Mutual interactions between HIV-1 and cytokines in adherent cells during acute infection

Intracerebroventricular (i.c.v.) infusions of angiotensin II (AII) reliably induced c-fos expression in the supraoptic (SON) and paraventricular (PVN) nuclei, as well as other areas of the basal forebrain including the OVLT, subfornical organ (SFO), and bed nucleus (BNST). Double-labelling showed that AII-induced c-fos was observed in both vasopressin (AVP-) and oxytocin (OXY)-containing neurons of the SON and PVN in male rats. Allowing rats to drink water after AII infusions suppressed c-fos expression both AVP- and OXY-stained magnocellular neurons. Intragastric infusions of water were also effective, showing that oro-pharyngeal stimuli were not critical. Maximal suppression occurred in rats in whom water had been infused intragastrically about 5 min before i.c.v. AII infusions, suggesting that changes in osmolarity were responsible. i.c.v. AII also induced c-fos expression in a number of brainstem structures, including the solitary nucleus (NTS), lateral parabrachial nucleus (LPBN), locus coeruleus (LC), and the area postrema (AP). These results indicate that AVP and OXY-containing neurons in the magnocellular parts of the SON and PVN alter their immediate-early gene response to AII after water intake, and that this does not depend upon oro-pharyngeal factors. Furthermore, AII can induce c-fos expression in a number of brainstem nuclei associated with autonomic function, and these do not respond to water intake.     

Biosynthesis of mitochondrial DNA. Is 8 S DNA an artifact?

Sucrose density gradient fractionation of isolated rat liver mitochondrial DNA ordinarily yields two peaks, one at 39 S, the other at 27 S. However, when these mitochondria are first incubated with a labeled DNA precursor, a labeled peak at about 8 S is also observed. Is this low molecular weight 8 S DNA merely an artifact of contamination or breakdown, or is it a functioning part of the mitochondrial genome? That it is not a nuclear contaminant is shown by: (a) the absence of nuclei or nuclear fragments in active mitochondrial preparations; (b) the insensitivity of 8 S DNA synthesis to treatment of mitochondria with DNase and RNase; (c) the ability of inner membrane preparations to synthesize this DNA; (d) the ability of atractyloside to inhibit incorporation of [3H]dATP into 8 S and 39 S or 27 S DNA equally; (e) the labeling of 8 S DNA (as well as 39 S and 27 S DNA) but not of nuclear DNA after the administration in vivo of [3H]thymidine. The evidence that 8 S DNA is not an artifact resulting from DNA breakdown during mitochondrial incubation or DNA isolation is as follows: (a) 8 S DNA can be isolated from unincubated mitochondrial; (b) 8 S DNA becomes labeled when labeled DNA precursors are administered in vivo; (c) 8 S DNA biosynthesis continues in the complete absence of labeled 39 S or 27 S DNA (whose synthesis is repressed by ethidium bromide), making it unlikely that 8 S DNA is formed from the breakdown of 39 S or 27 S DNA; (d) substitution of milder methods of DNA extraction does not decrease 8 S DNA labeling; moreover, the usual conditions of extraction, when applied to purified 39 S and 27 S DNA, do not generate 8 S DNA, nor does an additional mitochondrial washing cycle; (e) the specific radioactivity of 8 S DNA is higher than that of 39 S or 27 S DNA, making it improbable that the latter forms are precursors of 8 S DNA. Since 8 S DNA is double-stranded, it is not identical to the 7 S fragment of D loop DNA. The hypothesis that the artifactual nicking of those DNA molecules which contain opposing D loops leads to the release of double-stranded fragments was tested. The DNA which was released was predominantly (and probably completely) single-stranded. We conclude that 8 S DNA is probably not an artifact and studies are in progress on its function.     

The ocular albinism type 1 gene product is a membrane glycoprotein localized to melanosomes

Ocular albinism type 1 (OA1) is an inherited disorder characterized by severe reduction of visual acuity, photophobia, and retinal hypopigmentation. Ultrastructural examination of skin melanocytes and of the retinal pigment epithelium reveals the presence of macromelanosomes, suggesting a defect in melanosome biogenesis. The gene responsible for OA1 is exclusively expressed in pigment cells and encodes a predicted protein of 404 aa displaying several putative transmembrane domains and sharing no similarities with previously identified molecules. Using polyclonal antibodies we have identified the endogenous OA1 protein in retinal pigment epithelial cells, in normal human melanocytes and in various melanoma cell lines. Two forms of the OA1 protein were identified by Western analysis, a 60-kDa glycoprotein and a doublet of 48 and 45 kDa probably corresponding to unglycosylated precursor polypeptides. Upon subcellular fractionation and phase separation with the nonionic detergent Triton X-114, the OA1 protein segregated into the melanosome-rich fraction and behaved as an authentic integral membrane protein. Immunofluorescence and immunogold analyses on normal human melanocytes confirmed the melanosomal membrane localization of the endogenous OA1 protein, consistent with its possible involvement in melanosome biogenesis. The identification of a novel melanosomal membrane protein involved in a human disease will provide insights into the mechanisms that control the cell-specific pathways of subcellular morphogenesis.     

Effects of intrathecal administration of adrenergic agonists on the frequency of copulatory pelvic thrusting of the male rat

The effects of the intrathecal perispinal administration of adrenergic agonists on the characteristics of frequency, duration, and vigor of pelvic thrusting displayed by male rats during copulation was assessed by an accelerometric technique. A different dose of one drug (noradrenaline, clonidine or isoproterenol) and saline as control was administered at the lumbosacral level of the spinal cord to sexually active male rats in tests of sexual behavior performed at weekly intervals. The intrathecal administration of noradrenaline (alpha-adrenoceptor agonist) increased the frequency of pelvic thrusting in mount and intromission responses, whereas both the alpha 2-adrenoceptor agonist clonidine (25 micrograms) and the beta-adrenoceptor agonist isoproterenol (40 micrograms) reduced the frequency of pelvic thrusting in these responses as compared to values obtained under the intrathecal administration of saline. On the other hand, the duration of the thrusting trains and the potency or vigor of pelvic thrusting in mounts and intromissions did not differ from values obtained under saline treatment. These findings indicate a possible participation of noradrenaline in the modulation of the spinal mechanisms involved in the generation of rhythmic pelvic thrusting performed by the male rat during copulation.     

Acute toxicity of several organophosphorous insecticides and protection by cholinergic antagonists and 2-PAM on Artemia salina larvae

Western blot analysis and indirect immunofluorescence microscopy were used to evaluate the fate of the aryl-hydrocarbon receptor (AhR) and aryl-hydrocarbon receptor nuclear translocator (Arnt) protein in culture cell models exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In wild-type (WT) murine Hepa-1c1c7 cells, AhR protein was depleted by 85% after 4 hr of TCDD treatment as measured in total cell lysates. In contrast, the concentration of Arnt protein was unaffected by TCDD treatment in WT cells. Analysis of the AhR with immunofluorescence microscopy revealed that nuclear translocation of the liganded AhR preceded its depletion from cells. AhR protein was depleted from Hepa-1 type I variants (that contain a concentration of AhR that is 10% of WT) with a similar time course and to the same maximal level observed in WT cells (85%). The EC50 for AhR depletion in Hepa-1 cells was 39 pm TCDD and correspond to the EC50 for induction of P4501A1 protein. Murine embryonic fibroblasts (NIH-3T3), rat aortic smooth muscle cells (A7), and murine skeletal muscle cells (C2C12) all exhibited >90% depletion of the AhR after 2-4 hr of TCDD treatment. Arnt concentration was not affected by TCDD in these cell lines. These results indicate that the liganded AhR is rapidly depleted within the nuclear compartment of hepatic and nonhepatic cells in a manner independent of the Arnt protein.     

Safety of intrauterine contraceptive devices during MR imaging

OBJECTIVE: We report a case of candidiasis of the upper urinary tract that presented as acute renal failure associated with septic syndrome. The patient initially required hemodialysis. Right hydronephrosis and perirenal collection were observed on ultrasound examination. METHODS: A percutaneous nephrostomy was performed. Nephrostomy urine cytology and cultures were positive for Candida tropicalis. An anterograde pyelography showed a 'fungus ball' in the urinary tract. RESULTS: Therapy with oral fluconazole and percutaneous amphotericin B achieved excellent results. CONCLUSIONS: Candidiasic urinary infection of the upper urinary tract often produces obstructive uropathy requiring percutaneous nephrostomy, which can also be used to instill amphotericin B. Combination therapy with amphotericin B and fluconazole can achieve excellent results.