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Biomedical subjects

S Rosenberg

Publications and source records attributed to S Rosenberg.

At least 19 recordsLinked to original sources
PubMed1992

Peptoids: a modular approach to drug discovery.

Peptoids, oligomers of N-substituted glycines, are described as a motif for the generation of chemically diverse libraries of novel molecules. Ramachandran-type plots were calculated and indicate a greater diversity of conformational states available for peptoids than for peptides. The monomers incorporate t-butyl-based side-chain and 9-fluorenylmethoxy-carbonyl alpha-amine protection. The controlled oligomerization of the peptoid monomers was performed manually and robotically with in situ activation by either benzotriazol-1-yloxytris(pyrrolidino)phosphonium hexafluorophosphate or bromotris(pyrrolidino)phosphonium hexaflurophosphate. Other steps were identical to peptide synthesis using alpha-(9-fluorenylmethoxycarbonyl)amino acids. A total of 15 monomers and 10 oligomers (peptoids) are described. Preliminary data are presented on the stability of a representative oligopeptoid to enzymatic hydrolysis. Peptoid versions of peptide ligands of three biological systems (bovine pancreatic alpha-amylase, hepatitis A virus 3C proteinase, and human immunodeficiency virus transactivator-responsive element RNA) were found with affinities comparable to those of the corresponding peptides. The potential use of libraries of these compounds in receptor- or enzyme-based assays is discussed.

Alkylation↗
PubMed1992

Expression and characterization of recombinant hepatitis A virus 3C proteinase.

The 3C proteinase from the hepatitis A virus (HAV) was cloned into a multicopy expression vector in Escherichia coli under control of the tac promoter. The resulting plasmid construction produced 3C proteinase as a soluble and active enzyme constituting approximately 10% of total cellular proteins. The enzyme was purified to apparent homogeneity as judged by SDS gel electrophoresis and HPLC reversed-phase and FPLC ion-exchange chromatography. A colorimetric assay was developed, and synthetic peptides derived from the predicted cleavage sites of the HAV polyprotein were tested for proteolysis of the enzyme. The peptide representing the 2B/2C cleavage site was cleaved most efficiently with a Km and kcat of 2.1 +/- 0.5 mM and 1.8 +/- 0.1 s-1, respectively. Site-directed mutagenesis was then used to identify the cysteine at position 172 as the active site nucleophile. Finally, the purified enzyme showed the expected endoproteinase activity on the P1 precursor protein generated by in vitro transcription/translation.

3C Viral Proteases↗
PubMed1992

DSM-III-R as a taxonomy. A cluster analysis of diagnoses and symptoms.

While there have been many applications of cluster analysis in psychiatric classification research, there are no studies in which cluster analysis is used to discover the taxonomic structure implicit in the DSM-III itself. In order to do so, the symptom index in the DSM-III-R manual was summarized in a two-way matrix of disorders by symptoms and then analyzed using a hierarchical classes model and companion algorithm (HICLAS) that permits overlap among classes. A novel feature of this model is that superordinate-subordinate relationships among diagnostic and symptom classes are explicitly represented. The HICLAS analysis revealed that there are several discrete symptom classes in DSM-III-R and that many psychiatric disorders can be modeled as combinations of one or more of these classes. The disorders associated with these symptom classes tend to fit the hierarchical classes model relatively well, particularly the mood disorders and the psychotic disorders. However, disorders such as adjustment, personality, and sexual disorder fit the model poorly or not at all. The results are in line with the conjecture that the taxonomic model implicit in DSM-III-R is a hybrid of discrete symptom classes and some other structure, perhaps a dimensional one.

Algorithms↗
PubMed1992

Vestibular neurectomy in the United States--1990.

During the last decade, vestibular neurectomy has become a more frequently performed procedure to cure symptoms of inner ear vertigo while preserving hearing. In an effort to determine the results of vestibular neurectomy across the country, a questionnaire was prepared and sent to the 350 members of the American Otologic Society and the American Neurotology Society. Results of that survey indicated that 2,820 vestibular neurectomy procedures were performed by 58 surgeons. Ninety-two percent (2,590 cases) were performed through the posterior fossa approach. Of these, 1149 cases (44%) were through the retrolabyrinthine approach, 940 cases (36%) were through the retrosigmoid approach, 307 cases (12%) were through the combined retrolabyrinthine-retrosigmoid approach, and 194 cases (8%) were unspecified as to which posterior fossa approach was used. The remaining 230 cases (8%) were through the middle fossa approach. Sectioning of the vestibular nerve was done by the otologist in 58 percent of cases, by the neurosurgeon in 12 percent, and by either surgeon in 30 percent. Classic Meniere's disease, the most common indication for vestibular neurectomy, resulted in the best cure rate of 91 percent. Other inner ear diseases such as traumatic labyrinthitis and vestibular neuronitis had a lower cure rate of 74 to 81 percent. Hearing was preserved to within 20 dB of the preoperative pure-tone thresholds in 87 percent. There were no deaths, 11 cases of meningitis and 16 cases of facial paralysis, 15 of which occurred after middle fossa surgery, representing a 7 percent incidence of facial paralysis after middle fossa surgery. Eleven of the 15 cases resulted in permanent paralysis and four in temporary paralysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1991

Fermentation of a yeast producing A. niger glucose oxidase: scale-up, purification and characterization of the recombinant enzyme.

We have developed a fermentation process to produce up to 3 grams per liter of active, secreted glucose oxidase from a recombinant Saccharomyces cerevisiae. Real-time size-exclusion HPLC analysis is used to monitor enzyme production during fermentation, and purification to more than 95 percent is obtained using only filtration methods. The recombinant enzyme is stable to higher temperatures and a wider pH range than the native Aspergillus niger enzyme, and is free of contaminating amylase, cellulase and catalase.

Aspergillus niger↗
PubMed1991

Intraoperative facial nerve monitoring.

Facial nerve monitoring is one of the most exciting innovations in otologic surgery in the past decade. Intraoperative monitoring has been shown to reduce the probability of iatrogenic injury to the facial nerve during surgery. It saves surgical time and reduces the anxiety level of both patients and surgeons. There are several reasons to use facial nerve monitoring: The surgeon nerve knows when it will be needed in a particular case, the operating room personnel become familiar with the equipment, and the surgeon learns how to interpret the sounds produced by the monitor and how to correlate them with surgical manipulations around the facial nerve. Facial nerve monitoring has added another dimension of safety to otologic and neurotologic surgery and has reduced the incidence of facial weakness or paralysis in the authors' surgical practice.

Facial Nerve↗
PubMed1991

Ostiomeatal complex risk factors for sinusitis: CT evaluation.

The ostiomeatal complex was prospectively evaluated in 100 consecutive patients referred for CT scanning. The degree of nasal septal angulation, uncinate process deviation (U-VS angle), infundibular and middle meatus opacification were correlated with maxillary and ethmoid sinus opacification. Patients with more severe nasal septal deviation and more horizontally-oriented uncinate processes had a higher frequency of sinus opacification. However, the differences between patients with and without CT evidence of sinus disease were very small (1.7 degrees to 3.4 degrees). Infundibular opacification most accurately predicted maxillary (76%), and middle meatus opacification most accurately predicted ethmoid sinus disease (78%). There is a small but statistically significant decrease in U-VS angulation and increase in nasal septal deviation in patients with sinusitis. However, the value of performing these measurements is limited. The evaluation of the degree of nasal septal deviation and uncinate process angulation will be most useful in preoperative planning.

Causality↗
PubMed1991

Bilateral Menière's disease in surgical versus nonsurgical patients.

In patients with Menière's disease, the possibility of developing Menière's disease in the uninvolved ear is of great concern. In this study, the incidence of bilateral Menière's disease (BMD) in medically treated patients was found to be 17 percent, while in surgically treated patients it was significantly lower, 5.9 percent (p less than 0.01). The incidence of BMD for each surgical procedure was as follows: 9 percent after endolymphatic subarachnoid shunt (n = 101), 7 percent after cochleovestibular neurectomy (n = 100), 6 percent after cochleosacculotomy (n = 18), and 0 percent after vestibular nerve section (n = 73). The average duration of disease prior to surgery was 6.3 years. Seventy-two percent of the patients who developed BMD did so within 5 years of the onset of their symptoms. Proper patient selection is the most likely explanation for the low incidence of BMD among surgically treated patients.

Adolescent↗
PubMed1991

Once daily triamcinolone acetonide nasal spray is effective for the treatment of perennial allergic rhinitis.

A randomized, double-blind, placebo-controlled, parallel group study was conducted in 11 centers to evaluate the safety and efficacy of a once-a-day regimen of 110 micrograms, 220 micrograms; and 440 micrograms of triamcinolone acetonide intranasal aerosol versus placebo in relieving the symptoms of rhinitis in 305 adult and older pediatric patients with perennial allergic rhinitis. Nasal stuffiness, nasal discharge, sneezing, nasal itching and the nasal index (the sum of the mean scores of the first three symptoms) averaged over the first 6 weeks and second 6 weeks of the study were significantly reduced in patients who received the 220 micrograms/day and the 440 micrograms/day dosages. The 110 micrograms/day group had a reduction in these nasal symptoms, but only the sneezing and nasal index were significantly (P less than .05) better than placebo. During the last 6 weeks of the study, patients were allowed to take oral back-up medication for their nasal symptoms; all three groups receiving triamcinolone nasal aerosol took less back-up medication than did the placebo group. There were no significant adverse effects or laboratory abnormalities noted during this study. Intranasal triamcinolone acetonide 220 micrograms and 440 micrograms, used once-a-day for 12 weeks is clinically and statistically superior to placebo for the treatment of perennial allergic rhinitis.

Administration, Intranasal↗
PubMed1990

Enzymatic coupling of cholesterol intermediates to a mating pheromone precursor and to the ras protein.

The post-translational processing of the yeast a-mating pheromone precursor, Ras proteins, nuclear lamins, and some subunits of trimeric G proteins requires a set of complex modifications at their carboxyl termini. This processing includes three steps: prenylation of a cysteine residue, proteolytic processing, and carboxymethylation. In the yeast Saccharomyces cerevisiae, the product of the DPR1-RAM1 gene participates in this type of processing. Through the use of an in vitro assay with peptide substrates modeled after a presumptive a-mating pheromone precursor, it was discovered that mutations in DPR1-RAM1 cause a defect in the prenylation reaction. It was further shown that DPR1-RAM1 encodes an essential and limiting component of a protein prenyltransferase. These studies also implied a fixed order of the three processing steps shared by prenylated proteins: prenylation, proteolysis, then carboxymethylation. Because the yeast protein prenyltransferase could also prenylate human H-ras p21 precursor, the human DPR1-RAM1 analogue may be a useful target for anticancer chemotherapy.

Amino Acid Sequence↗
PubMed1990

Glucose oxidase from Aspergillus niger. Cloning, gene sequence, secretion from Saccharomyces cerevisiae and kinetic analysis of a yeast-derived enzyme.

The gene for Aspergillus niger glucose oxidase (EC 1.1.3.4) has been cloned from both cDNA and genomic libraries using oligonucleotide probes derived from the amino acid sequences of peptide fragments of the enzyme. The mature enzyme consists of 583 amino acids and is preceded by a 22-amino acid presequence. No intervening sequences are found within the coding region. The enzyme contains 3 cysteine residues and 8 potential sites for N-linked glycosylation. The protein shows 26% identity with alcohol oxidase of Hansenuela polymorpha, and the N terminus has a sequence homologous with the AMP-binding region of other flavoenzymes such as p-hydroxybenzoate hydroxylase and glutathione reductase. Recombinant yeast expression plasmids have been constructed containing a hybrid yeast alcohol dehydrogenase II-glyceraldehyde-3-phosphate dehydrogenase promoter, either the yeast alpha-factor pheromone leader or the glucose oxidase presequence, and the mature glucose oxidase coding sequence. When transformed into yeast, these plasmids direct the synthesis and secretion of between 75 and 400 micrograms/ml of active glucose oxidase. Analysis of the yeast-derived enzymes shows that they are of comparable specific activity and have more extensive N-linked glycosylation than the A. niger protein.

Amino Acid Sequence↗
PubMed1990

Different mechanisms of increased proteolysis in atrophy induced by denervation or unweighting of rat soleus muscle.

Mechanisms of accelerated proteolysis were compared in denervated and unweighted (by tail-cast suspension) soleus muscles. In vitro and in vivo proteolysis were more rapid and lysosomal latency was lower in denervated than in unweighted muscle. In vitro, lysosomotropic agents (eg, chloroquine, methylamine) did not lessen the increase in proteolysis caused by unweighting, but abolished the difference in proteolysis between denervated and unweighted muscle. Leucine methylester, an indicator of lysosome fragility, lowered latency more in denervated than in unweighted muscle. 3-Methyladenine, which inhibits phagosome formation, increased latency similarly in all muscles tested. Mersalyl, a thiol protease inhibitor, and 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8), which antagonizes sarcoplasmic reticulum release of Ca2+, reduced accelerated proteolysis caused by unweighting without diminishing the faster proteolysis due to denervation. Calcium ionophore (A23187) increased proteolysis more so in unweighted than control muscles whether or not Ca2+ was present. Different mechanisms of accelerated proteolysis were studied further by treating muscles in vivo for 24 hours with chloroquine or mersalyl. Chloroquine diminished atrophy of the denervated but not the unweighted muscle, whereas mersalyl prevented atrophy of the unweighted but not of the denervated muscle, both by inhibiting in vivo proteolysis. These results suggest that (1) atrophy of denervated, but not of unweighted, soleus muscle involves increased lysosomal proteolysis, possibly caused by greater permeability of the lysosome, and (2) cytosolic proteolysis is important in unweighting atrophy, involving some role of Ca2(+)-dependent proteolysis and/or thiol proteases.

Animals↗