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Biomedical subjects

S Rabinovich

Publications and source records attributed to S Rabinovich.

At least 19 recordsLinked to original sources
PubMed1998

Intravascular ultrasound-guided optimized stent deployment. Immediate and 6 months clinical and angiographic results from the Multicenter Ultrasound Stenting in Coronaries Study (MUSIC Study)

OBJECTIVES: A study was set up to validate the safety and feasibility of intravascular ultrasound-guided stenting without subsequent anticoagulation, and its impact on the 6 months restenosis rate. METHODS: The study was designed to be multicentred, prospective, and observational. RESULTS: One hundred and sixty-one patients with stable angina and a de novo coronary artery lesion were enrolled. In four patients, the implantation of a Palmaz-Schatz (with spiral bridge) stent had failed. One of these four patients died 3 days following bypass surgery. In two other patients, intravascular ultrasound assessment was not performed. One hundred and twenty-five of the remaining 155 patients (81%) were treated with aspirin (100 mg x day(-1)), because all three criteria for optimized stent expansion were met. Twenty-two of the remaining 38 patients (25%), in whom at least one criterion was not met were treated with aspirin and acenocoumarol (3 months, INR 2.5-3.5), while 16 patients only received aspirin. Stent thrombosis was documented in two patients (1.3%) for which repeat angioplasty was performed. During the hospital stay, there were no deaths or Q-wave myocardial infarctions. Five patients (3.2%) sustained a non-Q-wave myocardial infarction. During the follow-up period (198+/-38 days, complete for all patients, except one), one patient (0.6%) sustained a Q-wave myocardial infarction, one (0.6%) underwent bypass surgery, and repeat angioplasty was performed in nine patients (5.7%). In two of the nine patients, repeat angioplasty involved another lesion. Therefore, the target lesion revascularization rate during follow-up was 4.5% (seven patients). At quantitative coronary angiography, the minimal lumen diameter (mean+/-SD) increased from 1.12+/-0.34 mm before to 2.89+/-0.35 mm after stenting. Repeat angiography at 6 months was performed in 144 patients (92%). The minimal lumen diameter at follow-up was 2.12+/-0.67 mm. Restenosis (diameter stenosis of 50% or more) was documented in 12 patients or 8.3%. When the two patients with documented stent thrombosis are included, the restenosis rate amounts to 97%. CONCLUSIONS: These data confirm that, in selected patients, stents can safely be implanted without the use of systemic anticoagulation, provided optimal stent expansion is achieved. The exact role of intravascular ultrasound in the achievement of these results needs to be established by appropriately designed studies. In the meantime, intravascular ultrasound coupled with the Palmaz-Schatz stent incorporating a spiral bridge, may have contributed considerably to the immediate angiographic outcome, which in turn may explain the favourable clinical and angiographic outcome at 6 months.

Aged↗
PubMed1995

Epidemiology of spinal cord injuries in Novosibirsk, Russia.

The incidence of spinal cord injuries (SCI) in Novosibirsk is 29.7 per million per year. Almost all of these SCI patients (94.3%) are hospitalized to our clinic. Over the past 5 years (since 1989), a total of 196 patients with SCI were admitted. SCI were distributed as follows: cervical, 96 patients (49.0%); thoracic, 54 (27.5%); and lumbar, 46 23.5%). SCI was diagnosed using computed tomography (CT), magnetic resonance imaging (MRI), pneumomyelography, epidurography, radiography and electrophysiological methods (neuromyography, evoked potentials). All patients had a neurological deficit of varying degree; Frankel grade A, 64 patients (32.7%); B, 22 (11.2%); C, 67 (34.2%); and D, 43 (21.9%). Almost 40% (39.7%) of the patients had unstable fractures, most of them being in the cervical spine. One hundred and ninety patients were operated on, 52 within 3-4 h after trauma. Several types of operation were used: anterior decompression (106 patients); posterior decompression (64 patients); omentomyelopexia (seven patients); meningomyeloradiculolysis (13 patients). Conservative treatment ('halo' traction) was applied in six patients. No patient was made worse because of the surgery. Twenty four patients had a complete neurological recovery, 113 patients could be reclassified into a higher group (Frankel classification), and 59 patients had no neurological improvement. The overall mortality was 16.8% (13.7 postoperatively).

Adult↗
PubMed1991

Exact random-walk models in crystallographic statistics. VI. P.D.F.'s of magnitude of [E] for all plane groups and most space groups.

An exact calculation of the probability density function (p.d.f.) of magnitude of [E], the magnitude of the normalized structure factor, can be developed in terms of Fourier and Fourier-Bessel series whose coefficients can be expressed in terms of the characteristic function. This article provides the formulae for atomic contributions to such characteristic functions. The results presented in this study are applicable to all the plane groups and to 206 three dimensional space groups. Only the space groups isomorphous to the cubic point groups 432, 43m and m3m were omitted due to the complexity of the resulting expressions and the small deviations of the corresponding densities from the central-limit-theorem approximation, which have been observed in simulations for extreme atomic heterogeneities. Representative derivations illustrating the problems and techniques of their solution are provided. All the theoretical results have been computed numerically and compared with simulated distributions. Some results of these computations are illustrated in the accompanying paper, Part VII of this series [Rabinovich, Shmueli, Stein, Shashua & Weiss (1991). Acta Cryst. A47, 336-340].

Fourier Analysis↗
PubMed1991

Exact random-walk models in crystallographic statistics. VII. An all-space-group study of the effects of atomic heterogeneity on the P.D.F.'s of magnitude of [E].

Exact expressions have been found for the probability density functions (p.d.f.'s) of the magnitude of the normalized structure factor for all the two-dimensional and most three-dimensional space groups [Part VI: Rabinovich, Shmueli, Stein, Shashua & Weiss (1991). Acta Cryst. A47, 328-335]. The results of that investigation are used in the present article to examine some effects of atomic heterogeneity, in the various space-group symmetries, on the p.d.f.'s. Some typical comparisons are made between p.d.f.'s based on the central limit theorem and p.d.f.'s computed from exact formulae. In addition, the exact results are compared to histograms of simulated values of magnitude of [E]. It is found that the p.d.f.'s for some space groups are influenced rather strongly by the presence of outstandingly heavy scatters, but they are quite insensitive to the presence of such scatterers in other space groups. The often made general statement 'The presence of outstandingly heavy scatterers may invalidate the indications of Wilson's statistics' is made more precise here, insofar as it depends on the particular space group.

Fourier Analysis↗
PubMed1991

Prolonged continuous acyclovir treatment of normal adults with frequently recurring genital herpes simplex virus infection. The Acyclovir Study Group.

In this 3-year study of suppressive acyclovir for recurrent genital herpes, patients with more than six recurrences per year were randomized initially to 400 mg of acyclovir or placebo orally two times per day, with recurrences treated with 200 mg of acyclovir five times per day for 5 days. In the second year of the study, all patients received acyclovir as a daily suppressive or intermittent acute therapy; in the third year, all received daily acyclovir. Among 525 patients completing 3 study years, 289 received 3 years of suppressive therapy and 236 received 1 year of acute therapy followed by 2 years of suppressive therapy. Of those who completed the third year, 61% were recurrence free that year; 25% of the suppressive therapy-only group were recurrence free for all 3 years. The annual recurrence rate dropped from more than 12 recurrences per year at baseline to 1.0 (suppressive therapy) and 1.4 (acute and suppressive therapy) recurrences during the third year. No significant toxic effects were detected. Daily suppressive acyclovir therapy was effective and well tolerated.

Acyclovir↗
PubMed1990

Exact random-walk models in crystallographic statistics. V. Non-symmetrically bounded distributions of structure-factor magnitudes.

Derivations of exactly formulated Fourier-series representations of probability density functions (p.d.f.'s) of the magnitude of the structure factor are based on the fact that the structure factor and its real and imaginary parts are bounded. In some situations the bounds of the real and imaginary parts of the structure factor are different, and this gives rise to modified forms of the p.d.f.'s. Three physical examples that call for such modifications are investigated: (i) effect of dispersive scatterers on the p.d.f. of a centrosymmetric structure factor, (ii) effect of the presence of a centrosymmetric fragment in the asymmetric unit of a non-centrosymmetric space group, and (iii) effect of heavy scatterers in special positions of a non-centrosymmetric space group, where the imaginary part of the trigonometric structure factor for these special positions vanishes by symmetry. The general form of an exact Fourier p.d.f., taking account of such modifications, is derived, and expressions for Fourier coefficients are obtained for selected examples of the above three situations. It is seen that the effects of pseudocentrosymmetry may be most pronounced and those of dispersion are significant mainly in the range of small values of the structure factor.

Data Interpretation, Statistical↗
PubMed1989

Exact conditional distribution of a three-phase invariant in the space group P1. I. Derivation and simplification of the Fourier series.

An exact expression is derived for the conditional probability density function of a three-phase invariant and the general result is applied to the space group P1. The expression for the conditional density is given in terms of a sixfold Fourier series. A straightforward numerical evaluation of this series, without further analysis, is extremely time consuming. Much of the present paper is therefore devoted to an exposition of symmetries hidden in the various summations. The computational effort required for the evaluation of the above expression is thereby reduced to manageable proportions in a number of interesting cases. Results of numerical computations of the exact conditional density are given in the second paper in this series. It is also shown that the exact expression for the conditional probability reduces to that given by Cochran [Acta Cryst. (1955), 8, 473-478].

Chemistry, Physical↗
PubMed1989

Exact conditional distribution of a three-phase invariant in the space group P1. II. Calculations and comparison with the Cochran approximation.

The conditional probability density function of a three-phase invariant is computed from exact expressions derived and discussed in the first paper of this series [Shmueli, Rabinovich & Weiss (1989). Acta Cryst. A45, 361-367] and comparisons are presented of these computations with the approximate conditional density due to Cochran [Acta Cryst. (1955), 8, 473-478]. Conditional variances computed from the exact and approximate expressions are also compared. The computations are carried out for the space group P1. This is the first numerical comparison of conditional phase-invariant statistics evaluated from exact and approximate expressions. The discrepancy between these two kinds of statistics appears to be negligible if the E values involved are small and the number of atoms in the cell is moderately large. Very significant discrepancies are observed when the number of the atoms in the unit cell is small, as well as in the case of the presence of an outstandingly heavy atom. For a given triplet of magnitudes of E values or a fixed atomic composition of the unit cell the exact conditional density functions tend to have sharper peaks than the approximate ones.

Chemistry, Physical↗
PubMed1989

Neuromodulation of synovitis: capsaicin effect on severity of experimental arthritis.

This study addresses the effect of capsaicin on the severity of inflammation in experimental arthritis in the cat. Animals were sensitized with methylated bovine serum albumin (mBSA) and sequential serum antibody levels measured by enzyme-linked immunosorbent assay (ELISA). Synovitis was induced by intra-articular injection of mBSA. Histopathology revealed marked inflammatory cell infiltration and synovial cell hypercellularity, in comparison with the saline-injected control joint which showed no synovitis. In animals given intra-articular capsaicin concurrently with mBSA, there was consistently a diminution in the severity of inflammation compared with contralateral joints receiving mBSA alone. In this experimental system capsaicin appears to moderate the severity of inflammation in feline antigen-induced arthritis.

Animals↗
PubMed1989

Oxalate bone disease--an emerging form of renal osteodystrophy.

Rosette-like arrays of highly birefringent calcium oxalate crystals are commonly seen in the marrow space of bone biopsy specimens taken from patients with primary hyperoxaluria, particularly if complicated by renal failure. Similar deposits have been described in chronic hemodialysis patients with secondary forms of oxalosis. Large multinucleated histiocytes may be seen surrounding these crystal deposits. Many of these cells are histologically indistinguishable from osteoclasts. We present a patient in whom this histiocytic reaction appeared to be of sufficient magnitude to stimulate bone resorption and to cause severe osteodystrophy. This observation, and those of other investigators reviewed in the discussion, suggest that oxalate deposition within bone may contribute to the pathogenesis of uremic osteodystrophy in chronic renal failure patients with primary or secondary types of oxalosis.

Adult↗
PubMed1986

A cadaver workshop to teach medical procedures.

A seminar and workshop were conducted to train students in the indications, techniques and hazards of common diagnostic and therapeutic procedures in general medicine. Cadavers were utilized to teach the techniques of thoracentesis, pleural biopsy, chest-tube insertion, bone marrow biopsy and aspiration, paracentesis, percutaneous liver biopsy and arthrocentesis. The use of cadavers was realistic and provided standardized instruction to each student. The method gave students an opportunity to become familiar with equipment, techniques, indications and hazards of each procedure prior to actual performance. It is readily adapted to a wide variety of additional procedures.

Cadaver↗
PubMed1985

Quantitative radionuclide scanning in metabolic bone disease.

A simple method of quantifying skeletal uptake of 99Tcm-methylene diphosphonate, using a rectilinear scanner and a simultaneously image standard, is described. The pattern of quantified uptake in ten regions of the skeleton, the sacro-iliac joints and kidneys in 57 controls and 54 patients with various metabolic bone disease is presented. This method distinguishes patients with primary hyperparathyroidism and osteomalacia from controls with a sensitivity adequate for clinical purposes. In primary hyperparathyroidism the increased skull uptake of tracer correlated well with levels of serum alkaline phosphatase, plasma parathyroid hormone, urinary hydroxyproline excretion and the degree of intracortical resorption in the metacarpal bones. The skull uptake in oestoporosis was normal or moderately elevated and correlated well with bone mass density measurements of the radius. Patients with osteomalacia also showed the greatest increase in tracer uptake in the skull. Patients with thyrotoxicosis differed from most other patients by showing moderately increased uptake in shafts of long bones. We propose our method of quantitative bone uptake as a useful noninvasive test to detect metabolic bone disease and to monitor responses to therapy of bone disease.

Adolescent↗
PubMed1984

Electron microscopic study of the peritoneal kinetics of iron dextran during peritoneal dialysis in the rabbit.

Iron dextran, an electron-dense tracer, was given intravenously (100 mg of iron/100 g of body weight) to 8 normal rabbits to study its movement from the plasma to the peritoneal cavity during peritoneal dialysis. The dialysate infused at 75 ml/kg contained 1.5 g/dl of glucose in 4 animals and 4.25 g/dl in the remainder. Peritoneal dialysis was discontinued and the peritoneum was fixed in vivo at various times (20-120 min) after the injection of the iron dextran. Large amounts of tracer were detected in the effluent after draining the peritoneal cavity. Electron microscopic examination of the mesentery showed particles of iron dextran in the endothelial cells of small vessels (capillaries and venules) the interstitium and the mesothelial cells adjacent to vessels irrespective of the dialysate concentration or duration of dialysis. Tracer was not clearly demonstrated in the interendothelial or intermesothelial spaces. In the mesothelial cells, the particles were found exclusively in (small, elongated or large) vesicles, while in the endothelial cells they were both in vesicles and free in the cytoplasm. Our findings suggest that during the 20- to 120-min period after intravenous administration, the intracellular transport of iron dextran, depends on either moving vesicles or the presence of pre-existing tunnels in the mesothelial cells of rabbit mesentery.

Animals↗
PubMed1984

Oncogenic osteomalacia associated with a mesenchymal chondrosarcoma.

A patient with phosphaturic osteomalacia without chemical or pathological evidence of hyperparathyroidism and subnormal urinary cyclic AMP excretion was treated with vitamin D and phosphates for 9 months with partial improvement of osteomalacia, but not phosphaturia. Subsequent removal of a mesenchymal chondrosarcoma of the foot led to prompt resolution of phosphaturia and healing of the osteomalacia. Although 1,25-dihydroxyvitamin D levels were not obtained before vitamin D therapy, the levels noted during continued severe phosphaturia preoperatively were not lower than those obtained several months postoperatively during the healing phase. Studies done 1 year after tumor removal showed normalization of phosphaturia, urinary cyclic AMP, and bone histology. We suggest that the tumor elaborated products which promoted nonparathyroid mediated phosphate excretion independently from any effects on vitamin D metabolism.

Bone and Bones↗
PubMed1983

Protective effect of poly-2-vinylpyridine-N-oxide on susceptibility of silica-treated mice to experimental histoplasmosis.

We have studied the ability of poly-2-vinylpyridine-N-oxide (PVNO), a lysosomal stabilizing agent, to abrogate the cytotoxic effects of silica on macrophages. Male C3H/HeN mice were pretreated with PVNO and inoculated intravenously with silica particles. At 24 h after silica injection, silica-treated and -untreated mice were challenged intravenously with varying doses of live yeast cells of Histoplasma capsulatum. All mice receiving silica died when challenged with 5 X 10(5) yeast cells of Histoplasma sp. compared with no deaths in PVNO-pretreated animals and 10% mortality in controls not receiving PVNO or silica. When animals were given 2.5 X 10(5) yeast cells (a sublethal dose), the protective effect of PVNO was seen by a reduction in splenomegaly and viable Histoplasma sp. present in the spleen. Furthermore, PVNO alone showed a significant protective effect (P less than 0.05) against a lethal challenge with Histoplasma sp. Prior treatment with PVNO also protected mouse peritoneal macrophages from the cytotoxic effects of silica particles in vitro. These results indicate that PVNO abrogates the cytotoxicity of silica particles on macrophages and also increases the resistance of mice to histoplasmosis.

Animals↗