Arachidonic acid metabolites and their circadian rhythm in patients with allergic bronchial asthma

The aim of this study was to investigate circadian variation in concentrations of arachidonic acid (AA) metabolites in relation to the circadian pattern in bronchial patency. Blood samples were obtained at 4-hr intervals from 2000 of 1 day until 1400 of the next from 12 diurnally active asthmatic and six diurnally active non-asthmatic patients. Bloods were analyzed for the prostanoids thromboxane A2 (measured as stable metabolite 6-keto-PGF1a), PGE2 and PGF2a. Airways patency was assessed by self-measurement of peak expiratory flow (PEF). In asthmatics, circadian variation was detected in PEF as well as PGE2 and TXB2. The circadian trough of the PEF rhythm closely coincided with the circadian peak of the PGE2 and TXB2 rhythms. In the controls, the PEF was not circadian rhythmic. Of the AA metabolites only 6-keto-PGF1a exhibited 24-hr bioperiodicity in the controls. The controls exhibited a significantly higher circadian mean of PEF (P less than 0.001), while the asthmatics had a lower 24-hr average PGE2 but greater mean TXB2/PGE2 ratio. The obstructive effect caused by the overall 24-hr deficiency of PGE2 in asthmatics is possibly amplified by the increased of TXB2 during the early morning hours. This dissociation of the temporal patterns in TXB2 and PGE2 levels over the 24 hr is discussed as a characteristic finding for asthmatics.     

Corticotropin releasing factor stimulates growth hormone secretion in neonatal rats

Corticotropin releasing factor (CRF) both stimulates ACTH secretion from the pituitary and inhibits secretion of growth hormone (GH) in adult rats through actions in the CNS. The purpose of the present study was to evaluate these pituitary and central actions of CRF in neonatal rats, in which the hypothalamo- pituitary adrenal (HPA) axis is relatively hypo-functional. The results of this study show that central or peripheral administration of CRF evokes a marked dose-related rise in serum corticosterone in 6-day old rats. The same doses of CRF stimulate, rather than inhibit GH secretion. These results suggest that CRF has unique central actions early in ontogeny.     

Cloning and expression of a Streptomyces plicatus chitinase (chitinase-63) in Escherichia coli

4-Methylumbelliferyl (4-MU) glycosides of N-acetylglucosamine oligosaccharides were used as substrates to detect expression of a Streptomyces chitinase in Escherichia coli. Low levels of enzyme were detected when S. plicatus DNA was cloned into a bacteriophage lambda vector (EMBL-4). Subcloning into E. coli plasmids also gave low but detectable levels of enzyme expression. High level expression was achieved by resection of the cloned S. plicatus DNA with Bal31 followed by in-frame fusion to the amino-terminal peptide sequence of beta-galactosidase found in the pUC vectors. The Streptomyces chitinase was secreted into the periplasmic space of E. coli, and its signal sequence was removed. We characterized the activity of the cloned enzyme and compared it to three other purified Streptomyces plicatus chitinases with respect to hydrolysis of the 4-MU oligosaccharides. We found that two of the enzymes form 4-methylumbelliferone much more rapidly from the 4-MU disaccharide than from the trisaccharide. These same enzymes convert the 4-MU trisaccharide primarily to diacetylchitobiose and the 4-MU monosaccharide, a nonfluorescent product. The latter compound is not hydrolyzed appreciably by any of the enzymes. On the basis of these results, we suggest a new definition of "exo" and "endo" chitinase that differs from that found in the literature. We propose that exochitinase activity be defined as processive action starting at the nonreducing ends of chitin chains with release of successive diacetylchitobiose units, and that endochitinase activity be defined as random cleavage at internal points in chitin chains.     

Biochemical pathways in prokaryotes can be traced backward through evolutionary time

For the first time, a credible prokaryotic phylogenetic tree is being assembled by Woese and others using quantitative sequence analysis of oligonucleotides in the highly conservative rRNA. This provides an evolutionary scale against which the evolutionary steps that led to the arrangement and regulation of contemporary biochemical pathways can be measured. This paper presents an emerging evolutionary picture of aromatic amino acid biosynthesis within a large superfamily assemblage of prokaryotes that is sufficiently developed to illustrate a new perspective that will be applicable to many other biochemical pathways.      

Circadian rhythms in hot flashes in natural and surgically-induced menopause

The aim of this study was to investigate circadian and ultradian variations in menopausal hot flash. The number of hot flashes per 2-hr period was collected from 25 diurnally-active, perimenopausal women for 1 week in January or February of each year for 3 consecutive years. Fourteen women were experiencing natural menopause (NM) (mean age 51.9 years) and 11 were experiencing surgically-induced menopause (SIM) (mean age 52.0 years). The difference in the number of hot flashes between the two types of menopause at each clock time was not statistically significant; neither was the mean number of hot flashes per 24 hr different between the two groups (Student's t-test). Data when normalized for each woman and placed end-to-end revealed by cosinor analysis circadian rhythmicity in the SIM group (P = 0.02) but not in the NM group. A 12-hr periodicity was detected in both groups (P less than 0.001 for both). An 8-hr rhythm was detected only for the NM group (P = 0.04). Both groups combined exhibited statistically significant rhythmicities with periods of 24 hr (P = 0.003), 12 hr (P less than 0.001) and 8 hr (P = 0.005). Regardless of the type of menopause, the women could be separated into two groups based on the temporal pattern of hot flashes during the day. One group was defined by the occurrence of peak frequency of flashes during the morning (0400-0959), while the second group was defined by the occurrence of the peak in the evening (1600-2159).(ABSTRACT TRUNCATED AT 250 WORDS)     

USE OF SENSORY EVALUATION FOR MEASURING DEODORIZING EFFECTS OF AN AIR CONDITIONER

The application of sensory methodology for measuring deodorizing effect of an air conditioner equipped with electric plasma was introduced. Deodorizing effect was measured using chemical and sensory methods at different time (0, 30 and 60 min) and mode (control, blowing and cooling) of an air conditioner. Smoke from a roll of cigarette in a closed room was used as a source of odor and the concentrations of acetic acid and ammonia were measured as odorous chemical components. As one of the sensory methods triangle test was used and as a first step to obtain deodorizing effects by triangle test, the threshold of each panelist was obtained as the log dilution ratio of odor concentration at which the difference from odorless air was detected. The odor concentration at each time and mode was calculated using the threshold of the panel and the deodorizing effect was obtained on the basis of the odor concentration. In addition to a triangle test, scaling methods such as category scaling or magnitude estimation were used to measure deodorizing effect of an air conditioner. Deodorizing effects by scaling methods were calculated based on odor intensity with time at each mode. The regression analysis was done between the efficacy of deodorizing effect by sensory test and those by acetic acid and ammonia, the R² values of the regression equations for triangle test, category scale, and magnitude estimation were 0.84, 0.72 and 0.69, respectively. Deodorizing effect by triangle test explained the decrease of acetic acid and ammonia better than those by category scaling or magnitude estimation while high cost and time consuming labor involved in triangle tests reduced the merit. The results of this study demonstrated that various sensory methods could be used to measure deodorizing effect of air conditioners and further researches on fast and reliable methods are needed to establish the official procedures.     

Equilibria for the adsorption of antibiotics onto neutral polymeric sorbents: Experimental and modeling studies

The objective of this work was to study the equilibria for adsorption of three antibiotics (penicillin V, tetracycline, and cephalosporin C) from water onto commercially available neutral polymeric sorbents. The pH was observed to be an important factor in adsorption as our results suggest that the neutral forms of penicillin V and cephalosporin C are preferentially adsorbed onto the neutral sorbents. Also, sorbent surface chemistry was observed to be important for adsorption, as the antibiotics adsorbed more favorably (both in terms of affinities and enthalpies) onto the aromatic sorbent as compared to the aliphatic ester sorbent. In addition to these thermodynamic measurements, molecular modeling studies and Monte Carlo simulations suggest that adsorption onto aromatic sorbents may involve specific interactions between the planar regions of the antibiotic molecules and the phenyl rings of the aromatic sorbent. The interaction energies predicted from Monte Carlo simulations were observed to provide qualitative agreement with experimentally determined adsorption affinities. (c) 1995 John Wiley & Sons, Inc.