Essential role of vif in establishing productive HIV-1 infection in peripheral blood T lymphocytes and monocyte/macrophages.

The role of vif during the establishment of human immunodeficiency virus type 1 (HIV-1) infection of peripheral blood T lymphocytes and monocyte/macrophages was investigated using vif mutants of three HIV-1 proviral DNAs. Vif was found to be essential for the establishment of productive HIV-1 infection in peripheral blood T lymphocytes after cell-free infection with HXB2 and DFCI-HD, a vpr-positive, vpu-positive, nef-positive derivative of HXB2. A chimeric HIV-1 provirus in which the T-cell line-tropic env sequences in DFCI-HD were replaced with the macrophagetropic env of the ADA strain was constructed for studies on the role of vif during the establishment of HIV-1 infection in primary monocyte/macrophages. These studies showed that vif is also essential for the initiation of productive HIV-1 infection in primary monocyte/macrophage cultures after cell-free virus transmission. The DFCI-HD-ADA virus was shown to replicate in the CD4+ T-cell line Molt 4 clone 8 but not in other T-cell or monocytic cell lines, as previously shown for another macrophagetropic strain YU-2 (1), suggesting that this cell line may be useful for future studies on at least some macrophagetropic strains of HIV-1. The finding that vif is essential for the establishment of productive HIV-1 infection in primary T lymphocytes and monocyte/macrophages suggests that vif may be required for HIV-1 transmission and disease pathogenesis during natural infections and thus may be a good target for prophylactic or therapeutic intervention.

Normalization of hyperglycemia in diabetic rats by intraportal transplantation of cryopreserved islets from four donors.

Techniques for freezing rat islets have been examined by the intensive use of the supravital stains fluorescein diacetate and ethidium bromide. By the use of a simple scoring system, the effect of the cooling rate, treatment with dimethyl sulfoxide (DMSO), rate of thawing, and postthaw culture were examined. These studies showed the most effective method to be a 24-h culture of islets, followed by partial incubation with 20% DMSO at 0 degrees C, followed by seeding at -8 degrees C in an alcohol bath. The islets were then cooled at a rate of -0.25 degrees C/min to -40 degrees C followed by quenching in liquid nitrogen at -196 degrees C. Rapid thawing at 37 degrees C was then followed by a 24-h culture. Islets from four Lewis rat donors were cryopreserved, counted, and transplanted intraportally into streptozocin-induced diabetic Lewis rats. Corresponding control transplants were performed with islets from four donors only cultured for 48 h. The results showed that reversal of hyperglycemia in severely diabetic rats was obtained at 5, 5, 6, 6, 6, or 8 days with cryopreserved islets from four donors, compared to reversal of diabetes at 1, 4, 5, 6, 7, and 12 days with islets from four donors subjected to culture alone. The new cryopreservation technique has several small modifications over previously described methods and results in a significant improvement in islet survival.

The relevance of pressure changes in transplanted hearts and kidneys in immunosuppressed rats.

The pressure within rat cardiac and renal allografts has been observed to rise during rejection. We wished to see if this pressure rise could be prevented or reversed with immunosuppression. Transplants were performed from Lewis or DA donors to Lewis recipients. The rats received either a heterotopic cardiac transplant or an orthotopic renal transplant and were then treated with different immunosuppressive protocols. Intramyocardial pressure was recorded using a fine-gauge needle connected to an air pressure manometer. In the case of the renal transplants, a pressure transducer was used as well and the two methods compared. Intramyocardial and intrarenal pressures rose dramatically in unimmunosuppressed recipients of DA allografts. No such rise was seen in isografted organs, although the pressures recorded remained significantly higher than those found in untransplanted hearts and kidneys. Cyclosporine 20 mg/kg/day was effective in suppressing rejection in both models, and inhibited any rise in intraorgan pressure. Cyclosporine 10 mg/kg/day was less effective, and with 2 mg/kg/day allograft function was considerably impaired, one-third of the cardiac grafts being rejected by 16 days. In both models intraorgan pressures became raised. The addition of methylprednisolone 16 mg/kg i.p. on days 7 and 8 to this low dose regimen of cyclosporine 2 mg/kg/day rapidly reversed the rise in pressure and restored graft function to normal. Intraorgan pressure levels therefore accurately reflected the state of function of transplanted hearts and kidneys. When a manometer and a transducer were compared as a means of measuring the pressure in the renal transplants, the manometer method was found to be superior.