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Biomedical subjects

D Hong

Publications and source records attributed to D Hong.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Intraoperative endoscopic sphincterotomy for common bile duct stones during laparoscopic cholecystectomy].

OBJECTIVE: To assess the effects of approach-intraoperative endoscopic sphincterotomy (IOES) for common bile duct (CBD) stones during laparoscopic cholecystectomy (LC). METHODS: Twenty-seven patients with secondary CBD stones were treated by IOES during LC. Therapeutic effects were evaluated on the basis of the cure rate, early complications, and days of hospitalization. RESULTS: IOES was successfully performed in 26 (96.30%) of 27 cases, and their CBD stones were cleared completely. Two cases (7.69%) were complicated by mild acute pancreatitis. CONCLUSION: IOES as an alternative to the treatment of CBD stones during LC is safe and avoids reoperation.

Adult↗
PubMed1999

Nicotine-modified postinfarction left ventricular remodeling.

Cigarette smoking has been noted to impair wound healing in tissues such as skin, bone, and gut. This study was designed to examine whether nicotine adversely affects postinfarction cardiac wound healing and remodeling in an experimental model of myocardial infarction. For this purpose, two groups of rats were studied. The control group received a simple bandage, and the nicotine group had a section (1.75 mg/day) of a nicotine patch attached on their backs. After a 7-day treatment period, an anterior wall infarction was induced. A bandage-free 7-day healing period followed, after which hearts were isolated for mechanical tests. Nicotine-treated rats developed significantly enlarged left ventricles with thin, infarcted walls and a rightward shift in the passive pressure-volume relationship. Pressure-strain analysis also indicated possible changes in the material properties of the wound for nicotine-treated rats. In conclusion, nicotine has significant adverse effects on postinfarction healing and left ventricular remodeling. These observations have important clinical implications because of the enhanced risk for development of heart failure.

Animals↗
PubMed1999

Dexamethasone attenuates acute macromolecular efflux increase evoked by smokeless tobacco extract.

The purpose of this study was to determine whether dexamethasone attenuates the acute increase in macromolecular efflux from the oral mucosa elicited by an aqueous extract of smokeless tobacco (STE) in vivo, and, if so, whether this response is specific. Using intravital microscopy, we found that 20-min suffusion of STE elicited significant, concentration-related leaky site formation and an increase in clearance of fluorescein isothiocyanate-labeled dextran (FITC-dextran; mol mass 70 kDa) from the in situ hamster cheek pouch (P < 0.05). This response was significantly attenuated by dexamethasone (10 mg/kg iv). Dexamethasone also attenuated the bradykinin-induced leaky site formation and the increase in clearance of FITC-dextran from the cheek pouch. However, it had no significant effects on adenosine-induced responses. Dexamethasone had no significant effects on baseline arteriolar diameter and on bradykinin-induced vasodilation in the cheek pouch. Collectively, these data indicate that dexamethasone attenuates, in a specific fashion, the acute increase in macromolecular efflux from the in situ oral mucosa evoked by short-term suffusion of STE. We suggest that corticosteroids mitigate acute oral mucosa inflammation elicited by smokeless tobacco.

Adenosine↗
PubMed1999

Pancreatic pseudocyst: heparin-induced haemorrhage through the ampulla of Vater.

Bleeding from a pancreatic pseudocyst through the ampulla of Vater is a rare cause of overt gastrointestinal haemorrhage. Previously described mechanisms of such haemorrhage are reviewed. We report a case of a 74-year-old female with a pancreatic pseudocyst that bled into the gastrointestinal tract following the administration of heparin. We believe that this is the first reported case of its kind.

Aged↗
PubMed1999

[The application of intraoperative cholangiography in laparoscopic cholecystectomy].

OBJECTIVE: To evaluate the role of intraoperative cholangiography in laparoscopic cholecystectomy (LC). METHODS: Intraoperative cholangiography was attempted in 1 466 patients, and was successfully completed in 1382 patients. The success rate was 94.27%. RESULTS: Stones in the common bile duct in 92 patients, bile duct injury in 8 patients and abnormal bile duct in one patient were found. CONCLUSIONS: Intraoperative cholangiography is an accurate and safe procedure, can provide clear films of biliary tree, and has a high success rate. Its application can reduce the rate of bile duct injury and improve the quality of LC.

Bile Ducts↗
PubMed1998

Cooperation of a single lysine mutation and a C-terminal domain in the cytoplasmic sequestration of the p53 protein.

Cytoplasmic sequestration of the p53 tumor suppresser protein has been proposed as a mechanism involved in abolishing p53 function. However, the mechanisms regulating p53 subcellular localization remain unclear. In this report, we analyzed the possible existence of cis-acting sequences involved in intracellular trafficking of the p53 protein. To study p53 trafficking, the jellyfish green fluorescent protein (GFP) was fused to the wild-type or mutated p53 proteins for fast and sensitive analysis of protein localization in human MCF-7 breast cancer, RKO colon cancer, and SAOS-2 sarcoma cells. The wild-type p53/GFP fusion protein was localized in the cytoplasm, the nucleus, or both compartments in a subset of the cells. Mutagenesis analysis demonstrated that a single amino acid mutation of Lys-305 (mt p53) caused cytoplasmic sequestration of the p53 protein in the MCF-7 and RKO cells, whereas the fusion protein was distributed in both the cytoplasm and the nucleus of SAOS-2 cells. In SAOS-2 cells, the mutant p53 was a less efficient inducer of p21/CIP1/WAF1 expression. Cytoplasmic sequestration of the mt p53 was dependent upon the C-terminal region (residues 326-355) of the protein. These results indicated the involvement of cis-acting sequences in the regulation of p53 subcellular localization. Lys-305 is needed for nuclear import of p53 protein, and amino acid residues 326-355 can sequester mt p53 in the cytoplasm.

Amino Acid Sequence↗
PubMed1998

Thermology and facial telethermography. Part I: History and technical review.

This paper is a review of historical trends and technical advances in measurement of skin temperature. Most biochemical processes generate heat which must be dissipated. Skin is the major route for heat dissipation using blood as the heat exchange fluid. Skin temperature is an indicator of aberrations in metabolism, hemodynamics or in neuronal thermoregulatory processes. Since most of the heat dissipation of skin is by infrared blackbody emission, skin temperature should be measured without contact by monitoring the emitted infrared radiation. This has been the basis of telethermography. Recent advances in computing technology combined with advanced infrared sensor technology has led to the development of dynamic area telethermometry (DAT) which promises to be as an important new quantitative method to analyse the pathophysiology of thermoregulatory processes.

Face↗
PubMed1997

Genomic structure and promoter analysis of the gene encoding MM3, a member of transmembrane 4 superfamily.

We have isolated genomic clones encoding hamster MM3, a member of transmembrane 4 superfamily (TM4SF). Nucleotide (nt) sequence analysis revealed that it is composed of 5 exons spanning about 8 kb. The exon-intron organization of the MM3 gene was quite different from those of other TM4SF members. We also identified its transcription start points (tsp) and the promoter region. Deletion analysis of the promoter revealed that about 160-bp region containing TATA-box, CAAT-box and GC-box was necessary for efficient transcription in cultured cells.

Amino Acid Sequence↗
PubMed1996

The efficacy of a computer-assisted preoperative tutorial for clinical clerks.

OBJECTIVE: To assess the effectiveness of computer-assisted preoperative tutorials on human anatomy in improving the operating-room learning experience for clinical clerks. DESIGN: Crossover trials with immediate assessment and approximately 1-week delay between trials. SETTING: General surgery operating room of a university teaching hospital. SUBJECTS: Eight 4th-year clinical clerks on a single 8-week surgical rotation. MAIN OUTCOME MEASURES: The senior surgeon's assessment of the clerk's knowledge and understanding of the operation, according to a six-item questionnaire, and the clerk's own assessment of the experience in the operating room, according to an eight-item questionnaire. RESULTS: Surgeons rated the clerks' performances in the operating room as better when they had received the preoperative tutorial (mean [and standard deviation], 3.7 [0.4]) than when they had not received the preoperative tutorial (3.0 [0.3]). The difference (0.7 [0.6]) was statistically significant (t7 = 3.3, p < 0.01). Similarly, clerks rated their own experience more positively when they had received the tutorial (4.0 [0.2]) than when they had not (3.1 [0.3]), with the difference (0.9 [0.5]) being statistically significant (t7 = 4.9, p < 0.001). CONCLUSIONS: Short, preoperative, computer-assisted tutorials on human anatomy can have a positive impact on the clerk's level of knowledge and confidence in the operating room. Further research is warranted into the extent to which students spontaneously make use of these tutorials.

Anatomy↗
PubMed1995

The inhibition of DMBA-induced carcinogenesis by neoxanthin in hamster buccal pouch.

Neoxanthin, a major carotenoid pigment of spinach, is found in the Chloroplast membrane and has an unknown function in plants. Neoxanthin inhibited the production of superoxide anions in an artificial xanthine and xanthine oxidase system and depressed DNA synthesis in methylcholanthrene (MCA)-initiated C3H10T1/2 fibroblasts. in two-stage carcinogenesis experiments, neoxanthin at 0.2 micrograms/0.2 ml inhibited the formation of tumors that were induced sequentially by 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) in the buccal pouch of Syrian Golden hamsters. To assess the ongoing process of carcinogenesis, the activity of ornithine decarboxylase (ODC), required for cell proliferation, was analyzed. Neoxanthin inhibited the activity of ODC when animals were treated with neoxanthin one hour before the application of TPA in two-stage carcinogenesis. However, neoxanthin did not inhibit ODC activity when animals were treated with neoxanthin one hour before the application of DMBA in two-stage carcinogenesis, and there was no subsequent tumor formation. In a short-term anti-initiation experiment, neoxanthin inhibited the covalent binding of isotope-labeled DMBA to DNA by 53%. These results indicate that neoxanthin inhibits the initiation stage and the promotion stage in two-stage carcinogenesis. This suggests that neoxanthin may act as a potential chemopreventive agent.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Synthesis of 6-(methoxycarbonyl)prednisolone and its derivatives as new antiinflammatory steroidal antedrugs.

The synthesis and pharmacological evaluation of 6-(methoxycarbonyl)prednisolone (11) (a 3:1 mixture of 6 alpha-isomer 11a and 6 beta-isomer 11b), its 21-ol acetates 13a (6 alpha-isomer) and 13b (6 beta-isomer), and 17,21-diol acetonide 14 (a 6:1 mixture of 6 alpha-isomer 14a and 6 beta-isomer 14b) as local antiinflammatory steroidal antedrugs are described. The lead compound 11 was prepared via 12 steps from hydrocortisone (1). In the croton oil-induced ear edema assay, the topical antiinflammatory activity of 13a was higher than that of its epimer 13b. Except for 13a, the compounds (11, 13b, and 14) showed less activity than prednisolone. The systemic activities were assessed after 5 days of consecutive administration of these compounds at equiactive doses. Neither 11 nor 14 depressed plasma corticosteroid levels or significantly altered adrenal weights. Thymic involution was absent for 14, 15% for 11, and 47% for prednisolone at the equiactive doses. Both 13a and 13b showed significant reduction of adverse systemic effects assessed as the increase of body weight and the decreases of adrenal and thymus weights. The putative metabolite, carboxylic acid 12, showed 26 times less topical antiinflammatory activity than prednisolone. These results suggest that introduction of a labile methoxycarbonyl group at the C-6 position of prednisolone results in retention of antiinflammatory activity while reducing systemic effects noted following topical application of the parent compound prednisolone.

Administration, Topical↗
PubMed1994

Receptor binding affinity and antiproliferative activity of new antiinflammatory antedrugs: 6-methoxycarbonyl prednisolone and its derivatives.

Systemic side effects of antiinflammatory steroids may be minimized by incorporation of a metabolically labile group which is metabolized to make the steroid inactive upon entry into the systemic circulation (antedrug concept). In continuing efforts to minimize systemic adverse effects of potent antiinflammatory steroids, we have recently synthesized methyl 11 beta, 17 alpha, 21-trihydroxy-3,20-dioxopregna-1,4-diene-6-carboxylate (P6CM), its 21-acetoxys (P6CMa, P6CMb) and 17,21-acetonide (P6CMacet) derivatives. Structure-activity relationships have now been assessed and compared with prednisolone (P) for glucocorticoid receptor affinity (P IC50 = 28 nM), gluconeogenic activity as induction of tyrosine aminotransferase (EC50 = 4.4 nM) in H4-II-C3 HTC cells and antiproliferative effects (P = 48% inhibition of [3H]thymidine incorporation at 1 microM). Relative potencies for receptor binding (P = 1) were 0.12, 0.03, 0.004, and 0.0008 for P6CM, P6CMa, P6CMb, and P6CMacet, respectively, and enzyme induction relative potencies were 0.13, 0.05, 0.01, and 0.008, respectively. Antiproliferative effects of all derivatives were also less than that of P. These decreases suggest that addition of the 6-carboxymethyl group to prednisolone results in the general reduction of glucocorticoid activities. Taken together with previously reported results demonstrating retention of topical antiinflammatory activity of these novel steroids, P6CM and its derivatives may represent new locally active antiinflammatory steroids with reduced propensity to cause gluconeogenic and antiproliferative adverse effects.

Animals↗
PubMed1994

Upstream tRNA genes are essential for expression of small nuclear and cytoplasmic RNA genes in trypanosomes.

An interesting feature of trypanosome genome organization involves genes transcribed by RNA polymerase III. The U6 small nuclear RNA (snRNA), U-snRNA B (the U3 snRNA homolog), and 7SL RNA genes are closely linked with different, divergently oriented tRNA genes. To test the hypothesis that this association is of functional significance, we generated deletion and block substitution mutants of all three small RNA genes and monitored their effects by transient expression in cultured insect-form cells of Trypanosoma brucei. In each case, two extragenic regulatory elements were mapped to the A and B boxes of the respective companion tRNA gene. In addition, the tRNA(Thr) gene, which is upstream of the U6 snRNA gene, was shown by two different tests to be expressed in T. brucei cells, thus confirming its identity as a gene. This association between tRNA and small RNA genes appears to be a general phenomenon in the family Trypanosomatidae, since it is also observed at the U6 snRNA loci in Leishmania pifanoi and Crithidia fasciculata and at the 7SL RNA locus in L. pifanoi. We propose that the A- and B-box elements of small RNA-associated tRNA genes serve a dual role as intragenic promoter elements for the respective tRNA genes and as extragenic regulatory elements for the linked small RNA genes. The possible role of tRNA genes in regulating small RNA gene transcription is discussed.

Animals↗
PubMed1994

Effects of serum and insulin-like growth factor I on protein degradation and protease gene expression in rat L8 myotubes.

We examined the effects of horse and fetal bovine sera and insulin-like growth factor I (IGF-I) on proteolysis and protease gene expression in rat L8 skeletal myotube cultures. Protein degradation was measured as release of radioactive trichloroacetic acid (TCA)-soluble materials from intracellular proteins prelabeled with [3H]tyrosine. Horse serum and fetal bovine serum inhibited (P < .05) protein degradation by 19.7 and 8.1%, respectively. The IGF-I at 200 ng/mL inhibited protein degradation by 14% (P < .01) over a 6-h measurement period. To study the regulation of proteolysis by IGF-I, we evaluated its effects on protease mRNA and alpha-tubulin mRNA concentrations by Northern blot analysis. Proteases under investigation included cathepsins B and D, proteasome C2 subunit, and m-calpain. The IGF-I had no effect (P > .05) on cathepsin B and D gene expression but slightly increased (P < .05) m-calpain and alpha-tubulin mRNA concentrations. Proteasome mRNA concentration was reduced (P < .05) by IGF-I treatment. The changes in proteasome mRNA levels paralleled the IGF-I-dependent alterations in proteolysis. These observations suggest that effects of IGF-I on muscle protein degradation may be mediated by the specific down-regulation of proteasomal subunit mRNAs.

Animals↗
PubMed1993

Exploiting mechanistic differences between drug classes to define functional drug interaction domains on topoisomerase II. Evidence that several diverse DNA cleavage-enhancing agents share a common site of action on the enzyme.

To fully understand the mechanism of action of topoisomerase II-targeted agents, the effects of these drugs on the catalytic cycle of the enzyme must be well characterized. The present study utilized a nonturnover DNA catenation assay to determine the effects of several drugs (etoposide, genistein, CP-115,953, amsacrine, and novobiocin) on the DNA strand passage event mediated by topoisomerase II. With the exception of etoposide, all of the drugs inhibited the DNA strand passage step of the topoisomerase II catalytic cycle. A series of drug competition experiments that exploited this mechanistic difference was used to determine relationships between drug interaction domains on the enzyme. While the inclusion of etoposide in nonturnover DNA catenation assays reversed the inhibition of strand passage induced by genistein, CP-115,953, and amsacrine, it had no effect on the inhibition induced by novobiocin. These results strongly suggest that etoposide can displace other DNA cleavage-enhancing agents from the enzyme.DNA complex. Therefore, it is concluded that the interaction domain of etoposide overlaps those of several DNA cleavage-enhancing drugs but, consistent with previous observations (Robinson, M. J., Corbett, A. H., and Osheroff, N. (1993) Biochemistry 32, 3638-3643), is distinct from that of novobiocin.

Amsacrine↗