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Biomedical subjects

R Mohr

Publications and source records attributed to R Mohr.

At least 55 records · Page 3Linked to original sources
PubMed1995

Aprotinin improves hemostasis after cardiopulmonary bypass better than single-donor platelet concentrate.

Platelet transfusion and aprotinin administration improve platelet function and clinical hemostasis after extracorporeal circulation. To compare two methods of improving postoperative hemostasis, we preoperatively randomized 40 patients undergoing various open heart procedures into two groups. Group A included 20 patients who, immediately after bypass, received single-donor plateletpheresis concentrates collected from ABO-compatible donors (Baxter Autopheresis-C System). They were compared with 20 patients who received high-dose aprotinin (6 x 10(6) KIU) before and during cardiopulmonary bypass (group B). Group A patients showed significantly higher platelet count after single-donor plateletpheresis concentrate transfusion (157 +/- 36 x 10(9)/L compared with 118 +/- 42 x 10(9)/L (p < 0.05). However, platelet aggregation on extracellular matrix was better in group B (3.4 +/- 0.7 versus 2.8 +/- 0.9; p < 0.05). Total 24-hour blood loss and exposure to homologous blood products were significantly less in group B (396 +/- 125 mL and 1.1 +/- 1.6 units compared with 617 +/- 233 mL and 5.4 +/- 3.4 units; p < 0.01). Despite higher platelet count in patients after single-donor plateletpheresis concentrates transfusion, hemostasis in patients receiving aprotinin is better due to improved platelet function.

Aprotinin↗
PubMed1995

Coronary artery bypass without cardiopulmonary bypass: analysis of short-term and mid-term outcome in 220 patients.

Two hundred twenty patients, preferentially those with high-risk conditions, underwent coronary artery bypass grafting without cardiopulmonary bypass. Early unfavorable outcome events included operative mortality (7 patients, 3.2%), nonfatal perioperative myocardial infarction (6 patients, 2.7%), cerebrovascular accident (1 patient, 0.4%), and sternal infection (3 patients, 1.4%). There were two deaths (13%) among 15 patients with calcified aorta and four (12%) in 33 patients who underwent emergency operation. Multivariate analysis revealed these two risk factors to be the only predictors of early mortality (odds ratios, 8.0 and 9.8, respectively). Preoperative risk factors such as left ventricular dysfunction (ejection fraction < or = 35%) (40 patients, 18%), congestive heart failure (46 patients, 21%), acute myocardial infarction (59 patients, 27%), cardiogenic shock (7 patients, 3%), age 70 years or older (59 patients, 27%), renal failure (19 patients, 9%), and cerebrovascular accident and carotid disease (11 patients, 5%) were not found to be major predictors of early mortality or unfavorable outcome. During 12 months of follow-up (range 1 to 21 months), there were four cardiac and three noncardiac deaths (1-year actuarial survival 93%) and 17 cases (7.7%) of early return of angina. Calcified aorta, nonuse of the internal mammary artery, reoperation, and diabetes mellitus were independent predictors of unfavorable events. We conclude that coronary artery bypass grafting without cardiopulmonary bypass can be done with relatively low operative mortality, although there seems to be an increased risk for early return of angina. This procedure should therefore be considered for patients with appropriate coronary anatomy, in whom cardiopulmonary bypass poses a high risk. This procedure is still hazardous with calcified aorta or emergency operation.

Adult↗
PubMed1995

Irradiation of fresh whole blood for prevention of transfusion-associated graft-versus-host disease does not impair platelet function and clinical hemostasis after open heart surgery.

Since our previous studies suggested that the transfusion of 1 unit fresh whole blood (FWB) after cardiopulmonary bypass (CPB) using a bubble oxygenator may provide hemostatic benefit equivalent to 8-10 units of platelet concentrates, we have routinely used FWB at the termination of CPB. Two patients who received FWB and developed transfusion-associated graft-versus-host disease (TA-GVHD) prompted us to investigate the effect of irradiation of FWB on platelet and clinical hemostasis. Twenty-four patients were randomized to receive either 1 unit FWB (12 patients), or 1 unit irradiated FWB (IrFWB, 1,500 cGy,12 patients) after CPB. Platelet aggregation on extracellular matrix, studied by a scanning electron microscope and graded from 1 to 4 (from poor to excellent aggregation), was similar in both groups preoperatively [3.3 +/- 0.9 (FWB) and 3.5 +/- 0.5 (Ir FWB)], and at the end of CPB [1.8 +/- 1.2 (FWB) and 1.9 +/- 0.9 (IrFWB)]. Platelet aggregation was similar after transfusion of FWB (3.0 +/- 1.0) and after IrFWB (3.2 +/- 0.8), as was the increase in platelet count. Twenty-four hours total postoperative bleeding was similar (560 +/- 420 and 523 +/- 236 ml for FWB and IrFWB, respectively). We conclude that irradiation of FWB for prevention of TA-GVHD does not impair platelet aggregating capacity, and can be used when blood is donated by the patient's next of kin.

Aged↗
PubMed1994

Transcriptional activation of a ras-like gene (kir) by oncogenic tyrosine kinases.

We report the characterization of a member of the ras gene family that is overexpressed in cells transformed by abl tyrosine kinase oncogenes. The gene, named kir (for kinase-inducible ras-like), is induced at the transcriptional level. kir mRNA has a rapid turnover and encodes a protein of 33 kDa with guanine nucleotide-binding activity but undetectable intrinsic GTPase activity. kir was cloned by differential screening of genes present in fully malignant versus growth factor-independent cell lines expressing wild-type or mutant forms of BCR/ABL. BCR/ABL and v-Abl induce transcription of the kir gene via specific signaling pathway(s), but kir overexpression alone is not sufficient to mediate transformation.

3T3 Cells↗
PubMed1994

Coronary artery by-pass without cardiopulmonary by-pass for patients with severe left ventricular dysfunction.

OBJECTIVES: To evaluate results of coronary artery bypass grafting (CABG) without cardiopulmonary by-pass (CPB) for patients with severe left ventricular dysfunction. MATERIALS AND METHODS: Fifty-three patients with severe LV dysfunction (EF < 35%) underwent CABG without cardiopulmonary by-pass (CPB) between December 1991 and December 1993. They comprise 22% of 242 patients operated on without CPB by one of the authors (RM) in this period. There were 45 (85%) males and eight (15%) females. Twelve (23%) patients were over 70 years. Nine (17%) were re-do CABG. Ten (19%) were referred for operation within the first 24 hours of evolving MI, and 13 (25%) up to two weeks after acute MI. Nine (17%) had preoperative EF < 20%, and six patients (11%) were in cardiogenic shock. Mean number of grafts/pt was 1.8 and IMA was used in 41 (77%). Only 14 patients (26%) received a graft to a circumflex marginal artery. Ischemic time was 8 +/- 4 min/graft (mean +/- SD) when anastomosed to the LAD or RCA, and 14 +/- 7 min/graft when anastomosed to a marginal branch. RESULTS: One patient (1.9%) died perioperatively, and two (3.7%) suffered a non-fatal MI. At two-year follow-up there were three late deaths, one of them from cancer. Three patients had return of angina, two of them were reoperated upon. CONCLUSIONS: These results suggest that CABG without CPB may be advantageous for patients with severe LV dysfunction.

Adult↗
PubMed1994

Coronary by-pass reoperations without cardiopulmonary by-pass: the Israeli experience.

OBJECTIVES: To evaluate results of coronary artery by-pass grafting (CABG) reoperations without cardiopulmonary by-pass (CPB). MATERIALS AND METHODS: Thirty-two patients underwent CABG reoperation with CPB between December 1991 and December 1993. There were 29 (91%) males, and 3 (9%) females. Mean age was 62 +/- 7 years. Five (16%) were operated on emergently, two (6%) of them during cardiogenic shock. Three (9%) were referred for operation up to two weeks following acute MI. Six (19%) had preoperative EF < 35%. Significant associated systemic diseases included previous CVA in two patients (6%), calcified aorta in two (6%), peripheral vascular disease in six (19%), renal failure in one (3%), and severe COPD in one (3%). Mean number of grafts/pt was 1.5 (range 1-3), and IMA was used in 26 (81%) of patients. Only nine patients (28%) received a graft to a circumflex marginal artery, six (66%) of whom were operated on through left thoracotomy. RESULTS: Only two patients (6%) had low output syndrome postoperatively; one was supported with catecholamines, and the other with intraaortic balloon pump. Hospital stay was 6.1 +/- 1.5 days (mean +/- SD). Early unfavorable outcome included operative death in one patient (3.1%), non-fatal MI in two (6%), and sternal infection in one (3%). Follow-up (10 +/- 5 months, mean +/- SD) showed two late deaths (one cardiac, and one carcinoma), one (3%) non-fatal MI, and return of angina in three (9%) patients. CONCLUSIONS: CABG reoperations without CPB should be considered, particularly for revascularization of the LAD and RCA systems. Left thoracotomy is optional for patients with disease confined to circumflex and LAD systems.

Aged↗
PubMed1993

Basaloid squamous cell carcinoma of floor of mouth.

BACKGROUND: Only five cases of basaloid squamous cell carcinoma (BSCC), a rare tumor of head and neck, have been reported to involve the floor of mouth. METHODS: Clinicopathologic and immunohistochemical features of eight BSCC of floor of mouth were studied to evaluate the significance of the basaloid features. RESULTS: Five patients were male and three were female. Their mean age was 52 years (range, 39-59). At presentation, one patient was diagnosed with Stage II disease, four were diagnosed with Stage III disease, and three were diagnosed with Stage IV disease. Aside from typical squamous differentiation, each patient had a component of basaloid cells arranged in irregular nests, cords, or pseudoglandular spaces with a brisk mitotic rate, myxoid stroma, and marked tendency for perineural invasion. A panel of immunostains yielded the following results: keratin, +8/8; carcinoembryonic antigen, +3/8; and S-100, chromogranin, and neuron-specific enolase were negative. Mucin stains were negative in all cases. Ultrastructural characterization of three BSCC revealed squamous differentiation of the basaloid cells and a peculiar basal membrane-like material in between them. No neurosecretory granules were present. Seven patients underwent surgery; six of them were also treated with postoperative radiation therapy. In two cases, chemotherapy was added at recurrence. One nonresectable patient received radiation and chemotherapy. At the last follow-up, five patients were dead of disease within 13 months from the diagnosis. One patient died of an unknown cause. Two patients were still alive at the time of this report, 4 and 2 months after treatment. Seven patients had recurrent disease. The authors compared these data with a control group of patients with conventional squamous cell carcinoma (SCC). CONCLUSIONS: The authors' results indicate that BSCC of floor of mouth is an aggressive variant of SCC and is prognostically worse than the conventional SCC, regardless of the grade of the latter.

Adult↗
PubMed1993

Platelet protection by low-dose aprotinin in cardiopulmonary bypass: electron microscopic study.

To evaluate the effect of low-dose aprotinin during cardiopulmonary bypass on platelet function and clinical hemostasis, 30 patients undergoing various cardiopulmonary bypass procedures employing bubble oxygenators were randomized to receive either low-dose aprotinin (2 x 10(6) KIU in the cardiopulmonary bypass priming solution, 15 patients [group A]) or placebo (15 patients [group B]). Blood samples were collected before and after cardiopulmonary bypass to assess platelet count and aggregation on extracellular matrix, which was studied by a scanning electron microscope. On a scale of 1 to 4 preoperative mean platelet aggregation grades were similar in both groups (3.8 +/- 0.5 and 3.5 +/- 0.5 for groups A and B, respectively). Postoperatively, platelet aggregation on extracellular matrix decreased slightly in group A (2.8 +/- 1.3; p < 0.01) and significantly in group B (1.3 +/- 0.5; p < 0.001). Eleven of the 15 patients in group A remained in aggregation grade 3 or 4 compared with none of the group B patients. Platelet count was similar in both groups preoperatively and postoperatively. Total 24-hour postoperative bleeding and blood requirement were lower in the aprotinin group (487 +/- 121 mL and 2.3 +/- 1.0 units) than in the placebo group (752 +/- 404 mL and 6.8 +/- 5.1 units; p < 0.01). These results show that the use of low-dose aprotinin during cardiopulmonary bypass provides improved postoperative hemostasis, which might be related to the protection of the platelet aggregating capacity.

Aged↗
PubMed1993

Tricuspid valve surgery: recent experience at the Chaim Sheba Medical Center.

From 1 January 1989 to 30 June 1992, 35 patients underwent cardiac surgery that included a tricuspid valve (TV) procedure. All had severe TV dysfunction documented by echocardiography, and were in NYHA functional class III-IV. The etiology of TV dysfunction was rheumatic-functional in 19 patients, rheumatic-organic in 13, and infective in 3. Nineteen (54%) had had at least one previous cardiac operation, and in 29 an associated procedure (MVR, AVR, DVR, DVR + CABG) had been performed. The TV was repaired in 27 patients, was replaced by a bioprosthesis in 7, and was excised in 1. There were three (8.6%) operative and two late deaths. Except for two, all surviving patients are in NYHA functional class I-II. In two patients with organic lesions who underwent repair, residual moderate tricuspid regurgitation was observed. We conclude that in these critically ill patients TV surgery can be performed with acceptable results. Long-term fate of a bioprosthesis in the tricuspid position is yet to be determined.

Adult↗
PubMed1992

Platelet protection by aprotinin in cardiopulmonary bypass: electron microscopic study.

To evaluate the functional integrity of platelets in patients administered the proteinase inhibitor aprotinin during cardiopulmonary bypass, 20 patients undergoing a complicated and prolonged open heart operation were studied. They were randomized to receive either a high dose of aprotinin (total dose, 6 to 7 x 10(6) KIU) before and during cardiopulmonary bypass (10 patients) or a placebo (10 patients). Blood samples were collected preoperatively, at the termination of bypass, and 90 minutes thereafter to assess platelet count and aggregation on extracellular matrix, which was studied by scanning electron microscopy. On a scale of 1 to 4, mean preoperative platelet aggregation grades were similar in both groups (3.5 +/- 0.5). Postoperatively, at the termination of cardiopulmonary bypass and 90 minutes thereafter, all 10 patients treated with aprotinin revealed normal, unchanged platelet aggregation (grade, 3.5 +/- 0.5), whereas all placebo-treated patients showed severely disturbed aggregation (grade, 1.4 +/- 0.5) (p less than 0.001). The platelet count was similar in both groups before and after operation (preoperatively, 182 +/- 75 x 10(9)/L and 146 +/- 30 x 10(9)/L, and postoperatively, 87 +/- 13 x 10(9)/L and 80 +/- 27 x 10(9)/L for the aprotinin and placebo groups, respectively). Total 24-hour postoperative bleeding and blood requirement were significantly lower in the aprotinin group (371 +/- 84 mL and 2 +/- 0.7 units, respectively) compared with the placebo group (608 +/- 28 mL and 3.4 +/- 1.3 units, respectively) (p less than 0.01). These results demonstrate that improved postoperative hemostasis is directly related to the complete preservation of platelet function achieved by the protective properties of aprotinin.

Adult↗
PubMed1992

Fresh blood units contain large potent platelets that improve hemostasis after open heart operations.

Twenty units of fresh whole blood were separated into fresh packed red blood cells (PC) and platelet-rich plasma (PRP) and were transfused to 40 patients immediately after coronary bypass grafting. Patients were preoperatively randomized to receive either PRP (group A, 20 patients) or PC (group B, 20 patients). Platelet number in the PRP group was greater, but not significantly greater, than in the PC group (7.5 +/- 3 versus 5.9 +/- 2.2 x 10(10); p = not significant). However, mean platelet volume in the PC group was significantly greater (8.75 +/- 1.1 versus 6 +/- 0.7 fL). Postoperatively, group A patients bled more than group B (566 +/- 164 versus 327 +/- 41 mL; p less than 0.01) and received more red blood cell units (2.7 +/- 1.2 versus 1.6 +/- 0.7 U; p less than 0.05) and a larger number of blood products (5.9 +/- 3.7 versus 2.6 +/- 1.2 U; p less than 0.05). Transfusion of PRP to group A increased platelet count from 128 +/- 20 to 148 +/- 110 x 10(9)/L; however, platelet functions did not improve. Administration of PC to group B increased platelet count from 139 +/- 22 to 156 +/- 23 x 10(9)/L, improved platelet aggregation (with collagen from 33% +/- 20% to 53% +/- 23%, with epinephrine from 36% +/- 24% to 51% +/- 20%; p less than 0.05), and corrected the prolonged bleeding time. The results suggest that the improved hemostasis observed after fresh whole blood administration is related to the large, potent platelets that remained in the PC and were not separated to the PRP during standard platelet concentrate preparation.

Blood↗
PubMed1992

Correlation between myocardial ischemia and changes in arterial resistance during coronary artery bypass surgery.

The arterial resistometer provides continuous on-line monitoring of changes in arterial resistance. Resistance index (Ri), which bears a direct relationship to systemic vascular resistance (SVR), is defined by the equation Ri = P'/(dP'/dt), where dP'/dt is the peak dP/dt of the arterial waveform, and P' is the pressure at dP'/dt. In 42 patients with unstable angina, changes in Ri were studied at six periods during aortocoronary bypass surgery before tracheal intubation, during tracheal intubation, leg elevation, presternotomy, sternotomy, and dissection of the internal mammary artery. Thirty-four episodes of ischemia (0.1 mV ST segment changes) were observed in 26 patients. All ischemic episodes were associated with increased Ri (mean increase, 102 +/- 52%). Elevation of the pulmonary capillary wedge pressure correlated with ischemia during the preintubation, intubation, and sternotomy periods, but not in the remaining periods. Changes in arterial pressure and heart rate were not good predictors of ischemia. The prevalence of ST segment changes increased markedly during all periods of anesthesia with increase in Ri (P less than 0.05). Ninety-one percent of ST segment changes were associated with a 25% increase from the baseline Ri. Raising the cutoff point to a greater than or equal to 75% increase in Ri improved the specificity of Ri in ischemia detection from 61% to 92%. An increase of greater than or equal to 75% in Ri occurred in only 8% of cases without ST segment changes. It was found that an increase in Ri as depicted by the arterial resistometer was the best hemodynamic correlate of myocardial ischemia.

Adult↗
PubMed1992

Aprotinin prevents cardiopulmonary bypass-induced platelet dysfunction. A scanning electron microscope study.

BACKGROUND: Administration of aprotinin during extracorporeal circulation reduces blood loss and improves platelet function. METHODS AND RESULTS: To evaluate the protective effect of aprotinin on platelets, 50 patients undergoing cardiopulmonary bypass were randomized before surgery to one of three groups. Seventeen patients (group A) received continuous high-dose aprotinin (7 x 10(6) KIU) during cardiopulmonary bypass, 17 (group B) received a single bolus of aprotinin in the pump prime (2 x 10(6) KIU), and 16 (group C) received placebo. Scanning electron microscopy was used to evaluate platelet aggregation on extracellular matrix. The platelet function was graded from 1 to 4, with grade 4 being normal aggregation. Immediately after cardiopulmonary bypass, 16 patients in group A (94%) reached preoperative aggregation grade (mean grade, 3.4 +/- 0.7) compared with nine of 17 in group B (52%) (mean grade, 2.9 +/- 1.2), and none in group C (0%) (mean grade, 1.4 +/- 0.5; p < 0.001). Postoperative platelet count did not differ significantly among the three groups. After surgery, group A bled less than groups B and C (395 +/- 120 versus 488 +/- 135 and 780 +/- 408 ml, respectively; p < 0.01). Patients in the aprotinin groups received fewer red blood cell units (0.9 +/- 1.2 and 1.9 +/- 1.2 versus 3.4 +/- 1.9, respectively; p < 0.01) and were exposed to less homologous blood products (1.3 +/- 1.7 and 2.1 +/- 1.1 versus 6.1 +/- 5, respectively; p < 0.001). CONCLUSIONS: By preserving platelet function, aprotinin improves postoperative hemostasis in all patients who receive high dose and in most who receive low dose.

Aprotinin↗
PubMed1992

Synergism between infarct-borne left ventricular dysfunction and cardiomegaly in increasing the risk of coronary bypass surgery.

The effect of cardiomegaly on operative and late mortality in patients with left ventricular dysfunction undergoing coronary bypass operation was investigated. The study group consisted of 178 patients whose left ventricular ejection fraction was below 45% and who were operated on from 1978 through 1985. Forty-five patients (group A) had severe left ventricular dysfunction (ejection fraction < 30%) and 133 (group B) had moderate dysfunction (30% > ejection fraction > 45%). Twenty-four of group A (53%) and 54 of group B (41%) patients had cardiomegaly (cardiothoracic ratio on chest x-ray films > 0.5). There were 10 (6%) hospital deaths, four in group A (9%) and six in group B (4.5%). All four deaths in group A and the six deaths in group B were patients who had cardiomegaly. Regardless of the severity of the left ventricular dysfunction, there was no operative death among patients with normal heart size (p < 0.001). Age over 65, bypass time longer than 2 hours, and incomplete revascularization emerged as risk factors. Follow-up ranged from 5 to 13 years (mean 7.8 years). Overall 5-year actuarial survival, including hospital mortality, was 80% +/- 3%. Reduced 5-year survival was observed in patients with cardiomegaly (67% +/- 5% versus 91% +/- 3%, p < 0.05). Five- and 10-year survival of patients from group A with cardiomegaly was 53% +/- 7% and 18% +/- 13%, respectively.

Cardiomegaly↗