Fourfold daily growth rate in multicellular marine alga Ulva meridionalis

Microalgae with high growth rates have been considered as promising organisms to replace fossil resources with contemporary primary production as a renewable source. However, their microscopic size makes it hard to be harvested for industrial applications. In this regard, multicellular macroalgae are more suitable for harvesting. Here, we show that Ulva meridionalis has the highest growth rate ever reported for a multicellular autotrophic plant. Contrasted to the known bloom-forming species U. prolifera growing at an approximately two-fold growth rate per day in optimum conditions, U. meridionalis grows at a daily rate of over fourfold. The high growth ability of this multicellular alga would provide the most effective method for CO2 fixation and biomass production.

Drivers of land-use changes in societies with decreasing populations: A comparison of the factors affecting farmland abandonment in a food production area in Japan

The extraordinary population growth of the 20^th century will subside in the 21^st century, followed by depopulation, constituting the first population decline phase in human history in Japan and other developed countries. The drivers of land-use change during the population decline phase are expected to differ from those of the population growth phase; however, research on land-use drivers during the decline phase is limited. Identifying these drivers is necessary to develop effective management plans for biodiversity and ecosystem services in the decline phase. First, we calculated the probability of farmland abandonment in Hokkaido, a Japanese food production area, from 1973–2009 and divided the period into the population growth phase (1978–1997) and the decline phase (1997–2009). We examined various geographical and social factors that were assumed to alter the land use during these two phases. Geographical and social conditions are key factors in determining the probability of farmland abandonment, but their influences varied between the two phases. The farmlands located on geographically uncultivable sites, such as marginal, underproductive, narrow, and steep land, were abandoned during these phases; however, social conditions, such as the distance from densely inhabited districts (DIDs) and the population, exerted opposite effects during these two phases. Farmland abandonment occurred near DIDs (i.e., urban areas) during the population growth phase, whereas farmland abandonment occurred far from DIDs and sparsely populated farmlands during the decline phase. Farmland abandonment was strongly affected by government policy during the population growth phase, but the policy weakened during the decline phase, which triggered farmland abandonment throughout Hokkaido. The geographical and social drivers found in the present study may provide new insights for other developed countries experiencing depopulation problems.

Modeling future wildlife habitat suitability: serious climate change impacts on the potential distribution of the Rock Ptarmigan Lagopus muta japonica in Japan's northern Alps

Background

The Rock Ptarmigan Lagopus muta japonica lives in the alpine zones of central Japan, which is the southern limit of the global distribution for this species. This species is highly dependent on alpine habitats, which are considered vulnerable to rapid climate change. This study aimed to assess the impact of climate change on potential L. muta japonica habitat based on predicted changes to alpine vegetation, to identify population vulnerability under future climatic conditions for conservation planning. We developed species distribution models, which considered the structure of the alpine ecosystem by incorporating spatial hierarchy on specific environmental factors to assess the potential habitats for L. muta japonica under current and future climates. We used 24 general circulation models (GCMs) for 2081–2100 as future climate conditions.

Results

The predicted potential habitat for L. muta japonica was similar to the actual distribution of the territories in the study area of Japan’s northern Alps (36.25–36.5°N, 137.5–137.7°E). Future potential habitat for L. muta japonica was projected to decrease to 0.4% of the current potential habitat in the median of occurrence probabilities under 24 GCMs, due to a decrease in alpine vegetation communities. Some potential habitats in the central and northwestern part of the study area were predicted to be sustained in the future, depending on the GCMs.

Conclusions

Our model results predicted that the potential habitats for L. muta japonica in Japan’s northern Alps, which provides core habitat for this subspecies, would be vulnerable by 2081–2100. Small sustainable habitats may serve as refugia, facilitating the survival of L. muta japonica populations under future climatic conditions. Impact assessment studies of the effect of climate change on L. muta japonica habitats at a nationwide scale are urgently required to establish effective conservation planning for this species, which includes identifying candidate areas for assisted migration as an adaptive strategy.

Electronic supplementary material

The online version of this article (10.1186/s12898-019-0238-8) contains supplementary material, which is available to authorized users.

Analyzing community structure subject to incomplete sampling: hierarchical community model vs. canonical ordinations

Recently developing hierarchical community models (HCMs) accounting for incomplete sampling are promising approaches to understand community organization. However, pros and cons of incorporating incomplete sampling in the analysis and related design issues remain unknown. In this study, we compared HCM and canonical redundancy analysis (RDA) carried out with 10 different dissimilarity coefficients to evaluate how each approach restores true community abundance data sampled with imperfect detection. We conducted simulation experiments with varying numbers of sampling sites, visits, mean detectability and mean abundance. Performance of HCM was measured by estimates of "expected" (mean) abundance ( λ ^ ij ) and realized abundance ( N ^ ij : direct estimate of site- and species-specific abundance). We also compared HCM and different types of RDA (normal, partial, and weighted), all performed with the same ten different dissimilarity coefficients, with unequal number of visits to sampling sites. In addition, we applied the models to a virtual survey carried out on the Barro Colorado Island tree plot data for which we know true community abundance. Simulation experiments showed that N ^ ij yielded by HCM best restored the underlying abundance of constituent species among 12 abundance estimates by HCM and RDA regardless if the sampling was equal or unequal. Mean abundance predominantly affected the performance of HCM and RDA while λ ^ ij yielded by HCM had comparable performance to percentage difference and Gower dissimilarity coefficients of RDA. Relative performance of RDA types depended on the combination of dissimilarity coefficients and the distribution of sampling effort. Best performance of N ^ ij followed by λ ^ ij , percentage difference and Gower dissimilarity were also observed for the analysis of tree plot data, and graphical plots (triplots) based on λ ^ ij rather than N ^ ij clearly separated the effects of two environmental covariates on the abundance of constituent species. Under our conditions of model evaluation and the method, we concluded that, in terms of assessing the environmental dependence of abundance, HCMs and RDA can have comparable performance if we can choose appropriate dissimilarity coefficients for RDA. However, since HCMs provide straightforward biological interpretations of parameter estimates and flexibility of the analysis, HCMs would be useful in many situations as well as conventional canonical ordinations.

Land abandonment and changes in snow cover period accelerate range expansions of sika deer

Ongoing climate change and land‐use change have the potential to substantially alter the distribution of large herbivores. This may result in drastic changes in ecosystems by changing plant–herbivore interactions. Here, we developed a model explaining sika deer persistence and colonization between 25 years in terms of neighborhood occupancy and habitat suitability. We used climatic, land‐use, and topographic variables to calculate the habitat suitability and evaluated the contributions of the variables to past range changes of sika deer. We used this model to predict the changes in the range of sika deer over the next 100 years under four scenario groups with the combination of land‐use change and climate change. Our results showed that both climate change and land‐use change had affected the range of sika deer in the past 25 years. Habitat suitability increased in northern or mountainous regions, which account for 71.6% of Japan, in line with a decrease in the snow cover period. Habitat suitability decreased in suburban areas, which account for 28.4% of Japan, corresponding to land‐use changes related to urbanization. In the next 100 years, the decrease in snow cover period and the increase in land abandonment were predicted to accelerate the range expansion of sika deer. Comparison of these two driving factors revealed that climate change will contribute more to range expansion, particularly from the 2070s onward. In scenarios that assumed the influence of both climate change and land‐use change, the total sika deer range increased by between +4.6% and +11.9% from the baseline scenario. Climate change and land‐use change will require additional efforts for future management of sika deer, particularly in the long term.

Novel distribution pattern between coexisting sexual and obligate asexual variants of the true estuarine macroalga Ulva prolifera

Where sexual and asexual forms coexist within a species, the asexuals are often found to be prevalent in marginal habitats. This asexual distribution pattern has received evolutionary attention linked to the paradox of sex. In many marine species, there is a distributional trend of asexual modes being more common in lower salinity waters regarded as the ecogeographic marginal, being explained by negative effects of low salinities on sexual reproductive success. However, the distribution pattern of estuarine species recently adapted to low salinity waters has remained unknown. The brackish macroalga Ulva prolifera being a major benthic component of estuarine ecosystems includes a sexual variant and obligate asexual variants by means of motile spores. We examined the sexual-asexual distribution pattern of this alga along a salinity gradient in river estuaries. Surprisingly, opposite to the distributional trend of marine organisms, the results clearly showed the persistent predominance of sexuals in the lower salinity reaches than the asexuals. In addition, a frequent alternating of dioecious gametophytes and sporophytes in the sexual population was observed, suggesting the sexual reproductive process would be robustly performed in the low salinity waters. Considering U. prolifera had evolved from the ancestral marine species to become a true estuarine species of which the core habitat is the low salinity reaches, in a broad sense its sexual-asexual distribution pattern would be involved in asexual marginal occupations of the species range previously reported in other organisms. Based on the frozen niche variation model, we can give a concise explanation for the evolutionary process of this pattern; multiple asexuals with frozen genotypic variation had arisen from sexual ancestors undergoing low salinity adaptation and share the estuarine habitat with the sexuals at present.

Distinct effects of pitavastatin and atorvastatin on lipoprotein subclasses in patients with Type 2 diabetes mellitus

AIMS

Effects of pitavastatin and atorvastatin on the lipid profile and lipoprotein subclasses were compared in patients with Type 2 diabetes with dyslipidaemia.

METHODS

Patients with Type 2 diabetes with hypercholesterolaemia and/or hypertriglyceridaemia were randomized to receive pitavastatin 2 mg (n = 16) or atorvastatin 10 mg (n = 15) for 6 months, and blood lipid and lipoprotein profiles and cholesterol and triglyceride contents of 20 lipoprotein subclasses, determined by high-performance liquid chromatography, were compared.

RESULTS

At baseline, cholesterol in VLDL and LDL subclasses were increased equally in two groups of patients with diabetes as compared with normolipidaemic control subjects. As compared with baseline, serum levels of total cholesterol, LDL cholesterol, non-HDL cholesterol, LDL cholesterol:HDL cholesterol ratio and apolipoprotein B were decreased after 1, 3 and 6 months of treatment with atorvastatin and pitavastatin. Serum triglyceride levels were decreased after 1, 3 and 6 months of atorvastatin, but only at 3 months of pitavastatin. Serum HDL cholesterol was increased after 1, 3 and 6 months of pitavastatin, whereas HDL cholesterol was even decreased after 6 months of atorvastatin. Cholesterol levels of most VLDL and LDL subclasses were decreased equally in both groups. However, only pitavastatin increased cholesterol of medium HDL subclass. Serum triglyceride and triglyceride contents in VLDL and LDL subclasses were decreased only by atorvastatin.

CONCLUSIONS

The impact on lipoprotein subclass profiles was different between pitavastatin and atorvastatin. It may be beneficial to determine lipoprotein subclass profile and select the appropriate statin for each profile in patients with diabetes with an additional cardiovascular risk such as low HDL cholesterol or hypertriglyceridaemia.

Development of an Artificial Myocardium using a Covalent Shape-memory Alloy Fiber and its Cardiovascular Diagnostic Response

The authors have been developing a newly-designed totally-implantable artificial myocardium using a covalent shape-memory alloy fibre (Biometal®, Toki Corporation), which is attached onto the ventricular wall and is also capable of supporting the natural ventricular contraction. This mechanical system consists of a contraction assistive device, which is made of Ti-Ni alloy. And the phenomenon of the martensitic transformation of the alloy was employed to achieve the physiologic motion of the device. The diameter of the alloy wire could be selected from 45 to 250μm. In this study, the basic characteristics of the fiber of 150μm was examined to design the sophisticated mechano-electric myocardium. The stress generated by the fiber was 400gf under the pulsatile driving condition (0.4W, 1Hz). Therefore it was indicated that the effective assistance might be achieved by using the Biometal shape-memory alloy fiber.

Protein kinase B/Akt signalling is required for palmitate-induced beta-cell lipotoxicity

AIM

This study was conducted to clarify cell death and survival signals in pancreatic beta-cell lipotoxicity.

METHODS

Rat insulinoma INS-1 cells, with or without expression of dominant-negative mutant of Akt (K179M), were cultured with palmitate (C16:0) or oleate (C18:1) and cell numbers were determined by 0.2% eosin dye exclusion assay. The Akt activity was determined by anti-3'-phospho-inositide-dependent protein kinase (Akt)/protein kinase B (PKB) or anti-phospho-Akt (Serine 473) immunoblotting, and nuclear protein nuclear factor-kB (NF-kappaB)-binding activity was by supershift analysis.

RESULTS

Twenty-four hours treatment with palmitate increased the INS-1 cell number at 0.1-0.2 mM but decreased the cell number at 0.5-1 mM. Oleate did not affect cell number at 0.1-1.0 mM. Palmitate dose-dependently increased phosphorylation of 473th serine in Akt/PKB. The K179M form of Akt/PKB abolished palmitate-induced cell proliferation at the low dose and death at the high dose. Nuclear protein NF-kappaB binding was enhanced at 0.2 and 0.5 mM of palmitate but decreased at 1.0 mM.

CONCLUSION

Results suggest that Akt/PKB signalling is involved in palmitate-induced cell death and survival of pancreatic beta cell.

Three-dimensional computer-aided design based design sensitivity analysis and shape optimization of the stem using adaptive p-method

The number of stem designs for total hip arthroplasty is increasing, and occasionally design changes have yielded unexpected clinical results. At present, we are not able to clearly identify which parameter of the stem is most important, and the optimum value of many parameters. The goals of this study were to identify which parameter is most important, to understand the effect of design change, and to find the optimum stem shape. For this purpose, we used adaptive p-method together with three-dimensional computer-aided design software program for the design sensitivity analysis (DSA) and shape optimization of the stem. The results suggested that increasing the lateral and medial width of the distal cross-section together with decreasing the medial-lateral width and the medial radius of the distal cross-section from the default value would lead to a decrease in the largest maximum principal stress of the distal cement. The medial width of middle cross-section, however, was not so simple. The result of DSA suggested that decreasing this parameter from the default value decreased the stress in the distal cement, but the optimum shape was obtained by increasing this parameter. The method used in this study will assist our engineers and surgeons in the process of modifying and optimizing the stem design.

[Neonatal conjunctivitis in a hospital at Gran Buenos Aires. Last 5 years up-date]

Neonatal conjunctivitis is one of the most important consultation reasons in the first days of life. Causes may be chemical or infectious. Neonatal conjunctivitis study for common microorganisms and Chlamydia trachomatis is being performed at Posadas Hospital since 1995, in a progressive form. The objective of this study was to know the epidemiological situation in the last five years (1999-2003), and to describe the variations detected between two periods, 1995-1998, and 1999-2003. It was observed no change about C. trachomatis prevalence (8%), during all the time in the population studied. With regard to common microorganisms it was showed a decrease in the second period (36.6%) with respect to the first (52.4%). Likely, the causes may be due to changes about sample collection conditions, or to epidemiological variations. The most frequent microorganisms found were: Staphylococcus aureus 69 (27.6%), Streptococcus pneumoniae 68 (27.2%), and Haemophilus influenzae 64 (25.6%). We consider important to evaluate the kind of ocular secretions at the first consultation, which can lead to a symptomatic treatment that will be corroborated or not, according to microbiological results.

Epstein-Barr virus (EBV) subtype in EBV related oral squamous cell carcinoma in Okinawa, a subtropical island in southern Japan, compared with Kitakyushu and Kumamoto in mainland Japan

AIM

In Okinawa, a subtropical island located between the East China Sea and Pacific Ocean, 2000 km south of mainland Japan, the incidence of oral squamous cell carcinoma is 1.5 times higher than that seen in mainland Japan, and a large number of these patients have been reported to be infected with the Epstein-Barr virus (EBV). This study aimed to gain a better understanding of the pathogenesis of this malignancy in this area by carrying out genomic analysis of EBV.

METHODS

Fifty four patients with oral squamous cell carcinoma reported from 1997 to 1999 in Okinawa were compared with 21 and 20 patients from Kitakyushu and Kumamoto in Kyushu, mainland Japan, respectively. Diagnosis was confirmed by conventional histological examination of paraffin wax sections. EBV was detected by non-isotopic in situ hybridisation (NISH) and the polymerase chain reaction (PCR) (Bam HI-F, EBV nuclear antigen 2 (EBNA2), and latent membrane protein 1 (LMP-1) regions). Sequence analysis of the PCR products was also carried out.

RESULTS

In Okinawa, 25 patients were found to be infected with EBV type A by analysing the 3' sequence divergence of the EBNA2 genes. Six patients were positive for EBV type B, and eight for both type A and B. Therefore, type A virus infection was demonstrated in 33 of 54 patients, and type B in 14 of 54. In total, 39 of 54 patients were infected with EBV. However, the "f" variant was shown in only one patient, who was also infected with type A virus. In contrast, 97.0% of EBV type A infected patients showed a 30 bp deletion of the LMP-1 gene, but those infected with EBV type B did not. Sequence analysis of the type A virus EBNA2 gene revealed slight variations of the sequence (mutations)-(48991)G-->T and (48998)C-->A-in 18 of 33 cases compared with the B95-8 strain, and in 14 cases, in addition to these, a further mutation of (48917)T-->C was demonstrated; in the single remaining case, only one mutation at (49137)A-->G was detected. The mutations at 48991 (G-->T), and 49137 (A-->G) are associated with amino acid changes Arg-->Met and Thr-->Ala, respectively. In contrast, no mutation was seen in the EBNA2 DNA from the 14 cases of type B virus when compared with that of the Jijoye strain. In Kitakyushu and Kumamoto, only 10 of 41 patients (six in Kitakyushu and four in Kumamoto) were infected with EBV. Among them, nine patients were infected with type A virus, and only one patient from Kitakyushu was infected with type B virus. The (48991)G-->T and (48998)C-->A mutations of the EBNA2 region were demonstrated in type A virus, but the (48917)T-->C and (49137)A-->G mutations were not when compared with the B95-8 strain. In the case of type B virus no mutation was noted. A 30 bp deletion was found in these nine cases of type A, but not in type B. The sequence analysis of EBV type A in Okinawa, Kitakyushu, and Kumamoto showed slight variations when compared with B95-8, but EBV type B LMP-1 did not when compared with the Jijoye strains.

CONCLUSION

In Okinawa, EBV infection was frequently demonstrated in oral squamous cell carcinoma (p < 0.001). However, in mainland Japan there was no significant correlation between EBV and oral squamous cell carcinoma. In Okinawa, EBV type B infection is approximately 10 times more common than in the mainland. However, in these areas-Okinawa, Kitakyushu, and Kumamoto-the frequency of the "f " variant was very low, whereas a high incidence of a 30 bp deletion of LMP-1 was noted. The number of EBV (including type A and/or B) infected oral squamous cell carcinomas in Okinawa was about three times higher than that seen in the mainland, although the frequency of oral squamous carcinoma was only 1.5 times higher than that seen in the mainland. A high prevalence of type B virus infection and slight differences in the EBNA2 gene sequence in the type A virus might influence the frequency of this carcinoma in Okinawa.

[Aeromonas species infection with severe clinical manifestation in okinawa, Japan -association with gas gangrene-]

We experienced two patients having Aeromonas species infection with severe clinical manifestations. The one patient was a 15-year-old high school girl student, who had been healthy in her school life, was admitted to the hospital with a sudden onset of left thigh muscle pain and swelling. She subsequently went into septic shock and died one day after admission. Pathological examination on autopsy revealed massive gas formation, skin bullas and ulcers, and extensive severe soft tissue damage throughout the body. Also, all the specimens, including brain, liver, spleen, thigh muscle, and blood in cardiac cavity, were positive for A. veronii biovar sobria. The other patient was 35-year-old man, who suffered from multiple bone fractures during the work in the harbor. One day after admission, he became febrile and went into septic shock. With the presumptive diagnosis of sepsis and gas gangrene, amputation of left thigh was performed. The exudate and aspirate of the amputated portion were repeatedly positive for A. hydrophila. Through the surveillance in Okinawa, Kagoshima, Miyazaki, and Kumamoto Prefectures, a total of 426 isolates from blood cultures were collected in the period from August, 1999 to February, 2000. Of these, 14 isolates (3.3%) were the species of Aeromonas. Of 14 isolates of Aeromonas, 13 were reported from Okinawa and the remaining one was from Kumamoto. Most patients had underlying diseases, particularly liver diseases including liver cirrhosis. The mortality rate was extremely high at 62.5%, and the patients died in short terms after blood culture became positive. With these, Aeromonas species infection is unique to Okinawa, and positive blood culture for Aeromonas species potentially indicates a high-risk, particularly among the patients with underlying diseases.

Differences in EBNA2 and LMP-1 carboxy terminal region sequences of Epstein-Barr virus type A between the tumors in a multiple cancer patient

Using PCR, type A Epstein-Barr virus (EBV) infection was demonstrated in a squamous cell carcinoma of the maxilla (in a 52-year-old man) and the tongue of the same patient 18 years later (at the age of 70). Furthermore, at the age of 72, this patient developed an EBV-infected anaplastic large cell lymphoma. Analysis of the terminal regions of the EBV genome revealed a monoclonal proliferation of EBV-infected lymphoma cells. However, sequence analysis of the EBV revealed a slight difference in the EBNA2 regions between the virus-infected lymphoma and the squamous cell carcinomas. The mutations at 48991 (G-->T) and 48998 (C-->A) were demonstrated in the lymphoma. Although the squamous cell carcinoma of the tongue occurred after an interval of 18 years, the mutation site in the carcinomas was the same, 49137 (A-->G), as compared with B95-8 strain EBV EBNA2. The mutations at 48991 and at 49137 were associated with amino acid changes, Arg-->Met and Thr-->Ala, respectively, but the alteration at 48998 was a silent mutation. Thirty-bp deletion in the LMP-1 carboxy terminal region was demonstrated in the virus-infected lymphoma, but not in the squamous cell carcinomas. On the other hand, HTLV-1 proviral DNA (tax, gag and env) was not detected in the lymphoma, nor was HPV demonstrated in the squamous cell carcinomas, although Okinawa is known as an HTLV-1 and HPV prevalence region. The T-cell receptor beta gene rearrangement was demonstrated in the lymphoma, but the t(2;5) fusion transcript was not detected using PCR. Cytogenetic analysis of the lymphoma cells showed a complex hypertriploid karyotype with 76XY. The type A EBV infection might play a role in the carcinogenesis of the tumors of our patient. Interestingly, the infected virus genome sequences, the EBNA2 and LMP-1 regions, which were closely associated with carcinogenesis in the squamous cell carcinomas and the lymphoma, showed slight differences.

Portal and mesenteric vein and inferior vena cava thrombosis associated with antiphospholipid syndrome

We report a 48-year-old man with thrombosis of the portal and superior mesenteric vein and inferior vena cava associated with primary antiphospholipid syndrome (APS). Primary APS was diagnosed by a positive reaction with anticardiolipin antibody (aCL) and the absence of any evidence suggesting the presence of other disease states known to be associated with aCL. A coeliac angiography showed obstruction of the portal and superior mesenteric vein with prominent collaterals and cavernous transformation. Femoral vein angiography showed total obstruction of the external iliac vein and inferior vena cava, and dilation of the pelvic veins, with contrast medium in the lumbar vein. This case is noteworthy as a report of primary APS accompanied by extensive abdominal and pelvic venous thrombosis.

An outbreak of allergy-like food poisoning

Eight cases of allergy-like food poisoning resulting from the ingestion of yellowfin tuna, which had been kept in stock for 10 days prior to being cooked, are described. The main symptoms were headaches, facial flushing and palpitation. Samples of the ingested fish were analyzed for histamine content, and a high level of histamine was confirmed (310 mg/100 g of fish). Corticosteroids were given to 3 patients who exhibited dyspnea or persistent symptoms, while the remaining patients improved without medication. In situations where allergy-like clinical features are present after the ingestion of food, the possibility of allergy-like food poisoning should be recognized and included in a differential diagnosis.

Expression of Fushi tarazu factor 1 homolog and Pit-1 genes in the pituitaries of pre-spawning chum and sockeye salmon

Fushi tarazu factor-1 (FTZ-F1) and Pit-1 are major pituitary transcription factors, controlling expression of genes coding for gonadotropin (GTH) subunits and growth hormone/prolactin/somatolactin family hormone, respectively. As a first step to investigate physiological factors regulating gene expression of these transcription factors, we determined their mRNA levels in the pituitaries of chum salmon (Oncorhynchus keta) at different stages of sexual maturation. FTZ-F1 gene expression was increased in males at the stage before spermiation, where the levels of GTH alpha and IIbeta subunit mRNAs were elevated. Pit-1 mRNA showed maximum levels at the final stage of sexual maturation in both sexes, when expression of somatolactin gene peaked. To clarify whether gonadotropin-releasing hormone (GnRH) is involved in these increases in FTZ-F1 and Pit-1 gene expression, we examined effects of GnRH analog (GnRHa) administration on their gene expression in maturing sockeye salmon (Oncorhynchus nerka). GnRHa stimulated Pit-1 gene expression in females only, but failed to stimulate FTZ-F1 gene expression in both sexes. The up-regulated expression of FTZ-F1 and Pit-1 genes at the pre-spawning stages suggest that the two transcription factors have roles in sexual maturation of salmonids. Physiological factors regulating gene expression of FTZ-F1 and Pit-1 are discussed in this review.

[A case of acute pulmonary embolism associated with squatting]

The patient was a 69-year-old man with a 3-year history of diabetes mellitus accompanied by cerebral infarction and arteriosclerosis obliterans of the lower extremities. After squatting to clean a car, the patient began to experience dyspnea. A blood gas analysis was performed upon admission, and the patient's PaCO2 and PaO2 levels were found to be low. Examination of a blood sample revealed elevated FDP, FDP-D dimer and platelet factor 4 levels. A perfusion lung scan showed multiple defects in both lungs, but no abnormal findings were detected on a ventilation scan. A pulmonary angiogram showed an interrupted blood flow in branches A9 + 10 of the left pulmonary artery. Accordingly, a pulmonary embolism was diagnosed. Squatting may have caused a partial obstruction of the venous return from the lower extremities by compression of the inguinal region and may have been a predisposing cause of the thrombosis. To our knowledge, such cases of pulmonary embolism triggered by the act of squatting are very rare.

Extremely high Langerhans cell infiltration contributes to the favourable prognosis of HPV-infected squamous cell carcinoma and adenocarcinoma of the lung

AIMS

The infiltration of Langerhans cells in adenocarcinomas and squamous cell carcinomas of the lung was examined in relation to prognostic implications and human papillomavirus (HPV) infection.

METHODS AND RESULTS

Samples from 62 adenocarcinoma and 59 squamous cell carcinoma patients in 1995-97, the prognosis of which had been followed up, were used. The Langerhans cells were demonstrated immunohistochemically using anti S100a and CD1 antibodies. Human papillomavirus (HPV) infection was examined by polymerase chain reaction (PCR) and nonisotopic in-situ hybridization (NISH) methods. Statistical analysis was carried out using the Kaplan-Meier method (Wilcoxon analysis) and multiple regression analysis. HPV infection was demonstrated in 12 cases (19.4%) of adenocarcinoma. The HPV-infected adenocarcinomas had abundant faintly eosinophilic cytoplasm, and were immunohistochemically positive for the surfactant apoprotein A. In the 59 cases of squamous cell carcinomas 19 were of the well differentiated form, and 29 and 11 were moderately and poorly differentiated cases, respectively. HPV was detected in 29 cases (49.2%) (13 well and 16 moderately differentiated cases). In all HPV-infected adenocarcinoma and squamous cell carcinoma cases, extremely large numbers of Langerhans cells (more than 100 per high-power field) were demonstrated in the tumour nests. In contrast, in the non-HPV-infected adenocarcinomas and squamous cell carcinomas, only a few (less than about 10 per high-power field) Langerhans cells were observed. The squamous cell carcinoma cases with high Langerhans cell infiltration, which were also infected with HPV, showed a significantly good prognosis (P = 0.007). The adenocarcinoma cases with high Langerhans cell infiltration tended to have a better prognosis than the cases with low Langerhans cell infiltration, but the difference was not statistically significant. The low number of highly infiltrated cases was insufficient for an adequate statistical analysis. Furthermore, there was no significant correlation between either Langerhans cell infiltration and smoking, or HPV infection and smoking, in either squamous cell carcinoma or adenocarcinoma cases.

CONCLUSIONS

It was considered that the extremely high Langerhans cell infiltration in the tumours was caused by HPV infection. The extremely large number of Langerhans cells in the tumours contributes to the favourable prognosis for HPV-infected lung cancer.

Experimental myelitis in BALB/cN and C57BL/6N mice caused by herpes simplex virus type 1 compared with herpes simplex virus type 2

Intraperitoneal and footpad inoculations of herpes simplex virus type 1 (HSV) into BALB/cN (HSV-susceptible) and C57BL/6N (HSV-resistant) mice were carried out to induce experimental myelitis. Standard laboratory strains (McIntyre, F, RK, and recently Okinawa strain R1) were inoculated in mice. As a control, the HSV 2 standard laboratory strain SAV was also inoculated. The McIntyre strain was the most virulent, while the F strain was the least. RK and R1 were both moderately virulent. Myelitis was induced in BALB/cN mice after intraperitoneal and footpad inoculations of low to high doses of the McIntyre strain, and intraperitoneal inoculation of moderate and high doses of the RK and R1 strains. Symptoms of paraplegia of the hind legs and rectal and urinary incontinence were observed, but not until 3-5 hours before death. The symptoms caused by footpad inoculation were slightly different from those following intraperitoneal inoculation; rectal incontinence, in particular, was inconspicuous in the former. In the case of footpad inoculation of RK and R1, only one mouse inoculated with R1 showed symptoms and histology of myelitis. The F strain caused no symptoms. In the case of C57BL/6N mice, high dose intraperitoneal and footpad inoculations of the McIntyre strain also caused myelitis, and the symptoms were observed about 6-7 hours before death. In only one C57BL/6N mouse intraperitoneally inoculated with a high dose of R1 did symptoms appear about 6 hours before death. The same symptoms caused by intraperitoneal and footpad inoculations of HSV 2 (SAV) were observed more clearly and for a longer period (half to one day) than those caused by HSV 1 inoculation. Spinal cord necrosis was noted with McIntyre, RK and R1 inoculations, but it was not marked with randomly located foci, when compared with that caused by SAV. Further, the foci of necrosis in C57BL/6N mice were smaller than in BALB/cN mice, even when high dose McIntyre strain was used. Nuclear pyknosis and edema of the brain in the dead mice following HSV 1 inoculation were more marked than in those killed by SAV.

Liporegulation in diet-induced obesity. The antisteatotic role of hyperleptinemia

To test the hypothesis that the physiologic liporegulatory role of hyperleptinemia is to prevent steatosis during caloric excess, we induced obesity by feeding normal Harlan Sprague-Dawley rats a 60% fat diet. Hyperleptinemia began within 24 h and increased progressively to 26 ng/ml after 10 weeks, correlating with an approximately 150-fold increase in body fat (r = 0.91, p < 0.0001). During this time, the triacylglycerol (TG) content of nonadipose tissues rose only 1-2.7-fold implying antisteatotic activity. In rodents without leptin action (fa/fa rats and ob/ob and db/db mice) receiving a 6% fat diet, nonadipose tissue TG was 4-100 times normal. In normal rats on a 60% fat diet, peroxisome proliferator-activated receptor alpha protein and liver-carnitine palmitoyltransferase-1 (l-CPT-1) mRNA increased in liver. In their pancreatic islets, fatty-acid oxidation increased 30% without detectable increase in the expression of peroxisome proliferator-activated receptor-alpha or oxidative enzymes, whereas lipogenesis from [14C]glucose was slightly below that of the 4% fat-fed rats (p < 0.05). Tissue-specific overexpression of wild-type leptin receptors in the livers of fa/fa rats, in which marked steatosis is uniformly present, reduced TG accumulation in liver but nowhere else. We conclude that a physiologic role of the hyperleptinemia of caloric excess is to protect nonadipocytes from steatosis and lipotoxicity by preventing the up-regulation of lipogenesis and increasing fatty-acid oxidation.

Slow recovery of body fat lost during adenovirus-induced hyperleptinemia

In normal rats, adenovirus-induced hyperleptinemia causes disappearance of visible body fat, downregulation of lipogenic enzymes, and upregulation of oxidative enzymes and thermogenic proteins. In addition, preadipocyte markers replace mature adipocyte markers, suggesting dedifferentiation. In weight loss induced by caloric restriction, by contrast, the lipogenic machinery is essentially intact. To determine if the radical changes induced by leptin would slow the reappearance of body fat, we compared normal lean rats made hyperleptinemic by infusing an adenovirus-leptin construct with diet-matched littermates. Initially, in plasma leptin the hyperleptinemic rats averaged approximately 50x the controls and, although it declined progressively, it was still slightly elevated at 150 days (P < 0.05). In the hyperleptinemics, body fat mass, quantified by magnetic resonance spectroscopy, remained below the pretreatment value for 60 days, while in diet-matched controls it exceeded the pretreatment value. Epididymal fat pad weight in hyperleptinemics was still 28% below paired controls at 150 days posttreatment. Histologic examination revealed adipocytes of hyperleptinemic animals to be smaller 60 days after treatment. At 60 days, adipose tissue UCP-2 gene expression in hyperleptinemics was still above controls, but expression of other lipogenic and oxidative enzymes had returned to baseline expression levels. We conclude that in normal rats recovery of body fat following adenovirus-induced hyperleptinemia is much slower than after caloric restriction, possibly because of persistent upregulation of adipocyte UCP-2.

Quantitative analysis of fushi tarazu factor 1 homolog messenger ribonucleic acids in the pituitary of salmon at different prespawning stages

Steroidogenic factor 1 (SF-1) or Ad4BP is a member of the fushi tarazu factor 1 (FTZ-F1) family and an orphan nuclear receptor that plays an important role in the hypothalamus-pituitary-gonadal axis and the adrenal cortex. Although its critical role in the differentiation of adrenals, gonads, and pituitary gonadotropes has been well demonstrated, regulatory function of SF-1 during sexual maturation is yet to be examined. To investigate the potential role of SF-1 in sexual maturation, expression of two salmon FTZ-F1 homolog genes, sFF1-I and sFF1-II, was examined in the pituitaries of chum and sockeye salmons, using specific and sensitive RNase protection assays. Only sFF1-I mRNA was found in the pituitary and other organs, such as the ovary, spleen, liver, brain, and skeletal muscle. In chum salmon during upstream migration from the bay to the hatchery, the level of sFF1-I mRNA in the male fish was increased on the midway in the river, where the levels of gonadotropin alpha- and II beta-subunit mRNAs were increased. In maturing sockeye salmon, the expression of the sFF1-I gene was elevated in the mature male fish, but the administration of GnRH analog did not further enhance the expression. These results indicate that sFF1-I gene expression in the pituitary is upregulated in maturing salmon, and this upregulation may not depend on GnRH.

Hyponatremia with increased plasma antidiuretic hormone in a case of hypothyroidism

We report a 70-year-old woman with hypothyroidism and severe hyponatremia. Her plasma antidiuretic hormone (ADH) level was inappropriately high for her low plasma osmolality. Her low serum sodium level was gradually corrected by water restriction and sodium supplementation prior to the initiation of thyroid hormone replacement. After a diagnosis of Hashimoto's thyroiditis had been made, the patient was treated with levothyroxine. Following this treatment, the patient's serum sodium level increased drastically. It is suggested that the elevated plasma ADH level played an important role in the development of hyponatremia in this case.

[A case of non-small-cell lung cancer successfully treated using combination chemotherapy with CDDP and vinorelbine]

A 67-year-old woman presented to our hospital with a chief complaint of bloody sputum. A plain chest X-ray a CT scan revealed a tumor shadow 3 cm in size in the middle lobe of the right lung, multiple nodular shadows in the bilateral lung fields and enlarged hilar and mediastinal lymph nodes. A tumor biopsy done under bronchoscopy revealed poorly differentiated adenocarcinoma of the lungs (cT2N3M1). She was given two courses of combination therapy consisting of cisplatin (80 mg/m2) and vinorelbine (20 mg/m2). The primary tumor in the middle lobe of the right lung and the lung metastases were markedly reduced in size, and a complete response was obtained. The only adverse events were grade 4 neutropenia and grade 2 nausea and vomiting.

Preventive procedures against GBS infection by means of antibody measurement

OBJECTIVE

Screening group B Streptococcus (GBS) in the vagina of pregnant women and measuring serum level of its type-specific antibody would be useful for cost-benefit of the prevention against GBS infection.

STUDY DESIGN

The subjects included a total of 1,150 pregnant women who consented to the study. Serotypes of GBS detected were classified with antiserum. Serum type-specific antibody titers were measured by a bacterial agglutination method.

RESULTS

Of a total of 1,150 pregnant women, 250 cases (21.7%) had GBS in the vagina. The turn of GBS serotype occurrence was types VI (NT6) (27. 2%), VIII (JM9) (25.2%), III (11.2%), Ia (8.8%), and Ib (8.0%). None or low type-specific antibody titer was 41.0% of Ia, 20.0% of Ib, 22. 0% of II, 15.0% of III, 65.0% of VI, and 69.0% of VIII incarriers. Noneonatal GBS infection occurred under the empirically treatment.

CONCLUSION

The measurement of serum type-specific antibody against GBS would be informative for the cost-benefit treatment of the vaginal GBS in pregnant women.

Leptin, troglitazone, and the expression of sterol regulatory element binding proteins in liver and pancreatic islets

Overaccumulation of lipids in nonadipose tissues of obese rodents may lead to lipotoxic complications such as diabetes. To assess the pathogenic role of the lipogenic transcription factor, sterol regulatory element binding protein 1 (SREBP-1), we measured its mRNA in liver and islets of obese, leptin-unresponsive fa/fa Zucker diabetic fatty rats. Hepatic SREBP-1 mRNA was 2.4 times higher than in lean +/+ controls, primarily because of increased SREBP-1c expression. mRNA of lipogenic enzymes ranged from 2.4- to 4.6-fold higher than lean controls, and triacylglycerol (TG) content was 5.4 times higher. In pancreatic islets of fa/fa rats, SREBP-1c was 3.4 times higher than in lean +/+ Zucker diabetic fatty rats. The increase of SREBP-1 in liver and islets of untreated fa/fa rats was blocked by 6 weeks of troglitazone therapy, and the diabetic phenotype was prevented. Up-regulation of SREBP-1 also occurred in livers of Sprague-Dawley rats with diet-induced obesity. Hyperleptinemia, induced in lean +/+ rats by adenovirus gene transfer, lowered hepatic SREBP-1c by 74% and the lipogenic enzymes from 35 to 59%. In conclusion, overnutrition increases and adenovirus-induced hyperleptinemia decreases SREBP-1c expression in liver and islets. SREBP-1 overexpression, which is prevented by troglitazone, may play a role in the ectopic lipogenesis and lipotoxicity complicating obesity in Zucker diabetic fatty rats.

[A case of Klebsiella pneumoniae infection causing a buccal abscess complicated with multiple lung abscesses]

A 51 year-old man fitted with a dental prosthesis was hospitalized with buccal swelling, fever and chest pain. Laboratory data showed marked inflammatory changes, and chest radiography and CT scanning revealed small nodular shadows within the lung. A diagnosis of multiple lung abscesses secondary to a buccal abscess possibly caused by the prosthesis was made from needle aspiration biopsies of the lung nodules and of a buccal lesion. Klebsiella pneumoniae was isolated from these lesions and from a blood culture. The patient was successfully treated with antibiotics and by surgical drainage of the buccal abscess. It is important to note that the patient was immunodeficient at the time as a result of diabetes and alcohol intoxication.

Lipotoxic heart disease in obese rats: implications for human obesity

To determine the mechanism of the cardiac dilatation and reduced contractility of obese Zucker Diabetic Fatty rats, myocardial triacylglycerol (TG) was assayed chemically and morphologically. TG was high because of underexpression of fatty acid oxidative enzymes and their transcription factor, peroxisome proliferator-activated receptor-alpha. Levels of ceramide, a mediator of apoptosis, were 2-3 times those of controls and inducible nitric oxide synthase levels were 4 times greater than normal. Myocardial DNA laddering, an index of apoptosis, reached 20 times the normal level. Troglitazone therapy lowered myocardial TG and ceramide and completely prevented DNA laddering and loss of cardiac function. In this paper, we conclude that cardiac dysfunction in obesity is caused by lipoapoptosis and is prevented by reducing cardiac lipids.

[Evaluation of inoculum density prepared by prompt inoculation system and antimicrobial susceptibility test results by the automated MicroScan WalkAway system]

The Prompt Inoculation System adapted to the susceptibility testing by the automated microbiology system, MicroScan WalkAway (Dade MicroScan Inc., West Sacramento, CA, U.S.A.) was evaluated by determining colony forming units (cfu) per ml of the inocula and by the susceptibility test results obtained through repeated testing of the American Type Culture Collection (ATCC) reference strains described by the National Committee for Clinical Laboratory Standards (NCCLS). The colony forming units per ml of the inocula prepared by the Prompt ranged 2x10++(5) to 2x10(6)++ cfu/ml for the ATCC reference strains, the results indicating that the Prompt gave a higher inoculum density and was more reproducible when compared to the standard turbidity, McFarland adjustment. Also, most inocula prepared from the clinical isolates, comprising the strains of Enterobacteriaceae,no-entericbacilli,staphylococci,enterococci, and streptococci,contained 1x10(6) to 3x10(6) cfu/ml. Although the inocula prepared by the Prompt contained more viable bacterial cells, the outcome results for susceptibility testing by the MicroScan WalkAway were highly acceptable. Four ATCC reference strains were repeatedly tested. Of 540 MIC determinations, 489 (90. 6%) were within the acceptable MIC ranges described by the NCCLS M100-S9, whereas the inocula prepared by the photometric adjustment gave 87.4%. In conclusion, the Prompt inocula were found to give more precise susceptibility test results mostly equivalent to those obtained from inocula prepared by the conventional photometric procedures.

Troglitazone prevents mitochondrial alterations, beta cell destruction, and diabetes in obese prediabetic rats

To determine whether the antidiabetic action of troglitazone (TGZ), heretofore attributed to insulin sensitization, also involves protection of beta cells from lipoapoptosis, we treated prediabetic Zucker Diabetic Fatty rats with 200 mg/kg per day of TGZ. Their plasma-free fatty acids and triacylglycerol fell to 1.3 mM and 111 mg/dl, respectively, compared with 2.0 mM and 560 mg/dl in untreated controls. Their islet triacylglycerol content was 34% below controls. In islets of control rats, beta cells were reduced by 82% and the islet architecture was disrupted; beta-cell glucose transporter-2 was absent, 85% of their mitochondria were altered, and they were unresponsive to glucose. In treated rats, the loss of beta cells was prevented, as were the loss of beta cell glucose transporter-2, the mitochondrial alterations, and the impairment of glucose-stimulated insulin secretion. We conclude that the antidiabetic effect of TGZ in prediabetic Zucker Diabetic Fatty rats involves prevention of lipotoxicity and lipoapoptosis of beta cells, as well as improvement in insulin sensitivity.

Comparing the hypothalamic and extrahypothalamic actions of endogenous hyperleptinemia

To determine whether the depletion of body fat caused by adenovirus-induced hyperleptinemia is mediated via the hypothalamus, we used as a "bioassay" for hypothalamic leptin activity the hypothalamic expression of a leptin-regulated peptide, cocaine- and amphetamine-regulated transcript (CART). The validation of this strategy was supported by the demonstration that CART mRNA was profoundly reduced in obese rats with impaired leptin action, whether because of ablation of the ventromedial hypothalamus (VMH) or a loss-of-function mutation in the leptin receptor, as in Zucker diabetic fatty rats. We compared leptin activity in normal rats made hyperleptinemic by adenovirus-leptin treatment (43 +/- 9 ng/ml, cerebrospinal fluid leptin 100 pg/ml) with normal rats made hyperleptinemic by a 60% fat intake (19 +/- 4 ng/ml, cerebrospinal fluid leptin 69 +/- 22 pg/ml). CART was increased 5-fold in the former and 2-fold in the latter, yet in adenovirus-induced hyperleptinemia, body fat had disappeared, whereas in high-fat-fed rats, body fat was abundant. Treatment of the high-fat-fed rats with adenovirus-leptin further increased their hyperleptinemia to 56 +/- 6 ng/ml without changing CART mRNA or food intake, indicating that leptin action on hypothalamus had not been increased. Nevertheless, their body fat declined 36%, suggesting that an extrahypothalamic mechanism was responsible. We conclude that in diet-induced obesity body-fat depletion by leptin requires supraphysiologic plasma concentrations that exceed the leptin-transport capacity across the blood-brain barrier.

Hyperleptinemia depletes fat from denervated fat tissue

Adenovirus-mediated transfer of the leptin gene causes severe hyperleptinemia with rapid disappearance of visible body fat. To determine if this dramatic lipopenic action is mediated by neurotransmitted signals from the central nervous system, we transplanted the right epididymal fat pad of normal rats to the anterior abdominal wall. Four weeks later, rats were infused with either adenovirus-leptin cDNA (AdCMV-leptin) or adenovirus-beta-galactosidase (AdCMV-beta-gal). Eight days later, plasma leptin averaged 23 +/- 12 ng/ml in the former and 1.2 +/- 0.4 ng/ml in the latter. The fat transplant was intact in all 4 AdCMV-beta-gal-infused rats but had disappeared in all 4 hyperleptinemic rats. Tyrosine hydroxylase staining of the fat pad remnant was negative, excluding regrowth of sympathetic nerves. Thus, the lipopenic action of severe hyperleptinemia on adipocytes is not mediated by neurotransmitters, but must have resulted either from direct action of leptin and/or from leptin-mediated neurohormones.

Reversing adipocyte differentiation: implications for treatment of obesity

Conventional treatment of obesity reduces fat in mature adipocytes but leaves them with lipogenic enzymes capable of rapid resynthesis of fat, a likely factor in treatment failure. Adenovirus-induced hyperleptinemia in normal rats results in rapid nonketotic fat loss that persists after hyperleptinemia disappears, whereas pair-fed controls regain their weight in 2 weeks. We report here that the hyperleptinemia depletes adipocyte fat while profoundly down-regulating lipogenic enzymes and their transcription factor, peroxisome proliferator-activated receptor (PPAR)gamma in epididymal fat; enzymes of fatty acid oxidation and their transcription factor, PPARalpha, normally low in adipocytes, are up-regulated, as are uncoupling proteins 1 and 2. This transformation of adipocytes from cells that store triglycerides to fatty acid-oxidizing cells is accompanied by loss of the adipocyte markers, adipocyte fatty acid-binding protein 2, tumor necrosis factor alpha, and leptin, and by the appearance of the preadipocyte marker Pref-1. These findings suggest a strategy for the treatment of obesity by alteration of the adipocyte phenotype.

Lipoapoptosis in beta-cells of obese prediabetic fa/fa rats. Role of serine palmitoyltransferase overexpression

We reported that the lipoapoptosis of beta-cells observed in fat-laden islets of obese fa/fa Zucker Diabetic Fatty (ZDF) rats results from overproduction of ceramide, an initiator of the apoptotic cascade and is induced by long-chain fatty acids (FA). Whereas the ceramide of cytokine-induced apoptosis may be derived from sphingomyelin hydrolysis, FA-induced ceramide overproduction seems to be derived from FA. We therefore semiquantified mRNA of serine palmitoyltransferase (SPT), which catalyzes the first step in ceramide synthesis. It was 2-3-fold higher in fa/fa islets than in +/+ controls. [3H]Ceramide formation from [3H]serine was 2.2-4. 5-fold higher in fa/fa islets. Triacsin-C, which blocks palmitoyl-CoA synthesis, and L-cycloserine, which blocks SPT activity, completely blocked [3H]ceramide formation from [3H]serine. Islets of fa/fa rats are unresponsive to the lipopenic action of leptin, which normally depletes fat and prevents FA up-regulation of SPT. To determine the role of leptin unresponsiveness in the SPT overexpression, we transferred wild type OB-Rb cDNA to their islets; now leptin completely blocked the exaggerated FA-induced increase of SPT mRNA while reducing the fat content. Beta-cell lipoapoptosis was partially prevented in vivo by treating prediabetic ZDF rats with L-cycloserine for 2 weeks. Ceramide content and DNA fragmentation both declined 40-50%. We conclude that lipoapoptosis of ZDF rats is mediated by enhanced ceramide synthesis from FA and that blockade by SPT inhibitors prevents lipoapoptosis.

Enhanced de novo lipogenesis in the leptin-unresponsive pancreatic islets of prediabetic Zucker diabetic fatty rats: role in the pathogenesis of lipotoxic diabetes

Overaccumulation of fat in pancreatic islets of obese ZDF fa/fa rats is believed to cause beta-cell failure and diabetes. Previously, we demonstrated that ZDF islets have an increased capacity to esterify fatty acids imported via the circulation. Here we examine the capacity of ZDF islets to synthesize fatty acids de novo. Compared with age-matched wild-type (+/+) control islets, acetyl CoA carboxylase (ACC) mRNA was fivefold and sixfold higher and fatty acid synthetase (FAS) was fourfold and sevenfold higher in prediabetic and diabetic ZDF islets, respectively. Incorporation of label from [14C]glucose into lipids was 84% higher in ZDF islets and was not suppressed normally by fatty acids. Chronic hyperleptinemia, induced by adenoviral transfer of leptin cDNA, reduced ACC and FAS mRNA in +/+ islets by 93 and 80%, respectively, but did not decrease the high ACC and FAS expression in islets of fa/fa rats. Recombinant leptin cultured with islets isolated from +/+ rats lowered ACC and FAS expression by 66 and 47%, respectively, but had no effect in fa/fa islets. We conclude that de novo lipogenesis in islets is controlled by leptin and remains low in leptin-responsive islets. It is increased in leptin-insensitive fa/fa islets, contributing to the fat overload that leads to beta-cell dysfunction and diabetes.

Role of peroxisome proliferator-activated receptor alpha in disease of pancreatic beta cells

Expression of peroxisome proliferator-activated receptor alpha (PPARalpha) and enzymes of fatty acid (FA) oxidation is markedly reduced in the fat-laden, dysfunctional islets of obese, prediabetic Zucker diabetic fatty (fa/fa) rats with mutated leptin receptors (OB-R). Leptin, PPARalpha/retinoid x receptor ligands, and FA all up-regulate PPARalpha and enzymes of FA oxidation and stimulate [3H]-palmitate oxidation in normal islets but not in islets from fa/fa rats. Overexpression of normal OB-R in islets of fa/fa rats corrects all of the foregoing abnormalities and reverses the diabetic phenotype. PPARalpha is a OB-R-dependent factor required for normal fat homeostasis in islet cells.