Search

The purpose of this study was to test the hypothesis that [H.sub.2][O.sub.2] decreases the amount of force produced by a given intracellular [Ca.sup.2+] concentration (i.e., the [Ca.sup.2+] sensitivity) in airway smooth muscle (ASM) in part by mechanisms independent of changes in regulatory myosin light chain (rMLC) phosphorylation. A new preparation was developed and validated in which canine ASM strips were first exposed to [H.sub.2][O.sub.2] and then permeabilized with 10% Triton X-100 to assess the persistent effects of [H.sub.2][O.sub.2] on [Ca.sup.2+] sensitivity. Experiments in which [H.sub.2][[O.sub.2] was administered before permeabilization revealed a novel mechanism that contributed to reduced [Ca.sup.2+] sensitivity independently of changes in rMLC phosphorylation, in addition to an rMLC phosphorylation-dependent mechanism. The mechanism depended on factors not available in the permeabilized ASM strip or in the buffer to which the strip was exposed, since there was no effect when [H.sub.2][[O.sub.2] was added to permeabilized strips. [H.sub.2][[O.sub.2] treatment of a maximally thiophosphorylated purified myosin subfragment (heavy meromyosin) significantly reduced actomyosin ATPase activity, suggesting one mechanism by which the phosphorylation-independent reduction in [Ca.sup.2+] sensitivity may occur. regulatory myosin light chain phosphorylation; thiophosphorylation; permeabilized smooth muscle; reactive oxidant species; myosin; actomyosin adenosinetriphosphatase

Doctors describe the successful transplantation of a larynx, trachea, pharynx, thyroid, and parathyroid glands to treat a man whose larynx and pharynx had been crushed 20 years before in a motorcycle accident. The man learned to speak and could swallow normally.

Research was conducted to find out whether the time-dependent decline in the rate of ATP hydrolysis by actomyosin ATPase during sustained isometric force can occur in the absence of a time-dependent decrease in regulatory myosin light chain (rMLC) phosphorylation in Triton X-100-permeabilized canine tracheal smooth muscle. Maximal activation with 10 microM Ca2+ induced sustained increases in isometric force, stiffness and rMLC phosphorylation. However, the increase in the ATP hydrolysis rate was initially high but then decreased to a steady-state level above that of the unstimulated muscle.

A study was conducted on the influence of four putative protein kinase C inhibitors on acetylcholine-induced Ca2+ sensitization using a Beta-escin permeabilized canine tracheal smooth muscle. The four pharmacological protein kinase C inhibitors employed are chelerythrine chloride, calphostin C, staurosporine and a pseudosubstrate protein kinase C inhibitor. None of the inhibitors were able to reverse or prevent increase in Ca2+ sensitization induced by acetylcholine plus GTP.

The ability of halothane to inhibit the influx of Ca2+ in tracheal smooth muscle cells during submaximal and maximal muscarinic stimulation was investigated. Decreases in both the Ca2+ and Mn2+ influx were observed during submaximal muscarinic stimulation but halothane has no observed effect on Ca2+ and Mn2+ influx during maximal stimulation. Results showed that the intensity of muscarinic stimulation influence the effects of halothane on Ca2+ influx.

The role of acetylcholine (ACh) in mediating nitric oxide (NO) release from the vascular endothelium was investigated by monitoring the release of NO from local cholinergic mechanisms using a standard bioassay system. The results showed that release of NO from the vascular endothelium can be mediated by local cholinergic mechanisms. ACh was shown to stimulate NO release from the vascular endothelial cells or from neighboring cells.

A study of the involvement of cyclic nucleotides in the direct effect of halothane on the smooth muscle cell that mediates airway smooth muscle relaxation in acetylcholine (Ach)-treated canine tracheal smooth muscle reveals that a cyclooxygenase-dependent pathway mediates the halothane-induced increase in intracellular cAMP levels and that this increase does not contribute to the relaxation. Ach-induced increases in isometric force and intracellular Ca2+ are lowered by halothane, while the increase in cAMP level is furthered by halothane. Indomethacin eliminates the effects of Ach and halothane on cAMP levels but does not influence the isometric force and Ca2+ levels.

The theory of reduction of force generation for a given concentration of Ca ion by halothane in canine tracheal smooth muscles in vitro during acetylcholine (ACh)-induced stimulation of muscarinic receptor is evaluated. The direct relaxing effect of halothane on canine tracheal smooth muscle occurs through a muscarinic receptor stimulation intensity-dependent cellular pathway. Stimulation with low quantities of ACh leads to force reduction through reduced Ca ion concentration.

An analysis of canine tracheal smooth muscle (CTSM) which contracts due to acetylcholine or KCl reveals that relaxation which seems to be mediated by guanosine 3',5'-cyclic monophosphate-dependent processes that lower (Ca2+)i, is induced by 3-morpholinosydnonimine. This is evident from an analysis of the comparative significance of processes nitrovasodilators use to relax the airway smooth muscle, and other relaxing processes for CTSM.

A powerful bronchodilator halothane affects canine tracheal muscle constriction modulated vagally. The acetylcholine-induced impermanent peak of ionized calcium concentration (Ca2+)i is altered due to the presence of halothane. Sustained and developed muscle force during peak-formation are recorded. Developed force and (Ca2+)i are enhanced by halothane, while halothane impact on sustained force results in tracheal smooth muscle relaxation. While halothane affects (Ca2+)i, no effect is observed on the membranal calcium movement.

* Context.--Head and neck squamous cell carcinoma is commonly associated with tobacco and alcohol use. There are, however, a group of patients without a significant history of tobacco or alcohol use, and the etiology of these tumors is incompletely understood. Objective.--To examine tumors in this subpopulation for association with human papillomavirus (HPV) using newly available in situ hybridization probes. Design.--Between October 2004 and October 2005, 22 patients who did not use alcohol or tobacco were included. Formalin-fixed, paraffin-embedded tissue sections were used to perform in situ hybridization using newly available probe sets (Ventana Medical Systems, Tucson, Ariz). The slides were examined for the presence of integrated HPV using light microscopy. Positive and negative xenograft controls were run with the assay. Results.--The mean age of the patients was 64 years. There were 14 men and 8 women. The most common anatomic sites included tongue (n = 8), tonsil (n = 7), and larynx (n = 7). All cases and controls were successfully stained. Only 2 cases were positive for high-risk HPV, and both demonstrated an integrated pattern. Both cases were tumors of the tonsil. No cases were positive for low-risk HPV. Conclusions.--These results demonstrate that the new probe sets for HPV can be used very efficiently in clinical pathology material of head and neck squamous cell carcinoma. Our data show that high-risk HPV is an uncommon finding in head and neck squamous cell carcinoma from patients who do not have a history of tobacco or alcohol use; low-risk HPV was not seen in any case., Tobacco and alcohol use are well known and established risk factors for head and neck squamous cell carcinoma (HNSCC). However, there is a subset of HNSCC patients who do not [...]

Lorenz, Robert R., David O. Warner, and Keith A. Jones. Hydrogen peroxide decreases [Ca.sup.2+] sensitivity in airway smooth muscle by inhibiting rMLC phosphorylation. Am. J. Physiol. 277 (Lung Cell. Mol. Physiol. 21): L816-L822, 1999.--The purpose of this study was to determine the mechanism by which hydrogen peroxide ([H.sub.2][O.sub.2]), an important inflammatory mediator, relaxes canine tracheal smooth muscle (CTSM). [H.sub.2][O.sub.2] caused concentration-dependent relaxations of CTSM strips contracted with ACh or isotonic KCl [[EC.sub.50] of 0.24 [+ or -] 0.04 (SE) and 0.23 [+ or -] 0.04 mM, respectively]. Indomethacin (10 [micro]M) decreased the sensitivity of both KCl- and ACh-contracted strips to [H.sub.2][O.sub.2]. [H.sub.2][O.sub.2] increased intracellular cAMP levels, an increase that was abolished by indomethacin. [H.sub.2][O.sub.2] did not affect intracellular cGMP levels. In strips treated with indomethacin and contracted with ACh or isotonic KCl, [H.sub.2][O.sub.2]-evoked relaxations were accompanied by increases in intracellular [Ca.sup.2+] concentration and decreases in regulatory myosin light chain phosphorylation. We conclude that [H.sub.2][O.sub.2] decreases [Ca.sup.2+] sensitivity in CTSM by decreasing regulatory myosin light chain phosphorylation through inhibition of myosin light chain kinase and/or activation of smooth muscle protein phosphatases. lung; trachea; canine tracheal smooth muscle; acetylcholine; guanosine 3',5'-cyclic monophosphate; adenosine 3',5'-cyclic monophosphate; regulatory myosin light chain