The origin of the most common mutation of adenine phosphoribosyltransferase among Japanese goes back to a prehistoric era

The incidence of adenine phosphoribosyltransferase (APRT) deficiency is higher among Japanese nationals than among other ethnic groups, and the most common mutation (APRT*J, ATG to ACG mutation at codon 136) accounts for 68% of the disease-causing genes among Japanese. To investigate the origin of these mutations, we studied the geographical distribution of the mutant genes in Japan. The APRT*J mutation is distributed nearly uniformly in the four main islands of Japan and Okinawa, suggesting a very early origin. The products of PCR amplification between positions 2344 and 2750 of the genomic APRT sequence were examined by SSCP analysis in random blood samples from Japanese, Korean, and Taiwanese nationals. Among 955 random Japanese blood samples, 7 (0.73%) were heterozygous for the APRT*J mutation, giving a calculated heterozygote frequency of 1.1% among Japanese for the entire APRT deficiency. None of 231 Taiwanese samples contained heterozygotes for the APRT*J mutation, while 2 (0.53%) of 356 Korean samples were heterozygous. In addition to the APRT*J sequence, a total of five variant sequences was found. Sequencing one variant revealed a base substitution in intron 4, suggesting therefore that they are harmless mutations. Since the APRT*J mutation is present in Koreans and Okinawans who share ancestors only before the Yayoi era (third century BC to third century AD), the origin of the APRT*J mutation predates 300 BC.

Positive charge at position 549 is essential for phosphatidylinositol 4,5-bisphosphate-hydrolyzing but not phosphatidylinositol-hydrolyzing activities of human phospholipase C delta1

Point mutagenesis, phosphatidylinositol (PI), and phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis assays and equilibrium centrifugation PIP2 assays were used to study the functional roles of four highly conserved arginine residues in the Y region of human phospholipase C delta1 (PLCdelta1) (Arg-527, -549, -556, -701). Most of the mutant enzymes were either partially defective or fully active in their abilities to catalyze the hydrolysis of PI or PIP2. However, upon substitution of Arg-549 by glycine or histidine, the mutant enzyme was defective in its ability to catalyze the hydrolysis of PIP2, but it is still able to hydrolyze PI. Replacing Arg-549 with lysine had little effect on the level of PI and PIP2 hydrolytic activities of the mutant enzyme. The residual PIP2 hydrolyzing activity of R549H is highly dependent on pH. R549H showed 5-10% of the PIP2-hydrolyzing activity of the native enzyme between pH 5 and 7 and nondetectable PIP2-hydrolyzing activity at pH 8. The PIP2-hydrolyzing activity of R549G was not detectable at all pH values. Kinetic analysis of PLCdelta1-catalyzed PIP2 hydrolysis revealed that the micellar dissociation constant Ks and interfacial Michaelis constant Km were similar in the native, R549K, and R549H enzymes; but the specific activity at the saturated substrate mole fraction and infinite level of substrate (Vmax) of the R549H mutant were reduced by a factor of 15. PIP2 competitively inhibits the native enzyme to hydrolyze PI at both pH 7 and 8. However, PIP2 inhibits R549H only at pH 7.0 and does not inhibit R549G at either pH. Taken together, these results suggest that positive charge at position 549 of PLCdelta1 protein is essential for the enzyme to recognize and catalyze the hydrolysis of PIP2 but not PI.

Etoposide causes illegitimate V(D)J recombination in human lymphoid leukemic cells

Etoposide is one of the most widely used antineoplastics. Unfortunately, the same treatment schedules associated with impressive efficacy are associated with an increased risk of secondary acute myeloid leukemia (AML), which has prompted its withdrawal from some treatment regimens, thereby potentially compromising efficacy against the original tumor. Because etoposide-associated AML is characterized by site-specific illegitimate DNA recombination, we studied whether etoposide could directly cause site-specific deletions of exons 2 and 3 in the hprt gene. Human lymphoid CCRF-CEM cells were treated with etoposide for 4 hours, and DNA was isolated after subculturing. The deletion of exons 2 and 3 from hprt was assayed by a quantitative polymerase chain reaction (PCR) method. In the absence of etoposide treatment, the frequency of deletions of exons 2 and 3 was very low (5.05 x 10(-8)). After exposure to 10 mumol/ L etoposide, the frequency of the exon 2 + 3 deletion was increased immediately after and at 24 hours after etoposide treatment (65 to 89 x 10(-8)) and increased to higher levels (128 to 173 x 10(-8)) after 2 and 6 days of subculture (P < .001 overall). The frequency of the exon 2 + 3 deletion assessed at 6 days of subculture after 4 hours of 0, 0.25, 1, 2.5, 5, and 10 mumol/L etoposide treatment increased with etoposide concentration, ie, 5.05 x 10(-8), 89.2 x 10(-8), 108 x 10(-8), 142 x 10(-8), 163 x 10(-8), and 173 x 10(-8), respectively (P < .0001). Sequencing of a subset of amplified products confirmed the presence of DNA sequences at the breakpoints consistent with V(D)J recombination. By contrast, exon 2 + 3 deletions after etoposide treatment in the myeloid cell lines KG-1A and K562 showed no evidence of V(D)J recombinase in their genesis. We conclude that etoposide can induce the illegitimate site-specific action of V(D)J recombinase on an unnatural DNA substrate after a single treatment in human lymphoid cells.

Role of oxidative DNA damage in hydroxychavicol-induced genotoxicity

Chewing betel quid has been linked to the development of oral cancer. In Taiwan, fresh Piper betle inflorescence is uniquely added to betel quid, and hydroxychavicol is the major phenolic components of P.betle inflorescence. In this study, we tested the mutagenic potential of hydroxychavicol in Salmonella typhimurium TA97, TA98, TA100 and TA102 with and without Aroclor-1254 induced S9 fraction. The results showed that hydroxychavicol was positive in S.typhimurium TA102 without metabolic activation. This increase in revertants was partially inhibited by catalase and superoxide dismutase. In Chinese hamster ovary (CHO-K1) cells, hydroxychavicol induced chromosome aberrations in a dose-dependent manner (10-50 microM) and the majority were chromosome-type aberrations. Hydroxychavicol also significantly increased the frequency of micronuclei in CHO-K1 cells up to 3-fold at a concentration of 40 microM. In addition, hydroxychavicol dose-dependently (0.1-20 microM) induced copper-dependent strand breaks in plasmid DNA. We further tested the oxidative DNA damage potential of hydroxychavicol by measuring 8-hydroxydeoxyguanosine (8-OH-dG) formation in CHO-K1 cells following an 18-h incubation and found that hydroxychavicol (6.25-100 microM) induced 8-OH-dG levels dose-dependently. The increase of 8-OH-dG formation was positively correlated (r = 0.79) with the hydroxychavicol-induced cytotoxicity. In conclusion, hydroxychavicol may exert its genotoxic potential through oxidative DNA damage.

[The study on the in-vitro stability of Tc(V)-99m dimercaptosuccinic acid]

Tc(V)-99m DMS, developed by Yokoyama et al. in 1981, has been recognized to be advantageous for the scintigraphic diagnosis of various malignant tumors and their metastasis, the aim of this study is to assess the in-vitro stability of Tc(V)-99m DMS. Thin-layer chromatography, including paper chromatography and silica gel thin layer chromatography, is performed to determine the change of radiochemical species presented in the reconstituted solution of Tc(V)-99m DMS prepared from the DMS kit (Institute of Nuclear Energy Research, Atomic Energy Council R.O.C.) and the commercial DMSA kit (Nephroscint, IRE CELLTARG Radiopharmaceuticals Japan). The bioscan imaging scanner is used to measure the Rf value and labeling efficiency of radiochemical species on the chromatographic strip. The in-vitro stability of Tc(V)-99m DMS prepared from the DMS kit and the commercial DMSA kit is studied by examining various parameters which include temperature(degree C) and time(hr) after reconstitution. The results show that the in-vitro stability of Tc(V)-99m DMS prepared from the DMS kit is actually better than that from the commercial DMSA kit. The one-step labeling method of DMS kit is much simpler than the two-step labeling method of DMSA kit.

Association between use of spermicide-coated condoms and Escherichia coli urinary tract infection in young women

Diaphragm/spermicide use increases the risk of urinary tract infection (UTI). To determine whether spermicide-coated condoms are also associated with an increased risk of UTI, the authors conducted a case-control study at a large health maintenance organization in Seattle, Washington. Cases were sexually active young women with acute UTI caused by Escherichia coli, identified from computerized laboratory files during 1990-1993. Age-matched controls were randomly selected from the enrollment files of the plan. Of 1,904 eligible women, 604 cases and 629 controls (65%) were interviewed. During the previous year, 40% of the cases and 31% of the controls had been exposed to any type of condom. The unadjusted odds ratio for UTI increased with frequency of condom exposure from 0.91 (95% confidence interval (CI) 0.65-1.28) for weekly or less during the previous month to 2.11 (95% CI 1.37-3.26) for more than once weekly. Exposure to spermicide-coated condoms conferred a higher risk of UTI, with odds ratios ranging from 1.09 (95% CI 0.58-2.05) for use weekly or less to 3.05 (95% CI 1.47-6.35) for use more than once weekly. In multivariate analyses, intercourse frequency (odds ratio (OR) = 1.14 per weekly episode), history of UTI (OR = 2.64), and frequency of spermicide-coated condom exposure (OR = 3.34 for more than once weekly and 5.65 for use more than twice weekly) were independent predictors of UTI. Spermicide-coated condoms were responsible for 42% of the UTIs among women who were exposed to these products.

Novel 3,7-diheterabicyclo[3.3.1]nonanes that possess predominant class III antiarrhythmic activity in 1-4 day post infarction dog models: X-ray diffraction analysis of 3-[4-(1H-imidazol-1-yl)benzoyl]-7-isopropyl-3,7-diazabicyclo[3.3.1]nona ne dihydroperchlorate

Several 3,7-diheterabicyclo[3.3.1]nonanes (DHBCNs) were prepared and screened in the Harris dog model for their ability to abolish pace-induced and sustained ventricular tachycardia (SVT) or prevent induction of ventricular tachycardia. In addition, an electrophysiological examination was made in the infarcted hearts of each animal to determine if more than one class activity was present. The examples exhibited predominately class III antiarrhythmic activity via a prolongation of the ventricular effective refractory period (VERP) in the models, although there may well be an underlying class Ib action present as exemplified by the ability of several of the agents to slow conduction in the myocardial infarcted dog hearts. 3-[4-(1H-Imidazol-1-yl)benzoyl]-7-isopropyl-3,7-diazabicyclo[3.3.1]nonan e dihydroperchlorate displayed powerful class III activity in the model systems while several other DHBCNs exhibited various degrees of class III action. An X-ray diffraction analysis revealed that this compound has a 3,7-diazabicyclo[3.3.1]nonane bicyclic unit in a chair-chair conformation.

Bioavailability and pharmacokinetics of ibuprofen in the broiler chicken

The intravenous, intramuscular and oral pharmacokinetics of ibuprofen in broiler chickens were investigated. In a preliminary study, plasma ibuprofen concentration-time profiles, following i.v. (25 mg/kg) dosing were best described by a 2-compartment model. After intravenous administration, the volume of distribution at steady-state (Vd(ss)), the total systemic clearance (ClB), the elimination half-life (t1/2 beta) and the MRT were 0.303 L/kg, 482.3 ml/h.kg, 2.71 h and 1.02 h, respectively. After intramuscular administration of ibuprofen, the tmax and Cmax were 0.37 h, and 42.2 micrograms/mL, respectively, with an estimated bioavailability of 46.7%. After oral administration of ibuprofen, the tmax and Cmax were 0.31 h and 23.91 micrograms/mL, respectively, with an estimated bioavailability of 24.2%. This is a preliminary study, examining the use of ibuprofen in broiler chickens, and should be followed by tissue residue and efficacy studies in different disease states.

Analysis of the rat clusterin gene promoter and cyclic AMP-regulated mRNA stability in testicular cells

Clusterin, also known as SGP-2 or TRPM-2, is expressed in the male reproductive tissues at different levels. The genomic structure of the rat clusterin gene was recently reported by our laboratory and others. In this study, we have determined the promoter responsible for the basal expression of the rat clusterin gene in testicular cells by analyzing the transient expression of the bacterial chloramphenicol acetyl transferase (CAT) reporter gene in MA-10 cells driven by different segments of the 5'-flanking region and the first intron of the clusterin gene. The region required for maximal basal expression was identified at -266 to +54. Addition of DNA fragments of the rat clusterin gene from -1298 to -266 bp, or from +54 to +1153 to (-266/+54)CAT resulted in a 87% decrease in CAT activity, suggesting the presence of inhibitory DNA elements in both the 5'-flanking region and the first intron. When DNA fragment in the first intron, +1153 to +2874, was included, CAT activity in the (-266/+2874)CAT construct increased to 70% of the clusterin promoter (-266/+54)CAT, indicating that stimulatory DNA elements may be present in this region of the first intron. Treatment of MA-10 cells with cyclic AMP (cAMP) neither decreased CAT activity driven by any of the clusterin/CAT chimeric plasmids examined in transient transfection studies, nor reduced the synthesis of nuclear clusterin RNA in nuclear run-on assays, indicating that the reduction of clusterin mRNA levels by cAMP previously reported in our laboratory is not exerted at the transcriptional level. Furthermore, addition of transcriptional or translational inhibitors (actinomycin D and cycloheximide respectively) abolished the cAMP effect observed in MA-10 cells. In summary, we have demonstrated that the basal transcription of the rat clusterin gene in testicular cells is under the control of both positive and negative regulatory sequences at the 5'-flanking region as well as in the first intron. The reduction of clusterin mRNA after exposure of MA-10 cells to cAMP is not due to a decrease in its transcriptional activity, but rather to an increase in the degradation of this mRNA through synthesis of a destabilizing protein(s) and its mRNA.

Postoperative morbidity and mortality of pancreaticoduodenectomy for periampullary cancer

OBJECTIVE

To find out factors that may influence the mortality after Whipple's operation, whether duct to mucosa anastomosis is better than classic "dunking" pancreaticojejunostomy and whether age over 70 is a contraindication for this procedure.

DESIGN

Prospectively randomised study.

SETTING

Teaching hospital, Taiwan, R.O.C.

PATIENTS

93 patients with periampullary cancer undergoing Whipple's operation were randomly divided into two groups. Forty-six with periampullary cancer underwent invaginating pancreaticojejunostomy, and 47 patients underwent duct to mucosa anastomosis for reconstruction.

MAIN OUTCOME MEASURES

Mortality and morbidity were compared between two groups.

RESULTS

The over all mortality was 8% (7/93). An albumin concentration of less than 30 g/L before operation and operative blood loss influenced the surgical mortality both in the univariate and multivariate analysis. Age over 70 years was not a factor. Patients with duct to mucosa anastomoses had a leak rate of 4% (2/47), morbidity of 21% (10/47) and mortality of 6% (3/47). Patients with an invaginated pancreaticojejunostomy had a leak rate of 15% (7/46), morbidity of 33% (15/46), and mortality of 9% (4/46). The need for total parenteral nutrition in the invaginated group (33%) was statistically greater than in the other group (11%) (p = 0.01).

CONCLUSIONS

The morbidity and mortality of pancreaticoduodenectomy for periampullary cancer although slightly greater for patients over the age of 70 are acceptable. The factors that may influence the mortality are an albumin concentration of less then 30 g/L and the amount of blood lost during operation. The duct to mucosa anastomosis is a safe procedure, which has a lower leak rate and less need for total parenteral nutrition than pancreaticojejunostomy.

Ultrasound-guided fine-needle aspiration biopsy of lung cancers

One hundred eighty-eight patients with 191 lung cancers were collected retrospectively to evaluate the diagnostic results and to determine the accuracy of cytologic diagnoses obtained from ultrasound-guided fine-needle aspiration biopsy (US-guided FNAB), and to discuss the necessity of large-bore tissue core needle biopsy. All 188 patients underwent US-guided FNAB, and 20 patients with 21 lung tumors also underwent US-guided tissue-core needle biopsy. Using US-guided FNAB alone, the positive cytologic results and correct cytologic diagnoses were 91% (174 of 191) and 71% (37 of 52). If both US-guided FNAB and selected US-guided tissue core needle biopsy (n = 21) were evaluated, the positive cytologic or histologic results and correct cytologic or histologic diagnoses were 94% (180 of 191) and 80% (45 of 57), respectively. Analyzing the disagreement between the cytologic results and histologic diagnoses (n = 15), we found that the disagreement usually occurred in the specimens with poorly differentiated carcinomas (nonspecific cell type) (53% [8 of 15]); of these, two patients (13% [2 of 15], small cell carcinoma) would have a change in treatment. The complications of US-guided FNAB were pneumothorax (n = 3), hemoptysis (n = 1), hemothorax (n = 1), and suspected tract metastasis (n = 1). We conclude that US-guided FNAB has a high diagnostic yield in lung cancers, and US-guided tissue core needle biopsy is only necessary in patients whose cytologic results are negative or who have poorly differentiated carcinomas.