Thermal Rearrangement of 4-Alkyl-1,2,4-triazoles. Rearrangements in the Crystalline State

Studies of the thermolyses of 4-alkyl substituted 1,2,4-triazoles was reviewed. They were observed to rearrange at 200–350 °C to the corresponding 1-alkylated triazoles. When substituted in the 4-position with aryl- or vinylic substituents the triazoles were inert to thermolysis, contrary to what was observed for the 4-alkyl- and 4-allyl substituted systems. The mechanisms for the reactions were elucidated, e.g., by studies of substituents effects and by kinetic measurements in solution as well as for the neat samples. Reactions in solutions were slow. The rearrangements in melts of the neat triazoles readily proceeded to the products, and were proposed to take place via a series of nucleophilic displacement steps. X-ray crystallographic measurements of selected structures, showed that the interatomic distances and angles between the relevant atoms in these structures, to a large degree resembled the geometry expected for the S_N2-type transition states proposed for the rearrangement mechanism. Thus, thermolyses of a series of triazole structures at temperatures below their melting points, confirmed that rearrangements actually did take place. The “kinetics” of the reactions in the crystalline state were investigated and rate constants and thermodynamic data were correlated with the structural characteristics of the crystals.     

The diet of two species of Isoperla (Plecoptera: Perlodidae) in relation to season,site, and sympatry

The seasonal change in gut contents of nymphs of Isoperla grammatica and I. difformis from six streams in southern Sweden was analysed. Both species had ingested a variety of benthic prey and vegetable matter, predominantly diatoms. Some seasonality was evident with high percentages of diatoms in spring in I. grammatica, and in autumn in I. difformis. The scope of food was larger in the latter species which contained about equal proportions of vegetable matter, chironomids, mayfly, stonefly, and black fly larvae. In I. grammatica plant matter and chironomids dominated strongly, comprising > 50% of the gut contents on an annual basis, > 90 % in spring. While small nymphs of I. difformis contained a low proportion of animal matter, only gradually increasing with size, the nymphs of I. grammatica were carnivorous from very early instars. Both species switched to a temporarily strong utilization of algae in spring. This differed among sites, and appeared to reflect differences in insolation and thus the availability of algae. There was a significant negative relationship between the mean densities of Isoperla nymphs and the proportion of animal material found in the guts of I. grammatica (R ² = 0.86). Considering the density of I. grammatica alone, the relationship was weaker (R ² = 0.56). A positive correlation between predator and prey size was observed. With chironomid prey the size range increased with predator size. With simuliid prey, however, prey size increased with predator size in such a way that it suggests selection rather than just an expanding prey size range. Correlations were stronger and regression coefficients significantly higher for I. grammatica than for I. difformis. We suggest that I. grammatica, which ingests a much wider size range of prey might choose prey of optimal sizes more readily than the more synchronously developing I. difformis. Although the life cycles of the two species are staggered, overlap in size distribution indicates that competition for food could be important in spring. However, observed differences in diet should facilitate coexistence. Gut content differences might in turn be accomplished through microhabitat segregation.     

Comparison of an electrochemiluminescent homogenous immunoassay and an ELISA for monitoring productivity in mammalian cell bioreactors

Summary An Enzyme Linked Immuno Sorbent Assays (ELISA) and an Electro-chemiluminescent Immuno Assay (CIA) are compared for the purpose of monitoring product formation in mammalian cell bioreactors. The ELISA had a relative standard deviation of 10%, compared to 8% for the CIA . The CIA was found to be a fast and accurate alternative to the ELISA. The use of more than one immuno assay format was also shown to provide additional insight into process performance.     

Effects of dexamethasone on multiplication and differentiation of rat adipose precursor cells

The effects of dexamethasone (DEX) on adipose precursor cells from rat adipose tissue were studied in primary culture. When added from the beginning of culture in media containing untreated fetal calf serum (SM), serum treated with charcoal to remove steroid hormones (CSM), or serum-free medium (SFM), DEX inhibited cellular growth. Lipoprotein lipase (LPL) as well as glycerophosphate dehydrogenase (GPDH) activities, markers of cellular differentiation, were also inhibited, except in CSM where LPL was stimulated. When added after cellular confluence, however, DEX had opposite effects and now stimulated cellular differentiation. This effect was highly dependent on insulin. These studies demonstrate that DEX affects adipose precursor cells in several ways, depending on the type of culture medium, the time period of exposure, and the presence of insulin.     

A quantitative and qualitative study of blood monocytes in patients with bronchogenic carcinoma

Summary Absolute circulating number and functions of blood monocytes (i.e., pinocytosis, phagocytosis, and chemotaxis) were studied in 25 patients with untreated bronchogenic carcinoma and in 28 control subjects. The absolute circulating monocyte count was increased in 20 (80%) of the patients. There was no difference in the pinocytic and phagocytic activity of patient and control monocytes. In contrast, patient monocytes showed depressed chemotactic responsiveness. This defect was more severe in small cell anaplastic carcinoma than in the other histologic types of bronchogenic carcinoma (P=0.001), and may explain the difference in macrophage infiltration seen in solid tumours of the lung. There was no correlation between chemotaxis and clinical stage. Depressed chemotaxis may be related to a plasma factor, since patient plasma inhibited the chemotaxis of control monocytes as well as the activity of chemotactic agents. The defective chemotaxis and the presence of plasma inhibitory activity may interfere with the ability of blood monocytes to accumulate as macrophages in tumour sites. Abbreviations used in this paper are: MCR, monocyte chemotactic response; SAC, small cell anaplastic bronchogenic carcinoma; OBC, non-small cell bronchogenic carcinoma MEM, Eagle's minimal essential medium; CFI, chemotactic factor inhibitor(s); HSA, human serum albumin     

Technique for Simultaneous Determination of [35S]Sulfide and [14C]Carbon Dioxide in Anaerobic Aqueous Samples

A technique for the simultaneous determination of [³⁵S]sulfide and [¹⁴C]carbon dioxide produced in anaerobic aqueous samples dual-labeled with [³⁵S]sulfate and a ¹⁴C-organic substrate is described. The method involves the passive distillation of sulfide and carbon dioxide from an acidified water sample and their subsequent separation by selective chemical absorption. The recovery of sulfide was 93% for amounts ranging from 0.35 to 50 μmol; recovery of carbon dioxide was 99% in amounts up to 20 μmol. Within these delineated ranges of total sulfide and carbon dioxide, 1 nmol of [³⁵S]sulfide and 7.5 nmol of [¹⁴C]carbon dioxide were separated and quantified. Correction factors were formulated for low levels of radioisotopic cross-contamination by sulfide, carbon dioxide, and volatile organic acids. The overall standard error of the method was ±4% for sulfide and ±6% for carbon dioxide.