Viral proteins of bovine papillomavirus type 4 during the development of alimentary canal tumours

In cattle infection of the upper alimentary canal mucosa by bovine papillomavirus type 4 (BPV-4) results in the development of papillomas which can progress to cancer in animals fed on bracken fern. This paper describes a study of the cellular and subcellular distribution of a number of different BPV-4 products in experimentally-induced BPV-4 tumours. E8 and E4 proteins were detected solely as cytoplasmic antigens in the undifferentiated and differentiated layers of the papilloma, respectively; L2 was detected solely as a nuclear antigen in the differentiated layers, whereas E7 was present in either the nucleus or the cytoplasm depending on the differentiation stage of the keratinocyte. Replicative forms of viral DNA were detected from the spinous to the squamous layers. Viral antigens were not detected during papilloma regression or in carcinomas. E8 was most prominent in early developmental stages, while E4 and L2 were most abundant in mature papillomas. E7 was present in large amounts in both early and mature stages, declining at later stages. These results suggest a temporal and spatial requirement for the expression and function of the viral proteins.

Comparison between testosterone enanthate-induced azoospermia and oligozoospermia in a male contraceptive study. V. Localization of higher 5 alpha-reductase activity to the reproductive tract in oligozoospermic men administered supraphysiological doses of testosterone

Sex steroid contraceptive regimes result in incomplete suppression of spermatogenesis in 30-45% of Caucasian men. The basis for this is unclear, but differences in the activity of 5 alpha-reductase (5 alpha R) have been demonstrated. Two isoforms of 5 alpha R have been described: 5 alpha R1 is found in skin, whereas the predominant from in reproductive tissues is 5 alpha R2. To investigate possible contributions of these isoenzymes, we have investigated androgen-dependent changes in seminal plasma androgens (5 alpha R2) and sebum production (5 alpha 1) during administration of a supraphysiological dose (200 mg IM weekly) of testosterone enanthate (TE) to 33 normal men. Eighteen men rapidly (< 20 weeks treatment) became azoospermic, the remainder having a mean sperm density of 2.0 +/- 0.6 x 10(6) at that time. The concentrations of testosterone and 3 alpha, 17 beta-androstanediol glucuronide (AdiolG) were lower in seminal plasma than in blood but rose by a similar degree (100%) after 16 weeks TE treatment in both groups. There were no differences in seminal-plasma concentration of testosterone or AdiolG between azoospermic and oligozoospermic responders, either pretreatment or after 16 weeks TE treatment. Although the concentrations of dihydrotestosterone (DHT) were similar in seminal plasma and blood pre- and posttreatment, there was a selective increase in seminal plasma DHT concentration in the oligozoospermic responders from 2.12 +/- 0.29 to 2.94 +/- 0.33 nmol/L (P < 0.05), while there was no significant change in the azoospermic responders (2.18 +/- 0.31-2.54 +/- 0.27 nmol/L) after 16 weeks of TE treatment. Dihydrotestosterone in seminal plasma is primarily derived from 5 alpha R activity in the epididymis. The concentration of prostaglandin E2 (PGE2) in seminal plasma was unchanged during TE treatment. Sebum excretion was increased during TE treatment, but there were no difference between azoospermic and oligozoospermic responders pretreatment or after 16 weeks TE treatment. These results are consistent with the hypothesis that incomplete suppression of spermatogenesis during TE treatment is associated with a relatively higher 5 alpha R activity in the reproductive tract (epididymis and/or testis) during TE treatment. As the predominant form of 5 alpha R in the reproductive tract is 5 alpha R2 (type 2), we conclude that the increase in activity derives from this form of the enzyme, rather than the type 1 form (5 alpha R1) predominantly found in nongenital skin.

Cloning and in vitro expression of rat lecithin:cholesterol acyltransferase

Rat lecithin:cholesterol acyltransferase (LCAT) cDNA was obtained by reverse transcriptase/polymerase chain reaction amplification of rat liver total RNA. A consensus sequence was derived from four independent clones from two strains of rats. In vitro expression of rat LCAT cDNA in COS cells resulted in secreted enzyme protein with the same fatty acyl specificity for phospholipase A2 activity and cholesterol esterification as rat plasma LCAT, but different from that of recombinant or human plasma LCAT.

Differential expression of messenger ribonucleic acids encoding 11beta-hydroxysteroid dehydrogenase types 1 and 2 in human granulosa cells

In glucocorticoid target organs 11beta-hydroxysteroid dehydrogenase (11betaHSD) regulates the levels of active glucocorticoids available to glucocorticoid receptors. To date two isoforms of 11betaHSD, NADP-dependent type 1 11betaHSD (11betaHSD1) with predominant reductase activity and NAD-dependent type 2 11betaHSD (11betaHSD2) with dehydrogenase activity have been identified. Human ovarian granulosa cells have been shown to possess both dehydrogenase and reductase 11betaHSD activities and express 11betaHSD1 mRNA. However, whether 11betaHSD2 mRNA is also present or if the expression of either mRNA is developmentally regulated in the human ovary is unknown. We therefore used northern analysis to examine 11betaHSD1 and 11betaHSD2 mRNA levels in non-luteinized and luteinizing granulosa cells, corpora lutea (CL) and ovarian stroma obtained from human ovaries. Here we show that non-luteinized granulosa cells express relatively high levels of 11betaHSD2 mRNA but not 11betaHSD1. Conversely, luteinizing granulosa cells abundantly express 11betaHSD1 mRNA but not 11betaHSD2. CL also expresses 11betaHSD2 to lesser extent. Neither 11betaHSD mRNA is detectable in ovarian stroma. These results indicate that mRNAs encoding both 1lbetaHSD isozymes are present in human granulosa cells and they are developmentally--but differentially--regulated during preovulatory follicular development. The existence of developmentally regulated 11betaHSD in human granulosa cells is important new evidence that glucocorticoids, acting directly on the ovary, serve physiologically significant roles in the regulation of folliculogenesis.

Lack of toxicity of chromium chloride and chromium picolinate in rats

OBJECTIVE

To evaluate the safety of chromium (Cr) as a nutrient supplement. Several recent studies have reported beneficial effects of supplemental Cr at levels higher than the upper limit of the suggested intake for Cr. Trivalent Cr is considered relatively nontoxic but some recent unconfirmed studies have questioned its toxicity. We evaluated the toxicity of Cr chloride and a more bioavailable form of trivalent Cr, Cr tripicolinate.

METHODS

Harlan Sprague Dawley rats (4 weeks of age) were fed a stock diet to which was added 0, 5, 25, 50 or 100 mg of Cr per kg of diet as chloride or picolinate. Fasting blood samples were taken at 11 and 17 weeks and animals sacrificed at 24 weeks of age. Lack of toxicity was demonstrated by blood and histological measurements. Chromium incorporation into tissues was determined by graphite furnace atomic absorption.

RESULTS

There were no statistically significant differences in body weight, organ weights or blood variables among all the groups tested at 11, 17 and 24 weeks. Blood variables measured were glucose, cholesterol, triglycerides, blood urea nitrogen, lactic acid dehydrogenase, transaminases, total protein and creatinine. Histological evaluation of the liver and kidney of control and animals fed 100 mg/kg Cr as Cr chloride or picolinate also did not show any detectable differences. Liver and kidney Cr concentrations increased linearly for both the Cr chloride and picolinate fed animals.

CONCLUSIONS

These data demonstrate a lack of toxicity of trivalent Cr, at levels that are on a per kg basis, several thousand times the upper limit of the estimated safe and adequate daily dietary intake for humans. Animals consuming the picolinate supplemented diets had several-fold higher Cr concentrations in both the liver and kidney than those fed Cr chloride.

Effects of different chromium compounds on blood pressure and lipid peroxidation in spontaneously hypertensive rats

In a previous study, we found that oral chromium nicotinate overcame sucrose-induced hypertension in spontaneously hypertensive rats (SHR). Accordingly, we examined more chromium compounds to determine if others were more or less effective in regulating blood pressure (BP) of SHR. Since chromium is postulated to be an antioxidant, we also assessed the ability of different chromium compounds to alter free radical formation measured by determining thiobarbituric acid reactive substances (TBARS). The control group of SHR ingested a diet low in chromium, and 5 other groups ate the same diet with various chromium compounds added at 5 ppm-chloride, acetate, nicotinic acid-glycine-cysteine-glutamic acid (NA-AA), picolinate, and nicotinate. Following this, the rats were challenged with drinking water containing 5% and 10% w/v sucrose. Except for NA-AA, all chromium compounds inhibited the sucrose-induced elevation of systolic BP; and acetate, picolinate, and nicotinate chromium compounds lowered HbAIC below control. Only chromium acetate and nicotinate significantly lowered both hepatic and renal TBARS. Chromium picolinate lowered hepatic TBARS, and chromium chloride and NA-AA lowered neither. We conclude that chromium, rather than a specific ligand, plays a major role in ameliorating sucrose-induced BP elevations and can act as an antioxidant.

Physiological relationships between inhibin B, follicle stimulating hormone secretion and spermatogenesis in normal men and response to gonadotrophin suppression by exogenous testosterone

Inhibin has been postulated to be secreted by Sertoli cells in response to follicle stimulating hormone (FSH) and in turn to exert an inhibitory effect on FSH production. We have investigated this relationship using an assay specific for dimeric inhibin B. A total of 56 normal men received 200 mg testosterone enanthate (TE) i.m. weekly, for 65 +/- 1 weeks in a trial of hormonal male contraception. Before treatment a significant negative correlation between inhibin B and FSH concentration (r = 0.49, P < 0.001) was observed. During TE treatment, luteinizing hormone (LH) and FSH were rapidly suppressed. This was followed by a parallel decline in inhibin B and sperm concentration. During the early recovery phase, inhibin B concentrations remained suppressed in men who showed a delay in resumption of spermatogenesis, despite higher FSH concentrations. Inhibin B returned to pretreatment concentrations after 24 weeks recovery, when the inverse relationship with FSH was restored. Our results showed the expected inverse physiological relationship between inhibin B and FSH in normal men, with a decline during TE treatment and alpha subsequent resumption of the inverse relationship during recovery. These data clearly support the hypothesis that inhibin B plays a physiological role in the feedback control of FSH secretion, and reflects FSH-stimulated Sertoli cell function.

Beneficial effects of chromium on glucose and lipid variables in control and somatotropin-treated pigs are associated with increased tissue chromium and altered tissue copper, iron, and zinc

Chromium (Cr) and somatotropin have been shown to increase lean body mass in pigs but by independent mechanisms. Somatotropin and Cr also affect blood glucose, lipids, and tissue trace metal concentrations. Twenty-four castrated male pigs were divided into four groups: 1) control basal diet; 2) basal diet + 300 micrograms of Cr/kg of diet as Cr picolinate; 3) basal diet + pituitary porcine somatotropin (ppST; 100 micrograms/kg live weight injected daily); and 4) basal diet + Cr + ppST. Pigs were fed the diets from 30 to 60 kg body weight and then killed. Supplemental Cr led to increased total Cr in kidney (1.1 vs 2.3 micrograms) and liver (5.9 vs 8.8 micrograms) but not in the heart independent of ppST treatment. Chromium concentrations in longissimus muscle were less than 1.5 ng/g in all samples, and any increases due to supplemental Cr were not detected. Somatotropin treatment led to decreased hepatic Cr, Cu, Fe, and Zn concentrations and increased total renal Cu, Fe, and Zn. These data demonstrate that supplemental Cr causes increased tissue Cr in the liver and kidney but not in the heart or muscle in control and somatotropin treated pigs. Somatotropin treatment caused decreased kidney and liver Cr concentrations that were offset by increased tissue weights. Somatotropin effects on tissue Cr, Cu, Zn, and Fe were variable and difficult to evaluate due in part to growth hormone-induced changes in organ weights.

Immunosuppressive therapy: a potential alternative to bone marrow transplantation as initial therapy for acquired severe aplastic anemia in childhood?

PURPOSE

Currently bone marrow transplantation (BMT) with an HLA-identical sibling donor is recommended as optimal therapy for children with acquired severe aplastic anemia (SAA). Immunosuppressive therapy (IST) has become a very successful initial therapy for SAA in children lacking a related bone marrow donor. We wished to evaluate whether current IST regimens may be as efficacious as BMT.

PATIENTS AND METHODS

A retrospective review identified children treated for SAA over a 12-year period. Children with a related donor received a BMT. Children lacking a donor were treated with IST followed by a "rescue" BMT if IST was ineffective. IST consisted of anti-thymocyte globulin and steroid +/- cyclosporine A. Transfusion independence and survival rates were compared between the two groups.

RESULTS

Twenty-seven children were identified. Nine received a related BMT; seven of these survive and are transfusion independent (median follow-up 54 months). Sixteen of 18 patients who received IST are transfusion-independent survivors, including three of four patients who received a rescue BMT (median follow-up 33.5 months). Actuarial survival is 75% (95% CI = 45%, 105%) and 92% (95% CI = 78%, 107%) for the BMT and IST groups, respectively (p = 0.15). Severe toxicity was not experienced by any patient as a result of IST.

CONCLUSIONS

Equivalent rates of transfusion independence and survival were experienced by patients receiving BMT and IST. We propose that a prospective trial be undertaken to evaluate IST as initial therapy in all children with SAA, to be followed by BMT if there is inadequate response.

Interrupted blood feeding by Culex (Diptera:Culicidae) in relation to individual host tolerance to mosquito attack

Field studies at Delta Marsh (1991) and Winnipeg (1993), MB, and Vero Beach (1992), FL, examined variation among individual quail hosts in terms of the blood-feeding success by mosquitoes that fed on them. Culex tarsalis Coquillett was the predominant species collected in box traps baited with 2 quail at Delta Marsh in 1991, Culex nigripalpus Theobald was the predominant species collected at Vero Beach in 1992, and both Cx. tarsalis and culex restuans Theobald were collected in approximately equal numbers at Winnipeg in 1993. In 48 of 70 samples, blood feeding was skewed significantly from an even distribution between the 2 quail in each trap. In 5 of 13 samples of Cx. tarsalis collected in 1991, incomplete feeding (proportion of blood meals < or = 1/2 full) was from 2 to 8 times more likely on one bird relative to the other. In 7 of 13 samples of Cx. nigripalpus collected in 1992, incomplete feeding was from 2 to > 10 times more likely on one bird relative to the other. Incomplete feeding was from 2 to > 10 times more likely on one bird relative to the other is 7 of 11 mixed Cx. restuans/Cx. tarsalis samples collected in 1993. The probability that a given quail would interrupt a feeding mosquito was correlated negatively with the probability of the same quail being fed on. The proportion of detectable multiple meals in a given trap night was correlated negatively with the degree to which the distribution of blood meals in each trap night was skewed away from 0.5 on each bird. Individual quail varied significantly in terms of the blood feeding success of mosquitoes that fed on them.

A novel interaction between the juxtamembrane region of the p55 tumor necrosis factor receptor and phosphatidylinositol-4-phosphate 5-kinase

Tumor necrosis factor-alpha (TNF-alpha) binding to its receptors leads to a diversity of biological responses. The actions of TNF are the result of the interaction of cytoplasmic proteins that bind directly to the intracellular domains of the two TNF receptors, p55 and p75. Here we report a novel interaction between the juxtamembrane region of the p55 TNF receptor and a newly discovered 47-kDa isoform of phosphatidylinositol-4-phosphate 5-kinase (PIP5K), a member of the enzyme family that generates the key signaling messenger, phosphatidylinositol 4,5-bisphosphate. The interaction was found to be specific for the p55 TNF receptor and was not observed with the p75 TNF receptor, the Fas antigen, or the p75 neurotrophin receptor, which are other members of the TNF receptor superfamily. In vitro experiments using recombinant fusion proteins verify the authenticity of the interaction between the p55 receptor and PIP5KIIbeta, a new isoform of PIP5K, but not the previously identified 53-kDa PIP5KIIalpha. Treatment of HeLa cells with TNF-alpha resulted in an increased PIP5K activity. These results indicate that phosphatidylinositol turnover may be linked to stimulation of the p55 TNF receptor and suggest that a subset of TNF responses may result from the direct association of PIP5KIIbeta with the p55 TNF receptor.

Amino acid residue 149 of lecithin:cholesterol acyltransferase determines phospholipase A2 and transacylase fatty acyl specificity

Human LCAT prefers phosphatidylcholine (PC) with sn-1-palmitoyl-2-oleoyl PC (POPC) as substrate for cholesteryl ester synthesis, whereas rat LCAT (which is 92% similar in amino acid sequence) prefers sn-1-palmitoyl-2-arachidonoyl PC (PAPC). Six recombinant human LCAT cDNA clones were constructed with unique clusters of rat sequence substitutions in the human background spanning the region encoding amino acids 121-296. Media from transfected COS cells expressing each of the constructs were assayed for LCAT cholesterol esterification (CE) or phospholipase A2 (PLA2) activity using substrate particles containing POPC or PAPC. The PAPC/POPC CE activity ratio of the cluster 1 construct (amino acids 149-158) was 1.3, resembling rat LCAT, whereas cluster 2-5 clones produced CE activity ratios <0.3, unchanged from human LCAT. The cluster 6 clone (Y292H/W294F) had an intermediate ratio (0.6). Similar results were observed for LCAT PLA2 activity. In additional studies, position 149 of human LCAT was changed to the rat sequence (hE149A) and compared to a triple mutation containing the remainder of the cluster 1 changes (G151R/E154D/R158Q). CE and PLA2 activity ratio for the hE149A construct was >1.7, similar to rat LCAT, whereas the triple mutation construct retained a ratio similar to human LCAT (<0.6). Thus, a single amino acid substitution (E149A) was sufficient to alter the fatty acyl specificity of human LCAT to that of rat LCAT, with an increase in activity toward PAPC. This is the first example of a point mutation in an enzyme with PLA2 activity that results in an increase in activity toward arachidonic acid.

Type I phosphatidylinositol-4-phosphate 5-kinases are distinct members of this novel lipid kinase family

Phosphatidylinositol-4-phosphate 5-kinases (PIP5K) synthesize phosphatidylinositol-4,5-bisphosphate, a key precursor in phosphoinositide signaling that also regulates some proteins and cellular processes directly. Two distinct PIP5Ks have been characterized in erythrocytes, the 68-kDa type I (PIP5KI) and 53-kDa type II (PIP5KII) isoforms. Using peptide sequences from the erythroid 68-kDa PIP5KI, we have isolated cDNAs encoding PIP5KIalpha from human brain. Partial cDNAs obtained for a second isoform, PIP5KIbeta, established that the human STM7 gene encoded a previously unrecognized PIP5KI. However, the peptide sequences demonstrated that erythroid PIP5KI corresponded to PIP5KIalpha. Recombinant, bacterially expressed PIP5KIalpha possessed PIP5K activity and was immunoreactive with erythroid PIP5KI antibodies. By Northern analysis, PIP5KIalpha and PIP5KIbeta had wide tissue distributions, but their expression levels differed greatly. PIP5KIs had homology to the kinase domains of PIP5KIIalpha, yeast Mss4p and Fab1p, and a new Caenorhabditis elegans Fab1-like protein identified in the data base. These new isoforms have refined the sequence requirements for PIP5K activity and, potentially, regulation of these enzymes. Furthermore, the limited homology between PIP5KIs and PIP5KIIalpha, which was almost exclusively within the kinase domain core, provided a molecular basis for distinction between type I and II PIP5Ks.

Casein kinase I alpha and alpha L: alternative splicing-generated kinases exhibit different catalytic properties

Casein kinase I (CKI) is a family of serine/threonine protein kinases found in all eukaryotes examined to date. Here, the rat CKI isoforms alpha and alpha L were cloned and expressed in both eukaryotic and prokaryotic systems. Characterization of the genomic DNA flanking the exon unique to CKI alpha L demonstrated that CKI alpha and CKI alpha L arise by the alternative splicing of a common pre-mRNA molecule. To the best of our knowledge, the alpha L isoform is the only known active serine/threonine kinase to contain an insert within its catalytic domain. Tissue distribution of each splicing isoform was examined by RT-PCR, immunoprecipitation, and Western blotting. Both isoforms were expressed in all tissues tested but at different levels. Bacterially expressed CKI alpha isoforms were active and therefore biochemically characterized. CKI alpha and CKI alpha L proteins were demonstrated to have casein kinase I catalytic properties. More importantly, the recombinant isoform proteins exhibited differences in binding and activity toward common CKI substrates. These observations demonstrate that the alpha L insert within the kinase domain modulates substrate kinetics. These kinetic differences suggest that CKI alpha and CKI alpha L may perform different biological roles.

Home ovulation testing in a donor insemination service

The use of home ovulation testing kits in donor insemination (DI) has been proposed to increase patient and clinic convenience while not compromising fecundity rates. Such a system was introduced into our DI service in December 1994, and we here report an audit of experience over 6 months. Patients were offered home or laboratory luteinizing hormone (LH) testing, and those requesting home testing were asked to store an aliquot of tested urine for subsequent assay in the laboratory allowing retrospective analysis of the accuracy of cycle timing. Insemination using cryopreserved semen was performed on the day home testing predicted ovulation, or on the day an LH surge was detected in the laboratory, and on the following day. Pregnancy rates were significantly reduced in home testers: 3.4% per cycle (174 cycles, 64 women) versus 12.7% (110 cycles, 53 women) over the same time period (P < 0.005, 95% confidence interval 6.5-18.9). Urine samples from 140 cycles from 51 women using home testing were analysed. There were insufficient data in nine to allocate the cycle. Of home tested cycles, 37 (28%) were inseminated on a day other than the first day of the LH surge. In 13 of these insemination was performed after the first day of the LH surge. Incorrect treatment was associated with high baseline LH, but those with 'late' treatment had low basal LH concentrations, similar to those correctly treated. Analysis of individual urine samples showed that the positive predictive value of home testing was 72%. These results suggest that home ovulation testing results in reduced chance of pregnancy, with increased frustration for both patients and clinic staff. This may be particularly so in women with high baseline LH concentrations.

Paramagnetic beads coated with Pisum sativum agglutinin bind to human spermatozoa undergoing the acrosome reaction

For the evaluation of sperm functions it is important to assess the acrosome reaction after induction with various stimuli. Acrosome reaction tests normally include the capacitation of spermatozoa, treatment with an inducer, and detection of acrosomal loss by dyes, lectins or antibodies. Since most of these methods are time-consuming or require expensive equipment, paramagnetic beads coated with Pisum sativum agglutinin (PSA) were investigated for their usefulness in facilitating the detection of human sperm acrosome reaction. Binding of PSA beads to the acrosomal region increased significantly after incubation of capacitated spermatozoa with 10 microM A23187 (20.3 +/- 6.7% [mean +/- SD, absolute binding], n = 21), 1 mM dibutyryladenosine cyclic monophosphate (17.1 +/- 8.5%, n = 25) and 10 mM phorbol myristate acetate (21.1 +/- 12.5%, n = 10). Bead binding was significantly reduced by pre-incubation with a protein kinase inhibitor. Beads bound to Concanavalin A (ConA) were also attached to the acrosomal region after induction of the acrosome reaction by A23187 or dbcAMP, but a lower number of spermatozoa were bound to ConA-beads than to PSA beads. Pre-treatment of spermatozoa with alpha-methyl-D-mannoside before addition of the PSA beads markedly decreased bead binding, which indicates its mannose-specificity. Electron microscopic examinations demonstrated that PSA beads mainly bound to membrane structures of spermatozoa that were undergoing, but had not completed the acrosome reaction.

Interventions in response to chemically dependent nurses: effect of context and interpretation

Despite state laws and professional norms, administrators intervene in different ways in response to chemically dependent nurses. The purpose of this study was to examine how context and interpretation affect these interventions. Nurse administrators from 322 hospitals participated in the study. Regression analysis revealed a relationship between interpretation (threat or nonthreat) of chemically dependent nurses and the interventions. The higher the degree of threat perceived in relation to these nurses, the higher the tendency to terminate them (p<.01), and the lower the tendency to refer them to treatment (p<.05), reintegrate them (p<.01), and hire them (p<.01). Two context variables, professionalization and communication, were related to reintegration (p<.05). Understanding the relationship between context and interpretation on decision making will allow for progress toward improved management of the health care environment.

Definition of a human herpesvirus-6 betaherpesvirus-specific domain in glycoprotein gH that governs interaction with glycoprotein gL: substitution of human cytomegalovirus glycoproteins permits group-specific complex formation

Formation of the glycoprotein gH/gL heterooligomer has important implications for understanding the pathology of human herpesvirus-6(HHV-6)-associated disease because this complex is essential for infectivity and fusogenic cell-to-cell spread. Definition of the HHV-6 gH domain involved in protein-protein interactions was addressed by targeting regions defined by conserved cysteines identified by alignment of gH amino acid sequences representative of all herpesvirus subfamilies. Studies using site-directed mutagenesis and transient cellular expression showed that the N-terminus of HHV-6 gH includes a 230-amino-acid domain required for interaction with HHV-6 gL encompassing residues conserved specifically amongst betaherpesviruses. Interestingly, the human cytomegalovirus (HCMV) homologues, UL75 (gH) or UL115 (gL), can substitute for HHV-6 glycoproteins and participate in heterologous complex formation. Furthermore, the region which governs this heterologous gL binding also maps to the N-terminal portion of HHV-6 gH. Although both proteins can functionally substitute for complex formation there are also specific differences. Surprisingly, further deletion of HHV-6 gH to 145-amino-acid-domain residues abolishes complex formation with HHV-6 gL but allows interaction with HCMV gL. This may be related to requirements in HHV-6 for homodimer formation before complex formation between gH and gL. Under nonreducing conditions HHV-6 gH and gL form multimeric complexes consistent with intra- and intermolecular dimer formation stabilised by disulphide bonds whereas for HCMV there is no evidence for dimer formation for gH and multimeric complexes have only been observed between gH and gL. In summary, both HHV-6 and HCMV glycoproteins can interact and the heterologous complex between HHV-6 gH and HCMV gL is possibly more stable. This may result in important biological consequences in vivo during cellular coinfections by facilitating spread of the viruses, with applications to altered cellular tropisms and effects on reactivation from the latently infected cell.

Take charge: managing six transformations in health care delivery

Changes occurring in the health care industry are substantive and constitute a paradigm shift. Nurse managers can participate in shaping the health care organization of the future by understanding six critical areas of transformation and their driving forces.

Comparison between testosterone enanthate-induced azoospermia and oligozoospermia in a male contraceptive study. II. Pharmacokinetics and pharmacodynamics of once weekly administration of testosterone enanthate

Hormonal suppression of spermatogenesis is currently being investigated as a method of reversible male contraception. However, administration of exogenous testosterone (T) induces azoospermia in only 40-70% of Caucasian men, whereas the remainder suppresses to severe oligozoospermia (< 5 x 10(5)/mL). The reason(s) for the heterogeneity in the spermatogenic response is not clear. We have prospectively investigated the possibilities that higher plasma concentrations of T and/or differences in the extent and rate of gonadotropin suppression could maintain a low level of spermatogenesis in subjects taking part in a clinical efficacy trial of hormonal male contraception. Thirty-three healthy adult men, aged 21-41 yr, were given 200 mg T enanthate (TE), im, weekly for up to 18 months. Azoospermia was achieved in 18 men (55%) after 20 weeks of treatment, at which time the remaining 15 (45%) stabilized at a mean sperm density of 2.0 +/- 0.8 (+/- SD) x 10(6)/mL. These 15 subjects remained oligozoospermic for the rest of the efficacy study. To compare the pharmacokinetics and pharmacodynamics of TE between the azoospermic and oligozoospermic responders, plasma samples were obtained immediately before and 1, 2, 4, and 7 days after the 1st and 16th TE injections. Further samples were taken after 2, 4, 8, and 12 weeks of treatment. Plasma concentrations of total, free, and non-sex hormone-binding globulin (non-SHBG)-bound T, estradiol, LH, and FSH were measured. Compared to baseline, preinjection levels of total T increased 2.5-fold, reaching a steady state around 12 weeks of treatment. Peak concentrations of total T increased by 5-fold, but free and non-SHBG-bound T levels were increased by 10-fold after 16 weeks. The plasma levels of estradiol showed similar changes as T. However, neither T (bound or free) nor estradiol was significantly different between azoospermic and oligozoospermic responders. Plasma SHBG was reduced to a similar degree in both groups of men after 16 weeks of TE treatment. Plasma concentrations of both LH and FSH decreased rapidly after the first TE injection; a significant decline in LH was detectable after 24 h. Mean levels of both gonadotropins decreased to less than 0.5 U/L by the end of 4 weeks and to below the limit of sensitivity of the assays (0.05 IU/L) by 12 weeks. There were no significant differences in plasma concentrations of LH or FSH or in the rates of suppression between azoospermic and oligozoospermic responders. We conclude that the polymorphism of spermatogenic suppression in response to exogenous T is unlikely to be due to differences in the pharmacokinetics or pharmacodynamics of TE or in the sensitivity of the hypothalamo-pituitary-testicular axis to sex steroid inhibition. Measurements of total plasma T considerably underestimate the increase in bioavailable T during the weekly TE regimen.

Glycosylation structure and enzyme activity of lecithin:cholesterol acyltransferase from human plasma, HepG2 cells, and baculoviral and Chinese hamster ovary cell expression systems

The glycosylation state of lecithin:cholesterol acyltransferase (LCAT) may be important in determining its enzymatic activity. We compared glycosylation structure, enzyme kinetics, and phosphatidylcholine (PC) acyl specificity of human LCAT from four sources: human plasma (pLCAT), media from HepG2 cells (HepG2 LCAT), media from SF21 cells infected with a recombinant baculovirus (bLCAT) and media from stably transfected Chinese hamster ovary (CHO) cells (CHO LCAT). bLCAT was underglycosylated (molecular weight approximately 50 kDa) and resistant to digestion by N-glycanase F, endoglycosidase F, and neuraminidase. CHO and HepG2 LCAT were overglycosylated (approximately 68 kDa and approximately 70-75 kDa) compared to pLCAT (approximately 65 kDa). CHO LCAT, like pLCAT, was sensitive to N-glycanase F and neuraminidase but not to endoglycosidase F. HepG2 LCAT demonstrated resistance to N-glycanase F and endoglycosidase F. Apparent Km values for all four enzymes were similar (1.4-9.2 microM cholesterol) for recombinant high density lipoproteins (rHDL) containing sn-1 16:0, sn-2 18:1 PC (POPC). Apparent Vmax values (nmol cholesteryl ester formed/h per micrograms) were 52.6 for pLCAT, 48.6 for CHO LCAT, 15.3 for bLCAT, and 8.3 for HepG2 LCAT. Changes in PC acyl specificity in the presence and absence of cholesterol were characterized by comparing the ratio of LCAT activity on rHDL containing sn-1 16:0, sn-2 20:4 PC (PAPC) or POPC (PAPC/POPC activity ratio). The ratios for pLCAT, bLCAT, CHO LCAT, and HepG2 LCAT activity were 0.63, 0.49, 0.56, and 0.51 with cholesterol and 0.34, 0.29, 0.36, and 0.99 without cholesterol, respectively. We conclude that LCAT source influences glycosylation structure, which affects the apparent Vmax for cholesteryl ester formation with only minor changes in apparent Km or acyl substrate specificity.

Comparison between testosterone enanthate-induced azoospermia and oligozoospermia in a male contraceptive study. III. Higher 5 alpha-reductase activity in oligozoospermic men administered supraphysiological doses of testosterone

The administration of exogenous testosterone (T) to eugonadal men causes suppression of gonadotropin secretion and thus of spermatogenesis. This is currently being investigated as a possible method of hormonal male contraceptive, but complete suppression of spermatogenesis to azoospermia is induced in only 50-70% of Caucasian men; the remainder maintain a low rate of spermatogenesis. The basis for this polymorphism in response is unclear. The enzyme 5 alpha-reductase (5 alpha R) converts T to dihydrotestosterone (DHT) and is important in determining the magnitude of the androgen stimulus in some tissues. We investigated whether the maintenance of spermatogenesis in men remaining oligozoospermic while receiving suppressive doses of T is associated with evidence of increased 5 alpha R activity. Thirty-three normal men were given 200 mg T enanthate (TE), im, weekly in a clinical trial of hormonal male contraception. The MCR of T (MCRT) and the conversion ratio of T to DHT (CRT-DHT) were measured by infusion of [3H]T, plasma levels of DHT and androstanediol glucuronide (AdiolG) were measured by RIA, and 24-h urinary steroid metabolites were measured by capillary column gas chromatography. Sperm density decreased in all men; 18 achieved azoospermia by 20 weeks of treatment, and the remainder had a mean sperm density of 2.0 +/- 0.8 x 10(5)/mL at that time. This treatment caused increases in plasma T levels and MCRT, but with no differences between azoospermic and oligozoospermic responders. There were no differences in CRT-DHT plasma DHT, or AdiolG before treatment, but after 16 weeks, CRT-DHT had increased in the oligozoospermic responders, but not in the azoospermic responders. TE treatment increased plasma DHT and AdiolG levels in both groups, but the increases in both 5 alpha R metabolites were significantly greater in the oligozoospermic responders. Urinary excretion of etiocholanolone and androsterone was increased after 16 weeks of TE treatment, but did not differ between the two groups, andetiocholanolone/androsterone ratios did not differ greatly from unity. There was no change in urinary excretion of tetrahydrocortisol, allo-tetrahydrocortisol, or cortisone after 16 weeks of TE treatment in either group. These results suggest that after TE administration there is a selective increase in 5 alpha R activity in those men who remain oligozoospermic, but not in those becoming azoospermic. This difference in the androgenic milieu may underlie the incomplete suppression in the oligozoospermic responders, in whom a low rate of spermatogenesis is maintained despite the apparent absence of gonadotropins.