Effects of glucagon on glycogenolysis and gluconeogenesis are region-specific in periportal and perivenous hepatocytes

BACKGROUND: Survival of post-myocardial infarction patients is related inversely to their levels of very-low-frequency (0.003 to 0.03 Hz) RR-interval variability. The physiological basis for such oscillations is unclear. In our study, we used blocking drugs to evaluate potential contributions of sympathetic and vagal mechanisms and the renin-angiotensin-aldosterone system to very-low-frequency RR-interval variability in 10 young healthy subjects. METHODS AND RESULTS: We recorded RR intervals and arterial pressures during three separate sessions, with the patient in supine and 40 degree upright tilt positions, during 20-minute frequency (0.25 Hz) and tidal volume-controlled breathing after intravenous injections: saline (control), atenolol (0.2 mg/kg, beta-adrenergic blockade), atropine sulfate (0.04 mg/kg, parasympathetic blockade), atenolol and atropine (complete autonomic blockade), and enalaprilat (0.02 mg/kg, ACE blockade). We integrated fast Fourier transform RR-interval spectral power at very low (0.003 to 0.03 Hz), low (0.05 to 0. 15 Hz), and respiratory (0.2 to 0.3 Hz) frequencies. Beta-adrenergic blockade had no significant effect on very-low- or low-frequency RR-interval power but increased respiratory frequency power 2-fold. ACE blockade had no significant effect on low or respiratory frequency RR-interval power but modestly (approximately 21%) increased very-low-frequency power in the supine (but not upright tilt) position (P<0.05). The most profound effects were exerted by parasympathetic blockade: Atropine, given alone or with atenolol, abolished nearly all RR-interval variability and decreased very-low-frequency variability by 92%. CONCLUSIONS: Although very-low-frequency heart period rhythms are influenced by the renin-angiotensin-aldosterone system, as low and respiratory frequency RR-interval rhythms, they depend primarily on the presence of parasympathetic outflow. Therefore the prognostic value of very-low-frequency heart period oscillations may derive from the fundamental importance of parasympathetic mechanisms in cardiovascular health.     

Characterization of a high-brilliance soft x-ray laser at 13.9 nm by use of an oscillator-amplifier configuration

We have improved a highly coherent x-ray laser at 13.9 nm using an oscillator-amplifier configuration. To improve a high-brilliance x-ray laser, we adopted traveling wave pumping for the amplifier target and rotated the amplifier target 3-4 mrad in the counterclockwise direction. Thereby, a seed x-ray laser can be amplified by medium plasma of the amplifier target with a high gain coefficient. The amplified x-ray laser has the output energy of approximately 1.3 microJ, corresponding to a large photon flux of 6.5 x 10(10) photons/pulse and a high peak brilliance of 5 x 10(26) photons/(s x mm(2) x mrad(2) x 0.01% bandwidth).     

Increased epinephrine-induced cAMP response in severely diabetic BB/W rat liver

The effect of prolonged diabetes on epinephrine-induced adenosine 3',5'-monophosphate (cAMP) response in the liver was examined in diabetes-prone BB/W rats. Basal and 1 microM epinephrine-induced cAMP release from isolated perfused liver was similar in non-diabetic and diabetic BB/W rats with preserved adipose tissue. In adipose tissue-absent diabetic rats losing intra- and retro-peritoneal adipose tissue completely, both basal and 1 microM epinephrine-induced cAMP release from the liver were enhanced (P<0.01, each case). Plasma epinephrine and norepinephrine were similar in non-diabetic, adipose tissue-preserved and -absent diabetic BB/W rats. The plasma free thyroxine level was similar in non-diabetic and adipose tissue-preserved diabetic BB/W rats, but was lower in adipose tissue-absent diabetic BB/W rats than in non-diabetic rats (P<0.01), but the frequency of lymphocytic thyroiditis was similar in these three groups, although plasma corticosterone was lower in adipose tissue-preserved diabetic BB/W rats (P<0.05) and the lowest in adipose tissue-absent diabetic BB/W rats (P<0.01). Lymphocytic infiltration was not observed in the adrenal or pituitary glands in any group. Plasma total protein and albumin were low in adipose tissue-absent diabetic BB/W rats (P<0.01, each case). In adipose tissue-absent diabetic BB/W rats, liver dysfunction and hepatomegaly, but no apparent histological change in the liver, were observed. Plasma glucose was higher (P<0.01) and plasma insulin lower (P<0.05) in adipose tissue-absent diabetic BB/W rats than in adipose tissue-preserved diabetic BB/W rats. In conclusion, epinephrine-induced cAMP response in the liver was enhanced only in adipose tissue-absent diabetic BB/W rats. Denervation supersensitivity was not likely to be responsible for the enhanced beta-adrenergic response. The observed reductions in plasma thyroxine and corticosterone seemed to result from severe diabetes. Although the severity of diabetes can vary continuously, severe diabetes with loss of adipose tissue appeared to cause significant changes in the metabolism and enhanced beta-adrenergic response in the liver.     

Purification and characterization of cis-aconitic acid decarboxylase from Aspergillus terreus TN484-M1

cis-Aconitic acid decarboxylase (CAD) was assumed to be a key enzyme in the production of itaconic acid by comparing the activity of CAD from Aspergillus terreus TN484-M1 with that of CAD from the low-itaconate yielding strain Aspergillus terreus CM85J. The constitutive CAD was purified to homogeneity from A. terreus TN484-M1 by ammonium sulfate fractionation, and column chromatography on DEAE-toyopearl, Butyl-toyopearl, and Sephacryl S200HR, and then characterized. A molecular mass of 55 kDa for the native enzyme was determined by SDS-PAGE. The enzymic activity was optimal at a pH of 6.2 and temperature of 45 degrees C. The K(m) value for cis-aconitic acid was determined as 2.45 mM (pH 6.2, 37 degrees C). The enzyme was completely inactivated by Hg+, Cu2+, Zn2+, p-chloromercuribenzoate, and 5,5'-dithio-bis(2-nitrobenzoate).     

Improvement of DCT-based compression algorithms using Poisson's equation.

We propose two new image compression-decompression methods that reproduce images with better visual fidelity, less blocking artifacts, and better PSNR, particularly in low bit rates, than those processed by the JPEG Baseline method at the same bit rates. The additional computational cost is small, i.e., linearly proportional to the number of pixels in an input image. The first method, the "full mode" polyharmonic local cosine transform (PHLCT), modifies the encoder and decoder parts of the JPEG Baseline method. The goal of the full mode PHLCT is to reduce the code size in the encoding part and reduce the blocking artifacts in the decoder part. The second one, the "partial mode" PHLCT (or PPHLCT for short), modifies only the decoder part, and consequently, accepts the JPEG files, yet decompresses them with higher quality with less blocking artifacts. The key idea behind these algorithms is a decomposition of each image block into a polyharmonic component and a residual. The polyharmonic component in this paper is an approximate solution to Poisson's equation with the Neumann boundary condition, which means that it is a smooth predictor of the original image block only using the image gradient information across the block boundary. Thus, the residual--obtained by removing the polyharmonic component from the original image block--has approximately zero gradient across the block boundary, which gives rise to the fast-decaying DCT coefficients, which, in turn, lead to more efficient compression-decompression algorithms for the same bit rates. We show that the polyharmonic component of each block can be estimated solely by the first column and row of the DCT coefficient matrix of that block and those of its adjacent blocks and can predict an original image data better than some of the other AC prediction methods previously proposed. Our numerical experiments objectively and subjectively demonstrate the superiority of PHLCT over the JPEG Baseline method and the improvement of the JPEG-compressed images when decompressed by PPHLCT.     

Impaired vagus nerve-mediated control of insulin secretion in Wistar fatty rats

It has been reported that hyperglycemia in the portal venous blood suppresses afferent activity of the hepatic branch of the vagus nerve, which in turn accelerates efferent activity of the pancreatic branch of the vagus nerve to stimulate insulin secretion. The present study examined this neural control mechanism in genetically obese diabetic male Wistar fatty (fa/fa) rats. Adult (aged 12 to 14 weeks) Wistar fatty rats were obese, hyperinsulinemic, and hyperglycemic. Young (aged 5 to 6 weeks) Wistar fatty rats were slightly obese and hyperinsulinemic, but were euglycemic compared with the lean littermates. In both adult and young lean littermates, the plasma insulin response after an intragastric glucose load (1 g/kg) was diminished by intracerebroventricular (i.c.v.) atropine methylbromide (methylatropine 10 nmol) pretreatment, and a transient increase in plasma insulin was observed after selective hepatic vagotomy, as reported in normal rats. In contrast, in both adult and young Wistar fatty rats, the plasma insulin response after an intragastric glucose load was not diminished by i.c.v. methylatropine pretreatment, and plasma insulin decreased slightly after selective hepatic vagotomy. Further, afferent discharges of the hepatic vagal branch decreased and efferent discharges of the celiac/pancreatic vagal branch increased when 10 mg glucose was infused into the portal vein in the 9-week-old lean littermates, as reported in normal rats. In 7-week-old Wistar fatty rats, afferent discharges of the hepatic vagal branch decreased but efferent discharges of the celiac/pancreatic vagal branch did not increase after intraportal glucose infusion. It is concluded that the vagus nerve-mediated regulation of insulin secretion is impaired from an early stage of life in Wistar fatty rats. Efferent discharges of the vagus nerve to the pancreas seem not to be suppressed by afferent discharges from the hepatic vagus branch, which may lead to insufficient insulin secretion in response to nutrient ingestion followed by a delayed peak. These abnormalities may thus lead to the insulin resistance and fasting hyperinsulinemia that characterize the Wistar fatty rat model.     

Identification and analysis of specific chromosomal region adjacent to exogenous Dhfr-amplified region in Chinese hamster ovary cell genome

Chinese hamster ovary (CHO) cells are widely used for the stable production of recombinant proteins. Gene amplification techniques are frequently used to improve of protein production, and the dihydrofolate reductase (DHFR) gene amplification system is most widely used in the CHO cell line. We previously constructed a CHO genomic bacterial artificial chromosome (BAC) library from a mouse Dhfr-amplified CHO DR1000L-4N cell line and one BAC clone (Cg0031N14) containing the CHO genomic DNA sequence adjacent to Dhfr was selected. To identify the specific chromosomal region adjacent to the exogenous Dhfr-amplified region in the CHO cell genome, we performed further screening of BAC clones to obtain other Dhfr-amplified regions in the CHO genome. From the screening by high-density replica filter hybridization using a digoxigenin-labeled pSV2-dhfr/hGM-CSF probe, we obtained 8 new BAC clones containing a Dhfr-amplified region. To define the structures of the 8 BAC clones, Southern blot analysis, BAC end sequencing and fluorescence in situ hybridization (FISH) were performed. These results revealed that all the selected BAC clones contained a large palindrome structure with a small inverted repeat in the junction region. This suggests that the obtained amplicon structure in the Dhfr-amplified region in the CHO genome plays an important role in exogenous gene amplification.     

Fine structure of the human ceruloplasmin gene

We characterized the genomic region corresponding to the human ceruloplasmin cDNA previously reported. Using PCR-direct sequencing methods, we determined precise intron/exon boundaries and intron-exon composition of the gene in the region. The gene region spanned about 50 kb and was composed of 19 exons and 18 introns. The lengths of exons and introns range from 107 to over 267 bp and from 0.44 to 10.0 kb, respectively. The translation initiation codon and the termination codon were located in exons 1 and 19, respectively. The nucleotide sequences of the introns were also determined in the region around the intron/exon boundaries for 24-220 bp. All the sequences around the intron/exon boundaries were consistent with the 5' and 3' consensus sequences for splice junctions of transcribed genes. Putative lariat sequences were identified between -17 and -42 nucleotides from the 3' splice junction for all 18 introns.