Genetically encoded fluorescent sensors of membrane potential

Imaging activity of neurons in intact brain tissue was conceived several decades ago and, after many years of development, voltage-sensitive dyes now offer the highest spatial and temporal resolution for imaging neuronal functions in the living brain. Further progress in this field is expected from the emergent development of genetically encoded fluorescent sensors of membrane potential. These fluorescent protein (FP) voltage sensors overcome the drawbacks of organic voltage sensitive dyes such as non-specificity of cell staining and the low accessibility of the dye to some cell types. In a transgenic animal, a genetically encoded sensor could in principle be expressed specifically in any cell type and would have the advantage of staining only the cell population determined by the specificity of the promoter used to drive expression. Here we critically review the current status of these developments.

Helicobacter pylori eradication induces marked increase in H+/K+-adenosine triphosphatase expression without altering parietal cell number in human gastric mucosa

BACKGROUND AND AIMS

Gastric acid secretion is downregulated by Helicobacter pylori infection and upregulated after its eradication, but the mechanisms are still unclear. We examined the effects of H pylori eradication on the number of parietal cells and on expression of molecules functioning in acid secretion in the human gastric mucosa.

METHODS

We enrolled 111 consecutive men with chronic gastritis induced by H pylori. Biopsy specimens were endoscopically obtained before and 12 weeks after successful eradication of H pylori and parietal cell numbers were counted. mRNA expression levels of H+/K+-adenosine triphosphatase (H+/K+-ATPase), anion exchanger 2, M3 muscarinic receptor, intrinsic factor, and interleukin 1beta were determined with a real time reverse transcriptase-polymerase chain reaction method. The severity of gastric atrophy was evaluated using the serum pepsinogen I/II ratio.

RESULTS

No significant difference was observed in parietal cell numbers before and after H pylori eradication. Median mRNA expression levels of H+/K+-ATPase in the gastric mucosa increased 250-fold after H pylori eradication accompanied by attenuation of interleukin 1beta. A large increase in H+/K+-ATPase expression was observed even in patients with severe atrophic gastritis. In contrast, fold increases in mRNA expression levels, including intrinsic factor, anion exchanger 2, and M3 muscarinic receptor, after eradication therapy, were limited to 1.4, 2.3, and 2.5 times, respectively.

CONCLUSIONS

In the absence of alteration of parietal cell number, gastric H+/K+-ATPase mRNA expression was markedly restored after successful H pylori eradication, suggesting a central role for the restoration of H+/K+-ATPase expression in gastric acid secretion recovery after H pylori eradication.

Histamine-2 receptor expression in gastric mucosa before and after Helicobacter pylori cure

BACKGROUND

Helicobacter pylori infection prevents the occurrence of the tolerance phenomenon of Histamine-2 (H2) receptor antagonists. Gastro-esophageal reflux disease develops in some cases with the restoration of acid secretion after H. pylori eradication therapy.

AIM

To clarify the mechanisms of H2 receptor restoration after the eradication of H. pylori on parietal cells.

METHODS

We enrolled 80 consecutive asymptomatic male patients with H. pylori infection, having chronic gastritis with or without the presence of peptic ulcers. Biopsy specimens from the greater curvatures at the mid-corpus of the stomach were obtained endoscopically from all subjects before and 12 weeks after the eradication of H. pylori. Degrees of gastric atrophy were evaluated by serum pepsinogen levels. The amounts of mRNA expression of H2 receptor were evaluated in each subject's gastric mucosa by real time reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

H2 receptor mRNA expression levels significantly correlated with serum pepsinogens I and II ratios. The expression level of H2 receptor mRNA was lower in subjects with hypergastrinemia. The median expression level of H2 receptor after H. pylori eradication was threefold greater than prior to treatment. In addition, its restoration became more pronounced in subjects with severe gastric atrophy. However, a comparatively low restoration of H2 receptor mRNA was found in subjects with hypergastrinemia.

CONCLUSIONS

H2 receptor mRNA levels decrease with the progression of gastric atrophy induced by H. pylori infection, and are restored after H. pylori eradication. Such expression levels of H2 receptor may explain a part of the tolerance phenomenon to H2 receptor antagonists.

Pericryptal fibroblast sheath in intestinal metaplasia and gastric carcinoma

BACKGROUND AND AIMS

In the progression of chronic gastritis, gastric mucosal cells deviate from the normal pathway of gastric differentiation to an intestinal phenotype which is closely related to gastric carcinoma. However, to date, it has not been elucidated whether the intestinal metaplasia is merely a change in the epithelium or whether the underlying mesenchyme also changes from gastric type to intestinal type. We have investigated the relationship between intestinal metaplasia and the pericryptal fibroblast sheath (PCFS) in the mesenchyme. In addition, we also examined PCFS in gastric carcinoma.

METHODS

We determined the existence of PCFS in the intestinal metaplastic mucosa and carcinoma of both human and Cdx2 transgenic mouse stomach. PCFS was determined using the antibody against alpha-smooth muscle actin and electron microscopic observations.

RESULTS

PCFS formed an almost complete layer around the small and large intestinal crypts while it did not exist around the normal gastric glands in both mice and humans. PCFS was seen around the glands of intestinal metaplastic mucosa in both Cdx2 transgenic mouse and human stomachs. However, PCFS was virtually absent in the intestinal-type gastric adenocarcinoma area.

CONCLUSION

We successfully demonstrated that the epithelium as well as the mesenchyme changed from the gastric type to the intestinal type in intestinal metaplasia and that PCFS disappeared in intestinal-type gastric carcinoma.

Cdx1 induced intestinal metaplasia in the transgenic mouse stomach: comparative study with Cdx2 transgenic mice

BACKGROUND AND AIMS

Gastric intestinal metaplasia, which is mainly induced by Helicobacter pylori infection, is thought to be a precancerous lesion of gastric adenocarcinoma. Intestinal metaplastic mucosa expresses intestine specific homeobox genes, Cdx1 and Cdx2, in the human gastric mucosa. We and others have reported that ectopic expression of Cdx2 in the gastric epithelium generates intestinal metaplasia in the transgenic mouse model.

METHODS

To clarify the differences in the roles of Cdx1 and Cdx2 in intestinal metaplasia, we generated transgenic mice expressing Cdx1 in the gastric mucosa and compared Cdx1 induced gastric mucosal morphological changes with Cdx2 induced intestinal metaplasia.

RESULTS

The gastric mucosa in Cdx1 transgenic mice was completely replaced by intestinal metaplastic mucosa, consisting of all four intestinal epithelial cell types: absorptive enterocytes, goblet, enteroendocrine, and Paneth cells. Paneth cells, which were not recognised in Cdx2 transgenic mice, were in the upper portion of the intestinal metaplastic mucosa. Pseudopyloric gland metaplasia, which was induced in Cdx2 transgenic mice, was not recognised in Cdx1 transgenic mice. Proliferating cell nuclear antigen (PCNA) positive cells were diffusely scattered in Cdx1 induced intestinal metaplastic mucosa while PCNA positive cells in Cdx2 induced intestinal metaplastic mucosa were in the base of the metaplastic mucosa. Intestinal metaplastic mucosa of Cdx1 transgenic mouse stomach was significantly thicker than that of wild-type or Cdx2 transgenic mouse stomach.

CONCLUSIONS

We have confirmed that Cdx1 induced gastric intestinal metaplasia but that it differed from Cdx2 induced intestinal metaplasia in differentiation, structure, and proliferation.

Functional topology of the mossy fibre-granule cell--Purkinje cell system revealed by imaging of intrinsic fluorescence in mouse cerebellum

We report an activity-induced green fluorescence signal observed when mouse cerebellar slices were illuminated with blue light and parallel fibre-Purkinje cell synapses were activated. The optical signal consisted of an initial increase in fluorescence that peaked within 1-2 s after the onset of stimulation, followed by a long lasting (40 s) transient decrease in fluorescence. Single or tetanic electrical stimuli applied to the molecular layer elicited 'beam-shaped' fluorescence changes along the trajectory of parallel fibres. These signals reported activation of Purkinje cells as they were depressed by antagonists of ionotropic and metabotropic glutamate receptors at Purkinje cells and correlated with Purkinje cell spiking activity. Optical responses induced by direct pharmacological activation of glutamate receptors were reduced by a calcium-free extracellular medium, consistent with the hypothesis that they reflect metabolic activity due to an increased intracellular calcium load associated with neuronal activation. We used these intrinsic fluorescence signals to address the question of whether granule cells excite Purkinje cells only locally via the ascending branches of their axons, or more widespread along the parallel fibre trajectory. White matter stimulation of the mossy fibres also elicited a beam-like fluorescence change along the trajectory of parallel fibres. Simultaneous imaging and extracellular recording demonstrated the association between the beam-like fluorescence signal and Purkinje cell spiking. This non-invasive imaging technique supports the notion that parallel fibre activity, evoked either locally or through the mossy fibre-granule cell pathway, can activate postsynaptic Purkinje cells along more than 3 mm of the parallel fibre trajectory.

L-type Ca 2+ channel and Ca 2+ -permeable nonselective cation channel as a Ca 2+ conducting pathway in myocytes isolated from the cricket lateral oviduct

The Ca2+-conducting pathway of myocytes isolated from the cricket lateral oviduct was investigated by means of the whole-cell patch clamp technique. In voltage-clamp configuration, two types of whole cell inward currents were identified. One was voltage-dependent, initially activated at -40 mV and reaching a maximum at 10 mV with the use of 140 mM Cs2+-aspartate in the patch pipette and normal saline in the bath solution. Replacement of the external Ca2+ with Ba2+ slowed the current decay. Increasing the external Ca2+ or Ba2+ concentration increased the amplitude of the inward current and the current-voltage (I-V) relationship was shifted as expected from a screening effect on negative surface charges. The inward current could be carried by Na+ in the absence of extracellular Ca2+. Current carried by Na+ (INa) was almost completely blocked by the dihydropyridine Ca2+ channel antagonist, nifedipine, suggesting that the INa is through voltage-dependent L-type Ca2+ channels. The other inward current is voltage-independent and its I-V relationship was linear between -100 mV to 0 mV with a slight inward rectification at more hyperpolarizing membrane potentials when 140 mM Cs+-aspartate and 140 mM Na+-gluconate were used in the patch pipette and in the bath solution, respectively. A similar current was observed even when the external Na+ was replaced with an equimolar amount of K+ or Cs+, or 50 mM Ca2+ or Ba2+. When the osmolarity of the bath solution was reduced by removing mannitol from the bath solution, the inward current became larger at negative potentials. The I-V relationship for the current evoked by the hypotonic solution also showed a linear relationship between -100 mV to 0 mV. Bath application of Gd3+ (10 microM) decreased the inward current activated by membrane hyperpolarization. These results clearly indicate that the majority of current activated by a membrane hyperpolarization is through a stretch-activated Ca2+-permeable nonselective cation channel (NSCC). Here, for the first time, we have identified voltage-dependent L-type Ca2+ channel and stretch-activated Ca2+-permeable NSCCs from enzymatically isolated muscle cells of the cricket using the whole-cell patch clamp recording technique.

An efficient linkage analysis strategy for autosomal dominant polycystic kidney disease

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common inherited renal disorders in the world. Mutations in PKD1 are responsible for 80-95% of all autosomal dominant polycystic kidney disease (ADPKD). Although the need for linkage analysis of ADPKD is decreasing after the success of mutation detection at whole exons of PKD1, linkage analysis still has some advantages in detecting non-PKD1 families, thereby avoiding hopeless mutation analysis.

METHODS

We evaluated ten microsatellite markers beside or inside PKD1 on chromosome 16p. Allele frequency and heterozygosity of each marker were calculated based on the 100 genotypes obtained from 50 normal Japanese. Automated microsatellite genotyping using ABI Prism 377 and GeneScan software was applied. Markers were mapped using radiation hybrid mapping. Finally, this strategy was applied in the linkage analysis of 6 independent Japanese ADPKD families.

RESULTS

D16S3024, D16S3082, D16S3027 and D16S423 showed high heterozygosity (> 0.80) in a normal Japanese population and sufficient proximity to the PKD1 gene for linkage analysis. We could successfully analyze 144 genotypes within 7 hours. This strategy produced theoretically near-maximum LOD scores in 4 independent Japanese families inheriting ADPKD.

CONCLUSIONS

Automated genotyping using microsatellite markers, D16S3024, D16S3082, D16S3027 and D16S423 are very useful in the linkage analysis of ADPKD.

Change in apoptosis in the gastric surface epithelium and glands after eradication of Helicobacter pylori

BACKGROUND

Change in apoptosis in gastric glands after eradication of Helicobacter pylori has never been reported.

AIMS

The purpose of this paper is to investigate the change in apoptosis in gastric glands after eradication of Heliobacter pylori.

PATIENTS AND METHODS

We studied 23 Heliobacter pylori-positive patients with duodenal and gastric ulcers, who were monitored for 6-12 months after eradication, and eight controls. Biopsies were taken from the antrum and body. Apoptosis was evaluated immunohistochemically using anti-single stranded DNA antibody. Apoptotic index was calculated by counting immunostained cells in surface epithelial and glandular cells.

RESULTS

In the surface epithelium, Apoptotic indexes were significantly higher in patients than in controls. In the upper portion of fundic glands, apoptotic indexes were significantly higher in patients with gastric ulcers (14.2% (9.3, 17.8)) (median (1st quartile, 3rd quartile)) than in controls (8.0% (2.0, 9.0), p < 0.01) and decreased significantly after eradication (3.4% (2.0, 5.3)), p < 0.01). In pyloric glands, apoptotic indexes were no different between patients and controls. In the lower portion of fundic glands, apoptotic indexes were very low, both in patients and in controls.

CONCLUSIONS

Our results showed that apoptosis, not only of surface epithelial cells but also of glandular cells in the upper portion of fundic glands, increased in Heliobacter pylori-positive patients with gastric ulcers and decreased to normal levels after eradication of Heliobacter pylori.

Association between nasal allergy and a coding variant of the Fc epsilon RI beta gene Glu237Gly in a Japanese population

The gene for the beta-chain of the high-affinity receptor for IgE (Fc epsilon RI beta) has been proposed as a candidate gene for atopy. A coding variant Glu237Gly has been studied in various populations with asthma and atopy, and the results were controversial for association of the variant with atopy/asthma. Because nasal allergy is a more common atopic disease and shows less remission than asthma, we analyzed whether the Glu237Gly variant is correlated with nasal allergy. The study enrolled 233 patients with nasal allergy and 100 control subjects. Further, three subgroups were selected: patients with perennial nasal allergy (n=149), Japanese cedar pollinosis (n=189), and allergy to multiple allergens (n=45). The allele frequency of Gly237 in the controls and patients was 0.14 and 0.20, and the frequency of Gly237-positive subjects was 0.23 and 0.356, respectively. There was a significant association between Gly237-positivity and nasal allergy, perennial nasal allergy, Japanese cedar pollinosis, and allergy to multiple allergens. Among all 333 subjects we observed a significant relationship between Gly237 and elevated levels of serum total IgE (>250 IU/ml) and very high IgE (>1000 IU/ml). Among patients positive for a specific IgE, Gly237 was significantly associated with high IgE for house dust, mite, and Japanese cedar pollen. These results suggest that the Glu237Gly variant of the Fc epsilon RI beta gene is involved in the development of nasal allergy through the process for the production of both specific and nonspecific IgE antibodies.

Analysis of the p53 gene in parotid gland cancers: a relatively high frequency of mutations in low-grade mucoepidermoid carcinomas

Mutations and overexpression of the p53 gene and protein were analyzed in 40 cases with various types of parotid gland cancers. Mutations were found in 12 cases (30%), and low-grade mucoepidermoid carcinomas (43%) and highly malignant carcinomas including adenocarcinoma, salivary duct carcinoma, and undifferentiated carcinoma (56%) showed a relatively high frequency of mutations. Overexpression of the protein was observed in 11 cases (28%) and 4 of the 11 cases also had p53 mutations. These results suggest that mutations of the p53 gene have significance in certain types of parotid cancers irrespective of the aggressiveness of a tumor type.

p53 expression in the gastric mucosa before and after eradication of Helicobacter pylori

BACKGROUND

Accumulation of p53 has been recognized in the gastric mucosa infected with Helicobacter pylori. We investigated the prevalence of p53-positive cells in the gastric mucosa before and one month after eradication of H. pylori and the relationship between p53 positivity and inflammation and cell proliferation.

METHODS

The subjects included 24 H. pylori-positive patients. They achieved eradication one month after anti-H. pylori therapy. Biopsies were taken from the greater curvatures of the antrum and middle body. H. pylori status was assessed using culture and tissue section (Giemsa stain). Serial sections were used for examination of gastritis (hematoxylin and eosin stain) and for immunostaining of p53, Ki-67 and myeloperoxidase (MPO). p53 index and Ki-67 labeling index (LI) were calculated by counting p53-positive and Ki-67-positive cells in the entire gastric pits longitudinally sectioned and expressing them as a percentage of the total cells in a gastric pit. In the neck regions with and without p53-positive cells, polymorphonuclear leukocytes (PMNs) were counted in the corresponding area (/50 x 50 microm2) of the sections stained both with p53 and MPO.

RESULTS

p53-positive cells decreased significantly after eradication of H. pylori. Before eradication, the number of PMNs was significantly higher in the neck regions with p53-positive cells than in those without.

CONCLUSIONS

In the gastric mucosa infected with H. pylori, p53-positive cells were found in the neck region infiltrated with PMNs. p53 expression decreased significantly one month after eradication of H. pylori.

A missense mutation, A156T, in the alpha-galactosidase A gene causes typical Fabry disease

AIMS

Fabry disease is a rare but important cause of end-stage renal disease. Recent molecular investigations on alpha-galactosidase A (alpha-Gal A) have proven the existence of atypical variants in Fabry disease, making genotype assessment of each phenotype indispensable. We report here a missense mutation, which causes a typical form of Fabry disease.

MATERIAL AND METHODS

The proband, a 45-year-old man, presented with acroparesthesias, hypohidrosis, left ventricular hypertrophy, renal involvement (proteinuria and renal insufficiency) with typical microscopic findings and extremely reduced plasma alpha-Gal A activity, indicating the typical form of the disease. Total RNA was isolated from the proband's cultured fibroblasts, reverse-transcribed and amplified for direct sequencing of alpha-Gal A. Genomic DNA of the proband's mother and 75 controls (50 males and 25 females) living in the same area as the proband was also examined.

RESULTS

Sequencing of the cDNA revealed a substitution of G to A in codon 156 of alpha-Gal A, resulting in a single amino acid change from alanine to threonine (A156T). The mutation can be detected with PCR-RFLP with SfaNI digestion. This technique revealed that the mother was a heterozygote of A156T with no A156T noted in the 100 haplotypes of the controls. With a vigorous search of the same mutation in the literature, no previous description was found other than one case listed in several review papers as a classic phenotype without any other information. In our study, we examined A156T in a pedigree and demonstrated that the mutation was not a polymorphic variant in our area.

CONCLUSION

Taken together, the present results strongly suggest that the missense mutation, A156T, in the alpha-Gal A gene causes typical Fabry disease.

Effect of ACE gene polymorphism on age at renal death in polycystic kidney disease in Japan

Polycystic kidney disease (PKD) is one of the most common genetic disorders and a major cause of renal death or end-stage renal disease (ESRD) requiring regular hemodialysis. The responsible genes recently have been cloned; however, genetic factors influencing the rate of progression to ESRD in patients with PKD have yet to be defined. Several studies have shown increased activity of the renin-angiotensin system (RAS) in patients with PKD. In addition, genetic polymorphisms of the RAS have been associated with the development of cardiovascular diseases. Therefore, these polymorphisms are good candidates for disease-modifying genetic factors or markers in PKD. In two previous reports of white subjects with a cumulative survival analysis, it was suggested that patients with P:KD1 homozygous for the deletion allele of the angiotensin-converting enzyme (ACE) gene are at increased risk for early renal death. To confirm this hypothesis in Japanese subjects, 103 individuals with PKD were genotyped for several components of the RAS, ie, ACE insertion/deletion (I/D) polymorphism, angiotensinogen (AGT) M235T, and angiotensin II type 1 receptor (AT1) A1166C. Seventy-six of the 103 patients (73.8%) reached ESRD at an average age of 52.1 +/- 11.3 years. The frequencies of each genotype of the genes were similar to those expected from Hardy-Weinberg equilibrium. There was a tendency to an excess of patients homozygous for the D allele in patients with ESRD (DD in patients with ESRD, 11.8%; DD in patients without ESRD, 3.7%; chi-square, 1.505; P: = 0.22). Cumulative renal survival was significantly less in those with the DD genotype compared with ID/II genotypes. Estimated mean renal survival was 46.4 years (95% confidence interval, 39.5 to 53.3) in subjects with the DD genotype and 57.2 years (95% confidence interval, 54.2 to 60.2) in ID/II genotypes (chi-square, 7.76; P: = 0.0053). There was no association between age at onset of ESRD and either M235T or A1166C polymorphism. These findings suggest that Japanese patients with PKD homozygous for the D allele of the ACE gene are at increased risk for developing ESRD at an early age.

Suppression by flavonoids of cyclooxygenase-2 promoter-dependent transcriptional activity in colon cancer cells: structure-activity relationship

Cyclooxygenase-2 (COX-2) plays an important role in carcinogenesis. Investigation of the suppressive action of twelve flavonoids of different chemical classes on the transcriptional activity of the COX-2 gene in human colon cancer DLD-1 cells using a reporter gene assay have revealed quercetin to be the most potent suppressor of COX-2 transcription (IC50 = 10.5 microM), while catechin and epicatechin showed weak activity (IC50 = 415.3 microM). Flavonoids have three heterocyclic rings as a common structure. A structure-activity study indicated that the number of hydroxyl groups on the B ring and an oxo group at the 4-position of the C ring are important in the suppression of COX-2 transcriptional activity. A low electron density of the oxygen atom in the hydroxyl group of the A ring was also important. Further examination of the role of the hydroxyl group in the A ring showed that bromination of resacetophenone to give 3,5-dibromo-2,4-dihydroxyacetophenone resulted in a 6.8-fold increase in potency for suppressing COX-2 promoter activity. These results provide a basis for the design of improved suppressors of COX-2 transcriptional activity.

Suppression of cyclooxygenase-2 promoter-dependent transcriptional activity in colon cancer cells by chemopreventive agents with a resorcin-type structure

Cyclooxygenase-2 (COX-2) is abundantly expressed in colon cancer cells. It has been reported that inhibition of COX-2 enzyme activity is shown to prevent colon carcinogenesis. Thus, suppression of COX-2 expression may also be an effective chemopreventive strategy. In the present study, we constructed a beta-galactosidase reporter gene system in human colon cancer DLD-1 cells, and measured COX-2 promoter-dependent transcriptional activity in the cells. Interferon gamma suppressed this COX-2 promoter activity, while 12-O-tetradecanoylphorbol-13-acetate and transforming growth factor alpha (TGFalpha) exerted enhancing effects. We then tested the influence of 14 candidate cancer chemopreventive compounds on COX-2 promoter activity. Chemopreventive agents such as quercetin, kaempferol, genistein, resveratrol and resorcinol, all having a common resorcin moiety, were found to effectively suppress the COX-2 promoter activity with and without TGFalpha-stimulation in DLD-1 cells. Since all these compounds have a resorcin moiety as a common structure, a resorcin-type structure may play an active role in the inhibition of COX-2 expression in colon cancer cells.

Review article: transcriptional events controlling the terminal differentiation of intestinal endocrine cells

Secretin-producing enteroendocrine cells arise from a multipotential endocrine progenitor in the crypts of the small intestine. As these cells migrate up the crypt-villus axis, they produce secretin and stop dividing as they terminally differentiate and die. Transcription of the secretin gene is controlled by a complex enhancer binding to multiple transcription factors. The basic helix-loop-helix protein, BETA2, binds to an E box sequence and associates with the p300 coactivator to activate transcription of the secretin gene. Basic helix-loop-helix proteins appear to play a pivotal role in the control of cellular differentiation. BETA2 induces cell cycle arrest and apoptosis in addition to activating secretin gene expression. Thus BETA2 may function as a master regulatory gene to coordinate terminal differentiation of secretin cells.

Pretreatment antimicrobial susceptibilities of paired gastric Helicobacter pylori isolates: antrum versus corpus

BACKGROUND

Antimicrobial susceptibility testing of Helicobacter pylori isolates is the most useful tool for guiding specific therapy, especially when primary resistance is suspected. However, the most informative gastric biopsy site for detection of resistant H. pylori isolates is uncertain. We sought to determine whether susceptibilities to commonly used antimicrobials (amoxicillin, clarithromycin, minocycline, and metronidazole) were related to biopsy site.

METHODS

H. pylori isolates were obtained from patients who had duodenal ulcer and had not received any therapy directed against H. pylori. Agar-dilution minimum inhibitory concentrations of each antimicrobial were compared between paired H. pylori isolates from the antrum and the proximal corpus.

RESULTS

Differences in minimum inhibitory concentrations exceeding twofold were observed within the pairs of H. pylori isolates in 5 of the 40 patients tested. In three patients with clarithromycin-resistant isolates and two with metronidazole-resistant isolates, both antral and corporeal specimens revealed resistance. However, no patient had pairs of isolates categorized as resistant at one site and sensitive at the other.

CONCLUSIONS

While we found that an individual may have a mixed H. pylori infection with respect to differing antimicrobial susceptibility in different parts of the stomach, a single biopsy specimen from either the antrum or the corpus should provide reliable detection of H. pylori isolates with primary resistance.

Polaprezinc, a mucosal protective agent, in combination with lansoprazole, amoxycillin and clarithromycin increases the cure rate of Helicobacter pylori infection

AIM

To evaluate the efficacy of polaprezinc, a mucosal protective agent, in combination with a 7-day triple therapy containing lansoprazole, amoxycillin and clarithromycin, as a treatment for Helicobacter pylori.

METHODS

Sixty-six consecutive patients suffering from dyspeptic symptoms with H. pylori infection were randomly allocated to one of two regimens: one group (LAC; n = 31) received lansoprazole 30 mg b.d., amoxycillin 500 mg b.d. and clarithromycin 400 mg b.d. for 7 days. The other group (LACP; n = 35) received the LAC regimen plus polaprezinc 150 mg b.d. for 7 days. H. pylori status was evaluated by rapid urease test, histology and culture at entry and 4 weeks after treatment.

RESULTS

Five patients did not complete the treatment: no follow-up endoscopy was performed on two patients in the LAC group; one patient in the LAC group and two in the LACP group had their treatment stopped due to severe diarrhoea. By per protocol analysis, H. pylori eradication was achieved in 24 of the 28 evaluable patients (86%; 95% CI: 72-100%) after LAC therapy, and in 33 of the 33 evaluable patients (100%) after LACP therapy (P < 0.05). On intention-to-treat analysis, the rates of eradication were 24 of 31 patients (77%; 95% CI: 62-93%) in the LAC group, and 33 of 35 patients (94%; 95% CI: 86-100%) in the LACP group (P < 0.05).

CONCLUSION

A 7-day triple therapy with lansoprazole, amoxycillin and clarithromycin is effective in H. pylori eradication, but this regimen is significantly improved by the addition of polaprezinc.

Fine structural and morphometric studies on gastric parietal cells of peptic ulcer patients after long-term treatment with omeprazole

Omeprazole, a substituted benzimidazole, is known to inhibit acid secretion from parietal cells in gastric glands, and is widely utilized as a drug for peptic ulcer. To clarify the ultrastructural changes in parietal cells from long-term treatment with a therapeutic dose of omeprazole, biopsy specimens of the gastric mucosa obtained from peptic ulcer patients were morphometrically analyzed before and after omeprazole treatment. Before treatment with omeprazole, parietal cells in both the stimulated and resting stages were observed; the stimulated cells possessed smaller amounts of tubulovesicles in the cytoplasm and numerous profiles of microvilli in the intracellular canaliculi, whereas the cells in the resting phase showed numerous profiles of tubulovesicles and poorly developed microvilli in the canaliculi. Eight weeks after the onset of omeprazole treatment, the amounts of both tubulovesicles in the cytoplasm and microvilli in the intracellular canaliculi drastically decreased. These decreases in the profiles of the membrane structures with a proton pump occurred concomitantly with a significant increase in autophagic vacuole/autolysosome-like structures. These results suggest that the membrane structures with proton pump are not recycled between tubulovesicles and microvilli of intracellular canaliculi in parietal cells after omeprazole treatment, but may be sequestrated into autophagosomes and degraded by lysosomal enzymes.

Miconazole gel increases the cure rate of Helicobacter pylori infection when added to lansoprazole and amoxicillin in a randomized trial

BACKGROUND

Miconazole is an antimycotic agent with bacteriocidal activity against Helicobacter pylori in vitro. Its role in the clinical eradication of H. pylori has not been studied. The objective of this study was to investigate the efficacy and side effect profile of miconazole for the treatment of H. pylori.

MATERIALS AND METHODS

We studied 65 patients with gastritis or peptic ulcer disease in whom H. pylori infection was confirmed by a rapid urease test and microbiologic assessment. In vitro miconazole sensitivity was assessed for the H. pylori strains isolated from the enrolled patients. All patients were randomized to receive either dual therapy consisting of lansoprazole 30 mg daily and amoxicillin 500 mg three times a day for 14 days (LA, n = 33) or triple therapy using the LA regimen plus miconazole gel 100 mg three times a day for 14 days (LAM, n = 32). At least 8 weeks after the treatment, successful therapy was validated by the histological and microbiologic assessment. Adverse effects and drug adherence were monitored by direct questioning.

RESULTS

The minimum inhibitory concentrations of miconazole ranged from 3.13 to 6.25 mg/L. H. pylori was eradicated in 16 of 33 patients (48%, 95% CI = 31% to 67%) after LA therapy, and 24 of 32 patients (75%, 95% CI = 59% to 91%) after LAM therapy (p < .03). There was no significant difference in the occurrence of adverse events between the two groups.

CONCLUSIONS

The addition of miconazole gel to the LA regimen significantly improved the cure rate of H. pylori without an increase in adverse effects.

The basic helix-loop-helix protein BETA2 interacts with p300 to coordinate differentiation of secretin-expressing enteroendocrine cells

The major epithelial cell types lining the intestine comprise a perpetually self-renewing population of cells that differentiate continuously from a stem cell in the intestinal crypts. Secretin-producing enteroendocrine cells represent a nondividing subpopulation of intestinal epithelial cells, suggesting that expression of the hormone is coordinated with cell cycle arrest during the differentiation of this cell lineage. Here we report that the basic helix-loop-helix protein BETA2 associates functionally with the coactivator, p300 to activate transcription of the secretin gene as well as the gene encoding the cyclin-dependent kinase inhibitor p21. Overexpression of BETA2 in cell lines induces both cell cycle arrest and apoptosis suggesting that BETA2 may regulate proliferation of secretin cells. Consistent with this role, we observed both reentry of normally quiescent cells into the cell cycle and disrupted cell number regulation in the small intestine of BETA2 null mice. Thus, BETA2 may function to coordinate transcriptional activation of the secretin gene, cell cycle arrest, and cell number regulation, providing one of the first examples of a transcription factor that controls terminal differentiation of cells in the intestinal epithelium.

[Assessment of 123I-beta-methyl iodophenyl pentadecanoic acid (BMIPP) myocardial scintigraphy in patients of chronic right ventricular overload--fatty acid metabolism in right ventricular myocardium]

An investigation on the right ventricular pressure level and the abnormalities in the fatty acid metabolism of myocardium was made using 123I-beta-methyl-iodophenyl pentadecanoic acid (BMIPP) myocardial SPECT in patients with chronic right ventricular overloading. Twenty patients who presented with right ventricular systolic pressure (RVSP) of 35 mmHg or more were used as the subjects. Dual myocardial SPECT with 201TlCl (Tl) and BMIPP was carried out for the subjects and RVc/LVc, a ratio of radioactivity count incorporated in the right ventricular free wall to the left one was determined for Tl and BMIPP. And the correlations between RVc/LVc and RVSP, and RVc/LVc and RVSP/LVSP were examined. The subjects were classified into 3 groups based on the RVSP levels and the count ratio, BMIPP/Tl was compared among the three groups. With respect of Tl uptake, there were significant, positive correlations between RVc/LVc and RVSP (correlation coefficient r = 0.51, p < 0.05) and between RVc/LVc and RVSP/LVSP (correlation coefficient r = 0.59, p < 0.01). On the other hand, no significant correlation was found between them with respect of the uptake of BMIPP. The BMIPP/Tl ratio in the group with higher than 80 mmHg of RVSP was 0.82 +/- 0.06, which was significantly lower than the ratio's for two groups of less than 80 mmHg; 0.91 +/- 0.07 and 0.98 +/- 0.04 in the group with 35-49 and 50-79 mmHg of RVSP, respectively. These results show that when compared with BMIPP, Tl is superior for the estimation of right ventricular pressure. For the patients with right ventricular overloading, it was suggested that when RVSP reaches 80 mmHg or more, there appear some disorders in the fatty acid metabolism in the right ventricular myocardium.

Diabetes, defective pancreatic morphogenesis, and abnormal enteroendocrine differentiation in BETA2/neuroD-deficient mice

Candidate transcription factors involved in pancreatic endocrine development have been isolated using insulin gene regulation as a paradigm. The cell-type restricted basic helix-loop-helix (bHLH) gene, BETA2/NeuroD, expressed in pancreatic endocrine cells, the intestine, and the brain, activates insulin gene transcription and can induce neurons to differentiate. To understand the importance of BETA2 in pancreatic endocrine cell differentiation, mice lacking a functional BETA2 gene were generated by gene targeting experiments. Mice carrying a targeted disruption of the BETA2 gene developed severe diabetes and died perinatally. Homozygous BETA2 null mice had a striking reduction in the number of insulin-producing beta cells and failed to develop mature islets. Islet morphogenesis appeared to be arrested between E14.5 and E17.5, a period characterized by major expansion of the beta cell population. The presence of severe diabetes in these mice suggests that proper islet structure plays an important role in blood glucose homeostasis. In addition, secretin- and cholecystokinin-producing enteroendocrine cells failed to develop in the absence of BETA2. The absence of these two pancreatic secretagogs may explain the abnormal cellular polarity and inability to secrete zymogen granules in pancreatic acinar exocrine cells. The nervous system appeared to develop normally, despite abundant expression of BETA2 in differentiating neurons. Thus, BETA2 is critical for the normal development of several specialized cell types arising from the gut endoderm.

The basic helix-loop-helix transcription factor BETA2/NeuroD is expressed in mammalian enteroendocrine cells and activates secretin gene expression

The gene encoding the hormone secretin is expressed only in enteroendocrine S cells and insulin-producing pancreatic beta cells during development. A 120-bp enhancer directs cell-specific expression of the rat secretin gene in secretin-expressing cells. The enhancer includes an E-box sequence, CAGCTG, which is important for transcriptional activity. To further characterize the role of the E box, a consensus binding site for basic helix-loop-helix (bHLH) proteins, we have examined factors that interact with this element in the secretin gene. The results suggest that transcription is activated by a recently isolated tissue-specific bHLH protein, BETA2, heterodimerized to the ubiquitously expressed bHLH proteins, Pan 1 and Pan 2, the rodent homologues of E47 and E12. The importance of BETA2 for transcriptional activation of secretin is further illustrated by antisense experiments inhibiting BETA2 expression in secretin-producing cell lines, which resulted in the inhibition of most E box-dependent transcription. Expression of BETA2 in a nonendocrine cell line conferred the ability to express secretin-reporter genes that are transcribed at minimal levels in the absence of BETA2. Secretin-producing enteroendocrine cells in the murine small intestine showed specific immunostaining with BETA2 antibodies, corroborating observations in cell lines. Thus BETA2 is to our knowledge the first transcription factor identified that specifically activates cell type-specific expression of an intestinal hormone gene.

Tissue-specific response of the human platelet-activating factor receptor gene to retinoic acid and thyroid hormone by alternative promoter usage

We have studied the effects of retinoic acid (RA) and thyroid hormone (3,3',5-triiodothyronine; T3) on platelet-activating factor receptor (PAFR) gene expression in intact rats and the ability of two human PAFR gene promoters (PAFR promoters 1 and 2) to generate two transcripts (PAFR transcripts 1 and 2). Northern blotting showed that RA and T3 regulated PAFR gene expression only in rat tissues that express PAFR transcript 2. Functional analysis of the human PAFR promoter 2 revealed that responsiveness to RA and T3 was conferred through a 24-bp element [PAFR-hormone response element (HRE) located from -67 to -44 bp of the transcription start site, whereas PAFR promoter 1 did not respond to these hormones. The PAFR-HRE is composed of three direct repeated TGACCT-like hexamer motifs with 2-and 4-bp spaces, and the two upstream and two downstream motifs were identified as response elements for RA and T3. Thus, the PAF-PAFR pathway is regulated by the PAFR level altered by a tissue-specific response to RA and T3 through the PAFR-HRE of the PAFR promoter 2.

Platelet-activating factor receptor. Gene structure and tissue-specific regulation

The human platelet-activating factor receptor gene exists as a single copy on chromosome 1. Two 5'-noncoding exons (Exon 1 and 2) has distinct transcription initiation sites and promoters. These exons are alternatively spliced to a common splice acceptor site on exon 3 that contains a total coding regions. The transcript 1 is expressed ubiquitously with an emphasis of differentiated eosinophilic cell line (Eol-1), and leukocytes. On the other hand, the transcript 2 is expressed tissue-specifically. The latter is not expressed in leukocytes or brain. The transcript 1 has three tandem repeats of NF-kappa B, and SP-1 site, and responded to various inflammatory reagents including PAF itself, lipopolysaccharide, or phorbol ester. By northern blotting of tissue or cells with various nutritional or hormonal treatments, the PAF receptor messages are up-regulated. Estrogen increased the expression of the PAF receptor in human endometrial glandular cells, and vitamin A (retinoic acid) or thyroid hormone treatment up-regulates the PAF receptor expression only tissues with transcript 2 By various in vivo and in vitro transcriptional assays (CAT reporter assay, gel mobility shift assay), we identified estrogen responsible element, and hormone responsive element. The PAF receptor hormone responsive element is composed of three direct repeated TGACCT-like hexamer motifs with 2 and 4 bp spaces, and the two upstream and two downstream motifs were identified as response elements for RA and T.

Up-regulation of the intracellular Ca2+ signaling and mRNA expression of platelet-activating factor receptor by estradiol in human uterine endometrial cells

Platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine), a potent chemical mediator in inflammation, plays a role in reproduction. Using primary culture of human uterine endometrial cells, we investigated the effect of sex steroid hormones on the PAF-induced signal and its receptor mRNA expression. After a 24 hr treatment with estradiol, PAF increased the intracellular calcium ion ([Ca2+]i) in the glandular cells, but not in the stromal cells. This response was not observed in the non-treated cells, and was blocked by a PAF antagonist, WEB2086. Two types of mRNA (transcript 1 and transcript 2) occurred for PAF receptor by alternative splicing, which are under control of two distinct promoters. Using RT-PCR analysis, it was shown that both transcripts existed in endometrial cells and that estradiol alone or a combination of estradiol and progesterone induced the accumulation of transcript 2, the promoter of which responded to estrogen in our previous studies. The regulation of PAF receptor by sex steroid hormones in human uterine endometrial cells suggests that PAF is involved in the physiological process of reproduction.

Relationships between metal ions and oxygen free radicals in ethanol-induced damage to cultured rat gastric mucosal cells

The current study investigated whether metal ions were cytoprotective against ethanol-induced injury to cultured rat gastric mucosal cells in vitro. Secondly, the relationships between oxygen free radicals and cytoprotection by metal ions were examined. Cultured cells exposed to ethanol produced superoxide anion, as assessed by reduction of cytochrome c, in a time-related fashion, and the production of superoxide anion increased dose-dependently as the concentration of ethanol increased. Cellular damage increased proportionately to the production of superoxide anion. ZnCl2, AlCl3, CoCl2, CuCl2, and CdCl2 significantly diminished ethanol-induced injury dose-dependently. All of the agents studied decreased the reduction of cytochrome c in ethanol-induced damage dose-dependently. These results led to the conclusions that: (1) cultured rat gastric mucosal cells exposed to ethanol generate oxygen free radicals; (2) the production of oxygen free radicals is closely linked with ethanol-induced damage to the cells; and (3) metal ions decrease ethanol-induced gastric mucosal cell damage in vitro. Metal ions protect cultured rat gastric mucosal cells from ethanol-induced damage in which oxygen free radicals participate.

Amino-acid sequence and tissue distribution of guinea-pig leukotriene A4 hydrolase

The guinea-pig leukotriene A4 hydrolase (LTA4H)-encoding cDNA was isolated from a guinea-pig lung cDNA library by cross-hybridization using a human probe. The deduced amino acid (aa) sequence consists of 611 aa (68 756 Da) and contains all twelve internal peptide and N-terminal sequences determined from the purified enzyme from guinea-pig intestine. The aa identity of the guinea-pig enzyme with its human, mouse and rat counterparts was 92.9, 90.5 and 90.4%, respectively. The previously characterized zinc-binding motif and a putative active site were highly conserved, supporting the aminopeptidase activity described for this enzyme. RNA blot analysis demonstrated ubiquitous expression of the LTA4H mRNA.

Adaptive cytoprotection in cultured rat gastric mucus-producing cells. Role of mucus and prostaglandin synthesis

In cultured gastric mucosal cells, we investigated whether: (1) adaptive cytoprotection was associated with stimulation of endogenous prostaglandin synthesis; (2) prostaglandins given exogenously were cytoprotective against ethanol-induced gastric mucosal cell damage; and (3) a relationship existed between cytoprotection and mucus release. Cytolysis was quantified by measuring 51Cr release from prelabeled cells. Mucus release was determined by measurement of [3H]glucosamine release. Concentrations of ethanol > 12% caused cell damage and increased 51Cr release dose dependently. Pretreatment with low concentrations of ethanol (0.5-1.5%) decreased ethanol-induced 51Cr release, but also decreased prostaglandin E2 synthesis. Prostaglandin E2 and 16,16-dimethyl prostaglandin E2 given exogenously were cytoprotective against ethanol-induced gastric mucosal cell damage. Treatment with low concentrations of ethanol (1.5%) increased mucus release from cultured gastric mucosal cells. However, prostaglandin E2 and 16,16-dimethyl prostaglandin E2 did not affect mucus release. We conclude that in cultured gastric mucus-producing cells: (1) adaptive cytoprotection occurs without stimulation of endogenous prostaglandin synthesis but with increase in mucus release; and (2) exogenous prostaglandins are cytoprotective against ethanol-induced gastric mucosal cell damage without stimulating mucus release in vitro. We postulate that adaptive cytoprotection in cultured gastric mucus-producing cells is not mediated by prostaglandin, but by mucus released in response to a mild irritant.

Positive and negative regulations of human platelet-activating factor receptor transcript 2 (tissue-type) by estrogen and TGF-beta 1

We found that the expression of human platelet-activating factor receptor (PAFR) gene is differentially regulated by estrogen and TGF-beta 1. Primer extension analysis revealed that the levels of the PAFR transcript 2 were increased by estrogen, but decreased by TGF-beta 1 in the human stomach cancer cell line (JR-St cells) which expressed both functional endogenous PAFR transcript 1 (leukocyte-type) and transcript 2 (tissue-type). Both ligands did not affect the expression of intrinsic PAFR transcript 1. Furthermore, the response elements to estrogen and TGF-beta 1 in the PAFR promoter 2 were delineated by a transient expression assay using the chloramphenicol acetyltransferase (CAT) gene as a reporter in this cell line. A negative response element for TGF-beta 1 was mapped on the sequence from -90 bp to -81 bp, which has consensus sequence for TIE (TGF-beta 1 inhibitory element). Although consensus estrogen response element (AGGTCAnnnTGACCT) is not present in this promoter, the entire sequence comprising two AGGTCA half motifs spaced by 153 bp (from -257 bp to -93 bp) conferred weak but significant estrogen responsiveness. Thus, through these elements in the PAFR promoter 2, estrogen and TGF-beta 1 may regulate the PAFR gene to achieve a tissue-specific expression.

Platelet-activating factor (PAF) positively auto-regulates the expression of human PAF receptor transcript 1 (leukocyte-type) through NF-kappa B

The human platelet-activating factor receptor (PAFR) gene is transcribed by two distinct promoters (promoter 1 and promoter 2) to generate two transcripts (designated as PAFR transcript 1 and PAFR transcript 2), though their open reading frames are identical. By primer extension analysis to discriminate two transcripts, we found that the levels of PAFR transcript 1 (leukocyte-type), but not PAFR transcript 2 (tissue-type), are upregulated by PAF as well as by 12-O-tetradecanoylphorbol-13-acetate (TPA) in the human stomach cancer cell line (JR-St cells) which expresses both functional PAFR transcript 1 and PAFR transcript 2 endogenously. Functional analysis of the promoter 1 with a transient expression assay using chloramphenicol acetyltransferase (CAT) gene as a reporter showed that both PAF and TPA activated the promoter 1 but not the deleted promoter lacking the three consensus binding sites for NF-kappa B located from -571 bp to -459 bp. These findings suggest a molecular mechanism of positive regulation of PAFR gene expression by PAF through NF-kappa B, possibly by a phosphorylation reaction involving protein kinase C by PAF.

Growth regulation of rabbit gastric epithelial cells and protooncogene expression

We recently developed a primary culture system for gastric epithelial cells from adult rabbits that allows the investigation of growth regulation at the cellular level. In this study, we demonstrated that epidermal growth factor (EGF), insulin, and dibutyryl adenosine 3',5'-cyclic monophosphate (dBcAMP) all stimulated cell proliferation. Insulin and dBcAMP potentiated the stimulation of cell proliferation by EGF, while transforming growth factor-beta 1 (TGF-beta 1) inhibited it. Expression of c-fos and c-myc was induced in response to the stimulation by these growth regulators, but the degree of expression did not necessarily correlate with the effects of these agents on cell proliferation. In conclusion, EGF, insulin, and dBcAMP were positive growth regulators, while TGF-beta 1 was a negative regulator in gastric epithelial cells. These growth modulators may exert their effects by distinct pathways from a standpoint of the expression of c-fos and c-myc.

P2 purinergic receptor regulation of mucus glycoprotein secretion by rabbit gastric mucous cells in a primary culture

BACKGROUND/AIMS

Physiological regulation of gastric mucus secretion has not been well studied. The present study investigated the effects of adenosine 5'-triphosphate (ATP), a P2 purinergic receptor agonist, and its analogues on gastric mucus secretion using gastric mucous cells in a primary culture.

METHODS

A monolayer culture of gastric mucous cells from adult rabbits were prepared after enzyme digestion. Mucus secretion was estimated from the release of [3H]glucosamine from prelabeled cells. Intracellular calcium concentration ([Ca2+]i) was monitored by a Ca(2+)-sensitive probe, indo-1. Prostaglandin E2 (PGE2) in the media was measured by an enzyme-linked immunoassay.

RESULTS

ATP significantly stimulated mucus secretion by these cells at nontoxic doses in a dose-dependent fashion. The order of potency of ATP analogues stimulating mucus secretion was alpha beta-methylene ATP > ATP > 2-methylthio ATP, whereas adenosine, a P1 purinergic receptor agonist, had no effect. ATP also induced an elevation of [Ca2+]i in a dose-dependent fashion. The efficacy of ATP analogues to increase [Ca2+]i showed a similar potency to their actions on mucus secretion. ATP increased PGE2 at relatively higher concentrations, whereas indomethacin did not block ATP-induced increase of mucus secretion.

CONCLUSIONS

These results suggest that ATP stimulates mucus secretion by gastric mucous cells through P2 purinergic receptors; this appears to be mediated by intracellular calcium not by endogenous PGE2.

Protection of cultured rat gastric cells against oxidant-induced damage by exogenous glutathione

BACKGROUND/AIMS

Reduced glutathione (GSH) is an intracellular protectant against oxidants. The present study determined whether extracellular GSH protects against oxidant damage or whether an uptake system of GSH is present in cultured gastric cells.

METHODS

Hydrogen peroxide was generated by glucose oxidase and glucose. Cytotoxicity was assessed by 51Cr release. Intracellular GSH was assayed by the method of Tietze.

RESULTS

Pretreatment with extracellular GSH decreased H2O2-induced 51Cr release. Treatment with GSH enhanced cellular GSH content. Protection by pretreatment with GSH was prevented by buthionine sulfoximine (an inhibitor of gamma-glutamylcysteine synthetase). Enhancement of intracellular GSH was also prevented by buthionine sulfoximine. Acivicin (an inhibitor of gamma-glutamyl transpeptidase) prevented intracellular accumulation of GSH from extracellular GSH. Cysteine was effective in preventing damage and enhancing intracellular GSH content, whereas both glutamine and glycine were not.

CONCLUSIONS

Extracellular GSH protects cultured gastric cells from H2O2 damage by accelerating intracellular GSH synthesis; this is mediated by membrane-bound gamma-glutamyl transpeptidase acting on extracellular GSH (which supplies these cells with cysteine) and then by intracellular gamma-glutamylcysteine synthetase.

Churg-Strauss syndrome (allergic granulomatous angiitis) with multiple perforating ulcers of the small intestine, multiple ulcers of the colon, and mononeuritis multiplex

A case of Churg-Strauss syndrome with multiple perforations of the small intestine is described. A 31-year-old woman was admitted with a complaint of epigastric pain. She had a history of bronchial asthma. One week before admission, white blood cell count was 20,800/mm3 with 59% eosinophils. Neurological examination on admission disclosed mononeuritis multiplex with paresthesia in both the lower and upper extremities. At colonoscopy, there were scattered aphthous ulcers in the colon. Ophthalmological examination revealed allergic conjunctivitis. After admission, hypereosinophilia increased to as high as 36,000/mm3. Oral administration of prednisolone (60 mg/day) was begun. On the 3rd day of the treatment, the eosinophil count decreased dramatically, to 400/mm3, while severe abdominal pain developed. Since abdominal X-ray film revealed free air in the abdominal cavity, emergency laparotomy was performed and multiple intestinal ulcers with perforations were found. Partial ileectomy was performed. Pathological findings of the resected specimen were interpreted as a necrotizing angiitis with extravascular granuloma. Since the operation, the patient has been asymptomatic, except for neurological symptoms. Hypereosinophilia has decreased without treatment to counts averaging 270/mm3, within 3 months. On the basis of the clinical features and histopathological findings, a diagnosis of Churg-Strauss syndrome was established.

Roles of Ca2+ and protein kinase C in regulation of prostaglandin E2 release by cultured rabbit gastric epithelial cells

Prostaglandin (PG) has been reported to be one of the important protective factors in the gastric mucosa. However the mechanism of the regulation of endogenous PG production has not been well studied. We investigated the possible roles of Ca2+, cAMP, and protein kinase C (PKC) in the regulation of PGE2 release from cultured rabbit gastric mucosal cells. PGE2 was measured by radioimmunoassay. A23187 (Ca2+ ionophore) at 2 x 10(-6) M significantly increased PGE2 release. Deprivation of Ca2+ from the medium blocked the A23187-induced increase of PGE2. TMB-8 (a putative inhibitor of Ca2+ release from intracellular stores) did not have any significant effects on the increase of PGE2-induced by A23187. Thus, A23187 increased PGE2 through the influx of extracellular Ca2+. W7 or compound 48/80 (calmodulin inhibitors) did not alter the response of PGE2 caused by A23187. Exogenous administration of cAMP, forskolin (an activator of adenylate cyclase), or 2-chloroadenosine (a possible activator of adenylate cyclase through adenosine A2 receptor) had neither significant effects on PGE2 release nor an effect on A23187-induced increase of PGE2 release. 12-O-tetradecanoylphorbol 13-acetate (TPA, an activator of PKC) significantly stimulated PGE2 release in a dose-dependent fashion, whereas another phorbol ester with no biological activity did not. A23187 at 0.8 x 10(-6) M, but not cAMP, potentiated the TPA-induced increase of PGE2. Mepacrine (a phospholipase A2 inhibitor) reduced the A23187- and TPA-induced increase of PGE2. These results suggest that Ca2+ and protein kinase C may play important roles in the regulation of PGE2 release by cultured rabbit gastric cells.

Two different promoters direct expression of two distinct forms of mRNAs of human platelet-activating factor receptor

The human platelet-activating factor (PAF) receptor gene exists as a single copy on chromosome 1. We identified two 5'-noncoding exons, each of which has distinct transcriptional initiation sites. These exons are alternatively spliced to a common splice acceptor site on a third exon that contains the total open reading frame to yield two different species of functional mRNA (Transcript 1 and 2). Transcript 1 has consensus sequences for transcription factor NF-kappa B and Sp-1, and the Initiator (Inr) sequence homologous to the murine terminal deoxynucleotidyltransferase gene. Transcript 2 also contains consensus sequences for transcription factor AP-1, AP-2, and Sp-1. Transcripts 1 and 2 were both detected in heart, lung, spleen, and kidney, whereas only Transcript 1 was found in peripheral leukocytes, a differentiated human eosinophilic cell line (EoL-1 cells), and brain. Existence of distinct promoters was thus suggested to play a role in the regulatory control of PAF receptor gene expression in different human tissues and cells.

Role for mucous glycoprotein in protecting cultured rat gastric mucosal cells against toxic oxygen metabolites

The gastric epithelium is exposed to oxygen radicals that are generated within the lumen. Much interest has been focused on the role of mucus in maintaining integrity of the gastric mucosa against oxidants, because gastric mucus may act as a scavenger of oxygen radicals. The aim of this study was to assess the role of mucous glycoprotein in protecting cultured gastric epithelial cells against oxygen radicals. Monolayer cultures of rat gastric mucus-producing cells were studied. Oxygen radicals were generated by hypoxanthine and xanthine oxidase. Cytotoxicity was quantified by measuring chromium 51 release form prelabeled cells. Rate of mucous synthesis was estimated by incorporation of tritiated glucosamine into the cells. The effects of tetraprenyl acetone (a stimulant of mucus production) and N-acetyl-L-cysteine (a mucolytic agent) on oxygen radical-induced damage were determined. Preincubation with tetrapenyl acetone, while stimulating mucous glycoprotein by the cultured cells, caused a dose-dependent reduction of hypoxanthine-xanthine oxidase-induced 51Cr release, reaching maximum protection of the damage by 31% to 50%. In contrast, pretreatment with N-acetyl-L-cysteine potentiated oxygen radical-induced 51Cr release dose dependently. The protective effect of tetraprenyl acetone was significantly abolished by N-acetyl-L-cysteine. Neither tetraprenyl acetone nor N-acetyl-L-cysteine alone under the conditions of this study affected the cellular content of glutathione, which modulates oxygen radical injury to these cells. These results suggest that mucous glycoprotein partially but significantly protects cultured gastric epithelial cells against extracellularly generated oxygen radicals. It seems likely, therefore, that gastric mucus is involved in antioxidant defenses in these cells.

Gastric cytoprotection: morphological perspectives

In 1979, a new mechanism of gastric defense named cytoprotection was followed by numerous reports elucidating this interesting and important phenomenon. During this decade, however, the concept and definition of gastric cytoprotection have been modified from the morphological and ultrastructural viewpoints. This review attempts to describe the concept and mechanisms of cytoprotection as well as its pathophysiological features. Specifically, in vitro studies using isolated cells or monolayer cultured cells as well as molecular investigations of signal transduction system have been documented.

Molecular cloning and characterization of the platelet-activating factor receptor gene expressed in the human heart

PAF decreases cardiac contractility and blood pressure. To characterize the cardiac PAF receptor, we screened a human ventricular cDNA library in a low stringency condition, using a PCR product derived from guinea pig lung PAF receptor as a probe. Four clones were obtained and named HV1-4. In Xenopus oocytes injected with cRNA derived from HV3 or 4 but not from HV1 or 2, PAF elicited a Ca(2+)-activated Cl- current. HV3 and HV4 were duplicate clones, encoding a 342 amino-acid polypeptide which was identical to that of the human leukocyte PAF receptor. However, a portion of the 5' untranslated region of HV3 (or 4) was different from that of the leukocyte receptor cDNA. Northern blotting of human ventricles and atria using the HV3 insert showed a single band of approximately 4 kb. These results suggest a tissue-specific translational mechanism responsible for regulation of the expression of the PAF receptor mRNA in these tissues.

Three types of Gi alpha protein of the guinea-pig lung: cDNA cloning and analysis of their tissue distribution

cDNA clones encoding three types of Gi alpha, the alpha subunit of GTP-binding protein (Gi1 alpha, Gi2 alpha, and Gi3 alpha), were isolated from a cDNA library of the guinea-pig lung. Nucleotide sequence analysis revealed a high degree of homology with other mammalian Gi alpha cDNAs. By RNA blot analysis, the expression pattern of Gi1 alpha was more tissue-specific than those of other types of Gi alphas in the guinea-pig tissues examined. While Gi2 alpha and Gi3 alpha mRNAs were ubiquitously expressed in all tissues examined, Gi1 alpha mRNA was mainly expressed in the brain, lung and kidney. These results suggest that each Gi alpha protein may have a different role.

Leukotriene A4 hydrolase, a bifunctional enzyme. Distinction of leukotriene A4 hydrolase and aminopeptidase activities by site-directed mutagenesis at Glu-297

We previously obtained evidence for intrinsic aminopeptidase activity for leukotriene (LT)A4 hydrolase, an enzyme characterized to specifically catalyse the hydrolysis of LTA4 to LTB4, a chemotactic compound. From a sequence homology search between LTA4 hydrolase and several aminopeptidases, it became clear that they share a putative active site for known aminopeptidases and a zinc binding domain. Thus, Glu-297 of LTA4 hydrolase is a candidate for the active site of its aminopeptidase activity, while His-296, His-300 and Glu-319 appear to constitute a zinc binding site. To determine whether or not this putative active site is also essential to LTA4 hydrolase activity, site-directed mutagenesis experiments were carried out. Glu-297 was mutated into 4 different amino acids. The mutant E297Q (Glu changed to Gln) conserved LTA4 hydrolase activity but showed little aminopeptidase activity. Other mutants at Glu-297 (E297A, E297D and E297K) showed markedly reduced amounts of both activities. It is thus proposed that either a glutamic or glutamine moiety at 297 is required for full LTA4 hydrolase activity, while the free carboxylic acid of glutamic acid is essential for aminopeptidase.