Evaluation of Differences Between Fan-Beam and Pencil-Beam Densitometers

We compared the bone and body composition results in vivo on two bone densitometers using fan-beam geometry (EXPERT and PRODIGY) with those using pencil-beam geometry (DPX). Measurements were made on large groups of adults ranging in weight from about 50 to 120 kg. Both spine and femur neck BMD on the fan-beam densitometers averaged within 1% of the pencil-beam results, and there was no magnitude dependence of the results by Bland-Altman analysis. Total body BMC and BMD on the PRODIGY and DPX were congruent, but on the EXPERT, BMC was about 2% lower and BMD 2% higher than corresponding values on the DPX. Soft-tissue composition was closely congruent for the PRODIGY and DPX; the comparable EXPERT-DPX differences showed greater scatter but no significant magnitude dependence. The smaller fan-angle of the PRODIGY (4°) probably contributed to its better congruence to pencil-beam results compared with the EXPERT (12°). Received: 23 February 2000 / Accepted: 14 April 2000 / Online publication: 27 July 2000     

Severe asthma in children

Most children with asthma have their disease easily controlled if low‐dose inhaled corticosteroids (ICSs) are regularly and correctly administered. If a child presents with asthma which is apparently resistant to therapy with high‐dose ICS and other controllers, then they have problematic severe asthma. However, in light of the UK National Review of Asthma Deaths, definitions of severe asthma based solely on the levels of prescribed treatment are too narrow. A detailed assessment of all such children should be performed. First, the diagnosis of asthma should be confirmed, then co‐morbidities assessed. Next, a nurse‐led assessment further characterizes the problem, conventionally categorizing the child as either having difficult asthma or severe therapy‐resistant asthma. Here, we reassess in particular the interactions between, and management of, these two categories, highlighting that this dichotomous classification may need reconsideration. We use bronchoscopy and an intramuscular steroid injection to determine if the child has steroid‐resistant asthma, using a novel, multidomain approach because the adult definition does not apply to around half the children we see. Finally, we highlight some mechanistic data which have emerged from this protocol such as the absence of T‐helper 2 (TH2) cytokines even in eosinophilic severe asthma and the potential role of the innate epithelial cytokine IL‐33, novel data on lineage negative innate lymphoid cells, which we can measure in induced sputum, and demonstrating that intraepithelial neutrophils are associated with better, not worse asthma outcomes. Severe paediatric asthma is very different from severe asthma in adults, and approaches must not be uncritically extrapolated from adult disease to children.     

Antiangiogenic property of human thrombin

Using protein chromatography, we purified and identified human prothrombin from human plasma as antiangiogenic. Prothrombin significantly inhibited endothelial cell tube formation in vitro at 10 microg/ml. Importantly, it also inhibited bFGF-induced angiogenesis in Matrigel-plug assays performed in mice. The proteolytic activity of thrombin appeared to be critical for the antiangiogenic activity of prothrombin. For example, thrombin exhibited inhibitory effects on endothelial cell tube formation in vitro at 10 U/ml. Addition of lepirudin, a specific inhibitor of thrombin, completely blocked prothrombin's and thrombin's antiangiogenic effects in vitro. We also assessed the importance of thrombin receptors in angiogenesis. Using small peptides that activate different protease-activated receptors (PARs), we showed that activation of PAR-1 led to inhibition of endothelial cell tube formation in vitro and bFGF-induced angiogenesis in vivo. Collectively, our data suggest that thrombin's proteolytic activity can be antiangiogenic.     

Bacterial translocation to mesenteric lymph nodes is increased in cirrhotic rats with ascites

Cirrhotic patients are predisposed to develop spontaneous bacteremias and/or peritonitis, mainly caused by enteric bacteria. The aim of this study was to investigate if bacterial translocation, which is the passage of bacteria from the intestinal lumen to regional lymph nodes and/or the systemic circulation, is increased in a rat model of cirrhosis. Rats were studied after 12–16 weeks of CCl₄ inhalation, when samples of mesenteric lymph nodes, blood, liver, and spleen for standard bacteriologic cultures and a fragment of colon and liver for histology were obtained. Immunostaining of the cecum was performed using a polyclonal anti-Escherichia coli antibody. A significantly greater proportion of rats with cirrhosis and ascites (5 of 9; 56%) had positive mesenteric lymph node cultures compared with cirrhotics without ascites (0 of 9) and normal controls (0 of 12) (P < 0.01). In one cirrhotic rat, E. coli was isolated from both mesenteric lymph nodes and ascites. Rats with cirrhosis and ascites had significantly greater cecal submucosal edema and inflammation than rats with no ascites and controls. Immunoreactivity with E. coli was present in the cecal wall in 3 of 5 animals with E. coli translocation to mesenteric lymph nodes. In cirrhotic rats, bacterial translocation is increased after the development of ascites and may be a major factor in the development of spontaneous infections in cirrhosis.     

Oxidative stress in plasma from maple syrup urine disease patients during treatment

Maple Syrup Urine Disease (MSUD) is an autossomal recessive metabolic disorder caused by a deficiency of branched-chain α-keto acid dehydrogenase complex activity leading to accumulation of the branched-chain amino acids leucine, isoleucine and valine and their corresponding branched-chain α-keto acids. Affected patients usually present hypoglycemia, ketoacidosis, convulsions, poor feeding, coma, psychomotor delay and mental retardation. Considering that the pathophysiology of MSUD is still poorly understood, in this study we evaluated some parameters of oxidative stress, namely thiobarbituric acid-reactive substances (TBARS), total antioxidant reactivity (TAR) and total antioxidant status (TAS) in plasma from treated MSUD patients presenting high and low plasma leucine levels. We verified a significant increase of TBARS (lipid peroxidation) and a decrease of TAR (capacity to rapidly react with free radicals) in plasma from treated MSUD patients with low and with high plasma levels of leucine compared to the control group. It was also verified that TAS (quantity of tissue antioxidants) was not altered in plasma from treated MSUD patients with low and high blood leucine levels. Finally, we found no correlation between leucine, valine and isoleucine levels with the various parameters of oxidative stress. These results are indicative that increased lipid oxidative damage and decreased antioxidant defenses occur in plasma of MSUD patients and that the accumulating branched-chain amino acids are probably not directly associated to oxidative stress in this disorder.     

A nosocomial outbreak of Branhamella catarrhalis confirmed by restriction endonuclease analysis

An outbreak of respiratory illness due to Branhamella catarrhalis occurred in the intermediate care unit of a Veterans Administration hospital and involved patients and staff members. Four patients had pneumonia and four had bronchitis. Infected patients were placed in a cohort separated from noninfected patients and were treated. Pharyngeal culture was used to survey prevalence in staff and all other patients on the unit; three of 18 staff members and two of 19 asymptomatic patients were positive for B. catarrhalis. A case-control study showed that respiratory therapy, steroid use, and location within the unit were significant risk factors for B. catarrhalis infection or colonization. Strains from five patients and two staff members had identical bacterial restriction endonuclease digestion patterns with three different enzymes; these patterns were distinct from those of control strains. This study is the first to document an outbreak of B. catarrhalis infection confirmed with a typing system and thus establishes B. catarrhalis as a nosocomial pathogen.     

Inflammation and dephosphorylation of the tight junction protein occludin in an experimental model of multiple sclerosis

Multiple sclerosis (MS) is a disease of the CNS in which inflammation, demyelination and neurodegeneration contribute to its initiation and progression. A frequently employed model of MS is experimental autoimmune encephalomyelitis (EAE). Here, to gain new insights into the disease process, an analysis of proteins in extracts of lumbar spinal cord from naïve and EAE rats was undertaken. The data mainly confirm that inflammation and blood–brain barrier (BBB) breakdown are the major hallmarks of disease in this model. Given their importance in the BBB, junctional proteins were further investigated. Occludin, a protein localizing to tight junctions in brain endothelial cells, showed strikingly increased migration in EAE when analyzed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE). This increased migration was mimicked by in vitro phosphatase treatment, implying its dephosphorylation in EAE. Occludin dephosphorylation coincided with the onset of inflammation, slightly preceding visible signs of disease, and was just prior to apparent changes in BBB permeability. These findings suggest occludin is a target for signaling processes in EAE, perhaps regulating the response of the BBB to the inflammatory environment as seen in MS.