Posttraumatic skeletal muscle proteolysis: The role of the hormonal environment

To investigate the role of hormones as mediators of net skeletal muscle proteolysis following injury, healthy normal male volunteers received a continuous 76-hour infusion of the 3 stress hormones: hydrocortisone, glucagon, and epinephrine. As a control, each subject received a saline infusion during another 4-day period. Ten paired studies were conducted. Diets were constant and matched on both occasions. Triple hormone infusion achieved hormone concentrations similar to those seen following mild-moderate injury. After 72 hours of infusion, skeletal muscle intracellular glutamine concentrations were lower in the hormone studies than in the control group (N=4). Free amino acid concentrations in arterial whole blood and forearm amino acid efflux were little affected by hormonal infusion. Thus, alteration of the hormonal environment by the triple hormone infusion was not a sufficient stimulus to induce all of the changes in skeletal muscle proteolysis observed in critical illness. Since studies utilizing neurohormonal blockade have shown diminished net muscle proteolysis, the stress hormones appear to be necessary but not sufficient for the protein catabolic response to injury.

---

Resumen Con el propósito de investigar el papel de las hormonas como agentes mediadores de la proteolisis muscular neta que se presenta en el trauma y en otros estados críticos, se administró una infusión de las 3 hormonas del estrés, hidrocortisona, glucagón, y epinefrina, a voluntarios sanos por períodos continuos de 76 horas. Como control, cada individuo recibió una infusión de solución salina durante otro período de 4 días. Se condujeron 10 estudios apareados, con dietas constantes y similares en ambas ocasiones. La infusión triple de hormonas produjo concentraciones sanguíneas hormonales similares a las observadas en pacientes con trauma leve-moderado. A las 72 horas de la infusión las concentraciones intracelulares de glutamina en el mÚsculo esquelético aparecieron menores que en los estudios de control (N=4). Las concentraciones de aminoácidos libres en la sangre arterial y el flujo de salida de aminoácidos en el antebrazo resultaron mínimamente afectados por la infusión hormonal. Por lo tanto, la alteración del medio hormonal producida por infusión triple de hormonas no representa un estímulo suficiente para inducir la totalidad de las alteraciones en la proteolisis del mÚsculo esquelético que se observa en la enfermedad crítica. Puesto que los estudios con bloqueo neurohumoral han demostrado una disminución en la proteolisis muscular neta, las hormonas del estrés parecen ser necesarias, pero no suficientes de por sí, para la respuesta catabólica a la injuria biológica.

---

Résumé Pour étudier le rôle des hormones dans la protéolyse posttraumatique de muscle squelettique, des volontaires de sexe mâle en bonne santé ont été perfusés pendant 76 heures avec les 3 hormones de stress: hydrocortisone, glucagon, et adrénaline. En contrôle, chaque patient a reÇu une perfusion de sérum physiologique pendant quatre jours. Dix études appariées ont été faites. Pendant les deux études, l'alimentation était la mÊme et constante. La perfusion des 3 hormones a provoqué une concentration semblable à celle qu'on observe après un traumatisme moyen. Après 72 heures, le taux de glutamine dans les muscles squelettiques était plus bas dans l'étude hormonale que dans l'étude contrôle (N=4). La concentration en acides aminés libres dans le sang artériel et notamment l'arrivée de sang dans l'avant-bras n'étaient que peu influencées par la perfusion hormonale. Ainsi, la perfusion avec augmentation de la concentration des 3 hormones de stress ne suffisait pas pour provoquer la protéolyse musculaire squelettique que l'on observe lors des maladies graves. Puisque d'autres études ont montré que le blocage neurohormonal diminue nettement la protéolyse musculaire, les hormones de stress semblent donc nécessaires mais non suffisantes dans la réponse catabolique protéinique au traumatisme.

---

---

Supported by the National Institutes of Health Trauma Center Grant P50-GM 29327-03 and Clinical Research Center Grant no. 290-9299.     

二氧化硅活化巨噬细胞中早期生长反应因子-1及其信号转导通路的研究

目的 探讨早期生长反应因子(Egr-1)及其信号转导在矽肺发生发展中的作用。方法用细胞免疫荧光、原位杂交方法检测二氧化硅(SiO2)刺激后Egr-1的表达定位,用报道质粒及EMSA检测其活性改变;用激酶活性分析法检测si0：刺激巨噬细胞后ERK1／2活性改变,进一步用激酶抑制剂初步探讨SiO2活化Egr-1的信号转导通路。结果SiO2刺激RAW264．7细胞短时间Egr-1核蛋白表达及转录因子明显增加;且在处理后30～60min,Egr-1核蛋白结合活性明显升高(为未处理组的20倍);在刺激后15min ERK1／2活性开始升高,30min达高峰(活性为对照组的29倍)而后渐降至基础水平;进一步用激酶阻断发现,Egr-1 mRNA及蛋白表达均减少。结论SiO2能激活巨噬细胞中Egr-1,且此过程可能由ERK1／2、p38介导,提示SiO2-ERK1／2、p38-Egr-1通路可能在矽肺发生发展过程中起重要作用。     

金针菇子实体多糖提取物对人肝癌SMMC—7721细胞的抑增殖作用

金针菇子实体经热水提取，乙醇沉淀，胰蛋白酶水解，Ｓｅｖａｇ法去除蛋白质，乙醇分级沉淀等处理得金针菇子实体多糖。研究了该多糖对人肝部ＳＭＭＣ－７７２１细胞生长曲线，有丝分裂指数及线粒体活性的影响。结果表明该多糖对体外培养的人肝癌ＳＭＭＣ－７７２１细胞具一定抑制作用。     

散发性急性戊型肝炎血清抗体动态变化和肝脏超微…

为探讨散发性戊型肝为血清抗体动态变化，应用酶联免疫法（ＥＩＡ）检测了７例急性戊型肝炎抗戊型肝炎病毒（ＨＥＶ）ＩｇＧ和ＩｇＭ抗体、并对１例２进行了肝超微结构病理检测，结果表明，发病１０天至４５天内抗ＨＥＶ－ＩｇＧ和ＩｇＭ滴度最高，发病第４０天仍有肝细胞肿胀，胞浆空化和线粒体固缩等病理变化。患者轿清抗－ＨＥＶＩｇＭ滴度在４５天后逐渐下降，２个月内全中消失，抗－ＨＥＶＩｇＭ滴度在４５天后逐渐下降，２个月     

Characterization of the UL4 gene product of herpes simplex virus type 2

Summary.  We have identified the herpes simplex virus type 2 (HSV-2) UL4 gene product using a rabbit polyclonal antiserum raised against a recombinant 6xHis-UL4 fusion protein expressed in Escherichia coli. The antiserum reacted specifically with a 27-kDa protein in HSV-2 186-infected cell lysates. The protein was not detectable in the presence of the viral DNA synthesis inhibitor, suggesting that the UL4 gene was expressed as a γ₂ gene. Indirect immunofluorescence studies localized the UL4 protein within the nucleus as discrete punctate forms at late times postinfection. However, when expressed in the absence of other viral proteins, the UL4 protein was limited to the cytoplasm, indicating that an interaction with one or more other virus-induced proteins was responsible for the nuclear localization during infection. Subnuclear fractionation studies showed that the protein was released from the nuclear structure of infected cells by high salt treatment. Moreover, the UL4 protein was detected in purified virions and light particles. Received December 24, 1997 Accepted February 4, 1998     

Interleukin-1 and tumor necrosis factor receptor signaling is not required for bacteria-induced osteoclastogenesis and bone loss but is essential for protecting the host from a mixed anaerobic infection

Bacterial infection causes significant morbidity, mediated in part by the up-regulation of inflammatory cytokines. Cytokine induction is thought to stimulate osteolysis in conditions such as periodontal disease and otitis media. To establish the relative importance of interleukin-1 (IL-1) and tumor necrosis factor (TNF) in mediating the response to a mixed anaerobic infection, we used an in vivo model in which the dental pulp was inoculated with six anaerobic pathogens, in mice with functional deletions of receptors to IL-1 (IL-1RI(-/-)), TNF (TNFRp55(-/-)-p75(-/-)), or both (TNFRp55(-/-)-IL-1RI(-/-)). Polymorphonuclear and mononuclear phagocyte recruitment occurred to the greatest extent in TNFRp55(-/-)-IL-1RI(-/-) mice, and to a lesser extent in IL-1RI(-/-) or TNFRp55(-/-)-p75(-/-) mice, and the least in wild-type mice, demonstrating that recruitment of these phagocytes is not dependent on IL-1 or TNF receptor signaling. A similar pattern was observed for bacterial penetration into host tissue. Because it had recently been reported that TNF played a critical role in mediating lipopolysaccharide-induced bone loss, we anticipated that mice with targeted deletions of TNFRp55(-/-) would have reduced osteoclastogenesis. Surprisingly, osteolytic lesion formation was greatest in animals lacking TNF and/or IL-1 receptors. These results indicate that IL-1 or TNF receptor signaling is not required for bacteria-induced osteoclastogenesis and bone loss, but does play a critical role in protecting the host against mixed anaerobic infections.     

Display of a PorA peptide from Neisseria meningitidis on the bacteriophage T4 capsid surface.

The exterior of bacteriophage T4 capsid is coated with two outer capsid proteins, Hoc (highly antigenic outer capsid protein; molecular mass, 40 kDa) and Soc (small outer capsid protein; molecular mass, 9 kDa), at symmetrical positions on the icosahedron (160 copies of Hoc and 960 copies of Soc per capsid particle). Both these proteins are nonessential for phage infectivity and viability and assemble onto the capsid surface after completion of capsid assembly. We developed a phage display system which allowed in-frame fusions of foreign DNA at a unique cloning site in the 5' end of hoc or soc. A DNA fragment corresponding to the 36-amino-acid PorA peptide from Neisseria meningitidis was cloned into the display vectors to generate fusions at the N terminus of Hoc or Soc. The PorA-Hoc and PorA-Soc fusion proteins retained the ability to bind to the capsid surface, and the bound peptide was displayed in an accessible form as shown by its reactivity with specific monoclonal antibodies in an enzyme-linked immunosorbent assay. By employing T4 genetic strategies, we show that more than one subtype-specific PorA peptide can be displayed on the capsid surface and that the peptide can also be displayed on a DNA-free empty capsid. Both the PorA-Hoc and PorA-Soc recombinant phages are highly immunogenic in mice and elicit strong antipeptide antibody titers even with a weak adjuvant such as Alhydrogel or no adjuvant at all. The data suggest that the phage T4 hoc-soc system is an attractive system for display of peptides on an icosahedral capsid surface and may emerge as a powerful system for construction of the next generation multicomponent vaccines.     

Analysis of the genetic diversity of genes 5 and 6 among group C rotaviruses using cDNA probes

Summary Two partial cDNA clones of genes 5 (encoding the major inner capsid protein VP 6) and 6 (encoding a nonstructural protein) of the porcine group (Gp) C rotavirus (Cowden strain) were radiolabeled with³²P and used individually as probes in Northern and dot blot hybridization assays. The specificity of each probe was tested against genomic dsRNA from: (1) porcine Gp A, B, and C rotaviruses; (2) Gp C rotaviruses from different species; and (3) porcine Gp C rotavirus field strains with varying electropherotype patterns. Neither probe hybridized with ds RNA from the porcine Gp A and B strains under the stringency conditions employed in the study. However, the gene 5 probe hybridized with the corresponding gene from the homologous porcine and the heterologous human and bovine Gp C rotaviruses tested. The gene 6 probe hybridized with the corresponding gene from the homologous Cowden strain, but hybridized weakly with gene 6 from the human and bovine Gp C rotaviruses. Both probes recognized all six different porcine Gp C field strains, although with varying intensities. Our results demonstrate that the gene 5 and 6 probes used in this study are specific for Gp C rotaviruses. However, evidence for greater genetic variation in the gene 6 among porcine, bovine and human Gp C strains suggested that the gene 5 probe may prove more broadly reactive among Gp C strains from different species. cDNA probes used in our study should prove useful for the detection of Gp C rotaviruses in feces and facilitate epidemiologic studies.     

平行平板流动腔的合理设计和使用

高度远小于横向和纵向几何尺寸的平行平板流动腔，是当前用以体外研究细胞力学行为，特别是细胞粘附特性的主要工具之一。本文从目前常用的平行平板流动腔内流体定常流动时的切应力表达式出发，指出该切应力表达式仅适用于小雷诺数条件，由此确定平行平板流动腔几何尺寸的合理选择；通过对小孔入流和出流的平行平板流动腔流场的分析，指出该切应力表达式只在远离孔口边界一定距离，即达到均匀流动后成立。