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J Brierley

Publications and source records attributed to J Brierley.

25 records · Page 2Linked to original sources
PubMed1986

Immunoregulatory molecules of trophoblast and decidual suppressor cell origin at the maternofetal interface.

The mammalian fetus expresses a variety of paternal histocompatible, oncofetal, and trophoblast antigens against which the mother can mount an immune response. Survival of the "fetal graft" appears to depend upon local immunosuppressive mechanisms in lymph nodes draining the uterus and at the intrauterine implanation site itself. Nonspecific not-T-Fc-receptor-bearing small lymphocytes containing cytoplasmic granules present in successfully allopregnant mice can suppress both the generation of maternal-antipaternal killer T cells and the infiltration of cytotoxic T lymphocytes into sponge-matrix allografts during the effector phase of the immune response. These suppressor cells are deficient at the implantation sites of xenogeneic and allogeneic mouse embryos that are susceptible to maternal immunity and are destined to resorb. A soluble suppressor factor of approximately 100,000 daltons in size can be obtained from the suppressor cells and acts to block the response of T cells to interleukin-2 by interfering with IL-2 receptors. The development of the suppressor cells in the decidua requires certain hormonal signals as well as signals provided by trophoblast cells. Freshly explanted or cultured murine trophoblast cell lines elaborate soluble factor(s) that are active in recruitment or activation of suppressor cells. Since suppressor cells may be isolated from decidua of successfully allopregnant humans, the suppressor cell mechanism and its regulation may represent a key factor in the protection of the "fetal allograft" from rejection by maternal immunity.

Abortion, Spontaneous↗
PubMed1985

Direct electrical stimulation promotes growth and enhances survival of aneurogenic muscles of the chick embryo.

Analyses of embryonic aneurogenic muscles indicate that several processes associated with early myogenesis in vivo proceed in the absence of peripheral nerves. However, aneurogenic muscles demonstrate impaired growth and limited survival. To investigate whether neurally mediated activity is responsible for these phenomena, aneurogenic muscles of the chick embryo were directly stimulated in vivo via implanted electrodes. Volumetric analyses of stimulated aneurogenic brachial (latissimus dorsi) muscles from Stage (St) 33 (7.5 to 8 days) through St 37 (11 days) demonstrated that growth was enhanced significantly beyond the level characteristic of unstimulated aneurogenic muscles. Moreover, for the majority of embryos, the stimulation regimen actually rescued the posterior latissimus dorsi muscle which characteristically does not survive beyond St 32 (7.5 days) in the aneurogenic state. Thus, our results implicate activity per se as an important factor necessary for the proper growth and survival of brachial muscles during early embryogenesis. The stimulation regimen, however, did not alter myosin ATPase profiles.

Animals↗
PubMed1982

Differentiation of muscle fiber types in aneurogenic brachial muscles of the chick embryo.

Cross-reinnervation studies performed ex ovo with newly hatched chicks demonstrate that peripheral motor neurons control the phenotypic characteristics of avian muscles. The present experiments were designed to determine whether or not nerves play a similar role during the initial expression of muscle fiber types. Previous experiments indicated that differentiation of specific fiber types occurs during the first week of embryogenesis, temporally coincident with the penetration of nerves within muscle masses. These observations suggested that peripheral nerves may be associated with the initial differentiation of fiber types. To test this hypothesis directly, anterior limb buds of the chick embryo were rendered aneurogenic by deletion of the brachial segment of the neural tube. To ensure a completely aneurogenic environment for developing brachial muscles, surgery was performed at day 2 in ovo before the exit of ventral root fibers. Experimental and control embryos from Stage (St) 25 (4.5 d) through St 45 (19d) were analyzed histochemically by a silver-cholinesterase reaction to detect nerves and by the myosin ATPase reaction, following alkali and acid preincubation, to determine the fiber type composition of the muscles. In addition, the total volume of aneurogenic and control muscles was compared. Results demonstrate that the characteristic myosin ATPase profiles of individual aneurogenic and innervated (control) muscles were identical throughout the entire period analyzed. Therefore, we conclude that these enzymic profiles are endogenously expressed and are not under neuronal control during early embryogenesis. Furthermore, the entire sequence of events from the migration of myogenic cells to the anterior limb bud through the division of the primary muscle masses to form individual brachial muscles proceeded on schedule in the absence of nerves. Since the growth of aneurogenic muscles was impaired, we conclude that during embryogenesis peripheral motor nerves are necessary initially for the proper growth of muscles and ultimately, for their survival. They are not involved, however, with either the initial formation or initial differentiation of individual brachial muscles.

Adenosine Triphosphatases↗
PubMed1979

Phosphorylation of casein by human erythrocyte membrane-bound protein kinase: competition of casein with endogenous substrates.

The possibility that spectrin and band-3 protein are phosphorylated by the same membrane-bound protein kinase was investigated by adding casein to unsealed erythrocyte ghosts and examing competition of the three proteins for phosphorylation. The extent of spectrin and band-3 protein phosphorylation was reduced by up to approximately 55%. This indicated that casein was competing with these endogenous substrates for phosphorylation and was most probably phosphorylated by the same protein kinase(s). Furthermore, the extent of inhibition of the phosphorylation of the two endogenous substrates was indistinguishable over the range of casein concentrations tested (0.1 to 5 mg/ml). This indicates that spectrin and band-3 protein may be phosphorylated by the same protein kinase. In contrast, casein was found to have no effect on the cAMP-dependent phosphorylation of band 4.5. This result indicates that casein only competes with the endogenous proteins phosphorylated by the cAMP-independent protein kinase(s). The extent of reduction of endogenous substrate phosphorylation in the presence of casein was found to be constant over incubation periods of 1 to 15 min, indicating that this reduction was not due to consumption of ATP. Since the spectrin and band-3 protein phosphorylations were specifically and identically reduced by casein and these reductions were not due to the ATP consumption or to a general alteration of the membrane, we conclude that the two substrates are likely phosphorylated by one kinase which also phosphorylates casein.

Caseins↗