Neuroreceptor Bindings and Synaptic Activity in Visual System of Monocularly Enucleated Rat

PURPOSE

To study the changes in the distribution of postsynaptic benzodiazepine (BDZ) and presynaptic adenosine A(1) (AA(1)) receptors in the superior colliculus (SC) and visual cortex (VC) of rats following monocular enucleation.

METHODS

The right eyes of 6-week-old Long-Evans rats were enucleated and ex vivo autoradiography was performed on the SC and VC obtained at different times up to 8 weeks after the enucleation. [14C]deoxyglucose was used to detect glucose metabolism, and [11C]flumazenil and [1-methyl-(11)C]8-dicyclopropylmethyl-1-methyl-3-propylxanthine ([11C]MPDX) were used to map BDZ and AA(1) receptors, respectively. The receptor-specific binding for 11C was determined, and 11C and 14C activities were evaluated separately in the same tissue by a double tracing method.

RESULTS

The uptake of [14C]deoxyglucose in the SC was depressed immediately after enucleation and gradually recovered. The binding of [11C]flumazenil to BDZ receptors in the contralateral SC was increased at week 2, and then returned to the pre-enucleation levels. The uptake of [11C]MPDX by the AA(1) receptors in the contralateral SC decreased by about 67% on day 5 after enucleation and remained low thereafter. In the contralateral VC, the uptake of [14C]deoxyglucose decreased immediately after the enucleation followed by a gradual recovery, whereas the uptake of [11C]flumazenil and [11C]MPDX was not altered.

CONCLUSIONS

The axon degeneration related decrease of the AA(1) receptor density resulted in a transient up-regulation of postsynaptic BDZ receptor density in monocularly enucleated adult rats. These results suggest that these radioligands can be used to study the distribution of the postsynaptic BDZ and presynaptic AA(1) receptors in the visual system and can probably be applied to the human visual system for positron emission tomography.

Incidence of the appearance of the red color sign on esophageal varices and its predictive factors: long-term observations of 359 patients with cirrhosis

PURPOSE

The red color sign observed by endoscopic examination is a reliable predictive factor for variceal bleeding. The aim of this study was to calculate the incidence of the appearance of the red color sign and to evaluate its predictive factors.

METHODS

Endoscopic examination was repeatedly performed in 359 consecutive patients diagnosed as having liver cirrhosis with or without esophageal varices, during a median follow-up period of 2651 days.

RESULTS

The incidence of the appearance of the red color sign on esophageal varices at the end of the tenth year was compared among patients without varices (11.4%), those with small varices (45.4%), and those with mid-size varices (65.0%). The difference was significant (P < 0.0001). The number of varices (P = 0.0010), size of varices (P = 0.0064), platelet count (P = 0.0168), and alpha-fetoprotein level (P = 0.0207) were significantly correlated with the appearance of the red color sign, as estimated by the multivariate Cox hazard model. To exclude the influence of carcinogenesis, observation was stopped when hepatocellular carcinoma was discovered. Additive predictive factors with significance were: number of varices (P = 0.001), size of varices (P = 0.027), and platelet count (P = 0.0315).

CONCLUSIONS

Endoscopic signs of esophageal varices and platelet count were significant predictors for the appearance of the red color sign.

A rare aneurysmal bone cyst of the maxillary sinus: a case report

Aneurysmal bone cyst (ABC) is a non-neoplastic expansile bone lesion that is common in the long bones; only 2% occurs in the head and neck. We present a case of ABC in a 23-year-old male and describe the clinical and radiological features, histopathology and treatment. Magnetic resonance imaging (MRI) demonstrated multiple internal septations, cysts with fluid-fluid levels of varying intensity, and an intact rim of low-intensity signal completely surrounding the lesion. The tumor was removed by enucleation with resection of the lateral nasal cavity. Histopathologic diagnosis was ABC and fibrous dysplasia. We suggest that MRI is very useful for the diagnosis of ABC. ABC is thought to follow other lesions, and thus when treating ABC, it is important to determine whether any pre-existing lesion has preceded or not; in particular, if the lesion site is in the head and neck region.

Glycyrrhizin restores the impaired IL-12 production in thermally injured mice

Mice 6 days after thermal injury (TI-mice) did not respond to lipopolysaccharide (LPS) stimulation for production of serum interleukin 12 (IL-12; 2 h after LPS stimulation, <20 pg/ml in TI-mice; 1091+/-162 pg/ml in normal mice). However, 2 h after LPS stimulation, 1456+/-118 pg/ml of IL-12 were demonstrated in sera of TI-mice previously treated with a 10 mg/kg i.p. dose of glycyrrhizin (GR). IL-12 was not induced by LPS in sera of normal mice inoculated with burn-associated type 2 T cells (IL-4/IL-10-producing CD8+CD11b+TCRgamma/delta+T cells isolated from spleens of TI-mice). However, IL-12 production was induced by LPS in sera of these mice previously treated with GR or a mixture of monoclonal antibodies (mAbs) for type 2 cytokines. Also, IL-12 production was induced by LPS in TI-mice inoculated with CD4+T cells from spleens of GR-treated normal mice (GR-CD4+T cells, 5x10(6)cells/mouse). Since GR-CD4+T cells have been shown to be antagonistic cells against production of type 2 cytokines by burn-associated type 2 T cells, these results indicate that IL-12 unresponsiveness shown in TI-mice is recovered by GR through the regulation of burn-associated type 2 T cell responses.

A mechanism of interleukin-12 unresponsiveness associated with thermal injury

An unresponsive state for the production of interleukin-12 (IL-12) is commonly observed in animals and patients with severe thermal injuries. In the present study, the participation of corticosteroids, prostaglandin E(2) (PGE(2)), and type 2 cytokines, which appeared in association with thermal injury, on the burn-associated IL-12 unresponsiveness was studied. These substances have been described as inhibitors of IL-12 production. Less than 20 pg/ml serum IL-12 was produced in thermally injured mice (TI-mice) after stimulation with lipopolysaccharide (LPS), while 1037 pg/ml IL-12 was detected in sera of unburned mice equally stimulated with LPS. Almost complete restoration of the impaired IL-12 production was witnessed in TI-mice after treatment with soluble IL-4 receptor (50 ng/mouse, 2 h and 2 days after thermal injury). However, IL-12 was not induced by LPS stimulation in TI-mice treated with an inhibitor of PGE(2) (indomethacin, 0.1-5 mg/kg) or an inhibitor of corticosteroid production (ketoconazole, 10 mg/kg). LPS-stimulated IL-12 production was also impaired in normal mice inoculated with burn-associated type 2 T cells. In addition, in the presence of 1 microg/ml LPS, naive macrophages cocultured with burn-associated type 2 T cells did not produce IL-12 in their culture fluids, while IL-12 was produced by LPS-stimulated naive macrophages that were cocultured with naive splenic CD8(+) T cells. These results suggest that the IL-12-unresponsive state demonstrated in TI-mice is associated mainly with type 2 cytokines released from burn-associated type 2 T cells.

Long-term interferon therapy for 1 year or longer reduces the hepatocellular carcinogenesis rate in patients with liver cirrhosis caused by hepatitis C virus: a pilot study

BACKGROUND AND METHODS

In order to elucidate the influence of a long-term administration of interferon on the appearance rates of hepatocellular carcinoma (HCC) in hepatitis C virus (HCV)-related cirrhosis, we retrospectively analyzed 694 patients with cirrhosis. A total of 113 patients underwent interferon therapy, including 25 patients with a long-term administration of interferon for 1 year or more, and the other 581 patients received no antiviral drugs.

RESULTS

Crude cumulative appearance rates of HCC in the interferon and the untreated groups were 14.1, and 28.4% at the end of the 5th year, and 36.7 and 52.5% at the end of the 10th year, respectively (P = 0.0028). As there was a waiting time between diagnosis and treatment (median 2.0 months, average 21.3 months) in the treated group, Cox proportional hazard analysis using a time-dependent covariate was introduced to evaluate the anticarcinogenic effect of interferon. Although male sex, higher alpha-fetoprotein, older age, lower albumin concentration, and lower platelet count significantly increased the carcinogenesis rate, interferon was not a significant contributing factor to the carcinogenesis rate as a whole (hazard ratio = 0.83, P= 0.32). When the patients with interferon were divided into two groups according to therapy duration, long-term interferon therapy significantly decreased the hepatocellular carcinogenesis rate after an adjustment by significant covariates (hazard ratio = 0.28, P= 0.0048).

CONCLUSION

When interferon is administered for 12 months or longer, effective cancer prevention will be achieved, even in patients with HCV-related cirrhosis.

Twice-daily administration of interferon-beta for chronic hepatitis C is not superior to a once-daily regimen

PURPOSE

Although interferon (IFN) is commonly used for the treatment of chronic hepatitis C virus (HCV) infection, eradication of the virus occurs in only a small proportion of patients with genotype 1b and a high virus titer. Modified IFN therapies have been tried, with only limited benefit. Recently, the administration of IFN-beta twice per day has been reported to be more effective than the usual once-daily administration regimen. The aim of this study was to evaluate whether twice-daily IFN results in a sustained response in patients with chronic HCV infection with genotype 1b, and a high virus titer.

METHODS

Twenty patients with genotype 1b and high HCV RNA level (more than 1 MEq/ml by branched DNA probe assay) were randomly assigned to receive either twice-daily 3 MU of IFN beta (group A) or once-daily 6 MU of IFN-beta (group B) for 4 weeks. All patients received a further daily dose of 6 MU IFN-beta for 12 weeks, followed by IFN-alfa three times a week for 16 weeks.

RESULTS

Although a rapid fall in HCV RNA levels was noted in group A, a sustained response was observed in only one of nine patients in this group, and none of group B. Adverse effects of IFN were more frequent and pronounced in group A than in group B.

CONCLUSIONS

We conclude that further modification, which combines the early strong anti-viral effects of the twice-daily regimen with long-term sustained response, is necessary for effective therapy of HCV patients with genotype 1b and high HCV RNA levels.

Molecular and functional identification of large neutral amino acid transporters LAT1 and LAT2 and their pharmacological relevance at the blood-brain barrier

We present here the evidence of molecular and functional expression of LAT1 and LAT2, subunits of the large neutral amino acid transporter system L, in cultured brain capillary endothelial cells of the rat. By means of the RT-PCR method, transcripts of LAT1, LAT2 and heavy chain of 4F2 antigen (4F2hc) were detected in rat primary cultured brain capillary endothelial cells (BCECs) and immortalized subline, RBEC1. The uptake properties of RBEC1, such as [3H]leucine and L-[3H]DOPA uptake, were similar to those of primary cultured BCECs. So, RBEC1 may retain almost native properties of the large neutral amino acid uptake activities. [3H]Leucine uptake by RBEC1 showed two saturable components and the Km values of the high- and low-affinity components were 8.92+/-3.18 and 119+/-45 microM, respectively. The Km value of the high-affinity component agreed well with that of LAT1 and the amino acid transport selectivity of RBEC1 was similar to that of LAT1. Therefore, it is suggested that LAT1 is important at the blood-brain barrier of rats. Additionally, the Km value of the low-affinity component was similar to that of LAT2. These observations indicate that LAT1 and LAT2 are involved as transporters for large neutral amino acids at the blood-brain barrier. Additionally, we concluded that RBEC1 is useful as an in-vitro model for evaluation of the pharmacological relevance of system L at the blood-brain barrier.

Relationship between five-year histological outcome and serial changes in serum alanine aminotransferase in patients with biochemical and virological relapse after interferon treatment for chronic hepatitis C

OBJECTIVE

The aim of this study was to assess the correlation between serial changes in serum alanine aminotransferase (ALT) levels and histological outcome 5 years after treatment of patients with chronic hepatitis C with interferon (IFN).

METHODS

We retrospectively evaluated 61 consecutive patients who underwent two liver biopsies, just before and 5 years after a 6-month course of IFN therapy, and who showed a relapse after therapy. The extent of liver fibrosis was estimated using a scale with seven grades.

RESULTS

At the end of 6-month IFN therapy, 40 (65.6%) patients had normal serum ALT concentrations. However, 13 of the 40 patients relapsed within 6 months after IFN therapy. The average ALT during 5 years in 40 patients was less than or equal to 75 IU/l, while in the other 21 patients it was more than 75 IU/l. Among the 40 patients with a mean ALT less than 75 IU/l, 13 (33%) patients showed histological improvement, 26 (65%) showed no changes and only 1 patient (2%) showed worsening of liver fibrosis. On the other hand, among the 21 patients with a mean ALT of more than 75 IU/l, only 1 (5%) patient showed improvement, 8 (38%) showed no changes and 12 patients (57%) showed worsening of liver fibrosis.

CONCLUSION

There is a significant relationship between 5-year histological outcome and serial changes in serum ALT in patients with biochemical and virological relapse after IFN treatment for chronic hepatitis C.

Long-term increase of GluR2 alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor subunit in the dispersed dentate gyrus after intrahippocampal kainate injection in the mouse

Intrahippocampal injection of a subtoxic dose of kainate in mice has been shown to induce a dispersion of granule cells of the dentate gyrus, which is a characteristic morphological change often seen in human hippocampal sclerosis. In addition, it has been shown recently that such injections lead to recurrent hippocampal seizures and changes in glucose metabolism, which are reminiscent of temporal lobe epilepsy. Previous reports on human hippocampal sclerosis have shown an increase of the expression of the GluR2 alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate subunits in the dispersed granule cell somata. However, no such changes have been observed so far in animal models of epilepsy with hippocampal sclerosis. In this study, the expression of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor subunits was examined by immunohistochemistry following intrahippocampal injection of kainate in mice and rats. In mice, such injection induced a persistent increase of GluR2 immunoreactivity in the granule cells for up to 180 days. By contrast, GluR1 immunoreactivity was transiently increased during the first four days after the injection and progressively decreased thereafter. By contrast, intrahippocampal injection of kainate in rats did not result in granule cell dispersion and no changes in GluR1 immunoreactivity or GluR2 immunoreactivity were observed. These results show that, in addition to morphological, clinical and metabolical similarities, intrahippocampal injection of kainate results in a persistent increase of GluR2 associated with granule cell dispersion, as in human hippocampal sclerosis. These data suggest the existence of common mechanisms between granule cell dispersion and regulation of GluR2 subunits associated with hippocampal sclerosis.

Increased response rate to interferon therapy after a second course in hepatitis C patients who show relapse after the initial course

Some patients with chronic hepatitis C become HCV-RNA seronegative during interferon (IFN) therapy. However, about one-half of these patients show a relapse, evident by high serum alanine aminotransferase (ALT) level. In some patients with biochemical relapse, the serum HCV-RNA level becomes low immediately after the ALT relapse. Here, we assessed the changes in serum HCV-RNA level in patients with ALT relapse after IFN therapy, and evaluated the efficacy of a second course of IFN, started at the recovery stage after ALT relapse. Two hundred and seventy-seven patients who showed HCV-RNA seronegativity by reverse transcription nested-polymerase chain reaction (RT nested-PCR) and normalization of ALT during the initial IFN therapy, and had positive HCV-RNA with ALT relapse (> 100 IU/l) within 3 months after completion of the initial IFN course were enrolled in this retrospective study. Two hundred and sixty patients were followed-up without further IFN retreatment after the ALT relapse (group 1), and 17 patients received another 6-month course of IFN after the ALT relapse (group 2). The median level of serum HCV-RNA, determined with a branched DNA probe assay (version 1; Chiron-Dai-ichi Kagaku Tokyo, Japan), in group 1 was 3.1 Meq/ml before IFN therapy, 1.3 Meq/ml at the time point of the ALT peak after the completion of IFN therapy, and 0.7 and 2.6 Meq/ml at 2-4 and 6-8 weeks after the ALT peak, respectively. The serum HCV-RNA level at 2-4 weeks after the ALT peak was lower than that before IFN therapy. The eradication rate of HCV-RNA (complete response; CR) in group 2 (47.1%; 8/17) was significantly higher than that in group 1 (1.5%; 4/260; P < 0.001). In conclusion, our data suggested that: (1) patients who showed biochemical relapse after initial IFN therapy had a significantly lower serum HCV-RNA level at recovery after ALT relapse compared with that before initial IFN therapy. (2) A high response rate was noted after a second course of IFN administered at the recovery stage of the ALT relapse, compared with patients without IFN retreatment.

DOPA cyclohexyl ester, a competitive DOPA antagonist, protects glutamate release and resultant delayed neuron death by transient ischemia in hippocampus CA1 of conscious rats

In rat striata, DOPA released is a causal factor for glutamate release and resultant delayed neuron death by four-vessel occlusion. Nanomolar DOPA cyclohexyl ester (CHE), a potent and relatively stable competitive DOPA antagonist, protects these events. We tried to clarify whether DOPA CHE protects these events in hippocampal CA1 pyramidal cell layers most vulnerable against ischemia. Five to 10 min ischemia caused slight to mild glutamate release in 10 min samples during microdialysis and mild to severe neuron death 96 h after reperfusion. DOPA and dopamine were under assay limit in this design, but were basally detected by 20 min sampling and released by 20 min ischemia. In 10 min samples, intrahippocampal perfusion of 100 nM DOPA CHE 10 min before ischemia for 70 min did not inhibit glutamate release by 10 min ischemia, while it abolished glutamate release and protected delayed neuron death by 5 min ischemia. DOPA CHE is neuroprotective under a mild ischemic condition in rat hippocampus CA1.

Fluctuation patterns of HCV-RNA serum level in patients with chronic hepatitis C

The serum level of hepatitis C virus (HCV)-RNA is clinically important as a predictor of the response to interferon (IFN) therapy in patients with chronic hepatitis C. If serum HCV-RNA levels fluctuate during follow-up, and IFN therapy is begun at the time of a low HCV-RNA level, the IFN therapy may be more effective. We evaluated the fluctuation of HCV-RNA serum levels for 2 years in 212 patients with chronic hepatitis C, untreated with IFN who had HCV genotype 1b and an HCV-RNA level of 10 Meq/ml or more at first consultation. The HCV-RNA level was measured monthly for 2 years with an HCV branched DNA probe assay (b DNA probe assay). We classified HCV-RNA patterns into three types by the ratio of maximum HCV-RNA level (a) to minimum HCV-RNA level (b). In pattern 1 (constant type, 151 patients; 71.2%) the a/ b ratio was 1-5. In pattern 2 (slight fluctuation type, 46 patients; 21.7%) the a/b ratio was 5-10. In pattern 3 (severe fluctuation type, 15 patients; 7.1%), the a/b ratio was 10 or more. Next, we evaluated the factors associated with the three patterns. Acute exacerbation of chronic hepatitis was regarded as an increase in serum alanine aminotransferase (ALT) level to more than 250 IU/l. The incidence of acute exacerbation for a 2-year follow-up was 13.9% (21/151) in pattern 1, 19.6% (9/46) in pattern 2, and 53.3% (8/15) in pattern 3. Multivariate analysis showed that acute exacerbation was the most important factor in the manifestation pattern 3. In conclusion, we found that: (1) about 70% of patients had a constant HCV-RNA levels for 2 years. (2) A few patients had severe fluctuation of serum HCV-RNA level after acute exacerbation of chronic hepatitis.

Endogenously released DOPA is a causal factor for glutamate release and resultant delayed neuronal cell death by transient ischemia in rat striata

Glutamate is implicated in neuronal cell death. Exogenously applied DOPA by itself releases neuronal glutamate and causes neuronal cell death in in vitro striatal systems. Herein, we attempt to clarify whether endogenous DOPA is released by 10 min transient ischemia due to four-vessel occlusion during rat striatal microdialysis and, further, whether DOPA, when released, functions to cause glutamate release and resultant delayed neuronal cell death. Ischemia increased extracellular DOPA, dopamine, and glutamate, and elicited neuronal cell death 96 h after ischemic insult. Inhibition of striatal L-aromatic amino acid decarboxylase 10 min before ischemia increased markedly basal DOPA, tripled glutamate release with a tendency of decrease in dopamine release by ischemia, and exaggerated neuronal cell death. Intrastriatal perfusion of 10-30 nM DOPA cyclohexyl ester, a competitive DOPA antagonist, 10 min before ischemia, concentration-dependently decreased glutamate release without modification of dopamine release by ischemia. At 100 nM, the antagonist elicited a slight ceiling effect on decreases in glutamate release by ischemia and protected neurons from cell death. Glutamate was released concentration-dependently by intrastriatal perfusion of 0.3-1 mM DOPA and stereoselectively by 0.6 mM DOPA. The antagonist elicited no hypothermia during and after ischemia. Endogenously released DOPA is an upstream causal factor for glutamate release and resultant delayed neuronal cell death by brain ischemia in rat striata. DOPA antagonist has a neuroprotective action.

Interferon therapy for flare-up of hepatitis B virus infection after emergence of lamivudine-induced YMDD motif mutant

A 61-year-old man with chronic hepatitis B was treated with interferon (IFN)-alpha for flare-up after the emergence of a lamivudine-induced YMDD motif mutant. The YMDD mutant emerged 13 months after the initiation of lamivudine therapy. Despite this, lamivudine therapy was continued. Acute exacerbation occurred 25 months after the emergence of the YMDD mutant. Treatment with IFN-alpha resulted in rapid loss of hepatitis, B virus DNA, resolution of hepatitis, and clinical recovery.

Lamivudine therapy for spontaneously occurring severe acute exacerbation in chronic hepatitis B virus infection: a preliminary study

OBJECTIVE

The nucleoside analogue lamivudine, a potent inhibitor of hepatitis B virus replication, has shown notable results in treating chronic hepatitis B. However, lamivudine has not been specifically tested for effectiveness against spontaneously occurring severe acute exacerbations of hepatitis in patients chronically infected with this virus. We addressed this issue in a pilot study.

METHODS

Ten patients with chronic hepatitis B developed severe acute exacerbation spontaneously during follow-up; 3 of them developed hepatic failure shortly before entering the trial. Lamivudine was administered long-term to the 10 patients at a daily oral dose of 100 or 300 mg.

RESULTS

All 3 patients with hepatic failure at initiation of treatment recovered dramatically. Of the remaining 7 patients, 5 recovered rapidly with lamivudine, but 2 progressed quickly to hepatic failure despite treatment. One died of sepsis and the other of multiorgan failure. In the 8 survivors, serum alanine transaminase activity decreased rapidly to normal with lamivudine therapy, and serum hepatitis B virus DNA level declined rapidly to undetectable levels. Serum total bilirubin concentrations normalized somewhat later. Prothrombin time improved steadily and gradually. Hepatitis B e antigen elimination or seroconversion was achieved in 3 survivors. No adverse effects were noted in any patient. All survivors had good quality of life with long-term lamivudine monotherapy.

CONCLUSIONS

Lamivudine is effective, safe, and well tolerated by patients with spontaneous, severe, acute exacerbation complicating chronic hepatitis B virus infection, even in the presence of hepatic failure. Lamivudine appears to be an attractive therapeutic option and may represent the best choice.

Syncope in patients with atrial flutter during treatment with class Ic antiarrhythmic drugs

We describe 2 atrial flutter (AFL) patients with syncope during treatment with class Ic antiarrhythmic drugs. During the syncope, 1:1 atrioventricular (AV) conduction during AFL preceded a wide QRS tachycardia. The class Ic drugs, flecainide and pilsicainide, slowed the atrial rate, resulting in AFL with 1:1 AV conduction, and the width of the QRS complexes became wider during the tachycardia. Syncope was abolished after successful radiofrequency catheter ablation of the AFL. These potential proarrhythmic effects of the class Ic drugs should be taken into account in AFL patients, and concomitant use of beta-blocking agents would be critical to prevent proarrhythmias.

Ultrathin SiO(x) Film Coating Effect on the Wettability Change of TiO(2) Surfaces in the Presence and Absence of UV Light Illumination

Wettability of sol-gel TiO(2) film surfaces has been studied by following the H(2)O contact angle (straight theta) as functions of illumination time and subsequent dark storage time. Upon illumination of the TiO(2) surface (lambda(ex)>300 nm), the value of straight theta rapidly decreased to reach approximately zero (photoprocess). When the resultant superhydrophilic sample was stored in the dark, the straight theta value increased slowly with increasing storage time (dark process). Ultrathin SiO(x) films were formed on the surface of TiO(2) by repeating chemisorption of 1,3,5,7-tetramethylcyclotetrasiloxane and its photooxidation. With increasing thickness of the SiO(x) monolayer coating, the rate for the dark process significantly decreased, while that for the photoprocess also decreased. Both X-ray photoelectron spectroscopic studies and product analyses during the photoprocess clarified that photocatalytic oxidation of organic adsorbates in air causes the superhydrophilicity of the TiO(2) surfaces. Copyright 2000 Academic Press.

Nine polymorphisms of angiotensinogen gene in the susceptibility to essential hypertension

Even if the importance of angiotensinogen (AGT) gene has been known in gene targeting animals and humans genetic studies, its precise mechanism and the interaction among AGT gene variants, plasma AGT concentration and risk for hypertension remain uncertain. We examined whether AGT gene variants predispose to hypertension via an increase of plasma AGT concentration. Plasma AGT concentration was estimated from plasma angiotensin I which was cleaved by an excess amount of human renin and measured by RIA. Using 9 AGT gene variants which included new polymorphisms (G-152A and T+31C), we examined the association with hypertension and with plasma concentration by a case-control study. Haplotype analysis revealed that G-6A, T+31C and M235T polymorphisms were in absolute linkage disequilibrium and were associated with hypertension but not with plasma AGT level. On the other hand, -1074t;T235 haplotype was associated with an increase of AGT level but not with hypertension. In the haplotype analysis, only H3 haplotype frequency, which contained G-6, T+31 and M235 alleles, was significantly increased in normotensive subjects, suggesting that this haplotype is associated with a hypotensive effect. According to combined haplotype analysis of diallele and microsatellite markers, it remains a possibility that M235T, T+31C, G-6A, A-20C and G-1074T polymorphisms may play an important role in increased risk for essential hypertension. Our results suggest that the positive association between AGT polymorphism and hypertension is not simply explained by an increase of plasma AGT concentration.

Search for PET probes for imaging the globus pallidus studied with rat brain ex vivo autoradiography

We have evaluated the feasibility of using four positron emission tomography (PET) tracers for imaging the globus pallidus by ex vivo autoradiography in rats. The tracers investigated were [11C]KF18446, [11C]SCH 23390 and [11C]raclopride for mapping adenosine A2A, dopamine D1 and dopamine D2 receptors, respectively, and [18F]FDG. The highest uptake by the globus pallidus was found for [11C]SCH 23390, followed by [18F]FDG, [11C]KF18446 and [11C]raclopride. The receptor-specific uptake by the globus pallidus was observed in [11C]KF18446 and [11C]SCH 23390, but not in [11C]raclopride. Uptake ratios of globus pallidus to the striatum for [18F]FDG and [11C]KF18446 were approximately 0.6, which was twice as large as that for [11C]SCH 23390. In a rat model of degeneration of striatopallidal gamma-aminobutyric acid-ergic-enkephalin neurons induced by intrastriatal injection of quinolinic acid, the uptake of [11C]KF18446 by the striatum and globus pallidus was remarkably reduced. To prove the visualization of the globus pallidus by PET with [18F]FDG and [11C]KF18446, PET-MRI registration technique and advances in PET technologies providing high-resolution PET scanner will be required. The metabolic activity of the globus pallidus could then be measured by PET with [18F]FDG, and [11C]KF18446 may be a candidate tracer for imaging the pallidal terminals projecting from the striatum.

Novel putative photoreceptor and regulatory genes Required for the positive phototactic movement of the unicellular motile cyanobacterium Synechocystis sp. PCC 6803

Synechocystis: sp. PCC 6803 is a unicellular motile cyanobacterium, which shows positive or negative phototaxis on agar plates under lateral illumination. By gene disruption in a substrain showing of positive phototaxis, it was demonstrated that mutants defective in sll0038, sll0039, sll0041, sll0042 or sll0043 lost positive phototaxis but showed negative phototaxis away from the light source. Mutants of sll0040, which is located within the cluster of these genes, retained the capacity of positive phototaxis but to a lesser extent than the parent cells. These genes are homologous to che genes, which are involved in flagellar switching for bacterial chemotaxis. Interestingly, sll0041 (designated pisJ1) is predicted to have a chromophore-binding motif of phytochrome-like proteins and a signaling motif of chemoreceptors for bacterial chemotaxis. It is strongly suggested that the positive phototactic response was mediated by a phytochrome-like photoreceptor and CheA/CheY-type signal transduction system.

Diagnostic significance of the morphological change in the atrial electrogram during Para-Hisian pacing

Para-Hisian pacing (PHP), a pacing method to differentiate between conduction occurring over an accessory pathway (AP) from that over the atrioventricular node (AVN), is assessed essentially by comparing the timing in the atrial electrogams. Morphological change in the atrial electrograms is often observed during PHP, but its significance has not been investigated. Prior to the catheter ablation procedure, PHP was performed in 52 patients with an AP and in 36 patients with AV nodal reentrant tachycardia (AVNRT). The morphological change in the atrial electrograms, which was retrospectively assessed between the His bundle and proximal right bundle branch (HB-RB) captured and non-captured beats, was identified in 15 of 52 patients with an AP and in 26 of 36 patients with AVNRT. The atrial electrogram in the 6 of these 15 AP patients changed its morphology without overlapping the ventricular electrogram. All 6 AP patients exhibited a PHP pattern with the presence of 2 retrograde conduction routes, an AP and the AVN. In the patients demonstrating no morphological change in the atrial electrogram, 33 of 37 AP patients and all 10 AVNRT patients had only one retrograde conduction route. Morphological change in the atrial electrogram without overlapping the ventricular electrogram seems to have diagnostic significance indicating the presence of both AP and AVN conduction.

Association of amino acid sequence in the PKR-eIF2 phosphorylation homology domain and response to interferon therapy

Hepatitis C virus (HCV) genotype 1b and high pretreatment virus load are well known predictive factors of poor response to interferon (IFN) therapy. In addition, a sparsity of amino acid substitutions in the interferon sensitivity determining region (ISDR) is also predictive of a poor response to IFN in patients with genotype 1b, although this issue is still controversial. Recently, a 12 amino acid domain in the E2 protein of HCV (PKR-eIF2 alpha phosphorylation homology domain [PePHD]) has been reported to bind with and block the virus replication inhibition ability of PKR, suggesting that the interaction of E2 and PKR may be one mechanism by which HCV circumvents the antiviral effect of IFN. To clarify the significance of amino-acid sequences in this domain in predicting the effect of IFN therapy, we analyzed 82 patients with genotype 1b. Eleven patients (13.4%) responded to treatment whereas the remaining 71 patients (86.6%) were nonresponders. Multivariate analysis showed that only HCV load and amino-acid substitutions in the ISDR were predictive of sustained response to IFN. Amino-acid substitutions in the PePHD were detected in only eight of 82 patients (9.8%), and did not correlate with the therapeutic effect of IFN. However, amino-acid-sequence analyses of quasispecies before and after 1 week of IFN therapy showed elimination of clones with substitutions in this domain. Our results suggest that amino-acid sequences of the PePHD domain may be related to viral resistance to IFN but do not predict the outcome of IFN therapy as amino-acid substitutions in this domain are rare.