Human platelet polyphosphate (polyP) is a multifunctional molecule; however, its functions are not yet fully understood. A recent study demonstrated that similar to skeletal muscle, polyP is involved in energy metabolism in platelets, which suggests that well-trained athletes may exhibit elevated platelet polyP levels for energy storage. To test this hypothesis, we quantified platelet polyP along with NADH, a component involved in ATP production in non-trained and well-trained male Japanese participants of the same generation. Washed platelets were prepared from the venous blood of young, healthy, non-athletes, and professional soccer players (pro-athletes). NADH and polyP levels were spectrophotometrically determined using tetrazolium reduction and fluorometrically determined using 4′,6-diamidino-2-phenylindole at the excitation/emission wavelengths of 425/525 nm. Body weight and impedances were measured simultaneously. Statistical analyses were performed using the Mann-Whitney U test and Spearman correlation coefficient. Although basal metabolic rate levels were significantly higher, platelet polyP levels were significantly lower in pro-athletes than in that in non-athletes. No significant differences were detected in other body compositions or platelet indices between the two groups. The pro-athlete group showed a moderate, nearly significant correlation (R = 0.439; p = 0.0512) between platelet polyP and NADH levels. Taken together with the weak correlation data between polyP and body mass index, it is suggested that platelet polyP levels may be influenced by platelet and body energy metabolic activity. Further biochemical studies are needed to elucidate this mechanism.

The levels of the soluble intercellular adhesion molecule 1 (sICAM-1) and soluble granule membrane protein-140 (sGMP-140) were measured in middle ear effusions (MEEs) of otitis media (OM) with ELISA. MEEs of chronic serous and mucoid OM in children contained significantly higher levels of sICAM-1 and sGMP-140 compared with normal serum. sGMP-140 in acute and chronic OM in children was higher than in adult chronic serous OM, and in acute purulent OM higher chronic serous OM in children. Cytologic analysis showed that the mean level of sGMP-140 was significantly higher in the neutrophil dominant group than in other groups except the few cells type. sICAM-1 showed no differences among the cytologic classifications. Copious amounts of sICAM-1 and sGMP-140 in MEEs were observed in this study, and were probably the result of shedding from the cells expressed cell adhesion molecules. These cell adhesion molecules in MEEs were thought to modify the inflammatory response in OM.

The presence of mucosa-associated lymphoid tissue (MALT) was investigated histopathologically in every 20th section from 99 vertically cut, celloidin-embedded temporal bone-eustachian tube (ET) specimens. Among specimens from infants and children between 1 month and 7 years of age, MALT was found in 22 of 44 (50%). However, in 26 adults over 18 years of age, MALT was found in only 2 specimens (7.7%), a significantly lower incidence than that in infants and children. Moreover, MALT did not appear in any of the 21 neonates under the age of 1 month. All 99 specimens were classified into 2 groups: 41 specimens with otitis media (OM) and 58 specimens without OM. The presence of MALT was significantly higher in specimens with OM (43.9%) than in specimens without OM (13.8%). Mucosa-associated lymphoid tissue was found in the ET, middle ear, and mastoid process in 18 specimens (43.9%). 5 specimens (12.2%), and 1 specimen (2.4%) with OM, respectively, and in 8 (13.8%), 0, and 0 specimens without OM. In regard to the distribution of MALT, it occurred more frequently in the pharyngeal half of the cartilaginous portion of the ET than in the rest of the ET, middle ear, and mastoid; the presence was significantly greater in the inferior half of the cartilaginous portion of the ET than in the superior half. Inflammatory cell infiltration in the cartilaginous and bony portions of the ET was significantly greater in specimens with OM than in specimens without OM with no MALT. However, even in some specimens without OM, inflammatory cells were found in the ET, particularly in the pharyngeal half of the cartilaginous portion of the ET. These findings suggest that MALT has a close relationship to OM and that it may be a local response to repeated infection.

The mechanism of long-term B cell immunity against donor blood group antigens in recipients who undergo ABO-incompatible (ABOi) living-donor kidney transplantation (LKTx) is unknown. To address this question, we evaluated serial anti-A and anti-B antibody titers in 50 adult recipients. Donor-specific antibody titers remained low (≤1:4) in 42 recipients (84%). However, antibodies against nondonor blood group antigens were continuously produced in recipients with blood type O. We stimulated recipients' peripheral blood mononuclear cells in vitro to investigate whether B cells produced antibodies against donor blood group antigens in the absence of graft adsorption in vivo. Antibodies in cell culture supernatant were measured using specific enzyme-linked immunosorbent assays (ELISAs). Thirty-five healthy volunteers and 57 recipients who underwent ABOcompatible LKTx served as controls. Antibody production in vitro against donor blood group antigens by cells from ABOi LKTx patients was lower than in the control groups. Immunoglobulin deposits were undetectable in biopsies of grafts of eight recipients with low antibody titers (≤1:4) after ABOi LKTx. One patient with blood type A1 who received a second ABOi LKTx from a type B donor did not produce Bspecific antibodies. These findings suggest diminished donor-specific antibody production function in the setting of adult ABOi LKTx.

Platelets produce inorganic polyphosphate (polyP) upon activation to stimulate blood coagulation. Some researchers have linked polyP metabolism to ATP production, although the metabolic linkage is yet to be elucidated. We found evidence for this possibility in our previous study on professional athletes (versus non-athletes), and proposed that the regulatory mechanism might be different for these two groups. To explore this aspect further, we investigated the effects of modulated ATP production on polyP levels. Blood samples were obtained from Japanese healthy, non-athletes in the presence of acid-citrate-dextrose. The platelets in the plasma were treated with oligomycin, rotenone, and GlutaMAX to modulate ATP production. PolyP level was quantified fluorometrically and visualized using 4′,6-diamidino-2-phenylindole. Correlations between polyP and ATP or NADH were then calculated. Contrary to the hypothesis, inhibitors of ATP production increased polyP levels, whereas amino acid supplementation produced the opposite effect. In general, however, polyP levels were positively correlated with ATP levels and negatively correlated with NADH levels. Since platelets are metabolically active, they exhibit high levels of ATP turnover rate. Therefore, these findings suggest that ATP may be involved in polyP production in the resting platelets of non-athletes.