D. W. Johnson

Suppression of in vitro immunoglobulin biosynthesis in bovine spleen cells by bovine viral diarrhea virus

Abstract Incubation of bovine splenic lymphoid cells with pokeweed mitogen (PWM) and bovine viral diarrhea (BVD) virus for 5 days caused a consistent, statistically significant decrease in plasma cell development (cells containing intracytoplasmic immunoglobulin) as well as IgG or IgM synthesis compared to cultures without BVD virus. Suppression of plasma cell development and immunoglobulin synthesis was not due to decreased cell viability in virus-infected cultures even though virus replication was evident in both PWM-stimulated as well as control cultures. Finally, it was shown that heat-inactivated BVD virus was not capable of suppressing either plasma cell development or immunoglobulin synthesis. Thus, these data support the hypothesis that BVD virus can alter B-cell responses, plasma cell development, and subsequent synthesis of IgG and IgM immunoglobulins.

Potential use of lymphocyte blastogenic responses in diagnosis of bovine tuberculosis

Abstract A comparison of in vitro lymphocyte responses and delayed type tuberculin skin test responses was made in an animal experimentally exposed to a Mycobacterium bovis -infected animal and in cattle naturally infected with M. bovis . Tuberculin skin tests did not suppress in vitro lymphocyte responses to M. bovis PPD and to M. avium PPD tuberculin. The whole blood test used in these studies provided for considerable savings in time as compared to use of purified lymphocytes for evaluating in vitro cellular responses. Variations in the responsiveness of lymphocytes to specific mycobacterial antigens was observed, therefore, it is recommended that profiles be established using three or more tests conducted at 14-day intervals.

A Distributed Hardware Mechanism for Process Synchronization on Shared-Bus Multiprocessors

Several techniques have been used to reduce the performance impact of process synchronization in fine-grained multiprocessor systems. These existing techniques tend to have long synchronization times or high shared-bus use, or they require complex and expensive hardware. A new technique is presented that uses distributed hardware locking queues to reduce both contention and latency to the minimum values that can be obtained using a shared-bus. This technique is shown to require at most two shared-bus transactions, with one transaction being typical. The latency for process continuation after obtaining a lock is reduced to near zero. Barrier synchronization using this distributed mechanism requires only one shared-bus transaction per processor involved in the barrier. This new technique is scalable and applicable to both new architectures and to existing systems, and is less complex than other hardware solutions.

Low-Cost, High-Performance Barrier Synchronization on Networks of Workstations

Circulating active barrier (CAB) is a new low-cost, high-performance hardware mechanism for synchronizing multiple processing elements (PEs) in networks of workstations at fine-grained programmed barriers. CAB is significantly less complex than other hardware barrier synchronization mechanisms with equivalent performance, using only a single conductor, such as a wire or copper run on a printed-circuit board, to circulate barrier packets between PEs. When a PE checks in at a barrier, the CAB hardware will decrement the count associated with that barrier in a bit-serial fashion as a barrier packet passes through, and then will monitor the packets until all PEs have checked in at the barrier. The ring has no clocked sequential logic in the serial loop. A cluster controller (CC) generates packets for active barriers, removes packets when no longer needed, and resets counters when all PEs have seen the zero-count. A hierarchy of PEs can be achieved by connecting the CCs in intercluster rings. When using conservative timing assumptions, the expected synchronization times with optimal clustering are shown to be under 1 ?s for as many as 4096 PEs in multiprocessor workstations or 1024 single-processor workstations. The ideal number of clusters for a two-dimensional hierarchy ofNPEs is shown to be N(D+G)/(I+G)]1/2, whereGis the gate propagation delay,Dis the inter-PE delay, andIis the intercluster transmission time. CAB allows rapid, contention-free check-in and proceed-from- barrier and is applicable to a wide variety of system architectures and topologies.

Development of a whole blood lymphocyte stimulation assay for detecting hypersensitivity to PPD in cattle experimentally infected with Mycobacterium bovis

Abstract A whole blood lymphocyte stimulation assay utilizing the uptake of tritiated thymidine was developed for the detection of Mycobacterium bovis sensitivity in cattle. Results on eight M. bovis infected animals (six to ten weeks after infection) and eight control animals show that satisfactory lymphocyte stimulation can be obtained using heparinized whole blood diluted 10-fold in tissue culture medium and cultured with purified protein derivative (PPD) for three to seven days. Infected animals exhibited significantly greater stimulation when cultured with PPD than did control animals.

Tumor associated antigens of bovine cancer eye

A study was conducted to determine the presence of surface antigens on cultured cells of bovine ocular squamous cell carcinoma (BOSCC) by serological testing. Serum from cattle with plaque and malignant stages of disease were tested for reactivity with surface antigens of cultured autologous and allogeneic cells. Indirect immune fluorescence assays were conducted to determine the presence of antibodies towards these tumor cells. It was found that sera tested possessed antibodies to the cultured tumor cells. Further, no surface reactivity was observed when these sera were tested for reactivity with normal epithelial cells. Reactive sera were analyzed by absorption tests with autologous and allogeneic cells. Absorbed sera showed no reactivity to surface antigens or allogeneic cells. This study suggests that there might be a shared antigen among the cells from plaque and malignant lesions.

Monocyte-induced potentiation of bovine fetal thymocyte mitogenic responses to concanavalin A

Peripheral blood monocytes significantly potentiated the mitogenic response of bovine fetal thymocytes to Concanavalin A as measured by incorporation of [3H] thymidine into cellular DNA. Mononuclear cells obtained from either normal or Mycobacterium bovis sensitized cattle were cultured with or without purified protein derivative (PPD) for 24 hours at which time bovine fetal thymocytes and concanavalin A were added. After 3 days of culture, both activated or non-activated monocytes significantly potentiated Con A-induced blastogenic responses. of monocytes from thymocyte cultures completely abrogated thymocyte responses to Concanavalin A.

Application of a whole-blood lymphocyte stimulation test in detection of Brucella infection in an outbreak

A whole-blood lymphocyte stimulation test (WBLST), the standard plate and tube agglutination tests, the Brucella buffered antigen test, the 2-mercaptoethanol agglutination test, the Rivanol plate precipitation test and bacteriological isolation were utilized in a brucellosis outbreak investigation in a beef herd. Three of the animals were classified as not infected serologically. However, these 3 animals were classified as infected on the WBLST, andBrucella abortus biotype 1 (not strain 19) was isolated from their lymph nodes. The WBLST exhibited significant sensitivity in this investigation and more observations of this nature might strengthen the application of this assay in similar situations.

In vitro stimulation of bovine milk lymphocytes standardization of the assay for bovine brucellosis

Abstract Lymphocytes of bovine milk origin were investigated by immunostimulation in vitro to standardize the assay for measuring the immune responses of the cells which might be useful in further understanding the immunopathology and diagnosis of bovine brucellosis. The lymphocytes were separated from whole freshly collected milk by centrifugation. The pellet of lymphocytes was washed in RPMI-1640 medium, cultured at different concentrations for different days and with Brucella abortus soluble antigen strain 1119-3 and Concanavalin A. Each culture was labelled with 1.0 μCi of methyl-[3H]thymidine 16–18 hours prior to termination of incubation at 37 C. Termination was done by cooling to 4 C. The cells were harvested for liquid scintillation counting spectrometry. In the groups of calfhood vaccinated cows and nonexposed milkers, a milk lymphocyte concentration of 2.0 × 106/ml of medium yielded a statistically significant blastogenesis. The Brucella abortus soluble antigen concentration of 4.4 μg of protein/well was found optimal to induce significant immunostimulation. A period of 4 days of incubation of the milk lymphocyte in the test was found optimal in inducing statistically significant blastogenesis in this system.

Specific in-vitro lymphocyte immunostimulation activities of Brucella abortus fractions obtained by column chromatography

Abstract A Brucella abortus soluble antigen (BASA) preparation and fractions obtained thereof, by column chromatography, were compared in terms of their ability to induce specific lymphocyte stimulation responses (LSR) in lymphocytes from cattle infected with B. abortus . Endotoxin and protein contents and the fractions were determined. The LSR induced by BASA and the fractions were compared in terms of correctly identifying samples from infected and non-infected cattle. The sensitivity and specificity for each preparation were determined and these two attributes were then correlated with endotoxin and protein content. The results suggest that lymphocyte stimulation had greater association with relative protein content than endotoxin content of the antigen preparations.