Tissue expression of gelsolin in oral carcinogenesis progression and its clinicopathological implications

Gelsolin has important cellular functions, including cell motility, proliferation and apoptosis. Altered gelsolin expression has been reported in several types of human malignancies, but has not been evaluated in oral carcinogenesis. In this study, all normal oral mucosa (n=12) had high gelsolin expression, whereas only 7.7% of oral precancerous lesions (n=26) had positive gelsolin expression. A significant increased positive staining was found in primary (n=51; 37.3%) and metastatic (n=26; 30.8%) oral squamous cell carcinoma lesions. Tumors with high gelsolin expression were associated with greater tumour size (P=0.007), invasive growth (P=0.02), and younger age (P=0.006). High gelsolin expression conferred a poor clinical outcome in patients with metastatic disease (P=0.005). In conclusion, a biphasic profile in gelsolin expression was observed during the progression of oral carcinogenesis. This may be due to a balance of its multiple cellular functions in tumour invasion and cell growth. The underlying mechanisms, however, remain to be elucidated.

Pre-operative chemo-radiotherapy improves the sphincter preservation rate in patients with rectal cancer located within 3 cm of the anal verge

AIMS

To evaluate whether pre-operative chemo-radiotherapy (CRT) improves the sphincter preservation rate for distal rectal cancers within 3 cm of the anal verge.

METHODS

Between January 2001 and December 2004, 49 patients underwent surgery with or without pre-operative CRT for primary rectal adenocarcinoma within 3 cm of the anal verge. Clinical data were retrospectively reviewed, including stage workups, surgical records and pathology records to determine sphincter preservation rate and the factors influencing sphincter preservation.

RESULTS

Of 49 patients with rectal tumours within 3 cm of the anal verge, 31 underwent pre-operative CRT followed by surgery (CRT group), and 18 underwent surgery alone (non-CRT group). Sphincter preservation was possible in 11 of 31 CRT patients, and only one of 18 non-CRT patients (p=0.036). The factors most influencing sphincter preservation were reduction in tumour size (p=0.005) and downstaging (p=0.001) following pre-operative CRT.

CONCLUSION

We could observe that sphincter preservation was improved in CRT group with statistical significance when compared to non-CRT group in our study patients with rectal cancer within 3 cm of the anal verge.

Comparative study of the subserosal versus submucosal dye injection method for sentinel node biopsy in gastric cancer

AIMS

To determine the most efficient injection method for a sentinel node (SN) biopsy in gastric cancer.

METHODS

Gastric adenocarcinoma patients without serosal invasion and distant metastasis were prospectively enrolled in this study. Isosulfan blue was injected into the subserosa (SS) of the first set of 71 consecutive patients and an intraoperative endoscopic submucosal (SM) injection of the same dye was injected into the second set of 50 consecutive patients. After the biopsy of blue-stained SNs, a gastrectomy with a D2 lymphadenectomy was performed. All dissected lymph nodes were evaluated for metastasis. The results of the SN biopsies were compared between the SS and SM dye injection methods.

RESULTS

Detection rate (0.92 vs 0.94), mean number of SNs (2.5 vs 2.9) and sensitivity (0.61 vs 0.46) of the SN biopsies were not significantly different between the SS and SM injection methods (P>0.05). The operation time was significantly shorter in the SS than the SM injection method (159.7 vs 172.7 min, P=0.030).

CONCLUSIONS

Both injection methods were equally efficient in their roles for a SN biopsy in gastric cancer. However, the SS injection method was more preferable due to its easy technique and short operation time.

Tuberculin reactivity in adults after 50 years of universal bacille Calmette–Guérin vaccination in Taiwan

We aimed to assess whether tuberculin reactivity in adults is affected by bacille Calmette-Guerin (BCG) vaccination after 50 years of universal BCG vaccination with 80-95% coverage. A community-based study on tuberculin reactivity in 619 participants was conducted in February 2000 in Keelung city, Taiwan. Information on BCG vaccination policies and annual risk of infection (ARI) in the underlying population was extracted from consecutive national prevalence surveys relating to the period 1952-1997. Compared with the expected ARI estimate, the standardized morbidity ratio of positive tuberculin response for vaccination in infancy was 2.2 (95% CI 0.3-15.5) for those aged <10 years. The corresponding figures for older age groups ranged from 3.6 (95% CI 2.2-5.9) for those aged 10-12 years to 0.7 (95% CI 0.5-0.9) for those aged 57-67 years. This suggests that the effect of BCG vaccination on positive tuberculin response in adults aged >30 years is probably negligible irrespective of age at vaccination or revaccination and that the tuberculin skin test can be used to diagnose TB in control programmes in countries with moderate or high incidence of TB.

Enhanced optical nonlinearity near the photonic bandgap edges of a cholesteric liquid crystal

The third-order Kerr nonlinear optical effect of a one-dimensional photonic bandgap structure of a cholesteric liquid crystal is investigated. In a femtosecond nonlinear transmission measurement, nonlinear optical changes in the bandgap edges are observed. From analysis of the dispersion relation, Kerr nonlinear coefficients of nematics, forming the cholesteric liquid crystal, are found to be enhanced by 1-2 orders of magnitude through the photonic bandgap structure.

Mechanism of bradykinin-induced Ca(2+) mobilization in MG63 human osteosarcoma cells

BACKGROUND

The effect of bradykinin on intracellular free Ca(2+) levels ([Ca(2+)](i)) in MG63 human osteosarcoma cells was explored using fura-2 as a Ca(2+) dye.

METHODS/RESULTS

Bradykinin (0.1 nM-1 microM) increased [Ca(2+)](i) in a concentration-dependent manner with an EC(50) value of 0.5 nM. The [Ca(2+)](i) signal comprised an initial peak and a fast decay which returned to baseline in 2 min. Extracellular Ca(2+) removal inhibited the peak [Ca(2+)](i )signals by 35 +/- 3%. Bradykinin (1 nM) failed to increase [Ca(2+)](i) in the absence of extracellular Ca(2+ )after cells were pretreated with thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor; 1 microM). Bradykinin (1 nM)-induced intracellular Ca(2+) release was nearly abolished by inhibiting phospholipase C with 2 microM 1-(6-((17 beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122). The [Ca(2+)](i )increase induced by 1 nM bradykinin in Ca(2+)- free medium was abolished by 1 nM HOE 140 (a B2 bradykinin receptor antagonist) but was not altered by 100 nM Des-Arg-HOE 140 (a B1 bradykinin receptor antagonist). Pretreatment with 1 pM pertussis toxin for 5 h in Ca(2+) medium inhibited 30 +/- 3% of 1 nM bradykinin-induced peak [Ca(2+)](i) increase.

CONCLUSIONS

Together, this study shows that bradykinin induced [Ca(2+)](i) increases in a concentration-dependent manner, by stimulating B2 bradykinin receptors leading to mobilization of Ca(2+) from the thapsigargin-sensitive stores in a manner dependent on inositol-1,4,5-trisphosphate, and also by inducing extracellular Ca(2+) influx. The bradykinin response was partly coupled to a pertussis toxin-sensitive G protein pathway.

Effect of nordihydroguaiaretic acid on intracellular Ca(2+) concentrations in C6 glioma cells

The effect of nordihydroguaiaretic acid (NDGA) on Ca(2+) signaling in C6 glioma cells has been investigated. NDGA (5-100 microM) increased [Ca(2+)]i concentration-dependently. The [Ca(2+)]i increase comprised an initial rise and an elevated phase over a time period of 4 min. Removal of extracellular Ca(2+) reduced NDGA-induced [Ca(2+)]i signals by 52+/-2%. After incubation of cells with NDGA in Ca(2+)-free medium for 4 min, addition of 3 mM CaCl2 induced a concentration-dependent increase in [Ca(2+)]i. NDGA (100 microM)-induced [Ca(2+)]i increases in Ca(2+)-containing medium was not changed by pretreatment with 10 microM nifedipine or verapamil. In Ca(2+)-free medium, pretreatment with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin (1 microM) abolished 100 microM NDGA-induced [Ca(2+)]i increases. Inhibition of phospholipase C with 2 microM U73122 had little effect on 100 microM NDGA-induced Ca(2+) release. Several other lipoxygenase inhibitors had no effect on basal [Ca(2+)]i. Collectively, the results suggest that NDGA increased [Ca(2+)]i in glioma cells in a lipoxygenase-independent manner, by releasing Ca(2+) from the endoplasmic reticulum in a manner independent of phospholipase C activity and by causing Ca(2+) influx.

Nordihydroguaiaretic acid elevates osteoblastic intracellular Ca2+

Nordihydroguaiaretic acid (NDGA) is widely used as a pharmacological tool to inhibit lipoxygenases; however, recent evidence suggests that it increases renal intracellular [Ca2+]i via novel mechanisms. Here the effect of NDGA on Ca2+ signaling in MG63 osteoblastic cells was explored using fura-2 as a Ca2+ indicator. NDGA (2-50 microM) increased [Ca2+]i in a concentration-dependent manner. The signal comprised an initial rise and an elevated phase over a time period of 4 min. Removing extracellular Ca2+ reduced 2-50 microM NDGA-induced signals by 62+/-2%. After incubation with 50 microM NDGA in Ca2+-free medium for several minutes, addition of 3 mM CaCl2 induced an increase in [Ca2+]i. NDGA (50 microM)-induced [Ca2+]i increases were not changed by pretreatment with 10 microM of verapamil, diltiazem, nifedipine, nimodipine and nicardipine. In Ca2+-free medium, pretreatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin (1 microM) inhibited 50 microM NDGA-induced [Ca2+]i increases by 69+/-3%. Inhibition of phospholipase C with 2 microM U73122 had little effect on 50 microM NDGA-induced Ca2+ release. Several other lipoxygenase inhibitors had no effect on basal [Ca2+]i. At a concentration that did not increase basal [Ca2+]i, NDGA (1 microM) did not alter 10 microM ATP- or 1 microM thapsigargin-induced [Ca2+]i increases. Alteration of protein kinase C activity with 1 nM phorbol 12-myristate 13-acetate or 2 microM GF 109203X did not affect 50 microM NDGA-induced [Ca2+]i increases. Together, the results show that NDGA increased [Ca2+]i in osteoblasts in a lipoxygenase-independent manner, by releasing stored Ca2+ in a fashion independent of phospholipase C activity, and by causing Ca2+ influx.

Crystallization and preliminary crystallographic results of apo and complex forms of human dehydroepiandrosterone sulfotransferase

Dehydroepiandrosterone sulfotransferase converts dehydroepiandrosterone (DHEA) and some other steroids to their sulfonated forms. The human enzyme has been crystallized in the presence of substrate (DHEA) alone, in the presence of substrate and non-sulfated cofactor analogue (PAP) and in the absence of both substrate and PAP in our laboratory, with data sets collected at a synchrotron source. The crystals of the uncomplexed form belong to the orthorhombic space group C222(1), with unit-cell parameters a = 85.26, b = 87.69, c = 108.20 A and data 99.2% complete to 2.35 A resolution. The DHEA complex crystallizes in the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 74.46, b = 127.49, c = 44.59 A and data 92.9% complete to 2.15 A resolution. The ternary complex crystallizes in the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 62.25, b = 87.28, c = 138.86 A and data 98.6% complete to 2.50 A resolution. Preliminary molecular-replacement solutions indicate significant variations in dimer formation.

Critical residues for the specificity of cofactors and substrates in human estrogenic 17beta-hydroxysteroid dehydrogenase 1: variants designed from the three-dimensional structure of the enzyme

Human estrogenic 17beta-hydroxysteroid dehydrogenase is an NADP(H)-preferring enzyme. It possesses 11- and 4-fold higher specificity toward NADP(H) over NAD(H) for oxidation and reduction, respectively, as demonstrated by kinetic studies. To elucidate the roles of the amino acids involved in cofactor specificity, we generated variants by site-directed mutagenesis. The results showed that introducing a positively charged residue, lysine, at the Ser12 position increased the enzyme's preference for NADP(H) more than 20-fold. Substitution of the negatively charged residue, aspartic acid, into the Leu36 position switched the enzyme's cofactor preference from NADPH to NAD with a 220-fold change in the ratio of the specificity toward the two cofactors in the case of oxidation. This variant dramatically abolished the enzyme's reductase function and stimulated its dehydrogenase activity, as shown by enzyme activity in intact cells. The substrate-binding pocket was also studied with four variants: Ser142Gly, Ser142Cys, His221Ala, and Glu282Ala. The Ser142Gly variant abolished most of the enzyme's oxidation and reduction activities. The residual reductase activity in vitro is less than 2% that of the wild-type enzyme. However, the Ser142Cys variant was fully inactive, both as a partially purified protein and in intact cells. This suggests that the bulky sulfhydryl group of cysteine entirely disrupted the catalytic triad and that the Ser142 side chain is important for maintaining the integrity of this triad. His221 variation weakened the apparent affinity for estrone, as demonstrated by a 30-fold increase in Michaelis-Menten constant, supporting its important role in substrate binding. This residue may play an important role in substrate inhibition via the formation of a dead-end complex. The formerly suggested importance of Glu282 could not be confirmed.

Mechanisms of diethylstilbestrol-induced calcium movement in MG63 human osteosarcoma cells

The effect of the estrogen diethylstilbestrol (DES) on cytosolic free Ca(2+) levels ([Ca(2+)](i)) in MG63 human osteoblasts was explored by using fura-2 as a Ca(2+) indicator. DES at concentrations between 5--20 microM induced an immediate increase in [Ca(2+)](i) in a concentration-dependent manner with an EC(50) of 10 microM. Removing extracellular Ca(2+) reduced the Ca(2+) signal by 70%. Pretreatment with 50 microM La(3+) or 10 microM of nifedipine, verapamil and diltiazem did not change 20 microM DES-induced [Ca(2+)](i) increases. Addition of 3 mM Ca(2+) increased [Ca(2+)](i) in cells pretreated with 20 microM DES in Ca(2+)-free medium. Pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor) to deplete the endoplasmic reticulum Ca(2+) store partly inhibited 20 microM DES-induced Ca(2+) release, but addition of carbonylcyanide m-chlorophenylhydrazone (CCCP; a mitochondrial uncoupler) and thapsigargin together abolished DES-induced Ca(2+) release. Conversely, pretreatment with 20 microM DES abrogated CCCP- and thapsigargin-induced Ca(2+) release. Inhibition of phospholipase C activity with 2 microM U73122 did not alter 20 microM DES-induced Ca2+ release. Another estrogen 17beta-estradiol also increased [Ca(2+)](i) in a concentration-dependent manner with an EC50 of 7 microM. Together, the data indicate that in human osteoblasts, DES increased [Ca(2+)](i) via causing Ca(2+) release from both mitochondria and the endoplasmic reticulum in a phospholipase C-independent manner, and by causing Ca(2+) influx.

Acute and long-term outcomes of stenting in coronary vessel > 3.0 mm, 3.0-2.5 mm, and < 2.5 mm

We compared the acute and long-term outcomes of stentings in coronary vessels > 3.0 mm, 3.0-2.5 mm, and < 2.5 mm. A total of 1,152 patients underwent coronary stenting was divided into three groups based on the reference vessel size. Group A consisted of 598 patients (667 lesions) with a reference vessel diameter > 3.0 mm, group B 485 patients (544 lesions) with a reference vessel diameter of 3.0-2.5 mm, and group C 114 patients (119 lesions) with a reference vessel diameter < 2.5 mm. The procedural success, stent thrombosis, and in-hospital cardiac event rate were similar in the three groups. At 6-month angiographic follow-up, the lesion restenotic rate was significantly higher in the small-vessel group (14%, 22%, and 26% in groups A, B, and C, respectively; P = 0.011). These differences appeared to result from a lesser acute gain and a lesser net gain in small-vessel group; the late luminal loss was similar in the three groups. During a follow-up duration of 28 +/- 3 months, group C patients had a significantly lower rate of event-free survival than the group A and B patients (71% vs. 85% and 82%; P = 0.002). Stepwise regression analysis demonstrated that complex lesion (P = 0.032) and long lesion (P = 0.046) are independent predictors of restenosis in very-small-vessel (< 2.5 mm) stenting. In conclusion, the acute results of stenting in small coronary arteries appear safe and feasible with a high procedural success rate and a low incidence of stent thrombosis. Stenting in patients with a small coronary artery appears to have a similar in-hospital cardiac event rate, but a higher angiographic restenosis rate and a lower event-free survival rate, compared to stenting in patients with a larger coronary artery. The predictors of restenosis in very-small-vessel stenting are complex lesions and long lesions. Cathet Cardiovasc Intervent 2001;53:314-322.

Solution structure, backbone dynamics, and stability of a double mutant single-chain monellin. structural origin of sweetness

Single-chain monellin (SCM), which is an engineered 94-residue polypeptide, has been characterized as being as sweet as native two-chain monellin. Data from gel-filtration high performance liquid chromatography and NMR has proven that SCM exists as a monomer in aqueous solution. In order to determine the structural origin of the taste of sweetness, we engineered several mutant SCM proteins by mutating Glu(2), Asp(7), and Arg(39) residues, which are responsible for sweetness. In this study, we present the solution structure, backbone dynamics, and stability of mutant SCM proteins using circular dichroism, fluorescence, and NMR spectroscopy. Based on the NMR data, a stable alpha-helix and five-stranded antiparallel beta-sheet were identified for double mutant SCM. Strands beta1 and beta2 are connected by a small bulge, and the disruption of the first beta-strand were observed with SCM(DR) comprising residues of Ile(38)-Cys(41). The dynamical and folding characteristics from circular dichroism, fluorescence, and backbone dynamics studies revealed that both wild type and mutant proteins showed distinct dynamical as well as stability differences, suggesting the important role of mutated residues in the sweet taste of SCM. Our results will provide an insight into the structural origin of sweet taste as well as the mutational effect in the stability of the engineered sweet protein SCM.

Human dehydroepiandrosterone sulfotransferase: purification and characterization of a recombinant protein

Dehydroepiandrosterone sulfate is the most abundant sulfated steroid transformed in human tissues and serves as a precursor for steroid hormones. Recombinant human dehydroepiandrosterone sulfotransferase (DHEA-ST) expressed in glutathione sulfotransferase fusion form in E. coli was purified using glutathione sepharose 4B affinity adsorption chromatography, a Factor Xa cleavage step, and Q-sepharose fast flow column chromatography. The homogeneous preparation had an activity toward dehydroepiandrosterone (DHEA) of 150+/-40 nmol/min per mg of protein under the assay conditions at an overall yield of 38.4%. The recombinant human DHEA-ST was shown to have a subunit mass of 34 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis, while having a molecular mass of 67.2 kDa by Superose-12 gel filtration. Our results indicate that the active recombinant enzyme expressed in E. coli is a homodimer.Biochemical properties for purified DHEA-ST were studied using DHEA as a substrate. The optimum pH ranged from pH 7 to 8, and the optimum temperature 40-45 degrees C. Ninety percent of basal DHEA-ST activity remained even after the enzyme was treated at 45 degrees C for 15 min. The 50% inactivation concentration of NaCl for DHEA-ST activity was determined to be around 500 mM. The K(m) value for DHEA was 1.9+/-0.3 microM and V(max)=190+/-18 nmol/min per mg of protein at 37 degrees C, pH 7.5.

Benefits of late coronary artery stenting in patients with acute myocardial infarction with and without thrombolytic therapy

BACKGROUND

There are no added benefits when balloon angioplasty is conducted in conjunction with thrombolytic therapy in patients with acute myocardial infarction. The purpose of this study was to determine whether or not thrombolysis has an impact on the outcome of late coronary artery stenting following acute myocardial infarction.

METHODS

The outcome of late coronary artery stenting in the infarct-related artery following acute infarction was compared in patients with (68 patients, group A) and without (118 patients, group B) prior thrombolytic therapy.

RESULTS

The baseline characteristics were similar in the 2 groups except that total occlusion of the infarct-related artery was more common in group B. The angiographic characteristics of the target lesion were similar in the 2 groups; the procedural success rate was 98% in both groups. There was no subacute thrombosis or other complications in either group. The 6-month follow-up coronary angiography and the restenosis rate was 18% in both groups; the reocclusion rate was 2% in group A and 4% in group B. The increment of the left ventricular ejection fraction was similar in both groups (6% versus 7%). During a follow-up duration of 18 +/- 3 months, the mortality rate was 3% versus 2%, reinfarction 0% versus 1%, recurrent angina 6% versus 4%, and target lesion revascularization by angioplasty 13% versus 13% in group A and B patients, respectively.

CONCLUSION

The outcome of late coronary artery stenting following acute myocardial infarction in patients with and without prior thrombolytic therapy was comparable. Significant improvement of left ventricular function was noted in both groups.

Clinical significance of hepatitis C virus infection to alcoholics with cirrhosis in Korea

BACKGROUND/METHODS

To investigate the prevalence and clinical significance of hepatitis C virus (HCV) infection and its relationship with the development of hepatocellular carcinoma (HCC), 162 consecutive alcoholic patients with cirrhosis were studied. Alcohol intake and parenteral risk factors were investigated by interview using a questionnaire. All patients had consumed at least 80 g alcohol/day for at least the past 5 years. Sera were tested for anti-HCV using a third-generation enzyme immunoassay (EIA), hepatitis B s antigen (HBsAg), anti-HBs, anti-HBc and anti-HIV. Serum HCV-RNA was detected by a one-tube reverse transcription-polymerase chain reaction (RT-PCR) method. Patients were classified into three groups accroding to the presence or absence of viral markers: (i) cases without anti-HCV or HBsAg (group A); (ii) cases with HBsAg only (group B); and (iii) cases with anti-HCV only (group C). Demographic and clinical findings were compared among the three groups.

RESULTS

Anti-HCV was present in 17 cases (10.5%) and HBsAg was present in 47 cases (29%). No patient had both anti-HCV and HBsAg. Group C subjects were the oldest, but the duration of drinking in this group was similar to that of group A. There was no significant difference in the daily alcohol intake among the three groups. Previous surgical operations and tattooing were more frequent in group C. Only one patient in group C was an intravenous drug user. The combined rate of HCC was significantly higher in groups B and C than in groups A (34, 23.5 and 6.1%, respectively). Laboratory data showed a higher platelet count, higher albumin level, lower bilirubin level and lower aspartate aminotransferase/alanine aminotransferase ratio in group C patients than in the other two groups. Hepatitis C virus RNA was detected in 14 of 85 cases tested (16.5%), in 11 of 12 cases (91.7%) with anti-HCV and in three of 73 cases (4.1%) without anti-HCV.

CONCLUSIONS

Hepatitis C virus infection is frequent in alcoholic patients with cirrhosis in Korea. Hepatitis C virus, as well as hepatitis B virus, infection may have a synergistic effect on the development of HCC in alcoholic patients.

Evaluation of a population-based screening for type 2 diabetes: a community-based screening project in Puli, Taiwan

BACKGROUND

A Markov method incorporating the relationships between prevalence, incidence, and mortality with respect to type 2 diabetes was used to assess a population-based screening for this disease.

METHODS

Data from a population-based screening project for residents of Puli, Taiwan, over 30 years of age (n= 1,219) were used to estimate the annual incidence of asymptomatic type 2 diabetes, the prevalence to incidence (P/I) ratio, and the hazard rate of death due to type 2 diabetes. These parameters were employed to develop a Markov process to evaluate the effects of early detection of type 2 diabetes on the risk of death from this disease in a simulated population (n= 10,000) receiving biennial, 5-year interval, or no screening.

RESULTS

The estimated annual incidence, average duration from asymptomatic to symptomatic type 2 diabetes (P/I ratio), and hazard rate for death from this disease were 0.86% (95% CI 0.50-1.48), 10 years (95% CI 7.69-14.01), and 1.1% per year, respectively. This yields an optimal screening interval of 5 years. Simulation of a 5-year interval screening regimen versus no screen ing yielded a relative risk reduction of 31% (95% CI 12-46%). A similar value was found for a biennial screening regime.

CONCLUSIONS

The results suggest that early detection of type 2 diabetes via a community-based screening project in developing countries with high prevalence is worthwhile.

Time trend of substance use among adolescent students in Taiwan, 1991-1996

The purpose of this study was to determine the prevalence and time trend of cigarette, alcohol, and illicit substance use among adolescent students in Taiwan, from 1991 through 1996. Subjects were selected through a two-stage random-sampling procedure. In the first stage, the strata were based on the type of school: middle school (13-15 years), high school (16-18), vocational school (16-18), and junior college (first 3 years only, 16-18). In the second stage, the strata were based on grade: one class each for 1st, 2nd, and 3rd grades were randomly selected from each type of school. Students were guaranteed anonymity before the questionnaire was administered. About 12,000 students from 100 schools participated each year in 1991 and 1994-1996. In 1993, 8,320 students from 65 schools participated. The prevalence of smoking and drinking decreased between 1991 and 1994, and then increased between 1994 and 1996. In 1996, the prevalence of illicit substance use was 15.4% for smoking, 16.7% for drinking, and 1.5% for illicit substance use. The rate of illicit substance use was lowest among high school students, followed by middle school students, and higher among students in vocational schools and junior colleges. The percentage of smokers and drinkers who had started early (at age 12 or earlier) rose every year. The prevalence of smoking and drinking habits among girls increased consistently during the study period. The most commonly abused substance was amphetamine. However, in 1996, sniffing glue became more prominent among middle school students, and flunitrazepam became the second most commonly abused substance among high school students.

Clinical and angiographic outcomes are similar with half, single, or multiple contiguous Palmaz-Schatz stent implantations for a single coronary stenosis

We compared the immediate and 6-month clinical and angiographic outcomes in patients undergoing a half, a single, or multiple contiguous stent implantations for a single coronary stenosis. Four hundred forty-three consecutive patients, who underwent elective Palmaz-Schatz stent implantations for 542 stenoses between November 1995 and July 1998, were analyzed. Sixty-three patients with 78 stenoses received a half stent (group A), 346 patients with 395 stenoses received a single stent (group B), and 68 patients with 69 stenoses received multiple overlapping stents (group C) for a single coronary stenosis. Seventy-eight half stents were implanted in 78 stenoses in group A, 395 stents in 395 stenoses in group B, and 141 stents in 69 stenoses in group C. The baseline characteristics were similar in the 3 groups. There were no deaths, no subacute thrombosis, and no vascular complications. Forty-nine patients with 57 stenoses in group A, 280 patients with 326 stenoses in group B, and 59 patients with 60 stenosis in group C underwent 6-month follow-up coronary angiography; the restenotic rate per patient was 10% in group A, 20% in group B, and 24% in group C (NS); the restenotic rate per stenosis was 9% in group A, 18% in group B, and 23% in group C (NS). Follow-up of 18 +/- 3 months revealed no differences in mortality, reinfarction, recurrent angina, target narrowing angioplasty, and elective coronary artery bypass surgery among the 3 groups. The overall cardiac event-free survival was 90%, 82%, and 83% in groups A, B, and C, respectively (p = 0.275). Thus, the procedural success rate, the in-hospital morbidity, and the long-term outcome are similar with coronary stenting using a half, a single, or multiple overlapping Palmaz-Schatz stents for a single stenosis.

Mechanisms and clinical significance of transient atrioventricular block during dobutamine stress echocardiography

OBJECTIVES

The purpose of this study was to investigate the possible mechanism and the clinical significance of transient atrioventricular block (AVB) during dobutamine stress echocardiography (DSE).

BACKGROUND

Transient AVB occurs rarely during DSE; however, the mechanisms responsible for blocks are unclear.

METHODS

A retrospective analysis of clinical, echocardiographic, catheterization, revascularization and head-up tilting test data was conducted in patients who developed transient AVB during DSE.

RESULTS

A total of 302 patients with known or suspected coronary artery disease (CAD) underwent DSE before coronary angiography between November 1997 and August 1998. Transient AVB developed in 12 patients during the test. Mobitz I block was noted in six patients and Mobitz II block in the other six patients. Nine of these 12 patients were subsequently shown to have CAD and three had no significant coronary artery stenosis. Mobitz II block was observed only in patients with CAD, while Mobitz I block occurred in three patients with and three patients without CAD (p < 0.05). Eight of the nine patients with CAD underwent a successful coronary angioplasty with or without stenting and a repeat DSE revealed no recurrence of heart block except in one patient. Head-up tilting test in the 12 patients revealed a positive response in three of the nine patients with and all three patients without CAD. A negative head-up tilting test was likely to be observed in patients with, as compared with those without, CAD in this study population (p < 0.05).

CONCLUSIONS

Transient AVB is not an infrequent manifestation during DSE. Both myocardial ischemia and neurally mediated vagal reflex may be responsible for this phenomenon. The development of Mobitz II block during DSE is indicative of the presence of CAD. A successful revascularization in patients with CAD who develop transient AVB may abolish this phenomenon.

Loss of heterozygosity in dysplasia and carcinoma of the gallbladder

The loss or inactivation of genes at specific chromosomal loci is one of the important mechanisms during the tumor development in humans. To investigate the role of genetic alterations in the carcinogenesis of gallbladder carcinoma, 32 carcinoma cases and 11 dysplasia cases of gallbladder were analyzed for loss of heterozygosity (LOH) and microsatellite instability (MI) on chromosomal regions 3p, 5q, 8p, 9p, 13q, 17p, and 18q with 17 microsatellite markers. Loss of one allele was identified on chromosomes 5q (55%) and 17p (40%) in dysplasias and on chromosomes 3p (52%), 5q (66%), 9p (52%), and 17p (58%) in carcinomas. LOH on chromosomes 13q and 18q was frequent only in advanced stage (III and IV) carcinomas (40% and 31%, respectively). LOH on chromosome 17p was correlated with intranuclear p53 accumulation. LOH on multiple chromosomes was more frequent in advanced carcinomas with metastasis than in cases without metastasis (P < .05). A widespread MI was observed in only one case of carcinoma. We conclude that LOH on 5q is an early change of carcinogenesis in gallbladder and that LOH on 3p and 9p is related to the progression of gallbladder carcinoma LOH on 13q and 18q is likely to be a late event. LOH on 17p occurs not only in dysplasia but also increases during the subsequent stages. Accumulation of LOH may be associated with carcinogenesis of the gallbladder, but the role of MI may not be significant.

String-plucking as a mechanism of chordal rupture during balloon mitral valvuloplasty using inoue balloon catheter

Percutaneous transvenous mitral commissurotomy using the Inoue technique was performed in a 59-year-old female with mitral stenosis and a severely calcified mitral leaflets. Although not entrapped in the subvalvular apparatus, the balloon catheter was deviated away from the mitral orifice-apex axis of the left ventricle during the inflation of the proximal balloon, which plucked and severed the chordae tendineae of the posterior mitral leaflet and resulted in severe mitral regurgitation.

Gallstone formation and gallbladder mucosal changes in mice fed a lithogenic diet

To investigate the pathologic change of gallbladder mucosa related to gallstone formation, 52 mice were fed a lithogenic diet containing 1% cholesterol and 0.5% cholic acid and we evaluated the sequential morphologic changes in the gallbladder from two days to 40 weeks. Cholesterol gallstones began to appear after two weeks and all the mice had gallstones after eight weeks. At two days, the mitotic index was at its highest. The gallbladder mucosa showed progressive hyperplastic change with earlier papillary projection of the folds and later inward proliferation. At the same time of stone formation, mucous cells forming glands appeared. Their histochemical profile of mucin was different from that of normal epithelium. Numbers of mucous cells increased gradually until 24 weeks but slightly decreased afterward. These results suggest hyperplasia and metaplasia are closely related to the gallstone formation. Hyperplasia is probably reactive to irritating effect of lithogenic bile or stone. Metaplasia and cholesterol gallstone may develop simultaneously, and act synergistically.