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Biomedical subjects

J Hong

Publications and source records attributed to J Hong.

At least 109 records · Page 6Linked to original sources
PubMed1999

Multiple intestinal ulcerations and perforations secondary to methicillin-resistant Staphylococcus aureus enteritis in infants.

PURPOSE: The aim of this study was to define a distinctive clinical entity of multiple intestinal ulcerations and perforations in infants. METHODS: Two infants underwent abdominal exploration for surgical abdomen and were noted to have multiple intestinal ulcerations and perforations. A peculiar and unique surgical finding, numerous transverse linear ulcerations scattered along the entire small intestine, prompted us to search for similar instances. Five similar cases were additionally identified by members of the Korean Association of Pediatric Surgeons. The clinical courses, the surgical findings, and the results of bacterial cultures were reviewed. As well, the tissues of resected intestines were examined histopathologically. RESULTS: The characteristics of this entity are as follows. (1) It usually occurs in infants who have been treated with broad-spectrum antibiotics. (2) Despite broad-spectrum antibiotic treatment, diarrhea and abdominal distension developed progressively and deteriorated. (3) Histological evaluation showed mucosal ulcers with neutrophil infiltration, submucosal microabscesses, and colonies of Gram-positive cocci. (4) Methicillin-resistant Staphylococcus aureus (MRSA) was the predominant organism cultured from the body fluid. (5) Only two cases, the completely resected one and the one immediately treated postoperatively with vancomycin, survived. CONCLUSIONS: This entity is caused by multiple intestinal ulcerations and perforations secondary to MRSA enteritis in infants. It has a high mortality rate because of its difficult diagnosis. However, early recognition of this entity can lead to successful treatment.

Anti-Bacterial Agents↗
PubMed1999

A new in vitro model to study interaction between whole blood and biomaterials. Studies of platelet and coagulation activation and the effect of aspirin.

We have developed a versatile in vitro chamber model with a double purpose: first, to be able to study mechanisms of bio-incompatibility, and, second, to test biomaterials at all levels of interactions, in whole blood. The use of biomaterials in the form of microscope slides as walls in the chamber makes it possible to analyse both the biomaterial surface with regard to protein and cell binding, as well as the molecular events taking place in the fluid. Incubation of blood in the chamber, for 60 min at 37 degrees C resulted in the rapid binding of complement and coagulation proteins and of leukocytes and platelets to polyvinylchloride (PVC) slides. The cells formed a layer which more or less covered the underlying surface. Unlike complement activation, as reflected by soluble C3a and C5b-9, the thrombin-antithrombin formation was completely nullified in cell-depleted plasma. Despite the fact that thrombin-antithrombin generation was also negligible in platelet-rich plasma, inhibition of platelet aggregation on the material surface with aspirin resulted in suppressed generation of thrombin antithrombin complexes. Taken together, the coagulation activation in the chamber was dependent on the presence of blood cells which suggests that bound/aggregated platelets initiate a sequence of events involving leukocytes that results in coagulation activation.

Anticoagulants↗
PubMed1999

Cytotoxic polyacetylenes from the marine sponge Petrosia sp.

Three C46 (1-3) and three C30 (4-6) polyacetylenic alcohols with cytotoxic activity against a small panel of human solid-tumor cell lines have been isolated from the marine sponge Petrosia sp. Although compound 1 was identified as the stereoisomer of petrocortyne A, the structures of compounds 2-5 have not been previously reported and were established by spectral methods. Compound 6 was identified as the known compound petrosiacetylene D. The stereochemistry of compounds 1-5 was determined by the modified Mosher's method.

Acetylene↗
PubMed1999

New cytotoxic polyacetylenes from the marine sponge Petrosia.

New polyacetylenic alcohols with a C(45) carbon skeleton (2) and with an enone moiety in the alkyl chain (C(46), 1) were isolated from the marine sponge Petrosia sp. The gross structures of 1 and 2 were established by spectral methods, and the absolute stereochemistry was determined by the modified Mosher's method. Compounds 1 and 2 displayed considerable cytotoxicity against a small panel of human solid tumor cell lines. Significant inhibitions on DNA replication by 1 and 2 were also observed which could be explanative of their cytotoxicity.

Acetylene↗
PubMed1999

Lyso-PAF analogues and lysophosphatidylcholines from the marine sponge Spirastrella abata as inhibitors of cholesterol biosynthesis.

A series of phospholipids, including previously undescribed compounds 4-7, were isolated by a bioactivity-guided fractionation from the marine sponge Spirastrella abata as inhibitors of cholesterol biosynthesis in human liver cells. These compounds were identified as lyso-PAF analogues (1-5) and lysophosphatidylcholines (6, 7) based on NMR and MS analyses. Compounds 1-7 specifically blocked the conversion of lanosterol into cholesterol in the Chang liver cell.

Animals↗
PubMed1999

A comparative study on the structure and function of a cytolytic alpha-helical peptide and its antimicrobial beta-sheet diastereomer.

Antimicrobial peptides which adopt mainly or only beta-sheet structures have two or more disulfide bonds stabilizing their structure. The disruption of the disulfide bonds results in most cases in a large decrease in their antimicrobial activity. In the present study we examined the effect of d-amino acids incorporation on the structure and function of a cytolytic alpha-helical peptide which acts on erythrocytes and bacteria. The influence of a single or double d-amino acid replacement in alpha-helical peptides on their structure was reported previously in 50% 2,2,2, trifluoroethanol/water [Krause et al. (1995) Anal. Chem. 67, 252-258]. Here we used Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) spectroscopy and found that the predominant structure of the wild-type peptide is alpha-helix in phospholipid membranes, whereas the structure of the diastereomer is beta-sheet. However, the linear, beta-sheet diastereomer preserved its cytolytic activity on bacteria but not on erythrocytes. Previous studies have shown that the ability of antimicrobial peptides to lyse bacteria but not normal mammalian cells correlated with their ability to disintegrate preferentially negatively charged, but not zwitterionic phospholipid membranes. In contrast, the diastereomer described here disrupts zwitterionic and negatively charged vesicles with similar potencies to those of the hemolytic wild-type peptide. Interestingly, whereas addition of a positive charge to the N-terminus of the wild-type peptide (which caused a minor effect on its structure) increased activity only towards some of the bacteria tested, similar modification in the diastereomer increased activity towards all of them. Furthermore, the modified wild-type peptide preserved its potency to destabilize zwitterionic and negatively charged vesicles, whereas the modified diastereomer had a reduced potency on zwitterionic vesicles but increased potency on negatively charged vesicles. Overall our results suggest that this new class of antimicrobial diastereomeric peptides bind to the membrane in 'carpet-like' manner followed by membrane disruption and breakdown, rather than forming a transmembrane pore which interfere with the bacteria potential. These studies also open a way to design new broad-spectrum antibacterial peptides.

Amino Acid Sequence↗
PubMed1999

Increased TNF-alpha, IL-1 beta and IL-6 levels in the bronchoalveolar lavage fluid with the upregulation of their mRNA in macrophages lavaged from patients with active pulmonary tuberculosis.

SETTING: We hypothesized that patients with active pulmonary tuberculosis (TB) have tubercular pneumonitis and that alveolar macrophages at these sites release proinflammatory cytokines, resulting in high levels of cytokines in alveolar epithelial lining fluid. OBJECTIVE: To measure cytokine levels in bronchoalveolar lavage fluid (BALF) and to confirm the source of any cytokines by examination of alveolar macrophage cytokine mRNA. DESIGN: Seventeen active pulmonary TB patients and 15 healthy controls were prospectively studied. Bronchoalveolar lavage (BAL) was performed, proinflammatory cytokine levels were determined and alveolar macrophages isolated from BALF were prepared for RNA extraction and Northern blot analysis. RESULTS: Compared with healthy controls, TNF-alpha, IL-1 beta and IL-6 in BALF were all significantly higher in patients with active pulmonary TB, 298.7 +/- 85.9 vs. 8.9 +/- 2.7 (P = 0.0001); 164.4 +/- 67.5 vs. 8.9 +/- 2.7 (P = 0.003); 969.2 +/- 214.2 vs. 86.4 +/- 17.0 (mean +/- SE pg/ml) (P = 0.0001), respectively. Only TNF-alpha and IL-6 levels were significantly higher in sera of active pulmonary TB patients, 92.3 +/- 28.7 vs. 3.5 +/- 1.2; 15.2 +/- 5.4 vs. 2.1 +/- 2.1, respectively. Northern blot analysis revealed increased gene expression of these alveolar macrophage cytokines in patients with active pulmonary TB compared healthy controls. CONCLUSION: Significantly higher levels of TNF-alpha, IL-1 beta and IL-6 were found in BALF from patients with active pulmonary TB, and were released by alveolar macrophages in the TB lesions.

Adult↗
PubMed1999

HIV-associated parotid lymphoepithelial cysts.

BACKGROUND: An outstanding feature of the diffuse infiltrative lymphocytosis syndrome, or DILS, a subset of HIV-1 disease, is asymptomatic bilateral parotid swelling. Recognition of the entity is important because people with this disease will seek routine dental care. CASE DESCRIPTION: The authors present a classic case of DILS. The patient exhibited bilateral parotid swellings caused by lymphoepithelial cysts, cervical lymphadenopathy, a CD8 circulating lymphocytosis and a CD8 lymphocytic infiltration into the labial salivary glands. A right superficial parotidectomy had been performed several years previously. However, no intervention was advised for the remaining left parotid because of its benign course. CLINICAL IMPLICATIONS: Since patients with DILS can develop lymphomas, periodic observation is mandatory. Any change in the growth pattern requires that a fine-needle aspiration biopsy be performed.

Adult↗
PubMed1999

Titanium is a highly thrombogenic biomaterial: possible implications for osteogenesis.

Titanium has superior osteointegrating properties compared to other biomaterials. The mechanism for this is unknown. During the initial phase of bone implantation the biomaterial comes into direct contact with whole blood. In this study we use a newly developed in vitro chamber model to compare different commonly used biomaterials in contact with whole blood. These materials were selected with respect to their different osteointegrating properties in order to correlate these properties with the response to whole blood. In the presence of 3 IU/ml of heparin only titanium induced macroscopic clotting. This was reflected by the generation of thrombin-antithrombin which was much increased in blood in contact with titanium compared with steel and PVC. The coagulation activation caused by titanium was triggered by the intrinsic pathway because the generation of FXIIa-AT/C1 esterase inhibitor paralleled that of thrombin-antithrombin, and both thrombin-antithrombin complex and FXIIa-AT/C1 esterase inhibitor generation were abrogated by corn trypsin inhibitor, which is a specific inhibitor of FXIIa. The binding of platelets was increased on the titanium surface compared to the other biomaterial surfaces and the state of platelet activation was much more pronounced as reflected by the levels of beta-thromboglobulin and PDGF. This study indicates that titanium is unsuitable as a biomaterial in devices which are in direct contact with blood for a prolonged period. Furthermore, PDGF and other alpha-granule proteins e.g. TGF-beta, are known to be potent promotors of osteogenesis which suggests that the pronounced thrombogenic properties of titanium might contribute to the good osteointegrating properties.

Blood Coagulation↗
PubMed1999

Ingestion of green tea rapidly decreases prostaglandin E2 levels in rectal mucosa in humans.

The objective of this Phase I/II study was to assess the potential for green tea to be used as a colorectal cancer chemopreventive agent. This study measured the dose-related biological effects of administration of a single dose of green tea on the rectal mucosa of normal volunteers. Volunteers were admitted to the Robert Wood Johnson Medical School Clinical Research Center for 24 h. Baseline blood and rectal biopsy samples were obtained before the volunteers drank 0.6, 1.2, or 1.8 g of green tea solids dissolved in warm water. Blood samples were taken 2, 4, 8, and 24 h after the tea administration. Rectal biopsies were obtained at 4, 8, and 24 h. Prostaglandin E2 (PGE2) levels were analyzed by ELISA. Tea polyphenol levels in the blood, urine, and rectal tissue were measured by high-performance liquid chromatography using a Coulochem electrode array detection system. Statistical comparisons were made using ANOVA. Decreased levels of PGE2 in rectal mucosa were observed at 4 and 8 h after consumption of green tea. There was no correlation between inhibition of PGE2 and tissue or plasma levels of tea polyphenols. Ten of 14 subjects demonstrated a response to green tea, as evidenced by at least a 50% inhibition of PGE2 levels at 4 h. We conclude that green tea constituents have biological activity in inhibiting PGE2 synthesis. Given the 71% "response rate," we believe these data support the study of green tea as a colorectal chemopreventive agent in more long-term Phase II trials.

Administration, Oral↗
PubMed1999

Epidemiology of human ancylostomiasis among rural villagers in Nanlin County (Zhongzhou village), Anhui Province, China: age-associated prevalence, intensity and hookworm species identification.

Hookworm infection has traditionally been highly endemic to Anhui Province, China. Zhongzhou village in southwestern Anhui was identified as an endemic focus of infection caused by the hookworm Ancylostoma duodenale. This species was found to predominate over Necator americanus in ratios ranging from 35:1 based on the recovery of third-stage infective larvae (L,) to 21:1 based on the recovery of adult hookworms after anthelmintic chemotherapy. The overall prevalence of Ancylostoma infection in Zhongzhou was 33.2% with a greater prevalence among males. Unlike the age-associated prevalence patterns for N. americanus in Hainan and other southern Chinese provinces that show increasing prevalence with age and the highest prevalence among the elderly, the age-associated prevalence for A. duodenale in Zhongzhou exhibited a peak in middle-aged adults with subsequent decline. The age-associated intensity pattern exhibited a similar trend although the most of the hookworm infections were light or moderate infections as defined by quantitative egg counts.

Adolescent↗
PubMed1999

[Study on relationship between two different syndromes and three soluble cytokine receptors in patients with rheumatoid arthritis].

OBJECTIVE: To study the relationship between two different Syndromes (Cold-Damp Syndrome and Damp-Heat Syndrome) and three soluble cytokine receptors (sCKR, soluble interleukin-2 receptor, sIL-2R, soluble interleukin-6 receptor, sIL-6R, soluble tumor necrosis factor receptor 1, sTNFR1) in rheumatoid arthritis (RA). METHODS: The serum levels of three soluble receptors were measured by ELISA in patients with RA. RESULTS: The serum levels of 3 sCKR were significantly elevated in RA patients compared to healthy controls and obviously lowered after treatment (P < 0.01). The level of sIL-2R was significantly higher in Cold-Damp Syndrome than that in Damp-Heat Syndrome (P < 0.01), but serum sTNFR1 was significantly higher in Damp-Heat Syndrome than that in Cold-Damp Syndrome, there was no obvious difference between sIL-6R of two Syndromes. CONCLUSION: The high serum sIL-2R and low sTNFR1 might be a criterion of Cold-Damp Syndrome, but the high sTNFR1 and low sIL-2R might be a criterion of Damp-Heat Syndrome, these criteria reflected some states of different functions in immune system in patients with RA.

Adolescent↗
PubMed1999

[Effect of sodium ferulate on proliferation of rabbit aortic smooth muscle cells induced by oxidized LDL].

OBJECTIVE: To investigate the effect of sodium ferulate on the proliferation and lipid peroxidation of aortic smooth muscle cells(SMC). METHOD: Using experimental models of proliferation of cultured rabbit aortic SMC induced by oxidized-low density lipoprotein, the level of lipoperoxide(LPO) was determined by thiobarbituric acid reactive substance(TBARS) method and 3H-thymidine(3H-TdR) incorporation was used to observe DNA synthesis. RESULTS: SF markedly reduced the increase of medium LPO and inhibited the 3H-TdR incorporation in a dose-dependent manner. CONCLUSION: SF can inhibit the proliferation of SMC. The inhibitory effect may be related to the inhibition of lipid peroxidation.

Angelica sinensis↗
PubMed1999

[Analyzing of iatrogenetic factors causing 60 periapicitis and its treatment]

OBJECTIVE: To analyse the causes of iatrogenetic periapicitis and probe into the several methods of endo-treatment. METHODS: Prepare the root canal with routine,stepback,endo-ultrasound,precurve and synthesis methods, then fill the root cannal with gutta percha points,reexaminate after 6 months.RESULTS: 54 cases were successfully treated in total of 60 cases and the result showed quite effective after over 6 months.The successful rate was 90%. CONCLUSION: The key that reduces the incidence of iatrogenetic periapicitis and improves the successful rate of treatment is to grasp the indication of treatment,choice the fitting method and observe the operating routine.

Journal Article↗
PubMed1998

Isolation and stability of histidine-tagged proteins produced in plants via potyvirus gene vectors.

A system for the expression and purification of histidine-tagged proteins from plants has been developed using a tobacco etch potyvirus (TEV)-derived gene vectors. The vectors offered a convenient polylinker and a choice of histidine tagging at the recombinant proteins' N or C termini. These vectors were utilized for expression of proteins encoded by beet yellows closterovirus (BYV). Approximately 4 micrograms/g of 20-kDa BYV protein was readily isolated from plants systemically infected by hybrid TEV. In contrast, only minute quantities of 22-kDa BYV capsid protein (CP) histidine-tagged at its N or C terminus could be purified. Rapid degradation of the recombinant CP has been implicated in its failure to accumulate in infected plants. Fusion with TEV HC-Pro stabilized the histidine-tagged BYV CP and facilitated purification of the fusion product from infected plants. This same fusion approach was successfully used with the 24-kDa minor BYV CP. The recombinant proteins were recognized by histidine-tag-specific monoclonal antibody in immunoblot analysis. These results demonstrate the utility of a designed series of TEV vectors for expression, detection, and purification of the recombinant proteins and suggest that intrinsic protein stability is a major factor in a recovery of recombinant proteins from plants.

Amino Acid Sequence↗
PubMed1998

Compstatin inhibits complement and cellular activation in whole blood in two models of extracorporeal circulation.

Recently, a C3-binding cyclic synthetic peptide (Compstatin) has been identified that binds to complement component C3 and inhibits complement activation. Here we have examined the influence of Compstatin on complement activation and its indirect effects on cellular responses in whole blood in two models for extracorporeal circulation. Compstatin effectively inhibited the generation of C3a and sC5b-9 and the binding of C3/ C3 fragments to the polymer surface. As a result of the inhibition of complement activation, the activation of polymorphonuclear leukocytes (PMNs; as assessed by the expression of CD11b) and the binding of these cells (CD16(+)) to the polymer surface were almost completely lost. In contrast, blood cell counts were not affected. Using surface plasmon resonance technology, we have confirmed that Compstatin exerts its inhibitory effect on complement activation by binding to native C3. These data show that complement activation, leading to activation and binding of PMNs to the biomaterial surface, can be abolished by the addition of Compstatin. The properties of Compstatin make Compstatin a promising drug for use in extracorporeal circuits to avoid bioincompatibility reactions, eg, during cardiopulmonary bypass, but also a favorable precursor peptide for the development of an anticomplement drug for oral use.

Amino Acid Sequence↗