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Biomedical subjects

E Katz

Publications and source records attributed to E Katz.

At least 55 records · Page 3Linked to original sources
PubMed1999

Precipitation of an insoluble product on enzyme monolayer electrodes for biosensor applications: characterization by Faradaic impedance spectroscopy, cyclic voltammetry, and microgravimetric quartz crystal microbalance analyses.

Precipitation of an insoluble, insulating product on monolayer-functionalized electrodes enables the development of new electrochemical biosensors. Faradaic impedance spectroscopy and cyclic voltammetry are used to probe the electron-transfer resistance at the conductive support upon the accumulation of the insoluble product on the electrode surface. Similarly, microgravimetric quartz crystal microbalance, QCM, analyses were used to assay the formation of the precipitate on the electrode. A horseradish peroxidase, HRP, monolayer electrode is used to analyze H2O2 via the biocatalyzed oxidation of 4-chloro-1-naphthol (1) and the precipitation of the insoluble product (2). A bienzyme-layered electrode consisting of HRP and glucose oxidase, GOx, is used to sense glucose. Biocatalyzed oxidation of glucose by O2, in the presence of GOx, yields H2O2, and the generated hydrogen peroxide effects the formation of the insoluble product (2) in the presence of HRP. The insoluble product accumulated on the electrode, and the extent of the resulting electron-transfer resistance, correlated with the amounts of H2O2 or glucose, and appropriate calibration curves are extracted.

Biosensing Techniques↗
PubMed1999

The value of intravenous heme-albumin and plasmapheresis in reducing postoperative complications of orthotopic liver transplantation for erythropoietic protoporphyria.

Erythropoietic protoporphyria (EPP) is marked by a deficiency of ferrochelatase, which occurs in all cells and tissues, preventing effective conversion of proto porphyrin IX to heme and thereby blocking effective feedback inhibition of heme synthesis. The major source of the excess protoporphyrin is the bone marrow. Protoporphyrin IX may accumulate, with resultant toxicity chiefly of the marrow, skin, nervous system, and liver. Orthotopic liver transplantation (OLT) is, at present, the only adequate intervention for severe liver compromise secondary to protoporphyrin deposition, but it has been complicated by severe photosensitivity and polyneuropathy. Intravenous heme and plasmapheresis have been proposed but not previously reported as means to reduce the protoporphyrin burden before liver transplantation. We report a man with EPP who underwent preoperative heme-albumin administration and plasmaphereses that led to marked reductions in plasma and erythrocyte protoporphyrin levels. His OLT was uneventful, and he developed neither polyneuropathy nor exacerbation of photosensitivity.

Albumins↗
PubMed1999

Kinetics of formation of neutralizing antibodies against vaccinia virus following re-vaccination.

Administration of vaccinia immune globulin (VIG), derived from vaccinated healthy adult volunteers, is the treatment-of-choice for patients suffering from severe complications following smallpox vaccination. The present study was aimed to determine the time interval after vaccination, at which the highest titer of neutralizing antibodies is obtained. Ninety-nine 18-year-old soldiers, immunized with vaccinia virus at birth, participated in the study, 87 of whom had detectable antibodies against vaccinia virus prior to re-vaccination. Their initial average neutralizing antibodies titer (NT50) was 27. Fourteen days after re-vaccination the titer reached 152 and then dropped to 136, 119, 110 and 87 at 21, 30, 45 and 60 d, respectively. The titers of vaccinia antibodies induced in vaccinees without detectable antibodies at the start of the study, were significantly lower and the titers observed after re-vaccination were: 62, 56, 66, 38 and 34, at 14, 21, 30, 45 and 60 d, respectively. In an additional study, 65 volunteers vaccinated at birth and again at the age of 8 years old were re-vaccinated. Fourteen days later their NT50 was higher than those vaccinated only at birth. It can be concluded that bleeding of vaccinees 14 d following re-vaccination is the preferable time for the preparation of VIG.

Adolescent↗
PubMed1999

The alpha9 nicotinic acetylcholine receptor shares pharmacological properties with type A gamma-aminobutyric acid, glycine, and type 3 serotonin receptors.

In the present study, we provide evidence that the alpha9 nicotinic acetylcholine receptor (nAChR) shares pharmacological properties with members of the Cys-loop family of receptors. Thus, the type A gamma-aminobutyric acid receptor antagonist bicuculline, the glycinergic antagonist strychnine, and the type 3 serotonin receptor antagonist ICS-205,930 block ACh-evoked currents in alpha9-injected Xenopus laevis oocytes with the following rank order of potency: strychnine > ICS-205,930 > bicuculline. Block by antagonists was reflected in an increase in the acetylcholine (ACh) EC50 value, with no changes in agonist maximal response or Hill coefficient, which suggests a competitive type of block. Moreover, whereas neither gamma-aminobutyric acid nor glycine modified ACh-evoked currents, serotonin blocked responses to ACh in a concentration-dependent manner. The present results suggest that the alpha9 nAChR must conserve in its primary structure some residues responsible for ligand binding common to other Cys-loop receptors. In addition, it adds further evidence that the alpha9 nAChR and the cholinergic receptor present at the base of cochlear outer hair cells have similar pharmacological properties.

Acetylcholine↗
PubMed1999

Co-infection of acyclovir-resistant and acyclovir-sensitive herpes simplex type 2 virus strains in BS-C-1 cells.

Co-infection of BS-C-1 cells by the herpes simplex virus type 2 (HSV-2) Curtis strain with its acyclovir (ACV)-resistant mutant (HSV-2-ACV(R)), resulted in a severalfold increase in virus yield, as compared to a single infection. On the other hand, when two viruses (G strain and HSV-2-ACV(R)) belonging to different strains of HSV-2 were involved, their growth was significantly inhibited; the decrease in the titer of the second virus to infect the cells was greater when its infection took place at later times following infection by the first. This inhibition was not due to the shut-off of host cell protein synthesis caused by the first virus, since an HSV-2 mutant which is unable to inhibit the protein synthesis of the host cell was still capable of efficiently inhibiting the growth of the superinfecting virus.

Acyclovir↗
PubMed1999

Technologies to minimize blood transfusion in cardiac and orthopedic surgery. Results of a practice variation survey in nine countries. International Study of Peri-operative Transfusion (ISPOT) Investigators.

OBJECTIVES: Due to the discovery in the 1980s that blood transfusion can transmit HIV, there has been increased interest in technologies that reduce the amount of allogeneic blood used during and after surgery. These technologies include drugs (aprotinin, tranexamic acid, epsilon-aminocaproic acid, erythropoietin), devices (cell salvage), and techniques (acute hemodilution, predeposited autologous donation). The purpose of this study was to ascertain the degree of practice variation, if any, that exists for eight technologies in nine countries in orthopedic and cardiac surgery. METHODS: In each country, either all hospitals or a random sample of hospitals with medical/surgical beds were surveyed between 1995 and 1997. Two instruments were used. The first instrument was a postcard that asked recipients whether the technologies were currently being used in their hospital for orthopedic and/or cardiac surgery to reduce perioperative allogeneic transfusion. The second questionnaire elicited information regarding the degree of use both in qualitative and quantitative terms. Data were collected, entered, and analyzed in each country, with summary results submitted to the Canadian coordinating center on a standardized data collection form. RESULTS: Pharmaceuticals were generally used in a much smaller proportion of hospitals in orthopedic than in cardiac surgery. Aprotinin and tranexamic acid were the drugs most frequently used in cardiac surgery. Nonpharmacological technologies were used to a greater degree than drugs in orthopedic surgery, although there was wide variation among technologies and countries. Acute hemodilution and cell salvage were used in a greater proportion of hospitals for cardiac surgery than orthopedic surgery. CONCLUSIONS: The results of this survey indicate that there is considerable practice variation in the use of technologies to minimize exposure to perioperative allogeneic transfusion within and between countries.

Antifibrinolytic Agents↗
PubMed1998

Single-cell RT-PCR and functional characterization of Ca2+ channels in motoneurons of the rat facial nucleus.

Voltage-dependent Ca2+ channels are a major pathway for Ca2+ entry in neurons. We have studied the electrophysiological, pharmacological, and molecular properties of voltage-gated Ca2+ channels in motoneurons of the rat facial nucleus in slices of the brainstem. Most facial motoneurons express both low voltage-activated (LVA) and high voltage-activated (HVA) Ca2+ channel currents. The HVA current is composed of a number of pharmacologically separable components, including 30% of N-type and approximately 5% of L-type. Despite the dominating role of P-type Ca2+ channels in transmitter release at facial motoneuron terminals described in previous studies, these channels were not present in the cell body. Remarkably, most of the HVA current was carried through a new type of Ca2+ channel that is resistant to toxin and dihydropyridine block but distinct from the R-type currents described in other neurons. Using reverse transcription followed by PCR amplification (RT-PCR) with a powerful set of primers designed to amplify all HVA subtypes of the alpha1-subunit, we identified a highly heterogeneous expression pattern of Ca2+ channel alpha1-subunit mRNA in individual neurons consistent with the Ca2+ current components found in the cell bodies and axon terminals. We detected mRNA for alpha1A in 86% of neurons, alpha1B in 59%, alpha1C in 18%, alpha1D in 18%, and alpha1E in 59%. Either alpha1A or alpha1B mRNAs (or both) were present in all neurons, together with various other alpha1-subunit mRNAs. The most frequently occurring combination was alpha1A with alpha1B and alpha1E. Taken together, these results demonstrate that the Ca2+ channel pattern found in facial motoneurons is highly distinct from that found in other brainstem motoneurons.

Animals↗
PubMed1998

Fully integrated biocatalytic electrodes based on bioaffinity interactions.

Integrated bioelectrocatalytically active electrodes are assembled by the deposition of enzymes onto respective electrically contacted affinity matrices and further cross-linking of the enzyme monolayers. A catalyst-NAD(+)-dyad for the binding of the NAD(+)-dependent enzymes and cytochrome-like molecules for the binding of the heme-protein-dependent enzymes are used to construct integrated electrically contacted biocatalytic systems. NAD(+)-dependent lactate dehydrogenase (LDH) is assembled onto a pyrroloquinoline quinone-NAD+ monolayer. The redox-active monolayer is organized via covalent attachment of pyrroloquinoline quinone (PQQ) to a cystamine monolayer associated with a Au-electrode, followed by covalent linkage of N6-(2-aminoethyl)-NAD+ to the monolayer. The interface modified with the PQQ-NAD(+)-dyad provides temporary affinity binding for LDH and allows cross-linking of the enzyme monolayer. The cross-linked LDH is bioelectrocatalytically active towards oxidation of lactate. The bioelectrocatalyzed process involves the PQQ-mediated oxidation of the immobilized NADH. Integrated, electrically contacted bioelectrodes are produced by the affinity binding and further cross-linking of nitrate reductase (NR) (cytochrome-dependent, E.C. 1.9.6.1 from E. coli) or CoII-protoporphyrin IX reconstituted myoglobin (CoII-Mb) atop the microperoxidase-11 (MP-11) monolayer associated with a Au-electrode. The MP-11 monolayer provides an affinity interface for the temporary binding of the enzymes, that allows the cross-linkage of the enzyme molecules. The MP-11 assembly acts as electron transfer mediator for the reduction of the secondary enzyme layer. The integrated bioelectrodes consisting of NR and CoII-Mb show catalytic activities for NO3- reduction and acetylene-dicarboxylic acid hydrogenation, respectively. Two FeIII-protoporphyrin IX units are reconstituted into a four alpha-helix bundle de novo protein assembled as a monolayer on a Au-electrode. Vectorial electron transfer proceeds in the synthetic heme-protein monolayer. Cross-linking of an affinity complex generated between the FeIII-protoporphyrin IX reconstituted de novo protein monolayer and NR yields an integrated, electrically contacted enzyme electrode that stimulates the bioelectrocatalyzed reduction of nitrate.

Animals↗
PubMed1998

Endoscopic treatment of postoperative bronchopleural fistula: experience with 45 cases.

BACKGROUND: The value of bronchoscopic sealing of bronchopleural fistulas was studied retrospectively. METHODS: The cases of 45 patients seen between 1983 and 1996 with bronchopleural fistula after pneumonectomy (40 patients) or lobectomy (5 patients) were reviewed. Age, underlying disease, side, fistula size (millimeters) at initial bronchoscopy, survival (days) after endoscopic treatment, mode and number of endoscopic interventions, interval (days) between operation and fistula occurrence, and pathologic TNM stage in the case of malignancy were recorded. On the basis of the therapeutic outcome (cure, death, chronic empyema with closed fistula, or chronic empyema with open fistula) and the modality (successful sealing or bronchoscopic failure with subsequent surgical intervention), various groups were assessed and compared. RESULTS: Of 29 patients (64%) treated only endoscopically, 9 were cured. Seven patients had fistula closure, but persistent chronic empyema necessitated permanent drainage. In another 7 patients, the fistula remained open and also was controlled by permanent drainage. Six patients in this group died. The overall rate of fistula closure was 35.6% (16 patients), and recurrence occurred in 2 patients. Sixteen patients (35.6%) required surgical intervention because of increasing fistula size (8 patients), sepsis with refractory empyema (7), and fecal empyema (1 patient). Two patients in the surgical group died. Small fistulas (<3 mm) responded particularly well to primary endoscopic treatment. CONCLUSIONS: Bronchoscopic treatment of bronchopleural fistula appears an efficient alternative, especially when surgical intervention cannot be done because of the physical condition of the patient.

Adult↗
PubMed1998

Potential use of repeated fluorescence in situ hybridization in the same human blastomeres for preimplantation genetic diagnosis.

OBJECTIVE: To assess the feasibility of repeated fluorescence in situ hybridization (FISH) procedures in the same nucleus of a human blastomere. DESIGN: Three consecutive FISH procedures were performed in the same human blastomere by using direct label fluorescence CEP and WCP probes (Vysis). SETTING: Hospital-based private IVF program. PATIENT(S): Twenty-eight infertile couples who underwent conventional IVF in our center. INTERVENTION(S): Embryos from oocytes with three pronuclei after in vitro insemination were used in this study. MAIN OUTCOME MEASURE(S): The rates of nuclear loss, present signals, and absent signal were examined. RESULT(S): In group 1, the rates of presence of signals were 94% after the first FISH, 92% after the second FISH, and 88% after the third FISH. In group 2, the rates of presence of signals were 96% after the first FISH, 93% after the second FISH, and 87% after the third FISH. There was no statistically significant difference in the rates of nuclear loss, present signals, and absent signal between three consecutive FISH procedures and between CEP and WCP probes. CONCLUSION(S): Six or more chromosomes of a single blastomere may be examined with use of this repeated FISH procedure, which may be important for preimplantation genetic diagnosis.

Blastomeres↗
PubMed1998

Ultrarapid detection of sex chromosomes with the use of fluorescence in situ hybridization with direct label DNA probes in single human blastomeres, spermatozoa, amniocytes, and lymphocytes.

OBJECTIVE: To assess the ultrarapid fluorescence in situ hybridization (FISH) procedure with a 1-minute hybridization time for gender determination. DESIGN: Fluorescence in situ hybridization with direct label fluorescence DNA probes for chromosomes X and Y were tested with the use of different hybridization times and different cell types. SETTING: Hospital-based IVF program. INTERVENTION(S): The efficiency of the FISH procedure with different hybridization times was compared with the use of male lymphocytes. The same FISH procedure, but with only 1-minute hybridization, was carried out in human blastomeres, spermatozoa, uncultured amniocytes, male lymphocytes, and female lymphocytes. MAIN OUTCOME MEASURE(S): Percentages of nuclei with positive signals. RESULT(S): The percentages of nuclei with positive signals in lymphocytes with hybridization times of 1, 3, 4, 10, 30, and 45 minutes were 97%, 97%, 98%, 98%, 98%, and 98%, respectively. The percentages of nuclei with positive signals after FISH with a 1-minute hybridization time in single blastomeres, spermatozoa, amniocytes, male lymphocytes, and female lymphocytes were 94%, 96%, 96%, 98%, and 97%, respectively. CONCLUSION(S): Chromosomes X and Y of human blastomeres. spermatozoa, uncultured amniocytes, and lymphocytes can be detected rapidly with the use of this ultrarapid FISH procedure with a 1-minute hybridization time.

Amniotic Fluid↗
PubMed1998

A tetrazolium-based colorimetric assay for titration of neutralizing antibodies against vaccinia virus.

A colorimetric assay for titration of neutralizing antibodies against vaccinia virus was developed. The test is based on the ability of live cells in culture to reduce the yellow tetrazolium salt MTT (thiazolyl-blue), to its blue formazan derivative. Antisera from individuals vaccinated with vaccinia virus against smallpox were serially diluted, incubated with 100 plaque-forming units (PFU) of vaccinia virus for 1 hour at 37 degrees C, and then transferred to a 96-well plate containing monolayers of B-SC-1 cells. After incubation for 3 to 4 days at 37 degrees C, when more than 80% of the control infected cultures exhibited high degree of cytopathogenic effect, MTT was added. The absorbance of the formazan formed and extracted by dimethylsulfoxide was read at 492 nm by an automatic microplate spectrophotometer. A good correlation was found between the results obtained using this newly developed method and those of the plaque-reduction assay.

Antibodies, Viral↗
PubMed1998

Feasibility study of repeated fluorescent in-situ hybridization in the same human blastomeres for preimplantation genetic diagnosis.

In order to increase the number of chromosomes examined in each blastomere, we have developed a repeated fluorescent in-situ hybridization (FISH) procedure by which six or more chromosomes can be analysed per blastomere of a human embryo. Three consecutive FISH procedures with directly-labelled fluorescent Vysis DNA probes were carried out for examination of chromosomes X, Y, 11, 13, 18 and 21 in the same blastomeres (n = 126) and lymphocytes (n = 164). Based on the initial number of nuclei, the percentages of nuclear loss and presence of signals were 3 and 92% respectively in blastomeres; 6 and 91% respectively in lymphocytes after the first FISH; 7 and 87% respectively in blastomeres and 10 and 86% respectively in lymphocytes, after the second FISH. These percentages were 13 and 78% respectively in blastomeres and 14 and 81% respectively in lymphocytes after the third FISH. The FISH procedure was repeated successfully in a couple for preimplantation genetic diagnosis of chromosomal aneuploidies in biopsied blastomeres of their embryos in our clinic. In conclusion, it is feasible to carry out repeated FISH procedures in the same blastomeres. Six or more chromosomes of a single blastomere may be examined using this procedure.

Adult↗
PubMed1997

Immunogenicity of recombinant vaccinia viruses that display the HIV type 1 envelope glycoprotein on the surface of infectious virions.

A chimeric protein, consisting of the extracellular domain of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein attached to the transmembrane and cytoplasmic domains of the vaccinia virus B5R glycoprotein, is displayed on the surface of extracellular recombinant vaccinia virus particles, whereas the unmodified full-length HIV-1 glycoprotein is not (Katz E, et al., J Virol 1997;71:3178-3187). Here, we report that rabbits and mice inoculated with recombinant vaccinia viruses that express the chimeric protein developed higher HIV-specific antibody responses than animals inoculated with vaccinia virus that expressed the unmodified HIV glycoprotein. These data suggest that the immunogenicity of recombinant proteins may be enhanced by their presentation on the surface of vaccinia virus particles.

Animals↗
PubMed1997

Stress, social support and negative affectivity in children with newly diagnosed cancer: a prospective transactional analysis.

Conceptually-driven investigations on the potentially modifiable predictors of individual differences among children with newly-diagnosed cancer may facilitate the identification of pediatric cancer patients at risk for maladjustment during the profound adversity associated with this life-threatening disease and aversive biomedical treatment. Within a risk and resistance theoretical framework, perceived stress and social support were investigated concurrently and prospectively within an exploratory design as predictors of negative affectivity (anxiety and depressive symptoms composite construct) in newly-diagnosed pediatric cancer patients at Time 1 (within one month after diagnosis), Time 2 (6 months postdiagnosis), and Time 3 (9 months postdiagnosis). Hierarchical multiple regression analysis findings indicate that perceived stress and social support have direct and independent effects on negative affectivity principally at the 9-month time interval. These findings are discussed in terms of the cognitive-behavioral treatment implications for enhancing child adjustment during the transition from the initial cancer diagnosis and aversive biomedical treatment to subsequent school and social reintegration.

Adolescent↗