Probing the structural diversities of long alpha-neurotoxins by fluorescence quenching studies

Trp fluorescence of Ophiophagus hannah neurotoxins (Oh-4, Oh-6A, Oh-7, and Oh-8) and Bungarus multicinctus (alpha-bungarotoxin was quenched by acrylamide and iodide. Acrylamide quenching studies indicated that the degree of exposure of Trp residues in the neurotoxins followed the order Oh-8 > Oh-7 > Oh-6A > Oh-4 > alpha-bungarotoxin, as did the accessibility for iodide. These results reveal that the exposed degree of Trp residues and the microenvironment surrounding Trp residues in the neurotoxins differ, even though their Trp residues and positively charged residues are located at the same or homologous positions. In contrast to unfolded Oh-4, Oh-6A, Oh-7, and alpha-bungarotoxin, unfolding of Oh-8 by reduction and S-carboxymethylation caused a notable decrease in the susceptibility of their Trp residues for iodide. These observations support the view that the side chains of Trp residues and positively charged residues in their native structure do not point toward the same spatial positions. Computer models of the neurotoxins are in good agreement with this proposition. These results elucidate why the conserved Trp residues and cationic groups do not always play the same roles in the biological activities of the neurotoxins.

Mutations of p53 gene in gastric carcinoma in Taiwan

BACKGROUND

p53 gene mutation and p53 protein accumulation is the most common event in human cancers. The present study was conducted to investigate the occurrence of p53 mutations in patients with gastric carcinoma in Taiwan.

MATERIALS AND METHODS

Tumor samples from 36 patients with primary gastric carcinoma undergoing radical gastrectomy were evaluated. The mutational status of the p53 (exons 5 to 8) was screened by polymerase chain reaction/single strand conformation polymorphism (PCR-SSCP) analysis followed by direct sequencing. These results were compared with p53 protein expression as assessed by immunohistochemical staining.

RESULTS

Of all 36 gastric carcinomas, mutations of the p53 gene were found in 7 cases (19.4%). These results from direct sequencing indicated that mutations consisted of five missence mutations, one silent mutation and one mutation within the splice donor site of intron 5. Mutations were found at codon 145 in exon 5 (1 case), intron 5 (1 case), codon 248 in exon 7 (1 case), codon 251 in exon 7 (2 cases), codon 285 in exon 8 (1 case) and codon 287 in exon 8 (1 case). The mutation hot spot at codon 251 in gastric cancer has not been observed previously. Over-expression of p53 oncoprotein was observed in 10 patients (27.8%) immunohistochemically.

CONCLUSIONS

p53 gene mutation might contribute to the pathogenesis of human gastric carcinoma. However, the suggestion awaits further investigation for confirmation.

Identification of a new CA dinucleotide repeat in the human factor VIII gene

We describe the identification of a new CA dinucleotide repeat marker for the diagnosis of haemophilia A carriers. The marker (CA-6) is present in intron 6 as a single copy 5 kb upstream of exon 7. Of 195 and 118 X chromosomes from normal individuals and haemophilia A patients, respectively, we observed three alleles of CA-6 with 12-14 repetitions [(CA)(12-14)]. The frequencies were 0.5% and 0% for (CA)(12), 99% and 95.8% for (CA)(13), and 0.5% and 4.2% for (CA)(14) in normals and patients respectively. We conclude that the low polymorphism of the CA-6 marker renders it less useful for the diagnosis of Chinese haemophilia A carriers.

Mice deficient in hepsin, a serine protease, exhibit normal embryogenesis and unchanged hepatocyte regeneration ability

Hepsin, a liver-enriched novel serine protease, has been implicated in participating with normal cell growth, embryogenesis, and blood coagulation pathway. To study its function in vivo, we have disrupted the mouse hepsin gene by homologous recombination. Targeted disruption of the hepsin gene and ablation of hepsin message were demonstrated by Southern blotting, Northern blotting and RT-PCR analysis. Homozygous hepsin -/- mice were viable, fertile, and exhibited no gross abnormalities, as judged by the size, weight and blood coagulation (PT) assays. However, the serum concentration of the bone form of alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase of the hepsin -/- mice was mildly elevated, in spite of no obvious pathological change of hepatocytes. To examine whether hepsin is involved in controlling cell growth in adult tissues, 70% hepatectomy was applied to the hepsin -/- mice. Liver regeneration proceeded normally in the hepsin -/- mice as judged by the liver mass restoration rate. These results suggest that loss of hepsin function causes no effect in cell growth and embryogenesis in vivo, which is in contradiction to the studies using in vitro cell culturing system. Moreover, gross mass regeneration of liver after damage proceeds normally in the absence of functional hepsin.

Chimaeric mice with disruption of the gene coding for phosphatidylinositol glycan class A (Pig-a) were defective in embryogenesis and spermatogenesis

Mutations in the gene encoding PIG-A (phosphatidylinositol glycan class A) are found in patients with paroxysmal nocturnal haemoglobinuria (PNH), an acquired haematopoietic stem cell disorder. Individuals with hereditary PIG-A mutations have never been identified, which is also manifested by the difficulties in generating Pig-a knockout (KO) mice. This study investigated the effect of Pig-a mutations on the development of visceral and genital organs in addition to the haematopoietic system by the generation of Pig-a KO chimaeric mice. Of a total of 54 live births out of 1684 blastocysts injected, chimaerism for Pig-a knockout was detected in 29 mice, suggesting the importance of Pig-a in embryogenesis and in live birth. Quantification of the degree of chimaerism in different organs of the surviving chimaeric mice revealed extremely low levels of Pig-a KO cells in the liver and spleen. In contrast, high levels of KO signals were usually detected in the brain, heart, lung and kidney. Haematopoiesis proceeded normally in these chimaeric mice (as measured by 'complete blood cell counting') and the Pig-a KO cells were present at low levels in red blood cells and B lymphocytes but at high levels in T lymphocytes, although these KO cells did not gain any growth advantage. The effect of Pig-a knockout was also prominent in the reproductive system, another organ with high mitotic activity. Breeding the male chimaeras revealed a high rate of infertility and abnormality in the male genital organs, including abnormally shaped testes, epididymis and seminal vesicles. Even in the absence of gross abnormalities of the genital organs, low counts of motile sperm were also discernible. Pig-a KO sperm was detected in these organs; however, no transmission of the KO allele was observed. The results suggest a possible mechanism underlying the non-transmission of the Pig-a KO gene in germlines.

The multiplicity of cardiotoxins from Naja naja atra (Taiwan cobra) venom

Four novel cardiotoxins were isolated from Naja naja atra (Taiwan cobra) venom by successive separation on a SP-Sephadex C-25 column and a reverse phase column. Amino acid sequences of the cardiotoxins were determined by Edman degradation and carboxypeptidase digestion. It shows that these cardiotoxins comprise 60 amino acid residues. Comparative analyses on the amino acid sequences of cardiotoxins from the venoms of N. naja atra and other Naja species indicated that amino acid substitutions of cardiotoxin isoforms frequently occurred at positions 7-11, 27-32 and 45-47. The hypervariable segments encoded by the second and third exon of cardiotoxin genes are located at or near the tips of loop structure of cardiotoxin molecules. These results, together with the suggestions that the residues at the tips of cardiotoxins' loop structure were involved in the manifestation of the biological activities of cardiotoxins, reflect that the preferential mutations may contribute to alterations in the function of cardiotoxin molecules. Analysis on the secondary structure of pre-mRNAs of N. naja atra cardiotoxin 4 gene and N. naja sputatrix cardiotoxin 3 gene has shown that the hypervariable regions of the exon 2 pertain to form intra-exon pairings and are not involved in the formation of intron-exon pairings. Since the pairings of splice sites and gene architecture were supposed to be associated with intron-exon recognition, it is likely that the preferred loci of mutations occurring with the evolution of cardiotoxin genes would not affect the processing of cardiotoxin precursors.

Increased frequency of angiotensin-converting enzyme DD genotype in patients with type 2 diabetes in Taiwan

BACKGROUND

Diabetes is one of the major causes of end-stage renal failure in the Taiwanese population. Previous studies have shown that angiotensin-converting enzyme (ACE) inhibitor can improve glucose utilization and suppress hepatic glucose production and the renin-angiotensin system may play an important role in the initiation and progression of diabetic nephropathy. Thus, ACE gene polymorphism may be associated with type 2 diabetes and diabetic nephropathy.

METHODS

To investigate the distribution of ACE-I/D genotype in type 2 diabetes and diabetic nephropathy, we examined 336 patients with type 2 diabetes (157 without nephropathy and 179 with nephropathy) and 263 age-matched normal controls. The diagnosis of nephropathy was made when daily protein loss exceeded 500 mg. ACE gene polymorphism was analysed by use of polymerase chain reaction.

RESULTS

Our study revealed that the frequency of the D allele of the ACE gene was 29.3% in normal controls. The frequency of ACE DD genotype was significantly higher in type 2 diabetics compared with normal controls (18.2 vs 9.1%, P<0.01). The frequency of ACE DD genotype in patients with diabetic nephropathy was significantly higher than in patients without nephropathy (22.3 vs 13.4%, P<0.05). To determine whether ACE gene polymorphism was associated with the severity of diabetic nephropathy, we divided patients with diabetic nephropathy into dialysis and non-dialysis groups. The frequency of ACE DD genotype in the dialysis group was significantly higher than in non-dialysis group (28.7 vs 15.3%, P<0.05).

CONCLUSION

Our results indicate that the frequency of ACE DD genotype is markedly higher in patients with type 2 diabetes, and the ACE DD genotype is significantly associated with diabetic nephropathy.

Atrophy and intestinal metaplasia one year after cure of H. pylori infection: a prospective, randomized study

BACKGROUND & AIMS

Helicobacter pylori-infected gastric mucosa evolves through stages of chronic gastritis, intestinal metaplasia (IM), glandular atrophy (GA), and dysplasia before carcinoma develops. We studied if H. pylori eradication would alter the course of premalignant histologic changes in the stomach.

METHODS

Volunteers from the Yantai County in China underwent upper endoscopy with biopsy specimens obtained from the antrum and corpus. H. pylori-infected subjects were randomized to receive either a 1-week course of omeprazole, amoxicillin, and clarithromycin (OAC) or placebo. At 1 year, endoscopies with biopsies were repeated.

RESULTS

A total of 587 H. pylori-infected subjects were randomized to OAC (n = 295) and placebo (n = 292). At 1 year, H. pylori was eradicated in 226 subjects assigned to OAC. In the placebo group, 245 patients remained H. pylori infected. Analysis of paired samples obtained from the same patients showed that acute and chronic gastritis decreased in both the antrum and corpus after H. pylori eradication (P<0.001) and activity of IM decreased in antrum (P = 0.014). In the H. pylori-infected group, antral biopsy specimens had more pronounced acute gastritis (P = 0.01), whereas corpus specimens showed increased acute and chronic gastritis (P<0.001) and a marginal increase in GA (P = 0.052). When histologic changes were compared between the 2 groups, decrease in acute and chronic gastritis was more frequent after H. pylori eradication (P<0.001) but changes in IM were similar. In the H. pylori-infected group, increase in GA was seen in the corpus (P = 0.01).

CONCLUSIONS

At 1 year, H. pylori eradication is beneficial in preventing progression of pathologic changes of the gastric mucosa.

Increased renal medullary endothelin-1 synthesis in prehypertensive DOCA- and salt-treated rats

To investigate the role of renal endothelin-1 (ET-1) synthesis in water-sodium homeostasis, we measured mRNA expressions, protein levels, enzyme activity, and receptor binding of the renal ET-1 system in a DOCA- and salt-treated rat model. Male Wistar rats were divided into control and DOCA- and salt-treated (DOCA-Salt) groups. The DOCA-Salt group received 25 mg/kg body wt DOCA and was maintained on 1% NaCl drinking water. Rats were killed on days 1, 2, 4, and 10 of the experiment. Urinary ET-1-like immunoreactivity significantly increased from the second day in the DOCA-Salt group and correlated well with the urinary sodium excretion rate (r = 0.81, P < 0.001). Renal endothelin-converting enzyme (ECE) activity, ET-1, and ECE-1 mRNA expressions were significantly increased in the renal medullary area of DOCA-Salt rats. In situ hybridization and immunohistochemical studies showed that the increase in ET-1 synthesis was mainly localized in the inner medullary collecting ducts. The maximum binding of endothelin B receptor also increased from the second day in the renal medulla of the DOCA-Salt group. Our results suggest that renal medullary synthesized ET-1 may be a natriuretic factor and may participate in the intrarenal regulation of water and salt homeostasis in prehypertensive DOCA-and salt-treated rats.

Expression and regulation of macrophage inflammatory protein-2 gene by vanadium in mouse macrophages

Environmental and occupational exposure to vanadium (V) dusts results in inflammation mainly confined to the respiratory tract. Macrophages apparently play an important role in mediating the inflammation via the production of many chemokines. In the current study, we investigated whether vanadium can regulate the gene expression of a CXC chemokine macrophage inflammatory protein-2 (MIP-2), and to determine the molecular mechanisms controlling MIP-2 gene expression. A mouse macrophage cell line RAW 264.7 was treated with sodium metavanadate (NaVO3) at the dose of 0.5, 5, or 10 microg/mi V. Northern blot analysis showed that induction of MIP-2 mRNA expression was in a dose-dependent manner. To define the time course of the inflammatory response, RAW 264.7 cells were exposed to 5 microg/ml V, MIP-2 mRNA in macrophages increased markedly as early as 1 h after treatment, maximally induced at 4 h and reduced to 2-fold above control levels by 6 and 8 h. The protein levels of MIP-2 in conditioned media, measured by enzyme-linked immunosorbent assay (ELISA), was well correlated with the levels of MIP-2 mRNA following all of the treatments in the study. In addition, the increase in MIP-2 mRNA expression by vanadium was attenuated by co-treatment with the antioxidant N-acetylcysteine (NAC), at the doses of 10 and 20 mM, suggesting that the induction of MIP-2 mRNA is mediated via the generation of reactive oxygen species (ROS). To further investigate transcriptional regulation of the MIP-2 gene expression by vanadium, we performed RNA decay assay by measuring the half-life of MIP-2 mRNA. Co-treatment of macrophages with the transcriptional inhibitor actinomycin D at 5 microg/ml following exposure to 5 microg/ml V for 4 h revealed complete stabilization of vanadium-induced MIP-2 mRNA and no sign of mRNA degradation, at least, for 6 h, in comparison to the half-life of MIP-2 mRNA was approximately 2.5 h by bacterial lipopolysaccharide (LPS) treatment, supporting post-transcriptional stabilization as the predominant role of MIP-2 gene expression. In conclusion, these observations demonstrate that in vitro vanadium can induce MIP-2 mRNA expression, mediating, at least in part, via the production of ROS. In addition, the increase in MIP-2 mRNA level involves, most likely, post-transcriptional control via increased mRNA stability.

Decreased GTPase activity of K-ras mutants deriving from human functional adrenocortical tumours

Our previous studies have shown that seven out of 15 patients with adrenocortical tumours contained K-ras gene mutation. In addition, the mutation type was a multiple-site mutation, and the hot spots were located at codons 15, 16, 18 and 31, which were different from those reported before (codons 12, 13 and 61). To understand whether the mutation hot spots in human adrenocortical tumours were associated with activation of K-Ras oncogene and the alterations of its biocharacteristics, mutant K-Ras genes were cloned from tumour tissues and then constructed with expression vector pBKCMV. Mutant K-Ras genes were expressed at high levels in Escherichia coli and the resultant K-Ras proteins were shown to be functional with respect to their well-known specific, high-affinity, GDP/GTP binding. The purified K-Ras protein from E. coli were then measured for their intrinsic GTPase activity and the GTPase activity in the presence of GTPase-activating protein for Ras. The results showed that the wild-type cellular K-Ras protein (p21BN) exhibits about ten times higher intrinsic GTPase activity than the activated protein (p21BM3) encoded by mutant K-Ras gene, which mutated at codon 60. With regards to the codon 15, 16, 18 and 31 mutant K-Ras proteins (p21BM2), the GTPase activity in the presence of GAP is much lower than that of the normal K-Ras protein, whereas the intrinsic GTPase activity is nearly the same as that of the normal K-Ras protein. These results indicated that mutations at these hot spots of K-Ras gene were indeed activated K-Ras oncogene in adrenocortical tumours; however, their association with tumors needs further experiments to prove.

Up-regulation of adrenal cortical and medullary atrial natriuretic peptide and gene expression in rats with deoxycorticosterone acetate-salt treatment

Our previous study demonstrated that human adrenal medulla is a site of atrial natriuretic peptide (ANP) synthesis. To further evaluate the role of adrenal ANP in body fluid homeostasis, we investigated the changes in adrenal ANP in rats receiving deoxycorticosterone acetate (DOCA)-salt treatment. In situ hybridization and immunohistochemical study showed that adrenal ANP messenger RNA (mRNA) and ANP-like immunoreactivities (ANP-LI) were mainly localized in the zona glomerulosa and medulla of vehicle-treated rats. DOCA-salt treatment activated ANP mRNA and peptide expression in all adrenal zones, especially in the zona fasciculata/reticularis from 12 h to the entire 8-day study period. Using a semiquantitative RT-PCR technique, the relative quantities of ANP mRNA in the adrenals of the DOCA-salt-treated group were significantly increased from 1 to 8 days, whereas the adrenal weights of DOCA-salt-treated rats were significantly decreased from day 2 to day 8. Our results are the first to indicate that ANP is synthesized not only in the adrenal medulla but also in the adrenal cortex and their syntheses are markedly increased in DOCA-salt-treated rats. These results imply that adrenal ANP may participate in the intraadrenal regulation of adrenal function on water-electrolyte homeostasis in an autocrine or paracrine manner.

Increased nitric oxide synthase mRNA expression in the renal medulla of water-deprived rats

Increased nitric oxide synthase mRNA expression in the renal medulla of water-deprived rats.

BACKGROUND

Experiments were performed to investigate whether renal nitric oxide synthase (NOS) mRNA and protein expression are responsive to the alteration of body volume.

METHODS

Four days of water deprivation (WD) was initiated in 16 male Wistar rats, and 16 normal rats (NC) served as the control group. Neuronal NOS (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS) mRNAs and immunoreactivity were measured by reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot hybridization and immunohistochemistry, respectively. Plasma angiotensin II, vasopressin, and atrial natriuretic peptide (ANP) concentrations were measured by radioimmunoassay.

RESULTS

The four-day WD increased plasma sodium and osmolality levels, but severely decreased daily urine sodium excretion and urine volume. Plasma angiotensin II and vasopressin concentrations were increased, but the plasma ANP level was significantly decreased in WD rats. nNOS, eNOS, and iNOS mRNA levels were increased by 5.2-, 3.3-, and 3. 4-fold in the outer medulla and 1.7-, 1.5-, and 1.8-fold in the inner medulla, whereas no significant difference was found in the renal cortex of WD rats as compared with NC rats. Additionally, immunohistochemistry revealed that the immunostaining intensity of nNOS, eNOS, and iNOS was clearly enhanced in the medullary thick ascending limb, proximal straight tubule, inner medullary collecting duct, and proximal convoluted tubule in WD rats. Kidney angiotensin II content as well as renin mRNA levels in renal cortex, outer medulla, and inner medulla in WD rats were apparently increased.

CONCLUSIONS

Our results indicate that the increases of nNOS, eNOS, and iNOS synthesis in the kidney, particularly in the renal medulla, may have a role in the adaptation of renal function to volume depletion in the face of an increase of systemic and intrarenal vasoconstrictive substances.

The influence of age at onset and gender on the HLA-DQA1, DQB1 association in Chinese children with insulin dependent diabetes mellitus

Certain alleles of human leukocyte antigen (HLA)-DR and -DQ genes have been strongly associated with susceptibility and resistance to insulin- dependent diabetes mellitus (IDDM). To further clarify the association of HLA DQ alleles with IDDM and the influence of age at onset and gender on the association with IDDM, we investigated the association of HLA-DQA1, -DQB1 in 54 childhood onset Chinese (21 male) IDDM patients and 65 normal controls by using polymerase chain reaction-sequence specific primer (PCR-SSP). The mean age plus or minus SD at onset of IDDM patients was 8.37+/-3.54 year old. Our results revealed that the frequencies of DQA1 *0301, *0302, DQB1 *0201, and *0302 in IDDM patients were significantly higher than that in the control group (p < 0.025, < 0.005, < 0.001, and < 0.001, respectively). The frequency of DQA1 *0301, *0302, DQB1 *0201, and *0302 were susceptible alleles to IDDM with relative risks of 2.0, 3.5, 5.0 and 4.3, respectively. The protective alleles to IDDM were DQA1 *0101, *0103, DQB1 *0301, *0503, and *0602. We divided IDDM patients into three groups according to age at onset (1-5, 6-10, and 11-15 years old). The frequency of DQA1 *0302 decreased as age increased, and the frequency of DQA1 *0501 increased as age increased. Our results also showed that male IDDM patients had higher frequencies of DQA *0501, DQB1 *0201 than female IDDM patients (p < 0.025 and < 0.025, respectively), while female IDDM patients had higher frequencies of DQB1 *0502 than male IDDM patients (p < 0.05). In our study significant susceptibility haplotypes to IDDM were DQA1 *0301-DQB1 *0302, DQA1 *0501-DQB1 *0201, DQA1 *0301-DQB1 *0201, and DQA *0302-DQB1 *0201.

Determination of urinary arsenic, mercury, and selenium in steel production workers

The fumes and dust of trace elements and their compounds are very toxic and have been related to an increase in the incidence of diseases. Occupational exposure to toxic metals and metalloids can be determined by means of workplace air measurements and biological monitoring. The aim of our investigation was to determine the concentrations of As, Hg, and Se in urine samples under routine clinical laboratory conditions. To assess the reliability of these methods, critical factors such as detection limit(s), calibration range(s), cost, accuracy, and precision were studied. The method was employed for the quantitative determination of arsenic, mercury, and selenium in urine samples from steel production and quality control workers and healthy unexposed controls. After pretreatment with acids, the samples were digested by means of a microwave oven. Arsenic was determined by hydride atomic absorption spectrometry and mercury was determined by cold vapor atomic absorption spectrometry, whereas selenium was determined by a graphite furnace atomic absorption spectrometry. The results indicate those urinary arsenic, mercury, and selenium levels of the exposed workers are significantly higher than those of the controls. The possibility that these elements are involved in the etiology of diseases is discussed and recommendations are made to improve workplace ventilation and industrial hygiene practices.

Chromosome 11q13 and atopic asthma

Asthma is a complex syndrome in which bronchial inflammation and smooth muscle hyperactivity lead to labile airflow obstruction. The commonest form of asthma is that due to atopy, which is an immune disorder where production of IgE to inhaled antigens leads to bronchial mucosal inflammation. The ultimate origins of asthma are interactive environmental and genetic factors. The genetics is acknowledged to be heterogeneous, and one chromosomal region of interest and controversy has been 11q13. To clarify the nature of the chromosome 11q13 effect in atopy and asthma, we conducted a genetic association study in subjects with marked atopic asthma and matched controls, which incorporated the study of 13 genetic variants over a distance of 10-12 cM and which took account of detailed immune and clinical phenotyping. Association with high IgE levels was limited to the interval flanked by D11S1335 and CD20 in a 0.8-Mb interval and was greatest for variants of Fc epsilonRIbeta and HTm4; these variants also associated with asthma (recurrent wheeze with labile airflow obstruction and need for regular inhaler treatment). At the more telomeric marker, D11S480, variants associated with asthma, but not with high IgE levels. The data might support the possibility of multiple loci relevant to atopic asthma on chromosome 11q13.

Mutational spectrum of p53 gene in arsenic-related skin cancers from the blackfoot disease endemic area of Taiwan

To understand the role of p53 tumour suppressor gene in the carcinogenesis of arsenic-related skin cancers from the blackfoot disease endemic area of Taiwan, we collected tumour samples from 23 patients with Bowen's disease, seven patients with basal cell carcinomas (BCC) and nine patients with squamous cell carcinomas (SCC). The result showed that p53 gene mutations were found in 39% of cases with Bowen's disease (9/23), 28.6% of cases with BCC (2/7) and 55.6% of cases with SCC (5/9). Most of the mutation sites were located on exon 5 and exon 8. Moreover, the results from direct sequencing indicated that missense mutations were found at codon 149 (C-->T) in one case, codon 175 (G-->A) in three cases, codon 273 (G-->C) in three cases, codon 292 (T-->A) in one case, codon 283 (G-->T) in one case, codon 172 (T-->C) in one case and codon 284 (C-->A) in one case. In addition, silent mutations were also found in four cases. These mutations were located at codons 174, 253, 289 and 298 respectively. In immunohistochemistry analysis, p53 overexpression was found in 43.5% (10/23) of cases with Bowen's disease, 14% (1/7) of cases with BCC and 44% (4/9) of cases with SSC. These findings showed that p53 gene mutation rate in arsenic-related skin cancers from the blackfoot disease endemic area of Taiwan is high and that the mutation types are different from those in UV-induced skin cancers.

Fungal keratitis caused by Candida utilis--case report

We report the first case of an ocular fungal infection caused by Candida utilis in a 72-year-old woman. Although candidiasis is the most common opportunistic fungal infection in humans, C. utilis had not been associated with human morbidity until two cases of fungemia were reported in 1988 and 1993. The clinical features exhibited typical feather-like infiltration at the ulceration margin of this case. After treatment with topical fluconazole and amphotericin-B, the ulceration healed within 3 weeks. The patient underwent penetrating keratoplasty and regained useful vision. We concluded that C. utilis is a new corneal pathogen and should be included in the differential list of mycotic keratitis.

Seroepidemiologic survey for hepatitis B virus infection in Taiwan: the effect of hepatitis B mass immunization

A hepatitis B mass immunization program was launched in Taiwan in July 1984, beginning with newborns of hepatitis B carrier mothers for the first 2 years of the program, which was then extended to all newborns. Seroepidemiology was studied in 3 cohorts at age 6 years. Each cohort consisted of 1500 children proportionally and randomly sampled from those entering elementary school in 1989, 1991, and 1993, representing those born 1 year before the program began and years 1 and 3 of the program, respectively. By RIA, the hepatitis B surface antigen positivity rates in the groups were 10.5%, 6.3%, and 1.7%, respectively; hepatitis B surface antibody positivity rates were 36.9%, 62.0%, 65.4%; and hepatitis B infection rates were 25.0%, 15.9%, 4.3%. Thus, universal immunization was more effective in reducing hepatitis B carriage than selective immunization of newborns of carrier mothers only. The program has proved effective in controlling chronic hepatitis B infection in Taiwan.

Stability of self-prepared fortified antibiotic eyedrops

Self-prepared fortified antibiotic eye drops are essential for the severe ocular infection. The relation of potency decay and storage conditions including temperature, concentration and duration were studied by the changes of MIC. 1% and 10% amikin, 10% and 50% pipril, and 5% and 25% vancomycin were diluted from the prarenteral antibiotics with the 5% glucose and storage at 4, -18 and -80 degrees C for 3, 7, 14 and 28 days. MICs of amikin against Pseudomonas aeruginosa, pipril and vancomycin against Staphylococcus aureus were determined by the agar diffusion method. Fluctuations of the MIC were noted during the observation period. Most of the significant changes of MIC were found during the first 7 days. When the potencies between time of zero and 28 days are compared, only 10% pipril and 25% vancomycin stored at -80 degrees C had significant change. Our conclusion is that all of the fortified antibiotic eye drops in this study can be stored in the house refrigerator or freezer for up to 28 days. High concentration may show a negative result of the preservation. Temperature does not influence the preservative effect within four weeks' observation.

Disulfide isomers of alpha-neurotoxins from King cobra (Ophiophagus hannah) venom

Two novel alpha-neurotoxins, Oh-6A and Oh-6B, isolated from the king cobra (Ophiophagus hannah) venom, consist of 70 amino acid residues with 10 cysteine residues and share the same amino acid sequences as determined by Edman degradation on the peptide fragments generated from the proteolytic hydrolysates. Their sequences share 46-53% homology with Oh-4, Oh-5, Toxin a, and Toxin b from the same venom. The finding that Oh-6A and Oh-6B had different retention times in the reversed-phase column suggested that the two toxin molecules should not have the same conformation. Selective reduction on the disulfide bond, Cys26--Cys30, at the tip of their loop II structures resulted in the production of the partially reduced derivatives eluted at the same position. Under redox conditions, the partially reduced Oh-6A and 6B exclusively converted into native Oh-6A as evidenced by HPLC analyses. This suggests that Oh-6A and Oh-6B are disulfide isomers which probably arise from cis-trans isomerization of the Cys26--Cys30 disulfide bond. Alternatively, the two toxins exhibited binding activity toward nAChR and lethal toxicity equally. It reflects that the diversity around the extra loop at the loop II structure does not exert a significant effect on the manifestation of the neurotoxicity of Oh-6A and Oh-6B.

The hemodynamic changes of gastroduodenal regional blood flow after Helicobacter pylori eradication in patients with duodenal ulcer scar

Duodenal ulcer (DU) is frequently accompanied by Helicobacter pylori (Hp) infection and associated with the imbalance of aggressive factors and defensive factors. To investigate the possible relationship between Hp and regional gastric blood flow, 26 endoscopically proved DU (scar stage) and Hp infection patients were included and received triple therapy (colloid bismuth subcitrate 120 mg qid for 4 weeks, amoxicillin 500 mg qid for 2 weeks and metronidazole 250 mg tid for 2 weeks). Regional gastroduodenal blood flow (RGDF) was measured at DU scar area and antrum lesser curvature site by laser Doppler flowmetry during endoscopic examination, before and one month after triple therapy. In 22 patients with Hp eradication the RGDF was significantly elevated at antrum lesser site after triple therapy (p < 0.05) but there was no difference at DU scar area. However, in 4 patients without Hp eradication no difference of RGDF in these two points was found. Therefore, Hp appears to have direct effects on gastric microcirculation.

Characterization and cloning of long neurotoxin homolog from Naja naja atra

The cDNA encoding a long neurotoxin homolog was constructed from the cellular RNA isolated fom the venom glands of Naja naja atra (Taiwan cobra) by reverse transcription-polymerase chain reaction. BLAST searches for sequence similarity in the GenBank databases reveal that the cDNA sequence of the long neurotoxin homolog is not highly homologous with long and short neurotoxins. Although the long neurotoxin homolog exhibited an activity to inhibit acetylcholine-induced muscle contractions as Naja naja atra cobrotoxin, the degree of inhibition caused by the addition of long neurotoxin homolog was only approximately 35% of that observed with the addition of cobrotoxin. Moreover, the primary structure of the long neurotoxin homolog did not fulfill the characteristic features of long or short neurotoxins. Together with long neurotoxin homologs from other snake species, they probably represent an evolutionary divergence between long and short neurotoxins.

Identification of arg-30 as the essential residue for the enzymatic activity of Taiwan cobra phospholipase A2

Taiwan cobra (Naja naja atra) phospholipase A2 (PLA2) was inactivated by arginine-specific reagents, phenylglyoxal and 1, 2-cyclohexanedione. Kinetic analyses of the modification reaction revealed that the inactivation of PLA2 followed pseudo-first-order kinetics and the loss of activity was correlated with the incorporation of one molecule of modification reagent per PLA2 molecule. This was confirmed by the results of amino acid composition determination, that showed that a marked decrease in enzymatic activity was associated with the modification of one arginine residue. Tryptic cleavage of the modified protein and microsequencing revealed that Arg-30 was the functionally essential residue. The incorporation of a modifier into the PLA2 did not significantly affect the secondary structure of the enzyme, as revealed by the CD spectrum, and Ca2+-binding of the modified PLA2 was unaffected. Nevertheless, the nonpolarity of the active site of PLA2 markedly decreased with the arginine modification, as evidenced by the decreases in the enhancement of Trp and 8-anilinonaphthalene sulfonate fluorescence. These results, together with those of X-ray crystallographic analysis of N. naja atra PLA2 [Scott et al. (1990) Science 250, 1541-1546], demonstrate that Arg-30 is one of the residues involved in the interfacial binding of a PLA2 molecule with its substrate.

Human ARHGDIG, a GDP-dissociation inhibitor for Rho proteins: genomic structure, sequence, expression analysis, and mapping to chromosome 16p13.3

GDP-dissociation inhibitors (GDIs) play a primary role in modulating the activity of GTPases. We recently reported the identification of a new GDI for the Rho-related GTPases named RhoGDIgamma. This gene is now designated ARHGDIG by HUGO. Here, in a detailed analysis of tissue expression of ARHGDIG, we observe high levels in the entire brain, with regional variations. The mRNA is also present at high levels in kidney and pancreas and at moderate levels in spinal cord, stomach, and pituitary gland. In other tissues examined, the mRNA levels are very low (lung, trachea, small intestine, colon, placenta) or undetectable. RT-PCR analysis of total RNA isolated from exocrine pancreas and islets shows that the gene is expressed in both tissues. We also report the genomic structure of ARHGDIG. The gene spans over 4 kb and is organized into six exons and five introns. The upstream region lacks a canonical TATA box and contains several putative binding sites for ubiquitous and tissue-specific factors active in central nervous system development. Using FISH, we have mapped the gene to chromosome band 16p13.3. This band is rich in deletion mutants of genes involved in several human diseases, notably polycystic kidney disease, alpha-thalassemia, tuberous sclerosis, mental retardation, and cancer. The promoter structure and the chromosomal location of RhoGDIgamma suggest its importance and underscore the need for further investigation into its biology.