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I Cohen

Publications and source records attributed to I Cohen.

At least 55 records · Page 3Linked to original sources
PubMed2000

The N-terminal domain of rat liver carnitine palmitoyltransferase 1 contains an internal mitochondrial import signal and residues essential for folding of its C-terminal catalytic domain.

We have previously shown that the first 147 N-terminal residues of the rat liver carnitine palmitoyltransferase 1 (CPT1), encompassing its two transmembrane (TM) segments, specify both mitochondrial targeting and anchorage at the outer mitochondrial membrane (OMM). In the present study, we have identified the precise import sequence in this polytopic OMM protein. In vitro import studies with fusion and deletion CPT1 proteins demonstrated that none of its TM segments behave as a signal anchor sequence. Analysis of the regions flanking the TM segments revealed that residues 123-147, located immediately downstream of TM2, function as a noncleavable, matrix-targeting signal. They specify mitochondrial targeting, whereas the hydrophobic TM segment(s) acts as a stop-transfer sequence that stops and anchors the translocating CPT1 into the OMM. Heterologous expression in Saccharomyces cerevisiae of several deleted CPT1 proteins not only confirms the validity of the "stop-transfer" import model but also indicates that residues 1-82 of CPT1 contain a putative microsomal targeting signal whose cellular significance awaits further investigation. Finally, we identified a highly folded core within the C-terminal domain of CPT1 that is hidden in the entire protein by its cytosolic N-terminal residues. Functional analysis of the deleted CPT1 proteins indicates that this folded C-terminal core, which may belong to the catalytic domain of CPT1, requires TM2 for its correct folding achievement and is in close proximity to residues 1-47.

Animals↗
PubMed2000

Signals for TBP/TATA box recognition.

The TATA box-binding protein (TBP) recognizes its target sites (TATA boxes) by indirectly reading the DNA sequence through its conformation effects (indirect readout). Here, we explore the molecular mechanisms underlying indirect readout of TATA boxes by TBP by studying the binding of TBP to adenovirus major late promoter (AdMLP) sequence variants, including alterations inside as well as in the sequences flanking the TATA box. We measure here the dissociation kinetics of complexes of TBP with AdMLP targets and, by phase-sensitive assay, the intrinsic bending in the TATA box sequences as well as the bending of the same sequence induced by TBP binding. In these experiments we observe a correlation of the kinetic stability to sequence changes within the TATA recognition elements. Comparison of the kinetic data with structural properties of TATA boxes in known crystalline TBP/TATA box complexes reveals several "signals" for TATA box recognition, which are both on the single base-pair level, as well as larger DNA tracts within the TATA recognition element. The DNA bending induced by TBP on its binding sites is not correlated to the stability of TBP/TATA box complexes. Moreover, we observe a significant influence on the kinetic stability of alteration in the region flanking the TATA box. This effect is limited however to target sites with alternating TA sequences, whereas the AdMLP target, containing an A tract, is not influenced by these changes.

Adenoviridae↗
PubMed2000

Contributions of intrinsic and synaptic activities to the generation of neuronal discharges in in vitro hippocampus.

1. Extracellular and intracellular records were made from guinea-pig hippocampal slices to examine the contributions of intrinsic cellular properties and synaptic events to the generation of neuronal activity. Extracellular signals were filtered to pass action potentials, which could be detected within a distance of about 80 microm from a discharging cell. 2. Spontaneous action potentials were invariably detected in records from the stratum pyramidale of CA3 region. Blocking excitatory synaptic transmission with NBQX and APV reduced their frequency by 23 +/- 35 %. Suppressing synaptic inhibition, while excitation was already blocked, increased the rate of spike discharge to 177 +/- 71 % of its control value. 3. Most action potentials recorded intracellularly from CA3 pyramidal cells were initiated in the absence of a detectable synaptic event. In contrast, most action potentials generated by inhibitory cells located close to stratum pyramidale were preceded by an EPSP. 4. In 31 simultaneous recordings, intracellular pyramidal cell action potentials appeared consistently to initiate extracellular spikes with a mean latency of 2.2 +/- 1.0 ms. Single inhibitory cell action potentials could initiate a reduction in the frequency of extracellular spikes of duration 10-30 ms. 5. Some identified extracellular spikes (n = 9) consistently preceded intracellularly recorded IPSPs. IPSPs were initiated monosynaptically with latencies of 0.9-1.5 ms. In reciprocal interactions, single pyramidal cell action potentials could trigger the discharge of an identified unit that in turn appeared to initiate an IPSP in the same pyramidal cell. 6. These data suggest that intrinsic cellular mechanisms underly much of the spontaneous activity of pyramidal cells of the CA3 region of the hippocampus in vitro. Both synaptic inhibition and a strong excitation of inhibitory cells by pyramidal cells act to reduce population activity.

Action Potentials↗
PubMed2000

Prenatal sonographic detection of a lipomeningocele as a sacral lesion.

We present a case of a lipomeningocele in a newborn. Prenatal sonography revealed dysraphia and a 3.8 x 4.3 cm, semisolid, echogenic mass that was continuous with the sacral area and bulged posteriorly under the skin. The mass was diagnosed after birth as a lipomeningocele based on the results of MRI. This diagnosis was confirmed histologically.

Adult↗
PubMed2000

Detection of micrometastasis by cytokeratin-20 (reverse transcription polymerase chain reaction) in lymph nodes of patients with endometrial cancer.

BACKGROUND: Cytokeratins are constituents of the intermediate filaments (IFs) of epithelial cells which are expressed in various combinations, depending on the type of epithelium and degree of differentiation. We have reported (R. Zemer, A. Fishman, J. Bernheim, S. Zimlichman, O. Markowitz, M. Altaras, and A. Klein, Gynecol Oncol 70:410-413, 1998) on the determination of cytokeratin-20 (CK-20) by reverse transcription polymerase chain reaction (RT-PCR) in the detection of endometrial cancer cells as a potential biomarker. In that study, we also found that by using immunocytochemistry, most carcinomas were found to be negative for CK-20. The sensitivity and specificity rates obtained by using the RT-PCR method were 94.4 and 91%, respectively. OBJECTIVE: The aim of this study is to investigate the feasibility and potential of the specific mRNA marker, CK-20, to detect endometrial cancer cells-micrometastases (MMs)-by RT-PCR in lymph node (LN) samplings of patients undergoing hysterectomy for endometrial carcinoma. METHOD: We used the RT-PCR method to determine the expression of CK-20 in the LNs of 20 patients [study group (SG)] who were being surgically staged and treated for endometrial carcinoma. The specificity of the mRNA CK-20 marker was examined in LNs obtained from five healthy patients [control group (CG)] who underwent abdominal hysterectomy and bilateral salpingo-oopherectomy for benign gynecologic conditions. The LNs obtained from the SG and CG patients were prepared together before mRNA extraction. RNA of the various cell pellets was extracted and RT-PCR was performed with CK-20 primers. RT-PCR products were analyzed by agarose gel electrophoresis and ethidium bromide staining against PCR size markers. Specificity of the RT-PCR products was examined by Southern blotting. RESULTS: Histopathologic examinations demonstrated the presence of metastases in two (10%) SG patients. These patients were also CK-20 positive. Of the remaining 18 patients with negative histopathologic results, 6 (33%) were CK-20 positive and 12 (67%) were negative. All the CG patients were CK-20 negative (specificity, 100%). CONCLUSIONS: The results obtained in this study suggest that RT-PCR of CK-20 is more sensitive than traditional histopathologic methods in the diagnosis of MMs in LNs of patients with endometrial cancer. Thus, due to the aforementioned characteristics of CK-20, it may be considered a powerful biomarker in the detection of MMs in LNs of patients with endometrial cancer.

Adenocarcinoma↗
PubMed2000

Localization, detection and guided removal of soft tissue in the hands using sonography.

Penetrating wounds and lacerations are frequent pathologies treated in the emergency room. The management of hand trauma represents a large part of the work in any surgical practice. Although X-rays are routinely taken, numerous foreign bodies remain undetected, and the wounds are just locally debrided and the lacerations sutured. Unfortunately, as not all foreign bodies are radio-opaque, the radiography results may appear normal, but the patient fails to recover. Patients complaining of persistent wound tenderness were sent for ultrasound investigations, and foreign bodies were detected. Had ultrasonography been carried out initially in the emergency room, the correct diagnosis would have been made, and the sonographic equipment could have helped to guide the physician in his attempt to remove the foreign body. Usually, in response to continued pain, an ultrasound investigation is ordered, and the pathology becomes apparent. A number of examples are briefly described in order to highlight the present inadequacies. It is suggested that hospital administrators consider the need to provide ultrasonographic services as an integral facility of the emergency room.

Adult↗
PubMed2000

Storing live embryonic and adult human cartilage grafts for transplantation using a joint simulating device.

OBJECTIVES: Cartilage transplantation as a means to replace damaged articular surfaces is of interest. A major obstacle is the long-term preservation of cartilage grafts. The commonly used technique of freezing the grafts inevitably leads to cellular death. The current study compares the technique to an innovative approach using a pulsed-pressure perfusion system termed a joint simulating device (JSD), intended to simulate intra-articular mechanical forces. METHODS: Human articular cartilage explants were harvested from both embryonic epiphyseal tissue and femoral heads of elderly women (over 70 years of age) undergoing a partial joint replacement (hemi-arthroplasty) and were divided in two groups: half of the samples were incubated in the JSD while the remaining half were grown in static culture within tissue culture plates. After 10 days all samples were evaluated for: (a) cell vitality as assessed by image analysis and XTT assay; (b) biosynthetic activity as expressed by radioactive sulfate incorporation into glycosaminoglycans (GAG's); and (c) proteoglycan content as assessed by alcian blue staining intensity. RESULTS: A 10-fold increase in sulfate incorporation in samples held in the JSD compared to the static culture group was observed in embryonic cartilage. In adult cartilage culture in the JSD elevated sulfate incorporation by threefold as compared to static culture. Central necrosis was observed in specimens grown in the static culture plates, while it did not occur in the samples held in the JSD. Cell vitality as assessed by XTT assay was significantly better in the JSD group as compared to static culture. The difference was more pronounced in the embryonic specimens as compared to adult cartilage. The specimens cultured within the JSD retained proteoglycans significantly better than those cultured in static culture. CONCLUSIONS: Maintenance of cartilage specimens in a JSD was highly effective in keeping the vitality of cartilage explants in vitro over a 10-day period. A possible future application may be a long-term preservation of chondral grafts, without freezing. Avoidance of freezing of cartilage grafts, might prevent the cartilage degeneration often observed in frozen osteochondral grafts.

Aged↗
PubMed2000

Orthopaedic outcome of total knee replacement in haemophilia A.

A consecutive series of 16 patients with classical Haemophilia underwent 21 total knee replacements between 1989 and 1997 for haemophilic arthropathy. The patients received Factor VIII replacement therapy via continuous infusion, and fibrin glue was used to facilitate haemostasis. Three different types of prostheses were used. A follow-up evaluation was undertaken between 2 and 10 years after the operation (mean 5.6 years) and two patients with infection were excluded. Knee scores averaged 77.5 (pre-operative 24. 1) and functional scores averaged 84.4 (preoperative 23.2). There were no cases with aseptic loosening of the prosthesis. Complications included one early deep infection controlled by conversion of the TKR into an arthrodesis, one case of late septic loosening that had to be re-operated upon, one case of patellar dislocation, two cases of stiff knee (fibro-arthrosis) that required manipulation under anaesthesia, one postoperative hepatitis, one superficial infection treated by incision and drainage and four febrile patients with no clear source of infection, who responded to antibiotics alone. In conclusion, TKR offers haemophilic patients a long-lasting improvement of their quality of life and we therefore advocate its use with the appropriate indications.

Adult↗
PubMed2000

Internal hemipelvectomy for bone sarcomas in children and young adults: surgical considerations.

AIMS: Pelvic bone sarcomas in children and young adults are rare, and associated with a poor prognosis and a high rate of local recurrence. Primary goals of treatment include prevention of local recurrence and distant metastases. A secondary goal is maintenance of quality of life by avoiding major amputative surgery. This is why internal hemipelvectomy (a limb-sparing surgery) is advocated whenever possible. The focus of our presentation is surgical issues in the context of resection and reconstruction of the pelvis in the first two decades of life. MATERIALS AND METHODS: Between January 1988 and June 1998, 27 patients were treated and operated on (follow-up time 1.5-12 years). There were 17 males and 10 females. Their age ranged between 2 and 22 years. There were 24 patients with Ewing's sarcoma (ES) and three with other bone sarcomas. In 19 patients the tumour involved the entire or part of the iliac bone (in some cases with extension to the sacrum). In five patients the tumour involved the pubis and/or ischium. In three patients the tumour involved the sacrum with some extension to the posterior iliac bone. All patients received neoadjuvant and adjuvant chemotherapy and radiotherapy with different protocols (related to the origin of referral). RESULTS: Twenty-seven patients underwent internal hemipelvectomy. According to Enneking's classification there were: type I-10; type II-one; type III-six; type IV-five (including one localized sacrectomy); type I+IV-five patients. In 15 patients some kind of reconstruction was needed and in 12 no reconstruction was done. Four wound infections occurred that were managed successfully by surgical debridement, antibiotics and local wound care. In one case removal of the 'implant' was needed. No primary or secondary amputations were performed in the series. The rate of local recurrence was 22%. Functional status at the last follow-up visit or before death, according to the AMSTS functional rating system: excellent-six; good-17; fair-three and poor-one. All patients except the one poor result maintained their walking ability during the follow-up time. CONCLUSIONS: Internal hemipelvectomy is achievable in most cases and justified for better quality of life in children, adolescents and young adults with sarcomas. Further efforts are needed to improve the reconstructive options in the pelvis.

Adolescent↗
PubMed2000

Enhanced prognostic stratification of patients with left ventricular hypertrophy with the use of single-photon emission computed tomography.

BACKGROUND: Patients with left ventricular hypertrophy (LVH) are at increased risk of future cardiovascular events. Little is known about risk stratification of these patients with the use of myocardial perfusion imaging. This study sought to assess the prognostic stratification of patients with LVH by using myocardial perfusion single-photon emission computed tomography (SPECT). METHODS AND RESULTS: We studied 633 consecutive patients with electrocardiographic evidence of LVH who underwent dual isotope myocardial perfusion SPECT (rest thallium 201/stress technetium 99m sestamibi) and were followed up for a mean period of 22 +/- 7 months. During the follow-up period, 67 events (35 cardiac deaths and 32 nonfatal myocardial infarctions) occurred (6% annual event rate). The results of the perfusion scan significantly risk-stratified the population; patients with normal scans had a low rate of nonfatal myocardial infarction and cardiac death (<1% per year of follow-up). The rates of cardiac events increased significantly as a function of the scan result: 4.9% in patients with mildly abnormal scans and 10. 3% in moderately to severely abnormal scans. Cox proportional hazards analysis demonstrated that after adjusting for pretest likelihood of coronary artery disease (the most predictive clinical variable; chi(2) = 15.5, P <.001), summed stress score (the most predictive nuclear variable; chi(2) = 18, P <.0001) added significant incremental prognostic information (global chi(2) increased from 15.5 to 36; P <.001). CONCLUSIONS: In patients with LVH with an overall high cardiac event rate, SPECT provided enhanced stratification by adding significant incremental prognostic information over clinical and historic variables.

Aged↗
PubMed2000

Ex vivo expansion of early and late megakaryocyte progenitors.

Our goal is to produce ex vivo-expanded human megakaryocytes (MK) cells from peripheral blood progenitor cell (PBPC) harvests for use in supplementing conventional autografts. In this paper we show the megakaryocytopoietic productivity of small-scale in vitro serum-free cultures of human CD34+ cells containing MK growth and development factor (MGDF) and stem cell factor (Kit ligand; SCF) +/- granulocyte colony-stimulating factor (G-CSF). Cultures were characterized after 3, 6, 9, and 13 days by flow cytometry and clonogenic assays. CD34+ cells expanded 5.2- and 3.4-fold, and produced 2.2 and 2.4 CD34+/41(+) cells per seeded CD34+ cell after 6 and 9 days in culture, respectively. None were detected at day 13. CD41+ cells expanded exponentially over 13 days. Colony-forming unit-megakaryocyte (CFU-MK) also expanded exponentially, but the proportion of the most primitive CFU-MK dropped from 45% to 1.5% and to <1% after 6 and 9 days, respectively. G-CSF increased total cell expansion, but decreased CD41+ frequency, yielding no gain in MK production. We also found that PB CD34+ cells cultured for 3-6 days are richer in primitive MK progenitors, while those cultured for 9-13 days have greater numbers of more differentiated MKs. Overall, the combination of MGDF+SCF proved sufficient for expanding CD34+/CD41+ cells. As the stage of ex vivo MK differentiation most conducive to optimal platelet production in vivo is not known, we are planning a clinical trial to determine the efficacy of ex vivo-expanded MKs on platelet recovery in relation to MK maturity.

Antigens, CD34↗
PubMed2000

Marginal corneal infiltrates: a possible new manifestation of sinus histiocytosis with massive lymphadenopathy.

PURPOSE: To describe unilateral deep marginal corneal infiltrates and chronic anterior uveitis in a young patient with sinus histiocytosis and massive lymphadenopathy. METHODS: A 20-year-old man with a painless enlargement of his cervical lymph nodes was followed for five years after debulking of these nodes on the right side for right chronic anterior uveitis and deep marginal corneal infiltrates. RESULTS: Histological sections of cervical lymph node confirmed the diagnosis of sinus histiocytosis with the typical emperipolesis. The uveitis partially responded to topical corticosteroid treatment but tended to recur upon its withdrawal. The marginal corneal infiltrates resolved gradually over a period of five years. CONCLUSIONS: Marginal corneal infiltrates and uveitis may presumably be associated with sinus histiocytosis. Patients with sinus histiocytosis should also be screened for rare ocular involvement, such as uveitis and corneal infiltrates.

Adult↗
PubMed2000

Ultrasonographic measurement of endometrial changes following discontinuation of tamoxifen treatment in postmenopausal breast cancer patients.

OBJECTIVE: To assess whether there is a decrease in endometrial thickness following discontinuation of tamoxifen treatment as measured by ultrasound. DESIGN: Prospective study. SETTING: Department of Obstetrics and Gynaecology, Sapir Medical Centre, Kfar-Saba, Israel. POPULATION: Fifty-eight postmenopausal women with breast cancer who were treated with tamoxifen. METHODS: Transvaginal ultrasonographic measurements of endometrial thickness. MAIN OUTCOME MEASURES: Evaluation of the changes of endometrial thickness and the frequency the endometrium reached a thickness of < or = 5 mm at different time intervals after stopping tamoxifen treatment. RESULTS: There was a significant decrease in median thickness of the endometrium, within six months after stopping tamoxifen, from 7.75 mm measured at the last ultrasonographic study performed before tamoxifen discontinuation down to 5.2 mm (P = 0.002). There were no further reductions in endometrial thickness, and it remained constantly low in subsequent ultrasonographic studies which were performed at various times up to 30 months following the discontinuation of tamoxifen treatment. While taking tamoxifen, only 25-9% of the women had an endometrial thickness of < or = 5 mm. This proportion doubled in their first six months after stopping. CONCLUSIONS: Median thickness of endometrial thickness significantly reduced within six months following tamoxifen discontinuation, and remained constantly low thereafter. This finding may support use of ultrasonographic imaging for the measurement of tamoxifen's effect on the endometrium of postmenopausal breast cancer patients.

Antineoplastic Agents, Hormonal↗
PubMed2000

Pelvic actinomycosis presenting as ureteric and rectal stricture.

BACKGROUND/AIMS: Simultaneous ureteric and rectal stricture due to pelvic actinomycosis is very rare and only a few cases of either rectal or ureteric stricture have been reported. Our aim is to report a case of stricture of the rectum and the right ureter due to pelvic actinomycosis infection in a 63-year-old man. METHODS: Explorative laparotomy and biopsies of the inflammatory pelvic mass were the only procedures that led to the definitive diagnosis of actinomycosis. Temporary diverting colostomy, drainage of the right ureter by a pigtail catheter and postoperative treatment with appropriate antibiotics were successful in eradicating the inflammatory process. CONCLUSIONS: Extensive pelvic masses involving pelvic viscera should be biopsied before undertaking any major surgery because of the possibility of pelvic actinomycosis.

Actinomycosis↗