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Biomedical subjects

A Fleischer

Publications and source records attributed to A Fleischer.

At least 19 recordsLinked to original sources
PubMed2003

Calibration of the viscometric glucose sensor before its use in physiological liquids--compensation for the colloid-osmotic effect.

The function of the recently described viscometric affinity sensor (VAS), which measures glucose due to its strong effect on the viscosity of a sensitive liquid containing Concanavalin A (ConA) and dextran, was analysed for osmotic and colloid-osmotic effects on the glucose reading. The suction of low- and high-molecular weight osmotica on the membrane of the microdialysis fibre was measured using a membrane osmometer built from the microdialysis probe of the VAS. The reduction of the sensor read-out in blood plasma can be completely explained by a change in small osmotic volume fluxes through the dialysis membrane, which affect the ConA concentration and the viscosity after the flow of the sensitive liquid through the dialysis probe. The measuring error could be prevented by the presence of the polyethylene glycol 6000 at an isotonic concentration in the glucose standard solutions used for sensor calibration.

Biosensing Techniques↗
PubMed2001

The association of Aiolos transcription factor and Bcl-xL is involved in the control of apoptosis.

We have analyzed the mechanism implicated in the control of the anti-apoptotic role of Bcl-xL. We show that IL-4 deprivation induces apoptosis, but does not modulate Bcl-xL expression. Because Bcl-xL does not promote cell survival in the absence of IL-4, we investigate the mechanism by which Bcl-xL was unable to inhibit apoptosis. Using yeast two-hybrid system, coimmunoprecipitation, and indirect immunofluorescence techniques, we found that Bcl-xL interacts with the transcription factor Aiolos in IL-4-stimulated cells, increasing upon IL-4 deprivation. IL-4 does not promote translocation of Aiolos or Bcl-xL, but induces tyrosine phosphorylation of Aiolos, which is required for dissociation from Bcl-xL. Transfection experiments confirm that cells overexpressing Bcl-xL are able to prevent apoptosis in the absence of IL-4. On the contrary, cells that overexpress Bcl-xL and Aiolos are unable to block apoptosis in the absence of IL-4. We propose a model for the regulation of the Bcl-xL anti-apoptotic role via Aiolos.

Animals↗
PubMed2001

Trisomy 8 as sole karyotypic aberration in an ovarian metastasizing Sertoli-Leydig cell tumor.

Sertoli-Leydig cell tumors (SLCTs) represent a rare group of sex-cord stromal tumors of the ovary of unknown pathogenesis. We report a SLCT of intermediate differentiation with peritoneal recurrence and lymph node metastasis 12 months after removal, including cytogenetic analysis by comparative genomic hybridization and fluorescence in situ hybridization, which showed trisomy 8 as sole unbalanced karyotypic aberration. Our results provide evidence that a simple numeric chromosomal abnormality in SLCT may be associated with a malignant phenotype and suggest that the molecular pathogenesis of SLCT may be different from ovarian granulosa-stromal cell tumors.

Adolescent↗
PubMed2001

[Normal sense of smell in Kallmann syndrome. A case report].

BACKGROUND: Kallmann's syndrome (KS) was first mentioned in 1944 as an association of anosmia and hypogonadotropic hypogonadism. Causes are multiple genetic defects the most common of which is the x-linked KS appearing mostly in men. However, autosomal dominant and autosomal recessive forms have also been described. PATIENT: We present a case of KS with normosmia (male, 39 years of age). All symptoms of hypogonadotropic hypogonadism were present. RESULTS: Psychophysical olfactory testing revealed left-sided anosmia with right-sided normosmia which was confirmed by electrophysiological measures of olfactory function. Magnetic resonance imaging indicated aplasia of the left olfactory tract and bulb, whereas the right-sided structures appeared to be normal. CONCLUSIONS: As indicated in this case with lateralized anosmia and contralateral normosmia, overall olfactory function strongly depends on the "best" nostril. Therefore, in many clinical situations, lateralized olfactory testing appears to be extremely important.

Adult↗
PubMed2001

Detection of invasion-related chromosomal changes in highly and weakly invasive melanoma cell clones by a modified comparative genomic hybridization approach.

Invasion is a key step in the systemic spread of tumour cells. The aim of this study was to investigate whether specific chromosomal aberrations in melanoma occur during acquisition of a strongly invasive phenotype. We previously selected highly and weakly invasive cell clones from the human melanoma cell line Mel Im. Both cell clones retained a stable phenotype over more than 40 passages, revealing a five-fold difference in their invasive potential in vitro. Direct comparative genomic hybridization (CGH) (modified CGH) of the two cell clones was used as a powerful tool to screen for different chromosomal aberrations in both clones. Standard CGH and fluorescence in situ hybridization (FISH) was performed to verify the results of this improved technique. In general, the CGH pattern showed a high degree of identity consistent with the fact that the cell lines represent subclones of the same cell line. However, a few defined changes between the two cell clones were observed, including loss of 1q21-qter, 4q, 11p14-pter, 19q and 20p in the highly invasive cell clone. Two of the regions (1q and 11p) have already been suggested to be involved in melanoma progression, whereas changes in the others have not been detected before. In summary, our direct CGH approach proved to be suitable for fast and direct comparison of two cell types and allowed the identification of two known and three novel chromosomal changes involved in the acquisition of a strongly invasive melanoma cell phenotype.

Cell Line↗
PubMed2000

Acute stress disorder symptomatology during hospitalization for pediatric injury.

OBJECTIVE: To examine and identify predictors of acute stress disorder (ASD) and ASD symptomatology (ASDS) in children hospitalized for injuries. METHOD: Fifty-four youths were assessed while hospitalized for injuries. Dependent variables were parent and nurse ratings of children's ASDS. Independent variables included children's prior trauma exposure and behavior problems, injury severity and permanence, brain injury, injury or death to family/friend(s), parental distress, and child reports of the injury/hospitalization experience as meeting criterion A for ASD. RESULTS: A total of 92.6% of children felt the current experience met criterion A, compared with 64.8% of parents. According to parent questionnaires, 4 subjects (7.4%) met DSM-IV criteria for ASD while another 12 (22.2%) had clinically significant but subsyndromal ASDS. Children's ASDS, as reported by parents, correlated highly with parental distress and ratings of children's prior psychopathology, and modestly with injury severity and family/friend(s) injured or killed. Nurses' ratings of children's ASDS correlated strictly with injury- and accident-related variables, and not with parent ratings of children's ASDS. CONCLUSIONS: Children perceive injuries and hospitalizations as stressful. ASDS is widely though divergently reported by parents and nurses in children hospitalized for injury. Parental distress, children's prior psychopathology, and injury-related factors may be useful predictors of children's postinjury ASDS.

Acute Disease↗
PubMed2000

Predicting posttraumatic stress after hospitalization for pediatric injury.

OBJECTIVE: To determine the prevalence and predictors of posttraumatic stress disorder (PTSD) in children after hospitalizations for accidental injuries. METHOD: Forty-eight children (aged 7-17 years) and their parents were assessed during hospitalization with measures of children's prior traumatization, prior psychopathology, injury severity, parental acute distress, and child acute distress. At outpatient follow-up at least 1 month later, children were evaluated for current PTSD diagnosis and PTSD symptomatology (PTSDS) by a child structured interview and for PTSDS by a parent questionnaire. RESULTS: A total of 12.5% had the full syndrome of PTSD at follow-up, and an additional 16.7% had partial (sub-syndromal) PTSD. Full PTSD was associated with a higher level of prior psychopathology, higher parental acute distress, and higher rates of prior sexual abuse, compared with partial or no PTSD. Prior psychopathology, parental distress, and, to a lesser extent, children's acute distress as reported by parents and breadth of prior traumatization, predicted subsequent PTSDS. CONCLUSIONS: Full or partial PTSD is relatively common in youths 1 month or more after hospitalization for injuries. Parents' acute distress as well as children's prior psychopathology, prior traumatization, and acute distress may be useful predictors of such injured children's subsequent PTSD or PTSDS.

Adolescent↗
PubMed2000

Child maltreatment, other trauma exposure, and posttraumatic symptomatology among children with oppositional defiant and attention deficit hyperactivity disorders.

Consecutive child psychiatric outpatient admissions with disruptive behavior or adjustment disorders were assessed by validated instruments for trauma exposure and posttraumatic stress disorder (PTSD) symptoms and other psychopathology. Four reliably diagnosed groups were defined in a retrospective case-control design: Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD), comorbid ADHD-ODD, and adjustment disorder controls. ODD and (although to a lesser extent) ADHD were associated with a history of physical or sexual maltreatment. PTSD symptoms were most severe if (a) ADHD and maltreatment co-occurred or (b) ODD and accident/illness trauma co-occurred. The association between ODD and PTSD Criterion D (hyperarousal/hypervigilance) symptoms remained after controlling for overlapping symptoms, but the association of ADHD with PTSD symptoms was largely due to an overlapping symptom. These findings suggest that screening for maltreatment, other trauma, and PTSD symptoms may enhance prevention, treatment, and research concerning childhood disruptive behavior disorders.

Adjustment Disorders↗
PubMed1999

The Pore Size of Non-Graminaceous Plant Cell Walls Is Rapidly Decreased by Borate Ester Cross-Linking of the Pectic Polysaccharide Rhamnogalacturonan II.

The walls of suspension-cultured Chenopodium album L. cells grown continually for more than 1 year on B-deficient medium contained monomeric rhamnogalacturonan II (mRG-II) but not the borate ester cross-linked RG II dimer (dRG-II-B). The walls of these cells had an increased size limit for dextran permeation, which is a measure of wall pore size. Adding boric acid to growing B-deficient cells resulted in B binding to the wall, the formation of dRG-II-B from mRG-II, and a reduction in wall pore size within 10 min. The wall pore size of denatured B-grown cells was increased by treatment at pH </= 2.0 or by treatment with Ca(2+)-chelating agents. The acid-mediated increase in wall pore size was prevented by boric acid alone at pH 2.0 and by boric acid together with Ca(2+), but not by Na(+) or Mg(2+) ions at pH 1.5. The Ca(2+)-chelator-mediated increase in pore size was partially reduced by boric acid. Our results suggest that B-mediated cross-linking of RG-II in the walls of living plant cells generates a pectin network with a decreased size exclusion limit for polymers. The formation, stability, and possible functions of a borate ester cross-linked pectic network in the primary walls of nongraminaceous plant cells are discussed.

Journal Article↗
PubMed1998

The boron requirement and cell wall properties of growing and stationary suspension-cultured chenopodium album L. cells

Suspension-cultured Chenopodium album L. cells are capable of continuous, long-term growth on a boron-deficient medium. Compared with cultures grown with boron, these cultures contained more enlarged and detached cells, had increased turbidity due to the rupture of a small number of cells, and contained cells with an increased cell wall pore size. These characteristics were reversed by the addition of boric acid (>/=7 &mgr;M) to the boron-deficient cells. C. album cells grown in the presence of 100 &mgr;M boric acid entered the stationary phase when they were not subcultured, and remained viable for at least 3 weeks. The transition from the growth phase to the stationary phase was accompanied by a decrease in the wall pore size. Cells grown without boric acid or with 7 &mgr;M boric acid were not able to reduce their wall pore size at the transition to the stationary phase. These cells could not be kept viable in the stationary phase, because they continued to expand and died as a result of wall rupture. The addition of 100 &mgr;M boric acid prevented wall rupture and the wall pore size was reduced to normal values. We conclude that boron is required to maintain the normal pore structure of the wall matrix and to mechanically stabilize the wall at growth termination.

Journal Article↗
PubMed1998

Prenatal diagnosis of low level trisomy 15 mosaicism: review of the literature.

Low level chromosome mosaicism found at amniocentesis is problematic for clinicians and patients. We report prenatal diagnosis of a fetus with a rare karyotype of 47,XX, + 15/46,XX. Second trimester amniocentesis was performed for advanced maternal age. Fetal ultrasound revealed a hypoplastic right ventricle and intrauterine growth retardation (IUGR). The rest of the fetal anatomy was within normal limits. A mosaic karyotype of 47,XX, + 15/46,XX was observed. The couple interrupted the pregnancy at 19 weeks by dilation and suction evacuation. Careful evaluation of multiple pieces of fetal parts and placenta revealed one abnormal finding: a single umbilical artery. Cytogenetic metaphase and fluorescent in situ hybridization (FISH) interphase analyses of cells from fetal lung, heart, placenta, and skin revealed the presence of the trisomic line in all tissues. Molecular analysis demonstrated that the origin of the extra chromosome 15 was maternal, the error most likely occurred in meiosis I and the diploid line was of biparental inheritance. This case report discusses the associated findings in this fetus and reviews the literature describing other cases of mosaic trisomy 15.

Amniocentesis↗
PubMed1998

Techniques of treatment of peritoneal endometriosis: the cavitational ultrasonic surgical aspirator.

The efficacy of medical therapy in endometriosis-associated infertility has been called into question. For decades, surgery has been used in the treatment of endometriosis. However, before the 1960s it consisted of either excision or hysterectomy and bilateral adnexectomy. Although controversy exists about whether laparotomy or operative laparoscopy is the more efTective therapeutic approach for endometriosis, the efficacy of surgery in reducing implants, relieving dysmenorrhea and pelvic pain, and improving fertility has been well-established.

Journal Article↗
PubMed1995

Genetic threshold hypothesis of neocortical spike-and-wave discharges in the rat: an animal model of petit mal epilepsy.

Neocortical high-voltage spike-and-wave discharges (HVS) in the rat are an animal model of petit mal epilepsy. Genetic analysis of total duration of HVS (s/12 hr) in reciprocal F1 and F2 hybrids of F344 and BN rats indicated that the phenotypic variability of HVS cannot be explained by a simple, monogenic Mendelian model. Biometrical analysis suggested the presence of additive, dominance, and sex-linked-epistatic effects, buffering maternal influence, and heterosis. High correlation was observed between average duration (s/episode) and frequency of occurrence of spike-and-wave episodes (n/12 hr) in parental and segregating generations, indicating that common genes affect both duration and frequency of the spike-and-wave pattern. We propose that both genetic and developmental-environmental factors control an underlying quantitative variable, which, above a certain threshold level, precipitates HVS discharges. These findings, together with the recent availability of rat DNA markers for total genome mapping, pave the way to the identification of genes that control the susceptibility of the brain to spike-and-wave discharges.

Action Potentials↗
PubMed1995

Prenatal diagnosis of congenital lipoid adrenal hyperplasia.

Congenital lipoid adrenal hyperplasia (lipoid CAH) is a rare genetic disorder of adrenal and gonadal steroidogenesis of unknown cause in which cholesterol cannot be converted to pregnenolone. As a result, affected individuals can make no steroid hormones, so that all affected newborns are phenotypic females, irrespective of karyotype. We studied two pregnancies in a family with two previously affected children by examining fetal karyotype, genital ultrasonography, and amniotic fluid steroid concentrations and by performing ACTH tests on family members. Prenatal diagnosis correctly identified both an unaffected XX fetus and an affected XY fetus. In the affected pregnancy, amniotic fluid concentrations of progesterone and pregnenolone were 30% and 50% of normal, respectively, but concentrations of 17 alpha-hydroxypregnenolone, 17 alpha-hydroxyprogesterone, cortisol, dehydroepiandrosterone, androstenedione, and estriol were either extremely low or undetectable, suggesting that these detected steroids were donated by maternal steroidogenesis. Fetal cord blood obtained at the termination of pregnancy showed very low concentrations of estrogens donated by the mother's circulation. Absent fetal steroidogenesis was confirmed by gas chromatography and mass spectrometry of both fetal and maternal serum. The responses of 10 different steroids to adrenal stimulation with ACTH in the obligately heterozygous parents were normal. Thus, unlike the case with other forms of CAH, heterozygosity cannot be determined by hormonal responses to provocative testing with ACTH. Immunocytochemistry and Western blotting showed that the affected placental tissue contained P450scc protein, confirming that P450scc is intact in these patients.

Adrenal Hyperplasia, Congenital↗
PubMed1994

Successful hematopoietic reconstitution with transplantation of erythrocyte-depleted allogeneic human umbilical cord blood cells in a child with leukemia.

Cord blood, a potent source of hematopoietic stem cells, has been shown to successfully reconstitute hematopoiesis following allogeneic transplantation in a variety of disorders. A major drawback of cord blood has been the risk of transfusion reactions in ABO blood group incompatibility and drastic reduction in the stem cell pool if the cord blood is manipulated to remove red cells prior to cryopreservation or after thawing. This report describes an erythrocyte depletion method employing 3% gelatin-induced erythrocyte sedimentation for the selective removal of red cells from cord blood. The red cell-depleted fraction was shown to be enriched in progenitor cells and in cells secreting hematopoietic cytokines interleukin 3, granulocyte/macrophage colony-stimulating factor, and interleukin 6; a major source for cytokines was from cord T cells. This preparative technique was employed to separate out red cells from cord blood of an infant delivered by cesarean section who had an 8-year-old sibling with leukemia. Histocompatibility testing of cord cells revealed complete matching with the patient. A cord cell transplant of cryopreserved and thawed cells consisting of 4 x 10(7) nucleated cells per kg was administered to the patient following myeloablative chemotherapy. The patient's quick hematologic recovery and 9-month disease-free period to date suggest that 3% gelatin separation of erythrocytes is a simple method that can be successfully used for transplanting cord cells for malignant/nonmalignant diseases.

ABO Blood-Group System↗