bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Carbapenem Antibiotics on Plasma Concentrations of Valproic Acid
Authors: Mancl Erin E , Gidal Barry E 
Published: November 2009

Objective:To critically evaluate the mechanisms of the interaction between valproic acid and carbapenem antibiotics.Data Sources:A PubMed search (January 1971–June 2009) was performed to identify literature on the interaction between valproic acid and carbapenem antibiotics. Additional references were identified through review of bibliographies of identified articles.Study Selection and Data Extraction:Data on the mechanisms of the interaction between valproic acid and carbapenem antibiotics were extracted from identified references that were published in English.Data Synthesis:Valproic acid plasma concentrations fall markedly during concomitant administration with carbapenem antibiotics due to a combination of absorption, distribution, and metabolism mechanisms. Carbapenems appear to inhibit the intestinal transporter of valproic acid, thereby reducing absorption of orally administered valproic acid. In vivo experiments in rats demonstrate a 57% reduction in absorption of orally administered valproic acid in the presence of imipenem. Followup studies in Caco-2 cells suggest that the inhibition probably occurs at the basolateral membrane. In addition, enterohepatic recycling of valproic acid may be diminished due to carbapenem activity against gut flora producing β-glucuronidase. When rabbits and rats were given intravenous valproic acid-glucuronide, the glucuronide metabolite of valproic acid, 50–90% of the conversion back into valproic acid was inhibited in the presence of a carbapenem. An increase in erythrocyte distribution of valproic acid has also been observed in the presence of carbapenems. After intravenous administration of a carbapenem and valproic acid, valproic acid plasma concentrations fell in the presence of a carbapenem, yet whole blood concentrations of valproic acid did not change significantly. Follow-up studies suggest that the mechanism of this distribution shift is that multidrug resistance proteins on adenosine triphosphate–binding cassette transporters on erythrocyte membranes are inhibited by carbapenems. Thus, valproic acid is not effluxed out of the erythrocytes. Finally, carbapenems may enhance glucuronidation of valproic acid by increasing UDP-glucuronic acid levels. In rats, UDP-glucuronic acid levels increased by 1,7-fold in the presence of panipenem, which was proportionate to the increase in valproic acid-glucuronide formation.Conclusions:Published data demonstrate a serious and complex interaction between valproic acid and carbapenem antibiotics. Coadministration should be avoided, but if no other antibiotic therapies exist, it is imperative to monitor valproic acid concentrations more frequently. Clinicians should anticipate higher doses of valproic acid to maintain therapeutic serum concentrations during coadministration and subsequent dose reductions upon discontinuation of the carbapenem antibiotic.
An Updated Focused Review of Dexmedetomidine in Adults
Authors: Gerlach Anthony T , Murphy Claire V , Dasta Joseph F 
Published: November 2009

Objective: To evaluate recent comparative studies regarding the safety and efficacy of dexmedetomidine in adults. Data Sources: Articles evaluating safety and efficacy of dexmedetomidine were identified from an English-language MEDLINE search (1996–July 2009), with a focus on data published since our previous review in 2007 to the present. MeSH terms included dexmedetomidine, medetomidine, α2:-agonist, and sedation. References from selected articles were also reviewed for additional material. Study Selection and Data Extraction: Experimental and observational English-language studies that focused on the efficacy, safety, and pharmacoeconomics of dexmedetomidine in humans were selected. Data Synthesis: Dexmedetomidine is an α2-agonist used for sedation during procedures and in critical illness. Compared with placebo, use of dexmedetomidine during procedures was associated with decreased use of rescue midazolam and a similar degree of sedation compared with various agents used during surgery or for procedures. Use of long-term (>24 h) dexmedetomidine sedation is comparable to sedation with benzodiazepines in critically ill patients. In a Phase 4 study, dexmedetomidine was safe in dosages up to 1.4 μg/kg/hour for greater than 24 hours and did not produce rebound tachycardia or hypertension when abruptly discontinued. One small randomized controlled trial demonstrated decreased incidence of delirium, the primary endpoint, with dexmedetomidine compared with midazolam or propofol for sedation after cardiac valve surgery. Many, but not all, studies suggest that dexmedetomidine has a promising role in prevention and treatment of delirium in critically ill patients when delirium was studied as a secondary endpoint. Conclusions: Dexmedetomidine is an alternative for procedural sedation and can be used long-term (>24 h) in critically ill patients, in dosages up to 1.5 μg/kg/hour. More studies are needed to better define the role of dexmedetomidine in preventing and treating delirium.
β-Adrenergic Antagonists in Hypertension: A Review of the Evidence
Authors: Warmack T Scott , Estes Mark A , Heldenbrand Seth , Franks Amy M 
Published: November 2009

Objective: To evaluate the effects of β-adrenergic antagonist therapy on cardiovascular and cerebrovascular outcomes in the treatment of hypertension. Data Sources: Literature searches were conducted using MEDLINE (1966–August 2009), International Pharmaceutical Abstracts (1970–August 2009), and Cochrane Database of Systematic Reviews (until third quarter 2009) to locate clinical trials and meta-analyses comparing β-blocker therapy with placebo or other antihypertensive agents in patients with hypertension. Bibliographies from relevant research and review articles were reviewed for additional references. Study Selection and Data Extraction: All English-language articles identified from the data sources were reviewed. Articles describing original research with cardiovascular or cerebrovascular outcomes and/or death as either primary or secondary endpoints were included. Articles describing the use of β-blocker therapy for conditions other than hypertension were not included, Data Synthesis: Five placebo-controlled studies and 10 active-controlled studies were reviewed. In addition, 11 meta-analyses were evaluated. Placebo-controlled trials of β-blockers in hypertension provide evidence of reduced risk for stroke, cardiovascular events, and heart failure. Only 2 studies comparing β-blockers with other antihypertensives found significant benefit with β-blockers. However, the majority of meta-analyses comparing β-blockers with other antihypertensive agents show increased risk for stroke with β-blockers, and some data suggest increased risk for cardiovascular events and all-cause mortality. The majority of data results from studies of atenolol, and many studies employed combination antihypertensive therapies, which often included thiazide diuretics. Conclusions: Overall, data supporting β-blockers as preferred therapy in hypertension are inadequate. Although most negative cardiovascular and cerebrovascular outcomes of β-blockers were associated with atenolol therapy, data supporting other β-blockers in hypertension are lacking.
Probable Drug Interaction Between Warfarin and Hormonal Contraceptives
Authors: Zingone Michelle M , Guirguis Alexander B , Airee Anita , Cobb Diana 
Published: November 2009

Objective: To report a single patient case that presented with a probable drug interaction between warfarin and 3 methods of hormonal contraceptives, as assessed by the Horn Interaction Probability Scale. Case Summary: A 33-year-old female patient required long-term anticoagulation following an aortic valve replacement. While taking warfarin (38.5 mg weekly), she transitioned from a monophasic combined oral contraceptive (ethinyl estradiol plus norethindrone) to an implantable progestin-only contraceptive (etonogestrel) on the advice of her cardiologist. Nineteen days following etonogestrel implant insertion, her international normalized ratio (INR) decreased to 1.8 and required a 55.8% warfarin dose increase (resulting dose of 60 mg weekly). Within 10 months, the patient elected to have the implant removed due to vaginal bleeding. Nine days following removal of etonogestrel, she experienced a transient INR increase to 6.5. Her INR returned to within goal range after her warfarin dose was decreased to 55.5 mg weekly. After using barrier methods of contraception for 48 days, she initiated an oral progestin-only contraceptive (norethindrone). Further warfarin dose adjustments were made, resulting in a weekly warfarin dose of 53.5 mg. Thirty-nine days after initiation of oral norethindrone, she elected to discontinue use due to vaginal bleeding and no longer uses hormonal contraceptive methods. No further adjustments to her warfarin dose were warranted. Discussion: The increased warfarin requirement observed in this patient may have been a result of multiple factors. Based on a literature review, we hypothesize that the predominant mechanism of interaction was ethinyl estradiol inhibition of CYP1A2 and 2C19. Conclusions: We recommend that further in vivo studies be completed to definitively identify the mechanism of the interaction. It is necessary to intensify warfarin monitoring upon initiation or alteration of hormonal contraceptives.
Hyperchloremic Metabolic Acidosis Due to Deferasirox in a Patient with Beta Thalassemia Major
Authors: Papadopoulos Nikolaos , Vasiliki Aresti , Aloizos Georgios , Tapinis Petros , Kikilas Athanasios 
Published: November 2009

OBJECTIVE To report a case of hyperchloremic metabolic acidosis in a patient with beta thalassemia major secondary to treatment with deferasirox due to iron overload. CASE SUMMARY A 58-year-old white female with beta thalassemia major was admitted with fever, fatigue, abnormal liver function test results, and hyperchloremic metabolic acidosis (lactate dehydrogenase 494 U/L, aspartate aminotransferase 167 U/L, alanine aminotransferase 250 U/L, γ-glutamyl transferase 102 U/L, total bilirubin 3.79 mg/dL, direct bilrubin 2.37, potassium 3.3 mEq/L, PO2 81.4 mm Hg, PCO2 29.4 mm Hg, HCO3 16 mEq/L, pH 7.35, chloride 116 mEq/L, anion gap 7.5 mEq/L). Twenty-five days before admission the patient decided to discontinue treatment with deferoxamine for chronic iron overload and continue treatment with oral deferasirox 1500 mg/day. Despite extended clinical and laboratory examination, no obvious cause of fever, hepatitis, or hyperchloremic metabolic acidosis was revealed. Diagnosis was compatible with tubular dysfunction, drug-induced hepatitis, and hypersensitivity reaction due to deferasirox. All pathological findings were fully reversible and our patient had an excellent outcome. DISCUSSION The presence of tubular dysfunction should be considered in any patient with otherwise unexplained hyperchloremic metabolic acidosis. In our patient, other potential causes of metabolic hyperchloremic acidosis were ruled out. Toxic effects of deferasirox are probably caused by chelation of mitochondrial iron, leading to adenosine triphosphate depletion in tubular epithelial cells. Use of the Naranjo probability scale revealed that the adverse reaction was probable. CONCLUSIONS Kidney toxicity may be a major issue in the management of patients receiving deferasirox. Our case indicates a potential risk of renal toxicity with the presence of tubular dysfunction and hyperchloremic metabolic acidosis in patients undergoing treatment with deferasirox.
Physiological responses of polar benthic algae to ultraviolet radiation
Authors: Karsten Ulf , Wulff Angela , Roleda Michael Y. , Müller Ruth , Steinhoff Franciska S. , Fredersdorf Jana , Wiencke Christian 
Published: November 2009

AbstractStratospheric ozone depletion and the concomitant increase in ultraviolet (UV) B radiation at the earth's surface represent major threats to polar marine ecosystems. Whereas in coastal rocky shore environments macroalgae constitute an assemblage of particular significance to ecosystem function, benthic diatoms dominate microphytobenthic assemblages, which typically grow on shallow-water sediments as highly productive and stabilising phototrophic biofilms. This review summarises present knowledge on how UV radiation affects the physiology of polar benthic algae with an emphasis on cell biological and structural changes, molecular targets and repair mechanisms, induction of reactive oxygen species and antioxidative strategies, photosynthesis and growth, photoprotective mechanisms, interactive effects between UV radiation and other abiotic factors, and finally ecological consequences. Although available data indicate that there are specific characteristics and adaptations in polar benthic micro- and macroalgae that explain their ecological success and limits under environmentally extreme conditions, much more research is needed to understand the underlying mechanisms. In particular, more ecosystem approaches and studies on interactive effects, as well as modern genomic, proteomic and metabolomic approaches could help address all open questions and depict a more holistic picture.
Freezing tolerance and photosynthetic performance of polar seaweeds at low temperatures
Authors: Becker Susanne , Walter Bettina , Bischof Kai 
Published: November 2009

Abstract
Organisms populating benthic shallow water systems of both polar regions are adapted to a particularly harsh environment. We studied effects of freezing and the combination of high light intensities and low water temperatures on photosynthesis of key macroalgal species from the Arctic intertidal (Fucus distichus) and Antarctic subtidal (Palmaria decipiens). Photosynthetic activity of F. distichus specimens was monitored during the freezing process; there was a marked decrease in quantum yield with decreasing temperatures, and a rapid recovery as soon as temperatures increased again. Thus, under the experimental conditions tested, no indication of photodamage was found. Specimens of Palmaria were exposed to a combination of high light intensities and low water temperatures. A persistent impairment of photosynthetic activity occurred at 0°C at light intensities of 400 μmol photons m-2 s-1. In all treatments, there was a decreasing ratio of phycobiliproteins to chlorophyll a. Overall, the two studies provide baseline data for interpreting physiological responses of two important macroalgal species in an extreme environment, the polar coastal ecosystem.
Notes on the systematics and biogeographical relationships of Antarctic and sub-Antarctic Rhodophyta with descriptions of four new genera and five new species
Authors: Hommersand Max H. , Moe Richard L. , Amsler Charles D. , Fredericq Suzanne 
Published: November 2009

Abstract
The present study consolidates knowledge of Antarctic marine Rhodophyta, incorporating new observations from the Antarctic Peninsula. Descriptions of four new genera and five new species are included: Rhodokrambe laingioides (Delesseriaceae), Leniea lubrica, Austropugetia crassa, Varimenia macropustulosa R.L. Moe gens. et spp. nov., and Nereoginkgo populifolia R.L. Moe sp. nov. (Kallymeniaceae). The new combination Trematocarpus
antarcticus (Hariot) Fredericq et R.L. Moe is proposed for Kallymenia antarctica Hariot (Sarcodiaceae). Phylogenetic relationships are suggested based primarily on unpublished molecular analyses of rbcL sequences provided by S.-M. Lin, S. Fredericq, P.W. Gabrielson, D.W. Freshwater and M. Volovsek. Habitat and environmental conditions are incorporated from the field studies of R.L. Moe and C.D. Amsler. A preliminary assessment is made of the biogeographic relationships between Antarctic red algae and those found in related temperate regions based on a summary of tectonic and climatic reconstructions of the Cenozoic Southern Ocean and the unpublished phylogenetic studies of Hommersand and his associates.
The abiotic environment of polar marine benthic algae
Authors: Zacher Katharina , Rautenberger Ralf , Hanelt Dieter , Wulff Angela , Wiencke Christian 
Published: November 2009

Abstract
Due to different oceanographic and geological characteristics, benthic algal communities of Antarctica and the Arctic differ strongly. Antarctica is characterized by high endemism, whereas in the Arctic only a few endemic species occur. In contrast to the Antarctic region, where nutrient levels never limit algal growth, nutrient levels in the Arctic region are depleted during the summer season. Both regions have a strongly seasonally changing light regime, fortified by an ice covering throughout the winter months. After months of darkness, algae are suddenly exposed to high light caused by the breaking up of sea ice. Simultaneously, harmful ultraviolet radiation (UVR) enters the water column and can significantly affect algal growth and community structure. In the intertidal zone, fluctuations of temperature and salinity can be very large. Ice scours can further influence growth and settlement of intertidal algae. The subtidal zone offers a more stable habitat than the intertidal, permitting the growth of larger perennial algae and microbial mats. Polar regions are the areas most affected by global climate change, i.e., glacier retreat, increasing temperature and sedimentation, with as yet unknown consequences for the polar ecosystem.
Inverse relationship between serum high density lipoprotein and negative syndrome in antipsychotic-naive schizophrenia
Authors: Venkatasubramanian Ganesan , Arasappa Rashmi , Rao Naren P. , Behere Rishikesh V. , Kalmady Sunil , Gangadhar Bangalore N. 
Published: November 2009

Abstract

Background: Recent literature suggests a role for apolipoprotein L (apoL) aberrations in the pathogenesis of schizophrenia. ApoL is almost exclusively associated with apolipoprotein A-I in high-density lipoproteins (HDLs). The objective of this study was to examine the correlation between symptom scores and serum HDL in antipsychotic-naive schizophrenia patients.

Methods: In this cross-sectional study, 60 antipsychotic-naive schizophrenia patients were systematically examined for their symptom scores, with good inter-rater reliability. Concurrently, an overnight fasting serum lipid profile from these patients was assessed.

Results: Serum HDL had a significant inverse correlation with a total negative syndrome score (ρ=−0.43; p=0.001).

Conclusions: The study observation supports the potential role for HDL abnormalities in the genesis of negative symptoms in schizophrenia.
Clin Chem Lab Med 2010;48:95–8.
Differences in serum potassium concentrations between Chinese, Indians and Malays
Authors: Hawkins Robert C. 
Published: November 2009

Abstract

Background: It has been suggested that potassium concentrations may vary between different geographical regions, possibly reflecting ethnic differences in potassium status. This study compared the serum potassium concentrations of three Asian ethnicities in a single geographical location.

Methods: Details of simultaneous serum potassium, creatinine, cholesterol, triglyceride and serum index measurements for samples from polyclinics and health screening were extracted for multivariable linear regression. Haemolysed and duplicate patient samples were excluded. Separate analysis was performed based on measurement platform (Roche or Beckman-Coulter) and patient location.

Results: Eighty-five thousand nine hundred and ninety-seven records met the inclusion criteria. When controlled for age, gender, serum creatinine, cholesterol and triglyceride, the average serum potassium concentration in Indians was 0.13–0.16 mmol/L higher than in Malays, who in turn had average serum potassium concentrations 0.05–0.06 mmol/L higher than Chinese when controlled for age, gender, serum creatinine, cholesterol and triglyceride concentrations. For patients undergoing health screening, the average serum potassium concentration in Indians and Malays was 0.12 mmol/L higher than in Chinese.

Conclusions: Chinese individuals have lower average serum potassium concentrations than Indians and Malays. This may have clinical implications in relation to the high occurrence of thyrotoxic hypokalaemic paralysis and the aetiology of sudden unexplained death syndrome (SUDS) in Asians.
Clin Chem Lab Med 2010;48:105–8.
Analytical performance of the serum free light chain assay
Authors: Briand Pierre-Yves , Decaux Olivier , Caillon Hélène , Grosbois Bernard , Le Treut André , Guenet Lucienne 
Published: November 2009

Abstract

Background: The Freelite™ system for nephelometric or turbidimetric measurement of serum free light chains (FLCs) has been available since 2001. It has been valuable for the management of patients with oligosecretory myeloma, light chain myeloma and AL amyloidosis. However, there are several limitations of the method. The goal of this study was to evaluate the analytical performance of the FLC assay.

Methods: Titrated controls and clinical serum specimens were used to determine precision and post-dilution recovery.

Results: As reported elsewhere, we found that the assay had several limitations, including poor post-dilution linearity and overestimation by nephelometry.

Conclusions: These data demonstrate that the results of the FLC assay must be interpreted jointly by the clinician and the biologist, taking into account the individual patient's clinical and biological characteristics.
Clin Chem Lab Med 2010;48:73–9.
A study on the stability of urinary free catecholamines and free methyl-derivatives at different pH, temperature and time of storage
Authors: Roberts Norman B. , Higgins Gerald , Sargazi Mansour 
Published: November 2009

AbstractBakground:The goal of our study was to test the relative stability of urine, unconjugated, free catecholamines and the methyl derivatives. We measured the change in concentrations in commercially available urines after storage at various pH values, temperatures and time, from days up to 10 weeks.Methods:Samples of commercial control urines were adjusted to pH 2.0, 4.0, 6.0 and 8.0 and aliquots stored at ambient temperature (20–26°C), 4°C and –18oC. The free catecholamines (cats) and the free methyl derivatives (mets) were measured after 1, 2, 3 and 6 days and 1, 2, 3 and 10 weeks using the automated sample trace enrichment dialysis (ASTED) procedure with reversed phase ion pair high performance liquid chromatography (HPLC) and coulometric detection.Results:Free catecholamines were relatively stable, with <15% loss of concentration, when stored at pH 6.0 or less for at least 4 days and up to 10 weeks at pH 2.0 at either 4oC or –18oC. At pH 8.0, the concentration fell to <60% after 48 h and at a pH of 6.0 or 8.0, up to 90% was lost within the first week at 4oC and 25oC. More than 40% of free normetadrenaline and metadrenaline were lost after 1–2 weeks when stored at 20–25oC and pH 8.0. After 10 weeks at pH 4.0, 6.0 and 8.0, up to 90% loss was observed at 25oC. Free cats were stable at pH 2.0 and 4.0 at –18oC and the free mets were stable at –18oC over the entire time period studied and at all pHs.Conclusions:In the analysis of free catecholamine and the free methyl derivatives, urine samples should be acidified to a pH range 2.0–3.0 to ensure stability and hence the correct analysis.Clin Chem Lab Med 2010;48:81–7.
Counting Determinants of Fibonacci–Hessenberg Matrices Using LU Factorizations
Authors: Li Hsuan-Chu , Chen Young-Ming , Tan Eng-Tjioe 
Published: November 2009

AbstractWe investigate the LU factorizations of Fibonacci–Hessenberg matrices which enable us to find the determinant of a new class of Hessenberg matrices and yield a better computation of determinants of the old ones.