Ultrastructural localization of adhalin in normal murine skeletal myofiber

The ultrastructural localization of adhalin and its relations to dystrophin, β-dystroglycan, and β-spectrin were studied in normal murine skeletal myofibers. The C-terminal peptides of adhalin and β-dystroglycan were synthesized based on their cDNAs, and the affinity-purified antibodies against these peptides were produced. Single-immunolabeling electron microscopy showed that the adhalin was located just inside the muscle plasma membrane or inside the myofiber a short distance from the plasma membrane. The adhalin signal was also noted at the sarcoplasmic side of plasmalemmd invaginations or at vesicular structures in subsarcolemmal areas. Double-immunogold-labeling electron microscopy disclosed a similar localization of dystrophin, β-dystroglycan, and β-spectrin. The close association of adhalin with dystrophin or β-dystroglycan was demonstrated by formation of doublets by signals of antibodies of adhalin with those of dystrophin or β-dystroglycan and was confirmed by statistical analyses. This study demonstrated that the location of adhalin is close to that of dystrophin and β-dystroglycan at the muscle plasma membrane.     

Dual Effects of Hexanol and Halothane on the Regulation of Calcium Sensitivity in Airway Smooth Muscle

Background: Contraction of airway smooth muscle is regulated by receptor-coupled mechanisms that control the force developed for a given cytosolic calcium concentration (i.e., calcium sensitivity). Halothane antagonizes acetylcholine-induced increases in calcium sensitivity by inhibiting GTP-binding (G)-protein pathways. The authors tested the hypothesis that hexanol, like halothane, inhibits agonist-induced increases in calcium sensitivity in airway smooth muscle by inhibiting G-protein pathways.

Methods: Calcium sensitivity was assessed using [alpha]-toxin-permeabilized canine tracheal smooth muscle. In selected experiments, regulatory myosin light chain phosphorylation was also determined by Western blotting in the presence and absence of 10 mm hexanol and/or 100 [mu]m acetylcholine.

Results: Hexanol (10 mm) and halothane (0.76 mm) attenuated acetylcholine-induced calcium sensitization by decreasing regulatory myosin light chain phosphorylation during receptor stimulation. Hexanol also inhibited increases in calcium sensitivity due to direct stimulation of heterotrimeric G-proteins with tetrafluoroaluminate but not with 3 [mu]m GTP[gamma]S, consistent with prior results obtained with halothane. In contrast, in the absence of receptor stimulation, both compounds produced a small increase in calcium sensitivity by a G-protein-mediated increase in regulatory myosin light chain phosphorylation that was not affected by pertussis toxin treatment.     

Anesthetics Inhibit Membrane Receptor Coupling to the Gq/11 Heterotrimeric G Protein in Airway Smooth Muscle

Background: Some anesthetics relax airway smooth muscle in part by inhibiting acetylcholine-induced increases in Ca2+ sensitivity, an effect associated with inhibition of guanosine nucleotide exchange at the [alpha] subunit of the Gq/11 (G[alpha]q/11) heterotrimeric G protein. This study tested the hypothesis that these anesthetic effects are not unique to the muscarinic receptor but are a general property of the heptahelical receptors that increase Ca2+ sensitivity in airway smooth muscle.

Methods: Anesthetic effects on agonist-induced increases in Ca2+ sensitivity were measured in porcine airway smooth muscle strips permeabilized with S. aureus [alpha]-toxin. Anesthetic effects on basal (without agonist stimulation) and agonist-promoted G[alpha]q/11 guanosine nucleotide exchange were determined in crude membranes prepared from porcine airway smooth muscle. The nonhydrolyzable, radioactive form of guanosine 5'-triphosphate was used as the reporter for nucleotide exchange at G[alpha]q/11.

Results: Acetylcholine, endothelin-1, and histamine caused a concentration-dependent increase in Ca2+ sensitivity. Halothane (0.67 +/- 0.07 mm) and hexanol (10 mm) significantly inhibited the increase in Ca2+ sensitivity induced by each agonist. Each agonist also caused a time- and concentration-dependent increase in G[alpha]q/11 nucleotide exchange. Neither anesthetic had an effect on basal G[alpha]q/11 nucleotide exchange, whereas halothane and hexanol significantly inhibited the increase in G[alpha]q/11 nucleotide exchange promoted by each agonist.     

Intrarenal localization of receptors for alpha-rat atrial natriuretic polypeptide: an autoradiographic study with [125I]-labeled ligand injected in vivo into the rat aorta

We examined intrarenal localization of receptors for alpha-rat atrial natriuretic polypeptide (alpha-rANP) by injecting [125I]-labeled ligand in vivo into the rat aorta. We found that the receptors for alpha-rANP are distributed also on the vasa recta of the outer and inner medulla in addition to the previously reported sites, i.e., the renal arteries, renal pelvis, glomeruli, and inner medullary tissues including collecting tubules. In the vascular bundle of the outer medulla, the majority of grains was preferentially localized on the arterial vasa recta. The electron microscopic autoradiography of the glomerulus showed that the binding sites were mainly localized on the foot process of the podocyte. Since alpha-rANP injected into the aorta under physiological conditions was bound to the glomerulus and vasa recta in the kidney, the effect of ANP on these binding sites may be important in the mechanism of natriuresis.     

Aging gracefully: a retrospective analysis of functional status in Okinawan centenarians.

OBJECTIVE: This study retrospectively explored the late-life functional status of Okinawan centenarians. METHODS: Activities of daily living were measured retrospectively at five time points (10, 5, 3, and 1 year prior and present) for 22 centenarians in relation to seven physical, two sensory, and two cognitive functions using the Inoue Index. RESULTS: In all, 82% of individuals were still functioning independently at a mean age of 92 years and almost two-thirds were still functioning independently at a mean age of 97 years. CONCLUSION: Preliminary analyses suggest high functional status in Okinawan centenarians throughout their 90 s. The genetic and environmental factors contributing to this successful aging phenomenon deserve further investigation.     

PEUTZ‐JEGHERS SYNDROME ASSOCIATED WITH RENAL AND GASTRIC CANCER THAT DEMONSTRATED AN STK11 MISSENSE MUTATION

A 75‐year‐old male was admitted to the gastroenterology unit of Nagoya City University Hospital due to epigastralgia after surgical treatment for right renal cancer. Endoscopy revealed advanced type 1 gastric cancer in the corpus of the stomach and multiple polypoid lesions in the stomach and duodenum. X‐ray examination of the small intestine using barium showed multiple polyps in the upper jejunum. Faint pigmentation on the palm was also detected. Peutz‐Jeghers syndrome (PJS) was diagnosed, despite a lack of family history. Total gastrectomy, resection of part of the upper jejunum and intraoperative endoscopic polypectomy of duodenal polyps was performed. This is the second reported case of PJS associated with renal cancer. We also detected a missense mutation in the tumor suppressor gene STK11 that, when mutated, is causative for PJS.