Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Cloning of PCS gene (TpPCS1) from Tagetes patula L. and expression analysis under cadmium stress

Phytochelatins (PCs) constitute an important mechanism for plants to resist heavy metal stress. Widely found in higher plants, they are small heavy metal binding peptides, synthesized through catalysis of phytochelatin synthase (PCS). We speculate that there may be PCS genes in Peacock grass (Tagetes patula L., Asteraceae), which is an important reason for its rich cadmium. In order to obtain the full-length cDNA sequence of the PCS gene from T. patula L. used rapid amplification of cDNA ends (RACE). Meanwhile, Relative expression of TpPCS1 under different concentrations of cadmium (Cd) stress was analysed using quantitative real-time polymerase chain reaction (qRT-PCR). Results found ORF of TpPCS1 genes with a length of 1970 bp, a gene coding area length of 1764 bp, coding for 587 amino acids. Expression of TpPCS1 under Cd stress was tissue specific. TpPCS1 in the root showed higher expression, while expression in the leaf and seed was relatively low. This research demonstrates that expression of TpPCS1 enhanced the enrichment of cadmium in T. patula L. roots and could be used to construct a plant hyperexpression carrier that would provide new avenues for plant restoration technology.

Characterizing randomness in photonic glasses using autocorrelation functions of two-dimensional images

We have developed a simple method to quantify randomness in photonic glasses in relation to the ideal random limit, using autocorrelation functions obtained from two-dimensional images. In our case, the photonic glasses consist of randomly packed silica microspheres which serve as a model system representing isotropic random media. Conventional methods of characterizing randomness in photonic materials often entail technical complexities, such as chemical functionalization, three-dimensional rendering, and particle tracking. Our method circumvents these difficulties based on a mathematical relation that we derive between the autocorrelation function and the radial distribution function. This relation enables us to find the autocorrelation function in the ideal random limit. The autocorrelation function of experimentally fabricated photonic glasses is then obtained from images of a single cross-sectional plane and directly compared to that of the ideal limit. The comparison shows that the autocorrelation function of real structures deviates only slightly from the ideal limit. We find that the deviation can be explained in part by the microsphere polydispersity. Our general method would be useful in characterizing a large class of photonic random media, encompassing biological materials, radiative cooling coatings, and random lasing photonic glasses.

Clinical risk factors for acute ischaemic and haemorrhagic stroke in patients with infective endocarditis

BACKGROUND

Stroke as a complication of infective endocarditis portends a poor prognosis, yet risk factors for stroke subtypes have not been well defined.

AIM

To identify risk factors associated with ischaemic and haemorrhagic strokes.

METHODS

A retrospective patient chart review was performed at a single US academic centre to identify risk factors and imaging for patients who were 18 years or older with infectious endocarditis (IE) and stroke diagnoses. Differences in patient characteristics by stroke status were assessed using univariate analysis, χ² or student's t-test as well as logistic regression models for multivariable analyses and correlation matrices to identify possible collinearity between variables and to obtain odds ratios (OR) and their 95% confidence intervals.

RESULTS

A final sample of 1157 participants was used for this analysis. The total number of non-surgical strokes was 178, with a prevalence of 15.4% (78% ischaemic, 10% parenchymal haemorrhages, 8% subarachnoid haemorrhages and 4% mixed ischaemic/haemorrhagic). Multivariate risk factors for ischaemic stroke included prior stroke (OR 2.0, 1.3-3.1), Staphylococcus infection (OR 2.0, 1.3-3.0), mitral vegetations (OR 2.2, 1.4-3.3) and valvular abscess (OR 2.7, 1.7-4.3). Risk factors for haemorrhagic stroke included fungal infection (OR 6.4, 1.2-34.0), male gender (OR 3.5, 1.4-8.3) and rheumatic heart disease (OR 3.3, 1.1-10.4).

CONCLUSION

Among patients with IE, there exist characteristics that relate differentially to ischaemic and haemorrhagic stroke risk.

[The efficacy and safety of testa triticum tricum purif in treatment of functional constipation in the late middle-aged and elderly patients: a multicenter randomized controlled clinical trial]

Objective: To evaluate the efficacy and safety of testa triticum tricum purif for the treatment of functional constipation(FC) in the late middle-aged and elderly patients. Methods: This study was designed as a multicenter randomized controlled trial. Patients who met Rome Ⅲ diagnostic criteria of FC were enrolled, with age between 55-85 years old. Those with organic diseases were excluded. The patients were randomly allocated to receive testa triticum tricum purif (3.5 g bid) or polyethylene glycol 4000 powder (PEG4000, 10g bid) for 8 weeks, followed by single dose of maintenance therapy for 4 weeks. Follow-up visits were at 4 and 12 weeks after treatment discontinuation. The independent investigators in each center evaluated the constipation symptoms scores. The primary endpoints included rates of significant improvement, improvement and overall improvement at the end of 2, 4 and 8 weeks of therapy, which were calculated by the reduction of symptom scores ≥75%, 50%-74%, ≥25% respectively. Results: A total of 127 FC subjects were enrolled from 3 centers, and 122 cases valid for final analysis. The mean age was (69.4±6.9) years old, including 62 cases in testa triticum tricum purif group and 60 cases in PEG4000 group. The demographic data, constipated symptoms scores and proportion of FC subtypes at baseline were comparable. The rates of significant improvement, improvement and overall improvement in testa triticum tricum purif and PEG4000 groups at the end of 2, 4 and 8 weeks were 37.70% (23/61) vs 59.32% (35/59) (P=0.018), 57.38% (35/61) vs 74.14% (43/58) (P=0.054), and 64.41% (38/59) vs 79.31% (46/58) (P=0.073) respectively. Testa triticum tricum purif therapy significantly improved the proportion of spontaneous bowel movement(SBM) ≥3 times/week from 43.55% (27/62) to 80.33% (49/61), 83.61% (51/61) and 93.22% (55/59) at 2, 4, and 8 weeks respectively (all P<0.01), which were comparable with PEG4000 group (all P>0.05). The proportion of normalized stool forms in study group was significant higher than that of control group at the end of 8 weeks [86.44% (51/59) vs 67.24% (39/58), P=0.014]. Only one patient complained mild abdominal distension during testa triticum tricum purif therapy. Conclusions: The efficacy of testa triticum tricum purif for the treatment of FC in late middle-aged and older patients is comparable with osmotic laxatives PEG4000, which has significant effect on normalization of fecal forms and reliable safety.

Evaluation of bee venom as a novel feed additive in fast-growing broilers

1. The present study was designed to evaluate purified bee venom (BV) as an alternative to antibiotics in broiler chickens. The experimental treatment diets were formulated by adding BV into a maize-soybean meal-based diet to give 0, 10, 50, 100, and 500 μg BV per kg of diet. 2. Dietary BV quadratically improved (P < 0.05) feed conversion ratio and increased body weight gain at 1-21 d as level in diet increased. Higher BV levels lowered relative weight of spleen (linear and quadratic, P < 0.05), bursa of Fabricius (quadratic, P < 0.05), and liver (linear and quadratic, P < 0.05) at 21 d of age. Relative breast meat yields were increased quadratically at 21 d and linearly at 35 d with supplementation levels. Dietary BV increased (linear and quadratic, P < 0.05) lightness (L*) value for meat at 21 d, decreased (linear, P < 0.05) ileal villus height and narrowed (quadratic, P < 0.05) width. 3. Dietary BV inclusion linearly increased the concentration of secretory immunoglobulin A (sIgA) on ileal mucosa at 21 d and decreased (quadratic, P < 0.05) nitric oxide contents in serum samples at 21 d and 35 d. Total short-chain fatty acids (SCFA) in caecal digesta were reduced with increasing venom in diets at 21 d of age. None of the serum parameters except for creatinine was affected by dietary BV. 4. It was concluded that dietary BV exhibited wide range of in vivo biological properties in broiler chickens and could be incorporated into feed to promote growth and animal health.

Control of Randomness in Microsphere-Based Photonic Crystals Assembled by Langmuir-Blodgett Process

Photonic structures in biological systems typically exhibit an appreciable level of disorder within their periodic framework. However, how such disorder within the ordered framework renders unique optical properties has not been fully understood. Toward the goal of improving this understanding, we have investigated Langmuir-Blodgett assembly of microspheres to controllably introduce randomness to photonic structures. We theoretically modeled the assembly process and determined a condition for surface pressure and substrate pulling speed that results in maximum structural order. For each surface pressure, there is an optimum pulling speed and vice versa. Along the trajectory defined by the optimum condition, however, the structural order decreases moderately as the pulling speed increases. This moderate decrease in structural order would be useful for controlled introduction of randomness into the periodic structures. Departing from the trajectory, our experiment reveals that a small change in pulling speed at a given surface pressure can significantly disrupt the structural order. For multilayer assembly, we find that, at a fixed pulling speed, the surface pressure should increase as the number of layers increases to achieve maximum structural order. In totality, we quantitatively present the optimum trajectories for the nth layer assembly relating surface pressure and pulling speed.

Symmetry-breaking nanostructures on crystalline silicon for enhanced light trapping in thin film solar cells

We introduce a new approach to systematically break the symmetry in periodic nanostructures on a crystalline silicon surface. Our focus is inverted nanopyramid arrays with a prescribed symmetry. The arrangement and symmetry of nanopyramids are determined by etch mask design and its rotation with respect to the [110] orientation of the Si(001) substrate. This approach eliminates the need for using expensive off-cut silicon wafers. We also make use of low-cost, manufacturable, wet etching steps to fabricate the nanopyramids. Our experiment and computational modeling demonstrate that the symmetry breaking can increase the photovoltaic efficiency in thin-film silicon solar cells. For a 10-micron-thick active layer, the efficiency improves from 27.0 to 27.9% by enhanced light trapping over the broad sunlight spectrum. Our computation further reveals that this improvement would increase from 28.1 to 30.0% in the case of a 20-micron-thick active layer, when the unetched area between nanopyramids is minimized with over-etching. In addition to the immediate benefit to solar photovoltaics, our method of symmetry breaking provides a useful experimental platform to broadly study the effect of symmetry breaking on spectrally tuned light absorption and emission.

Comparative genomic hybridization analysis of rice dwarf mutants induced by gamma irradiation

Comparative genomic hybridization (CGH) is a powerful tool used to analyze changes in copy number, polymorphisms, and structural variations in the genome. Gene copy number variation (CNV) is a common form of natural diversity in the genome, which can create new genes and alter gene structure. Thus, CNVs may influence phenotypic variation and gene expression. In this study, to detect CNVs, we irradiated rice seeds with gamma rays (300 Gy) and selected two dwarf mutagenized plants, GA-III-189 and -1052, in the M₃ generation. These plants were subjected to CGH analysis using Agilent's RICE CGH array. Most of the CNVs identified were less than 10 kb in length. We detected 90 amplified and 18 deleted regions in GA-III-189, and 99 amplified and 11 deleted regions in GA-III-1052. Of note, CNVs were located on chromosome 12 in both GA-III-189 and -1052, which contained 39 commonly amplified regions in 29 genes. The commonly amplified genes included six genes encoding F-box domain-containing proteins. Alterations in these F-box domain-containing genes were confirmed by quantitative RT-PCR. Integration of CGH and gene expression data identified copy number aberrations and novel genes potentially involved in the dwarf phenotype. These CGH and gene expression data may be useful for uncovering the mechanisms underlying the dwarf phenotype.

Targeted Next-Generation Sequencing for Comprehensive Genetic Profiling of Pharmacogenes

Phenotypic differences in drug responses have been associated with known pharmacogenomic loci, but many remain to be characterized. Therefore, we developed next-generation sequencing (NGS) panels to enable broad and unbiased inspection of genes that are involved in pharmacokinetics (PKs) and pharmacodynamics (PDs). These panels feature repetitively optimized probes to capture up to 114 PK/PD-related genes with high coverage (99.6%) and accuracy (99.9%). Sequencing of a Korean cohort (n = 376) with the panels enabled profiling of actionable variants as well as rare variants of unknown functional consequences. Notably, variants that occurred at low frequency were enriched with likely protein-damaging variants and previously unreported variants. Furthermore, in vitro evaluation of four pharmacogenes, including cytochrome P450 2C19 (CYP2C19), confirmed that many of these rare variants have considerable functional impact. The present study suggests that targeted NGS panels are readily applicable platforms to facilitate comprehensive profiling of pharmacogenes, including common but also rare variants that warrant screening for personalized medicine.

Genome-wide expression analysis of a rice mutant line under salt stress

Salinity is a major environmental stress to plants. In this study, the ability of plants to tolerate salt was investigated by studying growth, physiological characteristics, and expression levels of genes related to the salt-stress response in the salt-tolerant rice mutant (Till-II-877), which was derived from γ-ray irradiation. Compared to plants grown under normal conditions, the height and root length of wild type (WT) were reduced by approximately 40 and 29% following exposure to salt stress for 3 weeks, whereas Till-II-877 line showed 29 and 23% reductions in plant height and root length, respectively. No significant changes were observed in total chlorophyll content, and the malondialdehyde content of the mutant increased less than that of the WT under salt treatment. Gene expression was compared between the WT and mutant lines using microarray analysis. An unbiased analysis of the gene expression datasets allowed us to identify the pathways involved in salt-stress responses. Among the most significantly affected pathways, changes in gene expression were observed in α-linolenic acid and linoleic acid metabolism (in lipid metabolism), fructose and mannose metabolism and glycolysis-gluconeogenesis (in carbohydrate metabolism), cysteine and methionine metabolism (in amino acid metabolism), and carbon fixation (in the energy metabolism of photosynthetic organisms) under salt stress. These results show that the differential response of plants subjected to salt stress was due to changes in multiple metabolic pathways. These findings increase our understanding of the effects of salt stress in rice and may aid in the development of salt-tolerant rice cultivars.

Clinical characteristics and risk factors of intracranial hemorrhage in systemic lupus erythematosus

We enrolled and reviewed 26 medical records of systemic lupus erythematosus (SLE) with intracranial hemorrhage (cases) and 104 randomly matched records of SLE without intracranial hemorrhage (controls) out of 6653 admitted patients at Peking Union Medical College Hospital from 1994 to 2012, to analyze the clinical characteristics and risk factors of intracranial hemorrhage in SLE. The incidence of SLE with intracranial hemorrhage was only 0.39% within the last 18 years at Peking Union Medical College Hospital. However, the in-hospital fatality rate was quite high (23.1%). Headache was the most common symptom (53.5%) in SLE patients with intracranial hemorrhage. The anatomical localization of the hemorrhages in the brain was predominantly located in the cerebrum. Intracranial hemorrhage could happen in either stable or active SLE patients. SLE patients with intracranial hemorrhage presented other neuropsychiatric syndromes defined by the American College of Rheumatology (ACR) in 1999, thrombocytopenia and antiphospholipid syndrome more frequently than controls. Thrombocytopenia was the independent risk factor for intracranial hemorrhage coexisting with SLE (OR=3.687, 95% CI 1.510-9.001, p=0.004).

Effect of pre-exposure to sevoflurane on the bispectral index in women undergoing Caesarean delivery under general anaesthesia

BACKGROUND

Patients undergoing Caesarean delivery under inhalation anaesthesia are at a high risk of awareness, especially in the period before delivery. We assessed the effects of pre-exposure to sevoflurane on the bispectral index (BIS) in the interval before delivery.

METHODS

Sixty-four patients undergoing elective Caesarean delivery were randomly assigned to receive 1.0-1.1 vol% (control 1) or 1.2-1.3 vol% (control 2) end-tidal sevoflurane, or the same concentrations of end-tidal sevoflurane combined with pre-exposure to 1 vol% sevoflurane for the last 1 min of the preoxygenation period (the preSevo 1 and preSevo 2 groups, respectively). We assessed BIS values, arterial pressure, and heart rate at the time of induction; before intubation; and upon skin incision, uterine incision, and delivery. We also determined the maternal incidence of intraoperative awareness and the neonatal Apgar scores, and conducted umbilical blood gas analysis.

RESULTS

At skin incision, BIS values were significantly lower in the preSevo 1 group than in the control 1 group [50 (13) vs 72 (8), P<0.001] and in the preSevo 2 group than in the control 2 group [44 (11) vs 67 (10), P<0.001]. The mean BIS values in the preSevo 1 and 2 groups were maintained below 60 in the period before delivery. No other parameter differed among groups, and no patient exhibited intraoperative awareness.

CONCLUSIONS

Pre-exposure to low concentrations of sevoflurane reduced BIS values in the interval before delivery, suggesting that this approach may reduce the risk of maternal awareness. Clinical Research Information Service (code KCT0000069, http://cris.cdc.go.kr).

Randomized clinical trial of intravenous soybean oil alone versus soybean oil plus fish oil emulsion after gastrointestinal cancer surgery

BACKGROUND

Specific immunonutrients may reduce the incidence of postoperative complications and shorten recovery time. This randomized trial evaluated the clinical efficacy of a fish oil emulsion on outcome and immune function after gastrointestinal cancer surgery.

METHODS

A total of 206 patients with gastrointestinal or colonic cancer were randomized to receive isocaloric and isonitrogenous intravenous infusions of either soybean oil alone (1.2 g per kg bodyweight per day; control group, 103 analysed) or soybean plus fish oil emulsion (1.0 and 0.2 g per kg per day respectively; treatment group, 100 analysed) over 20-24 h daily for 7 days after surgery.

RESULTS

Baseline data were comparable in the two groups. There were fewer infectious complications (four versus 12 on day 8; P = 0.066), systemic inflammatory response syndrome (SIRS) was significantly less common (four versus 13; P = 0.039) and hospital stay was significantly shorter (mean(s.d.) 15(5) versus 17(8) days; P = 0.041) in the treatment group. Total postoperative medical costs were comparable in the two groups (mean(s.d.) US $ 1269(254) and 1302(324) in treatment and control groups respectively; P = 0.424). The median (interquartile range) difference in CD4/CD8 between days 1 and 8 after surgery was + 0.30 (0.06 to 0.79) in patients receiving fish oil and + 0.20 (-0.19 to 0.55) in controls (P = 0.021). No severe adverse events occurred in either group.

CONCLUSION

Fish oil emulsion-supplemented parenteral nutrition significantly reduced SIRS and length of hospital stay. These clinical benefits may be related to normalization of cellular immune functions and modulation of the inflammatory response.

Synthesis and Characterization of Germanium Coordination Compounds for Production of Germanium Nanomaterials

A series of novel germanium(II) precursors was synthesized to initiate an investigation between the precursors' structures and the morphologies of the resulting nanoparticles. The precursors were synthesized from the reaction of Ge[N(SiMe3)2]2 or [Ge(OBut)2]2 and the appropriate ligand: N,N'-dibenzylethylenediamine (H2-DBED), tert-butanol (H-OBut), 2,6-di-methyl phenol (H-DMP), 2,6-di-phenyl phenol (H-DPP), tert-butyldimethylsilanol (H-DMBS), triphenylsilanol (H-TPS), triphenylsilanethiol (H-TPST), and benzenethiol (H-PS). The products were identified as: [Ge(μc-DBED)]2 (1, μc= bridging chelating), [Ge(μ-DMP)(DMP)]2 (2), Ge(DPP)2 (3), [Ge(μ-OBut)(DMBS)]2, (4), [Ge(μ-DMBS)(DMBS)]2 (5), Ge(TPS)3(H) (6), [Ge(μ-TPST)(TPST)]2 (7), and Ge(PS)4 (8). The Ge(II) metal centers were found to adopt a pyramidal geometry for 1, 2, 4, 5, 7, a bent arrangement for 3, and a tetrahedral coordination for the Ge(IV) species 6 and 8. Using a simple solution precipitation methodology, Ge(0) nanomaterials were isolated as dots and wires for the majority of precursors. Compound 7 led to the isolation of amorphous GexSy. The nanomaterials isolated were characterized by TEM, EDS, and powder XRD. A correlation between the precursor's arrangement and final observed nanomorphology was proffered as part of the 'precursor structure affect' phenomenon.

Impact of leakage current and electrolysis on FET flow control and pH changes in nanofluidic channels

We have fabricated multiple-internal-reflection Si infrared waveguides integrated with an array of nanochannels sealed with an optically transparent top cover. The channel walls consist of a thin layer of SiO2 for electrical insulation, and gate electrodes surround the channel sidewalls and bottom to manipulate their surface charge and zeta-potential in a fluidic field effect transistor (FET) configuration. This nanofluidic device is used to probe the transport of charged molecules (Alexa 488) and to measure the pH shift in nanochannels in response to an electrical potential applied to the gate. During gate biasing for FET operation, laser-scanning confocal fluorescence microscopy (LS-CFM) is used to visualize the flow of fluorescent dye molecules (Alexa 488), and multiple internal reflection-Fourier transform infrared spectroscopy (MIR-FTIRS) is used to probe the characteristic vibrational modes of fluorescein pH indicator and measure the pH shift. The electroosmotic flow of Alexa 488 is accelerated in response to a negative gate bias, whereas its flow direction is reversed in response to a positive gate bias. We also measure that the pH of buffered electrolyte solutions shifts by as much as a pH unit upon applying the gate bias. With prolonged application of gate bias, however, we observe that the initial response in flow speed and direction as well as pH shift becomes reversed. We attribute these anomalous flow and pH shift characteristics to a leakage current that flows from the Si gate through the thermally grown SiO2 to the electrolyte solution.

Effect of wall-molecule interactions on electrokinetic transport of charged molecules in nanofluidic channels during FET flow control

The interactions between charged molecules and channel surfaces are expected to significantly influence the electrokinetic transport of molecules and their separations in nanochannels. This study reports the effect of wall-molecule interactions on flow control of negatively charged Alexa 488 and positively charged Rhodamine B dye molecules in an array of nanochannels (100 nm wx 500 nm dx 14 mm l) embedded in fluidic field effect transistors (FETs). For FET flow control, a third electrical potential, known as a gate bias, is applied to the channel walls to manipulate their zeta-potential. Electroosmotic flow of charged dye molecules is accelerated or reversed according to the polarity and magnitude of the gate bias. During FET flow control, we monitor how the electrostatic interaction between charged dye molecules and channel walls affects the apparent velocity of molecules, using laser-scanning confocal fluorescence microscopy. We observe that the changes in flow speed and direction of negatively charged Alexa 488 is much more pronounced than that of positively charged Rhodamine B in response to the gate bias that causes either repulsive or attractive electrostatic interactions. This observation is supported by calculations of concentration-weighted velocity profiles of the two dye molecules during FET flow control. The velocity profile of negatively charged Alexa 488 is much more pronounced at the center of each nanochannel than near its walls since Alexa 488 molecules are repelled from negatively charged channel walls. This pronounced center velocity further responds to the gate bias, increasing the average velocity by as much as 23% when -30 V is applied to the gate (zeta-potential = -80.6 mV). In contrast, the velocity profile of positively charged Rhodamine B is dispersed over the entire channel width due to dye-wall attraction and adsorption. Our experimental observations and calculations support the hypothesis that valence-charge-dependent electrostatic interaction and its manipulation by the gate bias would enhance molecular separations of differentially charged molecules in nanofluidic FETs.

Experimentally and theoretically observed native pH shifts in a nanochannel array

Lab-on-a-chip (LOC) technology provides a powerful platform for simultaneous separation, purification, and identification of low concentration multicomponent mixtures. As the characteristic dimension of LOC devices decreases down to the nanoscale, the possibility of containing an entire lab on a single chip is becoming a reality. This research examines one of the unique physical characteristics of nanochannels, in which native pH shifts occur. As a result of the electrical double layer taking up a significant portion of a 100 nm wide nanochannel, electroneutrality no longer exists in the channel causing a radial pH gradient. This work describes experimentally observed pH shifts as a function of ionic strength using the fluorescent pH indicator 5-(and-6)-carboxy SNARF-1 and compares it to a model developed using Comsol Multiphysics. At low ionic strengths (approximately 3 mM) the mean pH shift is approximately 1 pH unit whereas at high ionic strengths (approximately 150 mM) the mean pH shift is reduced to 0.1 pH units. An independent analysis using fluorescein pH indicator is also presented supporting these findings. Two independent non-linear simulations coupling the Nernst-Planck equation describing transport in ionic solutions subjected to an electric field and Poisson's equation to describe the electric field as it relates to the charge distribution are solved using a finite element solver. In addition, the effects of chemical activities are considered in the simulations. The first numerical simulation is based on a surface zeta-potential which significantly underestimates the experimental results for most ionic strengths. A modified model assuming that SNARF and fluorescein molecules are able to diffuse into the hydrolyzed SiO2 phase, and in the case of the SNARF molecule, able to bind to neutral regions of the SiO2 phase agrees quantitatively with experimental results.

Using 100% Oxygen does not Alter the Cardiovascular Autonomic Regulation during Non-invasively Simulated Haemorrhage in Healthy Volunteers

We tested the effect of 100% oxygen on heart rate (HR), arterial blood pressure (ABP), cardiac output (CO), stroke volume (SV), total peripheral resistance (TPR), HR variability (HRV), systolic blood pressure variability (SBPV) and baroreflex sensitivity (BRS) in 20 healthy volunteers during simulated haemorrhage induced by −40 mmHg lower body negative pressure (LBNP). HRV in the high frequency region (HRVHF), BRS, ABP and TPR were significantly increased, SBPV in the low frequency region (SBPVLF), CO and SV were unchanged, and HR was significantly decreased by 100% oxygen administration during normovolaemia. HRVHF, BRS, CO and SV were significantly decreased, SBPVLF and ABP were unchanged, and HR and TPR were significantly increased by LBNP during 21% or 100% oxygen administration. There were no significant differences in cardiovascular autonomic and haemodynamic responses to LBNP during 21% or 100% oxygen administration, suggesting that 100% oxygen does not alter normal cardiovascular autonomic responses during simulated haemorrhage.

Monitoring FET flow control and wall adsorption of charged fluorescent dye molecules in nanochannels integrated into a multiple internal reflection infrared waveguide

Using Si as the substrate, we have fabricated multiple internal reflection infrared waveguides embedded with a parallel array of nanofluidic channels. The channel width is maintained substantially below the mid-infrared wavelength to minimize infrared scattering from the channel structure and to ensure total internal reflection at the channel bottom. A Pyrex slide is anodically bonded to the top of the waveguide to seal the nanochannels, while simultaneously enabling optical access in the visible range from the top. The Si channel bottom and sidewalls are thermally oxidized to provide an electrically insulating barrier, and the Si substrate surrounding the insulating SiO(2) layer is selectively doped to function as a gate. For fluidic field effect transistor (FET) control, a DC potential is applied to the gate to manipulate the surface charge on SiO(2) channel bottom and sidewalls and therefore their zeta-potential. Depending on the polarity and magnitude, the gate potential can accelerate, decelerate, or reverse the flow. Here, we demonstrate that this nanofluidic infrared waveguide can be used to monitor the FET flow control of charged, fluorescent dye molecules during electroosmosis by multiple internal reflection Fourier transform infrared spectroscopy. Laser scanning confocal fluorescence microscopy is simultaneously used to provide a comparison and verification of the IR analysis. Using the infrared technique, we probe the vibrational modes of dye molecules, as well as those of the solvent. The observed infrared absorbance accounts for the amount of dye molecules advancing or retracting in the nanochannels, as well as adsorbing to and desorbing from the channel bottom and sidewalls.

Solution synthesis of germanium nanowires using a Ge2+ alkoxide precursor

A simple solution synthesis of germanium (Ge0) nanowires under mild conditions (<400 degrees C and 1 atm) was demonstrated using germanium 2,6-dibutylphenoxide, Ge(DBP)2 (1), as the precursor where DBP = 2,6-OC6H3(C(CH3)3)2. Compound 1, synthesized from Ge(NR2)2 where R = SiMe3 and 2 equiv of DBP-H, was characterized as a mononuclear species by single-crystal X-ray diffraction. Dissolution of 1 in oleylamine, followed by rapid injection into a 1-octadecene solution heated to 300 degrees C under an atmosphere of Ar, led to the formation of Ge0 nanowires. The Ge0 nanowires were characterized by transmission electron microscopy (TEM), X-ray diffraction analysis, and Fourier transform infrared spectroscopy. These characterizations revealed that the nanowires are single crystalline in the cubic phase and coated with oleylamine surfactant. We also observed that the nanowire length (0.1-10 microm) increases with increasing temperature (285-315 degrees C) and time (5-60 min). Two growth mechanisms are proposed based on the TEM images intermittently taken during the growth process as a function of time: (1) self-seeding mechanism where one of two overlapping nanowires serves as a seed, while the other continues to grow as a wire; and (2) self-assembly mechanism where an aggregate of small rods (<50 nm in diameter) recrystallizes on the tip of a longer wire, extending its length.

Water-soluble germanium(0) nanocrystals: cell recognition and near-infrared photothermal conversion properties

Surfactant-passivated germanium nanocrystals (Ge(0) NCs) 3-5 nm in diameter were synthesized and encapsulated with functionalized phospholipids to yield water-soluble Ge(0) NCs. Upon encapsulation, the NCs retained their cubic crystalline phase and displayed good resistance to oxidation, as determined by transmission electron microscopy and X-ray photoelectron spectroscopy. As a test of their cell compatibility, the ability of carboxyfluorescein (CF)-labeled dinitrophenyl (DNP)-functionalized Ge(0) NCs to crosslink dinitrophenol-specific immunoglobulin E antibodies on the surface of mast cells (RBL-2H3) was examined in vitro. Treatment with a multivalent DNP antigen (i.e., DNP-Ge(0) NCs or CF-DNP-Ge(0) NCs) caused crosslinking of FcepsilonRI receptors and cellular responses, which were evaluated with morphological and colorimetric assays and live-cell fluorescence microscopy. Incubation of RBL-2H3 cells with Ge(0) NCs for approximately 24 h gave less than a 2 % increase in cell death as compared to DNP-functionalized bovine serum albumin. When irradiated with near-infrared (NIR) radiation (lambda(exc)=770 nm, 1.1 W cm(-2)) from a continuous-wave Ti:sapphire laser, the bulk-solution temperature of a toluene solution containing 20 mg mL(-1) Ge(0) NCs increased by approximately 35 degrees C within 5 min. Phospholipid-encapsulated water-soluble Ge(0) NCs at concentrations of 1.0 mg mL(-1) also displayed stable photothermal behavior under repetitive and prolonged NIR laser exposures in water, to yield a temperature increase of approximately 20 degrees C within 5 min (lambda(exc)=770 nm, 0.9 W cm(-2)). The photothermal efficiency of water-soluble Ge(0) NCs compares favorably with a recent report for Au nanoshells.

A Comparison of Ultrasonic and X-ray Methods for Imaging the Growth Plate

The purpose of this study was to assess a systematic and scientific method for measuring children's growth development, in which the accuracy of the existing diagnostic method has not yet been concretely examined. The most popular method for diagnosis of children's growth is to analyse the opening degree of the growth plate in each joint by an X-ray image. However, the X-ray method has some disadvantages; it is impossible to measure the diagnosis of growth periodically and repeatedly due to the radiation problem. Hence, this study introduced a profile analysis and the algorithm of analysing the image of the growth plate using the broadband ultrasound attenuation (BUA) of calcaneus, to verify the possibility of using an alternative ultrasonic method harmless to the human body. The images of the growth plate in the proximal tibiae, phalanges, and calcanei of 269 children (7–16 years old) were obtained using X-ray. The image of the growth plate in the calcanei was also obtained from these children using ultrasound. The results showed that the time of the opening degree of the growth plate in each joint was almost consistent between X-ray and ultrasonic images. Also, the images of the growth plate measured using X-ray and ultrasound showed a high correlation. Therefore, it is expected that the algorithm of ultrasonic profile analysis introduced in this study can replace the existing X-ray method to measure the growth plate correctly.

Changes in magnesium concentration in the serum and cerebrospinal fluid of neuropathic rats

BACKGROUND

Central sensitization of neuropathic pain is associated with an influx of extracellular calcium via the opening of N-methyl-D-aspartate (NMDA) receptor-gated ion channels, which are usually blocked by magnesium plugs. As magnesium-deficient rats develop a mechanical hyperalgesia and intrathecal or intraperitoneal magnesium suppresses neuropathic pain, the magnesium concentrations in serum and cerebrospinal fluid may be altered in neuropathic pain. We therefore compared the magnesium concentrations in serum and cerebrospinal fluid of neuropathic rats with those in injured rats without symptoms of neuropathic pain and normal rats.

METHODS

Mechanical allodynia was induced in male Sprague-Dawley rats by tight ligature of the left lumbar fifth and sixth spinal nerves. The threshold of paw withdrawal was evaluated by the up-down method using withdrawal response to stimulus with a von Frey filament on the third, seventh and 14th days. Rats with a threshold of less than 4 g were selected as the symptomatic group and compared with an asymptomatic group, an unoperated control group and a sham-operated group. On the 16th day, the Mg2+ concentrations in serum and cerebrospinal fluid were measured.

RESULTS

The magnesium concentrations in the serum and cerebrospinal fluid of symptomatic neuropathic rats did not differ from those in the injured rats without symptoms of neuropathic pain, sham-operated rats and normal rats.

CONCLUSION

Our results suggest that physiologic homeostasis is maintained by active transport through the blood-brain barrier despite the activation of NMDA receptor-gated ion channels. However, rats with neuropathic pain may be in a magnesium-deficient condition at the effector site, such that magnesium treatment can decrease neuropathic pain.

Anhydrous solution synthesis of germanium nanocrystals from the germanium(II) precursor Ge[N(SiMe3)2]2

A convenient, simple, single-source solution synthesis of Ge nanocrystals via thermal reduction of Ge(II) precursor Ge[N(SiMe3)2]2 in a non-coordinating solvent at 300 degrees C and 1 atm Ar is described.

Adsorption kinetics of 1-alkanethiols on hydrogenated Ge(111)

We have investigated the liquid-phase self-assembly of 1-alkanethiols (HS(CH2)n-1CH3, n = 8, 16, and 18) on hydrogenated Ge(111), using attenuated total reflection Fourier transform infrared spectroscopy as well as water contact angle measurements. The infrared absorbance of C-H stretching modes of alkanethiolates on Ge, in conjunction with water contact angle measurements, demonstrates that the final packing density is a function of alkanethiol concentration in 2-propanol and its chain length. High concentration and long alkyl chain increase the steady-state surface coverage of alkanethiolates. A critical chain length exists between n = 8 and 16, above which the adsorption kinetics is comparable for all long alkyl chain 1-alkanethiols. The steady-state coverage of hexadecanethiolates, representing long-chain alkanethiolates, reaches a maximum at approximately 5.9 x 10(14) hexadecanethiolates/cm2 in 1 M solution. The characteristic time constant to reach a steady state also decreases with increasing chain length. This chain length dependence is attributed to the attractive chain-to-chain interaction in long-alkyl-chain self-assembled monolayers, which reduces the desorption-to-adsorption rate ratio (kd/ka). We also report the adsorption and desorption rate constants (ka and kd) of 1-hexadecanethiol on hydrogenated Ge(111) at room temperature. The alkanethiol adsorption is a two-step process following a first-order Langmuir isotherm: (1) fast adsorption with ka = 2.4 +/- 0.2 cm3/(mol s) and kd = (8.2 +/- 0.5) x 10(-6)(s-1); (2) slow adsorption with ka = 0.8 +/- 0.5 cm3/(mol s) and kd = (3 +/- 2) x 10(-6) s(-1).

Peering into the self-assembly of surfactant templated thin-film silica mesophases

It is now recognized that self-assembly is a powerful synthetic approach to the fabrication of nanostructures with feature sizes smaller than achievable with state of the art lithography and with a complexity approaching that of biological systems. For example, recent research has shown that silica/surfactant self-assembly combined with evaporation (so-called evaporation induced self-assembly EISA) can direct the formation of porous and composite thin-film mesostructures characterized by precise periodic arrangements of inorganic and organic constituents on the 1-50-nm scale. Despite the potential utility of these films for a diverse range of applications such as sensors, membranes, catalysts, waveguides, lasers, nano-fluidic systems, and low dielectric constant (so-called low k) insulators, the mechanism of EISA is not yet completely understood. Here, using time-resolved grazing incidence small-angle X-ray scattering (GISAXS) combined with gravimetric analysis and infrared spectroscopy, we structurally and compositionally characterize in situ the evaporation induced self-assembly of a homogeneous silica/surfactant/solvent solution into a highly ordered surfactant-templated mesostructure. Using CTAB (cetyltrimethylammonium bromide) as the structure-directing surfactant, a two-dimensional (2-D) hexagonal thin-film mesophase (p6mm) with cylinder axes oriented parallel to the substrate surface forms from an incipient lamellar mesophase through a correlated micellar intermediate. Comparison with the corresponding CTAB/water/alcohol system (prepared without silica) shows that, for acidic conditions in which the siloxane condensation rate is minimized, the hydrophilic and nonvolatile silicic acid components replace water maintaining a fluidlike state that avoids kinetic barriers to self-assembly.

Disc hydration measured by magnetic resonance imaging in relation to its compressive stiffness in rat models

The in vivo effects of body dehydration on the water content and compressive stiffness of rat intervertebral disc (IVD) and vertebral body were investigated. Thirty-one rats were divided into three dietary groups: water restricted ( WR), pair fed (PF) and ad libitum (AL). The in vivo water content of L4-5 IVD was measured using magnetic resonance imaging (MRI). Water contents of L4-5 IVD were also determined using the wet/dry weight method after killing. Compressive stiffness of the L5 vertebral body and the L3-4 motion segment were determined. Results showed that the water content of L4-5 IVD was significantly less in the WR group than in the PF and AL groups as measured by the wet/dry weight method; likewise, MRI water content was also less in the WR group. The material stiffness of the IVD was significantly greater in the WR than in the PF and AL groups. However, there was no significant difference in material stiffness of the L5 vertebral body for the WR group in comparison with the PF and AL groups. It was also found that the stiffness of the IVD was significantly lower than that of the vertebral body. This study suggests that the dehydrated matrix of the IVD may be responsible for a stiffer disc that may lead to a less flexible spine.

The interaction between intrathecal neostigmine and GABA receptor agonists in rats with nerve ligation Injury

Nerve ligation injury may produce a pain syndrome that includes tactile allodynia. Reversal effects on tactile allodynia have been demonstrated after the intrathecal administration of gamma-aminobutyric acid (GABA) receptor agonists or cholinesterase inhibitors in rats. We examined the drug interactions between neostigmine and muscimol or baclofen in a rat model of nerve ligation injury. Rats were prepared with tight ligation of the left L5-6 spinal nerves and chronic intrathecal catheter implantation. Tactile allodynia was measured by applying von Frey filaments ipsilateral to the lesioned hindpaw. Thresholds for paw withdrawal were assessed. Neostigmine (0.3-10 microg), muscimol (0.1-10 microg), and baclofen (0.1-3.0 microg) were administered to obtain the dose-response curve and the 50% effective dose (ED(50)). Fractions of ED(50) values were administered intrathecally to establish the ED(50)s of drug combinations (neostigmine-muscimol and neostigmine-baclofen). The drug interactions were performed. Intrathecal neostigmine, muscimol, baclofen, and their combinations produced a dose-dependent increase in withdrawal threshold of the lesioned hindpaw. Both analyses revealed a synergistic interaction for the neostigmine-muscimol combination, whereas the effect of the neostigmine-baclofen combination was additive. These results suggest that the activation of both muscarinic and GABA(A) receptors is required for synergistic interaction.

IMPLICATIONS

This study indicates that drug interaction is synergistic for the neostigmine-muscimol combination, whereas the effect of the neostigmine-baclofen combination is additive. In a rat model of nerve ligation injury, neostigmine, muscimol, baclofen, and their combinations provide an antagonism on touch-evoked allodynia at the spinal level.

Formation of alkanethiol monolayer on Ge(111)

Alkanethiols, CH3(CH2)(n-1)SH, are shown to react readily with HF-treated Ge(111) surface at room temperature to form a high-quality monolayer. The resulting films are characterized by using contact angle analysis (CAA), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and high-resolution electron energy loss spectroscopy (HREELS). The octanethiol and octadecanethiol films on Ge(111) both exhibit 101 degrees and 40 degrees water and hexadecane contact angles, respectively. These values indicate that the thiol surface coverage is relatively high, and that the films possess a high degree of orientational ordering. The angle-resolved XPS analysis supports that thiols are bound to the Ge surface by Ge-S bonds at the monolayer/Ge interface. The film thickness values obtained by XPS and SE agree well with the earlier reported values on alkyl monolayers on Ge(111) prepared by Grignard reaction. On the basis of HREEL spectra taken after thermal annealing steps, the monolayers are found to be thermally stable up to 450 K. The thermal stability provides further evidence that thiols are covalently bonded to Ge(111).

Conduction block by clonidine is not mediated by alpha2-adrenergic receptors in rat sciatic nerve fibers

BACKGROUND AND OBJECTIVES

Clonidine, an alpha(2)-adrenergic agonist, has been shown to prolong local anesthesia. It appears that clonidine by itself produces conduction block by acting on peripheral nerves. However, whether clonidine-induced conduction block is mediated through alpha(2)-adrenergic receptors remains unclear. The purpose of this study was to see if clonidine's nerve-blocking action was through alpha(2)-adrenergic receptors by examining clonidine's action in the presence of alpha(2)-adrenergic antagonists.

METHODS

The compound action potentials (CAPs) evoked by electrical stimuli were recorded from the isolated rat sciatic nerve in a recording chamber. Conduction block was examined by analyzing CAPs with regard to peak amplitude and time-to-peak in the presence of clonidine alone or clonidine plus alpha(2)-adrenergic antagonist yohimbine or idazoxan.

RESULTS

Both clonidine and yohimbine produced concentration-dependent, reversible, conduction block. Based on concentration-response relationships, the 50% of effective concentration (EC(50)) were estimated to be 1.61 +/- 0.51 mmol/L (mean +/- SD) for clonidine and 51.4 +/- 27.2 micromol/L for yohimbine. A mixture of equal volumes of 2.07 mmol/L clonidine and 55.6 micromol/L yohimbine produced conduction block to a level close to the mean value between conduction blocks induced by 2.07 mmol/L clonidine alone and 55.6 micromol/L yohimbine alone. Addition of idazoxan, a more specific alpha(2)-adrenergic antagonist than yohimbine, to clonidine was without effect on clonidine-induced conduction block.

CONCLUSIONS

The results indicated that the mixture of clonidine and yohimbine, in which either drug inhibited impulse conduction, produced conduction block in an additive manner, and that clonidine-induced conduction block was not reversed by coapplication with a specific alpha(2)-adrenergic antagonist idazoxan. These data suggest that clonidine's effects likely depend on mechanisms not mediated by alpha(2)-adrenergic receptors.

Comparison of wiring techniques for bone fracture fixation in total hip arthroplasty

The objective of this study was to investigate the effect of cerclage wire position and determine the number of wires necessary to prevent crack opening and stem subsidence following a proximal femoral fracture in cementless total hip arthroplasty. A cementless femoral stem one size larger than the templated size was inserted into each femur to initiate a proximal crack. A cerclage wire was wrapped around the fracture in one of two orientations: 1) parallel to the osteotomy (PO) and 2) normal to the fracture line (NF). The femur was compressed to a load of 890 N, 1780 N and 2670 N while crack opening and stem subsidence were measured. A second cerclage wire was placed parallel to NF wire and inferior to the lesser trochanter and a third wire was placed 1 cm distal and parallel to the second wire. The loading was repeated again. The mechanical evaluation of stem subsidence were verified by various computer simulations even using four wires. We have found that placement of the cerclage wires normal to the fracture line prevents stem subsidence and crack opening better than placement of the wires parallel to the osteotomy. Three cerclage wires, placed normal to the fracture line at three locations: 1) adjacent to the superior of the lesser trochanter, 2) adjacent to the inferior of the lesser trochanter and 3) 10 mm distal to the bottom of the lesser trochanter were necessary to achieve stability under higher loads.

Truncated form of importin alpha identified in breast cancer cell inhibits nuclear import of p53

Disruption of the function of tumor suppressor proteins occasionally can be dependent on their subcellular localization. In about 40% of the breast cancer tissues, p53 is found in the cytoplasm as opposed to the nucleus, where it resides in normal breast cells. This means that the regulation of subcellular location of p53 is an important mechanism in controlling its function. The transport factors required for the nuclear export of p53 and the mechanisms of their nuclear export have been extensively characterized. However, little is known about the mechanism of nuclear import of p53. p53 contains putative nuclear localization signals (NLSs) which would interact with a nuclear transport factor, importin alpha. In this report we demonstrate that importin alpha binds to NLSI in p53 and mediates the nuclear import of p53. Reverse transcriptase-polymerase chain reaction and sequencing analyses showed that a truncated importin alpha deleted the region encoding the putative NLS-binding domain of p53, suggesting that it could not bind to NLSs of p53 proteins. Binding of importin alpha to p53 was confirmed by using yeast two-hybrid assay. When expressed in CHO-K1 cells, the truncated importin alpha predominantly localized to the cytoplasm. In truncated importin alpha expressing cells, p53 preferentially localized to cytoplasmic sites as well. A significant increase in the p21(waf1/cip1) mRNA level and induction of apoptosis were also observed in importin alpha overexpressing cells. These results strongly suggest that importin alpha functions as a component of the NLS receptor for p53 and mediates nuclear import of p53.

An analysis of drug interaction between morphine and neostigmine in rats with nerve-ligation injury

Intrathecal neostigmine reverses mechanical allodynia in humans and animals. The efficacy of morphine in a neuropathic pain state is still controversial. This study examines the antiallodynic interaction between morphine and neostigmine in a rat model of neuropathic pain. Rats were prepared with tight ligation of left L5-6 (fifth and sixth lumbar) spinal nerves and chronic intrathecal catheter implantation. Mechanical allodynia was measured by using application of von Frey hairs to the left hindpaw. Morphine (1, 3, 10, and 30 microg) and neostigmine (0.3, 1, 3, and 10 microg) were administered intrathecally to obtain the dose-response curves and the 50% effective dose (ED(50)) for each drug. ED(50) values and fractions of the ED(50) values (1/2, 1/4, and 1/8) were administered intrathecally in an equal dose ratio to establish the ED(50). Isobolographic and fractional analyses for the drug interaction were performed. Intrathecal morphine produced a moderate antagonism of the tactile allodynia. A morphine-neostigmine combination produced a dose-dependent increase in withdrawal threshold of the lesioned hind paw with reduced side effects. Both analyses revealed a synergistic interaction after the coadministration of morphine and neostigmine. These experiments suggest that the antiallodynic action of a morphine-neostigmine combination is synergistic at the spinal level.

IMPLICATIONS

This study indicates that, by using both isobolographic and fractional analyses, the antiallodynic effect of intrathecal morphine and neostigmine is synergistic when coadministered intrathecally. In a rat model of neuropathic pain, the intrathecal morphine produced a moderate antagonism on touch-evoked allodynia at the spinal level.

Ultrasound velocity and attenuation in relation to maximum trabecula stress in the patella

The ultrasound velocity and attenuation were examined in 16 sets of human patellae. The average ultrasound velocity of patella was shown to be greater in the superior/inferior direction than in the anterior/posterior and medial/lateral directions. The distribution of bone mineral density (BMD) was also examined. The BMD of the patella varied with location. BMD values were largest at the superior and lateral regions and decreased inferiorly and medially. A two-dimensional finite element analysis was performed on each patella. The maximum von Mises stress occurred along the cortical shell on the non-articular surface. The trabecular von Mises stress existed in the posterior region of the patella. Correlation study showed that patellar BMD was significantly associated with each of three directional ultrasound velocities. The relationship between BMD and ultrasound attenuation was not significant. It was also found that the ultrasound velocity and attenuation were not significantly correlated with the maximum von Mises stress.

Transfer from manual to automated sample preparation: a case study

A manual sample preparation for a controlled release capsule formulation has been converted to an automated sample preparation. Each step of the manual sample preparation was evaluated as to its feasibility for automation in terms of precision, carryover, filter selection and other critical issues. Although most steps of the manual method were easily translated to the automated procedure, certain 'simple' details such as filter selection, sample storage, and the conversion from volumetric to gravimetric measurements needed closer investigation.

Management of difficult airways with a laryngeal mask airway under propofol anaesthesia

We report four cases of difficult airway managed with a laryngeal mask airway (LMA) under propofol anaesthesia; this method was chosen to minimize psychological and physical trauma. Case 1 was a boy with dermatomyositis; Case 2, a girl wearing a base ring of a stereotactic frame; Case 3, a boy with Treacher-Collins syndrome; Case 4, a boy with Goldenhar syndrome. They were anaesthesized with propofol and though spontaneous ventilation became shallower, or apnoea occurred, the stimulus of inserting an LMA awakened the patient and caused more active spontaneous ventilation while a patent airway was established by the LMA. All tracheal intubations were performed smoothly and without delay through the LMA, and we believe that psychological and physical trauma was thus minimized.

The antiallodynic effects of intrathecal cholinesterase inhibitors in a rat model of neuropathic pain

BACKGROUND

This study determined the effect of intrathecally administered cholinesterase inhibitors, edrophonium and neostigmine, on nerve injury-induced, touch-evoked allodynia and identified the pharmacologic characteristics of this action.

METHODS

Rats were prepared with tight ligation of the left L5 and L6 spinal nerves and with lumbar intrathecal catheters fitted for long-term monitoring. Edrophonium (3, 10, 30, or 100 microg) or neostigmine (0.3, 1, 3, or 10 microg) was administered intrathecally. Tactile allodynia and motor weakness were assessed. To evaluate the pharmacologic characteristics of the activity, a muscarinic receptor antagonist or a nicotinic receptor antagonist was administered intrathecally before edrophonium or neostigmine was injected. To compare the action of subtype antagonists, the M1 muscarinic receptor antagonist pirenzepine, the M2 antagonist methoctramine, the M3 antagonist 4-DAMP (diphenylacetoxy-N-methypiperidine), and the M4 antagonist tropicamide were administered intrathecally before cholinesterase inhibitors were injected.

RESULTS

Intrathecal edrophonium or neostigmine produced a dose-dependent antagonism of the touch-evoked allodynia. Neostigmine resulted in a moderate effect on motor weakness at doses of 3 and 10 microg. Pretreatment with intrathecal atropine but not mecamylamine yielded a complete antagonism of the effects of the cholinesterase inhibitors. In addition, antiallodynia produced by edrophonium (100 microg) was reversed by pretreatment with methoctramine, 4-DAMP, tropicamide, and pirenzepine. In the neostigmine (10 microg) group, only the M1 antagonist pirenzepine had a moderate effect on reversal of increased allodynic threshold.

CONCLUSIONS

These experiments suggest that intrathecal edrophonium or neostigmine produces an antagonism on touch-evoked allodynia at the spinal level in a rat model of neuropathic pain and that the antiallodynic action of cholinesterase inhibitors is probably mediated by a spinal muscarinic system, especially at the M1 receptor subtype.

Cerclage wiring technique after proximal femoral fracture in total hip arthroplasty

Cerclage wires have been used to stabilize proximal femoral cracks after stem insertion in cementless total hip arthroplasty. The objective of this study was to determine the optimal number and orientation of cerclage wires necessary to prevent stem subsidence and crack propagation. The crack was stabilized by 1, 2, or 3 wires placed either normal to the femoral neck axis or normal to the crack. The femora were compressed to 2,670 N while measuring crack opening and stem subsidence. Wires placed normal to the crack allowed less stem subsidence by 3.17 mm and less crack opening by 1.55 mm compared with wires placed normal to the neck. The addition of multiple wires reduced subsidence by 50% and reduced crack opening to <1 mm. Medial and anterior calcar cracks are best stabilized by at least 2 cerclage wires that are placed normal to the crack.

Increased glyceraldehyde-3-phosphate dehydrogenase gene expression in human cervical cancers

OBJECTIVE

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a classical glycolytic protein. A higher level of GAPDH mRNA was found in lung, pancreas, and prostate cancers, but in cervical carcinoma there have not been any reports about the level of GAPDH gene expression. So, we tried to investigate the GAPDH gene expression patterns in cervical carcinomas compared to normal cervical tissues, and the relationships between the expression levels of this gene and conventional clinicopathological parameters were evaluated.

MATERIALS AND METHODS

In this study, 25 normal exocervical tissues, 35 primary untreated cervical cancer tissues, 2 cervical cancer cell lines, and 2 post-nude-mouse-derived cervical cancer cell lines were subjected to Northern blot analyses for GAPDH gene expression.

RESULTS

Northern blot analyses revealed that the levels of GAPDH gene expression were elevated in 34 of 35 (97%) cervical carcinoma tissues and all of the 4 cervical cancer cell lines compared to normal cervical tissues. The levels of GAPDH gene expression were more prominent in rapidly proliferating cervical carcinoma cells. The levels of the GAPDH gene expressions in cervical cancer tissues were not associated with conventional clinicopathological parameters including clinical stage, histological type, and degree of differentiation.

CONCLUSION

These results suggest that increased GAPDH gene expression is characteristic of human cervical carcinomas and that rapidly proliferating carcinoma cells express more enhanced GAPDH gene. Future gene therapy using antisense oligodeoxynucleotide directed against GAPDH mRNA might be another therapeutic tool for human uterine cervical carcinoma.

Dependence of broadband ultrasound attenuation on the elastic anisotropy of trabecular bone

The effect of trabecular elastic anisotropy on broadband ultrasound attenuation (BUA) and bone mineral density (BMD) was investigated with human and bovine cubic cancellous bones. Ultrasonic parameters describing trabecular anisotropy were found from the three orthogonal ultrasound velocities. BMD was measured using quantitative computed tomography. Three elastic anisotropy ratios were compared to BUA in all three directions and to BMD. The combined effect of anisotropic characteristics and BMD was also correlated with BUA. The results showed that the anisotropy ratios were significantly related to BUA (p < 0.05). There was, however, no correlation between BMD and the elastic anisotropy ratios. The combination of BMD and the anisotropy produced a significantly enhanced relationship with BUA.

Loss of heterozygosity of the retinoblastoma and p53 genes in primary cervical carcinomas with human papillomavirus infection

OBJECTIVE

Paired DNA samples from 55 primary uterine cervical carcinomas and normal bloods were studied for chromosomal allelic loss (loss of heterozygosity; LOH) of the retinoblastoma (Rb) and p53 gene loci by polymerase chain reaction (PCR) or PCR-restriction fragment length polymorphism analysis. All the study samples contained at least one of the oncogenic human papillomavirus (HPV) type 16 and/or 18 sequences. And the relationships between allelic losses of these genes and conventional clinicopathological parameters were evaluated.

METHODS

In order to detect LOH of the Rb gene in cervical cancers, we analyzed four polymorphic intronic sites (intron 1, 17, 20, and 25) of the Rb gene and one additional microsatellite near the Rb locus (D13S118). For detection of the LOH in p53, three intragenic polymorphisms (exon 1, exon 4, intron 6) and one microsatellite distal to the p53 gene (D17S5) were examined.

RESULTS

By analyzing this system, we could increase the heterozygosity of the Rb and p53 loci up to 0.91 and 1, respectively. The observed allelic loss rates of the Rb and p53 loci in informative cases were 14% (7/50) and 5.5% (3/55), respectively. The patients with LOH at the D13S118 locus also had the allelic loss of the Rb gene, whereas only one of the four patients with LOH at the D17S5 locus showed a concomittant allelic loss of the p53 gene. The frequency of cervical cancer with one LOH at the Rb or p53 loci was 20% (11/55). No shifted bands were observed in the PCR-single-strand conformation polymorphism analysis of the p53 gene. The LOH of the Rb or p53 gene was not significantly associated with other parameters including clinical stage, histological type, degree of differentiation, status of HPV infection, and p53 gene mutation.

CONCLUSION

Concerning the results above, we conclude that the allelic imbalance of the Rb or p53 gene itself is not implicated as a major contributing factor in the malignant transformation or the tumor progression in HPV-positive uterine cervical cancers.

A comparison between the patella and the calcaneus using ultrasound velocity and attenuation as predictors of bone mineral density

The bone mineral density (BMD), ultrasound velocity (UV) and attenuation were examined in sixteen matched sets of human patellae and calcanei. For the sixteen calcanei, BMD was strongly correlated with all ultrasound parameters. Calcaneal UV appeared to be inferior to attenuation in the ability to predict BMD. For the sixteen patellae, the average UV was found to be greater in the superior/inferior direction than in the anterior/posterior and medial/lateral directions. It was found that patella BMD was significantly correlated with each of three directional ultrasound velocities. The relationship between BMD and ultrasound attenuation parameters was not significant in the patella. A comparative study of the two different bone sets demonstrated that the BMDs of the patella and calcaneus were significantly correlated with each other. Ultrasound velocity of calcaneus, measured in the medial/lateral direction, was not significantly associated with any of three directional ultrasound velocities in the patella. Similarly, ultrasound attenuation parameters of calcaneus were not significantly correlated with those of patella. The present study also demonstrated evidence that when predicting BMDs at their respective sites using ultrasound, the calcaneus appeared to be superior to the patella.

Direct enantiomeric separations by high performance liquid chromatography using cyclodextrins

Due to their identical chemical and physical properties, the separation of enantiomers has been considered one of the most difficult challenges in chemistry from both an analytical or a preparative viewpoint. With the development and commercialization of many new or improved chiral stationary phases and chiral additives, interest in enantiomeric separation by HPLC has grown tremendously in the last two decades. Cyclodextrins and modified cyclodextrins are widely used chiral selectors. They are used as either the chiral stationary phases, as chiral mobile phase additives, or as chiral counter-ions. This review describes the historical development of derivatized and underivatized cyclodextrins in HPLC and their various applications.