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Biomedical subjects

S Sandor

Publications and source records attributed to S Sandor.

At least 19 recordsLinked to original sources
PubMed1997

Surface-based labeling of cortical anatomy using a deformable atlas.

We describe a computerized method to automatically find and label the cortical surface in three-dimensional (3-D) magnetic resonance (MR) brain images. The approach we take is to model a prelabeled brain atlas as a physical object and give it elastic properties, allowing it to warp itself onto regions in a preprocessed image. Preprocessing consists of boundary-finding and a morphological procedure which automatically extracts the brain and sulci from an MR image and provides a smoothed representation of the brain surface to which the deformable model can rapidly converge. Our deformable models are energy-minimizing elastic surfaces that can accurately locate image features. The models are parameterized with 3-D bicubic B-spline surfaces. We design the energy function such that cortical fissure (sulci) points on the model are attracted to fissure points on the image and the remaining model points are attracted to the brain surface. A conjugate gradient method minimizes the energy function, allowing the model to automatically converge to the smoothed brain surface. Finally, labels are propagated from the deformed atlas onto the high-resolution brain surface.

Algorithms↗
PubMed1988

Experimental alcohol blastopathy.

Experimental data are presented with respect to "experimental alcohol blastopathy" performed in our laboratory. As in our interpretation the notion of blastopathy involves both pathological changes during preimplantation development due to previous, preconceptional or preimplantation influences and later, pre- or postnatal effects induced by factors active during the preimplantation period, up to now the following experimental models were applied (on rats and mice): chronic and acute maternal, biparental or paternal ethanol alcoholization; preimplantation treatment with acetaldehyde or disulfiram followed by ethanol administration; acute ethanol intoxication before implantation on the background of chronic maternal ethanol intake; chronic maternal intake of various beverages. The main components of experimental alcohol blastopathy detected (by using a complex control methodology) were: pathological changes during the preimplantation developmental stages (lower mean number of embryos/animal, retardation of development, lowered migration rate of the embryos from the oviduct to the uterus, higher number of pathological morphological features), delayed implantation, disturbances of the early postimplantation development, retarded late foetal and placental growth. The effect of ethanol may be direct (ethanol being detectable in the oviductal and uterine fluid after both acute and chronic alcoholization) or indirect, via changes of the maternal macro- or microenvironment. The increase of the maternal blood acetaldehyde level may contribute to the appearance of alcohol blastopathy. Chronic beer and wine intake and acute intoxication with cognac suggest - up to now - the enhancing effect of beverage congeners. The noxious effect of acute ethanol intoxication superposed to chronic alcoholization is more marked that the separate effect of the two kinds of treatment. The chronic ethanol intake of fertilizing males (in mice) leads, both in the case of treated or untreated females, to lowered fertilization efficiency, to retardation of development (not occurring in the experimental model with chronic alcoholization of females) and to an enhanced increase of the number of pathological features. The cytogenetic control of preimplantation embryos (after chronic, acute or combined treatment with ethanol) does not reveal significant chromosomal changes. A possible alcohol blastopathy in humans must be taken into account (i.e. a noxious effect during the very early period of pregnancy when it is ignored).

Animals↗
PubMed1983

Decrease of red blood cell filterability seen in intensive care. II. Red blood cell crenelation "in vivo" as morphological evidence of increased red blood cell viscosity in low flow states.

We have reported the finding of numerous spiculed erythrocytes in blood stored for 15-21 days with acid citrate dextrose, drawing attention to the possible decrease of stored red cell deformability because of the decrease of the surface to volume ratio. The presence of anisotropy with crenated spheres, equivalent to the internal crystallization of hemoglobin, is closely related to these altered red cell parameters. The increase of erythrocyte filtration time in blood stored with acid citrate dextrose correlated well with the duration of storage up to the 21st day, r = 0.74 greater than 3 Sr, y = 1.104x + 1.853, n = 47, as well as with the increase of the proportion of crenated red cells. Using higher magnification (X700-1000) of the microcirculation in the great omentum of shocked dogs, crenated spheres could be seen within the arterioles, venules and capillaries; during refractory shock, nearly all the red cells became crenated spheres. The observation of echinocytes "in vivo" is a morphological proof of the damage to deformability of normal red blood cells in low flow states.

Animals↗
PubMedDate not supplied

Dyes as teratogens.

The main fats and problems of the role of dyes in prenatal pathology are reviewed. The first section deals with the practical aspects related to teratological screening of industrial dyes (including also the results obtained in this laboratory). In the second section, various aspects of azo-dye teratogenesis are largely discussed, including also the experimental contributions of this laboratory. Concluding remarks are made with respect to the importance and to the perspectives of this field of research.

Animals↗
PubMedDate not supplied

A new experimental model of overgrowth and consecutive exencephaly.

By intraamniotic injection of a.d. diluted rat or rabbit blood plasma in 3-day chick embryos overgrowth and consecutive cranioschisis and exencephaly may be induced. Control experiments exclude colloid-osmotic mechanism. Morphological changes suggest an early general disturbance of brain wall morphogenesis and differentiation.

Animals↗
PubMedDate not supplied

Contributions to the study of bisazo dye(s) induced eye anomalies in rats.

Eye anomalies were studied in embryos and foetuses of pregnant Wistar albino rats injected i.p. on day 9 of pregnancy with trypan blue (8-15 mg/100 g) and Niagara sky blue 6B (10-15 mg/100 g). Specimens were obtained by killing or by repeated surgical interventions between the 12th and 20th day of pregnancy. Microscopical changes were recorded in 170 embryos and foetuses of the experimental series and in 50 control specimens. Anophthalmia nad microthalmia (of various degrees) were the main anomalies induced by both dyes used. Other anomalies, less frequent, involved the whole eye or one or more eye components. No degenerative and necrotic changes the whole eye or one or more eye components. No degenerative and necrotic changes were recorded and no features attesting the vascular origin of malformations could be found. The persistence of eye appendages even in the total absence of any eye rudiment was constantly observed. Control specimens showed no microscopical changes of the developing eye. Some problems concerning possible pathogenic pathways are discussed.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Researches on the formation of axial organs in the chick embryo. IX. On the development of somites in axial-paraaxial segments explanted to the zona pellucida.

Axial-paraaxial segments (neural tube, chorda, unilateral meso- and endoderm) excized from explanted 36--40-hour-incubated chick embryos at the level of unsegmented mesoderm, after removal of the ectoderm, were grafted onto subectodermal pockets of the zona pellucida. Under these conditions somites develop and differentiate normally. Paraaxial segments (unilateral meso- and endoderm) grafted under the same conditions show (retarded) somitogenesis only in 15% of the cases. Pure paraaxial unsegmented mesoderm grafted under the same conditions develops somites in 14% of the cases. Since in situ, the removal of the axial organs and of the endo- and ectoderm does not inhibit somitogenesis, the above-mentioned results prove that under conditions of grafting, some additionary "factors of realization" necessary for normal somitogenesis are lacking.

Animals↗
PubMedDate not supplied

Contributions to the transfer of preimplantation molse embryos into "foster-mothers".

A new method for the transfer of preimplantation stages in mice has been developed by using as recipient the "pregnant empty uterus" obtained by ligature at the utero-oviductal junction. Results obtained with several combinations between Wh, CBAT6T6, C57Bl6 strains varied according to transfer media and strain combination, the best percentage of taking being under the level of those reported by other authors. By using transfer within the RAP strain, taking (controlled at 14 days of pregnancy) was similar to the best results generally obtained by the surgical transfer method. The advantages offered by the transfer method are briefly discussed.

Animals↗
PubMedDate not supplied

6-Aminonicotinamide-induced eye defects in rats.

The pathological changes and structural anomalies induced by 6-aminonicotinamide (6-AN) in the developing eye were studied in rats (Wistar and hooded randombred strain). The substance was administered in aqueous solution intraperitoneally (4 mg/kg on day 9--10 of pregnancy: 5 mg/kg on day 11 of pregnancy; 8 mg/kg on day 13--17 of pregnancy) and in physiological saline intraamniotically (0.01 ml of a 1% solution in physiological saline on day 15 of pregnancy). Embryos and foetuses from experimental series and from untreated control series were macro- and microscopically examined on day 10--20 of pregnancy. Control foetuses from mothers injected with distilled water on day 9--17 of pregnancy were examined on day 20 of pregnancy. The pathological changes and structural anomalies detected at successive developmental stages are presented. They reveal an obvious phase specificity and attest that the same substance may act through both of the main teratogenic pathways hypothetically put forward by Menkes et al. (1970). Based upon the present findings (and some previous results obtained in experiments with bisazo dyes) a working hypothesis is tentatively presented, as to the possible determination of the uni- or/and bilateral distribution of chemically induced developmental defects. In connection with some reversible or transitory pathological changes the role of recovery in teratogenesis is pointed out.

6-Aminonicotinamide↗
PubMedDate not supplied

On the prenatal noxious effects of trypan blue and of a related azo dye.

Since 1948 trypan blue has been a well-known and extensively used experimental teratogen, belonging to the group of azo dyes. Chemically, trypan blue consists of a biphenyl molecule (0-tolidine or benzidine) combined by means of azo linkages with two molecules of a substituted naphthalene. Between 1987-89 the effect of the replacement of the biphenyl molecule by a molecule of p,p'-diaminobenzanilide upon the prenatal noxious action of trypan blue has been controlled. Investigations were carried out on three species: chick embryos, albino rats and albino mice. In the species used, the replacement annihilates the teratogenic properties of the dye, with the persistence of some embryotoxic effects. On the other hand, the control of o-tolidine and of p,p'-diaminobenzanilide revealed that no one had teratogenic properties (only some embryotoxic effect, more marked in the case of o-tolidine). It results that the teratogenic action of trypan blue cannot be attributed to the o-tolidine molecule proper but to an effect which results (in a for the moment unknown manner) from its combination with the other parts of the dye molecule.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Homeostasis changes induced by the action of ethanol on the materno-fetal complex in rats. V. Late fetal effects of acute intoxication during the preimplantation period.

The late fetal effect of ethanol administered during the preimplantation period (in acute experiment) was investigated. Ethanol was injected i.v. (33.16% v/v in a.d., 4.80 ml/kg b.w.) to pregnant female rats on day 2 and 4 of pregnancy. Some effects concerning biochemical and morphological homeostasis on at-term fetuses (day 20 of pregnancy) were studied. Data obtained were compared with those of the control group. Biochemical investigation performed on hepatic DNA and on some serum metabolites revealed the following statistically non-significant changes: the increase of fetal hepatic DNA; the increase of total protein determined from pooled fetal serum of the whole litters; hypoalbuminemy and hyperglobulinemy; hypo-alpha 1-globulinemy and hyper-alpha 2-, beta-, gamma-globulinemy; the increase of total lipids, decrease of cholesterol; increase of uric acid and urea. In the amniotic fluid the following statistically non-significant values were found: increase of proteins, lipids, uric acid and urea content and decrease of cholesterol. Ponderal somatometry evidenced a statistically significant decrease of fetal and placental wet weight. The changes found show that--in our experimental conditions--the i.v. administration of ethanol during the preimplantation period does not significantly influence the late, fetal biochemical values and induces a significant lowering of fetal and placental wet weight and a significant increase of late fetal mortality.

Animals↗