Human immunodeficiency virus rev protein recognizes a target sequence in rev-responsive element RNA within the context of RNA secondary structure

Human immunodeficiency virus type 1 Rev protein modulates the distribution of viral mRNAs from the nucleus to the cytoplasm by interaction with a highly structured viral RNA sequence, the Rev-responsive element (RRE). To identify the minimal functional elements of RRE, we evaluated mutant RREs for Rev binding in vitro and Rev response in vivo in the context of a Gag expression plasmid. The critical functional elements fold into a structure composed of a stem-loop A, formed by the ends of the RRE, joined to a branched stem-loop B/B1/B2, between bases 49 and 113. The 5' 132 nucleotides of RRE, RREDDE, which possessed a similar structure, bound Rev efficiently but were nonfunctional in vivo, implying separate binding and functional domains within the RRE. Excision of stem-loop A reduced Rev binding significantly and abolished the in vivo Rev response. The B2 branch could be removed without severe impairment of binding, but deletions in the B1 branch significantly reduced binding and function. However, deletion of 12 nucleotides, including the 5' strand of stem B, abolished both binding and function, while excision of the 3' strand of stem B only reduced them. Maintenance of the native RRE secondary structure alone was not sufficient for Rev recognition. Many mutations that altered the primary structure of the critical region while preserving the original RNA conformation were Rev responsive. However, mutations that changed a 5'..CACUAUGGG..3' sequence in the B stem, without affecting the overall structure abolished both in vitro Rev binding and the in vivo Rev response.

Cytotoxic effects of cyclophosphamide in the mouse seminiferous epithelium: DNA flow cytometric and morphometric analysis

Stage-specific cytotoxicity of cyclophosphamide (CP) in the mouse testis was analyzed by quantitative DNA flow cytometry and morphometry. In five series of experiments, three mice were injected (ip) with either a single dose of CP at 30 mg/kg or a vehicle saline. At 3, 11, and 20 days later, spermatogenic cells from stages II-V, VII-VIII, and IX-XI of the seminiferous epithelial cycle were quantified by flow cytometry and by morphometry. CP killed a part of the differentiating spermatogonia which became apparent at 11 days when the number of panchytene spermatocytes at stages II-V and VII-VIII was decreased. At stages IX-XI, the number of leptotene and zygotene spermatocytes declined at this time point. These damages could be detected by morphometry, while flow cytometry showed only the trend of the difference. At 20 days, both methods revealed a decrease in the number of haploid spermatids at stages VII-VIII (48 and 33% decrease detected by morphometry and flow cytometry, respectively). DNA flow cytometry proved to be a rapid and practical method to detect stage-specific disruption of spermatogenesis, while morphometry was more sensitive.

Multi-organ involvement of tuberculosis--case report of an atypical presentation

A case involving tuberculosis of multiple organs and mimicking carcinoma in several respects is presented.

Passive consumption of marijuana through milk: a low level chronic exposure to delta-9-tetrahydrocannabinol(THC)

Cannabis sativa grows abundantly among other natural vegetation in the northern part of Pakistan. Buffalo, the common dairy animals of the region, are allowed to graze upon this vegetation. These animals ingest significant amounts of marijuana, which after absorption is metabolized into a number of psychoactive agents which are ultimately excreted through the urine and milk. This potentially contaminated milk is used by the people of the region. Depending upon the amount of milk ingested and the degree of contamination, the milk could result in a low to moderate level of chronic exposure to Delta-9-Tetrahydrocannabinol (THC) and other metabolites especially among the children raised on this milk. This research was conducted to investigate the extent of passive consumption of marijuana by the consumers of potentially contaminated milk. Urine and milk specimens were obtained from buffalo and were analyzed for 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) which is a major metabolite for THC. The analysis was done by using gas chromatography/mass spectrometry. It was observed that during the months of June and July, 60 percent of the buffalo contained detectable levels of THC-COOH in their urine and 50 percent of these animals produced milk which was contaminated with THC or other metabolites. Analysis of the urine obtained from children with ages ranging from six months to 3 years, who were being raised on the milk from these animals, indicated that 29 percent of them had low levels of THC-COOH in their urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Alteration of follicular steroid secretion and thecal morphology after in-vitro exposure of individual pig follicles to follicle regulatory protein

Medium-sized (4-6 mm) pig follicles were incubated for 10 h and then examined via light microscopy. Treatment with pig FSH resulted in significantly increased concentrations of oestradiol, testosterone, androstenedione and progesterone in the medium. Follicle regulatory protein (FRP) alone (1 micrograms/ml) decreased follicular secretion of oestradiol (56%) and progesterone (53%) but stimulated the secretion of testosterone (226%) and androstenedione (139%). In the presence of 1 ng FSH/ml, the inhibitory effect of FRP on oestradiol secretion was enhanced (74%), progesterone values were unaffected and secretion of testosterone and androstenedione were reduced by 66% and 53%, respectively. All effects of FRP were fully overcome by 1 micrograms FSH/ml. The incidence of atresia, as defined by granulosa cell pycnosis, was similar in all treatment groups (1-3 of 10 follicles per group). The remaining follicles had intact granulosa cells. However, follicles treated with FRP (1 micrograms/ml) + FSH (1 ng/ml) had pycnotic nuclei in the theca interna cells, in the presence of an intact stratum granulosum. External exposure of follicles to FRP may not reflect physiological conditions since, in vivo, thecal pycnosis is never observed before granulosa cell pycnosis. However, the present results indicate that FRP is potentially capable of altering both follicular morphology and steroidogenesis. We suggest that FSH and FRP interact to affect follicular development.

Regulation of testicular inhibin subunit messenger ribonucleic acid levels in vivo: effects of hypophysectomy and selective follicle-stimulating hormone replacement

To examine the pretranslational regulation of inhibin subunits in the rat testis by FSH, we studied the effects of hypophysectomy with or without selective FSH replacement on testicular inhibin subunit mRNA levels in immature and adult animals. In the first experiment (Exp I), sexually immature (20-23 days old) intact and hypophysectomized male rats were killed 1, 3, and 7 days after surgery, and the testicular content of inhibin subunit mRNAs was determined by filter hybridization. A second group of immature, intact, or hypophysectomized rats was treated with saline or FSH for 7 days as follows: I) intact, saline; II) hypophysectomized, saline; III) hypophysectomized, FSH [0.05 microgram/100 g BW, sc, twice daily (BID)]; IV) hypophysectomized, FSH (0.50 microgram/100 g BW, sc, BID); V) hypophysectomized, FSH (5.0 micrograms/100 g BW, sc, BID); and VI) hypophysectomized, FSH (50.0 micrograms/100 g BW, sc, BID). In the second experiment (Exp II), adult (60 days old) intact or hypophysectomized animals were treated with saline, FSH, and/or testosterone for 7 days as follows: I) intact, saline; II) hypophysectomized; saline; III) hypophysectomized, 22-mm testosterone implant; IV) hypophysectomized, FSH (50.0 micrograms/100 g BW, sc, BID; and V) hypophysectomized, 22-mm testosterone implant plus FSH (50.0 micrograms/100 g BW, sc, BID. The effects of FSH and testosterone on testicular inhibin subunit mRNA levels were measured by filter hybridization. In Exp I, the level of inhibin alpha-subunit mRNA per testis was significantly lower in hypophysectomized rats than in intact controls at all time points after surgery. Replacement of FSH to hypophysectomized immature rats led to a dose-dependent increase in alpha-subunit mRNA per testis. However, hypophysectomy and FSH replacement had no significant effect on beta-B-subunit mRNA. In adult rats (Exp II), hypophysectomy significantly lowered and FSH replacement increased testicular inhibin alpha-subunit mRNA levels. Replacement of testosterone to adult animals, either alone or in combination with FSH, had no effect on expression of inhibin alpha-subunit mRNA. beta-B mRNA levels in adult testis were not significantly altered by any of the treatments. beta-A-Subunit mRNA levels were below the detection threshold of filter hybridization in both Exp I and II. Collectively, these data demonstrate that FSH regulates alpha- but not beta-B-subunit mRNA in the testis of both immature and adult rats in vivo. Differential regulation of inhibin subunits may provide a mechanism for creation and regulation of functional diversity of inhibin-related peptides in the testis.

Rev-induced modulation of Nef protein underlies temporal regulation of human immunodeficiency virus replication

The replication of human immunodeficiency virus type 1 (HIV-1) requires the concerted action of two virus-encoded transactivator proteins, Tat and Rev, and is in turn moderated by the viral transcriptional repressor Nef. We show here that the phenotype of a Rev- HIV-1 provirus was nonreplicating and was distinguished by accumulation of Nef protein and reduced Tat function. Provirus defective in both the rev and nef genes (Rev-Nef-) was also nonreplicating but had normal Tat function. Trans-complementation of the Rev- mutant with Rev caused a decrease of both the steady-state level and the rate of synthesis of Nef. This was accompanied by enhanced synthesis of viral structural proteins. Rev induced even greater levels of virus production from the Rev-Nef- double mutant. In contrast, exogenous Rev did not augment virus production from wild-type provirus. Virus production from Rev- and Rev-Nef- mutants induced by Rev was repressed by exogenous Nef. The repression induced by Nef could not be reversed by exogenous Rev. The ability of Rev to modulate Nef expression solely from the provirus, and thereby relieve the Nef-mediated inhibition of transcription from the viral long terminal repeat, reveals a delicate balance of the functions of these two proteins that might underlie the switch between latency and reactivation.

Quantitative assessment of the biological effects of follicle regulatory protein on dihydrotestosterone-maintained spermatogenesis in hypophysectomized rat

Follicle regulatory protein (FRP) isolated from porcine ovarian follicles influences folliculogenesis through a paracrine mechanism. A similar protein has been found in the testes and seems to have some inhibitory effects on spermatogenesis when administered to intact male experimental animals. On the basis of female and male studies, it has been ascertained that the effects of FRP are at the level of gonads and not the pituitary or the hypothalamus. In the studies with intact males it was not possible to determine the exact site of FRP action on the testes. Dihydrotestosterone (DHT) has been shown to maintain spermatogenesis in hypophysectomized rats. In order to determine if the inhibitory effects of FRP are at steps prior to the formation of DHT, FRP was administered to hypophysectomized rats that were injected with DHT. Groups of adult rats were hypophysectomized and treated daily with FRP, DHT, FRP + DHT, or vehicle alone for 30 days. At necropsy, body, testes, prostate glands, and seminal vesicle weights were recorded. One testis and sexual accessory glands were fixed for histological evaluation. The contralateral testis was decapsulated, six 2 mm segments of seminiferous tubules, representing defined stages of spermatogenesis, were isolated by transillumination-assisted microdissection, and spermatogenic cells were quantified by DNA flow cytometry. Histologically, the seminiferous tubules of vehicle-treated hypophysectomized controls showed advanced regression. Rats treated with FRP alone showed similar degeneration. On the other hand, rats treated with DHT showed maintenance of spermatogenesis comparable to normal controls. The testes of rats treated with FRP + DHT were indistinguishable from those treated with DHT only. Flow cytometric quantification of germinal cells from all groups confirmed the histological findings. In this study FRP did not exert deleterious effects on DHT-maintained spermatogenesis. This finding suggests that the inhibitory effects of FRP on spermatogenesis in intact animals may not be a direct effect on spermatogenic cells but may impair androgen action or production or DHT formation.

Flow cytometric quantification of rat spermatogenic cells after hypophysectomy and gonadotropin treatment

DNA flow cytometry was evaluated as a tool to analyze stage-specific changes that occur in absolute cell numbers in the testes. Hypophysectomy was selected as a model system for perturbing testicular cell types, since the cytological sequelae of this treatment post-hypophysectomy in the rat are well documented in the literature. Rat spermatogenic cells in stages II-V, VII, and IX-XIII of the seminiferous epithelial cycle (as defined by Leblond and Clermont, 1952) were quantified in numbers per standard length of seminiferous tubule by DNA flow cytometry after hypophysectomy and subsequent gonadotropin treatment. In agreement with previous histological studies, we found that acrosome- and maturation-phase spermatids disappeared from the seminiferous epithelium after 17 days post-hypophysectomy, whereas meiosis and early spermiogenesis continued at least 164 days. The number of meiotic cells and round spermatids gradually decreased after hypophysectomy. Changes were observed as early as Day 6 post-hypophysectomy. Treatment with human chorionic gonadotropin (hCG) alone maintained most cell numbers within normal limits, and follicle-stimulating hormone (FSH) was needed in addition to hCG to maintain the normal number of cells with the amount of DNA contained in primary spermatocytes and spermatogonia in G2/M-phase (4C) in stages IX-XIII and elongated spermatids (1C') in stages II-V of the epithelial cycle. The absolute numbers of spermatogenic cells at different phases of maturation provide a useful reference for quantitative studies of spermatogenesis. Pathological changes in the seminiferous epithelium can be detected and quantified by DNA flow cytometry.

Morphological and biochemical changes in the adult male rat reproductive system following long-term treatment with 1,2-dibromo-3-chloropropane

Adult Long-Evans male rats were treated with various dosages of pure or technical grade 1,2-dibromo-3-chloropropane (DBCP), epichlorohydrin (Epi), or allyl chloride (AC) for 1, 3, or 6 months on a daily basis. AC, which is the substrate for the production of DBCP, and Epi, which is a contaminant and/or metabolite of DBCP, had no effect on any of the parameters of the male reproductive system studied. The deleterious effects on male reproduction are therefore attributable specifically to DBCP. The effects of DBCP were dose and duration dependent. At the lowest dose (1 mg/kg) DBCP did not have any discernible effects on the male reproductive system. By 3 months of treatment at the intermediate dose of 5 mg/kg, the morphology of the testis ranged from normally appearing seminiferous tubules to ones which contained Sertoli cells only. At 6 months of treatment there was a reduction in the weights of the testes and sexual accessory glands. At the highest dose, the majority of the rats showed advanced testicular regression by 1 month of treatment. The most extreme testicular regression was observed in the 6-month treatment group. Almost all of the seminiferous tubules of all of the rats were composed of Sertoli cells only. In some of the animals, a few isolated seminiferous tubules contained an occasional spermatogonium or primary spermatocyte. Some of the Leydig cells of the rats in this group showed morphological evidence of atrophy as evidenced by the clumping of chromatin and paucity of stainable cytoplasm. This was confirmed by lower levels of intratesticular testosterone, a significant reduction in the number of luteinizing hormone (LH) receptors and increased serum levels of LH and follicle-stimulating hormone (FSH). From these results we conclude that DBCP is a specific male gonadotoxin and that the effects are not a result of contamination or metabolism. The effects appear to be a direct action at the testicular level because feedback inhibition to the pituitary gland was adversely affected.

Activation of anterior pituitary folliculo-stellate cells in the formation of estrogen-induced prolactin-secreting tumors

The response of folliculo-stellate (FS) cells of the anterior pituitary to estrogen has been studied in two strains of rat which differ in estrogen responsiveness. Fischer 344 (F344) rats are highly estrogen-responsive in comparison to Sprague-Dawley (S-D) rats. Ovariectomized adults were implanted with silastic capsules containing 17 beta-estradiol benzoate. Control and experimental animals were sacrificed 10 and 20 days after implantation of the silastic capsules. Most FS cells of F344 rats revealed dramatic changes, i.e. activation as phagocytes, after 10 and 20 days of estrogen treatment. These activated FS cells separated themselves from adjacent parenchymal cells and frequently contained phagosomes which included portions of granulated cells, mostly somatotrophs and lactotrophs. They also contained a variety of lysosomal dense bodies and dilated cisterns of endoplasmic reticulum. Endfeet processes abutting the parenchymal basal lamina contained large aggregates of dumbbell-shaped granules and tubulo-vesicles. Subjacent to the endfeet processes the basal lamina was often discontinuous, and profiles suggesting uptake of fragments of the basal lamina by FS cells were evident. Most FS cells of estrogen-treated S-D rats either were identical to those of controls or were only minimaly modified. However, a few activated FS cells were present and these contained a variety of lysosomal dense bodies and phagosomes, as well as lipid inclusions and dilated endoplasmic reticulum. Endfeet projections at the parenchymal basal lamina contained very few dumbbell-shaped granules or tubulo-vesicles, and the basal lamina was intact.(ABSTRACT TRUNCATED AT 250 WORDS)

The gag gene products of human immunodeficiency virus type 1: alignment within the gag open reading frame, identification of posttranslational modifications, and evidence for alternative gag precursors

Seven human immunodeficiency virus gag polypeptides were identified in the purified virus and in infected CD4+ lymphocytes by peptide mapping and limited amino acid sequencing of immune-purified proteins. Two gag polyproteins of 55,000 (p55) and 41,000 (p41) daltons were rapidly labeled and readily processed into the major internal gag proteins that were aligned within the gag open reading frame (ORF) as NH2-p16 (MA)-p24 (CA)-p9 (NC)-p7-COOH. The myristoylated p16 (matrix, MA) protein was processed from the myristoylated p55 gag precursor protein. The immunoreactivity of the p16 (MA) protein with region-specific gag antisera and the conservation of the N-terminal myristyl group of the p55 precursor protein in p16 (MA) confirmed its position as the N-terminal-most protein. The p9 (nucleocapsid, NC) protein was localized to residue 378 of the gag ORF, next to the C terminus of the p24/p25 (core antigen, CA) protein. The p9 protein had a repeating Cys residue containing motif which is found in the nucleic acid-binding Cys residue-containing proteins of retroviruses. The p24 (CA) protein, which was localized to residue 133 of the gag ORF, was apparently derived by C-terminal processing of an intermediate polypeptide, p25. Both the mature p24 (CA) and p16 (MA) proteins were phosphorylated at Ser residue(s). We also identified two forms of gag p41 species, one resulting from the C-terminal processing of p55 and the other originating either from N-terminal processing of p55 or from de novo synthesis.

The effects of fetal exposure to 1,2-dibromo-3-chloropropane on adult male reproductive function

Several drugs have been shown to cross the placental barrier and affect the fetal testis causing a reduction in testosterone with a resultant impairment of sexual differentiation and an ultimate problem in adult sexual function. In this study, pregnant female rats were treated with 25 mg/kg of the pesticide 1,2-dibromo-3-chloropropane (DBCP). Treatment began on Days 14.5, 16.5, or 18.5 and continued through Day 19.5 of gestation. Some animals were killed on Day 20.5 of intrauterine life and fetal intratesticular testosterone was measured. All other animals were allowed to deliver, and the males were raised to adulthood. At adulthood, body, testis, prostate glands and seminal vesicle weights were recorded. Intratesticular testosterone and luteinizing hormone (LH) receptors were measured. Male and female sexual behavior was quantified and the volume of the sexually dimorphic nucleus of the preoptic area of the hypothalamus was calculated. The histological appearance of the testis was also examined. Treatment for 6 days during fetal life with DBCP decreased intratesticular testosterone by 50% compared to controls at 20.5 days of gestation. At adulthood, all male rats treated during fetal life had a reduced body weight that was correlated with the duration of exposure. Adult testis weight was reduced to 75% of controls as a result of 2 days of fetal exposure to DBCP, whereas 4 and 6 days of exposure during fetal life reduced testis weight by greater than 90%. LH receptors and intratesticular testosterone, in the adults treated during fetal life, were also dramatically reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Nef protein of HIV-1 is a transcriptional repressor of HIV-1 LTR

In studies of the genetics of human immunodeficiency virus type 1 (HIV-1), the product of the nef gene, formerly known as F, 3'-orf, or B-ORF, was a negative regulator of HIV-1 replication. Proviruses with mutations in the nef gene replicated better than their standard counterparts during transient expression, and the mutant virus maintained its enhanced replication even after serial passages in T lymphocytes. The nef protein trans-suppressed, in a dose-dependent manner, the replication of wild-type and nef mutant proviruses and the expression of reporter genes linked to the HIV-1 long terminal repeat (LTR). The repression induced by the nef protein was mediated by inhibition of transcription from the HIV-1 LTR, which contains a far upstream cis element (previously recognized to be a negative regulatory element) between 340 and 156 nucleotides upstream of the RNA initiation site.

Purification and structural characterization of the putative gag-pol protease of human immunodeficiency virus

We have purified a 10,774-dalton protein from human immunodeficiency virus (HIV) type 1 that is encoded in the protease domain of the pol open reading frame (ORF). Radiochemical amino acid microsequencing identified 12 amino acids from the stretch of 39 N-terminal residues of this protein, beginning with a PQITLW sequence at position 69 of the pol ORF. Radiosequencing of selected tryptic peptides of the protein identified 11 additional residues (Leu-9 and Val-2) in six peptides encompassing the entire molecule of 99 residues. A protein of similar size and identical N-terminal sequence (determined through the first 39 residues) was present among the processed HIV pol gene products in Escherichia coli which expressed the entire HIV pol ORF. The C terminus of both the viral and E. coli-expressed proteins was inferred to be contiguous with the N terminus of the p64-p51 reverse transcriptase on the basis of tryptic mapping and specific immunoreactivity with an antiserum against a dodecapeptide located upstream of the reverse transcriptase. Thus, the initial processing of the pol precursor that generates the native protease is apparently preserved across phylogenetic barriers. Although the purified viral protease lacked measurable proteolytic activity, the bacterial extracts were capable of processing an HIV gag precursor protein synthesized in E. coli.

Post mortem studies on infertile buffalo bulls: testicular histology

Testicular tissues of 22 buffalo bulls (Bubalus bubalis) which suffered from three types of infertility were examined histologically. Nine bulls with no sexual libido showed underdeveloped seminiferous tubules; five of them also had various forms of germinal tissue hypoplasia (bilaterally complete, partial or incomplete) and in the other four the seminiferous tubules showed developed layers of germinal epithelium but no complete spermiogenesis. Among 11 bulls which had always produced poor quality semen one suffered from incomplete bilateral testicular hypoplasia and two had simple testicular degeneration; five showed marked testicular degeneration associated with fibrosis of intertubular spaces, and in three there was intertubular fibrosis and tubular stasis. In two bulls in which the quality of semen had deteriorated one showed bilateral partial testicular hypoplasia and the other had bilateral testicular degeneration with unilateral intertubular fibrosis and tubular stasis.

Mouse molar cell proliferation kinetics in vivo and in vitro

Patterns of cell proliferation kinetics have been examined in mouse first mandibular molars growing in vivo and in vitro. In vitro teeth were cultured on semi-solid medium or on Millipore filters. These conditions led respectively to normal and abnormal cusp formation. Similar cell-compartment specific mitotic activities existed in vivo and in vitro. Intradental control mechanisms exist. In vitro however the duration of cell cycle was lengthened, leading to lower rate of decrease of mitotic indices. The implications of these findings are discussed in the context of tooth morphogenesis and cytodifferentiation.

Iatrogenic Buschke's disease (Michelin man syndrome)

Scleredema [corrected] adultorum as originally described by Buschke in 1900, is cutaneous thickening of unknown aetiology. Since then several cases have been reported which have illustrated different aspects of the disease but the exact aetiology, pathogenesis and prognosis remain uncertain. Disease of possible iatrogenic origin appears not to have been described previously.