Pyrethroid-sprayed tents for malaria control: an entomological evaluation in Pakistan

Field trials were undertaken in the North West Frontier Province of Pakistan to determine the effects of pyrethroid-sprayed tents on feeding success, mortality and biting-rates of wild mosquitoes attracted to bait cows confined within the tents. Under natural conditions, endophagic mosquitoes rested only briefly in untreated tents during the night, followed by complete exodus at dawn. In tents sprayed on the interior surface with permethrin 0.5 mg/m2 or with deltamethrin 0.03 g/m2 the biting rate of Anopheles stephensi was reduced by about 40%; deterrency against culicines and other anophelines was much less. Mortality-rates of bloodfed mosquitoes from the treated tents were 75% An.stephensi, 65% An.subpictus but only 10% of culicines. Outer fly-sheets prolonged the effective life of the treatment; bioassays on the sprayed inner-sheets showed that insecticidal efficacy remained high for over a year, whereas on tents without fly-sheets permethrin residual efficacy declined rapidly 20-40 weeks post-treatment. It is concluded that tent-spraying with fast-acting photostable residual pyrethroid insecticide would probably provide effective protection against malaria transmission for the inhabitants of tents in any part of the world where the vector mosquitoes are endophilic and susceptible to pyrethroids.

Anti-CD4 monoclonal antibody treatment in combination with total lymphoid irradiation and cyclosporin A in hamster-to-rat cardiac transplantation. Morphological features of heart grafts, recipient spleens and lymph nodes

Significantly prolonged graft survival (GS) of hamster hearts transplanted heterotopically into rats can be achieved by different immunosuppressive treatment strategies. The exact mechanism of graft rejection is unclear, but it seems to be a primarily humoral, antibody-mediated type of rejection. The histopathology of long-term surviving grafts is controversial and the morphology of lymphoid tissue in spleens and lymph nodes as the possible site of anti-donor antibody formation has not previously been investigated. This report demonstrates a significantly prolonged GS in hamster-to-rat cardiac transplantation after combined treatment with total lymphoid irradiation (TLI), cyclosporin A (CyA) and anti-CD4 monoclonal antibodies (MAb), where long-term GS (> 100 days) could be achieved in a few animals. The histopathology of heart grafts showed predominantly chronic vascular changes with endothelial proliferation, intimal thickening and vessel obliteration. No substantial cellular reactivity in terms of mononuclear/lymphoid cell infiltration could be demonstrated in rejected grafts. Spleens and lymph nodes were characterized by a profound global reduction in lymphoid tissue after preoperative TLI. Although subsequent lymphoid regeneration was depressed due to postoperative immunosuppression, a significant increase in IgM-positive plasma cells was observed, supporting evidence of an antibody-mediated mechanism of graft rejection. The role of CD4+ cells is unclear, but anti-donor antibody formation might involve T-cell help.

Long-term cyclosporin A nephrotoxicity in the rat. Evaluation of a morphological scoring system and of co-treatment with isradipine

Cyclosporin A (CyA) nephrotoxicity was examined in Spraque-Dawley rats given CyA (12.5 (n = 45) or 25 (n = 45) mg/kg/day perorally for 16 weeks. Control rats (n = 45) received CyA vehicle. All rats were given either isradipine (ISRA) 1 or 5 mg/kg/day orally, or isradipine vehicle. Fifteen rats died from interstitial pneumonia caused by Staphylococcus xylosus. A predefined morphological CyA nephrotoxicity scoring system, based on semiquantitative scores for basophilic tubules and for interstitial fibrosis, performed on hematoxylin-eosin-stained tissue, yielded mean scores for basophilic tubules of 0.2 (range 0-1) in controls, 1.4 (range 0-3) in rats given CyA 12.5 mg/kg/day (p < 0.001), and 1.7 (range 0-3) in CyA 25 mg/kg/day rats (p < 0.001 as compared to controls). Rats given CyA were grouped according to their score for interstitial fibrosis: 0.2 (range 0-1) in CyA 12.5 mg/kg/day and 1.7 (range 0-3) in CyA 25 mg/kg/day rats (p < 0.001). When scores for basophilic tubules and interstitial fibrosis were pooled, none of the control rats had a score above 1, while 47% of the low-dose and 95% of the high-dose rats scored above 1. Thus, this CyA nephrotoxicity scoring system provided an easy, efficacious, and reproducible identification of rats with morphological CyA nephrotoxicity, and may be of clinical interest in the assessment of CyA nephrotoxicity. Kidney tissue from rats not treated with isradipine was further investigated with periodic acid-Schiff (PAS) with and without diastase treatment, and with Sirius Red. The latter confirmed the increase in connective tissue following tubular atrophy in CyA-treated rats. PAS reaction disclosed diastase-resistant positivity in the glomerular arterioles (score in controls: mean 0.4, range 0-1, in CyA 12.5 mg/kg/day mean 2.2, range 1-3, p < 0.001 as compared to controls; in CyA 25 mg/kg/day mean 1.1, range 0-2, p < 0.005 as compared to controls, p < 0.05 as compared to CyA 12.5 mg/kg/day). Furthermore, the straight part of the distal tubules of rats given the highest CyA dose contained considerable amounts of glycogen. The significance of this finding is unknown. Renal functional studies confirmed previous results since CyA decreased inulin clearance (Cin) from 1.2 +/- 0.5 to 0.8 +/- 0.3 ml/min/g kidney weight (kW) (p < 0.05), and lithium clearance (CLi) was reduced from 263 +/- 113 to 119 +/- 61 microliters/min/gKW (p < 0.001). Isradipine had no significant effect.

An ultrastructural analysis of concordant and discordant cardiac xenografts in unmodified recipients. A sequential study in rodents with special reference to endothelial cell changes in the microvascular system

Ultrastructural changes in endothelial cells in a hamster-to-rat and guinea pig-to-rat heart transplantation model are described. In the hamster-to-rat model, changes were minimal with an increase in cytoplasmic vesicles 4-6 h after transplantation. 16-24 h after transplantation larger vesicles appeared and the basement and cell membranes were less well defined. 42-48 h after transplantation the changes had progressed with destruction of cell membranes and the appearance of extravasated changes had progressed with destruction of cell membranes and the appearance of extravasated erythrocytes. At the time of complete rejection, changes had further progressed with widespread endothelial cell destruction and infiltration of neutrophilic granulocytes and macrophages, and large amounts of fibrin were present. In the guinea pig-to-rat model, changes were characterized by the appearance of platelets in close contact with the endothelium of the capillaries 1-3 min after transplantation. 4-6 min after transplantation the basement membranes as well as the cell membranes were affected with indistinct borders and interruption. Occasionally fusion of platelets and endothelial cell membranes was demonstrated. In the grafts examined 7-9 min after transplantation, changes had further progressed. Massive aggregation of platelets now appeared in relation to remnants of endothelial cells. Signs of microvascular damage appeared in both models, but with different morphology. In hamster grafts, endothelial cell activation is indicated by gradual changes in the cell membranes resulting in vascular damage and infiltration of the grafts by macrophages and neutrophilic granulocytes. In the guinea pig grafts, activation of endothelial cells results in platelet aggregation, formation of microthrombi, and subsequent tissue damage. Even though antibody and complement are involved in both types of rejection the basic mechanisms are different.

Immunosuppressive effect of total body irradiation and cyclosporine A on graft survival and the lymphatic system in a cardiac hamster-to-rat transplantation model

The aim of the study was to evaluate the effect of total body irradiation (TBI) and cyclosporine A (CyA) on graft survival and the lymphatic system in a concordant hamster-to-rat heart transplantation model, and to compare these effects with those of total lymphoid irradiation (TLI). Preoperatively TBI was given as a single dose of 5 Gy, CyA was given intramuscularly at a dose of 10 mg/kg/day. TBI prolonged graft survival to seven days. Combined TBI and CyA prolonged graft survival to ten days. The effect of TBI on graft survival, total white blood cell count (WBC) and differential counts was reproducible but not as distinct as the effect of TLI. Analysis of changes in WBC and differential counts combined with the morphology of the grafts at rejection and of spleens from TBI- and CyA-treated animals indicates a reproducible immunosuppressive effect of TBI and a severe type of acute humoral rejection with vasculitis and cellular infiltrates dominated by macrophages and neutrophilic granulocytes. In conclusion, we find TBI a simple pretreatment which may be useful in combination with other immunosuppressive treatment as preoperative induction and depletion therapy.

Anti-CD4 monoclonal antibody treatment combined with total lymphoid irradiation and cyclosporin A in hamster-to-rat cardiac transplantation. Analysis of lymphocyte subsets and anti-donor xenoantibodies

Combined treatment with total lymphoid irradiation and cyclosporin A results in prolonged graft survival in concordant xenogeneic cardiac transplantation, but reproducible long-term graft acceptance has proved to be difficult. Anti-CD4 monoclonal antibody treatment has been successful in inhibiting heart graft rejection in allogeneic models. Used as monotherapy in a concordant xenogeneic model for pancreatic islet transplantation, prolonged graft survival has been reported; however, no beneficial effect on primarily vascularized heart grafts was noted. The object of this investigation was to combine these treatment strategies with respect to reproducible long-term hamster heart graft survival in rats, to monitor the effect on lymphocyte subpopulations, and to determine possible anti-donor antibody formation correlated to time of rejection. Graft survival after combined preoperative total lymphoid irradiation and postoperative cyclosporin A + anti-CD4 monoclonal antibody treatment was prolonged from 14 to > 100 days (compared to spontaneous graft survival of three to four days), with long-term graft function in four of 19 recipients. Total white blood counts in the postoperative course were characterized by an unproportional increase of Ig+ cells and an incomplete recovery of CD4+ cells. Flow-cytometric analysis of anti-donor antibodies showed low levels of preformed antibodies and increasing amounts of strain-, but not donor-specific antibodies, correlated to the time of rejection. Long-term survivors with functioning grafts at the time of sacrifice had an initially moderate antibody increase with subsequent decrease to baseline levels. Our results indicate that total lymphoid irradiation combined with cyclosporin A and anti-CD4 monoclonal antibodies can prolong graft survival significantly in concordant hamster-to-rat cardiac xenotransplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for a primarily humoral rejection mechanism in concordant xenogeneic heart transplantation. A sequential immunohistological study in a hamster-to-rat model

Heterotopic heart transplantations in an unmodified hamster-to-rat model were studied sequentially by immunohistochemical analysis. Monoclonal mouse anti-rat antibodies against B cells, T cells, macrophages and neutrophilic granulocytes (MRC OX-19, MRC OX-38, MRC OX-8, MRC OX-22, MRC OX-33, MRC OX-41 and MRC OX-42) were used in an indirect immunoperoxidase technique and monoclonal mouse anti-rat IgM and IgG were used for immunofluorescence. In grafts investigated after 6 h (N = 8) minimal infiltration of macrophages was demonstrated with MRC OX-41+ and MRC OX-42+ cells. No T- or B cells were seen. In a few cases, deposition of IgG and IgM was seen related to the endothelium of larger vessels. In grafts examined 24 h after transplantation (N = 10) the number of MRC OX-41+ and MRC OX-42+ cells had increased and in half of the cases IgM and IgG were located in relation to endothelial cells of larger vessels. In grafts investigated 48 h after transplantation (N = 8) the infiltration with MRC OX-41+ and MRC OX-42+ cells had further increased and a few scattered MRC OX-19+ and MRC OX-8+ cells appeared. At this time all but one heart had deposition of IgG and IgM in the vessel walls. Upon complete rejection (N = 8) diffuse infiltration of MRC OX-41+ and MRC OX-42+ cells was seen, but still only a few scattered T cells could be demonstrated. At this time IgG an IgM deposition appeared in all vessels and was also located in relation to the capillaries. These results further support our hypothesis that acute xenograft rejection in this animal model is primarily of the humoral type.

The mersilene covered intraorbital implant

The most widely used material for covering spherical intraorbital implants is sclera. Mersilene mesh is an alternative substance combining the advantages of permanent implant cover with low rates of infection and ready availability. We describe our experiences in the use of Mersilene mesh covered intraorbital implants in 14 patients. Our findings suggest that Mersilene mesh could be considered as a possible alternative choice of material for covering intraorbital implants.

Survival, function, morphology and serological aspects of rat renal allografts. Effect of short-term treatment with cyclosporine A, anti-CD4 and anti-interleukin-2 receptor monoclonal antibodies

The aim of this study was to investigate the effect of short-term treatment with cyclosporine A (CyA) combined with anti-CD4 (OX-38) and anti-interleukin-2 receptor (OX-39) monoclonal antibodies (MAbs) on graft survival, graft function, morphology, and anti-donor antibody levels in a BN-to-LEW rat kidney transplantation model. Spontaneous rejection occurred at 9.3 days (range 9-10 d). Administration of CyA (12.5 mg/kg/d) for 14 days prolonged graft survival to 33 days (range 23-40 d, P less than 0.02). Supplementing with OX-38 and OX-39 100 micrograms/kg/d, given i.p. from days 0 to 7, further prolonged graft survival to 70 days (range 38- greater than 100 d, P less than 0.02 vs controls and CyA group). One of seven recipients had good graft function for more than 100 days. A three-fold increase of the MAb dosage did not improve mean graft survival (53.5 d), but three of eight recipients had well functioning grafts for greater than 100 days. Kidney function was characterized by reduced creatinine clearance, also in the recipients with long-term graft survival, and a defect in concentrating urine creatinine with subsequent pronounced increase in urinary output. Graft histology showed a complex pattern of interstitial alterations including mononuclear cell infiltration, fibrosis, tubular atrophy and vascular damage with intimal/endothelial cell hyperplasia and perivascular inflammation. In nine of 10 MAb-treated recipients with graft survival greater than 60 days, granular deposits of immunoglobulins and C3 were found by immunofluorescence microscopy (IFM). The deposits were localized in the glomerular capillaries and mesangium. IFM in MAb-treated control animals could not demonstrate any deposits. Flow cytometric evaluation of posttransplant serum samples against donor target cells showed increasing amounts of anti-donor antibodies until the time of rejection, while recipients with long-term graft function had moderately positive cross-matches up to two months after transplantation. Hereafter antibody titres decreased and cross-matches at the time of sacrifice were again negative. The morphological findings and the flow cytometric cross-match results seem to indicate a postponed antibody-mediated type of rejection. The reason why some kidney recipients showed decreasing antibody titres and stable long-term graft function is unclear.

Single and combined effects of the vitamin D analogue KH1060 and cyclosporin A on mercuric-chloride-induced autoimmune disease in the BN rat

Mercuric chloride induces in BN rats a self-limiting systemic autoimmune disease characterized by proliferation of autoreactive CD4+ T lymphocytes, polyclonal activation of B lymphocytes, and the development of an anti-glomerular basement membrane (GBM) nephritis with concomitant nephrotic range proteinuria. We have used this model of autoimmune disease to test the immunosuppressive ability of a novel vitamin D3 analogue KH1060. This compound prevents autoimmune manifestations including proteinuria, serum IgE, and serum anti-laminin antibodies in a dose-dependent manner, as does cyclosporin A (CyA). When dosages of KH1060 capable of partial reduction of proteinuria without causing significant hypercalcaemia are combined with small dosages of CyA also capable of partial prevention of proteinuria, an additive effect is seen, leading to complete prevention of proteinuria and substantial reductions in serum IgE and anti-laminin levels. Possible mechanisms of action are discussed and it is suggested that KH1060 could prove useful as an immunosuppressive agent in the treatment of autoimmune diseases.