Bi- and trifunctional dichloroacetates were synthesized from the corresponding multifunctional alcohols or phenols and then employed as multifunctional initiators for the living radical polymerizations of methyl methacrylate mediated by RuCl2(PPh3)3 in the presence of aluminum compounds such as Al(OiPr)3 and Al(acac)3 (acac:  acetylacetonate). All these systems led to living polymerizations. However, the systems with Al(OiPr)3 involved partial transesterification of the ester units in the initiators, which resulted in the formation of a monofunctional initiator. In contrast, new systems with Al(acac)3 did not induce such transesterification and produced the multiarmed living polymers. 1H NMR analysis showed that polymers obtained with the di- and trifunctional esters possessed almost two and three arms, respectively, along with controlled molecular weights and their narrow distributions.

No abstract

The T cell function of congenitally athymic nude mice and rats, as well as the severe immunodeficiency resulting from thymic dysplasia in humans, can be corrected by implantation of intact thymus or thymic epithelium (1-5). Either syngeneic or allogeneic thymic grafts are effective for reconstituting T cell functions in congenitally thymus-deficient rodents (6-10), although these functions are generally less effective than those of intact normal animals. Such reconstituted nude mice (grafted with allogeneic thymus or thymic epithelial cells) accept skin grafts from the syngeneic and the donor strain, whereas those derived from a third strain are vigorously rejected (4, 1 1).In the present experiments, attempts were made to reconstitute T cell functions of nude mice by transplantation of thymic rudiments obtained from embryonic rats. The results show that these grafted mice gained T cell-mediated immune function, and accepted skin grafts from the donor rat strain. These mice, however, developed severe multiple organ-localized autoimmune diseases showing features similar to the autoimmunity observed in the mice after neonatal thymectomy, as reported previously (12-16). Materials and MethodsThymic Rudiment Transplantation. The rudiments of the thymuses were aseptically dissected from 15-d-old F344/DuCcj (F344) or ACI/NMs (ACI) rat embryos or 14-d-old BALB/cAJcl (BALB/c) mouse embryos (observation of vaginal plug = day 0). Female BALB/~ nu/nu mice, 5 wk of age, (Clea Japan Inc., Tokyo, Japan) were grafted under each kidney subcapsule with two lobes of thymic rudiments. This was done with an orally controlled micropipette introduced through a dorsal incision exposing the kidney. All mice were housed in a conventional animal-care facility.Chromosome Analysis. Chromosome analysis of lymphoid cells of thymic grafts was carried out by the air-drying method (17). The cells were harvested from 5 BALB/c nu/nu mice 8 wk after grafting with F344 thymic rudiments. Colchicine (0.05 mg/g body weight) was injected subcutaneously 2 h before harvest. Cells were treated with 1% sodium citrate in water for 5 rain at 37°C, fixed in cold acetic acid/methanol (1:1), and then

From 133 to 615 glomeruli were examined in sections of kidneys from each of 60 animals, representing six rodent models of proteinuria. Particular attention was paid to the position of segmental lesions. Lewis rats given sheep anti-rat glomerular basement membrane antibodies had lesions almost exclusively at the glomerulo-tubular junction. Wistar rats on a diet of 24 per cent casein or with subtotal nephrectomy and a diet of 24 per cent soya had lesions mainly at the hilum. Wistar rats given bovine serum albumin had global lesions but virtually no segmental lesions. Wistar rats given puromycin aminonucleoside had lesions at the glomerulo-tubular junction and global mesangial abnormalities shortly after the treatment but later developed segmental lesions at all parts of the glomerulus. Untreated BUF/Mna rats had lesions at the glomerulo-tubular junction early in life but later had lesions at all parts of the glomerulus. Untreated NZB/NZW hybrid mice had various types of glomerulonephritis and also had lesions at the glomerulo-tubular junction. These findings showed that (1) segmental lesions at the glomerulo-tubular junction, or glomerular tip, occur in experimental animals, a fact not previously reported, and these tip changes are a common feature in several different models of proteinuria; (2) hilar segmental lesions are seen in conditions with hyperfiltration of protein; and (3) segmental lesions at various parts of the glomerulus are seen in some models of proteinuria and probably indicate late effects of random toxic damage to the glomerulus. Thus, there are at least three different types of segmental glomerular lesions in experimental animals--tip, hilar, and random--with different morphology and pathogenesis. It is likely that these findings can be extended to human renal diseases with segmental glomerular lesions. This will help to clarify the controversial and unsatisfactory term focal segmental glomerulosclerosis.

Lymphopoiesis was studied in 3-month-old normal C57Bl mice and in 3-month-old C57Bl mice carrying from 12 to 48 C57Bl thymus grafts using tritiated thymidine labeling. Thymus graft lymphopoiesis was found to be identical with that of normal thymus tissue and the presence of thymus grafts was found to have no influence on host thymus lymphopoiesis. No evidence was found that the massive amounts of thymus graft tissue in the mice affected any parameter of host lymph node lymphopoiesis nor was any evidence detected for the migration of thymic lymphocytes from these massive deposits of thymus graft tissue either to host lymph nodes and blood or to other organs in the host animal. It is concluded that the majority of small lymphocytes produced in the thymus and thymus graft tissue do not migrate from these tissues but die locally at the end of their intrathymic life span of 3 to 4 days.