Evidence for immune selection of hepatitis C virus (HCV) putative envelope glycoprotein variants: potential role in chronic HCV infections

E2/nonstructural protein 1, the putative envelope glycoprotein (gp72) of HCV, possesses an N-terminal hypervariable (E2 HV) domain from amino acids 384 to 414 of unknown significance. The high degree of amino acid sequence variation in the E2 HV domain appears to be comparable to that observed in the human immunodeficiency virus type 1 gp120 V3 domain. This observation and the observation that the HCV E2 HV domain lacks conserved secondary structure imply that, like the V3 loop of human immunodeficiency virus 1 gp120, the N-terminal E2 region may encode protective epitopes that are subject to immune selection. Antibody-epitope binding studies revealed five isolate-specific linear epitopes located in the E2 HV region. These results suggest that the E2 HV domain is a target for the human immune response and that, in addition to the three major groups of HCV, defined by nucleotide and amino acid sequence identity among HCV isolates, E2 HV-specific subgroups also exist. Analysis of the partial or complete E2 sequences of two individuals indicated that E2 HV variants can either coexist simultaneously in a single individual or that a particular variant may predominate during different episodes of disease. In the latter situation, we found one individual who developed antibodies to a subregion of the E2 HV domain (amino acids 396-407) specific to a variant that was predominant during one major episode of hepatitis but who lacked detectable antibodies to the corresponding region of a second variant that was predominant during a later episode of disease. The data suggest that the variability in the E2 HV domain may result from immune selection. The findings of this report could impact vaccine strategies and drug therapy programs designed to control and eliminate HCV.

A comprehensive analysis of the developmental and tissue-specific expression of the isoactin multigene family in the rat

The present study represents the first comprehensive analysis of isoactin gene expression in the developing rat. Our results clearly demonstrate that the developmental and tissue-specific expression of the actin multigene family is a highly integrated and complex process involving a variety of regulatory paradigms. The distinct temporal patterns of expression reported in this study indicate that there are three key phases in the regulation of expression of the actin multigene family during development. These include early embryonic development, late fetal development, and early postnatal development. The specific spatial patterns of expression observed in this study demonstrate that the expression of the actin multigene family is much more permissive than previously reported. This permissive expression includes a wide range of "ectopic" expression of the striated muscle isoactins as well as an extended expression of the alpha-smooth muscle isoactin. These findings expand our current understanding of the expression of the actin multigene family in development and provide a fundamental basis for future studies directed at investigating these processes.

The molecular biology of heparan sulfate fibroblast growth factor receptors

Two distinct classes of cell surface FGF-binding proteins have been identified. These receptors differ in both mode of interaction and in affinity for the FGFs. cDNAs that encode the low-affinity receptor were isolated from a hamster kidney cell line cDNA library by expression cloning. Transfected cells that contained these heparan sulfate proteoglycan FGF receptor cDNAs were enriched for by panning on basic FGF-coated plates. The analogous human cDNA was isolated from a hepatoma cell line cDNA library. The homology of our hamster cDNAs to the previously described murine integral membrane proteoglycan syndecan, together with an exact amino acid sequence match of our human-cDNA-encoded product to human syndecan, clearly indicates the identity of these independently isolated proteoglycans. Further confirmation that the expressed molecule serves as a proteoglycan core protein was achieved by immunoprecipitation of 35SO4-labeled material from solubilized transfected cells. Nitrous acid treatment and chondroitinase digestion revealed that 77% of the label was associated with heparan sulfate chains and 22% with chondroitin sulfate chains. These heparan sulfate chains contributed to the fivefold increase in the total heparan sulfate found to be present on the surface of the transfected cells compared with cells transfected with a vector lacking the cDNA insert.

Outflow facility and its response to pilocarpine decline in aging rhesus monkeys

Refractive error and total outflow facility were determined by Hartinger coincidence refractometry and two-level constant-pressure perfusion, respectively, in 17 rhesus monkeys, aged 5 to 29 years. Maximum accommodative response to corneal (iontophoretic) carbachol hydrochloride, baseline outflow facility, and the facility response to strong but submaximal intracameral doses of pilocarpine hydrochloride all declined with age. The correlation between accommodative response to carbachol and facility response to pilocarpine was slightly stronger than that between age and facility response. Since the ciliary muscle plays a major role in controlling both outflow facility and accommodation, and since histologic and videographic techniques demonstrate an age-related decline in rhesus ciliary muscle excursion induced by topical pilocarpine or electrical stimulation of the Edinger-Westphal nucleus, the present data support the hypothesis that an age-related decline in ciliary muscle mobility is associated, perhaps causally, with an age-related decline in facility and facility responsiveness to cholinergic drugs.

New developments in the drug treatment of glaucoma

This article reviews standard treatment modalities for patients with glaucoma and describes 3 classes of drugs which are undergoing development: apraclonidine (aplonidine, ALO 2145), an alpha 2-adrenergic agonist which has been released for clinical use; topical carbonic anhydrase inhibitors, a modification of the systemic carbonic anhydrase inhibitors currently in use; and prostaglandins (PGs), a new class of drugs with topical ocular hypotensive activity. Standard treatment modalities include parasympathomimetic agents such as pilocarpine, carbachol, and phospholine iodide, which lower intraocular pressure (IOP) by increasing aqueous outflow through the trabecular meshwork. A newer form of pilocarpine as a gel produces a longer action. Adrenergic agonist medications, such as epinephrine (adrenaline) and its prodrug dipivefrine (dipivalyl epinephrine), function by increasing uveoscleral outflow and trabecular outflow facility. A decrease in aqueous formation by the ciliary processes is thought to be the mechanism of action of beta-adrenoceptor antagonists, but the physiological basis for this action has not been clearly demonstrated. A newer beta-blocker, betaxolol, has relatively selective beta 1-blocking activity. Carbonic anhydrase inhibitors are nonbacteriostatic sulphonamide derivatives which decrease aqueous formation by the ciliary body. Almost 50% of patients taking these medications are unable to tolerate them because of their adverse effects, and there is thus much interest in the development of a topical carbonic anhydrase inhibitor with the potential for fewer adverse effects. MK 507 is the most recent and most potent compound in the series of topically active carbonic anhydrase inhibitors. Apraclonidine hydrochloride is a derivative of clonidine hydrochloride, an alpha 2-adrenergic agonist. Clonidine has previously been shown to lower IOP significantly, but has the potential to produce marked lowering of both systolic and diastolic blood pressures. Its major ocular effect appears to be a decrease in aqueous production. The structural modification to apraclonidine decreases corneal absorption and the drug's ability to cross the blood-brain barrier, minimising the risk of centrally mediated cardiovascular side effects. Apraclonidine may also influence secondary avenues of aqueous outflow, such as uveoscleral outflow, and may also affect conjunctival and episcleral vascular flow. It produces a mean decrease in IOP of 25% for as long as 12 hours. Adverse effects include blanching of the conjunctiva, minimal mydriasis and eyelid retraction. This drug has been approved in the US for use in prevention of elevated IOP after argon laser trabeculoplasty and iridotomy, and has potential uses in preventing an IOP rise after YAG laser posterior capsulotomy and cataract surgery in patients already on other antiglaucomatous medications.(ABSTRACT TRUNCATED AT 400 WORDS)

Variable and hypervariable domains are found in the regions of HCV corresponding to the flavivirus envelope and NS1 proteins and the pestivirus envelope glycoproteins

Based on the flavi- and pestivirus model of genome organization for the hepatitis C virus (HCV) (1-5), the nucleotide and deduced amino acid sequences of the putative envelope (E1) and the junction between the E1 and NS1/envelope 2 (E2) region from six different human isolates of HCV were compared with the nucleotide and predicted amino acid sequences of the prototype hepatitis C virus (HCV-1) (5). The overall percentage of nucleotide and amino acid changes among all six isolates, including HCV-1, from nucleotide 713 to 1630 (amino acid 129 to 437) was between 3 and 7%, which is comparable to that seen in some flaviviruses (6-8). An analysis of the number of nucleotide and deduced amino acid sequence changes among all six isolates and HCV-1 revealed a moderately variable domain of approximately 40 amino acids in the E1 region and a hypervariable domain (Region V) of approximately 28 amino acids, which is directly downstream from a putative signal peptide sequence, in the junction between E1 and NS1/E2. A similar hypervariable domain is not found in the C-terminus of the envelope polypeptide or in the N-terminus of the NS1 polypeptide domain of the flaviviruses. These findings suggest that the mature NS1/E2 polypeptide starts about amino acid 380 and that the NS1/E2 domain may correspond to a second envelope glycoprotein as in the case of the pestivirus. The observed heterogeneity in the putative structural proteins of HCV may have important ramifications for future vaccine development.

Ligand-affinity cloning and structure of a cell surface heparan sulfate proteoglycan that binds basic fibroblast growth factor

Expression cloning of cDNAs encoding a basic fibroblast growth factor (FGF) binding protein confirms previous hypotheses that this molecule is a cell-surface heparan sulfate proteoglycan. A cDNA library constructed from a hamster kidney cell line rich in FGF receptor activity was transfected into a human lymphoblastoid cell line. Clones expressing functional basic FGF binding proteins at their surfaces were enriched by panning on plastic dishes coated with human basic FGF. The amino acid sequence deduced from the isolated cDNAs revealed several interesting features, including hydrophobic signal and transmembrane domains that flank an extracellular region containing six potential attachment sites for glycosaminoglycan side chains. The structure also contains a short hydrophilic cytoplasmic tail sequence homologous to previously reported actin binding domains. Binding of basic FGF to cells expressing the binding protein could be inhibited by heparin and heparan sulfate but not by chondroitin sulfate, dermatan sulfate, or keratan sulfate. In addition to binding basic FGF, this protein or related surface proteins may function as an initial cellular attachment site for other growth factors and for viruses, such as herpes simplex virus.

Effects of various anesthetic and autonomic drugs on refraction in monkeys

Resting refractive correction in ketamine-, pentobarbital-, or halothane-anesthetized rhesus and cynomolgus monkeys was approximately 1-3 diopters myopic, with little difference under the various anesthetic regimens. Topical cyclopentolate or atropine, or systemic hexamethonium eliminated much of the myopia, while epinephrine, phenylephrine and thymoxamine had little effect. Anesthesia-induced myopia in monkeys thus seems comparable to tonic accommodation ("night myopia") in the human. Accommodation induced by electrical stimulation of the Edinger-Westphal nucleus averaged approximately 50% less under halothane than under pentobarbital, possibly due to halothane-induced systemic arterial hypotension.

In vivo videography of the rhesus monkey accommodative apparatus. Age-related loss of ciliary muscle response to central stimulation

Fourteen rhesus monkeys, aged 1 to 24 years, underwent permanent implantation of a bipolar stimulating electrode into the Edinger-Westphal nucleus and complete unilateral or bilateral iridectomy. Slit-lamp Scheimpflug videography of the lens and slit-lamp goniovideography of the lens equator, zonule, and ciliary body allowed direct real-time observation and video recording of the movements of these structures during centrally stimulated accommodation and during disaccommodation. Scalloping of the lens capsule at the zonular insertion sites was clearly visible during disaccommodation and even during accommodation when the zonules were folded. During accommodation, the lens became axially thicker, the ciliary ring narrowed, and, at high levels of accommodation, the zonular fibers slackened and even folded and the lens moved downward. With increasing age and concomitantly decreasing accommodative amplitude, these excursions all diminished, so that in the oldest animals, they were very minimal or absent. Maximum centrally stimulated accommodative amplitude declined with age on a time scale similar to that for cholinomimetic drug-induced accommodation in the rhesus monkey and voluntary accommodation in the human.

Reproducible stimulation of ciliary muscle contraction in the cynomolgus monkey via a permanent indwelling midbrain electrode

To better study the pivotal role of the ciliary muscle in ocular accommodation and aqueous humor outflow, a technique was developed to permit long-term reproducible stimulation of the muscle via the normal efferent neuronal pathway in cynomolgus monkeys. Following a small midline craniotomy, the stereotaxic coordinates of the Edinger-Westphal (E-W) nucleus were localized by contrast ventriculoradiography. A bipolar stimulating electrode was stereotaxically positioned to generate the maximum accommodative amplitude, and then permanently affixed to the surrounding cranium. Once experience was gained, the implant procedure required approximately 3 h and was well-tolerated by the animals, which subsequently exhibited normal behavior and no apparent discomfort or neurological deficits. Most animals retained the implant seemingly permanently (8-42 months follow-up), although a few animals extruded them after 4-8 months. Electrode placement in the E-W nucleus was verified histologically. The stimulation current and frequency-accommodative response relationships varied remarkably little between eyes, animals, or experimental sessions, although there was moderate inter-animal variation in the maximum accommodative amplitude. Using square-wave pulses of 0.5 ms duration, maximum accommodation, averaging approximately 15 diopters, was achieved at approximately 700 microA and approximately 70 Hz, and was greater under pentobarbital than under halothane anesthesia. Topical application of carbachol, eserine and echothiophate to the eye induced more accommodation than did central electrical stimulation. Permanent implantation of a stimulating electrode into the E-W nucleus may facilitate study of ocular physiological parameters dependent upon ciliary muscle contraction.

Retinoic acid proximalizes level-specific properties responsible for intercalary regeneration in axolotl limbs

The objective of this study was to determine whether retinoic acid (RA) coordinately proximalizes positional memory and the cellular recognition system that detects pattern discontinuity in regenerating amphibian limbs. The strategy was to test the capacity of RA-treated blastemas to evoke intercalary regeneration when grafted to an amputation level proximal to their level of origin. Control wrist and ankle, or elbow and knee blastemas treated with the retinoid solvent, dimethylsulphoxide, evoked intercalary regeneration as effectively as untreated blastemas, when grafted to the midstylopodial amputation surface of host limbs. RA-treated wrist and ankle or elbow and knee blastemas were proximalized and formed complete limbs that were at an angle to, or continuous with, the midstylopodium of the host limb. No intercalary regeneration, from either graft or host, was observed in these cases. The results indicate that the cellular mechanism that recognizes disparities between non-neighbouring cells and initiates intercalary regeneration is coordinately proximalized with positional memory. Thus the recognition mechanism and positional memory are directly related. Intercalary regeneration and corrective displacement (affinophoresis), both of which restore a pattern of normal cell neighbours by different means in regenerating axolotl limbs, appear to use the same mechanism to recognize pattern discontinuity.

Retinoic acid coordinately proximalizes regenerate pattern and blastema differential affinity in axolotl limbs

An assay that detects position-related differences in affinity of axolotl regeneration blastema cells in vivo was used to test whether retinoic acid, which proximalizes regenerate pattern, simultaneously proximalizes blastema cell affinity. The assay involved autografting or homografting late bud forelimb blastomas derived from the wrist, elbow or midupper arm levels to the dorsal surface of the blastema-stump junction of an ipsilateral, medium-bud-stage hindlimb regenerating from the midthigh level. The grafted blastemas consistently displaced to their corresponding levels on the proximodistal axis of the host regenerate, indicating the existence of level-specific differences in blastema cell affinity. Retinoic acid proximalized the pattern of donor forelimb regenerates to the level of the girdle and abolished their displacement behaviour on untreated host hindlimbs. Conversely, untreated forelimb donor blastemas displaced distally to their corresponding levels on host ankle regenerates, that had been proximalized to the level of the girdle by retinoic acid. These results indicate that positional memory in regenerating limbs is directly related to blastema cell affinity, and that very similar or identical sets of level-specific affinity properties are shared by forelimb and hindlimb cells.

Effects of topical PGF2 alpha on aqueous humor dynamics in cynomolgus monkeys

Single topical applications of prostaglandin F2 alpha (PGF2 alpha) tromethamine salt to living cynomolgus monkey eyes reduced intraocular pressure (IOP). Twice daily topical application was far more effective, so that after the 7th 50 micrograms or 100 micrograms dose on day 4, IOP fell 40-50%, to 8-10 mm Hg. Following twice daily application of 50 or 100 micrograms for greater than 3 days: (1) no increase in total outflow facility could be demonstrated by 2-level constant pressure perfusion or Schiotz tonography; (2) no decrease in aqueous humor formation rate could be demonstrated by fluorophotometry--rather, aqueous flow may have increased; (3) anterior chamber aqueous humor protein concentration was unaltered, but entry of intravenously injected fluorescein into the cornea and anterior chamber tended to increase; (4) there was a weak but sometimes statistically significant miosis of up to approximately 0.5 mm. We conclude that in the cynomolgus monkey: (1) PGF2 alpha is a potent ocular hypotensive agent with only very weak miotic and blood-aqueous barrier-disrupting effects; (2) the ocular hypotensive action of PGF2 alpha is definitely not due to increased conventional outflow facility or decreased aqueous production, but probably to increased uveoscleral drainage of aqueous humor.

Use of retinoids to analyze the cellular basis of positional memory in regenerating amphibian limbs

Cells of the amphibian limb regeneration blastema inherit memories of their level of origin (positional memory) along the limb axes. These memories serve as boundaries of what is to be regenerated, thus preventing regeneration of any but the missing structures. Because of its importance in determining the boundaries of regenerate pattern, it is essential to understand the cellular and molecular basis of positional memory. One approach to this problem is to look for position-related differences in a cell or molecular property along a limb axis and then show, using an agent that modifies regenerate pattern, that the cell or molecular property and the pattern are coordinately modified. We have done this using retinoic acid (RA) as a pattern-modifying agent and an in vivo assay that detects position-related differences in a cell recognition-affinity property along the proximodistal (PD) axis of the regenerating axolotl limb. RA proximalizes positional memory in the PD axis, posteriorizes it in the anteroposterior axis, and ventralizes it in the dorsoventral axis. The level-specific PD cell recognition-affinity property is proximalized by RA, indicating that this property and positional memory are causally related. The effects of RA on positional memory may be mediated through a cellular RA-binding protein (CRABP), since the concentration of unbound (apo) CRABP molecules is highest during early stages of regeneration when the proximalizing effects of RA are greatest.

Pilocarpine antagonizes prostaglandin F2 alpha-induced ocular hypotension in monkeys. Evidence for enhancement of Uveoscleral outflow by prostaglandin F2 alpha

Twice daily topical application of 50 micrograms of prostaglandin F2 alpha tromethamine to cynomolgus monkey eyes produced significant ocular hypotension lasting at least six hours, with the intraocular pressure (IOP) falling between 35% and 50%, ie, to about 8 to 10 mm Hg, following the seventh dose. A single topical application of 1 mg of pilocarpine hydrochloride produced a much smaller IOP reduction and strong, probably maximal accommodation, both of which lasted at least eight hours. When prostaglandin F2 alpha-treated eyes were given pilocarpine before the seventh dose of prostaglandin F2 alpha, accommodation and IOP responded as in eyes receiving pilocarpine only. Atropine sulfate pretreatment of eyes receiving pilocarpine and prostaglandin F2 alpha completely prevented pilocarpine-induced accommodation and inhibition of ocular hypotension induced by prostaglandin F2 alpha. We hypothesize that (1) prostaglandin F2 alpha reduces IOP by increasing uveoscleral drainage of aqueous humor, and (2) pilocarpine pretreatment contracts the ciliary muscle, obliterating the intramuscular spaces and closing off the uveoscleral drainage pathway and thus physiologically blocking the effect.

Bio-electric conductivity potentials in experimental skin grafts

Prior investigations have established that changes in bio-electric potentials accompany the processes of wound creation and healing. In order to investigate these changes in an experimental full-thickness skin graft model, grafts were harvested from the dorsa of eight albino rabbits. Changes in potential were recorded over a period of 32 days, using silver-silver chloride electrodes and a recording polygraph. The potential measured across the skin graft became increasingly more electropositive until, between days 1 and 2, the potential abruptly reversed polarity. This negative potential lasted until day 4, when the conductivity again became positive, with a slow return to baseline measurements by day 32. Although these observations may indicate a bio-electric counterpart to the cellular events of wound healing, more study is needed.

Hypnosis and lateral cerebral function as assessed by dichotic listening

In a replication of Frumkin et al. we investigated the hypothesis that hypnosis may facilitate a shift in brain hemispheric dominance, as assessed by right-ear dominance shifts in a dichotic listening paradigm. Eight low, 13 medium, and 8 high hypnotizables, as assessed by the Stanford Hypnotic Susceptibility Scale, Form C, were given the Berlin et al. dichotic tape during two waking conditions and following an alert hypnotic induction. Results contradicted Frumkin et al. In contrast, low hypnotizables showed a significant reduction in right-ear dominance, suggestive of greater participation of the right cerebral hemisphere following hypnotic induction. Highs and mediums did not change. Discussion centers around procedural differences between the two studies (particularly type of hypnotic induction and instructions to attend to one or both ears) and the possible influence of relaxation/anxiety levels upon lateral shifts in cerebral function.

The development of human fetal dorsal root ganglia in vitro: the first 20 days

Human fetal dorsal root ganglia aged from 8 to 12 weeks post-menstrual were grown in vitro for up to 20 days. Outgrowth of Schwann cells, axons and fibroblasts occurred after 4 h. By the 7th day in vitro Schwann cells enclosed bundles of axons and after 10 days some Schwann cells were seen to enclose individual axons. By the 20th day in vitro there was still a predominance of Schwann cells enclosing axonal bundles, but there were more individual axons ensheathed by three or four turns of Schwann cells. This arrangement mimics the early development in vivo of human dorsal root ganglia and provides the potential for an experimental system utilizing human nervous tissue rather than non-human animal models.

Prevention of the mutagenic activation of an antischistosomal isothiocyanate in primates by an antibiotic

Administration of 4 nitro-4' isothiocyano-diphenylamine (CGP 4540, amoscanate) to two nonhuman primates, Macaca mulatta and Cebus apella, resulted in the appearance of mutagenic material in the urines of these animals. Mutagenic metabolites of this drug could also be detected in the urines when the drug was administered to primates infected with Schistosoma mansoni and Schistosoma japonicum. As observed previously in mice, the mutagenic activation of amoscanate can be prevented in primates by coadministration of a single oral dose of erythromycin with no concomitant reduction in antischistosomal activity. The protective effect of erythromycin was confirmed in several crossover experiments. This dissociation of mutagenic from chemotherapeutic effects provides an opportunity to reduce serious potential long-term risks of this antischistosomal drug.

Kinetic properties of Serratia marcescens adenosine 5'-diphosphate glucose pyrophosphorylase

The regulatory properties of partially purified adenosine 5'-diphosphate-(ADP) glucose pyrophosphorylase from two Serratia marcescens strains (ATCC 274 and ATCC 15365) have been studied. Slight or negligible activation by fructose-P2, pyridoxal-phosphate, or reduced nicotinamide adenine dinucleotide phosphate (NADPH) was observed. These compounds were previously shown to be potent activators of the ADPglucose pyrophosphorylases from the enterics, Salmonella typhimurium, Enterobacter aerogenes, Enterobacter cloacae, Citrobacter freundii, Escherichia aurescens, Shigella dysenteriae, and Escherichia coli. Phosphoenolpyruvate stimulated the rate of ADPglucose synthesis catalyzed by Serratia ADPglucose pyrophosphorylase about 1.5- to 2-fold but did not affect the S0.5 values (concentration of substrate required for 50% maximal stimulation) of the substrates, alpha-glucose-1-phosphate, and adenosine 5'-triphosphate. Adenosine 5'-monophosphate (AMP), a potent inhibitor of the enteric ADPglucose pyrophosphorylase, is an effective inhibitor of the S. marcescens enzyme. ADP also inhibits but is not as effective as AMP. Activators of the enteric enzyme counteract the inhibition caused by AMP. This is in contrast to what is observed for the S. marcescens enzyme. Neither phosphoenolpyruvate, fructose-diphosphate, pyridoxal-phosphate, NADPH, 3-phosphoglycerate, fructose-6-phosphate, nor pyruvate effect the inhibition caused by AMP. The properties of the S. marcescens HY strain and Serratia liquefaciens ADPglucose pyrophosphorylase were found to be similar to the above two S. marcescens enzymes with respect to activation and inhibition. These observations provide another example where the properties of an enzyme found in the genus Serratia have been found to be different from the properties of the same enzyme present in the enteric genera Escherichia, Salmonella, Shigella, Citrobacter, and Enterobacter.