Application of dynamic laser scattering to the quality control of injectable drugs: polymer formation in ampicillin solution

OBJECTIVE

To assess the usefulness of dynamic laser scattering for monitoring the stability of ampicillin after reconstitution from commercially available vials with respect to the polymer formation and potency.

METHODS

Polymer formation and the remaining potency of the reconstituted ampicillin solution were estimated using dynamic laser scattering and high-performance liquid chromatography.

RESULTS

The laser light-scattering submicron particle analyser was sufficiently sensitive for detecting both monomer and polymer aggregates with the average diameter of 1.1 +/- 0.2 and 7.3 +/- 1.7 nm, respectively, in the ampicillin solution. Polymer formation was dependent on both the storage temperature and the storage period, but it was detected, even when no precipitates were visible and when loss of potency was less than 10% of the initial value following storage at 4 or -15 degrees C.

CONCLUSION

Submicron particle analysis using scanning electron microscopy, when used in combination with high-performance liquid chromatography, provides a useful method for studying polymer formation in antibiotic solutions and for the quality control of antibiotic injections during storage.

The protein tyrosine phosphatase TCPTP suppresses the tumorigenicity of glioblastoma cells expressing a mutant epidermal growth factor receptor

Glioblastoma multiforme (GBM) is the most aggressive type of glioma and GBMs frequently contain amplifications or mutations of the EGFR gene. The most common mutation results in a truncated receptor tyrosine kinase known as Delta EGFR that signals constitutively and promotes GBM growth. Here, we report that the 45-kDa variant of the protein tyrosine phosphatase TCPTP (TC45) can recognize Delta EGFR as a cellular substrate. TC45 dephosphorylated Delta EGFR in U87MG glioblastoma cells and inhibited mitogen-activated protein kinase ERK2 and phosphatidylinositol 3-kinase signaling. In contrast, the substrate-trapping TC45-D182A mutant, which is capable of forming stable complexes with TC45 substrates, suppressed the activation of ERK2 but not phosphatidylinositol 3-kinase. TC45 inhibited the proliferation and anchorage-independent growth of Delta EGFR cells but TC45-D182A only inhibited cellular proliferation. Notably, neither TC45 nor TC45-D182A inhibited the proliferation of U87MG cells that did not express Delta EGFR. Delta EGFR activity was necessary for the activation of ERK2, and pharmacological inhibition of ERK2 inhibited the proliferation of Delta EGFR-expressing U87MG cells. Expression of either TC45 or TC45-D182A also suppressed the growth of Delta EGFR-expressing U87MG cells in vivo and prolonged the survival of mice implanted intracerebrally with these tumor cells. These results indicate that TC45 can inhibit the Delta EGFR-mediated activation of ERK2 and suppress the tumorigenicity of Delta EGFR-expressing glioblastoma cells in vivo.

Characteristics of learning and memory impairment induced by delta9-tetrahydrocannabinol in rats

We investigated the characteristics of delta9-tetrahydrocannabinol (THC)-induced impairment of learning and memory using an 8-arm radial maze task, a water maze, a visual discrimination task with 2 figures and a passive avoidance test in rats. THC (6 mg/kg, i.p.) impaired spatial memory in the standard task of the 8-arm radial maze. THC (4-6 mg/kg, i.p.) selectively impaired working memory in a reference and working memory task of the 8-arm radial maze. Even at a dose of 10 mg/kg, THC did not impair spatial memory in the water maze. In addition, THC at a dose of 6 mg/kg, which had inhibitory effects in the 8-arm radial maze, did not affect performance in the visual discrimination task. These results indicate that at low doses (2-6 mg/kg), THC may not produce visual function abnormalities. THC impaired retrieval (6 mg/kg, i.p.) as well as acquisition (10 mg/kg, i.p.) in the passive avoidance test. The consolidation process was also impaired by i.c.v. injection (100 microg), but not i.p. injection (6-10 mg/kg) of THC. These results suggest that THC-induced impairment of spatial memory is based on the selective impairment of working memory through its effects on acquisition and retrieval processes.

Role of dopaminergic system in core part of nucleus accumbens in hyperlocomotion and rearing induced by MK-801 in rats: a behavioral and in vivo microdialysis study

We investigated modification of the MK-801 effect on motor activity and extracellular amines concentration by 6-hydroxydopamine (6-OHDA)-induced lesion of core nucleus accumbens (cACC) of rats. In vivo microdialysis-HPLC showed that the concentrations (fmol/microl) of dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and serotonin were 0.738 +/- 0.135, 155.34 +/- 41.01 and 0.334 +/- 0.024, respectively, in the cACC of intact rats. The DOPAC/DA ratio was 264.24 +/- 94.01. Unilateral lesion of the cACC with 6-OHDA (8 microg/microl) substantially reduced DA (-93%) and DOPAC (-97%) in desipramine (30 mg/kg, i.p.)-pretreated rats (6-OHDA+DMI rats) as compared to the 65% reduction rate of both amines in saline-pretreated rats (6-OHDA+saline rats). Moreover, DOPAC was reduced by 72% in 6-OHDA+DMI rats. MK-801 increased DOPAC (426-467%) and DOPAC/DA ratio (180-230%) in intact rats. On the other hand, MK-801 increased DA by 154% and 505% in 6-OHDA+saline and 6-OHDA+DMI rats, respectively. 6-OHDA reduced the effect of MK-801 on DOPAC and DOPAC/DA ratio. In the behavioral studies, MK-801 (0.01-0.3 mg/kg, i.p.) increased locomotor activity and rearing of intact rats. Bilateral 6-OHDA+DMI lesion of the cACC caused greater reduction in the effect of MK-801 (0.1 mg/kg) than that of the shell nucleus accumbens. These results suggest that increased extracellular DOPAC concentration (but not DA) and DOPAC/DA ratio in the cACC plays an important role in MK-801-hyperactivity.

Hypothermic action of exogenously administered melatonin is dose-dependent in humans

The pineal hormone melatonin (MLT) is closely related to sleep initiation and maintenance in humans, and is now used as a potent therapeutic tool for some circadian rhythm sleep disorders. Acute and transient hypothermia induced by exogenously administered MLT (ex-MLT) may play a critical role in the circadian phase shifting and hypnogenic actions. Six healthy young male volunteers (mean age, 22.5 y; age range, 19-24 y), whose endogenous MLT secretion rhythms were previously assessed, took either 0.5 mg, 3 mg, or 9 mg of ex-MLT or a placebo at 0930 h (the average sleep onset time was 0000 h) on a randomized, single-blind, crossover basis. In comparison with placebo, ex-MLT significantly suppressed core body temperature at the 3-mg and 9-mg doses and slightly suppressed core body temperature at the 0.5-mg dose. There was significant positive correlation between the magnitude of core body temperature suppression and the area under the MLT concentration curve as well as the peak MLT concentration after ex-MLT administration. Our study showed that clinical doses of ex-MLT induce hypothermia in a dose-dependent manner. Results suggest that the therapeutic effect of larger doses of ex-MLT should be tested on patients who benefit little from typically lower clinical doses of ex-MLT.

Total sleep deprivation induces an acute and transient increase in NK cell activity in healthy young volunteers

STUDY OBJECTIVES

To investigate the effects of one night's total sleep deprivation (TSD) on NK cell activity, with rigorous control of circadian phase of sampling points as well as physical exercise level in association with sleep deprivation.

DESIGN

The mean sleep onset time of each subject before starting the study was defined as his 0000 h. This study was composed of a Sleep-Sleep session (sleep times, 00:00 h - 08:00 h and 24:00 h - 32:00 h) and a Sleep-Wake session (sleep time, 00:00 h - 08:00 h) with TSD (24:00 h - 32:00 h) placed in a cross-over design with 2-week interval between each session. In each session, the subjects were rested in the supine position under dim light from - 06:00 h to 36:00 h (for 42 hours).

SETTING

University-based sleep and chronobiology laboratory

PARTICIPANTS

10 healthy adult men (mean age, 20.9 y; age range, 19-23 y)

INTERVENTIONS

NA.

MEASUREMENTS AND RESULTS

NK cell activity was measured every 4 hours from 12:00 h. NK cell activity during TSD (at 28:00 h) has been revealed to significantly increase (p=0.01) compared with the corresponding value in the Sleep-Sleep session. This effect was weaker at their usual waking time 32:00 h (p=0.07), and disappeared until 36:00 h (4 hours after awakening). The circadian rhythm phases (dim light melatonin onset time) were coincident between the 2 sessions.

CONCLUSIONS

The present findings suggest that one night TSD induces an acute and transient increase in NK cell activity that is not influenced by the effects of circadian rhythm or the amount of physical exercise undertaken during TSD.

Environmentally benign formation of polymeric microspheres by rapid expansion of supercritical carbon dioxide solution with a nonsolvent

A novel method is reported for forming polymer microparticles, which reduce atmospheric emissions of environmentally harmful volatile organic compounds such as toluene and xylene used as paint solvent in paint industry. The polymer microparticles have formed through rapid expansion from supercritical solution with a nonsolvent (RESS-N). Solubilization of poly(styrene)-b-(poly(methyl methacrylate)-co-poly (glycidyl methacrylate)) copolymer(PS-b-(PMMA-co-PGMA), MW = 5000, PS/PMMA/PGMA = 2/5/3), poly(ethylene glycol) (PEG, M. W = 4000), bisphenol A type epoxy resin (EP, MW = 3000), poly(methyl methacrylate) (PMMA; MW = 15000, 75000, 120000), and poly(oxyalkylene) alkylphenyl ether (MW = 4000) in carbon dioxide (CO2) was achieved with the use of small alcohols as cosolvents. The solubility of the PS-b-(PMMA-co-PGMA) is extremely low in either CO2 or ethanol but becomes 20 wt % in a mixture of the two. Because ethanol is a nonsolvent for the polymer, it can be used as a cosolvent in rapid expansion from supercritical solution to produce 1-3 microm particles that do not agglomerate. Obtained polymer particles by RESS-N were applied as powder coatings. The resulting coatings have a smooth and coherent film. The particle size distribution of microspheres was controlled by changing the polymer concentration, preexpansion pressure, temperature, and injection distance. The feed compositions were more effective than the other factors in controlling the particle size. The polymeric microparticles formed by RESS-N method can be utilized to make the thin coating film without anytoxic organic solvents and/or surfactants.

Effects of endothelin on adrenomedullin secretion and expression of adrenomedullin receptors in rat cardiomyocytes

Both endothelin (ET) and adrenomedullin (AM), produced by cardiac myocytes, are thought to be locally-acting hormones in the heart. Recently, calcitonin receptor-like receptor (CRLR) and receptor activity modifying proteins (RAMPs) have been shown to function together to serve as AM receptors stimulating cAMP production. In the present study, we examined the effects of ET on AM secretion, intracellular cAMP response to AM, and gene expressions of CRLR and RAMPs in cultured cardiac myocytes. Synthetic ET-1 dose-dependently increased AM secretion from the cardiomyocytes. AM increased the intracellular cAMP level in a dose-dependent manner and the cAMP accumulation by AM was significantly amplified by 24 h preincubation with ET-1. 10 nmol/L ET-1 significantly increased the CRLR mRNA level without any effect on RAMP1 mRNA. 1 micromol/L ET-1 significantly reduced the RAMP2 mRNA level, but ET-1 dose-dependently increased the RAMP3 mRNA level in the cardiac myocytes. These findings suggest that ET-1 not only stimulates AM secretion, but also modulates intracellular cAMP responses to AM probably by altering the expressions of CRLR and RAMPs in rat cardiomyocytes.

Ameliorative effect of vasopressin-(4-9) through vasopressin V(1A) receptor on scopolamine-induced impairments of rat spatial memory in the eight-arm radial maze

In order to clarify the mechanism by which pGlu-Asn-Cys(Cys)-Pro-Arg-Gly-NH(2) (vasopressin-(4-9)), a major metabolite C-terminal fragment of [Arg(8)]-vasopressin (vasopressin-(1-9)), improves learning and memory, we used several different drugs such as an acetylcholine receptor antagonist, a Ca(2+)/calmodulin-dependent protein kinase II inhibitor, vasopressin receptor antagonists and L-type Ca(2+) channel blocker to disrupt spatial memory in rats. Moreover, we examined the effect of vasopressin-(4-9) on acetylcholine release in the ventral hippocampus using microdialysis. Vasopressin-(4-9) (10 fg/brain, i.c.v.) improved the impairment of spatial memory in the eight-arm radial maze induced by scopolamine, pirenzepine and Ca(2+)/calmodulin -dependent protein kinase II inhibitor. Pirenzepine, a vasopressin V(1A) receptor antagonist, and L-type Ca(2+) channel blocker, but not a vasopressin V(2) receptor antagonist, suppressed the effects of vasopressin-(4-9) on scopolamine-induced impairment of spatial memory. Moreover, vasopressin-(4-9) did not affect acetylcholine release in the ventral hippocampus of intact rats or of scopolamine-treated rats as assessed by microdialysis. These results suggest that vasopressin-(4-9) activates vasopressin V(1A) receptors on the postsynaptic membrane of cholinergic neurons, and induces a transient influx of intracellular Ca(2+) through L-type Ca(2+) channels to interact with muscarinic M(1) receptors. The activation of these processes by vasopressin-(4-9) is critically involved in the positive effect of vasopressin-(4-9) on scopolamine-induced impairment of spatial memory.

Human glioblastoma xenografts overexpressing a tumor-specific mutant epidermal growth factor receptor sensitized to cisplatin by the AG1478 tyrosine kinase inhibitor

OBJECT

Activation of signaling by the epidermal growth factor receptor (EGFR) through gene amplification or rearrangement is common in human malignancy, especially in a large fraction of de novo glioblastomas multiforme (GBMs). The most common mutant EGFR, (AEGFR, also known as de2-7 EGFR and EGFRvIII) lacks a portion of the extracellular domain, enhances tumorigenicity in vivo, and causes resistance to the chemotherapeutic drug cisplatin (CDDP). This resistance is due to the suppression of CDDP-induced apoptosis by the constitutively active tyrosine kinase activity of the receptor. The authors have investigated whether inhibition of AEGFR signaling by the tyrosine kinase inhibitor, tyrphostin AG1478, could sensitize tumor xenografts to CDDP and, thereby, enhance its therapeutic efficacy in animals.

METHODS

Nude mice were inoculated either subcutaneously or intracerebrally with human GBM cells expressing AEGFR and were then systemically treated with CDDP and/or AG1478. Tumor volumes were monitored and tumor sections were analyzed by using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assays or MIB-1 staining. Expression of AEGFR, but not wild-type EGFR, conferred CDDP resistance to the cells in vivo. Inhibition of receptor signaling by the EGFR-specific tyrosine kinase inhibitor, AG1478. sensitized the xenografts to the cytotoxic effects of CDDP. This combined CDDP/AG1478 treatment significantly suppressed growth of subcutaneous xenografts in nude mice in a synergistic manner (p < 0.01 compared with vehicle control) without causing generalized toxicity, whereas treatments with CDDP or AG1478 alone were ineffective. The synergistic growth suppression by the CDDP/AG1478 combination was not observed in xenografts overexpressing wild-type EGFR or kinase-deficient AEGFR. The combined CDDP/ AG1478 treatment induced tumor growth suppression, which correlated with increased apoptosis and reduced proliferation. This treatment also extended the life span of mice bearing intracerebral xenografts (p < 0.01 compared with controls).

CONCLUSIONS

The results of this study may provide the basis for the development of a novel and safe therapeutic strategy for the very aggressive AEGFR-expressing GBM.

Treatment modalities for oral verrucous carcinomas and their outcomes: contribution of radiotherapy and chemotherapy

BACKGROUND

This clinical study focused, firstly, on the results of treatment and, secondly, on the anaplastic transformation, of oral verrucous carcinomas (OVCs) diagnosed and treated from 1981 to 1997 at the Department of Oral and Maxillofacial Surgery at Shimane Medical University Hospital.

METHODS

We analyzed the treatment modalities and outcomes for 15 patients with OVC.

RESULTS

Excluding the results for 4 palliatively treated patients, the disease-free survival rates of the patients after the initial treatments, were 82% at 5 years and 66% at 10 years; for all 15 patients, these rates were 57% and 46%, respectively. Surgery alone and surgery combined with other treatments (such as radiotherapy and chemotherapy) appeared to yield disease-free survival rates to those achieved superior with other treatments whether single or combined; (78% vs 33% for 5-year disease-free survival; 52% vs 33% for 10-year disease-free survival); however, the difference was not significant (P = 0.47). Well differentiated squamous cell carcinomas (W-SCCs) (n = 5) as well as spindle cell carcinoma (n = 1) were found in subsequent operative or biopsy specimens.

CONCLUSION

Surgery was the most reliable treatment method for OVC; however, radiotherapy combined with chemotherapy was the next most preferable treatment when surgery was not undertaken. We also found that highly malignant transformation (anaplastic transformation) occasionally occurred during treatments for OVC.

Growth suppression of intracranial xenografted glioblastomas overexpressing mutant epidermal growth factor receptors by systemic administration of monoclonal antibody (mAb) 806, a novel monoclonal antibody directed to the receptor

A mutant epidermal growth factor receptor (variously called DeltaEGFR, de2-7 EGFR, or EGFRvIII) containing a deletion of 267 amino acids of the extracellular domain is frequently highly expressed in human malignant gliomas and has been reported for cancers of the lung, breast, and prostate. We tested the efficacy of a novel monoclonal anti-DeltaEGFR antibody, mAb 806, on the growth of intracranial xenografted gliomas in nude mice. Systemic treatment with mAb 806 significantly reduced the volume of tumors and increased the survival of mice bearing xenografts of U87 MG.DeltaEGFR, LN-Z308.DeltaEGFR, or A1207.DeltaEGFR gliomas, each of which expresses high levels of DeltaEGFR. In contrast, mAb 806 treatment was ineffective with mice bearing the parental U87 MG tumors, which expressed low levels of endogenous wild-type EGFR, or U87 MG.DK tumors, which expressed high levels of kinase-deficient DeltaEGFR. A slight increase of survival of mice xenografted with a wild-type EGFR-overexpressing U87 MG glioma (U87 MG.wtEGFR) was effected by mAb 806 concordant with its weak cross-reactivity with such cells. Treatment of U87 MG.DeltaEGFR tumors in mice with mAb 806 caused decreases in both tumor growth and angiogenesis, as well as increased apoptosis. Mechanistically, in vivo mAb 806 treatment resulted in reduced phosphorylation of the constitutively active DeltaEGFR and caused down-regulated expression of the apoptotic protector, Bcl-XL. These data provide preclinical evidence that mAb 806 treatment may be a useful biotherapeutic agent for those aggressive gliomas that express DeltaEGFR.

Age and topographic variation of insulin-like growth factor-binding protein 2 in the human rpe

PURPOSE

Previous studies have shown that insulin-like growth factor-binding protein (IGFBP)-2 is markedly upregulated in senescent RPE cells in vitro, and might therefore be a marker of senescent cells in vivo. This study was conducted to determine whether IGFBP-2 expression in human RPE cells from the macula and periphery varies with age in vivo.

METHODS

Paraformaldehyde (4%)-fixed and optimal cutting temperature (OCT) compound-embedded human eyes from 17 patients were cryosectioned and subjected to high-sensitivity digoxigenin (DIG)-labeled cRNA in situ hybridization to determine the expression of IGFBP-2. Complementary immunohistochemistry experiments using a polyclonal anti-IGFBP-2 antibody were performed to confirm IGFBP-2 protein expression. Specimens were examined by light microscopy, and images were captured with a digital camera. The total numbers of RPE cells and IGFBP-2 mRNA expression-positive RPE cells were counted for each section, and the ratio of labeled RPE cells to total RPE cells counted was calculated for both macular and peripheral regions of each donor.

RESULTS

IGFBP-2 mRNA expression was detected in the ganglion cell layer, inner and outer nuclear layers, and inner segments of photoreceptor cells in all 17 eyes. In 16 of 17 eyes, IGFBP-2 mRNA expression was detected in the RPE. In 11, the ratio of labeled cells to total RPE cells counted per section in the macula was 1.2 times greater than the ratio in the periphery (P = 0.008). The ratio of labeled RPE cells in the macula decreased with age (P = 0.0064). Immunohistochemistry studies for IGFBP-2 confirmed the expression pattern found by in situ hybridization.

CONCLUSIONS

There is a topographical and age-related change in IGFBP-2 expression in RPE cells from human donor eyes. This distribution is likely not to represent senescent RPE cells in vivo.

Microdialysates of amines and metabolites from core nucleus accumbens of freely moving rats are altered by dizocilpine

In vivo microdialysis combined with high performance liquid chromatography (HPLC) with electrochemical detection, was used to study the effect of MK-801 (0.1 mg/kg i.p.) on extracellular concentrations of dopamine (DA) 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), norepinephrine (NE) and DOPAC/DA ratio in intact, 6-hydroxydopamine (6-OHDA)-lesioned, DSP4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzyl-amine hydrochloride)-lesioned and reserpine-treated rats. The results revealed high basal DA (0.735+/-0.05 fmol/microl), DOPAC (195.93+/-20.18 fmol/microl) and NE (0.585+/-0.01 fmol/microl), low 5-HT (0.334+/-0.032 fmol/microl) and high DOPAC/DA ratio (265.11+/-20.73) in intact cACC. 6-OHDA alone (8 microg/2 microl) depleted DA (-66%), DOPAC (-65%), and NE (-62%). On the other hand, in desipramine (DMI)-pretreated rats, 6-OHDA induced a large depletion of DA (-94%), DOPAC (-97%) and reduced DOPAC/DA ratio (-73%), but increased NE to 142% of intact and 369% of 6-OHDA-lesioned rats. DSP4 (50 mg/kg) decreased NE (-97%), DOPAC (-75%) and DOPAC/DA ratio (-69%). Reserpine (5 mg/kg s.c.) significantly decreased DOPAC (-84%), DOPAC/DA ratio (-81%), 5-HT (-69%) and NE (-86%), but nonsignificantly increased DA. In the intact rats, MK-801 did not change DA, but increased DOPAC and DOPAC/DA ratio. In 6-OHDA-lesioned rats, MK-801 increased DA, whereas in 6-OHDA+DMI rats MK-801 additionally increased DOPAC and DOPAC/DA ratio. DSP4 and reserpine reduced the ability of MK-801 to increase DOPAC and DOPAC/DA ratio. MK-801 did not change NE concentration in dialysates collected from intact rats, but increased that from 6-OHDA+DMI-lesioned rats. In DSP4-lesioned and reserpine-treated rats, MK-801 increased NE but to a level lower than that observed in the intact rats. These results suggest that systemic administration of a low dose of MK-801, which induces profound locomotor stimulation without stereotypy, increases DOPAC and DOPAC/DA ratio in the cACC of intact rats, whereas it additionally increases the depleted DA and NE concentrations especially in 6-OHDA-lesioned rats pretreated with DMI.

Association of structural polymorphisms in the human period3 gene with delayed sleep phase syndrome

Recent progress in biological clock research has facilitated genetic analysis of circadian rhythm sleep disorders, such as delayed sleep phase syndrome (DSPS) and non-24-h sleep-wake syndrome (N-24). We analyzed the human period3 (hPer3) gene, one of the human homologs of the Drosophila clock-gene period (Per), as a possible candidate for rhythm disorder susceptibility. All of the coding exons in the hPer3 gene were screened for polymorphisms by a PCR-based strategy using genomic DNA samples from sleep disorder patients and control subjects. We identified six sequence variations with amino acid changes, of which five were common and predicted four haplotypes of the hPer3 gene. One of the haplotypes was significantly associated with DSPS (Bonferroni's corrected P = 0.037; odds ratio = 7.79; 95% CI 1.59-38.3) in our study population. Our results suggest that structural polymorphisms in the hPer3 gene may be implicated in the pathogenesis of DSPS.

Roles of protein kinase C and Ca2+-dependent signaling in angiotensin II-induced adrenomedullin production in rat cardiac myocytes

OBJECTIVES

We showed that angiotensin II stimulates adrenomedullin production in cultured neonatal rat cardiac myocytes, and that the secreted adrenomedullin inhibits hypertrophy of the myocytes, although the intracellular mechanisms of adrenomedullin production are still unknown. Since protein kinase C (PKC) and the Ca2+ signaling system are involved in cardiac hypertrophy, we examined the roles of these intracellular signaling systems in the production of adrenomedullin by myocytes.

METHODS

Cultured neonatal rat cardiac myocytes were incubated with agonists or antagonists of PKC and Ca2+ signaling systems for 24 h. Adrenomedullin secreted into the medium and adrenomedullin mRNA expression were measured by radioimmunoassay and quantitative polymerase chain reaction, respectively.

RESULTS

Both phorbol-12-myristate-13-acetate (PMA), a PKC activator and A23187, a calcium ionophore, significantly increased adrenomedullin mRNA expression and secretion from the myocytes. The induction of adrenomedullin secretion by PMA was abolished by H7, a PKC inhibitor, and by downregulation of PKC induced by pre-incubation with PMA. Similarly, the stimulation of adrenomedullin secretion by 10(-6) mol/l angiotensin II was significantly reduced following the inhibition or downregulation of PKC activity in the myocytes. Blockade of the L-type Ca2+ channel and chelation of intracellular Ca2+ both resulted in a significant reduction of the stimulation of adrenomedullin secretion by angiotensin II. In addition, the secretion was significantly attenuated by inhibitors of calmodulin (W-7) and calmodulin kinase II (KN-62), and slightly attenuated by FK506, a calcineurin inhibitor.

CONCLUSIONS

These results suggest that PKC and the Ca2+/calmodulin signaling systems are involved in angiotensin II-induced adrenomedullin secretion from rat cardiac myocytes.

Curvature elasticity of multilamellar lipid bilayers close to the chain-melting transition

We directly measured curvature elasticity of dipalmitoylphosphatidylcholine multilamellar bilayers close to the chain-melting transition using the method of electric-field-induced bending deformation of the cylindrical tubes. The result shows that the bending modulus, kappa(c), decreases remarkably at temperatures close to the melting transition temperature. This reflects a softening of the bilayer resulted from the area fluctuations as predicted theoretically. However, the decrease of kappa(c) near the transition is far smaller than that predicted. This is due to the experimental method and the narrow transition width of the multilamellar bilayers. Nevertheless, the result obtained gives direct evidence of the kappa(c) reduction predicted for multilamellar membranes in the transition regime. Below about 41 degrees C, almost of all cylindrical tubes cannot response to the electric field, indicating a very large bending rigidity.

Molecular mechanisms for alpha2-adrenoceptor-mediated regulation of synoviocyte populations

The sympathetic nervous system has been indicated to influence the severity of inflammatory disease including rheumatoid arthritis. In this study, we elucidated the effects of catecholamine on the synovial cell populations. Stimulation with epinephrine or norepinephrine for 1-2 weeks dose- and time-dependently increased the number of synovial A (macrophage-like) cells but decreased that of B (fibroblast-like) cells. These responses in A and B cells were inhibited by the alpha2-antagonist yohimbine, the G-protein inactivator pertussis toxin and the phospholipase C (PLC) inhibitor U-73122. Furthermore, the protein kinase C (PKC) inhibitor calphostin C and mitogen-activated protein (MAP) kinase inhibitors PD98059 and wortmannin also abolished the norepinephrine effects on A and B cell numbers. In A cells cloned from an A and B cell mixture, norepinephrine also increased the cell number. In immunoblotting and immunocytostaining analyses, among the PKC isozymes, only PKC betaII immunoreactivity was observed in the cytoplasm of unstimulated A and B cells. After alpha2-adrenoceptor stimulation, PKC betaII immunoreactivity increased in the plasma membranes of both A and B cells with decreases in the cytoplasm. These findings indicated that alpha2-adrenoceptor stimulation of type A and B synoviocytes produced an increase and a decrease in the respective cell number, probably through Gi-coupled PLC activation and the resulting stimulation of the PKC betaII/MAP kinase.

Selective and long-term learning impairment following neonatal hypoxic-ischemic brain insult in rats

We examined four different learning and memory tasks in rats which had been subjected to left carotid artery ligation followed by 2 h hypoxia (8% oxygen) when they were 7 days old. The examination began on the 4th week after insult and continued to 18 weeks post-insult. Compared with the control group, the hypoxic-ischemic group showed significant learning impairments in choice reaction time tasks relating to the attention process, and in plus-maze tasks and water maze tasks which examine long-term reference memory. In eight-arm radial maze tasks representing both short-term working memory and long-term reference memory, inferiority of the hypoxic-ischemic group was transient. Results of the sensorimotor test were normal in the hypoxic-ischemic group although slight flexion and twisting in the right forelimb was observed in 30% of the hypoxic-ischemic group when suspended by the tail. These abnormalities did not affect the results of learning tests. Findings of the study indicate that left-side brain damage produced by hypoxia-ischemia at 7 days of age resulted in selective and long-lasting learning and memory impairment.

Involvement of anion exchange in the hypoxia/reoxygenation-induced changes in pH(i) and

The involvement of Cl(-)/HCO(3)(-) exchange in hypoxia/reoxygenation-induced changes in pH(i) and Ca(2+) concentration ([Ca(2+)](i)) was examined in rat ventricular myocytes. During 10-min hypoxia, the initial pH(i) (7.21+/-0.04) fell to below 6.8. Subsequent reperfusion with reoxygenated buffer returned this acidic pH(i) to the neutral range with increases in [Ca(2+)](i). These responses were reduced by the removal of Cl(-) or HCO(3)(-) and by the addition of anion exchange inhibitors, SITS (4-acetamido-4'isothiocyanato-stilbene-2,2'disulfonic acid) and DIDS (4,4'-diisothiocyano-stilbene-2,2'-disulfonic acid), while inhibitors for the Cl(-) channel and Na(+)/K(+)/2Cl(-) cotransport were without effects. The hypoxia-induced acidification was attenuated by protein kinase C inhibitors, calphostin C and chelerythrine, but not by a protein kinase A inhibitor, KT5720. Under normoxic condition, protein kinase C activation induced a SITS-sensitive acidification. Furthermore, in electrically driven rat papillary muscle, SITS and DIDS improved the recovery of developed tension during the reoxygenation. These results suggest that the hypoxia-induced decrease in pH(i) is mediated at least in part by anion exchange stimulation through protein kinase C activation, and this exchange takes part in the reoxygenation-induced Ca(2+) overload as well as contractile dysfunction.

Comparison between the palatal configurations in complete and incomplete unilateral cleft lip and palate infants under 18 months of age

OBJECTIVE

The purpose of this study was to examine the three-dimensional characteristics of the palatal configurations in incomplete unilateral cleft lip and palate (UCLP) patients and to determine whether there are differences in the effect of early orthopedic treatment between complete and incomplete UCLP patients.

DESIGN

Eight infants with incomplete UCLP and 12 infants with complete UCLP, selected at random, wore Hotz plates, and 8 other infants with complete UCLP did not. Palatal impressions were taken of these patients immediately after birth and at 1, 2, 3, 4 (just before cheiloplasty), 6, and 18 months of age (just before palatoplasty). Using our measuring system, the palatal casts were measured and compared three-dimensionally.

RESULTS AND CONCLUSIONS

The palate of the incomplete UCLP patients measured immediately after birth, compared with complete UCLP, showed: (1) smaller posterior arch width; (2) sagittal arch length did not differ; (3) incisal point was located more mesially; (4) the gap between the alveolar arch forms of the major and minor segments was smaller; and (5) the curvature of the palatal surface forward the nasal cavity in the minor segment was less. At 18 months of age, the following characteristics could be observed: (1) the difference observed at birth in the posterior arch width between the incomplete and complete UCLP infants vanished; (2) a significant difference in the location of the incisal point was observed only between the incomplete UCLP infants and the complete UCLP infants with a Hotz plate; and (3) the curvature was less in the incomplete UCLP infants than in the complete UCLP infants. Furthermore, the morphological change of the palatal surface was less in the incomplete UCLP infants than in the complete UCLP infants. This suggested that any influence of the Hotz appliance might be less in incomplete UCLP than in complete UCLP.

Diminished melatonin secretion in the elderly caused by insufficient environmental illumination

The pineal hormone melatonin has some circadian regulatory effects and is assumed to have a close relation with sleep initiation and maintenance. Many previous reports have described age-related decreases in melatonin levels, especially in elderly insomniacs (EIs), which may act as causal or exacerbating factors in sleep disturbances in the elderly. Ten elderly residents with psychophysiological insomnia (mean age, 74.2 yr), 10 healthy residents of the same home [elderly control (EC) group; mean age, 72.7 yr], and 10 healthy young control subjects (mean age, 20.9 yr) living at home participated in this study. The elderly persons, especially the EIs, were exposed to significantly less environmental light and simultaneously suffered from significantly diminished nocturnal melatonin secretion. Supplementary exposure to 4 h (1000 to 1200 h, 1400 to 1600 h) of midday bright light in the EI group significantly increased melatonin secretion to levels similar to those in the young control group without circadian phase-shifting. There was a tendency for the magnitude of the increase in nocturnal melatonin secretion stimulated by bright light to parallel amelioration of sleep disturbances in these subjects. The present findings suggest that we need to pay attention to elderly individuals who suffer under conditions of poor environmental light resulting in disorganized circadian rhythms, including the sleep-wake cycle.