Relationship between serum cholesterol efflux capacity and glucose intolerance in Japanese-Americans

AIM

Serum cholesterol efflux has been suggested to be a key anti-atherogenic function of reverse cholesterol transport. Meanwhile, the quantitative and qualitative alteration of the levels of lipoproteins in the serum has been reported in patients with diabetes, although it remains unclear whether the serum cholesterol efflux capacity is impaired in cases of newly diagnosed glucose intolerance. We thus assessed the relationship between the serum cholesterol efflux capacity and glucose intolerance as detected using oral glucose tolerance tests (OGTTs).

METHODS

We measured the capacity of whole serum to mediate cholesterol efflux from human THP-1 macrophages in a cohort of 439 Japanese-Americans who underwent 75-g OGTTs. A multiple regression analysis was performed to examine the relationship between the serum cholesterol efflux capacity and glucose intolerance.

RESULTS

The serum cholesterol efflux capacity was found to be negatively correlated with the area under the curve for the serum glucose concentration during the 75-g OGTTs in all subjects. In addition, the serum cholesterol efflux capacity was found to be modestly but significantly lower in the glucose intolerance group (31.4 ± 6.2%) than in the normal glucose tolerance group (33.2 ± 6.1%). There was also a negative association between the serum cholesterol efflux capacity and glucose intolerance after adjusting for age and sex. Moreover, this association remained significant even after further adjustments for serum total cholesterol, high-density lipoprotein cholesterol, apolipoprotein AI and C-reactive protein.

CONCLUSIONS

The serum cholesterol efflux capacity is impaired in Japanese-Americans newly diagnosed with glucose intolerance. This impairment may contribute in some manner to increasing the risk of atherosclerotic disease in subjects with glucose intolerance.

Distinct dopaminergic control of the direct and indirect pathways in reward-based and avoidance learning behaviors

The nucleus accumbens (NAc) plays a pivotal role in reward and aversive learning and learning flexibility. Outputs of the NAc are transmitted through two parallel routes termed the direct and indirect pathways and controlled by the dopamine (DA) neurotransmitter. To explore how reward-based and avoidance learning is controlled in the NAc of the mouse, we developed the reversible neurotransmission-blocking (RNB) technique, in which transmission of each pathway could be selectively and reversibly blocked by the pathway-specific expression of transmission-blocking tetanus toxin and the asymmetric RNB technique, in which one side of the NAc was blocked by the RNB technique and the other intact side was pharmacologically manipulated by a transmitter agonist or antagonist. Our studies demonstrated that the activation of D1 receptors in the direct pathway and the inactivation of D2 receptors in the indirect pathway are key determinants that distinctly control reward-based and avoidance learning, respectively. The D2 receptor inactivation is also critical for flexibility of reward learning. Furthermore, reward and aversive learning is regulated by a set of common downstream receptors and signaling cascades, all of which are involved in the induction of long-term potentiation at cortico-accumbens synapses of the two pathways. In this article, we review our studies that specify the regulatory mechanisms of each pathway in learning behavior and propose a mechanistic model to explain how dynamic DA modulation promotes selection of actions that achieve reward-seeking outcomes and avoid aversive ones. The biological significance of the network organization consisting of two parallel transmission pathways is also discussed from the point of effective and prompt selection of neural outcomes in the neural network.

Low high-density lipoprotein cholesterol level is a significant risk factor for development of type 2 diabetes: Data from the Hawaii-Los Angeles-Hiroshima study

Aims/Introduction

A low level of high‐density lipoprotein cholesterol (HDLC) is a common feature of metabolic syndrome. We have reported that Japanese–Americans who share a virtually identical genetic makeup with native Japanese, but who have lived Westernized lifestyles for decades, have lower HDLC levels and a high prevalence of type 2 diabetes compared with native Japanese. However, the impact of low HDLC level on type 2 diabetes is unclear. The aims of the present study were to evaluate whether serum HDLC level was associated with development of type 2 diabetes and if the effect might be modified by lifestyle.

Materials and Methods

We examined 1,133 non‐diabetic Japanese–Americans and 1,072 non‐diabetic Japanese, who underwent the 75‐g oral glucose tolerance test (OGTT) and were followed for an average of 8.8 and 7.0 years, respectively. We analyzed whether serum HDLC level is a risk factor for development of type 2 diabetes based on the Cox proportional hazards model.

Results

After adjustment for age and sex, hazard ratios for development of type 2 diabetes per unit of serum HDLC level (mmol/L) were 0.292 (95% confidence interval [CI] 0.186–0.458, P < 0.0001) among Japanese–Americans and 0.551 (95% CI 0.375–0.88, P = 0.0023) among native Japanese. Comparable hazard ratios after further adjustment for category of OGTT and body mass index were 0.981 (95% CI 0.970–0.993, P = 0.0018) and 0.991 (95% CI 0.980–1.002, P = 0.112), respectively.

Conclusions

HDLC level was associated with development of type 2 diabetes in both Japanese–Americans and native Japanese. However, these results suggest that the impact of high‐density lipoprotein on glucose metabolism might be affected by lifestyle.

Significantly high level of late-night free cortisol to creatinine ratio in urine specimen in patients with subclinical Cushing's syndrome

OBJECTIVE

Absence of a late-night cortisol nadir is a consistent biochemical abnormality in patients with cortisol-producing adenoma. We evaluated the abnormality of late-night urinary free cortisol to creatinine ratio (late-night UFCCR) in patients with subclinical Cushing's syndrome (SCS).

METHODS

Fifty-eight patients with incidentally detected adrenocortical adenomas [SCS: 9; nonfunctioning adenoma (NF): 49] were enrolled as subjects. Values measured in all patients were urinary free cortisol accumulated between 9:00 p.m. and 11:00 p.m. (late-night UFCCR), serum cortisol at 11:00 p.m. (midnight serum cortisol: MSC), serum cortisol after 1-mg overnight dexamethasone suppression test (1 mg-DST) and 24-h urinary free cortisol (UFC).

RESULTS

Median late-night UFCCR value in SCS was significantly higher than that in NF (P < 0·001). Significant correlations were observed between late-night UFCCR and each of serum cortisol after 1 mg-DST and MSC (r = 0·537, P < 0·001 and r = 0·556, P < 0·001, respectively). There was no significant correlation between serum cortisol after 1 mg-DST and 24-h UFC (r = 0·211, P = 0·112). In receiver operating characteristic analysis for diagnosis of SCS, the areas under the curves of late-night UFCCR and 24-h UFC were 0·937 (95% confidence interval 0·865-1·008) and 0·726 (0·874-0·999), respectively. Late-night UFCCR cut-off value of 4·9 nmol/μmol Cre showed a sensitivity of 100% and a specificity of 76·6%.

CONCLUSION

Patients with SCS showed higher late-night UFCCR values than those with NF. Late-night UFCCR was significantly correlated with autonomous cortisol production findings. Diagnostic performance of late-night UFCCR was superior to 24-h UFC. These results suggest that late-night UFCCR might represent one of the simple and reliable tests for SCS diagnosis.

Single-shot detection of mid-infrared spectra by chirped-pulse upconversion with four-wave difference frequency generation in gases

Single-shot detection of ultrabroadband mid-infrared spectra was demonstrated by using chirped-pulse upconversion technique with four-wave difference frequency generation in gases. Thanks to the low dispersion of the gas media, the bandwidth of the phase matching condition of the upconversion process becomes very broad and the entire mid-infrared spectrum spanning from 200 to 5500 cm(-1) was upconverted by using a 10 ps chirped pulse to visible wavelength radiation, which was detected with a conventional visible dispersive spectrometer. This method was demonstrated by the successful measurement of infrared absorption spectra of organic polymer films.

Construction, expression and characterisation of recombinant molecules of the urease gene operon from a urease-positive thermophilic Campylobacter (UPTC) isolate

A recombinant molecule of the full-length urease gene operon was constructed in vitro from the Japanese urease-positive thermophilic Campylobacter (UPTC) CF89-12 isolate and expressed in Escherichia coli cells. Several large deletion recombinant variants of urease subunit genes were also constructed and expressed in E. coli cells. A positive urease reaction with the log-phase cultured E. coli JM109 cells in the NiCl2-containing medium transformed with pGEM-T vector carrying the recombinant molecule of the full-length operon was detected with isopropyl-beta-D-thiogalactoside. Among the several deletion recombinant variants, each ureA-, ureB-, ureE-, ureF-, ureG- and ureH-large deficient, only ureE-large deletion variant (63% deficient) showed a positive urease reaction (approximately 15-fold). In addition, a ureE-complete deletion recombinant variant (100% deficient) constructed also showed a positive reaction of urease (approximately 18-fold). Recombinant urease subunits A and B were immunologically identified by Western blot analysis with anti-urease alpha (A) and beta (B) raised against Helicobacter pylori.

Impact of glucose excursion and mean glucose concentration in oral glucose-tolerance test on oxidative stress among Japanese Americans

AIM

To evaluate the impact of glucose excursion (GE) and mean glucose concentration (MGC) on oxidative stress among persons with or without diabetes.

MATERIALS AND METHODS

We examined 775 Japanese Americans who had normal glucose tolerance (NGT), impaired glucose tolerance, or diabetes according to the 75 g oral glucose-tolerance test, using fasting, 1-hour, and 2-hour glucose data. We calculated GE by subtracting the minimum from the maximum glucose level among three points and calculated MGC using these measurements. We investigated the relationship between GE or MGC and urinary isoprostane as a marker of oxidative stress.

RESULTS

According to tertiles of GE or MGC, GE was associated with isoprostane levels among subjects with NGT as well as those with diabetes (P=0.004 and 0.033 for trend, respectively). However, MGC was associated with isoprostane only among NGT subjects (P=0.001 for trend). Association between GE and isoprostane was significant when adjustment was made for age, sex, smoking status, body mass index, C-reactive protein, glucose tolerance status, and homeostatic model assessment (P=0.029), but the association with MGC was not significant.

CONCLUSION

Our results suggest the possibility that GE might result in oxidative stress, and the relationship is stronger than that for MGC.

Influence of Adrenal Subclinical Hypercortisolism on Hypertension in Patients with Adrenal Incidentaloma

The purpose of our study was to clarify whether subtle cortisol-producing tumors, such as not only subclinical Cushing’s syndrome (SubCS) but also subclinical hypercortisolism (SH), influence the prevalence of hypertension, since numerous basic research studies have noted that glucocorticoid excess influences blood pressure.

80 patients with adrenocortical adenomas (39 women and 41 men; mean age 62.1 years) were enrolled. SubCS was diagnosed using a diagnostic criteria, and SH was diagnosed as the presence of a serum cortisol level greater than 50 nmol/L following 1-mg dexamethasone suppression test (DST).

SubCS, SH, or non-functioning adrenocortical adenoma (NF) was diagnosed in 14, 13, or 53 patients, respectively. The prevalence of hypertension differed significantly among the diagnoses (SubCS, 78.6%; SH, 84.6%; NF, 39.6%; P=0.002), whereas no differences in other clinical characteristics such as age, sex, or waist girth were observed. The patients with SH had an 11.7-fold increased risk (95% confidence interval: 1.9–72.7, P=0.009) and those with SubCS had a 9.5-fold increased risk (95% confidence interval: 1.9–48.3, P=0.007) for hypertension compared to those with NF using a multivariate analysis.

We demonstrated that subtle cortisol-producing tumors, such as SH as well as SubCS, were an independent risk factor for hypertension. The cut-off value of the 1-mg DST would be appropriate to predict the development of hypertension.

Associations between small dense LDL, HDL subfractions (HDL2, HDL3) and risk of atherosclerosis in Japanese-Americans

AIM

Small dense low-density lipoprotein (sdLDL) has been suggested to be more atherogenic than large buoyant LDL. High-density lipoprotein (HDL) consists of two major subfractions (HDL2, HDL3), and just as controversy remains regarding which of the two is the more powerful negative risk factor for atherosclerosis, associations between sdLDL and these HDL subfractions are unclear.

METHODS

We measured sdLDL cholesterol (sdLDL-C), HDL2 cholesterol (HDL2-C) and HDL3 cholesterol (HDL3-C) by a newly developed method in 481 Japanese-Americans who were not using lipid-lowering medication, and examined the associations of these cholesterol concentrations with variables related to atherosclerosis.

RESULTS

In multivariate analysis, sdLDL-C was positively correlated with the body mass index (BMI), fasting glucose and insulin, 2-h glucose, HOMA-IR, high sensitivity C-reactive protein (hsCRP), and carotid artery intima-media thickness (IMT) after adjustment for age and sex. In particular, sdLDL-C was positively correlated with IMT, even after adjustment for sex, age, smoking status, hypertension, diabetes mellitus and hsCRP. HDL2-C was more closely inversely correlated than total HDL-C with BMI, fasting glucose and insulin, 2-h glucose, HOMA-IR, and hsCRP, whereas HDL3-C was not correlated with these factors. Additionally, HDL2-C was more closely correlated than total HDL-C or HDL3-C with sdLDL-C, LDL-C, triglycerides (TG), and apolipoprotein B (apoB).

CONCLUSIONS

SdLDL-C was closely associated with insulin resistance and glucose tolerance, lending credence to its potential as a useful risk marker in assessing carotid artery IMT and the present degree of atherosclerosis in Japanese-Americans. The findings also suggest that subjects with higher HDL2-C levels were better protected from atherosclerosis.

Low serum levels of total and high-molecular-weight adiponectin predict the development of metabolic syndrome in Japanese-Americans

BACKGROUND

Adiponectin is thought to play a significant role in the development of both insulin resistance and metabolic syndrome. Yet, there is very few evidence about the association plasma adiponectin and metabolic syndrome in the prospective study. Adiponectin exists as multimers in serum, and high-molecular-weight (HMW) adiponectin is particularly considered to be the active form of the protein.

AIM

We investigated whether serum HMW adiponectin as well as total adiponectin is associated with the development of metabolic syndrome in a longitudinal study.

SUBJECTS AND METHODS

We enrolled 224 men and 312 women of Japanese- Americans without metabolic syndrome at baseline who were followed for an average of 3.2 yr. The association of plasma total and HMW adiponectin with a progression to metabolic syndrome was examined.

RESULTS

Subjects who developed metabolic syndrome had significantly lower plasma total and HMW adiponectin levels at baseline than those who did not develop metabolic syndrome. In a Cox proportional hazards model, lower total and HMW adiponectin levels were independent risk factors for the development of metabolic syndrome after adjusting for age, body mass index, classification of 75-g glucose tolerance test, and homeostasis model assessment (hazards ratio: total, 0.684, p=0.017, in men; 0.606, p=0.003, in women; HMW, 0.687, p=0.014, in men; 0.704, p=0.029, in women, respectively).

CONCLUSIONS

Low circulating levels of total and HMW adiponectin may be a possible predictor for the development of metabolic syndrome.

Molecular and comparative analyses of the full-length cytolethal distending toxin (cdt) gene operon and its adjacent genetic loci from urease-positive thermophilic Campylobacter (UPTC) organisms

Molecular and comparative analyses of the full-length cytolethal distending toxin (cdt) gene operon and its adjacent genetic loci (2.7-9.4 kilo base pairs in length) are carried out with 12 urease-positive thermophilic Campylobacter (UPTC) isolates using several polymerase chain reaction (PCR) primer pairs. Three putative open reading frames (ORFs) for cdtA, cdtB and cdtC, two putative promoters and a hypothetically intrinsic rho-independent transcription terminator were identified in all the operons of the 12 UPTC isolates examined. Although the number of amino acid residues slightly varied for the putative cdtA and cdtC ORFs, those for the cdtB were similar among all the UPTC isolates, as well as the six urease-negative (UN) C. lari examined previously. Regarding the cdt genes in UPTC CF89-12, each ORF commenced with an ATG start codon and terminated with a TAG stop codon for cdtA and cdtB and a TAA for cdtC. Start and stop codons of the three ORFs for the other 11 UPTC isolates were identical to those from the UPTC CF89-12 isolate except for the TTG start codon for cdtC in the two isolates (NCTC12892 and 12893) and the TGA stop codon for cdtA in five isolates (A1, A2, A3, 89049 and 92251). Two putative promoter structures, consisting of sequences at the -35-like (TTAATA) and -10-like (TATTAA) regions, as well as the start codon (ATG), were identified for the transcriptional promoter, immediately upstream of the cdtA gene in all the 12 isolates, Although the genetic heterogeneity of the cdtB gene locus occurred in all 28 C. lari isolates (n = 16 UN C. lari; n = 12 UPTC) examined, all nine amino acid-specific DNase residues were completely conserved in all their cdtB genes. Variable gene insertions with heterogeneous order and combinations occurred between cdtC and lpxB genes in the all UPTC organisms examined.

Resistance to thyroid hormone accompanied by Graves' disease

Resistance to thyroid hormone (RTH) is characterized by elevated serum levels of thyroid hormones and normal or slightly increased serum thyrotropin (TSH) levels. Recently it has been suggested that chronic TSH stimulation in RTH activates intrathyroidal lymphocytes, leading to thyroid damage and autoimmune thyroid disease (AITD). Therefore, individuals with RTH have an increased likelihood of AITD compared to unaffected relatives. We here report a 33-year-old woman in whom we diagnosed Graves' disease and treated her with thiamazole (MMI). For two years, her TSH levels were suppressed when thyroid hormones were elevated and conversely they were increased when thyroid hormones levels were decreased. These findings were common for a clinical course during treatment for Graves' disease with anti-thyroid drug. However, three years after the initiation of MMI therapy, she had a normal or gradually elevated serum TSH level even though the level of thyroid hormones never decreased, indicating inappropriate secretion of TSH. We concluded she had RTH clinically, and we demonstrated by direct sequence analysis a mutation of the TRβ gene, causing replacement of a glycine (G) with arginine (R) at codon 251. The finding of an elevated TSH level without decreased thyroid hormones should suggest the presence of RTH during therapy of Graves' disease.

Hepatitis C virus-related kidney disease: various histological patterns

BACKGROUND

Although hepatitis C virus (HCV) infection is known to be associated with Type 2 cryoglobulinemic glomerulopathy (CG), only a few reports about other types of nephropathy have been published.

METHODS

68 HCV antibody positive patients in whom renal biopsy had been performed for persistent proteinuria, hematuria, and/or renal dysfunction between 1992 and 2008 at our institute were included. The histological, clinical and laboratory characteristics including the age, gender, hypertension, diabetes mellitus, liver histology (chronic hepatitis or liver cirrhosis), HCV-RNA, HCV genotype, splenomegaly, gastroesophageal varices, serum creatinine, hemoglobin, platelet count, rheumatoid factor, cryoglobulin, IgG, IgA, IgM, CH50, C3, C4, creatinine clearance, 24-h protein excretion, and hematuria, between their nephropathy with and without immune deposition were compared.

RESULTS

Nephropathy was classified into two groups based on the detection of immune deposits by immunofluorescence microscopy: i.e., a positive group (n = 39) and a negative group (n = 29). The former group was further classified into three types of nephropathy: IgG dominant group (n = 10) (including membranous nephropathy (MN)), IgA dominant group (n = 20) (including IgA nephropathy (IgAN)), membranoproliferative glomerulonephritis (MPGN) (IgA type)), and IgM dominant group (n = 9) (MPGN apart from the IgA type). The latter group included diabetic nephropathy (n = 13), focal glomerular sclerosis (n = 4), and benign nephrosclerosis (n = 3), malignant nephrosclerosis (n = 1), tubulointerstitial nephritis (TIN) (n = 2), minimal change nephrotic syndrome (n = 1), cast nephropathy (n = 1), granulomatous TIN (n = 1), and others (n = 3). An increased serum IgM level, hypocomplementemia, splenomegaly, thrombocytopenia, liver cirrhosis, hematuria, and a high HCV RNA level were features of patients with MPGN of IgM dominant group (consistent with "CG").

CONCLUSIONS

Our results showed various histological patterns of HCV-related kidney disease and the specificity of CG, and revealed that a minority of HCV patients (n = 7) presented typical CG, while IgAN, MN, and diabetic nephropathy were more frequent.

Structural analysis and expression of the full-length cytochrome P450 gene operon in Campylobacter lari

Two sets of PCR primers are constructed to clone the cytochrome P450 structural gene, including putative promoter and terminator structures, and its adjacent genetic loci in Campylobacter lari isolates. The putative open reading frames (ORFs) of the P450 genes from 11 C. lari isolates (n=5 for urease-negative (UN) C. lari; n=6 urease-positive thermophilic campylobacters [UPTC]) examined consisted of 1365 or 1371 bases (455 or 457 amino acid residues), differing from those of the other thermophilic campylobacters (1359 [453] for C. jejuni and C. upsaliensis; 1368 [456] for C. coli). Each of the putative ORFs from the 11 isolates examined was also shown to carry start and stop codons and ribosome binding sites. Two putative promoter structures, consisting of sequences at the -35- and -10-like regions were also identified upstream of the ORFs. A single copy of the P450 gene in the genome was identified with UN C. lari JCM2530(T) and UPTC CF89-12, based on Southern blot hybridisation analysis. In addition, when reverse transcription polymerase chain reaction (RT-PCR) analyses were carried out, the transcription of the P450 structural gene in C. lari organisms in vivo was confirmed. The transcription initiation site for the gene was also determined. High nucleotide sequence similarities (95.2-98.8%) of the full-length P450 structural gene were shown with each of the 12 C. lari isolates. The UN C. lari and UPTC organisms showed similar findings with the neighbour-joining method, based on the sequence information of the P450 structural gene.

[Macroangiopathy compared between native Japanese and Japanese-Americans: findings from the Hawaii-Los Angels-Hiroshima Study]

We have conducted medical surveys of Japanese-Americans, in whom westernization of life style occurred earlier and more intensively, in order to clarify the impact of westernization of life style on diseases in Japanese. This survey is started in Hawaii in 1970, and Los Angeles in 1978. We clarified that the prevalence of obesity, which leads to insulin resistance, is higher in Japanese-Americans than that in Japanese, and that insulin resistance which is associated with diabetes, hypertention, and dyslipidemia could increase macroangiopathy such as ischemic heart disease and stroke in Japanese-Americans. The mortality rate of Japanese-Americans with diabetes from ischemic heart disease increased to be similar extent to that of Caucasian in the U.S. It could be concluded that Japanese-Americans are at high risk for macroangiopathy.

Improvement of hypercortisolism by β-blocker therapy in subclinical Cushing's syndrome associated with ACTH-independent macronodular adrenocortical hyperplasia

A 61-year-old man with hypertension and diabetes was referred for the evaluation of multiple bilateral adrenal tumors. While Cushingoid features were not apparent, an elevated cortisol level in response to a low-dose dexamethasone suppression test (187.7 nmol/l), an elevated urinary cortisol level (170.9 nmol/day), and a weak response to a cosyntropin-releasing hormone (CRH) provocation test were observed. Furthermore, the serum cortisol level increased in response to a posture test or isoproterenol infusion. Accordingly, the patient was diagnosed as having ACTH-independent macronodular adrenal hyperplasia (AIMAH) with subclinical Cushing's syndrome associated with the aberrant expression of β-adrenergic receptors. After 2 months of propranolol therapy, the serum cortisol responses to a posture test and isoproterenol infusion, the cortisol level in response to a low-dose dexamethasone suppression test (102.1 nmol/l), and the urinary cortisol level (165.9 nmol/day) all normalized. While the suppression of cortisol secretion was sustained for 24 months, glucose metabolism and adrenal size were unaffected. To our knowledge, this is the first report of AIMAH accompanied by subclinical Cushing's syndrome associated with the aberrant expression of β-adrenergic receptors. Furthermore, propranolol inhibited cortisol hypersecretion in the present case. Additional cases or controlled studies are needed to determine the potential effect of propranolol on metabolic disorders and adrenal size in patients with AIMAH.

HDL subspecies in young adult twins: heritability and impact of overweight

The association between abdominal obesity and atherogenic lipid profile emerges from complex interactions of genes and environment. We aimed to explore the heritability and effects of overweight on serum lipid profile (high-density lipoprotein-cholesterol (HDL-C), HDL mean particle size, percentages of HDL(2b, 2a, 3a, 3b, and 3c,) low-density lipoprotein-cholesterol (LDL-C), LDL peak particle size and triglycerides (TGs)) in healthy, young adults. HDL-C, LDL-C, and TG were measured in 52 monozygotic (MZ) and 89 dizygotic (DZ) twin pairs, aged 23-32 years, chosen to represent a wide range of BMIs (17.6-42.9 kg/m2). Of them, 24 MZ and 26 DZ pairs were chosen at random for measurements of HDL mean and LDL peak particle sizes and percentages of HDL subspecies. The heritabilities of the lipid parameters adjusted for BMI were HDL-C 73%, HDL mean particle size 56%, HDL subspecies 46-63%, LDL-C 79%, LDL peak particle size 49%, and TG 64%. Genetic and environmental correlations between BMI and HDL-C, LDL-C, and TG were modest (0.3-0.4). Abdominal overweight (waist circumference>or=94 cm for males and >or=80 cm for females) associated with decreased HDL-C, increased LDL-C, and TG concentrations, smaller HDL mean particle size, lower HDL2b, and higher HDL3c percentages in both genders. Within MZ twins, controlling for genetic influences, within-pair differences in HDL3c percentage were associated with those in waist (r=0.46, P=0.032) and BMI (r=0.51, P=0.013). In conclusion, serum lipid parameters, including LDL peak and HDL mean particle sizes and HDL subspecies distribution are under strong genetic control. Overweight associated with significant lipid profile changes, particularly, small HDL3c increased in overweight independent of genetic influences.

Genetic manipulation study of information processing in the cerebellum

The cerebellar circuitry consists of two main excitatory glutamatergic pathways. The inputs of mossy fibers and climbing fibers converge on Purkinje cells and deep cerebellar nuclei. In this circuitry, Golgi interneurons suppress granule cell excitability via the inhibitory GABA transmitter. A novel technique termed reversible neurotransmission blocking (RNB) was genetically established, in which granule cell transmission to Purkinje cells was selectively and reversibly blocked in the mouse cerebellar circuitry. This study revealed that Purkinje cells are essential for expression of conditioned eye-blink motor learning but that this memory is acquired and stored in deep cerebellar nuclei. A different technique termed immunotoxin-mediated cell targeting (IMCT) was developed to selectively ablate Golgi cells from the mouse cerebellar network. The study disclosed that excitatory glutamate receptors and inhibitory GABA receptors cooperatively act at Golgi cell-mossy fiber-granule cell synapses and are indispensable for motor coordination and adaptation. Finally, gene targeting of mGluR2 displayed that the metabotropic glutamate receptor acts collaboratively with the ionotropic AMPA receptors at granule cell-Golgi cell synapses and is crucial for the spatiotemporal regulation in the mouse cerebellar circuitry. The neural information is thus hierarchically regulated and integrated at different levels of the cerebellar network.