IgE-mediated14C-serotonin release from passively sensitized rat mast cells: Comparative kinetic study with formaldehyde and ice-cold methods

The kinetics of IgE-mediated release of serotonin from passively sensitized rat mast cellsin vitro was studied by stopping¹⁴C-serotonin release with the application of formaldehyde fixative or ice-cold mast cell medium (MCM). Antigen dose-release curves of¹⁴C-serotonin and/or histamine were comparable when mediator release was terminated with either formaldehyde at a final concentration of 1% or ice-cold MCM 15 min after antigen challenge. However, the kinetic study of immunological mediator release stopped by formaldehyde showed that the addition of antigen resulted in a progressive increase of released¹⁴C-serotonin for 7 min, the release curve being sigmoidal, whereas the application of ice-cold MCM artificially enhanced¹⁴C-serotonin and histamine release in the first 2 min. The results suggest that stopping IgE-mediated release of¹⁴C-serotonin with formaldehyde is a simple, rapid and accurate method of studying the kinetics of mediator release from mast cells.     

Effects of succinylated concanavalin A on infectivity and syncytial formation of human immunodeficiency virus

The effects of various lectins on the infectivity of human immunodeficiency virus (HIV) type 1 was investigated. Among the 25 lectins investigated, 2 types of concanavalin A (Con A) and 3 types of phytohemagglutinin were found to inhibit HIV infection. Succinylated Con A (S-Con A) efficiently blocked HIV-induced formation of syncytia in a coculture of MOLT-4 cells and blocked cell-free infection by HIV of MT-4 cells. The HIV-binding study revealed that S-Con A only partially inhibited viral binding to cells, although the control Leu-3a monoclonal antibody strongly inhibited it. When S-Con A was added to cultures after the initiation of viral adsorption, the number of HIV antigen-positive cells that developed depended on the time interval before addition of the compound. S-Con A inhibited HIV infection even after viral binding to cells at 0 °C and further incubation at 37 °C for 1 day. These data suggest that S-Con A inhibited mainly the fusion process rather than viral binding to cells in exerting its anti-HIV activity.     

Inactivation of the p16 gene by hypermethylation and loss of heterozygosity in adenocarcinoma of the lung

We investigated the aberrant promoter hypermethylation of p16, p15 and p14 genes and loss of heterozygosity (LOH) at 9p21-22 in 48 cases of adenocarcinoma of the lung. The frequencies of hypermethylation of genes were as follows: p16, 25.0%; p15, 22.9%; and p14, 18.8%. The frequency of LOH at chromosome 9p21-22 was 60.9%. The frequency of two-hit inactivation of the p16 gene by hypermethylation and LOH was 21.7%. Two-hit inactivation of the p16 gene showed loss of protein expression and was significantly correlated with tumor size, tumor grade and the Ki-67 labeling index. Hypermethylation of the p16 gene was not significantly correlated with hypermethylation of the p15 and p14 genes, both of which are close to the p16 gene locus, suggesting that hypermethylation of these genes occurs selectivity. In conclusion, biallelic inactivation of the p16 gene by hypermethylation and LOH might cause loss of p16 expression and play an important role in the development of adenocarcinoma of the lung. Therefore, controlling and monitoring for hypermethylation of the p16 gene may be partially useful for treatment and early diagnosis of adenocarcinoma of the lung.     

No evidence of PEG1/MEST gene mutations in Silver‐Russell syndrome patients

Silver‐Russell syndrome (SRS) is characterized by prenatal and postnatal growth retardation with morphologic anomalies. Maternal uniparental disomy 7 has been reported in some SRS patients. PEG1/MEST is an imprinted gene on chromosome 7q32 that is expressed only from the paternal allele and is a candidate gene for SRS. To clarify its biological function and role in SRS, we screened PEG1/MEST abnormalities in 15 SRS patients from various standpoints. In the lymphocytes of SRS patients, no aberrant expression patterns of two splice variants (α and β) of PEG1/MEST were detected when they were compared with normal samples. Direct sequence analysis failed to detect any mutations in the PEG1/MEST α coding region, and there were no significant mutations in the 5′‐flanking upstream region containing the predicted promoter and the highly conserved human/mouse genomic region. Differential methylation patterns of the CpG island for PEG1/MEST α were normally maintained and resulted in the same pattern as in the normal control, suggesting that there was no loss of imprinting. These findings suggest that PEG1/MEST can be excluded as a major determinant of SRS. © 2001 Wiley‐Liss, Inc.     

Epithelial Cell Rests of Malassez and OX6‐Immunopositive Cells in the Periodontal Ligament of Rat Molars: A Light and Transmission Electron Microscope Study

It has been shown that human and cat epithelial cell rests of Malassez (ERM) consist of heterogeneous cell populations. Immunohistochemical and immunoelectron microscopic analyses have verified the presence of neuroendocrine and Merkel‐like cells in both of these epithelia. During experimental orthodontic tooth movement, immunocompetent cells have also been found in the vicinity of ERM in rat periodontal ligament (PDL), but have not been characterized in normal rat PDL. The aim of this study was to investigate the presence and distribution of MHC class II antigen presenting cells by using OX6 antibody in ERM of rat molars by light and transmission electron microscopy. Immunohistochemical and immunoelectron microscopic observations of rat maxillary molars confirmed the presence of OX6‐positive cells in contact with ERM. Some immunopositive cytoplasmic processes containing vesicles interdigitated with cells of the Malassez epithelial clusters. Based on these findings it can be concluded that immunocompetent cells are localized close to Malassez epithelial clusters in normal rat PDL. Furthermore, the ultrastructural evidences indicate a possible interaction between the epithelial and immunocompent cells and suggest morphological and functional properties for ERM. Anat Rec, 291:242–253, 2008. © 2008 Wiley‐Liss, Inc.     

Analgesic action of loperamide,an opioid agonist,and its blocking action on voltage-dependent Ca2+ channels

We investigated the relationship between the antinociceptive effect of the opiate agonist loperamide at the spinal level and its inhibitory effect on calcium influx. Intrathecal administration of loperamide showed a significant antinociceptive effect in the formalin test, which was not prevented by naloxone. On the other hand, no significant effects were observed by nicardipine, an L-type specific blocker, or by BAY K8644, an L-type specific agonist, suggesting no significant role of L-type calcium channels in nociceptive signal transduction. Loperamide suppressed the calcium influx in dorsal root ganglion neurons. As the antinociceptive effect of loperamide was not affected by naloxone or other calcium channel blocking toxins, and loperamide showed a direct inhibitory effect on calcium-influx, the analgesic effect of intrathecally injected loperamide might be due to its blockade of the voltage-dependent calcium channels at the terminals of the primary afferent fibers.     

A novel translocation involving chromosomes 2, 9, 14, and 22 in chronic myeloid leukemia

A 46-year-old man with chronic myelogenous leukemia was found to have a new complex translocation. In chronic phase, all of the bone marrow cells had a rearrangement of a t(2;9;14;22) (p21;q34;q32;q11). Southern blot analysis of leukocyte DNA revealed rearrangement of the breakpoint cluster region (bcr) within the 5.8-Kb bcr. The patient eventually died in blast crisis 28 months later. The cytogenetic findings of bone marrow cells showed a 46,XY,t(2;9;14;22)(p21;q34;q32;qll),add(lp),del(3q) karyotype in blast crisis.     

Prevention of hypertensive crisis with ATP during anesthesia for pheochromcytoma

In the anesthetic management of five patients undergoing excision of pheochromocytoma, adenosine triphosphate (ATP) was used for the purpose of regulating systemic arterial pressure during the period of tumor manipulation. ATP was administered at doses of 0.05–0.4mg/kg/min. Systemic arterial pressure showed a significant decrease from 162 ± 17/103 ± 11mmHg before manipulation to 136 ± 21/81 ± 10mmHg during the manipulation period. The plasma catecholamine levels showed significant increases in this period. Immediately after excision, the systemic arterial pressure was maintained at normal levels (118 ± 13/75 ± 16mmHg) by fluid replacement and discontinuation of ATP administration, subsequently becoming 129 ± 19/79 ± 16mmHg. The heart rate was very stable and tachycardia did not ocurr during the manipulation period. Only one arrhythmic episode ocurred in one patient. The systemic vascular resistance index was significantly lower during the manipulation period than before it. It was therefore considered that ATP was useful as an agent for controlling arterial pressue during the anesthesia for pheochromocytoma.(Murata K, Sodeyama O, Ikeda K et al.: Prevention of hypertensive crisis with ATP during anesthesia for pheochromocytoma. J Anesth 1: 162–167, 1987)