3-Phenyllactic acid production by substrate feeding and pH-control in fed-batch fermentation of Lactobacillus sp. SK007

3-Phenyllactic acid (PLA), which is produced by some strains of lactic acid bacteria (LAB), is a known antimicrobial agent with a broad spectrum. Batch and fed-batch fermentation by the strain Lactobacillus sp. SK007 for PLA production have been reported. With batch fermentation without pH-control, PLA production yield was 2.42 g L⁻¹. When fed-batch fermentation by Lactobacillus sp. SK007 was conducted in 3 L initial volume with pH-control at 6.0 and intermittent feeding, which was developed after fermentation for 12 h and every 2 h with 120 mL 100 g L⁻¹ PPA phenylpyruvic acid (PPA) and 50 mL 500 g L⁻¹ glucose each time, PLA production yield reached 17.38 g L⁻¹. The final conversion ratio of PPA to PLA was 51.1%, and the PLA production rate was 0.241 g L⁻¹ h⁻¹. This indicated that PPA was the ideal substrate for PLA fermentation production, and fed-batch fermentation with intermittent PPA feeding and pH-control was an effective approach to improve PLA production yield.     

Supplemental intermittent-day heat training and the lactate threshold

Heat acclimation over consecutive days has been shown to improve aerobic-based performance. Recently, it has been suggested that heat training can improve performance in a temperate environment. However, due to the multifactorial training demands of athletes, consecutive-day heat training may not be suitable. The current study aimed to investigate the effect of brief (8×30 min) intermittent (every 3–4 days) supplemental heat training on the second lactate threshold point (LT₂) in temperate and hot conditions. 21 participants undertook eight intermittent-day mixed-intensity treadmill exercise training sessions in hot (30 °C; 50% relative humidity [RH]) or temperate (18 °C; 30% RH) conditions. A pre- and post-incremental exercise test occurred in temperate (18 °C; 30% RH) and hot conditions (30 °C; 50% RH) to determine the change in LT₂. The heat training protocol did not improve LT₂ in temperate (Effect Size [ES]±90 confidence interval=0.10±0.16) or hot (ES=0.26±0.26) conditions. The primary finding was that although the intervention group had a change greater than the SWC, no statistically significant improvements were observed following an intermittent eight day supplemental heat training protocol comparable to a control group training only in temperate conditions. This is likely due to the brief length of each heat training session and/or the long duration between each heat exposure.     

Predictive feedback control and Fitts–law

Fitts’ law is a well established empirical formula, known for encapsulating the “speed-accuracy trade-off”. For discrete, manual movements from a starting location to a target, Fitts’ law relates movement duration to the distance moved and target size. The widespread empirical success of the formula is suggestive of underlying principles of human movement control. There have been previous attempts to relate Fitts’ law to engineering-type control hypotheses and it has been shown that the law is exactly consistent with the closed-loop step-response of a time-delayed, first-order system. Assuming only the operation of closed-loop feedback, either continuous or intermittent, this paper asks whether such feedback should be predictive or not predictive to be consistent with Fitts law. Since Fitts’ law is equivalent to a time delay separated from a first-order system, known control theory implies that the controller must be predictive. A predictive controller moves the time-delay outside the feedback loop such that the closed-loop response can be separated into a time delay and rational function whereas a non- predictive controller retains a state delay within feedback loop which is not consistent with Fitts’ law. Using sufficient parameters, a high-order non-predictive controller could approximately reproduce Fitts’ law. However, such high-order, “non-parametric” controllers are essentially empirical in nature, without physical meaning, and therefore are conceptually inferior to the predictive controller. It is a new insight that using closed-loop feedback, prediction is required to physically explain Fitts’ law. The implication is that prediction is an inherent part of the “speed-accuracy trade-off”.     

The effect of recombinant human erythropoietin on serum selenium levels in hemodialysis patients

Successful results in the treatment of anemia, one of the main complications of chronic renal failure, can be achieved by the use of recombinant human erythropoietin (RhEPO), which is available almost fifteen years in clinics. On the other hand, as both chronic renal failure and maintenance hemodialysis reduce the levels of trace elements, this study was designed to evaluate the interaction potential of RhEPO with serum concentrations of selenium (Se) during four months. Thirty one adult hemodialysis outpatients participated in the study. Ten of them, not on any drug therapy to interact with RhEPO, recruited as “Control Group”, and the remainder, on RhEPO therapy, as “RhEPO Group”. Blood was drawn from the Control Group at the beginning of the study, and from the RhEPO Group at every month for four months. Serum erythropoietin levels were measured by a radioimmunoassay method and Se status by a spectrofluorometric method. It was found that Se levels were not affected by RhEPO treatment during 3 months of therapy, while an increase was seen on the fourth month. The observation indicates that the increase in serum Se levels would be significant in longer than three-month RhEPO treatment.     

Stochastic algorithms for Markov models estimation with intermittent missing data

Multistate Markov models are frequently used to characterize disease processes, but their estimation from longitudinal data is often hampered by complex patterns of incompleteness. Two algorithms for estimating Markov chain models in the case of intermittent missing data in longitudinal studies, a stochastic EM algorithm and the Gibbs sampler, are described. The first can be viewed as a random perturbation of the EM algorithm and is appropriate when the M step is straightforward but the E step is computationally burdensome. It leads to a good approximation of the maximum likelihood estimates. The Gibbs sampler is used for a full Bayesian inference. The performances of the two algorithms are illustrated on two simulated data sets. A motivating example concerned with the modelling of the evolution of parasitemia by Plasmodium falciparum (malaria) in a cohort of 105 young children in Cameroon is described and briefly analyzed.     

Prolactin and zinc in dialysis patients

The objectives of the present study were to investigate the frequencies of hyperprolactinemia and hypozincemia in patients undergoing hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD), the associations between blood levels of zinc (Zn²⁺) and hormones, and dietary zinc intake amount and its relation to zincemia. We studied 28 patients (14 HD and 14 CAPD) who had their blood levels of Zn²⁺, prolactin (PRL), parathyroid hormone (PTH), and gonadotropins (LH, FSH) evaluated. Thirteen patients had dietary nutrient amounts evaluated from a 3-d nutritional record. Hyperprolactinemia occurred in 29% patients (HD = CAPD), hypozincemia in 62% (20% HD and 42% CAPD), and low dietary Zn²⁺ intake in 90% of patients. No correlation among blood concentration of Zn²⁺ and PRL, PTH, LH, and FSH were observed in the two modalities of dialysis or between zincemia and Zn²⁺ ingestion. We concluded that the occurrence of hyperprolactinemia and hypozincemia were not related to dialysis modality and that zincemia did not reflect the observed low dietary intake of Zn²⁺.     

Hospital Patient‐Care and Outside‐the‐Hospital Energy Profiles for Hemodialysis Services

Studies investigated the patient‐care (in‐hospital) and outside‐the‐hospital energy consumptions for delivering the hemodialysis (HD) service. A life cycle inventory methodology was used for this patient‐based analysis for two hospitals located in Wichita, Kansas. It was found that, for both hospitals, the actual HD machines consumed approximately 3.5 kilowatt‐hours (kWh) of electrical energy per HD, only 8% to 16% of the total energy used for delivering the HD service (in hospital). This increases to 9.6 to 28.9 kWh of hospital billable energy for the whole system of HD machine, auxiliaries, and dialysis water treatment. Converting these hospital direct electrical energy values to natural resource energy (nre) then adding the cradle‐to‐gate natural resource energy for the manufacturing and supply chain of all the HD consumables, the total is 78 to 149 kWh nre/HD. The nre measures all the direct fuel burned to generate energy and is thus directly related to emissions to the air, water, and land and is a direct secondary impact on public health from HD. The ratio of outside‐the‐hospital energy to direct hospital HD electrical energy consumption is 4:1 to 7:1, so a broader base exists for improvement than just the hospital.     

维持性血液透析患者孤独状况与社会支持的关系研究

目的:调查维持性血液透析(MHD)患者的孤独状况,并探讨其与社会支持的关系。方法:采用问卷调查的方式对145例2018年1月至2019年6月期间来我院就诊的MHD患者(实验组)和同期150例健康状况良好正常人(对照组)进行调查,内容包括一般资料调查表、孤独量表(UCLA)、社会支持评定量表(SSRS),单因素Logistic回归模型筛选出造成孤独状况的危险因素,再采用非条件多因素Logistic回归模型计算危险因素与疾病的相关性。结果:实验组UCLA得分为(65.12±12.38)分,明显高于对照组的(25.38±5.57)分(P0.05),实验组SSRS量表中客观支持、主观支持、支持利用度以及总分分别为(14.86±1.89)分、(13.12±2.13)分、(10.88±1.56)分、(35.21±11.82)分,均低于对照组的(18.78±3.23)分、(20.95±3.06)分、(15.61±2.28)分、(50.98±15.24)分(P0.05)。多因素非条件Logistic回归显示MHD患者孤独状态的危险因素依次是客观支持、主观支持、支持利用度、透析年限及年龄(OR=5.246、4.568、4.315、4.172、2.342,均P0.05)。结论:MHD患者处于较为严重的孤独状态,社会支持是造成患者孤独状况的首要危险因素,良好的社会支持可以改善MHD患者的孤独状况。     

血液灌流联合血液透析对维持性血液透析患者IL-6、TNF-alpha、hs-CRP及 Hcy等指标水平的影响

目的：研究血液灌流联合血液透析对接受维持性血液透析（MHD）的患者白介素-6（IL-6）、肿瘤坏死因子（TNF-alpha）、超敏C 反应蛋白（hs-CRP）及同型半胱氨酸（Hcy）等指标水平的影响。方法：选择2010年5 月至2013 年5 月在我院接受MHD的终末期 肾病112 例作为研究对象。根据数字法随机分成观察组及对照组,每组均含56 例患者。对照组行常规血液透析治疗,观察组行血 液灌流及血液透析的联合治疗。治疗12 周后对比分析两组治疗前后的各项炎性因子与营养学指标,及生活质量指数（QOL）评 分。结果：治疗后观察组的hs-CRP、IL-6 及TNF-alpha与Hcy水平均显著低于对照组,差异均有统计学意义（均P＜0.05）。治疗后观察 组的血清Hb、TP及Alb 与TRF水平均显著高于对照组,差异均有统计学意义（均P＜0.05）。两组治疗后的QOL评分较治疗前均 显著上升,但观察组的上升幅度显著大于对照组,差异均有统计学意义（均P＜0.05）。结论：血液灌流与血液透析联合治疗接受 MHD的患者,可有效改善患者机体的微炎症及营养状况,提升患者的生活质量,效果明显,值得临床推荐。     

Habitat background selection by colonizing intermittent pond invertebrates

Habitat selection processes by organisms colonizing freshwater bodies have not been commonly studied, despite their obvious relevance to wetland ecology and management. We monitored, weekly, all organisms that appeared in tanks with different backgrounds (brown; white) and substrate/food availability treatments (control; added leaf litter; added algae) floating on the water surface of a natural intermittent pond. The experiment lasted for 14 weeks, from pond filling to pond drying, during which time we collected around 9,000 colonizing insects per m² (e.g., Diptera, Coleoptera, Hemiptera, and eggs) and a similar number of colonizing non-insects (e.g., Acari, Crustacea, Gastropoda, and ephippia). Non-insects exhibited greatest colonization early in the hydroperiod, correlated with major rain-fall events. Insect colonization was low at first, peaked in late May, and thereafter remained high until the pond dried. Most ovipositing female insects (especially chironomids) were attracted to tanks with a dark background or those containing decomposing dark leaves, although there were exceptions related to taxon (e.g., beetles) and hydroperiod. Non-insects showed treatment preferences similar to the insects, with cladoceran ephippia appearing more in the Leaf treatment. Colonization mechanisms were deemed ‘active’ for insects and largely ‘passive’ for the microcrustaceans, and the various possibilities for the latter (heavy rainfall, wind, wildlife) are discussed. For highly dispersive taxa, such as adults of the beetles Helophorus sp. and Anacaena sp. colonization densities at the pond surface were calculated to attain maxima of around 26 and 33 m⁻² respectively, in early May. Handling editor: S. Declerck