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Biomedical subjects

A Mizrahi

Publications and source records attributed to A Mizrahi.

At least 19 recordsLinked to original sources
PubMed2006

Detection of venous invasion in surgical specimens of colorectal carcinoma: the efficacy of various types of tissue blocks.

BACKGROUND: Venous invasion (VI) is an important prognosis predictor after colorectal carcinoma (CRC) resection, enabling more accurate staging and influencing postoperative management. AIMS: To assess/compare various tissue block types (perpendicular, tangential, across mesentery (AM), from major vessels or lymph nodes (LNs)) for VI detection in CRC. METHODS: Fifty two CRCs (51 colectomies, one polypectomy) were studied. Tumours were measured, surface area calculated, and colorectum and bowel wall sites recorded. Weigert's staining for elastin facilitated VI detection. VI sites, type, and amount were recorded. Ratios of relative yield of tissue block types to their frequency were calculated. RESULTS: Average numbers of tissue blocks/colectomy specimen were: perpendicular, 10.2; tangential, 9.1; AM, 3.3; from major vessels, 2.1. Average number of LNs examined was 16.47. VI was detected in 22 tumours. Overall, VI was detected in 16 perpendicular, seven tangential, five AM, and two LN blocks. VI was detected in eight, two, one, and three tumours in perpendicular, tangential, LN, and AM blocks alone, respectively. In seven tumours, VI was identified in multiple tissue block types. The average number of blocks obtained was 39.7, 42.1, and 38 from all tumours, VI positive, and VI negative tumours, respectively (p = 0.0497). Efficacy to detect VI was 2.151, 2.088, 1.092, 0.172, and 0 for AM, perpendicular, tangential, LN, and mesenteric vessel blocks, respectively. CONCLUSIONS: VI was identified most frequently and in eight cases only in perpendicular blocks. However, extramural VI was detected in six tumours only in blocks cut tangentially, AM, or from harvested LNs. Hence, all these types of blocks should be submitted routinely and scanned for VI.

Adult↗
PubMed2002

A laboratory study of the effect of calcium hydroxide mixed with iodine or electrophoretically activated copper on bacterial viability in dentinal tubules.

AIM: The aim of this laboratory study was to evaluate the ability of calcium hydroxide (CH), CH/iodine-potassium iodide (IKI) and electrophoretically activated copper to kill bacteria in dentinal tubules. METHODOLOGY: In an in vitro model of dentinal tubule infection, 42 cylindrical root specimens, prepared from freshly extracted bovine teeth were used. After removal of the smear layer, intracanal dentinal tubules were infected with Enterococcus faecalis for 3 weeks. CH alone or preparations of CH with copper or IKI were placed in the root canal for 1 week. In specimens containing copper/CH, an electrophoretic current(5 mA/5 min) was applied using two electrodes follow-ing placement of the medicament in the canal. Powder dentine samples obtained from the canal wall using ISO sizes: 025, 027, 029, 031 and 033 burs were examined for the presence of viable bacteria by inoculating agar plates and counting colony forming units (cfu). RESULTS: A significant difference was found between the experimental groups and the positive control group. CH and CH/IKI significantly (P < 0.001)reduced bacterial viability in dentinal tubules to a depth of 200 microm. Specimens with CH/IKI had significantly fewer viable bacteria than CH alone in tubules between the depths of 200-500 microm. Treatment with CH/copper and electrophoresis was most effective: specimens showed no viable bacteria in dentinal tubules to a depth of 500 microm from the root-canal space. CONCLUSIONS: IKI or electrophoretically activated copper additives can significantly improve the antibacterial properties of CH in dentinal tubules.

Animals↗
PubMed2001

Synaptic reorganization induced by selective photoablation of an identified neuron.

The maintenance of synaptic strength and specificity in the CNS may depend on interactions among postsynaptic dendrites. We examined the effect of removing a neuron on synaptic organization. A single identified postsynaptic neuron in the adult cercal system of the cockroach was removed with photoablation. After a 30 d recovery period, the synaptic connectivity and morphology of the intact presynaptic and postsynaptic neurons were analyzed. The synaptic connectivity was reorganized in a manner that was consistent with functional plasticity. To associate anatomical changes with this reorganization, we analyzed the morphology of the presynaptic and postsynaptic neurons by quantitative morphometry. Both presynaptic and intact postsynaptic neurons maintained a stable morphology after removal of a neighboring postsynaptic neuron. Using the Hausdorff Match method (HM) (Mizrahi et al. 2000), we found that the spatial organization of the intact dendritic and axonal trees after ablation of a postsynaptic neuron remained stable. Thus, interactions with neighboring neurons were not necessary for maintaining dendritic morphology in the adult nervous system. However, adult central synapses were capable of adjusting to maintain normal function.

Action Potentials↗
PubMed2001

Long-term maintenance of channel distribution in a central pattern generator neuron by neuromodulatory inputs revealed by decentralization in organ culture.

Organotypic cultures of the lobster (Homarus gammarus) stomatogastric nervous system (STNS) were used to assess changes in membrane properties of neurons of the pyloric motor pattern-generating network in the long-term absence of neuromodulatory inputs to the stomatogastric ganglion (STG). Specifically, we investigated decentralization-induced changes in the distribution and density of the transient outward current, I(A), which is encoded within the STG by the shal gene and plays an important role in shaping rhythmic bursting of pyloric neurons. Using an antibody against lobster shal K(+) channels, we found shal immunoreactivity in the membranes of neuritic processes, but not somata, of STG neurons in 5 d cultured STNS with intact modulatory inputs. However, in 5 d decentralized STG, shal immunoreactivity was still seen in primary neurites but was likewise present in a subset of STG somata. Among the neurons displaying this altered shal localization was the pyloric dilator (PD) neuron, which remained rhythmically active in 5 d decentralized STG. Two-electrode voltage clamp was used to compare I(A) in synaptically isolated PD neurons in long-term decentralized STG and nondecentralized controls. Although the voltage dependence and kinetics of I(A) changed little with decentralization, the maximal conductance of I(A) in PD neurons increased by 43.4%. This increase was consistent with the decentralization-induced increase in shal protein expression, indicating an alteration in the density and distribution of functional A-channels. Our results suggest that, in addition to the short-term regulation of network function, modulatory inputs may also play a role, either directly or indirectly, in controlling channel number and distribution, thereby maintaining the biophysical character of neuronal targets on a long-term basis.

Animals↗
PubMed2000

Sleep-related erections in vegetative state patients.

STUDY OBJECTIVES: To determine whether sleep-related erections occur in vegetative state and if so, to investigate their relationship with rapid eye movement (REM) sleep. DESIGN: N/A. SETTING: Major rehabilitation hospital. PATIENTS: Nine male patients in vegetative state aged 17-40 years. INTERVENTIONS: Continuous 24-hour polysomnographic recordings including penile circumferencial changes. MEASUREMENTS AND RESULTS: Sleep-related erection episodes (SREe's) were noted in all nine patients, ranging in number from 1-7/24 hr (average 4.4+2.4) and lasting 6 to 50 min (average 22.0+5.7 min). The number of REM periods (REMp's) ranged from 4-11 (average 6.6+2.5) and lasted for 1.0 to 44.0 min (average 16.0+6.6 min). Ninety-five percent of the SREe's recorded were associated with REMp's, usually (76.3%) appearing simultaneously with the REMp or soon thereafter; 64.6% of the REMp's were associated with SRE's. For both the nocturnal and diurnal periods, there were more REMp's with SREe's than without, and the REMp's associated with SREe's were of longer duration (by 25.5% and 28.4%, respectively). There were no statistically significant differences for any of the REMp or SREe parameters between the recovered and nonrecovered patients. CONCLUSIONS: The sleep-related erection characteristics of patients in vegetative state are similar to those of normal individuals. These findings may have implications for the assessment of the reorganization of REM sleep during recovery from vegetative state and may further help in our understanding of the pathophysiology of vegetative state. More studies are needed in larger groups of patients.

Adolescent↗
PubMed2000

Comparative analysis of dendritic architecture of identified neurons using the Hausdorff distance metric.

Dendritic trees often are complex, three-dimensional structures. Comparative morphologic studies have not yet provided a reliable measure to analyze and compare the geometry of different dendritic trees. Therefore, it is important to develop quantitative methods for analyzing the three-dimensional geometry of these complex trees. The authors developed a comparison measure based on the Hausdorff distance for comparing quantitatively the three-dimensional structure of different neurons. This algorithm was implemented and incorporated into a new software package that the authors developed called NeuroComp. The authors tested this algorithm to study the variability in the three-dimensional structure of identified central neurons as well as measuring the structural differences between homologue neurons. They took advantage of the uniform dendritic morphology of identified interneurons of an insect, the giant interneurons of the cockroach. More specifically, after establishing a morphometric data base of these neurons, the authors found that the algorithm is a reliable tool for distinguishing between dendritic trees of different neurons, whereas conventional metric analysis often is inadequate. The authors propose to use this method as a quantitative tool for the investigation of the effects of various experimental paradigms on three-dimensional dendritic architecture.

Algorithms↗
PubMed2000

Combining laser scanning confocal microscopy and electron microscopy to determine sites of synaptic contact between two identified neurons.

Here we report a double labelling method for correlative confocal and electron microscopy (EM) which allows selective characterisation of structural relationships between two single identified neurons in the same preparation. Using the lobster stomatogastric nervous system, we labelled pairs of identified, synaptically-connected neurons by intracellular injection of Lucifer Yellow (LY) in one neuron and a mixture of Rhodamine (Rdh) and Horseradish Peroxidase (HRP) in its partner. First, whole-mounts of LY- and Rdh-stained neurons were visualized using laser scanning confocal microscopy (LSCM) in order to isolate neuropilar regions of possible synaptic contact. Second, after conventional treatment for electron microscopy (LY was revealed with immunogold and HRP with DAB), areas of close appositions were viewed in EM. This technique allowed us to determine all the regions of close contact between two cells, and then to use electron microscopy to determine the presence or absence of synaptic contact within each of these restricted areas. These techniques enabled us to show that there were few areas of apposition and that only an extremely small proportion of these areas was in fact regions of synaptic contact between the two labelled neurons.

Animals↗
PubMed2000

Chronic urticaria in children: expanding the "autoimmune kaleidoscope".

Most cases of chronic urticaria (CU) are considered idiopathic. It has recently been accepted that autoimmunity plays a critical role in the pathogenesis of CU in some of these patients. Although urticaria is common in the pediatric population, the knowledge regarding CU-associated autoimmunity is very limited. We describe the association of CU with a wide spectrum of clinical and laboratory autoimmune disorders in 2 children and emphasize the concept that CU is another manifestation of the "autoimmune kaleidoscope."

Adolescent↗
PubMed1998

Morbidity differences by occupational class among men in seven European countries: an application of the Erikson-Goldthorpe social class scheme.

BACKGROUND: This paper describes morbidity differences according to occupational class among men from France, Switzerland, (West) Germany, Great Britain, the Netherlands, Denmark, and Sweden. METHODS: Data were obtained from national health interview surveys or similar surveys between 1986 and 1992. Four morbidity indicators were included. For each country, individual-level data on occupation were recorded according to one standard occupational class scheme: the Erikson-Goldthorpe social class scheme. To describe the pattern of morbidity by occupational class, odds ratios (OR) were calculated for each class using the average of the population as a reference. The size of morbidity differences was summarized by the OR of two broad hierarchical classes. All OR were age-adjusted. RESULTS: For all countries, a lower than average prevalence of morbidity was found for higher and lower administrators and professionals as well as for routine nonmanual workers, whereas a higher than average prevalence was found for skilled and unskilled manual workers and agricultural workers. Self-employed men were in general healthier than the average population. The relative health of farmers differed between countries. The morbidity difference between manual workers and the class of administrators and professionals was approximately equally large in all countries. Consistently larger inequality estimates, with no or slightly overlapping confidence intervals, were only found for Sweden in comparison with Germany. CONCLUSIONS: Thanks to the use of a common social class scheme in each country, a high degree of comparability was achieved. The results suggest that morbidity differences according to occupational class among men are very similar between different European countries.

Adult↗
PubMed1998

Differences in self reported morbidity by educational level: a comparison of 11 western European countries.

STUDY OBJECTIVE: To assess whether there are variations between 11 Western European countries with respect to the size of differences in self reported morbidity between people with high and low educational levels. DESIGN AND METHODS: National representative data on morbidity by educational level were obtained from health interview surveys, level of living surveys or other similar surveys carried out between 1985 and 1993. Four morbidity indicators were included and a considerable effort was made to maximise the comparability of these indicators. A standardised scheme of educational levels was applied to each survey. The study included men and women aged 25 to 69 years. The size of morbidity differences was measured by means of the regression based Relative Index of Inequality. MAIN RESULTS: The size of inequalities in health was found to vary between countries. In general, there was a tendency for inequalities to be relatively large in Sweden, Norway, and Denmark and to be relatively small in Spain, Switzerland, and West Germany. Intermediate positions were observed for Finland, Great Britain, France, and Italy. The position of the Netherlands strongly varied according to sex: relatively large inequalities were found for men whereas relatively small inequalities were found for women. The relative position of some countries, for example, West Germany, varied according to the morbidity indicator. CONCLUSIONS: Because of a number of unresolved problems with the precision and the international comparability of the data, the margins of uncertainty for the inequality estimates are somewhat wide. However, these problems are unlikely to explain the overall pattern. It is remarkable that health inequalities are not necessarily smaller in countries with more egalitarian policies such as the Netherlands and the Scandinavian countries. Possible explanations are discussed.

Adult↗
PubMed1997

Independent coding of wind direction in cockroach giant interneurons.

Independent coding of wind direction in cockroach giant interneurons. J. Neurophysiol. 78: 2655-2661, 1997. In this study we examined the possible role of cell-to-cell interactions in the localization processing of a wind stimulus by the cockroach cercal system. Such sensory processing is performed primarily by pairs of giant interneurons (GIs), a group of highly directional cells. We have studied possible interactions among these GIs by comparing the wind sensitivity of a given GI before and after removing another GI with the use of photoablation. Testing various combinations of GI pairs did not reveal any suprathreshold interactions. This was true for all unilateral GI pairs on the left or right side as well as all the bilateral GI pairs (left and right homologues). Those experiments in which we were able to measure synaptic activity did not reveal subthreshold interactions between the GIs either. We conclude that the GIs code independently for a given wind direction without local GI-GI interactions. We discuss the possible implications of the absence of local interactions on information transfer in the first station of the escape circuit.

Abdomen↗
PubMed1997

[Recourse to care and morbidity of the homeless in the Paris district].

The disparities of access to care and morbidity according to different socio-economic characteristics are highlighted over about thirty years; what is the situation with regard to the homeless, the least provided for, who in some sense lie at the limits of the social scale? We present data on hospitalizations, ambulatory care and the morbidity declared by the homeless revealed in the INED survey of February-March 1995 in the Paris region. We tried to compare hospitalizations and physician care of the homeless with the population of "ordinary households" in the same region on the basis of different statistical sources. Hospitalizations are considerably more numerous in this group than in the rest of the population which indicates that the homeless are more exposed to diseases and accidents; on the other hand, taking into account any possible errors of observation, the homeless and the general population seem to have the same rate of recourse to outpatient doctor treatment. Is this also the case for complementary examinations, biological tests and medical imagery?

Demography↗
PubMed1996

[Can past developments foresee the grand picture of the 21st health care system: reversal of trends and stability?].

Social and economic forecasting in the health sector in France is particularly uncertain since most indicators have reversed their trends: transfers among health care structures (ambulatory care/outpatient care), prices, financing. The growth rate of global expense is diminishing and seems to be tending towards an asymptote of unknown level. The higher increase of health care among the elderly indicates a better correspondence between health care and morbidity, however, economic and social disparities, while they decreased from 1960 to 1980, have grown since. The improvement of health (life expectancy, invalidity, disability) is accompanied by an increase in the amount of disease. Finally, although the freedom of policy-makers is limited, their firmly stated will to modify the rules increases the uncertainty of the future of health care.

Adolescent↗
PubMed1996

In situ visualization and photoablation of individual neurons using a low cost fiber optic based system.

This paper describes a low-cost system for in situ visualization and photoablation of single neurons. The system includes a fiber optics light source equipped with a filter port, a blue excitation filter and a yellow barrier filter, and a light guide which terminates with a focusing lens. This system is inexpensive, easy to use, and requires minimal maintenance. Given its price, this system is readily accessible and has the potential of becoming standard equipment for in situ visualization and killing of individual neurons.

Action Potentials↗
PubMed1989

Hospital use in France and the United States.

This report presents national statistics on hospital use from the U.S. National Hospital Discharge Survey conducted by the National Center for Health Statistics and the national survey of hospitalization conducted by CREDES, Centre de Recherche d'Etude et de Documentation en Economie de la Santé, previously the Medical Economics Division of CREDOC. The use statistics compared between the two countries include rates and percent distributions of discharges and days of care and average lengths of stay. These statistics are shown by sex, age, diagnostic category, and other hospital and patient characteristics. The similarities and differences between the two countries in population characteristics, causes of death, health care systems, and hospital systems are also described.

Adolescent↗