Biomedical subjects

S Park

Publications and source records attributed to S Park.

At least 73 records · Page 4Linked to original sources

PubMed2004

Desmoplastic reaction in pancreatic cancer: role of pancreatic stellate cells.

OBJECTIVES: Pancreatic cancer has a very poor prognosis, largely due to its propensity for early local and distant spread. Histopathologically, most pancreatic cancers are characterized by a prominent stromal/fibrous reaction in and around tumor tissue. The aims of this study were to determine whether (1) the cells responsible for the formation of the stromal reaction in human pancreatic cancers are activated pancreatic stellate cells (PSCs) and (2) an interaction exists between pancreatic cancer cells and PSCs that may facilitate local and distant invasion of tumor. METHODS: Serial sections of human pancreatic cancer tissue were stained for desmin and glial fibrillary acidic protein (stellate cell selective markers) and alpha-smooth muscle actin (alphaSMA), a marker of activated PSC activation, by immunohistochemistry, and for collagen using Sirius Red. Correlation between the extent of positive staining for collagen and alphaSMA was assessed by morphometry. The cellular source of collagen in stromal areas was identified using dual staining methodology, ie, immunostaining for alphaSMA and in situ hybridization for procollagen alpha1I mRNA. The possible interaction between pancreatic cancer cells and PSCs was assessed in vitro by exposing cultured rat PSCs to control medium or conditioned medium from 2 pancreatic cancer cell lines (PANC-1 and MiaPaCa-2) for 24 hours. PSC activation was assessed by cell proliferation and alphaSMA expression. RESULTS: Stromal areas of human pancreatic cancer stained strongly positive for the stellate cell selective markers desmin and GFAP (indicating the presence of PSCs), for alphaSMA (suggesting that the PSCs were in their activated state) and for collagen. Morphometric analysis demonstrated a close correlation (r = 0.77; P < 0.04; 8 paired sections) between the extent of PSC activation and collagen deposition. Procollagen mRNA expression was localized to alphaSMA-positive cells in stromal areas indicating that activated PSCs were the predominant source of collagen in stromal areas. Exposure of PSCs to pancreatic cancer cell secretions in vitro resulted in PSC activation as indicated by significantly increased cell proliferation and alphaSMA expression. CONCLUSIONS: Activated PSCs are present in the stromal reaction in pancreatic cancers and are responsible for the production of stromal collagen. PSC function is influenced by pancreatic cancer cells. Interactions between tumor cells and stromal cells (PSCs) may play an important role in the pathobiology of pancreatic cancer.

Actins↗

PubMed2004

Characteristics of intramucosal gastric carcinoma with lymph node metastatic disease.

AIM: Recent trends in treatment strategy for early gastric cancer (EGC) are towards minimal surgical procedures, such as endoscopic mucosal resection and laparoscopic partial resection. There is a possibility of incomplete removal of regional lymph nodes in minimal procedures, which may subsequently decrease the chance of a cure. Therefore, it is essential to be able to predict lymph node status and to make careful selection of candidates for mucosal resection. METHODS AND RESULTS: We studied the relationship between lymph node status and various pathological parameters including macroscopic appearance, location, size, differentiation, presence of ulceration, vascularity, presence of gastritis cystica profunda-like glandular proliferation, disruption of the muscularis mucosae and invasion into the muscularis mucosae, using age- and sex-matched samples of 40 node-positive and 80 node-negative tumours to define the characteristics of intramucosal EGCs. Histological differentiation (P < 0.001), increased submucosal vascularity (P < 0.05), breakdown of the muscularis mucosae (P < 0.05), and invasion of tumour cells into the muscularis mucosae (P < 0.05) were correlated with the lymph node status of intramucosal gastric carcinoma. Furthermore, diffuse type histology (P < 0.001) and deep invasion into the muscularis mucosae (P < 0.05) were indicators of node-positive intramucosal EGCs. CONCLUSIONS: These histological indicators are easily accessible and seem to predict lymph node metastatic disease in limited surgical specimens. Patients should be carefully selected despite the recent trend toward less invasive resection of EGCs, especially for those apparently confined to the mucosa.

Adult↗

PubMed2004

Functional studies of frataxin.

Mitochondria generate adenosine triphosphate (ATP) but also dangerous reactive oxygen species (ROS). One-electron reduction of dioxygen in the early stages of the electron transport chain yields a superoxide radical that is detoxified by mitochondrial superoxide dismutase to give hydrogen peroxide. The hydroxyl radical is derived from decomposition of hydrogen peroxide via the Fenton reaction, catalyzed by Fe2+ ions. Mitochondria require a constant supply of Fe2+ for heme and iron-sulfur cluster biosyntheses and therefore are particularly susceptible to ROS attack. Two main antioxidant defenses are known in mitochondria: enzymes that catalytically remove ROS, e.g. superoxide dismutase and glutathione peroxidase, and low molecular weight agents that scavenge ROS, including coenzyme Q, glutathione, and vitamins E and C. An effective defensive system, however, should also involve means to control the availability of pro-oxidants such as Fe2+ ions. There is increasing evidence that this function may be carried out by the mitochondrial protein frataxin. Frataxin deficiency is the primary cause of Friedreich's ataxia (FRDA), an autosomal recessive degenerative disease. Frataxin is a highly conserved mitochondrial protein that plays a critical role in iron homeostasis. Respiratory deficits, abnormal cellular iron distribution and increased oxidative damage are associated with frataxin defects in yeast and mouse models of FRDA. The mechanism by which frataxin regulates iron metabolism is unknown. The yeast frataxin homologue (mYfh1p) is activated by Fe(II) in the presence of oxygen and assembles stepwise into a 48-subunit multimer (alpha48) that sequesters >2000 atoms of iron in a ferrihydrite mineral core. Assembly of mYfhlp is driven by two sequential iron oxidation reactions: a fast ferroxidase reaction catalyzed by mYfh1p induces the first assembly step (alpha --> alpha3), followed by a slower autoxidation reaction that promotes the assembly of higher order oligomers yielding alpha48. Depending on the ionic environment, stepwise assembly is associated with the sequestration of < or = 50-75 Fe(II)/subunit. This Fe(II) is initially loosely bound to mYfh1p and can be readily mobilized by chelators or made available to the mitochondrial enzyme ferrochelatase to synthesize heme. However, as iron oxidation and mineralization proceed, Fe(III) becomes progressively inaccessible and a stable iron-protein complex is produced. In conclusion, by coupling iron oxidation with stepwise assembly, frataxin can successively function as an iron chaperon or an iron store. Reduced iron availability and solubility and increased oxidative damage may therefore explain the pathogenesis of FRDA.

Friedreich Ataxia↗

PubMed2004

A link between irritable bowel syndrome and fibromyalgia may be related to findings on lactulose breath testing.

BACKGROUND: An association between irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) has been found. OBJECTIVE: To compare the prevalence and test results for bacterial overgrowth between IBS and fibromyalgia. METHODS: Subjects with independent fibromyalgia and IBS were compared with controls in a double blind study. Participants completed a questionnaire, and a lactulose hydrogen breath test was used to determine the presence of SIBO. The prevalence of an abnormal breath test was compared between study participants. Hydrogen production on the breath test was compared between subjects with IBS and fibromyalgia. The somatic pain visual analogue score of subjects with fibromyalgia was compared with their degree of hydrogen production. RESULTS: 3/15 (20%) controls had an abnormal breath test compared with 93/111 (84%) subjects with IBS (p<0.01) and 42/42 (100%) with fibromyalgia (p<0.0001 v controls, p<0.05 v IBS). Subjects with fibromyalgia had higher hydrogen profiles (p<0.01), peak hydrogen (p<0.0001), and area under the curve (p<0.01) than subjects with IBS. This was not dependent on the higher prevalence of an abnormal breath test. The degree of somatic pain in fibromyalgia correlated significantly with the hydrogen level seen on the breath test (r = 0.42, p<0.01). CONCLUSIONS: An abnormal lactulose breath test is more common in fibromyalgia than IBS. In contrast with IBS, the degree of abnormality on breath test is greater in subjects with fibromyalgia and correlates with somatic pain.

Breath Tests↗

PubMed2004

Homologous and heterologous in vitro regulation of pig pituitary somatostatin receptor subtypes, sst1, sst2 and sst5 mRNA.

Somatostatin (SRIF) is commonly regarded as an inhibitor of GH release in rodents and humans. However, in pigs, SRIF can stimulate the release of GH at low (picomolar) doses, while inhibiting GHRH-stimulated GH release at high (nanomolar) doses in primary pituitary cell cultures. One possible mechanism by which pig cells respond differently to the actions of SRIF is by differential expression and regulation of SRIF receptor subtypes. As no information is available on the homologous regulation of SRIF receptors in pigs, we examined the acute (4 h) in vitro effects of SRIF on mRNA levels of SRIF receptors sst1, sst2 and sst5 by multiplex RT-PCR. These particular sst subtypes were selected because all three have been implicated in the inhibitory effects of SRIF on GH release in both rodents and humans. At a high dose (10(-7) M), SRIF stimulated the expression of sst1, sst2 and sst5 in pig pituitary cell cultures. At a low dose (10(-13) M), SRIF markedly increased sst1, without affecting sst2 or sst5. Given that our laboratory has shown SRIF at high and low doses stimulates cAMP production in a subpopulation of pig somatotropes, we sought to determine if this signaling pathway may be responsible for the stimulatory effect of SRIF on its own receptor expression. The receptor-independent cAMP activator forskolin elevated sst1 and sst2 mRNA levels but did not affect sst5 expression, suggesting the stimulatory actions of high- and low-dose SRIF on sst1 and high-dose SRIF on sst2 mRNA levels can be mediated by activation of cAMP, whereas the stimulatory effect of high-dose SRIF on sst5 mRNA is elicited by a cAMP-independent pathway. Interestingly, both GHRH (10(-8) M) and ghrelin (10(-6) M), which release GH in pig pituitary cell cultures via cAMP-dependent mechanisms, decreased sst5 without altering sst1 or sst2 mRNA levels. Since the actions of GHRH and ghrelin on sst expression markedly contrasted with that observed for SRIF and forskolin these results clearly indicate GHRH and ghrelin are regulating sst5 mRNA levels by a cAMP-independent signaling pathway. Taken together, our results demonstrate that expression of pig SRIF receptors is under a complex, receptor subtype-selective regulation, wherein the concerted actions of key regulators of somatotrope function would play divergent and dose-dependent effects.

Animals↗

PubMed2003

Biochemical properties and substrate specificities of alkaline and histidine acid phytases.

Phytases are a special class of phosphatase that catalyze the sequential hydrolysis of phytate to less-phosphorylated myo-inositol derivatives and inorganic phosphate. Phytases are added to animal feedstuff to reduce phosphate pollution in the environment, since monogastric animals such as pigs, poultry, and fish are unable to metabolize phytate. Based on biochemical properties and amino acid sequence alignment, phytases can be categorized into two major classes, the histidine acid phytases and the alkaline phytases. The histidine acid phosphatase class shows broad substrate specificity and hydrolyzes metal-free phytate at the acidic pH range and produces myo-inositol monophosphate as the final product. In contrast, the alkaline phytase class exhibits strict substrate specificity for the calcium-phytate complex and produces myo-inositol trisphosphate as the final product. This review describes recent findings that present novel viewpoints concerning the molecular basis of phytase classification.

6-Phytase↗

PubMed2003

High-resolution x-ray study of the nematic-smectic-A and smectic-A-smectic-C transitions in liquid-crystal-aerosil gels.

The effects of dispersed aerosil nanoparticles on two of the phase transitions of the thermotropic liquid-crystal material 4-n-pentylphenylthiol-4(')-n-octyloxybenzoate (8;S5) have been studied using high-resolution x-ray diffraction techniques. The aerosils hydrogen bond together to form a gel which imposes a weak quenched disorder on the liquid crystal. The smectic-A fluctuations are well characterized by a two-component line shape representing thermal and random-field contributions. An elaboration on this line shape is required to describe the fluctuations in the smectic-C phase; specifically the effect of the tilt on the wave-vector dependence of the thermal fluctuations must be explicitly taken into account. Both the magnitude and the temperature dependence of the smectic-C tilt order parameter are observed to be unaffected by the disorder. This may be a consequence of the large bare smectic correlation length in the direction of modulation for this transition. These results show that the understanding developed for the nematic to smectic-A transition for octylcyanobiphenyl and octyloxycyanobiphenyl liquid crystals with quenched disorder can be extended to quite different materials and transitions.

Journal Article↗

PubMed2003

Adrenal cortical carcinoma initially presented with overwhelming disseminated intravascular coagulation.

We report a 54-year-old man who had adrenal cortical carcinoma initially manifested as features of overwhelming disseminated intravascular coagulation (DIC). In the initial diagnostic work-up, an adrenal mass was detected with venous thrombi in the abdominal imaging study, but the radiologic diagnosis was a hematoma arising from the adrenal gland and a biopsy was not possible due to a bleeding tendency. A lot of platelets and plasma products were transfused, but the bleeding tendency and other DIC features persisted. Finally, he expired because of newly developed massive pulmonary thromboembolism. To our knowledge, this is the first reported case of adrenal cortical carcinoma complicated with bleeding tendency caused by DIC as an initial manifestation. This suggests that adrenal cortical carcinoma should be considered in a patient with an adrenal mass and DIC features.

Adrenal Cortex Neoplasms↗

PubMed2003

Commensurate spin dynamics in the superconducting state of an electron-doped cuprate superconductor.

We report neutron scattering studies on two single crystal samples of the electron-doped (n-type) superconducting (SC) cuprate Nd2-xCexCuO4 (x=0.15) with T(c)=18 and 25 K. Unlike the hole-doped (p-type) SC cuprates, where incommensurate magnetic fluctuations commonly exist, the n-type cuprate shows commensurate magnetic fluctuations at the tetragonal (1/2 1/2 0) reciprocal points both in the SC and in the normal state. A spin gap opens up when the n-type cuprate becomes SC, as in the optimally doped p-type La2-xSrxCuO4. The gap energy, however, increases gradually up to about 4 meV as T decreases from T(c) to 2 K, which contrasts with the spin pseudogap behavior with a T-independent gap energy in the SC state of p-type cuprates.

Journal Article↗

PubMed2003

A dominant negative PPARgamma mutant shows altered cofactor recruitment and inhibits adipogenesis in 3T3-L1 cells.

AIMS/HYPOTHESIS: PPARgamma, a member of the nuclear hormone receptor family of transcription factors, plays a key role in adipocyte differentiation and insulin sensitivity. The aim of this study was to identify a potential dominant negative murine PPARgamma mutant and to characterize the in vitro functional properties of this mutant. METHODS: In vitro transient transfections and mammalian two-hybrid assays in TSA201 cells were used to characterize the transcriptional activity of the L466A mutant and to study the molecular interaction of transcriptional cofactors with the L466A mutant in an attempt to elucidate the mechanism of its dominant negative activity. Adenoviral constructs expressing PPARgamma wild-type (AdWT) or the L466A mutant (AdL466A) were infected into the murine 3T3-L1 cell line to study the mutant's effect on adipogenesis. RESULTS: The L466A mutant alone is transcriptionally defective. However, it retains DNA binding and inhibits the ligand-dependent and -independent activity of the wild-type receptor, consistent with dominant negative properties. In mammalian two-hybrid studies, the L466A mutant does not bind nuclear receptor coactivators. However, it more avidly recruits corepressors due to enhanced binding to the corepressor ID1 domain, leading to pronounced transcriptional repression. The AdL466A mutant inhibits adipogenesis induced by either a differentiation cocktail or by thiazolidinedione ligand. AdL466A infection also blocked the upregulation of the adipocyte marker genes aP2 and adipsin. CONCLUSION: We conclude that the L466A PPARgamma mutant possesses potent dominant negative activity based on preferential corepressor recruitment and it inhibits adipogenesis and the expression of adipocyte-specific genes.

3T3 Cells↗

PubMed2003

Smectic ordering in liquid-crystal-aerosil dispersions. I. X-ray scattering.

Comprehensive x-ray scattering studies have characterized the smectic ordering of octylcyanobiphenyl (8CB) confined in the hydrogen-bonded silica gels formed by aerosil dispersions. For all densities of aerosil and all measurement temperatures, the correlations remain short range, demonstrating that the disorder imposed by the gels destroys the nematic (N) to smectic-A (SmA) transition. The smectic correlation function contains two distinct contributions. The first has a form identical to that describing the critical thermal fluctuations in pure 8CB near the N-SmA transition, and this term displays a temperature dependence at high temperatures similar to that of the pure liquid crystal. The second term, which is negligible at high temperatures but dominates at low temperatures, has a shape given by the thermal term squared and describes the static fluctuations due to random fields induced by confinement in the gel. The correlation lengths appearing in the thermal and disorder terms are the same and show a strong variation with gel density at low temperatures. The temperature dependence of the amplitude of the static fluctuations further suggests that nematic susceptibility becomes suppressed with increasing quenched disorder. The results overall are well described by a mapping of the liquid-crystal-aerosil system onto a three-dimensional XY model in a random field with disorder strength varying linearly with the aerosil density.

Journal Article↗

PubMed2003

Acquired activated protein C resistance, high tissue factor expression, and hyper-homocysteinemia in systemic lupus erythematosus.

Activated protein C resistance (APCR), high tissue factor (TF) expression, and hyper-homocysteinemia are associated with thromboembolic diseases. Thromboembolism is a frequent complication of systemic lupus erythematosus (SLE). In this study, we evaluated the prevalence of APCR, high TF, and homocysteine with correlation of the thrombotic tendency in SLE. Ninety-four SLE patients and 28 normal controls were included. APC ratio and TF antigen were measured using commercial kits. Plasma homocysteine level was measured using HPLC. The prevalence of APCR, high TF antigen level, and hyper-homocysteinemia in our SLE patients were 21.3%, 66.0%, and 23.4%, respectively. The median plasma level of TF antigen in SLE patients was 145.23 pg/mL (range, 31.00-778.50 pg/mL), which was significantly higher than the control value of 39.83 pg/mL (range, 1.55-168.50 pg/mL). The median APC ratio in SLE patients was 2.76 (range, 1.48-13.47), which was significantly lower than the control value of 3.59 (range, 0.26-5.66). The plasma level of homocysteine was not significantly different from that of control. A significant association was observed between the presence of APCR (OR = 8.59, P < 0.0001) but not with the presence of high plasma TF antigen level (OR = 1.24, P = 0.67) and thrombotic complications in SLE patients. In conclusion, APCR and high plasma TF levels are common in SLE, but a significant association was observed only between the presence of APCR and thrombosis in SLE patients.

Activated Protein C Resistance↗

PubMed2003

Ideal-observer performance under signal and background uncertainty.

We use the performance of the Bayesian ideal observer as a figure of merit for hardware optimization because this observer makes optimal use of signal-detection information. Due to the high dimensionality of certain integrals that need to be evaluated, it is difficult to compute the ideal observer test statistic, the likelihood ratio, when background variability is taken into account. Methods have been developed in our laboratory for performing this computation for fixed signals in random backgrounds. In this work, we extend these computational methods to compute the likelihood ratio in the case where both the backgrounds and the signals are random with known statistical properties. We are able to write the likelihood ratio as an integral over possible backgrounds and signals, and we have developed Markov-chain Monte Carlo (MCMC) techniques to estimate these high-dimensional integrals. We can use these results to quantify the degradation of the ideal-observer performance when signal uncertainties are present in addition to the randomness of the backgrounds. For background uncertainty, we use lumpy backgrounds. We present the performance of the ideal observer under various signal-uncertainty paradigms with different parameters of simulated parallel-hole collimator imaging systems. We are interested in any change in the rankings between different imaging systems under signal and background uncertainty compared to the background-uncertainty case. We also compare psychophysical studies to the performance of the ideal observer.

Algorithms↗

PubMed2003

Identification of genes in thyrocytes regulated by unfolded protein response by using disulfide bond reducing agent of dithiothreitol.

Disulfide bonds are formed between the sulfhydryl groups in two cysteine residues of a protein. The formation of these bonds is necessary for the proper folding of a protein into its active three-dimensional form. In this study, the genes associated with disulfide bond formation of proteins from the rat thyroid cell line, FRTL-5 cell, were investigated using disulfide bond reducing agent of dithiothreitol (DTT), which prevented disulfide formation of newly synthesized proteins. The expression of six genes, they being the cAMP phosphodiesterase 7A1, neuronal cell death inducible putative kinase (NIPK), cytosolic LIM protein (Ajuba), Eker, early growth response 1 and the ferritin heavy chain, was specifically enhanced under both reductive conditions and various endoplasmic reticulum (ER) stresses inducing drugs such as Brefeldin A (BFA), calcium ionophore A23187 (A23187) and tunicamycin. These results suggest that a suitable redox environment is necessary for the correct disulfide bond conformation in thyrocytes in a complex system.

Animals↗

PubMed2003

Identification of an encystation-specific transcription factor, Myb protein in Giardia lamblia.

The life cycle of Giardia lamblia contains two differentiation processes, encystation and excystation. We performed an experiment to identify the genes induced during encystation using the differential display reverse transcriptase-polymerase chain reaction. Three of twelve isolated cDNA clones that showed increased transcription during encystation were identified to be of the myb2, which encodes a well-known transcriptional factor involved in cellular development and differentiation. The amino acid sequences of the Myb2 protein deduced from the isolated gene revealed that this Myb2 has a DNA binding domain comprising two imperfect repeats at its carboxyl-terminus. The nuclear localization of Myb2 protein during encystation was observed in vivo by expressing a Myb2-GFP fusion protein. In a random site selection experiment, the oligonucleotides bound by rMyb2 contained a conserved sequence of GTTT(G/T)(G/T). Two promoters of the encystation-induced genes, myb2, and cwp1, were also found to bind to rMyb2, whereas gap1, one of the constitutive genes did not.

Animals↗

PubMed2003

Regional biosynthesis of prostaglandins and hydroxyeicosatetraenoic acids from arachidonic acid in the rat stomach tissue.

The present study was conducted to determine regional differences in the biosynthesis of prostaglandins (PGs) and hydroxyeicosatetraenoic acids (HETEs) in the rat stomach tissue (fundus, corpus and pyloric antrum) from radioactive arachidonic acid (AA). The radioactive metabolites were validated by RP-HPLC using non-radioactive AA as substrate. PGE(2) was the major prostanoid in the tissue(.) The relative ratio of PGE(2):PGF(2)alpha:PGD(2) in the whole stomach was 1:0.5:0.1. Regionally, the fundus biosynthesized the largest amount of all three cyclo-oxygenase products. Among the lipoxygenase metabolites, 15S-HETE was the predominant product, while 12S-HETE was found to be the lowest. The relative ratio of 15S-HETE:5S-HETE:12S-HETE in the whole stomach was 1:0.6:0.4. Interestingly, the generation of lipoxygenase products was the highest in the pyloric antrum when compared to fundus or corpus. Thus, the regional differences in the biosyntheses of gastric PGs and monohydroxy fatty acids may be relevant to our understanding of corresponding differences in mucosal resistance or susceptibility to gastric disease.

Amino Acids↗

PubMed2003

Long-term study of the clinical significance of loss of heterozygosity in childhood acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is one of the most common malignancies in childhood, with a widely variable outcome. Differences in the behavior and prognosis of the leukemia suggest that ALL can be divided into several biologic subgroups. We analyzed the loss of heterozygosity (LOH) of 6q, 9p, 11q and 12p using 31 microsatellite sites to determine their overall frequency and clinical value. We have studied 244 primary ALL samples obtained from the Multicenter Trial ALL-BFM 90 of Childhood ALL group. These patients have now been followed clinically for over 8 years. LOH occurred in 169 (69%) individuals in the following frequencies: 6q, 49 patients (20%); 9p, 97 patients (40%); 11q, 29 patients (12%); 12p, 60 patients (25%). Clinical data showed that those with 6q LOH were younger (P = 0.01) and had lower WBC counts (P = 0.02); patients with 9p LOH more frequently had CNS involvement (P = 0.01) and T cell phenotype (P = 0.0001); individuals with 11q LOH had a good response to induction chemotherapy (P = 0.02); those with 12p LOH were younger (P = 0.005), frequently had precursor B ALL (P = 0.001), and had a longer event-free survival (P = 0.05). Taken together, these data confirm that LOH is a very frequent alteration in childhood ALL.

B-Lymphocytes↗

PubMed2003

Endoscopic hemoclipping using a transparent cap in technically difficult cases.

BACKGROUND AND STUDY AIMS: Technical difficulties have been experienced in endoscopic hemoclipping on the posterior wall of the body of the stomach because the angle of approach is tangential. It has been suggested that the use of a transparent cap on the tip of the endoscope could help to solve this problem. The purpose of this study was to examine the efficacy of endoscopic hemoclipping using a transparent cap over the tip of the endoscope. PATIENTS AND METHODS: A total of 74 patients with a bleeding peptic ulcer or stigmata of recent hemorrhage underwent endoscopic hemoclipping. Technical difficulty in hemoclipping was experienced in 18 patients and the transparent cap was used in these cases. We therefore conducted a nonrandomized prospective study to compare bleeding control with the hemoclip with and without the aid of a transparent cap. RESULTS: There were no statistically significant differences between the patients treated with the cap and those treated without the cap with regard to the initial hemostasis rate (94.4 % vs. 91.1 %), the rebleeding rate (11.7 % vs. 11.8 %), or the permanent hemostasis rate (94.4 % vs. 96.4 %). CONCLUSIONS: Although there was no statistically significant difference between patients treated with or without a transparent cap, hemoclipping with the aid of the cap made it possible to clip a lesion too tangential to be clipped without it. However, this study did not compare conventional hemoclipping with hemoclipping using a cap because the cap was only used in cases in which conventional clipping had failed.

Duodenal Ulcer↗