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.

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.

A Markov chain model to assess the efficacy of screening for non-insulin dependent diabetes mellitus (NIDDM)

BACKGROUND

The high prevalence and severe consequences of non-insulin dependent diabetes mellitus (NIDDM) in Taiwan calls for urgent measures to detect this disease in the asymptomatic phase. However, the efficacy of early detection of NIDDM is highly dependent on its natural history from the disease-free state, through the asymptomatic to the symptomatic phase and death from NIDDM or other causes.

METHODS

In order to project the above progression, a five-state illness-and-death Markov chain model was proposed to estimate these transition parameters using data from two rounds of a blood sugar screening programme for NIDDM in Puli, in central Taiwan.

RESULTS

Results showed that the annual incidence for asymptomatic NIDDM was 10.67 per 1000 (95% CI: 8.26-13.79) and the average duration between the asymptomatic and symptomatic phases (the sojourn time) was 8 years (95%CI: 5.74-11.29). The 10-year survival rate for asymptomatic NIDDM (79.35%) was better than that for symptomatic NIDDM (69.45%). Prediction of deaths from NIDDM was performed to assess how the efficacy of screening for NIDDM varied by different screening frequencies (annual, biennial, 4-yearly and the control group). Results indicated there is no substantial difference in mortality reduction from NIDDM among the annual, biennial and 4-yearly screening regimens. However, a 4-yearly screening regimen significantly reduced deaths from NIDDM by 40% (95% CI: 26-51%).

CONCLUSIONS

A long sojourn time and the substantial reduction in mortality suggest that a 4-yearly screening regime for NIDDM would be most effective and feasible in Taiwan. The proposed five-state Markov chain model can be applied to other similar NIDDM screening projects.

Solution structure of a sweet protein single-chain monellin determined by nuclear magnetic resonance and dynamical simulated annealing calculations

Single-chain monellin (SCM), which is an engineered 94-residue polypeptide, has proven to be as sweet as native two-chain monellin. SCM is more stable than the native monellin for both heat and acidic environments. Data from gel filtration HPLC and NMR indicate that the SCM exists as a monomer in aqueous solution. The solution structure of SCM has been determined by nuclear magnetic resonance (NMR) spectroscopy and dynamical simulated annealing calculations. A stable alpha-helix spanning residues Phe11-Ile26 and an antiparallel beta-sheet formed by residues 2-5, 36-38, 41-47, 54-64, 69-75, and 83-88 have been identified. The sheet was well defined by backbone-backbone NOEs, and the corresponding beta-strands were further confirmed by hydrogen bond networks based on amide hydrogen exchange data. Strands beta2 and beta3 are connected by a small bulge comprising residues Ile38-Cys41. A total of 993 distance and 56 dihedral angle restraints were used for simulated annealing calculations. The final simulated annealing structures (<SA>k) converged well with a root-mean-square deviation (rmsd) between backbone atoms of 0.49 A for secondary structural regions and 0.70 A for backbone atoms excluding two loop regions. The average restraint energy-minimized (REM) structure exhibited root-mean-square deviations of 1.19 A for backbone atoms and 0.85 A for backbone atoms excluding two loop regions with respect to 20 <SA>k structures. The solution structure of SCM revealed that the long alpha-helix was folded into the concave side of a six-stranded antiparallel beta-sheet. The side chains of Tyr63 and Asp66 which are common to all sweet peptides showed an opposite orientation relative to H1 helix, and they were all solvent-exposed. Residues at the proposed dimeric interface in the X-ray structure were observed to be mostly solvent-exposed and demonstrated high degrees of flexibility.

Antibiotic usage in primary care units in Taiwan

To understand the situation of antibiotic usage in primary care units in Taiwan, we collected all prescriptions over a 1 week period during March 2 to March 7, 1992, December 2 to December 7, 1992, and January 14 to January 19, 1994 from out-patient clinics of public health stations located in various parts of Taiwan. In the first time period 60 health stations were sampled, 18,350 patient-visits made and 23,674 diagnoses recorded. In the second time period 168 health stations were sampled, 84,143 patient-visits made and 96,528 diagnoses recorded. In the third time period 173 health stations were sampled with 85,623 patient-visits and 105,132 diagnoses recorded. The percentages of total patient-visits that resulted in antibiotic treatment were 16.7, 13.5 and 12.4% in the three time periods, respectively. The patient group under the age of 11 received the highest percentage of antibiotic treatment. The percentage of patient-visits that resulted in treatment with two or more types of antibiotics decreased from 25.4% in March, 1992 to 13.2% in January, 1994. Common cold was the most frequent diagnosis in patients receiving antibiotic therapy during the three time periods and accounted for 36.9% of total antibiotic prescriptions. Of the patients with the diagnosis of common cold, 29.7% received antibiotic treatment, of whom the largest group were paediatric patients (< 16 years). Penicillins, macrolides and cephalosporins were the most commonly prescribed antibiotics and accounted for 34.0, 21.8 and 21.3% of all prescribed antibiotics in the three study periods.

Cognition and utilization of Papanicolaou testing after the implementation of National Health Insurance in rural Taiwan

Previous reports have indicated that knowledge and utilization of Papanicolaou (Pap) testing in Taiwan are low, especially among residents of rural areas. However, those studies were conducted before the implementation of National Health Insurance (NHI), which now covers Pap testing. To assess the cognition and utilization of Pap testing after the implementation of NHI in 1995, 708 women aged 40 years or more were interviewed by the Yang-Ming Crusade in July 1997. Of these women, 276 (39%) had heard of the Pap test, 226 (32%) had had the test, and 156 (22%) had had the test in the last 3 years (1995-1997). Of those who had never had the Pap test before 1995, 17% underwent it for the first time after the implementation of NHI. In contrast to an earlier comparable study, the present study shows a significant increase in both the cognition and utilization rates of Pap testing (from 27% to 39%, and 18% to 32%, respectively) among women in rural areas after the test was covered by NHI. However, both knowledge and use of the test among older and lower-educated women are still low.

Papillary endothelial hyperplasia presenting as a chest wall neoplasm

Soft tissue hematomas generally resolve but may persist and develop into slow-growing, organized masses. These chronic expanding hematomas are characterized by a pseudocapsule and a predominantly necrotic central cavity, with foci of newly formed capillaries. These have been called chronic expanding hematomas or Masson's papillary endothelial hyperplasia. These lesions can mimic vascular neoplasms and must be considered in the evaluation of expanding soft tissue vascular malformations.

Expression of foreign antigens on the surface of Escherichia coli by fusion to the outer membrane protein traT

The traT gene is one of the F factor transfer genes and encodes an outer membrane protein which is involved in interactions between an Escherichia coli and its surroundings. This protein was altered so as to permit the expression of foreign proteins on the outer membrane of E. coli in this study. A 729-bp DNA fragment, including the leader and entire structural gene sequence of traT, was amplified and obtained by PCR. This sequence was then subcloned downstream of the tac promoter of pDR540, resulting in a TraT expression vector, pT2. Here, we report that the expression of TraT protein, fused either with a partial pre-S antigen of hepatitis B virus (60 and 98 amino acids, respectively) or with the snake venom rhodostomin (72 amino acids), was successfully achieved on the outer membrane of E. coli, using the pT2 plasmid. This result was demonstrated using dot blot and immunofluorescence analysis. This finding supports the notion that the pT2 plasmid can be used as an E. coli display system. This system can detect a foreign peptide of about 100 amino acid residues in length on the bacterial surface.