Inhibition of BCL2A1 by STAT5 inactivation overcomes resistance to targeted therapies of FLT3-ITD/D835 mutant AML

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BCL2A1 is upregulated and exerts a pro-survival function in FLT3-ITD/D835 AML cells.

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Upregulation of BCL2A1 attenuates sensitivity to quizartinib in FLT3-ITD/D835 cells.

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Gilteritinib decreases BCL2A1 through inactivation of STAT5 in FLT3-ITD/D835 cells.

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Gilteritinib/Venetoclax has a synergistic anti-tumor activity in FLT3-ITD/D835 cells.

Tyrosine kinase inhibitors (TKIs) are established drugs in the therapy of FLT3-ITD mutated acute myeloid leukemia (AML). However, acquired mutations, such as D835 in the tyrosine kinase domain (FLT3-ITD/D835), can induce resistance to TKIs. A cap analysis gene expression (CAGE) technology revealed that the gene expression of BCL2A1 transcription start sites was increased in primary AML cells bearing FLT3-ITD/D835 compared to FLT3-ITD. Overexpression of BCL2A1 attenuated the sensitivity to quizartinib, a type II TKI, and venetoclax, a selective BCL2 inhibitor, in AML cell lines. However, a type I TKI, gilteritinib, inhibited the expression of BCL2A1 through inactivation of STAT5 and alleviated TKI resistance of FLT3-ITD/D835. The combination of gilteritinib and venetoclax showed synergistic effects in the FLT3-ITD/D835 positive AML cells. The promoter region of BCL2A1 contains a BRD4 binding site. Thus, the blockade of BRD4 with a BET inhibitor (CPI-0610) downregulated BCL2A1 in FLT3-mutated AML cells and extended profound suppression of FLT3-ITD/D835 mutant cells. Therefore, we propose that BCL2A1 has the potential to be a novel therapeutic target in treating FLT3-ITD/D835 mutated AML.

Comparison of the clinical performance and usefulness of five SARS-CoV-2 antibody tests

We examined the usefulness of five COVID-19 antibody detection tests using 114 serum samples at various time points from 34 Japanese COVID-19 patients. We examined Elecsys Anti-SARS-CoV-2 from Roche, and four immunochromatography tests from Hangzhou Laihe Biotech, Artron Laboratories, Chil, and Nadal. In the first week after onset, Elecsys had 40% positivity in Group S (severe cases) but was negative in Group M (mild-moderate cases). The immunochromatography kits showed 40–60% and 0–8% positivity in Groups S and M, respectively. In the second week, Elecsys showed 75% and 50% positivity, and the immunochromatography tests showed 5–80% and 50–75% positivity in Groups S and M, respectively. After the third week, Elecsys showed 100% positivity in both groups. The immunochromatography kits showed 100% positivity in Group S. In Group M, positivity decreased to 50% for Chil and 75–89% for Artron and Lyher. Elecsys and immunochromatography kits had 91–100% specificity. Elecsys had comparable chronological change of cut-off index values in the two groups from the second week to the sixth week. The current SARS-CoV-2 antibody detection tests do not provide meaningful interpretation of severity and infection status. Its use might be limited to short-term epidemiological studies.

Preβ1-high-density lipoprotein metabolism is delayed in patients with chronic kidney disease not on hemodialysis

BACKGROUND

Preβ1-high-density lipoprotein (HDL) is a lipid-poor cholesterol acceptor that is converted to lipid-rich HDL by lecithin-cholesterol acyltransferase (LCAT). In patients receiving hemodialysis, preβ1-HDL metabolism is hampered even if HDL cholesterol is normal. Hemodialysis may affect preβ1-HDL metabolism by releasing lipases from the vascular wall due to heparin.

OBJECTIVES

We investigated whether preβ1-HDL metabolism is delayed in patients with chronic kidney disease (CKD) who are not receiving hemodialysis.

METHODS

We examined 44 patients with Stage 3 or higher CKD and 22 healthy volunteers (Control group). The patients with CKD were divided into those without renal replacement therapy (CKD group, n = 22) and those undergoing continuous ambulatory peritoneal dialysis (CAPD group, n = 22). Plasma preβ1-HDL concentrations were determined by immunoassay. During incubation at 37°C, we used 5,5-dithio-bis (2-nitrobenzoic acid) (DTNB) to inhibit LCAT activity and defined the conversion halftime of preβ1-HDL (CHT_preβ1) as the time required for the difference in preβ1-HDL concentration in the presence and absence of 5,5-DTNB to reach half the baseline concentration.

RESULTS

The absolute and relative preβ1-HDL concentrations were higher, and CHT_preβ1 was longer in the CKD and CAPD groups than in the Control group. Preβ1-HDL concentration was significantly correlated with CHT_preβ1 but not with LCAT activity in patients with CKD and CAPD.

CONCLUSION

Preβ1-HDL metabolism is delayed in patients with CKD who are not on hemodialysis. This preβ1-HDL metabolic delay may progress as renal function declines.

Inhibition of FAO in AML co-cultured with BM adipocytes: mechanisms of survival and chemosensitization to cytarabine

Adipocytes are the prevalent stromal cell type in adult bone marrow (BM), and leukemia cells continuously adapt to deficiency of nutrients acquiring chemoresistant profiles in the BM microenvironment. We have previously shown that fatty acid metabolism is a key energy pathway for survival of acute myeloid leukemia (AML) cells in the adipocyte-abundant BM microenvironment. The novel fatty acid β-oxidation (FAO) inhibitor avocatin B, an odd-numbered carbon lipid derived from the avocado fruit, induced apoptosis and growth inhibition in mono-cultured AML cells. In AML cells co-cultured with BM adipocytes, FAO inhibition with avocatin B caused adaptive stimulation of free fatty acid (FFA) uptake through upregulation of FABP4 mRNA, enhanced glucose uptake and switch to glycolysis. These changes reflect the compensatory response to a shortage of FFA supply to the mitochondria, and facilitate the protection of AML cells from avocatin B-induced apoptosis in the presence of BM adipocytes. However, the combination treatment of avocatin B and conventional anti-AML therapeutic agent cytarabine (AraC) increased reactive oxygen species and demonstrated highly synergistic effects on AML cells under BM adipocyte co-culture condition. These findings highlight the potential for combination regimens of AraC and FAO inhibitors that target bone marrow-resident chemoresistant AML cells.

Apolipoproteins C-II and C-III as nutritional markers unaffected by inflammation

BACKGROUND

Rapid turnover proteins (RTPs), such as transthyretin (TTR), retinol binding protein (RBP), and transferrin (Tf), provide an accurate assessment of nutritional status but are susceptible to inflammation. Lipid-related markers, which have short half-lives in serum, may be better suited for nutritional assessment. We sought to identify sensitive nutritional markers unaffected by inflammation.

METHODS

Fasting serum samples were collected from 30 malnourished inpatients and 25 healthy volunteers. Malnourished inpatients were divided into 2 groups: a low-C-reactive protein (CRP) group (CRP < 20 mg/l, n = 15) and a high-CRP group (CRP ≥ 20 mg/l, n = 15). Lipid-related markers, traditional nutritional markers, RTPs, micronutrients, and ketone bodies were measured and compared among the groups.

RESULTS

Apolipoprotein (Apo)C-II and ApoC-III concentrations were lower in malnourished inpatients than in the control group. There was no significant difference in ApoC-II and ApoC-III between the low- and high-CRP groups. Carnitine transporters and ketone bodies did not show a significant difference among the three groups. Albumin, TTR, RBP, and Tf concentrations were lowest in the high-CRP group, intermediate in the low-CRP group, and highest in the control group.

CONCLUSIONS

These results indicate that ApoC-II and ApoC-III are appropriate nutritional biomarkers unaffected by inflammation.

Effect of arachnoid plasty using fibrin glue membrane after clipping of ruptured aneurysm on the occurrence of complications and outcome in the elderly patients

BACKGROUND

In elderly patients with aneurysmal subarachnoid hemorrhage (SAH), complications including vasosopasm, subdural effusion, and late hydrocephalus, are liable to occur even after aneurysmal surgery. We examined prospectively the efficacy of arachnoid plasty using fibrin glue membrane during surgery of ruptured aneurysms in the elderly patients for preventing complications. The effects on the modified Rankin scale (mRS) and the Glasgow outcome scale (GOS) 3 months after SAH were noted.

METHODS

Total of 31 patients aged more than 70 years selected from a consecutive series of patients with aneurysmal SAH, were divided into two groups alternately, a group with arachnoid plasty (n = 16) and a control group without arachnoid plasty (n = 15). Statistical analyses were performed to assess relationships among various clinical and neuroradiological variables, especially between arachnoid plasty and occurrence of symptomatic vasospasm, subdural effusion, late hydrocephalus, or outcome such as mRS and GOS 3 months after onset.

FINDINGS

Statistical analyses revealed that arachnoid plasty were associated with late hydrocephalus and subdural effusion negatively, but with better mRS at 3 months after SAH. A tendency to be associated with less frequent symptomatic vasospasm was also noted.

CONCLUSION

Arachnoid plasty using fibrin glue is suggested to be effective in preventing complications associated with SAH and aneurysmal surgery. A better outcome in the elderly patients can be achieved.

A shotgun tandem mass spectrometric analysis of phospholipids with normal-phase and/or reverse-phase liquid chromatography/electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry is used in lipidomics studies. The present research established a top-down liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) shotgun analysis method for phospholipids (PLs) using a normal-phase column or a C30 reverse-phase column with the data-dependent MS/MS scanning mode. A normal-phase column can separate most of the major different classes of PLs. By using LC/ESI-MS/MS with a normal-phase column, approximately 50 molecular species were identified in a PL mixture from rat liver. When the reverse-phase column was used, the PLs could be separated depending on their hydrophobicity, essentially the length of their fatty acyl chains and the number of unsaturated bonds in them. The LC/ESI-MS/MS method using a C30 reverse-phase column was applied to phosphatidylcholine (PC) and phosphatidylethanolamine (PE) mixtures as test samples. Molecular species with the same molecular mass but with different pairs of fatty acyl chains were separately identified. As a result, about 60 PC and 50 PE species were identified. PLs from rat liver were subjected to LC/ESI-MS/MS using the C30 reverse-phase column and about 110 molecular species were identified. Off-line two-dimensional LC/ESI-MS/MS with the normal-phase and C30 reverse-phase columns allowed more accurate identification of molecular species by using one-dimensional C30 reverse-phase LC/ESI-MS/MS analysis of the collected fractions.

Rapid and selective identification of molecular species in phosphatidylcholine and sphingomyelin by conditional neutral loss scanning and MS3

Analyses of molecular species of phospholipids containing choline (Ch), such as phosphatidylcholine (PC) and sphingomyelin (SM), are reported. Neutral loss scanning was applied for the selective detection of these lipids using a quadrupole-linear ion trap mass spectrometer. By using ammonium formate as an elution buffer, both PC and SM were detected as [M+HCOO]- ions in the negative ion mode. Upon collisional activation, the [M+HCOO]- adduct ions underwent facile elimination of HCO2, to yield an ion which, in turn, readily underwent collisional-induced dissociation (CID) to eliminate CH3 to yield an [M-CH3]- ion. By selecting the proper conditions for scanning for neutral loss of 60 Da (HCO2+CH3), SM species were identified separately from PCs. Further, by selection of this [M-CH3]- ion as the precursor ion, the identities of the fatty acyl chains of PC species can be effectively obtained by MS3 experiments. Furthermore, by the MS3 analyses of [M-CH3]- specifically obtained from SM molecules, identification of sphingosine or sphinganine derivatives and their N-acyl species can also be effectively obtained. This systematic analysis of PCs and SMs by conditional neutral loss scanning, with subsequent analyses by MS3, using a linear ion trap mass spectrometer in the negative ion mode, appears to be a very effective and sensitive method. Further, MS/MS in the positive ion mode at relatively low collision energy was also effective for the identification of positional specificities in individual molecular PC species from their lysoPC-related fragments. The present paper deals only with qualitative identification of individual molecular species, and the related quantitative studies are now underway.

Brain-derived neurotrophic factor modulates glucagon secretion from pancreatic alpha cells: its contribution to glucose metabolism

AIM

Brain-derived neurotrophic factor (BDNF) reduces plasma glucose levels in obese db/db diabetic mice and is speculated to produce its effects via the hypothalamus, the regulatory centre of satiety and the autonomic nervous system. The potential effect of BDNF directly on peripheral endocrine organs, however, remains to be clarified. Here we report the effects of BDNF on hormonal secretion from pancreatic islets of Langerhans using their isolated culture.

METHODS AND RESULTS

In an immunohistochemical study, mouse pancreatic alpha cells were stained specifically with the anti-TrkB (a specific receptor for BDNF) antibody. After 7 days culture of isolated islets of the normal mouse pancreas, 10 ng/ml BDNF decreased the secretion of glucagon per 6 h significantly less than that of the control (p = 0.016). In contrast, there were no significant changes in insulin secretion or glucagon and insulin contents in the islets cultured under the same conditions. In vivo administration of BDNF (10 mg/kg/day) to normal mice for 7 days significantly decreased their food consumption (p < 0.05). The fasting plasma glucose levels were decreased on day 7 compared with day 1 more significantly in BDNF-treated mice (p = 0.043) than in pair-fed control mice (p = 0.14). In newborn BDNF-knockout mice, fasting plasma glucose levels increased in the order of homozygote, heterozygote and wild type (p = 0.033). No apparent immunohistochemical abnormality was observed for pancreatic glucagon in the BDNF-knockout mice.

CONCLUSION

These data suggest that BDNF affects glucose metabolism not only with its anorectic effect but also with modulated glucagon secretion from pancreatic alpha cells.

Insulin inhibits glucagon-induced glycogenolysis in perivenous hepatocytes specifically

Hepatocytes form the hepatic acinus as the unit of microcirculation. Following the bloodstream, at least 2 different zones can be discerned: the periportal and perivenous zones. Two types of hepatocytes, periportal hepatocytes (PPHs) and perivenous hepatocytes (PVHs), have been thought to be functionally heterogeneous, with PPHs being predominantly gluconeogenic and PVHs being glycolytic. We therefore investigated the region-specific functional effects of insulin on glycogen synthesis, glycolysis, glycogenolysis, and gluconeogenesis in isolated PPHs and PVHs prepared by using the digitonin-collagenase method. Glycogen synthesis from 5 to 20 mmol/L glucose did not differ between the PPHs and PVHs of fed rats during 60 minutes of incubation. Lactate release induced by 5 to 20 mmol/L glucose was 3 times greater from PVHs than from PPHs (P <.01). The addition of insulin did not accelerate either glycogen synthesis or lactate release during 60 minutes of incubation. Insulin did not inhibit glucose release from gluconeogenic substrates with or without 0.2 nmol/L glucagon in either the PPHs or the PVHs of fasting rats. Insulin antagonized the 0.1 nmol/L glucagon-induced increase in glucose release from the PVHs of fed rats during 30 minutes of incubation (to 56.1% +/- 7.2%, P <.01) but not that from the PPHs (to 81.8% +/- 7.3%, P =.10). Thus the antagonizing effect was greater in PVHs than in PPHs (P <.01). Insulin binding did not differ between the PPHs and PVHs of fed rats. It was confirmed that PVHs are actually glycolytic. An acute metabolic effect of insulin was observed only in antagonizing glucagon-induced glycogenolysis in PVHs specifically. The specific effect of insulin on PVHs might depend on the differences in intracellular characteristics between PPHs and PVHs rather than hormone binding.

Hormone-specific combinations of isoforms of adenylyl cyclase and phosphodiesterase in the rat liver

Since many isoforms of adenylyl cyclase and adenosine 3', 5'-monophosphate (cAMP) phosphodiesterase have been cloned, it is likely that receptors of each hormone have a specific combination of these isoforms. Types I, III and VIII adenylyl cyclases are reported to be stimulated by Ca(2+)-calmodulin, type I phosphodiesterase by Ca(2+)-calmodulin, but types IV and VII (cAMP-specific) phosphodiesterases by Co2+. In the present study, we examined different effects of Ca2+ and Co2+ on hormone-induced cAMP response in the isolated perfused rat liver.The removal of Ca2+ from the perfusion medium (0 mM CaCl(2 ) + 0.5 mM EGTA) did not affect glucagon (0.1 nM)-responsive cAMP but reduced secretin (1 nM)-, vasoactive intestinal polypeptide (VIP, 1-10 nM)- and forskolin (1 microM)-responsive cAMP considerably. The addition of 1 mM CoCl2 reduced glucagon- and secretin-responsive cAMP considerably, forskolin-responsive cAMP partly, did not affect 1 nM VIP-responsive cAMP, but enhanced 10 nM VIP-responsive cAMP. Forskolin- and VIP-responsive cAMP was greater in the combination (0 mM CaCl(2) + 0.5 mM EGTA + 3 mM CoCl2) than in the Ca(2+)-free perfusion alone. These results suggest that secretin, VIP1 and VIP2 receptors are linked to Ca(2+)-calmodulin-sensitive adenylyl cyclase; glucagon receptor to Ca(2+)-calmodulin-insensitive adenylyl cyclase; VIP1 receptor to Ca(2+)-calmodulin-dependent phosphodiesterase; glucagon, secretin and VIP2 receptors to cAMP-specific phosphodiesterase, respectively, in the rat liver.

Side-to-side arterial anastomosis model in the rat internal and external carotid arteries

Microvascular anastomosis has become a general and essential technique in the field of vascular reconstructive surgery. Side-to-side microvascular anastomosis is rarely performed by microsurgeons. Laboratory training models are essential for the development and refinement of microsurgical techniques. A new experimental model of a side-to-side "arterial" anastomosis in the rat internal and external carotid arteries is presented, in which 100 percent patency was accomplished immediately, and was maintained 7 days after anastomosis. This model can provide an experimental and training tool for side-to-side anastomosis of small arteries.

Impaired neural regulation of insulin secretion related to the leptin receptor gene mutation in Wistar fatty rats

The Wistar fatty (WF) rat is a model of obese Type 2 diabetes mellitus (DM). These rats were bred by crossing Zucker fatty (ZF) and Wistar-Kyoto (WKY) rats. A homo-allelic leptin receptor gene mutation has been reported in ZF rats. We report here how these genetic factors contribute to plasma insulin regulation. The fasting plasma insulin levels were higher in WKY and Wistar lean (WL) rats than in Zucker lean (ZL) rats (p<0.05). The levels in WF and ZF rats were higher than in their respective lean littermates, WL and ZL rats (p<0.05). After intragastric glucose load, the plasma insulin increase was reduced upon pretreatment by intracerebroventricular (i. c.v.) methylatropine (an antagonist of the cholinergic receptor) injection in WL rats (p<0.05) but not in WF rats. Plasma glucagon-like peptide-1 (GLP-1) response to intragastric glucose load was not affected by methylatropine. After selective hepatic-vagotomy, plasma insulin levels increased in wild-type ZL rats (p<0.05). This increase was not observed in heterozygote ZL rats. Surprisingly, this response of plasma insulin was not shown in wild-type WL and WKY rats. ZF and WF rats did show a prominent decrease in insulin response (p<0.05). These results indicate that the genetic factor in ZF rats is associated with impaired vagal nerve-mediated control of insulin secretion. The genetic factor in WKY rats may diminish sensitivity to the vagal information of insulin release and contribute to insulin resistance. Therefore, we conclude that the presence of both genetic factors in a homo-allelic state is important to the development of DM in WF rats.

Hypocaeruloplasminaemia with heteroallelic caeruloplasmin gene mutation: MRI of the brain

We present two patients with hypocaeruloplasminaemia and a heteroallelic caeruloplasmin gene mutation (HypoCPGM). These patients had diabetes mellitus and tremor of the hands, respectively. T2-weighted fast spin-echo MRI showed mildly reduced intensity of the putamen, much more marked on echo-planar imaging.

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

It has been established, mainly by histochemical and immunohistochemical studies, that liver cells are functionally heterogeneous, with periportal hepatocytes (PPHs) being predominantly gluconeogenic and perivenous hepatocytes (PVHs) being glycolytic. We therefore investigated the region-specific functional effects of glucagon on glycogenolysis and gluconeogenesis in isolated PPHs and PVHs prepared by the digitonin-collagenase method. BB rats, a model of insulin-dependent diabetes, were used to study the region-specific heterogeneity of gluconeogenesis in the diabetic state. Although glycogen content was not different between PVHs and PPHs in rats fed the normal diet, basal glucose release was 1.37 times greater in PVHs than in PPHs (P <.05). The increase in glucose release stimulated by 0.01 to 0.1 nmol/L glucagon was 1.52 times greater in PVHs than in PPHs (P < .05), whereas no differences were seen in response to 1 to 100 nmol/L glucagon. Glucose release from gluconeogenic substrates was 1.57 times greater in the PPHs than in the PVHs of fasted normal rats (P < .05), whereas the increase in gluconeogenesis produced by glucagon was not different between PPHs and PVHs. The glucagon-binding capacity, the cAMP release, and the increase in intracellular Ca2+ stimulated by glucagon were not different between PPHs and PVHs in the fed or fasted states. Gluconeogenesis from gluconeogenic substrates was 1.52 times greater in the PPHs than in the PVHs of fasted nondiabetic BB rats (P < .05). After the development of diabetes, the gluconeogenic capacity in PVHs increased to the level observed in PPHs, but that in PPHs did not change. Thus there was no difference in gluconeogenesis between the PPHs and PVHs of diabetic BB rats. In both the PPHs and PVHs of diabetic BB rats, the 0.01 to 100 nmol/L glucagon-induced increase in gluconeogenesis was greater than that in PPHs from nondiabetic BB rats (2.30 and 3.07 times, P < .01, respectively). We conclude that PPHs and PVHs of normal rat liver express region-specific differences in their glycogenolytic and gluconeogenic responses to glucagon. In diabetic BB rats, the difference in the gluconeogenic capacity between PPHs and PVHs disappeared, whereas glucagon-induced gluconeogenesis was enhanced.

Identification of a novel mutation of the CPO gene in a Japanese hereditary coproporphyria family

Hereditary coproporphyria (HCP) is an autosomal dominant disease characterized by a deficiency of coproporphyrinogen oxidase (CPO) caused by a mutation in the CPO gene. Only 11 mutations of the gene have been reported in HCP patients. We report another mutation in a Japanese family. Polymerase chain reaction-single strand conformational polymorphism and direct sequence analyses demonstrated a C to T substitution in exon 1 of the CPO gene at nucleotide position 85, which lies in the putative presequence for targeting to mitochondria. This mutation changes the codon for glutamine to a termination codon at amino acid position 29. MaeI restriction analysis showed two other carriers in the family. The C-T mutation is located within a recently proposed putative alternative translation initiation codon (TIC-1), supporting that TIC-1 is the real TIC rather than TIC-2.

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.

A novel mutation of coproporphyrinogen oxidase (CPO) gene in a Japanese family

Hereditary coproporphyria (HCP) is an autosomal dominant disease characterized by a deficiency of coproporphyrinogen oxidase (CPO). Only 11 mutations of the gene have been reported to date as the mutations responsible for HCP. We report here a novel mutation of the gene responsible for the disease in a Japanese family. Analysis of the polymerase chain reaction (PCR) amplified DNA fragments of the gene by direct-sequencing and/or cloning-based sequencing methods revealed the gene abnormality responsible for the disease. The mutation found was a single base deletion of T at nt position 526, which results in frame shift and truncation of coded protein at amino acid position 204. Screening of pre-symptomatic cases seemed to be possible by PCR restriction analysis using restriction enzyme Xcm I.

Hyperglycemia is a factor for an increase in serum ceruloplasmin in type 2 diabetes

OBJECTIVE

To examine if there is a correlation between high blood glucose and serum ceruloplasmin (Cp) levels.

RESEARCH DESIGN AND METHODS

Serum Cp levels were measured in 637 patients with type 2 diabetes (all type 2 diabetes group). For the follow-up type 2 diabetes group, 161 patients who had not had any changes in their situation during the last year that are known to influence serum Cp levels were reexamined 1 year later. The control group was composed of 158 healthy individuals. Serum Cp and blood HbA1c levels were measured by radial immunodiffusion and high-performance liquid chromatography assays, respectively.

RESULTS

Serum Cp levels in the all type 2 diabetes group were significantly higher than those in the control group (P < 0.0001), although the serum Cp levels did not correlate with the blood HbA1c levels in the all type 2 diabetes group (r = 0.055, P = 0.351). Then we evaluated those factors (delta-log Cp and delta-HbA1c) in the follow-up type 2 diabetes group to minimize changes from the genetic differences and to exclude any known factors influencing serum Cp levels. This indicated that the delta-HbA1c had a positive correlation to the delta-log Cp (r = 0.304, P < 0.0001).

CONCLUSIONS

A persistent high blood glucose (namely HbA1c) is associated with an increase in serum Cp levels over 1 year.

Early potentials of direct cortical responses: experimental study in dogs and pathophysiological and clinical implications

OBJECTIVE

The characteristics of the early component of the direct cortical response have not been well studied, although direct cortical response recording is a common method of brain function monitoring.

METHODS

In this experimental study, we sought conditions affording the clearest recording of the early potential, by varying the polarity and low-cutoff filter setting, and we confirmed that the early potential consists of two components, P1 and P2.

RESULTS

When subcortical damage was induced by local cerebral compression or saline injection, transient changes in P1 and permanent disappearance of P2 were observed. P2 also disappeared when the fiber connections between the cortex and the basal ganglia, including the thalamus, were destroyed by wire insertion. With deep recording, both P1 and P2 exhibited potential reversal at a level histologically confirmed to be in Layer V of the cortex.

CONCLUSION

These findings suggest that P1 is a spike reflecting the activity of pyramidal cells evoked by electrical stimulation of the brain surface and that P2 is a potential arising in Layer V of the cortex and is related to afferent fibers from the thalamus. Recording of P2 may be useful for monitoring for subcortical damage.

Relative contribution of Ca2+-dependent mechanism in glucagon-induced glucose output from the liver

Divalent cations are known to affect the activity of the cAMP-generating system. By observing the effects of the addition of cobalt (Co2+) and the depletion of calcium (Ca2+), this study tried to determine the relative contribution of Ca2+-dependent mechanism in glucagon-induced glucose output from the isolated perfused rat liver. Co2+ (1 mM) completely suppressed glucose and cAMP output induced by 0.1 nM glucagon and partly suppressed those induced by 1 to 10 nM glucagon. Co2+ (1-5 mM) did not inhibit 125I-labeled glucagon binding to hepatic cell membrane. Phenylephrine- or angiotensin II-induced glucose output was not affected by 1 mM Co2+. Co2+ (1 mM) inhibited a glucagon-induced increase in [Ca2+]i in isolated rat hepatocytes but did not inhibit a phenylephrine-induced increase in [Ca2+]i. The removal of Ca2+ from the perfusion medium impaired phenylephrine- or angiotensin II-induced glucose output, but did not impair glucagon-induced glucose output. When glucagon-induced cAMP production was inhibited by Co2+, the glucose output produced by 1 to 10 nM glucagon was impaired further in the Ca2+-free perfusion. Addition of 0.1 mM IBMX increased the glucose output produced by 1 nM glucagon but did not increase that produced by 10 nM glucagon in the Co2+-containing Ca2+-free perfusion. These results suggest that Co2+ inhibits the glucagon-responsive adenylyl cyclase system directly, resulting in impaired glucose output. Glucagon increases [Ca2+]i through a mechanism different from that of phenylephrine. Glucagon (0.01-10 nM)-induced glucose output from the liver is derived mainly through a cAMP-dependent mechanism. Only when glucagon-induced cAMP production was inhibited by Co2+ was the Ca2+ dependency observed in high concentrations (>/=1 nM) of glucagon-induced glucose output, and it approximated 30% of the glucose output produced by 10 nM glucagon.

Sequential changes in CGRP-like immunoreactivity in NIDDM model Otsuka Long-Evans Tokushima Fatty (OLETF) rat pancreatic islets

We describe the changes in B cells and calcitonin gene-related peptide (CGRP)-like immunoreactivity in the pancreatic islets of Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of human non-insulin-dependent diabetes mellitus (NIDDM). In the OLETF rat pancreatic islets, CGRP immunoreactivity was seen in the nerve fibers with multiple varicosities and in endocrine cells that were identical to somatostatin-containing cells, but some somatostatin-immunoreactive cells lacked CGRP immunoreactivity. In the OLETF rats, plasma insulin levels were significantly higher than in the control rats (Long-Evans Tokushima Otsuka; LETO) only at 7 weeks of age. From 7 through 32 weeks of age, OLETF rats had a greater B-cell area than LETO rats. The length of CGRP-immunoreactive nerve fibers per area and the numbers of CGRP-immunoreactive cells per area did not differ between the groups at 7 weeks of age. After 16 weeks of age, both of these CGRP parameters in the OLETF rats became increasingly higher than in the LETO rats. These results suggest that CGRP is a B-cell growth factor and probably an inhibitory factor for insulin secretion.

Hypoglossal nerve paresis caused by spontaneous dissection of kinked internal carotid artery--case report

A 54-year-old male presented with pure hypoglossal nerve paresis. Angiography and magnetic resonance (MR) imaging showed the characteristic findings of left internal carotid artery (ICA) dissection. He received aspirin and his symptoms gradually disappeared. Repeat angiography and MR imaging showed that the lesion had completely disappeared. This case supports the hypothesis that hypoglossal nerve paresis is due to nerve stretching and compression by intramural hematoma of the dissected ipsilateral ICA, and severe tortuosity of the ICA may be a related phenomenon.

[Clinical effects of sodium ozagrel and urokinase in patients with acute cerebral infarction in the territory of the internal carotid artery]

In this study, the clinical effects were compared between a thromboxane synthetase inhibitor (sodium ozagrel) and a thrombolytic agent (urokinase) in patients with acute cerebral infarction. The subjects consisted of 598 patients admitted on the day of the onset of the cerebral infarction in the territory of the internal carotid artery who showed a low density area on CT images within 5 days. Of these patients, 300 were treated with sodium ozagrel and classified as Group Oz, while the remaining 298 were treated with urokinase and classified as Group Ur. The results were as follows: 1. In group Oz, complete recovery of motor impairment was seen in 209 (69.7%) patients. Complete recovery within 3 weeks after onset was seen in 186 (62.0%) patients. In group Ur, complete recovery of motor impairment was seen in 175 (58.7%) patients. Complete recovery within 3 weeks after onset was seen in 120 (40.3%) patients. Therefore, a higher incidence of complete recovery of the motor impairment was noted in group Oz [p < 0.001: chi 2 test]. Similarly, complete recovery within 3 weeks after onset was more frequent in group Oz [p < 0.001: chi 2 test]. 2. In group Oz, complete recovery was made contribution statistically by Anosognosia (Ag) and unilateral neglect (UN) on admission [multivariate analysis: p < 0.01]. In group Ur, complete recovery was made contribution statistically by Ag (p < 0.01), UN (p < 0.01) and aphasia (p < 0.05). 3. Progressive stroke was observed in 29 (9.5%) patients in the group Oz and in 71 (23.0%) patients in group Ur. There was a higher incidence of progressive stroke in group Ur [p < 0.001: chi 2 test] 4. All patients with progressive stroke had initial evidence of deterioration of neurological deficits within 6 days after the onset in group Oz, and within 5 days after the onset in group Ur. The maximal period from the beginning to the end of the deterioration of neurological deficit was 7 days. 5. In group Oz, progressive stroke was only seen in 29 (29.9%) of the patients who were admitted with motor disturbances and unilateral neglect. In group Ur, progressive stroke was seen in 8 (4.3%) of the 187 patients with motor disturbances without higher cortical dysfunction, in 17 (47.2%) of the 36 patients with motor disturbances and higher cortical dysfunction without unilateral neglect and was seen in 46 (61.3%) of the patients with motor disturbances and unilateral neglect. 6. Hemorrhagic infarction was observed in 14 (4.6%) patients in group Oz and in 31 (10.0%) patients in group Ur. There was a higher incidence of hemorrhagic infarction in group Ur [p < 0.001: chi 2 test]. 7. In group Oz, there was a higher incidence of hemorrhagic infarction among patients with atrial fibrillation (Af) on the ECG [p < 0.001: chi 2 test]. Similarly, in group Ur, hemorrhagic infarction was more frequent among patients with atrial fibrillation (Af) on the ECG [p < 0.001: chi 2 test]. Therefore, sodium ozagrel was clinically more efficient and safer than urokinase in patients with acute cerebral infarction.

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.

Case report: interferon induced coma in Sheehan's syndrome

A 54-year-old woman who was being treated with 10 million units (mu) of natural interferon (IFN)-alpha per day for chronic active hepatitis C at a local clinic, developed coma on the fourth day of treatment. On admission to Yamagata University Hospital, she was still in a state of semicoma with severe hyponatraemia (122 mEq/L) and hypochloraemia (89 mEq/L). After the administration of electrolytes, her condition improved remarkably. Endocrinological loading tests showed a hypofunction of the anterior pituitary gland. In consideration of these results, and her past experiences of haemorrhage during childbirth and subsequent amenorrhoea, we diagnosed her illness as a coma as a result of Sheehan's syndrome which had become overt during IFN therapy. She recovered completely after treatment with hydrocortisone and l-thyroxine.

A novel missense mutation in exon 4 of the human coproporphyrinogen oxidase gene in two patients with hereditary coproporphyria

Hereditary coproporphyria (HCP) is an autosomal dominant disease characterized by a deficiency of coproporphyrinogen oxidase. To date, four mutations of the gene have been reported. We report here another mutation in two Japanese families with HCP, which was revealed by analysis of polymerase chain reaction (PCR)-amplified DNA fragments of the gene by a direct-sequencing method. A point mutation, G to A, was found in exon 4 of the gene at position 538 of the cDNA from the reported putative translation initiation codon ATG. This mutation results in a glycine to arginine substitution at amino acid 180. Two carriers in the family were successfully diagnosed by detecting the mutation using restriction analysis of the PCR products.

Identification of a human cDNA homologue to the Drosophila translocation protein 1 (Dtrp1)

In yeast, several integral membrane proteins such as Sec61p, Sec62p and Sec63p have been reported as the components involved in protein translocation across and into the endoplasmic reticulum (ER) membrane. Among them, the homologues of Sec61p have been found both in bacterias and mammals, whereas those of Sec62p or Sec63p have not. So, Sec61p seem to be the evolutionary conserved component, while Sec62p and Sec63p may not. To date, no homologues of Sec62p have been found in mammals yet. Here, we report a novel human cDNA, HTP1 (for human translocation protein 1), that encodes a protein of 399 amino acids that is 36.3% identical (64.6% similar) to Drosophila homologue of Sec62p, Drosophila translocation protein 1 (Dtrpl). Northern blot analysis showed two HTP1 transcripts of about 2.8 and 5.5 kb, which were expressed concomitantly in various human tissues such as heart, brain, placenta, liver and pancreas.

Functional localization of glucose transporter 2 in rat liver

Heterogeneity of zonal hepatocytes is important to elicit specific liver function. We investigated the distribution of glucose transporter 2 (GLUT-2) in normal rat liver by immunostaining and Northern blot analysis. GLUT-2 stained by immunohistochemistry was distributed predominantly in the periportal hepatocytes and gradually thinned towards the perivenous zone. Ultrastructural immunostaining of GLUT-2 showed that it was localized on microvilli of the sinusoidal plasma membrane of hepatocytes but not on the basolateral plasma membrane. Consistent with the distribution of GLUT-2 protein, the level of GLUT-2 mRNA in periportal hepatocytes was 1.9-fold higher than in perivenous hepatocytes selectively isolated by the differential isolation technique. In addition, the mRNA level of phosphoenolpyruvate carboxykinase, one of the key enzymes of gluconeogenesis, was also twofold higher in the periportal hepatocytes. These results suggest that GLUT-2 contributes to the functional difference between periportal and perivenous hepatocytes in glucose metabolism of the liver.

Family study of acute intermittent porphyria and hereditary coproporphyria in Niigata and Akita Prefectures, Japan

Simple screening tests, urinary porphobilinogen (PBG) for acute intermittent porphyria (AIP) and fecal coproporphyrin for hereditary coproporphyria (HCP), were performed in a family study of AIP and HCP. Urinary PBG was positive in 93 of 211 members of 10 AIP families, but was negative in 568 of 572 controls. Fecal coproporphyrin was positive in 54 of 108 members of 10 HCP families, but was negative in 188 controls. A dominant inheritance was assumed by a chi-square test and Weinberg segregation ratio. Worsening factors around puberty were suggested by the onset age and cumulative percentage of genetically loaded cases. Sex-related expression of symptoms was also inferred by a higher incidence of both porphyrias in females than in males. Fitness and penetrance of both porphyrias were good. An l-triiodothyronine loading test was the most useful for the detection of masked carriers of AIP. In conclusion, AIP and HCP in Japan show a dominant inheritance with sex-related metabolic and clinical manifestations.

Hyper-adrenocorticotropinemia in a patient with Addison's disease after treatment with corticosteroids

A 40-year-old man with Addison's disease due to adrenal tuberculosis retained high levels of adrenocorticotropic hormone (ACTH) after conventional hydrocortisone replacement. Plasma ACTH levels were completely suppressed by usual replacement with hydrocortisone (20 mg at 8:00 and 10 mg at 21:00) but rebounded to abnormally high levels the following morning. Administration of 2 mg or 8 mg of dexamethasone suppressed ACTH and cortisol. Magnetic resonance imaging of the brain showed a low-intensity lesion of the pituitary gland. Pituitary hyperplasia or microadenoma with preserved regulation of ACTH was considered to be the cause of the high plasma ACTH levels. The combination of hydrocortisone and dexamethasone reduced plasma ACTH levels.

Intracerebroventricular injection of methylatropine suppresses insulin response to oral glucose load in rats

Hepatic glucoreceptor-vagal afferent inputs to the central nervous system and pancreatic vagal efferent stimuli are important for insulin secretion. In the present study, we examined the effect of intracerebroventricular (i.c.v.) injection of atropine methyl bromide (methylatropine) on the insulin response following glucose ingestion in rats. When rats were injected with methylatropine i.c.v., the plasma glucose concentration increased, the insulin response reduced, and glucagon-like peptide-1 (7-36) amide (tGLP-1) was unchanged following an oral glucose load, compared with the controls. The plasma insulin response following an intravenous glucose load was not affected by i.c.v. or intraperitoneal injection of methylatropine. A transient increase in plasma insulin after selective hepatic vagotomy was inhibited by i.c.v. injection of methylatropine. Arterial blood pressure or pulse rate was not changed by i.c.v. injection of methylatropine. These results show that the central nervous system plays an important role in the vagal control of the insulin response to glucose ingestion. In rats, for the insulin response soon after glucose ingestion (early phase insulin response), direct neural control (hepatic vagal afferent-central nervous system-pancreatic vagal efferent) of the islet B cells seems more important than the intestinal insulinotropic hormone, tGLP-1.

A nonsense mutation of the ceruloplasmin gene in hereditary ceruloplasmin deficiency with diabetes mellitus

A novel mutation of the ceruloplasmin (Cp) gene was found in a patient with hereditary ceruloplasmin deficiency (HCD) with diabetes mellitus (DM). The patient had been treated for DM for about 13 years, and then his illness was diagnosed as HCD. One year later, he was found dead in his home. A decrease in insulin-immunostained cells was observed in the islets of the patient's pancreas tissue, which accounted for his DM. The polymerase chain reaction (PCR)-direct sequencing analysis of the Cp gene of his daughter revealed a novel point mutation, G to A, at nucleotide 2630 in exon 15. This mutation changes the Trp858 codon (TGG) to a stop codon (TAG) (nonsense mutation). PCR-restriction analysis for the mutation revealed that the patient as well as his daughter was a heterozygote for the mutation, indicating that the patient was a compound heterozygote.

Dinucleotide repeat polymorphism in the human ceruloplasmin gene

We have identified a GT dinucleotide repeat polymorphism in intron 14 of the human ceruloplasmin gene. Observed heterozygosity for the polymorphism is 0.84.

Response of truncated glucagon-like peptide-1 and gastric inhibitory polypeptide to glucose ingestion in non-insulin dependent diabetes mellitus. Effect of sulfonylurea therapy

Gastric inhibitory polypeptide (tGIP) and truncated glucagon like peptide-1 (GLP-1) are potent gastrointestinal insulinotropic factors (incretin), are most released after a meal or ingestion of glucose in man and animals. To investigate whether sulfonylurea (SU) affects the secretion of incretin, the modulation of plasma GIP and tGLP-1 levels following glucose ingestion in non-insulin-dependent diabetic type 2 patients with or without SU therapy was studied. A 75-G oral glucose tolerance test (OGTT) was carried out on 9 healthy subjects (controls) and 18 patients with non-obese type 2, 9 of whom were treated by diet alone (NIDDM-diet) and the other 9 with SU (glibenclamide 2.5 mg or gliclazide 40 mg) once a day (NIDDM-SU). Plasma GIP was measured by radioimmunoassay (RIA) with R65 antibody, and GLP-1 was measured by RIA with N-terminal-directed antiserum R1043 (GLP-1NT) and C-terminal-directed antiserum R2337 (GLP-1CT). Following OGTT, plasma glucose, GIP, GLP-1NT, and GLP-1CT in type 2 patients increased more markedly than in controls, despite the lower response of insulin. However, there were no significant differences in plasma levels of these peptides between the NIDDM-diet and NIDDM-SU groups. Therefore, it is unlikely that SU is involved in the high response of GIP and GLP-1s to OGTT in type 2 patients.

Insulin-like growth factor I resistance in peripheral tissue but not in liver in streptozotocin-induced diabetic rats

The metabolic effect of recombinant human insulin-like growth factor I (IGF-I) was investigated by the glucose clamp technique in normal rats and streptozotocin-induced diabetic rats, a model of insulin-dependent diabetes mellitus (IDDM), and compared with that of insulin. Glucose uptake by peripheral tissues was stimulated by intravenous administration of IGF-I at rates of from 0.369 to 3.690 nmol/kg/min in a dose dependent manner, with a potency of 1/52 that of insulin estimated on the basis of the ED50 molar ratio in normal rats. In streptozotocin-induced diabetic rats, the maximum effects of IGF-I and insulin were reduced to 72% and 70% of those in normal rats, respectively, indicating the presence of both IGF-I and insulin resistance. Hepatic glucose output in normal rats was suppressed by IGF-I in a dose dependent manner with a weaker potency of 1/99 that of insulin assessed on the basis of the ED50 values. In streptozotocin-induced diabetic rats, a dose-response curve of the suppressive effect of insulin on hepatic glucose output shifted to the right, indicating the presence of hepatic insulin resistance, but a leftward shifting of the suppressive effect of IGF-I on hepatic glucose output was observed. We concluded that the IGF-I effect on peripheral tissue was decreased but that on the liver was rather increased in streptozotocin-induced diabetic rats, in contrast to the resistance of both peripheral tissues and liver to insulin.

A point mutation, C to T, in exon 8 of the porphobilinogen deaminase gene in a Japanese family with acute intermittent porphyria

Acute intermittent porphyria (AIP) is an autosomal dominant disease characterized by a deficiency of porphobilinogen deaminase (PBGD). To date, only two mutations have been reported in Japanese patients. We report here another mutation of the gene in a Japanese patient. Analysis of the PCR amplified DNA fragments of the gene by direct-sequencing method revealed the gene abnormality responsible for the disease. The mutation found was a point mutation, C to T, in exon 8 of the gene at position 346 of the housekeeping cDNA from the translation codon ATG. This mutation resulted in an Arg116 to Trp substitution. Four carriers in the family were successfully diagnosed by detecting the mutation using restriction analysis of PCR products.

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.

Intracerebroventricular administration of somatostatin octapeptide counteracts the hormonal and metabolic responses to stress in normal and diabetic dogs

Intracerebroventricular (ICV) injection of carbachol elicits hormonal and metabolic responses similar to moderate stress. In normal dogs, ICV carbachol stimulated marked counterregulatory hormone release, but altered plasma glucose only marginally because the marked increment in glucose production (Ra) was almost matched by the increment of utilization (Rd), even though plasma insulin was unchanged. In alloxan-diabetic dogs, Rd did not match Ra and plasma glucose increased substantially. Since somatostatin octapeptide (ODT8-SS) inhibits some sympathetic mechanisms of the stress response, we explored the extent to which ODT8-SS can alleviate the counterregulatory responses to stress induced by carbachol, and particularly whether it can restore glycemic control in diabetes. ODT8-SS (20 nmol) was ICV-injected (1) in normal dogs (n = 5), and (2) prior to ICV carbachol before (n = 7) and after (n = 6) the induction of alloxan-diabetes. ODT8-SS did not affect basal values, but when administered before ICV carbachol there were no significant increments in plasma epinephrine, cortisol, arginine vasopressin (AVP), insulin, glucose, or lactate. There were significant increases in norepinephrine, glucagon, Ra, Rd, and the glucose metabolic clearance rate (MCR), although they were much smaller than seen previously with ICV carbachol alone. After induction of alloxan-diabetes, Rd and MCR did not change with ICV ODT8-SS and carbachol as in normal dogs, but norepinephrine, epinephrine, glucagon, lactate, plasma glucose, and Ra increased, although with the exception of glucagon these increases were much smaller than seen previously with ICV carbachol alone. ODT8-SS administered before ICV carbachol in normal or diabetic animals resulted in increased free fatty acid (FFA) levels. The increases in glycerol were less than and those in FFA greater than seen previously with ICV carbachol alone. Since ODT8-SS does not alter basal counterregulatory hormone release but suppresses the release during stress, this is a useful probe to analyze some of the metabolic responses to stress. When the response to carbachol from our previous report is compared with the responses to carbachol + ODT8-SS, it is indicated that the stress-related increase in Ra was consistent with stimulation of the sympathetic nervous system, whereas increased Rd is related to an unknown stress-related neuroendocrine mechanism that requires a permissive effect of insulin, since it was not seen in the frankly diabetic animals. We hypothesize that the stress-induced increase in Rd occurs not only in muscle but also in adipocytes, and that the somatostatin-induced attenuation of Rd decreased FFA re-esterification and consequently markedly increased stress-induced FFA release.(ABSTRACT TRUNCATED AT 400 WORDS)

Gliclazide directly suppresses arginine-induced glucagon secretion

To clarify whether the effect of sulfonylurea on glucagon secretion is directly on the pancreatic A cell, we examined changes produced by gliclazide in glucagon (IRG), insulin (IRI) and somatostatin (IRS) release from the isolated perfused rat pancreas. Under 5 mM glucose infusion, IRI and IRS were increased by gliclazide in a dose-dependent manner, but IRG was unchanged. When 20 mM arginine was infused to stimulate glucagon secretion, both IRI and IRG increased markedly in a biphasic fashion and IRS increased slightly. The administration of gliclazide at the time of second phase response of IRG, IRI and IRS increased further and IRG decreased at every dose used. Insulin administration to the control and streptozotocin-treated rat pancreas did not change arginine-induced IRG secretion. Gliclazide-induced glucagon suppression was also observed in streptozotocin-diabetic rat pancreas. The amount of administered somatostatin required for inhibiting glucagon secretion was higher than the maximal level obtained from endogenous secretion of somatostatin after gliclazide. Neither cysteamine treatment alone (somatostatin-depleted) nor combined with streptozotocin-treatment (combined depletion of somatostatin and insulin) changed gliclazide-induced glucagon suppression. Thus, it is concluded that suppression of glucagon is induced by sulfonylurea itself.

Catecholamine-induced cAMP response in streptozotocin-induced diabetic rat liver

The effect of prolonged diabetic state on catecholamine-induced adenosine 3',5'-monophosphate (cAMP) response in the rat liver was examined using isolated liver perfusion. Epinephrine- or isoproterenol-induced cAMP production was enhanced (10-fold of the control) in the liver from extremely emaciated (intraperitoneal adipose tissue was absent completely) diabetic rats 4 weeks after streptozotocin-injection kept without insulin, but not from adipose tissue-present diabetic rats. Glucagon-induced cAMP production was decreased in the diabetic rat liver 4 weeks after streptozotocin regardless of the presence or absence of adipose tissue. Secretin-induced cAMP production was also decreased in the adipose tissue-absent diabetic rat liver. Plasma levels of glucose or insulin were not different between adipose tissue-present and -absent diabetic rats. Liver dysfunction (elevated AST and ALT levels) was observed 1 week after streptozotocin-injection, and worsened at 4 weeks. Forskolin-induced production of cAMP, and oxymetazoline (an alpha 2-adrenergic agonist)-induced suppression of it were not different among the control, newly diabetic (1 week after streptozotocin-injection), and the adipose tissue-absent diabetic rat liver.

IN CONCLUSION

1) enhanced beta-adrenergic, and decreased glucagon- or secretin-induced cAMP production seems to be caused by different mechanisms; 2) the prolonged severe diabetic state losing adipose tissue may cause a considerable change in metabolism and the characteristics of hepatocyte, and lead to enhanced beta-adrenergic cAMP production.

Acute intermittent porphyria caused by a single base insertion of C in exon 15 of the porphobilinogen deaminase gene that results in a frame shift and premature stopping of translation

A single base insertion of C in exon 15 of the porphobilinogen deaminase (PBG-D) gene was observed in a patient with acute intermittent porphyria (AIP) by polymerase chain reaction (PCR)-direct sequencing analysis. The insertion locates between positions -22 and -21 from the translation termination codon TAA, causes a frame shift, and results in a stop codon located 4 codons downstream from the insertion (premature stopping of translation). The mutation generates an MspI recognition site, which can be used, in turn, to detect the mutant allele. Analysis of the cDNA fragments amplified by PCR revealed the existence of the abnormal PBG-D mRNA from the mutant allele in the patient.

Stimulation of truncated glucagon-like peptide-1 release from the isolated perfused canine ileum by glucose absorption

To elucidate whether glucose absorption is necessary for oral glucose-induced truncated glucagon-like peptide-1 (tGLP-1) release, we examined tGLP-1 release by several stimulants from isolated perfused canine ileum. Glucose and nonabsorbable sugars, sucrose and 2-deoxyglucose (2DG), were intraluminally administrated. Following gel filtration of the perfusate after glucose ingestion, the main component of GLP-1 in the eluate is tGLP-1. Both glucose and tGLP-1 in the effluents increased after the intraluminal administration of 5% glucose, but not by that of sucrose or 2DG. Glucose absorption is more important than contact of glucose with ileal epithelium to stimulate tGLP-1 release.

Acute intermittent porphyria caused by a G to C mutation in exon 12 of the porphobilinogen deaminase gene that results in exon skipping

Genomic DNA from a patient with acute intermittent porphyria were analyzed by the polymerase chain reaction (PCR)-direct sequencing method. The patient was heterozygote for a point mutation G to C at the last position of exon 12 of the porphobilinogen deaminase (PBG-D) gene. Analysis of the cDNA fragments amplified by PCR revealed that the patient has the abnormal PBG-D mRNA, which does not have exon 12 and exists in an approximately equal amount to the normal mRNA.