in human PBMCs homozygous for a 32-bp deletion in CCR5 (CCR5-/-), but less effective in CCR5 +/+ PBMCs. Additionally, sequential primary HIV-1 isolates obtained from a longitudinal cohort who had switched from single coreceptor usage to a broad range of multiple receptors could be blocked effectively by both T-22 and AMD-3100 in CCR5-/- PBMCs. Our data suggest that CXCR4 antagonistic compounds are highly effective in blocking the entry of X4-tropic HIV-1, and that these compounds could be a useful additive to current anti-retroviral therapy for clinical management of HIV disease.     

Inherited prothrombotic defects in Budd-Chiari syndrome and portal vein thrombosis: a study from North India

We studied 57 patients with Budd-Chiari syndrome (BCS) and 48 with portal vein thrombosis (PVT) for underlying inherited prothrombotic defects such as protein C, protein S, and antithrombin III deficiencies. Genetic mutations for factor V Leiden, prothrombin gene 20210A, and methyltetrahydrofolate reductase (MTHFR) C677T were studied in 29 patients in each group. Inherited prothrombotic defects were detected in 16 (28%) of 57 patients with BCS and 7 (15%) of 48 patients with PVT. Factor V Leiden mutation was the most common prothrombotic defect in BCS (5/29 [17%]) followed by protein C deficiency (7/57 [12%]) and protein S deficiency (4/57 [7%]), whereas in PVT, protein C deficiency was the most common inherited prothrombotic defect (4/48 [8%]) followed by protein S deficiency (2/48 [4%]). The factor V Leiden mutation was detected in only 1 (3%) of 29 cases of PVT. The heterozygous MTHFR C677T mutation was detected in 7 (24%) of 29 patients with BCS and 6 (21%) of 29 patients with PVT. Antithrombin III deficiency, homozygous MTHFR C677T mutation, and prothrombin G20210A mutation were not detected in any patients.     

Adult cellular rhabdomyoma of the heart: a report of 3 cases

We present 3 adults with cardiac rhabdomyomas, 2 in the atria and 1 in the right ventricle. One atrial tumor was discovered incidentally, and 1 resulted in supraventricular tachycardia. The ventricular lesion caused ventricular tachycardia. Compared with congenital rhabdomyomas, the tumors are relatively cellular, the cells are smaller, there are few spider cells, and there is evidence of cell proliferation. Two of the 3 tumors demonstrated spindling in contrast to adult rhabdomyomas of the head and neck. Although surgical excision was possible in all patients, long-term follow-up will be required to determine the true biologic behavior of these neoplasms.     

Detection of human T-lymphotropic virus (HTLV) tax sequences in New York City blood donors seronegative for HTLV types 1 and 2

A potential public health concern is the reported detection of the human T-lymphotropic virus (HTLV) tax gene in the lymphocytes of up to 11% of a low-risk group of New York City blood donors (NYBD). This study aimed to independently confirm the prevalence of HTLV tax sequences in 293 NYBD. All NYBD tested negative for antibodies to HTLV types 1 and 2 and HTLV Tax. HTLV tax sequences were not detected in the NYBD lymphocytes. These data demonstrate the lack of HTLV-1 tax in this group of NYBD at low risk for HTLV infection.