Effects of nitric oxide synthase inhibitors on gastric alkaline secretion in rats.

The effects of NG-nitro-L-arginine methyl ester (L-NAME), the nitric oxide (NO) synthase inhibitor, on gastric HCO3- secretion were examined in anesthetized rats. Intravenous administration of L-NAME (1, 2.5, 5 mg/kg) increased HCO3- secretion in a dose-related manner. This effect of L-NAME was mimicked by NG-mono-methyl-L-arginine (50 mg/kg, i.v.) and was antagonized significantly by concurrent administration of L-arginine but not D-arginine (200 mg/kg, i.v.). These results indicate that gastric HCO3- secretion is stimulated by inhibition of NO biosynthesis.     

Surface epithelial cell damage induced by restraint and water-immersion stress in rats effects of 16,16-dimethyl prostaglandin E2 on stress-induced gastric lesions

The time-course of gastric mucosal surface epithelial cell damage and macroscopically visible lesions in response to restraint and water-immersion stress (22 degrees C) in rats was examined, and the effects on it of 16,16-dimethyl prostaglandin E2 (dmPGE2) were compared with those of papaverine, timoprazole and atropine. The stress produced surface epithelial cell damage prior to visible lesion, the former increasing in severity with time and reaching a plateau 60 min later, by which time exfoliation of surface epithelial cells was observable along the mucosal folds. In contrast, macroscopically visible lesions appeared 2 hr after stress, and severity continued to increase with time. Pretreatment injections (s.c.) of dmPGE2 (3, 30 micrograms/kg), papaverine (100 mg/kg) and atropine (1 mg/kg) protected the surface cells against stress (1 hr)-induced damage, and inhibited visible lesion formation after 4 hr stress. Timoprazole (30 mg/kg, s.c.) did not protect the surface cells, but did markedly inhibit visible lesion formation. dmPGE2, papaverine and atropine, but not timoprazole, inhibited stress-induced increases in gastric contractions. dmPGE2, timoprazole and atropine, but not papaverine, inhibited acid secretion in stress-conditions. These results indicated that stress induced damage to the gastric mucosa within 1 hr due to increased gastric contractions, and the surface epithelial cell damage developed into macroscopically visible lesions in the presence of acid, and that dmPGE2 protected the surface epithelium against stress-induced damage probably by inhibiting gastric contractions.     

Effects of misoprostol, (+/-)-methyl (11 alpha, 13E)-11, 16-dihydroxy-16-methyl-9-oxoprost-13-en-l-oate, on various gastric and duodenal lesions in rats

Male Sprague-Dawley rats (230-280 g), either fasted for 15-24 hr or non-fasted prior to experiments, were used. Misoprostol (3-100 micrograms/kg, p.o.) dose-dependently inhibited the development of 150 mM HCl X aspirin (100 mg/kg)-, 150 mM HCl X 60% ethanol-, and aspirin (150 mg/kg)-induced gastric lesions. Misoprostol (30, 100 micrograms/kg, p.o.), given twice daily for 4 days, significantly inhibited prednisolone (50 mg/kg given once daily for 4 days)-induced gastric lesions. Misoprostol (30 or 2 X 300 micrograms/kg, p.o.) also significantly inhibited water-immersion stress (21 degrees C, 10 hr)-induced gastric lesions or mepirizole (200 mg/kg)-induced duodenal lesions, respectively. In contrast, misoprostol (30-300 micrograms/kg, p.o.) had no effects on indomethacin (25 mg/kg)- and mepirizole (200 mg/kg)-induced gastric lesions. Misoprostol (30 micrograms/kg, p.o.) had no effect on gastric secretion in pylorus-ligated preparations (4 hr), but it (100 or 300 micrograms/kg, p.o.) significantly increased the volume and pepsin output. Gastric motility, either normal or enhanced with indomethacin (25 mg/kg), was inhibited by misoprostol (30 or 300 micrograms/kg, p.o.). Misoprostol (30 micrograms/kg, i.d.) significantly stimulated duodenal HCO3- secretion. Mechanisms by which misoprostol inhibits various gastric lesions remain unknown. However, the stimulatory activity on duodenal HCO3- secretion appears to be involved in the preventive effect of misoprostol on the development of duodenal lesions. The effects of cimetidine and 16,16-dimethyl PGE2 were also studied and compared with those of misoprostol.     

Basement membranes in adenoid cystic carcinoma. An immunohistochemical study.

Tissue samples from 30 patients with adenoid cystic carcinoma and 20 with adenocarcinoma of salivary gland origin were studied by immunohistochemical staining with specific antibodies to the four macromolecules that are present in normal basement membranes: type IV collagen, laminin, heparan sulfate proteoglycan, and entactin. In the adenoid cystic carcinoma samples, the four proteins were localized in different types of extracellular matrices in the tumor, namely pseudocystic spaces, hyaline stroma, and around tumor cell nests. The staining intensity was enhanced by pretreatment with hyaluronidase. The tumor cells of adenoid cystic carcinoma showed a tendency to proliferate with individual cells in contact with the basement membrane and to infiltrate through basement membrane-rich tissues, such as peripheral nerves, blood vessels, and skeletal muscles. In contrast, only circumferential staining of tumor cell nests was obtained in adenocarcinoma samples. The results suggest that adenoid cystic carcinoma is a tumor with affinity for basement membranes, and this basic feature is reflected in its histology and presumably in its biologic behavior. Immunostaining with antibodies to basement membrane proteins appears to be useful for differential diagnosis of some types of these two carcinomas.     

Histologic typing of non-Hodgkin's lymphomas by in situ hybridization with DNA probes of oncogenes

Expression of six proto-oncogenes (fos, myc, myb, Ki-ras, Ha-ras, and N- ras) in 43 cases of non-Hodgkin's lymphoma was analyzed by means of in situ hybridization. Biotinylated DNA probes of the six oncogenes and those of immunoglobulin H (IgH) gene and T-cell receptor beta (TCR beta) chain gene were used. The results of in situ hybridization performed under blind conditions by IgH gene and TCR beta chain gene probes were compatible with those of typing by cell surface markers. The nuclear protein-related proto-oncogenes, fos, myc, and myb, were expressed in about 70% to 80% of all cases regardless of phenotype, histology, or histologic grade. On the contrary, genes of ras family were expressed in more limited numbers of cases except for the Ki-ras gene, which was more frequently expressed by cases of the T-cell immunophenotype with a high malignancy grade. The results of dot hybridization with RNA extracted from some cases were compatible with those of in situ hybridization, further demonstrating the specificity of in situ hybridization.     

Stimulation by prostaglandin E2 of alkaline secretion in the rat duodenum: comparative study with hypertonic NaCl

Possible involvement of increased mucosal permeability in the stimulation by prostaglandin E2 (PGE2) of duodenal HCO3- secretion was investigated in rats. PGE2 (0.3, 1 mg/kg, s.c.) dose-dependently increased HCO3- secretion in the duodenum with a significant elevation of transmucosal potential difference (PD); the PD was increased from -4.5 +/- 0.3 mV to -10.0 +/- 1.5 mV (mucosa negative) at 1 mg/kg. These responses caused by PGE2 were abolished by sacrificing the animals with saturated KCl (i.v.). Although a significant increase of HCO3- output was observed after exposure of the mucosa to 1 M NaCl (0.5 ml), this response was accompanied by a significant reduction of PD and was not abolished after KCl injection. The mucosal permeability determined by Evans blue (1%, i.v.) was not affected by PGE2, while 1 M NaCl markedly elevated the amount of extravasated dye in both the luminal content and the mucosa. Stimulation of HCO3- output by PGE2 was significantly mitigated by ouabain (3 mg/kg, s.c.) or prior exposure of the mucosa to 1 M NaCl. These results suggest that stimulation by PGE2 of duodenal HCO3- secretion is not simply due to the increased mucosal permeability, but depends rather on both the Na/K ATPase activity and the intact perfusion of the organ. The HCO3- response as induced by 1 M NaCl may result from the increased permeability and is accompanied by a marked reduction of PD.     

Climbing exercise increases bone mass and trabecular bone turnover through transient regulation of marrow osteogenic and osteoclastogenic potentials in mice.

To investigate the relationship between the effects of bone turnover and bone marrow cell development in bone cells, we developed a mouse voluntary climbing exercise model. Climbing exercise increased bone volume and transient osteogenic potential of bone marrow. This model would be suitable for investigating the mechanistic roles of mechanical loading. INTRODUCTION: The relationship between bone mass gain and local bone formation and resorption in mechanically loaded bone is not well understood. MATERIALS AND METHODS: Sixty-five C57BL/6J mice, 8 weeks of age, were assigned to five groups: a baseline control and two groups each of ground control and climbing exercise mice for 2 and 4 weeks. Mice were housed in a 100-cm tower and had to climb toward a bottle placed at the top to drink water. RESULTS: Compared with the ground control, bone mineral density of the left femur increased in the climbing mice at 4 weeks. At 2 and 4 weeks, bone formation rate (BFR/BS) of periosteal surface, the cross-sectional area, and moment of inertia were increased in the climbing mice, whereas BFR/BS and eroded surface (ES/BS) of endosteal surface did not differ. The trabecular bone volume (BV/TV) of the proximal tibia increased in climbing mice, and osteoclast surface (Oc.S/BS) and osteoclast number decreased at 2 weeks. At 4 weeks, there were increases in BV/TV and parameters of bone formation, including mineralized surface, mineral apposition rate, and bone formation rate. In marrow cell cultures from the tibia, the number of alkaline phosphatase+ colony forming units-fibroblastic and the area of mineralized nodule formation in climbing mice were increased, and the number of osteoclast-like TRACP+ multinucleated cells was lower at 2 weeks. At 4 weeks, these parameters recovered to the levels of the ground controls. CONCLUSION: Our results indicate that climbing increased trabecular bone volume and reduced bone resorption, with a subsequent increase in bone formation. Intermittent climbing downregulates marrow osteoclastogenic cells and upregulates osteogenic cells initially, but further exercise seemed to desensitize them. Cortical envelopes were enlarged earlier, but the response seems to differ from trabecular bone.     

Measurement of free and total hydroxyproline by automated flow injection of serum or urine samples from maintenance hemodialysis patients with renal osteodystrophy

An automated measurement of total and free hydroxyproline in serum or urine is presented that uses flow injection analysis. After exclusion of nonspecific substances, hydroxyproline was oxidized by chloramine- T and L-cysteine with Ehrlich's reagent. The linearity obtained was from 3.8μmole/ L to 1.22 mmole/L with good precision (CV <3%). Comparison of the proposed method with HPLC yielded r = 0.939 as the correlation coefficient. Reference intervals of free and total hydroxyproline are 1.4–9.7 μmole/L, 3.8–27.2 μmole/L for serum, and 10.0–72.5 μmole/L, 25.2–303.6 μmole/L for urine, respectively. Serum free and total hydroxyproline levels in renal osteodystrophy patients on maintenance hemodialysis (N = 71) were significantly higher than in controls (P<0.0001). This method is superior to the use of HPLC with regard to stability of the color reaction. The measurement of serum free and total hydroxyproline is a useful marker for therapeutic observation of renal osteodystrophy patients. © 1994 Wiley-Liss, Inc.