Identification of six novel susceptibility loci for dyslipidemia by longitudinal exome-wide association studies in Japanese

Background

The circulating concentrations of triglycerides, high density lipoprotein (HDL)-cholesterol, and low density lipoprotein (LDL)-cholesterol have a substantial genetic component. Although previous genome-wide association studies identified various genes and loci related to plasma lipid levels, those studies were conducted in a cross-sectional manner.

Purpose

The purpose of the study was to identify genetic variants that confer susceptibility to hypertriglyceridemia, hypo-HDL-cholesterolemia, and hyper-LDL-cholesterolemia in Japanese. We have now performed longitudinal exome-wide association studies (EWASs) to identify novel loci for dyslipidemia by examining temporal changes in serum lipid profiles.

Methods

Longitudinal EWASs (mean follow-up period, 5 years) for hypertriglyceridemia (2056 case, 3966 controls), hypo-HDL-cholesterolemia (698 cases, 5324 controls), and hyper-LDL-cholesterolemia (2769 cases, 3251 controls) were performed with Illumina Human Exome arrays. The relation of genotypes of 24,691 single nucleotide polymorphisms (SNPs) that passed quality control to dyslipidemia-related traits was examined with the generalized estimating equation (GEE). To compensate for multiple comparisons of genotypes with each of the three conditions, we applied Bonferroni's correction for statistical significance of association. Replication studies with cross-sectional data were performed for hypertriglyceridemia (2685 cases, 4703 controls), hypo-HDL-cholesterolemia (1947 cases, 6146 controls), and hyper-LDL-cholesterolemia (1719 cases, 5833 controls).

Results

Longitudinal EWASs revealed that 30 SNPs were significantly (P<2.03 × 10–6 by GEE) associated with hypertriglyceridemia, 46 SNPs with hypo-HDL-cholesterolemia, and 25 SNPs with hyper-LDL-cholesterolemia. After examination of the relation of identified SNPs to serum lipid profiles, linkage disequilibrium, and results of the previous genome-wide association studies, we newly identified rs74416240 of TCHP, rs925368 of GIT2, rs7969300 of ATXN2, and rs12231744 of NAA25 as a susceptibility loci for hypo-HDL-cholesterolemia; and rs34902660 of SLC17A3 and rs1042127 of CDSN for hyper-LDL-cholesterolemia. These SNPs were not in linkage disequilibrium with those previously reported to be associated with dyslipidemia, indicating independent effects of the SNPs identified in the present study on serum concentrations of HDL-cholesterol or LDL-cholesterol in Japanese. According to allele frequency data from the 1000 Genomes project database, five of the six identified SNPs were monomorphic or rare variants in European populations. In the replication study, all six SNPs were associated with dyslipidemia-related phenotypes.

Conclusion

We have thus identified six novel loci that confer susceptibility to hypo-HDL-cholesterolemia or hyper-LDL-cholesterolemia. Determination of genotypes for these SNPs at these loci may prove informative for assessment of the genetic risk for dyslipidemia in Japanese.

Funding Acknowledgement

Type of funding source: None

Identification of two genes as novel susceptibility loci for type 2 diabetes mellitus in Japanese

Background

The heritability of Type 2 diabetes mellitus (T2DM) has been estimated to be 50% to 60%. Although genome-wide association studies identified >120 loci that confer susceptibility to T2DM, these studies were commonly conducted in a cross-sectional manner.

Purpose

The purpose of the study was to identify genetic variants that confer susceptibility to T2DM in Japanese. We have now performed longitudinal exome-wide association studies (EWASs) to identify novel loci for T2DM by examining temporal changes in fasting plasma glucose (FPG) level, blood hemoglobin A1c (HbA1c) content, and the prevalence of T2DM.

Methods

Longitudinal EWASs (mean follow-up period, 5 years) were performed with Illumina Human Exome-12 v1.2 DNA Analysis BeadChip or Infinium Exome-24 v1.0 BeadChip arrays and with 6,022 Japanese (755 subjects with T2DM, 5267 controls). The relation of genotypes of 24,579 SNPs that passed quality control to FPG level, blood HbA1c content, or the prevalence of T2DM was examined with the generalized estimating equation (GEE). To compensate for multiple comparisons of genotypes with each of the three parameters, we applied Bonferroni's correction for statistical significance of association.

Results

Longitudinal EWASs (GEE with adjustment for age, sex, body mass index, and smoking) revealed that rs6414624 of EVC (P<2.0×10–16 for T2DM, P=9.1×10–11 for FPG), rs78338345 of GGA3 (P<2.0×10–16 for T2DM, P=4.3×10–9 for FPG), rs10490775 of PTPRG (P<2.0×10–16 for T2DM, P=3.3×10–7 for FPG), and rs61739510 of GLT6D1 (P<2.0×10–16 for T2DM, P=5.8×10–7 for FPG) were significantly associated with the prevalence of T2DM and FPG levels; and rs11558471 in SLC30A8 with FPG level (P=1.8×10–8) and blood HbA1c content (P=1.2×10–7). After examination of the relation of identified SNPs to FPG level and blood HbA1c content, linkage disequilibrium of the SNPs, and results of the previous genome-wide association studies, we identified rs6414624 of EVC and rs78338345 of GGA3 as novel susceptibility loci for T2DM. In the identified SNPs (rs6414624 and rs7833834), FPG level, blood HbA1c content, and the prevalence of T2DM were significantly lower in homozygotes with the minor alleles than in homozygotes with the major alleles or heterozygotes. These results suggest that the minor alleles of rs6414624 and rs78338345 are protective against T2DM in Japanese. According to allele frequency data from the 1000 Genomes Project database, the minor G allele of rs78338345 of GGA3 is specifically distributed in East Asia. This suggests that the minor allele frequency may have increased in East Asian populations after the split of East Asian and non-East Asian populations.

Conclusion

We have newly identified EVC and GGA3 as susceptibility loci for T2DM in Japanese. Determination of genotypes for these SNPs at these loci may prove informative for assessment of the genetic risk for T2DM in Japanese.

Funding Acknowledgement

Type of funding source: None

P1542Identification of 13 novel susceptibility loci for early-onset myocardial infarction, hypertension, or chronic kidney disease in Japanese

Background

Early-onset cardiovascular and renal diseases have a strong genetic component.

Purpose

To identify genetic variants that confer susceptibility to early-onset myocardial infarction (MI), hypertension, or chronic kidney disease (CKD) in Japanese. We have performed exome-wide association studies (EWASs) in subjects with early-onset forms of these diseases.

Methods

A total of 8093 individuals aged ≤65 years was enrolled in the study. The EWASs for MI, hypertension, and CKD were conducted with 6926 subjects (1152 cases, 5774 controls), 8080 subjects (3444 cases, 4636 controls), and 2556 subjects (1051 cases, 1505 controls), respectively. Genotyping of single nucleotide polymorphisms (SNPs) was performed with Illumina Human Exome-12 DNA Analysis BeadChip or Infinium Exome-24 BeadChip arrays. The relation of allele frequencies for 31,245, 31,276, or 31,514 SNPs that passed quality control to MI, hypertension, and CKD, respectively, was examined with Fisher's exact test. Bonferroni's correction for statistical significance of association was applied to compensate for multiple comparisons of genotypes with MI, hypertension, or CKD.

Results

The EWASs of allele frequencies revealed that 25, 11, and 11 SNPs were significantly associated with MI (P<1.60 × 10–6), hypertension (P<1.60 × 10–6), or CKD (P<1.59 × 10–6), respectively. Multivariable logistic regression analysis with adjustment for covariates showed that all 25, 11, and 11 SNPs were significantly related to MI (P<0.0005), hypertension (P<0.0011), or CKD (P<0.0011), respectively. After examination of results from previous genome-wide association studies and linkage disequilibrium of the identified SNPs, we newly identified 11 loci (TMOD4, COL6A3, ADGRL3-CXCL8-MARCH1, OR52E4, TCHP-GIT2, CCDC63, 12q24.1, OAS3, PLCB2-VPS33B, GOSR2, ZNF77), six loci (MOB3C-TMOD4, COL6A3, COL6A5, CXCL8-MARCH1, NFKBIL1-6p21.3-NCR3, PLCB2-VPS33B), and seven loci (MOB3C-TMOD4, COL6A3, COL6A5, ADGRL3-CXCL8-MARCH1, MUC17, PLCB2-VPS33B, ZNF77) that were significantly associated with MI, hypertension, or CKD, respectively. Furthermore, six genes (TMOD4, COL6A3, CXCL8, MARCH1, PLCB2, VPS33B) were significantly associated with MI, hypertension, and CKD; two genes (ADGRL3, ZNF77) with MI and CKD; and two genes (COL6A5, MOB3C) with hypertension and CKD. Network analysis showed that the 13, 10, or 11 genes associated with MI, hypertension, or CKD, respectively, in the present study had direct or indirect interactions with the corresponding sets of 50 genes previously shown to be associated with MI, hypertension, or CKD.

Conclusion

We newly identified 13 loci (MOB3C-TMOD4, COL6A3, ADGRL3-CXCL8-MARCH1, OR52E4, TCHP-GIT2, CCDC63, 12q24.1, OAS3, PLCB2-VPS33B, ZNF77, COL6A5, NFKBIL1-NCR3, MUC17) that confer susceptibility to early-onset MI, hypertension, or CKD. Determination of genotypes for the SNPs at these loci may prove informative for assessment of the genetic risk for MI, hypertension, or CKD in Japanese.

P3718Identification of nine genes as novel susceptibility loci for early-onset ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage

Background

Given that substantial genetic components have been shown in ischemic stroke, intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH), a heritability may be higher in early-onset than late-onset individuals with these conditions. Although genome-wide association studies have identified various genes and loci significantly associated with ischemic stroke, ICH, or intracranial aneurysm mainly in European ancestry populations, genetic variants that contribute to susceptibility to these disorders in Japanese individuals remain to be identified definitively.

Purpose

The purpose of the study was to identify genetic variants that confer susceptibility to ischemic stroke, ICH, or SAH in Japanese. We have now performed exome-wide association studies (EWASs) in early-onset subjects with these conditions and corresponding controls.

Methods

A total of 6649 individuals aged ≤65 years were examined. For the EWAS of ischemic or hemorrhagic stroke, 6224 individuals (450 subjects with ischemic stroke, 5774 controls) or 6179 individuals (261 subjects with ICH, 176 subjects with SAH, 5742 controls), respectively, were examined. EWASs were performed with the use of Illumina Human Exome-12 v1.2 DNA Analysis BeadChip or Infinium Exome-24 v1.0 BeadChip. To compensate for multiple comparisons of allele frequencies with ischemic stroke, ICH, or SAH, we applied a false discovery rate (FDR) of <0.05 for statistical significance of association.

Results

The relation of allele frequencies of 31,245 single nucleotide polymorphisms (SNPs) that passed quality control to ischemic stroke was examined with Fisher's exact test, and 31 SNPs were significantly (FDR <0.05) associated with ischemic stroke. The relation of allele frequencies of 31,253 or 30,970 SNPs to ICH or SAH, respectively, was examined with Fisher's exact test, and six or two SNPs were significantly (FDR <0.05) associated with ICH or SAH, respectively. Multivariable logistic regression analysis with adjustment for age, sex, and the prevalence of hypertension and diabetes mellitus revealed that 12 SNPs were significantly [P <0.0004 (Bonferroni's correction, 0.05/124)] related to ischemic stroke. Similar analysis with adjustment for age, sex, and the prevalence of hypertension revealed that six or two SNPs were significantly [P <0.0016 (0.05/32)] related to ICH or SAH, respectively. After examination of linkage disequilibrium of identified SNPs and results of previous genome-wide association studies, we have newly identified HHIPL2, CTNNA3, LOC643770, UTP20, and TRIB3 as susceptibility loci for ischemic stroke, DNTTIP2 and FAM205A as susceptibility loci for ICH, and FAM160A1 and OR52E4 as such loci for SAH.

Conclusion

We have thus newly identified nine genes that confer susceptibility to early-onset ischemic stroke, ICH, or SAH. Determination of genotypes for the SNPs in these genes may prove informative for assessment of the genetic risk for ischemic stroke, ICH, or SAH in Japanese.

P5724Identification of 12 novel loci that confer susceptibility to early-onset dyslipidemia in Japanese

Background

The circulating concentrations of triglycerides, high density lipoprotein (HDL)–cholesterol, and low density lipoprotein (LDL)–cholesterol have a substantial genetic component, and the heritability of early-onset dyslipidemia is expected to be higher than that of late-onset forms of this condition.

Purpose

To identify genetic variants that confer susceptibility to early-onset hypertriglyceridemia, hypo–HDL-cholesterolemia, and hyper–LDL-cholesterolemia in Japanese. We have now performed exome-wide association studies (EWASs) for early-onset forms of these conditions.

Methods

A total of 8073 individuals aged ≤65 years was enrolled in the study. The EWASs for hypertriglyceridemia (2664 cases, 5294 controls), hypo–HDL-cholesterolemia (974 cases, 7085 controls), and hyper–LDL-cholesterolemia (2911 cases, 5111 controls) were performed with Illumina Human Exome-12 v1.2 DNA Analysis BeadChip or Infinium Exome-24 v1.0 BeadChip arrays. The relation of allele frequencies for 31,198, 31,133, or 31,175 single nucleotide polymorphisms (SNPs) that passed quality control to hypertriglyceridemia, hypo–HDL-cholesterolemia, or hyper–LDL-cholesterolemia, respectively, was examined with Fisher's exact test. To compensate for multiple comparisons of genotypes with each of the three conditions, we applied Bonferroni's correction for statistical significance of association.

Results

The EWASs of allele frequencies revealed that 25, 28, or 65 SNPs were significantly associated with hypertriglyceridemia (P<1.60 × 10–6), hypo–HDL-cholesterolemia (P<1.61 × 10–6), or hyper–LDL-cholesterolemia (P<1.60 × 10–6), respectively. Multivariable logistic regression analysis with adjustment for age and sex showed that all 25, 28, or 65 of these SNPs were significantly related to hypertriglyceridemia (P<0.0005), hypo–HDL-cholesterolemia (P<0.0004), or hyper–LDL-cholesterolemia (P<0.0002), respectively. After examination of the relation of the identified SNPs to serum concentrations of triglycerides, HDL-cholesterol, or LDL-cholesterol, linkage disequilibrium of the SNPs, and results of previous genome-wide association studies, we newly identified chromosomal region 19p12 as a susceptibility locus for hypertriglyceridemia, eight loci (MOB3C-TMOD4, LPGAT1, EHD3, COL6A3, ZNF860-CACNA1D, COL6A5, DCLRE1C, ZNF77) for hypo–HDL-cholesterolemia, and three loci (KIAA0319-FAM65B, UBD, LOC105375015) for hyper–LDL-cholesterolemia. Network analysis showed that the 10 or three genes associated with hypo-HDL-cholesterolemia or hyper-LDL-cholesterolemia, respectively, had direct or indirect interactions with the 50 genes previously shown to be associated with dyslipidemia.

Conclusion

We have thus identified 12 novel loci that confer susceptibility to early-onset dyslipidemia. Determination of genotypes for the SNPs at these loci may prove informative for assessment of the genetic risk for hypertriglyceridemia, hypo–HDL-cholesterolemia, or hyper–LDL-cholesterolemia in Japanese.

P4470Identification of four genes as novel susceptibility loci for early-onset type 2 diabetes mellitus, metabolic syndrome, or hyperuricemia in Japanese

Background

Given that early-onset type 2 diabetes mellitus (T2DM), metabolic syndrome, and hyperuricemia have been shown to have strong genetic components, statistical power of a genetic association study may be increased by focusing on early-onset subjects with these conditions. Although genome-wide association studies have identified various genes and loci significantly associated with T2DM, metabolic syndrome, and hyperuricemia, genetic variants that contribute to predisposition to these conditions in Japanese individuals remain to be identified definitively.

Purpose

The purpose of the study was to identify genetic variants that confer susceptibility to early-onset T2DM, metabolic syndrome, or hyperuricemia in Japanese. We have now performed exome-wide association studies (EWASs) for early-onset subjects with T2DM, metabolic syndrome, or hyperuricemia and corresponding controls.

Methods

A total of 8102 individuals aged ≤65 years was enrolled in the study. The EWAS for T2DM was performed with 7407 subjects (1696 cases, 5711 controls), that for metabolic syndrome with 4215 subjects (2296 cases, 1919 controls), and that for hyperuricemia with 7919 subjects (1365 cases, 6554 controls). Single nucleotide polymorphisms (SNPs) were genotyped with Illumina Human Exome-12 DNA Analysis BeadChip or Infinium Exome-24 BeadChip arrays. The relation of allele frequencies for 31,210, 31,521, or 31,142 SNPs that passed quality control to T2DM, metabolic syndrome, or hyperuricemia, respectively, was examined with Fisher's exact test. To compensate for multiple comparisons of genotypes with T2DM, metabolic syndrome, or hyperuricemia, we applied Bonferroni's correction for statistical significance of association.

Results

The EWAS of allele frequencies revealed that four, six, or nine SNPs were significantly associated with T2DM (P<1.60 × 10–6), metabolic syndrome (P<1.59 × 10–6), or hyperuricemia (P<1.61 × 10–6), respectively. Multivariable logistic regression analysis with adjustment for age and sex revealed that three, six, or nine SNPs were significantly related to T2DM (P<0.0031), metabolic syndrome (P<0.0021), or hyperuricemia (P<0.0014). After examination of the association of identified SNPs to T2DM-, metabolic syndrome-, or hyperuricemia-related traits, linkage disequilibrium of the SNPs, and results of previous genome-wide association studies, we have newly identified ZNF860 and OR4F6 as susceptibility loci for T2DM, OR52E4 and OR4F6 for metabolic syndrome, and HERPUD2 for hyperuricemia.

Conclusion

Given that OR4F6 was significantly associated with both T2DM and metabolic syndrome, we thus newly identified four genes (ZNF860, OR4F6, OR52E4, HERPUD2) that confer susceptibility to early-onset T2DM, metabolic syndrome, or hyperuricemia. Determination of genotypes for the SNPs in these genes may prove informative for assessment of the genetic risk for T2DM, metabolic syndrome, or hyperuricemia in Japanese.

P708Identification of 26 novel loci that confer susceptibility to early-onset coronary artery disease in a Japanese population

Background

Early-onset coronary artery disease (CAD) has a strong genetic component. Although genome-wide association studies have identified various genes and loci significantly associated with CAD mainly in European ancestry populations, genetic variants that contribute to susceptibility to this condition in Japanese individuals remain to be identified definitively.

Purpose

The purpose of the study was to identify genetic variants that confer susceptibility to early-onset CAD in Japanese. We have now performed exome-wide association studies (EWASs) in subjects with early-onset CAD and controls.

Methods

A total of 7256 individuals aged ≤65 years was enrolled in the study. The EWAS was conducted with 1482 subjects with CAD and 5774 controls. Genotyping of single nucleotide polymorphisms (SNPs) was performed with Illumina Human Exome-12 DNA Analysis BeadChip or Infinium Exome-24 BeadChip arrays. The relation of allele frequencies for 31,465 SNPs that passed quality control to CAD was examined with Fisher's exact test. To compensate for multiple comparisons of allele frequencies with CAD, we applied a false discovery rate (FDR) of <0.05 for statistical significance of association.

Results

The relation of allele frequencies for 31,465 SNPs to CAD with the use of Fisher's exact test showed that 170 SNPs were significantly (FDR <0.05) associated with CAD. Multivariable logistic regression analysis with adjustment for age, sex, and the prevalence of hypertension, diabetes mellitus, and dyslipidemia revealed that 162 SNPs were significantly (P<0.05) related to CAD. A stepwise forward selection procedure was performed to examine the effects of genotypes for the 162 SNPs on CAD. The 54 SNPs were significant (P<0.05) and independent [coefficient of determination (R2), 0.0008 to 0.0297] determinants of CAD. These SNPs together accounted for 15.5% of the cause of CAD. After examination of results from previous genome-wide association studies and linkage disequilibrium of the identified SNPs, we newly identified 21 genes (RNF2, YEATS2, USP45, ITGB8, TNS3, FAM170B-AS1, PRKG1, BTRC, MKI67, STIM1, OR52E4, KIAA1551, MON2, PLUT, LINC00354, TRPM1, ADAT1, KRT27, LIPE, GFY, EIF3L) and five chromosomal regions (2p13, 4q31.2, 5q12, 13q34, 20q13.2) that were significantly associated with CAD. Gene ontology analysis showed that various biological functions were predicted in the 18 genes identified in the present study. The network analysis revealed that the 18 genes had potential direct or indirect interactions with the 30 genes previously shown to be associated with CAD or with the 228 genes identified in previous genome-wide association studies of CAD.

Conclusion

We have newly identified 26 loci that confer susceptibility to CAD. Determination of genotypes for the SNPs at these loci may prove informative for assessment of the genetic risk for CAD in Japanese.

Dynamic 3D-CT angiography

BACKGROUND AND PURPOSE

3D-CT angiography (3D-CTA), a vessel-cast technique, is useful in the diagnosis of patients with brain lesions and cerebrovascular disease. However, it provides no information on blood-flow dynamics. Therefore, we developed a new technique, dynamic 3D-CTA (d3D-CTA), that yields 3D images of the vasculature and allows assessment of the hemodynamics and of the cerebral perfusion.

METHODS

We subjected 12 patients to d3D-CTA; 7 had brain tumors, 4 had arteriovenous malformations (AVMs), and 1 presented with cervical internal carotid artery occlusion. d3D-CTA was performed with a multidetector-row CT scanner with 64 detectors; the parameters were 0.5-mm section thickness, 0.5 seconds per rotation, 135 kV, and 150 mA. Contrast medium (total volume, 30-35 mL) was injected at 6-7 mL/s; scanning was started after a 5-second delay. Scans were generated with volume-rendering reconstruction and displayed in cine mode.

RESULTS

We succeeded in obtaining d3D-CTA scans in all cases. The scans yielded 3D information on the vascular structures and hemodynamics and on the status of the cerebral perfusion.

CONCLUSION

d3D-CTA facilitates the acquisition of information on the vascular and cerebral dynamic blood flow on 3D-CTA images. Despite the relatively high radiation exposure and contrast injection speed and its limited scan range, this technique is useful for the diagnosis of patients with brain tumors or cerebrovascular disease and for treatment planning.

Spinal evoked potentials following transcranial magnetic stimulation

Motor evoked potentials by magnetic stimulation is less invasive and causes no pain as opposed to high current electric stimulation. However, the distribution of the magnetic field generated by the round coil has not been fully studied. In this report, we mapped the extent of the magnetic induction flux density, and then the evoked potentials from the spinal cord were investigated by transcranial magnetic stimulation. We also examined the origin of the evoked potentials obtained by the magnetic stimulation. The following results were obtained. The magnetic induction flux density was at its maximum at the edge of the coil. The potentials consisted of a first negative wave and subsequent multiphasic waves. The first negative wave was similar to a response of the subcorticospinal tract in the lower brain stem, while the subsequent multiphasic waves were similar to those of the pyramidal tract. Although magnetic stimulation has certain advantages over electric stimulation, several problems remain to be solved for the monitoring of motor functions in the clinical settings.

All-solid-state, high-power, deep-UV laser system based on cascaded sum-frequency mixing in CsLiB6O10 crystals

We report on an efficient use of CsLiB6O10 (CLBO) crystals employed for an all-solid-state deep-UV laser system operated at 5 kHz. We obtained greater than 3 W of UV radiation around 242 nm by mixing the 349-nm third harmonic of a Nd:YLF laser with the tunable output from a Ti:sapphire laser in a CLBO crystal. This UV radiation was subsequently mixed with the residual 1047-nm output from the Nd:YLF laser in a second CLBO crystal. The system produced 1.5 W of deep-UV radiation at 196.3 nm, which is, to our knowledge, the highest deep-UV power below 200 nm generated in a nonlinear optical crystal. Additionally, the bandwidth of both outputs was estimated to be less than 200 MHz.

GABA increases refractoriness of adult rat dorsal column axons

We applied randomized double pulse stimulation for assessing the effects of GABA and a GABAA antagonist on compound action potentials in dorsal column axons isolated from adult rat. We stimulated the axons with double pulses at 0.2 Hz and randomly varied interpulse intervals between 3, 4, 5, 8, 10, 20, 30, 50 and 80 ms. Action potentials were measured using glass micropipettes. The first pulse was used to condition the response activated by the second test pulse. Concentrations of GABA of 1 mM, 100 microM and 10 microM did not affect action potential amplitudes or latencies activated by conditioning pulses. In the control studies, before drug administration, test pulses induced response amplitudes that were significantly decreased at 3-, 4- and 5-ms interpulse intervals. The test action potential amplitudes were 84.6 +/- 2.5%, 89.0 +/- 3.9% and 93.3 +/- 3.6% (mean +/- S.E.M.) of conditioning pulse levels, respectively. At 3-ms interpulse intervals, test response latencies were prolonged to 104.3 +/- 1.0%, but were unchanged at the other interpulse intervals. The 10 microM, 100 microM and 1 mM concentrations of GABA affected test response amplitudes. Application of 100 microM GABA reduced the amplitudes of test responses at 3-, 4-, 5- and 8-ms interpulse intervals, to 59.2 +/- 3.0%, 70.0 +/- 3.0%, 80.2 +/- 1.1% and 88.6 +/- 3.6% of the conditioning pulse amplitudes, respectively. At both 100 microM and 1 mM concentrations, GABA significantly prolonged the latencies of test responses. Treatment with 100 microM GABA prolonged the latencies of test responses at 3-, 4- and 5-ms interpulse intervals, to 119.3 +/- 3.1%, 107.3 +/- 2.8% and 105.5 +/- 2.5% of conditioning pulse latencies, respectively. The addition of 100 microM bicuculline methochloride, a GABAA antagonist, eliminated the effects of 100 microM GABA. The combined application of GABA and bicuculline (both 100 microM) did not affect amplitudes or latencies of test responses. These results suggest that GABA(A) receptor subtypes are present on the spinal dorsal column axons of adult rat, and that they modulate the excitability of the axons. The randomized double pulse methods reveal that GABA increases refractoriness of adult rat dorsal column axons.

Evidence for serotonin sensitivity of adult rat spinal axons: studies using randomized double pulse stimulation

We have recently shown both inhibitory and excitatory effects of serotonin on neonatal rat dorsal column axons. While neonatal rat dorsal column axons also respond to norepinephrine and GABA, adult rat dorsal columns are insensitive to the actions of both compounds. Therefore, we studied the effects of serotonin agonists on adult rat dorsal column axons using randomized double pulse stimuli at 0.2 Hz with random interpulse intervals of 3, 4, 5, 8, 10, 20, 30, 50 and 80 ms. The serotonin(1A) agonist, 8-hydroxy-dipropylaminotetralin-hydrobromide (8-OH-DPAT), significantly modulated test response amplitudes at 3, 4, 5 and 8 ms interpulse intervals by 29.6+/-4.0%, 17.4+/-2.1%, 9.6+/-2.3%, and 12.4+/-2.2% of conditioning pulse amplitudes, respectively. The mean latencies at 3, 4 and 5 ms interpulse intervals increased by 17.0+/-5.1%, 8.6+/-2.1%, and 5.1+/-1.4%, respectively (P<0.05). However, neither 10 microM 8-OH-DPAT nor 100 microM serotonin hydrochloride affected the compound action potentials evoked by conditioning or test pulses. In contrast, treatment with 100 microM quipazine dimaleate (a serotonin(2A) agonist) decreased the refractory period. While the response amplitudes to a 3-ms double pulse were reduced by 11.0+/-1.5% during the control period, the test response fell to only 2.4+/-1.8% of the conditioning response amplitudes after exposure to 100 microM quipazine. 8-OH-DPAT decreased the amplitude, prolonged the latency and increased the refractory periods of compound action potentials in the adult rat dorsal column, although a high concentration of the agonist (100 microM) was required for these effects. In contrast, the serotonin(2A) agonist, quipazine, decreased refractory periods. These results suggest that both serotonin(1A) and serotonin(2A) receptor subtypes are present on adult spinal dorsal column axons. Further, these receptors have opposing effects on axonal excitability, despite the fact that their sensitivities are relatively low.

Axonal regeneration through an autogenous nerve bypass: an experimental study in the rat

Neuroma-in-continuity can manifest itself not only as pain but also as incomplete return of motor and sensory nerve function. The mainstay of current treatment for peripheral neuromas employs neurolysis or segmental resection with interposition grafting. These techniques are complicated by the loss of the remaining conduction through intact fibers within the injured segment. Based on the recent finding that end-to-side neurorrhaphies demonstrate axonal growth, we studied the use of a nerve "bypass" graft as a possible alternative to neurolysis or segmental resection with interposition grafting. A sciatic nerve crush injury model was induced in the Sprague-Dawley rat by compression with a straight hemostat. Epineurial windows were created proximal and distal to the injury. An 8-mm segment of radial nerve was harvested and anastomosed to the sciatic nerve at the epineurial window sites proximal and distal to the compressed segment (bypass group). A sciatic nerve crush injury without bypass served as a control. Electrophysiological testing and gate studies were performed over an 8-week period. Sciatic nerves were then harvested en bloc and studied under transmission electron microscopy at 1250 times magnification. Myelinated and unmyelinated axon counts were obtained. Nerve conduction velocity in the bypass group was significantly faster than conduction velocity in the control group at 8 weeks (44.8 m per second vs. 36.4 m per second; p = 0.031). We found no difference in myelinated axon counts between the proximal and distal segments of the control sciatic nerve. In the experimental sciatic nerve, a 160% increase in the number of myelinated axons was noted in the distal segment. Significant axonal growth was noted in the bypass nerve segment itself. Gait analysis using the sciatic functional index revealed improved function of the bypass group compared to the control group, but this was not statistically significant. Nerve bypass may serve to augment peripheral axonal growth while avoiding further loss of the native nerve.

Independent depressive mechanisms of GABA and (+/-)-8-hydroxy-dipropylaminotetralin hydrobromide on young rat spinal axons

We compared the effect of GABA and the serotonin receptor agonist (+/-)-8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT) on compound action potential amplitudes, latency, and conduction velocity in the spinal cord isolated from young (eight to 13-day-old) Long-Evans hooded rats. Supramaximally activated conducting action potentials and extracellular K+ activity were recorded with microelectrodes from the cuneatus-gracilis fasciculi and corticospinal tract. In the cuneatus-gracilis fasciculi, 8-OH-DPAT (10(-4) M) significantly reduced response amplitudes by 26.1 +/- 10.3% (mean +/- S.D., P < 0.0001, paired t-test, n = 27) and increased latencies by 20.3 +/- 7.9% (P < 0.0001). GABA (10(-4) M) reduced/amplitudes by 31.7 +/- 15.0% (P < 0.0001, n = 28) and increased latencies by 6.1 +/- 5.4% (P < 0.0001). However, neither GABA nor 8-OH-DPAT significantly altered conduction velocities, suggesting that the latency shifts are due to changes in activation time and not conduction velocity. In cortical spinal tract, 8-OH-DPAT (10(-4) M) depressed response amplitudes by 18.9 +/- 9.6% (P < 0.05, n = 5), increased latencies by 23.3 +/- 7.2% (P < 0.0001), but reduced conduction velocities by 19.9 +/- 10.2%. GABA (10(-4) M) reduced amplitudes by 16.4 +/- 7.5% (P < 0.01, n = 5), increased latencies by 5.3 +/- 2.3% (P < 0.05), and did not change conduction velocities. Bicuculline or picrotoxin blocked the GABA effects but did not affect the 8-OH-DPAT effects on both tracts. The potassium channel blocker tetraethylammonium did not alter the 8-OH-DPAT effects. The Na+/K(+)-ATPase inhibitor ouabain (10(-6) M) markedly enhanced the depressive GABA effects from 27.9 +/- 12.0% to 49.4 +/- 24.5% (P < 0.01, n = 9), but had no effect on 8-OH-DPAT-mediated effects. These results suggest that GABA and serotonin agonists depress axonal excitability through different and independent mechanisms.

A histologically distinctive interstitial pneumonia induced by overexpression of the interleukin 6, transforming growth factor beta 1, or platelet-derived growth factor B gene

Interstitial pneumonia is characterized by alveolitis with resulting fibrosis of the interstitium. To determine the relevance of humoral factors in the pathogenesis of interstitial pneumonia, we introduced expression vectors into Wistar rats via the trachea to locally overexpress humoral factors in the lungs. Human interleukin (IL) 6 and IL-6 receptor genes induced lymphocytic alveolitis without marked fibroblast proliferation. In contrast, overexpression of human transforming growth factor beta 1 or human platelet-derived growth factor B gene induced only mild or apparent cellular infiltration in the alveoli, respectively. However, both factors induced significant proliferation of fibroblasts and deposition of collagen fibrils. These histopathologic changes induced by the transforming growth factor beta 1 and platelet-derived growth factor B gene are partly akin to those changes seen in lung tissues from patients with pulmonary fibrosis and markedly contrast with the changes induced by overexpression of the IL-6 and IL-6 receptor genes that mimics lymphocytic interstitial pneumonia.

Expression of hepatitis C virus core protein as a fusion protein with maltose binding protein. Detection of anti-hepatitis C core antibody by western blot

Putative hepatitis C virus core sequence was amplified from a serum sample positive for anti-C-100-3 and expressed in Escherichia coli. Approximately 62 kDa fusion protein with maltose binding protein containing 20 kDa hepatitis C core protein was obtained. The antibody to this protein was detected in 53 of 54 (98%) sera from hepatitis C virus ribonucleic acid-positive patients including 40 sera positive for anti-C-100-3 and 13 sera negative for anti-C-100-3. The antibody was also detected in all of 12 patients with acute hepatitis C showing the earlier detectability of the antibody than anti-C-100-3. Thus, the protein expressed from the amplified hepatitis C core sequence by the polymerase chain reaction would be useful for the diagnosis of hepatitis C.

[All-trans retinoic acid induced a complete remission in a case of refractory relapsed acute promyelocytic leukemia]

Forty five year old male suffering from relapsed acute promyelocytic leukemia (APL) was treated with all-trans retinoic acid (ATRA) and attained second complete remission (CR) without bone marrow hypoplasia. He was diagnosed as having APL in September 1989. The DCMP-85 regimen first induced CR in October, however the disease relapsed in September 1990. The DCMP-85 and and the MEC (MIT, ETOP, Ara-C) regimens were applied for re-induction without success. Then, 45 mg/m2/day ATRA was given orally from December 28, 1990. Laboratory data before ATRA treatment were as follows; 35.4% leukemic cells in the bone marrow, Hb 11.0 g/dl, Plt 130,000/microliters, WBC 5,100/microliters without leukemic cells, and no DIC was detected. During the treatment, his bone marrow was examined frequently. The bone marrow series showed no hypoplasia at any time and gradual reduction of leukemic cells with proliferation of mature granulocytes. CR was attained on January 21, 1991. DIC did not develop. Cytogenetic anomalies including t(14;17;15) (q24;q11.2;q22) reduced from 29/30 cells at relapse to 4/30 cells at the time of CR. Dryness of mouth and lips, irritation around eyes and the elevations of GOT, GPT and triglyceride level were seen as the side effects of ATRA, however they were tolerable.

Calcitonin gene related peptide stimulates adenylate cyclase activity in rat striated muscle

Rat calcitonin gene related peptide (CGRP) and salmon calcitonin (CT) stimulated adenylate cyclase activity in a dose-dependent manner in the rat diaphragm and in the kidney. The ED50 value of rat CGRP was lower and that of salmon CT was higher in the diaphragm than in the kidney. These results suggest that CGRP stimulates adenylate cyclase activity in the striated muscle by reacting with sites distinct from the site in the kidney.

Undergraduate instruction in physical medicine and rehabilitation

The New York Medical College core curriculum includes a 1-week compulsory course in rehabilitation medicine in the student's senior year. The most common disabilities seen in rehabilitation medicine are discussed. The presentations consist of didactic lectures and patient demonstrations. The program which has evolved over the past 10 years has proved to be successful and has gained recognition from the school and students alike. Instructors teach topics of special interest to them and in which they have particular expertise. A written examination is given at the end of the course. Students also complete an extensive questionnaire which attempts to evaluate the course, compare it with the other rotations, and point out any changes in their attitudes. Of the 103 students who responded to the questionnaire, 75 indicated they achieved a better understanding of physical disability after the coarse, and 32 reported an improved attitude toward disability and improved perception of the field of rehabilitation medicine. Earlier exposure could have influenced the student's choice of a specialty. We believe that we have been allocated adequate time for effective presentation of the basic principles in rehabilitation medicine. However, crucial to attracting young students into the field is rotation through rehabilitation medicine early in their medical training.

Cell kinetics of human squamous cell carcinomas in the oral cavity

Cell proliferation characteristic of human malignant tumors has been related to the responses of tumors to various therapeutic means. The present study mainly concerns a routine method to measure cell kinetic parameters in human solid tumors. Proposed for this aim is the in vitro double labeling method under hyperbaric condition. For assessment of the method, two steps were taken. First cell cycle parameters were compared in a mouse squamous cell carcinoma between this in vitro method and the in vivo percent labeled mitoses methods. Second, the in vitro method was applied to eight cases of human squamous cell carcinomas. The results indicate that two sets of the cell cycle parameters of mouse squamous cell carcinoma measured by the two methods are in good agreement within an experimental error. DNA synthesis time, labeling index and cell cycle time of human squamous cell carcinoma varied among cases with a dispersion of 2- to 3-fold, that is, with ranges of 4.1-14.0 h, 14.3-28.7% and 21.2-52.9 /, respectively.

Rehabilitation outcome of patients with dual disability of hemiplegia and amputation

The records of 30 patients with the dual disability of hemiplegia and amputation were reviewed. Six factors noted to have influenced the success of rehabilitation were: (1) age; (2) sequence of onset of disability, whether amputation or hemiplegia first; (3) localization of dual disability, whether ipsilateral or contralateral; (4) side of hemiplegia; (5) level of amputation; (6) availability of prolonged hospital stay and training. The final functional status was better if: (1) the amputation preceded the CVA; (2) the amputation and hemiplegia were ipsilateral; (3) amputation and hemiplegia were both on the right side. The hospital stay of patients with dual disability ranged from 4 months to 1 year. Those who had disability on contralateral sides and those who had left hemiplegia required a more prolonged hospital stay.