Biomedical subjects

R D Schultz

Publications and source records attributed to R D Schultz.

At least 37 records · Page 2Linked to original sources

PubMed1992

Comparative results of carotid-subclavian bypass and axillo-axillary bypass in patients with symptomatic subclavian disease.

The results of 26 carotid-subclavian bypass (CSB) and 17 axillo-axillary bypass (AAB) procedures, performed to treat symptomatic lesions of the proximal subclavian artery, were reviewed. Nine graft failures (seven CSB and two AAB) occurred (mean follow-up: CSB = 60.5 +/- 41 months; AAB = 67.8 +/- 48 months). All CSB graft thromboses were observed in patients with an associated ipsilateral carotid lesion, surgically treated or not (p less than 0.05). Cumulative 5- and 10-year patency rates were 78.3 and 62.9% for the CSB group and 87.9% for the AAB group (N.S.). In patients with an associated ipsilateral carotid lesion, 5- and 10-year patency rates were 66.0% and 40.8% for the CSB group and 100% for the AAB group (p less than 0.05). Both the surgical procedures were safe and effective with excellent results in terms of operative mortality, major morbidity and long-term patency. CSB is the procedure of choice for the treatment of proximal subclavian artery disease for its physiological characteristics and for graft shortness. However AAB must be considered a suitable alternative and preferred when a concomitant ipsilateral carotid lesion is present. Recurrence of carotid stenosis or carotid lesion progression may cause the carotid-subclavian failure.

Aged↗

PubMed1992

Endothelial cell seeding after carotid endarterectomy in a canine model reduces platelet uptake.

Post-endarterectomy platelet deposition may play an important role not only in vessel wall healing, but also in the development of progressive stenosis. Using a canine model, we investigated the effect of endothelial cell seeding on platelet deposition on endarterectomised arteries. Thirteen dogs underwent bilateral carotid intimectomy (5 cm long) and one side was seeded with an average of 2 x 10(6) viable freshly harvested endothelial cells. Blood flow was restored 20 min after seeding. On the contralateral side, a sham-seeding was performed. Deposition of 111indium-labelled autologous platelets was studied with sequential gamma camera images 3-5 h, 1, 2, 3, 4 days and 4 weeks after surgery. Platelet uptake was statistically reduced on the seeded side. Animals were killed at 4 weeks (nine dogs) and 5 weeks (four dogs) after surgery. Seven arteries for each group were found to be occluded. We conclude that endothelial cell seeding on endarterectomised arteries is feasible and reduces platelet uptake. Improvement in the efficiency of seeding and reduction of endothelial cell loss might permit clinical application of this technique.

Animals↗

PubMed1992

Healing of high-porosity polytetrafluoroethylene arterial grafts is influenced by the nature of the surrounding tissue.

The aim of this study was to determine the influence of the nature of the perigraft tissue in the healing pattern of high-porosity polytetrafluoroethylene (PTFE) vascular grafts. Nine-centimeter long segments of unreinforced experimental high-porosity (60 microns) PTFE grafts were placed as abdominal aortic interposition in mongrel dogs. Three grafts served as controls (group A); in five dogs (group B) a 25 x 25 cm piece of devascularized omentum was wrapped around the graft. In five dogs (group C) the omentum with its own vascular supply was completely wrapped around the graft. Animals were killed 4 weeks after surgery. The percentage of thrombus-free area was 31% in group A grafts, 39% in group B grafts, and 79% in group C grafts (p less than 0.01). Scanning electron microscopy showed many confluent areas of endothelium-like cells in the midportion of group C grafts, corresponding to capillary ingrowth. Transmural endothelial migration was more evident in group C grafts. We conclude that the nature of the perigraft tissue influences transmural capillary migration and the endothelialization rate of high-porosity PTFE grafts in dogs. Agents able to increase capillary formation in the perigraft tissue might improve endothelialization of vascular grafts.

Animals↗

PubMed1991

Effect of infection by bovine viral diarrhea virus (BVDV) in vitro on interleukin-1 activity of bovine monocytes.

The effect of bovine viral diarrhea virus (BVDV) infection in vitro on the interleukin-1 (IL-1) activity of bovine monocytes was studied. Supernatants from BVDV-infected monocytes suppressed IL-1-stimulated proliferation of mouse thymocytes and masked lipopolysaccharide-stimulated IL-1 activity of bovine monocytes in the mouse comitogen thymocyte assay. Suppression of mouse thymocyte proliferation was restored by the addition of IL-1. IL-1 inhibitory activity was induced both by the prototype variants BVDV/NADL cytopathic and BVDV/NY-1 noncytopathic and by BVDV variants isolated from persistently infected cattle. Suppressed IL-1 activity was also found in supernatants from monocytes from persistently infected cattle following infection with BVDV in vitro. No differences in levels of IL-1 mRNA synthesis were detected between BVDV-infected and uninfected monocytes by RNA-cDNA hybridization. These results suggest that infection of bovine monocytes with BVDV results in the production and/or activation of a soluble inhibitor of IL-1 activity.

Animals↗

PubMed1991

Adherence to bovine neutrophils and suppression of neutrophil chemiluminescence by Mycoplasma bovis.

The adherence of viable and heat-treated Mycoplasma bovis to bovine peripheral blood neutrophils was studied by specific immunofluorescence staining and flow cytometry. Viable and heat-treated M. bovis cells, adhered to bovine neutrophils in dose-dependent fashion within a 30 min incubation. Fluorescence quenching using crystal violet indicated that unopsonized M. bovis cells remained on the surface of bovine neutrophils without experiencing significant ingestion. The effect of M. bovis adherence on neutrophil microbicidal function was examined by measuring luminol enhanced chemiluminescence (CL). Adherent M. bovis cells did not elicit a bovine neutrophil CL response over a 75 min incubation period. M. bovis inhibited the capacity of bovine neutrophils to mount a CL response. Inhibition occurred whether viable or heat-treated M. bovis cells were used and it occurred when neutrophils were stimulated with opsonized zymosan (OZ) or phorbol myristate acetate (PMA). Inhibition of the PMA stimulated neutrophil CL response required cytadherence by M. bovis cells. These findings suggest that activation of the bovine neutrophil respiratory burst was inhibited at or distal in the pathway to the activation of protein kinase C (PKC), the site of PMA stimulation, and that it was mediated by a direct interaction between the adhering M. bovis cells and the bovine neutrophil membrane.

Animals↗

PubMed1991

Cellular immune responses in pigs fed a vitamin E- and selenium-deficient diet.

The effects of dietary restriction of vitamin E (Vit E) and selenium (Se) on lymphocyte proliferation, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC), and on burst respiratory response of stimulated granulocytes as measured by chemiluminescence (CL) were studied in pigs. Six male weanling pigs were maintained for 25 d on a torula yeast-based diet containing no measurable amount of alpha-tocopherol and less than .02 mg of Se per kilogram of feed. Six others received the same basal diet supplemented with 33 IU of DL-alpha-tocopheryl acetate and .2 mg of Se per kilogram of feed. All pigs were inoculated with Salmonella typhisuis on d 21 of the feeding period and killed on d 25. Tests to measure cellular immune functions were performed on cells isolated from blood samples taken on d 21 and 25. After 21 d of feeding, lymphocyte blastogenesis responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen in pigs fed the Vit E- and Se-deficient diet were normal compared with the response in pigs fed the supplemented diet. Moreover, the cytotoxic activity of NK cells, the ADCC response, and the CL response of granulocytes were not affected. After 25 d, a marked suppression of lymphocyte response to mitogens occurred in pigs fed the Vit E- and Se-deficient diet when the cells were cultured in the presence of autologous serum. When fetal bovine serum replaced autologous serum in the cultures, no suppression was observed. No effect on NK activity and ADCC was observed, whereas the CL peak response of granulocytes tended to be higher in pigs fed the deficient diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Prevalence of antibodies against canine parvovirus and canine distemper virus in wild coyotes in southeastern Colorado.

Serum from 72 wild coyotes (Canis latrans) in southeastern Colorado (USA) was collected and analyzed for prevalence of antibody to canine parvovirus (CPV) and canine distemper virus (CDV) from 1985 to 1988. The prevalence of antibodies to CPV and CDV was 71% and 57%, respectively, for the 4 yr of the study. Prevalence of antibody to CPV did not differ among years, between sexes, or with age. Prevalence of antibody to CDV did not differ among years or between sexes, but was significantly higher in adults (62%) than juveniles (33%). Prevalence of antibodies against CPV and CDV in southeastern Colorado was comparable to results reported in other serologic surveys in the western United States.

Animals↗

PubMed1990

Comparison of two techniques to isolate microvascular endothelial cells from the omentum.

The purpose of the study was to compare two different techniques for isolation of omental microvascular endothelial cells (ECs). Segments of unreinforced polytetrafluorethylene (PTFE) grafts, 9 cm long and 6 mm in diameter, were implanted in 22 dogs as an aortic interposition. Fourteen grafts were seeded with a mean of 7 x 10(5) viable ECs, derived from the microvessels of the omentum: eight grafts (group A) were seeded with ECs obtained by collagenase digestion and by filtration through a pore mesh; six grafts (group B) were seeded with ECs obtained by collagenase digestion and by Percoll gradient separation. In eight grafts (group C), the ECs were not added to the preclot mixture and served as a control. Animals were sacrificed 5 weeks after surgery. The percentage of thrombus-free area was 65 +/- 22% for group A grafts and 74 +/- 15% for group B grafts (NS). The subendothelial layer was 280 +/- 60 microns thick in group A and 220 +/- 30 microns thick in group B (P less than 0.05). Seeded grafts showed a higher production of 6-keto-PGF1 alpha after addition of sodium arachidonate than control grafts. Percoll gradient separation allows isolation of a more purified suspension of ECs. Refinements in omental EC procurement are still required to minimize contamination with other types of cells.

6-Ketoprostaglandin F1 alpha↗

PubMed1990

Bovine natural cell mediated cytotoxicity (NCMC): activation by cytokines.

Incubation of bovine peripheral blood mononuclear leukocytes (PBML) with the cytokines (CK) IL-2, alpha-IFN, gamma-IFN or IL-4 resulted in significant increases in natural cell mediated cytotoxicity (NCMC) over endogenous levels, as determined in an 18 h 51Cr-release assay using the human K562 or mouse Yac-1 target cell lines. Endogenous cytotoxic activity of bovine natural effector cells (NEC) using K562 or Yac-1 target cells was minimal (killing less than 8%). After 18 h of incubation with the CK hurIL-2, alpha-bovrIFN, gamma-bovrIFN or hurIL-4, NEC had significant increases in cytotoxic activity for both K562 and Yac-1 target cells. Significant increases in cytotoxic activity were not found after incubation of NEC with IL-1 or beta-IFN. Specific killing varied with CK concentration in a dose dependent manner and was proportional to effector:target cell ratio. Activation of the bovine NEC by CK was rapid, occurring within 6-12 h of incubation with alpha-IFN or gamma-IFN and within 12-18 h of incubation with IL-2. Incubation of bovine PBML with IL-2 and alpha- or gamma-IFN or with alpha-IFN and gamma-IFN showed that these CK do not act in a synergistic manner to increase NCMC in the bovine NEC.

Animals↗

PubMed1990

The mechanism of enhanced intraphagocytic killing of bacteria by liposomes containing antibiotics.

Liposomes containing aminoglycosides have been shown to enhance the killing of Brucella abortus and Staphylococcus aureus inside bovine phagocytic cells. This study examined the mechanism by which liposomes containing aminoglycoside enhance the intracellular killing of bacteria. Liposomes with entrapped aminoglycoside were found to significantly enhance the intraphagocytic killing of bacteria in bovine phagocytic cells (in vitro) when compared to free drug. Liposomes with entrapped aminoglycoside were also found to deliver significantly higher levels of aminoglycoside into phagocytic cells when compared to free drug (gentamicin) or free drug and liposomes without entrapped antibiotic. Antibiotic delivered to adherent phagocytic cells could be detected 3 days after treatment of the cells with liposomes containing aminoglycoside. No antibiotic could be detected in the supernatants of phagocytic cell cultures 3 days after treatment with liposomes containing antibiotic was only observed when the intraphagocytic bacteria were sensitive to the antibiotic entrapped in the liposomes. The rate of phagocytosis of S. aureus by cells treated with cationic liposomes (no entrapped antibiotic) did not differ from the rate of phagocytosis of control cells not treated with cationic liposomes. This study shows that the enhanced intraphagocytic killing of bacteria in bovine phagocytic cells occurs by direct delivery of entrapped antibiotic into the phagocytic cell by the liposome delivery vehicle and not by nonspecific enhancement of phagocytic cell function. Liposomes containing aminoglycoside appear to have no toxic effects on phagocytic cell function or viability in vitro.

Analysis of Variance↗

PubMed1990

Mycoplasma bovis suppression of bovine lymphocyte response to phytohemagglutinin.

The effect of viable Mycoplasma bovis on the in vitro bovine peripheral blood lymphocyte response to phytohemagglutinin (PHA) was studied. Results showed that M. bovis did not act as a mitogen for bovine lymphocytes. Viable M. bovis produced a dose and time dependent suppression of the PHA stimulated lymphocyte response. Suppression was not a result of differences in the viability of infected or control lymphocyte cultures. The suppressive effect of M. bovis was found to be independent of the concentration of PHA used in the test and the lymphocyte response could not be restored by supplementation of the culture medium with arginine. Delay for 48 h after PHA stimulation before adding M. bovis to the lymphocyte cultures diminished, but did not prevent, the suppression of the lymphocyte response. These results show that suppression of the lymphocyte response does not require the presence of M. bovis during the period of PHA stimulation, and that M. bovis was capable of interrupting [3H]-thymidine incorporation in lymphocytes which were actively synthesizing DNA.

Animals↗

PubMed1990

Sealed rupture of abdominal aortic aneurysms.

Sealed rupture of abdominal aortic aneurysms, even if uncommon, deserves particular attention for the possibility of misdiagnosis and for the deleterious effects of such a misdiagnosis. Sixteen patients (mean age 72 years; range 65 to 84 years) with chronic sealed rupture of abdominal aortic aneurysms are reported. Two patients had acute rupture of the aneurysm, and at operation chronic contained rupture was found along with the recent hemorrhage. One patient died after surgery. The remaining patients underwent successful resection with long-term survival and regression of symptoms. Consideration of sealed abdominal aortic aneurysm rupture should be included when examining elderly patients with history of unexplained back pain or femoral neuropathy. Computed tomography is a useful aid in the diagnosis of sealed rupture. Ultrasonography is less accurate; in three patients ultrasonography failed to diagnose the presence of the rupture.

Aged↗

PubMed1990

Detection of bovine viral diarrhea virus genome in leukocytes from persistently infected cattle by RNA-cDNA hybridization.

A bovine viral diarrhea virus (BVDV) cDNA library was constructed. One cloned complementary DNA sequence was used as a probe to detect BVDV RNA by hybridization in infected cell cultures and in mononuclear leukocytes from persistently infected cattle by dot blot and in situ hybridization. The cDNA probe hybridized with all cytopathic and noncytopathic BVDV isolates tested. The hybridization results were consistent with results obtained using conventional subculturing and immunofluorescent staining methods and by inoculation of seronegative test cattle.

Animals↗

PubMed1989

Efficacy of viral components of a nonabortigenic combination vaccine for prevention of respiratory and reproductive system diseases in cattle.

Efficacy and safety of components of an IM-administered vaccine for prevention of infectious bovine rhinotracheitis virus (IBRV), parainfluenza type-3 (PI-3) virus, bovine viral diarrhea virus (BVDV), and respiratory syncytial virus (RSV) infections and campylobacteriosis and leptospirosis were evaluated in cattle, including calves and pregnant cows. Challenge of immunity tests were conducted in calves for IBRV, PI-3 virus, or BVDV vaccinal components. All inoculated calves developed serum-neutralizing antibodies and had substantially greater protection (as measured by clinical rating systems) than did controls after challenge exposure to virulent strains of IBRV, PI-3 virus, BVDV, or RSV. In in utero tests, IBRV or bovine RSV vaccinal strains were inoculated into fetuses of pregnant cows. Histologic changes or abortions did not occur after fetal inoculation of the RSV vaccinal strain, and 10 of 14 fetuses responded serologically. Of 9 fetuses, one responded serologically to the IBRV vaccinal strain after in utero inoculation and was aborted 3 weeks later. In an immunologic interference test, 10 calves vaccinated with 2 doses of the multivalent vaccine, containing the 4 viral components and a Campylobacter-Leptospira bacterin, developed serum-neutralizing antibodies to IBRV, PI-3 virus, BVDV, and RSV without evidence of serologic interference. Under field conditions, 10,771 cattle, including 4,543 pregnant cows, were vaccinated. Vaccine-related abortions did not occur.

Animals↗

PubMed1989

Percutaneous transluminal angioplasty versus surgery for subclavian artery occlusive disease.

Twenty-one patients who underwent percutaneous transluminal angioplasty (PTA) for proximal stenosis of the subclavian artery were compared with 15 patients who underwent carotid subclavian reconstruction. This represents the first attempt to directly compare the two procedures. All patients had routine Doppler examination during follow-up. Mean follow-up was 30 +/- 24 months after PTA and 40 +/- 25 months after surgery. The incidences of procedural complications were similar (PTA one complication, surgery two complications). Although better early results were achieved in patients who underwent PTA (actuarial patency: PTA 91 percent, surgery 87 percent), after dilatation, we observed a continuous deterioration of the hemodynamic status of the artery, which led to a high rate of late restenosis (actuarial patency: PTA 54 percent, surgery 87 percent). There were no significant changes postoperatively. The specific role of each procedure is analyzed in view of the new acknowledgment of the clinical importance of proximal subclavian artery disease.

Angioplasty, Balloon↗

PubMed1989

Extrathoracic and transthoracic management of vascular disease of the aortic arch branches: a 16-year experience.

To determine factors influencing results of operation for proximal brachiocephalic arterial disease, a 16-year review of 74 consecutive patients was undertaken. A total of 62 subclavian, 14 common carotid, 6 innominate, and 2 vertebral arteries were revascularized during 79 procedures. The approach was transthoracic in 12 operations and extrathoracic in 67. Mean follow-up was 57 +/- 45 months. Two patients (2.5%) died of stroke after extrathoracic revascularization of the common carotid artery. Cumulative 5-year and 10-year freedom from neurological events was 81% and 75%, respectively. The best results were obtained with transthoracic procedures, with revascularization of the subclavian artery rather than the common carotid artery, and in operations performed in patients without associated distal carotid disease. In view of the recent progress in operative techniques and postoperative surgical care, the choice between the transthoracic approach and the extrathoracic approach should not be biased; rather, they should remain equal and viable alternatives based on anatomical and clinical features of the individual patients.

Adult↗

PubMed1989

Inflammatory aneurysms of the abdominal aorta: incidence, pathologic, and etiologic considerations.

Among 486 patients undergoing repair for abdominal aortic aneurysm (AAA) during a 12-year period, 30 (6.2%) had evidence of "inflammatory" AAA. One patient (3%) had acute rupture, and six patients (20%) had chronic contained rupture. Ureteral obstruction was evident in 20% of the patients. In the early period of the study there were two postoperative deaths and operative time and blood loss were significantly increased. In the last period of the study, no attempt was made to separate the duodenum and the ureters from the aneurysm; there was no operative mortality, and operative time and blood loss were similar to that of patients with atherosclerotic aneurysms. In 23 of 100 specimens of atherosclerotic AAA, microscopic findings resembling inflammatory AAA were found. On the basis of our study we conclude the following: (1) Inflammatory AAAs are simply atherosclerotic aneurysms that show an unusual accentuation of the chronic inflammation observed in relation to atherosclerotic aneurysms. (2) Operative technique should be modified to avoid excessive dissection and lysis of ureters and duodenum. (3) Excellent early and late results can be expected with proper surgical technique. (4) The causes of AAA are multiple, and chronic contained rupture of the aneurysm and reactive lymphatic hyperplasia might play a role of greater significance than previously thought.

Aged↗

PubMed1989

Ingestion and killing of Listeria monocytogenes by blood and milk phagocytes from mastitic and normal cattle.

Human listeriosis resulting from consumption of listeria-contaminated dairy products is emerging as a significant public health concern. There is a need to understand better the processes involved in the pathogenesis of Listeria monocytogenes-induced bovine mastitis. In the present report, we describe the results of the in vitro interaction of L. monocytogenes with bovine blood and milk leukocytes. Induction of an experimental L. monocytogenes mastitis resulted in a rapid and dramatic increase in neutrophils in the milk of infected cows. Blood neutrophils and mononuclear cells and milk leukocytes from listeria-infected and uninfected cows readily ingested L. monocytogenes in the presence of serum opsonins. These leukocytes also killed a portion of the ingested listeriae. Ingestion of listeriae evoked a vigorous chemiluminescence response by blood neutrophils and a relatively weak response by blood mononuclear cells. Ingestion, killing, and chemiluminescence by milk leukocytes were directly related to the percentage of neutrophils that were present. Blood neutrophils from healthy donor cattle ingested and killed L. monocytogenes when leukocyte-depleted milk and whey from mastitic cows were the sole sources of opsonins, although fewer listeriae were ingested than when normal bovine serum was present. These results indicate that bovine blood and milk phagocytes, like blood and inflammatory phagocytes from other mammalian species, can ingest and kill L. monocytogenes in vitro.

Animals↗