Small polydisperse low density lipoproteins in familial hyperalphalipoproteinemia with complete deficiency of cholesteryl ester transfer activity

Lipoprotein abnormalities were analyzed in 3 cases of marked hyperalphalipoproteinemia caused by complete deficiency of cholesteryl ester transfer activity. The probands were all men, aged 34, 43 and 48 years, respectively. The serum high density lipoprotein (HDL)-cholesterol levels of these patients were higher than 150 mg/dl (157-254 mg/dl), while serum total cholesterol levels ranged from 227 to 360 mg/dl. Sequential flotation-ultracentrifugation analysis disclosed that low density lipoprotein (LDL)-cholesterol was slightly decreased and that cholesteryl ester accumulated solely in the HDL2 fraction, which was also enriched with apolipoprotein E. Cholesteryl ester transfer activity was completely absent in all of these cases. High-performance liquid chromatography showed a decrease of LDL particle size in combination with a marked enlargement of HDL particle size. Analytical ultracentrifugation disclosed heterogeneity of LDL with the presence of small LDL subpopulations. We conclude that hyperalphalipoproteinemia due to complete deficiency of cholesteryl ester transfer activity is characterized by the presence of both small polydisperse LDL and markedly large HDL enriched with cholesteryl ester and apolipoprotein E.

Analysis of drug permeation across Caco-2 monolayer: implication for predicting in vivo drug absorption

PURPOSE

The aim of the present work is to characterize in vitro drug permeation processes across Caco-2 monolayer and to identify the advantages of this cultured cell system in predicting in vivo drug absorption after oral administration.

METHODS

The passive permeability of various drugs through Caco-2 monolayer was measured using Ussing-type chambers and compared with that of the isolated rat jejunum and colon. The in vivo drug permeability to the intestinal membrane was estimated by means of an intestinal perfusion study using the rat jejunum.

RESULTS

In Caco-2 monolayer, drug permeability increased with increasing drug lipophilicity and showed a good linear relationship with the in vivo permeability. In contrast, in the isolated jejunum and colon, the permeability of high lipophilic drugs was almost constant and, propranolol, a drug with the highest lipophilicity, hardly passed through the jejunal membrane in vitro. As a result, there was no significant relationship between in vitro and in vivo drug permeability in rat jejunum. However, the amount of drugs accumulated in the jejunal mucosa increased with increasing drug lipophilicity even under the in vitro condition.

CONCLUSIONS

The permeation and the accumulation studies suggested that the rate-limiting process of in vitro permeation of lipophilic drugs through the intestinal membrane differs from that of in vivo drug absorption. On the other hand, drug permeation through Caco-2 monolayer, which consists of an epithelial cell layer and a supporting filter, is essentially the same process as that of in vivo drug absorption. We concluded that the simple monolayer structure of a cultured cell system provides a distinct advantage in predicting in vivo drug absorption.

Oxidative stress in patients with hepatitis, cirrhosis, and hepatoma evaluated by plasma antioxidants

We have applied our method for the simultaneous detection of plasma ubiquinol-10 (reduced form) and ubiquinone-10 (oxidized form) (S. Yamashita and Y. Yamamoto, Anal. Biochem. 250, 66-73, 1997) to plasmas of normal subjects (n = 16) and patients with chronic active hepatitis (n = 28), liver cirrhosis (n = 16), and hepatocellular carcinoma (n = 20) to evaluate the pressure of oxidative stress in these patients. The average ubiquinone-10 percentages (+/- S.D.) in total ubiquinone-10 and ubiquinol-10 in the four groups were 6.4 +/- 3.3, 12.9 +/- 10.3, 10.6 +/- 6.8, and 18.9 +/- 11.1, respectively, indicating a significant increase in ubiquinone-10 percentage in patient groups in comparison to normal subjects. These results and a significant decrease in the plasma ascorbate level in patient groups indicate that oxidative stress is evident after the onset of hepatitis and the subsequent cirrhosis and liver cancer.

Unique activity associated with non-insecticidal Bacillus thuringiensis parasporal inclusions: in vitro cell-killing action on human cancer cells

Parasporal inclusion proteins from a total of 1744 Bacillus thuringiensis strains, consisting of 1700 Japanese isolates and 44 reference type strains of existing H serovars, were screened for cytocidal activity against human leukaemia T cells and haemolytic activity against sheep erythrocytes. Of 1684 B. thuringiensis strains having no haemolytic activity, 42 exhibited in vitro cytotoxicity against leukaemia T cells. These non-haemolytic but leukaemia cell-toxic strains belonged to several H-serovars including dakota, neoleonensis, shandongiensis, coreanensis and other unidentified serogroups. Purified parasporal inclusions of the three selected strains, designated 84-HS-1-11, 89-T-26-17 and 90-F-45-14, exhibited no haemolytic activity and no insecticidal activity against dipteran and lepidopteran insects, but were highly cytocidal against leukaemia T cells and other human cancer cells, showing different toxicity spectra and varied activity levels. Furthermore, the proteins from 84-HS-1-11 and 89-T-26-17 were able to discriminate between leukaemia and normal T cells, specifically killing the former cells. These findings may lead to the use of B. thuringiensis inclusion proteins for medical purposes.

Insulinlike growth factor I regulation of growth hormone gene transcription in primary rat pituitary cells

We have previously shown that insulinlike growth factor I (IGF-I) inhibits growth hormone (GH) secretion and messenger RNA (mRNA) levels in pituitary cells. The effects of IGF-I on new GH mRNA synthesis rates in primary monolayer rat pituitary cells were therefore examined by nuclear runoff transcription assays. IGF-I (1.3 nM) treatment for 1 h inhibited GH gene transcription to 60% of controls. IGF-I (3.25 nM) maximally suppressed GH gene transcription to 30% of control values after 4 h. After 24 h treatment, GH transcription was suppressed to 48% of controls by 3.25 nM IGF-I. IGF-I (3.25 nM) also inhibited the twofold growth hormone-releasing hormone (GHRH) (10 nM)-stimulated GH gene transcription by 30% after 4 h. Transcription of the prolactin (PRL) gene was not suppressed in these cells by IGF-I. Relatively high doses of insulin (200 nM) also suppressed GH gene transcription, but epidermal growth factor and fibroblast growth factor did not change GH mRNA synthesis. The results show that IGF-I exerts a rapid and selective suppression of basal and GHRH-stimulated GH gene transcription. These data indicate a role for IGF-I in negative feedback of GH gene expression and provide evidence for the direct transcriptional regulation of the GH gene by IGF-I in primary rat anterior pituitary cells.

Saturable absorbers incorporating carbon nanotubes directly synthesized onto substrates and fibers and their application to mode-locked fiber lasers

We present novel carbon-nanotube-based saturable absorbers. Using the low-temperature alcohol catalytic chemical-vapor deposition method, high-quality single-walled carbon nanotubes (SWNTs) were directly synthesized on quartz substrates and fiber ends. We successfully applied the SWNTs to mode lock a fiber laser producing subpicosecond pulses at a 50-MHz repetition rate.

Overexpression of group II phospholipase A2 in human breast cancer tissues is closely associated with their malignant potency

Membrane-associated phospholipase A2 (M-PLA2) is an enzyme that hydrolyses the sn-2 fatty acyl ester bond of phosphoglycerides. We measured M-PLA2 concentration in tissue extracts from 325 human breast cancers using a specific radioimmunoassay recently developed. Correlation analyses between the tissue concentration of M-PLA2 and clinicopathological factors showed that the enzyme level was significantly higher in patients with distant metastasis than in those without. In addition, M-PLA2 concentration was significantly higher in scirrhous carcinoma than in other histological types. No significant association was found between M-PLA2 concentration and age, menstrual status, tumour size, histological grade, vessel involvement or oestrogen receptor (ER) and progesterone receptor (PR) status. The expression of M-PLA2 mRNA was examined in a fibroadenoma, a stage IV breast cancer and its metastatic site of skin. Northern blot analysis showed a clear hybridisation band corresponding to M-PLA2 mRNA in both primary breast cancer and its metastatic site, while the fibroadenoma expressed a faint band corresponding to M-PLA2 mRNA. Breast cancer patients with high M-PLA2 concentrations exhibited significantly shorter disease-free and overall survival than those with low M-PLA2 concentration at the cut-off point of 5 ng 100 mg-1 protein, which was determined in a separate study. In multivariate analysis, M-PLA2 was found to be an independent prognostic factor for disease recurrence and death in human breast cancer. The possible significance of M-PLA2 expression in human breast cancer tissue is discussed.

Influence of epidermal growth factor and transforming growth factor-alpha on in vitro maturation of cumulus cell-enclosed bovine oocytes in a defined medium

This study was carried out to determine the effects of growth factors (epidermal growth factor, transforming growth factors-alpha and -beta 1, basic fibroblast growth factor, insulin), gonadotrophins (LH, FSH), and fetal bovine serum added to TCM199 medium on cumulus expansion and fertilization during in vitro maturation, and on subsequent embryonic development of bovine cumulus cell-enclosed oocytes. Epidermal growth factor, transforming growth factor-alpha, LH and FSH enhanced cumulus expansion and oocyte fertilizability. No significant effect was achieved with transforming growth factor-beta 1 nor with basic fibroblast growth factor. No additive stimulation on cumulus expansion and oocyte fertilizability was observed when epidermal growth factor was combined with LH or FSH. The addition of either epidermal growth factor or transforming growth factor-alpha to the maturation medium increased the number of fertilized ova that developed to the blastocyst stage. These results demonstrate the potential use of epidermal growth factor and transforming growth factor-alpha in obtaining high quality mature bovine oocytes for in vitro fertilization.

Rap2 as a slowly responding molecular switch in the Rap1 signaling cascade

Rap2 is a member of the Ras family of GTPases and exhibits 60% identity to Rap1, but the function and regulation of Rap2 remain obscure. We found that, unlike the other Ras family proteins, the GTP-bound active form exceeded 50% of total Rap2 protein in adherent cells. Guanine nucleotide exchange factors (GEFs) for Rap1, C3G, Epac (or cyclic AMP [cAMP]-GEF), CalDAG-GEFI, PDZ-GEF1, and GFR efficiently increased the level of GTP-Rap2 both in 293T cells and in vitro. GTPase-activating proteins (GAPs) for Rap1, rap1GAPII and SPA-1, stimulated Rap2 GTPase, but with low efficiency. The half-life of GTP-Rap2 was significantly longer than that of GTP-Rap1 in 293T cells, indicating that low sensitivity to GAPs caused a high GTP/GDP ratio on Rap2. Rap2 bound to the Ras-binding domain of Raf and inhibited Ras-dependent activation of Elk1 transcription factor, as did Rap1. The level of GTP-Rap2 in rat 3Y1 fibroblasts was decreased by the expression of v-Src, and expression of a GTPase-deficient Rap2 mutant inhibited v-Src-dependent transformation of 3Y1 cells. Altogether, Rap2 is regulated by a similar set of GEFs and GAPs as Rap1 and functions as a slowly responding molecular switch in the Rap1 signaling cascade.

Parasporin, a human leukemic cell-recognizing parasporal protein of Bacillus thuringiensis

An unusual property, human leukemic cell-recognizing activity, associated with parasporal inclusions of a noninsecticidal Bacillus thuringiensis soil isolate was investigated, and a protein (named parasporin in this study) responsible for the activity was cloned. The parasporin, encoded by a gene 2,169 bp long, was a polypeptide of 723 amino acid residues with a predicted molecular weight of 81, 045. The sequence of parasporin contained the five conserved blocks commonly found in B. thuringiensis Cry proteins; however, only very low homologies (<25%) between parasporin and the existing classes of Cry and Cyt proteins were detected. Parasporin exhibited cytocidal activity only when degraded by proteases into smaller molecules of 40 to 60 kDa. Trypsin and proteinase K activated parasporin, while chymotrypsin did not. The activated parasporin showed strong cytocidal activity against human leukemic T cells (MOLT-4) and human uterus cervix cancer cells (HeLa) but not against normal T cells.

Two decades of annual medical examinations in Japanese obese children: do obese children grow into obese adults?

OBJECTIVE

To investigate trends in frequency of obese children in Japan over two decades, the frequency of obese children who grow into obese adults and predictive factors for adult obesity.

DESIGN

Annual cross-sectional studies for 22 y (1974-1995) with a follow-up study.

SUBJECTS

Cross-sectional: Cumulatively 13,186 obese (% of standard body weight (SBW): > or = 120%) schoolchildren including 3158 extremely obese (> or = 140% of SBW) children out of 203,088 schoolchildren (age: 6-14 y) in Izumiohtsu City, Osaka, Japan.

FOLLOW-UP

151 initially obese children (initial age: 6-14 y and age at follow-up: 20-35 y) who lived in Izumiohtsu City.

CONTROL

3552 Japanese men and 4631 Japanese women (age: 20-35 y).

MEASUREMENTS

Cross-sectional: height, weight, trunk circumference, skin-fold thickness, blood pressure and blood biochemicals.

FOLLOW-UP

height, weight, trunk circumference, skin-fold thickness during childhood, and body height and weight at follow-up. Adulthood obesity: > or = 120% of the average body mass indices (BMI) of the controls.

RESULTS

Frequency of obese children increased from 5% to more than 10%, and that of extremely obese children increased from 1% to more than 2% during these 22 y. These increases were most prominent in the schoolboys aged 9-11 y. Prevalence of hyperglycemia and hyperlipidemia in the extremely obese children did not change, and that of hypertension and abnormal liver function gradually decreased during these two decades. After coming of age, 32.2% of the initially obese boys (relative risk: 5.3) and 41.0% of the initially obese girls (relative risk: 6.7) remained obese. BMI, percentage of the SBW and skin-fold thickness at the biceps during childhood were significantly larger in currently-obese girls. Positive correlations were demonstrated between these variables and percentage SBW at follow-up.

CONCLUSIONS

Childhood obesity is increasing in Japan, especially in boys aged 9-11 y. Approximately 32% of the obese boys and 41% of the obese girls grow into obese adults, and the degree of obesity is a predictive factor for adult obesity.

Electroporation as a new technique for producing transgenic fish

A recombinant plasmid, pMV-GH, containing rainbow trout growth hormone cDNA fused to mouse metallothionein I promoter, was introduced into medaka (Oryzias latipes) by electroporation. Of 3109 fertilized eggs treated with electric pulses (750 V/cm, 50 microseconds, 5 times), 783 (25%) hatched out. Four percent of the hatchlings were transgenic. To obtain transgenic lines, 180 hatchlings were maintained and 35 of them grew into adult fish. Two of these fish were transgenic. When one transgenic fish was mated with a normal female, the transgene was found in all the F1 offspring assayed. In F2 offspring obtained by mating transgenic F1 fish, 88% were transgenic.

Enhanced expression of rat obese (ob) gene in adipose tissues of ventromedial hypothalamus (VMH)-lesioned rats

A responsible gene of genetically obese (ob/ob) mouse has recently been isolated. Genetic disruption of ob gene causes massive obesity. To elucidate the pathophysiological regulation of ob gene, we examined the gene expression in fat tissues of a non-genetical obese model, VMH-lesioned rats. The ob mRNA was identified in both subcutaneous and mesenteric fat tissues in the control rats. In VMH-lesioned rats, the abundance of ob mRNA increased after the gain of body weight and marked expression was observed on 15th day after making VMH lesion. These data suggest that ob gene might be up-regulated with fat accumulation even in non-genetically obese animals.

Inflammation-induced repression of tumor suppressor miR-7 in gastric tumor cells

Inflammation has an important role in cancer development through various mechanisms. It has been shown that dysregulation of microRNAs (miRNAs) that function as oncogenes or tumor suppressors contributes to tumorigenesis. However, the relationship between inflammation and cancer-related miRNA expression in tumorigenesis has not yet been fully understood. Using K19-C2mE and Gan mouse models that develop gastritis and gastritis-associated tumors, respectively, we found that 21 miRNAs were upregulated, and that 29 miRNAs were downregulated in gastric tumors in an inflammation-dependent manner. Among these miRNAs, the expression of miR-7, a possible tumor suppressor, significantly decreased in both gastritis and gastric tumors. Moreover, the expression of miR-7 in human gastric cancer was inversely correlated with the levels of interleukin-1β and tumor necrosis factor-α, suggesting that miR-7 downregulation is related to the severity of inflammatory responses. In the normal mouse stomach, miR-7 expression was at a basal level in undifferentiated gastric epithelial cells, and was induced during differentiation. Moreover, transfection of a miR-7 precursor into gastric cancer cells suppressed cell proliferation and soft agar colony formation. These results suggest that suppression of miR-7 expression is important for maintaining the undifferentiated status of gastric epithelial cells, and thus contributes to gastric tumorigenesis. Although epigenetic changes were not found in the CpG islands around miR-7-1 of gastritis and gastric tumor cells, we found that activated macrophage-derived small molecule(s) (<3 kDa) are responsible for miR-7 repression in gastric cancer cells. Furthermore, the miR-7 expression level significantly decreased in the inflamed gastric mucosa of Helicobacter-infected mice, whereas it increased in the stomach of germfree K19-C2mE and Gan mice wherein inflammatory responses were suppressed. Taken together, these results indicate that downregulation of tumor suppressor miR-7 is a novel mechanism by which the inflammatory response promotes gastric tumorigenesis.

15 years after Chernobyl: new evidence of thyroid cancer

The Chernobyl nuclear power plant accident happened on April 26, 1986. We investigated the cause of the striking increase in frequency of thyroid cancer in children who lived within a 150 km radius of Chernobyl and who were born before and after the accident. No thyroid cancer was seen in 9472 children born in 1987-89, whereas one and 31 thyroid cancers were recorded in 2409 children born April 27, 1986, to Dec 31, 1986, and 9720 born Jan 1, 1983, to April 26, 1986, respectively. Short-lived radioactive fallout caused by the Chernobyl accident probably induced thyroid cancer in children living near Chernobyl.

Insulin-like growth factor I regulates growth hormone secretion and messenger ribonucleic acid levels in human pituitary tumor cells

GH secretion and mRNA levels were measured in cultured human GH adenoma cells incubated in serum-free medium for up to 48 h. A human recombinant insulin-like growth factor I (IGF-I) analog, Thr-59-IGF-I (6.5 nM), inhibited basal GH secretion by up to 60% in tumor cell cultures. The 30-50% stimulation of GH secretion by GH-releasing hormone (GHRH) was prevented by simultaneous exposure of the cells to IGF-I (6.5 nM). Gel electrophoresis of total RNA derived from GH cell adenoma tissue, followed by transfer and hybridization with 32P-labeled human GH cDNA, revealed a distinct mRNA species of about 1.0 kilobases. Using cytoplasmic dot blot hybridization, IGF-I inhibited the levels of human GH mRNA sequences in these cells and also prevented the GHRH-induced stimulation of GH mRNA. A monoclonal antibody to the type I IGF-I receptor (alpha IR3) prevented the inhibitory effects of IGF-I on basal and GHRH-stimulated GH secretion. This antibody also prevented the IGF-I-induced suppression of GH mRNA sequences. PRL secretion in these cells was not altered by IGF-I. Furthermore, relative levels of beta-actin mRNA were unaltered by IGF-I. Thus, IGF-I suppresses basal and GHRH-stimulated GH secretion and GH mRNA levels in pituitary adenoma cells, indicating that IGF-I acts selectively on the somatotroph to directly regulate GH gene expression.

Magnitude of sustained multiple risk factors for ischemic heart disease in Japanese employees: a case-control study

A case-control study was performed to clarify the cause of ischemic heart disease (IHD), such as acute myocardial infarction and angina pectoris, in Japanese employees. Among 122,051 workers from 31 industries, 94 cases of IHD were the subjects of the study, and a total of 191 age-matched subjects from the same department, but who did not develop IHD, served as the controls. Compared with the control group, body mass index, blood pressure, fasting plasma glucose, serum total cholesterol and serum triglyceride were significantly higher, and cigarette consumption and serum uric acid also tended to be higher, in the patient group from at least 10 years prior to onset. The frequency of moderate-drinkers tended to be lower in the case group. Electrocardiograms showed that, compared with the control group, the frequency of myocardial ischemia was higher in the case group from 9 years prior to onset and further rapidly increased from 3 years prior. The frequency of subjects with arrhythmia was the same as the control group until 3 years before onset and increased rapidly from 2 years prior. The frequency of subjects with multiple risk factors, particularly obesity, hypertension, hyperlipidemia and hyperglycemia, was consistently higher in the case group compared with the control group from 10 years prior to onset. Conditional logistic regression analysis demonstrated that having more than one risk factor greatly increased the risk; in particular, the combination of 3 or more factors increased the relative risk to 10.56 (95% confidence interval: 3.30-33.78). These findings suggest that a long duration of multiple risks is involved in the onset of IHD in Japanese employees, and that annual ECG monitoring as part of the medical examination was important in the prognosis.

Characterization of plasma lipoproteins in patients heterozygous for human plasma cholesteryl ester transfer protein (CETP) deficiency: plasma CETP regulates high-density lipoprotein concentration and composition

To understand the role of human cholesteryl ester transfer protein (CETP) in plasma lipoprotein metabolism, CETP activity and mass levels, lipoprotein and apolipoprotein concentrations, and the size of high-density lipoprotein (HDL) were determined in 15 heterozygotes and compared with those of four homozygotes and 20 normolipidemic controls. Plasma CETP activity and mass were totally deficient in the four homozygotes for CETP deficiency, while heterozygotes had approximately half the level of normals. CETP activity positively correlated with CETP mass levels (r = .95, P less than .001). No significant difference was observed in the level of low-density lipoprotein (LDL)-cholesterol among the three groups. The concentration of HDL2-cholesterol in the heterozygotes was approximately twice as high as that in controls, while that of homozygotes was sixfold higher than that in controls. No significant difference in the HDL3-cholesterol level was observed among the three groups. The HDL2-cholesterol to HDL3-cholesterol ratio of homozygotes was sixfold higher than that of controls, while heterozygotes showed intermediate values between homozygotes and controls. Negative correlations were found between CETP activity and HDL2-cholesterol level (r = -.884, P less than .001) and between CETP mass and HDL2-cholesterol level (r = -.829, P less than .001). Plasma apolipoprotein (apo) A-I, C-III, and E were markedly increased in homozygotes, but the differences between normal and heterozygotes were not statistically significant. The HDL size of homozygotes, determined by high-performance liquid chromatography (HPLC), was large, whereas that of heterozygotes was intermediate between homozygotes and normals.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of the methyltransferases in the yeast phosphatidylethanolamine methylation pathway by selective gene disruption

PEM1 and PEM2 are structural genes for the yeast phosphatidylethanolamine methylation pathway which mediates the three-step methylation of phosphatidylethanolamine to phosphatidylcholine. Selective disruption of each locus in the yeast genome was performed using the in-vitro-inactivated gene with insertion of yeast LEU2 or HIS3. Complementation test and spore analysis indicated that the disruptants were allelic with our previous mutants that were isolated by chemical mutagenesis and used for the cloning of PEM1 and PEM2. The methyltransferase activities of the disruptants were assayed using their membrane fractions. When the PEM1 locus was disrupted, the activity for the first methylation was greatly decreased but was still detectable, while the activities for the second and third methylations were well retained. The remaining three activities exhibited nearly identical pH optima and apparent Km values for S-adenosyl-L-methionine. The disruptant incorporated radioactivity from L-[methyl-14C]Met into phosphatidylcholine at a low but measurable rate and required choline for optimal growth. When choline was omitted from the culture medium, the phosphatidylcholine content of the cells significantly decreased, but was restored by the addition of N-monomethylethanolamine or choline. When the PEM2 locus was disrupted, the activities for the second and third methylations were totally lost, but that for the first methylation remained. This activity could be distinguished from those remaining in the pem1 disruptant by its different pH optimum and apparent Km for S-adenosyl-L-methionine. When incubated with [methyl-14C]Met, the pem2 disruptant accumulated the radioactivity in phosphatidylmonomethylethanolamine. This disruptant also required choline for optimal growth. In the absence of choline, it accumulated phosphatidylmonomethylethanolamine with a concomitant decrease in phosphatidylcholine and phosphatidylethanolamine. When both loci were disrupted, all phospholipid-methylating activities were lost and cells absolutely required choline for growth. The flux through the pathway became negligible. Thus, the PEM1-encoded methyltransferase was strictly specific to the first step while the PEM2-encoded methyltransferase exhibited a somewhat broader specificity with a preference for the second and third steps of the pathway. These two enzymes accounted for all the activities in the yeast phosphatidylethanolamine methylation pathway.

Molecular biology and pathophysiological aspects of plasma cholesteryl ester transfer protein

Plasma cholesteryl ester transfer protein (CETP) facilitates the transfer of cholesteryl ester (CE) from high density lipoprotein (HDL) to apolipoprotein B-containing lipoproteins. Since CETP regulates the plasma levels of HDL cholesterol and the size of HDL particles, CETP is considered to be a key protein in reverse cholesterol transport, a protective system against atherosclerosis. CETP, as well as plasma phospholipid transfer protein, belongs to members of the lipid transfer/lipopolysaccharide-binding protein (LBP) gene family, which also includes the lipopolysaccharide-binding protein (LBP) and bactericidal/permeability-increasing protein. Although these four proteins possess different physiological functions, they share marked biochemical and structural similarities. The importance of plasma CETP in lipoprotein metabolism was demonstrated by the discovery of CETP-deficient subjects with a marked hyperalphalipoproteinemia (HALP). Two common mutations in the CETP gene, intron 14 splicing defect and exon 15 missense mutation (D442G), have been identified in Japanese HALP patients with CETP deficiency. The deficiency of CETP causes various abnormalities in the concentration, composition, and functions of both HDL and low density lipoprotein. Although the pathophysiological significance of CETP in terms of atherosclerosis has been controversial, the in vitro experiments showed that large CE-rich HDL particles in CETP deficiency are defective in cholesterol efflux. Epidemiological studies in Japanese-Americans and in the Omagari area where HALP subjects with the intron 14 splicing defect of CETP gene are markedly frequent, have shown an increased incidence of coronary atherosclerosis in CETP-deficient patients. The current review will focus on the recent findings on the molecular biology and pathophysiological aspects of plasma CETP, a key protein in reverse cholesterol transport.

Local tumour progression after percutaneous ablation of colorectal liver metastases according to RAS mutation status

BACKGROUND

Percutaneous ablation is a common treatment for colorectal liver metastasis (CLM). However, the effect of rat sarcoma viral oncogene homologue (RAS) mutation on outcome after ablation of CLMs is unclear.

METHODS

Patients who underwent image-guided percutaneous ablation of CLMs from 2004 to 2015 and had known RAS mutation status were analysed. Patients were evaluated for local tumour progression as observed on imaging of CLMs treated with ablation. Multivariable Cox regression analysis was performed to determine factors associated with local tumour progression-free survival.

RESULTS

The study included 92 patients who underwent ablation of 137 CLMs. Thirty-six patients (39 per cent) had mutant RAS. Rates of local tumour progression were 14 per cent (8 of 56) for patients with wild-type RAS and 39 per cent (14 of 36) for patients with mutant RAS (P = 0·007). The actuarial 3-year local tumour progression-free survival rate after percutaneous ablation was worse in patients with mutant RAS than in those with wild-type RAS (35 versus 71 per cent respectively; P = 0·001). In multivariable analysis, negative predictors of local tumour progression-free survival were a minimum ablation margin of less than 5 mm (hazard ratio (HR) 2·48, 95 per cent c.i. 1·31 to 4·72; P = 0·006) and mutant RAS (HR 3·01, 1·60 to 5·77; P = 0·001).

CONCLUSION

Mutant RAS is associated with an earlier and higher rate of local tumour progression in patients undergoing ablation of CLMs.