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Biomedical subjects

Michal Barak

Publications and source records attributed to Michal Barak.

15 recordsLinked to original sources
PubMed2006

Quantitative analysis of clonal bone marrow CD19+ B cells: use of B cell lineage trees to delineate their role in the pathogenesis of light chain amyloidosis.

Light chain amyloidosis (AL) is a bone marrow (BM) plasma cell neoplasia with systemic deposition of Ig light chain amyloid fibrils. Here, we report the identification of clonal CD19 B cells in the BM and the use of a novel mathematical algorithm to generate B cell lineage trees of the clonal CD19 B cells and CD138 plasma cells from the BM of AL patients to delineate the relationship between these two clonal populations. The CD19+ clonal B cells in the BM of AL patients related to the clonal plasma cells represent a pre-plasma cell precursor population. The B cell lineage trees from AL patients also show significant differences in clonal diversification and antigenic selection compared to clones from normal, healthy controls. These data provide a robust example of the use of graphical quantification methods in delineating the role of neoplastic precursors in the pathogenesis of hematopoietic malignancies.

Algorithms↗
PubMed2006

ACC/AHA guidelines for preoperative cardiovascular evaluation for noncardiac surgery: a critical point of view.

This review examines the issue of preoperative cardiac evaluation from a critical point of view, based on recent medical literature. We reviewed the history of that field and focused on the American College of Cardiology and American Heart Association guidelines, which are a cornerstone in the field of cardiac patients undergoing noncardiac surgery. These guidelines synthesized the data into a comprehensive format and established the concept of integrating the patient's risk with the surgical risk. Nevertheless, there are some weaknesses in the guidelines. We believe that a better understanding of the guideline limitations will allow an improved and more educated practice of its recommendations.

American Heart Association↗
PubMed2006

Prolonged international normalized ratio correlates with a large intravascular fluid balance after major abdominal surgery.

We performed a prospective randomized study of 32 patients who had undergone pancreaticoduodenectomy and did not receive blood during and after surgery. The patients were prospectively assigned to two groups related to fluid balance in the immediate postoperative period. Group 1 (14 patients) were maintained at a positive intravascular fluid balance of 0-1000 mL; Group 2 (18 patients) were maintained at a positive balance of 1000-2000 mL. Complete blood counts and coagulation tests (International Normalized Ratio) and activated partial thromboplastin time (aPTT) were performed at three time points: the day before surgery, on arrival at the postanesthesia care unit, and on leaving the postanesthesia care unit (16 h later). There were significant differences in International Normalized Ratio values between the groups with deterioration during the time they were in the postanesthesia care unit but not in aPTT values. Positive correlation was found between the amount of positive fluid balance and International Normalized Ratio prolongation, but not with aPTT, suggesting that restricted intravascular fluid balance is beneficial for preservation of coagulation after major abdominal surgery.

Aged↗
PubMed2005

Immunoglobulin variable-region gene mutational lineage tree analysis: application to autoimmune diseases.

Lineage trees have frequently been drawn to illustrate diversification, via somatic hypermutation (SHM), of immunoglobulin variable-region (IGV) genes. In order to extract more information from IGV sequences, we developed a novel mathematical method for analyzing the graphical properties of IgV gene lineage trees, allowing quantification of the differences between the dynamics of SHM and antigen-driven selection in different lymphoid tissues, species, and disease situations. Here, we investigated trees generated from published IGV sequence data from B cell clones participating in autoimmune responses in patients with Myasthenia Gravis (MG), Rheumatoid Arthritis (RA), and Sjögren's Syndrome (SS). At present, as no standards exist for cell sampling and sequence extraction methods, data obtained by different research groups from two studies of the same disease often vary considerably. Nevertheless, based on comparisons of data groups within individual studies, we show here that lineage trees from different individual patients are often similar and can be grouped together, as can trees from two different tissues in the same patient, and even from IgG- and IgA-expressing B cell clones. Additionally, lineage trees from most studies reflect the chronic character of autoimmune diseases.

Arthritis, Rheumatoid↗
PubMed2005

Microbubbles: pathophysiology and clinical implications.

Gas embolism is a known complication of various invasive procedures, and its management is well established. The consequence of gas microemboli, microbubbles, is underrecognized and usually overlooked in daily practice. We present the current data regarding the pathophysiology of microemboli and their clinical consequences. Microbubbles originate mainly in extracorporeal lines and devices, such as cardiopulmonary bypass and dialysis machines, but may be endogenous in cases of decompression sickness or mechanical heart valves. Circulating in the blood stream, microbubbles lodge in the capillary bed of various organs, mainly the lungs. The microbubble obstructs blood flow in the capillary, thus causing tissue ischemia, followed by inflammatory response and complement activation. Aggregation of platelets and clot formation occurs as well, leading to further obstruction of microcirculation and tissue damage. In this review, we present evidence of the biological and clinical detrimental effects of microbubbles as demonstrated by studies in animal models and humans, and discuss management of the microbubble problem with regard to detection, prevention, and treatment.

Blood Coagulation↗
PubMed2005

Parathyroid hormone response to tracheal intubation in hyperparathyroid patients and normal subjects.

The stress of direct laryngoscopy and passing an endotracheal tube through the vocal cords elicits haemodynamic, metabolic and hormonal changes such as raising blood catecholamine levels. Catecholamines are known stimulants of PTH secretion. The effect of tracheal intubation on plasma parathyroid hormone levels has not yet been investigated. We monitored changes in plasma parathyroid hormone levels before and after tracheal intubation in 72 hyperparathyroid patients undergoing elective parathyroidectomy for primary and secondary hyperparathyroidism. These findings were compared to data collected from 20 subjects who underwent elective surgery (thyroidectomy or laparoscopic cholecystectomy) under general anesthesia. In the control group, tracheal intubation significantly increased plasma parathyroid hormone levels from 59 +/- 31 pg/ml to 91 +/- 40 pg/ml (mean +/- SD) (p<0.0003). In primary hyperparathyroid patients, the identical procedure increased plasma parathyroid hormone levels from 206 +/- 104 pg/ml to 217 +/- 113 pg/ml (p = 0.12) and from 898 +/- 495 pg/ml to 1162 +/- 613 pg/ml (p = 0.07) in secondary hyperparathyroidism patients. We concluded that tracheal intubation raises plasma parathyroid hormone levels. The mechanism underlying this response requires further investigation.

Adolescent↗
PubMed2005

Minimally invasive surgery for treatment of hyperparathyroidism.

BACKGROUND: Minimal invasive surgery for parathyroidectomy has been introduced in the treatment of hyperparathyroidism. OBJECTIVE: To evaluate the contribution of the sestamibi-SPECT (MIBI) localization, cervical ultrasonography, and intraoperative rapid turbo intact parathormone assay in minimal invasive parathyroidectomy. METHODS: Between August 1999 and March 2004, 146 consecutive hyperthyroid patients were treated using the MIBI and ultrasound for preoperative localization and iPTH measurements for intraoperative assessment. RESULTS: Parathyroid adenoma was detected in 106 patients, primary hyperplasia in 16, secondary hyperplasia in 16, tertiary hyperplasia in 5, and parathyroid carcinoma in 1 patient. Minimal invasive exploration of the neck was performed in 84 of the 106 patients (79.2%) with an adenoma, and in 17 of them this procedure was performed under local cervical block anesthesia in awake patients. Adenoma was correctly diagnosed by MIBI scan in 74% of the patients, and by ultrasound in 61%. The addition of ultrasonography to MIBI increased the accuracy of adenoma detection to 83%. In 2 of the 146 patients (1.4%) iPTH could not be significantly reduced during the initial surgical procedure. Minimal invasive surgery with minimal morbidity, and avoiding bilateral neck exploration, was achieved in 79.2% of patients with a primary solitary adenoma. CONCLUSIONS: Preoperative localizationof the parathyroid gland by MIBI and ultrasound together with intraoperative iPTH measurements resulted in an overall cure rate of 98.6% for the entire series, The addition of ultrasound to the MIBI scan increased the accuracy of adenoma detection.

Adenoma↗
PubMed2004

Thoracic epidural local anesthetics are ineffective in alleviating post-thoracotomy ipsilateral shoulder pain.

OBJECTIVE: This study was conducted to estimate the incidence and clinical predictors of post-thoracotomy shoulder pain and to determine the effectiveness of thoracic epidural block in alleviating this pain. DESIGN: A prospective clinical trial. SETTING: University teaching hospital. PARTICIPANTS AND INTERVENTIONS: Thirty-two adult patients undergoing elective thoracic surgery consented to participate in the study. All operations were open thoracotomies done by the same team of surgeons and anesthesiologists. A thoracic (T6) epidural catheter was placed before induction of general anesthesia. Each patient received 7 mL of lidocaine 2% epidurally and repeated doses of 5 mL of lidocaine 2% every half hour during the operation. Postoperatively, the occurrence of incision or ipsilateral shoulder pain was observed and treated with a maximal dose of 5 mL of lidocaine 2%. If ineffective, indomethacin suppository (nonsteroidal anti-inflammatory drug [NSAID]) was given. Variables such as patient's age, sex, American Society of Anesthesiologists physical status, type, site and duration of surgery, duration of anesthesia, the resection of main bronchus, and the use of thoracostomy tubes were recorded. MEASUREMENTS AND MAIN RESULTS: Postoperatively, 10 patients (31%) had shoulder pain, 4 patients (12.5%) complained of incision pain, and 2 (6.3%) complained of both incision and shoulder pain. A bolus of 5 mL of lidocaine 2% in the epidural catheter relieved incision pain in all the patients, but was ineffective for shoulder pain. Indomethacin suppository was effective in these patients. No correlation was found between any variable and the occurrence of shoulder pain. CONCLUSIONS: It is concluded that post-thoracotomy shoulder pain is a common problem, and the previously mentioned variables did not predict its appearance. Thoracic epidural block is effective in the treatment of incision but not shoulder pain. The NSAID indomethacin suppository was found to be effective for that problem.

Analgesia, Epidural↗
PubMed2004

Retroperitoneal hematoma after spinal anesthesia with the paramedian approach.

UNLABELLED: We present a case of a patient who developed a retroperitoneal bleeding after spinal anesthesia using 22-gauge Quincke needle, with the paramedian approach. Two attempts were needed to accomplish the block. Four hours later the patient complained of back pain radiating to her left calf, with weakness of the quadriceps muscle. Computed tomography revealed a large retroperitoneal hematoma from bleeding lumbar artery. Angiography failed to demonstrate the vessel. The patient was transfused with packed red blood cells and recovered gradually. She had normal coagulation tests throughout the event. IMPLICATIONS: We describe a case of a large retroperitoneal hematoma after the placement of an uneventful spinal block. The patient required four units of packed red blood cells despite having normal coagulation profiles throughout the event. The diagnosis and treatment of retroperitoneal hematoma are discussed.

Amputation, Surgical↗
PubMed2004

Cardiorespiratory parameters during conventional or gasless gynecological laparoscopy under general or regional anesthesia.

BACKGROUND: Conventional laparoscopy is aided by CO2 insufflation, which may impair the cardiorespiratory system and have life-threatening implications. This procedure is conducted under general anesthesia (GA). Gasless laparoscopy supposedly eliminates most of those disadvantages, but is technically more difficult to perform. In the present study, we compared cardiorespiratory parameters of conventional abdominal laparoscopy under GA to gasless laparoscopy under general or epidural anesthesia. MATERIAL/METHODS: This is a prospective study. Twenty four healthy female patients undergoing gynecological laparoscopies lasting <90 min were randomly assigned to one of three groups: group 1, conventional laparoscopy under GA; group 2, gasless laparoscopy under GA; and group 3, gasless laparoscopy under epidural anesthesia. Cardiorespiratory parameters and length of operative, postanesthesia care unit (PACU), and hospitalization periods as well as analgesic requirements in the PACU and complications in the operative and postoperative periods were recorded. RESULTS: No significant differences were detected between groups throughout the operative and postoperative periods, except for a rise in CO2 in group 1 and a lower analgesic requirement in the PACU in group 3. CONCLUSIONS: General and regional anesthesia may be employed in gasless laparoscopy for gynecological surgery.

Adult↗
PubMed2003

Hemodynamic and catecholamine response to tracheal intubation: direct laryngoscopy compared with fiberoptic intubation.

STUDY OBJECTIVE: To compare the stress response following tracheal intubation using direct laryngoscopy to that using fiberoptic bronchoscopy technique. DESIGN: Randomized, prospective study. SETTING: Operating rooms in a teaching hospital. PATIENTS: 51 ASA physical status I and II patients who were scheduled for an elective surgery with general anesthesia. INTERVENTIONS: Patients were randomly assigned to receive either direct laryngoscopy or fiberoptic orotracheal intubation, as part of general anesthesia. A uniform protocol of anesthetic medications was used. MEASUREMENTS: Blood pressure and heart rate were measured before induction, before endotracheal intubation, and 1, 2, 3, and 5 minutes afterwards. Catecholamine (epinephrine and norepinephrine) blood samples were drawn before the induction, and 1 and 5 minutes after intubation. MAIN RESULTS: Duration of intubation was shorter in the direct laryngoscopy group (16.9 (16.9 +/- 7.0 sec, range 8 to 40) compared with the fiberoptic intubation group (55.0 +/- 22.5 sec, range 29 to 120), p < 0.0,001. In both groups, blood pressure and heart rate were significantly increased at 1, 2, and 3 minutes after intubation, but there was no significant difference between the two study groups. Catecholamine levels did not increase after intubation and did not correlate with the hemodynamic changes. CONCLUSIONS: The use of either direct laryngoscopy or fiberoptic bronchoscopy produces a comparable stress response to tracheal intubation. Catecholamine levels do not correlate with the hemodynamic changes.

Adult↗
PubMed2003

Rapid atrial fibrillation following tube thoracostomy insertion.

We report a case of trauma patient, whose heart rhythm and rate changed from sinus tachycardia to rapid atrial fibrillation. The change occurred immediately after the insertion of left thoracostomy tube. The patient did not respond to pharmacological treatment. Only when the tube was pulled out, the rhythm returned to sinus. Chest radiogram shows the position of the tube, in close proximity to the cardiac silhouette.

Adult↗
PubMedDate not supplied

Fluid administration during abdominal surgery influences on coagulation in the postoperative period.

OBJECTIVE: Postoperative coagulopathy is an important concern for patients after major surgery. Our objective was to define the factors that correlate with postoperative deterioration in coagulation. DESIGN: Retrospective clinical case study. SETTING: University hospital. PARTICIPANTS: Adult patients (n = 150), who underwent major abdominal surgery, were randomly chosen to participate in the study. For each patient, demographic and medical data, anesthetic information, type and duration of surgery, hemodynamic variables, fluid administration, as well as preoperative and postoperative prothrombin time and partial thromboplastin time were collected. Statistical analysis was used to determine which factors correlated with deterioration of coagulation tests. RESULTS: We found statistically significant correlation between deteriorating coagulation functions and administration of more than 3 l of crystalloids during abdominal surgery. There was also correlation between administration of more than 500 ml of colloid administration and elongation of protrombin time. The remainder of the above studied factors did not correlate with deteriorating coagulation. CONCLUSIONS: Administration of more than 3-l crystalloids or 500-ml colloids during abdominal surgery correlates with postoperative coagulopathy.

Abdomen↗