Pattern of 72-hour intragastric acidity in a homogeneous group of intensive care unit patients

To gain insight into the variation over time of gastric acidity in postoperative ICU patients, intragastric pH was prospectively studied in patients undergoing elective abdominal aortic reconstructive surgery during a 72-hr intra- and postoperative period. Intragastric pH was monitored continuously in 14 patients with combined glass electrodes. During the day of surgery (day 1), the median 24-hr pH for all patients was 6.25 (5.8-7.0, IQR). However, three of the 14 studied patients had a median 24-hr pH of 1.8. The median 24-hr pH throughout day 2 for all was 2.45 (1.6-4.7, P = 0.001). The median 24-hr pH on day 3 was 1.6 (1.5-2.1, P = 0.001). Median 8-hr pH values demonstrate a remarkable interpatient and intraindividual variation in the course of the postoperative period. A progressive lowering of the intragastric pH was observed in the first 40 hr. From the 40- to 48-hr interval until the end of the study, no further significant decrease was found. The intragastric pH was above 4, 74% of the time during day 1, 39% during day 2 (P = 0.006) and 16% during day 3 (P = 0.003). Percentage of time above 4 on day 2 was significantly higher than on day 3 (P = 0.04). In conclusion, since gastric acid and pepsin seem to play a role in stress ulceration, this study suggests some patients are at risk of stress ulceration from the beginning of surgery, but most patients become at risk of stress ulceration in the course of the postoperative period.     

Effect of omeprazole 40 mg once daily on intraduodenal and intragastric pH in H. pylori-negative healthy subjects

There is a lack of information about the effect of omeprazole or other antisecretory drugs on intraduodenal pH. Aim of the study was to document the variation over time of intraduodenal pH during a 24-hr period and to simultaneously study the effect of omeprazole 40 mg once daily on intragastric and intraduodenal pH in healthy H. pylori-negative subjects. In a randomized, placebo-controlled study, eight subjects (five women, three men, mean age 22.7 years) received oral 40 mg omeprazole or placebo once daily for eight days. On day 7, intragastric and intraduodenal pH was measured continuously for 24 hr, using two miniature glass-membrane electrodes placed in the stomach (fundus) and in the distal third of the duodenum. The 24-hr median intraduodenal pH was 5.95 with placebo and 5.85 with omeprazole. Median intragastric pH was 1.68 without and 4.93 with omeprazole. During omeprazole therapy, intragastric pH fell below 4.0 in five of eight subjects. In the 2- and 3-hr postprandial periods, the percentage of time with pH < 5 was significantly reduced with omeprazole. In healthy subjects, 24-hr median and postprandial pH in the distal part of the duodenum was lower than previously thought. Omeprazole significantly reduced the percentage of time with pH < 5 postprandially. At night, intragastric pH fell below 4.0 with omeprazole 40 mg once daily. Omeprazole does not change 24-hr median intraduodenal pH significantly.     

Molecular determinants of a Ca2+-binding site in the pore of cyclic nucleotide-gated channels: S5/S6 segments control affinity of intrapore glutamates

Cyclic nucleotide-gated (CNG) channels play an important role in Ca2+ signaling in many cells. CNG channels from various tissues differ profoundly in their Ca2+ permeation properties. Using the voltage-dependent Ca2+ blockage of monovalent current in wild-type channels, chimeric constructs and point mutants, we have identified structural elements that determine the distinctively different interaction of Ca2+ with CNG channels from rod and cone photoreceptors and olfactory neurons. Segments S5 and S6 and the extracellular linkers flanking the pore region are the only structural elements that account for the differences between channels. Ca2+ blockage is strongly modulated by external pH. The different pH dependence of blockage suggests that the pKa of intrapore glutamates and their protonation pattern differ among channels. The results support the hypothesis that the S5-pore-S6 module, by providing a characteristic electrostatic environment, determines the protonation state of pore glutamates and thereby controls Ca2+ affinity and permeation in each channel type.     

PET and CBF studies of chronic hydrocephalus: a contribution to surgical indication and prognosis

The management of acute myoglobinuric renal failure, the major complication of rhabdomyolysis, continues to be a treatment dilemma for the clinician as limited therapeutic options are available. Previously, we have demonstrated that continuous arteriovenous hemofiltration (CAVH) is an effective technique for removing myoglobin in an animal model. In the present study, swine were administered four grams of equine myoglobin intravenously and underwent the continuous veno-venous hemofiltration (CVVH) procedure for six hours each. Animals were studied in each of the following groups: CVVH at a pump rate 100 ml/minute, CVVH at a pump rate 200 ml/minute and CVVH at a pump rate 100 ml/minute plus dialysis at a dialysate flow rate of one Liter/h. Once the filtering process was initiated there was a rapid and sustained production of ultrafiltrate in all groups. The amount of myoglobin excreted in the ultrafiltrate over the six-hour filtering period was 688, 948 and 570 mg which corresponded to 17, 24 and 14 percent of the administered dose, respectively, for the three treatments. In comparison to previous CAVH experiments, CVVH removed more circulating myoglobin and the addition of the dialysis component did not appear to improve removal. Based on these findings, it appears that the CVVH hemofiltration system is a viable option for the removal of systemic myoglobin.     

Right hemisphere emotional perception: evidence across multiple channels

Emotional perception was examined in stroke patients across 3 communication channels: facial, prosodic, and lexical. Hemispheric specialization for emotion was tested via right-hemisphere (RH) and valence hypotheses, and relationships among channels were determined. Participants were 11 right-brain-damaged (RBD), 10 left-brain-damaged (LBD), and 15 demographically matched normal control (NC) adults. Experimental measures, with analogous psychometric properties, were identification and discrimination tasks, including a range of positive and negative emotions. Nonemotional control tasks were used for each channel. For identification, RBDs were significantly impaired relative to LBDs and NCs across channels and valences, supporting the RH hypothesis. No group differences emerged for discrimination. Findings were not influenced by demographic, clinical, or control variables. Correlations among the channels were more prominent for normal than for brain-damaged groups.     

Birthweight and neonatal outcome at the Muhimbili Medical Centre, Dar es Salaam, Tanzania

BACKGROUND: The level of residual noise in auditory brainstem responses (ABR) depends not only on the number of averages but also on the amplitude of background noise and on the frequency of artifacts. This paper describes the influence of digital filtering and of different methods of artifact suppression on the residual noise of ABRs. METHOD: Amplitude of background noise was estimated for 1033 ABRs recorded under suprathreshold stimulation (70 and 90 dB nHL) in 251 subjects. In 45 ABR recordings in 15 subjects, all 4000 individual sweeps were stored for off-line simulation. The power spectrum of background noise was investigated using an FFT analyzer. RESULTS: A great variability of mean noise amplitude was found both between subjects and in the recordings for each subject. Depending on the slope of the analogue 100-Hz high-pass filter, mean RMS values of background noise of 4.2 microV (6 dB/Oct.) and 2.5 microV (12 dB/Oct.), respectively, were found. Digital high pass filtering before averaging was found to increase the signal-to-noise ratio (SNR) considerably. CONCLUSIONS: Results indicate that (i) effective suppression of low-frequency noise components can only be achieved by zero phase digital filtering and (ii) if clipping of noise amplitude to 25 microV is used, optimized artifact rejection as weighted averaging or adopted artifact rejection levels have only small effect on the SNR.     

Effects of nicotine dose and administration method on withdrawal symptoms and side effects during short-term smoking abstinence.

The effects of using several different nicotine replacement treatments on self-reported withdrawal symptoms and side effects during 2-day periods of smoking cessation, with 5 days of ad lib smoking between cessation days, were evaluated. Participants (N ?=?18) experienced the following conditions: nicotine gum, 24-hr patch, 16-hr patch, 24-hr patch plus gum, double 24-hr patch, and no nicotine replacement. The present study found morning urge to smoke was greater during the 16-hr than during the 24-hr patch condition. Double-patch use resulted in significantly greater insomnia than the smoking baseline and 16-hr patch conditions. The no medication and gum alone conditions resulted in similar withdrawal symptoms, and both tended to result in greater reported withdrawal symptoms than the smoking baseline condition. There were no significant withdrawal symptom differences between the 24-hr, patch-gum, and double-patch conditions. The 24-hr and double-patch conditions were preferred by two thirds of the participants (6 each). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial summation in simple (Fourier) and complex (non-Fourier) texture channels

Complex (non-Fourier, second-order) channels have been proposed to explain aspects of texture-based region segregation and related perceptual tasks. Complex channels contain two stages of linear filtering with an intermediate pointwise nonlinearity. The intermediate nonlinearity is crucial. Without it, a complex channel is equivalent to a single linear filter (a simple channel). Here we asked whether the intermediate nonlinearity is piecewise-linear (an ordinary rectifier), or compressive, or expansive. We measured the perceptual segregation between element-arrangement textures where the contrast and area of the individual elements were systematically varied. For solid-square elements, the tradeoff between contrast and area was approximately linear, consistent with simple linear channels. For Gabor-patch elements, however, the tradeoff was highly nonlinear, consistent with complex channels in which the intermediate nonlinearity is expansive (with an exponent somewhat higher than 2). Also, substantial individual differences in certain details were explainable by differential intrusion from "off-frequency" complex channels. Lastly, the results reported here (in conjunction with those of other studies) suggest that the strongly compressive intensive nonlinearity previously known to act in texture segregation cannot be attributed to a compressive nonlinearity acting locally and relatively early (before the spatial-frequency and orientation-selective channels) but could result from inhibition among the channels (as in a normalization network).     

Biochemical evidence that Saccharomyces cerevisiae YGR262c gene, required for normal growth, encodes a novel Ser/Thr-specific protein kinase

BACKGROUND AND PURPOSE: This study was designed to determine regional differences and age-related changes in the contribution of ATP-sensitive potassium (KATP) channels to vasodilator responses in the brain stem circulation in vivo. METHODS: Changes in diameter of the basilar artery (baseline diameter, 270 +/- 5 microns [mean +/- SEM]), its large branch (112 +/- 5 microns), and its small branch (49 +/- 2 microns) in response to KATP channel openers levcromakalim and Y-26763 were measured through a cranial window in anesthetized adult (4 to 6 months) and aged (24 to 26 months) Sprague-Dawley rats. RESULTS: Topical application of levcromakalim and Y-26763 produced concentration-dependent vasodilation that was similar among the three vessel groups in adult rats. In aged rats, dilator responses of the branches, but not of the basilar artery, to the KATP channel openers were smaller than those in adult rats (P < .05). Glibenclamide, a selective KATP channel blocker, almost abolished this vasodilation in both groups of rats. Vasodilator responses to sodium nitroprusside were preserved in aged rats. CONCLUSIONS: In adult rats, there is no regional heterogeneity in vasodilator response to KATP channel openers in the brain stem circulation in vivo. In aged rats, although KATP channels are also functional in the brain stem circulation, dilator response of the microvessels but not of the large arteries to direct activation of KATP channels is impaired.     

基于图像分割的噪声方差估计

提出一种基于图像分割的噪声方差两步估计算法.第一步,对含有噪声的图像进行平滑,再利用统计区域归并算法对图像进行分割,并计算每个区域的方差,根据统计规律选择适当的区域估计图像中噪声方差.第二步,利用初始估计的方差,修正平滑滤波、图像分割及噪声估计的参数,进行新一轮的平滑、分割和方差估计,得出更为准确的估计结果.在大量图像和不同噪声情况下的实验结果表明,该算法可以快速、准确地估计图像中噪声方差.      

Human leucocyte antigen-DQA1, -DQB1 polymorphism distribution in Shanghai Chinese women with pregnancy induced hypertension]

Our objective was to determine if maternal urinary calcium excretion is altered during treatment of mild preeclampsia remote from term with the calcium channel blocker nifedipine. One hundred forty-eight women with mild preeclampsia were randomly allocated to treatment with either bed rest alone (n=64) or in combination with nifedipine (n=84) at 26-36 weeks' gestation. All women had 24 hr urine samples collected for creatinine clearance and calcium excretion determination prior to therapy and during treatment. There was no difference in gestational age at the time of urine collection between the two groups. There were no differences in 24-hr creatinine clearance and calcium excretion between the groups prior to therapy. When followed longitudinally, there was a significant reduction in calcium excretion within each group (p=0.0005 control group, p <0.0001 nifedipine group). Further, a significant reduction in calcium excretion was noted following nifedipine therapy (62+/-94 mg Ca/24 hr) compared to the control group (143+/-153 mg Ca/24 hr), p <0.001. Consistent with previous studies, we have shown that progressive hypocalciuria is a feature of preeclampsia. Further, urinary calcium excretion decreased despite nifedipine therapy. Altered urinary calcium excretion may be less reflective of the progression in severity of preeclampsia in patients treated with nifedipine.     

In memoriam. Raymond Millard Cable 1909-1995

1. This experiment was designed to pharmacologically characterize a novel calcium channel blocker, AE0047. 2. After 1-hr treatment with each drug (10(-6) M), K(+)-induced contraction in rat aortic strip was clearly depressed by nifedipine and manidipine and slightly depressed by AE0047. After a wash out of the preparation in drug-free medium, the inhibition of K(+)-induced contraction by nifedipine or manidipine was abolished or unchanged, respectively. In contrast, AE0047-produced inhibition was reinforced with time after removal of the drug. 3. A cell membrane depolarization-induced 45Ca uptake into tissue was depressed completely by nifedipine, but, if it was washed out, merely 20% inhibition of control remained. AE0047-produced inhibition became prominent after drug removal. Manidipine did not have the same inhibitory effect after wash out. 4. A receptor-binding study indicated that affinity of AE0047 and manidipine for the dihydropyridine-sensitive Ca channel receptor was lower than that of nifedipine. AE0047, unlike nifedipine and manidipine, inhibited [3H]PN200-110 binding more strongly when a 4-hr preincubation was used than without extended incubation. 5. The drug molecule of AE0047 was highly partitioned into the lipid bilayer of the synaptosome in canine cerebral cortices. In the synaptic membrane and liposomes, both prepared from canine cerebral cortices, the respective partition coefficients of the drug were 6997 +/- 2309 and 422 +/- 28 against 1395 +/- 161 and 24 +/- 2 of nitrendipine. 6. AE0047 showed slower onset of inhibition against K(+)-induced contraction and enhanced Ca influx compared with manidipine and nifedipine. These results may suggest that AE0047 requires a long period of time to occupy the dihydropyridine-sensitive sites within the Ca channel, which was detected by decreased specific [3H]PN200-110 binding, and to inhibit K(+)-induced Ca influx into rat aorta.     

Direct high affinity modulation of connexin channel activity by cyclic nucleotides

Protonated aminosulfonate compounds directly inhibit connexin channel activity. This was demonstrated by pH-dependent connexin channel activity in Good's pH buffers (MES (4-morpholineethanesulfonic acid)), HEPES, and TAPS (3-({[2-hydroxy-1, 1-bis(hydroxymethyl)ethyl]amino]-1-propanesulfonic acid)) that have an aminosulfonate moiety in common and by the absence of pH-dependent channel activity in pH buffers without an aminosulfonate moiety (maleate, Tris, and bicarbonate). The pH-activity relation was shifted according to the pKa of each aminosulfonate pH buffer. At constant pH, increased aminosulfonate concentration inhibited channel activity. Taurine, a ubiquitous cytoplasmic aminosulfonic acid, had the same effect at physiological concentrations. These data raise the possibility that effects on connexin channel activity previously attributed to protonation of connexin may be mediated instead by protonation of cytoplasmic regulators, such as taurine. Modulation by aminosulfonates is specific for heteromeric connexin channels containing connexin-26; it does not occur significantly for homomeric connexin-32 channels. The identification of taurine as a cytoplasmic compound that directly interacts with and modulates connexin channel activity is likely to facilitate understanding of cellular modulation of connexin channels and lead to the development of reagents for use in structure-function studies of connexin protein.     

Position-linked interference in forming simple visual groups.

Experiments with 2-element visual groups reveal a form of interference that has several interesting properties. Observers judged the orientation of an imaginary line formed by 2 pixels (the target) while attempting to ignore a 3rd pixel (the noise). Noise interfered with performance, even when it was made distinct from the target in various ways. This interference was strongly position linked; a single equation described the interference pattern for many different target-noise configurations. Maximum interference was observed not when the noise was closest to the target but when it was at a distance of half the separation between target pixels. Some initial findings were consistent with the idea that visual grouping reflects the operation of visual channels with Gabor-like receptive-field profiles, but subsequent results implicated processes that automatically construct visual boundaries. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Voltage-dependent proton transport by the voltage sensor of the Shaker K+ channel

In voltage-dependent ion channels, pore opening is initiated by electrically driven movements of charged residues, and this movement generates a gating current. To examine structural rearrangements in the Shaker K+ channel, basic residues R365 and R368 in the S4 segment were replaced with histidine, and gating currents were recorded. Changes in gating charge displacement with solvent pH reveal voltage-dependent changes in exposure of the histidine to solvent protons. This technique directly monitors accessibility changes during gating, probes the environment even in confined locations, and introduces minimal interference of gating charge motion. The results indicate that charges 365 and 368 traverse the entire electric field during gating. The remarkable implication of the successive exposure of histidine to each side of the membrane is that in a pH gradient, the voltage sensor transports protons.     

Prolonged ambulatory oesophageal pH and pressure recording in healthy adults in Singapore

BACKGROUND/AIM OF STUDY: Data on prolonged ambulatory oesophageal pH and pressure monitoring in normal subjects in the East are limited. This study aimed to define the normal characteristics of ambulatory oesophageal pH and motility among healthy adults in Singapore. METHOD: Prolonged ambulatory oesophageal pH and pressure recording was performed on 10 healthy volunteers using a one-channel pH probe, a two channel pressure probe, a portable digital data recorder and a computerised data analysis system. The median (range) number of episodes with pH < 4 and the percentage of total time with pH < 4 were 24% (4%-56%) and 3.0% (0.2%-4.0%) respectively. They were greater in the upright than supine positions. RESULTS: The median percentages of peristaltic and simultaneous contractions were 65.8%-80.5% and 10.6%-12.7% respectively. The frequency, amplitude and duration of peristaltic contractions were greater during mealtimes than between meals in the upright position. CONCLUSION: This study provides the first data on prolonged ambulatory oesophageal pH and manometry in healthy Singaporean adults.     

陡脉冲干扰下的心电信号滤波及QRS提取

为消除陡脉冲带来的干扰,分析了陡脉冲干扰的特点,建立了陡脉冲噪声数学模型,提出了基于变分模态分解（Variational mode decomposition, VMD）的心电信号滤波算法,提取叠加在心电信号中陡脉冲干扰分量、识别陡脉冲干扰分量并剔除陡脉冲干扰分量;为减少VMD分解层数、提高实时性并减少内存消耗,提出了心电信号预处理算法;针对医疗环境中的随机噪声伴随陡脉冲出现的情况,分析了VMD后子信号中随机噪声的特点,提出了基于VMD子信号能量估计的阈值去噪算法;利用变分模态分解的带通滤波器组特性,提出了基于变分模态分解子信号重组的QRS波群检测算法,配合滤波算法以提高心电信号特征检测精度。以添加了高斯白噪声和模拟陡脉冲干扰的MIT?BIH数据库心电信号和医疗环境中采集的心电信号为实验对象,分别实现对滤波算法和QRS波群检测算法的定量对比分析。      

Perfusion system components release agents that distort functional properties of rod cyclic nucleotide-gated ion channels

In switching from studying native cyclic nucleotide-gated (CNG) ion channels in rod cells to studying the corresponding cloned channels expressed in Xenopus oocytes, we changed our perfusion system to a more efficient one. This change involved replacing culture flasks and a small plexiglass/glass chamber with plastic syringes, metal needles, and plastic petri dishes. We now report that these new perfusion system components release agents that distort or obscure measured functional properties of rod CNG channels. The magnitude and time course of appearance of the artifacts vary widely among individual components (e.g. from syringe to syringe). The effects most resemble voltage-dependent block of the channels, giving a decrease in current at positive potentials, and producing distortions of the kinetics and voltage dependence of channel activation.     

Effects of red wine on 24-hour esophageal pH and pressures in healthy volunteers

The purpose of this study was to assess the effects of red wine taken with meals on esophageal motility, esophageal exposure to acid, and gastric pH. Following a randomized design, 14 healthy male volunteers (mean age 25 years, range 18-35 years were given 360 ml of red wine or tap water during lunch or dinner. All subjects underwent ambulatory 24-hr esophageal motility and esophagogastric pH monitoring studies. Three different periods were analyzed: during meals (30 min), postprandial (3 hr), and 8-hr supine. Two volunteers complained of heartburn after wine ingestion. An increase in the number of high amplitude waves (> 125 mm Hg, 95th percentile of our motility unit controls) was observed during meals accompanied by wine: water 1.2 (0-10.2), wine 1.6 (0-32.6), P = 0.02 [median (range)]. No other esophageal motility changes occurred. Percent reflux time increased during the postprandial period after wine ingestion in comparison with water: 1.7 (0-14.9) vs 0.1 (0-0.8), P < 0.05. Gastric pH was unaffected by the type of drink. Ingestion of moderate amounts of red wine with meals increases postprandial esophageal exposure to gastric acid in healthy persons.