Mendelson syndrome in infancy and childhood

Acute pulmonary failure caused by gastric acid aspiration is designated as Mendelson's syndrome. It is characterized by a trias of symptoms comprising bronchial obstruction, pulmonary oedema, and right ventricular failure. The pathomorphological pulmonary alterations show the typical symptoms of ARDS and allow the differentiation of three phases. The initial phase of injury is characterized by cauterization of the bronchial and alveolar epithelium. It is followed by the exsudative second phase during which alveolar oedema are developing. They impair the pulmonary surfactant synthesis and the formation of hyaline membranes. Fibrosis processes are typical of the proliferative third phase. Every of the mentioned three phases may be classified by their corresponding clinical symptoms. The therapy is entirely symptomatic and follows the intensive medical standards of the ARDS-therapy.     

Dissociation of the electrical and contractile properties in single human motor units during fatigue

The surface EMG area often exhibits progressive enlargement during a submaximal fatiguing contraction, but the underlying reasons still remain uncertain. Fatigue-induced changes in the surface-detected motor unit action potentials (S-MUAPs) of 10 human thenar motor units (MUs) with widely differing physiological properties were examined. After 2 min of repetitive 40-Hz stimulation, the size of the S-MUAPs of all MUs increased, the magnitude of which was negatively correlated with their tetanic tension changes. These findings suggest that during muscle fatigue, in addition to reflecting recruitment of new MUs and increases in firing rates of the active MUs, the surface EMG may also be markedly influenced by changes in the S-MUAPs, especially in fast fatigable muscles.     

T-cell apoptosis in inflammatory brain lesions: destruction of T cells does not depend on antigen recognition

Elimination of inflammatory T cells by apoptosis appears to play an important role in the down-regulation of inflammation in the central nervous system. Here we report that apoptosis of T lymphocytes occurs to a similar extent in different models of autoimmune encephalomyelitis. Apoptosis is restricted to cells located in the neuroectodermal parenchyma, thereby leaving T cells present in the brain's connective tissue compartments unharmed. Death of T cells in the parenchyma does not depend on antigen presentation by resident microglial cells or astrocytes. Adoptive transfer experiments with T lymphocytes carrying a specific genetic marker revealed that in the central nervous system these cells are destroyed regardless of their antigen specificity or state of activation. Although many of both antigen-dependent and -independent mechanisms in the induction of T-cell apoptosis may act simultaneously, our results suggest that the nervous system harbors a specific, currently undefined, mechanism that effectively eliminates infiltrating T lymphocytes.     

Pulmonary aspergillosis in cystic fibrosis lung transplant recipients

STUDY OBJECTIVE: To define the prevalence of colonization and infection of the lower respiratory tract (LRT) with Aspergillus in lung transplant recipients with and without cystic fibrosis (CF). DESIGN: Retrospective review. SETTING: Large university lung transplant center. MATERIALS AND METHODS: The postoperative course of 31 CF and 53 non-CF double lung or double lobar transplant recipients receiving allografts from April 1991 to February 1996 was reviewed. All recipients were subjected to surveillance bronchoscopy and biopsy at predetermined intervals and when clinically indicated. BAL fluid (BALF) and biopsy material were examined by appropriate fungal culture and staining techniques. Infection was defined by the finding of tissue-invasive disease on biopsy specimens. RESULTS: Seven of the 31 CF recipients (22%) had Aspergillus isolated from cultures of sputum prior to transplantation. Following transplantation, 15 CF recipients (48%) had Aspergillus isolated from either sputum or BALF, including 4 of the 7 recipients identified with the fungus prior to transplantation. By contrast, 21 of the 53 non-CF recipients (40%) had Aspergillus isolated from the LRT following transplantation, none having had the fungus isolated prior to transplantation. The prevalence of Aspergillus did not differ between these groups (p = 0.51). Infections with Aspergillus occurred in 4 of the CF recipients (27%) and did not differ from the 3 infections (14%) identified in the non-CF recipients (p = 0.36). However, three of the four infections in the CF recipients involved the healing bronchial anastomosis and occurred prior to postoperative day 60. All three of these recipients had Aspergillus preoperatively. Postoperative infection was more common in the CF recipients having Aspergillus preoperatively than in those CF recipients without preoperative Aspergillus (p = 0.02). CONCLUSIONS: Isolation of Aspergillus from the LRT following double lung transplantation is common and generally not associated with tissue-invasive disease. Those CF recipients with Aspergillus isolated in cultures of sputum preoperatively are at risk for postoperative infections with this agent. The healing bronchial anastomosis is particularly vulnerable.     

A modifying locus for familial adenomatous polyposis may be present on chromosome 1p35-p36

Sixteen healthy male dogs were used at random in this protocol. The dogs were anaesthetized with isoflurane in oxygen. Eight of the dogs received 0.25 mg/kg of butorphanol (group B) and the others an equal volume of isotonic saline (group S) administered by a catheter inserted in the lumbosacral epidural space. Butorphanol concentrations in plasma and cerebrospinal fluid (CSF) were measured using high-performance liquid chromatography with electrochemical detection. Maximum concentration of butorphanol and time to obtain this concentration were 42.28 ng/mL at 13.88 min in blood, and 18.03 ng/mL at 30 min in CSF. Volume of distribution, clearance, mean distribution and elimination half-lives were respectively 4.39 L/kg, 2.02 L/h.kg, 16.5 min and 189.1 min. Mean isoflurane minimal alveolar concentration values for group B obtained following hind- or forelimb stimulation decreased by 31% after epidural butorphanol. Cutaneous analgesia (to pin-prick test) persisted for 3 h after the end of isoflurane anaesthesia in group B and was in correlation with the plasmatic analgesic dose of butorphanol (9 ng/mL). These results suggested that analgesia was predominantly obtained by action of butorphanol on the supraspinal structures following its vascular systemic absorption.     

Oligomerization-dependent folding of the membrane fusion protein of Semliki Forest virus

The spikes of alphaviruses are composed of three copies of an E2-E1 heterodimer. The E1 protein possesses membrane fusion activity, and the E2 protein, or its precursor form, p62 (sometimes called PE2), controls this function. Both proteins are, together with the viral capsid protein, translated from a common C-p62-E1 coding unit. In an earlier study, we showed that the p62 protein of Semliki Forest virus (SFV) dimerizes rapidly and efficiently in the endoplasmic reticulum (ER) with the E1 protein originating from the same translation product (so-called heterodimerization in cis) (B.-U. Barth, J. M. Wahlberg, and H. Garoff, J. Cell Biol. 128:283-291, 1995). In the present work, we analyzed the ER translocation and folding efficiencies of the p62 and E1 proteins of SFV expressed from separate coding units versus a common one. We found that the separately expressed p62 protein translocated and folded almost as efficiently as when it was expressed from a common coding unit, whereas the independently expressed E1 protein was inefficient in both processes. In particular, we found that the majority of the translocated E1 chains were engaged in disulfide-linked aggregates. This result suggests that the E1 protein needs to form a complex with p62 to avoid aggregation. Further analyses of the E1 aggregation showed that it occurred very rapidly after E1 synthesis and could not be avoided significantly by the coexpression of an excess of p62 from a separate coding unit. These latter results suggest that the p62-E1 heterodimerization has to occur very soon after E1 synthesis and that this is possible only in a cis-directed reaction which follows the synthesis of p62 and E1 from a common coding unit. We propose that the p62 protein, whose synthesis precedes that of the E1 protein, remains in the translocon of the ER and awaits the completion of E1. This strategy enables the p62 protein to complex with the E1 protein immediately after the latter has been made and thereby to control (suppress) its fusion activity.     

Role of superoxide anions in changes of endothelial vasoactive response during acute hyperglycemia

The effects of acute hyperglycemia on endothelial Ca2+ signaling, formation of endothelium-derived relaxing factor (EDRF) and bioactivity of EDRF were investigated. Hyperglycemia increased 2,5-tert-butyl-1,4-hydrochinone (BHQ)-initiated Ca2+ signaling and EDRF formation in a concentration-dependent manner. The effect of elevated D-glucose on Ca2+/EDRF response could be diminished by co-incubation with the antioxidants vitamin E, probucol, GSH, vitamin C and superoxide dismutase. Convincingly, hyperglycemic conditions yielded an increase in superoxide anion release from endothelial cells and the superoxide anion-generating mixture xanthine oxidase/hypoxanthine mimicked the effect of hyperglycemia on Ca2+/EDRF signaling. Besides an enhanced formation of the vasodilatatory NO compound EDRF, hyperglycemia enhanced NO degradation by endothelial cells and, thus, reduced bioactivity of EDRF. We suggest that vasoactivity during acute hyperglycemia depends on the superoxide anion scavenging properties of the vascular wall. In acute hyperglycemia and early stages of diabetes, radical scavenging capacity may be suitable to protect NO degradation, resulting in an enhanced vasodilation. In contrast, decreased free radical scavenging properties of the vasculature in prolonged hyperglycemia and in later stages of diabetes might promote NO degradation by an overshoot of superoxide anions, resulting in an attenuation of endothelium-dependent vasodilation.     

A functionally defined model for the M2 proton channel of influenza A virus suggests a mechanism for its ion selectivity

The M2 protein from influenza A virus forms proton-selective channels that are essential to viral function and are the target of the drug amantadine. Cys scanning was used to generate a series of mutants with successive substitutions in the transmembrane segment of the protein, and the mutants were expressed in Xenopus laevis oocytes. The effect of the mutations on reversal potential, ion currents, and amantadine resistance were measured. Fourier analysis revealed a periodicity consistent with a four-stranded coiled coil or helical bundle. A three-dimensional model of this structure suggests a possible mechanism for the proton selectivity of the M2 channel of influenza virus.     

Primary traumatic midbrain syndrome--follow-up and prognosis of acute primary brain stem damage

Within 27 months 122 patients with severe head injury were treated at our clinic. Of these patients twelve (9.8%) were categorized as having a primary brain stem lesion (9 male and 3 female, mean age 28.3 years (17 to 73 years). Their injuries were caused primarily by traffic accidents. Initial and follow-up CT ruled out mass lesions or other causes for transtentorial herniation, supporting the diagnosis of primary brain stem lesion. Respiratory insufficiency and control of vegetative function demanded artificial ventilation and analog-sedation for up to 32 days (mean 18 days) on our Intensive Care Unit. In all patients we performed initial and follow-up CT scans, ICP monitoring, evoked potentials (AEP, SSEP) and TCD. MRI was carried out in four patients. One patient died during the acute hospital phase, 7 were transferred in poor and four in good condition. During rehabilitation one patient died, two, one in a vegetative state and one in poor condition were transferred to a caring facility. Eight patients with a good or moderate recovery were dismissed home, subsequently regaining their prior social function. The primary traumatic brain stem lesion presents as a dramatic clinical picture. As shown in our series the prognosis is good independent of the duration of coma. The important prognostic factors were the primary neurological state according to the Gerstenbrand and Luecking classification, the degree of the brain stem lesion in CT scan and MRI, and normal evoked potentials, indicating a favourable outcome.