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Biomedical subjects

Y Manor

Publications and source records attributed to Y Manor.

At least 37 records · Page 2Linked to original sources
PubMed1999

Primary antiphospholipid syndrome associated with pernicious anaemia.

AIM: To determine whether there is an association between pernicious anaemia and antiphospholipid antibody syndrome. METHODS: Fifteen patients with pernicious anaemia and 11 patients with iron deficiency anaemia (controls) were evaluated for clinical parameters of thrombosis and/or the presence of antiphospholipid antibodies, antinuclear antibodies or lupus anticoagulant. RESULTS: One asymptomatic patient with pernicious anaemia had laboratory features suggestive of the antiphospholipid syndrome. An additional three patients in each group had slightly elevated antiphospholipid antibody concentrations, within one standard deviation of the normal range. CONCLUSION: The association between pernicious anaemia and antiphospholipid antibody syndrome is rare and evaluation should be guided by clinical indications.

Adult↗
PubMed1999

Coordination of fast and slow rhythmic neuronal circuits.

Interactions among rhythmically active neuronal circuits that oscillate at different frequencies are important for generating complex behaviors, yet little is known about the underlying cellular mechanisms. We addressed this issue in the crab stomatogastric ganglion (STG), which contains two distinct but interacting circuits. These circuits generate the gastric mill rhythm (cycle period, approximately 10 sec) and the pyloric rhythm (cycle period, approximately 1 sec). When the identified modulatory projection neuron named modulatory commissural neuron 1 (MCN1) is activated, the gastric mill motor pattern is generated by interactions among MCN1 and two STG neurons [the lateral gastric (LG) neuron and interneuron 1]. We show that, during MCN1 stimulation, an identified synapse from the pyloric circuit onto the gastric mill circuit is pivotal for determining the gastric mill cycle period and the gastric-pyloric rhythm coordination. To examine the role of this intercircuit synapse, we replaced it with a computational equivalent via the dynamic-clamp technique. This enabled us to manipulate better the timing and strength of this synapse. We found this synapse to be necessary for production of the normal gastric mill cycle period. The synapse acts, during each LG neuron interburst, to boost rhythmically the influence of the modulatory input from MCN1 to LG and thereby to hasten LG neuron burst onset. The two rhythms become coordinated because LG burst onset occurs with a constant latency after the onset of the triggering pyloric input. These results indicate that intercircuit synapses can enable an oscillatory circuit to control the speed of a slower oscillatory circuit, as well as provide a mechanism for intercircuit coordination.

Animals↗
PubMed1999

Synaptic depression creates a switch that controls the frequency of an oscillatory circuit.

Synaptic depression is a form of short-term plasticity exhibited by many synapses. Nonetheless, the functional significance of synaptic depression in oscillatory networks is not well understood. We show that, in a recurrent inhibitory network that includes an intrinsic oscillator, synaptic depression can give rise to two distinct modes of network operation. When the maximal conductance of the depressing synapse is small, the oscillation period is determined by the oscillator component. Increasing the maximal conductance beyond a threshold value activates a positive-feedback mechanism that greatly enhances the synaptic strength. In this mode, the oscillation period is determined by the strength and dynamics of the depressing synapse. Because of the regenerative nature of the feedback mechanism, the circuit can be switched from one mode of operation to another by a very small change in the maximal conductance of the depressing synapse. Our model was inspired by experimental work on the pyloric network of the lobster. The pyloric network produces a simple motor rhythm generated by a pacemaker neuron that receives feedback inhibition from a depressing synapse. In some preparations, elimination of the synapse had no effect on the period of the rhythm, whereas in other preparations, there was a significant decrease in the period. We propose that the pyloric network can operate in either of the two modes suggested by the model, depending on the maximal conductance of the depressing synapse.

Action Potentials↗
PubMed1999

Deletion of 6q27 in chronic lymphocytic leukemia and multiple myeloma detected by fluorescence in situ hybridization.

Nonrandom deletions of the long arm of chromosome 6 (6q) are associated with various lymphoid malignancies. It has been suggested that deletions of 6q25-27, 6q21, and 6q23 typically occur in intermediate-grade, high-grade, and low-grade lymphomas, respectively. We used fluorescence in situ hybridization (FISH) to evaluate the occurrence of 6q27 deletion in chronic lymphatic leukemia (CLL) and multiple myeloma (MM). 6q27 deletion was detected in 21% of patients with CLL and in 28% of patients with MM. The percentage of cells containing deletions ranged between 25-49. Two patients with MM had progressive disease and the aberration was detected in both. We conclude that FISH is a sensitive method to detect 6q27 deletion in lymphoproliferative disorders. Also, this deletion is not specific to intermediate-grade lymphomas, but occurs also in CLL and MM.

Aged↗
PubMed1999

Network oscillations generated by balancing graded asymmetric reciprocal inhibition in passive neurons.

We describe a novel mechanism by which network oscillations can arise from reciprocal inhibitory connections between two entirely passive neurons. The model was inspired by the activation of the gastric mill rhythm in the crab stomatogastric ganglion by the modulatory commissural ganglion neuron 1 (MCN1), but it is studied here in general terms. One model neuron has a linear current-voltage (I-V) curve with a low (L) resting potential, and the second model neuron has a linear current-voltage curve with a high (H) resting potential. The inhibitory connections between them are graded. There is an extrinsic modulatory excitatory input to the L neuron, and the L neuron presynaptically inhibits the modulatory neuron. Activation of the extrinsic modulatory neuron elicits stable network oscillations in which the L and H neurons are active in alternation. The oscillations arise because the graded reciprocal synapses create the equivalent of a negative-slope conductance region in the I-V curves for the cells. Geometrical methods are used to analyze the properties of and the mechanism underlying these network oscillations.

Animals↗
PubMed1999

Replication pattern in cancer: asynchronous replication in multiple myeloma and in monoclonal gammopathy.

In this study we evaluated the replication pattern and cell-cycle dynamics of cells from patients considered to have a premalignant condition (monoclonal gammopathy, or MGUS) and patients with multiple myeloma (MM), as well as healthy controls. We applied the fluorescence in situ hybridization (FISH) technique with the TP53, RB-1 and 21q22 loci on the patient's cells. Asynchrony was determined by the presence of one single and one set of double dots in the same cell. The rate of asynchronic replication was significantly higher in the cells from MM patients, with intermediate value in the cells from MGUS, while the lowest rate was in cells from controls. We suggest that these results may reflect the changes in gene replication and cell-cycle progression that occur in premalignant and malignant cells.

Aged↗
PubMed1999

Deletion 5q31 in patients with stable, melphalan-treated multiple myeloma.

The risk of myelodysplastic syndrome (MDS) or acute myeloblastic leukemia (AML) in patients with multiple myeloma has been estimated to be 10-20% after 10 years. Most myeloma patients develop MDS/AML after 3-4 years of treatment with alkylating agents, mainly melphalan; chromosomes 5 and 7 are most frequently involved. We studied 14 patients with myeloma by fluorescence in situ hybridization (FISH) with a probe to 5q31 (the critical area of deletion on chromosome 5) to verify whether deletion of 5q31 occurs during the course of stable, uncomplicated myeloma, and to assess the clinical importance of this abnormality. We found 2 patients (14%) with deletion of 5q31 in 30-40% of their peripheral white blood cells. One patient with this deletion received a high cumulative amount of melphalan, and the other patient was treated with multiple alkylating agents, including melphalan. In these patients, no clinical or laboratory evidence of transformation occurred 14 and 12 months after the finding of the aberration. These findings suggest that 5q-may occur months prior to the overt development of (t)-MDS/AML, and raise important concerns regarding the management of patients with this and similar aberrations, including modification of treatment and performance of cytogenetic evaluation prior to autologous or PSC transplantation. The clinical and biological implications of these findings should be evaluated in larger clinical and laboratory studies.

Aged↗
PubMed1999

Acute renal failure in a neonate caused by the transplacental transfer of a nephrotoxic paraprotein: successful resolution by exchange transfusion.

Acute renal failure was diagnosed within 6 days of birth in a full-term neonate. The mother was known to have a monoclonal gammopathy, immunoglobulin G (IgG) lambda, discovered a year before pregnancy on being investigated for hematuria and proteinuria. Her renal function was intact. Maternal renal biopsy performed at the time showed a focal proliferative glomerulonephritis with nonfibrillary homogeneous mesangial and intramembranous electron-dense deposits. Immunoperoxidase staining was positive for IgG and lambda and kappa light chains along the glomerular and tubular basement membranes. Pregnancy was uneventful. Protein electrophoresis and immunofixation of the infant girl's serum and urine samples showed the presence of a paraprotein electrophoretically identical to that found in the mother. Exchange transfusion resulted in a rapid improvement of renal function in parallel to the disappearance of the monoclonal component.

Acute Kidney Injury↗
PubMed1999

Lingual cyst with respiratory epithelium: an entity of debatable histogenesis.

PURPOSE: The purpose of this report was to describe a new case of lingual cyst with respiratory epithelium, to review and analyze the literature regarding lingual cyst of foregut origin and lingual alimentary cyst, and to discuss the suitable terminology for these uncommon cysts. MATERIAL AND METHODS: Data from articles published in the English language between the years 1942 and 1947 were used. RESULTS: The review of the literature showed 53 lingual cysts of which 29 could be grouped into lingual alimentary tract cysts and 24 into lingual cysts of foregut origin. There was an overlap in histologic and clinical features and embryogenesis of both cysts. CONCLUSIONS: Differentiation between both cysts cannot be supported, and until further information is accumulated it is suggested that histologic descriptive terms be used such as lingual cyst with respiratory epithelium, lingual cyst with gastric epithelium, or lingual cyst with respiratory and gastric epithelium.

Child↗
PubMed1999

Risk factors contributing to symptomatic plate removal in orthognathic surgery patients.

PURPOSE: This study analyzed the fate of miniplates in orthognathic surgery and defined risk factors that eventually result in plate removal. PATIENTS AND METHODS: The outpatient clinic files of 70 patients who had undergone orthognathic surgery were reviewed. All osteotomies were rigidly fixed with stainless steel or titanium miniplates. Study variables included age, gender, plate material, site of plates, and reasons for plate removal. RESULTS: Of 260 plates used for fixation, 31 were removed (12%). When all factors were considered together, only age was statistically significant. Patients older than 30 years of age were more likely to have plate removal (22% vs. 9%). Only when each factor was considered separately were gender and plate material statistically significant. Females (15.4% vs. 6.7%) and stainless steel plates (15.5% vs. 6.7%) were more prone to plate removal. Although more plates were removed from the buttress (15.5%) and chin (14.5%) compared with the piriform area (6.4%), this was not statistically significant. CONCLUSIONS: Age can be defined as a primary risk factor for plate removal, whereas gender and plate material are secondary. Although age and gender are not controllable, the use of titanium plates and infection control may lower the number of symptomatic plates and the need for their removal.

Adolescent↗
PubMed1999

Dental extractions in patients maintained on continued oral anticoagulant: comparison of local hemostatic modalities.

OBJECTIVE: The purpose of this study was to evaluate postoperative bleeding in patients treated with oral anticoagulant drugs who underwent dental extractions without interruption of the treatment and to compare the effect of 3 different hemostatic modalities. STUDY DESIGN: A total of 150 patients who underwent dental extractions were divided into 3 groups. Local hemostasis was carried out as follows: group 1 (119 extractions), with gelatin sponge and sutures; group 2 (117 extractions), with gelatin sponge, sutures, and mouthwash with tranexamic acid; group 3 (123 extractions), with fibrin glue, gelatin sponge, and sutures. RESULTS: Of 150 patients, 13 (8.6%) presented with postoperative bleeding: 3 patients from group 1, 6 patients from group 2, and 4 patients from group 3. CONCLUSIONS: Dental extractions can be performed without interruption in patients treated with oral anticoagulant. Local hemostasis with gelatin sponge and sutures is sufficient.

Administration, Oral↗
PubMed1999

Association between alopecia and response to aggressive chemotherapy in patients with Hodgkin's disease.

The clinical significance and implications of absence of alopecia and/or neutropenia in patients treated with chemotherapy for malignant disease is unknown. We hypothesized that there is a common mechanism of resistance to the effects and the adverse effects of anticancer treatment, which may have clinical implications. To evaluate this hypothesis, we conducted a retrospective analysis of the charts of 17 consecutive patients with Hodgkin's disease who received at least 4 courses of combination chemotherapy (ABVD or MOPP/ABV). Twelve patients underwent complete alopecia while 5 patients retained their hair or had only minimal hair loss. The two groups had similar pretreatment characteristics. Ten (83%) of the patients with alopecia achieved complete remission as compared with 2 (40%) of the patients who retained their hair (P = 0.11). Also, patients without alopecia had fewer episodes of neutropenia (0% vs 33%, P = 0.02), delays of scheduled treatments (0% vs 66%, P = 0.02) or number of courses with dose reductions (20% vs 41%, P = 0.39). These differences shows a clear trend which did not reach statistical significance due to the small number of patients. We suggest that, in intensively treated patients with Hodgkin's disease, the absence of alopecia may predict a poor response to treatment. Also, patients without alopecia probably have fewer episodes of leukopenia, deferral of treatment courses or number of courses with dose reductions. We hypothesize that there is a common mechanism of resistance to cytotoxic agents that may prevent apoptotic death in both normal and malignant cells.

Adult↗
PubMed1999

Unusual peripheral odontogenic tumors in the differential diagnosis of gingival swellings.

Differential diagnosis of gingival mass lesions includes several conditions and causes. Peripheral odontogenic tumors may mimic gingival swellings and, although rare, must be included in the differential diagnosis. The purpose of this article is to describe 3 different cases of peripheral odontogenic tumors and to discuss the differential diagnosis of gingival swelling. Histologic examination is mandatory when localized gingival swellings are surgically removed.

Adult↗
PubMed1999

A double-selective tissue culture system for isolation of wild-type poliovirus from sewage applied in a long-term environmental surveillance.

We describe a simple, cost-efficient, double-selective method for isolation of wild-type poliovirus from sewage samples containing vaccine polioviruses and other enteroviruses, with a detection limit of 18 to 50 PFU per 1 to 2 liters of sewage. By this method we were able to process 1,700 sewage samples collected between 1991 and 1996, from which 10,472 plaques were isolated, 41 of them being identified as wild-type polioviruses.

Animals↗
PubMed1999

Detection of poliovirus circulation by environmental surveillance in the absence of clinical cases in Israel and the Palestinian authority.

The global eradication of poliomyelitis, believed to be achievable around the year 2000, relies on strategies which include high routine immunization coverage and mass vaccination campaigns, along with continuous monitoring of wild-type virus circulation by using the laboratory-based acute flaccid paralysis (AFP) surveillance. Israel and the Palestinian Authority are located in a geographical region in which poliovirus is still endemic but have been free of poliomyelitis since 1988 as a result of intensive immunization programs and mass vaccination campaigns. To monitor the wild-type virus circulation, environmental surveillance of sewage samples collected monthly from 25 to 30 sites across the country was implemented in 1989 and AFP surveillance began in 1994. The sewage samples were processed in the laboratory with a double-selective tissue culture system, which enabled economical processing of large number of samples. Between 1989 and 1997, 2,294 samples were processed, and wild-type poliovirus was isolated from 17 of them in four clusters, termed "silent outbreaks," in September 1990 (type 3), between May and September 1991 (type 1), between October 1994 and June 1995 (type 1), and in December 1996 (type 1). Fifteen of the 17 positive samples were collected in the Gaza Strip, 1 was collected in the West Bank, and 1 was collected in the Israeli city of Ashdod, located close to the Gaza Strip. The AFP surveillance system failed to detect the circulating wild-type viruses. These findings further emphasize the important role that environmental surveillance can play in monitoring the eradication of polioviruses.

Environmental Monitoring↗