Differential effects of methylmercury on the synthesis of protein species in dorsal root ganglia of the rat

Dorsal root ganglia from control and methylmercury(MeHg)-treated rats were incubated in vitro with ³⁵S-methionine ant the proteins synthesized were analyzed by two-dimensional electrophoresis. The double labelling method, in which proteins of control dorsal root ganglia labelled in vitro with ³H-leucine were added to each of the two samples as an internal standard, was used to minimize unavoidable errors arising from the resolving procedure itself. The results obtained showed that the effect of MeHg on the synthesis of proteins in dorsal root ganglia was not uniform for individual protein species in the latent period of MeHg intoxication. Among 200 protein species investigated, 157 showed inhibition of synthesis close to that of the total proteins in the tissue (68% of the control). Among the remaining protein species, 20 showed real stimulation of synthesis, whereas 7 were moderately inhibited and 16 were inhibited more strongly than the total proteins in the tissue. These results suggest that the effect of MeHg on the synthetic rates for protein species in dorsal root ganglia differs with the species, and that unusual elevation or reduction of the synthesis of some protein species caused by MeHg may lead to impairment of normal nerve functions.This work was supported in part by a grant from the Japanese Environmental Agency     

Lasting increase in D1 dopamine receptors in the lateral part of the substantia nigra pars reticulata after subchronic methamphetamine administration

To examine the possible involvement of D₁ dopamine receptors in behavioral sensitization induced by subchronic methamphetamine (MAP) administration, regional D₁ receptors labeled with [³H]SCH 23390 were examined using binding assay and quantitative autoradiography. Rats received 4 mg/kg/day MAP (i.p.) for 14 days, and were decapitated after an abstinence period of 24 h, 7 days or 21 days. In MAP-treated rats, a significant decrease in K_d in the mesolimbic area was observed 24 h but not 7 days after the last injection. Neither K_d nor B_max changed in the striatum or medial prefrontal cortex of MAP-treated rats after any period of abstinence. Autoradiography revealed a significant increase in specific [³H]SCH 22390 binding in the lateral part of the substantia nigra pars reticulata (SNr) of MAP-treated rats. Since this increase lasted up to 21 days after cessation of subchronic MAP administration, it is suggested that lasting increase in the nigral D₁ receptors may be associated with the biological changes underlying MAP-induced behavioral sensitization.     

Establishment of a cell line with phenotypes of chondrocyte from a human osteogenic sarcoma of the mandible

We have succeeded in transplanting a human osteogenic sarcoma of the mandible into athymic mice. The transplanted tumor showed marked chondrogenesis and mineralization. Recently, a cell line (USAC) with phenotypes of chondrocyte has been established from the transplanted tumor. USAC cells were stellate or spindle-shaped in sparse culture, but polygonal or spherical at sub-confluency to confluency. In long-term culture, the cells were condensed and calcified nodules were formed. Production of types I, II and X collagen were detected by immunohistochemical staining and Western blot analysis. Type I collagen was strongly expressed in the stellate or spindle-shaped cells. Although type II collagen was usually present in all cells during culture, it was strongly stained in polygonal cells at confluency. Type X collagen was seen in large polygonal cells around calcified nodules. Marked [35S]-sulfate uptake and metachromasia were seen at the confluent stage and in the nodule. The cells around the nodules were positive for alkaline phosphatase, and the center of the nodules was stained with alizarin red. The potentiality of cartilage formation was confirmed by in vivo experiments using a diffusion chamber in athymic mice. These observations indicate that USAC cells maintain characteristics of chondrocyte progenitor cells and thus may serve as a useful model to study the sequential events of chondrogenesis and the process of morbid endochondral calcification. This experiment also demonstrated that transplantation of tumor tissue into athymic mice is a convenient strategy for establishment of a cell line.     

Relationship between free-running period and motor activity in blinded rats

The free-running rhythms of motor activity in blinded rats were measured by two different devices, an Automex or a running wheel. The period of free-running rhythm measured by a running wheel was likely to be shorter than that measured by an Automex, indicating that subtle environmental difference, such as whether a cage is equipped with a wheel or not, can affect the free-running period. In addition, we found a negative correlation not only between the free-running period measured by a running wheel and that measured by an Automex, but between the free-running period and the number of wheel revolutions per day. This is the first evidence that motor activity, other than the external factors such as light intensity and temperature, may be related to change in the free-running period.     

Gastric Wall Structure Using a 30 MHz Endoscopic Ultrasound Probe,Focusing upon Delineation of the Muscularis Mucosae

Background: The normal gastric wall has been reported to appear to be a five‐layered structure. The structure of the gastric wall using a 30 MHz endoscopic ultrasound probe and especially the identification of the muscularis mucosae (MM), has not been analyzed clearly. Methods: In a basic study, 11 sections of normal gastric wall with 26 horizontally inserted nylon sutures were immersed in water. The sections were scanned and the findings correlated using standard histology. In a clinical study, 15 early gastric cancers were examined by a 30 MHz endoscopic ultrasound probe. Results: In a basic study, layers deeper than the lower part of the submucosa could not be seen using ultrasonography. The first to fourth layers represented the mucosal layer except the MM, the fifth layer (high‐echo layer) represented the boundary echo and a part of the MM, while the sixth layer (low‐echo layer) represented the rest of the MM. The muscularis mucosae was seen clearly in all samples. In a clinical study the layers deeper than the submucosal layer could not be seen and the MM was visible in 87% of cases. The depth of invasion was estimated accurately in 90% of mucosal cancers and in 80% of submucosal cancers. Conclusion: A 30 MHz endoscopic ultrasound probe, which cannot image the entire gastric wall, can visualize the MM and may help to confirm the structure of gastric wall layers and improve the ability to determine the depth of invasion in gastric cancer.     

Pneumatosis Cystoides Intestinalis Following Steriod Pulse Therapy in a Patient with Polyarteritis Nodosa

We present a case of a 67‐year‐old female with polyarteritis nodosa, complicated by pneumatosis cystoides intestinalis. The definite diagnosis of polyarteritis nodosa was obtained by histological findings on a biopsy specimen from her sural nerve. Following steroid pulse therapy, she developed gastrointestinal symptoms such as nausea, abdominal fullness and watery diarrhea. Abdominal X‐ray and computed tomography showed an abundance of gas contrast within the large intestinal wall. Colonoscopy revealed submucosal tumor‐like multiple elevated lesions from the sigmoid to transverse colon. These findings indicated pneumatosis cystoides intestinalis and the patient was accordingly treated with a high concentration of oxygen via a nasal catheter. One week later, her symptoms and the gas in the bowel wall completely disappeared. Pneumatosis cystoides intestinalis may be one of the complications of steroid pulse therapy.     

A case of endocrine carcinoma of the sigmoid colon]

We report a case of endocrine carcinoma of the sigmoid colon. A 71-year-old man was admitted to our hospital because of constipation and bloody stool. Colonoscopy showed a mass lesion with irregular ulceration in the sigmoid colon. He was given a diagnosis of the poorly differentiated adenocarcinoma of the colon, and underwent sigmoidectomy with dissection of the lymph nodes. Histological and immunohistochemical examinations of the resected specimen revealed endocrine carcinoma. Endocrine carcinoma of the colon is rare, and the prognosis is very poor. We discuss this case with references.