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PubMed1981

An assessment of Leydig cell function after bilateral or unilateral efferent duct ligation: further evidence for local control of Leydig cell function.

Leydig cell function was examined in adult male rats at 2 and 4 weeks after bilateral or unilateral efferent duct ligation. Bilateral efferent duct ligation resulted in significantly elevated serum LH levels, an increased size of Leydig cells and an enhanced testosterone response to gonadotropin stimulation in vitro despite a marked loss of LH-hCG receptors. After unilateral ligation of the vasa efferentia, the parameters of Leydig cell function in the ligated testes showed identical changes to those seen after bilateral ligation, whereas such changes were minor or absent in the unligated contralateral testes of the same animals. These results demonstrate that the modifications of Leydig cell function after efferent duct ligation are mainly due to local changes within the testes providing further evidence for an intratesticular control of Leydig cell function.

Animals↗
PubMed1995

Stimulation of tyrosine phosphorylation of distinct proteins in response to antibody-mediated ligation and clustering of alpha 3 and alpha 6 integrins.

The interaction of cells with components of the extracellular matrix through their integrin receptors results in the stimulation of tyrosine phosphorylation of several proteins, suggesting that these receptors play a key role in signal transduction. Here we report that antibody-mediated ligation and clustering of alpha 3 beta 1 and alpha 6 beta 1/alpha 6 beta 4 integrins resulted in the stimulation of tyrosine phosphorylation of proteins that are specific for each heterodimer. Thus, ligation and clustering of the alpha 3 beta 1 integrin on human prostate carcinoma cells (PC-3) and human umbilical vein endothelial cells (HUVEC) with anti-alpha 3 antibodies resulted in the stimulation of tyrosine phosphorylation of a 55 kDa protein. In contrast, ligation and clustering of the alpha 6 beta 1 integrin on these cells with anti-alpha 6 antibody resulted in the dramatic stimulation of tyrosine phosphorylation of a 90 kDa protein in addition to a 52 kDa protein, and ligation and clustering of alpha 5 beta 1 on HUVEC did not result in the apparent stimulation of tyrosine phosphorylation of any proteins. Clustering with anti-beta 1 antibodies triggered the tyrosine phosphorylation of all of these proteins, whereas ligation and clustering of PC-3 cells with an anti-beta 4 antibody resulted in the tyrosine phosphorylation of a distinct 62 kDa protein. Since the PC-3 cells express both alpha 6 beta 1 and alpha 6 beta 4, these data suggest that these two receptors can transduce distinct signals. All of the phosphorylations could be inhibited by treating the cells with Genistein, a tyrosine kinase inhibitor. Antibody-mediated ligation and clustering of integrins on the two types of cells did not result in the stimulation of tyrosine phosphorylation of pp125 focal adhesion kinase, although this was observed upon cell attachment and spreading on fibronectin, laminin and anti-alpha 3 monoclonal antibody. Collectively, these data demonstrate that cross-linking of different integrin heterodimers can stimulate tyrosine kinase activities, leading to the phosphorylation of distinct proteins, which are also different from those observed when cells are allowed to spread on a matrix.

Antibodies↗
PubMed1993

Effect of the leukotriene receptor antagonist ONO-1078 on extravascular lung water after coronary ligation in dogs.

To determine whether or not leukotrienes are associated with pulmonary edema after coronary ligation in dogs, we studied the effects of a specific leukotriene C4/D4 antagonist, ONO-1078, on extravascular lung water, as measured by the thermal-dye double indicator dilution method (Extravascular thermal volume, ETV). Six dogs served as a sham control (group 1). The proximal left anterior descending coronary artery was ligated for 45 min in 6 dogs (group 2), and in 6 others the coronary artery was ligated after pretreatment with ONO-1078 (1 mu/kg/min) (group 3). ETV and pulmonary arterial pressure were measured at control and 45 min after coronary ligation. In group 1, no significant change was found in ETV. Although there was no significant increase in pulmonary arterial pressure after coronary ligation, ETV significantly increased in groups 2 and 3. ETV increased more in groups 2 and 3 than in group 1, but there was no significant difference between groups 2 and 3. Thus, ONO-1078 did not effectively prevent the accumulation of extravascular lung water after coronary ligation, indicating that leukotrienes are not important mediators of pulmonary edema after myocardial ischemia.

Animals↗
PubMed2005

Optimizing splinted ligation of highly structured small RNAs.

The synthesis of highly structured small RNAs containing nonstandard nucleotides is of high interest for structural and functional investigations. A general approach is the joining, by T4 DNA ligase-mediated splinted ligation, of two or more RNA fragments, each of which may contain its own set of modified nucleotides. The RNA fragments hybridize with a complementary DNA splint to form a ternary ligation-competent-complex (LCC), which is then turned over by the DNA ligase. We studied the formation of the LCC and its precursors using size exclusion chromatography combined with a fluorescence detector. The spatial proximity of two cyanine-dye-labeled RNA fragments in LCCs was detected by monitoring FRET. An observed correlation of LCC formation and ligation yields suggests the use of long splints to stabilize LCCs. Splint oligos of increasing length, which in general appear to reduce the number of different hybridization intermediate species found in a reaction mixture, were applied to the synthesis by T4-DNA-ligation of two highly structured target molecules, one a 73 mer tRNA, the other a 49 mer synthetic ribozyme. A stable LCC could be isolated and turned over with>95% ligation efficiency. In conclusion, the use of long splints presents a generally applicable means to overcome the low propensity of highly structured RNAs for hybridization, and thus to significantly improve ligation efficiencies.

Base Sequence↗
PubMedDate not supplied

[The significance of tubal ligation for people living in low-end neighborhoods in Porto Alegre].

Health care access in the several social strata increases the demand for methods that ensure unflawed contraception. In this sense, the demand for tubal ligation by women older than 25 and with little schooling has increased. It is an exploratory and descriptive study with a qualitative approach aiming at: getting to know the significance of tubal ligation among sterilized women in the Vila Pinto, Porto Alegre; understanding the reasons for choosing this method and; finding out whether this surgical procedure entails any changes in sexual relationship. The participants in the study are 12 women who undertook tubal ligation within the period from July 2002 to June 2003. Data collection occurred by means of a semi-structured interview. The contents of the reports were analysed, wherefrom three topics emerged: decision to have tubal ligation; occurrence of tubal ligation and; experiences after tubal ligation.

Adult↗
PubMed1983

Mechanism of gastric acid response to pylorus ligation: effects of nephrectomy.

In the rat nephrectomy raises the serum gastrin concentration but makes the parietal cells refractory to gastrin. Pylorus ligation stimulates the gastric acid output by a long vago-vagal reflex in innervated animals and by an intramural reflex in chronically vagotomized animals. Nephrectomy reduced the acid response to pylorus ligation in vagally intact rats but enhanced it in vagotomized rats. The acid response to pylorus ligation in all the experimental groups was inhibited by a muscarinic blocker, atropine, and by an H2-antagonist, metiamide. The serum gastrin concentration was raised by nephrectomy and by vagal denervation. Histamine mobilization from gastric endocrine cells is reflected in the activity of gastric histidine decarboxylase. The enzyme activity in pylorus-ligated innervated rats was raised by pentagastrin, atropine, and metiamide. In nephrectomized rats the basal enzyme activity was high, and it was raised further, slightly but significantly, by pentagastrin. The basal enzyme activity in pylorus-ligated rats was also quite high after vagotomy, and it was raised further by pentagastrin. After vagotomy + nephrectomy the basal enzyme activity was very high; it was not raised further by pentagastrin. It appears that both vago-vagal and intramural reflexes involve a cholinergic and a histaminergic pathway, that gastrin is not important for the neurally mediated acid response elicited by pylorus ligation, and that the postulated histaminergic pathway does not involve histamine derived from the gastric endocrine-like cells.

Animals↗
PubMed1999

Ligation of CD40 induced tumor necrosis factor-alpha in rheumatoid arthritis: a novel mechanism of activation of synoviocytes.

OBJECTIVE: To determine the immunopathological significance of CD40/CD40 ligand (CD40L) interaction in rheumatoid arthritis (RA). METHODS: The expression of CD40 ligand (CD40L) in synovial tissues (ST) from patients with RA was examined by immunohistochemistry. Tumor necrosis factor-alpha (TNF-alpha) was measured by ELISA. Expression of CD40 on ST cells was quantified by anti-CD40 monoclonal antibodies and 125I labelled anti-mouse IgG. RESULTS: Immunohistochemistry showed CD40L+ T cells in RA ST. Ligation of CD40 on RA ST cells significantly increased the production of TNF-alpha in a dose dependent fashion. Adherent, but not non-adherent, fraction of ST cells responded to ligation of CD40 to produce TNF-alpha. Interferon-gamma (IFN-gamma), interleukin 4 (IL-4), or IL-13 acted synergistically with CD40 ligation to enhance TNF-alpha production by ST cells. IL-10 exerted inhibitory effects on both CD40 ligation induced and CD40 ligation plus IFN-gamma induced TNF-alpha production by ST cells. CONCLUSION: These data indicate activated T cells participate in synovial inflammation of RA via CD40L to stimulate the production of TNF-alpha by ST cells. The effect of CD40 ligation is modulated by the presence of several cytokines, e.g., IFN-gamma, IL-4, IL-10, and IL-13.

Arthritis, Rheumatoid↗
PubMed1999

Autocrine IL-12 is involved in dendritic cell modulation via CD40 ligation.

Ligation of CD40 on dendritic cells (DC) triggers production of IL-12. Using an adoptive transfer model we have previously shown that rIL-12 acts directly on DC to enhance presentation of an otherwise poorly immunogenic tumor peptide. Using the same experimental model, we now describe a similar adjuvanticity of CD40 ligation on peptide presentation by DC. We also explore the possibility that the IL-12 resulting from CD40 ligation directly affects the APC function of DC, mediating or contributing to the adjuvant effect of CD40 ligation. CD40 engagement in vitro and rIL-12 at concentrations in the range induced by CD40 ligation were equally effective in priming DC for presentation of the tumor peptide in vivo. Remarkably, the copresence in vitro of neutralizing Ab to IL-12, but not to TNF-alpha, IL-1beta, or IFN-gamma, ablated the enhancing effect of CD40 engagement on the APC function of DC. These data suggest a major role for autocrine IL-12 in DC modulation via CD40 ligation.

Adjuvants, Immunologic↗
PubMed1975

[The present practice of tubal ligation in West German university departments of obstetrics and gynaecology (author's transl)].

Within a few years the attitudes of the general public and the majority of the physicians to tubal ligation have undergone radical change. The present indications, incidence and policies of tubal ligation in 21 west german University Departments were explored by questionnaire. A survey on the incidence of tubal ligation in large departments of Obstetrics and Gynaecology was obtained prior to the enactment of new laws and regulations. The reported figures show a steep rise in the incidence of tubal ligation from 1970 to 1974. This fact is partially due to a very liberal interpretation of medical indications and partly due to the acceptance of tubal ligation as permanent contraception under certain individual and family conditions. The results of the enquiry are interpreted as the present practice of regulations which are legally still in the planning stage. In spite of the liberalization of the indications for tubal ligation, problems such as individual psychological difficulties associated with female sterilization cannot be minimized. Therefore the majority of the departments demand an intensive explanatory session and detailed informed consent for female sterilization.

Adult↗
PubMed1992

Ligation of the external carotid artery for severe epistaxis.

Epistaxis which is not controlled by anterior and posterior nasal packing is usually treated by ligation or embolization of the arterial supply to the nose. Transantral ligation of the maxillary artery, or embolization of its branches, have recently been considered the treatments of choice. Ligation of the external carotid artery has the advantage of being a short procedure which can be readily performed under local anesthesia, and does not require particular surgical expertise or the use of specialized equipment. This procedure, in combination with ligation of the ipsilateral anterior ethmoidal artery, controlled the bleeding in 14 of 15 patients over a nine-year period. There were no deaths and no significant complications. Although ligation and embolization of the maxillary artery are of proven efficacy, ligation of the external carotid artery is similarly effective and its simplicity may still make it the procedure of choice in some situations.

Adult↗
PubMed2004

Effect of tubal ligation on pelvic endometriosis externa in multiparous women with chronic pelvic pain.

OBJECTIVE: To determine whether tubal ligation is associated with decreased prevalence and less severity of pelvic endometriosis in multiparous patients with chronic pelvic pain. MATERIAL AND METHOD: From January 1995 to April 2002, 322 chronic pelvic pain patients underwent laparoscopy. Of these, 125 patients were multiparous (parity > or = 2). Their obstetric history, present contraceptive methods and laparoscopic findings were recorded perioperatively. The medical record of each patient was reviewed and analyzed. RESULTS: Among multiparous women with chronic pelvic pain, the prevalence of endometriosis in patients with and without tubal ligation was 45.1% (23 of 51 patients) and 59.5% (44 of 74 patients), respectively. Moderate-severe endometriosis was found in 8.7% (2 of 23 patients) and 36.4% (16 of 44 patients) among patients with and without sterilization. Tubal ligation was statistically significantly associated with severity of disease [P = 0.036, Crude OR (95% CI) = 0.17 (0.02-0.85), Adjusted OR (95% CI) = 0.21 (0.04-1.08)]. There was no statistically significant relationship between tubal ligation and prevalence of endometriosis. The small sample size of the study might account for this statistical result. CONCLUSION: Nearly half of multiparous women with chronic pelvic pain and tubal ligation had endometriosis. Tubal ligation was related to less severity of disease, with statistically significant difference.

Adult↗
PubMed1983

Selective ligation of DNA molecules following microinjection.

Avian retroviral DNA is rapidly ligated and transcribed following microinjection into chick cells. To analyze the fidelity of intranuclear ligations, DNA molecules with a variety of protruding ends or flush ends were co-injected into env-deficient Rous sarcoma virus-infected (RSV(-] cells. Two fragments were chosen which could complement the RSV(-) env deficiency upon ligation. This sensitive biological assay indicated that intracellular ligation between molecules with complementary protruding ends or flush ends was relatively efficient. Ligation was not observed with non-complementary termini. Furthermore, when multiple DNA molecules possessing a variety of protruding termini were introduced into the cells, complementary termini were selectively joined. Finally, when viral DNAs which expressed separate genetic markers were co-injected, almost 50% of the virus subsequently released were recombinants, indicating that ligations generally involved multiple molecules.

Avian Sarcoma Viruses↗
PubMedDate not supplied

Clinical outcome and cost comparison of percutaneous embolization and surgical ligation of varicocele.

We reviewed the records of 81 consecutive subfertile men with oligospermia and/or asthenospermia, treated for varicocele with either percutaneous embolization or surgical ligation between 1987 and 1991, and compared the outcomes and costs of the two procedures. All men had presented with infertility of at least 6 months duration, and in most cases female factors had been previously evaluated and treated. Patients were offered a choice of embolization or ligation of the internal spermatic vein. Forty-five men (56%) underwent ligation, and 36 men (44%) opted for embolization. The mean age, serum follicle-stimulating hormone, pretreatment sperm density, motility, and concentration of motile sperm were similar for the two groups. Seminal quality improved in 65% of all patients after varicocele ablation (46 of 71). Improvements were seen in postoperative sperm density (P < 0.01), motility (P < 0.002), and concentration of motile sperm (P < 0.001). Thirty-nine percent of the assessable patients established pregnancies during the study interval (26 of 66). The two treatment groups did not differ significantly with regard to the likelihood of postoperative improvement in sperm density (P = 0.64), motility (P = 0.33), concentration of motile sperm (P = 0.11), or pregnancy rate (P = 0.83). Percutaneous embolization and surgical ligation of varicocele are equally effective in improving male infertility and cost about the same. Embolization offers the potential advantage of shorter recovery to full activity as compared to surgical ligation. Where experienced interventional radiologists are available, percutaneous embolization should be offered as an alternative to open ligation.

Adult↗
PubMed1994

Phosphatidylinositol synthesis is a proximal event in intracellular signaling coupled to T cell receptor ligation. Differential induction by conventional antigen and retroviral superantigen.

There is increasing evidence that at least two functionally distinct signal transduction pathways may be coupled to the TCR complex. A conventional signal transduction pathway coupled to TCR ligation by peptide/MHC complexes includes increased [Ca2+]i, phosphatidylinositol (PI) hydrolysis, and cytokine expression. TCR ligation by MIs-1a/MTV superantigens may be coupled to an alternative signal transduction pathway without increased [Ca2+]i or detectable PI hydrolysis. We asked whether early events in the PI hydrolytic pathway might account for differential levels of PI breakdown after TCR ligation by conventional Ag and superantigen. We show that TCR ligation by conventional peptide Ag is coupled to a burst of PI synthesis in nontransformed T cells, which may represent a rate-limiting step for downstream PI hydrolysis. Incorporation of radiolabeled glucose by newly synthesized PI as well as inositol-1,4,5-trisphosphate provided direct evidence that this intracellular pool of PI represents an important substrate for this signaling pathway. By contrast, TCR ligation of the same T cell clone by retroviral superantigen leads to similar levels of T cell proliferation without detectable PI synthesis. Increased levels of radiolabeled intracellular PI reflected de novo synthesis of PI from glucose-6-phosphate rather than recycling of inositol phosphates because labeled phosphate and glucose were incorporated into PI but extracellular [3H]inositol was not. These findings suggest that differential PI synthesis represents an early biochemical event that distinguishes two functionally distinct signaling pathways coupled to TCR ligation by peptide Ag and retroviral superantigen.

Animals↗
PubMed1993

A simple two-step method for efficient blunt-end ligation of DNA fragments.

The formation of recombinant plasmids results from ligation between one end of the linearized vector and one end of the insert (favored by high DNA concentration), followed by self-ligation of the newly created hybrid molecule (favored by low DNA concentration). Standard protocols recommend an average DNA concentration at which both events may occur. Since this DNA concentration is not optimum for both ligation events, efficient blunt-end ligation is compromised. We describe a method for blunt-end ligation starting at a high DNA concentration for 1 h then at 1/20 the initial DNA concentration overnight. The number of recombinant plasmids obtained with this method is about 10-fold higher than with standard protocols. Restriction digestion and agarose gel electrophoresis of 10 recombinant plasmids obtained with the two-step ligation method showed that all plasmids contained one copy of the insert.

Biotechnology↗
PubMed1998

[Association of prevalence of tubal ligation and sociodemographic characteristics of women and their partners in the State of São Paulo]

Brazil has a high prevalence of tubal ligation. The hypothesis that it indicates undercover birth control efforts specifically addressed to the poorest sector of Brazilian society has been raised. The purpose of this paper is to evaluate whether there are differences in rates of tubal ligation depending on socioeconomic status. Data were gathered from interviews with 1335 women 15-49 years of age, of low or lower-middle socioeconomic status, carried out in 1991 in two regions of the State of São Paulo. The results showed an apparently higher prevalence of tubal ligation among women with less schooling,, but also among those living in better housing. However, after controlling for women's age, these associations disappeared, suggesting that they were explained by lower educational levels and greater economic resources of women of older age, where the latter factor is more heavily associated with a higher prevalence of tubal ligation. The complexity of the associations between socioeconomic status and tubal ligation are discussed, including the correlations between socioeconomic status and C-sections, which are in turn closely related to tubal ligation.

Journal Article↗
PubMed1999

Quantitative analysis of the effect of CD16 ligation on human NK cell proliferation.

CD16 (Fc gammaRIIIA), the low affinity receptor for IgG, is expressed on the majority of human peripheral blood NK cells. Ligation of CD16 with mAb or immune complexes activates NK cell cytotoxicity and cytokine secretion, and stimulates death of activated NK cells by apoptosis. This study uses NK cells labeled with the stable intracytoplasmic fluorescent dye 5- and 6-carboxyfluorescein diacetate succinimidyl ester to provide quantitative data on the effect of CD16 ligation on NK cell division and NK cell survival. When NK cells are cultured with rIL-2 and CD16 is ligated, NK cell division is stimulated, but there also is a substantial loss of NK progenitor cells. When NK cell proliferation is stimulated by coculture with gamma-irradiated MM-170 malignant melanoma cells and rIL-2, CD16 ligation enhances entry of NK cells into division. In some cases, CD16 ligation is essential for NK cell proliferation stimulated by MM-170 cells. In these cultures, there is no loss of NK progenitor cells. This study demonstrates that CD16 is an activation receptor for NK cell proliferation, and suggests that cellular costimulation alters the balance between NK cell death and NK cell proliferation stimulated by CD16 ligation.

Antibodies, Monoclonal↗
PubMed1996

Early thoracic duct ligation for postoperative chylothorax.

Four cases of postoperative chylothorax occurring at this institution over the past 5 years, as well as an extensive review of the world literature, are presented. Of the four cases, three occurred after resection of carcinoma of the lung and one after resection of recurrent chondrosarcoma of the chest wall. These patients were treated nonoperatively for varying periods of time ranging from 2 days to nearly 3 weeks. Subsequently, all patients underwent ligation of the thoracic duct. Early reoperation for ligation of the thoracic duct resulted in no morbidity or mortality. In one case of delayed thoracic duct ligation, after an attempt at ligation of minor lymphatic vessels, the single mortality occurred. In view of the experience with these patients and that reported in the literature, we propose that not only is thoracic duct ligation superior to nonoperative management, but that it should be undertaken without delay.

Adult↗