Biomedical subjects

M Sobel

Publications and source records attributed to M Sobel.

At least 91 records · Page 5Linked to original sources

PubMed1990

Symptomatic abdominal aortic aneurysms in long-term survivors of cardiac transplantation.

Herein we report the only two long-term survivors of cardiac transplantation who underwent successful repair of symptomatic abdominal aortic aneurysms since the advent of cyclosporine therapy in 1983. Review of the world's literature indicates that the only two recorded cases of repair of symptomatic abdominal aortic aneurysms after cardiac transplantation occurred before the use of cyclosporine. The presentation and clinical course of our patients recently treated are presented, and perioperative care and immunosuppressive management are outlined. As the number of long-term survivors after cardiac transplantation increases, the incidence of other atherosclerotic complications including abdominal aortic aneurysm is likely to become more common, requiring extended cardiovascular follow-up.

Aorta, Abdominal↗

PubMed1989

The effect of alignment of the implant on fractures of the patella after condylar total knee arthroplasty.

The results in thirty-six knees that had a fracture of the patella after a total condylar arthroplasty were reviewed, and were analyzed according to the type of fracture and the alignment of the implant and the limb. Most of the fractures occurred two years or less after the initial operation. Fourteen knees were rated fair or poor and twenty-two, good or excellent. None of the thirty-six implants had been aligned in the neutral range. In sixteen knees, the alignment had a minor variation from the neutral range--that is, the knees were in minor malalignment. In general, these knees had the least severe fractures and the best over-all results. All had a good or excellent result except one, which was revised because of a loose patellar component. That knee was rated as fair at the latest follow-up. There was a major discrepancy in the alignment of twenty implants. These knees had more severe fractures and less satisfactory results than those in the other group. In two of these knees, the fracture was treated non-operatively; one had a good and the other, a poor result. Twelve of the remaining knees, which were treated surgically, were rated as fair or worse. Two knees that had revision of three components and restoration of alignment to the neutral range had an excellent result. The results of this study indicate that the alignment and fit of a component are important in determining the severity of a fracture of the patella after condylar total knee replacement and the long-term results after treatment of the fracture.

Adult↗

PubMed1989

Heparin-associated thrombocytopenia: observations on the mechanism of platelet aggregation.

We investigated the mechanism of heparin-mediated platelet aggregation in 11 patients with heparin-associated thrombocytopenia. Severe thrombocytopenia (16,000 to 66,000 platelets/microliters) developed in each patient during heparin therapy, and platelet aggregation occurred in vitro when heparin was added to mixtures of patient plasma and normal platelet-rich plasma. In 10 patients, heparin-initiated platelet aggregation was inhibited by preincubation of mixtures of normal platelet-rich plasma and heparin-associated thrombocytopenia plasma with monoclonal antiglycoprotein Ib antibodies 6D1 or LJ-Ib1. Both antibodies are directed against the von Willebrand factor binding site on glycoprotein Ib and inhibit only ristocetin-induced platelet agglutination. Purified immunoglobulin G (IgG) from patients with heparin-associated thrombocytopenia also supported heparin-induced aggregation, but equivalent amounts of antigen-binding fragments [F(ab')2] did not. We also found that F(ab')2 of LJ-Lb1 did not inhibit heparin-induced platelet aggregation but retained inhibitory activity against ristocetin-induced platelet agglutination. The monoclonal antibody 3G6, directed against the alpha-chain of glycoprotein Ib but not inhibitory of ristocetin-induced platelet agglutination, had no effect on heparin-induced platelet aggregation. Antibodies to von Willebrand factor that inhibit ristocetin-induced platelet agglutination did not inhibit heparin-mediated platelet aggregation, but antibodies to glycoprotein IIb-IIIa blocked aggregation. These data suggest that platelet aggregation in heparin-associated thrombocytopenia may be initiated by an interaction between patient IgG, heparin, and the platelet surface. Platelet activation appears to be mediated by a platelet surface crystallizable fragment (Fc) receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Heparin↗

PubMed1989

Total knee arthroplasty for the treatment of chronic hemophilic arthropathy.

Total knee arthroplasty (TKA) for hemophilic (factor VIII deficiency) arthropathy is a complex and demanding procedure with a high complication rate. However, the long-term benefits have not previously been reported. This study reviews 19 TKAs performed for hemophilic arthropathy that were followed for a minimum of 5.5 years and an average of 9.5 years. At present, 13 knees have good or excellent results, and six knees rate as poor or failures. Those patients with excellent results have maintained good pain relief and function. Four of the six failures were among the first seven arthroplasties performed, when only 80% factor VIII coverage was used during the perioperative period. Since the use of 100% factor VIII coverage was instituted, the failure rate has declined. Ten of the 19 knees suffered complications, including one deep infection, six superficial skin necroses, three nerve palsies, seven postoperative bleedings, and one transfusion reaction. Six of the seven knees operated on under 80% factor VIII coverage had complications. Once 100% factor VIII coverage was instituted, the only complications included one skin necrosis and three postoperative bleedings. The roentgenographic failure rate has remained high with progressive roentgenographic lucencies in 13 of 19 tibial components, associated with component shift in three knees. While these roentgenographic findings have not necessarily correlated with clinical results, they are disturbing and may portend future failures. However, pain relief and improved function are maintained at longer follow-up times. The best results were obtained under 100% factor VIII coverage using a posterior stabilized prosthesis and patellar resurfacing.

Adult↗

PubMed1988

The efficacy of tricyclic antidepressants.

Explore the source record for details and available documents.

Antidepressive Agents, Tricyclic↗

PubMed1988

Characterization of platelet binding of heparins and other glycosaminoglycans.

The binding of glycosaminoglycans to intact washed human platelets was studied. The platelet binding of a 3H-labeled unfractionated heparin was saturable and reached equilibrium in 10-15 minutes. Heparin binding was specific: a 50-fold molar excess of an equivalent unlabeled heparin displaced up to 90% of labeled heparin, while chondroitin sulfate A and hyaluronic acid minimally displaced the binding of labeled heparin. Low molecular weight heparin fragments showed intermediate efficacy in displacing the binding of unfractionated [3H]heparin. Dextran sulfate (Mr 8,000, sulfation 17%) was as potent as unfractionated heparin in displacing binding, while neutral dextrans were ineffective. We observed that platelet activation by the calcium ionophore A23187 increased heparin binding by 2 to 3-fold, principally by enhancement of binding capacity not binding affinity. This process of heparin binding to the platelet surface may mediate some of the reported effects of heparin on platelet behavior.

Binding, Competitive↗

PubMed1988

Biochemical mechanisms of tumor invasion and metastases.

Cancer invasion and metastases is a complex multistep process. In order for a tumor cell to successfully traverse all the steps of this process and initiate a metastatic colony, it must express the right combination of gene products. Such gene products may include proteins which regulate cell interaction with the basement membrane and cell motility. Tumor cells attach to the basement membrane glycoprotein laminin via the cell surface laminin receptor. The human laminin receptor was purified and molecularly cloned. The level of laminin receptor mRNA is a variety of human carcinoma cells correlated with the number of laminin receptors on the cell surface of these cells. Following attachment to the basement membrane, the tumor cell next secretes proteases which may degrade type IV collagen. A genetic linkage between type IV collagenase secretion and metastases was studied using our new genetic system for inducing metastases employing the ras oncogene. Following attachment and local proteolysis, the third step of invasion is tumor cell motility. We have isolated a tumor cell autocrine motility factor (AMF). This factor is secreted by the tumor cells and binds to a cell surface receptor resulting in a profound (greater than 100x) stimulation of cell locomotion. AMF may play a major role in the autonomous invasive behavior of tumor cells.

Animals↗

PubMed1988

Cerebrovascular CO2 reactivity after carotid artery occlusion.

Cerebral blood flow (CBF) was measured in 39 men at normocapnia and after 5% CO2 inhalation using the xenon-133 technique. Twenty-three patients had unilateral carotid artery occlusion with no angiographic evidence of contralateral carotid artery stenosis or ophthalmic collateral flow. Eleven of these patients had undergone extracranial-intracranial (EC-IC) bypass surgery. Sixteen age-matched normal men underwent CBF measurements at normocapnia and hypercapnia to provide control data. Mean hemispheric CBF was not different between hemispheres ipsilateral and contralateral to the carotid artery occlusion either in the patients who had undergone bypass surgery or in those with carotid artery occlusion alone. Considering all patients with carotid artery occlusion, mean CO2 reactivity was decreased in the hemisphere ipsilateral to the occlusion as compared to the contralateral hemisphere in both groups. Based on data from normal individuals, a hemispheric difference in CO2 reactivity of more than 0.94%/mm Hg PaCO2 or a global CO2 reactivity of less than 0.66%/mm Hg PaCO2 was considered abnormal for an individual patient. Six of 23 patients with carotid artery occlusion (three with an EC-IC bypass) had global or hemispheric abnormalities in CO2 reactivity. Patients with impaired CO2 reactivity were not distinguishable from other patients by neurological examination, presence of transient ischemic attacks, or evidence of infarction on computerized tomography scanning. This test was safe and simple to perform and may be a useful means of detecting impaired cerebrovascular collateral reserve capacity. If impaired CO2 reactivity after carotid artery occlusion proves to be associated with a high risk of subsequent stroke, the test would provide a physiological basis for selecting a subgroup of patients who could be helped by cerebral revascularization.

Administration, Inhalation↗

PubMed1988

Surgical management of heparin-associated thrombocytopenia. Strategies in the treatment of venous and arterial thromboembolism.

We report the vascular surgical strategies and results in 13 patients with heparin-associated thrombocytopenia and describe useful in vitro techniques for the evaluation of anticoagulant therapy. Thirteen of 40 patients with heparin-associated thrombocytopenia had 18 cardiovascular procedures done to save life or limb. Greenfield filters were placed in eight patients to prevent pulmonary embolism. Eight patients had 10 arterial procedures, with alternative anticoagulation that used dextran or warfarin in five cases. In three cases iloprost, a derivative of prostacyclin and a potent platelet inhibitor, was infused intraoperatively and heparin was given. Both the use of alternative anticoagulants and platelet suppression by iloprost were clinically effective strategies. The concurrent measurement of plasma levels of beta-thromboglobulin and fibrinopeptide A in two patients confirmed that both approaches can successfully prevent activation of platelets and plasma coagulation during arterial surgery. One operative death occurred; all vascular reconstructions remained patent at 3 to 6 months. In two patients who received heparin alone for arterial surgery, both procedures resulted in thrombosis and limb loss. When major venous thromboembolism is complicated by heparin-associated thrombocytopenia, insertion of a Greenfield vena cava filter should be considered if there is significant risk of pulmonary embolism. When necessary, arterial surgery is feasible in patients with heparin-associated thrombocytopenia if alternative anticoagulation or adequate suppression of platelet reactivity can be achieved.

Dextrans↗

PubMed1988

Biochemical mechanisms of tumor invasion and metastases.

Animals↗

PubMed1988

Nonpenetrating vascular injury to the subclavian artery.

Blunt subclavian artery injury has been uncommonly reported in the literature. Recent encounter with three such injuries prompted us to review our experience over the past 10 years uncovering only one additional case. These four cases and a review of pertinent literature form the basis for this article. Key clinical issues include a high index of suspicion in patients sustaining major blunt deceleration and rotational or direct injuries to the neck, thorax, and/or upper extremities. Prompt diagnosis remains obscured by the presence of severe associated injuries, the treatment of which requires prioritization. Arteriography is invaluable to elucidate injury because prompt vascular control is dictated by various approaches depending on the location. Expeditious surgical repair is indicated to prevent complications of hemorrhage, pseudoaneurysm, thromboembolism, and/or arteriovenous fistula. Long-term results appear to be good with major morbidity related to associated neurologic, soft tissue, and bony injuries.

Adolescent↗

PubMed1988

Patellar fracture type and prognosis in condylar total knee arthroplasty.

Fractures of the patella occurred following implantation of 36 condylar total knee arthroplasties in 35 patients. The end results were evaluated in relation to fracture type after an average 4.5-year follow-up period. The follow-up observations included a physical examination, quantitative knee score, and roentgenographic evaluations of extremity alignment and implant position. Twenty-two of the 36 knees had a good or excellent knee score and 14 had a fair or worse score at the time of the latest follow-up evaluation. The satisfactory knees had an average arc of motion of 100 degrees, while the unsatisfactory knees had an average arc of motion of 80 degrees. Fourteen fractures through the mid-body or superior pole of the patella not involving the implant, cement, or quadriceps mechanism (Type I) and two nondisplaced fractures through the inferior pole of the patella (Type IIIB) were managed nonoperatively, with all knees rating either a good or excellent score. Fractures of the patella disrupting the quadriceps mechanism or implant/bone/cement composite (Type II) were managed operatively in the six knees. Fractures of the inferior pole of the patella with disruption of the patellar ligament (Type IIIA) were managed operatively in seven of eight knees (one patient refused surgery). Lateral fracture-dislocations were managed operatively in all six knees. Six of the knees operated upon had a good or better score, and nine knees were rated as poor or failed. Those fractures alignment and implant position were seen had the more severe patellar fractures and poorest outcomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

The results of revision total knee arthroplasty.

The results of 65 consecutive revision total knee arthroplasties performed for mechanical failure were reviewed. Fifty-nine of the knees were followed for an average of five years (range, 2-10 years). The types of implants used included: total condylar, posterior stabilized, total condylar III, and the kinematic rotating hinge prostheses. Only 46% of the knees were considered excellent or good; 42% either had poor results or failed. The infection rate was 4.5%. Poor results were generally caused by patellofemoral problems and kinematic abnormalities. Revision total knee arthroplasty is a technically demanding procedure that can improve function when anatomic relationships of the knee are restored.

Aged↗

PubMed1988

Use of a total condylar knee prosthesis for treatment of osteoarthritis and rheumatoid arthritis. Long-term results.

Between May 1975 and December 1979, 113 patients had 153 arthroplasties using a total condylar knee prosthesis. Thirty patients (forty-two knees) died, and one (two knees) was lost to follow-up. Thirty-eight of these forty-four knees had been followed for more than two years, and none had had a revision. The remaining eighty-two patients (109 knees) were followed for an average of nine years (range, seven to 11.5 years). At the time of the latest examination, ten had had a revision for various reasons. For the ninety-nine knees that had the original prosthesis, the findings were compared with those of an evaluation that had been done four years postoperatively. The average over-all knee score was found to have decreased between the four-year and the latest follow-up evaluation, primarily because of a 7-point decrease in the score for function. The rate of infection was 0.6 per cent. The knees that had had patellar resurfacing had better over-all scores and better scores for pain than those that had not. This was particularly true in the patients who had osteoarthritis. The results of arthroplasty using a total condylar prosthesis appeared to be consistent and durable. Although there was a decrease in the quality of the functional result with increasing age, the patients reported consistent relief of pain.

Adult↗

PubMed1987

Vascular insufficiency in Okihiro's syndrome secondary to hypothenar hammer syndrome.

The presence of Okihiro's syndrome (congenital thenar hypoplasia and Duane's anomaly) in a patient became clinically significant when a hypothenar hammer syndrome developed. The ulnar artery occlusion resulted in a compromise of the hand's vascular supply because of a congenital hypoplastic radial artery. Resection of the thrombosed ulnar artery and insertion of an interposition vein graft restored circulation to the hand. Anatomic features in this case include a hypoplastic radial artery and double motor branch of the median nerve. Clinicians should consider Okihiro's syndrome in the differential diagnosis of thenar muscle atrophy since there are genetic, diagnostic, and clinical implications.

Adult↗

PubMed1987

Experimental comparison of percutaneous vena caval devices: titanium Greenfield filter versus bird's nest filter.

A venous embolism model with autogenous thrombus was used for comparison of the functional properties of two new vena caval devices: a titanium Greenfield filter and the bird's nest filter. All nine Greenfield filters were correctly placed in the inferior vena cava and produced significant clot lysis of 81.3% +/- 16.3% (p less than 0.001, paired t test). Difficulty was encountered in affixing the hooks of the bird's nest device into the vein wall and resulted in two filters not being inserted and two filters being placed too proximally. One set of hooked wires of another bird's nest device migrated to the right atrium despite correct insertion. Eight bird's nest devices allowed clot lysis of 83.4% +/- 17.7% (p less than 0.001), paired t test) but thrombus size was increased in one case. The Greenfield and bird's nest filters have comparable effects on trapped emboli, but the bird's nest filter may be susceptible to thrombosis and occlusion under certain circumstances. The pre-shaped hooked wires of the bird's nest device may be difficult to insert and may allow proximal migration after a large thrombus was trapped.

Animals↗

PubMed1987

Congenital vascular abnormalities in Okihiro's syndrome--a case report.

In this report, the authors describe the angiographic findings in the forearm and hand in Okihiro's syndrome. To the best of their knowledge, it has not been described before. Okihiro et al described hypoplasia of the thenar eminence in association with a congenital disorder of ocular motility previously reported in Duane's syndrome.

Adult↗

PubMed1987

Carotid endarterectomy in patients with heparin-induced platelet activation: comparative efficacy of aspirin and iloprost (ZK36374).

Patients with heparin-induced platelet activation who are reexposed to heparin may have recurrent thrombocytopenia, intravascular thrombosis, arterial emboli, or sudden death. To permit carotid endarterectomy in two patients with confirmed heparin-induced platelet activation, we compared the efficacies of aspirin and iloprost, a stable analogue of prostacyclin, in preventing heparin-induced platelet activation. In the first patient, although aspirin prevented both in vitro heparin-induced platelet aggregation (70% without and 7.5% with aspirin) and 14C serotonin release (48% without and 0% with aspirin), intraoperative administration of heparin resulted in an increase in plasma levels of platelet factor 4 from 8 to 260 ng/ml and beta-thromboglobulin levels from 29 to 39 ng/ml. In addition, the circulating platelet count decreased from 221,000 to 174,000 microliters, and 15% spontaneous platelet aggregation was observed. Fortunately, fibrinopeptide A levels remained less than 10 ng/ml intraoperatively, and no thrombotic complications occurred. In the second patient, aspirin did not prevent heparin-induced platelet aggregation in vitro (65% without and 41% with aspirin); however, iloprost (0.01 mumol/L) prevented both in vitro heparin-induced platelet aggregation (59.5% without and 0.0% with iloprost) and 14C serotonin release (56.7% without and 0.0% with iloprost). Therefore, a continuous infusion of iloprost was begun before administration of heparin and was continued until 20 minutes after reversal of heparin with protamine. After intraoperative administration of heparin, plasma levels of platelet factor 4 increased from 19 to 200 ng/ml, and beta-thromboglobulin levels increased from 56 to 76 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗