Prevalence and correlates of carotid atherosclerosis among elderly Japanese men

We determined intima-media thickness (IMT) and diameter of carotid artery and estimated their correlations with cardiovascular risk factors in 1129 men aged 60-74 years, who participated in a cardiovascular risk survey in three Japanese communities. The multivariate odds ratios (95% confidence interval) for the maximum IMT > or = 1.1 mm in the common carotid artery (CCA) were 1.3 (1.1-1.5) per 4 years of age, 1.8 (1.4-2.5) for hypertension, 1.4 (1.2-1.7) for a 34.4 mg/dl increase in serum total cholesterol, 0.7 (0.6-0.8) for a 14.7 mg/dl increase in serum HDL-cholesterol, and 2.4 (1.1-5.0) for history of stroke, while the maximum IMT > or = 1.5mm in the internal carotid artery (ICA) were 1.6 (1.4-1.8) per 4 years of age, 1.9 (1.5-2.4) for hypertension, 1.6 (1.2-2.1) for current smoking, and 3.5 (1.6-7.6) for history of stroke. Age, height, hypertension, current smoking, ethanol intake and history of coronary heart disease were independent determinants of both the outer and inner CCA diameter. Maximum IMT correlated positively with the outer diameter and inversely with the inner diameter in the CCA. Carotid atherosclerosis suggests to be a risk factor for stroke among Japanese elderly men, although future prospective studies are required to confirm this finding.     

Regeneration of granule neurons after lesioning of hippocampal dentate gyrus: evaluation using adult mice treated with trimethyltin chloride as a model

The hippocampal dentate gyrus in adult animals is known to contain neural progenitors that proliferate and differentiate into neurons in response to brain injury. Little has been observed, however, on regeneration of the granule cell layer of the dentate gyrus that has been directly injured. Using trimethyltin (TMT)-treated mice as an in vivo model, we evaluated the ability of this layer to regenerate after injury. The administration of TMT induced neuronal death in the dentate gyrus selectively 2 days later, with recovery of granule neurons on day 14 and thereafter. At an early stage (days 2-5) after the damage by TMT treatment, 5-bromo-2'-deoxyuridine (BrdU) incorporation into at least two different types of cells was facilitated in the dentate gyrus: BrdU-positive/neuronal nuclear antigen (NeuN)-negative cells were found predominantly in the subgranular zone and granule cell layer, whereas BrdU-positive/NeuN-positive cells were numerous in the dentate molecular layer and hilus. In addition, expression of proliferating cell nuclear antigen, nestin, NeuroD3, and doublecortin, which are markers for proliferating cells and neural progenitors/neuronal precursors, was extremely enhanced in the dentate gyrus at the early stage after treatment. Double staining revealed that BrdU was colocalized with nestin and doublecortin in the subgranular zone. Behavioral analysis revealed that TMT-induced cognition impairment was ameliorated by day 14 after the treatment. Taken together, our data indicate that the hippocampal dentate gyrus itself is capable of regenerating the neuronal cell layer through rapid enhancement of neurogenesis after injury.     

Clinical analysis of HLA-DR-negative non-M3 AML

The type of leukemia was defined as HLA-DR(-) non-M3-AML, when HLA antigens were detected by flow cytometry at an incidence of < 20% of the blast population excluding M3-AML. Out of 109 patients with de novo acute myeloid leukemia, 8 patients had HLA-DR(-) non-AML-M3. According to the French-American-British criteria, 7 patients could be subdivided into 3 patients with M1, 4 patients with M2 and 1 patient with M4. The morphological features of bone marrow aspiration demonstrated no dysplasia and peroxidase stain positivity was noted in over 86% of the blast cells in all patients, the blast cells with fine granularity in 7 patients. The cytogenetic analysis revealed a normal karyotype. There was no expression marker of the blast antigens except CD13, CD14, CD33, CD34 and CD56. All of 7 patients who underwent induction therapy attained complete remission. Overall survival and disease-free survival showed no significant differences between the HLA-DR(-) non- M3-AML group and the HLA-DR(+) AML group.     

Endotoxin contamination in wound dressings made of natural biomaterials

Contamination by endotoxin of nine kinds of wound dressings made of natural biomaterials (calcium alginate, collagen, chitin, and poly-L-leucine) was examined with the use of water extracts. By applying the Limulus amoebocyte lysate (LAL) test, high concentrations of endotoxin were detected in extracts from three kinds of products made of calcium alginate. These extracts evoked fever in rabbits and induced the release of a proinflammatory (pyrogenic) cytokine, interleukin-6 (IL-6), from human monocytic cells (MM6-CA8). The effects disappeared when the extracts were treated with endotoxin-removing gel column chromatography or with an endotoxin antagonist, B464, confirming that the contaminating pyrogen was endotoxin. A noteworthy finding was that one of the endotoxin-containing extracts showed very weak IL-6-inducibility in human monocytic cells in contrast to its high pyrogenicity to rabbits. The discrepancy could be explained based on differences between humans and rabbits in sensitivity to the endotoxin, because the extract showed higher proinflammatory-cytokine (TNF-alpha)-inducibility in rabbit whole-blood cells (WBCs) than human WBCs. The results suggest that the LAL test is a useful method of detecting endotoxin contamination in wound dressings and the MM6-CA8 assay is a good supplement to the LAL test for evaluating pyrogenicity in humans accurately.     

Carotid-cardiac baroreflex function does not influence blood pressure regulation during head-up tilt in humans

The influence of the carotid-cardiac baroreflex on blood pressure regulation was evaluated during supine rest and 40 degrees head-up tilt (HUT) in 9 healthy young subjects with and without full cardiac vagal blockade. The carotid baroreflex responsiveness, or maximal gain (G(MAX)), was assessed from the beat-to-beat changes in heart rate (HR) and mean arterial pressure (MAP) by the variable neck pressure and suction technique ranging in pressure from +40 to -80 Torr, with and without glycopyrrolate (12.0 +/- 1.0 microg/kg body weight; mean +/- SE). In the supine position, glycopyrrolate increased the HR to 91 +/- 3 bpm, from 54 +/- 3; MAP to 89 +/- 2 mmHg, from 76 +/- 2; and cardiac output to 6.8 +/- 0.3 l.min(-1), from 4.9 +/- 0.3 (P < 0.05). The G(MAX) of the carotid baroreflex control of HR was reduced to -0.06 +/- 0.01 bpm.mmHg(-1), from -0.30 +/- 0.02 (P < 0.05) with no significant effect on the G(MAX) of the carotid baroreflex control of MAP. During HUT the carotid baroreflex control of MAP was unchanged, though the G(MAX) of the carotid baroreflex control of HR was increased (P < 0.05). During HUT, central blood volume, assessed by electrical thoracic admittance, and total vascular conductance were decreased with and without glycopyrrolate. Furthermore, glycopyrrolate reduced G(MAX) of the carotid baroreflex control of HR during HUT (P < 0.05) with no significant effect on G(MAX) of the carotid baroreflex control of MAP. These data suggest that during supine rest and HUT-induced decreases in central blood volume, the carotid baroreflex control of HR is mediated primarily via parasympathetic activity. Furthermore, the maintenance of arterial blood pressure during postural stress is primarily mediated by arterial and cardiopulmonary reflex regulation of sympathetic activity and its effects on the systemic vasculature.     

Influence of PD‐L1 cross‐linking on cell death in PD‐L1‐expressing cell lines and bovine lymphocytes

Programmed death‐ligand 1 (PD‐L1) blockade is accepted as a novel strategy for the reactivation of exhausted T cells that express programmed death‐1 (PD‐1). However, the mechanism of PD‐L1‐mediated inhibitory signalling after PD‐L1 cross‐linking by anti‐PD‐L1 monoclonal antibody (mAb) or PD‐1–immunogloblin fusion protein (PD‐1‐Ig) is still unknown, although it may induce cell death of PD‐L1⁺ cells required for regular immune reactions. In this study, PD‐1‐Ig or anti‐PD‐L1 mAb treatment was tested in cell lines that expressed PD‐L1 and bovine lymphocytes to investigate whether the treatment induces immune reactivation or PD‐L1‐mediated cell death. PD‐L1 cross‐linking by PD‐1‐Ig or anti‐PD‐L1 mAb primarily increased the number of dead cells in PD‐L1^high cells, but not in PD‐L1^low cells; these cells were prepared from Cos‐7 cells in which bovine PD‐L1 expression was induced by transfection. The PD‐L1‐mediated cell death also occurred in Cos‐7 and HeLa cells transfected with vectors only encoding the extracellular region of PD‐L1. In bovine lymphocytes, the anti‐PD‐L1 mAb treatment up‐regulated interferon‐γ (IFN‐γ) production, whereas PD‐1‐Ig treatment decreased this cytokine production and cell proliferation. The IFN‐γ production in B‐cell‐depleted peripheral blood mononuclear cells was not reduced by PD‐1‐Ig treatment and the percentages of dead cells in PD‐L1⁺ B cells were increased by PD‐1‐Ig treatment, indicating that PD‐1‐Ig‐induced immunosuppression in bovine lymphocytes could be caused by PD‐L1‐mediated B‐cell death. This study provides novel information for the understanding of signalling through PD‐L1.