Improved immediate function of renal allografts with Belzer perfusate

The characteristics of 254 cadaveric kidneys were evaluated and the incidence of immediate function identified. The Belzer perfusate was used primarily (n = 140) and secondarily (n = 14) in combination with pulsatile machine perfusion. These two groups were compared with a previous group of kidneys machine-perfused with silica gel (cryoprecipitated human plasma). The incidence of immediate function of the group primarily perfused with Belzer perfusate was statistically significantly improved over that of the silica gel. The secondarily perfused Belzer group, "imported" kidneys previously preserved with simple cold storage, had notably longer periods of preservation and higher resistances on the machine. However, 100% of this group functioned immediately. Other findings in this study show that the Belzer perfusate allows for improved parenchymal function posttransplant, as noted by a more rapid clearance of serum creatinine posttransplant. When comparing the immediate function group with those suffering early dysfunction, there is a statistically significant increased resistance on the machine in the latter group. This allows for prediction of immediate function based on perfusion characteristics of the kidney. The Belzer perfusate, composed of metabolic substrates for high-energy phosphate production, improves the incidence of immediate function in machine-perfused kidneys, as well as improved qualitative function posttransplant. It also is effective as a "rescue" mechanism in previously simple cold-stored (ATP-depleted) kidneys.     

The effect of antigen deprivation on thymus-dependent and thymus-independent lymphocytes in the small intestine of the mouse

Isografts of foetal small intestine, implanted under the kidney capsules of adult mice grow normally and, despite the lack of intraluminal antigenic stimulation, are populated by thymus-dependent and thymus-independent lymphocytes. The Peyer's patches in these grafts are very small, lack germinal centres and can be shown to have small thymus-dependent areas.

Quantitative intraepithelial lymphocyte counts were carried out in normally sited small intestine of immunologically intact and thymus-deprived mice, and in grafts implanted in intact and thymus-deprived mice. Counts were also performed in a group of neonatally thymectomized and control mice. The results show a significant depletion of intraepithelial lymphocytes in neonatally thymectomized mice, and a profound reduction in numbers of intraepithelial lymphocytes in grafts, deprived of antigen, when compared with normally sited intestine of the same age.

     

Effect of cyclosporin A on rat mucosal mast cells and the associated protease RMCPII.

The effects of Cyclosporin A (CyA) on rat mucosal mast cells (MMC) have been investigated by cell counts in the jejunal mucosa and assays of the MMC-specific granule protease RMCPII in tissues and serum. CyA was administered by subcutaneous injection; for the majority of experiments the rats received 50 mg/kg daily for 3 days as a loading dose, then 50 mg/kg on alternate days. Treatment with this drug has two actions on MMC, a gradual reduction in the number of MMC and in the tissue content of RMCPII in the jejunum; and a rapid fall in the serum concentration of RMCPII, detectable 3 h after i.v. administration of CyA, 50 mg/kg. These phenomena were demonstrated in normal rats and in animals with an expanded jejunal MMC population due to graft vs host reaction or recent helminth infection. The functional relevance of the MMC depletion was demonstrated in immune rats given CyA for 3 days prior to induction of systemic anaphylaxis; intestinal permeability to i.v. Evan's blue was significantly reduced by CyA treatment. We suggest that CyA depletes intestinal MMC by suppression of T-cell-mediated regulatory stimuli to proliferation of mast cell precursors and/or their migration. The effects of the drug on serum RMCPII, evident before there were changes in the number of intestinal MMC, indicate that it also suppresses the secretion of granule mediators by MMC, probably indirectly via effects on mucosal T cells.     

Activation of swine peripheral blood lymphocytes with human recombinant interleukin-2.

These studies examined the effect of the lymphokine interleukin-2 (IL-2) on porcine peripheral blood lymphocytes (PBL). Cultures of porcine (Yorkshire) PBL in human recombinant (r) IL-2 had a time-dependent increase in activation of killer cells. Previous reports of porcine killer cells derived from PBL indicated maximal lysis 18 hr after killer and target cells were mixed, with very little lytic activity at 4 hr. After culturing for 2 days in rIL-2, the cells acquire enhanced lytic capabilities resulting in substantial target lysis in the 4-hr assay. Enhanced lytic activity in the 18 hr assay occurs as early as 30 min after exposure to rIL-2, with a more significant increase after 2 days' exposure. The IL-2-treated cells have an increase in the incorporation of tritiated thymidine and an increase in percentage of granular cells. Tumour targets, such as Daudi, which are resistant to lysis, and L929, Mdt4 and P815, which are moderately susceptible to lysis by untreated swine PBL, had a substantial increase in lysis in IL-2-treated swine PBL. These results indicate human rIL-2 induces functional and morphological changes in swine peripheral blood lymphocytes.     

Experimental staphylococcal endocarditis and aortitis

Summary The initial colonization, byStaphylococcus aureus, of the catheter damaged aortic valve and aorta of the rabbit, was examined by light and electron microscopy at 15 min, 3 h and 24 h post inoculation (PI). At 15 min PI, the majority of bacteria (80%) were located on the lateral surfaces of the thrombic vegetations while 20% were attached directly to the connective tissue of the aortic valve and aorta in areas where the endothelial lining was disrupted. By 3 h the bacteria on the thrombic vegetations were covered by fibrin. At this time, the bacteria both within the vegetations and on the surface of the vasculature were undergoing multiplication to form small groups. The precipitation of thrombus around the bacteria attached to the surface of the aorta to form microscopic infected vegetations had occurred by 24 h PI. The colonizing bacteria did not elicit any phagocytic response. The colonization of the cardiovasculature byStaph. aureus did not necessarily require pre-existing vegetations.     

2-Hour cytomegalovirus pp65 antigenemia assay for rapid quantitation of cytomegalovirus in blood samples

Of 109 blood samples tested for cytomegalovirus (CMV) antigenemia, 18 (16.5%) were positive. CMV Brite detected 13 and CMV Brite Turbo detected 16 of the 18 positives. There was no significant difference in the number of positive cells detected per sample. The seven discrepant samples contained a median of only one positive cell.     

Staphylococcal exopolysaccharides inhibit lymphocyte proliferative responses by activation of monocyte prostaglandin production.

The glycocalyx (exopolysaccharides) of Staphylococcus epidermidis has been reported to inhibit a variety of host defense mechanisms. We have examined the inhibitory effects of glycocalyx on the proliferation of human peripheral blood mononuclear cells (PBMC) and the mechanism of this inhibition. Glycocalyx isolated and partially purified under endotoxin-free conditions from defined liquid medium cultures of S. epidermidis and Staphylococcus lugdunensis inhibited the proliferative response of PBMC when added to cultures at 10 to 100 micrograms/ml. Glycocalyx-mediated inhibition of phytohemagglutinin-stimulated proliferation of PBMC required the presence of plastic-adherent peripheral blood monocytes. Culture supernatants of monocytes stimulated with glycocalyx contained a soluble factor that inhibited the proliferation of monocyte-depleted PBMC. This soluble inhibitory factor was not produced in the absence of glycocalyx or in the presence of both glycocalyx and indomethacin. Analysis of the supernatants of cultures of adherent monocytes revealed that glycocalyx from S. epidermidis and from S. lugdunensis could activate monocyte production of prostaglandin E2 (PGE2), human interleukin-1, and tumor necrosis factor alpha. The addition of purified PGE2, at the same levels of PGE2 (greater than or equal to 10(-9) M) generated in the monocyte cultures, to PBMC cultures resulted in a similar inhibition of proliferative responses. It is concluded that, contrary to previous suggestions, the bacterial glycocalyx does not have a direct inhibitory effect on T lymphocytes. However, it does appear that glycocalyx from coagulase-negative staphylococci can activate monocyte PGE2 production and that it is this activity that in turn contributes to the inhibition of T-cell proliferation.     

Effect of delayed specimen processing on cytomegalovirus antigenemia test results.

Blood samples held at either 4 degrees C or room temperature for 1 day had similar mean decreases in number of cytomegalovirus antigenemia-positive cells (52 to 55%) and similar false-negative test results (13 to 14%). After 2 days, samples held at 4 degrees C showed no further decline, whereas samples held at room temperature had a mean 81% decrease in positive cells, a 32% false-negative rate, and a more marked deterioration in cell morphology.     

High rates of clustering of strains causing tuberculosis in Harare, Zimbabwe: a molecular epidemiological study

We examined the pattern of tuberculosis (TB) transmission (i.e., reactivation versus recent transmission) and the impact of human immunodeficiency virus (HIV) infection in Harare, Zimbabwe. Consecutive adult smear-positive pulmonary TB patients presenting to an urban hospital in Harare were enrolled. A detailed epidemiological questionnaire was completed, and tests for HIV type 1 and CD4 cell counts were performed for each patient. Molecular fingerprinting of the genomic DNA recovered from cultures of sputum was performed by two molecular typing methods: spacer oligonucleotide typing (spoligotyping) and analysis of variable number of tandem DNA repeats (VNTRs). A cluster was defined as isolates from two or more patients that shared the same spoligotype pattern or the same VNTR pattern, or both. DNA suitable for typing was recovered from 224 patients. The prevalence of HIV infection was 79%. Of 187 patient isolates (78.6%) typed by both spoligotyping and analysis of VNTRs, 147 were identified as part of a cluster by both methods. By spoligotyping alone, 84.1% of patient isolates were grouped into 20 clusters. The cluster size was generally <8 patient isolates, although three large clusters comprised 68, 25, and 23 patient isolates. A total of 89.4% of the patient isolates grouped into 12 clusters defined by analysis of VNTRs, with 2 large clusters consisting of 127 and 13 patient isolates, respectively. Thirty-six percent of patient isolates with a shared spoligotype and 17% with a shared VNTR pattern were geographically linked within Harare, but they were not linked on the basis of the patient's home district. In a multivariate analysis, there were no independent predictors of clustering, including HIV infection status. Comparison with the International Spoligotype database (Pasteur Institute, Pointe a Pitre, Guadeloupe) demonstrated that our three largest spoligotype clusters are well recognized and ubiquitous in Africa. In this epidemiologically well characterized urban population with a high prevalence of HIV infection, we identified a very high level of strain clustering, indicating substantial ongoing recent TB transmission. Geographic linkage could be detected in a proportion of these clusters. A small group of actively circulating strains accounted for most of the cases of TB transmission.