Quantitative contribution of the acid production to the intracellular acidification in human neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine

A chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLP), induced an acidification of cytosol by about 0.05 pH units in 30 sec followed by an alkalinization in human neutrophils. The quantitative contribution of acid production to the acidification was studied. The superoxide (O₂ ^–) production stimulated by fMLP was not involved in the acidification because the production of acids in neutrophils from patients with chronic granulomatous disease who do not produce O₂ ^–, was the same as that in normal neutrophils. The intracellular acidification was completely inhibited by deoxyglucose, suggesting that energy metabolism enhanced upon stimulation by fMLP might be the main source of the acidification. Although enhancement of the lactate formation by fMLP was 0.8 nmol/10⁶ cells, which could lower intracellular pH by 0.08 pH units, the lactate production could not explain the initial acidification because the production of lactate started at 1 min after the stimulation while the intracellular acidification began immediately after the stimulation. Mitochondrial respiratory inhibitors such as KCN and rotenone had no effects on the fMLP-induced intracellular acidification. The fMLP-induced production of CO₂ in 30 sec through the hexose monophosphate shunt was only 2.6 pmol/10⁶ cells, which was calculated to decrease intracellular pH by only 0.0014. Thus, changes of energy metabolism induced by fMLP does not explain the acidification.Abbreviations fMLP N-formyl-methionyl-leucyl-phenylalanine - BCECF-AM 2,7-bis(carboxyethyl)carboxyfluorescein acetoxymethyl ester - PMA phorbol 12-myristate 13-acetate - CGD chronic granulomatous disease - HMP hexose monophosphate - pHi intracellular pH     

Nafion膜固定的亚甲基蓝为介体的生物传感器

制成了以亚甲基蓝为介体的电流型过氧化氢生物传感器,通过离子交换牢固地固定在Nafion膜中的亚甲基蓝,能有效地在辣根过氧化物酶和玻碳电极之间传递电子.探讨了pH值、温度、工作电位和抗坏血酸等物质对此传感器生物电催化还原H₂O₂的影响.此生物传感器选择性好、灵敏度高,对H₂O₂线性响应范围为5.0×10^-7～2×10^-4 mol/L,响应时间少于30 s.     

Vinculin Proteolysis Unmasks an ActA Homolog for Actin-based Shigella Motility

In polarized Madin-Darby canine kidney (MDCK) cells, the transferrin receptor (TR) is selectively delivered to the basolateral surface, where it internalizes transferrin via clathrin-coated pits and recycles back to the basolateral border. Mutant tailless receptors are sorted randomly in both the biosynthetic and endocytic pathways, indicating that the basolateral sorting of TR is dependent upon a signal located within the 61–amino acid cytoplasmic domain. To identify the basolateral sorting signal of TR, we have analyzed a series of mutant human TR expressed in MDCK cells. We find that residues 19–41 are sufficient for basolateral sorting from both the biosynthetic and endocytic pathways and that this is the only region of the TR cytoplasmic tail containing basolateral sorting information. The basolateral sorting signal is distinct from the YTRF internalization signal contained within this region and is not tyrosine based. Detailed functional analyses of the mutant TR indicate that residues 29–35 are the most important for basolateral sorting from the biosynthetic pathway. The structural requirements for basolateral sorting of internalized receptors from the endocytic pathway are not identical. The most striking difference is that alteration of G₃₁DNS₃₄ to YTRF impairs basolateral sorting of newly synthesized receptors from the biosynthetic pathway but not internalized receptors from the endocytic pathway. Also, mutations have been identified that selectively impair basolateral sorting of internalized TRs from the endocytic pathway without affecting basolateral sorting of newly synthesized receptors. These results imply that there are subtle differences in the recognition of the TR basolateral sorting signal by separate sorting machinery located within the biosynthetic and endocytic pathways.     

Interaction of an adenovirus 14.7-kilodalton protein inhibitor of tumor necrosis factor alpha cytolysis with a new member of the GTPase superfamily of signal transducers.

The adenovirus (Ad) 14.7-kDa E3 protein (E3-14.7K), which can inhibit tumor necrosis factor alpha (TNF-alpha) cytolysis, was used to screen HeLa cell cDNA libraries for interacting proteins in the yeast two-hybrid system. A new member of the low-molecular-weight (LMW) GTP-binding protein family with Ras and ADP-ribosylation factor homology was discovered by this selection and has been named FIP-1 (14.7K-interacting protein). FIP-1 colocalized with Ad E3-14.7K in the cytoplasm especially near the nuclear membrane and in discrete foci on or near the plasma membrane. Its interaction with E3-14.7K was dependent on the FIP-1 GTP-binding domain. The stable expression of FIP-1 antisense message partially protected the cells from TNF-alpha cytolysis. FIP-1 was associated transiently with several unknown phosphorylated cellular proteins within 15 min after treatment with TNF-alpha. FIP-1 mRNA was expressed ubiquitously but at higher levels in human skeletal muscle, heart, and brain. In addition to homology to other LMW GTP-binding proteins, FIP-1 has regions of homology to two prokaryotic metalloproteases. However, there was no homology between FIP-1 and any of the recently isolated death proteins in the TNF-alpha or Fas/APO1 cytolytic pathway and no interaction with several members of the Bcl-2 family of inhibitors of apoptosis. These data suggest that FIP-1, as a cellular target for Ad E3-14.7K, is either a new intermediate on a previously described pathway or part of a novel TNF-alpha-induced cell death pathway. FIP-1 has two consensus sequences for myristoylation which would be expected to facilitate membrane association and also has sequences for Ser/Thr as well as Tyr phosphorylation that could affect its function.     

Uptake of high-density lipoprotein by Y-organs of the crab,cancer antennarius. II. formal characterization of receptor-mediation with isolated membranes

Y-organs are the ecdysial glands of crustaceans, responsible for synthesis and secretion of ecdysteroid hormones. For this purpose, the glands acquire cholesterol as obligate precursor entirely from circulating high-density lipoprotein (HDL). A preceding study provided evidence for the mechanism of acquisition: Y-organs take up cholesterol bound to HDL by an energy-requiring process, receptor-mediated absorptive endocytosis. The present study characterized the receptors involved utilizing isolated Y-organ membranes. HDL binding was saturable and specific; a dissociation constant (K_d) of 1.08 × 10^?7 M and a binding maximum at equilibrium (B_max) of 70 μg HDL protein/mg membrane protein, were obtained. Binding was decreased by protease and was dependent upon calcium. Y-organs are regulated negatively by a peptide hormone from the eystalks, molt-inhibiting hormone (MIH). Y-organ membranes from de-eyestalked crabs (MIH absent) exhibited the same K_d value as membranes from intact crabs, but a B_max 17% higher. Thus, MIH activity apparently does not change the binding affinity of HDL, but decreases the number of binding sites. These results agree with our previous findings that MIH depresses ecdysteroid synthesis in part by inhibiting cholesterol uptake. Generally, Y-organ cells appear to contain receptors for HDL that are of high affinity and high binding capacity, similar to the characteristics reported for the binding of insect HDL (vitellogenin) to fat bodies and oocytes. © 1995 Wiley-Liss, Inc.     

Molecular structure of the halogenated anti-cancer drug iododoxorubicin complexed with d(TGTACA) and d(CGATCG).

4'-Deoxy-4'-iododoxorubicin, a halogenated anthracycline derivative, is an anticancer agent currently under Phase II clinical trials. In preclinical studies, it has demonstrated significantly reduced levels of cardiotoxicity compared to currently employed anthracyclines. It also has modified pharmacological properties resulting in an altered spectrum of experimental antitumor activity. The iodine atom at the 4' position of the sugar ring reduces the basicity and enhances the lipophilicity of this compound as compared to related anthracycline drugs. We report here single crystal X-ray diffraction studies of the complexes of 4'-deoxy-4'-iododoxorubicin with the hexanucleotide duplex sequences d(TGTACA) and d(CGATCG) at 1.6 and 1.5 A, respectively. The iodine substituent does not alter the geometry of intercalation as compared to previously solved anthracycline complexes, but appears to markedly affect the solvent environment of the structures. This could have consequences for the interaction of this drug with DNA and DNA binding proteins in cells.     

The cytologic diagnosis of Mycobacterium kansasi tuberculosis by fluorescence microscopy of Papanicolaou-stained specimens

The cytologic diagnosis of Mycobacterium kansasi tuberculosis by fluorescence microscopy of Papanicolaou-stained specimens
The sensitivities of (i) Papanicolaou fluorescence, (ii) auramine rhodamine fluorescence, and (iii) Ziehl-Neelsen staining were compared for their ability to detect the atypical mycobacterium Myco. kansasi in cytological samples. Ninety-two cases were investigated, and the sensitivities of the three methods of detection were found to be 36.9%, 12.0%, and 20.7%, respectively. The control groups consisted of 30 specimens from cases of bronchial carcinoma and 30 of pneumonia. All cases were proved by microbiology. No false-positive results were recorded using Papanicolaou fluorescence. An important but coincidental finding arising from this study was that infection by the atypical mycobacterium Myco. kansasi causes cytological patterns corresponding to those normally associated with acute pneumonia and not to tuberculosis.     

四川地区幼儿和学龄前儿童的鼻部测量

本文报告１１１６例四川地区幼儿和学龄前儿童（２－７岁）鼻部９项指标的测量均数,性差及年龄发育特点。性差：仅鼻凹鼻底距４－６．５岁等少数指标部分年龄段男女性间出现显著性划异（男＞女）。此外各项指标的绝大多数年龄段男女性间无显著性差异。年龄发育：９项测量指标中７项的生长曲线随年产长而上升,数值随年龄增大,并有１－２个发育高峰;提示鼻部发育具有阶段性;２项指标的曲线随年龄增长变化较小。４项指标男女性的曲     

猕猴桃种质资源保存及育种研究

收集保存猕猴桃属植物３５种或变种、变型,并将它们分为抗寒?喜凉、喜温３种类型。从保存的中华猕猴桃优株中系统选育出“武植２号”、“武植３号”２个优良品种。以中华猕猴桃为母本,毛花猕猴桃为父本进行种间杂交,从杂种Ｆ１代中培养出“江山娇”、“满天星”、“重瓣”３个具有园艺观赏价值的优良株系。这些研究工作为猕猴桃种质资源的保存及新品种的培育奠定了工作基础。     

Mechanism of Action of Lycoricidinol, a Plant Growth Inhibitor Isolated from Lycoris radiata Herb.

We studied the action mechanism of lycoricidinol, a plant growthinhibitor isolated from Lycoris radiata Herb. Lycoricidinolinhibited protein synthesis in mung bean hypocotyls, but notRNA synthesis. Protein synthesis in Escherichia coli was notaffected by the inhibitor. Results of in vitro translation experimentswith the wheat germ system and the E. coli system indicatedthat lycoricidinol inhibited only eukaryotic but not prokaryotictranslation. Use of specific inhibitors of initiation and polypeptidechain elongation of polypeptide synthesis revealed that chainelongation was inhibited by lycoricidinol. ¹Permanent address: Department of Biology, Yonsei University,Seoul 120, Korea. (Received September 30, 1983; Accepted December 28, 1983)