Biodegradability of injection molded bioplastic pots containing polylactic acid and poultry feather fiber.

The biodegradability of three types of bioplastic pots was evaluated by measuring carbon dioxide produced from lab-scale compost reactors containing mixtures of pot fragments and compost inoculum held at 58 °C for 60 days. Biodegradability of pot type A (composed of 100% polylactic acid (PLA)) was very low (13 ± 3%) compared to literature values for other PLA materials. Near infrared spectroscopy (NIRS) results suggest that the PLA undergoes chemical structural changes during polymer extrusion and injection molding. These changes may be the basis of the low biodegradability value. Biodegradability of pot types B (containing 5% poultry feather, 80% PLA, 15% starch), and C (containing 50% poultry feather, 25% urea, 25% glycerol), were 53 ± 2% and 39 ± 3%, respectively. More than 85% of the total biodegradation of these bioplastics occurred within 38 days. NIRS results revealed that poultry feather was not degraded during composting.

Comparison of efficacy of three extractants to solubilize glomalin on hyphae and in soil.

Glomalin, a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, is a major component of the humus fraction of soil organic matter. Glomalin is extracted from soil and hyphae of AM fungi by using sodium citrate at 121 degrees C in multiple 1-h cycles, but extensive extraction does not solubilize all glomalin in all soils. Efficacies of 100 mM sodium salts of citrate, borate or pyrophosphate (pH 9.0, 121 degrees C) were tested for two 1-h cycles for hyphae from four AM fungal isolates and four 1-h cycles for seven soils from four US geographic regions. Residual soil glomalin was examined by pyrophosphate extraction of soils previously extracted with citrate or borate followed by extraction of all soils after treatment with NaOH. Hyphal extracts were compared using Bradford-reactive total protein (BRTP) values, and extracts from soils were compared using BRTP, percentage C and C weight. No difference among extractants was detected for AM fungal isolates or across soils. The residual glomalin across soils for extractants contained the following percentages of the total BRTP: pyrophosphate, 14%; borate, 17%; and citrate, 22%. Comparisons among individual soils indicated that pyrophosphate extracted significantly more BRTP (10-53%) than borate or citrate in six soils and borate was equal to pyrophosphate in one soil. Extraction with borate should be compared with pyrophosphate before initiating an experiment. For routine extractions of ca. 85% of the glomalin across a variety of soils, sodium pyrophosphate appears to be equal to or better than borate and better than citrate.

Thermodynamic, spectroscopic, and computational evidence for the irreversible conversion of beta- to alpha-endosulfan.

Previous studies have provided unequivocal evidence for the symmetry of beta-endosulfan and the corresponding asymmetry of alpha-endosulfan; the conversion of beta-endosulfan to alpha-endosulfan was identified. In this study, evidence from differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) experiments combined with computational chemistry calculations was used to propose a molecular mechanism for the corresponding conformational changes that occur in this process. DSC and NMR data of mixtures indicated that both isomers can influence the conformer populations in the solid, solution, and vapor phase. Computational chemistry demonstrated that the relative S==O configuration between alpha- and beta-isomers can be the intermediate state through which the conformations of alpha- and beta-isomers affect each other. Furthermore, calculations for mixtures indicated that the asymmetrical conformation of the sulfite in alpha-endosulfan can induce asymmetry in beta-endosulfan, and conversion to alpha-endosulfan occurs from this transition state.

Novel fatty acid esters of p-coumaryl alcohol in epicuticular wax of apple fruit.

Hexane extracts of epicuticular wax from cv. Gala apples were noted to have an unusual, broad absorbance maximum at approximately 258 nm, which led us to isolate and identify the primary UV-absorbing compounds. Column and thin-layer chromatography yielded a fraction that gave a series of paired, 260-nm-absorbing peaks on C(18) HPLC. These were shown to be a family of phenolic fatty acid esters, for which retention times increased with increasing fatty acid chain length, and paired peaks were esters of two related phenolics with the same fatty acid moiety. Alkaline hydrolysis of the esters released two water-soluble phenolics separable by C(18) HPLC. Electrospray ionization mass spectrometry gave a molecular mass of 150 for both, and (1)H NMR plus UV absorbance spectra identified them as E and Z isomers of p-coumaryl alcohol. Alkaline cleavage of the fatty acid esters in the presence of methanol or ethanol resulted in partial derivatization of E-p-coumaryl alcohol to the corresponding gamma-O-methyl or O-ethyl ether. Gradient HMQC NMR of the HPLC-purified stearate ester of E-p-coumaryl alcohol indicated that fatty acid esterification occurs at the gamma-OH rather than at the 4-OH on the phenyl ring. This is the first report of fatty acid esters of monolignols as a natural plant product.

Nematode-antagonistic trichothecenes from Fusarium equiseti.

A strain of the fungus Fusarium equiseti isolated from soybean cyst nematode secretes nematode-antagonistic compounds. Bioassay-guided fractionation of an extract of the culture broth was undertaken to identify the compounds. Fractions were assayed for activity against a root-knot nematode (Meloidogyne incognita), a plant pathogen that attacks the roots of numerous plant species. Two trichothecene compounds were isolated that inhibited egg hatch and immobilized second-stage juveniles of this nematode: 4,15-diacetoxy-12,13-epoxy-3,7-dihydroxytrichothec-9-en-8-one (4,15-diacetylnivalenol) and 4,15-diacetoxy-12,13-epoxy-trichothec-9-en-3-ol (diacetoxyscirpenol). This is the first published report of these compounds affecting plant-parasitic nematodes.

Stereochemical effects in an insect repellent.

Racemic 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine repels blood-feeding arthropods such as mosquitoes, chiggers, and ticks. The compound contains two asymmetric carbon atoms and the racemate consists of four stereoisomers. Quantitative mosquito bioassays using Aedes aegypti (L.) showed that (1S,2'S) and (1R,2'S) configurations were 2.8-3.1 and 1.6-1.8 times more effective, respectively, than the other two stereoisomers in reducing mosquito bites. (1S,2'S) was 2.5 more repellent than the racemate. Biological data show that an interaction of the (2'S)-2-methylpiperidine configuration with a repellent receptor system in A. aegypti is apparently important to repellent activity. Nuclear magnetic resonance spectra and molecular mechanics calculations for the stereoisomers provided insight into the conformation of the (2'S)-group. Results indicate that enhanced repellent effects can be realized through formulation of the most active stereoisomers of the compound.

Influence of the chemical environment on metolachlor conformations.

Metolachlor exists in multiple, different stable conformations in solution. Assignment of the NMR frequencies to chemical structure is a prerequisite to understanding the behavior of individual conformations. (1)H NMR experiments of metolachlor in different chemical environments identified the labile sites of metolachlor and environments that influence conformational/configurational changes. Within very specific chemical environments, metolachlor atropisomers aS,12S (aR,12R) and aR,12S (aS,12R) freely interchange, and consequently, the multiple conformations also interchange. The changes in chemical environments, which most alter the conformations and molecular dynamics of metolachlor, identify the most critical components affecting its environmental fate. These results enable a structural interpretation of conformational changes that can influence the environmental fate of metolachlor.

Evidence for the unique function of docosahexaenoic acid during the evolution of the modern hominid brain.

The African savanna ecosystem of the large mammals and primates was associated with a dramatic decline in relative brain capacity associated with little docosahexaenoic acid (DHA), which is required for brain structures and growth. The biochemistry implies that the expansion of the human brain required a plentiful source of preformed DHA. The richest source of DHA is the marine food chain, while the savanna environment offers very little of it. Consequently Homo sapiens could not have evolved on the savannas. Recent fossil evidence indicates that the lacustrine and marine food chain was being extensively exploited at the time cerebral expansion took place and suggests the alternative that the transition from the archaic to modern humans took place at the land/water interface. Contemporary data on tropical lakeshore dwellers reaffirm the above view with nutritional support for the vascular system, the development of which would have been a prerequisite for cerebral expansion. Both arachidonic acid and DHA would have been freely available from such habitats providing the double stimulus of preformed acyl components for the developing blood vessels and brain. The n-3 docosapentaenoic acid precursor (n-3 DPA) was the major n-3-metabolite in the savanna mammals. Despite this abundance, neither it nor the corresponding n-6 DPA was used for the photoreceptor nor the synapse. A substantial difference between DHA and other fatty acids is required to explain this high specificity. Studies on fluidity and other mechanical features of cell membranes did not reveal a difference of such magnitude between even alpha-linolenic acid and DHA sufficient to explain the exclusive use of DHA. We suggest that the evolution of the large human brain depended on a rich source of DHA from the land/water interface. We review a number of proposals for the possible influence of DHA on physical properties of the brain that are essential for its function.

[Endovascular brachytherapy for the prevention of recurrence after PTA]. / Endovasculäre Brachytherapie zur Rezidivprophylaxe nach PTA.

PURPOSE: Recurrent stenosis after PTA is caused by intimal hyperplasia and constrictive arterial remodeling. In experimental and first clinical studies, ionizing radiation has demonstrated its potential to control excessive intimal proliferation. We wanted to evaluate the safety, feasibility and efficacy of endoluminal irradiation after PTA and/or stent implantation. MATERIAL AND METHODS: From September 1996, 24 patients (24 lesions) who had a stenosis or occlusion measuring more than 5 cm in length in the superficial femoral artery or a restenosis after PTA underwent endoluminal irradiation. An isodose of 14 Gy was applied to the vessel wall using an Ir-192-HDR afterloading unit. The radiation was tolerated well; the additional time needed for the procedure was 30-45 min. RESULTS: In a mean follow-up time of 15 months we found a cumulative patency rate of 60%. No side effects were observed. CONCLUSION: Endovascular brachytherapy is a safe and brief procedure. In our selection of patients, a patency rate of approx. 40% after 1 year has to be expected. Thus, these first results are promising, although first published studies of endoluminal irradiation in peripheral vessels with stent implantation showed higher patency rates. No randomized data are currently available. We conclude that endovascular irradiation should be performed together with stent implantation in long lesions or recurrent stenosis after PTA, in order to control not only excessive intimal proliferation but also constrictive arterial remodeling.

Effects of task complexity in young and old adults: reaction time and P300 latency are not always dissociated.

Twelve young and 11 elderly men (mean ages 21.1 and 70.1) performed a choice-reaction time (RT) task in which stimulus degradation and stimulus-response (S-R) compatibility were manipulated. The extant literature has suggested that the effects of age on RT are usually augmented (multiplicative) in more difficult task conditions, but also that the effects of age on the latency of the P300 component of the event-related brain potential (ERP) are constant (additive). The results indicated that the effects of age on RT were enhanced in more difficult conditions, whether the difficulty consisted of stimulus degradation or S-R incompatibility. However, the effects of age on P300 latency were enlarged as the stimuli were degraded, but not if the S-R mapping was incompatible. Thus, it appears that task content determines if effects of age on P300 latency are additive or multiplicative. A simple model is proposed that produces the obtained pattern of effects.

Functional correlates of callosal atrophy in relapsing-remitting multiple sclerosis patients. A preliminary MRI study.

In multiple sclerosis (MS), periventricular lesions produce atrophy of the corpus callosum (CC), as evidenced by magnetic resonance imaging (MRI). We investigated whether CC atrophy in relapsing-remitting MS patients is related to functional deficits. We compared 14 mildly disabled (mean Expanded Disability Status Scale score 2.7) relapsing-remitting MS patients with 14 age- und sex-matched controls. CC size was determined using sagittal T1-weighted MRI. The function of the CC was studied using a neuropsychological battery and neurophysiological evaluation based on visual stimulation using a divided visual field paradigm. The total area of the CC in patients (mean 5.3 cm2) was significantly (P = 0.002) smaller than in controls (mean 6.6 cm2). Patients showed left ear extinction using the dichotic listening test and impaired name learning, which was correlated with atrophy of the splenium. There were no differences in interhemispheric transfer time between patients and controls. Marked atrophy of the CC can be encountered in relapsing-remitting MS patients. The associated cerebral disconnection correlated with atrophy of expected regions of the CC, thus supporting topographical organization.

Structure-activity relationship observations oftrans-trimedlure enantiomers.

tert-Butyl 4- (and 5-) chloro-trans-2-methylcyclohexane-1-carboxylate (TML), a mixture of four majortrans and four minorcis isomers, is used as an attractant for detecting and monitoring the male Mediterranean fruit fly (medfly),Ceratitis capitata (Wiedemann). The eight isomers (racemic mixtures) were isolated by HPLC, and their relative attractiveness in the field was determined. A quantitative structure-activity relationship (QSAR) was proposed that related a molecular measurement (Å(3)) of the TML structure to male medfly captures. More recently, thetrans-TML enantiomers were synthesized in sufficient quantities for field testing. This paper reports the computer-aided molecular modeling, via Chem-X, of thetrans-TML enantiomers and the staggered and superimposed fitting with the most attractive isomer, (1S,2S,4R)-TML-C, to determine common volumes and surface areas from Van der Waals (VdW) maps. Observations of structure-activity relationships (SAR) are reported for the staggered fittings.

Association of beta-agonists with corresponding beta 2- and beta 1-adrenergic pentapeptide sequences.

Synthesized beta 1- and beta 2-pentapeptide sequences corresponding to published adrenoceptor transmembrane activation site subtypes were investigated in vitro for selectivity in association for drug ligands of known selectivity. Both nuclear magnetic resonance spectroscopy and molecular mechanics demonstrated that structural differences among the corresponding pentapeptide activation-site sequences can explain agonist selectivity. Results suggest the agonists bind across the activation site loop on the second transmembrane alpha-helix by dipole/dipole interactions between a ligand and the peptide. Since electrostatic interactions within the membrane may determine the rate of intercellular ion flux, agonist association across the activation site sequence could thereby decrease electrostatic resistance to positive ion flux into the cell. Interactions between the peptides and the ligands may provide insight into the structures and mechanisms involved in association of ligands for the identical sequences on the beta-adrenoreceptors.

13C CP/MAS of LDLL mixtures of amino acids.

A unit cell in which three isomers are in an L configuration and one is in a D configuration is inherently asymmetrical. For LDLL mixtures of amino acids with identical chemical structures (apart from chirality), the inter- and intramolecular interactions observed from the 13C CP/MAS NMR spectra are even larger than those which have been observed with mixtures of diastereoisomers in the solid state. This occurs even though the chemical composition of these molecular clusters consists only of nearest neighbor enantiomers. Because D and L isomers have identical chemical shifts, changes in chemical shift and peak intensities of these asymmetrical solid mixtures cannot be unambiguously assigned to either the D or one of the L isomers. In LLDL mixtures of amino acids in which half is L isomers and the other half is DL isomers, the NMR spectra clearly depend upon which amino acid contains the D isomer. Any further structural interpretation of these molecular clusters is equivocal without assigning chemical shifts to the D isomer (or alternatively designated the R, [-] or [+] isomer). Both more rigorous mathematical analysis and new NMR experiments are required which link interactions at chiral centers with NMR spectra of LLDL mixtures in the solid state.

Quantitative structure-activity relationships (QSAR) of trimedlure isomers.

Trimedlure (tert-butyl 4- and 5-chloro-cis- andtrans-2-methylcyclohexane-1-carboxylate), a mixture of eight isomers, is used as an attractant for detecting and monitoring the male Mediterranean fruit fly. This paper reports the quantitative structure-activity relationship (QSAR), via CHEMX, of the eight purified isomers (racemic mixtures) of trimedlure. The relationship between structure and attractiveness is demonstrated by utilizing male medfly field catch on day 0 of the individual isomers vs. several molecular descriptors: volume, surface area, a torsion angle, and an interatomic distance.

[The prevention of mucosal lesions during oropharyngeal irradiation with a dental-filling shield]. / Prävention lokaler Schleimhautläsionen während Oropharynx-Bestrahlung durch einen Plombenschutz.

In patients with metallic dental fillings radiation therapy to the oral cavity can cause mucous membrane lesions, which are more severe than expected. They appear as circumscribed erosions, opposite to metallic fillings and are caused by an increase in radiation dose through secondary radiation due to the higher density and atomic number of the filling material. This dose increase can be directly measured with 0.1 mm thin sheets of graphite-loaded TLD's (LiF, Vinten). For Co-60 gamma rays a commercial amalgam filling caused a dose increase by a factor of 1.7. The half value layer for this additional radiation was measured to be approximately 0.4 mm tissue. In order to avoid painful mucous membrane ulcerations which are even more a problem if hyperfractionated treatment schedules are used, we constructed individual dental shields for each patient. As shielding material we used a dental impression material (Optosil P+1 Bayer). This method was tested in 35 patients, in all of them circumscribed mucous membrane ulcerations could be avoided. The method proved to be fast and simple and was very well tolerated by all patients.

Assessment of body composition of poultry by nuclear magnetic resonance imaging and spectroscopy.

Nuclear magnetic resonance (NMR) imaging and spectroscopy were used to assess body composition of the chicken and turkey poult. The NMR imaging was performed using a clinical, whole-body imaging system operating at 1.5 tesla (T; 63 MHz). Three-dimensional reconstruction of cross-sectional images made along the transaxial plane was used to estimate mass of the Pectoralis muscle of chickens ranging in weight from 140 to 2,760 g. Results indicate that NMR imaging can be used to determine size of the Pectoralis muscle (R2 = .99) in the bird, thus permitting repetitive measurements during the growth and development of the bird. The NMR spectroscopy was performed using an imaging spectrometer operating at 4.7 T (200 MHz). Integral areas of the water and lipid proton peaks of the spectra were compared with the water and lipid content of the whole body as determined by chemical analysis. Regression analysis of measurements made on turkey poults, ranging in weight from 115 to 630 g (n = 6), resulted in R2 values of .94 for NMR water proton peak area and total body water, .93 for NMR lipid proton peak area and total body lipid, and .96 for NMR water proton peak area and total body protein. From NMR spectroscopy of chickens weighing 528 +/- 18 g (n = 6), the relative area of the lipid peak correlated with whole-body lipid (R2 = .97). Thus, whole-body spectroscopy of smaller birds can be used to measure total body water, protein, and lipid content.