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Biomedical subjects

D Atar

Publications and source records attributed to D Atar.

At least 37 records · Page 2Linked to original sources
PubMed2000

Congenital pseudoarthrosis of the tibia.

Congenital pseudoarthrosis of the tibia remains one of the most difficult conditions to treat in orthopedic surgery. Seven cases were treated in our hospital by different methods. Three out of seven patients were healed, two of these refractured. At follow-up, the success rate was 14% (one out of seven cases). It is our recommendation that early primary amputation with an appropriate prosthesis should be considered, and that the final evaluation should not be based on obtaining bone union, but on the level of function of the lower extremity.

Adolescent↗
PubMed2000

Reduced concentrations of soluble adhesion molecules after antioxidant supplementation in postmenopausal women with high cardiovascular risk profiles--a randomized double-blind study.

BACKGROUND: One of the suggested mechanisms of increased cardiovascular risk in postmenopause is a loss of the antioxidant effects of estrogens. It has been shown that classical cardiovascular risk factors increase oxidative stress on the arterial wall, and that endothelial cells react to this insult by increased expression of cellular adhesion molecules (CAM), which in turn are markers of arterial wall inflammation. METHODS: A randomized, placebo-controlled, double-blind study was performed in 60 postmenopausal women with high cardiovascular risk profiles, but free from clinical atherosclerotic disease. Patients were randomized to either antioxidant supplementation (using a combination of natural antioxidants; n = 30) or placebo (n = 30), and followed for 12 weeks. The concentrations of the adhesion molecules sVCAM-1 and sICAM-1 were measured by ELISA at baseline and at the end of the study, as well as total cholesterol, LDL, HDL, triglycerides and blood pressure. RESULTS: 27 women in the antioxidant supplementation group and 29 on placebo completed the study. At baseline, there were no significant differences in measured parameters between the groups: sICAM-1 concentrations were 341.8 +/- 116.9 vs. 349.9 +/- 104.6 ng/ml (active treatment vs. placebo; p = n.s.) and sVCAM-1 concentrations were 780.5 +/- 325.8 vs. 761.0 +/- 333.7 ng/ml (p = n.s.). In contrast, at the end of the study, sICAM-1 concentrations were 301.6 +/- 56.0 vs. 356.0 +/- 134.8 ng/ml (active treatment vs. placebo; p = 0.053) and sVCAM-1 concentrations were 656.0 +/- 326.5 vs. 818.5 +/- 381.0 ng/ml (p = 0.04). There were no significant differences between or changes within the groups in measured cholesterol and blood pressure. CONCLUSION: Antioxidant supplementation reduces serum concentrations of endothelium-derived adhesion molecules sICAM-1 and sVCAM-1 in postmenopausal women with high cardiovascular risk profiles.

Aged↗
PubMed1999

Isolation, electron microscopic imaging, and 3-D visualization of native cardiac thin myofilaments.

An increasing number of cardiac diseases are currently pinpointed to reside at the level of the thin myofilaments (e.g., cardiomyopathies, reperfusion injury). Hence the aim of our study was to develop a new method for the isolation of mammalian thin myofilaments suitable for subsequent high-resolution electron microscopic imaging. Native cardiac thin myofilaments were extracted from glycerinated porcine myocardial tissue in the presence of protease inhibitors. Separation of thick and thin myofilaments was achieved by addition of ATP and several centrifugation steps. Negative staining and subsequent conventional and scanning transmission electron microscopy (STEM) of thin myofilaments permitted visualization of molecular details; unlike conventional preparations of thin myofilaments, our method reveals the F-actin moiety and allows direct recognition of thin myofilament-associated porcine cardiac troponin complexes. They appear as "bulges" at regular intervals of approximately 36 nm along the actin filaments. Protein analysis using SDS-polyacrylamide gel electrophoresis revealed that only approximately 20% troponin I was lost during the isolation procedure. In a further step, 3-D helical reconstructions were calculated using STEM dark-field images. These 3-D reconstructions will allow further characterization of molecular details, and they will be useful for directly visualizing molecular alterations related to diseased cardiac thin myofilaments (e.g., reperfusion injury, alterations of Ca2+-mediated tropomyosin switch).

Actin Cytoskeleton↗
PubMed1999

Increased soluble platelet/endothelial cellular adhesion molecule-1 and osteonectin levels in patients with severe congestive heart failure. Independence of disease etiology, and antecedent aspirin therapy.

BACKGROUND: Platelet-endothelial interactions modulated by adhesion molecules, may play an important role in the pathogenesis of congestive heart failure (CHF). Soluble levels of these molecules and platelet-derived substances are reportedly elevated in patients with CHF. However, no data are available on the plasma levels of Platelet/Endothelial Cell Adhesion Molecule-1 (PECAM-1), and platelet-derived osteonectin in this growing population. METHODS AND RESULTS: Soluble levels by ELISA were prospectively determined in patients with severe CHF (n = 37) and correlated to etiology and antecedent aspirin use, and compared with 14 healthy control subjects. Left ventricular dysfunction was attributed to idiopathic dilated cardiomyopathy in 18 and coronary artery disease in 19 patients. Twenty-one patients were aspirin-free and 16 patients were using aspirin (81-500 mg daily). Elevated soluble PECAM-1 (51.31+/-2.44 ng/ml, P = 0.0001), and osteonectin (826.27+/-22.37 ng/ml, P = 0.0001) were observed in patients with CHF, as compared to healthy controls (32.56+/-1.21 ng/ml, and 478.02+/-31.32 ng/ml, respectively). Neither etiology of CHF, nor antecedent aspirin therapy significantly affects the levels of PECAM-1 or osteonectin. CONCLUSIONS: Despite long-term aspirin therapy and independently of the etiology of the disease, soluble PECAM-1 and osteonectin were elevated in the majority of patients with severe CHF, suggesting platelet-endothelial activation. The present data provide additional evidence that more potent anti-platelet and endothelial preservation regimens deserve further study in the heart failure population.

Aged↗
PubMed1999

Profound ECG abnormalities during emergency cesarean section in a patient with pre-eclampsia.

A case of severe ECG abnormalities occurring during pre-eclampsia is presented. Although these electrocardiographic changes were indicative of severe alterations of coronary flow, neither structural nor functional abnormalities could be documented during subsequent diagnostic workup. The pathogenetic pathways potentially involved in this case including coronary spasms are briefly discussed.

Adult↗
PubMed1999

Results of complete soft tissue clubfoot release combined with calcaneocuboid fusion in the 4-year to 8-year age group following failed clubfoot release.

A subset of postoperative recurrent clubfeet was isolated in a group of patients 4 to 8 years old. Twenty-seven consecutive patients who underwent redo surgery consisting of complete soft tissue clubfoot release combined with a calcaneocuboid fusion were reviewed for this study. Twenty-six feet of 27 feet in 20 patients had a long-term good result, suggesting that this procedure is the one of choice for this age group.

Algorithms↗
PubMed1998

Distinct subcellular localization of calcium binding S100 proteins in human smooth muscle cells and their relocation in response to rises in intracellular calcium.

Changes in cytosolic Ca2+ concentration control a wide range of cellular responses, and intracellular Ca2+-binding proteins are the key molecules to transduce Ca2+ signaling via interactions with different types of target proteins. Among these, S100 Ca2+-binding proteins, characterized by a common structural motif, the EF-hand, have recently attracted major interest due to their cell- and tissue-specific expression pattern and involvement in various pathological processes. The aim of our study was to identify the subcellular localization of S100 proteins in vascular smooth muscle cell lines derived from human aorta and intestinal smooth muscles, and in primary cell cultures derived from arterial smooth muscle tissue under normal conditions and after stimulation of the intracellular Ca2+ concentration. Confocal laser scanning microscopy was used with a specially designed colocalization software. Distinct intracellular localization of S100 proteins was observed: S100A6 was present in the sarcoplasmic reticulum as well as in the cell nucleus. S100A1 and S100A4 were found predominantly in the cytosol where they were strongly associated with the sarcoplasmic reticulum and with actin stress fibers. In contrast, S100A2 was located primarily in the cell nucleus. Using a sedimentation assay and subsequent electron microscopy after negative staining, we demonstrated that S100A1 directly interacts with filamentous actin in a Ca2+-dependent manner. After thapsigargin (1 microM) induced increase of the intracellular Ca2+ concentration, specific vesicular structures in the sarcoplasmic reticulum region of the cell were formed with high S100 protein content. In conclusion, we demonstrated a distinct subcellular localization pattern of S100 proteins and their interaction with actin filaments and the sarcoplasmic reticulum in human smooth muscle cells. The specific translocation of S100 proteins after intracellular Ca2+ increase supports the hypothesis that S100 proteins exert several important functions in the regulation of Ca2+ homeostasis in smooth muscle cells.

Aorta↗
PubMed1998

[Necrotizing soft tissue infection].

The dramatic course of necrotizing soft tissue infection represents a medical emergency, since it is limb- and life-threatening. Most necrotizing soft tissue infections are caused by mixed aerobic and anaerobic Gram-negative and Gram-positive organisms. Most case have been reported in immuno-compromised hosts after penetrating trauma or surgery. We describe a unique series of cases of necrotizing soft tissue infection. The mainstay of treatment is early and daily debridement of devitalized tissue and broad-spectrum antibiotics. Hyperbaric oxygen therapy should be considered.

Aged↗
PubMed1998

[Pelvic lytic lesion, and the need to suspect osteoporosis-related fractures].

Insufficiency fractures of the pelvis may be overlooked as a cause of hip or groin pain. These fractures occur in the elderly, usually those with pronounced osteopenia of the pelvis. Predisposing factors include corticosteroids, local irradiation and postmenopausal osteoporosis. These fractures are difficult to detect clinically and plain radiographs and other studies may be misleading, delaying diagnosis and treatment. A 65-year-old woman had left groin and hip pain for 2 months with no history of trauma. Plain radiographs showed lytic lesions in the left pubic rami. Bone scan revealed increased uptake in that region, suggesting metastatic bone disease. Computed tomography and magnetic resonance imaging demonstrated fractures in the left superior and inferior pubic rami, with callus formation with no involvement of soft tissues. Quantitative computed tomography indicated low calcium concentration, below fracture threshold. The diagnosis of insufficiency fractures of the pelvis was confirmed by the favorable clinical and radiographic outcome. It is therefore important to be familiar with the appearance and location of these fractures.

Aged↗
PubMed1998

Dobutamine stress echocardiography to detect inducible demand ischemia in anesthetized patients with coronary artery disease.

BACKGROUND: A cardiac risk stratification test that can be performed during operation would be expected to give valuable information for the therapeutic management of patients who need urgent noncardiac surgery. This study was designed to evaluate the feasibility and safety of a dobutamine-atropine stress protocol to detect inducible demand ischemia in anesthetized patients. METHODS: A standard dobutamine-atropine stress protocol was performed in 80 patients with severe coronary artery disease during fentanyl-isoflurane anesthesia. Biplane transesophageal echocardiography and 12-lead electrocardiography were used to detect induced ischemia. After dobutamine testing, esmolol, nitroglycerin, or both were used to revert ischemia and any hemodynamic changes, as appropriate. RESULTS: The protocol detected inducible ischemia or achieved the target heart rate in 75 of the 80 (94%) patients. None of the prospectively defined adverse outcomes, such as cardiovascular collapse, severe ventricular arrhythmia, persistent (> or =5 min) ischemia, or hemodynamic instability, occurred in any of the patients. Ischemia was induced and detected in 73 of the 80 (91%) patients. CONCLUSION: Dobutamine stress echocardiography is feasible in anesthetized patients with severe coronary artery disease. The lack of serious complications and the high sensitivity to detect inducible ischemia in this patient population provide the basis for further evaluation of the safety and diagnostic value of dobutamine stress echocardiography during general anesthesia in larger studies of patients at risk for coronary artery disease undergoing noncardiac surgery.

Anesthesia, General↗
PubMed1998

Pregnancy-associated osteoporosis: preliminary densitometric evidence of extremely rapid recovery of bone mineral density.

Pregnancy-associated osteoporosis (PAO) is considered a rare complication of pregnancy and lactation, but the actual incidence is unknown. Pregnancy-associated osteoporosis is self-limited and usually does not recur during subsequent pregnancies, but little is known about its pathogenesis or the dynamics of bone density during the evolution and recovery phases of an acute episode. We report a case of idiopathic PAO. Follow-up included repeat measurements of bone density, which revealed a striking rate of improvement during the first 6 months after delivery (50% increase) and continuous improvement, at a diminished though still relatively high rate, during the successive year. This observation provides insight into the early stages of recovery from PAO.

Absorptiometry, Photon↗
PubMed1998

Changes in hemostasis after parenteral magnesium in myocardial ischemia-reperfusion: from animal studies to clinical trials.

There has been some debate regarding the benefit of parenteral magnesium (Mg) in the treatment of acute myocardial infarction (AMI), due to conflicting results from animal studies and recent clinical trials. Several different hypotheses, proposing antiplatelet, and antithrombotic properties have been advanced to explain the cardioprotective properties of Mg during AMI. Although early clinical results were promising, there were serious flaws in the design and the logistics of small trials including out of date methodology, absence of control groups, and possible observer bias due to unblinded data collection. Moreover, the latest large-scale megatrial Fourth International Study of Infarct Survival (ISIS-4) provided conflicting data and caused major controversy, which will be difficult to resolve. Proponents of Mg therapy have suggested that the potential benefit was not seen in ISIS-4 because Mg was administered too late. Further clinical trials, well-designed, and carefully conducted, should elucidate possible benefits of parenteral Mg during myocardial injury, especially in conjunction with new and aggressive reperfusion techniques. The benefits of parenteral Mg in an expanding array of clinical conditions, including AMI, may be directly related to an improved hemostatic profile. This review summarizes the latest, and often confusing data on the effects of Mg on certain hemostatic characteristics which may be directly relevant to the existing controversy.

Animals↗
PubMed1998

[Vacuum phenomenon in the hip joint: diagnostic value].

Vacuum phenomenon is well known in degenerative spinal disease in the elderly, but is seldom seen in other joints, especially in children. The phenomenon does not represent a pathological finding, and can be used for imaging of the articular facets, mainly in the hip and knee joints. We report a patient with this phenomenon in the hip joint.

Arthrography↗
PubMed1997

[Myocardial reperfusion: salvation or danger for the heart muscle? Stunning, hibernation and preconditioning: the states of endogenous cardiac protection against ischemia].

During most of our decade myocardial ischemia was regarded as an all-or-nothing phenomenon, either resulting in myocardial necrosis in case of severe and prolonged ischemia, or in negligible changes when ischemia was transient and mild. This view has been challenged in the wake of new discoveries during the last 15 years which indicate that depressed myocardial contractility with preserved viability may exist during or following ischemic insults. The clinical and pathophysiologic characteristics of these ischemic myocardial syndromes--stunning, hibernation and preconditioning--are discussed in the present overview.

Humans↗