Immunohistochemical localization and biological activity of the steroidogenic enzyme cytochrome P450 17alpha-hydroxylase/C17, 20-lyase (P450C17) in the frog brain and pituitary

It is now clearly established that the brain has the capability of synthesizing various biologically active steroids including 17-hydroxypregnenolone (17OH-Delta(5)P), 17-hydroxyprogesterone (17OH-P), dehydroepiandrosterone (DHEA) and androstenedione (Delta(4)). However, the presence, distribution and activity of cytochrome P450 17alpha-hydroxylase/C17, 20-lyase (P450(C17)), a key enzyme required for the conversion of pregnenolone (Delta(5)P) and progesterone (P) into these steroids, are poorly documented. Here, we show that P450(C17)-like immunoreactivity is widely distributed in the frog brain and pituitary. Prominent populations of P450(C17)-containing cells were observed in a number nuclei of the telencephalon, diencephalon, mesencephalon and metencephalon, as well as in the pars distalis and pars intermedia of the pituitary. In the brain, P450(C17)-like immunoreactivity was almost exclusively located in neurons. In several hypothalamic nuclei, P450(C17)-positive cell bodies also contained 3beta-hydroxysteroid dehydrogenase-like immunoreactivity. Incubation of telencephalon, diencephalon, mesencephalon, metencephalon or pituitary explants with [(3)H]Delta(5)P resulted in the formation of several tritiated steroids including 17OH-Delta(5)P, 17OH-P, DHEA and Delta(4). De novo synthesis of C(21) 17-hydroxysteroids and C(19) ketosteroids was reduced in a concentration-dependent manner by ketoconazole, a P450(C17) inhibitor. This is the first detailed immunohistochemical mapping of P450(C17) in the brain and pituitary of any vertebrate. Altogether, the present data provide evidence that CNS neurons and pituitary cells can synthesize androgens.     

Human immunodeficiency virus type 1 replication in dendritic cell-T-cell cocultures is increased upon incorporation of host LFA-1 due to higher levels of virus production in immature dendritic cells

Dendritic cells (DCs) act as a portal for invasion by human immunodeficiency virus type-1 (HIV-1). Here, we investigated whether virion-incorporated host cell membrane proteins can affect virus replication in DC-T-cell cocultures. Using isogenic viruses either devoid of or bearing host-derived leukocyte function-associated antigen 1 (LFA-1), we showed that HIV-1 production is augmented when LFA-1-bearing virions are used compared to that for viral entities lacking this adhesion molecule. This phenomenon was observed in immature monocyte-derived DCs (IM-MDDCs) only and not in DCs displaying a mature phenotype. The increase is not due to higher virus production in responder CD4(+) T cells but rather is linked with a more important productive infection of IM-MDDCs. We provided evidence that virus-associated host LFA-1 molecules do not affect a late event in the HIV-1 life cycle but rather exert an effect on an early step in virus replication. We demonstrated that the enhancement of productive infection of IM-MDDCs that is conferred by virus-anchored host LFA-1 involves the protein kinase A (PKA) and PKC signal transduction pathways. The biological significance of this phenomenon was established by performing experiments with virus stocks produced in primary human cells and anti-LFA-1 antibodies. Together, our results indicate that the association between some virus-bound host proteins and their natural cognate ligands can modulate de novo HIV-1 production by IM-MDDCs. Therefore, the additional interactions between virus-bound host cell membrane constituents and counter receptors on the surfaces of DCs can influence HIV-1 replication in IM-MDDC-T-cell cocultures.     

A Randomized Trial of Time-Limited Antiretroviral Therapy in Acute/Early HIV Infection

Background

It has been proposed that initiation of antiretroviral treatment (ART) very soon after establishment of HIV infection may be beneficial by improving host control of HIV replication and delaying disease progression.

Methods

People with documented HIV infection of less than 12 months’ duration in Baltimore MD and seven Canadian sites were randomized to either a) observation and deferred ART, or b) immediate treatment with ART for 12 months. All subjects not receiving ART were followed quarterly and permanent ART was initiated according to contemporaneous treatment guidelines. The endpoint of the trial was total ART-free time from study entry until initiation of permanent ART.

Results

One hundred thirteen people were randomized, 56 to the observation arm and 57 to the immediate treatment arm. Twenty-three had acute (<2 months) infection and 90 early (2–12 months) infection. Of those randomized to the immediate treatment arm, 37 completed 12 months of ART according to protocol, 9 declined to stop ART after 12 months, and 11 were nonadherent to the protocol or lost to follow-up. Comparing those in the observation arm to either those who completed 12 months of ART or all 56 who were randomized to immediate ART, there was no significant difference between the arms in treatment-free interval after study entry, which was about 18 months in both arms.

Conclusions

This study did not find a benefit from administration of a brief, time-limited (12-month) course of ART in acute or early HIV infection.

Trial Registration

ClinicalTrials.gov NCT00106171     

Mécanismes régulateurs des α-glucosidases épididymaires chez le rat

Epithelial cells of mammalian epididymis produced acid and neutral α-glucosidases (α-G) which are either modulated by hormonal systemic influences or by local factors arising from the rete testis fluid. In this study, ligation of ductuli efferentes in the rat was characterized by a modest elevation of both α-G 15 days after surgery. In adrenalectomized rats, both α-G are lower than in intact animals. Because of the continuance of spermatophagia 2 weeks after ductuli ligation, the observed enzymatic variations cannot be ascribed to paracrine influences; however, the effects of adrenalectomy on α-G levels are obvious and may be attributed to a multifactorial endocrine control (androgens and corticoids).     

Arginine esterase from isolated dog prostate secretory granules is fully active enzymatically

We have isolated secretory granules from dog prostate homogenates and have determined whether a major portion of arginine esterase was localized in this fraction and if it was enzymatically active. Secretory granules were purified by density gradient centrifugation on sucrose, metrizamide, or Percoll. A major proportion of whole prostate homogenate arginine esterase was found in the granule fractions. Furthermore, the specific enzymatic activity in the granules was similar to the one observed in seminal plasma. No evidence could be found for the existence of significant amount of a zymogen inactive form of arginine esterase. These results suggest that arginine esterase could be active within the secretory granules in vivo and that it could hydrolyze protein substrates contained in this organelle.     

Concentration and purification of influenza virus from allantoic fluid

A simple procedure which enables the concentration and purification of influenza virus, using an angular rotor, is described. Virus is concentrated over a sucrose step gradient. The same gradients are reused and volumes up to 4 liters are concentrated in 1 day. The concentrated virus is further purified by a simplified density-gradient technique. No host cell protein is detectable in the final product. The technique offers a broad application potential for concentrating and purifying other viruses.     

In vitro rearing ofLysiphlebus fabarum [Hym.: Braconidae]

In vitro rearing of the aphid endoparasitoidLysiphlebus fabarum (Marshall) (Hymenoptera, Braconidae) was attempted. Successful permanent cultures ofAphis fabae Sc. andMyzus persicae Sulz. cells were not obtained. Therefore, parasitoid larvae were reared in 2 unnatural media rone of which included cells ofCeratitis capitata Wied. (Diptera, Trypetidae). A group of larvae was reared in a substrate to which parasitoid teratocytes had been added. SinceLysiphlebus fabarum females did not oviposit into paraffin droplets including the substrates, the larvae were directly transferred from parasitized aphids into the rearing media. Several larvae reached the final instar, but only 2 out of the 48 tested in the 3 substrates became adults. The meaning of teratocytes inin vitro rearing of Aphidiine, Braconids is discussed. This work was supported by a grant from the italian Ministry of Education (M.P.I. 40%).