Prediction of service life of building materials and components

Conclusions Data on the service life of building materials and components are essential to the cost-effective use of materials. For this reason, it is important that methods be available for reliably predicting service life. In the current state-of-the-art, test methods are most often useful for comparing the relative ‘durabilities’ of building materials as opposed to predicting quantitatively the service life. The need to advance the state-of-the-art of service life prediction of building materials has stimulated considerable interest in national and international activities in recent years. The technical barriers to meeting the need for improved predictions are numerous and formidable. Therefore, it is not practicable for one laboratory or even one country to pursue, on its own, the long-term, complex and costly research needed to address the barriers. But the barriers offer the opportunity for continued and increased international interactions and the opportunity for performing challenging research on building materials and their degradation processes. In this way, the needs can be met.     

Changes in structure of the bovine milk fat globule membrane on heating whole milk.

The effects of heat-induced interactions between milk fat globule membrane components and skim milk proteins in whole milk on the structure of the membrane were examined by isopycnic sucrose density gradient centrifugation and by using Triton X-100 as a membrane probe. Skim milk components were incorporated into all the lipoprotein fractions separated by density gradient centrifugation. High density complexes, higher in density than those found in the natural milk fat globule membrane, were formed during the heat treatment. Losses of natural membrane polypeptides from the medium and low density lipoproteins were observed on heating. Heating whole milk also altered the rate of release of membrane components by detergent, with decreases in protein released and an increase in phospholipid constituents released. Studies on washed cream indicated that some of the changes in the membrane on heating whole milk occurred due to the heat treatment alone, independent of the interactions with skim milk proteins.     

APIC position paper: hepatitis C exposure in the health care setting. Association for Professionals in Infection Control and Epidemiology, Inc

The Association for Professionals in Infection Control and Epidemiology, Inc (APIC), is a multidisciplinary, voluntary, international organization of professionals who practice infection control and the application of epidemiology in all health settings. APIC is an international leader in prevention and control of infection transmission.     

FULL CONTAINMENT SPRAY DRYING

ABSTRACT

Aspects of safety, environmental protection, and powder quality will continue to influence advances within spray dryer design and operation, and the concept of full containment spray drying offers a means to meet future industrial requirements. Process air recycle and powder containment within the drying chamber leads to no process air discharge to atmosphere, provides a more favorable operator environment around the spray dryer installation, reduces regions within the dryer layout where potential explosive powder/air mixtures can exist, improves yields, reduces powder losses, and provides easier cleaning operations with reduced wash water requirements.     

HIV seroprevalence amongst pregnant women in northeastern Zaire

Heparin co-factor II is in addition to antithrombin III another heparin dependent thrombin inhibitor. This glycoprotein blocks thrombin action not only in haemostasis but also in its other effects. Congenital deficiency of heparin co-factor II was found equally frequently among asymptomatic subjects and patients with thrombotic complications. Although its deficiency probably is not a serious risk factor of thromboembolic disease, it can promote its development in a significant way. The authors describe the case of a child with thrombotic complications and a congenital deficiency of heparin co-factor II.     

The role of the active site cysteine in catalysis by type 1 iodothyronine deiodinase

Type 1 iodothyronine deiodinase (deiodinase 1) is a selenoenzyme that converts the prohormone T4 to the active thyroid hormone T3 by outer ring deiodination or to the inactive metabolite rT3 by inner ring deiodination. Although selenocysteine has been demonstrated to be essential for the biochemical profile of deiodinase 1, the role of a highly conserved, active site cysteine (C124 in rat deiodinase 1) has not been defined. The present studies examined the effects of a Cys124Ala mutation on rat deiodinase 1 enzymatic function and substrate affinity. At a constant 10-mM concentration of dithiothreitol (DTT), the C124A mutant demonstrated a 2-fold lower apparent maximal velocity (Vmax) and Km for rT3 (KmrT3) than the wild type for outer ring deiodination, whereas the Vmax/Km ratio was unchanged. Similarly, the apparent Vmax and KmT3 sulfate for inner ring deiodination were 2-fold lower in the C124A mutant relative to those in the wild type, with no change in the Vmax/Km ratio. The C124A mutant exhibited ping-pong kinetics in the presence of DTT, and substitution of the active site cysteine increased the KmDTT by 14-fold relative to that of the wild-type enzyme, with no significant effects on KmrT3 or Vmax. The C124A mutant was inhibited by propylthiouracil in an uncompetitive fashion and exhibited a 2-fold increase in K(i)propylthiouracil compared with that of the wild type. KmrT3 was also reduced for the C124A mutant when 5 mM reduced glutathione, a potential physiological monothiol cosubstrate, was used in outer ring deiodination assays. These results demonstrate that thiol cosubstrate interactions with C124 in type 1 deiodinase play an important role in enhancing catalytic efficiency for both outer and inner ring deiodination.     

Is endoluminal abdominal aortic aneurysm repair using an aortoaortic (tube) device a durable procedure?

BACKGROUND: Controversies over the frequency and intensity of the follow-up care of breast cancer patients exist. Some physicians have adopted an intensive approach to follow-up care that consists of frequent laboratory tests and routine imaging studies, including chest radiographs, bone scans, and CT scans, whereas others have established a minimalist approach consisting of only history, physical examinations, and mammograms. OBJECTIVES: Our objective was to evaluate the role of intensive follow-up on detection of breast cancer recurrence and to examine the impact of follow-up on overall survival. METHODS: During a 10-year period (1986-1996), 129 patients with recurrent disease were identified from a prospective database of 1898 breast cancer patients. The patients with recurrent disease were divided into minimalist or intensive groups according to method of detection. RESULTS: Twenty-seven of 126 (21%) patients were assigned to the intensive method of detection group (LFT, CEA, CA 15-3, chest radiograph, CT scan, and bone scan); 99 of 126 (79%) patients were assigned to the minimal detection group (history, physical examination, and mammography). Distant disease to the bone was the most common initial tumor recurrence, at 27%. History, physical examination, and mammography detected recurrent cancer in approximately the same amount of time as LFTs, tumor markers, CT scans, and chest radiographs (P = .960). When the recurrent patients were divided into intensive and minimalist groups and analyzed by time to detection of recurrence, there was no significant difference between the time to detection in those recurrences detected by intensive methods and those recurrences detected by minimalist methods (P = .95). The independent variables age, tumor size, type of surgery, number of positive nodes, time to recurrence, method of detection, and site of recurrence (regional or distant) were subject to univariate and multivariate analysis by the Cox proportional hazards model. Only two variables had an impact on survival by multivariate analysis: early timing of the recurrence (P = .0011) and the site of the recurrence (P = .02). Timing was defined as early (< or =365 days from the time of diagnosis to recurrence) or late (> or =365 days from the time of diagnosis to recurrence). Early recurrence was the first variable found to be significant on stepwise forward regression analysis. The primary site of recurrence was significant at step two. The method of detection--intensive or minimal--did not significantly affect survival (P = .18). CONCLUSIONS: There is no survival benefit to routine intensive follow-up regimens in detecting recurrent breast cancer. Expensive diagnostic tests such as bone scans, CT scans, and serial tumor markers are best used for detection of metastasis in symptomatic patients.     

Ecto-nucleotidases terminate purinergic signalling in the cochlear endolymphatic compartment

There is strong evidence for a purinergic signalling system in the inner ear which regulates auditory sensitivity. This study describes the terminating mechanism for purinergic signalling in the cochlear endolymphatic compartment via ecto-nucleotidases. Exogenous ATP was introduced into the scala media (SM) of the isolated, perfused guinea-pig cochlea, and the effluent was assayed for the adenine nucleotide metabolites by reverse-phase HPLC. Tissue viability was confirmed by fluorescence imaging of cochlear tissues. Extracellular ATP degradation to adenosine was Ca2+/Mg2+ dependent, and was not affected by inhibitors of intracellular ATPases and non-specific alkaline phosphatase. High azide concentration (5 mM) and suramin produced an inhibitory effect on ATP hydrolysis, consistent with inhibition of E-type ATPase activity. The Vmax of ATP hydrolysis (2564 mumol min-1 SM-1) was indicative of high ecto-ATPase activity. Our results support the role of ecto-nucleotidases as a principal mechanism for termination of purinergic signalling within SM, a compartment of the cochlea showing considerable P2X receptor expression.     

Evidence for eosinophil activation in bronchiectasis unrelated to cystic fibrosis and bronchopulmonary aspergillosis: discrepancy between blood eosinophil counts and serum eosinophil cationic protein levels

The purpose of this prospective study was to evaluate the effect of prophylactic antibiotic treatment on postoperative antibiotic spinal wound infection after spinal surgery with instrumentation. Subjects consisted of 110 successive patients that underwent instrumented fusion with Cotrel-Dubousset (CD) or Miami Moss instrumentation. In 56 cases, the indication for surgery was painful spondylolisthesis. The remaining 54 patients were treated for idiopathic scoliosis. In total, 172 spinal procedures were performed and included in the study. Preoperative infection prophylaxis consisting of 2 g cefamandole was administered to all patients. Patients received three doses of 2 g/day cefamandole after surgery for 3 days. Follow-up ranged from 1 to 4 years. The study revealed an early infection in one (0.6%) of the 172 procedures in a patient with spondylolisthesis. A late infection occurred in one (0.6%) patient with the diagnosis of idiopathic scoliosis. In both cases, cultures were positive for Staphylococcus aureus.