High resolution computed tomography as a predictor of lung histology in systemic sclerosis

Background The relative proportions of fibrosis and inflammation seen by open lung biopsy examination is a predictor of disease outcome in fibrosing alveolitis. This study was designed to assess the ability of high resolution computed tomography to predict the histological appearance of open lung biopsy specimens from patients with systemic sclerosis.     

Keloid fibroblast responsiveness to epidermal growth factor and activation of downstream intracellular signaling pathways.

Keloids, which overgrow the boundaries of the original injury, represent aberrations in the fundamental process of wound healing that include over-abundant cell in-migration, cell proliferation, and inflammation, as well as increased extracellular matrix synthesis and defective remodeling. To understand the key events that result in the formation of these abnormal scars would open new avenues for better understanding of excessive repair, and might provide new therapeutic options. We examined epidermal growth factor receptor (EGFR)-induced cell motility in keloid fibroblasts, as this receptor initiates cell migration during normal wound repair. We show that keloid fibroblasts respond to EGF-induced cell migration but the response is somewhat diminished compared to normal adult fibroblasts (approximately 30% reduced); the mitogenic response was similarly blunted (approximately 5% reduced). Keloid fibroblasts express near normal levels of EGFR (82%), but show a much more attenuated activation of EGFR itself and the motility-associated phospholipase C-gamma. This was reflected in part by rapid loss of EGFR upon exposure to EGF. Interestingly, while extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) activation was relatively robust in keloid fibroblasts, the downstream triggering of the motility-associated calpain activity was blunted. This was reflected by high cell-substratum adhesiveness in the keloid fibroblasts. Thus, the blunted migratory response to EGF noted in keloid fibroblasts appears due to limited activation of two important biochemical switches for cell motility.     

Dr. Tom Chalmers, 1917-1995: the trials of a randomizer

Dr. Thomas Chalmers, an American physician who played a pivotal role in the scientific development of the randomized control trial and meta-analysis, died late last year. Shortly before Chalmers' death, Dr. Malcolm Maclure of the British Columbia Ministry of Health conducted a wideranging interview with him about his life and the past and future of clinical trials and evidence-based medicine. The first part is published below; the second part will appear in the Oct. 1 issue of CMAJ.     

Assessment of the Severity of Asthma in a Family Practice

The objective of this study was to evaluate clinical history and self-perception of severity as predictors of asthma severity. A short-term longitudinal study was conducted in a family practice in Melbourne, Australia, utilizing peak flow monitoring, medication diary, and self-administered asthma severity questionnaire. Seventy-two asthmatic subjects with a positive bronchodilator or exercise test, aged between 6 and 79 years, were studied. Symptom and treatment items were correlated with peak flow variability and minimal peak expiratory flow rate (PEFR). An asthma severity scale was generated using the partial credit version of Item Response Theory and the participants' severity scores were validated against lung function tests and medication usage. Quantitative modeling procedures were used to investigate the interrelationships of factors associated with peak flow variability. Severity scores demonstrated significant relationships with peak flow variability (partial r = 0.34) and treatment items. Self-perceived severity of asthma in the preceding 2 weeks showed significant association with peak flow variability (partial rho = 0.46) and minimal PEFR (rho = -0.41). The severity module of the Monash Respiratory Questionnaire is a valid and reliable instrument. The most important symptoms appear to be the frequency of use of bronchodilator and frequency of nocturnal attacks. A carefully structured clinical history in conjunction with the peak flow criteria of variability and minimal peak flow rate would be appropriate in the evaluation of asthma severity. Patients' self-perception of the severity of their asthma needs further evaluation.     

Multiple transduction as a means of preserving ganciclovir chemosensitivity in sarcoma cells carrying retrovirally transduced herpes thymidine kinase genes.

The potential value of retroviral gene transfer as a means of targeting therapeutic genes to neoplastic cells is threatened by the tendency of occasional cells to lose transduced genes or their expression. To determine whether this threat could be reduced by transducing multiple copies of a therapeutic gene, we compared 8 murine sarcoma sublines carrying from 1 to 6 copies of a retrovirally transduced herpes simplex virus thymidine kinase gene, which sensitizes cells to ganciclovir (GCV). When variability consequent to differences in vector integration site was excluded, increased copy number was associated with an increase in GCV sensitivity and a major reduction in the frequency of GCV-resistant mutants. The results suggest a potential means of preserving the efficacy of future antineoplastic gene therapy strategies.     

Asymmetric growth of the lateral cerebral ventricle in infants with posthemorrhagic ventricular dilation

Lateral cerebral ventricular volume in 36 preterm infants with or without an intraventricular hemorrhage, and with or without posthemorrhagic hydrocephalus, was measured longitudinally and compared with the ventricular index measurements of the same ventricles. A poor correlation was found (r2 = 0.67). To determine a reason for this poor relationship, we analyzed the volumes of the regions of the ventricles by a segmental volume analysis. The occipital region of the lateral cerebral ventricle enlarged at a much faster rate (1.904 +/- 0.477 ml/day) than either the anterior region (0.546 +/- 0.253 ml/day; p less than 0.01) or the middle region (-0.209 +/- 0.334 ml/day; p less than 0.01) in infants with posthemorrhagic hydrocephalus. The rate of growth of the middle region of the lateral cerebral ventricles was the same for all infants. Linear indexes, such as the ventricular index and the lateral ventricular ratio, do not allow for accurate serial estimates of ventricular size in posthemorrhagic hydrocephalus because of asymmetric growth of the lateral cerebral ventricle. We conclude that sequential volume measurements are more useful than ventricular index measurements to follow ventricular size sequentially in infants with posthemorrhagic hydrocephalus.     

Cervical lymphadenitis complicated by mycotic carotid artery aneurysm

A case of mycotic carotid artery aneurysm due to cervical lymphadenitis in a four-year old child is presented. Sonography and computed tomography (CT) demonstrated an irregular fluid-containing neck mass, similar in appearance to an uncomplicated abscess. Continuity with the carotid artery was suggested on sonography, and CT demonstrated intense contrast enhancement of the liquid portion of the mass. Mycotic carotid artery aneurysm is a rare, but potentially fatal, complication of cervical lymphadenitis that is detectable with noninvasive diagnostic imaging studies.