Phenidone prevents kainate-induced neurotoxicity via antioxidant mechanisms

Acculmulating evidence indicates that a marked generation of oxygen free radicals derived from the metabolism of arachidonic acid causes neurodegeneration. Recently, we have demonstrated that the novel antioxidant actions mediated by phenidone, a dual inhibitor of cyclooxygenase/lipoxygenase pathways, may play a crucial role in preventing neuroexcitotoxicity in vitro [Neurosci. Lett. 272 (1999) 91], and that phenidone significantly attenuates kainic acid (KA)-induced seizures via inhibiting the synthesis of Fos-related antigen protein [Brain Res. 782 (1998) 337]. In order to extend our understanding of the pharmacological intervention of phenidone, we evaluated the antioxidant activity of this compound in vivo in the present study. In order to better understand the significance of a blockade of both the cyclooxygenase and lipoxygenase pathways, we studied the effects of aspirin (ASP; a non-selective inhibitor of cyclooxygenase), NS-398 (a selective inhibitor of cyclooxygenase-2), esculetin (an inhibitor of lipoxygenase) and phenidone on lipid peroxidation, protein oxidation, and glutathione (GSH) status in the rat hippocampus after KA administration. ASP (7.5 or 15 mg/kg), NS-398 (10 or 20 mg/kg), esculetin (5 or 10 mg/kg) or phenidone (25, 50 or 100 mg/kg) was administered orally five times every 12 h before the injection of KA (10 mg/kg, i.p.). The KA-induced toxic behavioral signs, oxidative stress (lipid peroxidation and protein oxidation), impairment of GSH status, and the loss of hippocampal neurons were dose-dependently attenuated by the phenidone, NS-398+esculetin, and ASP+esculetin. However, ASP, NS-398 and esculetin alone failed to protect against the neurotoxicities induced by KA. Therefore, the results suggest that protection by blockade of both cyclooxygenase and lipoxygenase pathways against KA-induced neuroexcitotoxicity is via antioxidant actions. However, a novel anticonvulsant/neuroprotective effect mediated by phenidone remains to be further characterized.

Protection by a manganese porphyrin of endogenous peroxynitrite-induced death of glial cells via inhibition of mitochondrial transmembrane potential decrease

In the cerebral ischemic penumbra, progressive metabolic deterioration eventually leads to death of glial cells. The exact mechanism for the death of glial cells is unclear. Here we report that under glucose-deprived conditions immunostimulated glial cells rapidly underwent death via production of large amounts of peroxynitrite. The cell-permeable Mn(III)tetrakis(N-methyl-4'-pyridyl)porphyrin (MnTMPyP) caused a concentration-dependent attenuation of the increased death in glucose-deprived immunostimulated glial cells. The structurally related compound H(2)TMPyP, which lacks metals, did not attenuate this augmented cell death. MnTMPyP prevented the elevation in nitrotyrosine immunoreactivity (a marker of ONOO(-)) in glucose-deprived immunostimulated glial cells. In glucose-deprived glial cells, MnTMPyP also completely blocked the augmented death and nitrotyrosine immunoreactivity induced by the ONOO(-)-producing reagent 3-morpholinosydnonimine (SIN-1). The mitochondrial transmembrane potential (MTP), as measured using the dye JC-1, was rapidly decreased in immunostimulated or SIN-1-treated glial cells deprived of glucose. MnTMPyP, but not H(2)TMPyP, blocked the depolarization of MTP in those glial cells. The present data, at least in part, provide evidence for how glial cells die in the postischemic and/or recurrent ischemic brain.

The E-cadherin gene (CDH1) variants T340A and L599V in gastric and colorectal cancer patients in Korea

INTRODUCTION

Germline mutations in E-cadherin (CDH1) have been reported in families with early onset, diffuse gastric cancer. More recently, mutations in CDH1 have been described in colorectal cancer cell lines.

AIMS

We have investigated if germline mutations in CDH1 occur among different groups of Korean gastric and colorectal cancer patients, with and without a positive family history.

METHODS

We studied 131 patients and 168 normal controls (88 Korean and 80 non-Korean). Patients were divided into five groups: group I, 20 gastric cancer patients with a family history; group II, 26 colorectal cancer patients with a family history of gastric cancer (those from familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC) kindred were excluded); group III, 16 HNPCC patients without identified germline mutations in hMLH1 and hMSH2; group IV, 35 gastric cancer patients without a family history; and group V, 34 colorectal cancer patients without a family history. Polymerase chain reaction, single strand conformational polymorphism analysis, direct sequencing, and genotyping for identified variants were performed.

RESULTS

Several germline changes in CDH1 were found. In addition to previously described polymorphisms, we found three novel changes, two of which were missense changes (T340A and L599V). T340A was present in one patient in group III and one in group V. L599V was present in one patient in group II, in two in group III, and in one in group IV. T340A was not found in normal controls while L599V was present in two of 88 Korean controls. Patients with these variants may appear to have a tendency to early onset cancer with a positive family history, although differences in frequencies did not reach statistical significance. Genotyping results suggest that these variants might have a common origin, particularly T340A.

CONCLUSION

We have described two new missense germline variants in CDH1 in various groups of Korean gastrointestinal cancer patients. Further work is required to assess if these variants increase the risk of gastrointestinal cancer.

Efficiency of combined colonoscopy and computed tomography for diagnosis of colonic actinomycosis: a retrospective evaluation of eight consecutive patients

The preoperative diagnosis of colonic actinomycosis is accurate in fewer than 20% of patients. Colonoscopy and computed tomography (CT) findings were analyzed to ascertain their diagnostic value and their role in determining therapeutic modality and outcome. Before and after treatment we retrospectively evaluated eight consecutive patients with colonic actinomycosis, all of whom were women with a previous history of intrauterine contraceptive device use. Median follow-up period was 20 months (7-57). Localized nodules were found in all cases by colonoscopy; half of these nodules included umbilication at the apex. The colonic mucosa demonstrated normal to moderate inflammation as well as hyperemia and edema. Mucosal ulceration was found in only one case. All cases showed some degree of stenosis. These findings differ from those in other inflammatory or neoplastic diseases of the colon. Abdominopelvic CT revealed extramural involvement of heterogeneous lesions all cases. Contrast enhancement also indicated severe thickening of the colonic wall (7-20 mm) with focal and dense enhancement in six cases. Seven of eight patients required surgery for diagnostic or therapeutic purposes. Complete resolution was determined using both colonoscopy and CT. As more than half of these cases could have been safely managed using an adequate antibiotic treatment, diagnostic studies indicating a high likelihood of colonic actinomycosis should be evaluated to avoid unnecessary surgeries carried out for diagnostic purposes. A combination of colonoscopy and CT appears to be important for both diagnosis and management because of their compensatory findings of mucosal and extramucosal lesions, respectively.

Dual effects of dextromethorphan on cocaine-induced conditioned place preference in mice

Dextromethorphan (DM) at supra-antitussive doses might produce psychotomimetic effects in humans. In order to understand the underlying mechanisms responsible for the behavior induced by DM, we examined the effects of DM on cocaine-induced conditioned place preference (CPP) and locomotor pattern in mice, and Fos-related antigen immunoreactivity (FRA-IR) in the striatal complex (nucleus accumbens and striatum) of the mouse brain. The effects of DM (20 and 40 mg/kg, i.p.) on the CPP for 2.5, 5, 10, and 20 mg cocaine/kg, i.p. were assessed. Pretreatment with DM dose-dependently decreased the CPP for 20 mg cocaine/kg. Similarly, pretreatment with DM appeared to reduce the CPP for 10 mg cocaine/kg, but increase the CPP for 5 mg cocaine/kg. This finding was more pronounced for 2.5 mg cocaine/kg; DM significantly increased the CPP for 2.5 mg cocaine/kg in a dose-related manner. Furthermore, these results were correlated with alterations in the locomotor pattern (marginal activity) and FRA-IR in the striatal complex. Thus, our results suggest that DM exhibits a biphasic effect on the cocaine-induced CPP and locomotor pattern.

Dichotomy between Tc-99m MDP bone scan and fluorine-18 fluorodeoxyglucose coincidence detection positron emission tomography in patients with non-Hodgkin's lymphoma

The authors report two cases of non-Hodgkin's lymphoma that were evaluated not only by conventional staging work-up but also additional Tc-99m MDP bone scans and fluorine-18 fluorodeoxyglucose (F-18 FDG) coincidence detection (CoDe) positron emission tomographic (PET) imaging. There were discordant results between the Tc-99m MDP bone scans and F-18 FDG CoDe PET. In the first case, the bone marrow biopsy was positive, and F-18 FDG CoDe PET was consistent with a malignancy, but the findings of the Tc-99m MDP bone scintiscan were negative. In the second case, the bone marrow biopsy was negative, but F-18 FDG CoDe PET revealed focal skeletal involvement, which improved markedly on the follow-up study after chemotherapy. If skeletal involvement has a focal distribution and is confined to the marrow cavity, both bone marrow biopsy and bone scintigraphy can be falsely negative. In this situation, F-18 FDG PET is useful and revealing.

Mosquito surveillance in the Demilitarized Zone, Republic of Korea, during an outbreak of Plasmodium vivax malaria in 1996 and 1997

Since 1993, more than 2,000 cases of vivax malaria have occurred in the Republic of Korea in an epidemic that ended nearly 20 malaria-free years. Most malaria has occurred in the northwestern part of the country, mainly affecting Korean military personnel. As a part of an operational surveillance effort, we sampled mosquitoes in and near the Demilitarized Zone (Paju County, Kyonggi Province) during the last 2 wk of July in 1996 and from May 15 to September 10 in 1997. The 1st year, landing collections were done at 5 different sites; the 2nd year, carbon-dioxide-baited light traps at 5 sites, larval collections in 10 adjacent fields, and landing collections at 1 site in the Demilitarized Zone were performed weekly. Of 17 species collected, Anopheles sinensis was consistently the most abundant mosquito, comprising 79-96% of mosquitoes. The diel pattern of biting by An. sinensis varied by location and season, with the majority of individuals biting late at night during warm weather (>20 degrees C) and early at night during cool weather. In contrast, Aedes vexans nipponii (the 2nd most abundant species) bit in the greatest numbers at the same time all season, from 2000 to 2300 h. Among the correlates with abundance of An. sinensis were average nighttime temperature 2 wk previous to the night in question, wind late at night (negatively correlated), and apparent size of the moon (negatively correlated). The data showed that the exact number of An. sinensis biting could not be estimated from numbers collected in carbon-dioxide-baited light traps. On the other hand, a threshold of 15 An. sinensis per trap night corresponded (88% accuracy) to a threshold of 12 mosquitoes biting 2 adjacent collectors per night. Larval collections were also significantly correlated with landing collections, despite inexact sampling methods and separation of the larval habitat from the site where landing collections were performed. Operational entomology assets using nighttime temperature records, carbon-dioxide-baited light traps, and larval collections should be able to target their efforts in Korea more efficiently.

Isolated splenic metastasis from colorectal carcinoma: a case report

Isolated splenic metastasis arising from colorectal carcinoma is very rare and there has been only 6 cases reported in the English literature. A new case is presented, and its possible pathogenesis was considered with previously reported cases. A 65-year-old male patient had received a right hemicolectomy for ascending colon cancer 36 months earlier. He was followed up regularly with serial measurement of serum carcinoembryonic antigen (CEA). Rising serum CEA was discovered from 33 months postoperatively and CT revealed an isolated splenic metastasis. He therefore underwent splenectomy, which was proven to be a metastatic adenocarcinoma with similar histological feature to the original tumor. As all reported cases showed elevated serum CEA at the time of metastasis, isolated splenic metastasis might be associated with CEA in regard to its biological functions of immunosuppression and adhesion.

Synergistic depletion of astrocytic glutathione by glucose deprivation and peroxynitrite: correlation with mitochondrial dysfunction and subsequent cell death

Previously we reported that immunostimulated astrocytes were highly vulnerable to glucose deprivation. The augmented death was mimicked by the peroxynitrite (ONOO )-producing reagent 3-morpholinosydnonimine (SIN-1). Here we show that glucose deprivation and ONOO- synergistically deplete intracellular reduced glutathione (GSH) and augment the death of astrocytes via formation of cyclosporin A-sensitive mitochondrial permeability transition (MPT) pore. Astrocytic GSH levels were only slightly decreased by glucose deprivation or SIN-1 (200 microM) alone. In contrast, a rapid and large depletion of GSH was observed in glucose-deprived/ SIN-1-treated astrocytes. The depletion of GSH occurred before a significant release of lactate dehydrogenase (a marker of cell death). Superoxide dismutase and ONOO-scavengers completely blocked the augmented death, indicating that the reaction of nitric oxide with superoxide to form ONOO was implicated. Furthermore, nitrotyrosine immunoreactivity (a marker of ONOO-) was markedly enhanced in glucose-deprived/SIN-1 -treated astrocytes. Mitochondrial transmembrane potential (MTP) was synergistically decreased in glucose-deprived/SIN-1-treated astrocytes. The glutathione synthase inhibitor L-buthionine-(S,R)-sulfoximine markedly decreased the MTP and increased lactate dehydrogenase (LDH) releases in SIN-1-treated astrocytes. Cyclosporin A, an MPT pore blocker, completely prevented the MTP depolarization as well as the enhanced LDH releases in glucose-deprived/SIN-1-treated astrocytes.

An immunocytochemical study of mitochondrial manganese-superoxide dismutase in the rat hippocampus after kainate administration

We examined the immunocytochemical distribution of mitochondrial Mn-superoxide dismutase (SOD-2) in the rat hippocampus after systemic injection of kainic acid (KA), in order to understand SOD-2-responsible antioxidant defense mechanism during the neurodegenerative process. SOD-2 immunostaining was more intense in CA3 pyramidal neurons than in CA1 neurons in the normal hippocampus. The immunoreactivity in region CA1 was reduced without significant neuronal losses within 12 h of KA injection. The CA1 and CA3 neurons lost their immunoreactivity, whereas SOD-2-positive glia-like cells proliferated, mainly throughout the CA1 sector, and had intense immunoreactivity 3 and 7 days after KA injection. This immunocytochemical distribution of SOD-2-positive non-neuronal elements was similar to that of glial fibrillary acidic protein (GFAP) and S-100 protein-positive cells. Activated microglial cells selectively marked with lectin occurred in the areas affected by the KA-induced lesion. Double-labeling immunocytochemistry showed the co-localization of SOD-2-positive non-neuronal cells and GFAP or S-100 protein-like immunoreactivity in the same cells. This suggests that astroglial cells mobilized to synthesize of SOD-2 protein in a response to KA toxicity designed to reduce the oxidative damage.

Development of a centrifugal pump with thick blades

We have developed a centrifugal blood pump with thick impeller blades (60% of pitch) to obtain a small tip clearance. An unshrouded impeller with 6 backward curved thick blades was used to reduce the dead zone between the shroud and upper casing. A streamline angle in volute was uniform in circumferential direction by continuity and angular momentum conservation. To prove the effectiveness of small tip clearance, performance and hemolysis tests were conducted on pumps with a tip clearance of 0.5, 1.5, and 2.0 mm at exit with the blade thickness of 60% of pitch, and with that of 1.0, 2.0, and 2.5 mm at exit with the thickness of 40% of pitch. The results showed that the smaller the tip clearance, the better the hydrodynamic and hemolytic performance. The best result was seen in the pump with tip clearance of 0.5 mm with a blade thickness of 60% of pitch. These results suggest that a centrifugal pump with thick blades and a small tip clearance can be a promising alternative as a cardiopulmonary bypass pump.

Increased expression of cyclooxygenase-2 protein in human gastric carcinoma

Gastric adenocarcinoma is one of the most common malignancies in the world, and yet little is known about its molecular process of development and progression. Recent studies have suggested that ingestion of nonsteroid anti-inflammatory drugs reduces the risk of colon cancer, presumably by inhibiting the cyclooxygenase (COX) enzyme. COX-2, one isoform of the COX enzyme, is the rate-limiting enzyme in prostaglandin synthesis, and the function of this enzyme is thought to relate to inflammatory processes and carcinogenesis. To understand the role of COX enzyme in gastric cancer, we measured COX-2 expression in 104 human gastric carcinoma tissues by immunohistochemical analysis. We obtained tissue specimens from 104 surgically resected gastric adenocarcinoma patients. We performed immunohistochemical stain for human COX-2 with polyclonal antibody in gastric carcinoma. After curative resection and extensive lymph node dissection, all patients received adjuvant chemotherapy containing 5-fluorouracil. Expression of COX-2 showed cytoplasmic staining, not only in cancer cells but also in precancerous lesions such as metaplastic and adenomatous cells. We confirmed up-regulation of COX-2 in gastric cancer tissues compared with normal paired mucosa using Western blot analysis. There was no correlation between clinicopathological characteristics of gastric cancer patients and intensity of COX-2 protein expression. This study indicates that COX-2 protein over-expression may contribute to an early event of gastric cancer development, and it further suggests that selective inhibition of COX-2 may provide a chemopreventive effect against gastric carcinogenesis.

No evidence of Peutz-Jeghers syndrome gene LKB1 involvement in left-sided colorectal carcinomas

LKB1 serine/threonine kinase is a gene for Peutz-Jeghers cancer predisposition syndrome. Most studies have detected a low frequency of LKB1 defects in sporadic cancer. A notable exception is a recent report describing frequent, mostly missense type, LKB1 mutations in Korean distal colorectal tumors. To clarify the role of LKB1 in colon cancer, we scrutinized 50 left-sided Korean and Finnish specimens. No somatic mutations were found. The seven Korean somatic missense mutations reported previously were functionally analyzed, and five were found not to alter LKB1 kinase activity. One of these changes was found to be a germ-line polymorphism. LKB1 involvement in distal colorectal cancer is not common.

Prolonged exposure to cigarette smoke blocks the neurotoxicity induced by kainic acid in rats

We examined the effects of cigarette smoke (CS) on three parameters associated with kainic acid (KA)-induced neurotoxicity: seizure activity, cell loss in the hippocampus, and increased Fos-related antigen (FRA) expression. Animals were exposed to the main stream of CS from 15 Kentucky 2R1F research cigarettes containing 28.6 mg tar and 1.74 mg nicotine per cigarette, for 10 min a day, 6 days per week, for 4 weeks, using an automatic smoking machine. KA administration (10 mg/kg, i.p.) produced robust behavioral convulsions lasting 4-5 h. Pre-exposure to CS significantly reduced the seizures, mortality, and severe loss of cells in regions CA1 and CA3 of the hippocampus after KA administration. Consistently, pre-exposure to CS significantly attenuated the KA-induced increased FRA immunoreactivity in the hippocampus. In contrast, pretreatment with central nicotinic antagonist, mecamylamine (2 or 10 mg/kg, i.p.) blocked the neuroprotective effects mediated by CS in a dose-dependent manner. These results indicate that CS exposure provides neuroprotection against the KA insult via nicotinic receptor activation.

A successful delivery of a baby from a D--/D-- mother with strong anti- Hr0

We describe the first reported case in Korea of a woman with a D--/ D-- phenotype, a high-titer anti-Hr0, and the successful delivery of her newborn. The mother had a history of spontaneous abortion and artificial termination. In her third pregnancy, a live infant was delivered, but died of severe hemolytic disease of the newborn due to anti- Hr0 in spite of intensive medical intervention. In her fourth pregnancy, at 22 weeks gestation, the titer of anti- Hr0 was 1024, fetal cells were direct antiglobulin test positive and the blood type was group O, D+ (CDe). We performed plasma exchanges in the mother; however, the titer of antibody rebounded to its initial level after the third plasma exchange. At 26 weeks gestation, cord blood Hb decreased to 7.1 g/dL and three intrauterine transfusions were performed using the mother's washed red blood cells (RBCs). At 34 weeks gestation, a live baby was delivered by cesarean section. The infant was hydropic with hyperbilirubinemia and severe anemia. However, after two exchange transfusions using the washed RBCs of the mother's sister, who was also D--/D--, laboratory and clinical findings returned to normal.

Protection of methamphetamine nigrostriatal toxicity by dietary selenium

Multiple dose administration of methamphetamine (MA) results in long-lasting toxic effects in the nigrostriatal dopaminergic system. These effects are considered to be primarily due to oxidative damage mediated by increased production of hydrogen peroxide or other reactive oxygen species in the dopaminergic system. The present study was designed to determine the protective effects of dietary antioxidant selenium on MA-induced neurotoxicity in the nigrostriatal dopaminergic system. Male C57BL/6J mice were fed either selenium-deficient (< 0.01 ppm Se) or selenium-replete (0.2 ppm Se) diets for 90 days. MA treatment decreased the dopamine (DA) levels in the striatum and substantia nigra (SN) of both Se-replete and Se-deficient animals. However, in Se-replete animals, this DA depletion was significantly attenuated in both the striatum and SN. A novel observation is that MA administration resulted in increased activity of Cu,Zn-SOD in the brains of both Se-deficient and Se-replete animals. However, MA administration to Se-deficient animals exhibited a higher Cu,Zn-SOD activity in the nigrostriatal system than the control animals. Elevated malondialdehyde (MDA) levels in the striatum and SN were also observed in Se-deficient MA-treated animals. Se repletion significantly increased the glutathione peroxidase (GPx) activity and the ratio of reduced glutathione (GSH)/oxidized glutathione (GSSG) in the MA-treated animals. In conclusion, we have shown that dietary Se attenuated methamphetamine neurotoxicity and that this protection involves GPx-mediated antioxidant mechanisms. Even though Cu,Zn-SOD activity was significantly elevated by MA treatment, the role of this enzyme in MA-mediated neurotoxicity is not yet clear.

Partial liquid ventilation with perfluorocarbon improves gas exchange and decreases inflammatory response in oleic acid-induced lung injury in beagles

The aim of this study was to determine the effect of partial liquid ventilation (PLV) using a perfluorocarbon (PFC) on gas exchange and lung inflammatory response in a canine acute lung injury model. After inducing severe lung injury by oleic acid infusion, beagle dogs were randomized to receive either gas ventilation only (control group, n = 6) or PLV (PLV group, n = 7) by sequential instillation of 10 mL/kg of perfluorodecalin (PFC) at 30 min intervals till functional residual capacity was attained. Measurements were made every 30 min till 210 min. Then the lungs were removed and bronchoalveolar lavage (BAL) (35 mL/kg) was performed on the right lung and the left lung was submitted for histologic analysis. There was significant improvement in PaO2 and PaCO2 in the PLV group compared to the control group (p < 0.05) which was associated with a significant decrease in shunt (p < 0.05). There was no significant difference in parameters of lung mechanics and hemodynamics. There was a significant decrease in cell count and neutrophil percentage in BAL fluid and significantly less inflammation and exudate scores in histology in the PLV group (p < 0.05). We conclude that PLV with perfluorodecalin improves gas exchange and decreases inflammatory response in the acutely-injured lung.

Mitral annulus velocity in the evaluation of left ventricular diastolic function in atrial fibrillation

This study assessed the clinical utility of mitral annulus velocity in the evaluation of left ventricular diastolic function in patients with atrial fibrillation. Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice. The clinical usefulness of conventional Doppler indexes is limited in atrial fibrillation because of the altered left atrial pressure and loss of synchronized atrial contraction. Mitral inflow and mitral annulus velocities were measured simultaneously with tau in 27 patients with nonrheumatic atrial fibrillation at the cardiac catheterization laboratory. Among deceleration time of mitral inflow, peak mitral inflow velocity (E), and peak diastolic mitral annulus velocity (E), only E correlated with tau (r = 0.51, P =.007). Prolonged tau (>/=50 ms) could be predicted by E <8 cm/s with a sensitivity of 73% (16 of 22) and a specificity of 100% (5 of 5). The E/E ratio correlated with left ventricular filling pressure (r = 0.79, P <.001). The E/E ratio of >/=11 could predict elevated left ventricular filling pressure (>/=15 mm Hg) with a sensitivity of 75% (9 of 12) and a specificity of 93% (14 of 15). Mitral annulus velocity is useful in the detection of impaired left ventricular relaxation and estimation of filling pressure even in patients with atrial fibrillation.

Somatic mutations of the first 14 exons of APC in hamartomatous polyps of the colon

Although hamartomatous or hyperplastic polyps are rarely accompanied by adenomatous or carcinomatous foci, the role of APC (MIM# 175100) mutations in these polyps is not clear. The neoplastic potential of these polyps was assessed with regard to somatic mutation of the first 14 exons of APC. DNA from 14 hamartomatous polyps (12 patients with juvenile polyp, JP; two patients with Peutz-Jeghers syndrome, PJS) and 27 hyperplastic polyps was used. Exons 1-14 of APC were amplified using verified oligonucleotide primers, and PCR-SSCP analysis was performed. Translation-terminating mutation in exon 15 was also screened using the protein truncation test. All mutations found were transitions or transversions with heterozygous alleles of both wild-type and mutant APC in exons 2, 9, 10, and 11. Four hamartomatous polyps (three from JP and one from PJS) showed seven, new mutations and one common APC variant (codon 486), whereas no hyperplastic polyps demonstrated mutation. APC mutation was not correlated with previous history of colorectal carcinoma or number of polyps. Since all mutations were missense or silent mutations occurred in exons not previously known to have functionally relevant area, their phenotypic implication appeared to be limited.

Detection of transforming growth factor-alpha in the serum of gastric carcinoma patients

Transforming growth factor-alpha (TGF-alpha) is a ligand for epidermal growth factor receptor (EGFR) and it is overexpressed in various malignancies including lung, esophageal, colorectal, ovarian and gastric carcinomas. In patients with gastric carcinoma, its overexpression may be associated with advanced stage or poor prognosis. We have recently demonstrated that the mean serum level for EGFR in gastric carcinoma patients was significantly elevated compared with that of healthy controls. Using the enzyme-linked immunosorbent assay, the levels of TGF-alpha were determined in serum from 40 patients with gastric carcinoma (5 patients with stage I, 2 stage II, 4 stage III, and 29 stage IV patients) and 33 healthy controls. The mean serum level for TGF-alpha in the gastric carcinoma patients was significantly elevated as compared with that of healthy controls (104 +/- 235 vs. 22 +/- 16 pg/ml; p = 0.03). Eleven patients with gastric carcinoma (27.5%) showed elevated serum TGF-alpha levels above the cutoff value of 54 pg/ml (defined as 2 standard deviations above the mean of the control group). No significant association was noted between the positivity of TGF-alpha and clinicopathologic characteristics including gender, age and stage. However, poorly differentiated adenocarcinoma showed a higher positivity of serum TGF-alpha (43.8%) compared with other histologic types, which was marginally significant (p = 0.06). These results suggest that serum TGF-alpha could be useful as a tumor marker of gastric carcinoma for predicting prognosis and follow-up after surgery in patients whose initial serum TGF-alpha levels are elevated.

Phenidone attenuates oxygen/glucose deprivation-induced neurotoxicity by antioxidant and antiapoptotic action in mouse cortical cultures

The abrupt elevation in the levels of cyclooxygenase or lipoxygenase metabolites of arachidonic acid during cerebral ischemia contributes to neuronal injury. Recently, evidence has accumulated that both excitotoxic and apoptotic features can coexist in ischemia models in vitro and in vivo. In this study, we evaluated whether phenidone, an inhibitor of both cyclooxygenase and lipoxygenase, can provide protection against excitotoxin- or ischemia-induced neurotoxicity, including the staurosporine apoptosis model, in mouse cortical cultures. We examined the protective effect of phenidone against free radical injuries induced by arachidonic acid, hydrogen peroxide, xanthine/xanthine oxidase, Fe2+/ascorbic acid. Pre- and post-treatment with phenidone (300 microM for 24 h) moderately attenuated the neuronal injury induced by 50 microM kainate and oxygen/glucose deprivation (45 min) by 33% and 50%, respectively. It had no effect on NMDA induced injury (150 microM for 5 min). The maximum dose of phenidone (300 microM) reduced the oxidative injury induced by arachidonic acid (71% inhibition), hydrogen peroxide (95% inhibition), xanthine/xanthine oxidase (57% inhibition), and Fe2+/ascorbic acid (99% inhibition) neurotoxicity. Phenidone (300 microM) decreased staurosporine (100 nM)-induced apoptosis to 30%. These results suggest that phenidone may contribute to neuronal survival by modulating oxidative stress, which is involved in the excitotoxic and apoptotic processes occurring under ischemic conditions.

Evaluation of the malaria threat at the multipurpose range complex, Yongp'yong, Republic of Korea

As part of an operational effort to control the transmission of malaria after its reemergence in the Republic of Korea, a number of U.S. military and Korean civilian health workers assessed the situation at a large training site where two cases had been transmitted. The vector mosquitoes (Anopheles sinensis) probably had a limited flight range (< 1 km) in this situation based on low numbers in permanent light traps and biting collections at the billeting area compared with collections from light traps and larval surveys where the mosquito was abundant. The threat of malaria was proven by the presence of infected local Korean residents (13 of 105 sampled). However, only a small proportion of U.S. soldiers (39 of 78 surveyed) at the training site used personal protective measures. Further efforts should include improved techniques for informing and motivating soldiers to use personal protective measures and cooperation with Korean authorities to perform vector control in civilian areas bordering the training area.

Mechanisms of inactivation of mismatch repair genes in human colorectal cancer cell lines: the predominant role of hMLH1

Fifteen to twenty-five percent of sporadic colorectal carcinomas are replication error (RER) positive. Because the frequency of mutations in the mismatch repair genes (hMLH1 and hMSH2) is low in these tumors, we have investigated the role of mutational inactivation, methylation of the promoter region, and loss of heterozygosity (LOH) as a possible explanation for the mutator phenotype of RER+ colorectal cancer cell lines. Genomic DNA was extracted from a panel of 49 human colorectal cancer cell lines. The RER status was determined by amplification of BAT-26. All exons of hMLH1 and hMSH2 were amplified with the PCR and screened by using single-strand conformational polymorphism and direct sequencing. The methylation status was ascertained by methylation-specific PCR after bisulfite modification of DNA. Western blotting for hMLH1 was performed on methylated cell lines before and after the addition of the demethylating agent 5-azacytidine. LOH was sought by GENESCAN analysis of amplified CA repeat markers and indirectly by determining the number of homozygotes in the cell lines and human random controls. Twelve cell lines from ten tumors (24%) were RER+. Hypermethylation of the hMLH1 promoter occurred in five of ten (50%) RER+ tumors, whereas three of thirty-two (6%) RER tumors showed partial methylation. None of the fully methylated cell lines expressed hMLH1, although all reexpressed hMLH1 after treatment with 5-azacytidine. There was no LOH in the RER+ tumors in either hMLH1 or hMSH2. Our results suggest that mutations of hMLH1 together with hypermethylation of the promoter region, but not LOH, are the cause of the mutator phenotype in the majority (70%) of RER+ tumors.

Surgically induced degeneration and regeneration of the choriocapillaris in rabbit

BACKGROUND

Retinal pigment epithelium (RPE) and choriocapillaris play an important role in maintaining the outer retina. Clinical and experimental studies have shown that there is a close relationship between them. To examine the relationship between RPE and choriocapillaris we developed an animal model in which degeneration and regeneration of the choriocapillaris can be created easily and reproducibly.

METHODS

Using pigmented rabbits a retinal detachment (about 7 disk diameters) was created in the eye and the detached retina was surgically removed. A half area of the exposed RPE was mechanically debrided using a silicone brush. The other half area remained untouched. The eyes were morphologically examined at 3, 7, and 14 days and 4 and 8 weeks after the surgery using scanning or transmission electron microscopy. Changes in the choriocapillaris after the RPE debridement were also evaluated by corrosion vascular casts.

RESULTS

The debrided area was resurfaced with elongated RPE in 7 days after surgery. The replaced RPE was dedifferentiated but it gradually recovered cell polarity by 4 weeks after surgery. The choriocapillaris beneath the debrided area underwent degeneration; however, it regenerated by 4 weeks after surgery, corresponding to the timing of the morphologic recovery of the replaced RPE.

CONCLUSION

This animal model of surgically induced degeneration and regeneration of the choriocapillaris may be useful to clarify the relationship between RPE and choriocapillaris and to study potential treatments for choroidal vascular diseases.

Twelve-year tracking of blood pressure in Korean school children: the Kangwha Study

Longitudinal data from different populations have shown different degrees of tracking of blood pressure (BP). To examine BP tracking in Korean school children, 219 of 430 children (100 males, 119 females) who were 6 years old in 1986 in Kangwha County, Korea have been examined annually up to 1997 in the Kangwha Study. BP was measured twice with standard mercury sphygmomanometers and the average of the two measurements was used for the level of BP. Diastolic BP were measured at the fourth Korotkoff sound. Tracking was examined using a time-lag correlation analysis and McMahan's tracking index tau, which indicates the proportion of variation attributable to tracking apart from the natural growth component. As well the jackknife method was used to obtain the confidence interval of tau. Correlation coefficients between systolic BP from age 6 to 17 ranged from 0.39-0.54 for males and 0.44-0.57 for females. Taus for systolic BP were 0.875 (95% CI: 0.803-0.947) and 0.900 (95% CI: 0.809-0.991) in males and females, respectively. Correlation coefficients between diastolic BP from age 6 to 17 ranged from 0.28-0.47 for males and 0.14-0.47 for females. Taus for diastolic BP were 0.983 (95% CI: 0.897-1.000) and 0.800 (95% CI: 0.717-0.883) in males and females, respectively. These findings showed strong evidence for BP tracking in Korean school children from childhood to late adolescence.

Innovative ambulatory drug delivery system using an electrolytic hydrogel infusion pump

This report describes an ambulatory infusion device developed to provide parenteral drug delivery at a precisely controlled rate. The device is based on the innovative and unique concept of utilizing electrohydrolysis of a negatively charged hydrogel. The system consists of two modules: a pump unit and an electronic control unit. The pump module, which can be a disposable unit, contains medication separated by a flexible membrane from a gas generating chamber; this latter is an electrolytic cell comprising a hydrogel block and two platinum electrodes. The microcontroller-based control module is constructed with a user interface which includes input keys and a liquid crystal display, as well as a control to alter driving current level, depending on the infusion rate required. A microprocessor instantaneously calculates the current level required; this is based on operator-selected infusion rate, ambient pressure, and temperature sensor output. The accuracy and precision of the device were verified for all flow rates and for different environmental conditions; in vitro test results showed acceptable accuracy with less than +/- 5% error over the whole operating range of 0.1-100 [ml/h]. The device is small, lightweight, simple and easy to manufacture, and is also designed to be comfortably and conveniently worn by patients. It can be used for a variety of regimens including, for example, chemotherapy, insulin delivery, and pain management, antibiotic and AIDS therapy.

Inhibition of choriocapillaris regeneration with genistein

PURPOSE

To test the effects of genistein on choriocapillaris regeneration and retinal pigment epithelial (RPE) wound healing in a surgical model in the rabbit.

METHODS

Intravitreal injections of either 0.1 ml of a 90-microM concentration of genistein, dimethyl sulfoxide (DMSO; negative control), or 2 microg cycloheximide (positive control) were given 24 hours before surgical debridement of RPE in rabbits. Scanning electron microscopy (EM) of choroidal vascular casts and the RPE wounds and histologic evaluation by light microscopy and EM of the disturbed areas were performed at days 1, 7, and 30 after surgery. Quantitative analysis of the area of the choriocapillaris bed and RPE was performed by automated image analysis, and the results were analyzed by paired Student's t-test.

RESULTS

Loss of RPE caused a rapid initial atrophy followed by slower subsequent revascularization of the choriocapillaris, which paralleled the RPE wound healing. Choriocapillaris regeneration appeared nearly normal by day 30 in the DMSO group. Inhibition of choriocapillaris revascularization by genistein was significant at day 30 when compared with the DMSO-treated negative control (P = 0.013). There was a strong trend toward inhibition in the cycloheximide-treated positive control group (P = 0.062), which reached significance at day 7 compared with the DMSO group (P = 0.02). RPE covered the wound area by day 7 in all groups.

CONCLUSIONS

Intravitreal injection of genistein was found to cause significant inhibition of choriocapillaris regeneration without apparent effect on RPE wound healing. Tyrosine kinase inhibitors such as genistein may be useful as a pharmacologic approach in the treatment of choroidal neovascularization.

Lead induced thiamine deficiency in the brain decreased the threshold of electroshock seizure in rat

Many neurological disorders that occur frequently in lead intoxicated animals, have also been observed in thiamine deficient animals. To test whether lead intoxication could decrease the thiamine status and thresholds of electroshock seizure in rats, 3-week-old Wistar rats were treated with lead or lead plus thiamine. For comparison, a thiamine deficient group was included. Thiamine contents and transketolase activity, one of the thiamine dependent enzymes in the brain regions were significantly lowered by lead intoxication and thiamine deficiency. In both cases, thresholds of the electroshock seizure were significantly decreased. Thiamine supplementation reversed these signs and decreased the brain lead concentration in the lead treated group. The results from the present study suggest that the increased seizure susceptibility induced by lead intoxication in rats may be mediated at least in part through the changes of thiamine status.

Dextromethorphan modulates the AP-1 DNA-binding activity induced by kainic acid

We have recently reported that dextromethorphan attenuates the neurotoxicity induced by kainic acid in a dose-related fashion. Pretreatments with dextromethorphan (50 mg/kg, p.o. x2) significantly reduced the activator protein-1 DNA-binding activity and the Fos-related antigen-immunoreactive protein induced by kainic acid (10 mg/kg, i.p.) in the CA1, but not the CA3 or the dentate gyrus sector of the rat hippocampus. Paradoxically, dextromethorphan itself caused an elevated activator protein-1 DNA-binding activity and Fos-related antigen-immunoreactive protein in the CA1 region which lasted for at least 4 days. The results suggest that the CA1 area is the critical site for mediating the putative neuroprotective effect induced by dextromethorphan.

Nitric oxide-enhanced excitotoxicity-independent apoptosis of glucose-deprived neurons

Glucose deprivation has been shown to elicit neuronal death via extracellular glutamate accumulation. Here we report that immunostimulated glial expression of inducible nitric oxide synthase enhances the apoptotic death of glucose-deprived cerebellar granule cells (CGC) via the excitotoxicity-independent pathway. CGC cultures were immunostimulated by interferon-gamma (100 U/ml) and lipopolysaccharides (1 microg/ml) and 2 days later were challenged by glucose deprivation. Neither a 2-h Glucose deprivation nor a 2-day immunostimulation altered the viability of CGC. A 2-day immunostimulation, however, markedly enhanced the apoptotic death of CGC glucose-deprived for 1 h. The increased apoptotic death of glucose-deprived CGC after immunostimulation was mimicked by the nitric oxide (NO) releasing reagent 3-morpholinosydnonimine (200 microM, 30 min) and was partially prevented by the NO synthase (NOS) inhibitor N(G)-nitroarginine. The enhanced apoptotic death was not blocked by the N-methyl-D-aspartate (NMDA) receptor antagonists D-2-amino-5-phosphovalerate (APV) and dizocilpine (MK-801) or the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Moreover, the NO-induced enhanced apoptotic death occurred without a significant increase of the concentration of glutamate in the bathing medium. Our data indicate that immunostimulated glial cells potentiate the apoptotic death of glucose-deprived CGC in part through the expression of inducible NOS but not through NMDA receptor activation. Potentiation of glucose-deprived CGC death by immunostimulated glial cells may be clinically implicated in the tendency of recurrent ischemic insults to be more severe and fatal than an initial ischemic insult.

Extramammary Paget's disease with aggressive behavior: a report of two cases

Extramammary Paget's disease (EMPD) is an intraepithelial neoplastic disorder which is included as a rare malignant condition. However, it sometimes shows aggressive behavior of local recurrence and coexisting malignancy. We had experienced nine cases of EMPD involving the scrotum for seven years. Two cases of them presented metastasis. The first case presented extensive inguinal lymph node metastasis with underlying adnexal adenocarcinoma one year after wide local excision. The second case initially presented multiple metastasis to the liver and in the lymph node. The latter, showing fulminant progression with liver metastasis, may be only the second case reported in English literature. EMPD is considered as a malignant neoplasm with aggressive behavior from initial presentation. Because wide local excision of the lesion alone may be occasionally insufficient, a careful follow-up must be done to detect recurrence or internal malignancy.

Surgical reconstruction of the contracted orbit

Anophthalmic patients and patients afflicted with retinoblastoma incur severe deformity of the orbit. Treatment of the severely contracted orbit is very difficult, and patient satisfaction is often poor. Since 1988, we have performed temporalis muscle transfer and surgical expansion of the contracted bony orbit in 26 patients. Satisfactory results were obtained. Gradual expansion of the orbit was performed in case of congenital anophthalmic patients. The treatment should be established in multiplicity, among many methods available for contracted eye sockets, according to the degree of orbital deformity and the amount of residual conjunctiva. In case of severe deformity, volume expansion surgery and temporalis muscle transfer are necessary. If augmentation is required in the periorbital region, rib bone onlay graft must be performed. We were able to shorten the operative time by modifying the three-wall orbital expansion technique of Tessier and Wolfe to a more simplified method. Our observations show that our procedures achieved symmetry in both eyes in all patients, and there have been no remarkable complications.

Transforming growth factor beta stimulation of colorectal cancer cell lines: type II receptor bypass and changes in adhesion molecule expression

The type II transforming growth factor (TGF)-beta receptor gene (TGFBR2) is often mutated in nucleotide repeat sequences in colorectal cancers that are replication error positive (RER+). These mutations are thought to be selected for escape from growth inhibition by TGF-beta rather than representing bystander events because of an increased mutation rate. We investigated the role of TGFBR2 mutations in 12 colorectal cancer cell lines. Six of these were RER+, and these were shown to have homozygous TGFBR2 mutations. All cell lines then were tested for changes in proliferation in response to TGF-beta stimulation. Despite homozygous mutation of the type II TGF-beta receptor, two RER+ cell lines, Lovo and SW48, showed statistically significant growth inhibition when stimulated by TGF-beta1 in serum-free conditions. This shows that the type II TGF-beta receptor can be bypassed in certain cases to maintain growth inhibition. We next investigated whether there was any alternative mode through which TGFBR2 mutation may give a selective advantage, such as a change in adhesion molecule expression. All cell lines were stimulated with TGF-beta1 and adhesion molecules detected by ELISA. No consistent changes were identified between the RER+ and the RER- cell lines, although changes in E-cadherin, beta-catenin, and gamma-catenin were identified in individual cell lines. We conclude that (i) type II TGF-beta receptor activity can be bypassed and thus TGFBR2 mutations in RER+ cancers may, at least sometimes, be just "bystander" events and (ii) TGF-beta can affect adhesion molecule expression so that TGFBR2 mutation may give rise to a selective advantage through an effect other escape from growth inhibition.

Pretreatment of male BALB/c mice with beta-ionone potentiates thioacetamide-induced hepatotoxicity

A possible role of metabolic activation by cytochrome P450 (P450) in thioacetamide-induced hepatotoxicity was investigated in male BALB/c mice. The mice were pretreated with the P450 inducer, beta-ionone, subcutaneously at 600 mg/kg, 72 and 48 h prior to an intraperitoneal administration of either 100 or 200 mg/kg of thioacetamide. The elevated activities of serum alanine aminotransferase and serum aspartate aminotransferase by thioacetamide were greatly potentiated by the pretreatment with beta-ionone. Moreover, the potentiation of thioacetamide-induced hepatotoxicity was also observed in the histopathological examination of livers. The hepatic necrosis by thioacetamide was potentiated when mice were pretreated with beta-ionone. In liver microsomes, the activities of P450 2B-specific pentoxyresorufin O-depentylase and benzyloxyresorufin O-debenzylase were significantly induced by the treatment with beta-ionone. Beta-ionone also induced other P450-associated monooxygenases. Because the pretreatment with beta-ionone was not hepatotoxic at the dose inducing P450s. our present results suggest that beta-ionone may be a useful model inducer of P450 enzyme(s) in studying toxic mechanism of certain chemicals which require metabolic activation by P450s in mice.

Mutated epithelial cadherin is associated with increased tumorigenicity and loss of adhesion and of responsiveness to the motogenic trefoil factor 2 in colon carcinoma cells

Epithelial (E)-cadherin and its associated cytoplasmic proteins (alpha-, beta-, and gamma-catenins) are important mediators of epithelial cell-cell adhesion and intracellular signaling. Much evidence exists suggesting a tumor/invasion suppressor role for E-cadherin, and loss of expression, as well as mutations, has been described in a number of epithelial cancers. To investigate whether E-cadherin gene (CDH1) mutations occur in colorectal cancer, we screened 49 human colon carcinoma cell lines from 43 patients by single-strand conformation polymorphism (SSCP) analysis and direct sequencing. In addition to silent changes, polymorphisms, and intronic variants in a number of the cell lines, we detected frameshift single-base deletions in repeat regions of exon 3 (codons 120 and 126) causing premature truncations at codon 216 in four replication-error-positive (RER+) cell lines (LS174T, HCT116, GP2d, and GP5d) derived from 3 patients. In LS174T such a mutation inevitably contributes to its lack of E-cadherin protein expression and function. Transfection of full-length E-cadherin cDNA into LS174T cells enhanced intercellular adhesion, induced differentiation, retarded proliferation, inhibited tumorigenicity, and restored responsiveness to the migratory effects induced by the motogenic trefoil factor 2 (human spasmolytic polypeptide). These results indicate that, although inactivating E-cadherin mutations occur relatively infrequently in colorectal cancer cell lines overall (3/43 = 7%), they are more common in cells with an RER+ phenotype (3/10 = 30%) and may contribute to the dysfunction of the E-cadherin-catenin-mediated adhesion/signaling system commonly seen in these tumors. These results also indicate that normal E-cadherin-mediated cell adhesion can restore the ability of colonic tumor cells to respond to trefoil factor 2.

Evaluation of left ventricular diastolic function when mitral E and A waves are completely fused: role of assessing mitral annulus velocity

Mitral inflow parameters have been used most widely in the evaluation of left ventricular (LV) diastolic function. However, when the mitral E and A waves are completely fused, mitral inflow parameters cannot provide information about the LV diastolic function. LV filling pressure, mitral inflow, mitral annulus velocity, and tau (tau) were measured in 59 patients with sinus rhythm when mitral E and A waves were completely fused with right atrial pacing. When mitral E and A waves were completely fused, tau correlated with the peak fused mitral annulus velocity (r = -0.60, P <.001), and peak fused mitral annulus velocity of less than 12.5 cm/s best discriminated prolonged (>/=50 ms) from normal tau, with a sensitivity of 78% and specificity of 69%. The peak fused mitral inflow velocity to peak fused mitral annulus velocity ratio correlated with LV filling pressure (r = 0.62, P <.001). A ratio of at least 8, could predict elevated LV filling pressure (>/=15 mm Hg) with a sensitivity of 65% and specificity of 74%. In conclusion, even when mitral E and A waves are completely fused, mitral annulus velocity can be used in the evaluation of LV diastolic function.

Voltage-dependent sodium and calcium currents in acutely isolated adult rat trigeminal root ganglion neurons

Voltage-dependent sodium (INa) and calcium (ICa) currents in small (<30 microM) neurons from adult rat trigeminal root ganglia were characterized with a standard whole cell patch-clamp technique. Two types of INa showing different sensitivity to tetrodotoxin (TTX) were recorded, which showed marked differences in their activating and inactivating time courses. The activation and the steady-state inactivation kinetics of TTX-resistant INa were more depolarized by about +20 and +30 mV, respectively, than those of TTX-sensitive INa. Voltage-dependent ICa was recorded under the condition that suppressed sodium and potassium currents with 10 mM Ca2+ as a charge carrier. Depolarizing step pulses from a holding potential of -80 mV evoked two distinct inward ICa, low-voltage activated (LVA) and high-voltage activated (HVA) ICa. LVA ICa was first observed at -60 to -50 mV and reached a peak at about -30 mV. Amiloride (0.5 mM) suppressed approximately 60% of the LVA ICa, whereas approximately 10% of HVA ICa was inhibited by the same concentration of the amiloride. LVA ICa was far less affected by the presence of external Cd2+ or the replacement of Ca2+ by 10 Ba2+ than HVA ICa. The omega-conotoxin GVIA (omega-CgTx), an N-type ICa blocker, suppressed approximately 65% of the whole cell HVA ICa at the concentration of 1 microM. The omega-CgTx-resistant HVA ICa was sensitive to nifedipine (10 microM), a dihydropyridine (DHP) calcium channel antagonist, which produced an additional blockade by approximately 25% of the drug-free control ( approximately 70% of the omega-CgTx-resistant ICa). The combination of 10 microM nifedipine and 1 microM omega-CgTx left approximately 13% of the drug-free control ICa unblocked. The DHP agonist S(-)-BayK8644 (5 microM) shifted the activation of the HVA ICa to more negative potentials and increased its maximal amplitude. Additionally, S(-)-BayK8644 caused the appearance of a slowed component of the tail current. These results clearly demonstrate that the presence of two types of sodium channels, TTX sensitive and resistant, and three types of calcium channels, T, L, and N type, in the small-sized adult rat trigeminal ganglion neurons.

A novel glutamic acid to aspartic acid mutation near the end of the 2B rod domain in the keratin 1 chain in epidermolytic hyperkeratosis

We report a mutation in a mild case of epidermolytic hyperkeratosis that results in a glutamic acid to aspartic acid substitution in a novel location, codon 477 or position 106 of the 2B rod domain of the keratin 1 chain. This residue has been conserved in all intermediate filament chains and lies near the beginning of the highly conserved helix termination sequence and just prior to the predicted molecular overlap region. Keratin filaments assembled in vitro from chains bearing this substitution are abnormal, indicating that the glutamic acid residue is critically involved in ionic interactions in intermediate levels of filament structure.

Age-dependent resistance to Cryptosporidium muris (strain MCR) infection in golden hamsters and mice

An age-dependent aspect of resistance to Cryptosporidium muris (strain MCR) infection was monitored in Syrian golden hamsters, Mesocricetus auratus, at 1-, 5- and 10-week of age and in ICR mice. Mus musculus, at 3-, 12-, and 15-week of age orally inoculated with a single dose of 2 x 10(6) oocysts, respectively. The prepatent periods for both animals were similar, independent of age, but the patency was significantly longer in younger hamsters (P < 0.001) and a long tendency in younger mice. Hamsters infected at 1-week of age excreted about 10 times higher oocysts than those at 5- and 10-week of age. However, the total oocyst output was similar among mice of different ages. There was a good correlation between the length of the patency and the total oocyst output in hamsters (R = 0.9646), but not in mice (R = 0.4561). The immunogenicity of the parasite to homologous challenge infections was very strong in hamsters and relatively strong in mice. These results indicate that acquired resistance to C. muris infection is age-related and the innate resistance is independent of age of hamsters, and that both innate and acquired resistance, on the contrary, are irrespective of age of mice.

Alterations in protein tyrosine kinase pathways following retinal vein occlusion in the rat

PURPOSE

To determine whether an experimental retinal vein occlusion in the rat activates protein tyrosine kinase pathways and increases angiogenic growth factors in the retina.

METHODS

Retinal vein occlusion (RVO) was induced in the rat retina with argon laser photocoagulation. Retinas were collected at 2 days, 1, 2, and 4 weeks after RVO and divided into halves: one half represented an area within the distribution of the occluded vein [RVO(IN)] and the other half represented an area outside the distribution of the occluded vein [RVO(OUT)]. RVO(IN) and (OUT) were examined by western blot analysis of tyrosine-phosphorylated proteins, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and 3 signal proteins in the tyrosine kinase pathways: phospholipase Cgamma (PLCgamma), phosphatidylinositol 3-kinase (PI3K), and mitogen-activated protein kinase (MAPK).

RESULTS

RVO caused a severe capillary nonperfusion in RVO(IN). Overall tyrosine-phosphorylated proteins were increased after RVO, especially in RVO(IN) at 2 days and 1 week. VEGF and bFGF were markedly increased in RVO(IN) at 2 days and 1 week. Tyrosine-phosphorylated PLCgamma, PI3K, and MAPK were also increased in RVO(IN) at these time points.

CONCLUSIONS

RVO caused an increase in overall protein tyrosine phosphorylation in the rat retina. This increase was associated with an increase in angiogenic growth factors (VEGF and bFGF). These results suggest that protein tyrosine kinase pathways are activated during retinal ischemia and may play a role in mitogenesis of vascular endothelial cells and other responses in the retina after RVO.

Periodicity exhibited by Dirofilaria immitis microfilariae identified in dogs of Korea

Microfilarial periodicity of Dirofilaria immitis (the dog heartworm) was determined at two hr intervals for 72 consecutive hrs in 10 naturally infected war dogs, 3-9 years old, in Korea to facilitate harvest of the microfilariae for possible use in laboratory works and to elucidate further the periodicity of the microfilaria depending on geographic location. Although the periodicity had been observed as being low-grade nocturnal, maximal microfilarial counts were found at 21:00 hr and minimal at 11:00 hr, giving rise to an evident peak in fluctuation of the larval counts. This is the first record of the periodicity of the microfilariae identified as D. immitis in Korea.

Verification of immunosuppression in chicks caused by Cryptosporidium baileyi infection using Brucella abortus strain 1119-3

Humoral immune response of young chicks to Brucella abortus strain 1119-3 inoculation was monitored to verify the degree of immunosuppression caused by infection with Cryptosporidium baileyi. Young chicks (2-day-old) were orally inoculated each with 2 x 10(6) oocysts of C. baileyi, and then injected intramuscularly with 0.3 ml B. abortus strain 1119-3 containing 1 x 10(9) living organisms on day 14 postinoculation (PI). Serum samples were tested by plate agglutination test on day 17 PI onwards at an interval of 3-6 days over a period of 36 days. Infected chicks with the coccidium showed significantly lower antibody titers than those of uninfected controls (P < 0.05). These findings document that C. baileyi infection in early life stage may predispose chicks easily to other potential poultry diseases.