Mixed Portmanteau Tests for Time‐Series Models

Abstract. This paper obtains the joint limiting distribution of residuals and squared residuals of a general time‐series model. Based on this, we propose a mixed portmanteau statistic for testing the adequacy of fitted time‐series models. In some cases, it is shown that this statistic can be simply approximated by the sum of well‐known portmanteau statistics. The finite‐sample performance of the new test is compared with those of well‐known tests through simulations.     

Cytogenetic abnormalities in pediatric myelodysplastic syndrome: a report of three cases

Three consecutive cases of pediatric myelodysplastic syndrome (MDS) diagnosed over a three-year period in Queen Mary Hospital, Hong Kong, were described. Depending on the classification system used, they comprised two cases of chronic myelomonocytic leukemia (CMMoL) of which one can be reclassified as juvenile chronic myeloid leukemia (JCML) and one cases of refractory anemia with excess of blasts (RAEB) or an alternative diagnosis of atypical CML. Cytogenetic abnormalities were detected in all of them on examination of bone marrow cells. Of the two CMMoL, one had monosomy 21, whereas the other had hypodiploidy. The patient with RAEB had a complex karyotype of 46,X,del(X)(q24),t(1;7) (p22;q32),add(15)(q26)(8). The balanced translocation (1;7) seen in this patient was exceedingly rare and, to the best of our knowledge, was reported only twice in the literature. The karyotypic abnormalities that we saw in our patients were not well recognized in pediatric MDS. This report emphasizes the importance of cytogenetic study in children suspected of suffering from MDS, which remains a rare disorder of childhood, and a need to rationalize current classification schemes.     

Distribution and heterogeneity of mast cells in the human uterus

Mast cells (MCs) are widely distributed in most human tissues. Those cells that contain only tryptase are designated as T-MCs, while those that also contain chymase are referred to as TC-MCs. This study uses immunohistochemical staining for tryptase and chymase to assess the distribution and heterogeneity of these two types of MCs in the human uterus. The greatest number of MCs was found in the inner (i.e. luminal) half of the myometrium, with this area containing approximately equal proportions of T-MCs and TC-MCs. There were fewer MCs in the outer half of the myometrium and the cervix, but the proportion of TC-MCs in both of these areas was substantially higher. In contrast, the endometrium contained significantly fewer MCs, but proportionally more T-MCs. There was no change in the number of MCs between the proliferative and secretory phases of the menstrual cycle; however, there was a significantly lower number in all areas after menopause. Most of the MCs were observed in close association with uterine smooth muscle cells, as well as in the vicinity of fibroblasts and collagen, and it appears they may play an important role in the reconstruction of uterine tissues during the menstrual cycle.     

Effects of guan-fu base a on experimental cardiac arrhythmias and myocardial contractility

Guan-fu base A (GFA) is a terpenoid alkaloid isolated from the tuber of Aconitum coreanum in our institute. GFA (20-30 mg.L-1) reduced the ventricular tachycardia (VT) and ventricular fibrillation (VF) rate induced by K(+)-free and high Ca2+ solution in Langendorf heart of rats. Pretreatment of conscious rats with GFA 2.5-10 mg.kg-1 iv, increased the amount of beiwutine necessary to produce arrhythmias. Ouabain-induced VT in conscious dogs was reverted to sinus rhythm in 1-2 min by iv GFA 9-10 mg.kg-1. GFA 10-20 mg.kg-1 iv was also found to be effective in protecting anesthetized dogs from atrial fibrillation induced by topical application of ACh. GFA 10 mg.kg-1 iv obviously decreased heart rate and prolonged the P-R interval, but slightly affected the myocardial contractility in anesthetized dogs. GFA showed no obvious effect on stroke volume and cardiac output in conscious dogs. In conclusion, GFA showed therapeutic and prophylactic effect on different models of experimental arrhythmias without causing marked effect on myocardial contractility.     

The NIDDK liver transplantation database

Gap junctional communication between glial cells is thought to play a role in K+ spatial buffering, in the propagation of inter-astrocytic Ca2+ waves, and in glial-neuronal signaling. In the present study, we characterize dye coupling between astrocytes, and between astrocytes and Müller cells, in the isolated rat retina. Whole-cell patch recordings were obtained from retinal astrocytes and Müller cells and the cells filled with Lucifer Yellow and neurobiotin. Spread of Lucifer Yellow to two to ten neighboring astrocytes occurred in 90% of the astrocyte recordings. After fixation and incubation of the retina with fluorescent conjugated streptavidin, neurobiotin was seen to label clusters of 13-88 astrocytes, as well as > 100 Müller cells. In contrast, when Müller cells were filled with Lucifer Yellow and neurobiotin, both tracers were confined solely to the recorded Müller cell. The uncoupling agents octanol, halothane, and doxyl-stearic acid were tested for their ability to uncouple retinal glia in situ. All three agents eliminated the visible spread of Lucifer Yellow from the injected astrocyte and the spread of neurobiotin into Müller cells. However, only doxyl-stearic acid combined with octanol eliminated the spread of neurobiotin between astrocytes. These results demonstrate that astrocytes in the rat retina are coupled to each other and to Müller cells. The astrocyte-to-Müller cell coupling is asymmetric, allowing transfer of the tracer in the forward direction only. In addition, astrocyte-to-Müller cell coupling is more sensitive to the uncoupling agents tested than is astrocyte-to-astrocyte coupling.     

Low frequency of TEL/AML1 in adult acute lymphoblastic leukemia

Translocation (12;21)(p13;q22) is a recently characterized aberration in acute lymphoblastic leukemia, and results in the fusion of the TEL and the AML1 genes. It is the most common translocation in pediatric acute lymphoblastic leukemia (ALL), occurring in about one third of the cases. To determine the frequency of TEL/AML1 in adult ALL, we studied 4 cases of T lineage ALL and 26 cases of B lineage ALL. Only one positive case was identified, giving a very low frequency of 3.3%. In this patient, TEL/AML1 was still detectable in complete hematologic remission. The apparent age predilection of t(12;21) warrants further investigations.     

Closed humeral shaft fractures: a prospective evaluation of surgical treatment

OBJECTIVE: We tried to define the roles of the rigid dynamic compression plate (DCP) and the semi-rigid Ender nail (EN) in the treatment of closed humeral shaft fractures. DESIGN: A prospective, randomized clinical study was performed with detailed comparison parameters. MATERIALS AND METHODS: Ninety-one closed humeral shaft fractures were treated. Randomly, 30 humeri were treated with open reduction and internal fixation with DCP and no bone grafting (BG), 29 were treated with the same procedure but with BG, and 32 were treated with closed reduction and internal fixation with Ender nails. The average follow-up period was 32 months (range, 13-54 months). MEASUREMENTS AND MAIN RESULTS: In the group with DCP without BG, the average blood loss was 270 mL, operation time was 92 minutes, hospital length of stay was 6.5 days, and union time was 12.5 weeks. In the group with DCP with BG, the average blood loss was 325 mL, operation time was 108 minutes, hospital length of stay was 6.9 days, and union time was 9.4 weeks. In the EN group, the average blood loss was 114 mL, operation time was 54 minutes, hospital length of stay was 5.6 days, and union time was 9.9 weeks. Analysis of variance and Fisher's exact test were used to evaluate the statistical significance. CONCLUSION: In our experience, for humeral shaft fractures fixed surgically, EN is better than DCP without BG. When DCP is chosen for the means of fixation, prophylactic BG is recommended, especially in cases with more comminution.     

Controlled hydrothermal growth of multi-length-scale ZnO nanowires using liquid masking layers

In this study, we demonstrate a method for creating multi-length-scale ZnO nanowires in a controllable manner on diverse planar and curvilinear substrates by introducing immiscible liquid masking layers (LMLs) above and beneath a nutrient solution used in hydrothermal growth. The confinement of volatile reactants by the LMLs stabilizes the pH, which is an important parameter in determining the shape of the nanowires, to enable growth in a stable manner. The conformal wettability of the LMLs provides freedom in the choice of target substrates and allows for the possibility of mounting spatially moving stages without the use of a specially designed solid lid. Selective growth within the growth zone defined by the LMLs in a dynamic- and/or static-mode can create various types of ZnO nanowires with gradual or terraced length profiles in two- or three-dimensional geometries. For a device application, we developed cylindrical photodetectors with the configuration of Cr/ZnO seed/ZnO nanowires/poly(3-hexylthiophene-2,5-diyl)/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) to show the ability to spatially modulate the photo-sensitivity by controlled hydrothermal growth of diverse length scales of ZnO nanowires using the LML method.