Electrophysiological properties and their modulation by norepinephrine in the ambiguus neurons of the guinea pig

Electrophysiological properties of guinea pig ambiguus (AMB) neurons were studied in a brainstem slice preparation. During subthreshold depolarization AMB neurons displayed an early slow depolarization and a late outward rectification both of which were blocked by replacing Ca2+ with Co2+ in the extracellular solution. AMB neurons showed hyperpolarizing inward rectification which was blocked by extracellular Cs+ and is likely caused by the activation of Ih: In 58% (n = 49) of AMB neurons spike firing was restricted to the early phase of a long-lasting depolarizing current injection (phasic firing). The remaining AMB neurons showed repetitive firing throughout the depolarization (tonic firing). A Ca(2+)-mediated K+ current (IK(Ca)) caused an afterhyperpolarization that followed both single and repetitive spike firing. IK(Ca) also controlled the firing pattern in both types of firing, especially in the phasic firing. Norepinephrine (NE) blocked both the hyperpolarizing inward rectification and the Ca(2+)-dependent AHP. These effects of NE were antagonized by propranolol. It is proposed that the blockade of IK(Ca) and Ih contribute to the improvement of the 'signal-to-noise ratio' by NE in AMB neurons.

Effect of repeated administration of delta 9-tetrahydrocannabinol on delayed matching-to-sample performance in rats

In the present study we examined the effect of repeated exposure to delta 9-tetrahydrocannabinol (THC) at a dose of 10 mg/kg (once a day for 4 days) 24 h after administration, on delayed matching-to-sample (DMTS) performance in rats using a three-lever operant apparatus. Although DMTS performance was not changed on the 1st day, it was impaired on the 2nd day. The impairment was potentiated in dependence of repeated administration. After withdrawal of THC, the impairment of DMTS performance gradually disappeared. On the 10th day after withdrawal, readministration of 10 mg/kg THC resulted in marked impairment of DMTS performance at 24 h after administration. Furthermore, a single administration of 1.0 mg/kg THC 30 min prior to the session, the dose at which a single administration did not cause impairment of DMTS performance in vehicle-treated rats, significantly decreased the number of reinforcements in the test trial. In conclusion, the present study demonstrated that repeated THC administration impaired DMTS performance under the condition of 24 h after administration, and that behavioral sensitization to this impairment developed. Furthermore, the suppressive state of lever-pressing induced by repeated THC administration may be a useful animal model for amotivational syndrome in humans.

Menstrual cycle specific expression of epidermal growth factor receptors in human fallopian tube epithelium

We studied the expression of epidermal growth factor (EGF) receptor protein and messenger RNA (mRNA) in human fallopian tubes at three stages of the menstrual cycle: early follicular (n = 3), late follicular (n = 3) and luteal (n = 3). Immunohistochemical studies in the ampullary portion of the tubes showed that specific staining was localized to the epithelium and the vascular endothelium. Staining of the epithelium was intense at the late follicular and luteal stages, while it was weak at the early follicular stage. 125I-EGF binding study in the tubal plasma membranes revealed a class of high-affinity EGF receptors. Although dissociation constants were similar between the stages, numbers of binding sites at the late follicular and luteal stages were significantly (P < 0.01) greater than those at the early follicular stage. Western blotting showed that tubal plasma membranes contain M(r) 170,000 EGF receptor protein. The amounts were significantly (P < 0.01, n = 3) greater at the late follicular and luteal stages than those at the early follicular stage. Reverse transcription and polymerase chain reaction (RT-PCR) revealed that EGF receptor mRNA was expressed in all the 9 RNA samples (n = 3 for each stage) from the tubal ampullary portion. The amounts were significantly (P < 0.01, n = 3) greater at the late follicular and luteal stages than those at the early follicular stage (by a competitive PCR). Increase in the amounts of EGF receptor protein and mRNA occurred in association with an increase in serum oestradiol but not progesterone levels. Next we examined whether EGF receptor and its ligands (EGF and transforming growth factor alpha) are directly induced by oestrogen. We found that specific staining for EGF receptor and its ligands in the tubal epithelium was detected (by immunohistochemistry) in postmenopausal women with oestrogen replacement (n = 3), but not in subjects without oestrogen replacement (n = 3). These results suggested that EGF receptors in the human tubal epithelium are expressed in relation to specific stages of the menstrual cycle and that the expression may be induced by oestrogen.

Effects of vamicamide on urinary bladder functions in conscious dog and rat models of urinary frequency

PURPOSE

To investigate the usefulness of vamicamide, (+/-)-(2R*, 4R*)-4-dimethylamino-2-phenyl-2-(2-pyridyl)valeramide, as a novel drug for the treatment of urinary frequency and incontinence.

MATERIALS AND METHODS

Urinary frequency was evaluated in specially devised conscious dog and rat models by investigating the effects of the drug on urinary bladder function of these animals by cystometrography.

RESULTS

In the dog model with transected hypogastric nerves, the bladder volume at micturition (bladder capacity) was less than 50% that of the sham-operated dog, and in the rat model with bilateral lesioning of nuclei basalis, a part of the brain, by ibotenic acid injection, bladder capacity was about 50% that of the sham-operated rat. Other bladder functions in both models were unchanged. In the dog model, orally administered vamicamide at 0.32 and 1.0 mg./kg. significantly increased bladder capacity and did not change residual urine volume or micturition pressure. Oxybutynin 0.10 mg./kg., one of the most popular drugs for the treatment of urinary frequency and incontinence, or atropine 0.10 mg./kg. induced significant increases in bladder capacity similarly to vamicamide at 0.32 mg./kg. In the rat model, oral vamicamide 0.32 mg./kg. also significantly increased bladder capacity and did not change micturition pressure or threshold pressure. Again, oxybutynin 0.10 mg./kg. or atropine 0.32 mg./kg. had almost the same effects as vamicamide 0.32 mg./kg.

CONCLUSIONS

These findings suggest that vamicamide should be useful for the treatment of urinary frequency.

The mechanism of action of hepatic sympathetic nerves on ketone-body output from perfused rat liver. The effect of the interaction of noradrenaline with ATP on the release of beta-hydroxybutyrate

The regulatory mechanism of ketone-body output by the hepatic sympathetic nerves was studied in rat liver perfused in situ. Enrichment of the perfusion medium with 1 mM octanoate increased the basal ketone-body output from the liver up to 1.5 mumol.min-1.g liver-1. Under these conditions, electrical stimulation of the hepatic nerves (20 V, 20 Hz, 2 ms) decreased the output of both acetoacetate and beta-hydroxybutyrate, and was accompanied by an accumulation of beta-hydroxybutyrate in the liver. The effects of nerve stimulation were inhibited by the alpha 1-antagonist bunazosin (10 microM). However, noradrenaline, a typical sympathetic neurotransmitter, at a concentration of 1 microM decreased the output of acetoacetate but did not affect beta-hydroxybutyrate output. Prostaglandin F2 alpha at a concentration of 10 microM produced an effect similar to treatment with noradrenaline, without a decrease in beta-hydroxybutyrate output. ATP at 50 microM, however, decreased the output of both acetoacetate and beta-hydroxybutyrate and increased the tissue concentration of beta-hydroxybutyrate, mimicking the effect of nerve stimulation. Moreover, in the presence of 0.2 microM ATP, a concentration that produced neither metabolic nor hemodynamic changes, noradrenaline (1 microM) was shown to decrease the beta-hydroxybutyrate output. These results indicate the possible involvement of ATP in the action of hepatic sympathetic nerves on beta-hydroxybutyrate output from the liver, presumably through its interaction with noradrenaline.

Bile acids and microorganisms in the jejunal lumen after biliary reconstruction in dogs

BACKGROUND

This study evaluated the composition of various bile acids and microorganisms in the jejunal lumen after using different methods of biliary reconstruction.

STUDY DESIGN

A Billroth I biliary reconstruction, in which the biliary tract was directly anastomosed to the alimentary tract, was performed in 16 dogs, including eight with cholecystoduodenostomy (C-D group) and eight with cholecystojejunostomy (C-J group). A Billroth II reconstruction, involving a Rouxen-Y cholecystojejunostomy (R-Y group) in which bile flowed into the jejunal limb, was made in eight dogs. Jejunal fluid samples were used for microbial culture and bile acid assay by high-performance liquid chromatography.

RESULTS

The percentage of unconjugated bile acids in the R-Y group (9.96 +/- 2.17 percent) was significantly higher than that observed in the C-D group (0.11 +/- 0.05 percent), and that observed in the C-J group (1.05 +/- 0.72 percent) (p < 0.01). The detection rate of anaerobes was higher in the R-Y group than in the C-D and C-J groups.

CONCLUSIONS

This study suggests that due to an increase in unconjugated bile acids after the Billroth II biliary reconstruction the function of digestion and absorption is less well preserved than after the Billroth I method.

An ultrasound biomicroscopic study of filtering blebs after mitomycin C trabeculectomy

PURPOSES

To investigate the relation between filtering bleb function and ultrasound biomicroscopic images, and to establish a new classification system for filtering blebs according to these images.

METHODS

After trabeculectomy with mitomycin C, the filtering blebs of 117 eyes from 117 patients with various types of glaucoma were examined using ultrasound biomicroscopy. Four parameters of the images-intrableb reflectivity, visibility of the route under the scleral flap, formation of a cavernous fluid-filled space, and bleb height-were correlated with the level of intraocular pressure (IOP).

RESULTS

Reflectivity inside the bleb and visibility of a route under the scleral flap were highly associated with IOP control. Blebs were classified into four categories according to the four measured parameters: type L (low-reflective), type H (high-reflective), type E (encapsulated), and type F (flattened). Eyes with good IOP control had mainly type L blebs. Type E and type F blebs were seen mostly in eyes requiring additional medication.

CONCLUSION

The structure inside a filtering bleb is visible by ultrasound biomicroscopy, and bleb function is significantly associated with its ultrasound biomicroscopic image in eyes trabeculectomized with adjunctive mitomycin C.

Listeria monocytogenes can grow in macrophages without the aid of proteins induced by environmental stresses

Listeria monocytogenes is a facultative intracellular pathogen which is able to survive and grow within phagocytic cells. Some facultative intracellular bacteria have been shown to respond to the hostile environment within phagocytic cells by producing a set of stress proteins. Since L. monocytogenes has a mechanism for intracellular survival that is distinct from those of other bacteria, we studied the phenotypic response of the bacterium to phagocytosis by macrophages. After phagocytosis of L. monocytogenes EGD by J774-1 macrophage cells, the microorganism rapidly increased in numbers about 20-fold during an incubation period of 5 h. In this phase of phagocytosis, the selective induction of 32 proteins was observed by two-dimensional gel electrophoresis. The responses to the environmental stresses of heat and hydrogen peroxide were also studied, and it was found that 14 heat shock proteins and 13 oxidative stress proteins were induced. Five of the induced proteins were common to both heat and oxidative stresses. By amino acid sequencing analysis, homologs of DnaK and GroEL were confirmed among the heat shock proteins. A comparison of the autoradiograms of the two-dimensional gels revealed that none of these stress proteins were among the proteins induced by L. monocytogenes within the macrophages. This behavior is entirely different from that shown by other facultative intracellular pathogens. Stress proteins known to be induced by environmental stresses were absent in intracellularly grown L. monocytogenes in the present study. This absence could be due to the mechanism by which the microorganisms rapidly escape from this stressful environment at a very early phase of phagocytosis.

[Dobutamine stress echocardiography in the diagnosis of myocardial ischemia in patients with implanted pacemakers: report of two cases]

Dobutamine stress echocardiography was used in the diagnosis of myocardial ischemia in patients with implanted VVI pacemakers. A 69-year-old woman received a pacemaker for Mobitz II type AV block in October 1992. She had suffered from chest pain during effort since January 1993 and underwent dobutamine stress echocardiography in April 1993. Although the electrocardiogram failed to identify ischemia because of the pacemaker rhythm, ischemia of the anterior wall was revealed as a worsening of the wall motion on the echocardiogram. The coronary angiogram showed 99% stenosis of the left descending artery. A direct coronary atherectomy was performed on the lesion. A 68-year-old man received a pacemaker for sick sinus syndrome in August 1993. He had suffered from chest oppression during effort since May 1992 and underwent dobutamine stress echocardiography in October 1993. Spontaneous rhythm appeared with dobutamine infusion, but the electrocardiogram could not demonstrate ischemia because of incomparability with the rhythm at rest. Echocardiography detected a new wall motion abnormality of the inferior wall caused by dobutamine. The coronary angiogram showed 90% stenosis of the right coronary artery. PTCA was performed on the lesion. Dobutamine stress echocardiography is useful for the diagnosis of myocardial ischemia in patients with implanted pacemakers.

Three novel mutations of thyroid hormone receptor beta gene in unrelated patients with resistance to thyroid hormone: two mutations of the same codon (H435L and H435Q) produce separate subtypes of resistance

We report three novel mutations of the thyroid hormone receptor beta (TR beta) gene in three unrelated Japanese patients with resistance to thyroid hormone (RTH). Patients A and B exhibited generalized resistance phenotype, while patient C displayed more pituitary-selective unresponsiveness. Direct sequencing of TR beta gene exon 10 disclosed novel point mutations in all three patients. A Phe to Ile (TTC-->ATC) substitution at codon 451, a His to Leu (CAT-->CTT) substitution at codon 435, and a His to Gln (CAT-->CAA) substitution at codon 435 were identified in patients A, B, and C, respectively. Sequencing of TR beta gene exons 5-9 as well as TR alpha gene exons 4-9 failed to detect any additional mutations. All three patients were heterozygous for respective mutations. The unaffected parents of patients A and B, having normal thyroid function, possessed no mutations of TR beta gene exon 10, indicating that the F451I and H435L mutations occurred de novo. The F451I mutation is located near the most frequent mutation site in the ligand 2 subdomain. The identical codon mutations H435L and H435Q, which lie at the extreme carboxyl-terminus of the dimerization subdomain near the 9th heptad, were found in clinically different subtypes of RTH: patient B with generalized resistance and patient C with pituitary-selective resistance, respectively. The mutations broaden the growing catalogue of the TR beta gene mutations that could cause different phenotypes, despite the defects at the same codon.

Plasticity of central motor and sensory pathways in a case of unilateral extensive cortical dysplasia: investigation of magnetic resonance imaging, transcranial magnetic stimulation, and short-latency somatosensory evoked potentials

We studied a 13-year-old girl with unilateral extensive cortical dysplasia who had mild hemiparesis with mirror movement and no sensory deficit. Transcranial focal magnetic stimulation (TMS) to the unaffected hemisphere elicited bilateral motor evoked potentials (MEPs) of the abductor pollicis brevis muscle (APB) with similar latency and amplitude. The scalp positions where the MEP amplitudes were highest were at the same site in the unaffected hemisphere for both APBs. TMS to the affected heimsphere showed no MEP for either APB. These data indicated that the APB response of the paretic side originated from the same motor cortex as for the contralateral APB, probably due to axonal sprouting. In the study of short-latency somatosensory evoked potentials, the cortical representation point of the paretic hand sensation was in the ipsilateral unaffected hemisphere; this point was located anterior to the cortical representation point of the contralateral hand sensation. We conclude that reorganization of primary motor and sensory cortex occurs when there is unilateral extensive brain damage in early gestation.

Mutagenicity of soy sauce treated with nitrite in the presence of ethanol or alcoholic beverages

The mutagenicity induced by soy sauce after reaction with 50 mM nitrite at pH 3, 37 degrees C, for 60 min in the presence of 1.25-10% ethanol was reduced in proportion to the ethanol concentration. The mutagenicity of soy sauce treated with nitrite was also reduced in the presence of commercial alcoholic beverages, Japanese sake, wine, 'shochu', whiskey and brandy, but not beer, in proportion to the concentration. The mutagenicity of nitrite-treated tyramine, which is a major precursor of a mutagen in soy sauce treated with nitrite, was strongly reduced in the presence of ethanol, n-propanol or isopropanol and more strongly reduced in the presence of methanol, but was increased twofold in the presence of the sugars glucose or sucrose. The reduction of the mutagenicity of nitrite-treated tyramine required simultaneous treatment of tyramine with ethanol and nitrite. The mutagenicity of tyramine treated with nitrite was clearly reduced in the presence of shochu and whiskey, similarly to ethanol. Analysis by high-performance liquid chromatography revealed that the reduction of the mutagenicity of nitrite-treated tyramine in the presence of ethanol resulted from the reduced production of mutagenic 3-diazotyramine from tyramine.

Tobacco mitotic cyclins: cloning, characterization, gene expression and functional assay

Three cyclin cDNA clones (Ntcyc25, Ntcyc27, Ntcyc29) have been isolated from tobacco (Nicotiana tabacum) using the PCR cloning method. The encoded Ntcyc cyclins were highly homologous to mitotic cyclins. In synchronized tobacco suspension cultured cells, the mRNA levels of Ntcyc25 and Ntcyc27 were detectable through S, G2 and M phases, while the Ntcyc29 mRNA was detected from G2 to M phase. These expression patterns classified the Ntcyc25 and Ntcyc27 into A-type cyclin and Ntcyc29 into B-type cyclin. The three genes were expressed in growing tobacco cultured cells but ceased to be expressed when cells entered the stationary phase, indicating that the expression of these cyclin genes was well correlated with cell growth. The N-terminal truncated Ntcyc25 and Ntcyc29 cDNAs were able to rescue G1 cyclin mutant of Saccharomyces cerevisiae, while the full-length of Ntcyc27 protein could also partially perform G1 cyclin functions.

A cardiotonic steroid bufalin-like factor in human plasma induces leukemia cell differentiation

A Na+,K(+)-ATPase inhibitor, bufalin, has been shown previously to induce leukemia cell differentiation. The presence of a circulating Na+,K(+)-ATPase inhibitor has been proposed in mammals. The aim of this study was to explore an endogenous bufalin-like factor that induces leukemia cell differentiation. We found a fraction, designated as fraction A, obtained from human plasma extract that inhibits the growth of several human-derived leukemia cell lines. The effect of the fraction was retained after protease digestion or heat treatment. Murine leukemia cells and ouabain-resistant cells, which are insensitive to bufalin, appeared to be refractory to fraction A in terms of growth inhibition. Fraction A also induced functional and morphological maturation in THP-1 cells. Fraction A was recognized by anti-bufalin anti-serum and inhibited 3H-bufalin binding to K562 cells. These findings suggest that fraction A shows a similar behavior to that of bufalin on leukemia cells by inhibiting Na+,K(+)-ATPase. We propose that an endogenous Na+,K(+)-ATPase inhibitor in human plasma may play a role in cell differentiation.

Juvenile hyaline fibromatosis. Case report with five years' follow-up

Juvenile hyaline fibromatosis (JHF) is a rare hereditary disorder named by Drescher et al. in 1969. As recently as 1985, only 30 cases had been reported worldwide. We report the case of a 9-year-old girl who was diagnosed with JHF at age 3 and has been closely followed since. She initially had slowly growing multiple soft tumors over her entire body as well as hypertrophic gingiva and mild bone deformities. She was originally misdiagnosed with infantile myofibromatosis at age 3. However, at age 6, because of the light and electron microscopic findings of the tumors, she was diagnosed as having JHF. Currently, at age 9, she has nodular lesions developing over her body as well as bone changes that are progressing with no evidence of regression.

[A case of itraconazole-induced hypokalemia with pulmonary aspergilloma]

A case of itraconazole-induced hypokalemia with pulmonary aspergilloma is reported. A 68-year-old female who had been followed for rheumatoid arthritis, gastric ulcer and pulmonary aspergilloma was admitted to our hospital because of a cough, low grade fever and hemosputum. She was treated with itraconazole (100 mg/day) for pulmonary aspergilloma of the left upper lobe. Fifty seven days after starting the treatment, her serum potassium was 2.33 mEq/l. Since there was no history of diarrhea, vomiting or abuse of drugs known to cause hypokalemia, itraconazole- induced hypokalemia was suspected. Thirty one days after the discontinuation of the treatment with itraconazole, her serum potassium increased to 3.57 mEq/l without potassium supplement. The lymphocyte stimulation test for itraconazole was negative. This case suggests that serum potassium should be monitored in the patients treated with itraconazole.

Decreased expression of the very low density lipoprotein receptor mRNA in the cardiac ventricle of spontaneously hypertensive rats

1. To elucidate the functional implication of very low density lipoprotein (VLDL) receptor, we studied the gene expression of VLDL receptor in rats. The VLDL receptor mRNA was highly expressed in the cardiac ventricle and skeletal muscle. Intermediate amounts of VLDL receptor mRNA were detected in adipose tissue, adrenal gland, brain and lung. Thus the tissue distribution of VLDL receptor mRNA in rats was similar to that reported previously in rabbits. 2. We studied the gene expression of the VLDL receptor in the heart of stroke-prone spontaneously hypertensive rats (SHRSP), an animal model for hypertension-induced cardiac hypertrophy. RNase protection assay showed that the level of ventricular VLDL receptor mRNA was already decreased to one half when hypertension was not fully developed, and further diminished to one fifth when cardiac hypertrophy was established. 3. It is reported that energy utilization in SHRSP hypertrophied myocardium is impaired. Our results suggest that inactive fatty acid metabolism in the ventricle of SHRSP is related to the lowered expression of the VLDL receptor which is postulated as a gate for triglyceride-rich lipoprotein particle.

General pharmacology of the new antimuscarinic compound vamicamide

The general pharmacology of the new antimuscarinic compound vamicamide (FK176, (+/-)-(2R*, 4R*)-4-dimethylamino-2-phenyl-2- (2-pyridyl)valeramide, CAS 132373-81-0) was investigated using mice, rats, guinea pigs and dogs, and was in part compared with that of oxybutynin hydrochloride (oxybutynin, CAS 1508-65-2), a similar type of compound. 1. Vamicamide induced mydriasis after oral administration (p.o.) of 10 mg/kg or more, and suppressed defecation after 32 mg/kg or more in the general activity and behavior test with rats. 2. Vamicamide increased spontaneous locomotor activity in mice at 32 mg/kg or more (p.o.) and suppressed tonic convulsions in the electroconvulsive shock test with mice at 100 mg/kg. The compound at 10-100 mg/kg (p.o) did not show significant effects on hexobarbital-induced anesthesia, pentetrazole-induced convulsions and pain response by Haffner's method in mice, body temperature in rats or spontaneous electroencephalogram (EEG) in rabbits. On the other hand, oxybutynin increased high voltage slow waves of spontaneous EEG in rabbits at 32 mg/kg or more (p.o.) and prolonged hexobarbital-induced anesthesia time in mice at 100 mg/kg. 3. Vamicamide in concentrations of 0.001-1% (1 x 10(-4)-1 x 10(-1) g/ml) did not show local anesthetic effect on the corneal reflex test with guinea pigs. The compound in concentrations of 1 x 10(-5) and 1 x 10(-4) g/ml also had no effects on contractions of the isolated rat diaphragm caused by electrical stimulation of the phrenic nerve. 4. Vamicamide on the highest concentration of 1 x 10(-4) g/ml augmented contractions of isolated rat vas deferens induced by noradrenaline, resting tonus of the isolated guinea pig trachea, and contractile force of spontaneous movement of the isolated rat nonpregnant uterus. The compound at 1 x 10(-4) g/ml had no significant effects on KCl-induced contraction of the isolated rat thoracic aorta. 5. Vamicamide elevated systemic blood pressure and increased heart rate but had no effects on respiratory movement of the chest in conscious dogs at an oral dose of 10 mg/kg or more. The compound in intraduodenal (i.d.) doses of 3.2-32 mg/kg had no effect on femoral blood flow in anesthetized dogs. Vamicamide augmented contractile force and reduced beating rate in isolated guinea pig atria at a concentration of 1 x 10(-5) g/ml or more. Oxybutynin increased heart rate at 3.2 mg/kg or more (p.o.), and elevated blood pressure at 10 mg/kg or more in conscious dogs. 6. Vamicamide slightly inhibited small intestinal transit in rats at 3.2 mg/kg or more (p.o.). On the other hand, oxybutynin inhibited the transit in rats at 0.32 mg/kg or more. 7. Vamicamide had no effects on urine volume, urinary excretion of Na+, K+, Cl- and uric acid in rats at an oral dose of 100 mg/kg or less, or on renal function in anesthetized dogs at an i.d. dose of 32 mg/kg or less. 8. Vamicamide showed no effects on bleeding time in mice at 100 mg/kg p.o., rabbit platelet aggregation induced by adenosine diphosphate or collagen at 1 x 10(-4) g/ml, blood coagulation systems in rats at 100 mg/kg p.o., or hemolysis on rabbit blood at a concentration of 1% or less. Thus, vamicamide in the doses used inhibited gastrointestinal motility, and caused mydriasis as effects possibly due to its anticholinergic action. The compound had no effects on the central nervous system, cardiovascular system, renal functions, or blood system.

Chlorpropamide-induced ADH release, hyponatremia and central pontine myelinolysis in diabetes mellitus

Chlorpropamide (CPM) has been reported to produce impaired water excretion due to the enhancement of renal vasopressin (ADH) action and/or due to centrally enhanced ADH release, but it is still unknown whether CPM gives rise to ADH release with a subsequent hyponatremia in diabetes mellitus (DM), which, in turn, causes an impairment of the central nervous system. In 3 patients with DM, who developed hyponatremia during the treatment with CPM, an acute water load (WL) was carried out in the presence and absence of the drug, and plasma ADH was determined with plasma and urine osmolalities. Moreover, in 2 cases, MRI scans of the brain were taken. In all the patients, acute WL tests failed to suppress completely ADH release in response to changes in plasma osmolality in the presence of CPM, which, in turn, resulted in the impaired water excretion. In the absence of CPM, an acute WL normally suppressed plasma ADH leading to the diuresis. MRI scans illustrated the presence of central pontine myelinolysis. It is likely that CPM might stimulate ADH release in DM with a subsequent hyponatremia and brain damages.

Single unit responses of the amygdala after conditioned taste aversion in conscious rats

Amygdalar neuronal responses to sodium saccharin used as the conditioned stimulus (CS) and to other taste stimuli including sucrose, NaCl, HCl and quinine hydrochloride were recorded before and after the acquisition of conditioned taste aversion (CTA) in freely behaving rats. Of 73 units recorded from the basolateral nucleus of the amygdala (BLA), 17 (23%) and 1 (1%) exhibited facilitatory and inhibitory responses, respectively, to both the CS and sucrose after aversive conditioning to the CS. On the other hand, 3 (5%) and 11 (17%) of 64 units recorded from the central nucleus of the amygdala (Ce) exhibited facilitatory and inhibitory responses, respectively. The responsiveness of these BLA and Ce units to other taste stimuli did not change significantly. These findings that the facilitatory effect was dominant in the BLA, while the inhibitory effect was more frequent in the Ce suggest that the BLA and Ce are differentially involved in CTA.

Molecular cloning of cDNA encoding the Xenopus homolog of mammalian RelB

We have molecularly cloned cDNA encoding a new Rel-related protein in Xenopus laevis. Nucleotide sequencing revealed that the product is most homologous to mammalian RelB in its N-terminal region. Furthermore, the putative protein kinase A phosphorylation site (RRPS), found in most of the Rel family proteins, but replaced by QRLT in mammalian RelB, is replaced by QRIT, indicating that our cDNA most likely encodes the Xenopus homolog of mammalian RelB (XrelB). As in the case of mouse RelB, XrelB alone does not bind to DNA efficiently, while XrelB/human p50 heterodimers bind to kappa B sites and activate transcription. XrelB transcripts are present at all stages of oocyte maturation and in adult tissues examined. However, in staged embryos XrelB is undetectable from neurula to stage 28 and resumes expression at stage 47, while Xrel1/XrelA, the Xenopus homolog of p65, has been demonstrated to be expressed throughout embryogenesis. These results raise the possibility that XrelB and Xrel1/XrelA play different roles in the development of X.laevis.

Structure, organization, and transcription units of the human alpha-platelet-derived growth factor receptor gene, PDGFRA

Isolation and characterization of genomic clones encoding human alpha-platelet derived growth factor receptor (HGMW-approved symbol PDGFRA) revealed that the gene spans approximately 65 kb and contains 23 exons. The 5'-untranslated region of the mRNA is encoded by exon 1, and a large intron of 23 kb separates exon 2 encoding the translation initiator codon AUG and the signal sequence. The locations of exon/intron boundaries in the extracellular immunoglobulin-like domains, the transmembrane domain, the two cytoplasmic tyrosine kinase domains, and the kinase insertion domain are very similar to those in c-kit and macrophage colony stimulating factor-1 receptor genes. The transcription start site was mapped to a position 393 bp upstream of the AUG translocation initiator codon by S1 mapping and primer extension analysis. The 5'-flanking region of the gene lacks a typical TATA box but contains a typical CCAAT box and GATA motifs. This region also contains potential sites for AP-1, AP-2, Oct-1, Oct-2, and Sp1. The 5'-flanking region of the gene was fused to the luciferase reporter gene, and transcription units of the gene were determined.

Mesodermal defect in late phase of gastrulation by a targeted mutation of focal adhesion kinase, FAK

FAK is a unique non-receptor protein tyrosine kinase that was found in cellular focal adhesions. An increasing number of in vitro observations has suggested that FAK mediates signaling through integrins brought about by interactions with extracellular matrix (ECM). It is highly tyrosine-phosphorylated in v-src-transformed cells and during embryogenesis. To clarify the function of FAK in cell-ECM interactions, embryonic phenotype of its mutant was analysed. FAK-deficient embryos could implant and initiate gastrulation normally, but showed abnormalities in subsequent development. The abnormalities were characterized as a general deficiency in mesoderm, and the phenotype was quite similar to that caused by fibronectin-deficiency. The results suggest that FAK mediates fibronectin-integrin interactions uniquely at this stage of development, thereby playing an essential role in development of mesodermal cell lineages.

Cupric ion blocks NF kappa B activation through inhibiting the signal-induced phosphorylation of I kappa B alpha

A transcription factor NF kappa B, which regulates expression of various cellular genes involved in immune responses and viral genes including HIV, is sequestered in the cytoplasm as a complex with an inhibitory protein I kappa B. Various extracellular signals induce phosphorylation and rapid degradation of I kappa B alpha to release NF kappa B. Cu2+ was found to inhibit the activation of NF kappa B induced by TNF-alpha, TPA, or H2O2. Deoxycholate treatment of the cytoplasmic extract prepared from cells stimulated by TNF-alpha in the presence of Cu2+ resulted in the release of NF kappa B from I kappa B alpha, indicating that Cu2+ interferes with the dissociation of the NF kappa B-I kappa B complex. Neither phosphorylation nor degradation of I kappa B alpha was observed upon TNF-alpha stimulation in the presence of Cu2+. These results indicate that Cu2+ inhibits the release of NF kappa B by blockade of a signal leading to the phosphorylation of I kappa B alpha.