Intrathymic lymph nodes in humans.

An unusual lymph node exists in the centre of the human thymus. This lymph node, which we call an intrathymic lymph node (ITLN), possesses some interesting morphological characteristics. In ontogeny, this node seems to appear at the latter half of fetal period. The function of the ITLN is still unknown, but it is assumed that it may play a different role in the immune system than other peripheral lymph nodes by its characteristics.

Puromycin-sensitive alanyl aminopeptidase from human liver cytosol: purification and characterization.

A cytosolic alanyl aminopeptidase (AAP-S) was purified to homogeneity from human liver cytosol. The molecular weight of the purified enzyme was calculated to be approximately 98,000 on TOF-MS and 90,000 on SDS-PAGE in the presence of beta-ME. These findings suggest that the enzyme exists as a monomeric form in human liver cytosol. The enzyme rapidly hydrolyzed the substrates Ala-, Lys- and Phe-MCAs, and moderately hydrolyzed Met-, Leu-, Tyr- and Lys-Ala-MCAs at pH ranging from 7.5 to 8.0. The order of the K(cat)/K(m) values of AAP-S at the optimal pH was Arg->Arg-Arg->Met->Leu->Lys->Phe->Lys-Ala->Tyr->Ala-MCAs. It was strongly inhibited by bestatin, leuhistin, actinonin, amastatin, 1, 10-phenanthroline, DFP, PCMBS, Zn(2+), Cd(2+), Co(2+), Cu((2+)), Hg(2+) and puromycin. AAP-S was approximately 80 times more sensitive than human seminal plasma AAP (aminopeptidase N, membrane type). The amino acid sequence of the first 60 residues of AAP-S was highly homologous with the N-terminal amino acid sequence of the rat liver puromycin-sensitive enkephalin-degrading aminopeptidase. These physicochemical properties and findings indicate that AAP-S from human liver cytosol is identical to those of other puromycin-sensitive aminopeptidase(s). Furthermore, with immunohistochemistry the enzyme was strongly stained in the cytoplasm of liver cells and renal tubules, and was ubiquitously localized in various human tissues.

Lectin-histochemical detection of degenerative glycoconjugate deposits in human brain.

Several lectins were used to study the localization of glycoconjugates in brain of elderly people and patients with Alzheimer type dementia (ATD) and Down's syndrome (DS). Five kinds of degenerated or deposited materials stained clearly by lectins specific to GalNAC, Gal, Fuc, and/or Man were recognized much in ATD and DS, less in elderly peoples, in addition to the binding of the lectins to neurons. (i) Round shape deposits called corpora amylacea (CA) which consisted of various sizes of round material, existed mainly on the surface of cerebral cortex and some in white matter of the brain. They were colored by Alcian blue (AB), Aldehyde fucsin (AF) and periodic acid shiff (PAS) and weakly by Hematoxylin (H), but not by Eosin (B). They showed clear reactivity with lectins specific to GalNAC, Gal, Fuc and Gal-GalNAC. (ii) Amorphous and variform amyloid deposits existed around blood vessels in the white matter were stained by thioflavin and lectins specific to GalNAC, Gal and Fuc, but not with Man specific lectins and PAS, AB, AF and HE. (iii) Another kind of amyloid deposits which showed a similar characteristic to the previous one and were recognized mainly in white matter and independent blood vessels. These deposits were stained by thioflavin but not by PAS, AB, AF and HE and showed good reactivity with lectins specific to GalNAC, Gal, Fuc, Gal-GalNAC, Gal-GIcNAc and Man. The reactivity with lectins specific to Gal, Fuc, and Man was seen in senile plaques (iv) and neurofibrillary tangles (v). Although at present we are unable to explain the origin of these deposits, it is clear from this study that the glycoconjugates form an integral part of the degeneration in the brain. The lectin staining with GS-I is useful in the forensic pathology to diagnose brain disorders at postmortem examination, since these lectin were able to detect five types of degeneration changes and/or deposits.

Phylogenetic analysis of picoplankton in Lake Biwa and application to legal medicine.

Three strains of picoplankton designated as brown, green, and pink belonging to the Synechococcus genus in cyanobacteria (approximately 1 microm in size) are found ubiquitously in Lake Biwa, Japan. However, they could not be morphologically discriminated from other bacteria such as Proteobacteria and Bacillus by microscopy. In this study, we attempted to use the polymerase chain reaction (PCR) analysis of the 16S ribosomal DNA (rDNA) from picoplankton for the diagnosis of death by drowning. A segment of 16S rDNA was sequenced in order to investigate their phylogenetic relationships and to design the specific primers. The PCR products from three picoplanktons were compared with those from five other cyanobacteria, Melosira (diatom), Staurastrum (green alga), bacteria from Lake Baikal, and humans. The picogram order of template DNA from picoplankton was specifically amplified by the primers. When the template of picoplankton was mixed with human tissue, at least 10 ng of template DNA was needed to obtain a PCR product. The efficiency of PCR was increased more than hundredfold by isolating the picoplankton from human lung tissue. The specific PCR products of the picoplankton were obtained from a formalin-fixed drowning body (lung and liver) that was found in a downstream river and Lake Biwa. The PCR analysis of the picoplanktion 16S rDNA is considered useful for the diagnosis of death by drowning.

Tissue-specific expression of Le(Y) antigen in high endothelial venules of human lymphoid tissues.

In this study, we demonstrated that the anti-Le(Y) antibody (BM-1) especially reacted with high endothelial venules (HEVs) in peripheral lymph nodes of blood group O individuals. The Le(Y) expression on HEVs showed a unique tissue-specific pattern, i.e., a large amount of the Le(Y) expression in peripheral lymph nodes and no or small amounts in mesenteric lymph node. Statistical analysis showed that there was the significant difference between the percentage of Le(Y)-positive HEVs in peripheral lymph nodes and mesenteric lymph nodes. No expression of Le(Y) was observed in vessels of Payer's patch, thymus, spleen and other non-lymphoid organs. In blood group A or B individuals, the reactivity between HEVs and anti-Le(Y) antibody increased after enzyme digestion with alpha-N-acetylgalactosaminidase or alpha-galactosidase. These findings show that the expression of difucosylated blood group ABH antigens are especially expressed on HEVs in peripheral lymph nodes. Furthermore, the tissue-specific pattern suggests that these antigens may be related to intercellular adhesion between lymphocytes and HEVs.

[An autopsy case of a bicycle accident with ring fracture at the base of the skull].

We report the autopsy case of a 41-year old passenger who suffered a significant head injury with a typical ring fracture at the base of the skull as a result of a violent fall from a bicycle. Several reports about ring fractures of the base of the skull revealed that they were due to crashing a car at high speed, a collision and/or a fall while riding a motorcycle and a fall in piloting a gyrocopter and so on resulting in severe injury to another part of the body. In this case, the ring fracture occurred when his spine was pushed up by high impact of the parieto-occipital region against the ground.

Changes in choice of method and lethality between last attempted and completed suicides: how did suicide attempters carry out their desire?

Some researchers have emphasized that, from the perspective of suicide prevention, research into the methods of suicide seemed to be particularly promising, as it has been shown repeatedly that restricting access to the prevailing method of suicide in a country will decrease suicide rates and that the lethality of the method used significantly correlated with the degree of intention to die. In this study, we examined changes in choice of method and the lethality score between the last attempted suicide (LAS) and completed suicide (CS) in 416 victims (male: 197, female: 219) to point out the tendency on their choice of method in LAS and CS. There was a significant difference in choice of suicide method between LAS and CS, and injury to themselves (33.7%) was the most common method of LAS, while hanging (37.5%) was the most common method of CS. The mean lethality score of CS method was significantly higher than that of LAS method in both sex groups, suggesting that at least one of the causes that drives suicide attempters to commit suicide finally may be the difference in the lethalities of LAS and CS. At the time of CS, suicidal victims tend to choose the same method as that of LAS again. These findings suggest that although suicide attempters tend to choose the same method, they will use a more lethal method if they change the suicide method. Interestingly, moreover, there was no sex difference in the percentage of the mean lethality score at CS.

Characterization of new oral antidiabetic agent CS-045. Studies in KK and ob/ob mice and Zucker fatty rats.

CS-045 is a new oral antidiabetic agent that was effective in insulin-resistant diabetic animal models, including the KK mouse, the ob/ob mouse, and the Zucker fatty rat. CS-045 was not effective in the streptozocin-treated mouse, an insulin-deficient diabetic animal model. In fed KK mice, CS-045 lowered the plasma glucose levels in a dose-dependent manner after a single oral administration, and the hypoglycemic effect lasted for at least 18 h. In normal rats, however, plasma glucose levels were not changed after administration of CS-045. CS-045 when given chronically (2 wk) to diabetic KK and ob/ob mice as a 0.2% food admixture dramatically improved hyperglycemia, hyperinsulinemia, and hypertriglyceridemia to near-normal values and decreased plasma lactate, free fatty acid, and ketone body levels without reducing food intake or body weight. In the obese Zucker fatty rat, oral administration of CS-045 had a similar effect in lowering plasma glucose, insulin, triglyceride, free fatty acid, lactate, and ketone body levels. The CS-045-treated Zucker fatty rats showed increased glucose tolerance and decreased insulin secretion in response to oral glucose. After 9 days of treatment, insulin binding to adipocyte plasma membranes from both CS-045-treated Zucker fatty rats and KK mice was increased. Furthermore, 2-deoxyglucose uptake in CS-045-treated adipocytes was increased and the insulin dose-response curve was shifted to the left. These findings suggest that CS-045 increases not only insulin sensitivity but also insulin responsiveness. Based on its pharmacological profile, CS-045 is a new orally effective antidiabetic agent that may reduce abnormalities of glucose and lipid metabolism in obese and non-insulin-dependent diabetes mellitus patients with insulin resistance.