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851.
Gastroplasty operations for obesity occasionally require surgical reversal. A laparoscopic technique is described for the successful functional reversal of a case who had a Long vertical gastroplasty. 相似文献
852.
To determine which mucosal immunization routes may be optimal for induction of antibodies in the rectum and female genital tract, groups of women were immunized a total of three times either orally, rectally, or vaginally with a cholera vaccine containing killed Vibrio cholerae cells and the recombinant cholera toxin B (CTB) subunit. Systemic and mucosal antibody responses were assessed at 2-week intervals by quantitation of CTB-specific antibodies in serum and in secretions collected directly from mucosal surfaces of the oral cavity, rectum, cervix, and vagina with absorbent wicks. The three immunization routes increased levels of specific immunoglobulin G (IgG) in serum and specific IgA in saliva to similar extents. Rectal immunization was superior to other routes for inducing high levels of specific IgA and IgG in rectal secretions but was least effective for generating antibodies in female genital tract secretions. Only vaginal immunization significantly increased both specific IgA and specific IgG in both the cervix and the vagina. In addition, local production of CTB-specific IgG in the genital tract could be demonstrated only in vaginally immunized women. Vaginal immunization did not generate antibodies in the rectum, however. Thus, generation of optimal immune responses to sexually transmitted organisms in both the rectal and the genital mucosae of women may require local immunization at both of these sites. 相似文献
853.
A critical stage in pollen development is the dissolution of the four products of meiosis, the tetrads, into free microspores. The tetrads are surrounded by a thick callose wall composed of beta-1,3-glucan. At the completion of meiosis, the tetrads are released into the anther locule after hydrolysis of the callose by a beta-1,3-glucanase. Using the polymerase chain reaction, we have amplified and subsequently cloned a cDNA corresponding to a beta-1,3-glucanase, tobacco (Nicotiana tabacum cv. Samsun) anther glucanase (Tag 1), which is expressed exclusively in anthers from meiosis to the free microspore stage of pollen development. The identity of the clone was determined by DNA and deduced protein sequence similarity to other known beta-1,3-glucanases. Several regions strictly conserved among four classes of glucanases are also conserved in the Tag 1 protein. Tag 1 represents a novel class of beta-1,3-glucanase based on phylogenetic analysis and RNA expression pattern. Tag 1 RNA was detected in situ only in the tapetum, with maximal expression just prior to tetrad dissolution. Due to its expression pattern and sequence similarity to other beta-1,3-glucanases, we believe Tag 1 may be involved in tetrad dissolution. 相似文献
854.
RJ Hendrickson PA Cahill IH McKillop JV Sitzmann EM Redmond 《Canadian Metallurgical Quarterly》1998,362(2-3):251-259
The intrathecal (i.t.) injection of endothelins to conscious rats was found to cause respiratory arrest. To gain some insights into this central phenomenon, peripheral vascular permeability and lung oedema were measured after i.t. and i.v. injections of these peptides. When injected at T-8 spinal cord level, endothelin-1 (65 and 650 pmol) and endothelin-3 (650 pmol) enhanced vascular permeability in the lungs by 22-fold and 7-fold, respectively, and caused sudden death at the highest dose. Less prominent increases (between 1.4- and 2.2-fold) of vascular permeability were observed in other tissues (trachea, kidney, ears, skin of hind paws and back skin) with endothelin-1. Endothelin-1 (650 pmol) caused a similar increase (27-fold) in lung vascular permeability when injected at T-2, although the response was significantly less (P < 0.05) if injected at the L-4 (15-fold) spinal cord level. Only endothelin-1 produced lung oedema when injected at the T-2 or T-8 level. In contrast, intravenous injection of endothelins-1 and -3 (650 pmol) did not produce lung oedema and the lung vascular permeability was increased by only 1.4-1.6-fold and all rats survived. The prior i.t. injection of 6.5 nmol BQ-123 (cyclo[D-Trp, D-Asp, L-Pro, D-Val, L-Leu]), a selective endothelin ET(A) receptor antagonist, prevented the increases of lung vascular permeability and oedema and the mortality induced by i.t. endothelin-1 (650 pmol). Whereas i.v. treatment with phentolamine (2 mg/kg) or pentolinium (25 mg/kg + 50 mg/kg per h x 15 min) abolished the lung vascular permeability changes evoked by endothelin-1 (650) pmol), atropine (1 mg/kg), NG-nitro-L-arginine (50 mg/kg) or indomethacin (5 mg/kg) had no effect. Moreover, the effects of endothelin-1 were attenuated in capsaicin pretreated rats (125 mg/kg, 10 days earlier) and almost abolished in rats subjected to sympathectomy with 6-hydroxydopamine (100 mg/kg, 24-48 h earlier). All these treatments except atropine and NG-nitro-L-arginine prevented the endothelin-1-induced lung oedema and reduced the lethality by around 50%. These results suggest that the increases of pulmonary vascular permeability and oedema induced by i.t. endothelin-1 are due to an intense pulmonary vasoconstriction mediated by alpha-adrenoceptors following the release of catecholamines in response to the activation of endothelin ET(A) receptor in the spinal cord. This central phenomenon seems to be reflexogenic, including the involvement of primary afferent C-fibers and spinal cord ascending fibers to the brain. Thus, endothelin-1 could play a role in neurogenic pulmonary oedema through a central mechanism. 相似文献
855.
Dehydration of alcohols to ethers over Nafion-H, a solid perfluoroalkanesulfonic acid resin catalyst
Nafion-H has been found to be a highly efficient solid acid catalyst for the bimolecular conversion of alcohols to ethers
in excellent yields.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
856.
The effects of pneumoperitoneum on peak venous flow velocity in the common femoral vein and the vena cava have already been studied. The results suggested that venous stasis occurs during surgical pneumoperitoneum. This study determines the effects of pneumoperitoneum on the overall venous outflow resistance of the lower limbs. Venous outflow resistance was measured during surgical procedures by impedance plethysmography in 12 patients undergoing laparoscopic cholecystectomy, 4 patients undergoing laparoscopic herniorrhaphy, 4 patients undergoing conventional cholecystectomy, and 2 patients undergoing conventional herniorrhaphy. Venous outflow resistance did not change significantly during laparoscopic cholecystectomy or herniorrhaphy. No difference in venous outflow resistance between laparoscopic cholecystectomy and herniorrhaphy was found. During pneumoperitoneum, no obstruction to total lower limb venous outflow could be demonstrated, indicating that venous stasis in the limbs did not occur, and consequently, flow in the iliac and inferior caval veins was not compromised. Hypothetically, active vasodilatation resulting from mild compression may explain this. In our view, no special measures to prevent deep venous thrombosis have to be taken during laparoscopic procedures. 相似文献
857.
Spermatogenesis is a complex system leading to the formation of male gametes. Development of the spermatogenic cell lineage occurs throughout most of the pre- and post-natal lifetime of male mammals, and involves progression through a well-characterized series of stages and cell types. This progression is based on programmed gene expression. The mechanisms by which this tissue-, cell-type, and developmental-stage specific gene expression is regulated form the focus of an active area of investigation. In this review, I will summarize our efforts to elucidate these mechanisms through molecular analyses of the uniquely accessible mouse spermatogenic cell lineage. 相似文献
858.
859.
860.