bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Determination of Spinal Cord Content in Ground Beef by Near‐Infrared Spectroscopy
Authors: Gangidi Rahul Reddy , Proctor Andrew , Pohlman Fred William , Meullenet Jean‐Francois
Published: August 2010

The potential of near‐infrared spectroscopy to measure spinal cord content in ground beef was investigated. Near‐infrared spectra were obtained for ground beef adulterated with 0 to 100 ppm spinal cord. A partial least square model was developed with 2nd derivative near‐infrared spectral data (5400/cm to 10000/cm). The model showed a calibration of Rval= 0.94 and a validation of Rval= 0.90. The detection limit of the model was 21 ppm, and sensitivity to detect true positive spinal cord–adulterated samples was 87%. Near‐infrared spectroscopy has the potential to identify spinal cord–adulterated ground beef.
Purification of Amylase from Honey
Authors: Babacan Sibel , Rand Arthur G.
Published: August 2010

The major amylase in honey was concentrated by ultrafiltration, isolated by ultracentrifugation and gel filtration, and purified by ion‐exchange chromatography. The amylase activity was in the flow‐through fraction of the anion‐exchange column, suggesting a high isoelectric point (>7.4) for the enzyme. The enzyme fraction from the anion‐exchange chromatography was loaded onto a cation‐exchange column, and the amylase activity was eluted as a single band at 50 mM NaCl. The purification factor after this step was 531‐fold. The purified enzyme was an a‐amylase, as determined by thin‐layer chromatography, with a molecular weight of 57000 Da according to sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). The results supported the concept that amylase in honey had a high degree of similarity with bee amylase.
Electronic Nose Technology in Quality Assessment: Predicting Volatile Composition of Danish Blue Cheese During Ripening
Authors: Trihaas Jeorgos , van den Tempel Tatjana , Nielsen Per Vággemose
Published: August 2010

This work describes for the 1st time the use of an electronic nose (e‐nose) for the determination of changes of blue cheeses flavor during maturation. Headspace analysis of Danish blue cheeses was made for 2 dairy units of the same producer. An e‐nose registered changes in cheeses flavor 5, 8, 12, and 20 wk after brining. Volatiles were collected from the headspace and analyzed by gas chromatography‐mass spectrometry (GC‐MS). Features from the chemical sensors of the e‐nose were used to model the volatile changes by multivariate methods. Differences registered during ripening of the cheeses as well as between producing units are described and discussed for both methods. Cheeses from different units showed significant differences in their e‐nose flavor profiles at early ripening stages but with ripening became more and more alike. Prediction of the concentration of 25 identified aroma compounds by e‐nose features was possible by partial least square regression (PLS‐R). It was not possible to create a reliable predictive model for both units because cheeses from 1 unit were contaminated by Geotrichum candidum, leading to unstable ripening patterns. Correction of the e‐nose features by multiple scatter correction (MSC) and mean normalization (MN) of the integrated GC areas made correlation of the volatile concentration to the e‐nose signal features possible. Prediction models were created, evaluated, and used to reconstruct the headspace of unknown cheese samples by e‐nose measurements. Classification of predicted volatile compositions of unknown samples by their ripening stage was successful at a 78% and 54% overall correct classification for dairy units 1 and 2, respectively. Compared with GC‐MS, the application of the rapid and less demanding e‐nose seems an attractive alternative for this type of investigation.
Growth or Survival of Listeria monocytogenes in Ready‐to‐Eat Meat Products and Combination Deli Salads During Refrigerated Storage
Authors: Burnett Scott L. , Mertz Erin L. , Bennie Barbara , Ford Thomas , Starobin Anna
Published: August 2010

ABBSTRACT

Growth or survival of Listeria monocytogenes in cold‐smoked salmon; sliced, cooked ham; sliced, roasted turkey; shrimp salad; and coleslaw obtained at retail supermarkets stored at 5 °C, 7 °C, or 10 °C (41 °F, 45 °F, or 50 °F, respectively) for up to 14 d was evaluated. Cold‐smoked salmon, ham, and turkey were obtained in case‐ready, vacuum packages. All food products were stored aerobically to reflect additional handling within the retail supermarket. Cold‐smoked salmon, ham, and turkey supported the growth of L. monocytogenes at all 3 storage temperatures. Fitted growth curves of initial populations (about 3 log10 colony‐forming units [CFU]/g) in cold‐smoked salmon, ham, and turkey stored at 5 °C achieved maximal growth rates of 0.29, 0.45, and 0.42 log10 CFU/g growth per day, respectively. Storage at 10 °C increased the estimated maximal growth rate of the pathogen by 0.56 to 1.08 log10 CFU/ g growth per day compared with storage at 5 °C. A decline in populations of L. monocytogenes was observed in shrimp salad and coleslaw, and the rate of decline was influenced by storage temperature. Retention of viability was higher in shrimp salad than in coleslaw, where populations fell 1.2, 1.8, and 2.5 log10 CFU/g at 5 °C, 7 °C, and 10 °C, respectively, after 14 d of storage. Inability of shrimp salad and coleslaw to support the growth of L. monocytogenes may be attributed to the acidic pH (4.8 and 4.5, respectively) of the formulations used in this study. Results show that the behavior of L. monocytogenes in potentially hazardous ready‐to‐eat foods is dependent upon the composition of individual food products as well as storage temperature.
Allyl Alcohol Is the Sole Antiyeast Compound in Heated Garlic Extract
Authors: Choi Jong Hoon , Kyung Kyu Hang
Published: August 2010

The principal antiyeast compound of heated garlic was isolated and identified by high‐performance liquid chromatography (HPLC) and gas chromatography‐mass spectrometry (GC‐MS) as allyl alcohol (2‐pro‐pene‐1‐ol). The generation of allyl alcohol was observed in heated garlic as well as in heated pure alliin solution. The pattern of growth inhibition of Candida utilis ATCC42416 by allyl alcohol was essentially the same as that seen with heated garlic and heated alliin solution. The minimum inhibitory concentrations of heated garlic, with an alliin content of 1.5% (w/v), and allyl alcohol were 0.6% (v/v) and 0.002% (v/v), respectively, against C. utilis ATCC42416. Yeasts were extremely sensitive to allyl alcohol, with minimum inhibitory concentration (MIC) ranging from 0.002% (v/v) to 0.014% (v/v), while bacteria were not very sensitive to allyl alcohol, with MIC ranging from 4% to 7%. Among yeasts, xerotolerant strains, including Zygosaccharomyces rouxii, were significantly less sensitive to allyl alcohol and heated garlic extract than others. Allyl alcohol is different from all other known antimicrobial compounds found in garlic in that it does not contain sulfur in its molecule.
Retention of Ginsenosides in Dried Ginseng Root: Comparison of Drying Methods
Authors: Popovich David G. , Hu Chun , Durance Timothy D. , Kitts David D.
Published: August 2010

North American ginseng (Panax quinquefolius) has a long history of use and is currently a commercially reliable natural health commodity. Ginsenosides or triterpene saponins are generally regarded as bioactive constituents for several observed health effects associated with ginseng. North American ginseng was dried using 3 different drying techniques to assess the ginsenoside content of prepared extracts. Drying methods included freeze‐drying (FD), air‐drying (AD), and vacuum microwave‐drying (VMD) of ginseng root. High‐performance liquid chromatography (HPLC) analysis showed that FD ginseng processing gave greater (P≥ 0.05) amounts of the fingerprint ginsenosides Rg1 (28 ± 0.9 mg/g, dry weight) and Re (45 ± 0.1) compared with AD (Rg1 19 ± 0.7, Re 29 ± 0.1) and VMD (Rg1 22 ± 0.8, Re 24 ± 0.1); whereas, VMD produced greater amounts of Rb1 (83 ± 0.1) and Rd (13 ± 0.0) than FD (Rb1 62 ± 0.1, Rd 9 ± 0.1) and AD (Rb1 69 ± 0.1, Rd 5 ± 0.0), respectively. Total ginsenoside content was similar for FD and VMD and was the lowest (P≥ 0.05) for AD. Electrospray mass spectrometry (ESI‐MS) analysis showed a total of 12 compounds detected in FD ginseng compared with 10 compounds in ginseng dried by both VMD and AD. Our results support the fact that FD and VMD drying methods of North American ginseng can improve both extraction efficiency and actual retention of individual ginsenoside in root material.
Quality Characteristics of Spaghetti as Affected by Green and Yellow Pea, Lentil, and Chickpea Flours
Authors: Zhao Yonghuan H. , Manthey Frank A. , Chang Sam K.C. , Hou Home‐Jer , Yuan Shaohong H.
Published: August 2010

Spaghetti was made from semolina, containing 5% to 30% milled flours of green pea, yellow pea, chickpea, and lentil, respectively. Physical‐chemical characteristics and descriptive sensory and consumer acceptance characteristics were measured. Spaghetti containing legume flours darkened the spaghetti (P < 0.05) but did not affect the cooked weight significantly. Cooking loss and firmness increased with an increase in legume flour content. Trypsin inhibitor activity (TIA/g) was significantly reduced after cooking. Descriptive intensity analysis showed that the firmness, pulse flavor, and color intensity of the pasta products increased with the increase in the percentages of legume flour fortification up to 30%, whereas the intensity of the shiny appearance, elasticity, and overall quality decreased. Consumers preferred control spaghetti (without legume additives) more than the spaghetti containing legume flours and they slightly liked the spaghetti with 15% lentil or green pea and the spaghetti with 20% chickpea or yellow pea.
Effect of Pectinmethylesterase Infusion Methods and Processing Techniques on Strawberry Firmness
Authors: Duvetter Thomas , Fraeye Ilse , Hoang Tuyen Van , Buggenhout Sandy Van , Verlent Isabel , Smout Chantal , Loey Ann Van , Hendrickx Marc
Published: August 2010

Strawberry halves were pretreated with fungal pectinmethylesterase (PME) and calcium chloride using, respectively, passive osmotic infusion, vacuum‐assisted infusion, and pressure‐assisted infusion with the aim to improve the firmness. The vacuum‐assisted procedure was observed to be the only method able to accomplish an uptake of infusion solution and hence capable of improving the firmness of the strawberries. Significantly less firmness increase was realized when tomato PME was vacuum‐infused instead of fungal PME. Strawberry halves were pretreated by vacuum‐assisted infusion with fungal PME and calcium chloride and were subsequently subjected to thermal treatments at 60 °C and 80 °C and pressure treatments at about 400 MPa and 550 MPa. For all treatments studied, the pretreated sample was significantly firmer compared with the reference sample. For the thermal processes, the residual firmness relative to the initial value before treatment was depending on the temperature of the treatment and not on the pretreatment. However, vacuum‐assisted infusion of PME and calcium could limit the portion of firmness loss due to pressure treatment to 30% compared with 80% for non‐pretreated fruits.
Evaluation of Front‐face Fluorescence for Assessing Thermal Processing of Milk
Authors: Schamberger Gerry P. , Labuza Theodore P.
Published: August 2010

The use of front‐face fluorescence spectroscopy (FFFS) was assessed for its ability to monitor the development of Maillard browning in milk during thermal processing. Skim milk was processed using a Microthermics thermal processing system for a range of conditions from 70 °C to 140 °C from 3 to 30 s. Milk was analyzed using FFFS Hunter L*, a*, b*, hydroxymethylfurfural (HMF), tryptophan, and optical density. FFFS and HMF were found to be the most sensitive methods for distinguishing the heat treatment of milk. Activation energies of 126 and 190 kJ/ mol were found for HMF and FFFS, respectively. A strong correlation was found between these 2 methods. As a fast nonpreparatory method, FFFS is quite useful for evaluating the effect on the 1st stages of the Maillard reaction caused by the heat processing of milk. This work indicates that FFFS with no sample preparation has the potential to be of use as an online instrument for monitoring and control of thermal processing of milk; it can be applied as a process analytical technology (PAT) as is being done in the pharmaceutical industry with other methods.
Effects of Salts and Preheating Temperature of Brine on the Texture of Pickled Cucumbers
Authors: Yoo Kyung Mi , Hwang In Kyeong , Eog Geun , Moon BoKyung
Published: August 2010

The effects of salt type and preheating temperature on the texture and quality of pickled cucumber were studied. Four types of salt were used: bay salt, purified salt, and 2 prepared salts, 1 containing the same amount of Ca2+ and Mg2+ as those of bay salt, and the other containing a 3‐fold higher concentration of Ca2+ and Mg2+ than bay salt. Two different temperatures were used for the salt solutions: 98 °C and 65 °C. All samples were fermented for 30 d at 25 °C. To evaluate the quality of the pickled cucumber with fermentation, the pH level, total acidity, alcohol insoluble solids, and mineral contents were analyzed. Texture and sensory evaluation as well as a microscopic observation were performed to observe the textural change of the pickled cucumber during fermentation. Pickled cucumbers with 98 °C of preheated brine showed better texture than the ones with 65 °C. The pickled cucumbers brined with prepared salt, 1 which had the same amount of Ca2+ and Mg2+ to bay salt, displayed the best result among the samples tested, in terms of sensory, textural, and physical properties.
Mechanical and Thermal Characteristics of Pea Starch Films Plasticized with Monosaccharides and Polyols
Authors: Zhang Yachuan , Han J. H.
Published: August 2010

Edible starch films were produced from pea starch and various plasticizers (mannose, glucose, fructose, and glycerol and sorbitol) at the ratio of 4.34, 6.50, 8.69, and 10.87 mmol plasticizer per gram of starch. After film specimens were conditioned at 50% relative humidity, mechanical properties (tensile strength, elongation, and modulus of elasticity), water vapor permeability (WVP), moisture content, and thermomechanical properties (G’ and tan8) were determined as a function of plasticizer concentration. At all concentration levels, monosaccharides (mannose, glucose, and fructose) made the starch films stronger (higher tensile strength) and more stretchable than polyols (glycerol and sorbitol), while WVP of monosaccharide‐plasticized starch films were lower than those of polyol‐plasticized starch films, especially at higher plasticizer concentration levels. Except for 4.34 mmol/g of mannose‐plasticized film, all the other films showed similar modulus of elasticity at the same plasticizer concentration. Polyol‐plasticized films had lower T than the monosaccharide‐plasticized films. Glucose‐ and sorbitol‐plasticized films needed more activation energy to go through glass transition than others. After all, research results showed that not only the polyols but also the monosaccharides were effective in plasticizing starch films. It is concluded that molecular size, configuration, total number of functional hydroxyl group of the plasticizer as well as its compatibility of the plasticizers with the polymer could affect the interactions between the plasticizers and starch molecules, and consequently the effectiveness of plasticization.
Effects of Water‐Glycerol and Water‐Sorbitol Interactions on the Physical Properties of Konjac Glucomannan Films
Authors: Cheng Lai Hoong , Karim Alias Abd , Seow Chee Choon
Published: August 2010

Konjac glucomannan (KGM)‐edible films were prepared with different amounts of glycerol or sorbitol as a plasticizer. Films were characterized by moisture sorption isotherm, and following conditioning at different relative humidities, by differential scanning calorimetry and tensile tests. Moisture and polyols (sorbitol and glycerol) were found to plasticize KGM‐based films with respect to their tensile properties. However, thermal properties and water sorption capacity (WSC) of polyolplasticized KGM films were found to vary with water activity (aw), namely at low aw (< 0.6), WSC and melting enthalpy were decreased with increasing in polyol content and the opposite was true at higher aw (>0.6). This was attributed to extensive interactions between plasticizer and KGM that reduced the available active site (‐OH groups) for water adsorption. The presence of polyols at low aw appeared to suppress crystalline structures due probably to restricted molecular mobility. These effects were diminished when the moisture content was >20%.
Rapid and Reversible Inhibition of Brain Aromatase Activity
Authors: Balthazart J. , Baillien M. , Ball G. F.
Published: August 2010

Many actions of androgens require their conversion via the enzyme aromatase into oestrogens. Changes in brain aromatase activity are thought to take place via changes in enzyme concentration mediated by effects of sex steroids on aromatase transcription. These changes are relatively slow which fits in well with the fact that oestrogens are generally viewed as slow‐acting messengers that act via changes in gene transcription. More recently, fast actions of oestrogens, presumably at the level of the cell membrane, have been described both in the female brain and in the male brain after the conversion of testosterone to oestradiol. It is difficult to reconcile the slow regulation of oestrogen synthesis (that occurs via changes in aromatase concentration) with a rapid action at the membrane level. Even if fast transduction mechanisms are available, this will not result in rapid changes in brain function if the availability of the ligand does not also change rapidly. Here, we report that aromatase activity in neural tissue of male Japanese quail (Coturnix japonica) is rapidly downregulated in the presence of Mg2+, Ca2+ and ATP in hypothalamic homogenates and in brain explants exposed to high Ca2+ levels following a K+‐induced depolarization or the stimulation of glutamate receptors. The K+‐induced inhibition of aromatase activity is observed within minutes and reversible. Given that aromatase is present in presynaptic boutons, it is possible that rapidly changing levels of locally produced oestrogen are available for nongenomic regulation of neuronal physiology in a manner more akin to the action of a neuropeptide than previously hypothesized.
Involvement of N‐Methyl‐D‐Aspartic Acid Receptor Activation in Oxytocin and Vasopressin Release After Osmotic Stimuli in Rats
Authors: Onaka T. , Yagi K.
Published: August 2010

The present study aimed to examine roles of N‐methyl‐D‐aspartic acid (NMDA) receptors in oxytocin and vasopressin release after osmotic stimuli. A noncompetitive NMDA receptor antagonist, MK‐801 (0.2 mg/kg body weight, i.p.), significantly decreased plasma concentrations of oxytocin and vasopressin after hypertonic saline injection (0.3 or 0.6 M NaCl, i.p., 20 ml/kg). By contrast, oxytocin release induced by injection of cholecystokinin octapeptide (20 µg/kg, i.p.) was not significantly changed by MK‐801. Hypertonic saline injection increased the number of cells expressing Fos in the supraoptic nucleus and in the regions anterior and ventral to the third ventricle (AV3V) regions [the organum vasculosum of the lamina terminalis (OVLT) and median preoptic nucleus]. MK‐801 decreased the number of cells expressing protein in these areas after hypertonic saline injection. A microdialysis method showed that a hypertonic saline injection (0.6 M NaCl, 20 ml/kg, i.p.) facilitated glutamic acid release in and near the OVLT. The results support the view that NMDA receptor in the AV3V region modulates in a facilitative fashion the AV3V inputs to the supraoptic neurosecretory neurones.
cAMP Stimulation of Vasopressin and Oxytocin Release and Regulation of Vasopressin mRNA Stability: Role of Auto‐Facilitation
Authors: Song Z. , Sidorowicz H. E. , Sladek C. D.
Published: August 2010

The effects of cycloheximide and actinomycin on 8‐bromo‐cAMP (8‐Br‐cAMP) stimulated vasopressin and oxytocin release from the posterior pituitary and vasopressin mRNA content of the supraoptic nucleus were studied with perifused explants of the hypothalamo‐neurohypophyseal system. 8‐Br‐cAMP stimulated vasopressin and oxytocin release from the explant for up to 6 h. Inhibition of protein synthesis by cycloheximide completely suppressed the response to 8‐Br‐cAMP. When gene transcription was inhibited by actinomycin, vasopressin release was stimulated by 8‐Br‐cAMP for approximately 2 h, but the response was not sustained. Vasopressin mRNA content was not changed by 8‐Br‐cAMP in the absence or presence of cycloheximide, but it was significantly decreased by simultaneous exposure to 8‐Br‐cAMP and actinomycin. Actinomycin alone did not change vasopressin mRNA content. Since other studies have demonstrated that cAMP stimulates vasopressin gene transcription, and since vasopressin mRNA content reflects the balance between gene transcription and mRNA degradation, the effect of actinomycin and 8‐Br‐cAMP on vasopressin mRNA content suggests that 8‐Br‐cAMP also decreased vasopressin mRNA stability and thereby induced a rapid turnover of vasopressin mRNA. The effects of cycloheximide and actinomycin on vasopressin and oxytocin release suggest that ongoing protein synthesis is required for stimulation of hormone release. Since the posterior pituitary hormone stores are not depleted with a stimulus for release that is even more potent than cAMP, it is possible that cycloheximide and actinomycin depleted smaller pools of the peptides such as those responsible for intranuclear vasopressin and oxytocin release. Further evidence that intranuclear release of vasopressin and oxytocin is a prerequisite for cAMP stimulation of vasopressin and oxytocin release was obtained by demonstrating that d(CH2)5‐D‐Tyr(Me)VAVP, a potent combined V1a/V2/oxytocin receptor antagonist blocked stimulation of vasopressin and oxytocin release by 8‐Br‐cAMP.
Stimulating Effect of Glycoprotein Hormone Free α‐Subunit and Daily Gonadotropin Releasing Hormone Treatment on Prolactin Release from 50‐Day Ovine Foetal Pituitary Explants
Authors: Chabot V. , Gauthier C. , Combarnous Y. , Taragnat C.
Published: August 2010

The aim of our study was to determine whether free α of glycoprotein hormones (free α) plays a role in lactotroph function during early pituitary development in the sheep foetus. Detection and quantification of free α, luteinzing hormone β‐subunit (LHβ) and prolactin immunolabelling were determined by immunocytochemistry at days 32, 37, 42, 50 and 63 of gestation. Free α‐ and LHβ‐containing cells were first detected in the ovine foetal pituitary gland on day 37 of gestation, while prolactin‐containing cells were first identified on day 42. Analysis of serial sections suggested that free α immunoreactive cells were also LHβ‐positive, indicating that free α was mainly synthesized by gonadotrophs. In early foetal stages, free α occurred in the antero‐medio ventral region of the pituitary gland, whereas prolactin‐containing cells were more dorsally and more caudally localized. The free α‐, LHβ‐ and prolactin‐immunostained area increased markedly between days 50 and 63 of gestation. To evaluate a possible functional relationship between gonadotrophs and lactotrophs, the effects of free α or gonadotropin releasing hormone (GnRH) on prolactin release were assayed. Chronic treatment of pituitary explants from male and female 42‐day‐old ovine foetuses for 8 days with 10−9 or 10−7 M ovine free α did not affect prolactin release. By contrast, free α administration on pituitary explants from male and female 50‐day‐old foetuses resulted in enhanced prolactin release. At this age, a daily (2 h per day) treatment with 10−8 M GnRH had similar stimulatory effect to free α whereas a ‘first day’ treatment (24 h on the first day) reduced prolactin release throughout the culture in males and had no effect in females. These results indicate that, despite early detection of free α at day 37 in the ovine foetal pituitary, its stimulatory effect on prolactin release occurs from day 50 of gestation, corresponding to the first period of lactotroph development in vivo. A daily treatment with GnRH mimics the effect of free α on prolactin release.
Expression of mRNA for Prolactin Receptor (Long Form) in Dopamine and Pro‐Opiomelanocortin Neurones in the Arcuate Nucleus of Non‐Pregnant and Lactating Rats
Authors: Kokay I. C. , Grattan D. R.
Published: August 2010

Under most conditions, prolactin secretion from the pituitary gland is subject to negative‐feedback regulation. Prolactin stimulates dopamine release from tuberoinfundibular (TIDA) neurones in the arcuate nucleus of the hypothalamus, which in turn suppresses the production of prolactin. However, during late pregnancy and continuing into lactation, this feedback mechanism becomes less responsive to prolactin and, as a result, a hyperprolactinaemic state develops. We investigated whether long‐form prolactin receptor (PRL‐RL) mRNA is present on TIDA neurones in nonpregnant and lactating rats. In addition, we examined whether PRL‐RL mRNA is colocalised on hypothalamic pro‐opiomelanocortin (POMC) neurones. Dual‐label in situ hybridisations using an 35S‐labelled cRNA probe specific for long‐form PRL‐R, together with a digoxigenin‐labelled RNA probe that encoded either tyrosine hydroxylase (TH) or POMC mRNA, were performed on brain sections. In both nonpregnant and lactating rats, the majority of TH mRNA‐positive cells (> 90%) were found to express long‐form PRL‐R mRNA. In sections from nonpregnant rats, few non‐TH positive cells expressed PRL‐RL mRNA. By contrast, during lactation, the proportion of PRL‐RL mRNA‐positive cells that were not TH mRNA‐positive increased to approximately 70%. Only a small number of neurones in this subpopulation of PRL‐RL mRNA‐positive neurones were found to be positive for POMC mRNA. These data show that the loss of responsiveness to prolactin occuring during lactation is not due to down regulation of long‐form PRL‐R gene expression on TIDA neurones. Moreover, the persistent expression of PRL‐RL in arcuate neuroendocrine circuits suggests that PRL‐R‐mediated signalling continues to be important in these neurones during lactation.
Alpha‐Oestrogen and Progestin Receptor Expression in the Hypothalamus and Preoptic Area Dopaminergic Neurones During Oestrous in Cycling Rats
Authors: Leite C. M. , Szawka R. E. , Anselmo‐Franci J. A.
Published: August 2010

A secretory surge of prolactin occurs on the afternoon of oestrous in cycling rats. Although prolactin is regulated by ovarian steroids, plasma oestradiol and progesterone levels do not vary during oestrous. Because prolactin release is tonically inhibited by hypothalamic dopamine and modulated by dopamine transmission in the preoptic area (POA), the present study aimed to evaluate whether oestrogen receptor (ER)‐α and progestin receptor (PR) expression in the dopaminergic neurones of arcuate (ARC), periventricular, anteroventral periventricular (AVPe) and ventromedial preoptic (VMPO) nuclei changes during the day of oestrous. Cycling rats were perfused every 2 h from 10–20 h on oestrous. Brain sections were double‐labelled to ERα or PR and tyrosine hydroxylase (TH). The number of TH‐immunoreactive (ir) neurones did not vary significantly in any area evaluated. ERα expression in TH‐ir neurones increased at 14 and 16 h in the rostral‐ARC and dorsomedial‐ARC, 14 h in the caudal‐ARC and 16 h in the VMPO, whereas it was unaltered in the ventrolateral‐ARC, periventricular and AVPe. PR expression in TH‐ir neurones of the periventricular and rostral, dorsomedial, ventrolateral and caudal‐ARC decreased transitorily during the afternoon, showing the lowest levels between 14 and 16 h; but it did not vary in the AVPe and VMPO. Plasma oestradiol and progesterone concentrations were low and unaltered during oestrous, indicating that the changes in receptors expression were probably not due to variation in ligand levels. Thus, our data suggest that variations in ERα and PR expression may promote changes in the activity of medial basal hypothalamus and POA dopaminergic neurones, even under unaltered secretion of ovarian steroids, which could facilitate the occurrence and modulate the magnitude of the prolactin surge on oestrous.
Changes in the Brain Serotonin Satiety System in Transgenic Rats Lacking Brain Angiotensinogen
Authors: Voigt J.‐P. , Raasch W. , Hörtnagl H. , Bader M. , Fink H. , Jöhren O.
Published: August 2010

In transgenic rats, TGR(ASrAOGEN)680, with reduced glial expression of angiotensinogen, changes in brain angiotensinogen are associated with reductions in serotonin (5‐HT) content and/or 5‐HT metabolism as determined in various brain regions, including the hypothalamus. These rats showed an anxious phenotype upon a first behavioural screen. The present study aimed to extend the search for functional consequences of changes in brain 5‐HT with respect to feeding behaviour in these transgenic rats. In feeding experiments, rats were treated with the anorectic drug fenfluramine to probe for functional changes in the serotonergic satiety system. Fenfluramine (0.3 mg/kg, i.p.) reduced food intake in TGR(ASrAOGEN)680 rats whereas the minimal effective dose in wild‐type rats was 3 mg/kg, i.p. Although, in the cortex, no differences were apparent in the expression of serotonin 5‐HT1A, 5‐HT1B, 5‐HT2C receptor and 5‐HT transporter mRNAs between TGR(ASrAOGEN)680 and wild‐type rats, the expression of mRNAs for the 5‐HT2C receptor and 5‐HT transporter mRNA were significantly higher in the hypothalamus of TGR(ASrAOGEN)680 rats compared to wild‐type rats. No differences were found in the mRNA levels for hypothalamic 5‐HT1A and 5‐HT1B receptors between TGR(ASrAOGEN)680 and wild‐type rats. Taken together, these findings suggest that the transgenic effect on the brain 5‐HT system is paralleled by functional changes of the serotonergic feeding system.
Affective and Adrenocorticotrophic Responses to Photoperiod in Wistar Rats
Authors: Prendergast B. J. , Kay L. M.
Published: August 2010

The present study tested the hypothesis that seasonal intervals of exposure to modest changes in photoperiod, typical of those experienced by humans living in temperate latitudes (10–14 h light/day), engage changes in emotional behaviour of Wistar rats, a commonly‐used animal model for investigations of affective physiology. Short day lengths (≤ 12 h light/day) induced behavioural despair in a forced‐swim test, exploratory anxiety in an open field arena, and anhedonia in a two‐bottle sucrose preference task, relative to longer day lengths. Plasma adrenocorticotrophic hormone was lower in short‐day relative to long‐day rats, but testosterone and corticosterone concentrations were comparable across treatments. In common with animals that engage reproductive responses to day length, reproductively nonresponsive mammals such as Wistar rats exhibit changes in affective state following small changes in day length. Wistar rats may provide an animal model for the study of seasonal mood regulation because the neuroendocrine, depressive, anxious and anhedonic responses of Wistar rats to short days bear similarities to those observed in some human populations. Standard laboratory husbandry practices (exposure to a 12 : 12 h light/dark cycle) may inadvertently deliver a chronic background depressive and anxiogenic stimulus.
CONCANAVALIN A: THE SEQUENCE OF THE C‐TERMINAL NONAPEPTIDE AND OF A HEPTAPEPTIDE
Authors: Dyckes Douglas F. , Bodanszky Miklos
Published: August 2010

Tryptic digestion of concanavalin A has given rise to two important fragments: a nonapeptide, Leu‐Leu‐Gly‐Leu‐Phe‐Pro‐Asp‐Ala‐Asn, corresponding to the C‐terminal sequence of the protein and a heptapeptide, Trp‐Asn‐Met‐Gln‐Asn‐Gly‐Lys.
AMINO ACID COMPOSITIONS OF ALL THE TRYPTIC PEPTIDES FROM THE α AND β POLYPEPTIDE CHAINS OF ADULT HEMOGLOBIN OF THE SLOW LORIS (Nycticebus coucang)
Authors: Matsuda Genji , Maita Tetsuo , Watanabe Bunji , Ota Hishiro , Araya Aiko , Goodman Morris , Prychodko William
Published: August 2010

Hemoglobin was prepared from blood of adult animals of slow loris, and furthermore a and β polypeptide chains of the globin were separated by column chromatography. These two kinds of polypeptide chains were respectively digested with trypsin. The tryptic peptides thus obtained were isolated and purified by column chromatography and paper chromatography, and then each amino acid composition was analyzed.
THE SOLID‐PHASE SYNTHESIS OF HUMAN AND MONKEY BETA‐MELANOTROPINS
Authors: Wang Kung‐Tsung , Blake James , Li Choh Hao
Published: August 2010

Monkey and human β‐MSH have been synthesized by the solid‐phase method. The protected peptide resin corresponding to the sequence of each hormone was deprotected with liquid HF. Chromatographic purification gave the highly purified and biologically active hormones.
MOLECULAR PARAMETERS OF C‐PEPTIDE FROM BOVINE PROINSULIN
Authors: Markussen Jan , Schiff Hans Erik
Published: August 2010

The molecular parameters of bovine C‐peptide, which is a single‐chain peptide of 26 amino acids, were studied in aqueous solution. The partial specific volume δ was found to be 0.708 cm 3/g, the sedimentation coefficient s o20,w was found to be 0.53 S and the diffusion coefficient D o20,w was found to be 18.4 F. From these data, the frictional ratio f/f o was calculated at 1.31, and the molecular weight at 2421. The true molecular weight is 2383.

Hydration disregarded, the frictional ratio of 1.31 is equivalent to that obtained from a prolate ellipsoid of rotation with a ratio of 1:5.9 between the axes. The axes are calculated at 28.5 and 4.8 Å, making the total length 57 Å. For an oblate ellipsoid of rotation, the ratio between the axes becomes 1:6.7, and the axes become 16.5 Å and 2.5 Å, making the diameter 33 Å.

In insulin crystals, the terminals B 30 and A 1 are 10 Å apart. In proinsulin, these terminals are connected to the C‐peptide terminals through the basic dipeptides Arg‐Arg and Arg‐Lys, allowing, at maximum, a distance of 24 Å between the C‐peptide terminals. Assuming that free C‐peptide takes on the same conformation in solution as when proinsulin‐bound, one may combine the crystallographic and the hydrodynamic data to the following models: (a) A linear peptide chain of 26 amino acids having a bend near the middle, the two halves running antiparallel and close to each other, or (b) A peptide chain forming a planar ring with the terminals closing the loop.
CONFORMATIONAL STUDIES ON ALKALINE PROTEASE FROM Bacillus Mesentericus
Authors: Genov Nicolay , Jori Giulio
Published: August 2010

The alkaline protease from Bacillus mesentericus (E‐30‐III) is soluble in acidic media up to pH 4. Below this pH the protein precipitates. The difference ultraviolet spectra showed that in the pH‐range from 6.0 to 4.1 gradual changes in the environment of the aromatic chromophores in E‐30‐III take place which depend on pH.

On the basis of photooxidation kinetics the following subdivision of the methionyl and tryptophyl residues in E‐30‐III was made: at pH 6.85 two methionyl residues were “slowly reactive”, one tryptophyl residue was “reactive”, and four methionyl and two tryptophyl residues were “unreactive”. At pH 4.10 all six methionyl and one tryptophyl residues were “slowly reactive” and two tryptophyl residues were “reactive”. The comparison between subtilisin BPN‘, subtilisin Carlsberg and protease E‐30‐III showed some differences in the state of methionyl and tryptophyl residues.

Circular dichroism spectra showed that E‐30‐III possesses about 26% α‐helix structure at pH 6.85. At pH 4.10 the protein preserved about 11% α‐helix content.

Gradual but not complete unfolding of the protein molecule occurred when the pH was lowered from 6.0 to 4.1.
STUDIES ON A PROTAMINE (GALLINE) FROM FOWL SPERM: 1. Fractionation and Some Characterization
Authors: Nakano Minoru , Tobita Tohru , Ando Toshio
Published: August 2010

A nuclear basic protein, galline, could be isolated efficiently from semen of the domestic rooster by a method which has been used for preparing protamines from fish sperm. The molecular weight of whole galline was estimated to be about 7,000 as hydrochloride by gel chromatography on Sephadex G‐75 and the sedimentation coefficient was calculated to be 0.74 S by sedimentation velocity method. Whole galline was separated into eight main fractions by ion‐exchange chromatography on Bio‐Gel CM‐30, and each fraction was characterized by means of amino acid and end groups analyses. Three fractions (G‐I, G‐V and G‐VI) of them have thus been confirmed to be almost homogenous and ready for structural studies, and the homogeneity of these three fractions was shown by polyacrylamide disk electrophoresis. The following formulae were obtained based on the amino acid composition and analyses of end groups and terminal sequences. G‐I: H‐Ser‐(Ser2, Gly3, Val, Tyr, Arg14·1)‐Tyr‐OH; G‐V: H‐Ala‐Arg‐Tyr‐(Ar2, Ser, Gly)‐(Thr, Ser7, Pro2, Gly2, Tyr, Arg20·1)‐Ala‐Arg‐Arg‐OH; G‐VI: H‐Ala‐Argn‐Tyr‐(Arg4‐n, Ser, Gly)‐(Thr, Ser7, Pro2, Gly2, Tyr, Arg22·1)‐Ala‐Ser‐Arg‐Arg‐Arg‐OH (n = 1–4).
REDUCTIVE ALKYLATION OF PROTEINS WITH AROMATIC ALDEHYDES AND SODIUM CYANOBOROHYDRIDE
Authors: Friedman Mendel , Williams L. David , Masri M. Sid
Published: August 2010

Reductive alkylation of amino groups in proteins is achieved by treatment with substituted nitrobenzaldehydes and sodium cyanoborohydride in an alcoholic pH 5.2 lithium acetate buffer. The extent of modification was observed by UV spectroscopy and amino acid analysis. Because the new reductive alkylation can be carried out under mild conditions, it should be useful in protein chemistry.
PROTEIN SOLUBILITY: PHASE SEPARATION IN ARACHIN‐SALT‐WATER SYSTEMS
Authors: Tombs M. P. , Newsom B. G. , Wilding P.
Published: August 2010

Solutions of arachin, a groundnut protein, show liquid‐liquid phase separations in certain conditions of ionic strength and pH. Phase diagrams show upper, lower and closed boundaries corresponding to salting in and salting out curves of globulins and a hitherto undescribed solubility behaviour. The protein rich liquid phases and protein ‘precipitates’ are similar.

As conditions approach the phase boundary, arachin undergoes self‐association, as revealed by the concentration dependence of the sedimentation coefficient and gel chromatography, while in D2O, association is more extensive and the phase boundaries are correspondingly shifted. Oligomer formation could lead to thermodynamic instability of the solutions and hence phase separation. At high protein contents (60%) the protein rich phase produces deformed helical crystalline spherulites.

By electron microscopy the protein rich phase contains predominantly oligomers of about 400 Å diameter, but no evidence for long range order could be found.
THE THERMAL POLYMERIZATION OF AMINO ACIDS: The Role and Fate of the Reactants
Authors: Phillips R. Dixon , Melius Paul
Published: August 2010

Amino acid containing polymers were synthesized by heating mixtures of aspartic acid, glutamic acid, glycine, alanine, valine, leucine, isoleucine, and proline in the absence of water at temperatures of 180° to 190°C for several hours. The resulting product was fractionated by dialysis, gel filtration, and chromatography and electrophoresis on paper. The larger polymers were found to be rich in aspartic acid and poor in proline, while the smaller molecules were rich in glutamic acid and contained proline as a significant constituent. The N‐terminal positions are believed to be occupied largely by pyroglutamic acid, while the C‐terminal positions are comprised exclusively of aliphatic amino acids. Aspartic acid and glutamic acid were individually treated to the polymerization conditions. Little reaction of aspartic acid was observed, but glutamic acid formed a melt and upon cooling a glass. Investigation of this product indicated it to be a highly hydrogen bonded system of pyroglutamic and glutamic acids. The model system of glutamic acid and decylamine produced under polymerization conditions, the decylamide of pyroglutamic acid. The accumulated results suggest a model for thermal polymerization.
THERMALLY INDUCED PERMUTATIONS OF ANTIGENICITY AND CONFORMATION OF ARACHIN (PEANUT GLOBULAR PROTEIN)*
Authors: Jacks T. J. , Neucere N. J. , McCall E. R.
Published: August 2010

The reactivity of arachin (principal storage protein of the peanut) with anti‐arachin decreased after arachin was heated at certain temperatures. Infrared and circular dichroic spectra of heated and unheated samples of arachin were examined to determine whether conformational modes changed concomitantly with decreased antigenicity. Infrared absorbances of each sample at amide I, II and V bands were essentially identical; however, absorbances at amide IV and VI bands were altered in relative intensities proportionally to the temperatures of treatment. Conformational modes, determined by circular dichroism, gradually increased in content of unordered structure from α‐helical and pleated sheet modes relative to the temperature of treatment. These observations are discussed in regard to relationships of the loss of antigenicity to conformational changes in heated arachin.
A Hg(II) INDUCED CONFORMATIONAL CHANGE IN PENICILLINASE
Authors: D'Souza Leo , Madaiah Madaiah , Day Richard A. , Nickerson Kenneth W.
Published: August 2010

Penicillinase (E.C.3.5.2.6) from Bacillus cereus 569/H is inhibited by Hg(II). The inhibition is characterized by non‐competitive kinetics and can be reversed by EDTA. A Hg(II) induced conformational change is indicated because: (1) The EDTA regenerated activity is unstable and is rapidly converted to an iodine‐sensitive state, and (2) An irreversible change in the circular dichroism spectrum at 222 nm is found.
INTRINSIC VISCOSITY OF OVOMUCOID IN RANDOM COIL CONFORMATION
Authors: Ahmad Faizan , Salahuddin A.
Published: August 2010

Ovomucoid is denatured by concentrated solutions of guanidine hydrochloride. The intrinsic viscosities of the glycoprotein in 6 M guanidine hydrochloride in the absence and presence of β‐mercaptoethanol were found to be 8.1 and 16.0 ml/g, respectively. Ovomucoid with disulphide bonds reduced exists in linear random coil conformation. However, the intrinsic viscosity of the randomly coiled protein was less than that predicted from the empirical equations describing the molecular weight dependence of intrinsic viscosities of random coil proteins in 6 M guanidine hydrochloride. On excluding the carbohydrate content of the protein, which is theoretically justified, the calculated intrinsic viscosity interestingly became closer to the measured one. The temperature dependence of the intrinsic viscosity of ovomucoid in linear random coil conformation was studied in the temperature range, 25–55°. The features of the intrinsic viscosity‐temperature profile are not comparable with those exhibited by other linear random coil proteins in 6 M guanidine hydrochloride.
ON THE REACTION OF ACETAMIDOMETHANOL WITH NATIVE AND REDUCED BOVINE PANCREATIC TRYPSIN INHIBITOR (KUNITZ INHIBITOR)
Authors: Rocchi Raniero , Benassi Carlo A. , Tomatis Roberto , Ferroni Roberto , Menegatti Enea
Published: August 2010

The stability of native and reduced bovine pancreatic trypsin inhibitor (Kunitz inhibitor) in anhydrous hydrogen fluoride and their reaction with acetamidomethanol, in the same solvent, have been investigated. The bovine Kunitz inhibitor appears to be stable in liquid hydrogen fluoride but the reduced molecule loses about 50% of its ability to regain inhibitory power, upon air oxidation, by exposure to this solvent. Tyrosine residues appear to be affected by acetamidomethylation of the native protein to give a modified inhibitor which is still highly active in inhibiting trypsin. The extent of correct refolding, upon reoxidation, of the reduced tyrosine modified‐inhibitor is greatly diminished. Tyrosine modification can be prevented by carrying out the acetamidomethylation reaction in the presence of excess anisole. The stability constants and the standard free energies of binding of the complexes between trypsin and the native and the tyrosine modified‐inhibitor have been determined.
COMPLETE ENZYMIC DIGESTION OF ACIDIC PROTEINS
Authors: Kay John
Published: August 2010

Acidic proteins are usually resistant to complete enzymic hydrolysis. The increasing number of “unusual” amino acids, which are unstable to acid hydrolysis, makes it necessary to have a method of enzymic hydrolysis applicable to all proteins.

The complete hydrolysis of four acidic proteins by subtilisin plus leucine amino‐peptidase plus prolidase followed by carboxypeptidase C, is described. Recoveries of amino acids were in excellent agreement with the expected content from the known sequences.
KINETICS AND CONTROL OF BOVINE ADRENAL GLUCOSE‐6‐PHOSPHATE DEHYDROGENASE
Authors: Schachet Merl S. , Squire Phil G.
Published: August 2010

Michaelis‐Menten kinetics are observed in studies of highly purified bovine adrenal glucose‐6‐phosphate dehydrogenase at pH 8.0 in 0.1 M bicine. The Km for NADP+ is 3.8 μM and for glucose‐6‐phosphate, 61 μM. At pH 6.9, Km for NADP+ increases to 6.5 μM. The enzyme is inhibited by NADPH both at pH 6.8 and at 8.0 with a Kip of 2.36 μM at pH 8.0. Inhibition is competitive with respect to both substrates implying that addition of substrates is random ordered. The data are also interpreted in terms of “reducing charge”, the mole fraction of coenzyme in the reduced form. This appears to be the major mechanism for regulation of the pentose shunt. D‐glucose, oxidized by the enzyme at a very slow rate, is also a competitive inhibitor for the natural substrate with a Ki of 0.29 M. Phosphate is a competitive inhibitor for glucose‐6‐phosphate oxidation but both phosphate and sulfate accelerate glucose oxidation suggesting a common binding site for the two anions and the phosphate of the natural substrate. While binding of ACTH to our enzyme preparations has been observed, we have not been able, in spite of repeated attempts, to demonstrate augmentation of the activity of the enzyme by the addition of ACTH.
CYLIC PEPTIDES:
Authors: Shimohigashi Yasuyuki , Lee Sannamu , Aoyagi Haruhiko , Kato Tetsuo , Izumiya Nobuo
Published: August 2010

An AM‐toxin analog, cyclotetradepsipeptide, containing an O‐methyl‐l‐tyrosine residue in place of an l‐2‐amino‐5‐arylpentanoic acid residue in AM‐toxins has been prepared by a conventional method. The synthesis was attempted through six different routes and the desired analog was obtained by one such procedure. This compound showed extremely weak activity in causing necrosis on apple leaves.
ION BINDING PROPERTIES IN ACETONITRILE OF CYCLO‐PEPTIDES BUILT UP FROM PROLINE AND GLYCINE RESIDUES
Authors: Hollosi Miklos , Wieland Theodor
Published: August 2010

Ion binding properties of antamanide‐like cyclopeptides cyclo‐(Pro2–Glyn‐Pro2–Glym) (n, m = 1–3) have been studied by CD spectroscopy and by conductivity measurements. Cyclo‐(Pro2–Gly‐Pro2–Gly) forming complexes of different stoichiometry can be characterized by a strong preference of selectivity for Mg++ and Ca++ ions over alkali ions whereas the other members of the series bind selectively alkali and alkaline earth cations with ion radius of about 1 Å. Three main types of CD spectra of cyclic peptides and their complexes can be differentiated. Type I showing two negative Cotton effects at around 220 nm and 200 nm (Ib, Fig. 3), type II showing a positive band around 220 nm and a strong negative one below 190 nm (e.g. Ic in acetonitrile, Fig. 4), and type III showing a strong negative band in the 205 nm region (e.g. metal complexes of Id, Fig. 6).
STUDIES ON MOLECULAR STRUCTURE, SYMMETRY AND CONFORMATION:
Authors: Varughese K.I.
Published: August 2010

Isoleucine occurs in different conformations in the crystalline state and the various conformational aspects are analysed in the light of the energy calculations done earlier in this laboratory.