Synthesis, structure and structure–activity relationship analysis of 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives as potential antibacterial agents

Nine 2-arylthiazolidine-4-carboxylic acid derivatives and nine 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives were synthesized to screen for their antibacterial activities. Compounds 5, 14–18 were first reported. Their chemical structures were clearly determined by ¹H NMR, ¹³C NMR, ESI mass spectra and elemental analyses, coupled with one selected single-crystal structure. All the compounds were assayed for antibacterial activities against two Gram-positive bacterial strains (Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 6538) and two Gram-negative bacterial strains (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 13525) by MTT method. Most of the 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives exhibited better antibacterial activities against the four bacterial strains than relative 2-arylthiazolidine-4-carboxylic acid derivatives. Compound (2RS,4R)-3-(tert-butoxycarbonyl)-2-(5-fluoro-2-hydroxyphenyl)thiazolidine-4-carboxylic acid (14) showed powerful antibacterial activities against P. aeruginosa with IC₅₀ value of 0.195 μg/mL, which was superior to the positive controls Penicillin G and Kanamycin B, respectively. On the basis of the biological results, structure–activity relationships were discussed.     

In vitro activity of commercially manufactured disinfectants againstPseudomonas aerugionsa

The in vitro activity of 17 commercially manufactured disinfectants routinely used in a large teaching hospital was tested against 128 strains ofPseudomonas aeruginosa isolated from hospitalized patients and the hospital environment. Except for quaternary ammonium salts, all the disinfectants at dilutions higher or equalling those recommended by the manufacturer were adequate to suppressP. aeruginosa. Chlorhexidine-, povidone-iodine- and glutaraldehyde-based disinfectants at dilutions 4 to 8-fold lower than the normal use dilution had a marked bactericidal effect (>3 log₁₀ reduction of viable cells) within a short time (10 to 120 min). Similar formulations produced by different manufacturers exhibited comparable activity againstP. aeruginosa.     

Effect of three plastic catheters on survival and growth of Pseudomonas aeruginosa

The effect of Polyvinylchloride (PVC), polyurethane (PU) and siliconized latex (SL) catheters on the survival and growth of six non-mucoid and three mucoid strains of Pseudomonas aeruginosa was evaluated. Pseudomonas aeruginosa (1 × 10⁸) was incubated in PBS alone (control) or with 30 1-cm length segments of each catheter and the number of viable microorganisms was determined after 8 h, 1, 2, 5, 7 and 10 days. The presence of PVC catheters significantly favoured the survival and growth of non-mucoid strains in comparison to the control (P < 0·05 at 5 days, P < 0·01 at 7 days and thereafter); a similar result was observed with SL catheters (P < 0·05 at 2 days, P < 0·01 at 5 days and thereafter). No differences were observed with PU catheters. The number of mucoid microorganisms decreased with time in all controls and suspensions containing segments of catheter, but non-mucoid revertants appeared and quickly increased in the presence of PVC and SL (but not PU) catheters. Eluates of PBS previously containing PVC or SL segments induced a 100- to 500-fold increase in the growth of a non-mucoid strain in comparison with PBS alone. It is concluded that some plastic catheters can release substance(s) that favour the viability of P. aeruginosa.     

High resistance of Pseudomonas aeruginosa to paromomycin,an agent used for selective bowel decontamination (SBD)

Background: Paromomycin is used for selective bowel decontamination (SBD) in patients undergoing bone marrow transplantation in many hospitals, but there are no published resistance data for this compound in the recent medical literature. The aim of this study was to investigate the in vitro activity of paromomycin against the common intestinal bacteria E. coli and P. aeruginosa.Methods: 94 E. coli isolates and 77 P. aeruginosa isolates derived from clinical specimens were tested by broth microdilution against paromomycin and amikacin, respectively, following the CLSI recommendations for testing amikacin.Results: 86 of 94 E. coli isolates (91%) and 71 of 77 P. aeruginosa isolates (92%) showed in vitro susceptibility to amikacin (MIC90 for both compounds: 16 µg/ml, range: 1–32 µg/ml for E. coli and 1–>128 µg/ml for P. aeruginosa). Paromomycin was active against 83/94 E. coli isolates (88%; MIC90: 32 µg/ml, range: 2–>128 µg/ml), but showed poor in vitro activity against P. aeruginosa (3/77 isolates susceptible [4%]; MIC90: >128 µg/ml, range: 2–>128 µg/ml).Conclusion: If SBD with inclusion of an aminoglycoside antibiotic is applied, paromomycin should not be used unless local resistance data provide evidence of a sufficient in vitro activity of this compound against P. aeruginosa.     

Epidemiology of Pseudomonas aeruginosa in a tertiary referral teaching hospital

A genotypically indistinguishable strain of Pseudomonas aeruginosa (Australian epidemic strain III: AES III) has previously been found in a proportion of adults with cystic fibrosis (CF) in Tasmania, Australia. The aim of this study was to identify a source of these infections within the major tertiary referral hospital for the State of Tasmania, and to determine if this strain could be isolated from settings other than the CF lung. A total of 120 isolates of P. aeruginosa were collected from clinical and environmental sources within the hospital and from environmental locations in the hospital vicinity. These isolates were genotyped by random amplification of polymorphic DNA (RAPD)–polymerase chain reaction (PCR) and antimicrobial susceptibility testing was performed using the Clinical and Laboratory Standards Institute method. Confirmation of similar genotypes identified by RAPD–PCR was performed using pulsed-field gel electrophoresis with restriction enzyme SpeI. AES III was not recovered from any source other than the respiratory secretions of CF patients. P. aeruginosa in the non-CF settings was found to be panmictic, and no cross-infection or acquisition of hospital environment strains by patients was observed.     

Respiratory function among waste incinerator workers

Introduction:Whereas air pollutants have been measured in incinerator working areas, few studies have focused on the effects of these pollutants on the lung function of incinerator workers. In France, a study was performed among workers at two urban incinerators, aimed at identifying a link between exposure to different pollutants in incinerator plants and respiratory lung function impairments. Methods: A follow-up of lung function was carried out on 83 incinerator workers from two incinerator plants, comparing them with a group of 76 non-exposed workers recruited by the same occupational physician. Workers lung functions were measured during their yearly occupational medical examination, for 3 years. The American Thoracic Society quality criteria were used to control the quality of the flow–volume curves. Results: Base-line lung functions were lower among incinerator workers than among non-exposed workers. The few significant differences were indicative of obstructive symptoms. During the first year the differences observed between the two groups were close to the significant threshold value of 5% for FEF₇₅/ PV and FEF_25–75/PV. During the third year significant differences covered three parameters: FEF₅₀/PV, FEF_25–75/PV and FEF_25–75/FVC. After smoking habits (pack-years), medical history of allergy or lung diseases and the examination centres had been taken into account in a linear regression, the reduction of FEF₇₅/PV in the first year and FEF_25–75/FVC in the third year was linked to exposure in incinerator plants. There was no significant association between exposure and the differences observed in the FEF_25–75/PV in the first year or in the FEF₅₀/PV and the FEF_25–75/PV in the third year. Conclusion: This analysis of incinerator workers lung functions has identified some lung impairments among workers exposed to incinerator air pollutants compared to non-exposed workers, thus indicating possible obstructive disorders among incinerator workers. However, these impairments are moderate and in accordance with the low levels of airborne pollutants identified in a previous study.     

Epidemiological characteristics ofPseudomonas aeruginosa strains causing infection in an Italian general hospital

During the 1989 calendar year,P. aeruginosa caused clinical infections in 0.46% of patients admitted to Ospedali Riuniti (a general hospital), Bergamo, Italy. Strains (n=267) ofP. aeruginosa were collected during this period, and epidemiological characteristics were studied. The mean prevalence ofP. aeruginosa infection in inpatients was 1.1% (range 0.06–7.3), whereas outpatients showed a significantly lower prevalence of infection (0.05%). Strains were recovered from inpatients of surgical wards (n=126; 47.2%), and outpatients (n=15; 5.6%). Males were more often affected than females (2.7:1). Infection of the urinary tract was the most common (34.1%).Pseudomonas aeruginosa was also involved in lower respiratory tract infections (18.7%) and septicaemia (17.6%). Four typing methods were performed, i.e. serotyping, antibiotyping, pyocin typing, and restriction endonuclease analysis (REA). Serotypes 0:11 and 0:6 were endemic in the hospital. Some serotypes correlated with specific clinical wards. Pyocin typing was an unreliable epidemiological tool. However, antibiotyping showed the presence of some epidemic clusters, probably related to the antibiotic consumption of the patients. REA suggested the circulation of endemicP. aeruginosa strains in both the obstetrics and neurosurgery wards.     

Vegetables as a source of infection with Pseudomonas aeruginosa in a University and Oncology Hospital of Rio de Janeiro

Samples of fresh vegetables fed to patients in an Oncology and a University Hospital were examined for frequency of recovery and counts of Pseudomonas aeruginosa. Thirty-eight isolates from vegetables as well as 98 clinical isolates recovered during the same period of vegetable collection were serotyped and assayed for pyocin production in order to evaluate the role of vegetables as a source of microorganisms. Pseudomonas aeruginosa was recovered from 19·0% of the vegetable samples. Although 1% hypochlorite solution was used as a sanitizer, 50% of the positive samples were found to harbour more than 100 colony-forming units (ctu) g⁻¹. Lettuce, chicory and watercress yielded the highest frequencies of isolation (P < 0·05). The pyocin typing and serotyping of clinical strains revealed some types identical to those recovered from vegetables. Among those found in the University Hospital, serotype O4 and pyocin type PT10/b were detected in vegetables and in clinical specimens whereas types O1-PT22/e, O2a-PT10/a, O2a-PT10/b, O4-PT10/a, O11-PT10/a and O11-PT10/b were common in both groups of strains isolated in the Oncology Hospital. Our results strongly suggest that vegetables represent a source of endemic infection with P. aeruginosa for hospitalized patients.     

Quality of Vegetable Oil Prior to Fortification Is an Important Criteria to Achieve a Health Impact

Unbranded palm cooking oil has been fortified for several years and can be found in the market with different oxidation levels. This study aimed to investigate the stability and shelf life of unbranded, bulk, vitamin A-fortified palm oils with the most commonly observed oxidation levels in Indonesia. Three types of cooking oils were tested: (i) cooking oil with a peroxide value (PV) below 2 mEq O₂/kg (PO1); (ii) cooking oil with a PV around 4 mEq O₂/kg (PO2); and (iii) cooking oil with a PV around 9 mEq O₂/kg (PO3). The oil shelf life was determined by using accelerated shelf life testing (ASLT), where the product was stored at 60, 75 and 90 °C, and then PV, free fatty acid and vitamin A concentration in the oil samples were measured. The results showed that PO1 had a shelf life of between 2–3 months, while PO2’s shelf life was a few weeks and PO3’s only a few days. Even given those varying shelf lives, the vitamin A loss in the oils was still acceptable, at around 10%. However, the short shelf life of highly oxidized cooking oil, such as PO3, might negatively impact health, due to the potential increase of free radicals of the lipid peroxidation in the oil. Based on the results, the Indonesian government should prohibit the sale of highly-oxidized cooking oil. In addition, government authorities should promote and endorse the fortification of only cooking oil with low peroxide levels to ensure that fortification is not associated with any health issues associated with high oxidation levels of the cooking oil.     

Prevalence of protease and elastase production by clinical isolates of Pseudomonas Aeruginosa in relation to aeruginocine typing patterns

Sixty six consecutive P. aeruginosa isolates from heterogeneous clinical specimens were subjected to aeruginocine (pyocine) typing and assayed for in vitro protease and elastase production by a simple and reproducible qualitative test.The 45.4% of the clinical isolates were found to be both protease and elastase (P + E +) producers; 40.9% were only protease producers (P + E –) and 13.6% were non producers (P– E t-). Aeruginocine code 7777 strains were found to be predominant among P + E + and P+ E– types, as 48.2% and 51.7% isolates belonged to the types, respectively, suggesting thereby the virulence of this aeruginocine type in P. aeruginosa infections and the possible association of protease and elastase production with aeruginocine production.     

全国细菌耐药监测网2014—2019年临床分离非发酵革兰阴性杆菌耐药性变迁

目的了解全国临床分离非发酵革兰阴性杆菌的耐药性变迁。方法按照全国细菌耐药监测技术方案要求开展耐药监测工作,参考美国临床实验室标准化协会(CLSI)标准对2014—2019年全国1000余家医院上报至全国细菌耐药监测网的非发酵革兰阴性杆菌的临床资料进行总结和分析。结果非发酵革兰阴性杆菌主要分离自呼吸道标本(痰和支气管肺泡灌洗液)、尿、脓液和血,分别占83.6%,6.5%,4.0%和3.6%。铜绿假单胞菌、鲍曼不动杆菌、嗜麦芽窄食单胞菌和洋葱伯克霍尔德菌占分离细菌的比率分别为8.8%,7.3%,2.1%和0.5%。铜绿假单胞菌对多粘菌素B、阿米卡星和庆大霉素的敏感率分别为96.9%~98.2%,89.1%~94.0%和80.1%~86.4%;对哌拉西林和氨曲南的敏感率分别为66.7%~72.8%和58.8%~62.4%;对其余抗菌药物的敏感率维持在70.4%~81.7%。鲍曼不动杆菌对多粘菌素B、阿米卡星和米诺环素的敏感率分别为96.2%~98.0%,51.0%~58.0%和59.4%~63.4%,对其余抗菌药物的敏感率为35.8%~50.0%。嗜麦芽窄食单胞菌对米诺环素、复方磺胺甲口恶唑和左氧氟沙星的敏感率分别为93.0%~95.3%,89.3%~91.4%和85.0%~86.6%,对替卡西林/克拉维酸和氯霉素的敏感率为37.4%~50.3%和46.6%~51.1%。洋葱伯克霍尔德菌对替卡西林/克拉维酸和氯霉素的敏感率分别为18.5%~37.0%和54.4%~62.2%,对其余抗菌药物的敏感率维持在64.7%~86.8%。耐碳青霉烯类铜绿假单胞菌检出率呈下降趋势,而耐碳青霉烯类鲍曼不动杆菌检出率呈现先上升后下降的变化趋势。结论非发酵革兰阴性杆菌对常用抗菌药物的敏感性无明显变化,耐碳青霉烯类铜绿假单胞菌和鲍曼不动杆菌检出率呈下降趋势。     

Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa isolation from pharyngeal swab cultures among the Japanese elderly at admission to a geriatric hospital

The isolation rate of Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa from pharyngeal swab cultures in the Japanese elderly was studied at admission to a geriatric hospital which had long-term care units. The subjects were 233 consecutive patients who were admitted to K Hospital in the time period April 1994 to March 1996. The isolation rate of MRSA and of Pseudomonas aeruginosa was 10.3% and 8.2% respectively. The proportions of the patients with severely to moderately limited Activities of Daily Living (ADL) (ADL score = 0–1) (P < 0.01), those with fever (P < ;0.01), those with CRP positive (P = 0.04) and those with hypoalbuminemia (serum albumin<3.5 g/dl) (P < 0.01) were higher in the MRSA positive patients than in the negative patients while the proportion of the patients with fever was higher in the Pseudomonas aeruginosa positive patients than in the negative patients (P < 0.02). In the multiple logistic regression analysis, the limitation of ADL (ADL score 0–1 vs 2–3, OR = 1.54, 95% CI = 1.02–2.33) and fever (with vs without, OR = 1.77, 95% CI = 1.18–2.66) remained as risk factors for the isolation of MRSA while only fever (with vs without, OR = 1.67, 95% CI = 1.11–2.53) remained as a risk factor for the isolation of Pseudomonas aeruginosa.     

湖南省细菌耐药监测网2012—2021年铜绿假单胞菌耐药性监测报告

目的 了解2012—2021年湖南省细菌耐药监测网监测医院临床分离铜绿假单胞菌的分布及耐药性变迁情况。方法 采用纸片扩散法或自动化仪器法对临床分离株作药物敏感性(药敏)试验,按美国临床实验室标准化协会(CLSI)2022年版标准判断药敏试验结果,并应用WHONET 5.6软件进行统计分析。应用SPSS对数据进行趋势性检验(Cochran-armitage)及卡方检验。结果 2012—2021年湖南省耐药监测网共监测铜绿假单胞菌176 441株,其中,99.4%的菌株分离自住院患者,约70%的菌株分离自呼吸道标本;儿童(0～17岁)来源的铜绿假单胞菌占8.4%,成人来源的占91.6%。药敏结果显示,10年间铜绿假单胞菌对多黏菌素B最敏感,耐药率低于6%,对哌拉西林、哌拉西林/他唑巴坦、头孢他啶、头孢吡肟、氨曲南、亚胺培南、阿米卡星、庆大霉素、妥布霉素、环丙沙星、左氧氟沙星、多黏菌素B的耐药率均呈下降趋势。共检出耐碳青霉烯类铜绿假单胞菌(CRPA)29 920株,该省CRPA 10年的平均分离率为18.0%。成人CRPA检出率为18.5%,高于儿童的12.3%,均呈下降趋势。结论 湖南省临...     

Comparative hygienic surveillance of contamination with pseudomonads in a cystic fibrosis ward over a 4-year period

In order to study the long-term distribution and population dynamics of Pseudomonas aeruginosa strains in a highly contaminated hospital environment, two 4-week epidemiological studies, with an interval of 4 years, were carried out in the cystic fibrosis (CF) ward of the Paediatric Clinic of the Medical School of Hannover. Out of the 1948 specimens taken, P. aeruginosa was mainly identified in those from moist, inanimate sources (200 isolates) and hospitalized CF patients (168 isolates). A correlation was established between the frequency with which P. aeruginosa-positive patients came into contact with hospital facilities and the rate of contamination of these facilities. Rooms reserved for colonized patients were more frequently contaminated with P. aeruginosa in contrast to function rooms in the same ward and the outpatient clinic. However, no direct exchange between patients' strains and the inanimate hospital environment was detected. Out of the 11 genotypes of P. aeruginosa found in 1989 and the 13 genotypes found in 1993, four genotypes were present on both occasions. The most predominant clone was found in tap-water, sinks, wash-basins and creams with an incidence of 34 and 68% in the environmental isolates. The strains seemed to have spread into the adjacent control ward during the 4-year interval. Thus, the separation of colonized and non-colonized patients was undermined through the transfer of strains from a highly contaminated environment without additional hygiene precautions.     

Seasonal variation of Pseudomonas aeruginosa in culture positive otitis externa in South East England

Otitis externa is the inflammation of the external auditory canal. The disease is common and shows a seasonal variation with a greater incidence in warmer months. Pseudomonas aeruginosa is a common pathogen in otitis externa and in this retrospective study, we show a corresponding seasonal variation in the proportional incidence of P. aeruginosa isolates from otitis externa in South East England. In total 7770 patients were diagnosed with otitis externa over a period of 9 years from January 2008 to December 2016. P. aeruginosa was isolated from 2802 patients (proportional incidence of 36%). Incidence was higher in the months of August, September and October and in patients between 5 and 15 years of age. We postulate a combination of increased contact with water during warm weather in the holiday season and increased rainfall in the preceding season as a putative mechanism for the seasonal trends.Key words: Infection, otitis externa, otitis, pseudomonas, seasonal variation

Otitis externa is the inflammation of the external auditory canal. It is a common problem in general practice [1]. Pseudomonas aeruginosa and Staphylococcus aureus are common pathogens in otitis externa [2, 3].Otitis externa displays a characteristic seasonal variation with a greater disease burden in warmer months [1, 4]. However, this seasonal variation in disease incidence has not been correlated to seasonal trends in the proportional incidence of pathogen isolates. In this retrospective, observational study, we show a seasonal variation in the proportional incidence of P. aeruginosa isolates in otitis externa and correlate the observed variation to changes in environmental conditions.After institutional ethical approval, records of patients with the diagnosis of otitis externa on the sample request forms from January 2006 to December 2016 at Mid Essex Hospitals NHS Trust were analysed. Isolates were obtained from ear swabs cultured on agar following the standard operational procedure for ear swabs; based on the UK standards for microbiology investigations [5]. The proportional incidence of P. aeruginosa was the ratio of culture-positive patients with P. aeruginosa to the total number of patients with any other species isolate. Peak incidence date was estimated using Edward''s method [6]. Environmental data for the study period was obtained from the UK Meterological Office. The number of rainy days was correlated with the number of P. aeruginosa isolates. Statistical analysis was performed using IBM SPSS Statistics for Windows, Version 23.0.In the 9-year study period, 7770 patients had a positive bacterial culture. The commonest isolate was P. aeruginosa (n = 2802, proportional incidence 36%), followed by S. aureus (n = 1850, 24%), Aspergillus and Candida sp. (n = 1410, 18%), Enterobacteriaceae (n = 1289, 17%), anaerobic bacteria (n = 1212, 16%), beta-haemolytic streptococci (n = 811, 10%) and the Haemophilus, Streptococus pneumoniae, Moraxella group (n = 610, 8%). More than one organism was isolated from 3014 patients (39%).The average proportional incidence of P. aeruginosa was 25.9% (95% CI 25.0–26.9). However, there was a clear seasonal trend every year with a peak during the months of August–November (Fig. 1). No seasonal variation was evident for the other species isolates. Open in a separate windowFig. 1.Monthly incidence of P. aeruginosa in otitis externa infection from 2008 to 2016.The proportional incidence of P. aeruginosa also showed age-related differences, with the greatest incidence in the 45–65 age group (25%), followed by over 65 and the 5 to 15 age groups (19% and 18% respectively). The seasonal variation in proportional incidence was clearly observed in 5–15 age group with peaks in August and September (21% and 14% respectively, compared with a yearly average of 8% (95 CI 7.1–9.6)).The number of P. aeruginosa isolates each month correlated with the number of rainy days (r = 0.7). However, there was no correlation between the total number of patients with otitis externa and environmental factors (r = 0.2).The relationship between diseases and seasons have been recognised since antiquity, with Hippocrates postulating changes in environmental factors such as air, water and food as explanatory causes [7]. Our observational study confirms previously documented increases in otitis externa infections during summer months and the relative contributions of different agents to this incidence [1–4]. We have, for the first time, identified P. aeruginosa as a possible causal agent for the seasonal variation in otitis externa. This seasonal variation in the proportional incidence of P. aeruginosa occurs mainly in the 5–15 age group and correlated with the number of rainy days. These associations have only been sparsely described in the literature [1, 8]. Neither the seasonal variation nor the environmental association was observed with other putative pathogens.Predisposing factors for otitis externa include the presence of moisture, long exposure to moisture with an increased risk of maceration and cerumen loss, contact with contaminated water and increased water temperatures that promote rapid growth of the organism [9, 10]. These factors provide a clear causal mechanism for the observed association between the proportional incidence of P. aeruginosa and the number of rainy days. The seasonal variation in the 5–15 age group can be explained by behavioural changes leading to increased exposure to water in the warm summer months.The associations described in the study have practical relevance in choosing empirical antibiotics for otitis externa, especially in younger patients in late summer months. In the absence of a bacterial culture, empirical treatment targeting P. aeruginosa and S. aureus would cover approximately 60% of the isolates in otitis externa.     

Development of resistance to chlorhexidine diacetate in Pseudomonas aeruginosa and the effect of a 'residual' concentration

Stable resistance in Pseudomonas aeruginosa NCIMB 10421 was obtained by step-wise exposure to gradually increasing concentrations of chlorhexidine diacetate (CHX). Repeated exposure to a proposed 'residual' (sub-MIC) concentration of CHX also created stable resistance. Resistance was also developed by a single exposure to the 'residual' concentration of CHX, but this was unstable. Similar experiments with Escherichia coli and CHX or cetylpyridinium chloride resulted in no significant increase in resistance. Antibiotic susceptibility profiles of the CHX-resistant P. aeruginosa cultures showed no cross-resistance, although some of the cultures were resistant to benzalkonium chloride.     

Spot Sample Urine Specific Gravity Does Not Accurately Represent Small Decreases in Plasma Volume in Resting Healthy Males

Background: Urine specific gravity (U_SG) is often used to assess hydration status, particularly around athletic competition, but it is unknown whether high U_SG is indicative of plasma volume (PV) reduction (i.e., hypohydration). We tested the hypothesis that if high U_SG is reflective of reduced PV, subsequent fluid ingestion would increase PV.

Purpose: The purpose of this study was to examine 24-hour changes in U_SG and PV in individuals presenting with high and low spot U_SG.

Methods: Nineteen healthy males were provided food and water over 24 hours with a total water volume of 35 ml·kg^?1 body mass. Absolute PV and blood volume (BV), measured using the CO-rebreathe technique, along with U_SG were measured before and after a 24-hour intervention period. Based on a preintervention morning spot U_SG, subjects were post hoc assigned to groups according to U_SG (≤1.020 or >1.020; low and high U_SG, respectively).

Results: Despite presenting with an elevated spot U_SG (1.026 ± 0.004), subsequent fluid ingestion over 24 hours did not lead to changes (?) in PV (?75 ± 234 ml) or BV (?156 ± 370 ml) in the high U_SG group (p > 0.05). However, a spot U_SG after the 24-hour intervention in this group decreased (p = 0.018) to a level indicating improved hydration status (1.017 ± 0.007). In the low U_SG group, there were no changes in PV (?39 ± 274 ml), BV (?82 ± 396 ml), or U_SG (0.003 ± 0.007) over the 24-hour fluid intervention (all p > 0.05).

Conclusions: Despite a high preintervention U_SG and subsequent decrease after 24-hour fluid intake, measures of PV and BV were not indicative of this seemingly improved hydration status. This suggests that a highly concentrated spot sample U_SG and subsequent changes are not accurately representative of PV or BV.     

Effect of <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> on the rotifer <Emphasis Type="Italic">Brachionus calyciflorus</Emphasis> at different temperatures

Rotifers are one of the smallest metazoans. They serve as a model organism for ecotoxicological studies. More than 60% of the lakes in China are increasingly eutrophic and they are susceptible to blooms of Microcystis aeruginosa. We investigated the effects of M. aeruginosa on the survival and reproduction of Brachionus calyciflorus using the life table method at different temperatures. The findings showed that concentration of M. aeruginosa significantly affected the intrinsic rate of increase (r_m), net reproductive rate (R₀), average lifespan (L) and offspring number (p < 0.05). Temperature also significantly affected the generation time (T), average lifespan (L) and offspring number (p < 0.05). Moreover, the interaction between temperature and concentration had statistically significant effects on offspring number (p < 0.05). M. aeruginosa suppressed the survival and reproduction of B. calyciflorus, particularly at a concentration of 10⁶ cells/mL. The r_m values of the rotifers exposed at 10⁶ cells/mL decreased more than 200% compared with those of the control group. However, at a lower concentration, 10⁴ cells/mL, M. aeruginosa may supply appropriate nourishment to rotifers. In addition, at concentrations of 10⁵ and 10⁶ cells/mL, the inhibition of rotifers by M. aeruginosa heightened with increasing temperature.     

Butyrate and trichostatin A attenuate nuclear factor κB activation and tumor necrosis factor α secretion and increase prostaglandin E2 secretion in human peripheral blood mononuclear cells

The effects of short-chain fatty acids (butyrate, propionate, and acetate) and trichostatin A (TSA), a typical histone deacetylase inhibitor, on tumor necrosis factor (TNF)-α secretion and nuclear factor κB (NF-κB) activation in peripheral blood mononuclear cells induced with lipopolysaccharide were evaluated in relation to prostaglandin E₂ (PGE₂) secretion. Treatment of cells with butyrate; tributyrin, a prodrug of butyrate; propionate; acetate; and TSA down-regulated TNF-α secretion but all up-regulated PGE₂ secretion. Butyrate, propionate, and TSA inhibited NF-κB activation. The effects of the cyclooxygenase-nonspecific inhibitor, indomethacin; the cyclooxygenase-2 selective inhibitor, N-[2-(cyclohexyloxy)-4-nitro-phenyl] methanesulfonamide; and the general lipoxygenase inhibitor, nordihydroguaiaretic acid, varied in cells treated with each short-chain fatty acids. N-[2-(cyclohexyloxy)-4-nitro-phenyl] methanesulfonamide inhibited the effect of propionate on TNF-α secretion, and nordihydroguaiaretic acid inhibited that of acetate. The results showed that butyrate, propionate, and TSA inhibited TNF-α production via PGE₂ secretion and down-regulated NF-κB activation by lipopolysaccharide. These data suggest that the mechanism of butyrate and propionate action is through histone deacetylation and acetate through lipoxygenase activation in the regulation of proinflammatory responses in cells.