Structural basis for antioxidant activity of trans-resveratrol: ab initio calculations and crystal and molecular structure

From the experimental crystal structure and ab initio calculations on resveratrol and its derivatives, structural features of mechanistic importance are described. The molecular structure reveals the relative coplanarity of the trans-stilbene skeleton, and the molecular packing in the solid state shows an extensive hydrogen bond network that elucidates the flip-flop motion of the three hydroxyl groups that alternately form and break H bonds with each of the neighboring phenolic oxygens. The dynamic behavior provoked by the alternation of hydrogen bond formation and breaking can result in the ready mobility of up to three hydrogen atoms per resveratrol molecule that can be transferred to reactive oxidants that are rich in electron density. In addition, theoretical studies confirm the planarity of resveratrol as well as for half of the molecule of a condensation dimeric derivative of resveratrol, trans-sigma-viniferin. Furthermore, these studies show the p-4'-OH group to be more acidic compared to the other two m-OH groups. These features correlate with the biological activity of resveratrol as an antioxidant and support earlier studies showing H-atom transfer to be the dominant mechanism by which phenolic antioxidants intercept free radicals.     

Prevalence of Mycobacterium bovis infection in feral pigs in the Northern Territory

SUMMARY The prevalence of Mycobacterium bovis infection in populations of feral pigs from five areas in the Northern Territory was examined. In total 790 pigs were necropsied and positive cultures of M bovis were obtained from two pigs (0.25%) and a mycobacterial granuloma was found in one pig. The observed prevalence of M bovis infection in feral pigs is significantly less (x²= 139.8, df = 1, P < 0.001) than the results of a comparable survey conducted during the early 1970s before the implementation of the Brucellosis and Tuberculosis Eradication Campaign. The prevalence of all types of macroscopic lesions resembling tuberculosis was significantly (x²= 338.7, df = 1, P < 0.001) less than the earlier survey. The results are further support for the hypothesis that in the Northern Territory feral pigs are an end-host for M bovis infection, and that the previous high prevalence of M bovis recorded in feral pigs in the 1970s was caused by the close association between these animals and large populations of M bovis-infected buffalo and cattle.     

Sequence and structure of a human glucose transporter

The amino acid sequence of the glucose transport protein from human HepG2 hepatoma cells was deduced from analysis of a complementary DNA clone. Structural analysis of the purified human erythrocyte glucose transporter by fast atom bombardment mapping and gas phase Edman degradation confirmed the identity of the clone and demonstrated that the HepG2 and erythrocyte transporters are highly homologous and may be identical. The protein lacks a cleavable amino-terminal signal sequence. Analysis of the primary structure suggests the presence of 12 membrane-spanning domains. Several of these may form amphipathic alpha helices and contain abundant hydroxyl and amide side chains that could participate in glucose binding or line a transmembrane pore through which the sugar moves. The amino terminus, carboxyl terminus, and a highly hydrophilic domain in the center of the protein are all predicted to lie on the cytoplasmic face. Messenger RNA species homologous to HepG2 glucose transporter messenger RNA were detected in K562 leukemic cells, HT29 colon adenocarcinoma cells, and human kidney tissue.     

Studies of selenium-containing volatiles in roasted coffee

Coffee has been an important and heavily used beverage in many cultures over a long period of time. Although sulfur species have been found to be abundant constituents, no work to date has explored the presence of selenium analogues. Investigation of volatile selenium species from green coffee beans, roasted beans, and brewed coffee drink was performed using solid phase microextraction (SPME) sample preconcentration in conjunction with GC/ICP-MS. Several volatile selenium species at trace levels were detected from roasted coffee beans as well as in the steam from brewed coffee drinks. No detectable selenium (and sulfur) species, however, were found in the headspace of green beans, indicating that selenium-containing volatiles are formed during roasting, as is the case for the sulfur volatiles. Matching standards were prepared and used to identify the compounds found in coffee. Artificial supplementation of the green coffee beans with selenium before roasting was performed to further characterize the selenium-containing volatiles formed during the coffee-roasting process.     

Nitrogen,Phosphorus and Potassium Fertilization Interactions on the Photosynthesis of Containerized Citrus Nursery Trees

The objective of this research was to evaluate the nitrogen, phosphorus and potassium (NPK) fertilizer effect on the development of ‘Valencia’ sweet orange nursery trees budded on Rangpur lime rootstocks in a greenhouse using containers. The experiment was a complete (1/5) 5³ factorial randomized blocks design. Treatments comprised five concentrations (g per plant) of N (1.25; 6.25; 11.25; 16.25; 21.25); K (0.42; 3.75; 6.22; 9.34; 12.45); and P (0.19; 0.89; 1.59; 2.29; 2.99). Carbon dioxide assimilation rate (A), transpiration rate (E), stomata conductance (g_s), and internal carbon dioxide (CO₂) concentration (Ci) and water use efficiency (WUE). Reducing sugar, sucrose and starch were evaluated. Response functions were adjusted and nutrient rates for maximum yield were presented. The results indicated that the high levels of N (>16.25 g per plant) interferes negatively on photosynthesis. Potassium at intermediate fertilization levels (from 3.75 to 6.22 g per plant) had positive effects on photosynthesis. But P had little interference on photosynthesis. Carbohydrates levels were not related to nutrients fertilized.     

Biomimesis of linolenic acid transport through model lipidic membranes by differential scanning calorimetry

Multienoic fatty acids, such as linolenic acid, show their ability to interact with and to penetrate into model biomembranes by biomimetic experiments performed to support the absorption route followed by n-3 fatty acid in cells. The thermotropic behavior of model biomembranes, that is, dimyristoylphosphatidylcholine multilamellar or unilamellar vesicles, interacting with linolenic acid was investigated by differential scanning calorimetry. When dispersed in liposomes during their preparation, the examined biomolecule was found to interact with the phospholipid bilayers by modifying the gel to liquid-crystal phase transition of lipid vesicles; this modification is a function of the fatty acid concentration. Calorimetric analysis was also performed on samples obtained by leaving the pure n-3 acid in contact with lipid aqueous dispersions (multilamellar or unilamellar vesicles) and then examining the thermotropic behavior of these systems for increasing incubation times at temperatures higher than the transitional lipid temperature. Linolenic acid (LNA) was able to migrate through the aqueous medium and successively to interact with the vesicle surface and to penetrate into the model membranes, following a flip-flop mechanism, with a faster and higher effect for unilamellar vesicles, caused by the larger lipid surface exposed, compared to the multilamellar ones, although due to the lipophilic nature of LNA, such a transfer is hindered by the aqueous medium. The relevance of the medium in LNA absorption has been well clarified by other biomimetic transfer experiments, which showed the LNA transfer from loaded multilamellar vesicles to empty vesicles. Taken together, the present findings support the hypothesis of a passive n-3 acid transport as the main route of absorption into cell membranes.     

The effect of different combinations of lignocaine,ketoprofen, xylazine and tolazoline on the acute cortisol response to dehorning in calves

AIMS: The aims of this study were (a) to evaluate the effect of xylazine and tolazoline, with and without lignocaine, on the cortisol response of calves following amputation dehorning and (b) to assess the effect of a non-steroidal anti-inflammatory drug (ketoprofen) and local anaesthesia on the cortisol response of calves to amputation dehorning.

METHODS: Plasma cortisol concentrations were measured in 100 dehorned or non-dehorned 3-month-old calves over an 8-h period following five different sedative/analgesic or control treatments. Sedative/analgesic treatments were: control (no anaesthesia); local anaesthesia and ketoprofen; local anaesthesia and xylazine; local anaesthesia, xylazine and tolazoline; and xylazine only. Within each sedative/analgesic treatment group, half the calves (n=10 per group) were amputation dehorned and half were not dehorned.

RESULTS: The change in plasma cortisol concentrations in calves dehorned after being given ketoprofen and local anaesthesia did not differ significantly from that of non-dehorned control calves for at least 8 h. In contrast, the cortisol response of dehorned calves not given analgesic drugs peaked 30 min after dehorning and lasted >4 h. Xylazine injected before dehorning significantly reduced but did not eliminate the peak of the cortisol response. When both xylazine and local anaesthesia were administered before dehorning the peak in the cortisol response was virtually eliminated. In the dehorned calves that received xylazine with or without local anaesthesia, cortisol concentration increased significantly 3 h after dehorning and did not return to baseline until at least 5 h later. When tolazoline was administered shortly after xylazine, it caused a marked cortisol response, higher than the response to any other treatment.

CONCLUSIONS: Combining ketoprofen and local anaesthesia minimised the cortisol response, and by inference the pain- induced distress, following amputation dehorning in calves. Xylazine reduced the initial cortisol response to dehorning but not as much as when local anaesthesia was also given. The increase in cortisol concentration from 3–8 h after dehorning in calves given xylazine alone or in combination with local anaesthesia suggests that calves experienced pain-induced distress during this time and that xylazine had no long-term analgesic effect. Tolazoline, used to reverse the sedative effects of xylazine, caused a marked cortisol response in calves via a mechanism which remains unclear.     

The physiological and physical status of single calves at birth in a dairy herd in New Zealand

AIM: To determine the physiological status of calves at birth and the perinatal factors that might predispose newborn calves to debility and death, using criteria previously established for newborn lambs.

METHODS: Friesian mixed-aged cows and heifers on a dairy farm in New Zealand that were close to calving were separated from the main herd and observed 24 h a day until they calved. Cows in which labour did not progress for over 1 h or which were in distress were assisted. About 12–13 min after birth, rectal temperature was measured and a blood sample was taken from each calf. The packed cell volume (PCV) and plasma lactate, glucose and fructose concentrations were determined. The time to stand for each calf and the air temperature and weather conditions at birth were recorded.

RESULTS: The parameters measured were within normal ranges for newborns for the majority of calves. Calves sired by an Angus bull and born to heifers (AngusX) had significantly higher plasma lactate and fructose concentrations than Friesian calves born to cows, but there were no significant differences between the two breeds in any of the other parameters measured. Calves of both breeds born with assistance had significantly higher plasma lactate concentrations than those born without. Friesian calves that were assisted at birth had significantly lower PCvs and took significantly longer to stand than calves born without assistance. Assisted AngusX calves were significantly heavier than their unassisted counterparts. Calves born during windy and wet weather and when air temperatures were below 10°C had lower rectal temperatures, took longer to stand and had higher plasma glucose concentrations than those born in dry weather and when air temperatures were above 10°C.

CONCLUSIONS: Calves with physiological parameters outside the normal range had experienced difficult labour and/or intrapartum hypoxaemia. Placental insufficiency and maternal undernutrition during late pregnancy did not apparently contribute to neonatal problems in the present study.