The effect of prenatal treatment with busulfan on in vitro androgen production by testes from rats of various ages

Treatment of rats with busulfan in utero severely depletes the germ cell population of the seminiferous tubules. These studies have examined the in vitro capacity of testicular tissue and Leydig cells from such testes to secrete androgens. Leydig cells were identified by staining for 3 beta-hydroxy steroid dehydrogenase. Rats were studied at several ages to identify any developmental changes in the androgen-secreting capacity of control and treated gonads. At 30 days of age, no effect of treatment on serum androgen was found. At 60 and 90 days of age, treatment caused decreased androgen and increased LH content of the serum. At 12, 30, 60, and 90 days of age, the amount of androgen secreted per milligram of testicular tissue in response to LH was higher in busulfan-treated rats. Leydig cells from 60- and 90-day-old rats which had received busulfan were also hyperresponsive to LH. It was concluded that Leydig cells from testes essentially devoid of germ cells were hyperresponsive to LH. Serum androgen levels were decreased yet androgen production per Leydig cell was increased. A possible explanation of this apparent paradox is that busulfan treatment resulted in decreased numbers of Leydig cells in the gonads.     

Expression of adult female patterns of sexual behavior by male, female, and pseudohermaphroditic female rhesus monkeys

Gonadally intact pseudohermaphroditic female and normal female and neonatally castrated male rhesus monkeys were given estrogen treatment as adults and evaluated for attractivity, proceptivity, and receptivity during tests with a tethered stud male. Pseudohermaphrodites were produced by injecting their mothers during pregnancy with either testosterone propionate (TP) or dihydrotestosterone propionate (DHTP). Castrated males had reliably lower attractivity than normal females on all indicator responses shown by the tethered males. Additionally, castrated males showed reliably fewer proceptive responses on 4 of 5 measures than normal females. Receptivity could not be assessed in this situation for castrated males, because tethered males never contacted them unless the castrated males were displaying presentation. No reliable differences were observed between pseudohermaphrodites produced by prenatal treatments with TP or DHTP. Pseudohermaphrodites generally showed reliably less attractivity and proceptivity than normal females and reliably more of these traits than castrated males. Attractivity scores for pseudohermaphrodites were not different from those for normal females until proximity to the tethered male was established. Receptivity was not different in pseudohermaphrodites compared with normal females. Results indicate prenatal androgenization and its developmental sequelae lead to a defeminization in adulthood which, in this testing situation, was principally manifested by a deficiency in the performance of proceptive behaviors. Additionally, defeminization in rhesus monkeys, unlike that demonstrated in rodents, does not depend upon actions of an aromatizable androgen.     

Neurotrophic regulation of GABA receptors at a crayfish inhibitory synapse

Experiments were done on the inhibitory synapse of crayfish tonic muscle receptor organs (MROs) to determine whether gamma-aminobutyric acid (GABA) receptors would be affected by denervation or axotomy. It was found that severing the dorsal nerve containing the MRO sensory and inhibitory neurons usually induced, in 30 days or less, a dramatic transformation in the responses of MROs to ionophoretically applied GABA. In contrast to normal MROs which show only inhibitory responses to GABA, transformed MROs were substantially depolarized and excited by GABA application to numerous points found on the axon, soma, dendrites. Interspersed among the points of excitation, normal inhibitory points could still be found on the transformed cells. The results suggested that chronic lesions can induced structural changes in GABA receptors, whereby the Cl- ionophore is replaced by a cationic channel. It was possible to compare the effects of postsynaptic axotomy alone with those of postsynaptic plus presynaptic axotomy by testing MROs from animals whose ventral nerve cord was sectioned. These experiments suggested that interruption of the presynaptic neuron is an important factor in the transformation. It was not determined whether complete degeneration of the inhibitory synapse is necessary for the transformation, but the rapidity of the effect, coupled with the probability of long-term survival of synaptic contacts, suggested that complete degeneration was not necessary. Similarities were found in the GABA responses of transformed MROs and those MROs which normally receive no innervation, which are located in the sixth abdominal segment. These results support the idea that trophic regulation from inhibitory neurons is a factor in stabilizing the association of the Cl- ionophore with GABA receptor.     

Comparative effects of trichothecene mycotoxins on bovine platelet function: Acetyl T-2 toxin,a more potent inhibitor than T-2 toxin

The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10^?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds.     

Potent inhibition of human immunodeficiency virus type 1 in primary T cells and alveolar macrophages by a combination anti-Rev strategy delivered in an adeno-associated virus vector.

The rate of viral replication appears to play a pivotal role in human immunodeficiency virus type 1 (HIV-1) pathogenesis and disease progression as it outstrips the capacity of the immune system to respond. Important cellular sites for HIV-1 production include T lymphocytes and tissue macrophages. Antiviral strategies, including newer treatment modalities such as gene therapy of HIV-1-susceptible cell populations, must be capable of engendering durable inhibitory effects to HIV-1 replication in both of these primary cell types in order to be effective. Among the potential genetic targets for intervention in the HIV-1 life cycle, the Rev regulatory system, consisting of Rev and its binding site, the Rev-responsive element (RRE), stands out as particularly attractive. Rev is essential for maintaining the stability of the viral genomic RNA as well as viral mRNAs encoding key structural and regulatory proteins. Moreover, it exhibits favorable threshold kinetics, in that Rev concentrations must rise above a critical level to exert their effect. To disable Rev function, primary T cells or macrophages were transduced with anti-Rev single-chain immunoglobulin (SFv) or RRE decoy genes either singly or in combination by employing adeno-associated virus vectors and then challenged with HIV-1. By directing both a protein and a nucleic acid against the normal interaction between Rev and the RRE, this genetic antiviral strategy effectively inhibited infection by either clinical or laboratory virus isolates. These results provide a framework for novel interventions to reduce virus production in the infected host.     

Active and passive cation transport and L antigen hertogeneity in low potassium sheep red cells

Several lines of experimental evidence are presented suggesting that the L antigens in low potassium (LK) sheep red cells are associated with separate Na(+)K(+) pump flux is distinct from the action of anti-L(l) on K(+) leak flux, implying that K(+) leak transport sites may not be converted into active pumps by the L antiserum. Treatment of LK red cells with trypsin completely abolished both the stimulation of K(+) pump flux and the enhancement of the rate of ouabain binding brought about by anti- L. That this effect is due to a total destruction of the L(p) determinant associated with the LK pump was evident from the complete failure of anti-L(p) to bind to trypsinized LK red cells. The L(p) antigen can be effectively protected against the trypsin attack by prior incubation with anti-L, indicating that the sites for antibody binding and trypsin action may be closely adjacent at the structural level. Trypsin treatment, however, did not interfere with anti-L(l) reducing ouabain insensitive K(+) leak influx, nor did it prevent binding of anti-L(ly), the hemolytically active L antibody which is probably identical with anti-L(l). The functional independence of the L(p) and L(l) sites was documented by the observation that anti-L(l) still reduced K(+) leak influx in LK cells with experimentally induced high potassium concentrations, at which K(+) pump flux is fully suppressed, whether or not anti-L(p) was binding to the L(p) antigen associated with the LK pump.