Characterization and comparison of commercially available German and American cockroach allergen extracts.

BACKGROUND: In this study we examine the variability among unstandardized cockroach allergen extracts. METHODS: We obtained 24 aqueous and glycerinated cockroach allergen extracts from nine manufacturers. We used previously characterized cockroach extracts, E2-Cg and E2-Ca, as references. The modified ninhydrin assay was used to determine protein concentration of each extract. Relative potencies of extracts were determined by competition ELISA, using a human allergic serum pool. Bla g 1 and Bla g 2 levels of glycerinated German cockroach extracts were determined by ELISA using monoclonal antibodies. Extracts were also analysed by SDS-PAGE. RESULTS: Commercial cockroach allergen extracts had highly variable protein contents that were lower than the protein contents of the references. Electrophoretic data confirmed the presence of a variable number and intensity of protein bands in extracts among manufacturers. The relative potencies of the commercial extracts were between 10 and 782 BAU/mL for German cockroach and 10-250 BAU/mL for American cockroach. The mean Bla g 1 content of the commercial extracts was significantly lower than that of the reference (P = 0.001). The mean Bla g 2 content of the commercial extracts was higher than that of the E2-Cg reference but the Bla g 2 levels were more variable compared to Bla g 1. In glycerinated German cockroach extracts, protein concentrations, relative potencies and specific allergen levels were significantly correlated (P < 0.001). CONCLUSION: Our tests indicate that commercially available cockroach allergen extracts are variable in protein content, electrophoretic banding patterns, relative potency and Bla g 2 levels. In glycerinated German cockroach extracts, protein concentrations, relative potencies and specific allergen levels were significantly correlated.

Specific collagenolysis by gelatinase A, MMP-2, is determined by the hemopexin domain and not the fibronectin-like domain.

In view of the essential role of the hemopexin domain of the traditional interstitial collagenases, MMP-1, -8, -13 and MT1-MMP (MMP-14), in determining specific collagen cleavage we have studied the function of this domain in MMP-2, relative to that of the fibronectin-like domain that promotes gelatinolysis. Although the fibronectin-like domain promotes avid binding to collagen, our data demonstrate that the catalytic and hemopexin domains of MMP-2 are sufficient to effect the critical step in cleavage of rat type I collagen into 3/4 and 1/4 fragments. The mechanism of MMP-2 cleavage of collagen proceeds in two phases, the first resembling that of the interstitial collagenases, followed by gelatinolysis, promoted by the fibronectin-like domain.

The role of exon 5 in fibroblast collagenase (MMP-1) substrate specificity and inhibitor selectivity.

Interstitial collagen is degraded by members of the matrix metalloproteinase (MMP) family, including MMP-1. Previous work has shown that the region of MMP-1 coded for by exon 5 is implicated both in substrate specificity and inhibitor selectivity. We have constructed a chimeric enzyme, the exon 5 chimera, consisting primarily of MMP-1, with the region coded for by exon 5 replaced with the equivalent region of MMP-3, a noncollagenolytic MMP. Unlike MMP-3, the exon 5 chimera is capable of cleaving type I collagen, but the activity is only 2.2% of trypsin-activated MMP-1. 'Superactivation' of the chimera has no discernible effect, suggesting that the salt bridge formed in 'superactive' MMP-1 is not present. The kinetics for exon 5 chimera cleavage of two synthetic substrates display an MMP-3 phenotype, however, cleavage of gelatin is slightly impaired as compared to the parent enzymes. The K(iapp) values for the exon 5 chimera complexed with synthetic inhibitors and N-terminal TIMP-2 also show a more MMP-3-like behaviour. However, the k(on) values for N-terminal TIMP-1 and N-terminal TIMP-2 are more comparable to those for MMP-1. These data show that the region of MMP-1 coded for by exon 5 is involved in both substrate specificity and inhibitor selectivity and the structural basis for our findings is discussed.

Membrane type 1 matrix metalloproteinase and gelatinase A synergistically degrade type 1 collagen in a cell model.

A fibrosarcoma cell line transfected with the matrix metalloproteinase MT1 MMP showed an enhanced ability to degrade 14C-labelled collagen films. As previously shown for proMMP 2 activation, TIMP 1 was an ineffective inhibitor of the process of collagenolysis whereas TIMP 2 was efficient and completely prevented collagen degradation. In the presence of the calcium ionophore, ionomycin, proteolytic processing of MT1 MMP was restricted and collagenolysis did not occur indicating that the 63 kDa form of the enzyme is not a functional collagenase. The collagenolytic activity of MT1 MMP was shown to be enhanced by the addition of proMMP 2, but TIMP 1 inhibition remained poor relative to that of TIMP 2. The study demonstrated that synergy between two non-conventional collagenases effectively degrades insoluble pericellular collagen. Due to the membrane localisation of MT1 MMP, this could potentially occur in a highly localised manner.

Pulse oximetry in infants of < 1500 gm birth weight on supplemental oxygen: a national survey.

OBJECTIVE: To determine practices related to the use of pulse oximetry in monitoring infants of < 1500 gm birth weight on supplemental oxygen. STUDY DESIGN: A mailing list of all neonatal intensive care units with accredited Neonatal-Perinatal Fellowship programs was prepared. A questionnaire was prepared and mailed to collect information on the following: Method used for noninvasive monitoring of oxygen therapy, acceptable maximum and minimum arterial pulse oxygen saturation levels, high and low alarm settings, and whether oxygen was administered at a fixed or variable rate. RESULTS: A response rate of 70% to 85% was achieved for different items of the questionnaire. A wide variation exists regarding acceptable arterial pulse oxygen saturation levels and alarm settings. Many units accepted an arterial pulse oxygen saturation level of 100% or set the high alarm at 100%. CONCLUSION: There is a need for greater awareness of the potential for hyperoxemia that may result from accepting an arterial pulse oxygen saturation level of 100% or setting high alarms at 100%. We urge stricter adherence to published recommendations.

Sociodemographic factors and obesity in preadolescent black and white girls: NHLBI's Growth and Health Study.

The association of sociodemographic and family composition data with obesity was studied in 1213 black and 1166 white girls, ages 9 and 10, enrolled in the National Heart, Lung, and Blood Institute's Growth and Health Study. Obesity was defined as body mass index at or greater than age- and sex-specific 85th percentile as outlined in the Second National Health and Nutrition Examination Survey. The prevalence of obesity was higher for pubertal girls than for prepubertal girls and for girls with older mothers/female guardians. As odds ratio of 1.14 was observed for each 5-year increase in maternal age. Obesity was less common for girls with more siblings; the odds for obesity decreased by 14% for each additional sibling in the household. In blacks, the prevalence of obesity was not related to parental employment or to parental education. In whites, the odds of obesity were higher for girls with no employed parent/guardian in the household and for girls with parents or guardians with lower levels of educational attainment. Examining the associations between sociodemographic factors and risk of childhood obesity provides important clues for understanding racial differences in obesity, a major risk factor for coronary heart disease.

Childhood depression, anxiety, and aggression: a reanalysis of Epkins and Meyers (1994).

Research on the constructs of childhood depression and anxiety has typically found that the 2 traits are highly correlated. In a study of the construct validity of childhood depression, anxiety, and aggression, Epkins and Meyers (1994) concluded that, despite some mixed results, the 3 constructs demonstrated adequate convergent and discriminant validity. We reexamined the results of the Epkins and Meyers study in 2 new analyses--a focused comparison of correlational patterns among the traits and a confirmatory factor analysis--and found no support for the discriminant validity of depression and anxiety and only weak support for their convergent validity.

Productivity in the '90s. Lessons from the assembly line.

Defining the right product at the right moment is important. But how long it takes to develop and introduce that product can have a dramatic impact on both customer satisfaction and ROI. Here's a metaphorical approach to streamlining the process.

Enteral feeding in the hypoalbuminemic patient.

Previous studies have correlated intolerance of isotonic, intact protein enteral solutions with hypoalbuminemia. The purpose of this retrospective study was to determine whether the level of serum albumin (SA) influenced tolerance of such an enteral nutrient solution (ENS). All patients who received Entrition during 1987 for a minimum of 48 hr were studied for the first 10 days of enteral feeding. Documentation included SA, medications, stool frequency, gastric residuals (GR), and daily caloric intake. ENS intolerance was defined as greater than 3 stools/day for greater than 48 hr or GR greater than twice the hourly infusion rate for greater than 48 hr. Patients were categorized into two groups: those with SA greater than or equal to 2.5 g/dl (group I) and those with SA less than 2.5 g/dl (group II). Of 88 patients studied, 48 (86%) in group I and 28 (88%) in group II tolerated the ENS. Eight (14%) in group I and 4 (12%) in group II experienced ENS intolerance. There was no statistically significant difference in the frequency of ENS intolerance between these two groups (p less than 0.05). Also, 97% of all those with a SA less than 2.5 g/dl were fed 80% or more of their estimated caloric requirements. We concluded that ENS tolerance was not affected by the SA level and patients with hypoalbuminemia (SA less than 2.5 g/dl) could be fed enterally.

Home care: what do the patients say about it?

This article describes the results of an evaluation of Home Care Services, conducted by a patient questionnaire in Middlesex County. At the beginning, a brief description of Home Care Services sponsored by the Ontario Department of Health is provided. Home Care services previously have been known to help reduce the cost of medical services and increase the comprehensiveness of care for individual patients by transferring care to their home setting when applicable. All patients discharged between May 1, 1972 and June 30, 1972 were mailed the questionnaire. Information returned was analysed and results are discussed in the article. Our main objective was to evaluate the consumer's response to these services. Results were favorable indicating a strong acceptance of this form of community health service. It is hoped that this high degree of patient acceptance would encourage physicians to make greater use of this existing community service. Several minor criticisms were received and will hopefully help improve the quality of service provided in the future.