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Biomedical subjects

Y Manor

Publications and source records attributed to Y Manor.

At least 55 records · Page 3Linked to original sources
PubMed1998

Frequency control of a slow oscillatory network by a fast rhythmic input: pyloric to gastric mill interactions in the crab stomatogastric nervous system.

The stomatogastic nervous system of the crab, Cancer borealis, produces a slow gastric mill rhythm and a fast pyloric rhythm. When the gastric mill rhythm is not active, stimulation of the modulatory commissural ganglion neuron 1 (MCN1) activates a gastric mill rhythm in which the lateral gastric (LG) neuron fires in antiphase with interneuron 1 (Int1). We present theoretical and experimental data that indicate that the period of the MCN1 activated gastric mill rhythm depends on the strength and time course of the MCN1 evoked slow excitatory synaptic potential (EPSP) in the LG neuron, and on the strength of inhibition of Int 1 by the pacemaker of the pyloric network. This work demonstrates a new mechanism by which a slow network oscillator can be controlled by a much faster oscillatory neuron or network and suggests that modulation of the slow oscillator can occur by direct action on the neurons and synapses of the slow oscillator, or indirectly by actions on the fast oscillator and its synaptic connection with the slow oscillator.

Animals↗
PubMed1998

Pleural effusion in patients with non-Hodgkin's lymphoma: a case-controlled study.

BACKGROUND: Pleural effusion is reported in up to 20% of patients with non-Hodgkin's lymphoma (NHL), most often at presentation. However, the prognostic implications of such findings are not clear. The majority of the information in the literature is based on minor observational studies or case reports. Therefore, a case-controlled study was performed to verify the clinical significance of pleural effusion in NHL. METHODS: Seventeen patients with pleural effusion at the time of presentation of NHL were identified. They were categorized by grade of NHL (based on the Working Formulation). Twenty-nine control patients with similar histopathologic characteristics who had Stage III/IV NHL without pleural effusion were matched to these cases by age, time of diagnosis, and treatment. RESULTS: Ten patients with intermediate grade NHL were matched with 23 controls. No statistically significant difference in complete remission or survival rates between these groups was found (P=0.69 and P=0.7, respectively). The remission and survival rates also were similar in the subgroup of patients and controls who were treated with aggressive chemotherapy. Similarly, no difference was found in these parameters between four cases and six matched controls with low grade lymphoma. No matched controls were found for the patients with high grade lymphoma, but these patients had an unfavorable outcome. Fourteen of the 17 studied patients had an exudative type of pleural effusion. Thoracentesis yielded a positive cytologic finding in every case. CONCLUSIONS: The presence of pleural effusion at the time of presentation of NHL does not adversely affect complete remission or survival rates.

Adult↗
PubMed1998

Frequency regulation of a slow rhythm by a fast periodic input.

Many nervous systems contain rhythmically active subnetworks that interact despite oscillating at widely different frequencies. The stomatogastric nervous system of the crab Cancer borealis produces a rapid pyloric rhythm and a considerably slower gastric mill rhythm. We construct and analyze a conductance-based compartmental model to explore the activation of the gastric mill rhythm by the modulatory commissural neuron 1 (MCN1). This model demonstrates that the period of the MCN1-activated gastric mill rhythm, which was thought to be determined entirely by the interaction of neurons in the gastric mill network, can be strongly influenced by inhibitory synaptic input from the pacemaker neuron of the fast pyloric rhythm, the anterior burster (AB) neuron. Surprisingly, the change of the gastric mill period produced by the pyloric input to the gastric mill system can be many times larger than the period of the pyloric rhythm itself. This model illustrates several mechanisms by which a fast oscillatory neuron may control the frequency of a much slower oscillatory network. These findings suggest that it is possible to modify the slow rhythm either by direct modulation or indirectly by modulating the faster rhythm.

Action Potentials↗
PubMed1998

Leukocyte function in chronic myeloproliferative disorders.

The myeloproliferative disorders (MPD) are clonal diseases that originate from a transformed stem cell and involve all myeloid lineage. The affected cells have both proliferative and functional impairment. Therefore, we evaluated and compared neutrophil function in 31 patients with polycythemia vera (PV), idiopathic myelofibrosis (MF), chronic myeloid leukemia (CML), and essential thrombocytosis (ET). Neutrophil chemotaxis, random migration, bactericidal activity and superoxide anion release in these patients were simultaneously compared to those of 31 healthy controls. In this study, chemotactic activity was significantly impaired in patients with PV and CML as compared to controls (M+/-SE: 42 +/- 6 vs. 69+/- 5 cells/field; p<0.005 and 47+/-7 vs. 68+/- 5; p<0.05, respectively). The assessment of the bactericidal activity of neutrophils showed no impairment in most of the patients. In the CML group, the serum had a very strong "lytic" effect on bacteria, possibly due to the high levels of serum lysozyme (22 +/- 2 microgram/ml). The superoxide anion release was found to be normal in most of the patients. Nevertheless, in 25% of PV patients the superoxide production was impaired (less than 60% of the simultaneous controls). In ET most patients had normal neutrophil function. Regarding the effect of treatment, neutrophil chemotactic activity was found to be significantly reduced in the hydrea-treated patients, as compared to the non- treated patients (p<0.001) or healthy controls (<0.0001). We conclude that disturbances in neutrophil function are present in patients with various MPDs, except ET. This probably reflects abnormal maturation of ancessors of the damaged stem cells. Nevertheless, we should keep in mind that therapy itself could affect neutrophil functions. This matter should be studied more extensively. Although infections are not common in MPD disorders, they occasionally occur. It is possible that impairment in the phagocytic function contribute to the development of infections in patients with myeloproliferative disorders.

Adult↗
PubMed1998

Immune response to an intercalated enhanced inactivated polio vaccine/oral polio vaccine programme in Israel: impact on the control of poliomyelitis.

A combined enhanced inactivated polio vaccine (EIPV) and oral polio vaccine (OPV) programme was introduced in Israel in 1990, with the purpose of providing a solution to the persistent polio morbidity in spite of a 30 year long OPV programme. The schedule comprised two doses of EIPV administered at the age of 2 and 4 months, intercalated with two doses of OPV at 4 and 6 months, followed by a reinforcing dose with the two vaccines simultaneously administered at 12 months. The 5-year evaluation of the programme included: the assessment of clinical suspicions of polio, early immune response in successive cohorts administered the new schedule, dynamics of the immune profile in a cohort followed up to the age of 5, and monitoring of wild poliovirus excretion in sewage specimens collected in 25 permanent sites throughout Israel as well as from the Palestinian Authority. No paralytic polio cases associated with a wild or vaccinal poliovirus strain were detected since the introduction of the programme. At the age of 4 months, one week after administration of the second EIPV and first OPV dose, 100% seropositivity and high geometric mean titres (GMTs) of neutralizing antibody (NA) to the three vaccinal and to the wild poliovirus type 1, responsible for the 1988 polio outbreak, were observed. No change in percent of seropositivity occurred between the age of 6 and 12 months. Thirty days after the IPV and OPV reinforcing doses, GMTs to each of the four poliovirus strains were > or = 3037. Up to the age of 5, the seropositivity was unchanged. After a 2.5-10-fold decline in the first year following the completion of the programme, GMTs to the three vaccinal and the wild poliovirus strain levelled off at rather high values, considered protective. Between 1990 and 1995, 16 wild poliovirus type 1 strains were isolated in three separate episodes in Gaza Strip sewage and once only in one Israeli site very close to Gaza City. The rapidly established, high and persistent NA titre to the vaccinal and wild poliovirus strains and the presence of immunological memory are indicative of high individual protection throughout the first 5 years of life. The only one-time introduction, without circulation, of a wild poliovirus strain in a single Israeli settlement suggests community protection. The intercalated programme offers a contribution to polio eradication by providing a solution to the primary and secondary failure associated with OPV, as well as to the control of vaccine-associated paralytic poliomyelitis.

Antibodies, Viral↗
PubMed1998

Electrocardiographic changes in cardiac patients having dental extractions under a local anesthetic containing a vasopressor.

PURPOSE: This study attempted to identify which group of cardiac patients is most at risk when dental extractions are performed under a local anesthetic with a vasopressor. PATIENTS AND METHODS: Forty cardiac patients who had dental extractions under local anesthesia were connected to a Holter monitor for 24 hours, starting an hour before the procedure. The electrocardiogram was analyzed for the number of premature beats, ST depression, and cardiac rhythm. A mean rate was calculated for the first 2 hours after injection of the local anesthetic and for the subsequent 22 hours. The preoperative electrocardiogram was compared with the electrocardiogram performed 1 week before treatment. RESULTS: Electrocardiographic changes were observed in 15 patients (37.5%), and all occurred during the first 2 hours after injection of the local anesthetic. Of the 15 patients, eight were being treated with digoxin. CONCLUSIONS: Cardiac patients being treated with digoxin had more electrocardiographic changes after administration of a local anesthetic than other cardiac patients. When the local anesthetic contained a vasopressor, there was a greater incidence of tachycardia but less arrhythmia or ST depression.

Adult↗
PubMed1997

Temporal dynamics of graded synaptic transmission in the lobster stomatogastric ganglion.

Synaptic transmission between neurons in the stomatogastric ganglion of the lobster Panulirus interruptus is a graded function of membrane potential, with a threshold for transmitter release in the range of -50 to -60 mV. We studied the dynamics of graded transmission between the lateral pyloric (LP) neuron and the pyloric dilator (PD) neurons after blocking action potential-mediated transmission with 0.1 microM tetrodotoxin. We compared the graded IPSPs (gIPSPs) from LP to PD neurons evoked by square pulse presynaptic depolarizations with those potentials evoked by realistic presynaptic waveforms of variable frequency, amplitude, and duty cycle. The gIPSP shows frequency-dependent synaptic depression. The recovery from depression is slow, and as a result, the gIPSP is depressed at normal pyloric network frequencies. Changes in the duration of the presynaptic depolarization produce nonintuitive changes in the amplitude and time course of the postsynaptic responses, which are again frequency-dependent. Taken together, these data demonstrate that the measurements of synaptic efficacy that are used to understand neural network function are best made using presynaptic waveforms and patterns of activity that mimic those in the functional network.

Animals↗
PubMed1997

Lymphoma with multi gene rearrangement on the level of immunoglobulin heavy chain, light chains, and T-cell receptor beta chain.

A unique case with diffuse mixed malignant lymphoma was investigated for gene rearrangement on the level of T-cell receptor (TCR), heavy chain immunoglobulin (Ig), and both light chains. Cell phenotype was examined with immunofluorescence techniques using antibodies against surface immunoglobulins (SIg) and the kappa and lambda light chains. Monoclonal antibodies were used against CD3, CD4, CD5, CD8, CD10, CD19, CD22, HLA-DR, and TdT. Gene rearrangement analysis for monoclonality determination was carried out with restricted DNA (EcoR I and Hind III) hybridized with one of the following 32P-labelled probes: T-cell receptor (TCR beta), immunoglobulin heavy chain (JH), k light chain, and lambda light chain. Phenotyping of the cell population from the excised lymph node (LN) revealed the presence of 66% B-cells and 35% T-cells. Most of the B cells (94%) expressed mu heavy chain only. Expression of both light chains was negligible (k = 7% and lambda = 2%). Gene rearrangement, which indicates monoclonality, was positive on the level of TCR, Ig heavy chain, and both light chains. The data obtained suggests a neoplastic transforming event in lymphoid stem cells, which preceded the subsequent differentiation process into either B or T lymphoma.

Aged↗
PubMed1997

Monoallelic p53 deletion in chronic lymphocytic leukemia detected by interphase cytogenetics.

Chromosomal aberrations can be detected in 50% of patients with chronic lymphocytic leukemia (CLL). A role for tumor suppressor genes in the genesis of lymphoid tumors has been reported. In B-CLL, p53 gene mutations were found in 10-15% of the patients. We used fluorescence in situ hybridization (FISH) to detect p53 deletion in B-CLL. We also correlated the cytogenetic findings with the clinical course. In situ hybridization to interphase nuclei showed monallelic p53 deletion in 6 of 23 patients (26%). The percentage of cells with one p53 signal ranged from 12 to 100. A statistically significant correlation between p53 deletion and progression of CLL was demonstrated. We conclude that FISH is a sensitive and reliable method to detect deletion of specific genes (i.e., p53) in CLL. The finding of p53 deletion is associated with disease progression.

Aged↗
PubMed1997

Identification of a new strain of fastidious enterovirus 70 as the causative agent of an outbreak of hemorrhagic conjunctivitis.

A 1994 outbreak of acute hemorrhagic conjunctivitis in Israel was caused by an enterovirus 70 strain that was distinct from previously reported strains. Characterization was by electron microscopy (eye washes), reverse transcription-PCR (RT-PCR; eyewash, specimens, eye swabs, and tears), and sequence analysis of RT-PCR-amplified fragments from the 5' noncoding region and VP1.

Amino Acid Sequence↗
PubMed1997

Low-amplitude oscillations in the inferior olive: a model based on electrical coupling of neurons with heterogeneous channel densities.

The mechanism underlying subthreshold oscillations in inferior olivary cells is not known. To study this question, we developed a single-compartment, two-variable, Hodgkin-Huxley-like model for inferior olive neurons. The model consists of a leakage current and a low-threshold calcium current, whose kinetics were experimentally measured in slices. Depending on the maximal calcium and leak conductances, we found that a neuron model's response to current injection could be of four qualitatively different types: always stable, spontaneously oscillating, oscillating with injection of current, and bistable with injection of current. By the use of phase plane techniques, numerical integration, and bifurcation analysis, we subdivided the two-parameter space of channel densities into four regions corresponding to these behavioral types. We further developed, with the use of such techniques, an empirical rule of thumb that characterizes whether two cells when coupled electrically can generate sustained, synchronized oscillations like those observed in inferior olivary cells in slices, of low amplitude (0.1-10 mV) in the frequency range 4-10 Hz. We found that it is not necessary for either cell to be a spontaneous oscillator to obtain a sustained oscillation. On the other hand, two spontaneous oscillators always form an oscillating network when electrically coupled with any arbitrary coupling conductance. In the case of an oscillating pair of electrically coupled nonidentical cells, the coupling current varies periodically and is nonzero even for very large coupling values. The coupling current acts as an equalizing current to reconcile the differences between the two cells' ionic currents. It transiently depolarizes one cell and/or hyperpolarizes the other cell to obtain the regenerative response(s) required for the synchronized oscillation. We suggest that the subthreshold oscillations observed in the inferior olive can emerge from the electrical coupling between neurons with different channel densities, even if the inferior olive nucleus contains no or just a small proportion of spontaneously oscillating neurons.

Animals↗
PubMed1997

Ovarian cysts and cyclic hormone replacement therapy: is there an association?

OBJECTIVES: To evaluate whether there may be an association between postmenopausal ovarian cysts and hormone replacement therapy. METHODS: The study comprised 564 consecutive, asymptomatic, postmenopausal women who were referred for routine, transvaginal ultrasound examinations between January 1 and December 31, 1995. Various demographic and ultrasonographic parameters were recorded on a prospectively-created, computerized data base. RESULTS: There was no difference in the prevalence of ovarian cysts with or without hormone replacement therapy (10.5% vs. 12.5%, respectively). However, in the subgroup of early postmenopausal women (40-55 years), the use of hormone replacement therapy was associated with a significantly reduced prevalence of ovarian cysts (10.4% vs. 28.6%; p < 0.05). CONCLUSIONS: Hormone replacement therapy is associated with a reduced prevalence of ovarian cysts in early postmenopause.

Analysis of Variance↗
PubMed1997

Induction of apoptosis by chlorodeoxyadenosine and dexamethasone in B-chronic lymphocytic leukemia.

Apoptosis, programmed cell death, occurs in a variety of cellular systems and in response to many different stimuli. In the present study we examined the ability of dexamethasone (Dex) and chlorodeoxyadenosine (2-CdA) to induce apoptosis in lymphocytes of patients with B-chronic lymphocytic leukemia (B-CLL). Lymphocytes of 29 untreated patients and 9 healthy controls were isolated and incubated for 24 hours in the presence or absence of either Dex (2 microM) (n = 15) or 2-CdA (3 microM) (n = 14). Following incubation the cells were harvested and their DNA extracted and analysed for internucleosomal DNA cleavage by UV illumination after electrophoresis on agarose slab gel containing ethidium bromide. In the Dex group, 10 patients showed dexamethasone independent spontaneous apoptosis appearing 24 hours after the start of incubation. These were the only instances of dexamethasone-enhanced apoptosis. Five patients showed no spontaneous or dexamethasone induced apopto sis. Of the 2-CdA group, 5 showed spontaneous apoptosis enhanced by 2-CdA. No spontaneous apoptosis was observed in the cells from 9 other patients, however, 2-CdA induced apoptosis in 8 cases in this group. This study shows that monitoring of apoptosis in CLL may provide important information regarding susceptibility of the cells to drug induced apoptosis.

Antineoplastic Agents, Hormonal↗
PubMed1996

Trisomies 9 and 8 detected by fluorescence in situ hybridization in patients with systemic mastocytosis.

BACKGROUND: Systemic mastocytosis is a rare disease characterized by proliferation of mast cells in one or more organs. The origin of the mast cells is still debated, although it has been recently shown that they derive from CD34+ hematopoietic progenitors. Some clinical and in vitro studies have suggested a possible link between myeloproliferative disorders and systemic mast cell disease. OBJECTIVE: This study was designed to further evaluate the association between systemic mast cell disease and other hematologic disorders by means of conventional cytogenetic analysis and fluorescent in situ hybridization. METHODS: We used cytogenetic analysis and fluorescent in situ hybridization with probes to chromosomes 8 and 9 in six patients with systemic mast cell disease. RESULTS: Fluorescent in situ hybridization helped to identify five patients with trisomy 9 and one with trisomy 8. In contrast, chromosomal analysis demonstrated an abnormal karyotype (45,XO/46,XY) in only one patient. CONCLUSION: The association between myeloproliferation disorders and systemic mast cell disease may be explained by the finding that trisomy 9 and trisomy 8 are common in both disorders. A trisomy was detected in all of the patients in our small group compared with nearly 40% of previously reported patients with myeloproliferative disorders. FISH is more sensitive than conventional cytogenetics in detecting these aberrations.

Adult↗
PubMed1996

Placental isoferritin as a marker of early abortion in pregnancies induced by in vitro fertilization.

The relatively high rate of early pregnancy loss in artificial reproductive technology-induced conceptions has driven researchers to seek for an efficient diagnostic tool for estimating the gestational risk in these cases. Monitoring early gestation normalcy using serial beta-human chorionic gonadotrophin (beta hCG) measurements requires several days before diagnosis can be established. The objective of this study was to determine whether placental isoferritin (PLF) can be used as a predictive marker of normal pregnancy development during early stages of in vitro fertilization (IVF)-induced pregnancy. Ninety-three consecutive IVF cycles were investigated. Blood samples for PLF (enzyme linked immunosorbent assay; ELISA) and beta hCG (radio-immunoassay; RIA) determination were obtained from all women on days 11, 13 and 15 following embryo transfer. Placental isoferritin was detectable in the serum 11 days after embryo transfer in IVF conception cycles. These levels were significantly higher in normally developing pregnancies (n = 18) than in cases which eventually aborted spontaneously (n = 9) during the first trimester (mean +/- s.d.; 33 +/- 28 U/mL as compared with 1 +/- 2 U/mL; P = 0.0004; Wilcoxon test; sensitivity 94.5 per cent, specificity 88.9 per cent, positive predictive value 89.9 per cent, negative predictive value 94.5 per cent). Moreover, in those patients who later aborted, lower than normal PLF levels were detected long before the decline in beta hCG titres was evident. Considering its suppressor activity, it is expected that PLF levels would be high at the initiation of normal pregnancy. This may explain the present finding of low PLF levels in abnormally developing IVF-induced pregnancies. These preliminary data suggest that PLF can be used as a sensitive marker for detecting those cases destined to abort at a very early stage. However, further studies are still required on spontaneous conceptions, before this test can be recommended for routine clinical application.

Abortion, Spontaneous↗
PubMed1996

The detection of trisomies 8 and 9 in patients with essential thrombocytosis by fluorescence in situ hybridization.

Essential thrombocytosis (ET) is a clonal, chronic myeloproliferative disorder (MPD) originating from a multipotent stem cell. To date no specific cytogenetic marker has been found in ET. It was recently reported that chromosomal aberrations have been detected by fluorescence in situ hybridization (FISH) in patients with normal karyotypes or nonanalyzable metaphases. Therefore, we evaluated whether trisomies 8 and 9, which are commonly found in MPDs, can be detected in ET by FISH and compared the results with chromosome analysis. Peripheral blood mononuclear cells of patients with essential thrombocytosis were studied by classical chromosome banding and by FISH. We used biotin labeled alpha satellite of chromosome 8 and biotin labeled beta satellite of chromosome 9 as probes for the FISH studies. FISH detected 5 patients with trisomy 8 and 5 with trisomy 9 of the 18 patients evaluated. No trisomy was found by cytogenetic studies. The trisomies were detected by FISH in only a minority of the cells. No correlation was found between the presence of a trisomy and clinical characteristics. FISH is a sensitive method for the detection of trisomies 8 and 9 in patients with ET. The common finding of these chromosomal aberrations in MPD suggests that genes associated with myeloid proliferation are located on these chromosomes. Standardization of interphase cytogenetics is needed before this technique can be accepted for routine use in the clinic.

Adult↗
PubMed1996

A clinical approach to "idiopathic" normocytic-normochromic anemia.

OBJECTIVES: Normocytic-normochromic anemia is frequently found in patients with chronic disorders. The pathogenesis, epidemiological and clinical characteristics of normocytic normochromic anemia of unknown cause are not well established. We evaluated the role of bone marrow examination and the clinical course of patients with "idiopathic" normocytic-normochromic anemia. DESIGN: Patients with normocytic-normochromic anemia underwent a noninvasive evaluation according to a predetermined protocol. Bone marrow aspiration and biopsy were performed in those patients in whom no explanation for the anemia was found. They were later followed at 3 to 6 month intervals. RESULTS: Thirty-one patients (23 females and 8 males) with "idiopathic" normocytic-normochromic anemia (mean hemoglobin concentration was 10.0 + 0.6 g/dL) were detected. No patient had symptoms related to the anemia. Twenty-nine bone marrow aspirations and 21 biopsies were performed. Iron deficiency and mild myelofibrosis were found in one patient each. The rest of the bone marrow examinations were normal. During 15.5 +/- 10.3 months of follow-up, the hemoglobin level rose marginally to 10.9 + 1.0 g/dL (P < .0002). No changes in clinical or laboratory variables that could be ascribed to anemia were detected. CONCLUSION: Normocytic-normochromic anemia of unknown cause is encountered infrequently in clinical practice and is found mainly in older patients. The evaluation should be noninvasive to exclude correctable causes of the anemia. Bone marrow examination is only rarely contributive in this setting. The prognosis of these patients is excellent.

Adult↗