Thrombin is the major serum factor stimulating phosphoinositide turnover, but not DNA synthesis in human neuroblastoma SH-EP cells.

Fetal calf serum stimulates both phosphoinositide turnover and DNA synthesis in SH-EP cells. The phosphoinositide turnover-stimulating activity of serum is largely (70%) reduced in the presence of hirudin, a blocker of thrombin activity. Yet, hirudin does not alter the ability of serum to stimulate DNA synthesis. Purified alpha-thrombin is a potent (EC50, 35 pM) stimulator of phosphoinositide turnover in SH-EP cells, but induces DNA synthesis only at much higher concentrations (10 nM-1 microM). Thus, serum thrombin accounts for most of the ability of serum to stimulate phosphoinositide hydrolysis, but not for the effect of serum on cell division, since the concentration of thrombin in serum is not sufficient to induce DNA synthesis. These data suggest that hydrolysis of inositol lipids may not be the main signalling event mediating the mitogenic effects of alpha-thrombin.     

Laryngeal Resistance before and after Minor Surgery: Endotracheal Tube versus Laryngeal Mask Airway™

Background: The placement of an endotracheal tube (ETT) may promote laryngeal swelling, which is an important cause of upper airway obstruction after extubation. The authors hypothesized that laryngeal swelling after ETT placement increases laryngeal resistance and tested that hypothesis by comparing postoperative laryngeal patency between patients with ETT placement and those with a Laryngeal Mask Airway(TM) (LMA(TM)).

Methods: Fourteen adult patients who underwent elective minor surgeries were randomly allocated to two groups whose airway would be managed through ETTs (the ETT group) or LMAs(TM) (the LMA(TM) group) during the surgery. While maintaining at sevoflurane 1 minimum alveolar concentration, the authors measured laryngeal resistance before and after surgery, during both spontaneous breathing and mechanical ventilation under complete paralysis. In addition, they endoscopically measured the vocal cord angle under complete paralysis.

Results: In association with marked swelling of the vocal cords, the vocal cord angle significantly decreased after surgery in the ETT group, whereas the angle did not change in the LMA group. Laryngeal resistance during mechanical ventilation significantly increased only in the ETT group. Laryngeal resistance during spontaneous breathing significantly increased after surgeries in both groups.     

Inhibition of inward rectifier K+ currents by angiotensin II in rat atrial myocytes: lack of effects in cells from spontaneously hypertensive rats.

We examined the effects of angiotensin II (Ang II) on inward rectifier K+ currents (IK1) in rat atrial myocytes. [125I]Ang II-binding assays revealed the presence of both Ang II type 1 (AT1) and type 2 (AT2) receptors in atrial membrane preparations. Ang II inhibited IK1 in isolated atrial myocytes with an IC50 of 46 nmol/l. This inhibition was abolished by the AT, antagonist RNH6270 but not at all by the AT2 antagonist PD123319. Treatment of cells with pertussis toxin or a synthetic decapeptide corresponding to the carboxyl-terminus of Gialpha-3 abolished the inhibition by Ang II, indicating the role of a Gi-dependent signaling pathway. Accordingly, Ang II failed to inhibit IK1 in the presence of forskolin, dibutyryl-cAMP or protein kinase A catalytic subunits. In spite of the increased binding capacities for [125I]Ang II, Ang II failed to affect IKI in cells from spontaneously hypertensive rats (SHR). AT, immunoprecipitation from atrial extracts revealed decreased amounts of Gialpha-2 and Gialpha-3 proteins associated with this receptor in SHR as compared with controls. The reduced coupling of AT, with Gialpha. proteins may underlie the unresponsiveness of atrial IK1 to Ang II in SHR cells.     

Regulation of the small GTPase RhoA by syndecan-4 and integrins in focal adhesion formation

Introduction The transmembrane heparan sulfate proteoglycan, syndecan‐4, and integrins are important receptors for focal adhesion (FA) formation on fibronectin (FN) substrates. The small GTPase RhoA is also known to regulate FA and stress fiber formation. It has been suggested that syndecan‐4 and integrins co‐operatively regulate the assembly of FA in a Rho‐dependent manner, but the mechanism is unclear. Here, we examined the function of RhoA and the Rho effector kinases ROCKs in syndecan‐4 signalling on the process of FA formation and the possible mechanism by which syndecan‐4 may regulate RhoA activity. Methods Primary rat embryonic fibroblasts (REFs) were seeded on FN or ‘RGD’‐containing integrin‐binding domain of FN and lysed at various time points. The amount of active form of RhoA in each lysate was analysed by pull‐down experiments. Results and discussion The relative activities of RhoA showed one peak in the process of FA formation on FN, whereas no peak was obtained on the integrin‐binding domain. The one peak of RhoA activity on integrin‐binding domain was restored by addition of heparin‐binding domain into medium. These results suggested that a signal through syndecan‐4 link to the Rho pathway. Both ROCK‐I and ‐II isozymes were present in REF cell lysates and each could be specifically immunoprecipitated. The ROCK kinase activities in immunoprecipitates were analysed using GST‐myosin light chain as a substrate. The amount of ROCK‐I and ‐II activities changed through the adhesion process on FN and appeared to be independently regulated. Therefore, one or both ROCKs may be downstream of a syndecan‐4‐mediated signalling response through RhoA. The core protein of syndecan‐4 can directly bind to and activate PKC‐α. We found that PKC‐α could phosphorylate Rho‐Guanine Nucleotide Dissociation Inhibitor (GDI) in vitro. It has been suggested that PKC‐α‐mediated phosphorylation of Rho GDI stimulates GDI dissociation, thereby resulting in Rho activation. It is possible that syndecan‐4 regulates Rho/ROCK pathway through PKC‐α activation on the process of FA formation.     

Serum Levels of Free Insulin-Like Growth Factor (IGF)-I in Normal Children

Serum levels of free insulin-like growth factor (IGF)-I were measured by immunoradiometric assay (IRMA) in fasting sera of 137 normal boys and 120 normal girls aged from 8 to 15 yr to study relationships between free IGF-I levels and ages, total IGF-I, IGF binding protein (IGFBP)-1, IGFBP-3, and acid-labile subunit (ALS) levels. In both sexes, serum free IGF-I levels and the ratios of free IGF-I to total IGF-I were significantly higher in the pubertal age groups than in the prepubertal age groups. Serum levels of free IGF-I showed a significant positive correlation with those of total IGF-I, IGFBP-3 and ALS, while they showed a significant negative correlation with those of IGFBP-1. These observations suggest that increase in serum free IGF-I levels during puberty is caused by a dramatic increase in total IGF-I, rather than IGFBP-3, and a decrease in IGFBP-1. Also, high free IGF-I levels may play an important role in pubertal growth spurt.     

Long-term survival of a pulmonary artery sarcoma produced by aggressive surgical resection and adjuvant chemoradiotherapy.

Malignant pulmonary artery tumors represented by sarcomas are rare, but fatal. Early diagnosis and radical surgical resection offer the only chance for survival. However, surgical intervention has some challenging aspects, and prognosis is poor even after tumor resection. We report a case of a pulmonary artery sarcoma between the right ventricular outflow tract and the pulmonary artery branches. The tumor was aggressively extracted with reconstruction using a cryopreserved pulmonary valved allograft, followed by adjuvant chemoradiotherapy. At 56 months after surgery, the patient is well without any evidence of recurrence, demonstrating that aggressive surgical resection with adjuvant chemoradiotherapy can prolong survival.     

Effects of exposure to microwaves on cellular immunity and placental steroids in pregnant rats.

OBJECTIVES: Microwaves produce various detrimental changes based on actions of heat or non-specific stress, although the effects of microwaves on pregnant organisms has not been uniform. This study was designed to clarify the effect of exposure to microwaves during pregnancy on endocrine and immune functions. METHODS: Natural killer cell activity and natural killer cell subsets in the spleen were measured, as well as some endocrine indicators in blood--corticosterone and adrenocorticotrophic hormone (ACTH) as indices of the hypothalamic-pituitary-adrenal axis--beta-endorphin, oestradiol, and progesterone in six female virgin rats and six pregnant rats (nine to 11 days gestation) exposed to microwaves at 10 mW/cm2 incident power density at 2450 MHz for 90 minutes. The same measurements were performed in control rats (six virgin and six pregnant rats). RESULTS: Skin temperature in virgin and pregnant rats increased immediately after exposure to microwaves. Although splenic activity of natural killer cells and any of the subset populations identified by the monoclonal antibodies CD16 and CD57 did not differ in virgin rats with or without exposure to microwaves, pregnant rats exposed to microwaves showed a significant reduction of splenic activity of natural killer cells and CD16+CD57-. Although corticosterone and ACTH increased, and oestradiol decreased in exposed virgin and pregnant rats, microwaves produced significant increases in beta-endorphin and progesterone only in pregnant rats. CONCLUSIONS: Microwaves at the power of 10 mW/cm2 produced activation of the hypothalamic-pituitary-adrenal axis and increased oestradiol in both virgin and pregnant rats, suggesting that microwaves greatly stress pregnant organisms. These findings in pregnant rats suggest that--with exposure to microwaves--pregnancy induces immunosuppression, which could result in successful maintainance of pregnancy. This enhancement of adaptability to heat stress with pregnancy may be mediated by activation of placental progesterone and placental or pituitary beta-endorphin.     

Histamine metabolism in the nasal tissue of human and nasal hypersensitive guinea-pig

Histamine (HA) is the most important mediator of nasal allergy and nasal hypersensitivity. To investigate HA metabolism, HA content and activities of its synthetic enzyme, histidine decarboxylase (HDC) and degrading enzymes, histamine-N-methyltransferase (HMT) and diamine oxidase (DAO) in nasal mucosa of human and toluene diisocyanate (TDI) sensitized guinea-pigs were measured. In human nasal mucosa and nasal polyps, HA content and HDC activity were 80-200 nmol/g tissue, 20-30 fmol/min/mg protein respectively. Among two degrading enzymes, HMT activity was 20-200 times higher than that of DAO. In the nasal mucosa of guinea-pigs, HA content was significantly increased by TDI sensitization, and was decreased immediately after TDI provocation. In 24 hours after provocation, HA content recovered to 80% of pre-provocation level. HDC activity increased by TDI sensitization significantly. Though HMT activity increased slightly by TDI sensitization and provocation, DAO activity was unchanged. The data suggest that, increase in turnover rate of HA is present in allergic nasal mucosa.