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Biomedical subjects

A V Persson

Publications and source records attributed to A V Persson.

At least 19 recordsLinked to original sources
PubMed1992

The major glycolipid recognized by SP-D in surfactant is phosphatidylinositol.

Surfactant protein D (SP-D), a multimeric calcium-dependent lectin isolated from pulmonary alveolar lavage, has been previously shown to interact reversibly with crude surfactant [Persson et al. (1990) J. Biol. Chem. 265, 5755-5760]. In this study, SP-D is shown to interact reversibly with a preparation of organelles enriched in lamellar bodies, in a manner inhibited by calcium-chelating agents and by competing saccharides. An interaction with an endogenous glycoprotein could not be identified by electrophoresis of surfactant or lamellar body-associated proteins followed by electrotransfer of the separated proteins to nitrocellulose and then probing with radioiodinated SP-D via lectin overlay. Separation of the surfactant or lamellar body lipids on two-dimensional thin-layer chromatography (2D-TLC) followed by probing with radioiodinated SP-D via lectin overlay demonstrated binding to a single lipid. This interaction was dependent on the presence of calcium and was inhibited by competing saccharides. By assaying column fractions for the ability to bind radioiodinated SP-D after TLC, the glycolipid was purified to homogeneity and identified as phosphatidylinositol (PI). Identification was confirmed by mass spectrometry. We further demonstrate the ability of radiolabeled SP-D to bind to PI presented in a lipid bilayer through separation of free SP-D from liposome-bound SP-D on density gradients of Percoll. The interaction of SP-D with PI is dependent on calcium and inhibited by competing saccharides. SP-D binds with similar efficiency to liposomes with mole fractions of PI ranging from 2.5% to 30%, thereby demonstrating the lectin's ability to recognize mole fractions of PI available in surfactant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Deep venous thrombosis and pulmonary embolism.

All surgical patients are at risk for the development of deep venous thrombosis and subsequent pulmonary embolism or postphlebitic syndrome. The evolution of ultrasonographic imaging has increased the awareness of prevention, diagnosis, and treatment of deep venous thrombosis. Duplex imaging and Doppler color flow imaging have made the diagnosis of deep venous thrombosis relatively simple, painless, inexpensive, and definitive. These procedures have gained acceptance by both patients and physicians. Several risk factors have been identified that increase the chance of the development of deep venous thrombosis. These factors include a history of deep venous thrombosis, presence of a malignant process, increasing age, cigarette smoking, obesity, prolonged bed rest, and general anesthesia. The greater the number of risk factors, the more aggressive prophylaxis should be. Means of prophylaxis have improved, and surgeons now generally agree that some form of prophylaxis is required. Heparin and intermittent compression devices appear to be equally effective in preventing deep venous thrombosis. The addition of venous monitoring in high-risk patients permits immediate identification of the presence of deep venous thrombosis. During the last decade, the treatment of patients with deep venous thrombosis has changed little. Heparin followed by warfarin remains the treatment of choice. A small group of patients receive fibrinolytic therapy for deep venous thrombosis. Although the incidence of postoperative deep venous thrombosis has decreased during the last decade, it remains a significant complication.

Humans↗
PubMed1991

Use of noninvasive vascular laboratory in diagnosis of venous and arterial disease.

The development and widespread availability of noninvasive testing have revolutionized the approach to the diagnosis of vascular disease. Noninvasive tests are safe, can be performed on an outpatient basis, and are readily repeatable. These tests require skill and experience to perform with acceptable accuracy. In experienced hands, they compare favorably with standard angiography, and, after the initial cost, are less expensive. B-mode ultrasonography provides a gray scale image of the blood vessels. Doppler probes permit analysis of flow patterns and velocity. Color flow imaging, the latest advance, combines high-resolution B-mode and Doppler imaging systems using a computer to provide simultaneous anatomic and physiologic information. This method is a faster and more accurate means of detecting and evaluating the extent of vascular disease. Noninvasive testing is useful in assessing the carotid arteries before vascular or other high-risk operation. Stratification of the risk of future stroke is possible with these tests. This stratification assists in the selection of candidates for carotid surgery among patients with symptomatic carotid disease or asymptomatic bruits in the neck. The hemodynamic significance of obstructive disease in the peripheral arteries can be evaluated and followed by serial noninvasive testing. Noninvasive testing is also of proven value in the surveillance of patients with arterial bypass grafts and in diagnosing local vascular complications of arterial catheterization. Acute and recurrent deep venous thrombosis can be diagnosed accurately by noninvasive testing, greatly reducing the need for venography. In addition, noninvasive testing is particularly suited for screening patients at high risk for developing deep venous thrombosis.

Carotid Artery Diseases↗
PubMed1989

Use of the triplex scanner in diagnosis of deep venous thrombosis.

We report our experience with 264 patients who underwent triplex scans for venous occlusive disease over a 10-month period. Venography was obtained in 30 of these patients. Correlation between the two procedures was 100%. The anatomic location of thrombosis and the extent of disease were identical in both studies. The presence of intraluminal clot by angiodynography is detected by looking for changes in the venous color-flow patterns and in the B-mode image. Newer clots have low echogenicity and are seen as large black areas in the gray-scale image. Older clots are more echogenic. The presence of enlarged venous collateral veins as well as absence of color flow and inability to compress the veins confirm the diagnosis of acute deep venous thrombosis. The results of angiodynography alone can be used safely in diagnosing acute deep venous thrombosis in patients. Equally important, treatment can be withheld safety in a patient with normal results.

Arm↗
PubMed1989

The role of thrombolytic therapy in surgical practice.

The ability of streptokinase and urokinase to lyse intravascular fibrin-based clots is firmly established. However, there is a lack of enthusiasm for these agents because of serious haemorrhagic complications and a lack of controlled randomized studies indicating their efficacy. Thrombolytic therapy is suitable in only 15 per cent of patients with acute deep venous thrombosis. It restores the venous circulation to normal in up to 95 per cent of these patients if therapy is instituted within 5 days of the onset of symptoms. These patients have significantly fewer symptoms on follow-up than patients treated with heparin although the ability of thrombolytic therapy to preserve venous valvular function and to prevent the post-phlebitic syndrome is now in question. Thrombolytic therapy is as effective as heparin in preventing pulmonary embolism and may be superior in its treatment. Pulmonary haemodynamics are rapidly improved, diffusion capacity is restored and, although the evidence is inconclusive, long-term pulmonary hypertension may be prevented. Although the mortality rate is not decreased, controlled studies show that thrombolytic therapy may be beneficial in massive pulmonary embolism with clinical shock. Thrombolytic therapy is indicated for acute arterial and acute bypass graft occlusion when the surgical alternative is associated with a higher morbidity and mortality. Partial thrombolysis is achieved in up to 90 per cent of cases and the need for further therapeutic intervention is eliminated in one-third of the patients treated. New thrombolytic agents with greater specificity and potentially greater efficacy and fewer complications are being developed. Tissue plasminogen activator has been successfully used. Prourokinase, fibrin-seeking urokinase and acetylated streptokinase-plasminogen complex may expand the role of thrombolytic therapy in surgical practice.

Arterial Occlusive Diseases↗
PubMed1989

Chronic rupture of abdominal aortic aneurysms.

Chronic rupture of the aorta is a rare condition. In this report, the presentation, diagnosis, and management of two patients with this complication is described. Chronic rupture may occur without hypotension and may mimic several other conditions. CT scans are superior to ultrasound in diagnosis and evaluation. Emergency repair is not necessary in clinically stable patients and careful preoperative planning may diminish morbidity and mortality.

Aged↗
PubMed1988

Natural history of subclavian steal syndrome.

Eighty-two patients presenting with subclavian steal syndrome (36 men, 46 women; median age, 66.5 years) were studied. All patients underwent clinical and noninvasive evaluation. Diagnosis was based on both a 20 mmHg difference in blood pressure between arms and reversed blood flow in the vertebral artery. Twenty-one patients (25.6%) had a transient ischemic attack or cerebrovascular accident before the study. In 16 patients (19.5%), the anterior circulation was involved and the vertebrobasilar circulation was effected in 5 patients (4.8%). Fifty-five patients were followed for one to six years (mean 4.1 years). During this period three patients died. Noninvasive studies showed that 39 patients (70.9%) had progression of disease in the carotid arteries and that 10 of these 39 (12.1%) exhibited a transient ischemic attack or cerebrovascular accident, and eight patients (9.7%) required carotid endarterectomy. No patient had a stroke involving the vertebrobasilar circulation, but four patients (4.8%) had a transient ischemic attack. Three other patients had revascularization procedures performed for arm ischemia. Patients with subclavian steal syndrome are more likely to experience a transient ischemic attack or cerebrovascular accident involving the carotid circulation than the vertebrobasilar circulation. Noninvasive evaluation of the carotid arteries and the posterior circulation should be included in the long-term follow-up of these patients.

Aged↗
PubMed1986

Recent advances in imaging and evaluation of blood flow using ultrasound.

Use of ultrasound for noninvasive evaluation of the vascular system is now commonplace. A new imager has been developed that depicts Doppler images (moving structures) and B-mode images (nonmoving structures) on the same image screen. The new instrument and its potential for clinical use are described.

Blood Circulation↗
PubMed1986

Treatment of acute deep venous thrombosis with fibrinolytic agents.

Both heparin and fibrinolytic agents carry a risk of bleeding. Because of their beneficial effects in restoring vessel patency, we prefer the use of fibrinolytic agents in patients with acute deep vein thrombosis unless there is some specific contraindication. With the treatment regimen we have outlined, the risk of bleeding is extremely low. We have found that the long-term results achieved with streptokinase therapy are excellent, and normal venous hemodynamics can be restored quickly and effectively.

Bandages↗
PubMed1986

Intraplaque hemorrhage.

This prospective study, which correlated the findings at carotid surgery with the preoperative symptoms, indicates that the occurrence of an intraplaque hemorrhage is an important event in the manifestation of significant carotid artery disease. Almost all of the patients with TIAs had intraplaque hemorrhages and breaks in the endothelium, thereby exposing the hemorrhage to the arterial lumen and providing a source of embolization. The asymptomatic patients in this study had fewer intraplaque hemorrhages, and only 8 per cent had an identifiable source of embolization. It would thus appear from the pathologic study of the plaques harvested at surgery that the cause of TIAs is embolization of intraplaque hemorrhagic material and not platelets and fibrin, which gather on the surface of irregular plaques. We question the use of antiplatelet drugs in the treatment of TIAs, as they could increase the occurrence of intraplaque hemorrhages.

Aged↗
PubMed1985

Thrombolytic therapy for deep vein thrombosis.

We have outlined our treatment for acute DVT with thrombolytic agents. We prefer to use thrombolytic agents unless a specific contraindication is present. Both heparin and thrombolytic agents carry the risk of bleeding. In our opinion, the long-term results of restoring the deep venous system anatomically and physiologically are more likely if thrombolysis is the chosen therapy. Heparin therapy simply arrests the problem and relies on the development of sufficient venous collateral pathways, recanalization, or both to improve venous return. The short-term results (the first 6 months) of thrombolytic therapy and heparin are similar. The results of prospective, randomized studies comparing standard anticoagulation versus lytic therapy have documented improved long-term venous function in patients receiving thrombolytic therapy.

Blood Coagulation Tests↗
PubMed1985

Preoperative evaluation of the high-risk patient.

The benefits of surgery are usually clear and easy to define. The risk to which a particular patient is subjected during a specific operation, however, is a multifactorial and complex question related to preoperative condition, the complexity of the surgery proposed, and the skill and experience of the surgeon. We have concentrated our discussion only on preoperative evaluation of the patient's condition. By our system of evaluation of preoperative cardiac, pulmonary, carotid artery, nutritional, and general medical status some estimation of the risk of postoperative complication can be formulated. In some of our discussion we reported studies of other investigators, in which the likelihood of postoperative complications was expressed in percentages. An approach derived by study of groups of patients may or may not apply to a particular patient. Although such an approach may not be entirely accurate, it can assist in the estimation of the chance of serious postoperative complications. Obviously the most ideal situation would be to define precisely the risks and benefits of each operative procedure we recommend to a patient. Because this is not possible, we should state the benefits and estimate the risks of surgery preoperatively. We should also delay operation until the patient's preoperative condition is optimal, thereby decreasing the risks of complications. With a systematic preoperative evaluation these goals can be approximated. A critical part of the benefit-to-risk equation is the surgeon's judgment of whether the patient is a good operative risk. This opinion should not be ignored and should be part of any system of preoperative evaluation of risk of postoperative complications.

Adult↗
PubMed1985

Chronic intestinal ischemia. The Lahey Clinic approach to management.

Recognizing decreased mesenteric arterial blood supply in symptomatic and asymptomatic patients is essential to successful treatment of the ischemic bowel. The vascular disease can be documented by using standard arteriography, including a lateral projection. We favor revascularization by bypass in the celiac and superior mesenteric systems and by reimplantation or bypass in the inferior mesenteric system. Externally supported ringed PTFE is our conduit of choice. The chances of late recurrence can be lessened by complete revascularization. For the patient with no symptoms of mesenteric insufficiency who undergoes revascularization for other abdominal arteries, it is important to avoid restricting the mesenteric flow when disease is present, and it may be necessary to revascularize the superior mesenteric artery simultaneously as a prophylactic measure. Avoidance of the major problems of bowel infarction can be achieved by these maneuvers.

Arterial Occlusive Diseases↗
PubMed1985

Use of the personal computer in clinical research.

Personal computers are quickly becoming items of everyday use. More physicians' offices are using computers for billing and patients' records. Others have purchased computers for their word processing capabilities. These computers can be used for archives of medical case records or to collect and collate data for clinical research. This article focuses on how we use a personal computer for organization and management of clinical research projects. Included is a description of how we organize a research project, gather data, write computer programs, enter data into the computer, and generate and display reports. The use of a template program and a personal computer permits creation of individual programs without the aid of a professional programmer. When a single data-management program is used, five or six research projects can be carried out at a cost comparable to that of one project using a large computer and professional programmers.

Computers↗
PubMed1985

Rapid preparation of lecture slides.

When lecture slides must be prepared at a moment's notice, these methods of rapid preparation will allow you to create good quality slides. Although rush jobs are usually associated with higher costs, using these methods will keep the price per slide to a minimum. An investment must be made for the initial equipment, but the cost per slide is much less than that of slides produced by the standard methods. Type produced by typewriters or computer printers is adequate for most slides, but better slides can be produced with KroyType or Letraset letters. The KL film is preferred for reverse slides of text or line drawings, and the RPC film for production of radiographic slides. If an X-omat developer is not available, Polaroid film is a good alternative for rapid production of slides. The KL reverse slide projects best and can be colored, but RPC film produces a good positive slide of typed material. We have also photographed from a computer terminal screen using the KL film to make positive slides, the Polaroid continuous tone film for reverse slides, and Polaroid color film for color slides of material composed on a computer terminal with multicolor and graphics capabilities.

Computers↗
PubMed1985

Selection of patients for lumbar sympathectomy.

We successfully predicted that patients presenting with critical ischemia of a limb and Doppler ratios greater than or equal to 0.3 would benefit from lumbar sympathectomy alone. However, we found that the procedure failed in 14 per cent of limbs whose ratios were greater than or equal to 0.3. In retrospect, all these patients were found to have deep infection. Had we known this fact prospectively, our predictions for success would have been close to 100 per cent. We were less than 50 per cent successful in predicting failure of the procedure, but the number of patients in this group is too small to draw reliable conclusions. We believe that patients with arm-ankle Doppler ratios greater than or equal to 0.3 whose manifestations of ischemia are limited to the skin will have a greater than 95 per cent chance of receiving a good result from lumbar sympathectomy alone and that this result will be maintained for many years.

Aged↗