As the number falls,alternatives to the Hagberg–Perten falling number method: A review

This review examines the application, limitations, and potential alternatives to the Hagberg–Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end-product quality mainly due to starch degradation by the enzyme α-amylase. By viscometry, the FN test indirectly detects the presence of α-amylase, the primary enzyme that digests starch. Elevated α-amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α-amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α-amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract-specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α-amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high- and low-FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near-infrared spectroscopy, and hyperspectral imaging.     

Allocentric Versus Egocentric Spatial Memory After Unilateral Temporal Lobectomy in Humans.

Thirty patients who had undergone either a right or left unilateral temporal lobectomy (14 RTL; 16 LTL) and 16 control participants were tested on a computerized human analogue of the Morris Water Maze. The procedure was designed to compare allocentric and egocentric spatial memory. In the allocentric condition, participants searched for a target location on the screen, guided by object cues. Between trials, participants had to walk around the screen, which disrupted egocentric memory representation. In the egocentric condition, participants remained in the same position, but the object cues were shifted between searches to prevent them from using allocentric memory. Only the RTL group was impaired on the allocentric condition, and neither the LTL nor RTL group was impaired on additional tests of spatial working memory or spatial manipulation. The results support the notion that the right anterior temporal lobe stores long-term allocentric spatial memories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure to cure Mycobacterium gordonae peritonitis associated with continuous ambulatory peritoneal dialysis

Nontuberculous mycobacteria are increasingly recognized as important pathogens in peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD). Mycobacterium gordonae rarely causes human infection and is the least likely mycobacterium to produce clinical infection in CAPD patients. We describe a patient with persistent M. gordonae peritonitis acquired while undergoing CAPD. During 18 months of treatment, clinical improvement occurred but a microbiological cure could not be achieved. Principles of therapy for mycobacterial peritonitis developing during CAPD are reviewed, and potential explanations for our patient's failure to respond to therapy are discussed.     

Effects of a K+ATP channel opener, lemakalim, on systemic, coronary and regional vascular dynamics in conscious dogs: comparison with nifedipine, adenosine, nitroglycerin and acetylcholine

The systemic, coronary and regional vascular responses to the K+ATP channel opener lemakalim were compared to other potent vasodilators (i.e., nifedipine, adenosine, nitroglycerin and acetylcholine). Experiments were performed in 12 conscious dogs 2 to 4 weeks after implantation of aortic catheters and flow probes on the ascending aorta, left circumflex coronary, celiac, mesenteric, renal and iliac arteries, and solid-state miniature pressure gauges in the left ventricular cavity. Dose-response curves induced by bolus injection (i.v.) were examined. For doses that reduced total peripheral resistance by 22%, lemakalim reduced celiac (-28 +/- 2%), mesenteric (-24 +/- 3%), renal (-17 +/- 3%) and iliac (-18 +/- 3%) vascular resistances (i.e., by amounts similar to those observed with the other vasodilators, except for adenosine, which increased renal resistance). At these doses, lemakalim induced a greater decrease (-52 +/- 3%) (P < .05) in coronary resistance, as compared with nifedipine (-35 +/- 3%), adenosine (-38 +/- 3%), nitroglycerin (-25 +/- 2%) and acetylcholine (-32 +/- 3%). However, when near maximal vasodilation was elicited, adenosine elicited the greatest (P < .05) decrease in coronary resistance (-81 +/- 1%), as compared with lemakalim (-74 +/- 2%), nifedipine (-67 +/- 2%), nitroglycerin (-63 +/- 2%) and acetylcholine (-72 +/- 1%). Both the time to maximal increases in regional blood flow and the time for recovery in all vascular beds were significantly prolonged for lemakalim compared with the other vasodilators. Thus, the K+ATP channel opener lemakalim dilates the coronary bed out of proportion to other vascular beds, is relatively more potent at lower doses than other vasodilators and exhibits a delayed and more prolonged action in all regional vascular beds.     

Neural network control of communications systems

Neural networks appear well suited to applications in the control of communications systems for two reasons: adaptivity and high speed. This paper describes application of neural networks to two problems, admission control and switch control, which exploit the adaptivity and speed property, respectively. The admission control problem is the selective admission of a set of calls from a number of inhomogeneous call classes, which may have widely differing characteristics as to their rate and variability of traffic, onto a network. It is usually unknown in advance which combinations of calls can be simultaneously accepted so as to ensure satisfactory performance. The approach adopted is that key network performance parameters are observed while carrying various combinations of calls, and their relationship is learned by a neural network structure. The network model chosen has the ability to interpolate or extrapolate from the past results and the ability to adapt to new and changing conditions. The switch control problem is the service policy used by a switch controller in transmitting packets. In a crossbar switch with input queueing, significant loss of throughput can occur when head-of-line service order is employed. A solution can be based on an algorithm which maximizes throughput. However since this solution is typically required in less than one microsecond, software implementation policy is infeasible. We will carry out an analysis of the benefits of such a policy, describe some existing proposed schemes for its implementation, and propose a further scheme that provides this submicrosecond optimization.     

Copy number differences in the 195 bp repeated satellite DNA from Trypanosoma cruzi and Trypanosoma rangeli: potential use for epidemiologic surveys

Detection of a nondistended pyriform sinus on cross-sectional imaging studies represents a diagnostic dilemma. The finding may be an inconstant physiologic phenomenon without clinical significance, or it may be due to tissue thickening and lack of pliability related to neoplasia or inflammation. Rescanning during respiratory maneuvers may clarify the anatomy, but full patient cooperation is needed. We demonstrate a method (turning the patient's head away from the side of the nondistended sinus) that induces distention of the pyriform sinus but does not require active patient participation.     

The band areas of proteins determined by fluorescent scanning in the commercial automated gel electrophoresis apparatus

An automated gel electrophoresis apparatus, recently available commercially, allows one to follow the band during electrophoresis in real time, and lends itself therefore to an evaluation of bandwidth as a function of migration time (the dispersion coefficient), resolution and band shape. These determinations assume the constancy of band area with migration time and at various gel concentrations. The purpose of the present study was to verify these assumptions. Representative proteins and sodium dodecyl sulfate (SDS)-proteins, either natively fluorescent or fluorescein carboxylate labeled, were found to exhibit band areas which approach constancy as a function of migration time in both agarose and polyacrylamide gel electrophoresis, provided that (i) the protein concentration under the band was low enough to obviate self-quenching of fluorescence; (ii) the separation of the protein of interest from contaminants had progressed sufficiently during the time at which band areas were measured; (iii) the baseline under the peak was sufficiently well defined. However, band areas decrease with increasing gel concentration. Protein peaks exhibited leading and trailing tails. The ratio of the combined tail area to total area appeared to be near-constant at varying migration times. However, that ratio increases with increasing gel concentration. The tail area does not appear to be an artifact of fluorometric detection since it is reproduced upon fluorimetric analysis of the protein eluted from gel slices after electrophoresis. However, it may be due to photochemical destruction under the conditions of repetitive fluorometric peak detection.     

Metabotropic glutamate receptors are involved in long-term potentiation in isolated slices of rat medial frontal cortex

The prelimbic region of medial frontal cortex in the rat receives a direct input from the hippocampus and this functional connection is essential for aspects of spatial memory. Activity-dependent changes in the effectiveness of synaptic transmission in the medial frontal cortex, namely long-term potentiation (LTP) and long-term depression (LTD) can persist for tens of minutes or hours and may be the basis of learning and memory storage. Glutamatergic activation of ionotropic receptors is required to induce both LTP and LTD. We now present evidence of the involvement of metabotropic glutamate receptors in LTP in isolated slices of frontal cortex. Repetitive bursts of stimulation at theta frequencies (TBS) were applied to layer II, and monosynaptic EPSPs were monitored in layer V neurons of the prelimbic area. TBS was found to be more effective at inducing LTP than tetanic stimulation at 100 Hz and produced LTP that lasted >30 min in 8 out of 14 neurons. Tetanic stimulation at 100 Hz in the presence of the N-methyl--aspartate (NMDA)-antagonist 2-amino-5-phosphonopentanoate (AP5) was reported to be a reliable method of inducing LTD in prelimbic cortex (). However we found that this protocol did not facilitate the induction of LTD. The role of metabotropic glutamate receptors (mGluR) in LTP was assessed by using the selective, broad-spectrum antagonist (R, S)-alpha-methyl-4- carboxyphenylglycine (MCPG). This drug significantly reduced the incidence of LTP after TBS to only 1 of 14 neurons (P < 0.02, chi2 test). The pooled responses to TBS in MCPG showed significantly reduced potentiation [(P < 0.02, analysis of variance (ANOVA)]. The broad-spectrum mGluR agonist (1S, 3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) and the selective group I agonist S-3 hydroxyphenylglycine(S-3HPG) both produced membrane depolarization, an increase in number of spikes evoked by depolarizing current pulses, and a reduction in the afterhyperpolarization. Similar effects were produced by these agonists even when synaptic transmission was blocked by use of the gamma-aminobutyric acid-B (GABAB) receptor agonist, 200 microM baclofen, which suggests that group I mGluRs are present on layer V neurons. We conclude that mGluRs participate in the production of LTP in prelimbic cortex, and that this excitatory effect could be mediated by the postsynaptic group I mGluRs.