Tracing (r)bST in cattle: Liquid-based options for extraction and separation

Growth hormone (GH) or somatotropin (ST) is a species-specific polypeptide hormone produced in the pituitary gland of vertebrates. When administered exogenously to dairy cattle, it has galactopoietic effects and is capable of increasing the milk yield. The beginning of the commercial production of recombinant variants of bovine somatotropin (rbST), by the end of the 20th century, had a major economic impact in the dairy industry. Recombinant bST enabled large-scale applications in farms, enhancing significantly milk production. While it is banned in the European Union (EU), several countries permit the trade and use of recombinant somatotropins in animal husbandry. Also, rbST-free dairy products can be frequently found in the market of those countries, even though these labels are not actually verified in a laboratory. In this context, effective analytical methods are needed for residue control to avoid an illegal use of rbST but also to prevent fraudulent labeling in some cases. The present review includes studies published in the last 5 years (from 2012 to 2017) to monitor rbST in bovine animals, using liquid-based applications. It is then intended to serve as a practical guide to help those laboratories interested in developing analytical methods to detect rbST use and abuse.     

DOSE-RESPONSE OF CHRONIC ULTRAVIOLET EXPOSURE ON EPIDERMAL FORWARD SCATTERING-ABSORPTION IN SK-1 HAIRLESS MOUSE SKIN

This work provides a dose-response model of UV-induced epidermal-stratum corneum thickening induced by irradiation at wavelength lambda. This model assumes that photobiochemical reaction(s) can give rise to hyperplasia in a manner which is predictable from a simple photochemical kinetic scheme. In this work, we derive an equation which predicts an approximately linear relationship between the logarithm of the increase in optical skin thickening measured at 320 nm (delta OD320) and total cumulative dose (DT) seen by the target cells in or near the basal layer. For each excitation wavelength lambda, the slope R(lambda) of the log delta OD320 vs DT plot is proportional to epsilon(lambda) phi rx, where epsilon(lambda) is the extinction coefficient for the target chromophore at excitation wavelength, and phi rx is the quantum yield for the photochemical reaction(s) leading to hyperplasia. Our data previously obtained from irradiation of SK-1 hairless mice with "monochromatic" UV wavebands at 280, 290, 300, 307 and 313 nm (Menter et al., 1988, Photochem. Photobiol. 47, 225-260.) and data from Sterenborg and van der Leun at 254 and 313 nm (1988, Photodermatology 5, 71-82) are in good agreement with this model, except for 254 and 280 nm excitation, which are greatly attenuated by epidermis-stratum corneum. For excitation at the latter wavelengths, "dark" regressive processes successfully compete with the "light" reaction(s) which lead to (pre)cancerous lesion. This difficulty notwithstanding, the "intrinsic" action spectrum for hyperplasia derived from these measurements indicates that the target chromophore preferentially absorbs in the UV-C region.(ABSTRACT TRUNCATED AT 250 WORDS)     

Computational studies of the 3-Dimensional structure of cyclopenta polycyclic aromatic hydrocarbons containing a gulf region

Recently, some cyclopenta-fused polyaromatic hydrocarbons, an environmentally relevant subclass of chemicals, have been shown to have carcinogenic activity in animals. It has been suggested that benz[l] aceanthrylene ( I ), an active member of this subclass with a gulf region, has a trans dihydrodiol metabolite that is nonplanar and has two distinct spatial configurations. We have used MMP 2(85) and AM 1 to investigate the three-dimensional structure of this dihydrodiol and other similar derivatives of ( I ) and have found that although ( I ) is somewhat nonplanar the relevant derivatives are all nearly planar. Further, we have computed potential functions for the bending of the angular ring in the gulf region using MMP 2(85), AM 1, and ab initio computed energies for AM 1 spatial configurations and find that these molecules all have only a single potential minimum. We have performed the same calculations for benzo[c]phenanthren and its 1,12 dimethyl derivative, molecules with a similar gulf region for which crystallographic data exists. In agreement with that data, we find that two distinct spatial configurations exist separated by significant barries. The differences between the results generated by the three different methods of computation will be discussed.     

A search for properties which produce discrimination between cannabinoid psychoactivity and analgesic activity

One long-range goal of our work has been the design of cannabinoid analgesics with reduced psychopharmacological liability. We review here the progress we have made toward this goal. When we began our work on the cannabinoids, no cannabinoid analgesic had been reported that did not also possess significant psychoactivity. We approached the cannabinoid problem by calculating molecular reactivity characteristics (MRCS ) of template molecules for each activity: (?)-trans-delta-9-tetrahydrocannabinol (Δ⁹-THC) for psychoactivity, and (?)-9-nor-9-betahydroxyhexahydrocannabinol (9-nor-9β-OH? HHC) for analgesic activity. We then compared the MRC s of each template with the MRCS of a carefully chosen set of other cannabinoids (both active and inactive). Our focus in the calculation of MRCS was on accessible conformations of each subject molecule and on the molecular electrostatic potential generated in key planes by each accessible conformer. Our working hypothesis concerning the molecular basis of psychopharmacological activity in the cannabinoids was that activity is conferred by the set of molecular properties generated (1) by the orientation of the lone pairs of electrons of the phenyl group hydroxyl oxygen and (2) by the orientation of the carbocyclic ring and its C–9 substituent relative to this oxygen. Our working hypothesis concerning the molecular basis of cannabinoid analgesic activity was that activity is conferred by the set of molecular properties generated by the presence and relative location of two negative potential regions in the top half of the cannabinoid analgesic molecule. Our work thus far has revealed important steric and electronic features of the cannabinoids that may be used to enhance discrimination. We have shown that a simple structural feature, a C–9 substituent protruding into the α face of the molecule, can abolish or significantly diminish psychoactivity. We have also demonstrated that a free phenol group is not an absolute requirement for activity. Instead, we have found that compounds that do not possess free phenolic hydrogens, but that do maintain the orientation of the lone pairs of electrons of the “phenolic” oxygen toward the carbocyclic ring, exhibit selectivity toward analgesia.     

Purification and partial characterization of two lectin isoforms fromCratylia mollis mart. (camaratu bean)

Two additional electrophoretically distinct molecular forms, isoforms (iso) 2 and 3, with lectin properties were isolated fromCratylia mollis Mart, seeds (FABACEAE), by extraction with 0.15M NaCl and ammonium sulfate fractionation, followed by chromatography on Sephadex G-75 and Bio-Gel P-200 (iso 2), as well as CM-Cellulose and Sephadex G-75 (iso 3). Both isoforms were human group nonspecific and showed distinct specificity. Polyacrylamide gel electrophoresis resolved iso 2 and 3 in polypeptides of apparent mol wts 60 and 31 kDa, respectively; a distinct isoelectric focusing pattern was obtained for iso 2 and 3, under denaturing and reducing conditions.     

Evidence of upward spread of suppression in DPOAE measurements

Measurements of DPOAE level in the presence of a suppressor were used to describe a pattern that is qualitatively similar to population studies in the auditory nerve and to behavioral studies of upward spread of masking. DPOAEs were measured in the presence of a suppressor (f3) fixed at either 2.1 or 4.2 kHz, and set to each of seven levels (L3) from 20 to 80 dB SPL. In the presence of a fixed f3 and L3 combination, f2 was varied from about 1 oct below to at least 1/2 oct above f3, while L2 was set to each of 6 values (20-70 dB SPL). L1 was set according to the equation L1 = 0.4L2 + 39 [Janssen et al., J. Acoust. Soc. Am. 103, 3418-3430 (1998)]. At each L2, L1 combination, DPOAE level was measured in a control condition in which no suppressor was presented. Data were converted into decrements (the amount of suppression, in dB) by subtracting the DPOAE level in the presence of each suppressor from the DPOAE level in the corresponding control condition. Plots of DPOAE decrements as a function of f2 showed maximum suppression when f2 approximately = f3. As L3 increased, the suppressive effect spread more towards higher f2 frequencies, with less spread towards lower frequencies relative to f3. DPOAE decrement versus L3 functions had steeper slopes when f2 > f3, compared to the slopes when f2 < f3. These data are consistent with other findings that have shown that response growth for a characteristic place (CP) or frequency (CF) depends on the relation between CP or CF and driver frequency, with steeper slopes when driver frequency is less than CF and shallower slopes when driver frequency is greater than CF. For a fixed amount of suppression (3 dB), L3 and L2 varied nearly linearly for conditions in which f3 approximately = f2, but grew more rapidly for conditions in which f3 < f2, reflecting the basal spread of excitation to the suppressor. The present data are similar in form to the results observed in population studies from the auditory nerve of lower animals and in behavioral masking studies in humans.     

Effects of trivalent phosphorus compounds on vinyl polymerization. III. Anionic polymerization of acrylonitrile with triethyl phosphite

The polymerization of acrylonitrile catalyzed by triethyl phosphite was studied. It was found that the order with respect to the monomer concentration varies from two to three, depending on the polymerization temperature. From the results obtained for the molecular weight of the polymer and the phosphorus content in the polymer, it was thought that the zwitterion formed by the addition of triethyl phosphite to acrylonitrile is responsible for the initiation of polymerization. The following equation was suggested for the rate of the polymerization: