Eosinophilic granuloma of the cavernous sinus and orbital apex in an HIV-positive patient

A 35-year-old HIV-positive woman with painful ophthalmoplegia, sensory loss extending to all branches of the trigeminal nerve, and progressive optic neuropathy was found to have eosinophilic granuloma of the cavernous sinus, superior orbital fissure, and orbital apex. There was no radiologic evidence of a lytic bone lesion within the skull or orbit and clinical evidence suggested a primary intracranial origin for this lesion. This is the first case of a cavernous sinus syndrome caused by eosinophilic granuloma and the first time HIV infection is reported in association with histiocytosis-X.     

Evidence for enzymatic activation and oxygen involvement in cytotoxicity and antitumor activity of N,N',N'-triethylenethiophosphoramide

The cytotoxicity of N,N',N'-triethylenethiophosphoramide (thiotepa) was studied in vitro in the MCF-7 human breast carcinoma cell line and in vivo using the EMT6 mouse mammary tumor model, under various conditions of oxygenation and in the presence and absence of Aroclor 1254-induced liver preparations. The cytotoxicity of thiotepa toward exponentially growing MCF-7 cells was markedly dependent on the presence of oxygen during the period of drug exposure, with 3 log greater cell kill at 500 microM thiotepa being observed when the cells were normally oxygenated compared with hypoxic cells. Incubation of thiotepa with an Aroclor 1254-induced rat liver S-9 homogenate, in the presence of a NADPH-regenerating system, resulted in an 8-fold increase in cytotoxicity towards the MCF-7 cells over a wide range of drug concentrations. Thiotepa was shown to be metabolized under these conditions in a NADPH- and O2-dependent reaction that was catalyzed by one or more microsomal cytochrome P-450 enzymes that were present in the S-9 fraction. The thiotepa metabolite triethylene phosphoramide, which hydrolyzes significantly faster than thiotepa, was significantly less cytotoxic toward the MCF-7 cells than was thiotepa itself, suggesting that it is unlikely to be the S-9 metabolite responsible for the observed increase in drug cytotoxicity. Moreover, triethylene phosphoramide cytotoxicity was only partially O2 dependent and was largely unaffected by incubation in the presence of the S-9 preparation, indicating a mechanism of action distinct from that of thiotepa. Tumor cell survival experiments with the EMT6 mouse mammary carcinoma system revealed that a 3.6-fold increase in thiotepa cytotoxicity was obtained by prior administration of the liver inducer Aroclor 1254 to the tumor-bearing animals, 5 days before drug treatment. Finally, the therapeutic effectiveness of thiotepa was significantly enhanced (3- to 5.8-fold increase in tumor growth delay) when an increase in oxygenation was achieved, by carbogen breathing, in animals given the perfluorochemical emulsion Fluosol-DA. These findings establish that the cytotoxic effects of thiotepa are oxygen dependent and may involve, at least in part, metabolic processes catalyzed by cytochrome P-450 enzymes.     

Up against eugenics: Disabled women's challenge to receive reproductive health services

This is an overview of disabled women's reproductive health status. It focuses on the politics of eugenics, which explains why disabled women are devalued as sources of reproduction, have little access to women's health services, and are faced with methods of contraception which continue to pose a threat to their reproductive health and freedom. The ultimate goal of the author is to bring forth questions for research, and to help set the reproductive rights agenda for the aspiring disabled feminist movement.     

Sodium channel expression in optic nerve astrocytes chronically deprived of axonal contact.

Immunocytochemical and electrophysiological methods were used to examine the effect of retinal ablation on the expression of sodium channels within optic nerve astrocytes in situ and in vitro. Enucleation was performed at postnatal day 3 (P3), and electron microscopy of the enucleated optic nerves at P28-P40 revealed complete degeneration of retinal ganglion axons, resulting in optic nerves composed predominantly of astrocytes. In contrast to control (non-enucleated) optic nerve astrocytes, which exhibited distinct sodium channel immunoreactivity following immunostaining with antibody 7493, the astrocytes in enucleated optic nerves did not display sodium channel immunoreactivity in situ. Cultures obtained from enucleated optic nerves consisted principally (greater than 90%) of glial fibrillary acidic protein (GFAP)+/A2B5- ("type-1") astrocytes, as determined by indirect immunofluorescence; GFAP+/A2B5+ ("type-2") astrocytes were not present, nor were GFAP-/A2B5+ (O-2A) progenitor cells. Sodium channel immunoreactivity was not present in GFAP+/A2B5- astrocytes obtained from enucleated optic nerves; in contrast, GFAP+/A2B5- astrocytes from control optic nerves exhibited 7493 immunostaining for the first 4-6 days in culture. Sodium current expression, studied using whole-cell patch-clamp recording, was attenuated in cultured astrocytes derived from enucleated optic nerves. Whereas 39 of 50 type-1 astrocytes cultured from intact optic nerves showed measurable sodium currents at 1-7 days in vitro, sodium currents were present in only 6 of 38 astrocytes cultured from enucleated optic nerves. Mean sodium current densities in astrocytes from the enucleated optic nerves (0.66 +/- 0.3 pA/pF) were significantly smaller than in astrocytes from control optic nerves (7.15 +/- 1.1 pA/pF). The h infinity-curves of sodium currents were similar in A2B5- astrocytes from enucleated and control rat optic nerves. These results suggest that there is neuronal modulation of sodium channel expression in type-1 optic nerve astrocytes, and that, following chronic loss of axonal association in vivo, sodium channel expression is down-regulated in this population of optic nerve astrocytes.     

Development of a substrate-activity based approach to identify the major human liver P-450 catalysts of cyclophosphamide and ifosfamide activation based on cDNA-expressed activities and liver microsomal P-450 profiles.

The contributions of specific human liver cytochrome P-450 (CYP) enzymes to the activation, via 4-hydroxylation, of the oxazaphosphorine anticancer prodrugs cyclophosphamide (CPA) and ifosfamide (IFA) were investigated. Analysis of a panel of 15 human P-450 cDNAs expressed in human lymphoblasts and/or baculovirus-infected insect cells (Supersomes) demonstrated that CYPs 2A6, 2B6, 3A4, 3A5, and three CYP2C enzymes (2C9, 2C18, 2C19) exhibited significant oxazaphosphorine 4-hydroxylase activity, with 2B6 and 3A4 displaying the highest activity toward CPA and IFA, respectively. CYP2B6 metabolized CPA at a approximately 16-fold higher in vitro intrinsic clearance (apparent Vmax/Km) than IFA, whereas 3A4 demonstrated approximately 2-fold higher Vmax/Km toward IFA. A relative substrate-activity factor (RSF)-based method was developed to calculate the contributions of individual P-450s to total human liver microsomal metabolism based on cDNA-expressed P-450 activity data and measurements of the liver microsomal activity of each P-450 form. Using this method, excellent correlations were obtained when comparing measured versus predicted (calculated) microsomal 4-hydroxylase activities for both CPA (r = 0. 96, p <.001) and IFA (r = 0.90, p <.001) in a panel of 17 livers. The RSF method identified CYP2B6 as a major CPA 4-hydroxylase and CYP3A4 as the dominant IFA 4-hydroxylase in the majority of livers, with CYPs 2C9 and 2A6 making more minor contributions. These predicted P-450 enzyme contributions were verified using an inhibitory monoclonal antibody for 2B6 and the P-450 form-specific chemical inhibitors troleandomycin for 3A4 and sulfaphenazole for 2C9, thus validating the RSF approach. Finally, Western blot analysis using anti-2B6 monoclonal antibody demonstrated the presence of 2B6 protein at a readily detectable level in all but one of 17 livers. These data further establish the significance of human liver CYP2B6 for the activation of the clinically important cancer chemotherapeutic prodrug CPA.