林带中阻力分布的理论与实验研究

推导了风向垂直于林带走向时林带内的阻力分布的解析式,比较了３种所面形状林带的阻力分布特点,并用风洞实验资料进行了验证,简析了在实际生产中的应用．     

Dephosphorylation of skeletal muscle phosphorylase,glycogen synthase,and phosphorylase kinase β-subunit by a Mn2+-activated protein phosphatase

An Mn²⁺-activated phosphoprotein phosphatase of M_r = 80,000 from rabbit muscle catalyzes the dephosphorylation of skeletal muscle proteins that are phosphorylated by either phosphorylase kinase or cAMP-dependent protein kinase. Phosphorylase or glycogen synthase labeled by phosphorylase kinase at seryl residues 14 or 7, respectively, are both dephosphorylated by the phosphatase. Phosphorylase a and glycogen synthase compete with one another for the phosphatase. The phosphatase discriminates between different sites labeled by the cAMP-dependent protein kinase: glycogen synthase phosphorylated either to 1.0 or 1.8 mol phosphate/mol, or phosphorylase kinase phosphorylated on its β-subunit serve as substrates for the phosphatase, but the phosphorylase kinase α-subunit, the phosphorylated phosphatase inhibitor 1, or casein do not. Histone fraction IIA, phosphorylated by the catalytic subunit, was a poor substrate even at a concentration of 100 μm. Phosphorylation of the α-subunit of phosphorylase kinase had no influence on the kinetics of dephosphorylation of the β-subunit. Thus, the M_r = 80,000 phosphatase meets the functional definition of a protein phosphatase 1 [Cohen, P. (1978) Curr. Top. Cell. Regul.14, 117–196]. Furthermore, from a comparison of the known phosphorylated sites of these proteins, it appears that the phosphatase discriminates between different sites present in the phosphoproteins tested on the basis of the K_m values for the reactions. It displays a preferential activity toward proteins with a primary structure wherein basic residues are two positions amino-terminal from the phosphoserine, AgrLysX-YSer(P) or LysArgX-YSer(P), rather and one residue away, ArgArgX-Ser(P).     

Les échos de la phase aquitano-burdigalienne dans la coupe de Dellaca Bianca (Val Scrivia,bassin Liguro-piémontais,Italie)

The geologic section of the Torrente Scrivia in 061 the vicinity of Rigoroso is generally reported as an conformable sequence in Oligocene and Miocene strata.In fact, it has suffered important reworkingsduring Lower Miocene and this event is not only evident in sedimentology but also in paleontology. Locally, these events reflect tectonic motions more strongly marked in the north-eastern part of the ligurian piemontese basin.Consequently, the result is that the geologicsection concerned could not be satisfactory referring to Lower Miocene.     

A fluorinated vitamin D3 analog with biopotency greater than 1 alpha, 25-dihydroxy vitamin D3

Vitamin D metabolites and analogs induce $\text{de novo}$ synthesis of a specific calcium-binding protein in embryonic chick duodenum maintained in organ culture. Using calcium-binding protein biosynthesis as a specific and sensitive biochemical indicator of intrinsic biopotency, 24,24-difluoro-1α,25-dihydroxy vitamin D₃ was found to be approximately four times more potent on a molar basis than the most active, naturally occurring metabolite, 1α,25-dihydroxy vitamin D₃.     

Differential effects of ouabain on human cell-mediated cytotoxicity. I. Inhibition of mitogen-induced cellular cytotoxicity and antibody-dependent cellular cytotoxicity against chicken red cell targets.

The effects of ouabain, a known inhibitor of lymphoproliferation, were studied in relation to the cytotoxic effector function of human peripheral blood mononuclear leukocytes (MNL) against chicken red blood cell (CRC) targets. MNL effectors lysed ⁵¹Cr-labeled CRC targets in the presence of PHA (mitogen-induced cellular cytotoxicity—MICC) or rabbit anti-CRC antibody (antibody-dependent cellular cytotoxicity—ADCC) in the absence of ouabain. The addition of ouabain to the cytotoxic reaction caused profound diminution of MICC with greater than 90% suppression of killing at ouabain concentrations of 5 × 10^?4M; ADCC was much more resistant to the effects of ouabain with only 60 to 70% inhibition of killing at similar ouabain concentrations (P < 0.01). Similar ouabain inhibition of MICC occurred whether the effector cell populations were unseparated MNL, depleted of monocytes, enriched for T cells, or depleted of T cells, suggesting a generalized activity by ouabain against all effector cells active in MICC. Ouabain inhibition of MICC could be overcome by increasing PHA concentrations, indicating that ouabain inhibition was not due to irreversible toxic effects on effector cells. Increasing the concentration of anti-CRC antibody resulted in increased killing in this ADCC system and, paradoxically, ADCC cultures with the highest antibody concentrations were more completely inhibited by ouabain. This enhanced inhibitory effect of ouabain on ADCC cultures with the highest antibody concentrations was not observed when the effector cell population was first depleted of phagocytic cells, suggesting a preferential inhibitory action by ouabain against monocyte effectors in ADCC. Thus, the differential inhibitory effects of ouabain on MICC and ADCC against CRC targets may be in part explained by the differing ouabain sensitivities of the various effector cell subpopulations involved in these cell-mediated cytotoxic events.     

Differential effects of ouabain on human cell-mediated cytotoxicity. II. Stimulation of monocyte-mediated, spontaneous cytotoxicity against chicken red cell targets.

We have previously shown that ouabain inhibits mitogen-induced cellular cytotoxicity (MICC) and antibody-dependent cellular cytotoxicity (ADCC) against chicken red cell (CRC) targets. We now report that ouabain increases spontaneous killing of CRC targets in the absence of mitogen or antibody. Spontaneous cytotoxicity by fresh mononuclear leukocytes (MNL) was enhanced by ouabain in a dose-dependent fashion and was maximal at a ouabain concentration of 5 × 10^?5M. Removal of phagocytic cells from the MNL effector cell population abrogated ouabain-induced spontaneous cytotoxicity, suggesting that the effector cell activated by ouabain was a monocyte. Ouabain-induced spontaneous cytotoxicity was relatively inefficient compared to MICC or ADCC and was only demonstrated consistently at effector:target cell ratios higher than those routinely employed for MICC and ADCC. Very low concentrations of ouabain (5 × 10^?9M) also enhanced spontaneous cytotoxicity of MNL precultured for 7 days, when added at either Day 0 or Day 6 of preculture. The cell effecting spontaneous cytotoxicity after 7 days of culture has been previously shown to be a monocyte. Thus, ouabain has opposing effects on cell-mediated cytotoxic functions: it inhibits MICC and ADCC against CRC targets, but stimulates spontaneous, monocyte-mediated cytotoxicity against the same targets.     

The effects of corticosteroids on immunoregulation in sarcoidosis.

The effects of in vivo hydrocortisone administration on the kinetics and functional capabilities of cells involved in the immune response in sarcoidosis were examined. Untreated sarcoidosis patients have a decrease in the absolute numbers of circulating T lymphocytes (P < 0.05). However, with regard to the proportions of T lymphocyte subpopulations, there is an increase in the relative proportions of IgG Fc receptor positive T cells (T_G) (P < 0.01), which have suppressor capabilities in certain in vitro systems of mitogen-induced antibody production, and a relative decrease in IgM Fc receptor positive T lymphocytes (T^M) which have helper effects in this system (P < 0.05). Additionally, sarcoidosis patients have circulating “suppressor” monocytes capable of suppressing anti-sheep red blood cell (SRBC) plaque-forming cell (PFC) responses by pokeweed mitogen (PWM)-stimulated lymphocytes. The in vitro removal of this cell abrogated this depressed response (P < 0.01). Intravenous administration of hydrocortisone produced a transient absolute T lymphocytopenia (P < 0.01) accompanied by a relative increase in T^G cells (P < 0.01) and a relative decrease in T_M cells (P < 0.02). Four hours after hydrocortisone therapy, at the point of maximal hydrocortisone-induced monocytopenia (P < 0.01), the suppressed ability of sarcoidosis lymphocytes to synthesize and secrete in vitro anti-SRBC antibody after polyclonal activation was corrected (P < 0.01), and PFC responses comparable to those seen in untreated normal subjects were obtained. These studies demonstrate that corticosteroid administration has profound effects on certain in vitro demonstrable immunoregulatory abnormalities in sarcoidosis.     

In vitro immune blastogenesis during contact sensitivity in tumor-bearing mice: I. Description of progressive impairment and demonstration of splenic suppressor cells

T-cell responsiveness was measured by the DNA response of disassociated spleen and lymph node cells when exposed to antigen in vitro. Sensitized splenic lymphocytes from fibrosarcoma-bearing mice immunized with 2,4-dinitro-1,5-difluorobenzene (DN2FB) demonstrated a progressive decrease in T-cell responsiveness to the haptenprotein conjugate DNP-BSA. Hyporesponsiveness to the dinitrophenylated-protein conjugate appeared in the spleens but not lymph nodes of tumorous animals. Normal host lymph node cells (LNC) responded strongly 24 to 48 h after sensitization and subsequently declined with a corresponding increase in responsiveness in the spleen. Tumor-bearing hosts (TBH) had similar LNC kinetics during immunization, however, spleen cells were significantly suppressed when compared to normal BALB/c mice sensitization kinetics. Spleen cells from TBH were also capable of suppressing the in vitro response of normal primed lymphocytes to DNP-BSA when admixed. Results from these experiments suggest that in vitro measurement of contact sensitivity was affected by suppressor cells/products existing in the spleens but not lymph nodes of fibrosarcoma-bearing mice.     

The role of subcellular organelles in hormone secretion : The interactions of calcium, vitamin A, vinblastine, and cytochalasin B in PTH secretion

To determine the role of subcellular organelles in hormone secretion, we studied the interaction of low calcium concentration (low Ca), retinol (vitamin A, vit A), vinblastine (VB), and cytochalasin B (CB) in parathyroid hormone (PTH) secretion. Bovine parathyroid tissue pieces were incubated in media containing the above agents. Vit A stimulated PTH release to a mean of 170% of control. This effect of vit A was diminished when tissues were simultaneously stimulated with low Ca and, furthermore, absent when tissues were pre-incubated in low Ca.VB had no effect on low Ca-stimulated secretion, but did inhibit vit A-induced secretion in the presence of low Ca.CB stimulated PTH secretion to a mean of 150% of control during the second and third hours of incubation. CB had at least an additive effect with low Ca in stimulating PTH secretion, with a more prompt and greater response than seen in normal calcium. VB did not inhibit the acute effect of CB on secretion in normal calcium media, but did inhibit CB-induced secretion during the third hour of incubation.None of the agents stimulated the release of lysosomal cathepsin D, and vit A and CB did not stimulate the release of LDH.Our results suggest that; (1) vit A and low Ca stimulate PTH secretion through a common pathway involving the cell membrane; (2) CB stimulates PTH secretion through a separate effect on the cell membrane or submembrane microfilaments, which normally retards secretion of PTH; and (3) microtubular proteins may facilitate basal secretion of PTH, but are not involved in low Ca-stimulated secretion of PTH.     

繁殖期雌性蓝狐性激素检测与 性器官组织学观察

为了研究繁殖期雌性蓝狐(Alopexlagopus)类固醇激素含量、发情表现与性器官组织学结构之间的关系,于2019年选取繁殖期不同发情状况的雌性蓝狐,共18只,分为典型发情、非典型发情和不发情3组。通过无损伤取样法采集粪便与尿液并通过放射免疫法(RIA)测定孕酮(P)和雌二醇(E2)的含量;每组选取1只在发情并输精的当天取卵巢和子宫,进行组织学观察。结果显示,所测定典型发情、非典型发情、不发情蓝狐类固醇激素水平,雌二醇在尿液中的含量显著高于粪便,且在不同组间差异明显,尤其在典型发情组更高,达到(11 065.17±546.76)ng/L;孕酮含量尿液与粪样差异不大,孕酮含量在典型发情雌性蓝狐粪便与尿液含量差异不显著,但在不发情雌性蓝狐中差异显著,为(16.61±0.63)μg/L。粪尿测定孕酮和雌二醇激素含量与三组不同情况的发情表现相比相关性显著。粪、尿作为类固醇激素检测样本,虽然含量有差异,但变化趋势一致,都可使用。卵巢与子宫在典型发情雌性蓝狐中体积较大,卵巢可见各级卵泡和多个黄体,子宫黏膜上皮为柱状上皮,排列紧密,固有层内可见大量腺体;非典型发情雌性蓝狐卵巢、子宫发育状况与典型发情雌性蓝狐相类似;不发情雌性蓝狐卵巢、子宫呈静息状态,卵巢中卵泡多处于闭锁状态,无卵母细胞,也无黄体,固有层间质细胞及肌层肌细胞排列更为紧密。说明检测孕酮和雌二醇激素的含量,可以准确判定蓝狐发情的状态。