Sucrose:sucrose fructosyltransferase and fructan:fructan fructosyltransferase from allium cepa

Sucrose: sucrose fructosyltransferase and fructan:fructan fructosyltransferase were isolated from the inner leaf bases of bulbing onion plants (Allium cepa) and separated by gel filtration on Bio-Gel P-150. Sucrose:sucrose fructosyltransferase produced only one trisaccharide, 1^F-fructosylsucrose, from sucrose. Fructan:fructan fructosyltransferase produced tetrasaccharide and higher polymers from trisaccharide. The trisaccharide found in the greatest concentration in onion, 6^G-fructosylsucrose, was produced from 1^F-fructosylsucrose by fructan:fructan fructosyltransferase and was not a product of sucrose:sucrose fructosyltransferase.     

Reflexivity and countertransference in a psychiatric cultural consultation clinic

A Mexican-American woman who complained of persistent head pain and a bothersome voice was seen by a team consisting of a psychiatrist, social scientists, and spiritualist healers in a Cultural Consultation Clinic of a Psychiatric Consultation Liaison Service. This single case is analyzed to provide an understanding of the interpretive dimensions of psychiatric practice. It is argued that a hermeneutic analysis of clinical phenomena focuses attention on three distinct aspects of interpretation: on the interpretation by clinicians and clients of the discourse of the other in terms of their own clinical models; on the influence of deeply embedded personal meanings on this interpretive process; and on the role of the observer in clinical ethnography. It is argued that to sustain a hermeneutic analysis of psychiatric practice, an account of transference and countertransference in terms of interpretation theory will have to be developed.     

Human plasma high density apolipoprotein A-I: Effect of protein-protein interactions on the spontaneous formation of a lipid-protein recombinant

The effect of the self-association of apolipoprotein A-I on the dynamics of lipid-protein complex formation was studied. Treatment of self-associated apolipoprotein A-I with guanidine hydrochloride initially resulted in dissociation of the oligomers into monomers and subsequent denaturation of the monomers. The association of monomeric and oligomeric apolipoprotein A-I with dimyristoylphosphatidylcholine resulted in identical lipid-protein recombinants as determined by chemical analysis and gel-filtration column elution profiles. Denaturation of a recombinant with guanidine hydrochloride indicated that the protein is more stable in a lipid-protein recombinant than as an oligomer; however, self-association does decrease the rate of lipidprotein recombinant formation. Because apolipoprotein A-I is more stable when it is associated with lipid, we conclude that the association of this protein with a variety of lipids is subject to kinetic control.     

Reconstituted low density lipoprotein: A vehicle for the delivery of hydrophobic fluorescent probes to cells

Previous studies have shown that the cholesteryl ester core of plasma low density lipoprotein (LDL) can be extracted with heptane and replaced with a variety of hydrophobic molecules. In the present report we use this reconstitution technique to incorporate two fluorescent probes, 3-pyrenemethyl-23, 24-dinor-5-cholen-22-oate-3β-yl oleate (PMCA oleate) and dioleyl fluorescein, into heptane-extracted LDL. Both fluorescent lipoprotein preparations were shown to be useful probes for visualizing the receptor-mediated endocytosis of LDL in cultured human fibroblasts. When normal fibroblasts were incubated at 37°C with either of the fluorescent LDL preparations, fluorescent granules accumulated in the perinuclear region of the cell. In contrast, fibroblasts from patients with the homozygous form of familial hypercholesterolemia (FH) that lack functional LDL receptors did not accumulate visible fluorescent granules when incubated with the fluorescent reconstituted LDL. A fluorescence-activated cell sorter was used to quantify the fluorescence intensity of individual cells that had been incubated with LDL reconstituted with dioleyl fluorescein. With this technique a population of normal fibroblasts could be distinguished from a population of FH fibroblasts. The current studies demonstrate the feasibility of using fluorescent reconstituted LDL in conjunction with the cell sorter to isolate mutant cells lacking functional LDL receptors.     

Interaction of alcohols with proteins

The kinetics of denaturation of egg albumin have been determined for methanol, ethanol, propanol, and butanol. The reactions are first order in respect to protein but between 11th and 18th order for the alcohols. The denaturation reaction is characterized by a large temperature coefficient with little or no dependence on pH. There is a marked change of pH when proteins are denatured. A series of eight proteins has been studied. There is surprisingly little difference in susceptibility to alcohol denaturation between the various proteins. Methanol, ethanol, propanol, and butanol are strongly bound to egg albumin—butanol being the most strongly bound. The binding of alcohol is probably accompanied by protein dehydration. The polyhydric alcohols' behavior is much different. These alcohols do not denature proteins and the protein is hydrated. Sucrose produces the greatest degree of hydration.     

Antinociceptive effects of intrathecally administered human beta-endorphin in the rat and cat

Rats chronically implanted with intrathecal catheters displayed a dose-dependent increase in the hot-plate and tail-flick response latencies following the injection of human beta-endorphin into the lumbar spinal subarachnoid space through the indwelling catheter. beta-Endorphin was approximately 25 times more potent than morphine on a molar basis. Matching morphine and beta-endorphin doses such that approximately equal submaximal submaximal effects occurred, it was observed that the antinociception produced by beta-endorphin lasted approximately three times longer than that produced by morphine. Experiments with intrathecal injection of beta-endorphin into the spinal subarachnoid space of cats fitted with intrathecal catheters also revealed a potent antinociceptive effect which was completely antagonized by naloxone. In the rats, naloxone administered systemically in doses of 10--100 microgram/kg produced a parallel shift in the dose-response curves of both nociceptive measures suggesting a competitive antagonism. Using a dose ratio analysis, an in vivo pA2 of 7.1 for naloxone was obtained. These data and those derived from previous work based on the pA2 suggest that the interaction of morphine, certain pentapeptides, and beta-endorphin is the same with regard to the spinal opiate receptor population mediating behaviorally defined analgesia.     

Bacteriological activity in unfiltered calf sera collected for tissue culture use

Summary Bacteriological tests were made on 24 lots of unfiltered calf serum collected for subsequent use as a component of tissue culture media. The examination included the isolation and identification of bacteria, assay of phages, and demonstration of endotoxin material. Only Gram-positive bacteria were isolated and 96% of the sera were contaminated with bacteria. The prevalent strains of bacteria found wereBacillus species and streptococci and 63% of the sera coagulatedLimulus amebocyte lysate. More than 90% of the lots contained phages demonstrable with the C-3000 strain ofEscherichia coli. Only one lot of the serum was found to be free from bacteria, phages, and endotoxin by the tests used.     

Snow depth manipulation and its influence on soil frost and water dynamics in a northern hardwood forest

Climate change will likelyresult in warmer winter temperatures leading toless snowfall in temperate forests. Thesechanges may lead to increases in soil freezingbecause of lack of an insulating snow cover andchanges in soil water dynamics during theimportant snowmelt period. In this study, wemanipulated snow depth by removing snow for twowinters, simulating the late development of thesnowpack as may occur with global warming, toexplore the relationships between snow depth,soil freezing, soil moisture, and infiltration.We established four sites, each with two pairedplots, at the Hubbard Brook Experimental Forest(HBEF) in New Hampshire, U.S.A. and instrumentedall eight plots with soil and snow thermistors,frost tubes, soil moisture probes, and soillysimeters. For two winters, we removed snowfrom the designated treatment plots untilFebruary. Snow in the reference plots wasundisturbed. The treatment winters (1997/1998 and1998/1999) were relatively mild, withtemperatures above the seasonal norm and snowdepths below average. Results show the treatedplots accumulated significantly less snow andhad more extensive soil frost than referenceplots. Snow depth was a strong regulator ofsoil temperature and frost depth at all sites.Soil moisture measured by time domainreflectometry probes and leaching volumescollected in lysimeters were lower in thetreatment plots in March and April compared tothe rest of the year. The ratio of leachatevolumes collected in the treatment plots tothat in the reference plots decreased as thesnow ablation seasons progressed. Our data showthat even mild winters with low snowfall,simulated by snow removal, will result inincreased soil freezing in the forests at theHBEF. Our results suggest that a climate shifttoward less snowfall or a shorter duration ofsnow on the ground will produce increases insoil freezing in northern hardwood forests.Increases in soil freezing will haveimplications for changes in soil biogeochemicalprocesses.     

Logistic population growth under random dispersal

Various diffusion processes employed for modelling logistic growth are briefly summarized. A discrete-time, discrete-state space stochastic process for population growth is proposed and analyzed with either Bose-Einstein or Maxwell-Boltzmann statistics for the distribution of offspring in available sites in a restricted region. A diffusion approximation is constructed, which differs from those previously employed. The logistic law is a natural deterministic analog of the diffusion process.