Predicting rTMS effect for deciding stimulation parameters

Repetitive transcranial magnetic stimulation (rTMS) is used in the medical field to modulate cortical excitability. However, when applied in this setting, rTMS stimulation parameters are not usually decided objectively. The aim of this study is to make a model that predicts the rTMS effect, allowing stimulation parameters (intensity and pulse number) to be easily determined before use. First, we investigated the relationship between stimulation condition and rTMS outcome. rTMS delivered at 1 Hz was applied with stimulation intensities of 85%, 100%, or 115% resting motor threshold (RMT) over the primary motor cortex in the left hemisphere. Motor-evoked potentials (MEPs) were measured before rTMS and after every 200 rTMS pulses. Eighteen hundred pulses were applied for each stimulation condition. Results showed that more pulses and stronger intensities lead to a larger decrease in MEP amplitude. An initial prediction model was then made by applying multiple regression analysis over the experimental data. We then adjusted the model depending on the size of the initial MEP amplitude before rTMS, and confirmed the improvement.

Relationship between pulse number of rTMS and inter reversal time of perceptual reversal

The aim of this study is to investigate the stimulus parameter which affects the repetitive Transcranial Magnetic Stimulation (rTMS) effect. It is said that the condition under 1Hz rTMS induces the inhibition effect. On the other hand, the condition over 1 Hz rTMS induces the facilitation effect. However the number of pulses of rTMS is also important factor. In this study, we focused on the number of pulses. We used the cognitive task of perceptual reversal and compared the rTMS effects of different condition under 1 Hz which is the inhibition condition. It has been known that the right superior parietal lobule (SPL) has a role in perceptual reversal. We applied rTMS over the SPL and measured the inter-reversal time (IRT) of perceptual reversal. The results showed that when 0.25 Hz 60 pulses, 0.5 Hz 60 pulses and 1 Hz 60 pulses of rTMS was applied over the right SPL, the IRT was significantly smaller. On the other hand, when 1 Hz 240 pulses of rTMS was applied over the right SPL, the IRT was significantly longer. When 0.25 Hz 12 0 pulses, 0.5 Hz 120 pulses and 1Hz 120 pulses of rTMS was applied over the right SPL, there were no significant differences. Furthermore, to investigate the rTMS effects, when rTMS are applied over the motor area, we measured the motor evoked potential (MEP). The more pulses of rTMS was applied, the smaller the amplitude of MEP became. From these results, it was found that the IRT of perceptual reversal and the amplitude of MEP primarily affected by the number of pulses of rTMS.

Direct evidence for susceptibility genes for type 2 diabetes on mouse chromosomes 11 and 14

AIMS/HYPOTHESIS

Diabetogenic loci for type 2 diabetes have been mapped to mouse chromosome (Chr) 11 and 14 in the Nagoya-Shibata-Yasuda (NSY) mouse, an animal model of type 2 diabetes. We aimed to obtain direct evidence of these genes on each chromosome and to clarify their function and interaction in conferring susceptibility to type 2 diabetes.

METHODS

We established three consomic strains homozygous for diabetogenic NSY-Chr11, NSY-Chr14 or both on the control C3H background (C3H-11(NSY), C3H-14(NSY) and C3H-11(NSY)14(NSY), respectively), and monitored diabetes-related phenotypes longitudinally. The glucokinase gene was sequenced as a positional candidate gene on Chr11.

RESULTS

C3H-11(NSY) mice showed hyperglycaemia associated with impaired insulin secretion and age-dependent insulin resistance without obesity. C3H-14(NSY) mice exhibited hyperglycaemia mainly due to insulin resistance, with a slight increase in percentage body fat. C3H-11(NSY)14(NSY) double consomic mice showed marked hyperglycaemia and obesity, which was not observed in single consomic strains. Sequences of the glucokinase gene were allelically variant between NSY and C3H mice.

CONCLUSIONS/INTERPRETATION

These data provide direct evidence that Chr11 and Chr14 harbour major susceptibility genes for type 2 diabetes. These two chromosomes interact to cause more severe hyperglycaemia and obesity, which was not observed with the presence of either single chromosome, indicating different modes of gene-gene interaction depending on the phenotype. Marked changes in the phenotypes retained in the consomic strains will facilitate fine mapping and the identification of the responsible genes and their interaction with each other, other genes and environmental factors.

Time change of perceptual reversal of ambiguous figures by rTMS

The aim of this study was to investigate the effect of stimulus frequency and number of pulses during rTMS (repetitive transcranial magnetic stimulation) on the phenomenon of perceptual reversal. Particularly, we focused on the temporal dynamics of perceptual reversal in the right SPL (superior parietal lobule), using the spinning wheel illusion. We measured the IRT (inter-reversal time) of perceptual reversal. To investigate whether stimulus frequency or the number of pulses is critical for the rTMS effect, we applied the following schedules over the right SPL and the right PTL (posterior temporal lobe): 0.25Hz 60 pulses, 0.25Hz 120pulses, 0.5Hz 120 pulses, and 1Hz 120 pulses biphasic rTMS at 90% of the resting motor threshold. As a control, we included a No-TMS condition. The results showed that rTMS with 0.25Hz 60 pulses over the right SPL caused shorter IRT. There were no significant differences between IRTs for rTMS with 0.25Hz 120 pulses, 0.5Hz 120 pulses or 1Hz 120 pulses over the right SPL. Comparing these results with those of a previous study, we found that an rTMS condition with 60 pulses causes shorter IRT; 240 pulses causes longer IRT; and 120 pulses does not change IRT. Therefore, when applying rTMS over the right SPL, the IRT of perceptual reversal is primarily affected by the number of pulses.

Fatty liver and obesity: phenotypically correlated but genetically distinct traits in a mouse model of type 2 diabetes

AIMS/HYPOTHESIS

Obesity and fatty liver are commonly associated with type 2 diabetes, but the genetic and functional bases linking fatty liver with obesity and diabetes are largely unknown. Our aim was to investigate the association of fatty liver with obesity and other diabetes-related phenotypes and to define the genetic control of obesity and fatty liver.

MATERIALS AND METHODS

We established 306 F2 mice by crossing Nagoya-Shibata-Yasuda (NSY) mice, an animal model of type 2 diabetes, with control C3H mice, and analysed their phenotypes. Whole-genome screening of F2 mice was performed to identify the loci responsible for fatty liver and obesity.

RESULTS

A strong association of fatty liver with obesity, hyperinsulinaemia and hyperglycaemia was observed in F2 mice. Using whole-genome screening in 306 F2 mice, we mapped a new locus for fatty liver (Fl1n) on chromosome 6 (maximum logarithm of odds score [MLS] 10.0) and one for body weight (Bw1n) on chromosome 7 (MLS 5.1). Fl1n was linked to epididymal fat weight as well as fatty liver, but its effects were opposite in the two tissues in that the NSY allele increased liver fat but decreased epididymal fat, suggesting a role of Fl1n in partitioning of fat mass. The sequence of peroxisome proliferator-activated receptor gamma (Pparg), a candidate for Fl1n, showed allelic variation between NSY and C3H mice.

CONCLUSIONS/INTERPRETATION

These data suggest that fatty liver and obesity are phenotypically related but genetically independent. Loci homologous to Fl1n and Bw1n are good candidate genes for susceptibility to fatty liver and obesity in humans.

Phase II study of ifosfamide, carboplatin and etoposide (ICE) in recurrent glioblastoma

2066

Background: To evaluate the efficacy and tolerability of ifosfamide, carboplatin and etoposide ( ICE ) in patients with recurrent glioblastoma. Methods: This was an open-label, single-center phase II trial. Forty-two patients with first recurrent glioblastoma after surgery, standard radiotherapy and a first-line temozolomide-based or ACNU-based chemotherapy, were enrolled.The primary endpoint was progression-free survival at 6 months ( PFS-6 ), and secondary endpoints were response rate, toxicity, and survival. Chemotherapy consisted of Ifosfamide ( 700 mg / m2 on day 1, 2 and 3 ), carbopaltin ( 100 mg / m2 on day 1 ), etoposide ( 70 mg / m2 on day 1, 2, and 3 ), every 6 weeks. Results: PFS-6 was 37 %. The median PFS was 17 weeks. Response rate was 27 %. Adverse events were generally mild ( grade 1 or 2 ) and consisted mainly of alopecia. Conclusions: This regimen is well tolerated and has activity in patients with recurrent glioblastoma.

No significant financial relationships to disclose.

Allelic variation in class I K gene as candidate for a second component of MHC-linked susceptibility to type 1 diabetes in non-obese diabetic mice

AIMS/HYPOTHESIS

Recent studies have revealed that MHC-linked susceptibility to Type 1 diabetes is determined by multiple components. In the non-obese diabetic (NOD) mouse, a second component (Idd16) has been mapped to a region adjacent to, but distinct from Idd1 in the class II region. In this study, we investigated the class I K gene as a candidate gene for Idd16.

METHODS

We determined the genomic sequences of the class I K gene as well as the reactivity of K molecules with monoclonal antibodies in the NOD mouse, the Cataract Shionogi (CTS) mouse, and the NOD.CTS-H-2 congenic strain, which possesses a resistance allele to Type 1 diabetes at the Idd16 on the NOD genetic background genes.

RESULTS

While the K sequence of the NOD mouse was identical to that of Kd type, ten nucleotide substitutions were identified in the CTS mouse compared with the NOD mouse. Of these, three were in exon 4, giving two amino acid substitutions, which were identical to those seen in KK type. These characteristics were retained in the NOD.CTS-H-2 congenic strain, which had a lower incidence and delayed onset of Type 1 diabetes owing to a resistance allele at Idd16. Lymphocytes from NOD.CTS-H2 congenic mice reacted with anti-Kd and anti-Kk monoclonal antibodies, reflecting the unique sequence of the K gene. The nucleotide sequence of the K gene in the non-obese non-diabetic (NON) mouse was also unique, consisting of a combination of Kk- and Kb-like sequences.

CONCLUSIONS/INTERPRETATION

These data suggest that H2-K is unique in CTS and NON mice, and that allelic variation of the class I K gene may be responsible for Idd16.

Significance of fractionated irradiation for the biological therapeutic gain of carbon ions

It is well established that the RBE (relative biological effectiveness) for cell killing depends on LET (linear energy transfer), and that a maximum RBE is observed at approximately 150 keV.micron-1. However, the therapeutic gain depends on the ratio of the RBEs for the effects on the cancer cell population and the effects on normal tissues. The RBE of a given radiation quality depends not only on LET but also on dose, biological system and effect, and irradiation conditions. There is no data available to answer the question: which LET is suitable to improve the biological therapeutic gain of carbon ions? Here, three different LET values of 290 MeV/u carbon ions were selected, and the relative biological effectiveness was compared between tumour-growth retardation and skin damage using a murine transplantable tumour. Larger RBE values for tumours after than the skin type were obtained when carbon ions of intermediate LET were delivered daily for 2 to 5 fractions. The biological therapeutic gain would be high for the carbon ion SOBP if the number of fractions were correctly selected in clinical trials.

Scc1/Rad21/Mcd1 is required for sister chromatid cohesion and kinetochore function in vertebrate cells

Proteolytic cleavage of the cohesin subunit Scc1 is a consistent feature of anaphase onset, although temporal differences exist between eukaryotes in cohesin loss from chromosome arms, as distinct from centromeres. We describe the effects of genetic deletion of Scc1 in chicken DT40 cells. Scc1 loss caused premature sister chromatid separation but did not disrupt chromosome condensation. Scc1 mutants showed defective repair of spontaneous and induced DNA damage. Scc1-deficient cells frequently failed to complete metaphase chromosome alignment and showed chromosome segregation defects, suggesting aberrant kinetochore function. Notably, the chromosome passenger INCENP did not localize normally to centromeres, while the constitutive kinetochore proteins CENP-C and CENP-H behaved normally. These results suggest a role for Scc1 in mitotic regulation, along with cohesion.

Insulin secretion to glucose as well as nonglucose stimuli is impaired in spontaneously diabetic Nagoya-Shibata-Yasuda mice

To clarify the mechanisms of impaired insulin secretion in Nagoya-Shibata-Yasuda (NSY) mice, an inbred strain of mice with spontaneous development of type 2 (non-insulin-dependent) diabetes mellitus, the insulin response to glucose (5.5 to 27.8 mmol/L) and nonglucose stimuli (glibenclamide, arginine, and BayK8644, a Ca-channel opener) was studied in vitro using isolated islets from male NSY and control C3H/He mice at 36 weeks of age by the batch incubation method. Insulin response to 5.5 mmol/L glucose was not significantly different between NSY and C3H/He mice, but insulin response to a high concentration of glucose (> or = 11.1 mmol/L) was significantly smaller in NSY mice than in control C3H/He mice. The dose-response curve of insulin secretion showed a markedly reduced maximum response, but almost normal glucose sensitivity in NSY islets. Insulin responses to glibenclamide (1 mmol/L), arginine (20 mmol/L), and BayK8644 (0.1 mmol/L) were also significantly smaller in NSY mice than in C3H/He mice. Insulin content of islets, in contrast, was significantly higher in NSY mice than in C3H/He mice. The impaired insulin response to glucose and nonglucose stimuli together with higher insulin content in islets in the NSY mouse suggest that a defect in voltage-dependent Ca(2+)-channel or thereafter in the cascade of insulin secretion may be responsible for impaired insulin secretion in NSY mice. NSY mice, therefore, could be a novel animal model of type 2 diabetes with a defect in insulin secretion at a different site from that in previously known animal models.

Mapping and promoter sequencing of HNF-1beta gene in diabetes-prone and -resistant mice

By using a novel single nucleotide polymorphism (SNP) in the coding sequence, the chromosomal location of Tcf2, encoding hepatic nuclear factor (HNF)-1beta, was determined in F2 intercrosses between Nagoya-Shibata-Yasuda (NSY) mice, an animal model of type 2 diabetes, and control C3H/He mice. The promoter region of Tcf2 gene was sequenced in NSY, non-obese diabetic (NOD) and control C3H/He mice. Tcf2 was mapped between genetic markers D11MIT320 and D11MIT195 with the following distances: D11MIT320-(7.3 cM)-Tcf2-(0.5 cM)-D11MIT195. A variant with insertion of C between -205 and -204 in the promoter region of Tcf2 was identified in NSY mice, but not NOD and C3H/He mice.

Lack of association between hepatocyte nuclear factor-1beta gene and common forms of type 2 diabetes in the Japanese population

Mutations in the hepatocyte nuclear factor-1beta (HNF-1beta) gene have been shown to be a cause of maturity-onset diabetes of the young (MODY). We studied the contribution of the HNF-1beta gene to susceptibility to common forms of Type 2 diabetes in the genetically homogeneous Japanese population, by investigating the allelic association of Type 2 diabetes with two markers in the HNF-1beta region. The frequency of a nonsense mutation, R177X, which was previously reported in a Japanese family, was also studied by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method using a mismatch primer. A total of 200 subjects were studied. There was no significant difference in allele frequencies of either of the two polymorphisms studied between patients with Type 2 diabetes and control subjects, or between subgroups of patients subdivided by the presence of mild or severe diabetic nephropathy. None of the subjects studied had R177X mutation, giving a frequency of less than 1.1% in common forms of Type 2 diabetes in Japan. These results suggest that mutations in the HNF-1beta gene derived from a limited number of founders are not a major cause of common forms of Type 2 diabetes, even in the genetically homogeneous Japanese population.

The use of an osseointegrated implant for orthodontic anchorage to a Class II Div 1 malocclusion

This case report describes the use of an osseointegrated implant to maximize anchorage in a 24-year-old female orthodontic patient with an Angle Class II, Division 1 malocclusion. Preadjusted edgewise appliance therapy was performed by extraction of only the maxillary first premolars. The osseointegrated implant was placed in the median-sagittal region of the hard palate for maximum orthodontic anchorage and connected to maxillary first molar bands via a transpalatal arch. Total treatment time was 2 years and 8 months. Cephalometric superimposition revealed the achievement of maximum molar anchorage in the maxilla, resulting in satisfactory occlusal and facial improvements. Histological analysis of the implant-bone interface demonstrated that the fixture was successfully osseointegrated. In conclusion, the osseointegrated implant placed in the median-sagittal palate was shown to be an effective orthodontic system that can be used clinically as a rigid intraoral anchorage.

A comparative study of Caucasian and Japanese mandibular clinical arch forms

The purpose of this study was to clarify morphological differences between Caucasian and Japanese mandibular clinical arch forms in Class I, II, and III malocclusions. The study included 60 Class I, 50 Class II, and 50 Class III cases from each ethnic group. The most facial portion of 13 proximal contact areas was digitized from photocopied images of the mandibular dental arches. Clinical bracket points were calculated for each tooth based on mandibular tooth thickness data. Four linear and 2 proportional measurements were taken. The dental arches were classified into square, ovoid, and tapered forms to determine and compare the frequency distributions between the 2 ethnic groups. The Caucasian population had a statistically significant decreased arch width and increased arch depth compared with the Japanese population. When the subjects were regrouped by arch form, no statistically significant difference in arch dimension was observed between the 2 ethnic groups in any of the arch form samples. Our results suggest that there is no single arch form specific to any of the Angle classifications or ethnic groups. It appears to be the frequency of a particular arch form that varies among Angle classifications or ethnic groups.

Time course of reoxygenation in experimental murine tumors after carbon-beam and X-ray irradiation

We compared the tumor reoxygenation patterns in three different murine tumor cell lines after X-irradiation with those after carbon-beam irradiation using a heavy-ion medical accelerator (HIMAC) system. The tumors of the cell lines SCCVII, SCCVII-variant-1 and EMT6 on the hind legs of mice received local priming irradiation with a carbon-beam (8 Gy, 73 keV/microm in LET, 290 MeV/u, 6 cm SOBP) or X-rays (13 Gy, 250 kVp). After various intervals, the mice were given whole-body test irradiation (16 Gy. 250 kVp X-ray) either in air or after they were killed. The hypoxic fractions were estimated as the proportions of the surviving fractions of the tumors in killed mice to those in air-breathing mice. In the SCCVII tumors, the hypoxic fractions at 0.5 h were 50% and 21% (p < 0.05) after the priming X-irradiation and carbon-beam irradiation, respectively. In the SCCVII-variant-1 tumors, the hypoxic fractions were 85% and 82% at 0.5 h, 84% and 20% at 12 h (p < 0.01), and 21% and 31% at 24 h after X-ray and after carbon-beam irradiation, respectively. In the EMT6 tumors, the reoxygenation patterns after X-irradiation and carbon-beam irradiation were quite similar. We concluded that the reoxygenation pattern differed among the three tumor cell lines, and that reoxygenation tended to occur more rapidly after carbon-beam irradiation than after X-irradiation for SCCVII and SCCVII-variant-1 tumors.

Sequence analysis of candidate genes for common susceptibility to type 1 and type 2 diabetes in mice

Although type 1 and type 2 diabetes are regarded as clinically distinct diseases, several lines of evidence have suggested common genetic factors between the two types of diabetes. The non-obese diabetic (NOD) mouse, an animal model of type 1 diabetes, and the Nagoya-Shibata-Yasuda (NSY) mouse, a model of type 2 diabetes, are derived from the same outbred colony, Jcl:HCR, suggesting a shared susceptibility between the two types of diabetes in mice. Genetic as well as functional studies have supported the possibility that Tcf2, which encodes the transcription factor, hepatocyte nuclear factor 1beta (HNF-1beta), is a candidate gene for the common susceptibility between NSY and NOD mice. Txn, encoding thioredoxin which is a redox (reduction/oxidation)-active protein, is also a positional and functional candidate for a common susceptibility gene. To investigate whether either of these two genes is a common susceptibility gene, the coding nucleotide sequences of these two genes were compared among the NSY, NOD and control C3H strains. The coding sequence of Tcf2 of the NOD mouse was identical to that of the C3H mouse, but was different from that of the NSY mouse. The coding sequence of Txn was identical in the three strains. These data suggest that neither of the two genes is a common susceptiblity gene between type 1 and type 2 diabetes in mice.

Relative biological effectiveness of the 235 MeV proton beams at the National Cancer Center Hospital East

A therapy-dedicated cyclotron was installed in the National Cancer Center Hospital East (NCCHE) at Kashiwa in 1997. Prior to the start of clinical use, we investigated the biological effectiveness of therapeutic proton beams for cell lethality. The proton beams accelerated up to 235 MeV were horizontally extracted from the cyclotron, and scattered by a bar-ridge filter to produce a Spread-Out-Bragg-Peak (SOBP) of 10-cm width. The biological systems used here were mouse intestinal crypt cells and three in vitro cell lines, including SCC61 human squamous cell carcinoma, NB1RGB human fibroblasts and V79 Chinese hamster cells. The dose responses after irradiation at either the entrance plateau or the middle portion of SOBP were compared with those after linac 6 MV X-ray irradiation. The fit of a linear quadratic model to survival curves showed that proton irradiation increased the alpha value of SCC61 and the beta value of V79 cells with a least change for alpha/beta ratio of NB1RGB cells. The isoeffect dose that reduces either cell survivals to 10% or mouse jejunum crypts to 10 per circumference was termed D10. The relative biological effectiveness (RBE) of protons obtained by comparing the D10 values between protons and X-rays ranged from 0.9 to 1.2. The depth distribution of cell lethality was measured by replating V79 cells after irradiation from a "cell stack chamber" that received a single dose of 7 Gy at the middle position of SOBP. The thus-obtained cell survivals at various depths coincided well with the estimated survivals, but tended to decrease at the distal end of SOBP. We conclude that an RBE of 1.1 would be appropriate for 235 MeV proton beams at the NCCHE.

Induction by carbon-ion irradiation of the expression of vascular endothelial growth factor in lung carcinoma cells

PURPOSE

To investigate the induction by carbon- ion irradiation of vascular endothelial growth factor (VEGF) mRNA and protein.

MATERIALS AND METHODS

RERF-LC-AI lung squamous carcinoma cells were irradiated with carbon ions of either 13.3, 50 or 90keV/microm. Colony formation was used to determine cell survival. VEGF mRNA and protein of the irradiated cells were quantified by Northern blot analysis and ELISA assay, respectively. Genistein, Src tyrosine kinase inhibitor and H7, protein kinase C inhibitor, were used to inhibit VEGF mRNA expression.

RESULTS

The relative biological effectiveness (RBE) of carbon ions (13.3, 50 and 90keV/microm) was 1.10, 1.97 and 2.30, respectively, in terms of D10 values. Single doses of 15 Gy with either X-rays or carbon ions significantly induced VEGF mRNA expression at 16-24h after irradiation with a maximum induction of 2.81-fold. A significant increase was also observed in VEGF protein levels, detected in culture supernatant 24h after irradiation with 50 and 90keV/microm carbon ions. Neither mRNA nor protein induction showed a dependence on LET. The induction of VEGF mRNA by carbon-ion irradiation was completely inhibited by pretreating cells with genistein and H7, indicating that Src tyrosine kinase and protein kinase C on cell surface membranes is involved in the induction.

CONCLUSION

Irradiation of lung carcinoma cells with carbon ions induced VEGF mRNA expression and increased protein levels. The induction was dose-dependent. Radiation-induced DNA damage and/or its repair may not be a prerequisite for the induction of VEGF mRNA.

Calorie restriction and spontaneous hepatic tumors in C3H/He mice

Caloric restriction started at the young adult (YA) stage and the full adult (FA) stage in mice was compared, specifically focussing on whether there would be a delay in the onset time of spontaneous hepatoma or a reduction in its frequency. Caloric restriction lengthened the life spans of both groups, the YA, and FA. Both groups showed striking reductions of spontaneous hepatomas, from 70.9 +/- 3.5% for non-restricted controls down to 35.7 +/- 5.7 and 30.4 +/- 4.0%, for mice restricted from young adult, and from full adult stages, respectively; further, the numbers of tumor-free mice in the restricted groups increased by 45.7% and 38.5%, respectively, from 11.5%, in the non-restricted control. The cumulative incidences of hepatoma in the caloric restricted groups showed a delayed and lower incidence compared with those of the non-restricted group; a parallel delay might result from a weakened activity in tumor-promotion, whereas a lower frequency, might reflect a possible reduction of target cells for hepatomata development. Both effects can be assumed to have resulted from caloric restriction. When cumulative incidences of small hepatomas were compared between the two restricted groups, restriction started at the young adult stage is assumed to have caused fewer initiation stresses, as well as to have delayed promotion, as clearly evidenced by a flatter curve of incidence with a lower total incidence. Thus, the time at which caloric restriction is started plays a critical role in its subsequent effects.

Age-dependent changes in phenotypes and candidate gene analysis in a polygenic animal model of Type II diabetes mellitus; NSY mouse

AIMS/HYPOTHESIS

The Nagoya-Shibata-Yasuda (NSY) mouse closely mimics human Type II (non-insulin-dependent) diabetes mellitus in that the onset is age-dependent, the animals are not severely obese, and both insulin resistance and impaired insulin response to glucose contribute to disease development. The aim of this study was to clarify the influence of age on the pathogenesis of diabetes and to analyse a candidate gene for Type II diabetes in this strain.

METHODS

Several phenotypic characteristics related to diabetes mellitus were monitored longitudinally in male NSY and control C3H/He mice. The nucleotide sequence of Glut4, a candidate gene for Nidd1nsy (a susceptibility gene for Type II diabetes) on Chromosome 11, encoding insulin-sensitive glucose transporter, was determined in NSY and C3H mice.

RESULTS

Glucose intolerance worsened with age, and fasting blood glucose and fasting plasma insulin concentration increased with age in NSY mice. Pancreatic insulin content increased until 24 weeks of age but then decreased at 48 weeks of age in NSY mice. The hypoglycaemic response to insulin was statistically significantly smaller in NSY than in C3H/He mice. The nucleotide sequence of GLUT4 cDNA was identical in NSY and C3H/He mice, but both were different from the sequence reported previously.

CONCLUSION/INTERPRETATION

Insulin secretion and insulin resistance, as well as ageing possibly play an important part in the disease development in NSY mice. A decline of pancreatic insulin content in older age might cause the relative insulin deficiency in this strain. Nucleotide sequencing suggests that Glut4 is unlikely to be a candidate gene for Nidd1nsy.

Acid-sensitive and alkaline-sensitive sensory neurons regulate pH dependent gastrin secretion in rat

We examined the role of capsaicin-sensitive afferent neurons in pH-dependent gastrin secretion in the rat stomach. The change in serum gastrin levels relative to changes in luminal pH (using omeprazole for luminal alkalization or 0.1 N HCl for luminal acidification) was studied after oral administration of 4% lidocaine or capsaicin-induced ablation of afferent neurons. The increase of serum gastrin levels by luminal alkalization was significantly inhibited (50%) after administration of 4% lidocaine. Capsaicin pretreatment (125 mg/kg subcutaneously over two days) inhibited the change in serum gastrin levels both the luminal alkalization (38%) and acidification (66%). Antral gastrin contents, somatostatin contents, gastrin mRNA expression, and somatostatin mRNA expression were not significantly affected by capsaicin pretreatment. Our results indicate that capsaicin-sensitive afferent neurons participate in the secretion of gastrin by luminal alkalization and inhibition of gastrin by luminal acidification.

Age-related association of MHC class I chain-related gene A (MICA) with type 1 (insulin-dependent) diabetes mellitus

To assess the contribution of the HLA class I region to susceptibility to and heterogeneity of type 1 diabetes, we investigated the association of polymorphism of MHC class I chain-related gene A (MICA) with age-at-onset as well as susceptibility to type 1 diabetes. One hundred one Japanese patients and 110 healthy control subjects were studied. The frequency of A4 allele was significantly higher and that of A6 allele was significantly lower in patients than in control subjects. The frequency of A5.1 allele was highest in early-onset patients (23.0%), intermediate in intermediate-onset patients (9.2%) and lowest in late-onset patients (7.7%) (trend chi-squared test, p = 0.0098). A5. 1 allele was strongly associated with HLA-B7 and Cw7, suggesting that MICA*A5.1-B7-Cw7 haplotype contains a gene responsible for age-at-onset. A4 allele was associated with a susceptible haplotype, DR4-DQB1*0401, and A6 allele was associated with a protective haplotype, DR2-DQB1*0601, suggesting that the association of MICA with type 1 diabetes susceptibility may be due to linkage disequilibrium with class II haplotypes. These data suggest that MICA gene is associated with age-at-onset and that a gene (or genes) responsible for age-at-onset of type 1 diabetes is located in the HLA class I region, probably near the region of MICA-B-C.

Paternal-maternal effects on phenotypic characteristics in spontaneously diabetic Nagoya-Shibata-Yasuda mice

The Nagoya-Shibata-Yasuda (NSY) mouse is an inbred strain with spontaneous development of type 2 (non-insulin-dependent) diabetes mellitus. The purpose of this study was to determine the mode of inheritance of various phenotypes related to diabetes in this strain. Two reciprocal outcrosses, female C3H/He x male NSY F1 (C3NF1) and female NSY x male C3H/He F1 (NC3F1) mice, were performed. The phenotypic characteristics in both F1 mice were investigated. The cumulative incidence of diabetes was 100% (25 of 25) in male C3NF1 mice and 97% (29 of 30) in male NC3F1 mice at 48 weeks of age, indicating that diabetes in NSY mice was transmitted to male F1 hybrids in an autosomal dominant manner. Fatty liver also showed an autosomal dominant mode of inheritance. In contrast, epididymal fat accumulation and impaired insulin secretion showed an autosomal recessive mode of inheritance. The body mass index (BMI) showed a codominant mode of inheritance. Paternal-maternal effects associated with the severity of diabetes were observed. Insulin resistance was much more severe in male F1 mice than in the parental NSY strain. These data indicate different modes of inheritance among phenotypes related to type 2 diabetes. The presence of more severe insulin resistance in F1 mice versus the parental strains suggests the interaction of both parental genomes in the development of insulin resistance. The F1 mouse is expected to be useful for studies of the pathogenesis and genetic synergism of the insulin resistance syndrome.

Effects of carbon ions on primary cultures of mouse brain cells

Primary mixed cultures of astrocytes and microglia were obtained from neonatal mice, and were irradiated with high-LET carbon ions. Immunohistochemical staining showed astrocytes survived more prominently than microglia. Tagged with specific antibodies, astrocytes and microglia surviving after irradiation were counted by flow cytometry. Decreases in the number of microglia and astrocytes were detected at a dose as small as 2 Gy when Day 5 cultures were irradiated with 13 keV/micrometer carbon ions. When the cultures were irradiated on Day 10, the dose-dependent decrease of microglia was more prominent for 13 keV/micrometer carbon ions than 70 keV/micrometer carbon ions. Astrocytes showed a marginal decrease at Day 10 and Day 14. We concluded that microglia are more sensitive than astrocytes to carbon ions and X-rays, and that the radiosensitivity of microglia depends on both differentiation/proliferation status and radiation quality.

Electronic structure and cytotoxic activity of "half-mustard type" phenothiazines by MM3 and PM3 methods

Among 54 cancer cell lines, colon-cancer cells were the most sensitive to six "half-mustard type" phenothiazines [7-12], followed by leukemia, melanoma, prostate-, CNS-, breast-, lung-, renal and ovarian cancer cells. The distribution of electrostatic potential (ESP) of "half-mustard type" phenothiazines [7-12] suggests that the ESP surface of urea site is important for the interaction between "half-mustard type" phenothiazines [7-12] and target cancer cell structures (or DNA base sequence). Actually, the urea site of "half-mustard type" phenothiazines displayed extensive variability in the energy of lone pair orbital and net atomic charges of N1, 0 and N3 atoms.

Association of plasma fibrinogen level and blood pressure with diabetic retinopathy, and renal complications associated with proliferative diabetic retinopathy, in Type 2 diabetes mellitus

AIM

To clarify the association of several clinical parameters, including plasma fibrinogen level, with diabetic retinopathy in patients with Type 2 diabetes mellitus (DM).

METHODS

A total of 294 Japanese patients with Type 2DM were studied; 53 patients with no diabetic retinopathy (NDR), 90 with background diabetic retinopathy (BDR), and 151 with proliferative diabetic retinopathy (PDR). Multiple logistic regression analysis was performed to assess variables independently associated with diabetic retinopathy in two settings: presence of retinopathy of any severity and presence of advanced retinopathy.

RESULTS

The following parameters were identified as independent factors associated with the presence of diabetic retinopathy (NDR vs. BDR + PDR): type of therapy (P<0.0005), log-transformed plasma fibrinogen level (P < 0.05), mean blood pressure (P < 0.05), and duration of diabetes (P < 0.05). The independent variables associated with advanced retinopathy were type of therapy (P<0.00005), age (P<0.0005) and nephropathy (P<0.05). Body mass index, smoking and hypertensive status, HbA1c and total cholesterol levels were not independently associated.

CONCLUSIONS

These data suggest that in patients with Type 2 DM, an increased blood viscosity due to high fibrinogen level as well as an elevated intravessel pressure play a role in the development of diabetic retinopathy, and that the progression to PDR is influenced or accompanied by the deterioration of renal status.

Accelerated reoxygenation of a murine fibrosarcoma after carbon-ion radiation

PURPOSE

Reoxygenation of a murine tumour after irradiation with carbon ions was investigated and compared to that after gamma-rays.

MATERIALS AND METHODS

NFSa fibrosarcoma cells were transplanted into the right hind legs of syngeneic C3H male mice. Conditioning irradiation with either 290 MeV/u carbon ions or 137-Cs gamma-rays was delivered to the tumours at 8 mm diameter. At given times after irradiation the leg tumours, either clamped or not, received test doses of photons. Differences in tumour growth delay between the clamped and non-clamped tumours were interpreted in terms of reoxygenation. A lung-colony assay was used to obtain cell-survival curves.

RESULTS

The oxygen enhancement ratio in the NFSa tumour for 74 keV microm(-1) carbon ions was 1.6 while that for gamma-rays was 3.4. The NFSa tumours reoxygenated 4 days after 30 Gy of gamma-ray irradiation, but reoxygenated as early as 1 day after 16 Gy of carbon ions. Reoxygenation after gamma-rays shortened to 1 day when the tumours were initially clamped for the conditioning irradiation.

CONCLUSIONS

The fraction of surviving oxic cells in the NFSa tumours is larger after irradiation with carbon ions than with gamma-rays, resulting in accelerated reoxygenation.

Evidence for mRNA expression of vascular endothelial growth factor by X-ray irradiation in a lung squamous carcinoma cell line

Vascular endothelial growth factor (VEGF) is a multipotent cytokine which plays an important role in various angiogenic conditions as well as in some tumor behaviors. Here we examined the induction of VEGF mRNA by X-ray irradiation in a lung squamous cell carcinoma cell line (RERF-LC-AI). Irradiating the cells with 15 Gy X-rays significantly increased the mRNA expression up to 2.5-fold of control at a post-irradiation time of 16-24 h. The induction of VEGF mRNA by X-ray irradiation was completely blocked by treating cells with either genistein (Src tyrosine kinase inhibitor) or H7 (protein kinase C inhibitor). This suggests that the mechanism of induction might be concerned with the pathway which triggers Src tyrosine kinase of the cell surface and the protein kinase C pathway.

Hepatocyte nuclear factor-1alpha gene and non-insulin-dependent diabetes mellitus in the Japanese population

Recently, hepatocyte nuclear factor-1alpha(HNF-1alpha, which is encoded by the TCF1 gene) mutations were reported in a subset of patients with maturity onset diabetes of the young (MODY3). We studied the contribution of TCF1 to genetic susceptibility to common non-insulin-dependent diabetes mellitus (type 2) in Japanese subjects by investigating allelic association with type 2 diabetes use of three markers. We also studied the frequency of the G191D mutation, the only mutation of TCF1 reported so far in late-onset type 2 diabetes. A total of 356 subjects were studied. There were no significant differences in allele frequency of the three markers between patients with type 2 diabetes and control subjects. A G191D mutation was not found in the subjects studied, giving a frequency of less than 0.4% in common type 2 diabetes. The lack of association of type 2 diabetes with three markers in and near TCF1 suggests that mutations in TCF1 derived from a limited number of founders are not a major cause of common type 2 diabetes even in the genetically homogeneous Japanese population. The data also indicate that the G191D mutation in TCF1 plays little, if any, role in susceptibility to common type 2 diabetes in the Japanese.

Relationships between mandibular symphysis morphology and lower incisor inclination in skeletal class III malocclusion requiring orthognathic surgery

The purpose of this study is to clarify symphysis morphological characteristics in skeletal class III malocclusion requiring orthognathic surgery and their relationships with symphysis morphology and inclination of the long axis of the lower incisor. The materials were pretreatment lateral cephalometric radiographs from 50 subjects diagnosed as requiring orthognathic surgery. Controls were 30 adults with normal occlusion and well-balanced faces. Detailed cephalometric measurements on the mandibular symphysis (angular, linear and proportional measurements) were recorded and analyzed statistically. In the surgical group, the long axis of the lower incisor demonstrated a significant lingual inclination in relation to the mandibular plane and symphysis. Moreover, because the symphysis demonstrated lingual inclination everywhere except in the basal bone region in relation to the mandibular plane, the curvature between the alveolar and the basal bone region was significantly smaller than that of normal occlusion group. The symphysis labial external surface in the alveolar and basal bone regions demonstrated lingual inclination in relation to the mandibular plane, however, there was no difference in curvature. Small mean values were obtained for Pt.B width, Pog width, and Sym height. Significant differences were observed only in Pt.B width. In both the surgical and normal occlusion groups, a significant correlation was observed between the inclination of the long axis of the lower incisors and symphysis inclination. In the basal bone region, however, there was no significant correlation.

Asp905Tyr polymorphism of the gene for the skeletal muscle-specific glycogen-targeting subunit of protein phosphatase 1 in NIDDM

OBJECTIVE

To clarify the contribution of the Asp905Tyr polymorphism of the muscle-specific glycogen-targeting subunit of protein phosphatase 1 (PP1G) to insulin resistance and related diseases.

RESEARCH DESIGN AND METHODS

We investigated the Asp905Tyr polymorphism of the PPP1R3 gene, which encodes the muscle-specific glycogen-targeting subunit of PP1G, in 259 Japanese patients with NIDDM and 194 healthy control subjects.

RESULTS

No significant difference was found in the genotype distribution between NIDDM patients (N = 259; Asp/Asp = 0.10, Asp/Tyr = 0.44, Tyr/Try = 0.46) and healthy control subjects (n = 194; Asp/Asp = 0.13, Asp/Tyr = 0.37, Tyr/Tyr = 0.50) or between patient groups subdivided by the mode of treatment: NIDDM patients with insulin therapy (Asp/Asp = 0.14, Asp/Tyr = 0.46, Tyr/Tyr = 0.40) and those without insulin therapy (Asp/Asp = 0.07, Asp/Tyr = 0.43, Tyr/Tyr = 0.50). However, NIDDM patients with the Tyr allele, which was previously reported to be associated with insulin resistance, tended to have lower BMIs than those without this allele (Asp/Asp: 24.5 +/- 1.1 kg/m2, Asp/Tyr: 22.6 +/- 0.4 kg/m2, Tyr/Tyr: 22.8 + 0.3 kg/m2, P = 0.06 by analysis of variance).

CONCLUSIONS

These data suggest that the Asp905Tyr polymorphism of the PPP1R3 gene is not associated with NIDDM or high BMI, both of which are known to be insulin-resistant states, in the Japanese population.

Mouse skin reactions following fractionated irradiation with carbon ions

PURPOSE

Skin reactions in the mouse leg following various daily doses given with 290 MeV/u carbon ions were investigated.

MATERIALS AND METHODS

Seven different LET (linear energy transfer) values ranging from 14 to 100keV/microm were selected. The fractionation schedules were 1-, 2-, 4- and 8-daily fractions. The isoeffect doses to produce moist desquamation on the dose-response curves were calculated with 95% confidence limits.

RESULTS

The isoeffect doses for carbon ions of 14 and 20 keV/microm increased with an increase in the number of fractions up to 4 fractions, but became constant when the number of fractions further increased to 8 fractions. This leveling off in isoeffect dose was more prominent for 40 keV/microm. Recovered dose per fraction was largest for 2 fractions of the 14keV/microm carbon beam. The isoeffect doses for 50, 60, 80 and 100keV/microm consistently increased with an increase in the number of fractions and did not show saturation up to 8 fractions. RBE (relative biological effectiveness) increased linearly with LET for all fractionation schedules.

CONCLUSIONS

These results suggest that daily fractionation with carbon ions could spare radiation damage in patients, and that changes the fractionation schedule affect clinical outcome.

Association of distal chromosome 2q with IDDM in Japanese subjects

An insulin-dependent diabetes mellitus (IDDM)-susceptibility gene (IDDM13) has recently been mapped to a region of distal chromosome 2q, which is syntenic to the region of mouse chromosome 1 containing a murine susceptibility gene for IDDM, Idd5. To determine the contribution of this region to IDDM disease susceptibility further and to narrow the region for positional cloning of susceptibility genes, we have studied the association of distal chromosome 2q with IDDM in the genetically distinct Japanese population. A 137 mobility unit (mu) allele at D2S137 locus was significantly associated with IDDM (odds ratio 1.92, p = 0.0016). Other markers, D2S301 and D2S143, located in the same region were not associated with IDDM, indicating that IDDM13 is in linkage disequilibrium with D2S137, but not with D2S301 or D2S143. The association of D2S137 with IDDM was observed in patients lacking one of two high risk HLA alleles, DQBI*0303 and DQBI*0401, but not in patients with either of these alleles. The frequency of high risk HLA alleles was significantly lower in patients with the susceptible allele at D2S137, suggesting that IDDMI3 contributes to IDDM susceptibility in subjects without high risk genotypes at IDDM1. Demonstration of allelic association of D2S137 with IDDM localizes IDDM13 in the close vicinity (<2 centiMorgans) of D2S137, greatly facilitating fine structure mapping and positional cloning of IDDM13.

Calorie restriction reduces the incidence of myeloid leukemia induced by a single whole-body radiation in C3H/He mice

Dietary restriction, especially caloric restriction, is a major modifier in experimental carcinogenesis and is known to decrease significantly the incidence of neoplasms. Gross and Dreyfuss [Gross, L. & Dreyfuss, Y. (1984) Proc. Natl. Acad. Sci. USA 81, 7596-7598; Gross, L. & Dreyfuss, Y. (1986) Proc. Natl. Acad. Sci. USA 83, 7928-7931] reported that a 36% restriction in caloric intake dramatically decreased the radiation-induced solid tumors and/or leukemias. Their protocol predominantly produced lymphatic neoplasms. It is of interest to observe the effect of caloric restriction on radiation-induced myeloid leukemia, because the disease was observed to have been increased in the survivors of the atomic bombs in Hiroshima and Nagasaki. The spontaneous incidence of myeloid leukemia in C3H/He male mice is 1%, and the incidence increased to 23.3% when 3 Gy of whole-body x-ray irradiation was given. However, the incidence of myeloid leukemia was found to be significantly decreased by caloric restriction; it was reduced to 7.9% and 10.7% when restriction was started before (6 weeks old) and after (10 weeks old) irradiation, respectively. In addition, the onset of the myeloid leukemia in both restricted groups was prolonged to a greater extent as compared with the control diet group. Caloric restriction demonstrated a significant prolongation of the life span in the groups on a restricted diet after having been exposed to irradiation, either before or after dietary restriction, in comparison with mice that were only irradiated.