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Biomedical subjects

S Schlesinger

Publications and source records attributed to S Schlesinger.

At least 73 records · Page 4Linked to original sources
PubMed1985

Studies of defective interfering RNAs of Sindbis virus with and without tRNAAsp sequences at their 5' termini.

Three of six independently derived defective interfering (DI) particles of Sindbis virus generated by high-multiplicity passaging in cultured cells have tRNAAsp sequences at the 5' terminus of their RNAs (Monroe and Schlesinger, J. Virol. 49:865-872, 1984). In the present work, we found that the 5'-terminal sequences of the three tRNAAsp-negative DI RNAs were all derived from viral genomic RNA. One DI RNA sample had the same 5'-terminal sequence as the standard genome. The DI RNAs from another DI particle preparation were heterogeneous at the 5' terminus, with the sequence being either that of the standard 5' end or rearrangements of regions near the 5' end. The sequence of the 5' terminus of the third DI RNA sample consisted of the 5' terminus of the subgenomic 26S mRNA with a deletion from nucleotides 24 to 67 of the 26S RNA sequence. These data showed that the 5'-terminal nucleotides can undergo extensive variations and that the RNA is still replicated by virus-specific enzymes. DI RNAs of Sindbis virus evolve from larger to smaller species. In the two cases in which we followed the evolution of DI RNAs, the appearance of tRNAAsp-positive molecules occurred at the same time as did the emergence of the smaller species of DI RNAs. In pairwise competition experiments, one of the tRNAAsp-positive DI RNAs proved to be the most effective DI RNA, but under identical conditions, a second tRNAAsp-positive DI RNA was unable to compete with the tRNAAsp-negative DIs. Therefore, the tRNAAsp sequence at the 5' terminus of a Sindbis DI RNA is not the primary factor in determining which DI RNA becomes the predominant species in a population of DI RNA molecules.

Aspartic Acid↗
PubMed1985

Diminished type I collagen synthesis and reduced alpha 1(I) collagen messenger RNA in cultured fibroblasts from patients with dominantly inherited (type I) osteogenesis imperfecta.

Type I osteogenesis imperfecta (OI) is characterized clinically by a moderate fracture frequency with minimal bone deformity and dominant inheritance. Previous studies of the collagenous proteins synthesized by dermal fibroblasts obtained from unrelated patients with this form of OI suggested that the biochemical basis of the disease was reduced production of type I collagen. This study was designed to determine if this biochemical finding segregated with the disease within an individual family. Dermal fibroblast strains were established from three generations of a family having the typical features of type I OI. Analysis of the collagenous proteins made in culture revealed an elevated alpha 1(III) to alpha 1(I) collagen type ratio and an elevated alpha 1(I) to alpha 2(I) collagen chain ratio. The procollagen that accumulated in the medium reflected these ratios to the same degree. Total collagen synthesis was significantly reduced in affected family members. Therefore, the most striking abnormality in affected members was a 50-75% reduction of type I collagen production. Furthermore, the ratio of the alpha 1(I)/alpha 2(I) collagen messenger RNA (mRNA), measured by dot hybridization, was one-half of the value of uninvolved family members and unrelated controls. Since the reduction in the production of type I collagen and the altered alpha 1(I)/alpha 2(I) mRNA ratio clearly segregated with affected individuals within this family, these biochemical measurements may be a useful genetic marker for type I OI.

Adult↗
PubMed1984

Hereditary adult-onset leukodystrophy simulating chronic progressive multiple sclerosis.

We studied a large kindred with a chronic progressive neurologic disorder affecting at least 10 men and 11 women in four generations in a pattern compatible with autosomal dominant inheritance. In 20 of the affected subjects, evaluated before the availability of computerized tomography and without regard to family history, the diagnosis was multiple sclerosis. Symptoms of the neurologic disorder begin in the fourth and fifth decades and include cerebellar, pyramidal, and autonomic abnormalities. The autonomic symptoms, which involve bowel and bladder regulation and orthostatic hypotension, may be the earliest changes but are frequently disregarded. Survival for 20 years after onset is common. The CT scan is striking and shows a symmetrical decrease in white-matter density, beginning in the frontal lobes but extending to all of the centrum ovale and the cerebellar white matter. Limited pathological observation reveals gross white-matter degeneration with microscopic vacuolation, preservation of U fibers and cortical structures, and no inflammatory changes or reactive gliosis. Because of its hereditary basis, the disorder should be susceptible to genetic definition and ultimately to treatment or prevention.

Adult↗
PubMed1984

The formation of vesicular stomatitis virus (San Juan strain) becomes temperature-sensitive when glucose residues are retained on the oligosaccharides of the glycoprotein.

We have studied the effects of inhibiting the initial steps in processing of asparagine-linked oligosaccharides on the formation of vesicular stomatitis virus (VSV). Our data show that conditions which prevent the removal of glucose can block the growth of this virus. Our conclusion that inhibition of VSV synthesis is due specifically to an effect on the ability of the virus glycoprotein, G, to mature to a correct functional conformation is based on the following observations: (i) two drugs, deoxynojirimycin and castanospermine , both of which selectively inhibit the processing glucosidases, affected virus growth; (ii) only one of the two strains (San Juan and Orsay ) of VSV tested was affected and that strain, VSV(San Juan), is known to have a G protein highly sensitive to alterations in oligosaccharide structure; (iii) the effect was to make the formation of VSV(San Juan) temperature-sensitive, a result previously observed with alterations in the oligosaccharides on G protein; (iv) a cell variant missing glucosidase II activity also became temperature-sensitive in its ability to produce VSV(San Juan) but not VSV( Orsay ). Although inhibition of glucosidase activity by 1- deoxynojirimycin caused a 10-fold drop in virion formation, transport of G protein to the plasma membrane was not altered. The growth of VSV(San Juan) at 40 degrees C was not affected when subsequent steps in the processing pathway were blocked. These data indicate that by the time the glucose residues are removed G has attained a stable conformation.

1-Deoxynojirimycin↗
PubMed1984

Common and distinct regions of defective-interfering RNAs of Sindbis virus.

Defective-interfering (DI) particles are helper-dependent deletion mutants which interfere specifically with the replication of the homologous standard virus. Serial passaging of alphaviruses in cultured cells leads to the accumulation of DI particles whose genomic RNAs are heterogeneous in size and sequence composition. In an effort to examine the sequence organization of an individual DI RNA species generated from Sindbis virus, we isolated and sequenced a representative cDNA clone derived from a Sindbis DI RNA population. Our data showed that: (i) the 3' end of the DI RNA template was identical to the 50 nucleotides at the 3' end of the standard RNA; (ii) the majority (75%) of the DI RNA template was derived from the 1,200 5'-terminal nucleotides of the standard RNA and included repeats of these sequences; and (iii) the 5' end of the DI RNA template was not derived from the standard RNA, but is nearly identical to a cellular tRNAAsp (S. S. Monroe and S. Schlesinger, Proc. Natl. Acad. Sci. U.S.A. 80:3279-3283, 1983). We have also utilized restriction fragments from cloned DNAs to probe by blot hybridization for the presence of conserved sequences in several independently derived DI RNA populations. These studies indicated that: (i) a 51-nucleotide conserved sequence located close to the 5' end of several alphavirus RNAs was most likely retained in the DI RNAs; (ii) the junction region containing the 5' end of the subgenomic 26S mRNA was deleted from the DI RNAs; and (iii) the presence of tRNAAsp sequences was a common occurrence in Sindbis virus DI RNAs derived by passaging in chicken embryo fibroblasts.

Base Sequence↗
PubMed1983

Physical properties of a soluble form of the glycoprotein of vesicular stomatitis virus at neutral and acidic pH.

We have analyzed a soluble form of the glycoprotein (G) obtained from vesicular stomatitis virus (VSV) by treatment of intact virions with cathepsin D. This form lacks the carboxy-terminal and membrane-spanning domains and thus is analogous to the previously described secreted form of G, Gs. The molecular weight of the cathepsin D produced G, G(Cath D), measured by sedimentation equilibrium in the analytical ultracentrifuge is 57 600, indicating that it is a monomer. Intact G protein extracted from virions by octyl beta-D-glucoside also is monomeric, based on sedimentation equilibrium analysis. These results suggest that G may be monomeric in virions. The Stokes radii (Rs) of the two forms of G were obtained from their migration in nondenaturing polyacrylamide gradient gels. The Rs of G(Cath D) in the absence of nonionic detergent was 37 A; in the presence of nonionic detergent, it increased to 55 A. The Rs of detergent-extracted intact G was 63 A in nonionic detergent. From the molecular weight and Rs of G(Cath D), we calculated a sedimentation coefficient of 3.8 S; the value determined by centrifugation in a sucrose gradient was 3.7 S. Viruses such as VSV fuse with cell membranes at low pH [White, J., Matlin, K., & Helenius, A. (1981) J. Cell Biol. 89, 674-679]. We have used the fluorescent probe cis,trans,trans,cis-9,11,13,15-parinaric acid (cis-PnA) to detect a reversible conformational change in G(Cath D) when the protein was exposed to an acidic environment close to pH 5. cis-PnA binds to hydrophobic regions of protein, causing a quenching of the intrinsic tryptophan fluorescence and an increase in the fluorescence of the probe.

Cathepsin D↗
PubMed1983

The iliac bone or osteocutaneous transplant pedicled to the deep circumflex iliac artery. II. Clinical application.

10 patients received a bone or osteocutaneous transplant pedicled to the deep circumflex iliac artery (DCIA) after in-continuity resection of the mandible. 9 grafts healed primarily and were stable after a period of time corresponding to that needed in fractured bones. No infection or resorption occurred. In one case, varicosity made the vessel preparation impossible. Indications, reliability and pitfalls of this method are outlined and discussed in this paper.

Adult↗
PubMed1983

RNAs from two independently isolated defective interfering particles of Sindbis virus contain a cellular tRNA sequence at their 5' ends.

Defective interfering (DI) particles are deletion mutants that interfere specifically with the replication of homologous standard virus. We have determined the 5'-terminal nucleotide sequences of two DI RNA populations by the following methods: (i) cloning of the cDNA from one of the DI RNA populations and sequencing a representative clone, and (ii) using both DI RNA populations as templates for preparing primer-directed cDNA transcripts and sequencing these transcripts. The 5' terminal sequences of the two DI RNA populations were not derived from standard Sindbis viral RNA but were almost identical to those of a cellular tRNAAsp.

Animals↗
PubMed1983

Evolution of virus and defective-interfering RNAs in BHK cells persistently infected with Sindbis virus.

We analyzed a BHK cell line persistently infected with Sindbis virus for 16 months and a virus (Sin-16) cloned from these cells. Sin-16 virus was resistant to the defective interfering particles present in the original infection. We found that (i) cells infected with Sin-16 were impaired in the processing of a viral precursor glycoprotein, (ii) high-multiplicity passaging of Sin-16 gave rise to a variant that was able to generate and be inhibited by defective-interfering particles to which the original Sin-16 virus was resistant, and (iii) the persistently infected culture contained a heterogeneous mixture of defective Sindbis virus RNAs which were not packaged into extracellular particles. To determine whether these intracellular RNAs could interfere with the replication of Sin-16, we analyzed cells that were cloned from the persistently infected culture. One clone (A3) synthesized a single defective viral RNA which was lost with continued passaging in culture. Infection of A3 cells with Sin-16 showed that the presence of the defective RNA greatly enhanced cell survival and led to enrichment of this RNA. In contrast, cured cells were highly susceptible to killing by Sin-16, and survivors did not synthesize this RNA. Thus, A3 cells were not genetically altered in their response to Sin-16, but were protected from the cytopathic effects of infection by an RNA with the characteristics of a defective-interfering RNA.

Animals↗
PubMed1983

Sclerosteosis: neurogenetic and pathophysiologic analysis of an American kinship.

We studied an American kinship with sclerosteosis, an autosomal-recessive disorder of bone remodeling and bone overgrowth of the calvaria, skull base, and tubular bones. Unlike osteopetrosis, which is attributed to abnormal immune and osteoclast function as well as bone resorption, sclerosteosis appears to be primarily a disorder of osteoblast (bone formation) hyperactivity. Related to cranial vascular and neural foraminal narrowing and reduced intracranial volume, affected patients with sclerosteosis demonstrate frequent seventh nerve palsy, progressive optic and cranial neuropathies, mixed hearing loss, brainstem compression, intracranial hypertension with increased elastance, and sudden, premature death. Management should involve early childhood identification of homozygotes, monitoring and aggressive treatment of intracranial hypertension, and extensive bone removal from skull, posterior fossa, and cervical spine.

Adult↗
PubMed1983

Osteogenesis imperfecta and Paget's disease of bone. Biochemical and morphologic studies.

Osteogenesis imperfecta (OI) and Paget's disease of bone occurred in a patient whose brother has Paget's disease. Several other relatives have the dominant variety of OI. The familial occurrence of the two diseases is presumably due to chance and, to our knowledge, has not been previously reported. Examination of iliac crest bone biopsy specimens showed mild changes of both diseases in the proband. Electron microscopy of the bone collagen demonstrated type I collagen fibers, which are reduced in number, decreased in diameter, and stellate rather than smooth in outline. Three populations of collagen fibers were observed in the bone. The synthesis of type I collagen by dermal fibroblasts was diminished in the proband and affected relatives, but it was normal in the unaffected relatives. Since collagen fibers with a stellate outline have not been observed in OI bone, an intriguing question is the effect to the putative Paget agent (? viral) on collagen synthesis in OI.

Adult↗
PubMed1982

Physical properties of the glycoprotein of vesicular stomatitis virus measured by intrinsic fluorescence and aggregation.

We have studied the denaturation and renaturation of the purified glycoprotein (G) of vesicular stomatitis virus by using intrinsic fluorescence spectroscopy and an aggregation assay. Our studies were carried out with G containing two complex oligosaccharide chains, with the asialo form of the protein, and for some experiments with G containing altered oligosaccharide structures. Fluorescence quenching using acrylamide showed no differences between the native and denatured states of G due to sialic acid content. Denaturation by guanidinium chloride (GdmCl) at 25 degrees C was reversible for the major transition region. The data analyzed by a two-state denaturation model gave a free energy of unfolding in the absence of denaturant of approximately 1.4 kcal/mol. For renaturation, two types of dialysis protocols were employed. The first (direct dialysis) involved dialysis against standard buffer [140 mM NaCl, 10 mM sodium phosphate, 1 mM disodium ethylenediaminetetraacetate, and 0.2% (w/v) poly(oxyethylene) 10-tridecyl ether, pH 7.4]. Recovery of the native emission maximum did not occur for any of the G proteins by using this procedure. The second (annealing dialysis) involved slow removal of GdmCl against decreasing concentrations of GdmCl in standard buffer over a period of 2-3 days. Only in this case was recovery of the native emission maximum and fluorescence intensity obtained. For those G proteins in which the oligosaccharide chains were decreased in size, this protocol led to extensive aggregation.

Glycoproteins↗
PubMed1982

Sequence analysis of cDNA's derived from the RNA of Sindbis virions and of defective interfering particles.

Sindbis virus generates defective interfering (DI) particles during serial high-multiplicity passage in cultured cells. These DI particles inhibit the replication of infectious virus and can be an important factor in the establishment and maintenance of persistent infection in BHK cells. In an effort to understand how these DI particles are generated and how they interfere with the replication of standard virus, we performed a partial sequence analysis of the RNA obtained from two independently isolated populations of DI particles and from two Sindbis virus variants and compared these with the RNA of the parental wild-type virus. The 3'-terminal regions of the RNAs were sequenced by the dideoxy chain terminating method. Internal regions of the RNA were examined by restriction endonuclease digestion of cDNA's made to the various RNAs and by direct chemical sequencing of 5' end-labeled restriction fragments from cDNA made to the DI RNAs. One of the variant viruses examined was originally derived from cells persistently infected with Sindbis virus for 16 months and is resistant to interference by the DI strains used. In the 3'-terminal region of the RNA from this variant, only two base changes were found; one of these occurs in the 20-nucleotide 3'-terminal sequence which is highly conserved among alphaviruses. The DI RNA sequences were found to have been produced not by a single deletional event, but by multiple deletion steps combined with sequence rearrangements; all sequences examined are derived from the plus strand of Sindbis virion RNA. Both DI RNAs had at least 50 nucleotides of wild-type sequence conserved at the 3' terminus; in addition, they both contained conserved and perhaps amplified sequences derived from the non-26S region of the genome which may be of importance in their replication and interference ability.

Base Sequence↗
PubMed1981

The effect of oligosaccharide chains of different sizes on the maturation and physical properties of the G protein of vesicular stomatitis virus.

The envelope glycoprotein, G, of vesicular stomatitis virus (VSV) is initially glycosylated by the en bloc transfer of Glc3Man9GlcNAc2 oligosaccharides to 2 specific asparagine residues in the nascent polypeptide chain. We carried out in vivo and in vitro studies to determine whether the size of the oligosaccharide chains on two related but different G proteins can affect their ability to fold correctly. For the in vivo studies we used a mutant lymphoma cell line, Thy-1-e, which transfers the truncated oligosaccharide, Glc3Man5GlcNAc2, to nascent polypeptides. The growth of VSV in these cells was temperature-sensitive compared to that in parental Thy-1+ cells, and VSV (San Juan) was more affected than VSV (Orsay). These results are congruous with our previous observation that in the absence of glycosylation virus assembly is temperature-sensitive and VSV (San Juan) is inhibited more than VSV (Orsay). To examine the effect of oligosaccharide size on the properties of the G protein in vitro we treated G proteins containing either Man8GlcNAc2 or Man5GlcNAc2 oligosaccharide chains with guanidine hydrochloride and measured their ability to refold using an in vitro aggregation assay. The San Juan G protein with Man5GlcNAc2 oligosaccharides aggregated at 40 degrees C but not at 30 degrees C. The Orsay G protein with Man5GlcNAc2 oligosaccharides and both proteins containing Man8GlcNAc2 oligosaccharides did not aggregate at either temperature. We conclude that the size of the oligosaccharides present on the folding G protein can be crucial in attaining a proper conformation, and the extent of their effect depends on the primary structure of the polypeptide.

Animals↗