Stability of meropenem in normal saline solution after storage at room temperature

The bactericidal activity of meropenem is determined by the time that concentrations in tissue and serum are above the MIC for the pathogens during the dosing interval. Thus, the most effective mode of administering of meropenem is continuous infusion. However, the stability of meropenem reconstituted in solution is influenced by the storage temperature. Until now we have had no data to evaluate the stability of this drug during continuous infusion in a tropical country. The objective of this study was to provide such data. Meropenem 0.5 g and 100 ml normal saline solution were mixed together and stored at room temperature for 8 hours. Half of the solution was stored in a room with air conditioning at 20 degrees C and the other half of the solution was stored in a room without air conditioning at 32 degrees-37 degrees C. The concentrations of meropenem in the solution were measured at 0, 1, 2, 3, 4, 6 and 8 hours after the drug was reconstituted. Twelve lots of (0.5 g meropenem in normal saline) solution were evaluated in each temperature condition. The mean meropenem concentrations reconstituted in normal saline solution decreased 1.66%, 3.31% and 5.80% after 2, 4 and 8 hours storage at 20 degrees C, respectively. Drug concentrations decreased 3.14%, 5.86% and 11.85% after 2, 4 and 8 hours storage at 32 degrees-37 degrees C, respectively. Therefore, we conclude that this agent should not be administered by 8-hour continuous infusion at room temperature in a tropical country.     

Genuine divalent magnesium-ion storage and fast diffusion kinetics in metal oxides at room temperature

Rechargeable magnesium batteries represent a viable alternative to lithium-ion technology that can potentially overcome its safety, cost, and energy density limitations. Nevertheless, the development of a competitive room temperature magnesium battery has been hindered by the sluggish dissociation of electrolyte complexes and the low mobility of Mg²⁺ ions in solids, especially in metal oxides that are generally used in lithium-ion batteries. Herein, we introduce a generic proton-assisted method for the dissociation of the strong Mg–Cl bond to enable genuine Mg²⁺ intercalation into an oxide host lattice; meanwhile, the anisotropic Smoluchowski effect produced by titanium oxide lattices results in unusually fast Mg²⁺ diffusion kinetics along the atomic trough direction with a record high ion conductivity of 1.8 × 10⁻⁴ S ⋅ cm⁻¹ on the same order as polymer electrolyte. The realization of genuine Mg²⁺ storage and fast diffusion kinetics enabled a rare high-power Mg-intercalation battery with inorganic oxides. The success of this work provides important information on engineering surface and interlayer chemistries of layered materials to tackle the sluggish intercalation kinetics of multivalent ions.

Rechargeable multivalent metal-ion batteries are promising energy sources that can potentially satisfy the existing demand for high-energy density electrochemical energy storage devices (1, 2). The electrochemical discharge and charge reactions in these batteries involve multiple electron transfers per ion, which may significantly increase the ion storage capacity relative to that of monovalent batteries. Among the studied systems, Mg-ion batteries utilizing divalent magnesium ions (Mg²⁺) as charge carriers are considered the most viable option. In addition to their numerous advantages such as abundant Mg resources, low fabrication cost, and environmental friendliness, these batteries exhibit dendrite-free Mg plating and stripping during electrochemical cycling, which ensure high operational safety. Furthermore, the volumetric capacity of Mg anodes (3,833 mAh ⋅ cm⁻³) is almost twice as large as that of Li anodes (2,062 mAh ⋅ cm⁻³) (3–5). Unfortunately, it is very difficult to realize genuine storage and fast transport of Mg²⁺ ions in solids (especially in inorganic oxides) at low temperatures due to their high degree of polarization and charge density. The charge of the Mg²⁺ ion is two times larger than that of the Li⁺ ion, although the ionic radius of Mg²⁺ (0.72 Å) is close to that of Li⁺ (0.76 Å). As a result, Mg²⁺ ions are more likely to form strong covalent bonds with electrolytes (such as Mg–Cl bonds in the commonly used all-phenyl complex electrolytes) with very high dissociation energy. Meanwhile, the strong electrostatic interactions between Mg²⁺ ions and solid host lattices significantly inhibit their diffusion kinetics in these lattices. Resultantly, the migration barrier for Mg²⁺ ions is usually higher than that for Li⁺ ions in the same cathode material (6–8).To overcome the Mg bond dissociation barrier and enhance Mg-ion diffusion kinetics, intercalation chemistries based on solvated Mg²⁺ as the intercalating cation species, including Mg(DME)₃²⁺, Mg(H₂O)_x²⁺, and MgCl⁺, have been established (9–11). These complex ions lower the charge density by either increasing the ionic radius or decreasing the net charge. Although the storage of these complex ions alleviates the drawbacks related to the dissociation and diffusion of bare Mg²⁺ ions, it produces several challenges. The practical energy densities at the cell level for the hybrid battery based on such intercalation chemistry are lower than that of the battery exclusively involving Mg²⁺ storage. Additionally, the coinsertion of these bulky solvent molecules induces significant volume changes of the electrode, thereby limiting its cycle life. Recently, a two-pronged approach has been developed to overcome these challenges (12). It involved the storage of exclusively Mg²⁺ ions and their fast solid-state diffusion in an organic cathode fabricated from pyrene-4,5,9,10-tetraone. Heterogeneous enolization redox chemistry was utilized to avoid the bond cleavage and reformation; meanwhile, an electrolyte comprising weak-coordinated anions in an ethereal solvent blend was employed to increase the bulk ion mobility and promote Mg²⁺ desolvation on the electrode surface. However, it still remains a critical challenge in inorganic materials to overcome the two important problems: the ion dissociation in the conventional Mg chloride complex electrolyte and solid-state ion diffusion. The development of rechargeable inorganic cathodes for Mg batteries using a rational structural design is the major limiting factor of this promising post–Li-ion battery technology.Metal oxides are the most promising electrode materials for Li-ion batteries, taking advantage of their excellent chemical and thermal stabilities; however, this is not always true for Mg-ion batteries. Compared to sulfides and selenides, most metal oxides suffer from low reversible capacities and slow diffusion kinetics, owing to the higher strength of the Mg–O bond as compared with those of the Mg–S and Mg–Se bonds (7, 13). Furthermore, the reaction of Mg ions with highly polarizable O²⁻ ions often leads to MgO formation rather than Mg²⁺ intercalation, making it almost impossible to achieve reversibility in oxide-based cathodes (14). Therefore, the development of rechargeable metal-oxide electrode materials for Mg-ion batteries characterized by genuine Mg²⁺ storage, fast solid-state diffusion kinetics, and excellent cycling performance (especially at room and low temperatures) remained an unsurmountable challenge.In the present study, genuine Mg²⁺ intercalation/deintercalation and fast diffusion in oxide lattices were realized not only at room temperature but also at subzero temperatures. These outstanding results were achieved by placing protons on negatively charged metal-deficient oxide sheets and disorderly stacking these sheets over a certain distance (this strategy is schematically illustrated in Fig. 1). The stripping of Cl⁻ ions was facilitated by the presence of protons between the sheets, while fast Mg²⁺ diffusion was ensured by the extension of the wavefunction along an atomic trough on the unique sheet surface due to the anisotropic Smoluchowski effect. This induced the formation of flat potential-energy surfaces and diffusion highways, which gave a record high Mg-ion conductivity of 1.8 × 10⁻⁴ S ⋅ cm⁻¹. As a result, the fabricated Mg-ion cell exhibited a high-power density of 7.4 kW ⋅ kg⁻¹ while maintaining an energy of 113.0 Wh ⋅ kg⁻¹. Practically, the cell battery, which was charged in 55 s, could be gradually discharged for a stable long run of ∼4.5 h. Even at a subzero temperature of −15 °C, the electrode capacity remained above 55%, and the diffusion coefficient was in the range of 10⁻⁹ tο 10⁻¹¹ cm² ⋅ s⁻¹ (10⁻⁸ to 10⁻¹⁰ cm² ⋅ s⁻¹ at room temperature). The proposed strategy is generic and can be easily applied to other two-dimensional electrode materials, including titanium oxide, manganese oxide, and oxyanion-terminated titanium carbide.Open in a separate windowFig. 1.Schematic illustration. The genuine Mg²⁺ storage mechanism and fast diffusion in the oxide electrode, which were studied using PhMgCl–AlCl₃ electrolyte. The protons efficiently stripped Cl ions from the electrolyte complex, ensuring the genuine Mg²⁺-intercalation chemistry. The anisotropic Smoluchowski effect or wavefunction extension along the atomic troughs on the surface created pathways for the unusually fast diffusion of Mg²⁺ species.     

Characterization of plasma protein activity in riboflavin and UV light‐treated fresh frozen plasma during 2 years of storage at −30°C

Background The Mirasol Pathogen Reduction Technology System (PRT) for Plasma (CaridianBCT) is based on a riboflavin and UV light treatment process resulting in pathogen inactivation due to irreversible, photochemically induced damage of nucleic acids. This study evaluated the in vitro protein quality of plasma products treated with riboflavin and UV light following treatment and subsequent storage for up to 104 weeks at ?30°C. Materials and Methods Apheresis and whole blood‐derived plasma products were combined with riboflavin solution and exposed to ultraviolet light. Treated plasma was then flash frozen, within 8 h of collection, stored at ?30°C for up to 104 weeks and analysed at different stages of storage using standard coagulation assays. Results were compared with paired, untreated units stored for the same intervals. Results The average percent protein retention for all time‐points in PRT‐treated plasma samples after 36, 69, 87 and 104 weeks of storage at ?30°C in comparison with controls held under similar conditions were: Total Protein, 101%, Factor VIII, 79%, Fibrinogen, 78%, Factor II, 87%, Factor XII, 86%, Factor X, 84% and Factor IX, 81%. Anticoagulant and inhibitor proteins showed between 90% and 100% retention after 1 year (52 weeks) and 69 weeks of storage. No clinically relevant complement activation was observed in treated and stored samples. Conclusion Riboflavin and UV light‐treated plasma demonstrates reductions in several plasma coagulation factors following treatment. This reduction in activity levels is noted immediately after treatment and remains relatively constant during 2 years of storage at ?30°C.     

Effect of storage of sputum specimens at room temperature on smear and culture results

A study of 41 specimens of sputum stored for up to 28 days at room temperature in a tropical country showed that smear results were not affected by storage, the positivity being 83% before storage and 80–83% after. The culture positivity was 88% before storage, and 83%, 68%, 22%, 13% and 0% after 3, 7, 14, 21 and 28 days of storage respectively. The reduction in positivity on storage attains significance at 7 days (P=0.05).Another study involved 163 specimens of sputum and storage for 3, 5 or 7 days. Each specimen was examined before storage and after 2 periods of storage, at random. The smear results were again not affected. There was, however, significant loss of viability, the proportion culture positive being reduced from 92% before storage to 83% at 3 days (P = 0.05), 71% at 5 days (P < 0.01) and 63% at 7 days (P < 0.001). The contamination rate was 5%, 7%, 12% and 18% respectively.It is concluded that sputum should not be stored at room temperature for longer than 3 days for culture but it can be stored for 4 weeks without any loss of smear -positivity.     

Microcalorimetric studies of human platelet metabolism at rest. Influence of pH, temperature, cell concentration, preparation methods and storage.

Heat production in human platelets has been measured under different conditions of pH, temp., cell concentration, preparation and storage time. The heat effect was found to increase linearly in the pH range 7.00-7.95, by 20% per pH unit. The temp. coefficient for the heat effect was determined to be Q10 = 2.0 for the temp. interval 32-42 degrees C. Heat production per cell was not significantly affected by variations in cell concentration, or by storage for several hours at room temp. When citrate replaced heparin as anticoagulant significantly higher heat effect values were found.     

An evaluation of the stability of factor VIII inhibitors in plasma and plasma dried on filter paper discs stored at room temperature

The transportation of plasma specimens to specialized haemophilia centre laboratories for anti-factor VIII inhibitor titre determination is often necessary. The routine method of transporting frozen specimens on dry ice is limited by its cost and need for special handling. The present study was undertaken to evaluate the effect of storing specimens at room temperature on the FVIII inhibitor titre determinations using the Bethesda assay. Specimens stored both in liquid phase as well as adsorbed onto filter paper discs were studied. The results of the present study demonstrate that plasma specimens stored for up to 2 weeks at room temperature, either in liquid phase or adsorbed onto filter paper, yield equivalent measures of FVIII inhibitor titres using the Bethesda assay to plasma specimens stored frozen at -70 degrees C. Plasma specimens dried on filter paper discs and stored at room temperature offers a reliable, more practical and less expensive alternative to frozen plasma as a means of transport to specialized referral laboratories for analysis of anti-FVIII titres.     

Stability of plasma concentrations of N and C terminal atrial natriuretic peptides at room temperature.

BACKGROUND: Plasma concentrations of atrial natriuretic peptide (ANP) are increased in patients with ventricular dysfunction and could have a diagnostic role in heart failure. ANP may be unstable after collection, however, limiting any practical diagnostic role. METHODS: Blood samples were obtained from 18 patients with various conditions. Aliquots were either processed optimally or kept as blood or plasma at room temperature for 6-72 h before processing. RESULTS: Concentrations of C-terminal ANP were lower in specimens kept as blood for 24 and 72 h (mean difference from control -43% and -76%, respectively, (P < 0.001) but N-terminal ANP (extracted) seemed to be stable under all conditions studied (-2% at 24 h and -7% at 72 h, not significant). CONCLUSIONS: N-terminal ANP (extracted) is stable and potentially has a role in the diagnosis of heart failure in routine clinical practice.     

重庆市近三年空气湿度、PM2.5及气温水平对老年呼吸系统疾病的影响

近年来,随着全球气候异常变化以及极端天气气候事件的明显增多,主要由颗粒物引发的雾霾天气次数在全国范围内发生频率不断升高,空气质量对呼吸系统疾病的影响也成为了现阶段研究的一个热点问题[1-3]。研究显示,颗粒物尤其是细颗粒物PM2.5可造成机体呼吸系统损害以及免疫系统破坏,从而诱发心脑血管疾病或呼吸系统疾病等,并导致患者的发病率和病死率增加[4-6]。本文对重庆市近三年空气湿度以及空气PM2.5水平进行分析,旨在研究其对老年呼吸系统疾病的影响,现报道如下。     

基于核酸预混室温储运技术的荧光定量PCR快速检测鼠疫耶尔森氏菌

目的 实现荧光定量PCR技术在鼠疫现场和基层的应用。方法 本试验将已建立的基于核酸预混室温储运技术的荧光定量PCR方法应用于我国各鼠疫疫源地野生菌株的检测,进行特异性评价。选取分布于我国境内不同鼠疫疫源地野生鼠疫耶尔森氏菌株、鼠疫减毒菌株、耶尔森菌属近缘菌株假结核菌及小肠结肠炎菌进行荧光定量PCR检测。结果 55株鼠疫耶尔森氏菌及鼠疫减毒菌株扩增阳性,假结核耶尔森氏菌、小肠结肠炎耶尔森氏菌无阳性扩增,冻干试剂在室温25 ℃和37 ℃条件下可保存6个月,敏感性与冷冻保存无差异,核酸扩增诊断可在1 h内完成。结论 应用基于核酸预混室温储运技术的荧光定量PCR方法对我国各鼠疫疫源地55株鼠疫耶尔森氏菌检测呈现高度特异性,本试验冻干试剂具有可室温保存、便于运输、检测结果精准、快速等特点,具有较好的鼠疫现场应用前景。     

Advanced oxidation protein products in plasma: stability during storage and correlation with other clinical characteristics

Proteins are susceptible to free radical damage. We measured advanced oxidation protein products (AOPP) in the plasma of 56 hospitalised patients. Concentrations of AOPP were expressed as chloramine-T equivalents by measuring absorbance in acidic conditions at 340 nm in the presence of potassium iodide. We also determined erythrocyte sedimentation rate (ESR), circulating urea, creatinine, glucose, uric acid, electrolytes, lipids, total proteins and fractions and fibrinogen. Twenty-four samples were processed both immediately and after 7, 15, 30, 90, 180 and 438 days of storage at both at −20°C and −80°C (aliquots were frozen and thawed only once) to evaluate AOPP stability. The remaining 32 samples were also processed for thiobarbituric-acid-reactive substances (TBARS). Mean AOPP concentration in all 56 patients was 48.3±37.2 μM. Mean basal concentration of AOPP in the 24 plasma samples (55.0±47.1 μM) showed no significant change at each intermediate determination, yet significantly increased after 438 days of storage both at −80°C (96.6±83.2, p<0.01) and, markedly, at −20°C (171.3±94.6, p<0.001). TBARS concentration was 1.59±:0.65 μmol/l. Multiple regression analysis evidence that AOPP concentration was positively correlated (multiple r=0.62, p<0.001) with serum urea and triglycerides, but negatively correlated with patient age (indeed, serum albumin and total proteins decreased with increasing age, r=0.3, p<0.05). TBARS concentration was associated with ESR and serum glucose (multiple r=0.73, p<0.001), yet positively with AOPP (r=0.39, simple p<0.05). We conclude that AOPP remain stable during sample storage both at −20°C and −80°C for 6 months. Renal failure and hypertriglyceridemia probably enhance the in vivo process of AOPP formation. Oxidative damage as measured by TBARS may be increased because of exposure to hyperglycemia causing nonenzymatic glycation of plasma proteins. Received: 14 March 2001 / Accepted in revised form: 13 November 2001     

Computerized acquisition and elaboration of clinical data in Rheumatology during ten years: state of art and prospectives

The well known complexity to collect the clinical data of patients and in particular in the area of rheumatology push us to develop a computerized clinical chart in order to facilitate the classification, evaluation and monitoring of these patients. The proposed computerized clinical chart is easy to use but at the same time is a very potent tool that allow the clinicians to organize the classic rheumatological pathologies as well as the more complexes or even rare. The proposed clinical chart is based on a relational database (FileMaker Pro 5.0v1) available for both the actual operative systems implemented on personal computers (Windows and Macintosh); this allow the full compatibility among the two systems, the possibility of exchanging data without any loss of information. The computerized clinical chart is structured on modules for specific pathologies and for homogeneous groups of illnesses. Basically the modules are defined correlated files of data for a specific pathology but that can be used also as a common pool for different pathologies. Our experience, based on ten years of use, indicates in the computerized rheumatological clinical chart an indispensable tool for rheumatologists with a real friendly use.     

Filamentary microstructure and linear temperature dependence of normal state transport in optimized high temperature superconductors

A filamentary model of "metallic" conduction in layered high temperature superconductive cuprates explains the concurrence of normal state resistivities (Hall mobilities) linear in T (T-2) with optimized superconductivity. The model predicts the lowest temperature T0 for which linearity holds and it also predicts the maximum superconductive transition temperature Tc. The theory abandons the effective medium approximation that includes Fermi liquid as well as all other nonpercolative models in favor of countable smart basis states.     

Oestrone, oestradiol-17beta and oestriol levels in human foetal plasma during gestation and at term

Marked rises in both unconjugated and sulphoconjugated estrone, estradiol-17-beta and estriol were observed in human fetal plasma between midgestation and term. Significant arterio-venous differences were found in the umbilical cord plasma. No consistent arterio-venous differences were found in the umbilical cord plasma. This indicates that all 3 estrogens are secreted from the placenta into the fetal circulation in the unconjugated form. Mean unconjugated estrogen (estrone + estradiol-17-beta + estriol) levels rose from 22.7 ng/ml at 17-20 weeks of gestation to 108.9 ng/ml at term in umbilical venous plasma and from 4.3 ng/ml to 23.3 ng/ml in umbilical arterial plasma. This represents a secretion rate of approximately 30 mg estrogen/day into the umbilical vein at term. Mean estrogen sulphate levels rose from 128 ng/ml to 313 ng/ml in the cord plasma during the same period. Of the 3 estrogens measured, estriol was quantitatively the major estrogen in fetal plasma. It consistently represented about 78% of the unconjugated fraction and 95% of the sulphate fraction at all stages of gestation. The method of delivery did not have a significant effect on the estrogen levels in uncomplicated pregnancies. Similar estrogen levels were found in fetal heart blood after either hysterotomy at spontaneous abortion at 16-20 weeks of gestation, and no significant differences were found for estrogen levels in cord plasma after elective Caesarean section at 38-39 weeks when compared with estrogen levels after normal delivery at term. A significant rise in fetal unconjugated estrogens at a time when fetal corticosteroids are increasing may be of physiological importance for fetal maturation in women.