Classical and anaplastic seminoma: difference in survival

Classical and anaplastic seminoma are traditionally treated with radiation therapy and are said to have the same prognosis. A retrospective study was undertaken of 90 seminoma patients treated with radiation therapy between 1961 and 1985. The classical group consisted of 71 patients of whom 50 had stage I and 21 had stage II disease. The anaplastic group consisted of 19 patients of whom ten had stage I and nine had stage II disease. The median follow-up time was 64 months for the entire group. The 10-year relapse-free survival rate for the classical group was 94% and for the anaplastic group was 70% (P less than .05). For patients with classical stage I disease, the relapse-free actuarial survival rate was 98%; for patients with anaplastic stage I disease, it was 64% (P less than .02). For the classical stage II disease group, the relapse-free actuarial survival rate was 84% and for the anaplastic stage II disease group, 75% (P less than .70). Four patients in the classical group (6%) had relapses; of these, one patient had local recurrence of tumor, and three had distant metastases. In the anaplastic group, four patients (21%) had relapses; two patients had local recurrence of tumor, and two had distant metastases. Therefore the data suggest a difference in survival and relapse rates between classical and anaplastic seminoma.     

Importance of thiols in the reductive binding of 2-nitroimidazoles to macromolecules

Reductive activation of 2-nitroimidazoles in the presence of bovine serum albumin (BSA) led to binding of the nitroheterocycles to the protein. The binding was most efficient to BSA in which protein disulfides had been reduced to thiol groups. Protein thiols were at least twenty times more efficient than other protein, RNA or DNA nucleophiles in binding the reductively-activated nitroheterocycles. This result is of practical importance in the development of immunoassays for 2-nitroimidazoles as hypoxia markers in normal and tumor tissue.     

Upregulation of the Golgi protein GP73 by adenovirus infection requires the E1A CtBP interaction domain

GP73 is a novel type II Golgi transmembrane protein that is expressed at high levels in the hepatocytes of patients with viral hepatitis (R. D. Kladney, G. A. Bulla, L. Guo, A. L. Mason, A. E. Tollefson, D. J. Simon, Z. Koutoubi, and C. J. Fimmel, 2000, Gene 249, 53-65) and is induced in cultured cells by infection with viruses including adenoviruses. Its biological function and the mechanisms by which its expression may be regulated by viral infection are unknown. Here we report that GP73 is induced at the RNA and protein level in human Hep3B hepatoma cells infected by human Ad5 and Ad2. Hep3B cells were infected with wild-type or mutant adenoviruses. GP73 expression was measured by RNase protection assay, immunoblotting, or immunofluorescence microscopy. GP73 RNA and protein levels were strikingly induced following infection. The rise in GP73 expression coincided with the appearance of the adenovirus E1A and DBP proteins and preceded the expression of the fiber protein, a marker of the late phase of infection. Infection did not affect the expression of giantin, GPP130, or golgin-84, three integral Golgi membrane proteins with structural similarities to GP73. Mapping studies using a panel of mutant adenoviruses demonstrated that the E1A C-terminus, specifically its CtBP interaction domain (CID), is required for GP73 expression. Subsequently, Hep3B cells were transiently transfected with plasmids expressing wild-type or mutant E1A proteins. These studies confirmed that E1A induced GP73 expression via the CID. Our studies establish GP73 as a novel adenovirus-induced cellular protein whose expression is regulated through the CID of the E1A protein.     

Prevalence of obesity and hyperinsulinemia: its association with serum lipid and lipoprotein concentrations in healthy individuals from Maracaibo,Venezuela

The aim of this study was to analyse the prevalence of obesity and hyperinsulinemia and their association with lipid profile alterations on apparently healthy individuals from Maracaibo, Venezuela. We evaluated 306 men and 41 women, ages ranging from 33 to 65 years. All subjects underwent cardiovascular evaluation and laboratory examination after 10-12 h fasting, for glycaemia, total cholesterol, TG, VLDL-C, LDL-C and HDL-C as well as insulin. Seventy-four percent of men and 56.1% of women showed obesity (BMI > 25 Kg/m2). Men showed high concentrations of TG (48.3%), total cholesterol (40.2%), VLDL-C (48.3%) and LDL-C (33.9%) and low HDL-C levels (48%). The most frequent alteration on the lipid profile in women was high total cholesterol (46%) and LDL-C (51.2%). Men had significantly higher insulin concentrations than women (p < 0.005). After they were classified as obese or non obese, the obese subjects (men and women) showed higher prevalence of lipid profile alterations and insulin concentrations than non obese. The insulin concentration in obese men correlated with BMI, TG, VLDL-C and HDL and, in women with BMI, TG and VLDL-C. In conclusion, a high percentage of men and women in this study showed obesity and this obesity, specially in men, was strongly associated with lipid profile alterations and high insulin concentrations both well known cardiovascular risk factors.     

RENAL TRANSPLANTATION – AN EARLY EXPERIENCE

Renal transplant (RT) is now a therapy of choice for end stage renal disease (ESRD). The Nephrology Unit, Asvini started functioning in Dec 90 and to date 1298 sittings of hemodialysis have been given to 45 patients. Of these, 35 were in ESRD and 11 patients underwent renal transplantation at this hospital during the period Jan 91 – Dec 93. One patient expired after 18 months of transplantation due to infection. Early experience in screening patients for RT, use of immunosuppression, management of rejection episodes and protocol are presented with special emphasis on its relevance to the Armed Forces.KEY WORDS: Transplantation, Renal Failure, Immunosuppression, Rejection     

Oxidative stress occurs in perfused rat liver at low oxygen tension by mechanisms involving peroxynitrite

Ethanol increases free radical formation; however, it was recently demonstrated that it also causes extensive hypoxia in rat liver in vivo. To address this issue, it was hypothesized that peroxynitrite formed in normoxic periportal regions of the liver lobule has its reactivity enhanced in hypoxic pericentral regions where the pH is lower. Via this pathway, peroxynitrite could lead to free radical formation in the absence of oxygen. Livers from fed rats were perfused at low flow rates for 75 min. Under these conditions, periportal regions were well oxygenated but pericentral areas became hypoxic. Low-flow perfusion caused a significant 6-fold increase in nitrotyrosine accumulation in pericentral regions. During the last 20 min of perfusion, the spin-trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone was infused and adducts were collected for electron-spin resonance analysis. A six-line radical adduct signal was detected in perfusate. Direct infusion of peroxynitrite produced a radical adduct with identical coupling constants, and a similar pattern of nitrotyrosine accumulation was observed. Retrograde perfusion at low rates resulted in accumulation of nitrotyrosine in periportal regions. Although the magnitude of the radical in perfusate was increased by ethanol, it was not derived directly from it. Both nitrotyrosine accumulation and radical formation were reduced by inhibition of nitric oxide synthase with N-nitro-L-arginine methyl ester, but not with the inactive D-isomer. Radical formation was decreased nearly completely by superoxide dismutase and N-nitro-L-arginine methyl ester, consistent with the hypothesis that the final prooxidant is a derivative from both NO. and superoxide (i.e., peroxynitrite). These results support the hypothesis that oxidative stress occurs in hypoxic regions of the liver lobule by mechanisms involving peroxynitrite.     

Antitumour prodrug development using cytochrome P450 (CYP) mediated activation

An ideal cancer chemotherapeutic prodrug is completely inactive until metabolized by a tumour-specific enzyme, or by an enzyme that is only metabolically competent towards the prodrug under physiological conditions unique to the tumour. Human cancers, including colon, breast, lung, liver, kidney and prostate, are known to express cytochrome P450 (CYP) isoforms including 3A and 1A subfamily members. This raises the possibility that tumour CYP isoforms could be a focus for tumour-specific prodrug activation. Several approaches are reviewed, including identification of prodrugs activated by tumour-specific polymorphic CYPs, use of CYP-gene directed enzyme prodrug therapy and CYPs acting as reductases in hypoxic tumour regions. The last approach is best exemplified by AQ4N, a chemotherapeutic prodrug that is bioreductively activated by CYP3A. This study shows that freshly isolated murine T50/80 mammary carcinoma and RIF-1 fibrosarcoma 4-electron reduces AQ4N to its cytotoxic metabolite, AQ4 (T50/80 Km = 26.7 microM, Vmax = 0.43 microM/mg protein/min; RIF-1 Km = 33.5 microM, Vmax = 0.42 microM/mg protein/min) via AQM, a mono-N-oxide intermediate (T50/80 Km = 37.5 microM; Vmax = 1.4 microM/mg protein/min; RIF-1 Km = 37.5 microM; Vmax = 1.2 microM/mg protein/ min). The prodrug conversion was dependent on NADPH and inhibited by air or carbon monoxide. Cyp3A mRNA and protein were both present in T50/80 carcinoma grown in vivo (RIF-1 not measured). Exposure of isolated tumour cells to anoxia (2 h) immediately after tumour excision increased cyp3A protein 2-3-fold over a 12 h period, after which time the cyp protein levels returned to the level found under aerobic conditions. Conversely, cyp3A mRNA expression showed an initial 3-fold decrease under both oxic and anoxic conditions; this returned to near basal levels after 8-24 h. These results suggest that cyp3A protein is stabilized in the absence of air, despite a decrease in cyp3A mRNA. Such a 'stabilization factor' may decrease cyp3A protein turnover without affecting the translation efficiency of cyp3A mRNA. Confirmation of the CYP activation of AQ4N bioreduction was shown with human lymphoblastoid cell microsomes transfected with CYP3A4, but not those transfected with CYP2B6 or cytochrome P450 reductase. AQ4N is also reduced to AQ4 in NADPH-fortified human renal cell carcinoma (Km = 4 microM, Vmax = 3.5 pmol/mg protein/min) and normal kidney (Km = 4 microM, Vmax = 4.0 pmol/mg protein/min), both previously shown to express CYP3A. Germane to the clinical potential of AQ4N is that although both normal and tumour cells are capable of reducing AQ4N to its cytotoxic species, the process requires low oxygen conditions. Hence, AQ4N metabolism should be restricted to hypoxic tumour cells. The isoform selectivity of AQ4N reduction, in addition to its air sensitivity, indicates that AQ4N haem coordination and subsequent oxygen atom transfer from the active-site-bound AQ4N is the likely mechanism of N-oxide reduction. The apparent increase in CYP3A expression under hypoxia makes this a particularly interesting application of CYPs for tumour-specific prodrug activation.     

Measuring Tumor Hypoxia

A variety of techniques for measuring oxygen in normal and tumor tissue has been developed over the years in response to the realization that hypoxia is important in a number of pathophysiological conditions in normal tissues and in the response of tumors to radiation treatment. A review of the techniques for measuring tissue oxygenation is presented with an emphasis on clinical results. Histomorphometry, DNA strand break analysis (comet assay), oxygen microelectrodes and hypoxia markers are highlighted. Comparison among techniques is touched on and a short discussion of the possibility that hypoxia is not an independent variable in determining the outcome of radiation therapy is presented.     

Suicide patterns and trends in people of Indian subcontinent and Caribbean origin in England and Wales

Objectives: To examine suicide rates and trends in people of Indian subcontinent, east African and Caribbean origin using the latest mortality data available for England and Wales. To compare suicide rates in these groups with the baseline and target rates for suicide in the Health of the Nation strategy.

Methods: Suicide data for England and Wales for 1988–1992, classified by the country of birth of the deceased, and population denominators from the 1991 Census were used for the analysis. Standardised mortality ratios (SMRs) for ages 15–64 and age‐specific ratios were computed, using the age‐sex specific rates for England and Wales as the standard. Trends over the preceding decade and suicide by burning were also analysed. Directly age‐standardised suicide rates were derived to facilitate comparison with Health of the Nation baseline and target rates.

Results: Suicide ratios were significantly low (SMRs 32, 52 and 55 respectively) in Bangladeshi, Sri Lankan and Pakistani born men at all ages, but raised in young Indian and east African men. Ratios were significantly high in Indian and east African women (143 and 154), with a 2–3 fold excess at ages 15–34 years. Ratios were low in Pakistani and Bangladeshi women overall, but elevated at 15—24 years. For the Caribbean‐born, ratios were low overall but raised at ages 25–34. 20% of Asian female suicides were by burning. Indians are a high risk group in terms of the Health of the Nation suicide targets. Suicide trends in the minority ethnic groups reflect national trends.

Conclusions: This study confirms previous findings of high suicide rates in young Asian women. A new finding is the raised suicide rate in young Caribbeans. High suicide risks among young people from some ethnic minority communities are significant in the context of both the Health of the Nation strategy and recent governmental concern about the need to tackle health variations in the UK. Such deaths are indicative of larger numbers of young ethnic minority adults at risk of mental distress and self harm.