Myosin light-chain phosphorylation controls insulin secretion at a proximal step in the secretory cascade

The aim of this study was to investigate how insulin secretion is controlled by phosphorylation of the myosin light chain (MLC). Ca2+-evoked insulin release from pancreatic islets permeabilized with streptolysin O was inhibited by different monoclonal antibodies against myosin light-chain kinase (MLCK) to an extent parallel to their inhibition of purified MLCK. Anti-MLCK antibody also inhibited insulin release caused by the stable GTP analog guanosine 5'-O-(3-thiodiphosphate), even at a substimulatory concentration (0.1 microM) of Ca2+. Free Ca2+ increased MLC peptide phosphorylation by beta-cell extracts in vitro. In contrast to the phosphorylation by purified MLCK or by calmodulin (CaM) kinase II, the activity partially remained with the beta-cell under nonstimulatory Ca2+ (0.1 microM) conditions. The MLCK inhibitor ML-9 inhibited the activity in the beta-cell with both substimulatory and stimulatory Ca2+, whereas KN-62, an inhibitor of CaM kinase II, only exerted an influence in the latter case. ML-9 decreased intracellular granule movement in MIN6 cells under basal and acetylcholine-stimulated conditions. We propose that MLC phosphorylation may modulate translocation of secretory granules, resulting in enhanced insulin secretion.

Local synthesis of natriuretic peptides in the eel intestine

The intestine is a major osmoregulatory organ in euryhaline fishes which allows them to survive in the sea, and natriuretic peptides have been implicated in regulation of transmural transport. Atrial (ANP) and ventricular natriuretic peptide (VNP) were identified in eel intestine. Elution profiles of ANP and VNP from high-performance liquid chromatography (HPLC) were determined by radioimmunoassay using highly specific antisera. Elution times of immunoreactive ANP and VNP in HPLC were identical to those of authentic peptide standards and were consistent with the relative molecular masses of these peptides. Tissue localization of ANP and VNP was accomplished by fluorescence immunohistochemistry. Immunoreactive cells were observed in the epithelium of anterior, middle, and posterior regions of intestine. Reverse transcription of mRNA isolated from intestine and subsequent polymerase chain reaction amplification yielded appropriate-size products consistent with ANP and VNP expression. Together, these data show that natriuretic peptides are synthesized locally in eel intestine, rather than trapped from the circulation.

Early song-deprivation affects the expression of protein kinase C in the song control nuclei of the zebra finch during a sensitive period of song learning

Male zebra finches learn to imitate a tutor's song through auditory and motor learning during a sensitive period. The molecular aspects of auditory-dependent learning was investigated using protein kinase C (PKC) as a molecular marker for synaptic plasticity. We found a transient increase in the expression of PKC in the robust nucleus of the archistriatum (RA) during a sensitive period. Furthermore, both early deafening by cochlea removal and song deprivation inhibited the increase of PKC enzyme activity. The results strongly suggest that PKC is an important enzyme related to the synaptic plasticity of RA neurons during a sensitive period of song learning in the zebra finch.

Transient liver accumulation of Tc-99m phytate in hepatocellular carcinoma after percutaneous ethanol injection

PURPOSE

We report that colloid liver scanning gave early evidence of the return to normal of Kupffer cell functions after ethanol injections into the liver.

PATIENT AND METHODS

A 71-year-old man with hepatocellular carcinoma received percutaneous ethanol injections twice of 15 mL of ethanol, 1 week apart.

RESULTS

Abdominal CT after the second injection showed an irregularly shaped low-density area in the left side of the tumor, extending outside the tumor. Liver imaging with To-99m phytate 10 days later showed increased activity at the corresponding site. Thirty days after the second injection, liver imaging did not show high activity.

CONCLUSIONS

Ethanol that leaked into the normal part of the liver probably temporarily activated Kupffer cell function.

[Propofol anesthesia for a schizophrenic patient]

A 41-year-old man weighing 68 kg was scheduled for bilateral tonsillectomy because of palmoplantar pustulosis. The patient had been diagnosed as schizophrenic 10 years earlier. Psychotropic agents, mosapramine (75 mg.day-1), bromperidol (6 mg.day-1), cloxazolam (3 mg.day-1), biperiden (1 mg.day-1) and nitrazepam (5 mg as needed), were administered until the day before surgery. On the day of surgery, atropine (0.g mg) and midazolam (4 mg) were administered intramuscularly as premedication. Anesthesia was induced by intravenous propofol (120 mg) and fentanyl (100 microgram) followed by nasotracheal intubation using vecuronium (7 mg). Anesthesia was maintained with inhalation of oxygen and nitrous oxide (2 l.min-1 each) and the intravenous infusion of propofol (5-10 mg.kg-1 x h-1) supplemented by fentanyl (100 microgram). The patient recovered from anesthesia uneventfully. Immediately after surgery, intravenous haloperidol (5 mg) and intramuscular biperiden (1 mg) were given. The daily oral administration of psychotropics was resumed on the first postoperative day. There were no complications such as hypotension, arrhythmia, or worsening of the mental condition, throughout the course.

Clinical implication of expression of progesterone receptor form A and B mRNAs in secondary spreading of gynecologic cancers

This study was designed to determine the clinical implication of expression of progesterone receptor form A (PR-A) and B (PR-B) mRNAs in secondary spreading of gynecologic cancers. Approximately equal expression of PR-A and PR-B mRNAs was designated as type AB and dominant expression of PR-B mRNA as type B. Alteration from type AB to type B in the metastatic cancers occurred in 3/8 cases of uterine endometrial cancers, 2/8 cases of uterine cervical cancers, and 2/8 cases of ovarian cancers. Other cancers revealed type B regardless of primary or metastatic status. Thus, all metastatic cancers studied revealed type B. These results suggest that transcription of PR-A mRNA may be damaged, which might lead to uncontrolled overexpression of PR-B mRNA in metastatic lesion, and that the type B status could reveal a highly malignant phenotype in these three gynecologic cancers.

Cholinergic innervation of the song control nuclei by the ventral paleostriatum in the zebra finch: a double-labeling study with retrograde fluorescent tracers and choline acetyltransferase immunohistochemistry

During the sensitive period of song learning, the content of acetylcholine and the enzyme activity of choline acetyltransferase (ChAT) increase remarkably in the song control nuclei of a young male zebra finch. Cholinergic fibers innervate the two main song control nuclei of the forebrain: the higher vocal center (HVC) and the robust nucleus of the archistriatum (RA). The present study combines the retrograde tracer, Fluoro-Red (FRe), with ChAT immunohistochemistry. The results indicate that the cholinergic fibers which innervate the RA and HVC originate from the ventral paleostriatum (VP) in the basal forebrain, and that there is an anterior-posterior topography in the location of the cholinergic neurons in the VP that project to the HVC and RA, although there are a few neurons which project to both nuclei. These findings suggest that the VP is homologous to the nucleus basalis of Meynert of the basal forebrain cholinergic system of mammals which is associated with learning and memory processes, and that the cholinergic neurons in the VP play an important role in avian song learning.

TNF-alpha stimulates the biosynthesis of complement C3 and factor B by human umbilical cord vein endothelial cells

The human umbilical cord vein (HUVEC) endothelial cells synthesize and secrete complement components. We analyzed the regulation of biosynthesis of the third component of complement (C3) and factor B (Bf) by cytokines in endothelial cells. Production of C3 increased after stimulation with TNF-alpha or IL-1beta and that of Bf with TNF-alpha, TNF-beta and IFN-gamma. TNF-alpha was the most effective in stimulating the secretion of C3 and Bf or the expression of mRNA of C3 or Bf. Preincubation with TNF-alpha for at least 36 or 24 h was needed for the stimulation, respectively. TNF-alpha, together with IFN-gamma had synergistic effects and the release of C3 or Bf increased to about 40- and 26-fold higher than those in control cells after incubation with both cytokines.

Expression of E-cadherin and alpha- and beta-catenin mRNAs in ovarian cancers

To know the biological role of the adherens junction, mainly consisting of E-cadherin and alpha- and beta-catenins, associated with invasion and metastasis of ovarian cancers, we studied the expressions of E-cadherin and alpha- and beta-catenin mRNAs in the cancers in comparison with those in normal counterparts. The integral expression of E-cadherin and alpha- and, beta-catenin mRNAs was suppressed in the metastatic lesions of advanced ovarian cancers, while it was not in the primary tumors. Therefore, the suppressed expression of main adhesion molecules in the adherens junction might contribute to adherens junctional dysfunction, which might lead to the acquirement of invasiveness and metastatic potential by advanced ovarian cancers as one of the rate-limiting steps.

A case of nonfunctioning pituitary adenoma resembling so-called silent corticotroph adenoma

It has been indicated that some subsets of clinically nonfunctioning pituitary adenoma exhibit immunohistochemical and ultrastructural features of somatotroph or corticotroph cells, which are described as silent somatotroph and corticotroph adenomas, respectively. We here describe a 70-year-old woman with nonfunctioning pituitary adenoma presenting with visual disturbance. None of the pituitary hormones show abnormal finding. Magnetic resonance imaging study revealed a pituitary tumor which developed inferiorly into the sphenoidal sinus. Tumor resection was performed by a transsphenoidal approach, and resulted in a partial resection of the tumor. The specimen indicated chromophobic adenoma. Immunohistochemical examination revealed a characteristic distribution pattern of cytokeratin staining for ACTH cell adenoma, although immunostaining for ACTH was only weakly positive. After the operation, only ACTH secretion was impaired, requiring replacement therapy with glucocorticoid. Bromocriptine was administered in order to prevent the recurrence of the tumor. It remains to be elucidated whether the present case could be classified as silent corticotroph adenoma, which was originally indicated to have aggressive characteristics, i.e., progressive visual defect, high incidence of infarction and frequent recurrence.

Optimal lipiodol volume in transcatheter arterial chemoembolotherapy for hepatocellular carcinoma: study based on lipiodol accumulation patterns and histopathologic findings

To clarify the optimal dose of Lipiodol (Andre Guerbet, Aulnay-sous-Bois, France) during Lipiodol-transcatheter arterial embolization (L-TAE) and segmental L-TAE used to treat hepatocellular carcinoma, we studied the relationship between the volume of Lipiodol used during these procedures and the necrosis rates in resected specimens, as well as the correlation with the Lipiodol accumulation pattern based on the computed tomography findings (L-CT) and the volume of Lipiodol in resected and nonresected cases after L-TAE or segmental L-TAE. The L-CT and the dose of Lipiodol injected (mL) were studied correlatively in 198 cases (28 resected cases and 170 nonresected cases; tumor size < or = 5 cm in 52 cases and > 5 cm in 118 cases) that underwent L-TAE and in 80 cases (14 resected cases and 66 nonresected cases, tumor size < or = 5 cm in 52 cases and > 5 cm in 14 cases) that underwent segmental L-TAE. The L-CT was classified into four types: type I, homogeneous accumulation (type Ia, accumulation around the tumor; type Ib, no accumulation around the tumor); type II, partial defect; type III, sporadic accumulation; and type IV, punctate or no accumulation. In the 42 resected cases (L-TAE, 28 cases; segmental L-TAE, 14 cases), type I was seen in 68% (Ib, 100%) of the L-TAE cases and 93% (Ia, 79%; Ib, 14%) of the segmental L-TAE cases. The necrosis rate of the cases with type Ib L-CT was 90% to 100%, and all type Ia cases showed complete necrosis. In the 236 nonresected cases (L-TAE, 170 cases; segmental L-TAE, 66 cases), the volume of Lipiodol injected correlated with the L-CT type. In the L-TAE cases with a tumor size < or =5 cm, the frequency of the injected Lipiodol volume (D) being greater than the tumor diameter (d) (D > or = d) was 90%, and 87% of the cases with D > or = d showed type Ib L-CT. In the group whose tumor diameter (d) was more than 5 cm, the frequency of D > or = d was 25%, and 70% of the cases of D > or = d were type Ib. The frequency of D < d was 75%, and in 13% of these cases the L-CT was type Ib and the maximum dose was approximately 10 mL. In segmental L-TAE using the same dose of Lipiodol as in L-TAE, the frequency of D > or = d was 83%, and 93% of those cases showed type I, including 85% of type Ia. There was a correlation between the L-CT type and the necrosis rate, and type I, especially Ia in segmental L-TAE, showed complete necrosis in almost all cases. In L-TAE, standards for the optimal dose of Lipiodol are thought to be as follows: D > or = d in cases with d < or = 5, and slightly D < d and 10 mL maximally in cases with d > 5. In segmental L-TAE using the same dose of Lipiodol as in L-TAE, enhancement of the therapeutic effect was seen compared with L-TAE. This is surmised to have been because of the higher Lipiodol volume with anticancer agents per unit volume of the tumor in segmental L-TAE.

A role for macrophage scavenger receptors in atherosclerosis and susceptibility to infection

Macrophage type-I and type-II class-A scavenger receptors (MSR-A) are implicated in the pathological deposition of cholesterol during atherogenesis as a result of receptor-mediated uptake of modified low-density lipoproteins (mLDL). MSR-A can bind an extraordinarily wide range of ligands, including bacterial pathogens, and also mediates cation-independent macrophage adhesion in vitro. Here we show that targeted disruption of the MSR-A gene in mice results in a reduction in the size of atherosclerotic lesions in an animal deficient in apolipoprotein E. Macrophages from MSR-A-deficient mice show a marked decrease in mLDL uptake in vitro, whereas mLDL clearance from plasma occurs at a normal rate, indicating that there may be alternative mechanisms for removing mLDL from the circulation. In addition, MSR-A-knockout mice show an increased susceptibility to infection with Listeria monocytogenes or herpes simplex virus type-1, indicating that MSR-A may play a part in host defence against pathogens.

Ex vivo study of the increased sensitivity to NO of endothelium-denuded thoracic aortas isolated from dietary magnesium-deficient rats

The mechanisms underlying the enhanced relaxant responses to sodium nitroprusside (SNP) associated with magnesium (Mg) deficiency were examined using endothelium-denuded thoracic aortas isolated from rats with dietary Mg deficiency. This enhancement of SNP-induced relaxation was abolished or depressed in the presence of methylene blue (a guanylate cyclase inhibitor). The relaxant responses to 8-bromo cyclic GMP (8-Br cGMP; a membrane-permeable cGMP) of thoracic aortas isolated from Mg-deficient rats were enhanced like those to SNP. These enhanced relaxant responses were depressed by tetraethylammonium (a non-specific K+ channel blocker). Charybdotoxin, a large conductance Ca2+-activated K+ (K[Ca]) channel blocker, inhibited 8-Br cGMP-induced relaxations of aortas from Mg-deficient and control rats. Apamin, a small conductance K(Ca) channel blocker, inhibited 8-Br cGMP-induced relaxations of aortas from Mg-deficient, but not control rats. The relaxant responses to cromakalim (an ATP-sensitive K+ channel opener) of the two groups were not significantly different. These ex vivo results show that dietary Mg deficiency in rats leads to increased sensitivity to NO of endothelium-denuded thoracic aortas in vitro and K(Ca) channel activation via cGMP may be involved in this enhancement.

Ex vivo study of the effects of dietary magnesium deficiency on the formation and release of NO from endothelial cells and the sensitivity to NO of smooth muscle cells of thoracic aortas isolated from rats

We found that the contractile responses to phenylephrine (PE) of isolated endothelium-intact thoracic aortas were enhanced by a nitric oxide (NO) synthase inhibitor, nitro-L-arginine (LNAG). and the magnitude of this enhancement was significantly greater in Mg-deficient than control rats. In this study, we used a sandwich method to evaluate the effects of dietary Mg deficiency on the ability of vascular endothelial cells to form and/or release NO and on the sensitivity to NO of vascular smooth muscle cells. Male Wistar rats were fed a Mg-deficient (10 mg Mg/kg diet) or control (700 mg Mg/kg diet) diet for 30 days. With the sandwich method, when endothelium-denuded thoracic aortas from chow fed rats were used as the assay vessels, and endothelium-intact aortas from control or Mg-deficient rats were used as the NO-donor vessels, neither the aortic contractile responses to PE nor the enhancement by LNAG of these responses in control and Mg-deficient rats differed significantly. When endothelium-denuded thoracic aortas from control or Mg deficient rats were used as the assay vessels and endothelium-intact aortas from chow fed rats were used as NO-donor vessels, LNAG enhanced PE-induced contractions to a significantly greater extent in Mg-deficient than control rats. Furthermore, sodium nitroprusside (a NO donor) had a greater relaxant effect on endothelium-denuded thoracic aortas isolated from Mg-deficient than control rats. These ex vivo results suggest that dietary Mg deficiency in rats has little effect on the formation and/or release of NO by aortic endothelial cells. but it does appear to increase the sensitivity to NO of aortic smooth muscle cells.

Plausible novel therapeutic strategy of uterine endometrial cancer with reduction of basic fibroblast growth factor secretion by progestin and O-(chloroacetyl-carbamoyl) fumagillol (TNP-470; AGM-1470)

To know the potential of growth, invasion and metastasis of endometrial cancer associated with neovascularization, the effects of sex steroids and O-(chloroacetyl-carbamoyl) fumagillol (TNP-470; AGM-1470) on basic fibroblast growth factor (FGF) expression and secretion and its mRNA expression were investigated in well-differentiated endometrial cancer cell line Ishikawa and in undifferentiated endometrial cancer cell line AN3 CA. Basic FGF expression and secretion and its mRNA expression in Ishikawa cells, but not in AN3 CA cells, were increased by estrogen, while progesterone diminished the estrogen-induced increases. TNP-470 reduced the levels regardless of estrogen treatment in AN3 CA cells. Therefore, basic FGF secretion may be inhibited by progestin in differentiated cells, and by TNP-470 in undifferentiated cells. Since endometrial cancer consists of differentiated and undifferentiated cells as heterogeneity, a combination therapy for endometrial cancer with progestin and TNP470 might be effective.

[A case of asymptomatic posterior mediastinal pheochromocytoma diagnosed during the procedure of video-assisted thoracic surgery (VATS)]

The patient was a 20-year-old male. On routine check-ups, a posterior mediastinal tumor was found radiologically and referred to our hospital for the operation. During the Video-Assisted Thoracic Surgery (VATS), sudden elevation of the blood pressure up to 270 mmHg was observed by the tumor palpation. At once we diagnosed as pheochromocytoma. Changing the VATS to usual thoracotomy the tumor was completely removed and histologically confirmed. After the operation the patient was uneventful and the value of norèpinephrine reduced to normal range from 2912 pg/ml. The posterior mediastinal pheochromocytoma is rare and this report is the 6 th case in Japan. Clinical characteristics were discussed in addition to the review of the literature.

Expression of estrogen receptor wild type and exon 5 splicing variant mRNAs in normal and endometriotic endometria during the menstrual cycle

Expression of estrogen receptor exon 5 splicing variant (ER-E5SV) mRNA contributes to dominant positive properties and metastatic potential of gynecological cancers. Therefore, in endometriotic endometria, which conserve implantation and tumor-like spreading potentials, the expression of ER-E5SV and estrogen receptor wild type (ER-WT) mRNA was analyzed, to investigate the biological implications. Estrogen receptor wild type mRNA in normal endometria was downregulated after ovulation, but not in endometriotic endometria. Therefore the wild type cascade in endometriotic endometria might be partly disorganized. The level of ER-E5SV mRNA in endometriotic endometria was lower than that in normal endometria, regardless of the stage in the menstrual cycle. However, there was no significant difference in the ratio of ER-E5SV to ER-WT mRNA in both normal and endometriotic endometria. On the other hand, the level of ER-E5SV mRNA in both normal and endometriotic endometria did not vary during the menstrual cycle. The dominant positive behavior of ER-E5SV might be masked by the functional cascade of ER-WT in normal endometria, but not in endometriotic endometria. This status might result in an incomplete response to endogenous steroids, and contribute to implantation and spreading potentials of endometriosis.

Expression of E-cadherin and alpha- and beta-catenin mRNAs in uterine cervical cancers

To show the mRNA expressions of E-cadherin and alpha- and beta-catenin-which mainly compose the adherens junction-associated with invasion and metastasis of uterine cervical cancers, we studied the expression of E-cadherin and alpha- and beta-catenin mRNAs in cancers in comparison with normal counterparts. The integral expression of E-cadherin and alpha- and beta-catenin mRNAs was suppressed in the metastatic lesions of advanced uterine cervical cancers, while it was not in the primary tumors. Therefore, the suppressed expression of main adhesion molecules in the adherens junction might contribute to adherens-junctional dysfunction, which might lead to invasiveness and metastatic potential of advanced uterine cervical cancers as one rate-limiting step.

Intranuclear mitochondria in human myocardial cells

Intranuclear mitochondria have occasionally been reported in various cells including cardiac myocytes, but the incidence and details including the specific mechanism(s) whereby mitochondria exist in the nuclear matrix are unknown. We studied the ultrastructure of a total of 91 consecutive endomyocardial biopsy specimens obtained from 50 patients with various cardiac diseases. Intranuclear mitochondria were found in three patients: two with hypertrophic cardiomyopathy and one with chronic myocarditis. Their myocytes were markedly hypertrophic and the shapes of the nuclei were bizarre. Specimens from these patients were further studied on serial sections, and some of the nuclei with mitochondria showed ruptured nuclear envelope. Intranuclear mitochondria were found in at least 6% of the patients with cardiac diseases (3% of the specimens examined), and a novel mechanism of the pathogenesis was documented: communication between the nuclear matrix and cytoplasm through the rupture in the nuclear envelope. The nuclear rupture might be simply due to a laboratory artifact. On the other hand, it might imply some pathophysiological significances in the degeneration of myocytes in cardiac diseases.

Expression of basic fibroblast growth factor and its mRNA in advanced uterine cervical cancers

To know the potential of growth, invasion and metastasis of uterine cervical cancer cells associated with neovascularization, the expression of basic fibroblast growth factor (FGF) and its mRNA in uterine cervical cancers and normal uterine cervices as controls were determined by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction-Southern blot (RT-PCR-SB), respectively. Then, the relations between the expression and the histological grading and clinical staging in cervical cancers were analyzed. The levels of basic FGF and its mRNA were significantly higher in advanced primary uterine cervical cancers, regardless of histological type. Therefore, this status might contribute to the acceleration of growth, invasion, and metastasis with neovascularization in advanced uterine cervical cancers.

Evidence for the involvement of transforming growth factor-alpha in implantation in the rat

This study was conducted to examine the possibility for participation of transforming growth factor-alpha (TGF-alpha), one of the epidermal growth factor (EGF) family of growth factors, in implantation in the rat. Immunostaining of TGF-alpha in the periimplantation uterus showed distinct staining in the luminal and glandular epithelium and moderate staining in stromal and myometrial cells. After implantation decidual cells and embryos were also positive stained for immunostaining. Immunocytochemistry of EGF receptor showed distinct staining in the luminal and glandular epithelium during the preimplantation period, and after implantation decidua at implantation sites and embryos were stained. Intraluminal injection of anti-TGF-alpha antibodies into uterine horns at 0600 h on day 5 of pregnancy decreased the number of rats showing implantation (blue dye reaction) at 0200 h on day 6 in a dose-dependent manner. Intraluminal injection of 100 pg of TGF-alpha on day 5 of pseudopregnancy elicited a greater decidual response when compared with the vehicle-injected contralateral uterine horn. Intraluminal injection of 20 pg of TGF-alpha into each uterine horn induced implantation in 50% of the ovariectomized progesterone-treated delayed implanting rats. These results suggest that TGF-alpha is involved in the implantation process in the rat.