Induction of apoptotic cell death in rat thymus and spleen after a bolus injection of methamphetamine

We examined whether methamphetamine (MAP) induced apoptotic cell death in vivo. Male Wistar rats were injected intraperitoneally with 25 mg MAP/Kg body weight and were sacrificed at 4, 8 and 24 h. As early as 4 h after a single dose of MAP, DNA ladder bands representing DNA fragmentation into multiples of the internucleosomal DNA length of about 180 by were observed by gel electrophoresis in thymic and splenic DNA. DNA from control rats injected with 1 ml physiological saline/Kg body weight showed no ladder band patterns. The proportion of fragmented DNA from the thymus increased in a time-dependent manner up to 8 h and faint ladder band patterns were observed at 24 h, indicating that cell death via apoptosis occurred at an early stage and then apoptotic bodies were scavenged. DNA fragmentation in the thymus and spleen induced with MAP was also confirmed by the terminal deoxynucleotidyl transferase-mediated dUTPbiotin nick end labeling (TUNEL) method in situ. In control thymus samples, stained cells were numerous in the cortex but sparse in the medulla. At the boundary area between the cortex and medulla, stained cells were seen as a layer. In the MAP-treated rats, stained cells were increased and dispersed equally in the cortex and medulla. In control spleen samples, stained cells were numerous in all areas excluding the germinal centers. Cells at the germinal centers were stained intensively in MAP-treated rat spleen. Light microscopical analyses allowed us to identify lymphocytes during the course of apoptotic cell death. Electron microscopic studies showed morphological landmarks for the process of cellular apoptosis in both organs e.g. lymphocytes with chromatin condensed into crescents at the periphery of the nuclei and apoptotic bodies. These results indicate that MAP induced cell death of the thymic and splenic lymphocytes via apoptosis.     

Effects of total parenteral nutrition with nucleoside and nucleotide mixture on D-galactosamine-induced liver injury in rats

The effect of a nucleoside-nucleotide mixture on liver injury of rats induced by D-galactosamine was studied by examining changes in function and histopathology of the liver. Animals with liver damage received total parenteral nutrition with glucose and amino acids supplemented with a nucleoside-nucleotide mixture containing inosine, cytidine, GMP, uridine and thymidine, or with uridine which inhibits galactosamine injury, or with liver cell extract containing flavin adenine dinucleotide and nucleic acid derivatives. As control, animals with liver damage received total parenteral nutrition with glucose and amino acids only. The serum GOT and GPT concentrations were significantly lower in the group supplemented with nucleoside-nucleotide mixture than those in other groups. A large dose (1.2 g/kg) of uridine inhibited liver injury, but a lower dose (0.14 g/kg) did not have any effect, whereas nucleoside-nucleotide mixture containing the same amount of uridine inhibited the injury. Liver cell extract also did not improve liver function. Thus infusion of a physiological and balanced mixture of nucleosides or nucleotides may improve liver function in rats with liver injury.     

Modification of the Na,K-pump of glial cells within cobalt-induced epileptogenic cortex of rat

The characteristics of a glial Na⁺,K⁺-pump dependent on extracellular K⁺ within epileptogenic cortex were studied electrophysiologically, biochemically and histochemically in vitro using slices from cobalt-induced epileptogenic cortex of rat. When the extracellular K⁺ concentration ([K⁺]_o) was varied between 4 and 40 mM, the mean slope of membrane potential plotted against [K⁺]_o was about 57 mV in glia from the normal cortex (tissue A) and about 44 mV in glia from the epileptogenic cortex (tissue B); whereas no significant difference in the resting membrane potential of these tissues was observed. In glia from tissue B, a marked transient hyperpolarization above control level was caused by replacement of elevated [K⁺]_o with the normal medium. Ouabain abolished these phenomena observed in glia from tissue B, but had no effect on the membrane potential during normal [K⁺]_o. Reduction of extracellular Na⁺, Ca²⁺ and Cl⁻ did not significantly affect the membrane potential of glia from either tissue. In tissue A, the cells marked by intracellular injection of horseradish peroxidase after intracellular recording were protoplasmic astrocytes; in tissue B, fibrous astrocytes with abnormal processes predominated. K⁺-dependent stimulation of Na⁺,K⁺-ATPase activity of the astrocyte-enriched fraction and its membrane preparation from tissue B was much larger than that from tissue A. A certain amount of the reaction product of K⁺-pNPPase activity was seen on glial plasma membrane within tissue B but not on that from tissue A. The above findings suggest that a glial Na⁺,K⁺-pump within actively firing epileptogenic cortex may be modified to increase in its activity.     

Ultrastructure of lentigo maligna in the oral cavity

A rare case of lentigo maligna in the oral cavity was investigated by light and electron microscopy. Cutaneous lentigo malignas often develop to malignant melanomas. However, the electron microscopic examination revealed that even though there were a large number of melanosomes, most of them were late stage and had membrane structure, and positive staining with HMB-45 was not recognized. From our findings, it is difficult to conclude that oral lentigo malignas develop malignant melanomas, and thus further studies are needed.     

Modes of hantavirus transmission in a population of <Emphasis Type="Italic">Clethrionomys rufocanus bedfordiae</Emphasis> inferred from mitochondrial and microsatellite DNA analyses

Summary. To elucidate the mode of transmission of Puumala-related hantavirus in a population of gray red-backed voles, Clethrionomys rufocanus bedfordiae, in Hokkaido, Japan, we analyzed the kin structure and dispersal patterns of individual voles using microsatellite and mitochondrial DNA markers. Siblings or dam/offsprings was identified within the population based on the relatedness calculation with the microsatellite data. The pairwise relatedness values obtained could reveal kinship among all vole individuals within the population. Based on the assessment of kinship, we did not find a positive relationship between hantavirus transmission and close kinship. Males infected with the hantavirus carried a relatively uncommon mitochondrial haplotype. However, these infected males shared low relatedness values and were not considered closely related, i.e., they were not siblings or parent/offspring. These observations imply that hantavirus transmission in the vole population may not be related to close kinship but by random horizontal infection.     

Oral squamous cell carcinoma: electron microscopic and immunohistochemical characteristics

Oral squamous cell carcinoma is the most common oral malignancy, and we performed electron microscopic and immunohistochemical investigation of the tumor. In patients with cervical metastasis, microvilli were developed and a small number of desmosomes were found, regardless of the width of the intercellular spaces. In patients without the metastasis, few microvilli were found in relatively wide intercellular spaces, or numerous microvilli were found in narrow intercellular spaces, and a large number of desmosomes were shown. However, these findings were different from those of tumors that had received radiotherapy, in which numerous microvilli and a small number of desmosomes were found in the nonmetastatic cases. Transferrin receptor, which is a marker of cell proliferation, was localized on the cell membrane, especially in microvilli. Ultrastructural similarity between the primary tumor and the metastatic tumor was recognized, however, the features of microvilli, desmosomes, and the intercellular spaces differed between them in most cases. It is suggested that microvilli might be related to the metastasis of oral squamous cell carcinoma cells. Immunohistochemically, the protein expression of p53 and pRb2/p130 was related to the clinical course of the patients with oral squamous cell carcinoma; the mechanism of the synthesis of these proteins should be investigated in order to understand the biological behavior of the tumor.     

Ultrastructure of oral sarcoma

Sarcoma of the oral region is extremely rare and ultrastructural studies of the tumor are limited in number. We collected oral sarcomas, such as fibrosarcoma, malignant fibrous histiocytoma, liposarcoma, leiomyosarcoma, rhabdomyosarcoma, angiosarcoma, alveolar soft-part sarcoma, solitary plasmacytoma, and osteosarcoma, and performed ultrastructural studies of these tumors. The value of these studies for an understanding of the biological behavior of the tumors was then investigated. In these studies, electron microscopic examinations of oral sarcoma were of assistance in our attempt to establish correct diagnosis and histogenesis. Data from the studies of oral sarcoma by light microscopy, electron microscopy, and immunohistochemistry should be accumulated.