Crystalline keratopathy from Dieffenbachia plant sap

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Recombinant human granulocyte colony-stimulating factor infusion and/or autologous peripheral blood stem cell transplantation as a rescue for sequential high-dose combination chemotherapy: a preliminary report

BACKGROUND

Sequential cycles of combination chemotherapy with high-dose cyclophosphamide, etoposide and cisplatin (sHDCEP) can largely increase the total dose (TD) of drug delivered. If granulocyte colony-stimulating factor (G-CSF) and/or autologous peripheral blood stem cell (PBSC) rescue can shorten the duration of cytopenia between cycles of sHDCEP, the dose intensity (DI) can be increased as well. In order to explore the feasibility of delivering maximal TD and DI by administration of sHDCEP with G-CSF and/or PBSC rescue, this trial is undertaken to investigate the hematologic and nonhematologic toxicity observed with sHDCEP by G-CSF and/or PBSC rescue.

METHODS

Patients with refractory malignancy and well preserved physiologic function for whom no available therapy is likely to cure or prolong the survival were eligible for the study. Each cycle of high-dose chemotherapy consisted of: cyclophosphamide 5,000 mg/m2, etoposide 1,500 mg/m2 and cisplatin 150 mg/m2. G-CSF and/or PBSC were administered alternatively after each cycle as rescue for myelosuppression. The next cycle was given to patient who showed response to the previous cycle after recovery from toxicity for a maximal of 4 cycles.

RESULTS

Two cases of refractory malignancy with progressive disease were treated by sHDCEP for 7 cycles, including 4 cycles with G-CSF rescue, 2 cycle with PBSC rescue, and 1 cycle with G-CSF + PBSC rescue. In the 4 cycles rescued by G-CSF alone, we observed a slightly slower granulocyte and markedly prolonged platelet recovery in the subsequent cycle. By comparing the effect of G-CSF and/or PBSC rescue on hematologic recovery with the preceding cycle in the same patient, we found that G-CSF rescue provided faster granulocyte recovery than PBSC, but PBSC rescue provided faster platelet recovery than G-CSF. Rescue by larger number of PBSCs provided only faster platelet but not granulocyte recovery than rescue by adding G-CSF to a very small number of PBSCs. However, G-CSF plus the very small number of PBSCs provided shorter duration of both granulocytopenia and thrombocytopenia than rescue by G-CSF alone. The most common nonhematologic toxicity from sHDCEP included transient nausea, vomiting, diarrhea and mild impairment of liver function but we observed no significant or irreversible major organ damage. The side effect from PBSC collection was mild and toxicity from reinfusion of the thawed PBSCs was not obvious. Using G-CSF and/or PBSC rescue, sHDCEP was delivered repeatedly in no more than 4 weeks for the next-cycles except for patient 1 who had cycle 4 delayed because of prolonged platelet recovery by only G-CSF rescue in cycle 3.

CONCLUSIONS

Our initial experience has shown that the nonhematologic toxicity from sHDCEP, G-CSF and PBSC rescue was well tolerated. Prolonged platelet recovery after sequential cycles of HDCEP by only G-CSF rescue delayed the next cycle of chemotherapy. Although the next cycle was delivered within 4 weeks by only PBSC rescue, concurrent infusion of G-CSF and larger number of PBSCs should provide the most rapid hematologic recovery. Sequential high-dose chemotherapy administered by this model is likely to provide the maximal delivery of TD and DI, and is worthy of further clinical trials.

Baculovirus expression of the Ah receptor and Ah receptor nuclear translocater. Evidence for additional dioxin responsive element-binding species and factors required for signaling

In an effort to facilitate the structural and biochemical analyses of the Ah receptor (AHR) and the Ah receptor nuclear translocator (ARNT), a baculovirus system was developed to express microgram-milligram quantities of the human version of these proteins. To simplify purification, a polyhistidine tag was cloned at their C termini so that the recombinant proteins could be specifically adsorbed to nickel-nitriloacetic acid-Sepharose. Expression studies revealed that approximately 23% of the overexpressed AHR was recovered in cell extracts with the remaining 77% forming insoluble aggregates. ARNT was found to be more soluble, with 90% recovery from cell extracts and only 10% aggregation. Photoaffinity labeling and gel shift assays demonstrated that the recombinant proteins bound ligand, heterodimerized, and recognized their cognate "dioxin response element" (DRE) in a manner similar to their native counterparts. Coexpression of the AHR and ARNT in Sf9 cells resulted in the in vivo generation of heterodimers that bound the DRE in the absence of ligand. Studies with the nickel-nitriloacetic acid-purified recombinant proteins demonstrated that the AHR and ARNT could bind DRE only when reconstituted with a heat-sensitive factor(s) present in soluble extracts from a variety of cell types. Use of these proteins also demonstrated the existence of at least three AHR-dependent DRE-binding species, suggesting that the AHR can bind to DRE in at least three distinct conformations.

I-131-lipiodol cytotoxicity in hepatoma cells

Hepatoma is a common cancer in Taiwan. New effective treatment for hepatoma patients is urgently needed. Encouraging results of I-131-lipiodol treatment for hepatoma with minimal toxicity have been recently reported. The mechanism of lipiodol targeting and retention by hepatoma are not well understood. The cellular interaction of lipiodol and the cytotoxic effects of I-131-lipiodol on hepatoma cells were investigated in this study. HepG2 cells were cultured with lipiodol, and untreated HepG2 cells were used as the control. Changes of cellular morphology were accessed by light and electron microscopy. The uptake and retention of lipiodol by HepG2 cells were studied by phase contrast microscopy and neutron activation analysis. HepG2 cells were cultured with I-131-lipiodol varying from 0.12 microCi to 120 microCi. The cytotoxic effect of I-131-lipiodol was evaluated by the surviving fraction of HepG2 cells. Changes in cellular morphology was examined by light microscopy. Results indicated that HepG2 cells were capable of active uptake of large amounts of lipiodol by endocytosis and prolonged intra-cellular retention associated with the formation of many bulging cytoplasmic extensions. I-131-lipiodol was highly cytotoxic to HepG2 cells. There was a steep dose response relationship, and the effective dose (LD50) was 1.2 microCi (480 rads). The cytotoxic effects of I-131-lipiodol were associated with pleomorphism of HepG2 cells, an increase in cell size and nuclear-cytoplasmic ratio, an increase in the size and number of nuclei, and vacuolation of the cytoplasm around the nuclear regions. Multiple nucleoli, fragmentation and segregation and ring shaped changes of nucleoli were also observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary carnosine on plasma and tissue antioxidant concentrations and on lipid oxidation in rat skeletal muscle

The effect of dietary carnosine supplementation on plasma and tissue carnosine and alpha-tocopherol concentrations and on the formation of thiobarbituric acid reactive substances (TBARS) in rat skeletal muscle homogenates was evaluated. Plasma, heart, liver and hind leg muscle was obtained from rats fed basal semipurified diets or basal diets containing carnosine (0.0875%), alpha-tocopheryl acetate (50 ppm), or carnosine (0.0875%) plus alpha-tocopheryl acetate (50 ppm). Dietary carnosine supplementation did not increase carnosine concentrations in heart, liver and skeletal muscle. Dietary supplementation with both carnosine and alpha-tocopherol increased carnosine concentrations in liver 1.56, 1.51- and 1.51-fold as compared with diets lacking carnosine, alpha-tocopherol or both carnosine and alpha-tocopherol, respectively. Dietary supplementation with both carnosine and alpha-tocopherol also increased alpha-tocopherol concentrations in heart and liver 1-38-fold and 1.68-fold, respectively, as compared to supplementation with alpha-tocopherol alone. Dietary supplementation with carnosine, alpha-tocopherol or both carnosine and alpha-tocopherol was effective in decreasing the formation of TBARS in rat skeletal muscle homogenate, with dietary alpha-tocopherol and alpha-tocopherol plus carnosine being more effective than dietary carnosine alone. The data suggest that dietary supplementation with carnosine and alpha-tocopherol modulates some tissue carnosine and alpha-tocopherol concentrations and the formation of TBARS in rat skeletal muscle homogenates.

A phase II study of outpatient chemotherapy with cisplatin, 5-fluorouracil, and leucovorin in nasopharyngeal carcinoma

BACKGROUND

Systemic disease progression occurs in the majority of patients with locally advanced nasopharyngeal carcinoma (NPC). Although a variety of chemotherapeutic drugs have had tumoricidal activity, the roles of chemotherapy and optimal regimens must be further defined. Based on high response rates of Cisplatin, 5-Fluororacil and Leucovorin (PFL) in patients with advanced squamous cell cancers of the head and neck, we tested a new outpatient PFL chemotherapy program in patients with advanced NPC.

METHODS

Patients with NPC and 1) previously untreated, locally advanced disease; 2) local regional recurrence (LR) after radiotherapy; or 3) metastatic disease were eligible for study. Cisplatin 20 mg/m2/d, 5-FU 800 mg/m2/d and Leucovorin 90 mg/m2/d were administered simultaneously by continuous 96-hour intravenous infusion every three weeks. Patients were evaluated for response, survival, and toxicity.

RESULTS

Thirty-five patients were studied. The response rates of PFL therapy were 100% (15% complete response [CR], 85% partial response [PR]) in 20 patients with locally advanced or locally recurrent disease, and 80% (13.3% CR, 67.7% PR) in 15 patients with metastatic disease. The overall median survival was 20 months after therapy (range, 2-21). The median survival rate for previously untreated, locally advanced patients was not reached. The median survival rate for previously treated, local recurrence was 34 months and for metastatic patients was 14 months. Mucositis and leukopenia were the dose-limiting toxicities (20-23%, grade III) and occurred more frequently in patients previously irradiated. No treatment-related deaths occurred.

CONCLUSIONS

Outpatient PFL chemotherapy is active, safe, and convenient for advanced stage nasopharyngeal carcinoma patients, and the overall toxicities are tolerable.

Nitric oxide reverses acute hypoxic pulmonary hypertension in the newborn piglet

Inhaled nitric oxide has been reported to act as a specific pulmonary vasodilator. We used the newborn piglet to create acute hypoxic pulmonary hypertension and examined the effect of inhaled nitric oxide in this model. Six newborn piglets were instrumented in order to measure cardiac index, pulmonary arterial pressure, and systemic arterial pressure. Pulmonary hypertension was induced by reducing the fraction of inspired oxygen to 0.12 to 0.14. With hypoxia (arterial oxygen saturation between 35 and 45%), pulmonary arterial pressure increased by 48% (p < 0.01), pulmonary vascular resistance increased by 74% (p < 0.01), and both systemic arterial pressure and systemic vascular resistance decreased by 38 and 31%, respectively (p < 0.01). The animals were then giving varying concentrations of inhaled nitric oxide between 5 and 80 parts per million in random order. All concentrations of nitric oxide were associated with a rapid decrease in pulmonary arterial pressure and pulmonary vascular resistance (p < 0.001). Cardiac index increased (p < 0.001) and systemic vascular resistance significantly decreased (p = 0.01) with all doses of inhaled nitric oxide. The ratio of pulmonary to systemic vascular resistance decreased with all levels of inhaled nitric oxide (p < 0.001). For all of the above observations there was no significant difference noted between the varying doses of nitric oxide. The time course of the pulmonary arterial pressure response to nitric oxide was approximately twice as fast as that seen with the inhalation of 100% oxygen (10, 50, 90% responses of 4.1, 8.8, 88.6 versus 6.7, 51.9, 197 s, respectively; p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Polymerase chain reaction amplification and functional characterization of sockeye salmon histone H3, metallothionein-B, and protamine promoters

The histone H3 (H3), metallothionein-B (MT-B), protamine (PT) promoters of sockeye salmon were cloned by PCR using primers based on the DNA sequences of the rainbow trout promoters. Comparison of the DNA sequences of the sockeye salmon and the rainbow trout histone H3, MT-B, and PT promoters revealed that their DNA sequences and putative transcriptional cis-elements are remarkably conserved. Promoter activity of the sockeye salmon H3, MT-B, and PT promoters were examined by transfection studies using cell lines from fish and human. The H3 and MT-B promoters were shown to be active in all fish cell lines but were only weakly active in HeLa and GM637 cells. The MT-B promoter was also inducible by zinc and cadmium in RTH-149 cells. In contrast, the PT promoter was inactive in all fish cell lines. Transfection experiments also established that the HCMV IE promoter has very strong activity in the various fish cell lines. Our results suggest that the HCMV IE promoter and the sockeye salmon H3 and MT-B promoters are useful for the construction of expression vectors for transgenic and gene transfer studies in fishes.

RAPD analysis: an efficient method of DNA fingerprinting in fishes

Random Amplified Polymorphic DNA (RAPD) generated using arbitrary primers of 9, 10, 16 and 20 nucleotide lengths by Polymerase Chain Reaction (PCR) was investigated in 12 species of fishes. We found that the amplification products were best resolved by Urea-SDS-PAGE and detected by silver staining. The amplification products ranged from 25 to 75 depending on the primer and template combination. The random primers generated unique fingerprints for each species of fish in terms of number and position of RAPDs. Our results showed that the fish species can be distinguished from each other by RAPDs. The complexity of the RAPDs in the fingerprints may be manipulated to suit the requirement of the study. The use of RAPD in taxonomy, fishery management and fish culture is discussed.

Thoracoscopic pleural abrasion for pneumothorax

A thoracoscopic pleural abrasion technique is described. Pleural symphysis is obtained without thoracotomy. The procedure compliments thoracoscopic bullae resection in the management of spontaneous pneumothorax. The thoracoscopic abrasion technique is analogous to open pleural abrasion with a scouring pad.

Excimer laser photorefractive keratectomy in Singapore--a new treatment modality for myopia

BACKGROUND

Myopia is a national epidemic in Singapore. Photorefractive Keratectomy (PRK) for the treatment of myopia using the Argon Fluoride Excimer Laser commenced in January 1992 at the Singapore National Eye Centre.

METHODS

An open, prospective, non randomised clinical trial to assess the efficacy, predictability, stability, and safety of PRK for the correction of myopia between -2.0 to -6.0 dioptres.

RESULTS

One hundred and fifty-five eyes of one hundred and thirty-five patients underwent PRK between January and September 1992, of which thirty-one had completed at least six months of follow-up. Twenty-nine of the thirty-one patients (93.5%) achieved an unaided visual acuity of at least 6/12. Twenty-six patients (83.9%) were within 1 dioptre of emmetropia. There was an initial over-correction in all patients which regressed to a plateau at around three or four months. Corneal haze did not pose a significant problem. Three patients had ocular hypertension, and another developed a mild allergic reaction to the antibiotic-steroid ointment.

CONCLUSIONS

Excimer Laser Photorefractive Keratectomy is a very effective, fairly predictable, stable and safe surgical method for the treatment of myopia.

Mechanisms of regulation of liver fatty acid-binding protein

Liver fatty acid-binding protein (L-FABP) expression is modulated by developmental, hormonal, dietary, and pharmacological factors. The most pronounced induction is seen after treatment with peroxisome proliferators, which induce L-FABP coordinately with microsomal cytochrome P-450 4A1 and the enzymes of peroxisomal fatty acid beta-oxidation. These effects of peroxisome proliferators may be mediated by a receptor which has been shown to be activated by peroxisome proliferators in mammalian cell transfection studies. However, the peroxisome proliferators tested thus far do not bind to this receptor, known as the peroxisome proliferator-activated receptor (PPAR), and its endogenous ligand(s) also remain unknown. Peroxisome proliferators inhibit mitochondrial beta-oxidation, and one hypothesis is that the dicarboxylic fatty acid metabolites of accumulated LCFA, formed via the P-450 4A1 omega-oxidation pathway, serve as primary inducers of L-FABP and peroxisomal beta-oxidation. We have tested this hypothesis in primary hepatocyte cultures exposed to clofibrate (CF). Inhibition of P-450 4A1 markedly diminished, via a pre-translational mechanism, the CF induction of L-FABP and peroxisomal beta-oxidation. In further experiments, long-chain dicarboxylic acids, the final products of the P-450 4A1 omega-oxidation pathway, but not LCFA, induced L-FABP and peroxisomal beta-oxidation pre-translationally. These results suggest a role, in part, for long-chain dicarboxylic acids in mediating the peroxisome proliferator induction of L-FABP and peroxisomal beta-oxidation. We also found that LCFA, which undergo rapid hepatocellular metabolism, could become inducers of L-FABP and peroxisomal beta-oxidation under conditions where their metabolism was inhibited.(ABSTRACT TRUNCATED AT 250 WORDS)

A review of anaesthesia in ophthalmology

In this article, we review the methods of anaesthesia commonly used in ophthalmology in Singapore. These include topical, local, regional and general anaesthesia. Topical and local anaesthesia is adequate for most outpatient procedures. The most common form of regional anaesthesia in Singapore is still retrobulbar anaesthesia. General anaesthesia is used in children and when more extensive procedures are performed.

Induction of peroxisomal fatty acid beta-oxidation and liver fatty acid-binding protein by peroxisome proliferators. Mediation via the cytochrome P-450IVA1 omega-hydroxylase pathway

Both the enzymes of peroxisomal fatty acid beta-oxidation and the liver fatty acid-binding protein (L-FABP) are induced in the liver by peroxisome proliferators, such as clofibrate (CF), as well as high fat diets. One proposed mechanism for this induction is that it represents an adaptive response to altered intracellular fatty acid fluxes, mediated by dicarboxylic fatty acids formed via the cytochrome P-450IVA1 omega-oxidation pathway. The studies presented in this paper were designed to investigate the role of the products of P-450IVA1 omega-oxidation in the regulation of peroxisomal beta-oxidation and L-FABP. In primary hepatocyte cultures exposed to CF, the increase in P-450IVA1 activity preceded the induction of peroxisomal beta-oxidation and L-FABP. The CF-mediated increases in peroxisomal beta-oxidation and L-FABP, but not P-450IVA1, could be significantly inhibited pretranslationally by concurrent exposure of cultured hepatocytes to inactivators of cytochromes P-450, such as 1-aminobenzotriazole and 10-undecynoic acid. Hexadecanedioic acid, a 16-carbon dicarboxylic fatty acid, that is poorly metabolized in hepatocytes, induced peroxisomal beta-oxidation and L-FABP, but not P-450IVA1, via a pretranslational mechanism that was not inhibited by 1-aminobenzotriazole. Long-chain monocarboxylic acids were without such inducing effect. In further studies, non-beta-oxidizable dicarboxylic acid analogs were found to display greater potency as inducers of peroxisomal beta-oxidation when compared to hexadecanedioic acid. The inducing effects of the dicarboxylic acid analogs were also independent of the P-450 omega-oxidation pathway. The results of these studies suggest that the regulation of peroxisomal beta-oxidation enzymes and L-FABP is mediated, to a significant extent, by poorly metabolized long-chain dicarboxylic acids formed via the P-450IVA1 pathway.

Determinants of protein modification versus heme alkylation: inactivation of cytochrome P450 1A1 by 1-ethynylpyrene and phenylacetylene

Reaction of cytochrome P450 enzymes with arylacetylenes results in heme N-alkylation [e.g., Komives, E. A., and Ortiz de Montellano, P. R., (1985) J. Biol. Chem. 260, 3330-3336] and/or protein modification [e.g., Gan, L.-S. L., Acebo, A. L. and Alworth, W. L. (1984) Biochemistry 23, 3827-3836]. To clarify the factors that determine whether heme or protein alkylation occurs, we have investigated the cytochrome P450 1A1-catalyzed oxidation of 1-ethynylpyrene (1-EP) and phenylacetylene (PA). Cytochrome P450 1A1 in microsomes from beta-naphthoflavone-induced rats is inactivated in a time- and NADPH-dependent manner by 1-EP and PA. Parallel loss of the heme chromophore is observed with PA but not with 1-EP, although partial heme chromophore loss is observed when the purified, reconstituted enzyme is inactivated by either agent. Product analysis shows that 1-EP and PA are oxidized to, respectively, (1'-pyrenyl)-acetic and phenylacetic acids. In contrast to the inactivation of cytochrome P450 2B1 by PA, no isotope effect is observed on enzyme inactivation or metabolite formation when the acetylenic hydrogen is replaced by deuterium in either 1-EP or PA. Inactivation of cytochrome P450 1A1 by 1-EP results in covalent binding of 0.8-0.9 equiv (relative to total cytochrome P450 content) of the inhibitor to the microsomal protein. The results demonstrate that a single isozyme can be inactivated, depending on the structure of the arylacetylene, by heme or protein alkylation. Spectroscopic binding constants (Ks) show that 1-EP binds to the enzyme with > 2000 times greater affinity that PA.(ABSTRACT TRUNCATED AT 250 WORDS)

Preparation of [131I]lipiodol as a hepatoma therapeutic agent

An isotopic exchange method was used to label lipiodol with 131I. The labelling efficiency was > 92.5%, and the radiochemical purity of [131I]lipiodol was above 98% as determined by ITLC. The influencing factors e.g. the heating temperature, reaction time, pH and storage conditions were studied and the optimum conditions were determined. In a pilot study injecting [131I]lipiodol for the treatment of hepatoma, about 70% of hepatoma patients had a response to the treatment with a reduction of alpha-fetoprotein and decrease of hepatoma sizes. The overall median survival was 9 months (range 2-17 months).

From one to another

Organ transplantation is now well established as an excellent treatment for many previously fatal diseases of vital organs. For an organ to be of use to the recipient the cells must be alive but apart from kidney and hepatic lobe donation from a close blood relative, organs are removed from dead patients. The cause of death is usually a head injury or intracerebral bleed with permanent and complete destruction of the brain stem. Thus organ donation to save a life is usually associated with a tragedy for the donors and their families.

Mechanism-based probes of the topology and function of fatty acid hydroxylases

The use of three mechanism-based probes to investigate the topology and function of fatty acid hydroxylases is discussed. 1) The observation of protein rather than heme alkylation in the reaction of cytochrome P4504A1 with 10-undecynoic acid supports the argument that the enzyme circumvents the inherent preference for omega-1 hydroxylation by restricting access to the ferryl oxygen. 2) The regiochemistry of the ferricyanide-mediated iron-to-nitrogen shift of the cytochrome P450102 (P450BM-3) phenyl-iron complex indicates that the active site of this bacterial fatty acid hydroxylase is open primarily above pyrrole ring A of the prosthetic heme group, 3) Inhibition of clofibrate-mediated peroxisome proliferation in cultured rat hepatocytes by inactivation of cytochrome P4504A1 indicates that omega-hydroxylation of fatty acids provides a signal for peroxisome proliferation.

Epitaxial Cuprate Superconductor/Ferroelectric Heterostructures

Thin-film heterostructures of Bi(4)Ti(3)O(12)Bi(2)Sr(2)CuO(6+x), have been grown on single crystals of SrTiO(3), LaAlO(3), and MgAl(2)O(4) by pulsed laser deposition. X-ray diffraction studies show the presence of c-axis orientation only; Rutherford backscattering experiments show the composition to be close to the nominal stoichiometry. The films are ferroelectric and exhibit a symmetric hysteresis loop. The remanent polarization was 1.0 microcoulomb per square centimeter, and the coercive field was 2.0 x 10(5) volts per centimeter. Similar results were obtained with YBa(2)Cu(3)O(7-x) and Bi(2)Sr(2)CaCu(2)O(8+x), and single-crystal Bi(2)Sr(2)CuO(6+x)as the bottom electrodes. These films look promising for use as novel, lattice-matched, epitaxial ferroelectric film/electrode heterostructures in nonvolatile memory applications.

Protein overproduction in Escherichia coli: RNA stabilization, cell disruption and recovery with a cross-flow microfiltration membrane

After optimizing overproduction of a heterologous gene product (chloramphenicol acetyltransferase, CAT) using an RNA stabilization vector * in Escherichia coli (Chan et al., 1988), a single step cell disruption and recovery method * for obtaining a product stream essentially free of cell debris was developed. The behavior of an RNA stabilization plasmid (pKTN-CAT) containing stabilizing intron RNA was investigated in two different media both in batch and chemostat modes. CAT production of pKTN-CAT was consistently higher (3- to 7-fold) than that of the control lacking the stabilization sequences (pK-CAT). Highest CAT production was observed for cells grown in minimal medium in batch mode and induced for CAT expression early in growth. CAT production of cells grown in the chemostat mode exhibited an optimal dilution rate of about 0.1 h-1. Enhancement of protein production by pKTN-CAT as compared to pK-CAT tended to be higher when grown in rich medium rather than in minimal medium. Presence of the RNA stabilization plasmid did not significantly alter the growth rate of the cell. Using a combination of chemical treatment (1 mM EDTA) and shear stress resulting from cross-flow in a stainless steel microfiltration membrane *, CAT was released into the medium through disruption of the E. coli cells. The permeate flux increased from 2000 to 9000 kg m-2 h-1 with increasing axial Reynolds number from 10,000 to 60,000 or increasing mean shear stress from 12 to 47 Pa. The turbidity of the permeate was approximately 4% that of the retentate over this range of axial flow rates, indicating excellent removal of cell debris. Also, the concentration of CAT in the permeate was equal to that in the retentate over this range of axial flow rates, indicating complete passage of protein through the membrane. Thus, using a combination of chemical treatment and fluid-induced shear stress in a cross-flow membrane module, we were able to disrupt and recover the heterologous protein in a stream low in debris.

Development of a novel series of (2-quinolinylmethoxy)phenyl-containing compounds as high-affinity leukotriene receptor antagonists. 1. Initial structure-activity relationships

This series of reports describes the development of orally active, highly potent, specific antagonists of the peptidoleukotrienes containing a (2-quinolinylmethoxy)phenyl moiety. Described in this first report are the structure-activity relationships that led to a more than a 20-fold improvement of the potency and selectivity of the initial chemical lead (RG 5901). From this series of compounds, RG 7152 (16) was identified and selected for further evaluation in the clinic as an antiasthmatic agent. Compound 16 competitively inhibits [3H]LTD4 binding to membranes from guinea pig lung (Ki = 38 +/- 6 nM) and the spasmogenic activity of LTC4, LTD4, and LTE4 in parenchymal lung strips from guinea pigs. Unlike the original lead (RG 5901), compound 16 does not inhibit 5-lipoxygenase from guinea pig PMNs. Following oral administration to guinea pigs, 16 blocks LTD4-induced dermal permeability (ED50 = 6.9 mg/kg), LTD4-induced bronchoconstriction (ED50 = 1.1 mg/kg), antigen-induced bronchoconstriction (ED50 = 2.5 mg/kg), and anaphylactic-induced mortality (ED50 = 16 mg/kg). These studies on structure-activity relationships indicate that there is a requirement for an acidic function and the presence of the (2-quinolinylmethoxy)phenyl moiety in a specific geometric arrangement.

Transcription of the transforming genes of the oncogenic human papillomavirus-16 is stimulated by tumor promotors through AP1 binding sites

The promoter P97 of human papillomavirus-16 (HPV-16) gives rise to transcripts that encode the principal transforming genes of the virus, E6 and E7. The activity of P97 is regulated by a cell-type-specific enhancer, as well as by glucocorticoids and progesterone. We show here, that in CaSki cells, which contain HPV-16 genomes, P97 is also inducible by phorbol esters. Functional analysis of restriction fragments and oligonucleotides of the viral enhancer localizes two phorbol ester response elements on two transcription factor binding sites termed fp4e and fp9e. Sequence comparison, footprint analysis and bandshift competition of the cloned motifs suggest that both fp4e and fp9e are bound by the transcription factor AP1. These AP1 binding sites in HPV-16 and other papillomaviruses may provide a link between cellular oncogenes like jun, fos and possibly ras, whose transcription stimulating activity may lead to an elevated expression of the viral transforming genes E6 and E7.

Transcriptional activation of human papillomavirus 16 by nuclear factor I, AP1, steroid receptors and a possibly novel transcription factor, PVF: a model for the composition of genital papillomavirus enhancers

Human papillomavirus 16 (HPV-16), which is involved in genital carcinogenesis, contains an enhancer of transcription that is activated by cellular factors rather than by the viral E2 proteins. The activity resides on a 232 bp segment with 5 binding sites for nuclear factor 1 (NF1), 2 for AP1, and 1 for steroid receptors. Deletions and point mutations show that the constitutive enhancer and the steroid response depend on NF1 sites located 5' or 3' of a 65 bp fragment with AP1 sites that by itself shows little activity. Enhancement through a fragment with AP1 and NF1 sites is strongly reduced by mutation of the AP1 sites, or by mutation of the sequence AGGCACATAT. Sequence comparison and footprint analysis make it likely that this sequence binds a novel transcription factor which we call PVF. Fragments with one or several binding sites only for NF1, or AP1, or PVF exhibit little enhancement by themselves, suggesting the functional dependence of the HPV-16 enhancer on the cooperation of these factors. A comparison of our findings with the genomes and transcription factor binding sites of HPV-6, 11, 18, 31 and 33 lead us to propose a model of the composition of enhancers of genital papillomaviruses.

Receptor activity of rotavirus nonstructural glycoprotein NS28

Rotavirus morphogenesis involves the budding of subviral particles through the rough endoplasmic reticulum (RER) membrane of infected cells. During this process, particles acquire the outer capsid proteins and a transient envelope. Previous immunocytochemical and biochemical studies have suggested that a rotavirus nonstructural glycoprotein, NS28, encoded by genome segment 10, is a transmembrane RER protein and that about 10,000 Mr of its carboxy terminus is exposed on the cytoplasmic side of the RER. We have used in vitro binding experiments to examine whether NS28 serves as a receptor that binds subviral particles and mediates the budding process. Specific binding was observed between purified simian rotavirus SA11 single-shelled particles and RER membranes from SA11-infected monkey kidney cells and from SA11 gene 10 baculovirus recombinant-infected insect cells. Membranes from insect cells synthesizing VP1, VP4, NS53, VP6, VP7, or NS26 did not possess binding activity. Comparison of the binding of single-shelled particles to microsomes from infected monkey kidney cells and from insect cells indicated that a membrane-associated component(s) from SA11-infected monkey kidney cells interfered with binding. Direct evidence showing the interaction of NS28 and its nonglycosylated 20,000-Mr precursor expressed in rabbit reticulocyte lysates and single-shelled particles was obtained by cosedimentation of preformed receptor-ligand complexes through sucrose gradients. The domain on NS28 responsible for binding also was characterized. Reduced binding of single-shelled particles to membranes was seen with membranes treated with (i) a monoclonal antibody previously shown to interact with the C terminus of NS28, (ii) proteases known to cleave the C terminus of NS28, and (iii) the Enzymobead reagent. VP6 on single-shelled particles was suggested to interact with NS28 because (i) a monoclonal antibody to the subgroup I epitope on VP6 reduced particle binding, (ii) a purified polyclonal antiserum raised against recombinant baculovirus-produced VP6 reduced ligand binding, and (iii) a monoclonal antibody to a conserved epitope on VP6 augmented ligand binding. These experimental data provide support for the hypothesized receptor role of NS28 before the budding stage of rotavirus morphogenesis.

Progesterone and glucocorticoid response elements occur in the long control regions of several human papillomaviruses involved in anogenital neoplasia

We have previously identified in the long control region of the genome of human papillomavirus type 16 (HPV-16) a DNA segment which functions as a cell-type-specific enhancer as well as mediating glucocorticoid response. It contains multiple transcription-factor-binding sites, including several for nuclear factor I and one for the glucocorticoid receptor, which binds to the partially palindromic sequence TGTACANNNTGTCAT. We report here that this sequence element, when separated from the surrounding transcription-factor-binding sites and placed as an oligonucleotide into a test vector, retains its function as a glucocorticoid response element (GRE) in HeLa cells. In T47D cells, which express the progesterone receptor, the HPV-16 enhancer fragment mediates progesterone responsiveness. A point mutant in this fragment and the response of the oligonucleotide clone to both steroids prove the identity of the progesterone response element (PRE) with the GRE. The antiprogesterone and antiglucocorticoid RU486 interferes with both hormonal responses. In SiHa cells, the HPV-16 GRE mediates an increase in transcripts encoding E6 and E7 proteins, which are involved in transformation by HPV-16. Hormonal regulation is not restricted to HPV-16: DNA segments containing the cell-type-specific enhancers of HPV-11 and HPV-18 also mediate glucocorticoid and progesterone response. We identified sequence elements in the long control regions of HPV-11 and HPV-18 which function as GRE/PREs when tested as oligonucleotides. These findings suggest that GRE/PREs are an integral part of gene expression regulation in genital HPVs.

Differential effects of a series of hydroxamic acid derivatives on 5-lipoxygenase and cyclooxygenase from neutrophils and 12-lipoxygenase from platelets and their in vivo effects on inflammation and anaphylaxis

The synthesis of a series of novel substituted hydroxamates has been described along with their profile of inhibitory activity against 5-lipoxygenase, 12-lipoxygenase, and cyclooxygenase enzymes. The structure--activity relationship suggests that future molecules could be designed to specifically inhibit one or more of these enzymes since there were definite differences in structure--activity relationships for these different enzymes. A representative number of these compounds have been tested in vivo and found to possess potent oral activity in a systemic anaphylaxis model mediated by leukotrienes and topical activity in an arachidonic acid induced inflammation model. One of these molecules, compound 20, demonstrated that a leukotriene antagonist pharmacophore can be modified such that it contains both antagonist activity and 5-lipoxygenase inhibitory activity.

Cytogenetics of undifferentiated nasopharyngeal carcinoma xenografts from southern Chinese

Three undifferentiated nasopharyngeal carcinoma (NPC) tumour lines were successfully established from fresh biopsy material injected s.c. into athymic mice and passaged for many generations. These xenografts were found to be free of infiltrating lymphoid cells and remained undifferentiated up to passage 30. They were designated NPC/HK2117 (Xeno-1), NPC/HK1915 (Xeno-2) and NPC/HK1530 (Xeno-3), respectively. Passage 16 from Xeno-1, passage 1 from Xeno-2 and passage 14 from Xeno-3 were studied cytogenetically using G-banding with the trypsin-Giemsa method. Two xenografts were hyperdiploid with chromosome modal numbers ranging from 49 to 76, and one was hypodiploid with modal numbers ranging from 28 to 38. Five marker chromosomes have been identified with involvement of chromosomes 1, 3, 11, 12 and 17. Marker chromosomes derived from chromosomes 12q, 1q and 3q were consistent in one of the 2 xenografts successfully G-banded, and chromosomes 12, 11 and 17 were consistent in another. Three out of the 6 markers involve 12q13----qter. An abnormal chromosome 3 with most of the p arm deleted was also observed.

Stability of group I intron RNA in Escherichia coli and its potential application in a novel expression vector

Intron RNA excised from the primary transcript of the phage T4 td gene was found to be unusually stable in vivo. In contrast to the average half-life of about 1.5 min for a typical Escherichia coli mRNA at 37 degrees C, the half-life of the excised group-I td intron ranged from 12 to 19 min for the linear form and from 22 to 33 min for the circular form. A 631-nucleotide region of the intron that is not essential for splicing was replaced by the chloramphenicol acetyltransferase (CAT) structural gene (cat). Although the presence of the foreign sequence reduced intron stability several-fold, the half-life of the resulting intron-cat hybrid RNA was found to be twice that of the normal cat mRNA. The increase in stability was accompanied by a five- to eight-fold increase in CAT production above that seen with transcriptional activation from the strong Ptac promoter alone. The over-production was both temperature-dependent and partially splicing-dependent. This type of intron fusion represents a novel method of transcript stabilization, which is of potential use to augment other means of increasing gene expression for purposes of product amplification.

The catalytic site of rat hepatic lauric acid omega-hydroxylase. Protein versus prosthetic heme alkylation in the omega-hydroxylation of acetylenic fatty acids

Cytochrome P-450LA omega purified from clofibrate-induced rat liver oxidizes lauric acid to 11- and 12-hydroxydodecanoic acid in approximately a 1:17 ratio at a rate of 20 nmol/nmol P-450/min. In contrast, cytochrome P-450b oxidizes lauric acid much more slowly (0.5 nmol/nmol P-450/min) to an 8:1 mixture of the same metabolites. Western blot analysis indicates that P-450LA omega accounts for 1-2 and 16-30%, respectively, of the total cytochrome P-450 in uninduced and clofibrate-induced rat liver. Cytochrome b5 increases the efficiency of omega-hydroxylation but not the rate of catalytic turnover. Incubation of the enzyme with 10-undecynoic acid (10-UDYA) results in loss of approximately 45% of the enzymatic activity but none of the enzyme chromophore. Approximately 1 mol of 1,11-undecandioic acid is produced per mole of inactivated enzyme. This extraordinary inactivation efficiency is confirmed by NADPH consumption studies. Approximately 0.5 equivalents of label are covalently bound to the enzyme when it is incubated with 14C-labeled 10-UDYA. 11-Dodecenoic acid appears not to be a substrate for cytochrome P-450LA omega but is oxidized, presumably by a contaminating isozyme, to a 10:1 mixture of 11,12-epoxydodecanoic acid and 12-oxododecanoic acid. The results suggest the presence of two closely related P-450LA omega enzymes, only one of which is susceptible to inactivation by 10-UDYA. They also indicate that cytochrome P-450LA omega has a highly structured active site that sterically suppresses omega-1-hydroxylation in order to deliver the oxygen to the thermodynamically disfavored terminal carbon. Protein rather than heme alkylation follows from this reaction regiospecificity.

Topography of the simian rotavirus nonstructural glycoprotein (NS28) in the endoplasmic reticulum membrane

The simian rotavirus SA11 genome segment 10 codes for a nonstructural glycoprotein, NS28, that has been hypothesized to be involved in budding of viral particles into the endoplasmic reticulum (ER) membrane. Previous studies had suggested that NS28 is an integral membrane protein of the ER, possibly a transmembrane protein. We have examined the topography of NS28 inserted in microsomal membranes following cell-free translation of genome segment 10 transcripts. These transcripts were obtained either by hybrid selection of mRNA synthesized by the endogenous viral RNA polymerase or by in vitro transcription of genome segment 10 cDNA using SP6 polymerase. Full-length and truncated gene 10 transcripts were translated in a cell-free system supplemented with dog pancreatic microsomes. The existence of a cytoplasmic domain of the translation product was demonstrated by protease protection experiments. An 18,000 (18K) mol wt glycosylated polypeptide was protected from digestion with proteinase K and trypsin, whereas chymotrypsin digestion yielded a 23K mol wt glycosylated polypeptide. Correlation of these biochemical data with the known sequence of NS28 suggests that a 10K mol wt hydrophilic, carboxy-terminal fragment (from amino acid number 86 to amino acid number 175) of this glycoprotein is exposed on the cytoplasmic side of the ER membrane. A model of how NS28 folds in the ER membrane is proposed.

Aminoglutethimide augments follicle-stimulating hormone-induced aromatase activity in cultured porcine granulosa cells

The role of endogenous progestin synthesis in the modulation of FSH-induced aromatase activity was examined. Granulosa cells isolated from nonatretic medium-sized (3-5 mm) follicles of prepubertal pigs were cultured for an initial 48-h period, during which time aromatase activity was induced by FSH in the absence or presence of aminoglutethimide (AG). After induction, the cell monolayers were washed before being cultured for a further 6-h period in the presence of the substrate testosterone (0.5 microM). The aromatase activity was assessed by measuring the accumulation of estradiol during the test period. Basal aromatase activity was negligible and was unaffected by the presence of AG (0.1-100 microM) during the induction period. But when cells were cultured with FSH and AG (0.1-1000 microM) during the induction period, there was a dose-dependent, biphasic increase in the FSH-induced estradiol synthesis during the test period. Maximal enhancement was obtained with 10 microM AG (3.5-fold). Thereafter the aromatase activity declined and, at 1000 microM AG, was significantly (P less than 0.05) inhibited. At the same time, the FSH-stimulated progestin production during the induction period was inhibited in a dose-related fashion by AG. This AG-enhanced aromatase activity was dose and time dependent but was independent of the FSH concentration used. The apparent median effective dose of AG was 2.4 microM and a minimal time of 24 h or less was needed to potentiate the induction of aromatase activity by FSH. If AG was, however, added to the cell cultures during the test period, the FSH-induced aromatase activity was inhibited, showing that AG is an inhibitor of FSH-induced aromatase activity. This action of AG during the test period could be alleviated by the addition of testosterone during the induction period. The viability of the granulosa cells and the total cellular protein were not significantly (P greater than 0.05) altered by AG. These results show that the induction of aromatase activity by FSH could be enhanced by AG, which probably acts by inhibiting progestin production during the induction period, leading us to conclude that endogenous progestins might play an important role in modulating the induction of aromatase activity by FSH.

Human papillomavirus-16 and genital cancer: are tests for the viral gene expression in vitro indicators for risk factors in vivo?

Human papillomaviruses are found in up to 90% of all cervical carcinomas and are considered to play a causal role in the etiology of this malignancy. The genome of human papillomaviruses consists of a single circular DNA molecule with a size of approximately 8000 basepairs. 90% of this genome encodes proteins involved in functions such as neoplastic transformation of the host cell or formation of the viral capsid. The remaining 10% of the genome, which is termed upstream regulatory region (URR), harbours elements to control expression of the viral genes. We have identified in the URR DNA elements that regulate viral gene expression in the presence of glucocorticoid hormones or tumour promoting substances. This was done by DNase I protection experiments and functional analysis of fusion genes. Our data predict that the transforming potential of the virus might be stimulated by certain steroid hormones, polypeptide hormones and tumour promoting chemicals.

The cellular secretory pathway is not utilized for biosynthesis, modification, or intracellular transport of the simian virus 40 large tumor antigen

Unlike most proteins, which are localized within a single subcellular compartment in the eucaryotic cell, the simian virus 40 (SV40) large tumor antigen (T-ag) is associated with both the nucleus and the plasma membrane. Current knowledge of protein processing would predict a role for the secretory pathway in the biosynthesis and transport of at least a subpopulation of T-ag to account for certain of its chemical modifications and for its ability to reach the cell surface. We have examined this prediction by using in vitro translation and translocation experiments. Preliminary experiments established that translation of T-ag was detectable with as little as 0.1 microgram of the total cytoplasmic RNA from SV40-infected cells. Therefore, by using a 100-fold excess of this RNA, the sensitivity of the assays was above the limits necessary to detect the theoretical fraction of RNA equivalent to the subpopulation of plasma-membrane-associated T-ag (2 to 5% of total T-ag). In contrast to a control rotavirus glycoprotein, the electrophoretic mobility of T-ag was not changed by the addition of microsomal vesicles to the in vitro translation mixture. Furthermore, T-ag did not undergo translocation in the presence of microsomal vesicles, as evidenced by its sensitivity to trypsin treatment and its absence in the purified vesicles. Identical results were obtained with either cytoplasmic RNA from SV40-infected cells or SV40 early RNA transcribed in vitro from a recombinant plasmid containing the SP6 promoter. SV40 early mRNA in infected cells was detected in association with free, but not with membrane-bound, polyribosomes. Finally, monensin, an inhibitor of Golgi function, failed to specifically prevent either glycosylation or cell surface expression of T-ag, although it did depress overall protein synthesis in TC-7 cells. We conclude from these observations that the constituent organelles of the secretory pathway are not involved in the biosynthesis, modification, or intracellular transport of T-ag. The initial step in the pathway of T-ag biosynthesis appears to be translation on free cytoplasmic polyribosomes. With the exclusion of the secretory pathway, we suggest that T-ag glycosylation, palmitylation, and transport to the plasma membrane are accomplished by previously unrecognized cellular mechanisms.

Synthesis and immunogenicity of the rotavirus major capsid antigen using a baculovirus expression system

Rotaviruses are the major pathogens that cause life-threatening diarrhea in young children and animals. We inserted a simian rotavirus SA11 gene 6 cDNA into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus adjacent to the strong polyhedrin promoter. The major capsid antigen (VP6) was expressed in high yields (20 to 150 micrograms/10(6) cells) when Spodoptera frugiperda cells were infected with baculovirus recombinants containing SA11 gene 6 inserts. Reactivity with monospecific polyclonal and monoclonal antibodies suggested that VP6, expressed intracellularly or found in the media, maintained native antigenic determinants. VP6 purified from the media from infected cells also possessed a native oligomeric structure, was immunogenic in guinea pigs, and was able to spontaneously assemble into morphologic subunits. Antisera from immunized guinea pigs failed to neutralize virus in plaque reduction assays, but detected homologous and heterologous rotavirus strains when tested by immunofluorescence, immunoprecipitation, and enzyme-linked immunosorbent assays.

The inhibition of 3 beta HSD activity in porcine granulosa cells by 4-MA, a potent 5 alpha-reductase inhibitor

Addition of 17 beta-N,N,-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstane-3-one, a potent 5 alpha-reductase inhibitor, to granulosa cell cultures inhibited the FSH-stimulated progesterone synthesis during both the initial 48 h induction period and the subsequent 6h test period in a dose-dependent fashion. Besides being a more potent inhibitor of FSH-stimulated progesterone synthesis than testosterone, 4-MA also synergized with the androgen to inhibit progesterone synthesis. These results indicate that 4-MA has a direct inhibitory action on 3 beta-HSD.

Randomised study of ticarcillin, cefamandole with or without tobramycin in febrile, neutropenic patients with solid tumors

A prospective randomised study was conducted comparing the efficacy and toxicity of the antibiotics ticarcillin and cefamandole (TC) with or without tobramycin (TCT) in 100 febrile neutropenic patients with solid tumours undergoing conventional chemotherapy. In this study, neutropenia less than 100/microliter was noted in 31% of 106 evaluable infectious episodes and neutrophil counts less than 1,000/microliter persisted for a median 4 days. Infection was microbiologically documented in 42% of episodes (bacteremia 24%) with gram-negative organisms responsible for 63% of bacterial isolates. Overall, 65% of episodes responded to TC and 76% to TCT (p greater than 0.05). Patients with initial shock bacteremia, pulmonary infection, or gram-negative sepsis responded relatively poorly. Neutrophil nadir and pathogen susceptibility did not influence outcome. Antibiotic toxicity was minimal with no tobramycin-related nephrotoxicity. These results are broadly comparable to those observed with leukemic patients, but the relatively short duration of neutropenia in the solid-tumour patients appears to minimize the need for additional antibiotics provided there is adequate antimicrobial coverage with the initial choice of antibiotics.

Induction of aromatase activity in porcine granulosa cells by FSH and cyclic AMP

This paper examines the involvement of mRNA and protein synthesis in the induction of aromatase activity by FSH and also the site of action of androgens on FSH induction of aromatase activity in porcine granulosa cells. Treatment of cells with FSH or dbcAMP for an initial 48 h (induction period) resulted in an induction of aromatase activity, as measured by the production of estradiol during a subsequent 6h test period. Addition of testosterone to cells cultured with dbcAMP during the induction period enhanced the aromatase activity during both the induction and test periods. However, while DHT has no effect during the induction period, it significantly inhibited the aromatase activity during the test period. Culturing the granulosa cells with actinomycin D or cycloheximide during the induction period resulted in a dose-dependent inhibition of FSH induction of aromatase activity, suggestive of the synthesis of new protein(s). These results indicate clearly that FSH induction of aromatase activity involves the synthesis of mRNA and proteins.

Inhibition of follicle-stimulating hormone induction of aromatase activity in porcine granulosa cells by thyroxine and triiodothyronine

We examined the effects of T3 and T4 on basal and FSH-induced aromatase activity in granulosa cells isolated from medium-sized follicles (4-6 mm) of prepubertal pigs. Treatment of cells with T3 or T4 alone during an initial 48-h induction period did not result in any significant change in aromatase activity, as measured by 17 beta-estradiol accumulation during the subsequent 6-h test period, when testosterone (0.5 microM) was added as substrate. However, when cells were cultured with FSH and T3 or T4 during the induction period, a definite dose-dependent inhibition of FSH-induced aromatase activity was demonstrated. This inhibition was not altered by the presence of a binding protein (BSA). The inhibition of FSH-induced aromatase activity by T4 and T3 is a true biological effect, as inactive iodocompounds (MIT and DIT) and iodide had no significant effect on the gonadotropin-induced aromatase activity. Furthermore, the viability of cells was unaffected by the thyroid hormones, and total cellular protein did not change significantly. These results indicate that thyroid hormones might play an important role in modulating FSH-induced aromatase activity, and that the elevated plasma estrogen levels in some cases of hyperthyroidism are not due to increased ovarian secretion.

Two glycoproteins are produced from the rotavirus neutralization gene

The major neutralization antigen of rotaviruses is an outer capsid glycoprotein, VP7, with an apparent molecular weight of 38,000 (38K). The simian rotavirus SA11 genome segment 9, which codes for VP7, contains two in-phase initiation codons, each of which is followed by a sequence that codes for a region of hydrophobic amino acids. We have determined that this gene is functionally bicistronic by analyzing the synthesis of VP7 in SA11-infected cells and in cell-free translation systems programmed with hybrid-selected, segment 9 specific mRNA and dog pancreatic microsomes. The translation of hybrid-selected gene 9 mRNA in wheat germ extracts yielded two distinct polypeptides of molecular weights 37K and 35.3K. In vitro translation in the presence of microsomes yielded one diffuse band of 38K that was converted into the 37K and 35.3K precursor bands by digestion with endoglycosidase H. Studies with a variant of SA11 that lacks the glycosylation site in VP7 confirmed these precursor-product relationships and extended them by indicating that the glycoprotein produced by translation from the first AUG contained a cleaved signal sequence whereas the glycoprotein produced by translation from the second AUG contained an uncleaved signal sequence. Immunoprecipitation with monospecific anti-VP7 serum and improved gel electrophoresis conditions allowed us to show that both VP7s were expressed at similar times in infected cells and both were found in purified virus particles of several different rotavirus strains. Whether these two VP7 glycoproteins are functionally distinct remains to be determined.

FSH-induced aromatase activity in porcine granulosa cells: non-competitive inhibition by non-aromatizable androgens

The aim of this study was to examine the inhibitory effect of the non-aromatizable androgens on FSH-stimulated aromatase activity in porcine granulosa cells. The cells were isolated from medium-sized follicles (4-6 mm) of prepubertal pigs, and cultured under chemically defined conditions in the presence of FSH (1 microgram/ml, NIADDK-oFSH-S13) with and without the androgens for an initial 48-h induction period. Subsequently, the spent medium was replaced with fresh medium containing only testosterone as substrate and the cells were reincubated for a further 6 h. The conversion of this steroid to oestradiol-17 beta during this latter 'test' period was taken as a measure of the aromatase activity. The addition of 5 alpha-dihydrotestosterone (DHT) into cultures of FSH-stimulated cells during the induction period resulted in a definite dose-dependent inhibition (30-70%) of the aromatase activity expressed in the test period. This inhibitory action, of the mixed non-competitive type, is characterized by a decrease in the apparent Vmax and an increase in the Km value, suggestive of an androgen inhibition of FSH-stimulated aromatase synthesis. This inhibition was also shown by the other 5 alpha- and 5 beta-reduced androgens: 5 beta-androstanedione was the most effective, while DHT was the least. Other steroids such as pregnenolone and progesterone were inhibitory, but testosterone and diethylstilboestrol were stimulatory. These results suggest an important mechanism for the intrafollicular control of oestrogen synthesis, involving a possible reciprocal relationship between aromatase and 5 alpha-reductase activities.