Biomedical subjects
Publications and source records attributed to J Spengler.
Alpha-trifluoromethyl alpha-amino acids with unsaturated side-chains have been prepared from 5-fluoro-4-trifluoromethyloxazole and allyl, propargyl as well as terpene alcohols in a one-pot procedure.
5-Benzyloxy-4-trifluoromethyl-1,3-oxazoles, obtained from 5-fluoro-4-trifluoromethyloxazoles and benzyl alcohols, are capable for rearrangements. A 1,3 shift of a benzyl group is the key step of a new general route toward alpha-trifluoromethyl substituted aromatic and heteroaromatic amino acids, demonstrating that 5-fluoro-4-trifluoromethyl-1,3-oxazole is a synthetic Tfm-Gly equivalent. On reaction with benzpinacol partially fluorinated oxazoles are transformed into bis(trifluoromethyl) substituted 2,5-diamino adipic acid and N-benzoyl-2-benzhydryl-3,3,3-trifluoroalanine.
Amino acid sequences and linear or head-to-tail cyclopeptides can be represented conveniently in one-line text formulae using the three-letter symbols. However, other - but nonetheless important - topologies of peptides are 'side chain-to-head (or tail)', 'backbone-to-backbone', 'side chain-to-side chain' cyclopeptides, 'side chain-to-side chain' connected peptide strands, and branched peptides (like peptide dendrimers). In general, such structures cannot be described using the three-letter symbols in one-line text: a chemical structure editor is required for symbolic representations according to the IUPAC-IUBMB recommendations. The aim of this contribution is to offer an unambiguous and general nomenclature system that enables researchers to represent all cyclic and branched homo- and hetero-detic peptides in a coherent manner in one-line text - as long as their as constituents can be represented in (three)-letter codes. The application of this new nomenclature would overcome the existing difficulties and provide a way to express complex situations in the shortest way in order to highlight more clearly the salient points in a given scientific communication.
Intussusception of parts of the intestine in adulthood is a rare cause of ileus. In more than 90 % of all cases there is a malignant or benign tumour situated in the parts of the intestine affected. We describe a 55-year-old patient who was admitted to hospital as an emergency because of signs of a proximal intestinal obstruction. Abdominal sonography suggested the diagnosis of a typical jejunal intussusception, whereas gastroscopy yielded no pathological findings. Laparotomy was performed immediately and confirmed the diagnosis. After intraoperative de-invagination 9 cm of jejunum and an inflammatory fibrinoid polyp of 3 cm were resected.
Nine families of a public housing development in Boston were enrolled in a pilot asthma intervention program designed to gather dense environmental data and generate hypotheses about the relative importance of different contaminants and the viability of interventions. Despite formidable challenges working with this inner-city population, the project team succeeded in gaining active support for the project by forming a partnership with a community-based organization and by building positive relationships between the field team and the residents. Families were provided with physical interventions such as air filters, industrial cleaning and mattress covers to each apartment. Indoor temperature was high and relative humidity low during winter. Insulation of exposed steam pipes did not lower temperature. Cockroach, mouse and pet antigen levels were variable and frequently high in settled dust. Viable fungal spore levels were variable and high in some apartments. Dust-mite allergen levels were below the level of concern. Industrial cleaning led to transient reduction in mouse and cockroach antigen burden. Mattress and pillow covers lowered dust-mite antigen in bedrooms, but not living rooms. Nitrogen dioxide (NO2) levels exceeded ambient concentrations due to use of gas stoves and concentrations of particulate matter with aerodynamic diameter <2.5 microm (PM2.5) were above ambient levels because of smoking. Air filtering systems did not reduce PM levels. Several volatile organic compounds (VOCs) were above adverse risk concentrations. We hypothesize that our findings are consistent with a multifactorial model for exacerbation of asthma in this population and that no single problem dominates.
Many ice rink arenas have ice resurfacing equipment that uses fossil fuel as power. The combustion byproducts are a major source of contamination. Ventilation along with other pollution source control measures is the most widely applied strategy to lower the contaminant level below the threshold limit and maintain acceptable indoor air quality (IAQ). A computational fluid dynamics (CFD) model has been developed and used to predict the contaminant concentrations, air velocity, and air temperature distributions in ice rinks. The numerical results agree reasonably with the corresponding experimental data for both steady-state and transient conditions. The CFD model is a useful and inexpensive tool to investigate ventilation parameters, such as air distribution methods, ventilation effectiveness, air exchange rates, and various ventilation control strategies.
Suspension conditioning by ultrasound induced particle aggregation in a 3.3 MHz standing wave field was investigated in lab- and pilot scale sedimentation reactors (sonicated volume approx. 375 ml and 10 l). These were equipped with a variable number of acoustically transparent film (ATF) elements, inserted perpendicular to the sound propagation direction. ATFs control the development of undesired large-range Eckart-type acoustic streaming and thermal convection. ATF insertion led to increased separation efficiency especially for particles smaller than 10 microns. Results with a varied geometric set-up indicate the existence of an optimum for the number of ATFs inserted. Optical investigation of particle behaviour in different pilot plant configurations showed reduced streaming within the divided 24 mm pathlength sonic chamber, whereas at 100 mm pathlength, turbulent streaming dominated.
The ultrasonic standing-wave manipulation of suspended eukaryotic cells, bacteria and submicron latex or silica particles has been examined here. The different systems, involving plane or tubular ultrasonic transducers and a range of acoustic pathlengths, have been designed to treat suspension volumes of analytical scale i.e. 5 ml to 50 microliters for both sample batch and 'on-line' situations. Frequencies range from 1 to 12 MHz. The influence of secondary cell-cell interaction forces in determining the cell concentration dependence of harvesting efficiency in batch sedimentation systems is considered. Applications of standing wave radiation forces to (1) clarify cell suspensions, (2) enhance particle agglutination immunoassay detection of cells or cellular products and (3) examine and enhance cell-cell interactions in suspension are described.
A new method for the preparation of N-methylamino acids and some of their derivatives starting from hexafluoroacetone protected amino acids is described. The new concept results in saving of steps compared to conventional protection/activation techniques. Protection and deprotection proceed without recemization.
We followed a cohort of 1,150 children for 3 yr to investigate long-term effects of ambient ozone. Nine study sites were selected on the basis of air-quality data to represent a broad range of ozone exposure. In 1994, 1995, and 1996 lung function was recorded biannually, always before and after summertime. The effect of ozone was analyzed with regression analyses and study-site, a child's sex, atopy, passive smoking, baseline lung function, and increase in height were considered as confounding variables. A negative effect of summertime ozone on the pre- to post-summer-time change in FEV(1) (ml/d) was present in 1994 (beta = -0.019 ml/d/ppb; p < 0.01) and in 1995 (beta = -0.017 ml/d/ ppb; p < 0.05), but not in 1996 (beta = 0. 004 ml/d/ppb; p = 0.6); corresponding estimates for FVC were in 1994: beta = -0.022 ml/d/ppb, p < 0.005; 1995: beta = -0.018 ml/d/ppb, p < 0.05; and 1996: beta = 0.006 ml/d/ppb, p = 0.46. When all three study years were considered simultaneously, i.e., the changes in lung function between each of two subsequent surveys being the dependent variable, summertime ozone was associated with a lesser increase in FEV(1) (beta = -0.029 ml/d/ppb; p < 0.001), FVC (beta = -0.018 ml/d/ppb; p < 0.001), and MEF(50) (beta = -0.076 ml/s/d; p = 0.001). No consistent associations were observed for lung function and NO(2), SO(2) and PM(10). Long-term ambient ozone exposure might negatively influence lung function growth.
A large scale study of human exposure to nitrogen dioxide (NO2) was conducted in the Los Angeles Basin, the only metropolitan area in the United States that exceeds the NO2 NAAQS. Data are available for a population representative sample of 482 households and 682 individuals. Personal exposures, as well as indoor and outdoor home levels, were monitored using passive time-integrating filter badges. Monitoring extended over a one-year period (May 1987 to May 1988), with each individual providing two consecutive days of data. Information was also collected on activity patterns, household and personal characteristics, and spatial and temporal variables. This paper describes the study design, summarizes the sample characteristics and representativeness, and presents the distribution of personal, indoor, and outdoor NO2 concentrations recorded by the monitors. Over the entire sample, median personal and outdoor levels were 35 ppb; median indoor levels were 24 ppb. Personal exposures for those in homes with gas ranges with pilot lights average 10 ppb greater than those with electric ranges, and 4 ppb greater than those with gas ranges without pilot lights. Forty percent of the variation in indoor concentrations is explained by outdoor levels; 59 percent of the variation in personal exposures is explained by indoor levels; and 48 percent of the variation in personal exposures is explained by outdoor levels.
Daily diaries of respiratory symptoms are a powerful technique for detecting acute effects of air pollution exposure. While conceptually simple, these diary studies can be difficult to analyze. The daily symptom rates are highly correlated, even after adjustment for covariates, and this lack of independence must be considered in the analysis. Possible approaches include the use of incidence instead of prevalence rates and autoregressive models. Heterogeneity among subjects also induces dependencies in the data. These can be addressed by stratification and by two-stage models such as those developed by Korn and Whittemore. These approaches have been applied to two data sets: a cohort of school children participating in the Harvard Six Cities Study and a cohort of student nurses in Los Angeles. Both data sets provide evidence of autocorrelation and heterogeneity. Controlling for autocorrelation corrects the precision estimates, and because diary data are usually positively autocorrelated, this leads to larger variance estimates. Controlling for heterogeneity among subjects appears to increase the effect sizes for air pollution exposure. Preliminary results indicate associations between sulfur dioxide and cough incidence in children and between nitrogen dioxide and phlegm incidence in student nurses.
An aqueous mixture of p-phenylenediamine dihydrochloride, resorcinol and hydrogen peroxide, incubated for 30 min at 37 degrees C, was not mutagenic in the Ames test and in the mouse lymphoma assay and did not produce chromosome aberrations in human lymphocytes, whereas the same mixture without resorcinol was mutagenic in the Ames test and the chromosome aberration assay, probably due to the formation of Bandrowski's base. The formation of mutagenic Bandrowski's base and other reactive products could be demonstrated by thin-layer chromatography and subsequent Ames testing. Preincubation for 0-7 h of 5 different oxidative mixtures of p-phenylenediamine dihydrochloride and various couplers at 37 degrees C resulted in mutagenicities in the Ames test ranging from 'very strong effects' at 0 or 0.5 h for 2,4-diaminoanisole dihydrochloride to 'not mutagenic' at up to 7 h preincubation time for a recently developed alternative coupler. A comparable ranking of mutagenic potencies of the same mixtures could be obtained by Ames tests with dyed buffalo hair strands, either tested directly on the agar plates or by testing the solvent extracts of the colored strands. The optimal combination without any sign of mutagenic tendency was finally tested in a commercially available hair dye formulation. This complex mixture was also not mutagenic in the Ames test. Our main conclusions are as follows. (I) Oxidative hair dye mixtures of p-phenylenediamine dihydrochloride and non-mutagenic couplers are not mutagenic if tested under normal conditions of use; the formation of mutagenic reaction products (such as Bandrowski's base) can be prevented if the oxidative reaction time is limited to 30 min and if about equimolar proportions of para to meta compounds are used. (II) Optimal non-mutagenic combinations of primary intermediates (such as p-phenylenediamine dihydrochloride) and couplers can be evaluated in the Ames test by either time-dependent preincubation of the mixtures or the described test protocol with hair strands.
20 non-related patients suffering from autosomal dominantly polycystic renal disease were HLA-A, -B, -C and -DR typified and the HLA frequencies were compared with the normal population. Tissue typing was performed using the lymphocytotoxicity test using 180 well-characterized test sera. In contrast to the literature no significant differences were found. However, the value of erythrocytic phosphoglycolate-phosphatase-phenotyping should be checked in the genetic control and consultation.
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As part of a long-range, prospective study of the health effects of air pollution, approximately 8,000 children from 6 yrs to 10 yrs of age from 6 communities had questionnaires completed by their parents and had simple spirometry performed in school. Comparisons were made between children living in homes with gas stoves and those living in homes with electric stoves. Children from households with gas stoves had a greater history of respiratory illness before age 2 (average difference, 32.5/1,000 children) and small but significantly lower levels of FEV1 and FVC corrected for height (average difference, 16 ml and 18 ml, respectively). These findings were not explained by differences in social class or by parental smoking habits. Measurements taken in the homes for 24-h periods showed that NO2 levels were 4 to 7 times higher in homes with gas stoves than in homes with electric stoves. However, these 24-h measurements were generally well below the current federal 24-h outdoor standard of 100 micrograms/m3. Short-term peak exposures, which were in excess of 1,100 micrograms/m3, regularly occurred in kitchens. Further work will be required to determine the importance of these short-term peaks in explaining the effects noted.
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An epidemiological survey was made in 9 cities and towns of Russia to study the influence of negative characteristics of an inhabited place on respiratory diseases in children. About 6,000 questionnaires questioning the living conditions of young children were filled in. The questionnaire pays a particular attention to frequent leakages and mould in the flats. To study the children's health status, a number of questions of the questionnaire were devoted to the present of some respiratory and allergic diseases (symptoms) reflecting the influence of unfavorable factors within the inhabited place. The logistic regression analysis was used to examine the relationship between the characteristics of the inhabited place of schoolchildren and the presence of respiratory and allergic diseases. A significant relationship was established between the frequent leakages, the presence of mould in the rooms, and the risk for bronchial asthma, persistent productive cough, persistent stertorous respiration, respiratory infections and any manifestations of allergic reactions in children.