Effects of purified bovine whey factors on cellular immune functions in ruminants

Retinoid X receptors (RXRs) form heterodimers with thyroid hormone receptors (TRs). RXRs increase DNA binding affinity of TRs and T3-mediated transactivation on positive T3 response elements (TREs). However, the role of RXRs on negative TREs, and the relation of RXRs to the dominant negative effect of mutant TRs, are not defined. To clarify the function of RXRs on negative TREs, we performed transient cotransfection studies using the rat glycoprotein hormone alpha promoter fused to luciferase gene (alphaLuc), and human TRH promoter fused to luciferase gene (TRH-Luc) as reporters. We found that the JEG-3 cell-alphaLuc system was very sensitive to TR regulation. Using TRbeta1 wild-type (WT) expression vector, 6.2 ng/well (170 ng/10 cm dish), and 0.2 ng/well (11 ng/10 cm dish) caused maximal, and half maximal, inhibition of Luc activities in the presence of 1 nM T3. A T3 dose dependent inhibition study was also performed. From these studies, we determined that the appropriate conditions in which to study alphaLuc transactivation, in a linear portion of the dose response curve, was using 0.8 ng/well TRbeta1 expression vector and 0.1 nM T3. Under these conditions, TRbeta1 mutant R316H (GH), but not G345R (Mf), showed a weak dominant negative effect at a 1:1 ratio in the presence of 0.1 nM T3 although neither mutant had detectable T3 binding affinity. Moreover this dominant negative effect of R316H on the alphaLuc reporter was enhanced in the presence of RXRgamma. Mutant G345R showed a stronger dominant negative effect than did R316H when using a double palindromic TRE fused to herpes simplex thymidine kinase-Luc reporter as a positive TRE. These results conform to the clinical features of R316H which is associated with apparent pituitary resistance of thyroid hormone (PRTH). Mutant R316H also showed a weak dominant negative effect with TRH-Luc at a 1:1 ratio in the absence or presence of RXRgamma. However RXRgamma did not enhance the dominant negative effect as it did using alphaLuc reporter gene. Electrophoretic gel mobility shift assay (EMSA) showed that RXR alpha augmented the DNA binding affinity of wild type and R316H TRs as heterodimers on the previously reported negative TREs of glycoprotein hormone alpha promoter, suggesting that RXR does not produce its response by removing TRs from these TREs. RXR alpha augmented DNA binding affinity of TRbeta1WT, and R316H showed a weaker heterodimer band than did the wild type in EMSA. Using the TRH-Luc reporter, basal activity was increased by wild type TRbeta1. However a TRbeta1 DNA binding domain mutant, (C127S) which can not bind to DNA, did not increase the basal activity. This indicates that DNA binding of the TR is required for increasing basal activity of TRH promoter. These results indicate that (1) RXR-TR heterodimers play a role in basal transactivation and T3 suppression of negatively regulated genes, and (2) RXRs increase the dominant negative effect of some mutant TRs on specific negative TREs. (3) This effect occurs without removing TRs from the TRE. (4) The differential dominant negative effect of mutant R316H (negative TRE > positive TRE) may explain, at least in part, the presentation of R316H as PRTH. (5) Augmentation of basal activity by wild type TRs on a negative TRE requires DNA binding.     

Do descending influences alternate to produce episodic breathing?

This study examines the episodic breathing patterns of three disparate groups of vertebrates. In an in vitro bullfrog brainstem-spinal cord preparation, episodic breathing was replaced by uniformly spaced breaths following transection caudal to the optic chiasma. The same effect was produced in hibernating squirrels by inhalation of mild anesthesia. Preliminary data suggest that a similar conversion is also produced in hibernating squirrels by vagotomy, in conjunction with blockade of central NMDA-type glutamate receptors. In all cases, even though overall breathing frequency increased, due to elimination of periods of apnea, instantaneous breathing frequency slowed. Seals breathe episodically in sleep and when these animals awaken after the start of a breathing episode, breathing also immediately slows. The data presented here are consistent with the suggestion that in all vertebrates, higher centres can modulate the central rhythm generator for breathing, in both a positive and a negative fashion. During episodic breathing, in the species studied here, these modulating influences alternate in a fashion that produces periods of apnea alternating with periods of relatively high frequency ventilation.     

Activation of CDC 25 phosphatase and CDC 2 kinase involved in GL331-induced apoptosis

CDC 25 is a dual phosphatase responsible for dephosphorylation and, thus, activation of CDC 2 kinase in G2. Abnormal activation of cyclin B-associated CDC 2 kinase has been implicated in apoptosis induced by cancer chemotherapeutic agents such as paclitaxel (Taxol) and etoposide (VP-16). In this study, we found that the CDC 2 kinase could be transiently activated when nasopharyngeal carcinoma NPC-TW01 cells were treated for 3 h with a new anticancer agent, GL331. GL331 treatment also induced a concomitant increase in CDC 25A phosphatase activity and a reduced level of Tyr-15-phosphorylated CDC 2 in NPC-TW01 cells. Furthermore, subsequent apoptotic DNA fragmentation induced by GL331 could be interrupted by treatment of the cells with the cyclin B1-specific antisense oligonucleotides, suggesting that abnormal activation of cyclin B1-associated CDC 2 kinase and CDC 25A phosphatase was involved in GL331-induced apoptosis. Raf-1 has been shown to associate with CDC 25A and, thus, to stimulate its phosphatase activity. Our results revealed that GL331 could facilitate the association of CDC 25A with Raf-1, resulting in the cascade of CDC 25A phosphatase activation and CDC 2 kinase activation, as well as related signaling pathways, and ultimately causing apoptosis in cancer cells.     

自润滑钢板的生产

介绍了国外自润滑钢板的研究和生产工艺，自润滑钢板有机涂层的组成，以及国外自润滑钢板的生产情况，同时提出了攀钢生产自润滑钢板的建议。     

Prolonged survival in selected patients following surgical resection for pulmonary metastasis from hepatocellular carcinoma

BACKGROUND: Pulmonary metastasis is the commonest site of extrahepatic spread from hepatocellular carcinoma (HCC). The aim of the present study was to evaluate the efficacy of surgical management in patients with solitary pulmonary metastases from HCC. METHODS: This was a retrospective study of patients with HCC admitted for hepatectomy from July 1972 to June 1995. The records of patients who had a pulmonary resection for histologically proven pulmonary recurrence after curative hepatectomy were selected for analysis. RESULTS: In the study interval, 380 patients with HCC underwent hepatectomy. Some 48 patients (12.6 per cent) developed pulmonary metastases documented pathologically or radiologically. Nine (seven men and two women) were suitable for curative pulmonary resection. The median disease-free survival between hepatectomy and appearance of the lung metastasis was 21 months. The median survival after pulmonary resection was 42 months, and the 1-, 2- and 5-year survival rates were 100, 78 and 67 per cent respectively. CONCLUSION: Pulmonary resection for metastases from HCC resulted in long-term survival in these highly selected patients.     

Characterization of monoclonal antibodies to ovine tumor necrosis factor-alpha and development of a sensitive immunoassay

Monoclonal antibodies (mAbs) and a polyclonal rabbit antiserum were raised against recombinant ovine tumor necrosis factor-alpha (rovTNF alpha). Ten mAbs specific for rovTNF alpha were isolated and designated TNF1-10. All mAbs were of the IgG1 isotype and reacted with rovTNF alpha in Western blot analysis. Eight of the ten mAbs, TNF1, TNF3-7 and TNF9 and 10, completely blocked the activity of rovTNF alpha and macrophage derived native ovTNF alpha, as measured by their ability to inhibit TNF alpha-mediated lysis of WEHI-164 or L929 cells. In addition, TNF3, -7, -9 and -10 blocked the cytolytic activity of recombinant human TNF alpha (rhuTNF alpha). However, when tested for the ability to inhibit TNF alpha induced thymocyte proliferation, only mAbs TNF1, -3, -5, -7, -9 and -10 could completely block activity. Competitive binding analysis using unlabelled and horseradish peroxidase (HRPO) labelled mAbs indicated that the mAbs could be divided into five groups based on their reactivity with rovTNF alpha. The mAbs were used to develop a sensitive sandwich immunoassay for the detection of ovTNF alpha. All combinations of mAbs and the polyclonal antiserum were tested to determine which pair of antibodies gave the most sensitive assay. The combination of TNF5 as the capture antibody and the polyclonal antiserum gave the most sensitive result, detecting less than 0.24 ng rovTNF alpha ml-1. A similar sensitivity was obtained when TNF4 was used as the capture antibody and TNF10 HRPO labelled mAb as the second antibody. The immunoassay was more sensitive than the WEHI-164 bioassay which had a detection limit of 1 ng ml-1 for rovTNF alpha. This immunoassay also detected glycosylated ovTNF alpha in the supernatant of COS-7 cells which had been transfected with an ovTNF alpha cDNA.     

The role of scintigraphy in the evaluation of fever of unknown origin

Nuclear medicine imaging techniques are an important adjunct to other currently used modalities in the evaluation of patients with fever of unknown origin. Bone scanning performed with technetium-labeled phosphonate agents may identify osteomyelitis when plain radiography fails and may disclose sites of joint inflammation or unsuspected osseous tumor metastasis. Indium-labeled autologous leukocytes localize at sites of inflammation in the same manner as unlabeled leukocytes. Gallium citrate accumulates in areas of inflammation and in some tumors, most notably lymphomas. In most cases, scintigraphy is best used to determine the location of a lesion rather than to specifically identify the pathologic process.     

Association between bleomycin hydrolase and Alzheimer's disease in caucasians

A recent study showed modest evidence for an increased frequency of the bleomycin hydrolase (BH) V/V genotype in Alzheimer's disease (AD) patients compared with non-demented controls. To test this hypothesis, we examined this polymorphism in 621 rigorously evaluated patients and 502 control subjects (all caucasian) but were unable to detect an association between BH and AD even after controlling for age, gender, and apolipoprotein E (ApoE) genotype. We conclude that this polymorphism does not account for inherited susceptibility to AD in the populations represented in this sample.