Indoor nitrogen dioxide and childhood respiratory illness

Abstract: Nitrogen dioxide is produced from the combustion of fossil fuels and as an emission from gas-fired appliances, and is also a component of tobacco smoke. Nitrogen dioxide has been shown in experimental animals to be toxic to the respiratory tract. A number of recent studies have suggested that children exposed to significant levels of nitrogen dioxide in the home may be more susceptible to respiratory illness than children exposed to normal ambient levels. Respiratory illness is a major cause of morbidity in children everywhere. Here, we review the available evidence of this association and explore methodological issues in measurement of nitrogen dioxide exposure— misclassification of subjects, symptom bias and confounding. It has recently been shown that some New South Wales school rooms, where unflued gas heaters are often used as a source of warmth, have nitrogen dioxide levels which are above recommended ambient levels for outside air. This has underlined the need for setting standards for indoor levels of various pollutants, and cohort studies are suggested, to include personal monitoring and prospective data collection techniques.     

Dual-energy X-ray absorptiometry of lumbar vertebrae: relative contribution of body and posterior elements and accuracy in relation with neutron activation analysis.

The bone mineral content of 34 lumbar vertebrae obtained from ten cadavers (three men, seven women; age 61-88 years) was measured using a pulsed source dual-energy X-ray absorptiometry (DEXA) apparatus. Scanning was performed in the frontal projection and was repeated on the vertebral bodies obtained after removal of the posterior elements of the vertebrae. Subsequently a nondestructive neutron activation analysis (NAA) was performed. The mineral content of the vertebral bodies was found to represent (mean, SEM) 53.0% (1.9%) of the content of the whole vertebrae. The mineral content of the vertebral bodies assessed with NAA (BMC NAA) and with DEXA (BMC DEXA) showed a high correlation: BMC NAAA = (1.016 x BMC DEXA) + 0.990 r = 0.949 (p less than 0.001). We conclude that the mineral content of lumbar vertebral bodies can be accurately measured in vitro in a water environment by DEXA, and that the mean contribution of the posterior elements of the vertebra to the calcium hydroxyapatite content of whole vertebrae measured in the frontal projection is as high as 47.0%.     

Ultrasound diagnosis of fetal lung maturity--a new method]

First results are presented to determine the maturity of fetal lung by sonography. Using the fetal liver as a reference-organ we are avoiding the known pitfalls which made it impossible in the past to standardize the fetal lung changes depending on the age of gestation. We examined 104 patients between week 27 and week 41. In one ultrasound section cut we depicted as well lung and liver. According to the known A-mode we registered frequencies in both organs. The registered frequencies were entered digitally into a computer and checked for f(mean), f(max) and f(min). Afterwards the frequencies of the lung were divided by those of the liver. Of all weeks of gestation the mean value and standard deviation were calculated. We found the liver as an adequate reference-organ, since there is no change of the reflection pattern between the different weeks of gestation, while there are significant changes to be registered in the fetal lung, a cutting line being week 35. A quotient of f(mean) lower than 1.1 hints to lung maturity while values over 1.1 point to immaturity. This was confirmed by several cases of analysis of amniotic fluid (L/S-ratio). Further comparisons with amniotic fluid results will have to validate these findings.     

Tissue-specific extinguisher loci in the murine genome: A screening study based on a rat/mouse microcell hybrid panel

Extinction of tissue-specific traits in intertypic somatic cell hybrids is a well-known phenomenon. In the past few years, microcell hybrids have been used in attempts to dissect this phenotype genetically, and tissue-specific extinguisher loci have been mapped to two different mouse chromosomes. When transferred from fibroblasts into hepatoma cells by microcell fusion, these loci down-regulate expression of specific liver genes intrans. However, other liver genes that are extinguished in genotypically complete hybrids seem not to be extinguished in monochromosomal hybrids. To assess the generality of monochromosomal extinction phenotypes, we assembled a collection of rat hepatoma/mouse fibroblast microcell hybrids that represent most of the mouse chromosome complement, and we screened them for expression of a large number of liver-specific genes. Phosphoenolpyruvate carboxykinase gene expression was down-regulated in hybrids containing mouse chromosome 7 or mouse chromosome 11, but other extinction phenotypes were not readily apparent. These results indicate that extinction of many liver genes may be a polygenic trait.     

Antibiotic-impregnated plaster of Paris beads. Trials with teicoplanin.

Teicoplanin-impregnated plaster of Paris beads were made and in vitro release properties were studied. Teicoplanin was released in an initial massive dose, with a rapid decline during the first three days, followed by a slowly declining prolonged release up to 30 days. The release tested by diffusion in gelose and high-performance liquid chromatography was found to be 21.4% and 28.2%, respectively, of the amount theoretically present in the beads. Plaster of Paris is a resorbable, nontoxic biomaterial that has already been used to fill dead spaces in bone and deliver antibiotics in the treatment of chronic osteomyelitis. The addition of teicoplanin, a new antistaphylococcal agent with low known bacterial resistance, is a promising alternative. Follow-up tests in vivo, simulating local conditions of the osteomyelitic bone, are necessary to prove efficacy.     

VASCULAR CONNECTIVE TISSUE CHANGES IN EXPERIMENTAL PORTACAVAL ANASTOMOSIS

Hepatic vascular changes are generally associated to fibrotic lesions of the liver but their role in the development and extension of fibrosis is not well known. By performing a portacaval anastomosis in rats, a proliferation of hepatic vessels was attained progressively, comparable to proliferations seen in cirrhosis and schistosomiasis. Such a modification of the hepatic vasculature was accompanied by changes in the connective matrix of the liver, mainly related to the vascular walls. Moreover, sinusoidal capillarization was detected at the electron microscopical level whereas no alterations could be seen neither in the distribution nor in the quality of the connective matrix proteins with Immunofluorescence technique. The only modification detected by light microscopy, at this zone, was the shrinked aspect of reticulin fibers which could be related to the important liver atrophy provoked by the anastomosis. It can be assumed that in liver pathology, selective changes occur in the connective matrix components depending on the type of injury. Necrotic and inflammatory processes lead mainly to the deposition of interstitial collagens and associated proteins, related to a diffuse stroma reaction resultant from activation of specific cell populations whereas in portacaval anastomosis, a selective increase of vascular connective matrix (mainly basement membrane components) occurs as a direct consequence of vessel proliferation.     

A prospective study of Autologous Growth Factors (AGF) in lumbar interbody fusion.

BACKGROUND: Numerous preclinical and clinical studies have reported on the use of platelet concentrates to promote tissue healing. The results in spinal fusion applications are limited and controversial. PURPOSE: The purpose of the current prospective clinical cohort study is to assess the effect of Autologous Growth Factors (AGF) on lumbar interbody fusion with specific attention paid to determination of clinical and radiographic outcomes. STUDY DESIGN/SETTING: Prospective clinical study PATIENT SAMPLE: Candidates for anterior-posterior lumbar fusion with diagnosis of degenerative disc disease and/or up to grade I spondylolytic spondylolisthesis based on positive provocative discography. OUTCOME MEASURES: Clinical (visual analogue pain scale/functional outcome assessment) and radiographic outcomes (fusion on computed tomography at 6 months and plain radiographs at 12 and 24 months). METHODS: Thirty-seven patients were assigned to standard anterior-posterior interbody fusion L2-S1 (single or two-level) using iliac crest bone graft (autograft group: 22 patients with 32 levels operated) or allograft combined with autogenous growth factors (AGF group: 15 patients with 25 levels operated). Radiographic outcomes were collected at 6 months postsurgery with computed tomography and at 12 and 24 months with plain radiographs. Pre- and postoperative clinical outcome measures included visual analog scores (VAS) for back and leg pain (0-10), SF-36 scores, and Oswestry disability determination. Average clinical and radiographic follow-up for the autograft group was 24.3+/-5.6 months (12-36 months) and AGF was 25.7+/-7.5 (6-40 months). RESULTS: Fusion incorporation at each end plate was determined at 56% in both autograft and AGF (p=NS) patients based on computed tomography at 6 months with minimal subsidence noted and no direct correlation between the incidence or degree of cage subsidence and bone graft technique. The 12- and 24-month radiographic results confirmed an 85% arthrodesis rate for the autograft patients, whereas the AGF patients had an 89% fusion rate (p=NS). Clinical outcomes were similar for both groups and no significant differences were noted for pain or functional outcome improvements. CONCLUSIONS: AGF combined with an allograft carrier is equivalent in radiographic and clinical outcomes to autograft in one- or two-level lumbar interbody fusion with supplemental posterior fixation and, thus, eliminates any morbidity from iliac crest bone graft harvesting. AGF combined with an appropriate carrier is a reasonable alternative to autograft and expensive bone induction technologies. Further research is still required to examine the optimum carriers, preparation and formulation, and platelet concentrations for this technology.     

Transjugular intrahepatic portosystemic shunt before abdominal surgery in cirrhotic patients: a retrospective, comparative study.

Surgery in cirrhotic patients is associated with high morbidity and mortality related to portal hypertension and liver insufficiency. Therefore, preoperative portal decompression is a logical approach to facilitate abdominal surgery and hopefully to improve postoperative survival. The present study evaluated the clinical outcomes of 18 patients (mean age 58 years) with cirrhosis (seven alcoholics and 11 nonalcoholics) who underwent transjugular intrahepatic portosystemic shunt (TIPS) placement before antrectomy (n=5), colectomy (n=10), small-bowel resection (n=1), pancreatectomy (n=1) and nephrectomy (n=1). TIPS was performed a mean (+/-SD) of 72+/-21 days before surgery and induced a marked mean decrease in portohepatic gradient from 21.4+/-3.9 mmHg to 8.4+/-3.4 mmHg. Cirrhotic patients (n=17) who underwent elective abdominal surgery without preoperative TIPS placement were used as the control group. Both groups were matched for age, etiology of cirrhosis, indications for surgery, type of surgery and coagulation parameters. The mean Pugh score was significantly higher in the TIPS group (7.7 versus 6.2). No significant differences were observed for operative blood loss, postoperative complications, duration of hospitalization and one-month (83% versus 88%) or one-year (54% versus 63%) cumulative survival rate. Analysis using the Cox proportional hazards model showed that neither TIPS placement nor preoperative Pugh score were independent predictors for survival. The present study suggests that preoperative TIPS placement does not improve postoperative evolution after abdominal surgery in cirrhotic patients with good or moderately impaired liver function.