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The response of Monoterpenes to Different Enzyme Preparations in Gewürztraminer (Vitis vinifera L.) Wines

The α-terpineol, linalool, nerol and geraniol, which are the main aromatic monoterpenes in the grapevine varietyGewürztraminer, were determined in the grapes, must and wine after treatment with six different pectolytic enzymes[Lallzyme-β (‘Lall’); Rohavin VR-C (‘VRX’), Rohapect D5L (‘D5L’), Rohavin MX (‘MX’), Rohapect VRC (‘VRC’),Endozym cultivar A (‘Cult. A’)], and after treatment with β-glucosidase (βG, EC 3.2.1.21). The concentrations ofmonoterpenic compounds were determined by solid-phase microextraction (SPME) and GC-MS. The most abundantmonoterpene in the grapes of Gewürztraminer was geraniol (66.7 μg/L), followed by nerol (13.3 μg/L), α-terpineol(7.8 μg/L) and finally linalool (3.3 μg/L). Gewürztraminer wine from must treated with the Lall enzyme preparationwas the most aromatic, which was also confirmed by chemical and sensory analysis in which the concentrations ofnerol (45.9 μg/L), geraniol (31.8 μg/L), α-terpineol (10.5 μg/L) and linalool (6.1 μg/L) were determined. The winesproduced from must treated chemically with enzymes showed higher concentrations of many of the monoterpenecompounds compared to the control, although the sensorial analysis did not affirm this convincingly

Impact of Alternative Skin Contact Procedures on the Aroma Composition of White Wine

Zelen, Ribolla Gialla and Malvasia Istriana, grapes from the Vitis vinifera (L.) varieties, were subjectedto four processes involving grape skin contact. Fresh and fruity young wines were produced by adding6% or 12% grape berries, respectively, during alcoholic fermentation, freezing the pomace (Fp) and thefreezing whole grapes (Fg). Wine-free volatile aromatic compounds were determined using two extractiontechniques coupled to gas chromatography (GC). These aromatic compounds and wine standard chemicalparameters were compared to control wines produced without skin contact. Esters, higher alcohols,terpenes, volatile phenols and C6 alcohols proved to be the most important sensorial odorants in wines.Both the content of aromatic compounds and the odour activity values showed some positive effects fromskin contact. The freezing of the grapes and addition of 12% grape berries proved most effective forZelen and Malvasia Istriana, producing a more intensive fruity and floral odour, a less intensive solventodour and additional freshness. The same processes resulted only in additional fruitiness or a less intensivesolvent odour in Ribolla Gialla while the lowest concentrations of grape derived terpenes were achieved forthis variety. The three varieties were most affected by freezing processes. During the sensorial evaluation,the wines that had been subjected to skin contact were generally preferred to the control wines

Cervicothoracic Intradural Arachnoid Cyst Misdiagnosed as Motor Neuron Disease

Recognizing syndromes which mimic ALS is crucial both to avoid giving this diagnosis erroneously and since there may be appropriate treatments. We report a 63-year-old woman diagnosed with possible ALS five years ago based on upper and lower motor neuron signs with typical electrophysiology and normal cranial MRI. At reassessment, spinal MRI revealed a cervicothoracic cyst with cord compression that was successfully treated neurosurgically. Histopathology confirmed an arachnoid origin as suspected from MRI. Spinal cysts may mimic ALS and need to be thoroughly excluded by appropriate imaging

Comparative studies on the structure of an upland African stream ecosystem

Upland stream systems have been extensively investigated in Europe, North America and Australasia and many of the central ideas concerning their function are based on these systems. One central paradigm, the river continuum concept is ultimately derived from those North American streams whose catchments remain forested with native vegetation. Streams of the tropics may or may not fit the model. They have been little studied. The Amani Nature Reserve in the East Usambara Mountains of north-eastern Tanzania offers an opportunity to bring these naturally forested systems to the attention of the ecological community. This article describes a comparison made between two lengths of the River Dodwe in this area. The work was carried out by a group of postgraduate students from eighteen European and African countries with advice from five staff members, as part of a course organised by the Tropical Biology Association. Rigorous efforts were made to standardise techniques, in a situation where equipment and laboratory facilities were very basic, through a management structure and deliberate allocation of work to specialists in each area.The article offers a summary of invertebrate communities found in the stream and its biomass. Crabs seem to be the key organism in both sections of the streams

Statistical methods to correct for verification bias in diagnostic studies are inadequate when there are few false negatives: a simulation study

<p>Abstract</p> <p>Background</p> <p>A common feature of diagnostic research is that results for a diagnostic gold standard are available primarily for patients who are positive for the test under investigation. Data from such studies are subject to what has been termed "verification bias". We evaluated statistical methods for verification bias correction when there are few false negatives.</p> <p>Methods</p> <p>A simulation study was conducted of a screening study subject to verification bias. We compared estimates of the area-under-the-curve (AUC) corrected for verification bias varying both the rate and mechanism of verification.</p> <p>Results</p> <p>In a single simulated data set, varying false negatives from 0 to 4 led to verification bias corrected AUCs ranging from 0.550 to 0.852. Excess variation associated with low numbers of false negatives was confirmed in simulation studies and by analyses of published studies that incorporated verification bias correction. The 2.5^th– 97.5^thcentile range constituted as much as 60% of the possible range of AUCs for some simulations.</p> <p>Conclusion</p> <p>Screening programs are designed such that there are few false negatives. Standard statistical methods for verification bias correction are inadequate in this circumstance.</p