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Biomedical subjects

S Avital

Publications and source records attributed to S Avital.

34 records · Page 2Linked to original sources
PubMed1997

[Diverticular disease of the appendix].

The incidence of appendiceal diverticulosis in pathologic specimens is 0.004-2.1%. Diverticular disease of the appendix is classified as congenital (true) or acquired (false). The clinical presentation differs from that of acute appendicitis. The average age is older, the pain is often intermittent, and while localized in the right lower abdominal quadrant, is of longer duration. No further treatment besides appendectomy is needed. Since a high rate of perforations, peritonitis and lower gastrointestinal bleeding have been reported as complications, it is recommended that in those with an incidental finding of diverticula of the appendix during surgery, that appendectomy be performed. It is not recommended to perform prophylactic appendectomy when diverticula of the appendix are found on barium enema.

Appendectomy↗
PubMed1997

Survival of colorectal carcinoma in the elderly. A prospective study of colorectal carcinoma and a five-year follow-up.

PURPOSE: Colorectal carcinoma in elderly patients has become a more common problem in the last decade. There are some physicians who tend to offer a less definitive treatment for these patients because of their chronologic age. The purpose of this study was to evaluate the long-term survival of elderly patients (> 70) who underwent surgery for colorectal carcinoma in comparison with a younger group of patients with the same disease. METHODS: Long-term survival of patients with colorectal carcinoma who underwent surgery was prospectively evaluated. Long-term survival was compared between an elderly group of patients (age, > 70) and a younger group of patients. RESULTS: There was no significant difference in the five-year survival between the two age groups. Patients' survival was influenced by stage of the disease and type of operation (emergency vs. elective). CONCLUSIONS: Treatment decisions in elderly patients with colorectal carcinoma should not be influenced by the chronologic age of the patient.

Aged↗
PubMed1997

[Penetrating gluteal injuries management--the need for management protocols].

Gunshot wounds are the most common cause of penetrating injuries in the gluteal region (PIGR), while only 17.5% result from stabbing. Complications and even death have been described as resulting from stab injury in this area, which is thus a hazard that demands an algorithm for proper management. Recently, DiGiacomo et al. recommended that transpelvic bullet trajectory warrants surgery. Mercer et al., in a study of 81 patients with PIGR, recommended an algorithm based on anatomical gluteal zones and concluded that angiography is not mandatory in such injuries. We describe 9 cases of PIGR, 4 of which were from stab wound and 1 a gunshot wound, which bled from rami of the gluteal arteries. In 2 there was no apparent bleeding, and they were hemodynamically stable. Thus in this type of injury significant damage may be obscured. Our results suggest that angiography is important in the evaluation of such injuries an should be part of the protocol for management of PIGR.

Algorithms↗
PubMed1995

[Angioplasty for vein grafts and native coronary arteries after previous coronary artery bypass grafting].

219 patients after previous coronary artery bypass grafting (CABG) underwent coronary artery or vein graft angioplasty in 1984-1991. 452 stenotic lesions out of 498 were successfully dilated in 337 procedures (90.7%). For arterial lesions the initial success rate had been 89.2% (321/360) and for vein graft lesions 94.9% (131/138). For repeated angioplasty the success rate was the same. Major complications included 3 deaths (0.9%). 15 myocardial infarctions (5.3%) and 1 emergency CABG. Factors that had reduced the success rate were lesions at the proximal anastomosis, total occlusions, and complex (type C) lesions. Time since grafting did not affect success rate of the second procedure. Restenosis after successful angioplasty was 37.3% (34/91) for arterial lesions and 56.8% (25/44) for graft lesions, after a mean time of 11.2 +/- 2.7 months. Restenosis was more common in type C lesions and old vein grafts. There was considerable improvement in treadmill exercise time of patients after the angioplasty (5.92 vs 7.31 minutes) and in double product. During a follow up of about 3 years, 7.6% (15/196) died of cardiac events, 5.2% (10/189) had myocardial infarctions, 10.5% (20/189) were reoperated and 31.0% (68/219) needed at least 1 repeat angioplasty. Long term followup was better after angioplasty of native arteries than of grafts. After angioplasty of vein grafts, there were more cardiac related deaths, more MIs and more reoperations than after angioplasty of native arteries: 11.5% vs 3.5%, 9.6% vs 2.8%, 21% vs 4.9%, respectively, than in the arterial group. Considering the high mortality and morbidity of reoperation, balloon angioplasty in selected patients may be the preferred strategy. Clinical and angiographic results are better after re-angioplasty of native arteries than vein grafts.

Angioplasty, Balloon, Coronary↗
PubMed1991

Reactivation of the chloroplast CF1-ATPase beta subunit by trace amounts of the CF1 alpha subunit suggests a chaperonin-like activity for CF1 alpha.

Incubation of tobacco and lettuce thylakoids with 2 M LiCl in the presence of MgATP removes the beta subunit from their CF1-ATPase (CF1 beta) together with varying amounts of the CF1 alpha subunit (CF1 alpha). These 2 M LiCl extracts, as with the one obtained from spinach thylakoids (Avital, S., and Gromet-Elhanan, Z. (1991) J. Biol. Chem. 266, 7067-7072), could form active hybrid ATPases when reconstituted into inactive beta-less Rhodospirillum rubrum chromatophores. Pure CF1 beta fractions that have been isolated from these extracts could not form such active hybrids by themselves, but could do so when supplemented with trace amounts (less than 5%) of CF1 alpha. A mitochondrial F1-ATPase alpha subunit was recently reported to be a heat-shock protein, having two amino acid sequences that show a highly conserved identity with sequences found in molecular chaperones (Luis, A. M., Alconada, A., and Cuezva, J. M. (1990) J. Biol. Chem. 265, 7713-7716). These sequences are also conserved in CF1 alpha isolated from various plants, but not in F1 beta subunits. The above described reactivation of CF1 beta by trace amounts of CF1 alpha could thus be due to a chaperonin-like function of CF1 alpha, which involves the correct, active folding of isolated pure CF1 beta.

Bacterial Proteins↗
PubMed1991

Extraction and purification of the beta subunit and an active alpha beta-core complex from the spinach chloroplast CFoF1-ATP synthase.

Incubation of Rhodospirillum rubrum chromatophores with 2 M LiCl in the presence of MgATP has been shown to remove their F1 beta subunit leaving inactive but fully reconstitutable beta-less chromatophores (Gromet-Elhanan, Z., and Khanashvili, D., (1986) Methods Enzymol, 126, 528-538). A similar treatment of thoroughly washed spinach thylakoids has now been shown to release the CF1 beta subunit (CF1 beta) together with a complex containing equal amounts of CF1 alpha and CF1 beta (CF1 (alpha beta]. The purified CF1 (alpha beta) complex can reconstitute an active membrane-bound hybrid F0F1-ATPase with beta-less R. rubrum chromatophores and also catalyzes a low but very reproducible soluble MgATPase. Purified CF1 beta shows none of these activities although it can bind as efficiently as CF1 (alpha beta) to the beta-less chromatophores. By subjecting the crude spinach 2 m LiCl extract to dissociating conditions an enriched CF1 beta preparation is released. It contains traces of CF1 alpha and CF1 delta, is able to reconstitute an active hybrid F0F1-ATPase but, as the pure CF1 beta shows no soluble ATPase activity. These results indicate that trace amounts of CF1 alpha are enough for endowing CF1 beta with a reconstitutive capacity, but for exhibition of a significant soluble ATPase activity equivalent amounts of CF1 alpha and beta are required. The CF 1 (alpha beta) complex isolated and purified in this report thus represents the minimal catalytic core of the CF1-ATPase.

Blotting, Western↗
PubMed1985

Long range RNA-RNA interactions in the 30 S ribosomal subunit of E. coli.

We have attempted to identify long-range interactions in the tertiary structure of RNA in the E. coli 30 S ribosome. Native subunits were cleaved with ribonuclease and separated into nucleoprotein fragments which were deproteinized and fractionated into multi-oligonucleotide complexes under conditions intended to preserve RNA-RNA interactions. The final products were denatured by urea and heat and their constituent oligonucleotides resolved and sequenced. Many complexes contained complementary sequences known to be bound together in the RNA secondary structure, attesting to the validity of the technique. Other co-migrating oligonucleotides, not joined in the secondary structure, contained mutually complementary sequences in locations that allow base-pairing interaction without disrupting pre-existing secondary structure. In seven instances the complementary relationship was found to have been preserved during phylogenetic diversification.

Base Sequence↗
PubMed1982

A ribonucleoprotein fragment of the 30 S ribosome of E. coli containing two contiguous domains of the 16 S RNA.

Ribonucleoprotein fragments of the 30 S ribosome of E. coli have been prepared by limited ribonuclease digestion and mild heating of the ribosome in a constant ionic environment. One such fragment has been described previously. A second electrophoretically homogeneous fragment has now been isolated and its RNA and protein moieties have been characterized. It contains the 5' half of the 16 S RNA, encompassing domains I and II except for the extreme 5' terminus and several small gaps. Seven proteins are present: S4, S5, S6, S8, S12, S15 and S20. The RNA binding sites of five of these proteins are known, and all are RNA sequences that are present in the fragment. Published neutron scattering and immuno-electron microscopic data indicate that six of the proteins are clustered together in a cross sectional slice through the center of the subunit. After deproteinization, the RNA moiety gives two bands in gel electrophoresis, one containing domains I and II and the other, essentially only domain II. The former, although larger, migrates faster in gel electrophoresis, indicating that RNA domains I and II interact with each other in such a way as to become more compact than domain II by itself.

Base Sequence↗
PubMed1982

A ribonucleoprotein fragment of the 30 S ribosome of E. coli: evidence for long range RNA-RNA interactions.

A stable homogeneous ribonucleoprotein fragment of the 30 S ribosomal subunit of E. coli has been prepared by mild nuclease digestion and heating in a constant ionic environment. The fragment contains about half of the 16 S ribosomal RNa and six proteins: S4, S7, S9, S13, S16 and S19. The RNA moiety contains the reported binding sites of all six proteins. After deproteinization, 80% of the RNA migrated as two major electrophoretic bands, which were isolated and sequenced. Each band contained sequences from the 5' and 3' thirds of the 16 S RNA but none from the central third. That these two noncontiguous RNA domains migrated together electrophoretically in Mg++-containing gels after deproteinization constitutes direct evidence that the 16 S RNA is folded in the intact ribosome so as to bring the two domains close together and that there are RNA-RNA interactions between them in the presence of Mg++.

Base Sequence↗
PubMed1979

Binding of magnesium ions and ethidium bromide: comparison of ribosomes and free ribosomal RNA.

Comparative studies of free ribosomal RNA and ribosomes were made with two probes, Mg++ ions and ethidium bromide, which interact with RNA in different ways. Mg++. E. coli 16 S rRNA and 30 S ribosomes were equilibrated with four different buffers. Equilibration required several days at 4 degrees and several hours at 37 degrees. In all buffers ribosomes bound more Mg than free rRNA, the difference sometimes reaching 20--30%. Ribosomes were more resistant than free rRNA to heat denaturation and their denaturation was more highly cooperative. Ribosomes that bound more Mg++ had higher denaturation temperatures. Ethidium bromide. Fluorescence enhancement studies of ethidium intercalation showed the free 16 S rRNA to have 50--80 binding sites per molecule. A large fraction of these sites were present and accessible in the ribosome, but their ethidium-binding constants were reduced by an order of magnitude. In addition, free rRNA contained a small number of very strong binding sites that were virtually absent in the ribosomes.

Chemical Phenomena↗
PubMed1978

A large nucleoprotein fragment of the 50-S ribosomal subunit of Escherichia coli.

A large nucleoprotein fragment was isolated from a nuclease digest of Escherichia coli 50-S ribosomes and purified to gel electrophoretic homogeneity. Conditions were employed under which the fragmentation pattern was reproducible and the various fragment fractions were stable and maintained their sedimentation and electrophoretic properties throughout the several preparative and analytical procedures used. Fractions that appeared homogeneous in sucrose gradient centrifugation were found to be heterogeneous by gel electrophoresis. The large fragment was purified to homogeneity by preparative gel electrophoresis. It contained 21 proteins, the 5-S RNA, and two large oligonucleotides which together total about two thirds the molecular weight of the 23-S RNA. Because it can be prepared reproducibly in large quantities and because of its size and stability, the fragment appears suitable for functional and structural studies and as the starting material for further fractionation. An important contributing factor to the observed stability and reproducibility was the maintenance of an unchanging ionic environment. A single buffer was employed throughout all the procedures, and the fragments produced by nuclease digestion were dissociated from each other by heat rather than by changing the medium.

Enzymes, Immobilized↗