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A Schoenfeld

Publications and source records attributed to A Schoenfeld.

At least 19 recordsLinked to original sources
PubMed2003

A multivariate, spatiotemporal analysis of electromagnetic time-frequency data of recognition memory.

Electromagnetic indices of "fast" (above 12 Hz) oscillating brain activity are much more likely to be considerably attenuated by time-averaging across multiple trials than "slow" (below 12 Hz) oscillating brain activity. To the extent that both types of oscillations represent the activity of temporally and topographically separable neural populations, time averaging can cause a loss of brain activity information that is important both conceptually and for multimodal integration with hemodynamic techniques. To address this issue for recognition memory, simultaneous electroencephalography (EEG) and whole-head magnetoencephalography (MEG) recordings of explicit word recognition from 11 healthy subjects were analyzed in two different ways. First, the time course of neural oscillations ranging from theta (4.5 Hz) to gamma (42 Hz) frequencies were identified using single-trial continuous wavelet transforms. Second, traditional analyses of amplitude variations of time-averaged EEG and MEG signals, event-related potentials (ERPs), and fields (ERFs) were performed and submitted to distributed source analyses. To identify data patterns that covaried with the difference between correctly recognized studied (old) words and correctly rejected nonstudied (new) words, a multivariate statistical tool, partial least squares (PLS), was applied to both types of analyses. The results show that ERPs and ERFs are mainly displaying those neural indices of recognition memory that oscillate in the theta (4.5-7.5 Hz), alpha (8-11.5), and to some extent in the beta1 (12-19.5 Hz) frequency range. The sources of the ERPs/ERFs were in good agreement with the topography of theta/alpha/beta 1 oscillations in being confined to the anterior temporal lobe at 400 ms and being distributed across temporal, parietal, and occipital areas between 500 and 700 ms. Gamma oscillations covaried either positively or negatively with theta/alpha/beta1 oscillations. A positive covariance, for instance, was detected over left anterior temporal sensors as early as 200-350 ms and is compatible with studies in rodents showing that gamma and theta oscillations emerge together out of the interaction of the hippocampus and the entorhinal and perirhinal cortices. Fast beta oscillations (20-29.5 Hz), on the other hand, did not strongly covary with slow oscillations and were likely to arise from neural populations not adequately represented in ERPs/ERFs. In summary, by providing a more comprehensive description of electromagnetic signals, time-frequency data are of potential benefit for integrating electrophysiological and hemodynamic indices of brain activity and also for integrating human and animal electrophysiology.

Adolescent↗
PubMed2002

Sonographic evaluation of the puerperal uterus: correlation with manual examination.

OBJECTIVES: To document uterine involution after vaginal delivery and cesarean section by abdominal sonography and to compare the efficacy of manual examination and ultrasonography. STUDY DESIGN: Postpartum manual and sonographic assessment of uterine involution was performed in 120 patients following vaginal and cesarean delivery with an attempt to build a database of changes in uterine dimensions. The patients' reports on the intensity of uterine contractions and vaginal bleeding were compared to the results of sonographic imaging. RESULTS: Palpation revealed proper uterine involution in 80 and 25% of patients after vaginal delivery and cesarean section, respectively. It could not be performed in 2.5% after vaginal delivery compared to 50% after cesarean section. Uterine length was found to be significantly greater after cesarean section than after vaginal delivery (p = 0.0001), and the anterior uterine wall was significantly thinner than the posterior wall (p = 0.0001). Uterine length was significantly greater in the presence of blood accumulation in the uterine cavity (20.7 cm), than when the uterus was empty (18.8 cm) (p = 0.001). In correlating between the patient's report of intense bleeding and the sonographic picture of blood in the uterine cavity sonography had a sensitivity of 0.56 and a specificity of 0.83, whereas the patients' reports had a positive predictive value of 0.22. The difference in information provided by the patients versus that provided by sonography was highly significant (p = 0.001, chi(2) test). CONCLUSION: Within 3 days after delivery, patients particularly those having had a cesarean section, should undergo uterine sonographic scanning and manual palpation to evaluate involution and presence of blood in the uterine cavity.

Adult↗
PubMed2000

Scanning electron microscopy and X-ray diffraction studies in the analysis of medical materials: Gore-Tex versus braided polyester tape for repair of the incompetent cervix.

Cathodoluminescence in the scanning electron microscope and roentgenogram diffraction studies were applied to the analysis of two different medical materials used in cervical cerclage, the treatment of cervical incompetence. Braided polyester tape or Gore-Tex was used as suture material and was analyzed both before and after use in cerclage of the cervix. Results of SEM and X-ray diffraction studies showed distinct differences between the two materials, with the Gore-Tex demonstrating a superior morphological integrity and a decreased likelihood of phagocyte adhesion. These results correlated well with the clinical observations, which also showed Gore-Tex to be a superior medical material.

Female↗
PubMed1999

Neural correlates of recognition memory with and without recollection in patients with Alzheimer's disease and healthy controls.

To dissociate recognition memory with and without recollection, event-related potentials (ERPs) of patients with Alzheimer's disease (AD) and matched controls were recorded in a test of verbal recognition memory accompanied by a source judgement. AD patients who had smaller hippocampi showed a disability to recollect the study context (source). Their ERPs elicited by correctly recognized old words compared to new items were more positive only between 300 and 500 ms with a maximum over the frontal scalp. Controls exhibited a sustained old/new effect over left temporoparietal and frontal sites. The present findings suggest that preserved recognition memory in patients with mild AD is independent of hippocampally mediated processes recollecting episodic memories.

Aged↗
PubMed1999

Transducer user syndrome: an occupational hazard of the ultrasonographer.

Since no study to date has assessed the prevalence of scanning-related disorders amongst sonographers in Obstetrics and Gynecology, we distributed a survey to all trained personnel in our ultrasound division. We evaluated the correlation between injuries sustained in the workplace, and factors such as age, gender, work load and intensity, scanning techniques, previous medical problems, and physical activity. Injuries included one or more of the following: carpal tunnel syndrome; carpal instability; tendinitis; back, shoulder, and neck pain; tingling and/or numbness in the extremities; weakness; and motion restriction. Of the 44 respondents, 29 (65%) have experienced some type of injury or symptom over the course of their scanning career. Five (12%) reported having missed work because of their symptoms, 15 (34%) have received orthopedic treatment (medication or physiotherapy), two (4.5%) have been diagnosed with carpal tunnel syndrome, and one (2.3%) with carpal instability based on electrophysiological examinations. These results demonstrate that ultrasound scanning in Obstetrics and Gynecology may pose an occupational risk for doctors and technicians.

Adult↗
PubMed1999

Cervical pregnancy--a conservative stepwise approach.

A case of cervical pregnancy resistant to intramuscular methotrexate therapy is presented, which was successfully treated by intra-arterial methotrexate followed by selective prophylactic hypogastric artery embolization to avoid aggravating the vaginal bleeding. It is suggested that, in cervical pregnancies in which fertility preservation is desired, a stepwise conservative approach should be applied before resorting to surgical intervention.

Adult↗
PubMed1999

Pelvic abnormalities in hysterectomized patients-role of early postoperative ultrasonographic evaluation.

OBJECTIVE: To assess the incidence of post-hysterectomy pelvic fluid collection in the early postoperative period and to study its natural history. STUDY DESIGN: Cross-sectional, prospective, observational study. PATIENTS AND METHODS: The study sample comprised 36 consecutive patients undergoing hysterectomy for benign conditions in our department. All patients underwent two pelvic ultrasonographic examinations, the first on the third postoperative day and the second one year later. All postoperative complications were thoroughly evaluated. RESULTS: Thirty-two patients completed the study evaluations. Abnormal ultrasonographic findings were detected in 4 of them on the early postoperative scan. Three (9.4% of the sample) had pelvic fluid collections which persisted on the follow-up scan. The fourth patient had a simple ovarian cyst 4 cm in diameter which disappeared on follow-up. None of the patients with pelvic fluid collections had a febrile morbidity during the postoperative course. CONCLUSIONS: Transvaginal ultrasonography can detect asymptomatic early postoperative pelvic fluid collections and enables conservative management, thereby reducing patients stress, medical costs, and the need for unnecessary interventions.

Ascitic Fluid↗
PubMed1998

A second major native von Hippel-Lindau gene product, initiated from an internal translation start site, functions as a tumor suppressor.

The von Hippel-Lindau (VHL) tumor suppressor gene is inactivated in both sporadic and inherited clear cell renal carcinoma associated with VHL disease. We have identified two distinct native products of the human VHL gene, with apparent molecular masses of 24 and 18 kDa. The 18-kDa VHL protein was more abundant in nearly all cell lines examined. Reintroduction of the 18-kDa VHL gene product into renal carcinoma cells lacking wild-type VHL protein led to down-regulation of vascular endothelial growth factor (VEGF) mRNA and glucose transporter GLUT1 protein and suppressed tumor formation in nude mice. The 18-kDa VHL protein also demonstrated binding to elongins B and C. In an in vitro assay, the second in-frame AUG codon present in VHL mRNA was shown to be necessary and sufficient for production of the 18-kDa VHL protein, consistent with an internal translation mechanism. These data provide evidence for a second major VHL gene product, which contains the functional domains of the VHL gene. Moreover, these results indicate that internal translation initiation is an important mechanism for production of the major VHL protein.

Animals↗
PubMed1997

The detection of micrometastases in the peripheral blood and bone marrow of patients with breast cancer using immunohistochemistry and reverse transcriptase polymerase chain reaction for keratin 19.

The aim of this study was to determine whether reverse transcriptase polymerase chain reaction (RT-PCR) for keratin 19 (K19) provides additional information when combined with immunohistochemistry when used to detect micrometastases in blood and bone marrow in patients with primary breast cancer. We studied 78 patients with breast cancer who had no evidence of distant metastases. We collected blood and bone marrow, separated the mononuclear fraction and carried out RT-PCR and immunohistochemistry for K19. RT-PCR was done by two 40-cycle rounds using nested primers. In initial experiments, RT-PCR was shown to be capable of detecting one tumour cell in one million normal bone marrow cells, which was at least 10 times more sensitive than immunohistochemistry, while retaining specificity. Five per cent of the peripheral blood and 22% of the bone marrow samples contained K19 positive cells by immunohistochemistry staining. Using RT-PCR, these proportions increased to 25% and 35%, respectively. This represents a significantly greater detection frequency (P < 0.001 and P = 0.03, respectively). RT-PCR for K19 is a more sensitive method for detecting micrometastases in patients with primary breast cancer when compared with immunohistochemistry.

Adult↗
PubMed1997

Incisional hernias after laparoscopy.

Laparoscopy, using a two-puncture technique, has been used for a variety of gynecologic indications for more than two decades. The procedure is considered safe and effective, although rare complications, such as incisional hernias, have been reported. In this review, the issue of postlaparoscopic incisional hernias is discussed in terms of incidence, predisposing factors, time of appearance, and preventive measures. With the evolvement of operative laparoscopy, larger trocars and cannulas have been introduced, increasing the incidence of postlaparoscopic incisional hernias. Awareness of the possibility of this complication will lead to the use of proper surgical techniques, as suggested, while knowledge of the postoperative signs and symptoms will lead to early diagnosis and prevention of sequelae.

Female↗
PubMed1996

The impact of D-Trp6 LH-RH on plasma lipid levels.

BACKGROUND: There is increasing evidence regarding the correlation between the risk of death from cardiovascular disease and low levels of HDL-cholesterol or high plasma concentrations of LDL-cholesterol, total cholesterol, and triglycerides. Gonadotropin releasing hormone (GhRH) analogues are widely used in assisted reproduction programs. Therefore, it seems important to evaluate possible changes in serum lipoprotein levels following treatment with these compounds. PURPOSE: Our purpose was to assess possible lipoprotein changes following administration of the long-acting GnRH analogue, D-Trp6 luteinizing hormone-releasing hormone (LH-RH). DESIGN: Serum levels of cholesterol, HDL-cholesterol, LDL-cholesterol, and triglicerydes were determined before and after 6 weeks of treatment. RESULTS: No significant changes in either cholesterol or HDL-cholesterol, LDL-cholesterol, or triglicerydes following treatment with D-Trp6 LH-RH were demonstrated in the group of 25 patients investigated. CONCLUSIONS: Short-term use of D-Trp6 LH-RH is not associated with any significant change in plasma lipid levels. Further studies are still required with patients undergoing repeated treatment cycles, especially those who exhibit elevated pretreatment plasma lipid levels, to confirm the long-term safety of GnRH analogues with respect to lipid metabolism.

Arteriosclerosis↗
PubMed1996

The effect of surgical castration on lipid metabolism in premenopausal and postmenopausal women.

OBJECTIVE: To investigate the effect of endogenous estrogen on lipid and lipoprotein metabolism in premenopausal and postmenopausal women. DESIGN: Prospective randomized study. SETTING: Department of Obstetrics-Gynecology, Beilinson Medical Center and Tel-Aviv University Medical School, Israel. SUBJECTS: Twenty-seven women, 15 premenopausal and 12 postmenopausal, undergoing surgical castration (total abdominal hysterectomy and bilateral salpingo-oophorectomy). METHOD: Blood samples were drawn before the surgical intervention and after a 6-month interval. MAIN OUTCOME MEASURES: Assays were performed for estradiol, luteinising hormone and follicle-stimulating hormone, and triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol and total cholesterol/HDL as well as HDL/LDL ratio. RESULTS: No significant differences were found in both groups, before castration and after 6 months. A modest, but statistically significant, rise in triglycerides was observed in the premenopausal group. CONCLUSIONS: The serum lipid and lipoprotein profile encountered in premenopausal and postmenopausal women were unchanged 6 months after surgical castration. The clinical significance indicates that the effect of endogenous estrogen on lipid metabolism is doubtful and should be further investigated.

Adult↗
PubMed1996

Keratin 19 mRNA measurement to detect micrometastases in lymph nodes in breast cancer patients.

We have used polymerase chain reaction (PCR) to measure keratin 19 mRNA in order to detect breast cancer cells invading axillary lymph nodes. In a consecutive series of 125 patients with primary breast cancer, 75 patients had no evidence of lymph node involvement by conventional histology. A total of 530 lymph nodes from these patients were examined and 106 (20%) gave a keratin 19 product detectable by Southern hybridisation. This correlated with primary tumour size (P<0.001). These 106 nodes came from 23 patients. Thus, using this technique, 23/75 (30.6%) patients were found to have evidence of lymph node involvement who would otherwise have been designated lymph node negative.

Adult↗
PubMed1996

The effects of time interval after venipuncture and of anticoagulation on platelet adhesion and aggregation.

Abnormal platelet function plays an important role in atherosclerosis and thrombotic disorders. Simple in vitro testing of platelet function is preferable to other techniques, and adhesion measurement is especially important because it reflects an immediate platelet response. The time lapse after venipuncture and the anticoagulant may affect platelet function in an as yet unknown way. A method for determining platelet adhesion under controlled whole blood flow conditions and an aggregation study were used. Platelet adhesion and aggregation changed significantly with time elapsed since venipuncture, peaking after 60 min (P < 0.05): a plateau was reached only after more than 120 min. Platelet adhesion was directly suppressed by the use of sodium citrate as an anticoagulant, and surface density decreased from 14.2 to 8.8 (P < 0.001). To prevent the effect of time after venipuncture on platelet function, testing should be performed at the plateau phase.

Adenosine Diphosphate↗
PubMed1996

Prostaglandin metabolism in the yolk sacs of normal and diabetic pregnancies.

The malformations commonly found in fetuses of diabetic mothers occur before the 7th week of pregnancy, when fetal nutritional needs are met largely by the yolk sac. The diabetic milieu has been hypothesized to cause a disruption in the metabolism of arachidonic acid and phosphatidylinositol turnover, leading to a reduction in prostaglandin levels. In this study we evaluated how the diabetic milieu affects yolk-sac prostaglandin levels. We used ultrasound to characterize and guide aspiration of the yolk sacs of eight diabetic and 12 healthy women prior to elective abortion. In addition, we studied the yolk sacs of two healthy women in whom pregnancy termination was carried out by hysterectomy. All fetuses were between 8 and 10 weeks gestational age at the time of pregnancy termination. The yolk-sac prostaglandin E2 levels were measured using radioimmunoassay. We found that the yolk-sac diameters of diabetic women were 1.2 mm larger than those of normal women. Furthermore, the mean prostaglandin E2 level in healthy women was 3605 pg/ml, whereas prostaglandin was undetected in all the yolk sacs of diabetic women (p < 0.001). While this study suggests that defective yolk-sac metabolism of prostaglandins is one of the mechanisms responsible for diabetic embryopathy, further research is necessary to place yolk-sac enlargement and the role of prostaglandins in perspective.

Adult↗