VDUP1 potentiates Ras-mediated angiogenesis via ROS production in endothelial cells

Vitamin D3 up-regulated protein 1 (VDUP1) is a tumor suppressor of which expression is reduced in a variety of cancer cells, and enforced expression inhibits the tumor cell proliferation. It inhibits the activity of thioredoxin, thus contributing cellular ROS generation. Since ROS is a critical factor for angiogenesis, we investigated the role of VDUP1 in angiogenesis and endothelial proliferation. The expression of VDUP1 was upregulated by overexpression of an oncogene, Ras. Enforced expression of VDUP1 increases ROS production and proliferation of Ras-overexpressing endothelial cells. Overexpression of VDUP1 increases the resistance to the anchorage-dependent cell death and tube formation of the Ras-overexpressing endothelial cell. In addition, the removal of ROS by ROS scavenger attenuates the effect of VDUP1 on tube formation. These results suggest that VDUP1 is involved in Ras-mediated angiogenesis via ROS generation in endothelial cells.

Carrier-mediated antiferromagnetic interlayer exchange coupling in diluted magnetic semiconductor multilayers Ga1-xMnxAs/GaAs:Be

We report the antiferromagnetic (AFM) interlayer exchange coupling between Ga0.97Mn0.03As ferromagnetic semiconductor layers separated by Be-doped GaAs spacers. Polarized neutron reflectivity reveals a characteristic splitting at the wave vector corresponding to twice the multilayer period, indicating that the coupling between the ferromagnetic layers is AFM. When the applied field is increased to above the saturation field, this AFM coupling is suppressed. This behavior is not observed when the spacers are undoped, suggesting that the observed AFM coupling is mediated by doped charge carriers.

Stability of zinc oxide nanofluids prepared with aggregated nanocrystalline powders

Aqueous zinc oxide (ZnO) suspensions were prepared using a two-step preparation method in which an aggregated nanocrystalline ZnO powder was dispersed in water using a polyelectrolyte. The fluid showed anomalously high thermal conductivity when compared with the Maxwell and Hamilton-Crosser predictions. However, analysis of the particle size distribution showed that the fluid contained aggregated 20 nm crystallites of ZnO with a high volume fraction of particles larger than 100 nm. Sedimentation experiments revealed that particles settled out of the stationary fluid over times ranging from 0.1 hours to well over 10,000 hours. The size of the particles remaining in suspension agreed well with predictions made using Stoke's law, suggesting flocculation was not occurring in the fluids. Finally, a new concept of nanofluid stability is introduced based on the height of the fluid, sedimentation, Brownian motion and the kinetic energy of the particles.

Metabolic syndrome and visceral obesity as risk factors for reflux oesophagitis: a cross-sectional case-control study of 7078 Koreans undergoing health check-ups

BACKGROUND

Obesity has been associated with reflux oesophagitis. However, the relationship between metabolic syndrome characterised by visceral obesity and reflux oesophagitis is unclear.

AIM

To investigate whether metabolic syndrome or visceral obesity is a risk factor for reflux oesophagitis.

METHODS

A cross-sectional study of 7078 subjects undergoing upper endoscopy during health check-ups was conducted (3539 patients with reflux oesophagitis vs age- and sex-matched controls). We further analysed according to categories of visceral adipose tissue and subcutaneous adipose tissue area with 750 cases and age-, sex- and waist circumference-matched controls who underwent abdominal CT scan.

RESULTS

The prevalence of metabolic syndrome was higher in cases than controls (26.9% vs 18.5%, p<0.001). Multivariate analysis demonstrated that metabolic syndrome is associated with reflux oesophagitis (odds ratio (OR) = 1.42; 95% confidence interval (CI), 1.26 to 1.60). Among the individual components of metabolic syndrome, waist circumference (OR = 1.47; 95% CI, 1.30 to 1.65) and triglyceride (OR = 1.20; 95% CI, 1.05 to 1.36) independently increased the risk for reflux oesophagitis. On sub-analysis, cases showed higher mean visceral adipose tissue area (cm(2)) (136.1 (SD 57.8) vs 124.0 (SD 54.7), p<0.001) and subcutaneous adipose tissue area (cm(2)) (145.9 (SD 56.8) vs 133.5 (SD 50.7), p<0.001). However, only visceral adipose tissue area was an independent risk factor for reflux oesophagitis after adjusting for multiple confounders including smoking, alcohol, body mass index (BMI) and subcutaneous adipose tissue area (OR = 1.60; 95% CI, 1.03 to 2.48, lowest quartile vs highest quartile).

CONCLUSIONS

Metabolic syndrome was associated with reflux oesophagitis. Abdominal obesity, especially visceral obesity, was an important risk factor for reflux oesophagitis.

Pharmacokinetic interaction between DA-8159, a new erectogenic, and metformin in rats: competitive inhibition of metabolism via hepatic CYP3A1/2

BACKGROUND AND PURPOSE

Erectile dysfunction is highly prevalent in diabetic patients and PDE V inhibitors are effective and safe for the treatment of erectile dysfunction in men with diabetes. Therefore, in this study we investigated whether a pharmacokinetic interaction occurs between DA-8159 and metformin, as both drugs are metabolized via hepatic CYP3A1/2 in rats.

EXPERIMENTAL APPROACH

DA-8159 (30 mg kg(-1)) and metformin (100 mg kg(-1)), both separately and together, were administered to rats either intravenously or orally. The V (max), K (m), CL(int), apparent inhibition constants (K (i)), [I]/K (i) and concentrations of each drug in the liver and intestine were then measured.

KEY RESULTS

After i.v. administration of both drugs simultaneously, the AUC of DA-8159 and metformin was significantly greater (21.2 and 33.9% increase for DA-8159 and metformin, respectively) than that of each drug alone. After p.o. administration of the drugs, the AUC of metformin was also significantly greater (20.7% increase) in the presence of DA-8159 than in its absence. However, the AUC of DA-8159 was similar in the absence and presence of metformin.

CONCLUSIONS AND IMPLICATIONS

The significantly greater AUC of metformin and DA-8159 after i.v. administration of both drugs and of metformin after p.o. administration of both drugs is probably due to competitive inhibition for the metabolism of these drugs via hepatic CYP3A1/2. However, the similar AUCs of DA-8159 in the absence and presence of metformin, after p.o. administration, indicates that the dose of metformin used was insufficient to inhibit the hepatic and intestinal metabolism of DA-8159.

Detection of CSF leak in spinal CSF leak syndrome using MR myelography: correlation with radioisotope cisternography

BACKGROUND AND PURPOSE

Spinal CSF leak syndrome is a unique disorder caused by spinal CSF leak. In this study, we attempted to determine whether MR myelography (MRM) can detect the leakage site in the spine.

MATERIALS AND METHODS

We performed both MRM and radioisotope cisternography (RIC) in 15 patients with spinal CSF leak syndrome. Patients were included in this study if they had at least 2 of the following criteria: 1) orthostatic headache, 2) low CSF opening pressure, and 3) diffuse pachymeningeal enhancement on brain MR imaging. For comparison, we performed MRM in 15 subjects without symptoms of spinal CSF leak syndrome. MRM was performed with the 2D turbo spin-echo technique in the entire spine by using a 1.5T scanner. Two blinded radiologists evaluated the MRM findings in a total of 30 cases, composed of patient and control groups, with regard to the presence of leakage and the level of leakage if present. RIC was performed only in the patient group and was assessed by consensus among 3 physicians experienced in nuclear medicine. The diagnostic performance of MRM and RIC was evaluated on the basis of the clinical diagnosis of spinal CSF leak syndrome.

RESULTS

The sensitivity, specificity, and accuracy of MR myelography for detecting CSF leak was 86.7%, 86.7%, and 86.7% for reader 1, respectively, and 80.0%, 93.3%, and 86.7% for reader 2, respectively. The sensitivity of RIC was 93.3%. Agreement between the 2 techniques for the detection of CSF leak was substantial in reader 1 and moderate in reader 2 (kappa = 0.634 and 0.444, respectively).

CONCLUSION

MRM is an effective tool for detecting CSF leak in the spine in patients with spinal CSF leak syndrome.

Effects of steeping conditions of waxy rice on the physical and sensory characteristics of gangjung (a traditional Korean oil-puffed snack)

The objectives of this study were to investigate the effects of steeping period (1, 11, and 21 d) and temperature (15, 25, and 35 degrees C) of waxy rice on the physical and sensory characteristics of Gangjung (a traditional Korean oil-puffed snack). Increasing the steeping period from 1 to 21 d and increasing the temperature from 15 to 35 degrees C markedly increased the oil absorption ratio of Gangjung. Textural analysis indicated that the number of peaks (representing the internal air cell characteristics) for Gangjung decreased in proportion with increasing steeping temperature and period, but that the hardness was affected significantly only by steeping period. Regarding the sensory characteristics of Gangjung, 5 appearance, 7 flavor, and 9 texture attributes were developed and evaluated by trained descriptive panelists. When the steeping temperature and the steeping period were increased, the degree of expansion, size, and degree of external roughness increased, while the strength of external color decreased. Regarding the flavor attributes, the intensity of sweetness and toasted carbohydrate food flavor tended to decrease with increasing steeping temperature and period, while sourness and butyric acid flavor, which are related to the fermentation of waxy rice, increased. Finally, the increased steeping temperature and period decreased the intensity of hardness, crispness, and toughness of Gangjung but increased the degree of fracture, degree of melting, and oiliness.

Helicobacter pylori eradication for low-grade gastric mucosa-associated lymphoid tissue lymphoma is more successful in inducing remission in distal compared to proximal disease

A series of studies has shown that Helicobacter pylori eradication induces remission in most patients with low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma. However, there have been few reports about the effect of bacterial treatment on the gastric MALT lymphoma in Korea, a well-known H. pylori endemic area. A total of 111 H. pylori-infected patients were prospectively enrolled in Seoul National University Hospital and 99 among them were completely followed up according to our protocol. After H. pylori eradication, tumoural response was evaluated by endoscopy and histopathology every 2–3 months till complete remission (CR) and every 6 months after achieving CR. Median follow-up period was 41 months (range, 11–125 months). Helicobacter pylori was successfully eradicated in all 99 patients and CR was obtained in 84 (84.8%) of 99 patients. The median time to reach CR was 3 months and 94% of CR is in continuous complete remission. Five patients with CR relapsed after 10–22 months without the evidence of H. pylori reinfection. Cumulative recurrence rate was 2.3, 7.7 and 9.3% at 1, 2 and 3 years, respectively. Tumours were mainly located in distal stomach (67.7%) and tumours in distal stomach were associated with more favourable response than those in proximal stomach (P=0.001). Majority of patients with low-grade gastric MALT lymphoma treated by exclusive H. pylori eradication have a favourable long-term outcome, offering a real chance of cure. Tumour location could be a predictive factor for remission following H. pylori eradication.

Destruction of EDTA by mediated electrochemical oxidation process: monitoring by continuous CO2 measurements

The mediated electrochemical oxidation (MEO) process with cerium(IV) in nitric acid as the oxidizing medium was employed for the destruction of ethylenediaminetetraacetic acid (EDTA) in batch and continuous feeding modes. A complete mineralization of EDTA to CO(2) and water was achieved. The system parameters studied were the temperature (343, 353 and 368 K), concentration of nitric acid (2, 3 and 4M), Ce(IV) concentration (0.7-0.95 M), aqueous EDTA concentration (67-268 mM) , flow rate of EDTA addition (3.0-7.5 ml/min), and feeding time (30 min and 2h). The batch process CO(2) pattern clearly showed two distinct kinetic regimes. Accordingly the overall CO(2) formation rate constants were evaluated for fast and slow processes using pseudo first-order kinetics. In case of continuous organic feeding, the CO(2) formation rate constant was obtained using a new proposed mathematical procedure based on geometrical progression. The only parameter in the calculations was the first-order rate constant. The theoretical CO(2) evolution pattern was fitted on to the experimental data to obtain the formation rate constants. The activation energy was calculated based on the CO(2) formation constants and presented. The application of mathematical procedure predicted a steady-state attainment of CO(2) evolution for the destruction process during a long-term organic feeding and observed experimentally.

Stable multidomain structures formed in the process of magnetization reversal in GaMnAs ferromagnetic semiconductor thin films

The process of magnetization reversal in ferromagnetic Ga(1-x)Mn(x)As epilayers has been systematically investigated using the planar Hall effect (PHE). Interestingly, we have observed a pronounced asymmetry in the PHE hysteresis when the range of the field scan is restricted to fields below the final magnetization transition. The observed behavior indicates that (a) multidomain structures are formed as M undergoes a reorientation, (b) the domain landscape formed in this way remains stable even after the magnetic field is switched off, and (c) the reorientation of magnetization directions corresponding to the transition points in PHE takes place separately within each domain.

Preliminary studies using hybrid mediated electrochemical oxidation (HMEO) for the removal of persistent organic pollutants (POPs)

This study investigates the hybrid mediated electrochemical oxidation (HMEO) technology, which is a newly developed non thermal electrochemical oxidation process for organic destruction. A combination of ozone and ultrasonication processes to the mediated electrochemical oxidation (MEO) process is termed as hybrid mediated electrochemical oxidation. The electrochemical cell was developed in this laboratory. In the present study, several organic compounds, such as phenol, benzoquinone and ethylenediaminetetraacetic acid (EDTA), were chosen as the model organic pollutants to be destructed by the hybrid process. The organic destruction was monitored based on the CO2 generation and total organic carbon (TOC) reduction. The HMEO process was found to be extremely effective in the destruction of all the target organics chosen in this study. The information obtained from this study will provide an insight in adopting this technique for dealing with more recalcitrant organics (POPs).

Subdural hematoma in spontaneous CSF hypovolemia

Of 67 consecutive patients with spontaneous CSF hypovolemia (SCH), 11 (16.4%) had subdural hematoma (SDH). Patients with SDH were older (p = 0.005), more likely to be male (p = 0.035), and displayed longer time to diagnosis of SCH (p = 0.019) than those without SDH. All patients with SDH showed the findings of pseudo-subarachnoid hemorrhage on CT and responded favorably to epidural blood patches and neurosurgical drainage.

Assessment of converting from intravenous to oral administration of cyclosporin A in pediatric allogeneic hematopoietic stem cell transplant recipients

We studied the administration method during a transition period from continuous intravenous (i.v.) infusion to oral administration of cyclosporin A (CsA). Thirty-two pediatric hematopoietic stem cell transplant (HSCT) recipients, between the ages of 8 months and 15.6 years (median 7.1 years) participated in this study. The pharmacokinetic properties of CsA was evaluated during the transition period from i.v. to oral CsA. The daily oral dose of CsA was three times higher than the i.v. dose. Oral dosing began immediately after the continuous infusion was discontinued. Whole-blood CsA concentrations were measured by a monoclonal fluorescence polarization immunoassay (FPIA). The mean+/-s.d. value of bioavailability (F), maximum concentration (C(max)), half-life (t(1/2)) of CsA were 43.1+/-14.4%, 1135.3+/-340.6 ng/ml and 3.1+/-1.2 h, respectively. Mean clearance (CL)+/-s.d. was 480.9+/-103.7, 414.9+/-137.1 and 320+/-51.8 ml/h/kg in patients <20, 20-40 and >40 kg of body weight, respectively. The CsA CL of younger children was significantly greater than for older children (P=0.044). CsA trough levels were maintained within the therapeutic range throughout the transition period. Therefore, our findings suggest that the immediate administration of an oral formulation, after discontinuation of the continuous infusion, would be practical and effective for routine clinical use.

Stable bioavailability of cyclosporin A, regardless of food intake, from soft gelatin capsules containing a new self-nanoemulsifying formulation

AIM

We recently succeeded in preparing soft gelatin capsules containing a new self-nanoemulsifying formulation consisting of cyclosporin A (CsA), triacetin, polyoxyl 40 hydrogenated castor oil, polysorbate 20, medium chain triglycerides and medium chain mono- and diglycerides. The soft capsules containing the new formulation exhibited a significantly improved physical stability in terms of the appearance of the gelatin capsule shells and the composition of the fill mass during long-term storage, compared to commercially available soft capsules containing CsA, in which ethanol was employed as a cosolvent of CsA. In the present study, the influence of a fat-rich meal on the bioavailability of CsA from the soft capsule containing the new formulation (test drug) was evaluated and the results compared to those obtained with a representative soft capsule of CsA.

VOLUNTEERS AND METHODS

A randomized, open-label, 3-way crossover study was performed in the test capsules and reference soft capsules, in a fasted state or after a fat-rich breakfast. 18 healthy male volunteers received a single dose of the reference formulation (Neoral, Novartis AG, Basel, Switzerland) or test formulation (2 capsules each, 200 mg as CsA) with 240 ml of water with a 1-week washout period between the treatments, after a fat-rich (670 kcal, 45 g fat) breakfast (for the test drug, Treatment A; for the reference drug, Treatment B) or a 12-h fasting (for the test drug, Treatment C). Serial blood samples, collected over a 24-h period after the administration, were assayed for blood CsA concentrations using a specific monoclonal radioimmunoassay.

RESULTS

The differences in bioavailability parameters (i.e., AUC(0-24h), AUC(0-infinity) and C(max)) between the treatments were within the range of 80-125% of the reference treatment. An analysis of variance (ANOVA) revealed no significant differences (p > 0.05) between subjects, formulations or periods. The 90% confidence intervals (CI) indicated that the differences between the treatments (Treatments A and B, Treatments A and C) were also within the criteria.

CONCLUSION

These results indicate that the bioavailability of CsA from the test drug is equivalent to reference in the fed state, and is likely to be less influenced by a fat-rich meal. Therefore, the new formulation of CsA using triacetin appears to have an advantage over the commercial soft capsules of CsA using a volatile cosolvent such as ethanol.

Plasma low-molecular weight fluorescence in type 1 diabetes mellitus

Characteristic tissue fluorescence is associated with advanced glycation end product (AGE) accumulation in experimental diabetes models, but its utility in patients with type 1 diabetes remains to be established. We studied 148 patients with type 1 diabetes and 77 healthy age-matched control subjects. Low-molecular weight (LMW) fluorophore levels were estimated in plasma samples obtained after an overnight fast. Intra- and interassay coefficients of variation were 4.7% and 6.4%, respectively. LMW fluorophore levels were significantly higher in patients with diabetes than in control subjects (6.3 +/- 0.6 AU/mL vs. 4.1 +/- 0.3; P = 0.007). However, all of this difference came from patients with microvascular complications (n = 67, 7.5 +/- 1.3). There was no significant difference in LMW fluorescence between complication-free patients (4.4 +/- 0.2) and control subjects (P > 0.05). On multivariate analysis, LMW fluorophores correlated with measures of renal function (P < 0.05) but not with diabetes per se. In addition, there was no correlation between LMW fluorophores and the markers of oxidative stress or systemic inflammation. Longitudinal and interventional studies are required to determine whether the association between LMW fluorophores and nephropathy is cause or effect.

Polycarboxylic acid nanoparticles for ophthalmic drug delivery: an ex vivo evaluation with human cornea

In ophthalmic drug delivery, a major problem is retaining an adequate concentration of a therapeutic agent in the pre-corneal area. Polycarboxylic acid carriers such as polyacrylic acid and polyitaconic acid in sub-colloidal, nanoparticulate hydrogel form have a strong potential for sustained release of a drug in ocular delivery. Formulations have been prepared of brimonidine loaded in polycarboxylic (polyacrylic and polyitaconic) acid nanoparticles for potential ophthalmic delivery. These particles were prepared by a reverse micro-emulsion polymerization technique with sizes in the range of 50 nm. The loading efficiencies of the drug brimonidine in the particles were shown to be between 80-85% for polyacrylic acid nanoparticles and between 65-70% for polyitaconic nanoparticles. The loading efficiency was also found to be pH dependent. In a preliminary biocompatibility test, human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability, whereas polyitaconic acid nanoparticles were found to be toxic. Two-photon laser scanning microscopic studies of the fluorescently labelled polyacrylic acid nanoparticles and human cornea shows that they are adhesive on the corneal surface. The polyacrylic acid nanoparticles demonstrated a controlled release of the opthalmological drug (Brimonidine) through the human cornea as compared to that of the commercial formulation, Alphagan.

Different pharmacokinetics of nicotine following intravenous administration of nicotine base and nicotine hydrogen tartarate in rats

Pharmacokinetics of nicotine was studied in rats following intravenous (i.v.) administration of nicotine base (NB) and nicotine hydrogen tartarate salt (NS) at a nicotine dose of 1 mg/kg. The area under the plasma concentration-time curve (AUC), mean residence time (MRT), systemic clearance (CL), distribution volume at steady state (V(ss)) and terminal plasma half-life (T(1/2,beta)) of nicotine were compared between NB and NS. Compared to NS, NB exhibited higher and sustained plasma nicotine levels, thereby yielding significantly (P<0.05) larger AUC (66.3 vs. 27.7 microg ml/min), MRT (165.7 vs. 58.3 min), T(1/2,beta) (144.2 vs. 51.4 min) and a lower CL (18.3 vs. 46.3 ml/min per kg). The V(ss) was comparable between the two compounds. The metabolic conversion to cotinine from NS was threefold larger than that from NB. The plasma protein binding and distribution to blood cells were comparable between the compounds. The apparent partition coefficient (APC) of NS decreased as a function of its concentration, while that of NB remained nearly constant. Particles of different mean sizes were observed for the 1% (w/v) aqueous solutions of NS (388.6 nm) and NB (123.8 nm). Different metabolism and/or elimination between NB and NS appear to be mainly responsible for their different pharmacokinetics.

The transport of a hepatoprotective agent, isopropryl 2-(1-3-dithiethane-2-ylidene)-2[N-(4-methyl-thiazole-2-yl) carbamoyl] acetate (YH439), across Caco-2 cell monolayers

Isopropryl 2-(1-3-dithiethane-2-ylidene)-2[N-(4-methyl-thiazole-2-yl) carbamoyl] acetate (YH439) is currently under phase II clinical trials by the Yuhan Research Center for use as a hepatoprotective agent. Unfortunately, the oral bioavailbility of YH439, which is sparingly soluble in water (i.e., 0.3 microg/ml or 0.91 microM at room temperature), reportedly, is negligible regardless of the dose administered to rats in the 10-300 mg/kg range. The bioavailability of the compound increased up to 24%, when administered in the form of a micellar solution (700 microg/ml or 2.1 mM for YH439) at a dose of 10 mg/kg, suggesting that its limited solubility is associated with its negligible bioavailability. In order to obtain additional information concerning the bioavailability of YH439, the mechanism(s) involved in gastrointestinal (GI) absorption were investigated in the present study. For this purpose, the transport of YH430 across a Caco-2 cell monolayer was measured in a Transwell. A permeability of 4.07 x 10(-5) cm/s was obtained for the absorptive (i.e., apical to basolateral direction) transport of 0.42 pM YH439, implicating that the in vivo GI absorption is nearly complete. The absorptive transport exhibited a slight concentration-dependency with an intrinsic clearance (CLi) of 0.38 microLL/cm2/sec, which accounted for 28.1% of the total intrinsic clearance (i.e., CLi plus the intrinsic clearance for the linear component) of the transport. Thus, saturation of the absorption process appears to be a minor factor in limiting the bioavailability of the compound. The apparent permeability of YH439 from the basolateral to the apical direction (i.e., efflux, 6.67 x 10(-5) cm/s) was comparable to that for absorptive transport, but, interestingly, a more distinct concentration-dependency was observed for this transport. However, the efflux does not appear to influence the bioavailability of the compound, as evidenced by the sufficiently high permeability in the absorption direction. Rather, a reportedly extensive first-pass hepatic metabolism appears to be a principal factor in limiting the bioavailability. In this respect, reducing the first-pass metabolism by some means would lead to a higher bioavailability of the compound. Thus, elevation of the absorption rate of YH439 becomes a necessity. From a practical point of view, increasing the concentration of YH439 in the GI fluid appears to be a feasible way to increase the absorption rate, because the compound is primarily absorbed via a linear mechanism. In summary, the solubilization of YH439, as previously demonstrated for a micellar solution of the compound, appears to be a practical way to increase the oral bioavailability of YH439.

Medullary nephrocalcinosis associated with long-term furosemide abuse in adults

BACKGROUND

The use of furosemide is well recognized as a predisposing factor of nephrocalcinosis in infants. Although furosemide is widely used for various medical conditions in adults, its association with nephrocalcinosis in adults is not well established.

METHODS

We studied 18 consecutive adult patients (male:female ratio 1:17, age range 21-59 years) who habitually took furosemide to control weight or oedema for long periods of time (range 3-25 years). The daily dose of continuous intake of furosemide ranged from 40 to 2800 mg. Nephrocalcinosis was evaluated using renal ultrasonography (US), computed tomography (CT), or kidney biopsies.

RESULTS

Renal US and CT revealed bilateral nephrocalcinosis of the medullary pyramids in 15 (83.3%) out of 18 patients. The duration of furosemide abuse was similar between nephrocalcinosis positive (NC(+)) and nephrocalcinosis negative (NC(-)) groups. The daily dose of furosemide was nearly 10 times higher in the NC(+) group (range 120-2800 mg, mean 538 mg) than the NC(-) group (range 40-80 mg, mean 67 mg). All patients showed variable degrees of renal insufficiency and there was no difference in creatinine clearance between the NC(+) and NC(-) groups (P>0.05). Kidney biopsies performed in three patients showed focal tubulo-interstitial fibrosis and atrophy and calcifications were observed in outer medullary tubulo-interstitium.

CONCLUSIONS

Long-term furosemide abuse can cause medullary nephrocalcinosis in adults, and the risk of developing of nephrocalcinosis seems to be correlated with the daily dose of furosemide. We suggest that long-term furosemide abuse should be suspected in adult patients when medullary nephrocalcinosis is incidentally detected by US or CT.

Effects of cysteine on the pharmacokinetics of intravenous phenytoin in rats with protein-calorie malnutrition

The effects of cysteine on the pharmacokinetics of phenytoin and one of its metabolites, 5-(p-hydroxyphenyl)-5-phenylhydantoin (pHPPH) were investigated after intravenous administration of phenytoin, 25 mg/kg, to control rats (4-week fed on 23% casein diet) and rats with PCM (protein-calorie malnutrition, 4-week fed on 5% casein diet) and PCMC (PCM with oral cysteine supplementation, 250 mg/kg, twice daily starting from the fourth week). In rats with PCM and PCMC, the phenytoin hydroxylation (to form pHPPH) activities were significantly smaller (164, 103 and 95.3 pmol/min per mg protein for the control rats, and rats with PCM and PCMC, respectively) than that in control rats. In rats with PCMC, the intrinsic clearance of phenytoin, CL(int) was significantly slower than those in control rats and rats with PCM (0.175, 0.131 and 0.044 ml/min). The above data suggested that the formation of pHPPH could be reduced in rats with PCM and PCMC. This was supported by significantly smaller 24-h urinary excretion of pHPPH (54.7, 35.6 and 32.5% of intravenous dose of phenytoin) in rats with PCM and PCMC than that in control rats. In rats with PCM, the maximum velocity (0.344, 0.203 and 0.196 microg/min), apparent volume of distribution in central compartment (44.4, 65.4 and 72.2 ml/kg) of phenytoin, and total area under the plasma concentration-time curve from time zero to time infinity (609, 714 and 1210 microg min/ml), renal clearance (20.5, 13.4 and 4.67 ml/min per kg) and 24-h urinary excretion (54.7, 35.6 and 32.5% of intravenous dose of phenytoin) of pHPPH were not returned to control levels by cysteine supplementation (rats with PCMC). This could be mainly due to the fact that the phenytoin hydroxylation activity in rats with PCMC was not returned to control level.

Comparative study of the behavioral and neuropsychologic characteristics of tic disorder with or without attention-deficit hyperactivity disorder (ADHD)

To study the nature of the comorbidity of tic disorder and attention-deficit hyperactivity disorder (ADHD), patients with tic disorder with or without ADHD were compared on the basis of clinical ratings and neuropsychologic tests. Seventy-eight children were involved in this study: 16 with tic disorder, 19 with comorbid tic disorder and ADHD, 21 with ADHD, and 22 normal controls. Rating scales for ADHD, the Child Behavior Checklist and the Yale Global Tic Severity Scale, were completed in clinical groups. To identify differences in neuropsychologic function among the four groups, the results of seven neuropsychologic tests of global cognitive abilities, attention, information-processing capacity, and fine motor skill were compared. On most behavioral and neuropsychologic tests, the tic disorder with ADHD and the ADHD groups demonstrated similar performance patterns and marked deficits compared with the tic disorder and the control groups, whereas in most of the attention tests, the ADHD group made more commission errors than the tic disorder with ADHD group. These findings suggest that the tic disorder with ADHD group has marked cognitive deficits and behavioral disturbance similar to the ADHD group, whereas the tic disorder group is more similar to the controls. The tic disorder with ADHD group might represent a true comorbidity of the two disorders.

Incidence of gastroesophageal malignancy in patients with dyspepsia in Hong Kong: implications for screening strategies

BACKGROUND

A "test-and-treat" strategy for H pylori infection has been recommended in Europe and North America as safe and cost-effective for management of patients with dyspepsia. The primary aim of this study was to determine the frequency of gastroesophageal cancer in 2 groups of patients with dyspepsia: those 45 years of age or younger without "alarm" symptoms (low-risk group) and patients over 45 years of age or any patient with "alarm" symptoms (high-risk group). A secondary aim was to determine the frequency of gastric cancer among patients in the low-risk group with or without a positive serology for H pylori.

METHODS

Patients with persistent dyspepsia were recruited from 4 regional hospitals in Hong Kong. Those in the low-risk group were evaluated for H pylori by using a whole blood serology test; they underwent endoscopy within 1 week. Those in the high-risk group and those taking nonsteroidal anti-inflammatory drugs (NSAIDs) underwent endoscopy promptly. Alarm symptoms were as follows: weight loss (10 or more pounds over 8 weeks), recurrent vomiting, dysphagia, bleeding, or anemia.

RESULTS

Of 2627 patients enrolled, 1017 were in the low-risk group and 1610 in the high-risk group. Twenty-three patients (0.9%) had gastroesophageal cancers (20 gastric, 3 esophageal). Four patients with cancer (17.4%) were in the low-risk group (3 gastric, 1 esophageal); all except the patient with esophageal cancer had a positive serology test. In the high-risk group, 19 patients had cancer (17 gastric, 2 esophageal).

CONCLUSION

Gastric cancer is relatively frequent among young patients with dyspepsia who have no alarm features in Hong Kong. This finding raises concerns as to the safety of the "test-and-treat" strategy for the management of patients with dyspepsia in Asia.

Mechanistic insight into the inactivation of carboxypeptidase A by alpha-benzyl-2-oxo-1,3-oxazolidine-4-acetic acid, a novel type of irreversible inhibitor for carboxypeptidase A with no stereospecificity

On the basis of the active site topology and enzymic catalytic mechanism of carboxypeptidase A (CPA), a prototypical zinc-containing proteolytic enzyme, alpha-benzyl-2-oxo-1,3-oxazolidine-4-acetic acid (1), was designed as a novel type of mechanism-based inactivator of the enzyme. All four possible stereoisomers of the inhibitor were synthesized in an enantiomerically pure form starting with optically active aspartic acid, and their CPA inhibitory activities were evaluated to find that surprisingly all of the four stereoisomers inhibit CPA in a time dependent manner. The inhibited enzyme did not regain its enzymic activity upon dialysis. The inactivations were prevented by 2-benzylsuccinic acid, a competitive inhibitor that is known to bind the active site of the enzyme. These kinetic results strongly support that the inactivators attach covalently to the enzyme at the active site. The analysis of ESI mass spectral data of the inactivated CPA ascertained the conclusion from the kinetic results. The values of second-order inhibitory rate constants (k(obs)/[I](o)) fall in the range of 1.7-3.6 M(-1) min(-1). The lack of stereospecificity shown in the inactivation led us to propose that the ring cleavage occurs by the nucleophilic attack at the 2-position rather than at the 5-position and the ring opening takes place in an addition-elimination mechanism. The tetrahedral transition state that would be generated in this pathway is thought to be stabilized by the active site zinc ion, which was supported by the PM3 semiemprical calculations. In addition, alpha-benzyl-2-oxo-1,3-oxazolidine-5-acetic acid (18), a structural isomer of 1 was also found to inactivate CPA in an irreversible manner, reinforcing the nucleophilic addition-elimination mechanism. The present study demonstrates that the transition state for the inactivation pathway plays a critical role in determining stereochemistry of the inactivation.