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Biomedical subjects

J S Yao

Publications and source records attributed to J S Yao.

At least 19 recordsLinked to original sources
PubMed1992

Protective role of antigenic sites on the envelope protein of Hantaan virus defined by monoclonal antibodies.

To investigate the role of Hantaan virus envelope glycoprotein in infection, a panel of monoclonal antibodies (MAbs) was examined in vitro with several serological tests and in vivo by passive transfer experiments in mice. An antigenic site, specific for the inhibition of infected cell focus was detected with the focus inhibition neutralization test (FINT), in addition to the neutralization related antigenic sites, which were revealed by the ordinary focus reduction neutralization test (FRNT). Suckling mice were given the MAbs by passive transfer followed by lethal Hantaan virus challenge. All neutralizing MAbs detected by either FRNT or FINT protected all mice from lethal infection, confirming the importance of the antigenic sites as a protective antigen. Mice given non-neutralizing MAbs by passive transfer, however, began to die earlier than the control group; mean time to death (18.2 +/- 2.1 to 21.5 +/- 2.8 days) being significantly shorter than that of the control group (25.8 +/- 1.8, p less than 0.01, Mann-Whitney, U probability test). Virus titers in brains of mice which died early, were about 10 times higher than those of control mice. These results indicated the early death phenomenon of mice which was mediated by the anti-virus antibody.

Animals↗
PubMed1992

Antibody-dependent enhancement of hantavirus infection in macrophage cell lines.

Antibody-dependent enhancement (ADE) of hantavirus infections (strains Hantaan 76-118 and SR-11) was studied using macrophage-like cell lines (J774.1, P388D1, and U937). Significantly higher virus titers (1,000 to 4,000 FFU/ml) were obtained by pretreatment of the virus with immune serum as compared to normal serum (less than 20 FFU/ml). Monoclonal antibodies (MAbs) to strain Hantaan 76-118 were employed to determine the antigenic determinants responsible for the ADE activity. ADE of the infection occurred with MAbs to both G1 and G2 envelope glycoproteins, but not with MAbs to nucleocapsid protein. Antigenic determinants related to haemagglutination or virus neutralization were found to cause ADE of the infection.

Animals↗
PubMed1992

Effect of neutralizing monoclonal antibodies on Hantaan virus infection of the macrophage P388D1 cell line.

The effect of neutralizing monoclonal antibodies (N MAbs) on Hantaan virus infection of macrophages was investigated using P388D1 cells, a murine macrophage cell line. MAbs to the G1 protein (G1b) and the G2 protein (G2a and G2c) neutralized viral infectivity in P388D1 cells. N MAbs to G1b showed much higher neutralizing potency than those to G2a and G2c. With each N MAbs, two distinct effects were observed: neutralization of viral infectivity occurring at high concentrations and enhancement of that at low concentrations. Non-neutralizing MAbs, on the other hand, showed only enhancement of viral infectivity even at high concentrations without any inhibitory effects. The Fab fragments of N MAbs showed neither neutralizing nor enhancing activities. However, when the virus-Fab complexes were reacted with the anti-Fab antibodies, both neutralization and enhancement of viral infectivity were restored depending on the dose of Fab fragments. These results indicate that Hantaan virus infection of P388D1 cells is mediated by the Fc portion of the antibodies and neutralization is dependent on the concentration of N antibodies bound bivalently to the neutralization site on the virion.

Animals↗
PubMed1992

Interleukin-1 beta and tumor necrosis factor-alpha release in normal and diseased human infrarenal aortas.

The presence of chronic inflammatory cells in the adventitia and media of abdominal aortic aneurysms and aortic occlusive disease suggest an immunologic response. The purpose of this study is to determine whether normal or diseased infrarenal aortas liberate the inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta). Twenty-six infrarenal aortic biopsies (5 aortic occlusive disease, 15 abdominal aortic aneurysms, and 6 cadaveric donors) were weighed, minced into small pieces, and incubated in media for 48 hours. Conditioned media was harvested at 48 hours and assayed for IL-1 beta or TNF-alpha with use of an ELISA assay. Comparison of groups was performed with a one-way analysis of variance. The constitutive IL-1 beta produced by abdominal aortic aneurysms was significantly different than that in cadaveric donors (908 +/- 194 pg/ml [SE] vs 100 +2- 30 pg/ml). There was no statistically significant difference between abdominal aortic aneurysms and aortic occlusive disease (908 +/- 194 pg/ml vs 604 +/- 256 pg/ml) or aortic occlusive disease and cadaveric donor (604 +/- 256 vs 100 +/- 30). In time-course studies for the release of IL-1 beta, abdominal aortic aneurysms demonstrated maximal release at 48 hours. IL-1 beta release was augmented by lipopolysaccharide in all categories. A dose response curve demonstrated maximal IL-1 beta release on stimulation with 5 micrograms/ml LPS. Constitutive TNF-alpha production was low, ranging from 13 +/- 1.5 pg/ml in cadaveric donor, to 20 pg/ml in aortic occlusive disease, and 24 +/- 11 pg/ml in abdominal aortic aneurysms. There was no augmentation in TNF-alpha with lipopolysaccharide.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

Gray-scale ultrasound diagnosis of peripheral arterial aneurysms.

Diagnostic ultrasound is a feasible technique for demonstrating the presence of an aneurysm in the popliteal, femoral, iliac, and brachial arteries. All aneurysms were correctly identified and confirmed by arteriography, surgery, or examination of the amputated specimen. The popliteal artery in healthy volunteers had a mean size of 0.8 +/- 0.2 cm. Neither the age nor the sex of the patient influenced artery size. In patients with known abdominal aortic aneurysms of significant atherosclerosis, the popliteal size was within two standard deviations from the mean of normal popliteal arteries.

Adolescent↗
PubMed1979

Abdominal aortic salmonellosis.

A recent example of Salmonella mycotic abdominal aortic aneurysm is presented together with a review of the 24 other cases in the literature. Emphasis is placed on common modes of presentation, diagnosis, and surgical management. A review of current theories of etiology is presented along with a new, more descriptive classification of mycotic aneurysms.

Aneurysm, Infected↗
PubMed1979

The use of photoplethysmography in the assessment of venous insufficiency: a comparison to venous pressure measurements.

In an attempt to develop a noninvasive test to assess objectively the magnitude of venous valvular dysfunction in pathologic states, photoplethysmography (PPG) was compared to venous pressure in the saphenous vein at the ankle. Simultaneous venous pressure and PPG recordings were taken before, during, and after exercise with subjects in the sitting position. In a total of 338 paired measurements in 24 normal, 25 postphlebitic, and 14 varicose limbs, PPG and venous pressure tracings appeared to be identical; data points had a correlation coefficient of great significance (r = 0.898). Postexercise recovery times clearly separated the normal from the postphlebitic limbs. Varicose limbs were assessed accurately regarding results of proposed surgery using an above-knee tourniquet. It appears that the PPG evaluation provides information comparable to venous pressure studies and does so more quickly and noninvasively. The test holds promise in measuring results of direct venous reconstructive surgery as well as in venectomy procedures.

Humans↗
PubMed1979

Pelvic hemodynamics after aortoiliac reconstruction.

Changes in blood flow to the pelvis were monitored by measurement of penile blood pressures before and after 38 aortoiliac vascular reconstructions. An increase in penile pressure was noted in 14 patients (37%), a decrease was seen in eight patients (21%), and no change occurred in 16 patients (46%). These changes could have been predicted by matching arteriograms to the surgical procedure performed. Preoperative impotence was present in 27 patients (17%). In this group a postoperative increase in penile pressure was associated with restoration of erectile capability in eight of 11 patients. Only one of 10 patients with an unchanged penile pressure regained sexual potency. In contrast, none of the eight patients whose penile pressures decreased had recurrence of erectile capability. Six of these patients had end-to-end aortobifemoral grafts, and concurrent external iliac disease prevented retrograde flow to the internal iliac vessels.

Aged↗
PubMed1978

Vascular-laboratory diagnosis of clinically suspected acute deep-vein thrombosis.

Doppler ultrasound, impedance plethysmography, and contrast venography were performed in 207 lower limbs suspected of harbouring deep-venous thrombosis, to clarify the diagnostic value and limitations of the non-invasive methods. Doppler ultrasound and impedance plethysmography were accurate in 96% and 95% of normal limbs, respectively. In limbs with venographic evidence of thrombosis requiring treatment, Dopper ultrasound and impedance plethysmography correctly detected thrombosis in 60% and 97%, respectively. Doppler ultrasound was 97% accurate in recognising chronic venous insufficiency. Impedance plethysmography was incorrectly positive in 74% of limbs with chronic venous insufficienv cy which had no venographically detected thrombosis. These findings suggest that, for the accurate diagnosis of clinically suspected deep-vein thrombosis, venography is necessary only in patients with chronic venous insufficiency who have normal Doppler ultrasound tests and abnormal impedance plethysmograms and in patients with abnormal cardiac haemodynamics. In this series, 86% of limbs would have been spared venography had non-invasive tests been used. Venography, however, remains the standard test for the detection of minor calf-vein thrombosis. A diagnostic and therapeutic schema is proposed.

Chronic Disease↗
PubMed1978

Hemodynamic and angiographic guidelines in selection of patients for femorofemoral bypass.

Although crossover femorofemoral grafts have had good long-term patency, all patients have not been symptomatically improved. Seventy-one patients underwent 80 femorofemoral bypasses from 1968 to 1978. Hemodynamic assessment included preoperative and postoperative segmental Doppler pressures and femoral artery waveform recordings. Preoperative and selective postoperative arteriography was routinely performed. Twenty-nine failures occurred predominantely in two groups, those with greater than 50% stenosis of the donor iliac artery and those with severe recipient limb outflow occlusive disease. Ten patients with normal outflow beds bilaterally associated with 10% to 50% stenosis of the donor iliac artery underwent successful femorofemoral reconstruction. Progression of donor iliac artery disease was seen in only two patients. Cumulative five-year patency was 74%. Operative mortality totaled three (3.8%). This study supports the use of femorofemoral bypass as a primary procedure when proper guidelines are used.

Adult↗
PubMed1978

Carotid endarterectomy: a follow-up study of the contralateral non-operated carotid artery.

In a study of 103 patients surviving carotid endarterectomy, follow-up information was obtained from all patients over a period of time extending to four years. This was done so that better decisions could be made regarding recommendations for contralateral carotid surgery. In this follow-up study, only three patients had contralateral surgery. Three additional patients had events clearly in the territory supplied by the contralateral carotid artery, and no patient suffered a contralateral stroke. There were an additional four patients who suffered stroke in territory not supplied by the contralateral carotid artery. In addition, four patients experienced classical transient ischemic episodes referrable to the operated carotid artery and ten patients experienced nonclassical cerebral ischemia. Seven of the 103 patients died at times remote from the carotid surgery of nonstroke cause.

Aged↗
PubMed1978

A systematic approach to severe hand ischemia.

Because severely symptomatic hand ischemia is not common and because there are a wide variety of clinical conditions which can cause arterial insufficiency of the upper extremity, a retrospective study has been done to determine the efficacy of various diagnostic manipulations used in managing 65 patients with severe hand ischemia at the Northwestern University McGaw Medical Center, Traumatic, thermal, and iatrogenic causes of hand ischemia were diagnosed by simple history taking, as was advanced uremic arteritis. Doppler ultrasound and digital arterial pressure recording were confirmative, rather than diagnostic. These aided in defining precise degrees of ischemia and identifying proximal arterial occlusions. Invasive total extremity angiography clarified atherosclerotic, atheroembolic, and other chronic occlusive lesions while serum electrophoresis and immunoelectrophoresis defined the polyclonal and monoclonal gammopathies. When digital necrosis was present, organic arterial occlusions usually were found. These responded best to direct arterial reconstruction down to the mid-palm level. Transpleural, transthoracic sympathectomy was useful as an adjuvant or as definitive treatment for distal digital arterial occlusions. Selective vasodilator therapy was used as dictated by the cause of ischemia and its eventual outcome.

Acute Disease↗
PubMed1978

Rational approach to the differentiation of vascular and neurogenic claudication.

Lower extremity pain caused by exercise but relieved by rest is usually a reliable symptom of chronic arterial insufficiency. However, similar discomfort often occurs in patients with neurospinal compression. Furthermore, arterial occlusive disease and demonstrable spinal stenosis may be present simultaneously. Fifty-two patients with symptoms suggesting intermittent claudication comprised the study group. All were proven to have a nonarterial cause of their complaint. The study consists of a retrospective analysis of the diagnostic methods used in confirming the proper diagnosis. Conclusions reached suggest a rational approach to solution of individual patient problems. The nonvascular origin of the symptoms was suggested initially by clinical evaluation in 19 patients, and by noninvasive arterial evaluation in an additional 22. The neurospinal origin of symptoms was obscured in 11 patients because of the presence of significant arterial occlusive disease, as demonstrated by nominvasive arterial testing. Seven of the 11 patients underwent arterial reconstruction, which failed to relieve their symptoms. Subsequently, the neurospinal origin of these symptoms was proven by appropriate treatment. This experience has shown that the errors in diagnosis and treatment could have been avoided by using a combined diagnostic approach, correlating results of an accurate clinical evaluation with noninvasive arterial testing as well as the findings shown on lumbosacral spine films.

Adult↗