Corrosion and tarnish of dental silver-based alloys in 0.1% Na2S and Ringer's solutions. (Part 1) Electrochemical study

The corrosion behavior of three silver-based alloys, Ag-Sn-Zn, Ag-In, and Ag-Pd-Cu, were investigated by potentiodynamic anodic polarization analysis and the polarization resistance method in 0.1% Na2S and Ringer's solutions. The corrosion activity of the Ag-Sn-Zn alloy was higher in Ringer's solution than in the 0.1% Na2S solution. In contrast, the corrosion rate of the Ag-Pd-Cu alloy was approximately 500 times higher in the 0.1% Na2S solution than in Ringer's solution. The results show that the generally accepted concept that tarnish is merely a surface discoloration due to the deposition of insoluble products is inadequate. The alloy discolors while being severely attacked in the presence of sulfides. For the Ag-In alloy, the corrosion activity in the 0.1% Na2S solution was as high as in Ringer's solution. These silver-based alloys exhibit different electrochemical activities in different solutions. The test solutions for corrosion tests must be carefully chosen for each alloy system through a screening test to replicate the predominant corrosion reaction proceeding in the oral environment.     

Antiulcer activity of eel-calcitonin (elcatonin) is associated with enhanced gastric mucosal PGE2 generation in the rat

Elcatonin is a newly synthetized peptide that prevents experimental ulcer formation. In this study, we examined the influence of elcatonin on endogenous prostaglandin biosynthesis by the gastric mucosa with respect to its antiulcer activity. Control levels of PGE2 generation for the fundic and antral mucosa were 302 +/- 12 and 465 +/- 28 ng/g tissue/min, respectively. Pretreatment with elcatonin resulted in a dose-dependent increment in gastric mucosal PGE2 generation. We conclude that the antiulcer effect of elcatonin is probably due to its ability to enhance endogenous prostaglandin synthesis in the gastric mucosa.     

Gastric mucosal protection induced by restraint and water-immersion stress in rats.

We found that the gastric mucosal lesion induced by 60% ethanol containing 150 mM HCl was reduced by pre-loading the rat with restraint and water-immersion stress (22 degrees C). The resistance to ethanol injury was maximal in 1-hr stress loaded rats and gradually decreased with increasing time of stress (2-6 hr). The protective effect of stress was markedly decreased by subdiaphragmatic truncal vagotomy, and electrical stimulation of vagal nerves afforded similar protection as observed after stress. In contrast, pretreatment with atropine markedly reduced ethanol injury in both the control and 1 hr stress-loaded rats. One-hour stress produced surface epithelial cell damage in sham vagotomized rats, but the surface cells were almost intact in vagotomized rats. Pretreatment with indomethacin significantly mitigated the protective effect of stress against ethanol injury. However, the level of mucosal prostaglandin E2 was not changed 1 hr after stress, and it tended to decrease 6 hr after stress. Pretreatments with 1-hr stress and vagal stimulation weakly reduced localized staining of gastric mucosa with gentian violet. We conclude that adaptive protection can be achieved by restraint and water-immersion stress.     

A note on methods for estimating the number of patients in the nationwide epidemiological survey on intractable diseases

To find the most adequate method for estimating the number of patients in nationwide epidemiological surveys of intractable diseases, we examined six existing methods using reported data on 13 selected diseases. Estimated numbers of patients by the methods, except for methods with theoretical inadequacy or other problems, were almost equal to each other. The simple method, by which the number of patients is estimated as the reported one divided by the response rate, is recommended.     

Hypercalcemia related to the poor prognosis of patients with squamous cell carcinoma of the esophagus

A review of 208 cases of surgically treated squamous cell carcinoma of the esophagus revealed 16 (7.7%) with hypercalcemia. There was no evidence of bone metastases in 13 (6.3%) of the patients with hypercalcemia. Pathogenesis of this hypercalcemia without bone metastases was suggested to be multifactorial. Anastomotic leakage and malnutrition because of fasting were the most possible causes of mild hypercalcemia, and moderate to severe hypercalcemia was thought to be due to subclinical and clinical recurrence of the tumor, probably with PTH-like hormonal activity. Overall survival rates in the groups with and without hypercalcemia were 18.2 and 61.7% at the 12th postoperative month and 9.1 and 37.8% at the 24th month, respectively. Thus hypercalcemia is a significant prognostic factor linked to an unfavorable clinical course even in patients with no evidence of bone metastases.     

Morphological studies of peripheral nerves and skeletal muscles of an adult case with adrenoleukomyeloneuropathy

A 53-year-old patient with adrenoleukomyeloneuropathy, showing symptoms of mental deterioration, cerebellar ataxia, spastic tetraparesis, and polyneuropathy, was reported. The myelinated fiber densities were decreased in the anterior spinal root and sciatic nerve. Most of the myelinated fibers showed segmental demyelination and a few fibers showed axonal degeneration. Electron microscopy showed numerous lipid inclusions in the cytoplasm of the Schwann cells. The muscles showed neurogenic changes. Numerous lipid bodies and intracytoplasmic crystalline arrays were found in the sarcolemma.     

Clinical study on the effect of human lymphoblastoid interferon in multiple myeloma

Ten patients with multiple myeloma were treated with human lymphoblastoid interferon (HLBI). The dosages used were 3 X 10(6) IU to 6 X 10(6) IU of HLBI intramuscularly daily. Out of eight evaluable patients, one partial remission and 3 minor response were observed. More than half patients experienced fever exceeding 38 degrees C and mild myelosuppression. Other toxic effects consisted of anorexia, malaise, liver dysfunction and skin rash. On the basis of our preliminary study, we conclude that HLBI is an effective agent against multiple myeloma.