Human immunodeficiency virus (HIV) infection in men with penile carcinoma is associated with increased prevalence of human papilloma virus infection and younger age at presentation.

BACKGROUND: We investigated the prevalence of HIV and human papilloma virus (HPV) infection in men with penile carcinoma. METHODS: This retrospective study investigated all men with penile carcinoma at the Universitas Academic Hospital in Bloemfontein, South Africa (January 2000-December 2008). Patients' age, HIV status, histological type of carcinoma and evidence of HPV infection were recorded. Statistical analyses included Student's t-test and Fisher's exact test where appropriate (2-tailed p-value < 0.05 indicated statistical significant). RESULTS: Among 65 patients (mean age 50.9 years, range 37-69), the most common histological type was squamous cell carcinoma (80.0%). HIV status was known for 48 patients; 27 (56.2%) were HIV-positive. The mean age at presentation was 43.7 years (range 26-69) years in the HIV-positive and 57.2 years (range 26-89) years in the HIV-negative group. Approximately 55% of HIV-positive and 24% of HIV-negative patients showed histological evidence of HPV infection (p = 0.04). No significant difference was found with regard to histological type of carcinoma. CONCLUSION: Patients with penile carcinoma had a high prevalence of HIV infection. The HIV-positive group were significantly younger at presentation, with a higher prevalence of HPV infection, suggesting that HIV may contribute to HPV-associated penile cancer at a younger age.

Human immunodeficiency virus (HIV) infection in men with penile carcinoma is associated with increased prevalence of human papilloma virus infection and younger age at presentation

Background: We investigated the prevalence of HIV and human papilloma virus (HPV) infection in men with penile carcinoma.Method: This retrospective study investigated all men with penile carcinoma at the Universitas Academic Hospital in Bloemfontein, South Africa (January 2000­December 2008). Patients' age, HIV status, histological type of carcinoma and evidence of HPV infection were recorded. Statistical analyses included Student's t-test and Fisher's exact test where appropriate (2-tailed p-value < 0.05 indicated statistical significant).Results: Among 65 patients (mean age 50.9 years, range 37­69), the most common histological type was squamous cell carcinoma (80.0%). HIV status was known for 48 patients; 27 (56.2%) were HIV-positive. The mean age at presentation was 43.7 years (range 26­69) years in the HIV-positive and 57.2 years (range 26­89) years in the HIV-negative group. Approximately 55% of HIV-positive and 24% of HIV-negative patients showed histological evidence of HPV infection (p = 0.04). No significant difference was found with regard to histological type of carcinoma.Conclusion: Patients with penile carcinoma had a high prevalence of HIV infection. The HIV-positive group were significantly younger at presentation, with a higher prevalence of HPV infection, suggesting that HIV may contribute to HPV-associated penile cancer at a younger age

Properties of carbamoyl-phosphate synthetase (ammonia) in rat-liver mitochondria made permeable with toluene.

Some properties of carbamoyl-phosphate synthetase (ammonia) were studied in rat-liver mitochondria made selectively permeable by pretreatment with toluene. The Michaelis constants for NH3, MgATP and HCO-3 were 0.7, 1.2 and 2 mM respectively. N-Acetylglutamate activated the enzyme with a Ka of about 0.1 mM. At saturating concentrations of substrates and effectors the enzyme was inhibited by 50% by carbamoyl phosphate at a concentration of 13 mM. Binding of N-acetylglutamate to carbamoyl-phosphate synthetase required the presence of both free Mg2+ ions and MgATP, and was inhibited by Ca2+ ions and by N-carbamoylglutamate. The known activation of carbamoyl-phosphate synthetase by free Mg2+ is due to an increased affinity of the enzyme for N-acetylglutamate. Binding of N-acetylglutamate to carbamoyl-phosphate synthetase was a slow process: at N-acetylglutamate concentrations below 0.5 mM maximal binding was not completed within 30 min. The rate of binding increased with increasing N-acetylglutamate concentrations. Dissociation of N-acetylglutamate from the enzyme was relatively fast, with a half-time of about 5 min. Under all conditions studied there was a close relationship between carbamoyl-phosphate synthetase activity and the amount of N-acetylglutamate bound to the enzyme. The data are discussed in relation to the control of carbamoyl-phosphate synthetase in the intact hepatocyte.