Nivolumab with carboplatin, paclitaxel, and bevacizumab for first-line treatment of advanced nonsquamous non-small-cell lung cancer.

BACKGROUND: This international, randomized, double-blind phase III study (ONO-4538-52/TASUKI-52) evaluated nivolumab with bevacizumab and cytotoxic chemotherapy as first-line treatment for nonsquamous non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Between June 2017 and July 2019, this study enrolled treatment-naïve patients with stage IIIB/IV or recurrent nonsquamous NSCLC without sensitizing EGFR, ALK, or ROS1 alterations. They were randomly assigned in a 1 : 1 ratio to receive nivolumab or placebo in combination with carboplatin, paclitaxel, and bevacizumab every 3 weeks for up to six cycles, followed by nivolumab/placebo with bevacizumab until progressive disease or unacceptable toxicity. The primary endpoint was progression-free survival (PFS) assessed by an independent radiology review committee (IRRC). RESULTS: Overall, 550 patients from Japan, Korea, and Taiwan were randomized; of these patients, 273 and 275 received the nivolumab and placebo combinations, respectively. In the present preplanned interim analysis with a median follow up of 13.7 months, the IRRC-assessed median PFS was significantly longer in the nivolumab arm than in the placebo arm (12.1 versus 8.1 months; hazard ratio 0.56; 96.4% confidence interval 0.43-0.71; P < 0.0001). The PFS benefit was observed across all patients with any programmed death-ligand 1 (PD-L1) expression levels including PD-L1-negative patients. The IRRC-assessed objective response rates were 61.5% and 50.5% in the nivolumab and placebo arms, respectively. The incidence of treatment-related adverse events of grade 3 or 4 was comparable between the two arms; treatment-related adverse events leading to death were observed in five and four patients in the nivolumab and placebo arms, respectively. CONCLUSION: The TASUKI-52 regimen should be considered a viable new treatment strategy for treatment-naïve patients with advanced nonsquamous NSCLC.

Genetic association of the very low density lipoprotein (VLDL) receptor gene with sporadic Alzheimer's disease.

A specific isoform of apolipoprotein E has been associated with the accelerated rate of disease expression of sporadic Alzheimer's disease (AD) and late-onset familial AD (FAD). An earlier age at onset has also been demonstrated in familial AD patients with mutations in the amyloid precursor protein (APP) gene (APP717 and APP670/671)13 carrying the APOE epsilon-4 allele compared to those who do not, but not in familial AD patients with APP692 or 693 mutations, or in chromosome 14-linked familial AD patients. Hypothesizing that receptors for apoE-containing lipoproteins act as a potential risk factor for AD, we performed an association study using a polymorphic triplet (CGG) repeat in the gene for the VLDL receptor (VLDL-R), a receptor for apoE-containing lipoproteins. The frequency of the 5-repeat allele was significantly higher in all of the Japanese sporadic AD patients (P < 0.02) than in the Japanese controls. Moreover, the odds ratio was significantly increased in the AD patients homozygous for the 5-repeat allele (OR = 2.1, 95% CI = [1.1-4.2]). Multiple logistic regression analysis reveals that the relative risk conferred by the presence of two copies of the 5-repeat allele and at least one copy of the APOE epsilon-4 allele is 8.7 (95% CI = [2.9-25.8]). Our results suggest that the VLDL-R gene is a susceptibility gene for AD.

The prognostic value of 18F-FDG PET/CT taken immediately after completion of radiotherapy for lung cancer treated with concurrent chemoradiotherapy: A pilot study.

PURPOSE: The prognostic value of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) taken immediately after completion of radiotherapy in lung cancer patients is not well known. The purpose of this study is to assess the prognostic value of PET/CT taken immediately after completion of radiotherapy in lung cancer patients. MATERIALS AND METHODS: Patients with primary lung cancer planned to undergo concurrent chemoradiotherapy were enrolled. Patients underwent PET/CT scans at 3 time points: before radiotherapy, within 24hours of completing radiotherapy (im-PET/CT), and 2-9 months after radiotherapy (post-PET/CT). Maximum standardized uptake value (SUVmax) was obtained. A post-PET/CT-SUVmax cut-off of 2.5 was determined as radiotherapy success. RESULTS: Nineteen patients were enrolled. im-PET/CT-SUVmax for patients in the high post-PET/CT-SUVmax group was significantly higher than that of the low group (P=0.004). Receiver operator curve analysis indicated that im-PET/CT-SUVmax of 4.35 was an optimal cut-off value to discriminate between the two groups. Multivariable analysis showed that a high im-PET/CT-SUVmax was significantly associated with a high post-PET/CT-SUVmax (P=0.003). CONCLUSION: PET/CT-SUVmax taken immediately following radiotherapy was associated with that evaluated 2-9 months after radiotherapy.

Malignancy following kidney transplantation.

A cohort of 429 patients who received kidney grafts between 1973 and 2007 at our hospital was studied for the incidence and sites of malignancy. Sixty-two malignant diseases developed in 57 of 429 patients (13.3%). The cumulative incidences of malignancy increased markedly in the second and third posttransplantation decades. The overall rates were 1.8% at 5 years, 6.7% at 10 years, 12.5% at 15 years, 17.3% at 20 years, and 25.6% at 25 years. In the second and third posttransplantation decades, patients without malignancy showed significantly superior survival versus than those with cancer (P = .0002). Their survival rates were 83.4% versus 86.9% at 10 years and 63.1% versus 80.3% at 20 years, respectively. Skin cancer, renal cell carcinoma of the native kidney, hepatocellular carcinoma, posttransplantation lymphoproliferative disease, uterine cancer, and colorectal cancer were common in our series. The 5-year survival rates after the treatment of malignancy were better for skin cancer and renal cell carcinoma of the native kidney. Concerning the effects of immunosuppression, the tacrolimus-based group displayed a higher incidence among 3 groups (P = .0044).

Inhibition of diet-induced atheroma formation in transgenic mice expressing apolipoprotein E in the arterial wall.

Apolipoprotein E (apoE) plays a crucial role in lipoprotein metabolism both in plasma and in peripheral tissues. To test whether apoE in the vascular wall has a direct and local effect on atherogenesis, we established transgenic mice expressing human apoE under control of H2 Ld promoter. Studies on mRNA levels and immunohistochemistry demonstrated that this line was characterized by high expression of human apoE in the arterial wall while its expression was relatively low in other tissues as compared with the respective endogenous expression of mouse apoE. They showed no difference in plasma cholesterol levels and lipoprotein profile from controls when fed both normal and atherogenic diets. However, after 24 wk of an atherogenic diet, the formation of fatty streak lesions in proximal aorta was markedly inhibited in transgenic mice as compared with controls. Both lesion area and esterified cholesterol content were < 30% of those in controls. In a tissue cholesterol labeling study with 3H-cholesterol, the specific activity of aorta cholesterol was much less in transgenic mice, suggesting that apoE enhances cholesterol efflux from the aortic wall into plasma. Thus, apoE has anti-atherogenic action which is mediated via enhancing reverse cholesterol transport from arterial wall.

Secretion-recapture process of apolipoprotein E in hepatic uptake of chylomicron remnants in transgenic mice.

To investigate the role of apoE in hepatic uptake of chylomicron remnants, we studied chylomicron metabolism in transgenic mice overexpressing apoE in the liver. Plasma clearance of injected 125I-labeled human chylomicrons was fivefold faster in transgenic mice than in controls. Immunohistochemistry demonstrated that apoE was specifically localized at the basolateral surface of hepatocytes from fasted transgenic mice. After injection of a large amount of chylomicrons, the density of the cell surface apoE was markedly reduced and vesicular staining was observed in the cytoplasm, suggesting that the cell surface apoE was used for hepatic endocytosis of chylomicrons and remnants. Polyacrylamide gel analysis of chylomicrons and remnants that had been reisolated from plasma and from liver membrane after the injection of chylomicrons showed the particles to be enriched with apoE mainly after their influx into the liver rather than during their residence in plasma. These results provide strong evidence for the secretion-recapture process of apoE, whereby chylomicron remnants enter the sinusoidal space, acquire apoE molecules, and subsequently are endocytosed. Data from experiments with very low density lipoprotein and LDL showed that this system is specific for chylomicron remnants.

The transforming potential of the c-erbB-2 protein is regulated by its autophosphorylation at the carboxyl-terminal domain.

The mutant c-erbB-2 protein with Glu instead of Val-659 exhibited transforming activity in NIH 3T3 cells. This protein showed enhanced tyrosine kinase activity in vitro and enhanced autophosphorylation at Tyr-1248 located proximal to the carboxyl terminus. Enhanced tyrosine phosphorylation of several cellular proteins was detected in cells expressing the Glu-659 c-erbB-2 protein. Introduction of an additional mutation at the ATP-binding site (Lys-753 to Met) of this protein resulted in abolition of its transforming ability. These data indicate that the transforming potential of c-erbB-2 is closely correlated with elevated tyrosine kinase activity of the gene product. To investigate the role of autophosphorylation in cell transformation, we introduced an additional mutation at the autophosphorylation site of the Glu-659 c-erbB-2 protein (Tyr-1248 to Phe). This mutant protein exhibited lower tyrosine kinase activity and lower transforming activity. On the other hand, when the carboxyl-terminal 230 amino acid residues were deleted from the c-erbB-2 protein, the tyrosine kinase activity and cell-transforming activity of the protein were enhanced. Thus, the carboxyl-terminal domain, which contains the major autophosphorylation site, Tyr-1248, may regulate cellular transformation negatively and autophosphorylation may eliminate this negative regulation.

A clinicopathologic study of p27(kip1) expression in renal allograft biopsy.

BACKGROUND: P27 (Kip1) is an inhibitor of cyclin-dependent kinases/cyclin complex that keeps mature cells growth-arrested. In IgA nephropathy, a decreased p27kip1 expression in podocytes has been reported to be related to lesion formation of focal segmental glomerulosclerosis and renal dysfunction. We reviewed the p27kip1 expression in transplanted kidneys. METHODS: p27kip1 expression was examined immunohistochemically in 26 allograft biopsy specimens. RESULTS: p27kip1 expression was recognized in podocytes. Patients with more than 0.5 g proteinuria showed fewer p27kip1-positive cells than those with less than 0.5 g proteinuria. The decreased p27kip1 expression in podocytes was related to cg and ah of the Banff 97 classification. In the two cases in which p27kip1 expression was remarkably decreased, elevation of the serum creatinine level was recognized at the time of biopsy, resulting in kidney transplant loss. The histological findings were chronic/sclerosing allograft nephropathy grade II-(b) in both cases. CONCLUSION: In conclusion, decreased p27kip1 expression in podocytes suggested a significant role in proteinuria among renal transplant recipients.

Development of an immunochromatographic test kit for rapid detection of bovine viral diarrhea virus antigen.

An immunochromatographic test was developed for rapid diagnosis of bovine viral diarrhea virus (BVDV) infections using monoclonal antibodies against the nonstructural protein, NS3, of the virus. The kit detected specifically the NS3 of various BVDV strains. Using the kit, leukocyte extracts of cattle infected persistently with BVDV were found positive while those of healthy cattle were negative. The sensitivity and specificity of this kit in compared with virus isolation were 100% and 97.2%, respectively. Furthermore, the test also gave positive results for calves infected acutely with BVDV in experimental infection. The BVDV antigen was detected in 1 ml of blood using a relatively simple procedure. This test kit should be useful for rapid diagnosis of BVD.

Efficient tumor suppression by glioma-specific murine cytotoxic T lymphocytes transfected with interferon-gamma gene.

We have recently shown that exogenous expression of the mouse interferon-gamma (IFN-gamma) gene augmented the cell-killing potential of a line of cytotoxic T lymphocytes (CTLs) specific against a murine glioma line (203-glioma). In the present work, we further investigated the in vivo antitumor effects of the E gamma-6 and E gamma-9 sublines of this CTL line transfected with the IFN-gamma gene. Using the Winn assay to test the neutralization of subcutaneous gliomas, we determined that these CTL sublines were more effective than the E-4 parent CTL line and that suppression of the tumor growth was dependent on the number of effector cells (CTLs). Moreover, intravenous injection of E gamma-9 cells was more effective in suppressing the tumor growth than intravenous injection of E-4 cells. These results suggest that transfection of antitumor effector cells with the IFN-gamma gene could improve the efficacy of adoptive immunotherapy against cancer.

Characteristic immunological responses to an experimental mouse brain tumor.

Immunological responses to an experimental brain tumor of mice [the 20-methylcholanthrene-induced malignant glioma, 203-glioma)] were investigated. The killer T-cell activity of spleen cells, which was specific against 203-glioma cells, began to be severely impaired 2 weeks after intracranial inoculation; this impairment was concurrent with increased intracranial pressure, which was due to developing tumor growth. On the other hand, the killer T-cell activity continued for over 4 weeks in mice inoculated with the mitomycin C-treated tumor cells. Surface marker analysis showed that Lyt-1-2,3+ killer T-cells were predominant in intracranial tumor-bearing mice, whereas both Lyt-1-,2,3+ and Lyt-1+,2,3+ killer T-cells were equally present in s.c. tumor-bearing mice. The effects of adult thymectomy on the immune responses against 203-glioma were also investigated in intracranial and s.c. tumor-bearing mice. In both the intracranially and s.c. inoculated groups, killer T-cell activity was increased in mice thymectomized before 3 weeks and decreased in mice thymectomized before 10 weeks. In these mice, Lyt-1+,2,3+ killer T-cells were not detected, which suggests strongly that the progenitors of Lyt-1+,2,3+ killer T-cells are short-lived lymphocytes in contrast to those of Lyt-1-,2,3+ killer T-cells, which survive more than 10 weeks after adult thymectomy.

Specific adoptive immunotherapy with tumor-specific cytotoxic T-lymphocyte clone for murine malignant gliomas.

The efficacy of glioma-specific cytotoxic T-lymphocyte for a syngeneic murine malignant glioma (a 20-methylcholanthrene-induced ependymoblastoma, 203-glioma) was investigated. The cytotoxic clone (G-CTLL 1), established and expanded exponentially by T-cell growth factor, has retained target specificity for more than 6 months. In adoptive therapy and Winn assay, the in vivo antitumor activity of G-CTLL 1 was demonstrated against mice inoculated intracranially with 203-glioma cells. The therapeutic effects in adoptive immunotherapy were largely dependent on dose and time of i.v. administration, although the therapy was rather ineffective in condition of increased intracranial pressure due to the tumor growth. The mechanisms responsible for the in vivo protection were probably related to the killing activity of G-CTLL 1 or the tumor-specific production of immune interferon by G-CTLL 1.

Immunoregulatory effects of interleukin 2 and interferon on syngeneic murine malignant glioma-specific cytotoxic T-lymphocytes.

The effects of interleukin 2 (IL2) and interferon (IFN) on the generation and lytic activation of syngeneic murine malignant glioma (a methylcholanthrene-induced ependymoblastoma of C57BL/6 mouse origin, 203-glioma)-specific cytotoxic T-lymphocyte (G-CTL) were investigated. The surface marker analysis showed that G-CTLs from both intracranial and s.c. tumor-bearing mice were composed of thymectomy-resistant (mature) Lyt-1-.2.3+ and thymectomy-sensitive (immature) Lyt-1+.2.3+ CTLs, which markedly decreased concurrently with increased intracranial pressure. G-CTLs were confirmed to be activated with target specificity by both factors in a different way. The CTL activation by IL2 (20 units/ml) remained for a longer time, although a lag time of 5 days after initial culture was required. IL2 influenced Lyt-1+.2.3+ CTLs to proliferate and develop the lytic potential. In contrast, even a 3-h incubation with IFN (1000 units/ml) could enhance the cytotoxicity, but the augmenting effects were observed no longer than 5 days later. IFN activated Lyt-1-.2.3+ CTLs and increased their proportion of the total cell population with a simultaneous decrease of Lyt-1+.2.3+ CTLs. Therefore, it was suggested that IL2 may provide a growth of CTL populations and that IFN can accelerate recruitment of new effectors, causing activation of the lytic process.

Augmentation of tumor targeting in a line of glioma-specific mouse cytotoxic T-lymphocytes by retroviral expression of mouse gamma-interferon complementary DNA.

As an initial approach to experiments directed toward effective adoptive immunotherapy for cancer using lymphokine genes, we transferred retrovirally a complementary DNA encoding mouse gamma-interferon (IFN-gamma) into a specific cytotoxic T-lymphocyte clone, designated E-4, against 203 glioma cells (a 20-methylcholanthrene-induced mouse glioma line) and confirmed the efficacy of IFN-gamma production from the exogenous gene on augmentation of tumor targeting. Of five, two gene-transferred subclones constitutively produced 8 to 10 times the amount of IFN-gamma as compared with the parental E-4. Correspondingly, these two subclones exhibited 2 to 3 times higher killing activity against 203 glioma than the parental cells; the enhancement of the killing activities was abrogated by an adequate addition of anti-IFN-gamma antibody. No alteration was seen after the gene transfer in cell surface phenotypes, Thy-1+, Lyt-1-, Lyt-2+,3+, and asialo-GM1-. The surface expression of a major histocompatibility complex Class I antigen, H-2Kb, was not altered remarkably, but the Class II antigen, I-Ab, was partially and slightly enhanced on the two IFN-gamma-producing sublines mentioned above on fluorescence-activated cell sorter analysis. Since it is considered that in the vicinity of the constitutively IFN-gamma producing cytotoxic T-lymphocyte cells tumor cells are exposed to a high concentration of IFN-gamma, the cells may be stimulated to induce or enhance the expression of surface antigens including major histocompatibility complex antigens as well as tumor-associated antigens relevant to immune recognition. The 203 glioma cells pretreated with IFN-gamma were more efficiently killed by both the parental E-4 and the gene-transferred sublines. Taken together, the results suggested that the augmented specific tumor-killing activity of our gene-transferred cytotoxic T-lymphocytes was ascribed to the constitutive production of IFN-gamma derived from the exogenous gene.

Factors predicting successful discontinuation of continuous renal replacement therapy.

This multicentre, retrospective observational study was conducted from January 2010 to December 2010 to determine the optimal time for discontinuing continuous renal replacement therapy (CRRT) by evaluating factors predictive of successful discontinuation in patients with acute kidney injury. Analysis was performed for patients after CRRT was discontinued because of renal function recovery. Patients were divided into two groups according to the success or failure of CRRT discontinuation. In multivariate logistic regression analysis, urine output at discontinuation, creatinine level and CRRT duration were found to be significant variables (area under the receiver operating characteristic curve for urine output, 0.814). In conclusion, we found that higher urine output, lower creatinine and shorter CRRT duration were significant factors to predict successful discontinuation of CRRT.

Altered expression of the retinoblastoma (RB) gene in small-cell carcinoma of the lung.

Nine lung small-cell carcinoma (SCC) cell lines and 9 lung non-SCC cell lines were examined for structural changes of the retinoblastoma (RB) gene as well as its expression using a complementary DNA probe. The RB protein product was investigated using an anti-RB antibody which we produced. Although homozygosity or hemizygosity of the RB gene was suggested in 8 of 9 SCCs and one of 2 large cell carcinomas (LCCs) by Southern blot analysis using an RB cDNA probe and polymorphic DNA markers for chromosome 13, no obvious structural changes of the RB gene were detected in these 18 cell lines. However, RB transcripts were either markedly reduced in quantity or abnormal in length in 3 of 9 SCCs. The specific 115 kD protein was not immunoprecipitated by the anti-RB antibody in all 9 SCCs with either normal or abnormal size RB mRNA. Three of 4 adenocarcinomas (AdCs), all 3 squamous cell carcinomas, and one of 2 LCCs expressed normal size RB mRNA, and the 115 kD protein was immunoprecipitated by the anti-RB antibody. The 115 kD protein was also absent in one of 2 LCCs with shortened RB mRNA and in one of 4 AdCs with low level of RB mRNA expression. These results strongly suggest that inactivation of the RB gene might be involved in the development of lung cancers, especially of SCCs.

Tumor accumulation of novel RES-avoiding liposomes.

For passive targeting of liposomes to tumor tissues, we earlier developed reticuloendothelial system (RES)-avoiding liposomes modified with a uronic acid derivative, palmityl-D-glucuronide (PGlcUA) (Namba, Y., Sakakibara, T., Masada, M., Ito, F. and Oku, N. (1990) Chem. Pharm. Bull. 38, 1663-1666). In this present study, we examined the blood clearance and biodistribution of PGlcUA-liposomes (dipalmitoylphosphatidylcholine/cholesterol/PGlcUA = 40:40:20 as a molar ratio) in normal and tumor-bearing mice. Liposomes containing dipalmitoylphosphatidylglycerol (DPPG) instead of PGlcUA was also examined as a control. When [3H]inulin-encapsulated PGlcUA-liposomes and DPPG-liposomes were intravenously injected into normal mice, approx. 50% of the 3H radioactivity was recovered from the liver, the bulk of RES, at 12 h after administration of DPPG-liposomes, while only approx. 20% of it was found there when PGlcUA-liposomes were administered. Radioactivity remaining in the plasma at 12 h after injection was 5-fold higher when PGlcUA-liposomes were injected than when DPPG-liposomes were used. Biodistribution of liposomes in tumor-bearing mice was also examined. Mice were inoculated with 10(7) S180 cells into the hind leg. After 1 week, liposomes were injected. Radioactivity of [3H]inulin originally encapsulated in the PGlcUA-liposomes accumulated in the tumor to an extent 3-4-fold higher than that of the marker in DPPG-liposomes. Liver/tumor ratio of the radioactivity was 12 for DPPG-liposomes and only 2 for PGlcUA-liposomes. This latter value is the lowest of various liposome formulations ever reported.

Antitumor activity of vincristine encapsulated in glucuronide-modified long-circulating liposomes in mice bearing Meth A sarcoma.

Liposomes modified with the uronic acid derivative palmityl-D-glucuronide (PGlcUA) have a long circulation time and tend to accumulate in the tumors of tumor-bearing mice. Taking advantage of this character, we investigated the therapeutic effect of vincristine (VCR) encapsulated in liposomes containing PGlcUA (dipalmitoylphosphatidylcholine/cholesterol/PGlcUA = 4:4:1 as a molar ratio) on tumor-bearing mice. VCR was loaded into liposomes by a remote loading method, and then free or liposomal VCR was injected intravenously into BALB/c mice bearing Meth A sarcoma implanted subcutaneously 5 days before hand. Single-dose administration of VCR (3.0 mg/kg) in PGlcUA-liposomes significantly suppressed tumor growth, and prolonged the survival time (T/C = 1.37). Furthermore, two-dose administration of the liposomes cured one third of the animals. The therapeutic effect of PGlcUA-liposomes was greater than that of control liposomes containing dipalmitoylphosphatidylglycerol instead of PGlcUA. PGlcUA-liposomes might thus be a useful tool for delivering antitumor agents to tumor tissues.

Effect of serum protein binding on real-time trafficking of liposomes with different charges analyzed by positron emission tomography.

Liposomes have been used as carriers of various materials and as tools for gene transfer: for the latter purpose, positively charged liposomes are usually used. To evaluate the stability in the presence of serum and the in vivo behavior of such liposomes as well as those aspects of neutral and negatively charged liposomes, we investigated liposomal agglutinability in the presence of serum, serum protein binding to these liposomes, and real-time liposomal trafficking by a non-invasive method using positron emission tomography (PET). Liposomes composed of dipalmitoylphosphatidylcholine, cholesterol without or with charged lipid were prepared in the presence of mannitol, and the turbidity change in the presence of serum was determined. Turbidity increase was not observed for so-called long-circulating liposomes, i.e., liposomes modified with glucuronic acid or with poly(ethylene glycol), or for negatively charged liposomes containing dicetyl phosphate (DCP), phosphatidylglycerol, or phosphatidylserine. On the contrary, a significant turbidity increase was observed when positively charged liposomes modified with stearylamine, stearyltrimethylammonium chloride or 1,2-dimyristyloxypropyl-3-dimethylhydroxyethyl bromide (DMRIE), which is known as a component of liposomes for gene transfer, were used. These liposomes were found to have bound a high amount of serum proteins after separation of unbound serum proteins by use of a spin column. The liposomal trafficking in vivo was determined for three kinds of liposomes, i.e., liposomes with DMRIE, those with DCP, and those without charged lipids. These liposomes were prepared in the presence of 2-[18F]fluoro-2-deoxy-D-glucose ([2-18F]FDG), and the [2-18F]FDG-labeled liposomes were administered to mice to perform PET scans. Positively charged liposomes containing DMRIE showed high accumulation in the liver compared with neutral and negatively charged liposomes. Since DMRIE-liposomes tended to aggregate in the presence of serum, and to be associated with serum protein, these characteristics may lead to the high uptake of DMRIE-liposomes by the liver.

Rapid increase in circulating leptin in ventromedial hypothalamus-lesioned rats: role of hyperinsulinemia and implication for upregulation mechanism.

The mechanisms of marked increase in plasma leptin soon after ventromedial hypothalamus (VMH) lesions were investigated. Although rats did not gain body weight or parametrial fat-pad mass 24 h after the operation, the acute VMH-lesioned rats exhibited substantial five- and fourfold increases in plasma leptin levels compared with sham-operated control rats in fed (22.6 +/- 3.2 vs. 5.8 +/- 1.2 ng/ml) and fasted (8.8 +/- 2.0 vs. 2.3 +/- 0.3 ng/ml) states, respectively. Plasma insulin concentration was doubled in VMH-lesioned rats compared with sham-operated controls in both fed and fasting states. Northern blot analysis revealed that mRNA of ob gene was not increased in parametrial fat pad of animals 24 h after the creation of VMH lesions. However, leptin content in the fat pad was significantly increased in VMH-lesioned rats compared with sham-operated controls (32.2 +/- 4.7 vs. 17.4 +/- 2.3 ng/g wet tissue). The leptin content in parametrial fat pad was highly correlated with plasma leptin concentrations (r = 0.898, P < 0.001). To define the effect of hyperinsulinemia on their hyperleptinemia, a small dose of streptozotocin (STZ) (25 mg/kg body wt) was intravenously administered into rats 5 days before the creation of VMH lesions. Plasma insulin levels were not increased after VMH lesions in STZ-pretreated rats. Plasma leptin levels were halved in the absence of hyperinsulinemia, but still remained twofold higher than those in their sham-operated counterparts (9.9 +/- 1.3 vs. 4.8 +/- 0.7 ng/ml). These results indicate that the destruction of VMH rapidly promotes leptin production before obesity develops through an enhanced translational process in which hyperinsulinemia occurring after VMH lesioning plays an important role. The present study also suggests that there are other mechanisms that rapidly upregulate leptin production in adipocytes in VMH-lesioned rats in which the target organ of this hormone has been destroyed.