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Biomedical subjects

M Ilan

Publications and source records attributed to M Ilan.

18 recordsLinked to original sources
PubMed2007

Chemical versus mechanical bioerosion of coral reefs by boring sponges--lessons from Pione cf. vastifica.

Bioerosion by boring sponges is an important mechanism shaping the structure of coral reefs all around the world. To determine the excavation rate by boring sponges, we developed a system in which chemical and mechanical boring rates [calcium carbonate (CaCO(3)) dissolution and chip production, respectively] were measured simultaneously in experimental tanks containing reefal rock inhabited by a boring sponge. Pione cf. vastifica (Hancock 1849) was chosen as a model species to study the erosion rate of boring sponges. It is an abundant species in the coral reefs of the Nature Reserve Reef, Elat, Gulf of Aqaba, northern Red Sea, reaching maximum abundance at 25-30 m. The rate of chemical bioerosion was determined from the increase in tank-seawater alkalinity over time, and the mechanical bioerosion rate was estimated from the total amount of CaCO(3) chips produced over the same time interval. The measured bioerosion rate of P. cf. vastifica was 2.3 g m(-2) sponge day(-1), showing seasonal but not diurnal variations, suggesting that the zooxanthellae harboring the sponge have no effect on its boring rate. The experiments indicated clearly that per each mass of chips that P. cf. vastifica produces during its boring activity, it dissolves three masses of reef CaCO(3) framework. Assuming that some additional boring sponges can use a similar strategy of bioerosion, these findings suggest that chips, the most obvious erosion products of boring sponges, represent only a small fraction of boring sponge bioerosion capacity.

Animals↗
PubMed2000

Immunolocalization of the Toxin Latrunculin B within the Red Sea Sponge Negombata magnifica (Demospongiae, Latrunculiidae).

The location of latrunculin B, the major toxin of the Red Sea sponge Negombata magnifica, was revealed using specific antibodies. Antibodies from rabbits immunized with a conjugate of latrunculin B with keyhole limpet hemocyanin (KLH) were purified over a latrunculin B-Sepharose affinity column. Analysis of immunohistochemical and immunogold-stained sponge sections, using light and transmission electron microscopy, revealed latrunculin B labeling mostly beneath the sponge cortex at the border between the external (ectosome) and internal (endosome) layers (ectosome-endosome border). The endosome was less labeled than the border. Immunogold localization revealed latrunculin B in the sponge cells but not in its prokaryotic symbionts. Archeocytes and choanocytes were significantly more labeled than other cells. The antibodies primarily labeled membrane-limited vacuoles within archeocytes and choanocytes that are perhaps latrunculin B secretory or storage vesicles. Peripheral latrunculin B may have a role in defense against external epibionts, predators, and competitors.

Journal Article↗
PubMed1999

Effect of isoflurane on defibrillation threshold in biphasic active-can defibrillation systems.

In two patients receiving implantable cardioverter-defibrillators (ICD) for spontaneous and inducible ventricular tachyarrhythmias, the use of isoflurane appeared to significantly lower defibrillation thresholds (DFT) at implantation. In the first, at initial implantation and subsequent revision using isoflurane, adequate DFTs were verified by multiple tests. Post-implantation testing using midazolam and fentanyl revealed significantly higher DFTs, necessitating a third operation without isoflurane to obtain an adequate and subsequently verifiable DFT. During the second case, discontinuation of isoflurane intraoperatively resulted in a DFT rise within 25 minutes. In patients receiving general anesthesia for ICD implantation, this possible DFT effect of isoflurane should be recognized.

Anesthetics, Intravenous↗
PubMed1997

Treatment of spontaneous coronary artery dissection: report of three cases.

Spontaneous coronary artery dissection is an extremely rare cause of myocardial infarction. It has been reported mainly in young women during or after pregnancy. The prognosis and treatment of coronary dissection are not clear. We report three cases of spontaneous coronary artery dissection in young women. One of them was pregnant and one was 2 weeks after delivery. The dissection involved the left anterior descending artery (LAD) in two cases and the left main coronary artery in one case. There was no evidence of atherosclerosis on angiography or intracoronary ultrasound in any of the patients. Two of the women were treated by stent implantation with excellent results. This is the first known report of successful coronary stenting of spontaneous coronary artery dissection. The pregnant woman was not a candidate for stent implantation and underwent implantation of the left internal mammary to the LAD without cardiopulmonary bypass. She completed her pregnancy uneventfully.

Adult↗
PubMed1996

Improvement in ischemic parameters during repeated exercise testing: a possible model for myocardial preconditioning.

Repeated short episodes of coronary occlusion in experimental animals, and in humans during balloon angioplasty, cause myocardial preconditioning. This study examines whether myocardial ischemia induced by repeated exercise testing can reduce the extent of ischemia induced by subsequent exercise tests. Twenty-six patients with positive stress tests underwent 3 treadmill exercise tests at 30-minute intervals. Two additional tests were performed on each of the previous 2 days in order to eliminate and/or reduce the training effect. All 3 exercise tests were of similar work load. In spite of that, total ischemic time was markedly shortened from 633 to 399 seconds (p <0.0001) as well as the recovery time from 259 to 126 seconds (p <0.0001) between the first and the second tests. There was no further improvement on the third test. Time to 1-mm ST depression was prolonged from 487 to 593 seconds (p = 0.004) and double product at 1-mm ST depression was increased in the second test from 20,322 to 22,325 mm Hg/second (p = 0.008), implying a higher ischemic threshold. An improvement of > or = 10% in < or = 1 ischemic parameter was observed in 25 of the 26 patients and in > or = 2 of the ischemic parameters in 76% of the patients. Improvement in ischemic parameters develops during repeated exercise induced ischemia in most patients. We suggest that this phenomenon, which was previously known as "warm up," is the clinical counterpart of myocardial preconditioning which develops not only during ischemia caused by reduction in coronary flow, but also during demand-induced ischemia.

Coronary Angiography↗
PubMed1996

Intracrystalline macromolecules are involved in the morphogenesis of calcitic sponge spicules.

Control over the shapes of biologically formed crystals is generally not well understood. We have studied the morphogenesis of the different-shaped calcareous sponge spicules using high-resolution synchrotron X-ray diffraction. We show that a remarkable correlation exists between the distribution of defects within spicule crystals at the nanometer level and their macroscopic morphologies at the millimeter level. These defects are produced by controlled intercalation of specialized macromolecules into the crystals. We also show that such intracrystalline macromolecules are involved in the regulation of the shapes of synthetic crystals grown de novo from solution, and epitaxially overgrown on the spicule surfaces. We conclude that intracrystalline macromolecules play an important role in modulation of the morphologies of the forming biogenic crystals. Possible mechanisms that may account for the observed growth patterns are supported by fluorescence labeling experiments in vivo.

Animals↗
PubMed1995

The safety of dental mini-magnets in patients with permanent cardiac pacemakers.

To evaluate the safety of prosthetic mini-magnets, 12 patients treated with implanted cardiac pacemakers were examined. Small cylindric magnets were applied one, two, and three at a time to constant points on the pacemaker under electrocardiographic monitoring. No influence on the pacemaker was detected in nine of the patients, but limited changes were encountered in three patients. However, the changes disappeared when the magnets were moved 1 cm away. The conclusion was that the use of mini-magnets in dental care in patients with implanted pacemakers is safe and acceptable.

Aged↗
PubMed1995

Morphogenesis of calcitic sponge spicules: a role for specialized proteins interacting with growing crystals.

Crystals formed in biological tissues often adopt remarkable morphologies that are thought to be determined mainly by the shapes of the confined spaces in which they grow. Another possible way of controlling crystal shape, demonstrated only in vitro, is by means of specialized proteins preferentially interacting with certain crystal faces. In so doing, they reduce the rate of growth in these directions and consequently change the overall crystal shape. In an X-ray diffraction study of the distribution of defects within the lattice of calcite crystals produced by certain sponges, we show that a remarkable correlation exists between the defect patterns or crystal texture and the macroscopic morphology of the spicules. This was observed in two cases in which proteins are present within the spicule crystal, but not in a third case where such intracrystalline proteins are absent. Furthermore, one of the spicules exhibited marked differences in texture even within families of structurally identical crystal planes, demonstrating that the organisms exert exquisite control over the microenvironment in which crystals grow. We conclude that highly controlled intercalation of specialized proteins inside the crystals is an additional means by which organisms control spicule growth.

Animals↗
PubMed1994

A prospective randomized trial of intravenous magnesium versus intravenous propranolol in acute myocardial infarction.

A total of 266 patients entered into a study comparing the effect of intravenous magnesium and propranolol following acute myocardial infarction. Of these, 97 were able to receive either drug and were therefore randomized into the magnesium (n = 51) or propranolol group (n = 46). 88 patients were unable to receive propranolol and formed a third group (NR) while a further 81 patients could not receive either drug and formed a fourth group (N). The study showed that intravenous magnesium was as effective in preventing potentially lethal arrhythmias as propranolol and could be given to some 70 per cent of such patients whereas propranolol could only be given to 36 per cent.

Aged↗
PubMed1994

Long-term follow-up after acute myocardial infarction in patients randomized to treatment with intravenous magnesium or intravenous propranolol in the acute phase.

Ninety-five patients with acute myocardial infarction were followed up for 6 months to 3 years (mean 25.4 months) in a preliminary study to compare the effects of intravenous magnesium (49 patients) with that of intravenous propranolol (44 patients) given immediately after admission to the intensive care unit. There were four cardiac deaths in the propranolol group and no deaths in the magnesium group (P < 0.046) and 27 per cent of patients who received propranolol subsequently developed cardiac failure as opposed to 12 per cent of those who had received magnesium (P < 0.04). Intravenous magnesium given in the early stages of myocardial infarction reduces the subsequent cardiac death rate possibly by reducing infarct size.

Aged↗
PubMed1993

Calcium control of metamorphosis in polychaete larvae.

The importance of Ca2+ in the control of metamorphosis of a marine invertebrate larva was investigated. An excess of [Ca2+] in the external medium induced metamorphosis of Phragmatopoma californica (polychaete) larvae in a concentration-dependent manner. This effect is specific for calcium, and not simply the result of osmotic changes, as an excess of Mg2+ did not induce metamorphosis. Consistent with this finding, the calcium ionophore, A23187, also induced metamorphosis in a concentration-dependent manner. Paradoxically, however, the aromatic compounds diltiazem, verapamil, D600, and nifedipine, known to block Ca2+ channels in other systems, also induced metamorphosis. When exposed to diltiazem for only 20 h and subsequently washed free of this compound, 95% of the larvae metamorphosed and developed normally. Previous studies have demonstrated that the induction of metamorphosis in Phragmatopoma californica is controlled by chemosensory recognition of an exogenous morphogen and mediated by an excitatory pathway that involves adenyl cyclase and cyclic AMP. Because cellular excitation and cyclic AMP-dependent signal transduction generally involve the participation of calcium ion, the most parsimonious explanation for the results reported here include (1) direct control of the morphogenetic pathway by calcium ion, and (2) complexities of the calcium regulation of this process, or a functional similarity between the structurally related aromatic effectors tested and the natural inducer of metamorphosis.

Animals↗
PubMed1993

Progression and regression of coronary artery disease in one year. Quantitative angiographic assessment in patients with stable angina pectoris.

The rate of progression of coronary artery stenoses (CAS) is not clear. Spontaneous regression may also occur. Seventy-one CAS in 25 patients who were enrolled in a study of the effects of chromium on CAS were analysed. Coronary angiography was performed in multiple views and patients randomised to chromium or placebo treatment. Videodensitometric quantitative analysis was performed using a Vanguard XR70 Analyzer. After 1 year all patients were recatheterised. Corresponding frames from identical views were analysed. CAS were assessed with the observers blinded to the initial study results. No differences were found between chromium or placebo and the results have been combined. There was no overall progression of CAS as assessed by % area stenosis (p = 0.65), % diameter stenosis (p = 0.19), stenotic area (p = 0.87), or stenotic diameter (p = 0.99). However, 20% of individual lesions progressed, while 10% regressed, and 70% remained the same. These changes must be taken into account in studies of interventions which may modify the course of coronary atherosclerosis, and if coronary by-pass surgery is to be performed with a 1 year delay after angiography.

Adult↗
PubMed1992

Reproducibility of measurements of coronary narrowings by videodensitometry and by digital calipers.

Computer-assisted videodensitometry has been shown to be a reliable and reproducible method of measuring absolute and relative coronary narrowings. Using a commercially available analyzer (Vanguard XR70) we confirmed intra- and interobserver reproducibilities in 34 narrowings in 9 patients. Analyses were performed on normal area and diameter, stenotic area and diameter, percent area stenosis and percent diameter stenosis. For all 6 analyses, excellent intra- and interobserver correlations were found (r = 0.93-0.98), with slopes close to 1 and intercepts close to zero. Caliper measurements (Mitutoyo Digimatic) of the same lesions by the same observers showed good inter- and intraobserver reproducibility for percent diameter stenosis (r = 0.90 and 0.86), with mean interobserver difference of 1.67 +/- (SD) 6.4% and intraobserver difference of 2.97 +/- (SD) 7.9%. However, less good correlations were found between caliper and videodensitometric measurements of percent diameter stenosis; r = 0.61 and 0.76 for the two observers. These data suggest that videodensitometry is a highly reproducible quantitative angiographic method, suitable for documenting changes in the severity of coronary artery lesions, both spontaneous or related to interventions. Caliper measurements do not provide the same degree of accuracy, but they have acceptable reproducibility in measuring diameter stenosis. As such, they are also suitable for assessing changes in severity of coronary artery lesions in individual patients.

Angioplasty, Balloon, Coronary↗
PubMed1992

[Effect of workload on physicians' drug prescribing].

The possible effect of workload on the prescribing of drugs by physicians was studied in 10 primary care pediatricians during a 1-month period. The intraphysician variability revealed a positive correlation (p less than 0.05) between workload and prescription of antibiotics in the case of 2 of the physicians and a negative correlation (p less than 0.05) between workload and prescription of all drug items in another physician. The prescribing of the other 7 was not affected by changes in daily workload. The interphysician variability study revealed a significantly increased rate of prescription of analgesics/antipyretics by physicians with increased monthly workload (r = 0.91, p less than 0.001). These results suggest that although the prescribing habits of a minority of physicians may be affected by their workloads, prescription rates remain stable for the individual physician on most occasions. However, physicians with high workloads tend to prescribe more analgesics/antipyretics than those with low workloads.

Analgesics↗
PubMed1990

Reproducibility of measurements of coronary narrowings by videodensitometry: unreliability of single view measurements.

Computer-assisted videodensitometry has been shown to be a reliable and reproducible method of measuring absolute and relative coronary narrowings. Using a commercially available analyzer (Vanguard XR70) we confirmed the intra- and interobserver reproducibilities in 34 narrowings in 9 patients. Analyses were performed on normal area and diameter, stenotic area and diameter, percent area stenosis and percent diameter stenosis. For all 6 analyses, excellent intra- and interobserver correlations were found (r = 0.93-0.98), with slopes close to 1 and intercepts close to zero. In a separate study of 16 lesions in 11 patients, each lesion was analyzed in both the RAO and LAO planes. Correlation between the measurements was reasonable with r = 0.76 for the stenotic area and r = 0.75 for the absolute diameter stenosis. However, with suboptimal slopes (0.54 and 0.63 respectively), actual differences between measurements in the two planes were often unacceptably large. These data suggest that videodensitometry is a highly reproducible quantitative angiographic method; however, single view analyses are inadequate for comparative studies.

Absorptiometry, Photon↗
PubMed1990

Cor triatriatum sinistrum: diagnosis by Doppler echocardiography.

Cor triatriatum (CTT) sinistrum is a rare, congenital left ventricular inflow anomaly. Previous reports have used cardiac angiography, two-dimensional echocardiography, transesophageal echocardiography and magnetic resonance imaging to establish the diagnosis prior to surgery. We report a case of CTT diagnosed by echocardiography whose hemodynamic significance was established by the use of pulsed wave and color Doppler techniques. Immediate surgery was recommended based on anatomical and hemodynamic parameters.

Cor Triatriatum↗