B Lymphocyte signaling established by the CD19/CD22 loop regulates autoimmunity in the tight-skin mouse

Systemic sclerosis (SSc) is characterized by fibrosis and autoimmmunity. Peripheral blood B cells from SSc patients specifically overexpress CD19, a critical cell-surface signal transduction molecule in B cells. CD19 deficiency in B cells also attenuates skin fibrosis in the tight-skin (TSK/+) mouse, a genetic model for SSc. Herein we analyzed two transgenic mouse lines that overexpress CD19. Remarkably, 20% increase of CD19 expression in mice spontaneously induced SSc-specific anti-DNA topoisomerase I (topo I) antibody (Ab) production, which was further augmented by 200% overexpression. In TSK/+ mice overexpressing CD19, skin thickness did not increase, although anti-topo I Ab levels were significantly augmented, indicating that abnormal CD19 signaling influences autoimmunity in TSK/+ mice and also that anti-topo I Ab does not have a pathogenic role. The molecular mechanisms for abnormal CD19 signaling were further assessed. B-cell antigen receptor crosslinking induced exaggerated calcium responses and augmented activation of extracellular signal-regulated kinase in TSK/+ B cells. CD22 function was specifically impaired in TSK/+ B cells. Consistently, CD19, a major target of CD22-negative regulation, was hyperphosphorylated in TSK/+ B cells. These findings indicate that reduced inhibitory signal provided by CD22 results in abnormal activation of signaling pathways including CD19 in TSK/+ mice and also suggest that this disrupted B cell signaling contribute to specific autoantibody production.     

ASXL2 mutations are frequently found in pediatric AML patients with t(8;21)/ RUNX1‐RUNX1T1 and associated with a better prognosis

ASXL2 is an epigenetic regulator involved in polycomb repressive complex regulation or recruitment. Clinical features of pediatric acute myeloid leukemia (AML) patients with ASXL2 mutations remain unclear. Thus, we investigated frequencies of ASXL1 and ASXL2 mutations, clinical features of patients with these mutations, correlations of these mutations with other genetic alterations including BCOR/BCORL1 and cohesin complex component genes, and prognostic impact of these mutations in 369 pediatric patients with de novo AML (0–17 years). We identified 9 (2.4%) ASXL1 and 17 (4.6%) ASXL2 mutations in 25 patients. These mutations were more common in patients with t(8;21)(q22;q22)/RUNX1‐RUNX1T1 (ASXL1, 6/9, 67%, P = 0.02; ASXL2, 10/17, 59%, P = 0.01). Among these 25 patients, 4 (27%) of 15 patients with t(8;21) and 6 (60%) of 10 patients without t(8;21) relapsed. However, most patients with relapse were rescued using stem cell transplantation irrespective of t(8;21). The overall survival (OS) and event‐free survival (EFS) rates showed no differences among pediatric AML patients with t(8;21) and ASXL1 or ASXL2 mutations and ASXL wild‐type (5‐year OS, 75% vs. 100% vs. 91% and 5‐year EFS, 67% vs. 80% vs. 67%). In 106 patients with t(8;21) AML, the coexistence of mutations in tyrosine kinase pathways and chromatin modifiers and/or cohesin complex component genes had no effect on prognosis. These results suggest that ASXL1 and ASXL2 mutations play key roles as cooperating mutations that induce leukemogenesis, particularly in pediatric AML patients with t(8;21), and these mutations might be associated with a better prognosis than that reported previously.     

Are CD8+CD122+ cells regulatory T cells or memory T cells?

We identified CD8(+)CD122(+) regulatory T cells in the mouse. Some immunologists consider CD8(+)CD122(+) cells to be memory T cells despite our report of their regulatory function. Here, we propose a dual phenotype of these cells. Murine CD8(+)CD122(+) T cells demonstrate both memory and regulatory features in their functional profiles. Human CD8(+)CXCR3(+) T cells, which are thought to be the human counterpart of murine CD8(+)CD122(+) regulatory T cells, do not match human central memory T cells of the CD8(+)CD45RA(-)CCR7(+) phenotype. Thus, we must consider human CD8(+) regulatory T cells and murine CD8(+) regulatory T cells separately. Of human CD8(+) regulatory T cells, CD8(+)CXCR3(+) regulatory T cells can be divided into further subsets and we may be able to distinguish memory T cells and regulatory T cells. Of murine CD8(+)CD122(+) regulatory T cells, it seems to be impossible to divide CD8(+)CD122(+)CD44(+)CD62L(+) regulatory T cells into further subsets at present, indicating that this single population of cells has activities of both regulatory T cells and memory T cells.     

Pouch operation for rectal cancer

Many retrospective studies have found that the functional outcome after a low anterior resection for rectal cancer is better with colonic J-pouch reconstruction than with conventional straight anastomosis. This advantage was demonstrated in prospective, randomized trials and meta-analyses. However, despite its increasing popularity there are several areas of controversy about the use of the colonic J-pouch reconstruction. These issues include anastomotic leaks, the part of the colon used for the pouch, the pouch size, causes of difficulty in evacuation, indications (the optimum level of anastomosis), appropriateness for the elderly, and long-term (2 years or more after surgery) functional outcome. All relevant articles identified from MEDLINE databases were reviewed. The incidence of anastomotic leaks is apparently reduced by colonic J-pouch reconstruction. A 5-cm colonic J-pouch using the sigmoid colon increases the reservoir function without compromising evacuation, and provides better functional outcome than straight anastomosis, even 2 years or more after surgery, in patients whose anastomosis is less than 8 cm from the anal verge. Patients with ultralow anastomoses, less than 4 cm from the verge, appear to benefit the most. At a time when the indications for abdominoperineal excision appear to be reduced for low rectal cancer, the demand for colonic J-pouch reconstruction (the best technique in pouch operations) is therefore likely to increase.     

Age-related change of pulsatile gonadotropin secretion in Turner syndrome

In an attempt to understand the dynamic change of the gonadotropin-releasing hormone-pituitary axis during the transitional stage from prepuberty to puberty, we investigated gonadotropin secretory patterns using a highly sensitive assay system and frequent blood sampling technique in children with Turner syndrome aged 5-17 y. Blood samples were collected every 20 min for 24 h in 16 cases, or every 30 min for 9 h (daytime 5 h, nighttime 4 h) in nine cases. Serum LH and FSH were measured by time-resolved fluoroimmunoassay. A 24-h profile of LH and FSH was analyzed by a computerized pulse detection program (PC-PULSAR). As early as 5 to 6 y of age, mean daytime LH concentration was significantly higher than nighttime concentration and pulsatile LH secretion existed throughout the day and night. At about 9 to 11 y of age, corresponding to the early stage of puberty, a dramatic increase in LH concentration and amplitude was observed, and both concentration and pulse amplitude were much higher during the night than during the day. However, these day-night differences became less clear at ages corresponding to late pubertal stages. Pulse frequency of LH secretion remained almost constant throughout the day and night at all ages investigated. As for FSH concentration, a trend similar to that of LH was observed, although day-night differences and age-related changes were less remarkable. Furthermore, pulsatile FSH secretion was detected in only a small number of the cases. These findings suggest that in Turner syndrome the hypothalamic gonadotropin-releasing hormone oscillator is functioning actively with constant frequency before the onset of puberty.(ABSTRACT TRUNCATED AT 250 WORDS)     

A method for determining reference points in celloidin specimens for computer graphic reconstruction

Summary For three-dimensional computer graphic reconstruction of histological sections, it is important to determine reference points. We have developed a machine that makes reference points in a celloidin block for this purpose by drilling holes straight into the block. A sliding microtome is placed under the machine, which consists of a worktable, a stand, and a motor-driven unit. The celloidin block is sectioned on a microtome to determine a plane for serial sectioning. Several holes are then drilled in the block vertical to the plane selected. Serially sectioned specimens are next stained with hematoxylin and eosin and are mounted in the usual manner. Threedimensional reconstructions of the specimens were next done using a PC-9801 computer and CosmoZone-S software. As an example, the reconstruction of a guinea pig stapes is described.     

Study of virus isolation from pharyngeal swabs in children with varicella

We performed virus isolations from the pharyngeal swabs in 117 children with varicella who were aged from 22 days to 15 years and 70 healthy children who were aged from 3 months to 15 years, by using human embryonic lung cell cultures. Viral isolates were confirmed by an indirect immunofluorescence method or by neutralization with well-characterized antibodies. Five varicella-zoster virus isolates (4.3%), 23 cytomegalovirus isolates (19.7%), five herpes simplex virus isolates (4.3%), and one respiratory syncytial virus isolate (0.9%) were found in the patients with varicella. Ten cytomegalovirus isolates (14.3%), two herpes simplex virus isolates (2.9%), one respiratory syncytial virus isolate (1.4%), and one poliovirus isolate (1.4%) were found in the swabs of the healthy control children. The varicella-zoster virus isolation rate from the pharyngeal swabs in children with varicella was low as compared with the rate from those pharyngeal swabs in the children with cytomegalovirus and herpes simplex virus. No varicella-zoster virus isolates could be found in the swabbed materials after filtration (0.45 microns). On the other hand, cytomegalovirus and herpes simplex virus could be isolated from the filtrated swabs, as well as from the unfiltrated swabs. The method of testing by filtration could have affected the results.     

Meningo-encephalitis associated with HHV-6 related exanthem subitum

We report a 10-month-old boy with acute meningo-encephalitis associated with exanthem subitum. It has recently been reported that human herpesvirus-6 is the causative agent of exanthem subitum, and to our knowledge our case is the first report of meningo-encephalitis associated with HHV-6 infection.     

Sonographic imaging of the thyroid gland in congenital hypothyroidism

We have attempted to facilitate differential diagnosis of etiological types of congenital hypothyroidism using real-time ultrasonography. Sonography of the thyroid gland was performed on 418 normal children, and 23 patients with congenital hypothyroidism and hyperthyrotropinemia. The thyroid gland was imaged by transverse scanning at the neck; the maximum thickness and the maximum width of the right and left lobe were measured. On the basis of the normal thyroid gland size obtained from normal children, the thyroid gland image of the patients were classified into 4 types: large image, normal image, small image, and no image of the thyroid gland at the neck: no image of the thyroid gland indicated agenesis or ectopia; large thyroid gland image indicated goitorous hypothyroidism. On the other hand, normal or small thyroid gland image probably included mild or transient forms of hypothyroidism, and transient hyperthyrotropinemia; these 2 types required further examination to complete the diagnosis. We concluded that real-time ultrasonography of the thyroid gland was a useful diagnostic imaging technic for patients who revealed elevated serum thyrotropin on neonatal mass-screening.