In vitro drug screening models derived from different PC12 cell lines for exploring Parkinson's disease based on electrochemical signals of catecholamine neurotransmitters.

Gold nanostructures and a Nafion modified screen-printed carbon electrode (Nafion/AuNS/SPCE) were developed to assess the cell viability of Parkinson's disease (PD) cell models. The electrochemical measurement of cell viability was reflected by catecholamine neurotransmitter (represented by dopamine) secretion capacity, followed by a traditional tetrazolium-based colorimetric assay for confirmation. Due to the  capacity to synthesize, store, and release catecholamines as well as their unlimited homogeneous proliferation, and ease of manipulation, pheochromocytoma (PC12) cells were used for PD cell modeling. Commercial low-differentiated and highly-differentiated PC12 cells, and home-made nerve growth factor (NGF) induced low-differentiated PC12 cells (NGF-differentiated PC12 cells) were included in the modeling. This approach achieved sensitive and rapid determination of cellular modeling and intervention states. Notably, among the three cell lines, NGF-differentiated PC12 cells displayed the enhanced neurotransmitter secretion level accompanied with attenuated growth rate, incremental dendrites in number and length that were highly resemble with neurons. Therefore, it was selected as the PD-tailorable modeling cell line. In short, the electrochemical sensor can be used to sensitively determine the biological function of neuron-like PC12 cells with negligible destruction and to explore the protective and regenerative impact of various substances on nerve cell model.

Preparation and characterization of micro/nanocellulose reinforced PVDF/wood composites.

Polyvinylidene fluoride (PVDF) is commonly used in the chemical, electronic, and petrochemical industries because of its chemical and physical attributes. This study aimed to make novel PVDF-based composite with a high loading of silanized wood powder and micro/nanocellulose fibers, where glycerol acts as both a dispersant and a plasticizer all-in-one composite application for the first time. The purpose was also extended to systematically investigate their mechanical properties and melt flow. Results have demonstrated the efficiency of utilizing the cellulose fibers in bio-composites. With the addition of 30 wt% of filling materials, When the content of silanized cellulose fibers in glycerol dispersion is 25 wt%, the flexural strength and tensile strength reach the maximum value 72.30 MPa and 52.28 MPa. The experimental results indicate that silanized micro/nanocellulose fiber-reinforced PVDF/wood composites are a promising composite formula to help improve performance and reduce costs. It is an excellent example of utilizing biomass resources as a renewable/recyclable, sustainable and low-cost material to reduce the use of petroleum-based polymer, and improve the mechanical properties of composites.

Transvaginal repair of anterior vaginal wall prolapse with polyvinylidene fluoride (PVDF) mesh: an alternative for previously restricted materials?

INTRODUCTION AND HYPOTHESIS: To study the mid-term safety and functional outcomes of transvaginal anterior vaginal wall prolapse repair using polyvinylidene fluoride (PVDF) mesh (DynaMesh®-PR4) by the double trans-obturator technique (TOT). METHODS: Between 2015 and 2020, we prospectively included women with symptomatic high-stage anterior vaginal wall prolapse with or without uterine prolapse or stress urinary incontinence (SUI) in the study. The patients underwent transvaginal repair of the prolapse using PVDF mesh in two medical centers. We followed all patients for at least 12 months. We recorded the characteristics of vaginal and sexual symptoms, urinary incontinence, and prolapse stage pre- and postoperatively using International Consultation on Incontinence Questionnaire-Vaginal Symptoms (ICIQ-VS), International Consultation on Incontinence Questionnaire-Urinary Incontinence-Short Form (ICIQ-UI-SF), and Pelvic Organ Prolapse Quantification (POP-Q) system, respectively. RESULTS: One hundred eight women were included in the final analysis with a mean follow-up time of 34.5 ± 18.6 months. The anatomical success was achieved in 103 (95.4%) patients. There was a significant improvement in patients' vaginal symptoms, urinary incontinence, and quality of life scores postoperatively (p < 0.0001). Only six patients (5.5%) had mesh extrusion, five of whom were managed successfully. The total rates of complications and de novo urinary symptoms were 21.3% and 7.4%, respectively. Significant pain was reported in 17 cases (15.7%). CONCLUSION: Our findings show that using PVDF mesh in the double TOT technique for anterior vaginal wall prolapse repair is a safe procedure with high anatomic and functional success rates and acceptable complication rates in mid-term follow-up.

Quantification of Uncoupled Spin Domains in Spin-Abundant Disordered Solids.

Materials often contain minor heterogeneous phases that are difficult to characterize yet nonetheless significantly influence important properties. Here we describe a solid-state NMR strategy for quantifying minor heterogenous sample regions containing dilute, essentially uncoupled nuclei in materials where the remaining nuclei experience heteronuclear dipolar couplings. NMR signals from the coupled nuclei are dephased while NMR signals from the uncoupled nuclei can be amplified by one or two orders of magnitude using Carr-Meiboom-Purcell-Gill (CPMG) acquisition. The signal amplification by CPMG can be estimated allowing the concentration of the uncoupled spin regions to be determined even when direct observation of the uncoupled spin NMR signal in a single pulse experiment would require an impractically long duration of signal averaging. We use this method to quantify residual graphitic carbon using 13C CPMG NMR in poly(carbon monofluoride) samples synthesized by direct fluorination of carbon from various sources. Our detection limit for graphitic carbon in these materials is better than 0.05 mol%. The accuracy of the method is discussed and comparisons to other methods are drawn.

Nafion-stabilized black phosphorus nanosheets-maltosyl-ß-cyclodextrin as a chiral sensor for tryptophan enantiomers.

In this work, we have fabricated nafion (NF) stabilized black phosphorus nanosheets (BPNSs) and 6-O-α-maltosyl-ß-cyclodextrin (G2-ß-CD) composite (BPNSs-G2-ß-CD) as novel electrochemical sensoring platform for chiral recognition of tryptophan (Trp) enantiomers. BPNSs-G2-ß-CD composite modified glassy carbon electrode (BPNSs-G2-ß-CD/GCE) was further coated with NF which served as a protective film to immobilize BPNSs-G2-ß-CD on the electrode surface to achieve high stability. Under the optimum conditions, the oxidation peak current ratio of L-Trp to D-Trp (IL/ID) and the difference between the peak potential (ΔEp = ED - EL) were observed to be 1.49 and 20 mV at NF/BPNSs-G2-ß-CD/GCE by square wave voltammetry (SWV). In addition, a linear calibration curve could be obtained for peak current versus Trp enantiomers in the concentration range 0.01-1.00 mM with detection limits of 1.07 µM and 1.71 µM for L-Trp and D-Trp (signal-to-noise ratio of 3, S/N = 3), respectively. The chiral recognition mechanism was also proposed, and the intermolecular hydrogen bonding interactions as well as the hydrophobic-cavity-triggered embedding effect dominated the effective chiral recognition. Moreover, the proposed NF/BPNSs-G2-ß-CD/GCE showed excellent stability, good reproducibility and anti-interference capability. Therefore, the designed chiral sensor is expected to be practically applied for the sensitive recognition of Trp enantiomers in real samples.

Long-range interactions keep bacterial cells from liquid-solid interfaces: Evidence of a bacteria exclusion zone near Nafion surfaces and possible implications for bacterial attachment.

Hydrophilic surfaces of both abiotic and biological origin have been shown to bear particle-exclusion zones as large as hundreds of micrometers at liquid-solid interfaces. Here we present the first systematic investigation and evidence for bacteria-free exclusion zones for several bacterial strains, including pathogens associated with hospital infections and/or foodborne outbreaks: Staphylococcus aureus, Escherichia coli O157:H7, and Listeria monocytogenes. Tests were carried out both in a phosphate buffer, as well as triptic soy broth (TSB) of high ionic strength. Bacterial cell density distribution at the Nafion-liquid interface was visualized using confocal laser scanning microscopy. A robust image analysis method was developed to generate a profile of cell concentration near the interface and quantify EZ size. Results revealed an exclusion zone (EZ) of 40-60µm and a transition zone (TZ) of 40-80µm for bacterial cells suspended in tryptic soy broth. There were no statistical differences in the size of EZ and TZ for the bacterial strains tested with the same substrate, but differences existed for different substrates tested, implying a physicochemical underpinning for EZ. In a test conducted with E. coli, cells progressively penetrated EZ over 2days. Furthermore, EZ-bearing Nafion had 80% less biomass accumulation of E. coli over 2days compared to an EZ-less, hydrophilic, smooth aluminum oxide surface. This suggests that EZ may represent the first line of defense, spatially and temporally, against bacteria approaching certain hydrophilic surfaces. These findings could have important implications in developing biofouling-resistant material surfaces for applications sensitive to bacterial attachment and biofilm formation.

Amperometric biosensor based on prussian blue and nafion modified screen-printed electrode for screening of potential xanthine oxidase inhibitors from medicinal plants.

A simple and sensitive amperometric biosensor was developed for the screening of potential xanthine oxidase inhibitors from medicinal plants. This biosensor was prepared by immobilization of xanthine oxidase on the surface of prussian blue modified screen-printed electrodes using nafion and glutaraldehyde. The developed biosensor showed a linear amperometric response at an applied potential of +0.05 V toward the detection of hypoxanthine from 5 µM to 45 µM with a detection limit of 0.4 µM (S/N=3) and its sensitivity was found to be 600 mA M(-1) cm(-2). In addition, the biosensor exhibited a good storage stability. The inhibition of xanthine oxidase by allopurinol was studied under the optimized conditions. The linear range of allopurinol concentration is obtained up to 2.5 µM with an estimated 50% of inhibitionI50=1.8 µM. The developed biosensor was successfully applied to the screening of xanthine oxidase inhibitors from 13 medicinal plants belonging to different families. Indeed, Moroccan people traditionally use these plants as infusion for the treatment of gout and its related symptoms. For this purpose, water extracts obtained from the infusion of these plants were used for the experiments. In this work, 13 extracts were assayed and several of them demonstrated xanthine oxidase inhibitory effect, with an inhibition greater than 50% compared to spectrophotometry measurements that only few extracts showed an inhibition greater than 50%.

A Combined 28-Day Oral Toxicity Study of HFPO-Amidol (CASRN 75888-49-2) With Reproductive/Developmental Toxicity Screening Test in Wistar Han Rats.

HFPO-Amidol (CAS # 75888-49-2) is a new hexafluoropropylene oxide (HFPO)-based intermediate developed as an alternative to longer chain perfluorinated compounds. The repeated-dose toxicity of this material was evaluated in an Organization for Economic Cooperation and Development 422-compliant, 28-day oral exposure study with a concurrent reproductive/developmental toxicity screening test. Wistar rats received doses of 0, 30, 300, or 1000 mg/kg/d by oral gavage. Statistically significant changes in body weight gain of 1000 mg/kg/d females during the postcoitum period were possibly related to treatment but were considered not adverse, given the slight nature of the changes. The lower food consumption of 300 mg/kg/d females during the postcoitum and lactation period was not considered treatment related given the absence of a time- and dose-related trend and because food intake was generally similar to control levels after allowance for body weights. Statistically significant changes in motor activity (total movements and total ambulations) were noted in 1000 mg/kg/d main male and female rats. The changes observed in female rats were considered not treatment related in the absence of a dose-response trend. The higher motor activity of high-dose males was primarily apparent within the first 10 minutes of the 60-minute measurement period and was suggestive of temporary hyperreactivity to a new environment/stimulus. This increased peak motor activity remained present although at an apparent lower magnitude when measured 13 days after withdrawal of treatment. Because the possible toxicological relevance of the temporarily increased motor activity observed in 1000 mg/kg/d males could not be excluded, these changes were considered possibly adverse in nature. No treatment-related or toxicologically relevant effects were noted on the other parental, reproductive, and developmental parameters investigated in this study. The parental systemic no observed adverse effect level (NOAEL) for this study is 300 mg/kg/d (based on increased motor activity in males), while the reproductive and developmental NOAEL is 1000 mg/kg/d.

Ordered mesoporous carbon/Nafion as a versatile and selective solid-phase microextraction coating.

In this study, ordered mesoporous carbon (OMC) with large surface area (1019m(2)g(-1)), uniform mesoporous structure (pore size distribution centering at 4.2nm) and large pore volume (1.46cm(3)g(-1)) was synthesized using 2D hexagonally mesoporous silica MSU-H as the hard template and sucrose as the carbon precursor. The as-synthesized OMC was immobilized onto a stainless steel wire using Nafion as a binder to prepare an OMC/Nafion solid-phase microextraction (SPME) coating. The extraction characteristics of the OMC/Nafion coating were extensively investigated using a wide range of analytes including non-polar (light petroleum and benzene homologues) and polar compounds (amines and phenols). The OMC/Nafion coating exhibited much better extraction efficiency towards all selected analytes than that of a multi-walled carbon nanotubes/Nafion coating with similar length and thickness, which is ascribed to its high surface area, well-ordered mesoporous structure and large pore volume. When the OMC/Nafion coating was used to extract a mixture containing various kinds of analytes, it possessed excellent extraction selectivity towards aromatic non-polar compounds. In addition, the feasibility of the OMC/Nafion coating for application in electrochemically enhanced SPME was demonstrated using protonated amines as model analytes.

Monitoring of rosmarinic acid accumulation in sage cell cultures using laccase biosensor.

INTRODUCTION: A recently developed laccase based biosensor is used for polyphenols determination from in vitro Salvia cultures, the results being expressed as rosmarinic acid equivalent content. OBJECTIVE: The aim of this work was to use a previously developed laccase biosensor for the determination of total phenolic content from in vitro cultivated Salvia, and to support the biosensors further application for the assessment of polyphenols metabolites. METHODOLOGY: The biosensor was constructed by drop casting 3 µL of laccase solution and stabilisation with 0.1 % Nafion solution onto a DropSens carbon screen-printed electrode. Electrochemical measurements were carried out in a 0.1 mol/L phosphate buffer (pH 4.50), the applied working potential being -30 mV versus reference electrode. RESULTS: The response of the biosensor developed was characterised in terms of repeatability, accuracy and precision; the limit of detection was 7.5 × 10(-7) mol/L, the limit of determination was 9.5 × 10⁻7 mol/L, and linear response range for rosmarinic acid was 1 × 10⁻6-10⁻5 mol/L. CONCLUSION: A stable, sensitive and simple biosensor based on laccase-nafion was used for monitoring the total polyphenolic content from two in vitro cultivated plants. The biosensor response was free of electrochemical interferences and of possible interferences from growth media constituents, demonstrating a high sensitivity for rosmarinic acid determination in cell culture suspensions.

Amperometric nitric oxide sensor based on nanoporous platinum phthalocyanine modified electrodes.

This article describes the fabrication of electropolymerized Metallo 4', 4″, 4‴, 4'''' tetra-amine phthalocyanine (poly-MTAPc) modified electrodes for the detection of nitric oxide (NO) in phosphate-buffered saline (PBS) at pH 7.4. A two-step synthetic protocol using a laboratory microwave reactor was adopted to provide three MTAPc complexes bearing different metal centers (M = Cu(2+): CuTAPc, M = Zn(2+): ZnTAPc, and M = Pt(2+): PtTAPc). The MTAPc complexes and the intermediates were characterized by MALDI-TOF mass spectrometry, UV-vis spectroscopy, (1)H NMR spectroscopy, and elemental analysis. The MTAPc products were separately electropolymerized either onto a glassy carbon (GC) electrode as a thin-film or within the pores of Anodisc nanoporous alumina membrane as a densely packed array of poly-MTAPc nanotubes to produce two electrode systems. In the latter system, the surface area enhancement provided by the nanotube-arrayed morphology of the poly-MTAPc enabled a high faradaic (signal) to capacitative (background) current during NO electro-oxidation. Amperometric detection of NO using these two electrode systems shows that the sensitivity and linear ranges were insensitive to the metal centers (M = Cu(2+), Zn(2+), and Pt(2+)) of the poly-MTAPc material.

Computational design of a carbon nanotube fluorofullerene biosensor.

Carbon nanotubes offer exciting opportunities for devising highly-sensitive detectors of specific molecules in biology and the environment. Detection limits as low as 10(-11) M have already been achieved using nanotube-based sensors. We propose the design of a biosensor comprised of functionalized carbon nanotube pores embedded in a silicon-nitride or other membrane, fluorofullerene-Fragment antigen-binding (Fab fragment) conjugates, and polymer beads with complementary Fab fragments. We show by using molecular and stochastic dynamics that conduction through the (9, 9) exohydrogenated carbon nanotubes is 20 times larger than through the Ion Channel Switch ICS(TM) biosensor, and fluorofullerenes block the nanotube entrance with a dissociation constant as low as 37 pM. Under normal operating conditions and in the absence of analyte, fluorofullerenes block the nanotube pores and the polymer beads float around in the reservoir. When analyte is injected into the reservoir the Fab fragments attached to the fluorofullerene and polymer bead crosslink to the analyte. The drag of the much larger polymer bead then acts to pull the fluorofullerene from the nanotube entrance, thereby allowing the flow of monovalent cations across the membrane. Assuming a tight seal is formed between the two reservoirs, such a biosensor would be able to detect one channel opening and thus one molecule of analyte making it a highly sensitive detection design.

Design and properties of functional hybrid organic-inorganic membranes for fuel cells.

This critical review presents a discussion on the major advances in the field of organic-inorganic hybrid membranes for fuel cells application. The hybrid organic-inorganic approach, when the organic part is not conductive, reproduces to some extent the behavior of Nafion where discrete hydrophilic and hydrophilic domains are homogeneously distributed. A large variety of proton conducting or non conducting polymers can be combined with various functionalized, inorganic mesostructured particles or an inorganic network in order to achieve high proton conductivity, and good mechanical and chemical properties. The tuning of the interface between these two components and the control over chemical and processing conditions are the key parameters in fabricating these hybrid organic-inorganic membranes with a high degree of reproducibility. This dynamic coupling between chemistry and processing requires the extensive use and development of complementary ex situ measurements with in situ characterization techniques, following in real time the molecular precursor solutions to the formation of the final hybrid organic-inorganic membranes. These membranes combine the intrinsic physical and chemical properties of both the inorganic and organic components. The development of the sol-gel chemistry allows a fine tuning of the inorganic network, which exhibits acid-based functionalized pores (-SO(3)H, -PO(3)H(2), -COOH), tunable pore size and connectivity, high surface area and accessibility. As such, these hybrid membranes containing inorganic materials are a promising family for controlling conductivity, mechanical and chemical properties (349 references).

A novel sensitive detection platform for antitumor herbal drug aloe-emodin based on the graphene modified electrode.

This paper has presented a novel strategy to carry out direct and sensitive determination of antitumor herbal drug aloe-emodin in complex matrices based on the graphene-Nafion modified glassy carbon (GN/GC) electrode. This proposed modified electrode showed good electrochemical response towards aloe-emodin (AE). Compared with the multiwall carbon nanotubes (MWCNTs) modified electrode, the GN/GC electrode has the advantages of higher sensitivity and lower cost. Under the optimized conditions, the calibration curve for AE concentration was linear in the range from 5 nmol/L to 1 µmol/L with the detection limit of 2 nmol/L. In addition, the practical analytical performance of the GN/GC electrode was examined by evaluating the selective detection of AE in natural aloe extracts and human urine samples with satisfied recovery. Therefore, the GN/GC electrode may hold great promise for fast, simple and sensitive detection and biomedical analysis of AE in complex matrices.

Human detoxification of perfluorinated compounds.

There has been no proven method thus far to accelerate the clearance of potentially toxic perfluorinated compounds (PFCs) in humans. PFCs are a family of commonly used synthetic compounds with many applications, including repelling oil and stains on furniture, clothing, carpets and food packaging, as well as in the manufacturing of polytetrafluoroethylene - a non-stick surfacing often used in cookware (e.g. Teflon(r)). Some PFCs remain persistent within the environment due to their inherent chemical stability, and are very slowly eliminated from the human body due, in part, to enterohepatic recirculation. Exposure to PFCs is widespread and some subpopulations, living in proximity to or working in fluorochemical manufacturing plants, are highly contaminated. PFC bioaccumulation has become an increasing public health concern as emerging evidence suggests reproductive toxicity, neurotoxicity and hepatotoxicity, and some PFCs are considered to be likely human carcinogens. A case history is presented where an individual with high concentrations of PFCs in serum provided: (1) sweat samples after use of a sauna; and (2) stool samples before and after oral administration of each of two bile acid sequestrants - cholestyramine (CSM) and saponin compounds (SPCs). Stool samples before and after use of a cation-exchange zeolite compound were also examined. PFCs found in serum were not detected in substantial quantities in sweat or in stool prior to treatment. Minimal amounts of perfluorooctanoic acid, but no other PFCs, were detected in stool after SPC use; minimal amounts of perfluorooctanesulfonate, but no other PFCs, were detected in stool after zeolite use. All PFC congeners found in serum were detected in stool after CSM use. Serum levels of all PFCs subsequently declined after regular use of CSM. Further study is required but this report suggests that CSM therapy may facilitate gastrointestinal elimination of some PFCs from the human body.

Hyperbaric oxygen therapy in the treatment of diabetic foot ulcers--prudent or problematic: a case report.

Hyperbaric oxygen (HBO) therapy is increasingly used in the management of problem wounds, notably diabetic foot ulcers. However, concerns about unnecessary, inappropriate, and prolonged use of this adjunctive treatment exist. A case report of a 52-year-old patient with diabetes mellitus, Charcot foot, and a nonhealing plantar ulcer who had received HBO treatments only illustrates these concerns. He presented with normal pedal pulses, adequate transcutaneous partial oxygen pressure levels, no offloading footwear, and a heavily contaminated ulcer (Pseudomonas spp.). Following a course of oral antibiotics, appropriate topical wound care, and offloading instructions, the wound healed within 3 months. Advanced wound therapy modalities are only indicated for use in patients when accepted standards of wound care, including identification and correction of underlying disorders and comorbidities, have failed. To prevent misuse/overuse of HBO therapy, stand-alone HBO centers should include a multidisciplinary wound care team.

Nanoarray membrane sensor based on a multilayer design for sensing of water pollutants.

A ubiquitous electrochemical sensor which can detect pollutants in nonconducting aqueous solutions is prepared using a triple layer design, comprising a polyelectrolyte entrapped within micrometer-length nanochannels and sandwiched between two nanometer-thick electrode layers. Replacement of the polyelectrolyte with an enzyme-polyelectrolyte mixture within the nanochannels confers excellent biosensing characteristics. Its superior analytical performance of quantitating copper ions and formaldehyde at trace levels without additional sample treatment steps is demonstrated in freshwater samples derived from a local reservoir.

Evaluation of potential reproductive and developmental toxicity of potassium perfluorohexanesulfonate in Sprague Dawley rats.

This study evaluates the potential reproductive and developmental toxicity of perfluorohexanesulfonate (PFHxS), a surfactant found in sera of the general population. In a modified OECD 422 guideline-based design, 15 rats per sex and treatment group (control, 0.3, 1, 3, and 10mg/kg-d) were dosed by gavage with potassium PFHxS (K(+)PFHxS) or vehicle (0.5% carboxymethylcellulose) 14 days prior to cohabitation, during cohabitation, and until the day before sacrifice (21 days of lactation or presumed gestation day 25 (if not pregnant) for females and minimum of 42 days of treatment for males). Offspring were not dosed by gavage but were exposed by placental transfer in utero and potentially exposed via milk. Evaluations were made for reproductive success, clinical signs, body weight, food consumption, estrous cycling, neurobehavioral effects, gross and microscopic anatomy of selected organs, sperm, hematology, clinical pathology, and concentration of PFHxS in serum and liver. Additional three rats per sex per group were added to obtain sera and liver samples for PFHxS concentration determinations during the study. No reproductive or developmental effects were observed. There were no treatment-related effects in dams or offspring. K(+)PFHxS-induced effects noted in parental males included: (1) at all doses, reductions in serum total cholesterol; (2) at 0.3, 3, and 10mg/kg-d, decreased prothrombin time; (3) at 3 and 10mg/kg-d, increased liver-to-body weight and liver-to-brain weight ratios, centrilobular hepatocellular hypertrophy, hyperplasia of thyroid follicular cells, and decreased hematocrit; (4) at 10mg/kg-d, decreased triglycerides and increased albumin, BUN, ALP, Ca(2+), and A/G ratio. Serum and liver concentrations of PFHxS are reported for parents, fetuses, and pups. PFHxS was not a reproductive or developmental toxicant under study conditions.

Dependence of selectivity on eluent composition and temperature in the HPLC separation of taxanes using fluorinated and hydrocarbon phases.

Optimized conditions of aqueous acetonitrile (ACN) eluent composition and temperature are established for the rapid separation of a standard mixture of 15 taxanes, on each of five different fluorinated phases and one C8 hydrocarbonaceous phase. On both types of stationary phase, the retention factors (k') of most of the taxanes decrease at the same rate with increasing ACN concentration. However, the taxanes containing a xylosyl group show a higher rate of decrease, which necessitates careful control of eluent composition to achieve separation of all the taxanes. Temperature can have a remarkable and counterintuitive effect on retention and selectivity. For the C8 phase with eluent compositions in the 40%-60% ACN range, the k' values of the xylosyl taxanes show an increase with increasing temperature over the range from 25 to 55 degrees C; the k' values for 10-deacetyl baccatin III and 10-deacetyl taxol go through a maximum over the same ranges. The other taxanes behave normally. The same pattern is observed on the propyl(perfluorophenyl) phase, although this and the other fluorinated phases are less retentive. This accounts for the common belief that fluorinated stationary phases offer resolution of taxanes superior to that on hydrocarbon phases. The higher retention on the latter requires eluent compositions near 50% ACN, where careful temperature optimization is required, which in practice is rarely performed. The lesser retention on the fluorinated phases allows use of lower ACN concentrations where the aberrant temperature effect is not found, so good separations without temperature optimization can be achieved. Further evidence of the lack of any fundamental difference in the selectivity of the two types of stationary phase is the similarity of the surface excess isotherms measured for ACN/H2O on both the fluorinated and hydrocarbon phases.

Effect of postoperative treatment with a combination of chuangxiong and electret on functional recovery of muscle grafts: an experimental study in the dog.

Clinical experiences have shown that simultaneous use of constitutional and local treatments postoperatively may increase recovery of transplanted muscle function more than any single treatment. In the present experiment, 27 adult dogs had orthotopic replantation of their bilateral rectus femoris muscles by microneurovascular anastomoses with different therapeutic methods postoperatively for 22 weeks grouped as local implantation of an electret substance (n = 14), intramuscular injection of chuangxiong (Ligusticum wallichii franch) (n = 12), combined use of these two treatments (n = 14), or control (n = 14) to evaluate the influence of these different treatments on muscle function and morphology; electromyography, maximal tetanic tension, and histologic and histochemical examinations showed that the results in all the treatment groups were superior to those in the nontreatment group and that simultaneous use of constitutional and local treatments was superior to any single treatment. At week 22, the maximal tetanic tension of the three treatment groups returned to 57.68 +/- 1.67, 53.64 +/- 3.28, and 64.94 +/- 3.28 percent of control values (before transplantation), respectively, versus 47.99 +/- 2.21 percent in the nontreatment group. These results suggest that treatment with local electret and systemic chuangxiong simultaneously has a favorable effect on nerve regeneration and on muscle function after muscle transplantation.