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Nine samples of gellan gum in the sodium form, ranging in weight-average molar mass from 3.47 × 10⁴ to 1.15 × 10⁵ at 40 °C, were investigated by static and dynamic light scattering and viscometry in 25 mM aqueous NaCl both at 40 and at 25 °C. The ratios of the molar mass at 25 °C (in the ordered state) to that at 40 °C (in the disordered state) were in the range of 1.99 to 2.07, supporting the scheme of the conformational transition of gellan gum between a disassociated single chain and an associated chain composed of two molecules. Focusing on the effects of polydispersity, the intrinsic viscosities, radii of gyration, and hydrodynamic radii were analyzed on the basis of unperturbed wormlike chain models. The persistence lengths were evaluated as 9.4 nm at 40 °C and 98 nm at 25 °C.

The effect of potassium concentration on glycolysis was studied in the erythrocytes of Japanese Shiba dogs with high potassium (HK) and low potassium (LK) concentrations. When intracellular Na and K concentrations were changed in intact erythrocytes, lactate formation increased with increasing K concentration in both HK and LK dogs. In the reconstituted haemolysates, lactate formation, phosphofructokinase (PFK) and pyruvate kinase (PK) activities increased with increasing K concentration in both HK and LK dogs. These results suggest that glycolysis in erythrocytes of HK and LK dogs is dependent on K concentration because PFK and PK require K for their activities. In the reticulocytes of a LK dog possessing high K and low Na concentrations, PK and PFK activities were markedly elevated from the levels in mature erythrocytes and also dependent on K concentration. As in HK dog erythrocytes, high K concentration is required for glucose metabolism in LK dog reticulocytes. It is suggested that the glycolytic system of LK dog erythrocytes retains the potential to be stimulated with high K concentration even after cell maturation.

Sexual dimorphism of somatic growth in rats appears to reflect differing actions of sex steroids. However, mechanisms of gonadal steroid effects on the somatotropic axis are incompletely understood. To evaluate whether GH is involved in the effects of long-term gonadal suppression on somatic growth in rats, a GnRH agonistic analogue (GnRHa) was administered to normal Sprague-Dawley rats (controls) and to a strain of rats with complete growth hormone deficiency (GHD; n=4-6 in each group). Subcutaneous injection of GnRHa (2 mg/kg) or saline were given within 48 h after birth and repeated every 3 weeks. GnRHa treatment significantly reduced serum gonadal steroid levels in rats of both sexes with small testes in males and impaired development of internal genitalia in females. GnRHa-treated control females became significantly heavier (P<0.01 ANOVA for repeated measures) than saline-treated rats beginning at 8 weeks. However, female GHD rats with GnRHa treatment did not differ in body weight from rats receiving saline. In male rats, GnRHa treatment did not change body weight in either control or GHD rats. Serum IGF-I concentrations did not differ between treatment groups in GHD and control rats of either sex. Hepatic GH binding was reduced significantly by GnRHa treatment in female control rats (P<0.01), but not in female GHD rats. These data suggest that sexual dimorphism in body size and its modulation by estrogens are independent of circulating IGF-I levels suggesting non-endocrine IGF-I-mediated mechanisms, and that GH-induced somatic growth is modulated by estrogens, but not androgens, in rats.

Normal dog red blood cells lack the Na-K pump, and their cation composition is low K and high Na (LK). Recently, a dog was found with red blood cells containing high K and low Na concentrations (HK) due to the existence of the Na-K pump. In the present study, cation transport and volume regulation in HK cells were compared with those of LK cells. HK cells showed not only Rb influx through a Na-K pump, but also Rb influx through a Cl-dependent K transporter. The Rb influx rate through the Na-K pump was 0.65-1.44 mmol.l cells-1.h-1 in Cl and 1.75-2.24 mmol.l cells-1.h-1 in NO3, in HK cells, but only trace activities are found in LK cells. In HK cells, the Rb influx rate through Cl-dependent K transport was 0.36-0.96 mmol.l cells-1.h-1, and it was enhanced in swollen cells but vanished in shrunken cells. In LK cells, the transport was evident only in swollen cells. The original volume of swollen HK cells was restored by water extrusion promoted by Cl-dependent transport. The Na-Ca exchange transporter, which works as a volume regulator in LK cells, functioned in HK cells only when they were loaded with Na. Hence, the exchange transporter is latent in HK cells under physiological conditions. Moreover, the exchange transporter could restore the cell volume in swollen and Na-loaded HK cells. However, the volume in HK cells was still larger than that in LK cells, while the Na-Ca exchange transporter was working.(ABSTRACT TRUNCATED AT 250 WORDS)

Temperature dependences of the conformational properties of sodium-type gellan gum in aqueous solutions were studied by osmometry. The measurements were carried out in the range from 25 to 45 °C for aqueous solutions of three sodium chloride concentrations (Cs = 25, 50, and 75 mmol dm^-3). It was found that the Mn values obtained at 45, 40, 36, 28, and 25 °C with different Cs agreed with each other and the average Mn values above 36 °C were almost half the values obtained at 28 and 25 °C, suggesting association of two molecules. The values of A2 obtained at 45, 40, 36, 28, and 25 °C were almost the same at each Cs, while these A2 values decreased with increasing Cs. The Mn value obtained in solution with Cs = 25 mmol dm^-3 at 32 °C was slightly higher than those obtained above 36 °C but lower than those obtained below 28 °C, and in solutions with Cs = 50 and 75 mmol dm^-3, Mn values could not be determined due to abnormality of the π/c vs c plots. This suggests that a unimer should be in simultaneous equilibrium with a dimer. The data obtained at 32 °C were analyzed by employing a simple unimer/dimer equilibrium model. The equilibrium constant K increases with increasing Cs, which means that the extent of association increases and the proportion of dimer also increases with increasing Cs.

Summary Using a human dihydropteridine reductase (DHPR) cDNA, the frequency of restriction fragment length polymorphisms (RFLPs) with restriction endonucleases AvaII, MspI, NcoI and HinfI was estimated in unrelated, unaffected Japanese. The allele frequencies are different from those found in Caucasians, especially with MspI and HinfI. However, approximately 60% of Japanese are heterozygous for at least one of the RFLPs and analysis of one family with DHPR deficiency was shown to be informative. RFLP linkage analysis will be useful in the Japanese population as previously reported for Caucasians.

To assess hypothalamic-pituitary function, a corticotropin-releasing hormone (CRH) stimulation test was performed in nine children following treatment for brain tumours and in 27 growth hormone deficient (GHD) children whose pituitary adrenocorticotropin (ACTH) secretion was normal. In both groups, CRH tests were compared with ACTH and cortisol responses to insulin-induced hypoglycaemia and with ACTH response to metyrapone stimulation. In the patients with brain tumours (five craniopharyngiomas, two suprasellar germinomas, one cerebellar medulloblastoma and one cerebellar ependymoma), ACTH responses to CRH varied greatly with absent or blunted, normal, and exaggerated reactions. Cortisol and ACTH responses were not always correlated. In GHD children but not in children with brain tumours the responses to CRH, insulin tolerance test and metapyrone test were correlated. The marked variability of the CRH test was possibly caused by compounding factors such as preceding corticosteroid therapy, concomitant desmopressin therapy and spontaneous regeneration of damaged brain structures.

We have previously identified a protein factor, PEBP2 (polyomavirus enhancer-binding protein), in the nuclear extract from mouse NIH 3T3 cells which binds to the sequence motif, PEA2, located within the polyomavirus enhancer A element. Upon cellular transformation with activated oncogene c-Ha-ras, this factor frequently undergoes drastic molecular modifications into an altered form having a considerably reduced molecular size. In this study, the altered form, PEBP3, was purified to near homogeneity. The purified PEBP3 comprised two sets of families of polypeptides, alpha-1 to alpha-4 and beta-1 to beta-2, which were 30 to 35 kilodaltons and 20 to 25 kilodaltons in size, respectively. Both kinds of polypeptides possessed DNA-binding activities with exactly the same sequence specificity. Individual alpha or beta polypeptides complexed with DNA showed faster gel mobilities than did PEBP3. However, the original gel retardation pattern was restored when alpha and beta polypeptides were mixed together in any arbitrary pair. These observation along with the results of UV- and chemical-cross-linking studies led us to conclude that PEBP3 is a heterodimer of alpha and beta subunits, potentially having a divalent DNA-binding activity. Furthermore, PEBP3 was found to bind a second, hitherto-unnoticed site of the polyomavirus enhancer that is located within the B element and coincides with the sequence previously known as the simian virus 40 enhancer core homology. From comparison of this and the original binding sites, the consensus sequence for PEBP3 was defined to be PuACCPuCA. These findings provided new insights into the biological significance of PEBP3 and PEBP2.

cDNAs representing the alpha subunit of polyomavirus enhancer binding protein 2 (PEBP2; also called PEA2) were isolated. The products of the cDNAs are highly homologous to that of Drosophila segmentation gene runt (run) for an N-proximal 128-amino acid region showing 66% identity. The run homology region encompasses the domain capable of binding to a specific nucleotide sequence motif and of dimerizing with the companion beta subunit. The human AML1 gene related to t(8;21) acute myeloid leukemia also had a run homology region. Together with the beta subunit, which increases the affinity of the alpha subunit to DNA without binding to DNA by itself, PEBP2 represents a newly discovered family of transcription factor. The major species of PEBP2 alpha mRNA was expressed in T-cell lines but not in B-cell lines tested. Evidence indicated that PEBP2 functions as a transcriptional activator and is involved in regulation of T-cell-specific gene expression.

The metabolic effects of ovine placental lactogen (oPL) alone and in combination with bovine GH (bGH) were investigated in comparison with the identical dose of bGH alone in the well-fed postnatal lamb. The animals were treated by twice daily intramuscular injection for 5 days with oPL (n=7), bGH (n=7) or bGH+oPL (n=7) at a dose of 0·3 mg/kg per day or saline (n=9). bGH and bGH+oPL treatments, but not oPL treatment, resulted in significantly (P<0·01) higher plasma IGF-I levels than saline treatment. The rate of net protein catabolism (NPC) was significantly (P<0·05) reduced to the same extent by bGH and bGH+oPL treatment compared with saline treatment. In contrast, oPL did not affect the rate of NPC. Blood glucose and insulin:glucose ratio were significantly (P<0·05) elevated in the bGH+oPL group, whereas they were not significantly altered by either bGH or oPL treatment. These results suggest that oPL alone is not somatogenic or anticatabolic in the postnatal lamb despite the earlier evidence that oPL can bind to the oGH receptor (oGHR). However, oPL appeared to augment some of the effects of bGH when administered together, particularly with respect to carbohydrate metabolism. Potentiation of the diabetogenic effect of bGH by oPL may lead to insulin resistance during pregnancy. The lack of any obvious actions by oPL treatment alone may support the hypothesis that oGHR homo-dimerization is required for the full activation of GHR-mediated effects, since oPL binding does not initiate homo-dimerization of the oGHR.Journal of Endocrinology(1995) 145,87–95

Using a human dihydropteridine reductase (DHPR) cDNA, the frequency of restriction fragment length polymorphisms (RFLPs) with restriction endonucleases AvaII, MspI, NcoI and HinfI was estimated in unrelated, unaffected Japanese. The allele frequencies are different from those found in Caucasians, especially with MspI and HinfI. However, approximately 60% of Japanese are heterozygous for at least one of the RFLPs and analysis of one family with DHPR deficiency was shown to be informative. RFLP linkage analysis will be useful in the Japanese population as previously reported for Caucasians.

Each of the two human genes encoding the alpha and beta subunits of a heterodimeric transcription factor, PEBP2, has been found at the breakpoints of two characteristic chromosome translocations associated with acute myeloid leukemia, suggesting that they are candidate proto-oncogenes. Polyclonal antibodies against the alpha and beta subunits of PEBP2 were raised in rabbits and hamsters. Immunofluorescence labeling of NIH 3T3 cells transfected with PEBP2 alpha and -beta cDNAs revealed that the full-size alpha A1 and alpha B1 proteins, the products of two related but distinct genes, are located in the nucleus, while the beta subunit is localized to the cytoplasm. Deletion analysis demonstrated that there are two regions in alpha A1 responsible for nuclear accumulation of the protein: one mapped in the region between amino acids 221 and 513, and the other mapped in the Runt domain (amino acids 94 to 221) harboring the DNA-binding and the heterodimerizing activities. When the full-size alpha A1 and beta proteins are coexpressed in a single cell, the former is present in the nucleus and the latter still remains in the cytoplasm. However, the N- or C-terminally truncated alpha A1 proteins devoid of the region upstream or downstream of the Runt domain colocalized with the beta protein in the nucleus. In these cases, the beta protein appeared to be translocated into the nucleus passively by binding to alpha A1. The chimeric protein containing the beta protein at the N-terminal region generated as a result of the inversion of chromosome 16 colocalized with alpha A1 to the nucleus more readily than the normal beta protein. The implications of these results in relation to leukemogenesis are discussed.

The reflection of a pulse by multiple-dielectric layers is treated theoretically. The reflected wave is obtained by expanding the reflection coefficient of an elementary plane wave in a series, including the special case for which total reflection occurs. The pulsed waves reflected by two-dielectric slabs are considered in detail both analytically and numerically. The effect of a carrier frequency of a pulse-modulated carrier wave on the reflected wave form is also discussed.

The dispersion of stratum corneum (SC) into intact cells has been studied in aqueous mixed micelle solutions containing α-Terpineol (α-T) solubilized in solutions of N,N-dimethyldodecylamine oxide (C12,DMAO). The dispersion was found to be most effective when α-T is solubilized in the saturated state, and the sizes of the mixed micelles become larger with increasing concentrations of solubilized α-Terpineol (α-T) at pH 8.4.

The translocation from chromosome 8 to chromosome 21, t(8;21), associated with acute myeloid leukemia results in production of an AML1/MTG8(ETO) fusion transcript. The product of the AML1 gene contains an evolutionarily conserved 128-amino acid region referred to as the "Runt domain," which is necessary for binding to DNA at the PEBP2 site. A fragment of the AML1 protein containing mainly the Runt domain and the antisense oligonucleotide complementary to the fusion transcript strongly inhibited the growth and induced differentiation of cell lines derived from acute myeloid leukemia containing t(8;21). These results indicate that the transcriptional regulation through the PEBP2 site is critically important for growth and differentiation of t(8;21) leukemic cells and that the product of the chimeric gene is responsible for the maintenance of the leukemic phenotype.

Metabolism of the erythrocytes of high potassium and high glutathione (HK-high GSH), high potassium and low GSH (HK-low GSH) and normal low potassium and low GSH (LK-low GSH) dogs were studied with respect to the levels of enzymes associated with GSH synthesis and metabolism, and the capacity of the cells to regenerate GSH. HK-high GSH dogs were found to have significantly higher levels of hexokinase (Hx) and ?-glutamylcyclotransferase (GCT) than low GSH groups. The rate of GSH regeneration was much greater in high GSH dogs than in those of low GSH groups, and there is a positive correlation between GSH level and its, regeneration rate. Glutathione-S-transfer-ase (GST) activity was high in both HK-high GSH and HK-low GSH cells. There were no significant differences in the activities of ?-glutamyl cysteine synthetase (GCS), glutathione synthetase (GSHS) and glutathione reductase (GR) among these three groups. Our results indicate that GSH levels and Hx activity influence GSH regeneration rate, and the GSH levels also affect GST activity.

A murine transcription factor, PEBP2, is composed of two subunits, alpha and beta. There are two genes in the mouse genome, PEBP2 alpha A and PEBP2 alpha B, which encode the alpha subunit. Two types of the alpha B cDNA clones, alpha B1 and alpha B2, were isolated from mouse fibroblasts and characterized. They were found to represent 3.8- and 7.9-kb transcripts, respectively. The 3.8-kb RNA encodes the previously described alpha B protein referred to as alpha B1, while the 7.9-kb RNA encodes a 387-amino-acid protein, termed alpha B2, which is identical to alpha B1 except that it has an internal deletion of 64 amino acid residues. Both alpha B1 and alpha B2 associate with PEBP2 beta and form a heterodimer. The alpha B2/beta complex binds to the PEBP2 binding site two- to threefold more strongly than the alpha B1/beta complex does. alpha B1 stimulates transcription through the PEBP2 site about 40-fold, while alpha B2 is only about 25 to 45% as active as alpha B1. Transactivation domain is located downstream of the 128-amino-acid runt homology region, referred to as the Runt domain. Mouse chromosome mapping studies revealed that alpha A, alpha B, and beta genes are mapped to chromosomes 17, 16, and 8, respectively. The last two genes are syntenic with the human AML1 on chromosome 21q22 and PEBP2 beta/CBF beta on 16q22 detected at the breakpoints of characteristic chromosome translocations of the two different subtypes of acute myeloid leukemia. These results suggest that previously described chimeric gene products, AML1/MTG8(ETO) and AML1-EAP generated by t(8;21) and t(3;21), respectively, lack the transactivation domain of AML1.