[Myogenic hyperuricemia]

Myogenic hyperuricemia is caused by over-production of uric acid, which based on the excessive degradation of purine derivatives in exercising muscle. This phenomenon is frequently observed in the patients of muscle glycogen storage disease (GSD) types III, V and VII. In these patients, impairment of muscle ATP production leads to over-production of AMP, followed by excessive release of inosine and hypoxanthine from the muscle. The molecular lesions of muscle GSDs have been well analyzed. Recent repertoire of these mutations were referred in respect of myogenic hyperuricemia.

Plasma leptin levels and body fat distribution

The relation between body fat distribution and plasma leptin levels in the human was investigated in 51 obese and 41 non-obese subjects. Plasma levels of leptin showed a positive correlation with body mass index and subcutaneous fat area at the umbilicus level. However, a significant correlation between its plasma levels and visceral fat area was found in neither non-obese nor obese subjects. These results suggest that plasma leptin levels might be attributed mainly to the extent of subcutaneous adiposity in human obesity.

Expression of heparin-binding epidermal growth factor-like growth factor in neointimal cells induced by balloon injury in rat carotid arteries

Balloon catheter injury of rat carotid arteries induces migration and proliferation of smooth muscle cells (SMCs), with subsequent neointimal formation. Several growth factors, such as platelet-derived growth factor and basic fibroblast growth factor, have been shown to be involved in this process, but the mechanisms that modulate the growth and/or migratory properties of SMCs remain unclear. In this study, we investigated whether heparin-binding epidermal growth factor-like growth factor (HB-EGF), which is known to be a potent SMC stimulator from in vitro study, is associated with the proliferative response of SMCs to arterial injury. Northern blot analysis showed that the transcript levels of HB-EGF increased rapidly approximately 12-fold within 2 hours after injury and declined by 2 days but remained 3-fold at 14 days. In situ hybridization analysis demonstrated that the transcript of HB-EGF remained strongly expressed in the neointima, especially near the luminal surface, at 14 days after injury. Immunohistochemical staining showed that HB-EGF protein was positive in the endothelium and only faintly visible in medial SMCs in uninjured vessels. In contrast, 2 days after injury, positive HB-EGF immunostaining was detected in the medial SMCs along the luminal surface. At 7 days, the neointimal SMCs exhibited strong immunostaining for HB-EGF, and at 14 days, they exhibited a gradient of HB-EGF expression with strong immunoreactivity in the most luminal cells. SMCs labeled with 5-bromo-2'-deoxyuridine in their nuclei showed strong immunostaining for HB-EGF protein. Furthermore, the epidermal growth factor receptor to which HB-EGF can bind was also immunostained positively in neointimal SMCs. These data suggest that HB-EGF may play an important role of the proliferation and migration of SMCs in the process of neointimal accumulation induced by arterial injury, probably in an autocrine, paracrine, and/or juxtacrine manner.

Genetic analysis of a Japanese cerebrotendinous xanthomatosis family: identification of a novel mutation in the adrenodoxin binding region of the CYP 27 gene

Cerebrotendinous xanthomatosis (CTX), an autosomal recessive lipid-storage hereditary disorder, is caused by mutations in the sterol 27-hydroxylase gene (CYP 27). A 24-year-old female Japanese CTX patient and her parents were studied for a CYP 27 mutation. Multiple xanthomas were the main complaint of the patient and plasma cholestanol level was markedly elevated. Sterol analysis of a xanthoma biopsy confirmed cholesterol and cholestanol deposition, and the cholestanol accounted for 8.1% of the total sterols. Sterol 27-hydroxylase activity in fibroblasts derived from the patient was undetectable, while the activities in fibroblasts from her mother and father were 54% and 41% of the normal level, respectively. Direct sequence analysis showed a missense mutation of A for G substitution in the CYP 27 gene at codon 362 (CGT 362Arg to CAT 362His) with a homozygous pattern in the patient, and a heterozygous pattern in the parents. The mutation, which eliminates a normal HgaI endonuclease site at position 1195 of the cDNA and is located at the adrenodoxin binding region of the gene, is most probably responsible for the decreased sterol 27-hydroxylase activity in this Japanese CTX family. The combined data strongly support that the primary enzymatic defect in CTX is the disruption of sterol 27-hydroxylase and that the disease is inherited in an autosomal recessive trait.

Functional role of cation-independent mannose 6-phosphate/insulin-like growth factor II receptor in cell adhesion and proliferation of a human myeloma cell line OPM-2

The molecular mechanism underlying the interaction between myeloma cells and stromal cells was investigated by using a human myeloma cell line (OPM-2) and human umbilical vein endothelial cells (HUVECs). Adhesion of OPM-2 cells to HUVECs was found to be significantly augmented with treatment of OPM-2 cells with an alpha-glycosidase inhibitor, castanospermine (CSP). The treatment of OPM-2 cells with CSP resulted in alteration of oligosaccharide structures of cell surface glycoproteins particularly at molecular weight of 220 kD (GP220). To determine if GP220 was involved in the adhesion of OPM-2 cells to HUVECs, cell surface glycoproteins of HUVECs were labeled by biotin and were incubated with the PVDF membrane to which cell surface glycoproteins of OPM-2 cells were blotted. The biotinylated glycoproteins at the plasma membrane of HUVECs specifically bound to GP220 of OPM-2 cells. Purification and partial amino acid sequencing of GP220 revealed that GP220 had a structure homologous to cation-independent mannose 6-phosphate/insulin-like growth factor-II (CIM6P/IGF-II) receptor. Furthermore, an antibody against CIM6P/IGF-II receptor was reactive with GP220, indicating that GP220 was a CIM6P/IGF-II receptor. The adhesion of OPM-2 cells to HUVECs was inhibited by mannose 6-phosphate. Moreover, M6P was found to suppress the adhesion of human myeloma cell lines, OPM-2 and RPMI 8226, to bone marrow stromal cells that was established from the patients with multiple myeloma. In addition, proliferation of OPM-2 was stimulated in response to IGF-II. These results suggest that CIM6P/IGF-II receptor may be functional in terms of supporting cell adhesion and proliferation of myeloma cells.

The biologic properties of recombinant human thrombopoietin in the proliferation and megakaryocytic differentiation of acute myeloblastic leukemia cells

Thrombopoietin (TPO) is implicated as a primary regulator of megakaryopoiesis and thrombopoiesis. However, the biologic effects of TPO on human acute myeloblastic leukemia (AML) cells are largely unknown. To determine if recombinant human (rh) TPO has proliferation-supporting and differentiation-inducing activities in AML cells, 15 cases of AML cells that were exclusively composed of undifferentiated leukemia cells and showed growth response to rhTPO in a short-term culture (72 hours) were subjected to long-term suspension culture with or without rhTPO. Of 15 cases, rhTPO supported proliferation of AML cells for 2 to 4 weeks in 4 cases whose French-American-British subtypes were M0, M2, M4, and M7, respectively. In addition to the proliferation-supporting activity, rhTPO was found to induce AML cells to progress to some degree of megakaryocytic differentiation at both morphologic and surface-phenotypic level in 2 AML cases with M0 and M7 subtypes. The treatment of AML cells with rhTPO resulted in rapid tyrosine phosphorylation of the TPO-receptor, c-mpl, and STAT3 in all of cases tested. By contrast, the expression of erythroid/megakaryocyte-specific transcription factors (GATA-1, GATA-2, and NF-E2) was markedly induced or enhanced in only 2 AML cases that showed megakaryocytic differentiation in response to rhTPO. These results suggested that, at least in a fraction of AML cases, TPO could not only support the proliferation of AML cells irrespective of AML subtypes, but could also induce megakaryocytic differentiation, possibly through activation of GATA-1, GATA-2, and NF-E2.

A novel sulfonylurea receptor forms with BIR (Kir6.2) a smooth muscle type ATP-sensitive K+ channel

We have isolated a cDNA encoding a novel isoform of the sulfonylurea receptor from a mouse heart cDNA library. Coexpression of this isoform and BIR (Kir6.2) in a mammalian cell line elicited ATP-sensitive K+ (KATP) channel currents. The channel was effectively activated by both diazoxide and pinacidil, which is the feature of smooth muscle KATP channels. Sequence analysis indicated that this clone is a variant of cardiac type sulfonylurea receptor (SUR2). The 42 amino acid residues located in the carboxyl-terminal end of this novel sulfonylurea receptor is, however, divergent from that of SUR2 but highly homologous to that of the pancreatic one (SUR1). Therefore, this short part of the carboxyl terminus may be important for diazoxide activation of KATP channels. The reverse transcription-polymerase chain reaction analysis showed that mRNA of this clone was ubiquitously expressed in diverse tissues, including brain, heart, liver, urinary bladder, and skeletal muscle. These results suggest that this novel isoform of sulfonylurea receptor is a subunit reconstituting the smooth muscle KATP channel.

Induction of macrophage colony-stimulating factor receptor (c-fms) expression in vascular medial smooth muscle cells treated with heparin binding epidermal growth factor-like growth factor

Vascular smooth muscle cells migrate, proliferate, and transform to foam cells during the atherosclerotic process. We have reported that smooth muscle cells derived from the intima of atherosclerotic lesions express the proto-oncogene c-fms and a scavenger receptor, which are not normally expressed in normal medial smooth muscle cells. In the present study, we demonstrated that heparin binding epidermal growth factor-like growth factor (HB-EGF) induced the expression of c-fms and the scavenger receptor in normal human medial smooth muscle cells to the level observed in the intima. The expression of c-fms was partially inhibited by a protein kinase C inhibitor, suggesting that HB-EGF induces c-fms via pathways that are both dependent on and independent of protein kinase C. By contrast, most of the scavenger receptor induction by HB-EGF was suppressed by protein kinase C inhibitors. These results indicate that two characteristic genes of monocyte-derived macrophages were induced by HB-EGF via different mechanisms. The alteration of gene expression in response to HB-EGF may play an important role in the phenotypic change of smooth muscle cells to macrophage-like foam cells during the atherosclerotic process.

Affinity modulation of the platelet integrin alpha IIb beta 3 by alpha-chymotrypsin: a possible role for Na+/Ca2+ exchanger

In the present study, we have investigated the mechanism of affinity modulation of alpha IIb beta 3 by chymotrypsin. We first confirmed that alpha-chymotrypsin could activate alpha IIb beta 3 (approximately 7,000 molecules per platelet) without major intracellular signaling. However, we unexpectedly found that high concentrations of amiloride dose-dependently inhibited 125I-fibrinogen binding to the chymotrypsin-treated platelets, as well as the platelet aggregation (IC50 [50% inhibitory concentration] for fibrinogen binding, 530 mumol/L). In contrast, amiloride did not inhibit alpha IIb beta 3 activation induced by anti-alpha IIb beta 3 monoclonal antibody PT25-2 or AP5. To identify the pathway involved, the effects of alteration of Na+ gradient in platelets were examined. Lowering Na+ gradient by replacing extracellular Na+ with tetramethylammonium (TMA) increased the number of activated alpha IIb beta 3 by twofold, as assessed by fibrinogen-binding assay. The incubation of platelets with ouabain, a Na+/K(+)-adenosine triphosphatase (ATPase) inhibitor, further augmented alpha IIb beta 3 activation. These data suggested that a likely candidate for the pathway was Na+/Ca2+ exchanger. At 140 mmol/L [Na+]o, 45Ca2+ influx to the chymotrypsin-treated platelets was twofold greater than that to non-treated platelets. Replacement of Na+ with TMA further increased the Ca2+ influx, and the increase was inhibited by amiloride dose-dependently. 3',4'-Dichlorobenzamil (DCB) and bepridil, relatively specific inhibitors of Na+/Ca2+ exchanger, also inhibited the chymotrypsin-induced alpha IIb beta 3 activation, and the IC50 values of these inhibitors for fibrinogen binding were 25 mumol/L and 52 mumol/L, respectively. Moreover, platelet aggregation induced by various physiologic agonists was inhibited by DCB or bepridil, while platelet agglutination by ristocetin was not. Our data newly suggest that Na+/Ca2+ exchanger operating in reverse mode may be directly involved in inside-out signaling that activates alpha IIb beta 3.

Visceral fat accumulation and vascular complications associated with VMH lesioning of spontaneously non-insulin-dependent diabetic GK rat

OBJECTIVE

We have reported that ventromedial hypothalamic (VMH) lesions induced marked hyperglycemia and a distinct reduction in pancreatic insulin content during short-term observation in male Goto-Kakizaki (GK) rats, an animal model for non-insulin-dependent diabetes mellitus (NIDDM) (Metabolism 43: 32-37, 1994). We investigated the long-term effect of VMH lesions on glucose metabolism, pancreatic insulin content, abdominal fat distribution and vascular complications in male GK rats.

DESIGN

Metabolic and histological examinations in male GK rats during 16 weeks after making VMH lesions were compared to those in sham operated GK or Wistar rats.

SUBJECTS

Eleven 9-week-old male GK rats and 4 male Wistar rats. VMH-lesions were made in 6 GK rats and sham operation were performed on 5 GK rats and 4 Wistar rats as controls.

MEASUREMENTS

Food intake, body weight, and plasma glucose, insulin and lipid levels at 2 weeks interval after operation. Urinary protein and albumin levels at 15 weeks after operation. Measurement of pancreatic insulin content, mesenteric fat and abdominal subcutaneous fat weights, and histological examinations of kidney and aorta were performed after 16 weeks.

RESULTS

Although food intake increased in VMH-lesioned GK (GK-VMH) rats compared with that in sham-operated GK (GK-sham) rats, the body weight of GK-VMH rats was significantly less than that of GK-sham rats. Plasma glucose was markedly elevated in GK-VMH rats from 2 through 16 weeks after operation, while it was only mildly increased in GK-sham rats. Plasma insulin levels were higher in GK-VMH rats one week after operation and thereafter tended to be lower compared to those in GK-sham rats. Plasma triglyceride levels were significantly increased in GK-VMH rats. The insulin content of pancreas at 16 weeks after operation was markedly decreased in GK-VMH rats. VMH lesions caused a significant 1.2-fold increase in mesenteric fat weight and a 1.3-fold higher ratio of mesenteric fat weight to subcutaneous fat weight in GK rats compared with sham-operated rats at 16 weeks after operation. The urinary excretions of protein and albumin in GK-VMH rats were greater than those in GK-sham rats. Histological examinations of the kidneys in GK-VMH rats revealed that the glomerular basement membranes were thicker than those of GK-sham rats. The descending aorta in GK-VMH rats also showed morphologic changes in the intima characteristic of an early stage of atherosclerosis.

CONCLUSION

Male GK-VMH rats may be a useful animal model for non-obese NIDDM with visceral fat accumulation, which develops typical diabetic complications, including both microangiopathy and macroangiopathy.

[Obesity and insulin resistance syndrome]

Obesity is commonly associated with insulin resistance. The etiology of insulin resistance syndrome such as syndrome X or deadly quartet is not clear. We have proposed visceral fat syndrome, in which fat accumulation is predominant in the intra-abdominal cavity, frequently accompanied by disorders of glucose and lipid metabolism, and also hypertension. Excess free fatty acid of the portal circulation may cause the enhancement of lipid synthesis and gluconeogenesis as well as insulin resistance, resulting in hyperlipidemia, glucose intolerance and hypertension and finally atherosclerosis. Enhanced production of PAI-1 by increased visceral fat may be partly responsible for the development of cardiovascular disease in patient with visceral fat assmulation.

Exon 10 skipping caused by intron 10 splice donor site mutation in cholesteryl ester transfer protein gene results in abnormal downstream splice site selection

Cholesteryl ester transfer protein (CETP) deficiency is the most common cause of hyperalphalipoproteinemia in Japan. However, the genetic basis of this disorder has not been fully characterized. We have studied a 49-year-old Japanese male presenting with total cholesterol, HDL-cholesterol, and apolipoprotein A-I levels of 300, 236, and 233 mg/dl, respectively, and total absence of CETP activity and mass in plasma. Sequence analysis of the patient's CETP gene revealed that the splice donor consensus GT was substituted by GG in intron 10 (intron 10 splice defect) and by AT in intron 14 (intron 14 splice defect). Restriction digestion of PCR-amplified DNA using NdeI and MaeIII established that the patient was a compound heterozygote for both gene defects. Sequencing of cDNA amplified by RT-PCR from the patient's monocyte-derived macrophage RNA demonstrated abnormal splicing with deletion of exon 10 as well as alternative splicing at a native AG site located 31 nucleotides 5' of the normal splice acceptor in intron 13. Thus, the intron 10 splice defect results in exon 10 skipping and the insertion of a 31 bp fragment between exon 13 and exon 14, which contains an in frame stop codon. The presence of abnormally spliced mRNA was further confirmed by amplification of patient cDNA using CETP specific primers. Abnormal splicing of exon 14 as a result of the intron 14 splice defect was not detected, indicating potential unstable CETP mRNA derived from that mutation. These findings demonstrate that a novel splice site mutation in intron 10 of the CETP gene results in the skipping of exon 10, as well as disruption of downstream splicing at intron 13 identifying a novel mechanism leading to CETP deficiency.

Phospholipase A2 stimulation of rat intestinal epithelial cell (IEC-6) migration

The effect of phospholipase A2 (PLA2) on intestinal epithelial cell migration was investigated using an in vitro wounding model of confluent monolayers of IEC-6. PLA2 (0.001-2 U/ml) enhanced IEC-6 cell migration in a dose dependent manner. Addition of 4-bromophenacyl bromide (BPB) (a PLA2 inhibitor) to PLA2 completely blocked the migration-promoting effect. However, addition of piroxicam (a cyclooxygenase inhibitor) or nordihydroguaiaretic acid (a lipoxygenase inhibitor) had no influence on the effect. Lysophosphatidylcholine (lysoPC) (0.01-5,000 ng/ml), one of the products of phosphatidylcholine by PLA2, dose-dependently enhanced IEC-6 cell migration as well. A combination of PsLA2 (1 U/ml) and lysoPC (1,000 ng/ml) had no additive effect or migration. Moreover, the migration-promoting effect of PLA2 that was blocked by BPB was recovered by lysoPC. After pretreatment of IEC-6 cells with replication-inhibiting doses of mitomycin C, the enhanced migration induced by PLA2 or lysoPC was still observed. These observations suggest that PLA2 may, independently of proliferation, enhance intestinal epithelial cell migration mainly via lysoPC.

Effects of muscle relaxation therapy using specially designed plates in patients with pulmonary emphysema

It has been suggested that respiratory muscle dysfunction plays a major role in the development of acute ventilatory failure in patients with chronic obstructive pulmonary disease (COPD). In this study, we devised a respiratory muscle relaxation maneuver using wedge-shaped wooden plates, with which pressure was exerted on the intercostal and accessory respiratory muscles by hand, or by tapping with a wooden hammer, for 15-20 minutes twice a day. The muscle relaxation maneuver was performed in 5 moderate to severe pulmonary emphysema patients for 4 weeks and in 7 emphysema patients for 6 weeks, and the effects on pulmonary function were examined. After the therapy, inspiratory capacity (IC) and vital capacity (VC) in both the 4 weeks-and 6 weeks-treated groups, and the forced expiratory volume in 1 second (FEV 1.0) in the 6 weeks-treated group were significantly increased, and CO2 retention had also improved. Daily peak expiratory flow (PEF) showed significant increases from 2 weeks after the initiation of the therapy. These results suggest that the respiratory muscle relaxation maneuver is effective for improving the pulmonary function of pulmonary emphysema patients.

Serum pepsinogen I levels and acid secretion in Helicobacter pylori associated enlarged fold gastritis

It has been shown that serum pepsinogen I levels are correlated with maximal acid outputs and can be used as an indicator for parietal cell mass. In this study, the effect of Helicobacter pylori infection on the relationship between serum pepsinogen I levels and maximal acid outputs was investigated in 27 patients with Helicobacter pylori associated enlarged fold gastritis. Before treatment, serum pepsinogen I levels and maximal acid outputs were not significantly correlated. After eradication of Helicobacter pylori, a significant positive correlation was found between serum pepsinogen I levels and maximal acid outputs with a significant increase in pepsinogen I levels and a significant increase in maximal acid outputs. These results indicate that Helicobacter pylori infection distorts the relationship between serum pepsinogen I levels and maximal acid outputs by elevating the former and lowering the latter, and that serum pepsinogen I level after eradication of Helicobacter pylori may reflect parietal cell mass in patients with Helicobacter pylori associated enlarged fold gastritis.

Establishment of anaplastic thyroid carcinoma cell lines useful for analysis of chemosensitivity and carcinogenesis

Anaplastic thyroid carcinoma (ATC) is usually associated with a poor prognosis, with most patients dying within a few months. The mechanism of its carcinogenesis is unclear, and its rapid growth and spread often prevent effective surgical therapy. Thus, chemotherapy is necessary. However, ATC is often resistant to anticancer drugs. Therefore, prediction of chemosensitivity is important in selecting appropriate treatment. In this study, after the establishment of three cell lines (K119, KOA2, and IAA) from patients with ATC, we analyzed them for abnormalities in certain oncogenes (myc, ras, ret, and c-erbB2) and the p53 tumor suppressor gene. Only one of three cell lines (KOA2) had a N-ras mutation [codon 61 CAA(Gln)-->CGA(Arg)] and a p53 gene mutation [exon 6 codon 192 Caa(Gln)-->TAG(stop)]. We also investigated their in vitro drug sensitivity and compared it with clinical chemosensitivity, retrospectively. In vitro drug sensitivity was determined using an adhesive tumor cell culture system. Only the K119 cells were sensitive to adriamycin and cisplatin in vitro. The other two were resistant to them in vitro. These results paralleled the clinical responses. We also evaluated the in vitro drug sensitivity of a poorly differentiated thyroid carcinoma cell line (SMP) and papillary thyroid carcinoma cell lines (NPA). None of the five cell lines expressed the multidrug resistance gene (mdr-1). In conclusion, we established ATC cell lines that are suitable models for characterizing the nature of multidrug resistance and carcinogenesis.

A novel nonsense mutation (G181X) in the human cholesteryl ester transfer protein gene in Japanese hyperalphalipoproteinemic subjects

Cholesteryl ester transfer protein (CETP) plays an important role in regulating the concentration and composition of high density lipoprotein (HDL) and low density lipoprotein (LDL). Although several genetic abnormalities causing CETP deficiency have been identified in the Japanese subjects with a marked hyperalphalipoproteinemia (HALP), there are many CETP-deficient subjects for whom the genetic abnormalities have not been clarified. In the present study, we analyzed the molecular basis of an HALP subject without CETP activity and mass, and found a novel mutation in the CETP gene. This novel mutation (G181X) was a G-to-T substitution at codon 181 of exon 6 which replaced a codon for glycine (GGA) with a premature stop codon (TGA). The G181X mutation created a new cutting site by restriction enzyme MaeIII. To estimate the frequency of G181X, we investigated unrelated 294 HALP (HDL-cholesterol > or = 2.59 mmol/L = 100 mg/dl) subjects by restriction fragment length polymorphism (RFLP) analysis with Mae III. One (0.34%) HALP subject was homozygous and four (1.36%) were heterozygous for this mutation. The allelic frequency of a G-to-T substitution at codon 181 of exon 6 was 0.0102 in HALP subjects. From the lipid analysis of the proband and the homozygote, it was clarified that the G181X mutation had dominant effects on HDL and LDL metabolism, similar to a G-to-A substitution at the 5' splice donor site of the intron 14 (1451 + 1G-->A). In conclusion, the G181X mutation is one of causes of HALP in the Japanese HALP subjects, having dominant effects on lipid metabolism.

Oxidative stress increases gene expression of heparin-binding EGF-like growth factor and amphiregulin in cultured rat gastric epithelial cells

We investigated the effects of oxidative stress on mRNA levels of heparin-binding epidermal growth factor-like growth factor (HB-EGF) and amphiregulin (AR) in rat gastric epithelial RGM1 cells. In response to stimulation with hydrogen peroxide (100-400 microM), gene expression of HB-EGF and AR increased in a dose-dependent manner, peaked at 3 h, and returned to the base line at 7 h. Hydrogen peroxide-induced HB-EGF and AR gene expression was blocked by pretreatment with an antioxidant N-acetyl-cysteine. In addition, it was significantly inhibited by pretreatment with EGF receptor-specific tyrphostin AG1478, but not by depletion of protein kinase C. These data indicate that oxidative stress upregulates expression of EGF-related polypeptides and the possible involvement of EGF receptor in this process.

High glucose and hyperosmolarity increase heparin-binding epidermal growth factor-like growth factor (HB-EGF) production in cultured human aortic endothelial cells

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been shown to be a potent smooth muscle cell (SMC) mitogen and chemoattractant, and might be a candidate factor for the progression of atherosclerosis. We have investigated the effects of high glucose and hyperosmolarity on HB-EGF production in cultured human aortic endothelial cells. Following the culture of the cells for 2 days with high concentrations of glucose or in the hyperosmolar conditions, we measured the content of HB-EGF and the rate of production in the cells using a semi-quantitative immunofluorescent technique and a metabolic radiolabelling method. With high glucose (16.6 mmol) and hyperosmolar conditions (glucose 5.5 mmol + mannitol 11.1 mmol or glucose 5.5 mmol + raffinose 11.1 mmol), the content of HB-EGF was significantly increased and the metabolic rate was also significantly increased (more than a twofold increase, compared to that of 5.5 mmol glucose). In conclusion, conditions of high glucose or hyperosmolarity increase HB-EGF production in human aortic endothelial cells. These results suggest that diabetic macroangiopathy might be attributed at least in part to HB-EGF-related vascular changes which may be induced by glucose.

Effects of interleukin-1 beta on scanning electron microscopic appearance and thyroid peroxidase content of human thyrocytes in monolayer culture

Interleukin (IL-1), an inflammatory cytokine that is detected in the thyroid tissues of patients with autoimmune thyroiditis, is believed to be involved in the disease process. To clarify the role of IL-1 in the development of autoimmune thyroiditis, we investigated the effects of interleukin-1 beta (IL-1 beta) on the morphology of human thyrocytes in monolayer culture as well as the effect on thyroid peroxidase (TPO) content of these cells. Human normal thyrocytes were cultured with IL-1 beta for 4 days in the presence and absence of TSH. In morphologic studies, cultured cells were fixed for examination by scanning electron microscopy and for immunofluorescent staining of acting filaments. IL-1 produced striking morphologic changes in the cultured thyrocytes, including the cytoplasmic retraction and dissociation and/or depolymerization of actin filaments. These changes were unrelated to TSH stimulation. For detection of TPO, cultured cells were stained by an immunofluorescent technique and analyzed by fluorescence photometry. IL-1 reduced the TPO content and inhibited the TSH-induced increase in TPO in a concentration-dependent manner. These morphological changes and the reduction in TPO content of cultured thyrocytes suggest that IL-1 modulates the pathophysiology of autoimmune thyroiditis.

Dominant TCR alpha-chain clonotypes and interferon-gamma are expressed in the pancreas of patients with recent-onset insulin-dependent diabetes mellitus

In order to clarify the nature of T lymphocytes infiltrating the pancreatic islets of patients with insulin-dependent diabetes mellitus (IDDM), we analysed T cell receptor (TCR) gene transcripts expressed in pancreatic biopsy specimens of patients with recent-onset IDDM. We also investigated the expression of cytokines (interferon-gamma: IFN-gamma; tumour necrosis factor-alpha: TNF-alpha; interleukin-4: IL-4; interleukin-6: IL-6) in the same specimens. The TCR V beta repertoire was not restricted either in the pancreas or the peripheral lymphocytes of IDDM patients. In contrast, the TCR V alpha repertoire was restricted in the pancreas, but not in the peripheral blood lymphocytes, of IDDM patients. The sequence analysis of the complementarity-determining region 3 (CDR3) of the TCR alpha revealed the presence of dominant clonality in alpha chains of T cells in the patients. IFN-gamma mRNA was highly expressed in the pancreas of IDDM patients, while IL-4 mRNA was deficient. A lower level of expression of IL-6 mRNA was detected in the IDDM pancreas than in the control tissue. These results indicate that T cells bearing a distinct TCR alpha chain are selectively retained and activated within the pancreas of recent-onset IDDM.

Formation of nucleation center in single double-stranded DNA chain

The dynamic process of compaction of long double-stranded DNA, T4DNA (166 kbp), was studied by the observation for individual DNA using fluorescence microscopy. We have observed the process of folding of metastable elongated DNA into compacted form in polyethylene glycol solution. During the thermal Brownian motion, the transition from the unfolded state into the compacted state is initiated by the formation of a nucleation center in the DNA chain. This center then grows along the DNA chain until the entire individual DNA takes the compacted state. The greatest probability for the formation of a nucleation center is at the ends of the DNA chain. In addition to the ends, nucleation is observed only in the region containing the positions with relatively high GC content region along the DNA chain.