Increased MHC class II and CD25 expression on lymphocytes in the absence of persistent lymphocytosis in cattle experimentally infected with bovine leukemia virus.

We recently observed that a group of cattle experimentally infected with bovine leukemia virus (BLV) had enhanced antibody responses to recall antigens. None of the cattle in this group were classified as persistently lymphocytotic, but they did have significantly increased numbers of circulating T and B cells. In order to investigate the potential mechanisms of BLV-induced immune activation, dual-color flow cytometry was used to compare the expression of MHC class II (MHC II) molecules and the inducible IL-2 receptor alpha chain, CD25, on lymphocyte subsets in freshly isolated and cultured PBMC from these same BLV-infected cattle (n=5) with that of age-matched, uninfected controls (n=3). Freshly isolated peripheral blood mononuclear cells (PBMC) from BLV-infected cattle were found to contain a significantly higher percentage of B cells that expressed MHC II molecules (p<0.01). In addition, an increased proportion of CD4+ T cells from BLV-infected cattle expressed MHC II molecules after 20 h of Concanavalin A (Con A) stimulation (p<0.05), and MHC II expression was increased on both CD4+ (p<0.01) and CD8+ (p<0.05) T cells from BLV-infected cattle after 68 h in vitro, even in the absence of exogenous mitogen. Although CD25 expression was not increased on freshly isolated lymphocytes from BLV-infected cattle, an increased percentage of B cells from BLV-infected cattle expressed CD25 after 20 h of culture, either in the presence (p<0.05) or absence (p<0.01) of Con A. Thus, in addition to causing alterations in absolute numbers of circulating lymphocytes, BLV infection appears to cause a functional activation of both B and T cells, even in cattle that are non-lymphocytotic. It is likely that these BLV-induced alterations in lymphocyte activation status contributed to the previously observed enhancement of antibody responses in vivo.

Effects of long-term infection with bovine immunodeficiency virus and/or bovine leukemia virus on antibody and lymphocyte proliferative responses in cattle.

Immune responses were examined in cattle between 3-5 years after experimental inoculation with bovine immunodeficiency virus (BIG) and/or bovine leukemia virus (BLV). Lymphocyte proliferative responses to Con A or to allogeneic lymphocytes with foreign major histocompatibility complex molecules (allo MHC) were determined by 3H-thymidine incorporation assays. Antigen-specific antibody and lymphocyte proliferative responses were measured following vaccination with tetanus toxoid (TT) and bovine herpes virus-1 (BHV-1). Lymphocytes from BIV-infected cattle had significantly (p<0.05) reduced proliferative responses to Con A, but responses to allo-MHC and TT did not differ from those of uninfected controls. BIV infection also had little effect on TT-specific antibody responses in vivo. In contrast, BLV-infected cattle had significantly increased secondary antibody responses to vaccination with TT, as well as enhancement of antibody responses to BHV-1. Co-infection with BIV did not alter the BLV effect, suggesting a lack of significant interaction between the two viruses in vivo. Numbers of circulating mononuclear cells were also higher in BLV-infected cattle, which was attributable to increases in both T and B cell numbers. Unstimulated lymphocytes from BLV-infected cattle had significantly increased spontaneous uptake of 3H-thymidine in vitro. When differences in counts per minute were analyzed, lymphocytes from BLV-infected cattle had slightly increased proliferative responses to Con A, but no consistent alternations in responsiveness to allo-MHC, TT, or BHV-1. The observed increase in antibody responses to non-BLV antigens suggests that at least in clinically asymptomatic cattle, BLV infection may cause a non-specific B cell activation.

Prognostic significance of intrarenal resistance indices in patients with renal artery interventions: a preliminary duplex sonographic study.

No non-invasive test can predict the clinical outcome of renal revascularization procedures. Because duplex sonographic measurements of intrarenal flow patterns reflect the resistance to flow within the kidney, the prognostic value of the cortical end-diastolic to peak systolic (d/s) velocity ratio was investigated in patients undergoing intervention for renal artery stenosis. The clinical and duplex sonographic data on 32 patients with 35 interventions (30 percutaneous transluminal angioplasties and five operations) on 42 renal artery sides were analysed. Twenty-three patients had atherosclerotic renal artery stenosis and nine patients had fibromuscular dysplasia resulting in > or = 60% renal artery stenosis. Measurements of the renal to aortic velocity ratio and cortical d/s ratio were performed before and after intervention. In the atherosclerotic patients, three interventions were clinically and technically successful, eight were technically successful but clinical failures, and 14 were clinically and technically unsuccessful. In the fibromuscular dysplasia patients, eight interventions were clinically and technically successful, and two were clinically and technically unsuccessful. The difference between the corresponding d/s ratios for atherosclerotic and fibromuscular dysplasia sides was significant on both the treated and not-treated sides (P < 0.02, two-tailed unpaired t-test). None of the 11 clinically successful procedures had a d/s ratio below 0.3, compared with seven values below 0.3 in the 24 clinically unsuccessful interventions (P = 0.05, one-tailed Fisher's exact test). It is concluded that: (1), a d/s ratio below 0.3 correlates with clinical failure in subsequent treatment of hypertension by renal revascularization, while a value above 0.3 has no prognostic significance; (2), despite technical success, not all atherosclerotic patients have clinical success from renal artery interventions; (3), in fibromuscular dysplasia patients, all clinical failures of renal artery interventions are associated with technical failures; and (4), the difference in d/s ratio between atherosclerotic and fibromuscular dysplasia patients may be a consequence of the more advanced age, longer duration of hypertension and additional risk factors in atherosclerotic patients.

Hemodynamic parameters of failing infrainguinal bypass grafts.

PURPOSE: To assess the relationship of duplex ultrasound hemodynamic parameters in stenotic vein grafts with events such as graft thrombosis or surgical revisions. PATIENTS AND METHODS: We studied 35 patent infrainguinal bypass grafts that were observed by means of color duplex graft mapping using a surveillance protocol. RESULTS: During the 11.2 month mean follow-up interval, 10 grafts developed complications. Two stenotic grafts (1 already revised) thrombosed spontaneously, and arteriography was obtained on the basis of either clinical indications or a decreased ankle/brachial index of greater than 0.15 on 9 bypasses, leading to 12 procedures (multiple procedures on 2 grafts). The 14 duplex examinations preceding an event showed these bypasses had increased focal peak systolic velocities that ranged from 250 to 600 cm/s and velocity ratios that ranged from 3.4 to 25.0 at the stenotic segment of the graft, anastomosis, or outflow artery. None of the grafts with a stenotic peak systolic velocity less than 250 cm/s or a velocity ratio less than 3.4 thrombosed spontaneously or required revision. CONCLUSION: We conclude that stenotic vein grafts with a focal peak systolic velocity of at least 250 cm/s or a velocity ratio of at least 3.4 are at increased risk for thrombosis or need for revision. Asymptomatic stenotic vein grafts with focal peak systolic velocities and ratios less than the above values may be safely observed without immediate risk for thrombosis.

Loss of Gag-specific antibody reactivity in cattle experimentally infected with bovine immunodeficiency-like virus.

The development and persistence of virus-specific antibodies were investigated in eight cattle experimentally infected with the R29 isolate of bovine immunodeficiency-like virus (BIV). By 4 weeks postinoculation (p.i.), antibodies reactive to BIV gag- and env-encoded recombinant fusion proteins were detectable by immunoblotting in all animals. By 40 weeks p.i., seven of eight cattle had dramatically decreased Gag-specific antibodies, and anti-Gag reactivity remained very low or undetectable through 190 weeks p.i. Immunoprecipitation experiments revealed a similar loss of reactivity to nondenatured BIV Gag in these animals. In contrast, antibodies to a recombinant BIV Env protein were readily detectable throughout the study in all eight cattle. During the period of declining Gag antibody, infectious virus was recoverable from peripheral blood mononuclear cells of each animal. However, there was no evidence for sufficient amounts of BIV p26-containing immune complexes to explain the loss of anti-Gag reactivity. Interestingly, the single animal that maintained detectable anti-Gag reactivity throughout the study was repeatedly negative for virus recovery beyond 17 weeks p.i. All animals have remained clinically normal for over 4 years p.i., with no evidence of consistent changes in mononuclear cell subsets. These findings provide evidence that in BIV infection an early decline in Gag-specific antibody reactivity can occur without evidence of increasing viral replication or progression to overt clinical disease.

Prevalence of carotid and lower extremity arterial disease in patients with renal artery stenosis.

Atherosclerosis is the most common cause of renovascular hypertension secondary to hemodynamically significant stenoses (> 60% diameter reduction). To assess the prevalence of atherosclerosis in the peripheral arteries and carotid bifurcation, we prospectively studied 60 patients who had renal artery stenosis documented by ultrasonic duplex scanning. Disease of the peripheral arterial circulation was assessed by the measurement of the ankle/brachial systolic pressure ratio. To evaluate the extracranial carotid artery, ultrasonic duplex scanning was employed. The prevalence of a 50-100% diameter reducing stenosis in the carotid artery was 46% in patients with a > 60% diameter reducing renal artery stenosis. The prevalence of severe peripheral arterial disease was 73% in those patients with a high grade renal artery lesion. The prevalence of severe disease in the peripheral and carotid arteries was less (50% and 25%, respectively) in patients with renal artery lesions that reduced the diameter of the renal artery less than 60%. The high prevalence of associated lesions in the carotid and peripheral circulation in patients with renovascular disease secondary to atherosclerosis should prompt investigation of these major arteries when renal artery disease is detected. Disease of the carotid and peripheral arteries is a common cause of morbidity and should be treated according to accepted guidelines.

Ultrasound determination of total arterial wall thickness.

PURPOSE: Ultrasonic measurement techniques for determining intima-media thickness and total arterial wall thickness have been described. The intima-media thickness measurements are currently in use in large epidemiologic trials. Intima-media thickness does not evaluate extramedial atherosclerotic change and so may not fully reflect pathologic changes in the arterial wall. METHODS: After we performed variability studies of B-mode image acquisition and measurement, we measured total wall thickness and intima-media thickness of the common carotid arteries in 60 adult subjects in three groups: a control group aged 20 to 29 years, a control group aged 60 to 79 years, and a claudication group aged 60 to 79 years. Measurements were made with B-mode ultrasound images. RESULTS: No statistical difference between sexes was noted. A statistically significant (p < or = 0.05) increase in intima-media thickness and wall thickness was found with increasing age, and an additional increase was observed with clinically significant lower extremity arterial occlusive disease (p < or = 0.05). Image quality had an effect on measurement accuracy. CONCLUSIONS: The finding that the wall thickness of common carotid arteries is increased in those patients with clinically significant lower extremity disease supports the theory that atherosclerosis affects the arterial wall in a systemic fashion. Because intima-media thickness also increases across subject groups without change in its proportional contribution to the total arterial wall thickness, extramedial arterial changes also occur with aging and the development of atherosclerosis. We propose that because increases in wall thickness measurements of common carotid arteries follow intima-media thickness increase (but do not necessarily measure the same physiologic change) and the wall thickness method can be used in cases when the intima-media thickness cannot be measured, arterial wall thickness measurement may serve as an alternate or confirmatory test of peripheral artery atherosclerotic severity.

Renal atrophy and arterial stenosis. A prospective study with duplex ultrasound.

Renal artery disease is an important cause of both renal failure and hypertension. Duplex ultrasound is a reliable noninvasive method for classifying the severity of renal artery lesions and can be repeated to follow the course of the disease over time. The purpose of this study was to determine the changes in kidney size associated with various degrees of renal artery disease. Serial kidney lengths were measured as part of a prospective duplex ultrasound study of patients with renal artery narrowing. Fifty-four patients (22 men, 32 women; mean age, 65.8 years) with 101 renal artery and kidney sides eligible for follow-up were evaluated at 6-month intervals for an average of 14.4 months (range, 4 to 24 months). No kidneys with renal arteries classified as normal or less than 60% diameter stenosis by duplex criteria were found to have a decrease in length of greater than 1 cm during follow-up. In kidneys with a high-grade renal artery stenosis (> or = 60% diameter reduction), 26% (13 of 49 sides) were found to have a decrease in length of greater than 1 cm. The average decrease in length was 1.9 cm (range, 1.2 to 3.4 cm). By life table analysis, the estimated risk of a decrease in length of greater than 1 cm for kidneys with 60% stenosis or greater was 19% at 1 year. Loss of renal mass, as documented by ultrasound measurement of kidney length, is an important consequence of high-grade renal artery stenosis.

Natural history of atherosclerotic renal artery stenosis: a prospective study with duplex ultrasonography.

PURPOSE: Although the prevalence of renal artery stenosis in patients with peripheral arterial disease is in the range of 30% to 40%, the role of renal revascularization in patients without severe hypertension or kidney failure is controversial. Duplex scanning is a noninvasive technique that is ideally suited for screening and follow-up of renal artery disease. The purpose of this study was to document the natural history of renal artery stenosis in patients who were not candidates for immediate renal revascularization. METHODS: Eighty-four patients with at least one abnormal renal artery detected by duplex scanning were recruited from patients being screened for renal artery stenosis. Of the 168 renal artery/kidney sides, 29 were excluded (15 prior interventions, 6 nondiagnostic duplex scans, 8 presumed nonatherosclerotic lesions), leaving 80 patients with 139 sides for the follow-up protocol. Renal arteries were classified as normal, less than 60% stenosis, 60% or greater stenosis, or occluded by use of previously validated criteria. RESULTS: The study group included 36 men and 44 women with a mean age of 66 years who were monitored for a mean interval of 12.7 months. The initial status of the 139 renal arteries was normal in 36, less than 60% stenosis in 35, 60% or greater stenosis in 63, and occluded in 5. Although none of the initially normal renal arteries showed disease progression, the cumulative incidence of progression from less than 60% to 60% or greater renal artery stenosis was 23% +/- 9% at 1 year and 42% +/- 14% at 2 years. All four renal arteries that progressed to occlusion had 60% or greater stenoses at the initial visit, and for those sides with a 60% or greater stenosis, the cumulative incidence of progression to occlusion was 5% +/- 3% at 1 year and 11% +/- 6% at 2 years. The mean decrease in kidney length associated with progression of renal artery stenosis to occlusion was 1.8 cm. CONCLUSIONS: Progression of renal artery stenosis, as defined in this study, occurs at a rate of approximately 20% per year. Progression to occlusion is associated with a marked decrease in kidney length. Whether this natural history can be improved by earlier intervention for renal artery stenosis remains to be determined.