Recognition and response to alloantigens in vivo. I. Negative and positive selection of MLR reactivity in murine peripheral blood lymphocytes to major histocompatibility complex and Mls antigens

Specific mixed lymphocyte reaction (MLR) responsiveness to allogeneic major histocompatibility complex (MHC), or minor lymphocyte-stimulating (Mls) determinants, was depleted in the peripheral blood lymphocytes (PBL) obtained from mice 24 to 48 hr after i.v. injection of 5 to 7.5 X 10(7) MHC or Mlsa-incompatible spleen cells, respectively. Results of cell mixture experiments suggest that the generation of suppressor cells was not the explanation for this specific reduction in MLR proliferation occurring with these PBL responder cells. To gain additional insight into parameters involved in the recognition of allodeterminants in vivo, experimental manipulations of the host environment and donor cell inoculum utilized in the negative selection procedure were employed. For example, removal of the spleen in the recipient animal, an anatomic site in which injected allogeneic cells and corresponding host antigen-reactive cells (ARC) are trapped, still permitted the specific depletion in murine PBL of host ARC for donor foreign MHC antigens. This finding may implicate other sites such as the liver where unprimed host alloreactive clones are trapped. In addition, irradiation of allogeneic donor cells significantly reduced their capacity to trap alloreactive T cell clones in vivo, whereas heat treatment of the donor cells completely eliminated this ability, even though the Ia determinants were still expressed, measured by flow cytometry. After the negative selection period, kinetic analysis of proliferation showed that 3, 4, or 5 days after injection of MHC-incompatible allogeneic spleen cells, the PBL of the recipient showed specific hyperresponsiveness to the MHC-haplotype of the donor cells. Interestingly, these primed PBL responder cells had the volume distribution of small resting cells; thoracic duct lymphocytes (TDL), positively selected by adoptive transfer of T cells to irradiated semiallogeneic recipients, are reported to be mainly blast cells. In contrast to the MLR hyperresponsiveness that results from priming with MHC-incompatible splenocytes, PBL, obtained at these later time points from mice primed with Mlsa-incompatible, H-2-compatible splenocytes, showed complete unresponsiveness in MLR to these Mlsa-bearing stimulator cells, as well as some nonspecific reduction in proliferation to MHC-incompatible stimulator cells regardless of their Mls genotype.(ABSTRACT TRUNCATED AT 400 WORDS)     

Target-specific nerve regeneration through a nerve guide in the rat

Nerve regeneration across a gap in peripheral nerve has been achieved through various nonneural nerve guides in both lower and primate species. This technique can only be useful if the regenerated nerve cable grows specifically to and reinnervates the appropriate distal target. In this study, the proximal peroneal fascicle of rat sciatic nerve was inserted into the proximal limb of a Y-shaped nerve guide. Distal peroneal and tibial fascicles were placed within the two distal limbs of the same Y. The proximal peroneal nerve grew preferentially by a 2:1 ratio to the appropriate distal peroneal fascicle suggesting that target-specific reinnervation is possible through a nerve guide.     

Seasonal and size-related changes in the food of the short-finned eel,Anguilla australis in Lake Ellesmere,Canterbury, New Zealand

Synopsis An approximately monthly sampling programme in Lake Ellesmere, Canterbury, New Zealand, from January 1974 to April 1976 yielded 487 eels. The stomachs were fixed in 10% neutralised formalin and the contents examined. Preliminary analysis indicated that the mollusc Potamopyrgus antipodarum, the isopod Austridotea annectens, the mysid Tenagomysis chiltoni, the amphipod Paracalliope fluviatilis, the midge larva Chironomus zealandicus and the teleosts Retropinna retropinna, Galaxias maculatus and Gobiomorphus cotidianus together made up the bulk of the diet. The pre-ingested dry weight (i.e. the reconstructed weight) of the most important of these prey species was obtained by relating the length of a digestion resistant part to actual dry weight in field collected specimens. Regression equations for this relationship in each season enabled the reconstructed dry weight of each stomach item to be calculated. In some instances reconstructed weight was less than the actual digested dry weight of the prey specimen. In every case the larger value was used. This method is referred to as Combination Dry Weight (CDW) and is believed to be new. These data, used in conjunction with the energy content of the species concerned, enabled the caloric dietary contribution of each prey species to be determined. Comparison of relative contribution to eel diet between CDW and energy values calculated from CDW and bomb calorimetry revealed large differences. Marked variations in diet between ⩽40 cm, 40.1–50 cm, and>50.1 cm size classes were also shown. Eels ≤40 cm feed primarily on invertebrates and become progressively more piscivorous as they grow. Eels >50.1 cm are almost entirely piscivorous. Seasonal differences in diet also exist within each size class examined.     

Significance of the delta 5 and delta 4 steroidogenic pathways in the hamster preovulatory follicle

Isolated hamster granulosa cells and theca from preovulatory follicles were incubated in vitro for 2 and 6 h in the absence/or presence of LH and steroid substrates. The purpose of the experiments was to determine, in theca, the relative activities of the delta 5 and delta 4 pathways under controlled conditions, and to compare the ability of granulosa cells and theca to form progesterone from exogenous pregnenolone. The results of the experiments show that the delta 5 pathway in theca predominates before and up to 2 h after LH stimulation. The delayed effect of LH after 2 h is a switch from delta 5 to delta 4 as the major metabolic pathway. Progesterone formation from exogenous pregnenolone is 7 to 10 times greater in unstimulated granulosa cells than in theca. Acute effects of LH lead to increased conversion of exogenous pregnenolone to progesterone in granulosa cells but not theca. LH does, however, acutely stimulate the thecal conversion of DHEA to androstenedione. The longer term effect of LH in both cell types is to increase pregnenolone conversion to progesterone.     

Structural and functional studies of the adrenal zona glomerulosa in sodium-depleted and sodium-loaded sheep

Cell and Tissue Research - The effects of alterations in sodium status upon the morphology of the adrenal zona glomerulosa in sheep have been examined qualitatively and quantitatively, using...     

FREE-FLOW ELECTROPHORETIC SEPARATION AND ELECTRICAL SURFACE PROPERTIES OF SUBCELLULAR PARTICLES FROM GUINEA PIG BRAIN

Continuous free-flow electrophoretic separation has been used to obtain relatively pure preparations of synaptosomes and synaptic vesicles from crude fractions of guinea pig brain homogenates. Measurements of the contents of protein, neuraminic acid, and bound acetylcholine; the activities of succinic dehydrogenase, adenosine triphosphatase, choline acetylase, and 5'-nucleotidase; and the uptake of ¹⁴C-labeled choline arid acetylcholine in the presence and absence of hemicholinium, all confirm the electron microscope evidence that the electrophoretic preparations are at least as pure as those obtained by ultracentrifugal methods. The electrophoretic mobility measurements have been used to calculate zeta potentials and surface charge densities for these particles.     

Enzymatic aromatization of steroids. I. Effects of oxygen and carbon monoxide on the intermediate steps of estrogen biosynthesis

At Case Western Reserve University in Cleveland, the known intermediate steps in the aromatization, catalyxed by human placental microsomes, of 4-androstene-3, 17-dione to estrone were evaluated. Oxygen and carbon monoxide atmospheres were used to expose the properties of the participating oxidases. The results were judged to be evidence for the existence of 3 mixed function oxidases active in steroid aromatization. One of the oxidases may be a form of cytochrome P-450. The proposed microsomal components must be physically fractionated for validation of their independent existences.     

Hydrolysis of bradykinin and its higher homologues by angiotensin-converting enzyme (Short Communication)

The hydrolysis of bradykinin and its higher homologues by angiotensin-converting enzyme has been investigated by using an automated ninhydrin technique. The results show an inverse relationship of hydrolysis rate with size and charge of the peptide, which parallels the inactivation in the pulmonary circulation and offers an explanation for the selectivity of metabolism of these kinins by the lungs.