Pulse Oximetry: A Non-Invasive, Novel Marker for the Quality of Chest Compressions in Porcine Models of Cardiac Arrest

Objective

Pulse oximetry, which noninvasively detects the blood flow of peripheral tissue, has achieved widespread clinical use. We have noticed that the better the quality of cardiopulmonary resuscitation (CPR), the better the appearance of pulse oximetry plethysmographic waveform (POP). We investigated whether the area under the curve (AUC) and/or the amplitude (Amp) of POP could be used to monitor the quality of CPR.

Design

Prospective, randomized controlled study.

Setting

Animal experimental center in Peking Union Medical Collage Hospital, Beijing, China.

Subjects

Healthy 3-month-old male domestic swine.

Interventions

34 local pigs were enrolled in this study. After 4 minutes of untreated ventricular fibrillation, animals were randomly assigned into two resuscitation groups: a “low quality” group (with a compression depth of 3cm) and a “high quality” group (with a depth of 5cm). All treatments between the two groups were identical except for the depth of chest compressions. Hemodynamic parameters [coronary perfusion pressure (CPP), partial pressure of end-tidal carbon dioxide (P_ETCO₂)] as well as AUC and Amp of POP were all collected and analyzed.

Measurements and Findings

There were statistical differences between the “high quality” group and the “low quality” group in AUC, Amp, CPP and P_ETCO₂ during CPR (P<0.05). AUC, Amp and CPP were positively correlated with P_ETCO₂, respectively (P<0.01). There was no statistical difference between the heart rate calculated according to the POP (F_CPR) and the frequency of mechanical CPR at the 3^rd minute of CPR. The F_CPR was lower than the frequency of mechanical CPR at the 6^th and the 9^th minute of CPR.

Conclusions

Both the AUC and Amp of POP correlated well with CPP and P_ETCO₂ in animal models. The frequency of POP closely matched the CPR heart rate. AUC and Amp of POP might be potential noninvasive quality monitoring markers for CPR.

[The effect of blood volume change on the accuracy of pulse contour cardiac output]

OBJECTIVE

To study the accuracy of pulse contour cardiac output (PCCO) during blood volume change.

METHODS

Hemorrhagic shock model was made in twenty dogs followed by volume resuscitation. Two PiCCO catheters were placed into each model to monitor the cardiac output (CO). One of catheters was used to calibrate CO by transpulmonary thermodilution technique (COTP) (calibration group), and the other one was used to calibrate PCCO (none-calibration group). In the hemorrhage phase, calibration was carried out each time when the blood volume dropped by 5 percents in the calibration group until the hemorrhage volume reached to 40 percent of the basic blood volume. Continuous monitor was done in the none-calibration group.Volume resuscitation phase started after re-calibration in the two groups. Calibration was carried out each time when the blood equivalent rose by 5 percents in calibration group until the percentage of blood equivalent volume returned back to 100. Continuous monitor was done in none-calibration group. COTP, PCCO, mean arterial pressure (MAP), systemic circulation resistance (SVR), global enddiastolic volume (GEDV) were recorded respectively in each time point.

RESULTS

(1) At the baseline, COTP in calibration group showed no statistic difference compared with PCCO in none-calibration group (P >0.05). (2) In the hemorrhage phase, COTP and GEDV in calibration group decreased gradually, and reached to the minimum value (1.06 ± 0.57) L/min, (238 ± 93) ml respectively at TH8. SVR in calibration group increased gradually, and reached to the maximum value (5 074 ± 2 342) dyn · s · cm⁻⁵ at TH6. However, PCCO and SVR in none-calibration group decreased in a fluctuating manner, and reached to the minimum value (2.42 ± 1.37) L/min, (2 285 ± 1 033) dyn · s · cm⁻⁵ respectively at TH8. COTP in the calibration group showed a significant statistic difference compared with PCCO in the none-calibration group at each time point (At TH1-8, t values were respectively -5.218, -5.495, -4.639, -6.588, -6.029, -5.510, -5.763 and -5.755, all P < 0.01). From TH1 to TH8, the difference in percentage increased gradually. There were statistic differences in SVR at each time point between the two groups (At TH1 and TH4, t values were respectively 2.866 and 2.429, both P < 0.05, at TH2 - TH3 and TH5 - TH8, t values were respectively 3.073, 3.590, 6.847, 8.425, 6.910 and 8.799, all P < 0.01). There was no statistic difference in MAP between the two groups (P > 0.05). (3) In the volume resuscitation phase, COTP and GEDV in the calibration group increased gradually. GEDV reached to the maximum value ((394±133) ml) at TR7, and COTP reached to the maximum value (3.15 ± 1.42) L/min at TR8. SVR in the calibration group decreased gradually, and reached to the minimum value (3 284 ± 1 271) dyn · s · cm⁻⁵ at TR8. However, PCCO and SVR in the none-calibration group increased in a fluctuating manner. SVR reached to the maximum value (8 589 ± 4 771) dyn · s · cm⁻⁵ at TR7, and PCCO reached to the maximum value (1.35 ± 0.70) L/min at TR8. COTP in the calibration group showed a significant statistic difference compared with PCCO in the none-calibration group at each time point (At TR1-8, t values were respectively 8.195, 8.703, 7.903, 8.266, 9.600, 8.340, 8.938, 8.332, all P < 0.01). From TR1 to TR8, the difference in percentage increased gradually. There were statistic differences in SVR at each time point between the two groups (At TR1, t value was -2.810, P < 0.05, at TR2-8, t values were respectively -6.026, -6.026, -5.375, -6.008, -5.406, -5.613 and -5.609, all P < 0.05). There was no statistic difference in MAP between the two groups (P > 0.05).

CONCLUSION

PCCO could not reflect the real CO in case of rapid blood volume change, which resulting in the misjudgment of patient's condition. In clinical practice, more frequent calibrations should be done to maintain the accuracy of PCCO in rapid blood volume change cases.

Analysis of quantitative trait loci for main plant traits in soybean

Plant traits are important indices for regulating and controlling yield ability in soybean varieties. It is important to comprehensively study the quantitative trait locus (QTL) mapping for soybean plant traits, cloning related genes, and marker assistant breeding. In this study, 236 F2 generation plants and a derivative group were constructed by using Jiyu50 and Jinong18, obtained from Jilin Province. A total of 102 simple sequence repeat markers were used to construct a genetic linkage map. With 2 years of molecular and phenotypic data, QTL analyses and mapping were conducted for soybean maturity, plant height, main stem node, main stem branch, seed weight per plant, and more. Five main plant traits were analyzed via inclusive composite interval mapping using QTL IciMapping v2.2. Using one-dimensional scanning, a total of 30 QTLs were detected and distributed across 1 (A1), 4 (C2), and 12 (G). There were 9 linkage groups, including 16 major QTLs. Using two-dimensional scanning, 7 pairs of epistatic QTL interactions for maturity and plant height were detected in the soybean.

[The role of pulse oximetry plethysmographic waveform monitoring as a marker of restoration of spontaneous circulation:a pilot study]

OBJECTIVE

To investigate the feasibility of using pulse oximetry plethysmographic waveform (POP) to identify the restoration of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR).

METHODS

An observational research was conducted. A porcine model of ventricular fibrillation (VF) arrest was reproduced. After 3 minutes of untreated VF, animals received CPR according to the latest CPR guidelines, providing chest compressions to a depth of 5 cm with a rate of 105 compressions per minute and instantaneous mechanical ventilation. After 2 minutes of CPR, animals were defibrillated with 100 J biphasic, followed by continuous chest compressions. Data of hemodynamic parameters, partial pressure of end-tidal carbon dioxide (PETCO₂) and POP were collected. The change in POP was observed, and the characteristics of changes of the waves were recorded during the peri-CPR period using the time and frequency domain methods.

RESULTS

VF was successfully induced in 6 pigs, except 1 death in anesthesia induction period. (1) After VF, invasive blood pressure waveform and POP of the animals disappeared. PETCO₂was (18.83 ± 2.71) mmHg (1 mmHg=0.133 kPa), and diastolic arterial pressure was (23.83 ± 5.49) mmHg in compression stage. Animals attained ROSC within 1 minute after defibrillation, with PETCO₂[(51.83 ± 9.35) mmHg] and diastolic arterial pressure [(100.67 ± 10.97) mmHg] elevated significantly compared with that of compression stage (t1 = 8.737, t2 = 25.860, both P = 0.000), with appearance of arterial blood pressure waveform.(2) Characteristic changes in POP were found in all experimental animals. During the stages of induced VF, compression, ROSC, and compression termination, POP showed characteristic waveform changes. POP showed disappearance of waveform, regular compression wave, fluctuation hybrid and stable pulse wave in time domain method; while in the frequency domain method waveform disappearance, single peak of compression, double or fusion peak and single peak of pulse were observed.

CONCLUSIONS

Analysis of POP using time and frequency domain methods could not only quickly detect cardiac arrest, but also show a role as a feasible, non-invasive marker of ROSC during CPR.

Genetic analysis of the major gene plus polygene model in soybean resistance to Leguminivora glycinivorella

In order to investigate the genetic characteristics of soybean Leguminivora glycinivorella resistance and to improve soybean resistance insectivorous breeding efficiency by applying the multi-generation joint analysis method of the major gene plus polygene model, 5 pedigrees and generations (P1, F1, P2, F2, and F2:3) were used as the materials to perform the soybean L. glycinivorella resistance multi-generation joint analysis. The results showed that soybean resistance to L. glycinivorella was controlled and inherited by an additive major gene plus additive, dominant polygene. The major gene had a negative additive effect (d = -0.1633). The combination of the anti-L. glycinivorella genes showed negative heterosis. Because the polygene additive effects were positive, the polygene effects would increase the insect herbivory rate in the F1 generation. This hybrid combination showed an insect herbivory rate polygenic heritability of 21.9556 and 54.3490% in the F2 and F2:3 pedigrees, which presented a high heritability. Therefore, it was appropriate to perform the selective breeding of the insect herbivory rate in the late generation.

[Effects of acetamide at different doses on expression of amino acids in cerebral cortex of rats with acute tetramine poisoning]

OBJECTIVE

To investigate the effects of acetamide at different doses on the expression of inhibitory amino acids (gamma-aminobutyric acid, GABA) and excitatory amino acid (glutamate, Glu) in the cerebral cortex of rats with acute tetramine (TET) poisoning.

METHODS

Eighty Sprague-Dawley rats (SPF) were randomly divided into five groups, with 16 rats in each group: saline control group, dimethyl sulfoxide (DMSO) control group, TET exposure group, high-dose (2.8 g/kg/d) acetamide treatment group, and super-high-dose (5.6 g/kg/d) acetamide treatment group. Rats in the exposure group and treatment groups were exposed to TET by intragastric administration after fasting, and were then intramuscularly injected with saline or different doses of acetamide in the following 5 days. The cortex of the temporal lobe was collected at 3 h, 12 h, 48 h, or 7 d after treatment. The expression levels of GABA and Glu in the cortex of the temporal lobe were determined by average optical density (OD) values in immunohistochemistry.

RESULTS

1) Expression of GABA: The OD value of GABA in TET exposure group started to increase at 12 h after treatment, reached the peak at 48 h, and decreased to the normal level at 7 d. In the high-dose acetamide treatment group, the increase in OD at 12 h was not so significant as that in the TET exposure group, OD value decreased to the normal level at 48 h and was lower than that in the exposure group, and the changes were more like those in the control groups. In the super-high-dose acetamide treatment group, OD value began to increase significantly at 3 h and was significantly higher than that in the TET exposure group (P < 0.01), it reached the peak at 12 h, and was restored to the normal value at 48 h. 2) Expression of Glu: The OD value of Glu in TET exposure group at 3 h after treatment was significantly lower than those in the two control groups, it increased gradually from 12 h to 48 h, and recovered to the normal level at the 7th d. The changes in the high-dose acetamide treatment group were similar to those in the TET exposure group, but became more like those in the control groups after 48 h; the OD value in super-high-dose acetamide treatment group was significantly higher than that in the TET exposure group at 3 h after treatment (P < 0.01), while no significant difference was found at 12 h; it was significantly lower than those of all other groups at 48 h and 7 d (P < 0.01).

CONCLUSIONS

Treatment with high dose of acetamide has some curative effect on TET poisoning-induced central nervous lesion, while the effect of super-high-dose acetamide on expression of neurotransmitters is too complex to evaluate.

[Effect of acetamide on histopathology in cerebral cortex of rats with tetramine poisoning]

OBJECTIVE

To observe the effect of different doses of acetamide on the histopathology in the cerebral cortex of rats with tetramine (TET) poisoning and to provide a basis for the treatment of fluoroacetamide poisoning with acetamide.

METHODS

Eighty clean Sprague-Dawley rats were randomly divided into five groups: saline control group,dimethylsulfoxide water solution control group,TET poisoning group, acetamide (2.88 g/kg/d) treatment group, and acetamide (5.68 g/kg/d) treatment group, with 16 rats in each group. Rats in the poisoning group and treatment groups were poisoned with TET by intragastric administration after fasting; then, saline was injected intramuscularly into rats of the poisoning group, and different doses of acetamide were injected intramuscularly into rats of treatment groups; the course of treatment was 5 d. At 3 h, 12 h, 48 h, and 7 d after treatment, the cerebral cortex was harvested from rats in each group, and the histopathological changes in the cerebral cortex were evaluated under light and electron microscopes.

RESULTS

The light microscopy showed that the TET poisoning group had hypoxia changes in the cerebral cortex, which worsened over time; the treatment groups had reduced hypoxia changes, and the acetamide (2.88 g/kg/d) treatment group had more reduction than the acetamide (5.68 g/kg/d) treatment group. The electron microscopy showed that the apoptosis of neuronal cells were the main pathological changes in the TET poisoning group; the treatment groups had reduced apoptotic changes, and the acetamide (2.88 g/kg/d) treatment group had more reduction than the acetamide (5.68 g/kg/d) treatment group.

CONCLUSION

No pathological changes associated with the synergistic toxic effect of acetamide and TET are found in the cerebral cortex. Acetamide (2.88 g/kg/d) could reduce central nervous lesions, but the efficacy is not improved after increasing the dose. For patients who cannot be identified with TET or fluoroacetamide poisoning, acetamide could be considered for treatment.

Cloning and functional prediction of differentially expressed genes in the leaves of Glycine max parents and hybrids at the seedling stage

Here, we compare the molecular mechanism of soybean heterosis through the differential expression of basic cloning. Specifically, we cloned 22 differentially expressed cDNA fragments from hybrid combinations of Jilin 38 x EXP (which had obvious yield advantages) and their parents. In addition, we compared the homology of these fragments and predicted their functions. Cloning differentially expressed genes included the identification of the calmodulin binding protein, 18S ribosomal gene, 26S ribosomal gene, soybean satellite DNA, soybean acid phosphatase, soybean chlorophyll a/b-binding protein II (Cab-6) gene, soybean chloroplast PI 437654 gene, soybean PPR protein gene, and other fragments with unknown functions. In conclusion, the cloning and functional prediction of differentially expressed soybean genes in this study is anticipated to provide valuable information for studies on the molecular mechanism of heterosis.

PLGA/TCP composite scaffold incorporating bioactive phytomolecule icaritin for enhancement of bone defect repair in rabbits

Bone defect repair is challenging in orthopaedic clinics. For treatment of large bone defects, bone grafting remains the method of choice for the majority of surgeons, as it fills spaces and provides support to enhance biological bone repair. As therapeutic agents are desirable for enhancing bone healing, this study was designed to develop such a bioactive composite scaffold (PLGA/TCP/ICT) made of polylactide-co-glycolide (PLGA) and tricalcium phosphate (TCP) as a basic carrier, incorporating a phytomolecule icaritin (ICT), i.e., a novel osteogenic exogenous growth factor. PLGA/TCP/ICT scaffolds were fabricated as PLGA/TCP (control group) and PLGA/TCP in tandem with low/mid/high-dose ICT (LICT/MICT/HICT groups, respectively). To evaluate the in vivo osteogenic and angiogenic potentials of these bioactive scaffolds with slow release of osteogenic ICT, the authors established a 12 mm ulnar bone defect model in rabbits. X-ray and high-resolution peripheral quantitative computed tomography results at weeks 2, 4 and 8 post-surgery showed more newly formed bone within bone defects implanted with PLGA/TCP/ICT scaffolds, especially PLGA/TCP/MICT scaffold. Histological results at weeks 4 and 8 also demonstrated more newly mineralized bone in PLGA/TCP/ICT groups, especially in the PLGA/TCP/MICT group, with correspondingly more new vessel ingrowth. These findings may form a good foundation for potential clinical validation of this innovative bioactive scaffold incorporated with the proper amount of osteopromotive phytomolecule ICT as a ready product for clinical applications.

Constant Temperature Microfeature Embossing with Slowly Crystallizing Polymers

A new microfeature embossing method utilizing a slowly crystallizing mechanism was investigated to eliminate thermal cycling, as needed in standard hot embossing. Poly(ethylene terephthalate) was used as a model system for demonstration. Due to its slow crystallization, amorphous PET film can be made by melt casting onto a chilled roll. The resulting amorphous film was embossed at a constant temperature of 180°C for a period of time comparable to or longer than the polymer's half-time of crystallization. During constant-temperature embossing, the film is softened first, caused by rubber softening of the amorphous phase, and is then hardened, resulting from the crystallization of the amorphous phase at the same embossing temperature. Since the embossed film is hardened under the constant mold temperature, no cooling is needed. Selected micro features, including circular microchannels and high aspect ratio microribs, were consistently patterned using a total cycle time about 40s. The embossed films were characterized using DSC and rotational rheometry to elucidate the physical mechanism for softening and hardening the polymer during constant-temperature embossing.

Overexpression of multidrug resistance-associated protein 2 in the brain of pentylenetetrazole-kindled rats

Clinical studies and animal models have shown that pharmacoresistant epilepsy is partly due to the overexpression of ATP-binding cassette transporters at the brain. The purposes of the study were to investigate the function and expression of multidrug resistance-associated protein 2 (Mrp2) in the brain of pentylenetetrazole (PTZ)-kindled rats, and the effect of the altered Mrp2 function and expression on phenytoin (PHT) distribution in the brain. Kindled rats were developed by sub-convulsive dose of PTZ (33 mg/kg, every day, intraperitoneal (i.p.)) for 28 days. Mrp2 expression and function were measured by western blot and bromosulfophthalein (BSP) distribution in the brain. PHT concentrations in the brain of PTZ-kindled rats were measured alone or with co-administration of probenecid (50mg/kg). Further experiment was designed to investigate whether PHT treatment prevented the up-regulated brain Mrp2 expression and function induced by PTZ-kindling. The results showed that PTZ-kindling resulted in an increase of Mrp2 level in the hippocampus and cortex of rats, accompanied by significant decreases in the brain-to-plasma concentration ratio of BSP. PTZ-kindling also decreased PHT levels in the hippocampus and cortex without altering PHT concentrations in plasma, resulting in a lower brain-to-plasma concentration ratio of PHT. Co-administration of probenecid increased the brain-to-plasma ratio of BSP and PHT in the brain of both normal and PTZ-kindled rats. A 14-day PHT treatment prevented the up-regulation of Mrp2 expression and function induced by PTZ-kindling, accompanied by increases of PHT concentrations in the brain and good anticonvulsive effects. The present study demonstrated that chronic PTZ-kindling increased Mrp2 expression and function in the rat brain, and the up-regulation partly came from epileptic seizure.

Impaired bone healing in rabbits with steroid-induced osteonecrosis

Corticosteroids are prescribed for the treatment of many medical conditions and their adverse effects on bone, including steroid-associated osteoporosis and osteonecrosis, are well documented. Core decompression is performed to treat osteonecrosis, but the results are variable. As steroids may affect bone turnover, this study was designed to investigate bone healing within a bone tunnel after core decompression in an experimental model of steroid-associated osteonecrosis. A total of five 28-week-old New Zealand rabbits were used to establish a model of steroid-induced osteonecrosis and another five rabbits served as controls. Two weeks after the induction of osteonecrosis, core decompression was performed by creating a bone tunnel 3 mm in diameter in both distal femora of each rabbit in both the experimental osteonecrosis and control groups. An in vivo micro-CT scanner was used to monitor healing within the bone tunnel at four, eight and 12 weeks postoperatively. At week 12, the animals were killed for histological and biomechanical analysis.

In the osteonecrosis group all measurements of bone healing and maturation were lower compared with the control group. Impaired osteogenesis and remodelling within the bone tunnel was demonstrated in the steroid-induced osteonecrosis, accompanied by inferior mechanical properties of the bone.

We have confirmed impaired bone healing in a model of bone defects in rabbits with pulsed administration of corticosteroids. This finding may be important in the development of strategies for treatment to improve the prognosis of fracture healing or the repair of bone defects in patients receiving steroid treatment.

Single-primer PCR correction: a strategy for false-positive exclusion

Polymerase chain reaction (PCR) technology plays an important role in molecular biology research, but false-positive and nonspecific PCR amplification have plagued many researchers. Currently, research on the optimization of the PCR system focuses on double-primer-based PCR products. This research has shown that PCR amplification based on single-primer binding to the DNA template is an important contributing factor to obtaining false-positive results, fragment impurity, and nonspecific fragment amplification, when the PCR conditions are highly restricted during PCR-based target gene cloning, detection of transgenic plants, simple-sequence repeat marker-assisted selection, and mRNA differential display. Here, we compared single- and double-primer amplification and proposed "single-primer PCR correction"; improvements in PCR that eliminate interference caused by single-primer-based nonspecific PCR amplification were demonstrated and the precision and success rates of experiments were increased. Although for some kinds of experiments, the improvement effect of single-primer PCR correction was variable, the precision and success rate could be elevated at 12-50% in our experiment by this way.

Problems with and a system to eliminate single-primer PCR product contamination in simple sequence repeat molecular marker-assisted selection in soybean

Polymerase chain reaction (PCR) provides a foundation for simple sequence repeat molecular marker-assisted selection (SSR MAS) in soybean. This PCR system and its various conditions have been optimized by many researchers. However, current research on the optimization of the PCR system focuses on double-primer PCR products. We compared single- and double-SSR primer PCR products from 50 soybean samples and found that the use of single-PCR primers in the reaction system can lead to amplified fragments of portions of the SSR primers in the PCR process, resulting in both false-positives and fragment impurity of double-primer PCR amplification, inconvenient for subsequent analysis. We used "single-primer PCR correction" to eliminate interference caused by single-primer nonspecific PCR amplification and improve PCR quality. Using this method, the precision and success rates of SSR MAS in soybean can be increased.

Functional magnetic resonance imaging study on dysphagia after unilateral hemispheric stroke: a preliminary study

BACKGROUND

Swallowing dysfunction is common and disabling after acute stroke; however, the mechanism of dysphagia or recovery of swallowing from dysphagia remains uncertain. The purpose of this study was to explore cerebral activation of swallowing in dysphagia using functional MRI (fMRI) to compare the functional anatomy of swallowing in unilateral hemispheric stroke patients and healthy adults.

METHODS

In total, five left hemispheric stroke patients with dysphagia, five right hemispheric stroke patients with dysphagia and 10 healthy controls were examined with event related fMRI while laryngeal swallow related movements were recorded. Data were processed using the general linear model.

RESULTS

A multifocal cerebral representation of swallowing was identified predominantly in the left hemisphere, in a bilateral and asymmetrical manner. Cerebral activation during swallowing tasks was localised to the precentral, postcentral and anterior cingulate gyri, insula and thalamus in all groups. Activation of volitional swallowing in dysphagic unilateral hemispheric stroke patients might require reorganisation of the dominant hemispheric motor cortex, or a compensatory shift in activation to unaffected areas of the hemisphere.

CONCLUSIONS

The results indicate that unilateral stroke of either cerebral hemisphere can produce dysphagia. Effective recovery is associated with cerebral activation related to cortical swallowing representation in the compensating or recruited areas of the intact hemisphere. Functional MRI is a useful method for exploring the spatial localisation of changes in neuronal activity during tasks that may be related to recovery. Therefore, the subsequent information gleaned from changes in neural plasticity could be useful for assessing the prognosis of dysphagic stroke.

Neuroplasticity of face primary motor cortex control of orofacial movements

We have carried out a series of studies to address the role of the face primary motor area (MI) in the cerebral cortex in trained or semi-automatic orofacial motor behaviours and in behavioural adaptations to an altered oral environment. These studies have utilized intracortical microstimulation (ICMS), reversible cold block or single neurone recordings in face MI. Our studies in monkeys have revealed that face MI plays a strategic role in elemental and learned motor behaviours and in certain aspects of chewing and swallowing. Furthermore, successful training of awake monkeys in a novel tongue-protrusion task is associated with significant neuroplastic changes in face MI. These findings in monkeys are supported by correlated findings in humans which have revealed significantly enhanced corticomotoneuronal excitability when humans learn the novel tongue-protrusion task. Our related ICMS studies in rats reveal that trimming or extraction of the rat's lower incisors or damage to the rat's lingual nerve can result in significant changes in the MI representations of the tongue or jaw muscles. These various findings suggest that the face MI is important in orofacial motor skill acquisition and adaptation to an altered occlusion or loss of teeth or lingual sensory function, and that it reflects dynamic and modifiable constructs that are modelled by behaviourally significant experiences and that are critical to learning and adaptive processes.

Thermolabile phenotype of carnitine palmitoyltransferase II variations as a predisposing factor for influenza-associated encephalopathy

To assess the etiology of influenza-associated encephalopathy (IAE), a surveillance effort was conducted during 2000-2003 in South-West Japan. All fatal and handicapped patients except one (4/34 patients) exhibited a disorder of mitochondrial beta-oxidation evoked by the inactivated carnitine palmitoyltransferase II (CPT II) with transiently elevated serum acylcarnitine ratios (C(16:0) + C(18:1))/C(2) > 0.09 during high-grade fever. Analyses of genotypes and allele compositions of CPT II revealed a thermolabile phenotype of compound heterozygotes for [1055T > G/F352C] and [1102G > A/V368I], which shows a higher frequency in IAE patients than healthy volunteers (P < 0.025). The thermolabile phenotype of CPT II variations may be a principal genetic background of IAE in Japanese.

Osteogenic Cells Derived From Embryonic Stem Cells Produced Bone Nodules in Three-Dimensional Scaffolds

An approach for 3D bone tissue generation from embryonic stem (ES) cells was investigated. The ES cells were induced to differentiate into osteogenic precursors, capable of proliferating and subsequently differentiating into bone-forming cells. The differentiated cells and the seeded scaffolds were characterized using von Kossa and Alizarin Red staining, electron microscopy, and RT-PCR analysis. The results demonstrated that ES-derived bone-forming cells attached to and colonized the biocompatible and biodegradable scaffolds. Furthermore, these cells produced bone nodules when grown for 3-4 weeks in mineralization medium containing ascorbic acid and beta-glycerophosphate both in tissue culture plates and in scaffolds. The differentiated cells also expressed osteospecific markers when grown both in the culture plates and in 3D scaffolds. Osteogenic cells expressed alkaline phosphatase, osteocalcin, and osteopontin, but not an ES cell-specific marker, oct-4. These findings suggest that ES cell can be used for in vitro tissue engineering and cultivation of graftable skeletal structures.

Development of a two-stage flexible fibre biofilm reactor for treatment of food processing wastewater

Biofilm (or attached growth) reactors can be effectively used to treat organic wastewater from various industries such as food processing industry. They have a number of advantages including high organic loading rates (OLRs) and improved operational stability. A flexible fibre biofim reactor (FFBR) has been developed for efficient and cost effective treatment of food processing wastewater. In the process, simple flexible fibre packing with a very high specific surface area is used as support for microorganisms. The COD removal efficiencies for a range of OLRs have been studied. The FFBR can support an increasingly high OLR, but with a corresponding decrease in the COD removal efficiency. Therefore, a two-stage FFBR was developed to increase the treatment efficiency for systems with high OLRs. Experimental results indicated that a high overall COD removal efficiency could be achieved. At an influent COD of about 2700 mg/L and an OLR of 7.7 kgCOD/m3d, COD removal efficiencies of 76% and 82% were achieved in the first and the second stage of the reactor, respectively. The overall COD removal efficiency was 96%. Therefore, even for wastewater samples with high organic strength, high quality treated effluents could be readily achieved by the use of multiple stage FFBRs.

An equivalent current source model and laplacian weighted minimum norm current estimates of brain electrical activity

We have developed a method for estimating the three-dimensional distribution of equivalent current sources inside the brain from scalp potentials. Laplacian weighted minimum norm algorithm has been used in the present study to estimate the inverse solutions. A three-concentric-sphere inhomogeneous head model was used to represent the head volume conductor. A closed-form solution of the electrical potential over the scalp and inside the brain due to a point current source was developed for the three-concentric-sphere inhomogeneous head model. Computer simulation studies were conducted to validate the proposed equivalent current source imaging. Assuming source configurations as either multiple dipoles or point current sources/sinks, in computer simulations we used our method to reconstruct these sources, and compared with the equivalent dipole source imaging. Human experimental studies were also conducted and the equivalent current source imaging was performed on the visual evoked potential data. These results highlight the advantages of the equivalent current source imaging and suggest that it may become an alternative approach to imaging spatially distributed current sources-sinks in the brain and other organ systems.

[Influence of heart position change on body surface potential distribution]

Based on a 3-D emulational body torso model, the influence of changes of heart position caused by deep inspiration etc. on body surface potential maps(BSPMs) was studied in forward electrocardiography. In this report, BSPMs and ECGs during QRS were provided while the heart was in the normal position, or rotated clockwise to the vertical or counterclockwise to the transverse.

Source potential mapping: a new modality to image neural electric activities

A new neural electric imaging modality-source potential mapping (SPM)-is presented here, which images the neural sources by the potential produced by the sources in a homogeneous infinite conducting medium. Compared with the extant cortical surface potential mapping (CPM). SPM is a more direct reflection of the sources and is a simpler physical model, thus assuring easy understanding. The simulations show that SPM has a slightly higher spatial resolution than CPM and the calculation of SPM is more economical than that of CPM.

Synthesis and reactivity of potential toxic metabolites of tamoxifen analogues: droloxifene and toremifene o-quinones

Tamoxifen remains the endocrine therapy of choice in the treatment of all stages of hormone-dependent breast cancer. However, tamoxifen has been shown to increase the risk of endometrial cancer which has stimulated research for new effective antiestrogens, such as droloxifene and toremifene. In this study, the potential for these compounds to cause cytotoxic effects was investigated. One potential cytotoxic mechanism could involve metabolism of droloxifene and toremifene to catechols, followed by oxidation to reactive o-quinones. Another cytotoxic pathway could involve the oxidation of 4-hydroxytoremifene to an electrophilic quinone methide. Comparison of the amounts of GSH conjugates formed from 4-hydroxytamoxifen, droloxifene, and 4-hydroxytoremifene suggested that 4-hydroxytoremifene is more effective at formation of a quinone methide. However, all three substrates formed similar amounts of o-quinones. Both the tamoxifen-o-quinone and toremifene-o-quinone reacted with deoxynucleosides to give corresponding adducts. However, the toremifene-o-quinone was shown to be considerably more reactive than the tamoxifen-o-quinone in terms of both kinetic data as well as the yield and type of deoxynucleoside adducts formed. Since thymidine formed the most abundant adducts with the toremifene-o-quinone, sufficient material was obtained for characterization by (1)H NMR, COSY-NMR, DEPT-NMR, and tandem mass spectrometry. Cytotoxicity studies with tamoxifen, droloxifene, 4-hydroxytamoxifen, 4-hydroxytoremifene, and their catechol metabolites were carried out in the human breast cancer cell lines S30 and MDA-MB-231. All of the metabolites tested showed cytotoxic effects that were similar to the parent antiestrogens which suggests that o-quinone formation from tamoxifen, droloxifene, and 4-hydroxytoremifene is unlikely to contribute to their cytotoxicity. However, the fact that the o-quinones formed adducts with deoxynucleosides in vitro implies that the o-quinone pathway might contribute to the genotoxicity of the antiestrogens in vivo.

A self-coherence enhancement algorithm and its application to enhancing three-dimensional source estimation from EEGs

In this paper a new algorithm is proposed to enhance the spatial resolution of solutions of the underdetermined EEG inverse problem. Termed the self-coherence enhancement algorithm (SCEA), the present algorithm provides a self-coherence solution, which is a function of the high order self-coherence estimate of an unbiased smooth estimate of the underdetermined EEG inverse solution. The order of the high order self-coherence function is determined by the blurring level of the actual source distribution as represented by a normalized blurring index. The proposed SCEA algorithm may be used to enhance the spatial resolution of an inverse solution obtained by any inverse reconstruction algorithm. Computer simulation studies have been conducted to evaluate the performance of the SCEA and to compare its performance to that of the LORETA and the FOCUSS algorithms.

A method to standardize a reference of scalp EEG recordings to a point at infinity

The effect of an active reference in EEG recording is one of the oldest technical problems in EEG practice. In this paper, a method is proposed to approximately standardize the reference of scalp EEG recordings to a point at infinity. This method is based on the fact that the use of scalp potentials to determine the neural electrical activities or their equivalent sources does not depend on the reference, so we may approximately reconstruct the equivalent sources from scalp EEG recordings with a scalp point or average reference. Then the potentials referenced at infinity are approximately reconstructed from the equivalent sources. As a point at infinity is far from all the possible neural sources, this method may be considered as a reference electrode standardization technique (REST). The simulation studies performed with assumed neural sources included effects of electrode number, volume conductor model and noise on the performance of REST, and the significance of REST in EEG temporal analysis. The results showed that REST is potentially very effective for the most important superficial cortical region and the standardization could be especially important in recovering the temporal information of EEG recordings.

Transforming growth factor beta receptor signaling and endocytosis are linked through a COOH terminal activation motif in the type I receptor

Transforming growth factor beta (TGF-beta) coordinates a number of biological events important in normal and pathophysiological growth. In this study, deletion and substitution mutations were used to identify receptor motifs modulating TGF-beta receptor activity. Initial experiments indicated that a COOH-terminal sequence between amino acids 482-491 in the kinase domain of the type I receptor was required for ligand-induced receptor signaling and down-regulation. These 10 amino acids are highly conserved in mammalian, Xenopus, and Drosophila type I receptors. Although mutation or deletion of the region (referred to as the NANDOR BOX, for nonactivating non-down-regulating) abolishes TGF-beta-dependent mitogenesis, transcriptional activity, type I receptor phosphorylation, and down-regulation in mesenchymal cultures, adjacent mutations also within the kinase domain are without effect. Moreover, a kinase-defective type I receptor can functionally complement a mutant BOX expressing type I receptor, documenting that when the BOX mutant is activated, it has kinase activity. These results indicate that the sequence between 482 and 491 in the type I receptor provides a critical function regulating activation of the TGF-beta receptor complex.

5-hydroxytryptamine3 (5-HT3) receptors mediate spinal 5-HT antinociception: an antisense approach

To examine the role of the 5-hydroxytryptamine(1B) (5-HT1B) and 5-HT3 receptor subtypes in the analgesia produced by 5-HT (serotonin) agonists, we assessed the effect of antisense oligodeoxynucleotides (AODNs) designed to "knock down" the number of these receptor subtypes on analgesia produced by intrathecal (i.t.) 5-HT, the 5-HT1B receptor agonist, 7-trifluoromethyl-4-(4-methyl-1-piperazinyl)-pyrrolo[1,2-a]quinoxaline maleate (CGS-12066A), and the 5-HT3 receptor agonist, 2-methyl-5-HT. Groups of mice (n = 17-20) were injected i.t. on days 1, 3, and 5 with one of the AODNs, a mismatch oligo, or saline. On day 6, all mice were injected i.t. with 70.5 nmol of 5-HT, 44.4 nmol of CGS-12066A, or 49 nmol of 2-methyl-5-HT by lumbar puncture. Following testing, spinal cords were rapidly removed and prepared for receptor binding assays. Treatment with AODN for 5-HT1B receptors produced a 70% reduction in ligand binding to this receptor subtype. After treatment with AODN for 5-HT3 receptors, ligand binding to this receptor subtype was undetectable. In mice tested with i.t. 5-HT, tail-flick analgesia was attenuated only in mice treated with the 5-HT3 receptor AODN. Mice treated with the AODN designed to knock down 5-HT(1B) receptors or with its mismatch oligo were not significantly different from controls. In mice tested with i.t. administration of CGS-12066A, none of the oligo treatments produced a significant attenuation of analgesia. In mice tested with i.t. administration of 2-methyl-5-HT, only 5-HT3 receptor AODN attenuated analgesia. Thus, 5-HT and 2-methyl-5-HT analgesia are mediated by the 5-HT3 receptor subtype. However, spinal CGS-12066A analgesia appears not to be mediated by either the 5-HT1B or the 5-HT3 receptor subtypes.

A study of equivalent source techniques for high-resolution EEG imaging

High-resolution EEG imaging has been an important topic in recent EEG research, and much work has been done on the two equivalent source imaging techniques: the equivalent distributed dipole-layer source imaging technique (EST) and the equivalent multipole source imaging technique (SAT). In this paper we first develop a forward density formula for a spherical equivalent distributed dipole layer of an arbitrary dipole in a three-concentric-sphere head model. It is clarified using the derived forward formula that the equivalent dipole-layer source and equivalent multipole source are interrelated in theory. Finally, simulation comparisons are conducted, the results of which suggest that EST has a higher spatial resolution than SAT when both of them are implemented by a truncated singular value decomposition algorithm. This is due to the different singularities of the inversion equations involved in the two techniques. An empirical VEP data study also shows that EST is better than SAT in providing higher spatial resolution EEG imaging.

Human NADPH-P450 oxidoreductase modulates the level of cytochrome P450 CYP2D6 holoprotein via haem oxygenase-dependent and -independent pathways

NADPH-P450 oxidoreductase (CPR) is essential for the activity of cytochrome P450 (P450). Previous studies demonstrated that CPR regulates the levels of various P450 isoforms in vitro. We investigated the mechanistic basis for this regulation. By transfection of Chinese hamster ovary DUKXB11 cells we obtained the cell line DUKX/2D6, which expressed human CYP2D6, a P450 isoform. Subsequently, DUKX/2D6 cells were transfected with human CPR cDNA to generate the cell line DUKX/2D6/CPR-3. Expression of recombinant CPR decreased the level of spectrally detectable CYP2D6 holoprotein in DUKX/2D6/CPR-3 cells by 70%, whereas the level of immunodetectable apoprotein remained unchanged. Addition of the radical scavenger DMSO increased levels of CYP2D6 holoenzyme in DUKX/2D6/CPR-3 cells but not in DUKX/2D6 cells. A similar effect was noted when cells were grown in the presence of hemin. Importantly, combined treatment with DMSO and hemin increased levels of CYP2D6 holoenzyme in DUKX/2D6/CPR-3 but not in DUKX/2D6 cells even further than either treatment alone. None of these treatments affected the level of immunodetectable CYP2D6. This demonstrates that expression of CPR increases production of damaging radicals but also that CPR may alter haem homoeostasis. In agreement with this, the activity of haem oxygenase, a rate-limiting enzyme in haem metabolism, was compared with that in DUKX/DHFR control cells (expressing dihydrofolate reductase), and was 3-fold higher in DUKX/2D6/CPR-3 but similar in DUKX/2D6 cells. Furthermore, treatment of cells with sodium arsenite increased levels of haem oxygenase concomitant with a marked decrease of spectrally detectable CYP2D6 and a rise in levels of ferritin, which sequesters free iron released from the destruction of haem. These data demonstrate that CPR regulates P450 activity by supplying electrons and also by altering P450 levels via radical-and haem oxygenase-mediated pathways.

Detection of leukemic cells in the CD34(+)CD38(-) bone marrow progenitor population in children with acute lymphoblastic leukemia

Successful autologous hematopoietic stem cell (HSC) transplantation in childhood acute lymphoblastic leukemia (ALL) requires the ability to either selectively kill the leukemia cells or separate normal from leukemic HSC. Based on previous studies showing that more than 95% of childhood B-lineage ALL express CD38, this study evaluated whether normal CD34(+)CD38(-) progenitors from children with B-lineage ALL could be isolated by flow cytometry. CD34(+) cells from bone marrow samples from 10 children with B-lineage ALL were isolated at day 28 of treatment, when clinical remission had been attained. The CD34(+) progenitor cells were flow cytometrically sorted into CD34(+)CD38(+) and CD34(+)CD38(-) populations. The absolute numbers of CD34(+)CD38(-) cells that could be isolated ranged from 401 to 6245. The cells were then analyzed for the presence of clonotypic rearrangements of the T-cell receptor (TCR) Vdelta2-Ddelta3 locus. Only patients whose diagnostic marrow had an informative TCR Vdelta2-Ddelta3 rearrangement were included in this study. Detection thresholds were typically 10(-4) to 10(-5) leukemic cells in normal marrow. In 6 of 10 samples analyzed, the sorted CD34(+)CD38(-) cells had no detectable Vdelta2-Ddelta3 rearrangements. In 4 cases, the clonotypic leukemic Vdelta2-Ddelta3 rearrangement was detected in the CD34(+)CD38(-) population, indicating that the putative normal HSC population also contained leukemic cells. The data indicate that although most childhood ALL cells express CD34 and CD38, leukemic cells are also frequently present in the CD34(+)CD38(-) population. Therefore, strategies to isolate and transplant normal HSC from children with ALL will require a more stringent definition of the normal HSC than the CD34(+)CD38(-) phenotype. (Blood. 2001;97:3925-3930)

Synthesis and reactivity of the catechol metabolites from the equine estrogen, 8,9-dehydroestrone

The risk factors for women developing breast and endometrial cancers are all associated with a lifetime of estrogen exposure. Estrogen replacement therapy in particular has been correlated with an increased cancer risk. Previously, we showed that the equine estrogens equilin and equilenin, which are major components of the widely prescribed estrogen replacement formulation Premarin, are metabolized to highly cytotoxic quinoids which caused oxidative stress and alkylation of DNA in vitro [Bolton, J. L., Pisha, E., Zhang, F., and Qiu, S. Chem. Res. Toxicol. 1998, 11, 1113-1127]. In this study, we have synthesized 8,9-dehydroestrone (a third equine estrogen component of Premarin) and its potential catechol metabolites, 4-hydroxy-8,9-dehydroestrone and 2-hydroxy-8,9-dehydroestrone. Both 2-hydroxy-8,9-dehydroestrone and 4-hydroxy-8,9-dehydroestrone were oxidized by tyrosinase or rat liver microsomes to o-quinones which reacted with GSH to give one mono-GSH conjugate and two di-GSH conjugates. Like endogenous estrogens, 8,9-dehydroestrone was primarily converted by rat liver microsomes to the 2-hydroxylated rather than the 4-hydroxylated o-quinone GSH conjugates; the ratio of 2-hydroxy-8,9-dehydroestrone versus 4-hydroxy-8,9-dehydroestrone was 6:1. Also in contrast to experiments with equilin, 4-hydroxyequilenin was not observed in microsomal incubations with 8,9-dehydroestrone or its catechols. The behavior of 2-hydroxy-8,9-dehydroestrone was found to be more complex than 4-hydroxy-8,9-dehydroestrone as GSH conjugates resulting from 2-hydroxy-8,9-dehydroestrone were detected even without oxidative enzyme catalysis. Under physiological conditions, 2-hydroxy-8,9-dehydroestrone isomerized to 2-hydroxyequilenin to form the very stable 2-hydroxyequilenin catechol; however, 4-hydroxy-8,9-dehydroestrone was found to be stable under similar conditions. Finally, preliminary studies conducted with the human breast tumor S-30 cell lines demonstrated that the catechol metabolites of 8,9-dehydroestrone were much less toxic than 4-hydroxyequilenin (20-40-fold). These results suggest that the catechol metabolites of 8,9-dehydroestrone may have the ability to cause cytotoxicity in vivo primarily through formation of o-quinones; however, most of the adverse effects of Premarin estrogens are likely due to formation of 4-hydroxyequilenin o-quinone from equilin and equilenin.

An epidemiological survey on neonatal jaundice in China

OBJECTIVE

To provide epidemiological data for revising the diagnostic criteria of neonatal hyperbilirubinemia in China.

METHODS

A survey was performed among full-term infants in multiple centers throughout the country. From less than 24 hours after birth, the infants' bilirubin levels were measured every day until the peak level fell to less than 68.4 mumol/L. Auditory brainstem responses were assessed in 56 infants randomly chosen from those with serum bilirubin levels of higher than 220.5 mumol/L.

RESULTS

Jaundice in most infants was detected at 2-3 days after birth. The bilirubin level usually reached a peak level of 204 +/- 54.69 mumol/L at 5 days after birth and then fell. Among the 875 infants, the serum bilirubin levels in 34.4% of neonates were higher than 220.5 mumol/L. The mean serum bilirubin level of the infants during the first week after birth varied with geography (P < 0.001) and season (P < 0.001). The serum bilirubin level was significantly associated with gestation age (P < 0.01), delivery method (P < 0.01), weight loss (P < 0.001), and PCV elevation (P < 0.001) during the first three days after birth.

CONCLUSIONS

The start time of neonatal jaundice was similar to that reported elsewhere, but the mean peak level in our study was higher than the reported. It is suggested that the diagnostic criteria for neonatal hyperbilirubinemia in China should be strict.

[An off site petroleum-contaminated soil bioremediation technology: soil compositing in windrow]

With off-site bioremediation technology, a soil contaminated by crude oil from Liaohe Oil Field was treated on a 20 x 10 m prepared bed. 8 composting windrow units were set, each measured 8 m in length, 2 m in width, and 0.35 m in height. The results showed that when the pollutant petroleum hydrocarbon(TPH) was within the range of 4.16-7.72 g.100 g-1 soil, the total degradation rate of TPH reached 45.19%-56.74% after 53 days operation, which indicated that a technological basis would be provided for the bioremediation of oil-contaminated soil.

Mechanisms of transforming growth factor-beta receptor endocytosis and intracellular sorting differ between fibroblasts and epithelial cells

Transforming growth factor-betas (TGF-beta) are multifunctional proteins capable of either stimulating or inhibiting mitosis, depending on the cell type. These diverse cellular responses are caused by stimulating a single receptor complex composed of type I and type II receptors. Using a chimeric receptor model where the granulocyte/monocyte colony-stimulating factor receptor ligand binding domains are fused to the transmembrane and cytoplasmic signaling domains of the TGF-beta type I and II receptors, we wished to describe the role(s) of specific amino acid residues in regulating ligand-mediated endocytosis and signaling in fibroblasts and epithelial cells. Specific point mutations were introduced at Y182, T200, and Y249 of the type I receptor and K277 and P525 of the type II receptor. Mutation of either Y182 or Y249, residues within two putative consensus tyrosine-based internalization motifs, had no effect on endocytosis or signaling. This is in contrast to mutation of T200 to valine, which resulted in ablation of signaling in both cell types, while only abolishing receptor down-regulation in fibroblasts. Moreover, in the absence of ligand, both fibroblasts and epithelial cells constitutively internalize and recycle the TGF-beta receptor complex back to the plasma membrane. The data indicate fundamental differences between mesenchymal and epithelial cells in endocytic sorting and suggest that ligand binding diverts heteromeric receptors from the default recycling pool to a pathway mediating receptor down-regulation and signaling.

Modulation of P450 CYP3A4-dependent metabolism by P-glycoprotein: implications for P450 phenotyping

Some compounds used for phenotyping of cytochrome P450s are substrates of P-glycoprotein (pgp). It is likely that in these cases, the level of pgp modulates the metabolism of in vivo probes. To address this important issue, we have analyzed the effects of pgp on CYP3A4-mediated reactions in two newly established cell lines (3A4/HR/MDR(-) and 3A4/HR/MDR(+)), which express CYP3A4 in the absence and presence of pgp, respectively. In cultured cells, the presence of pgp increased the apparent K(m) for the 6beta-hydroxylase activity of CYP3A4 toward testosterone and cortisol by a factor of 1.7 and 4, respectively. These steroids are poor and good substrates of pgp, respectively, and cortisol 6beta-hydroxylase has been frequently used as an in vivo probe for CYP3A4. Interestingly, we also found that pgp modulated the inhibition of CYP3A4-mediated metabolism by several compounds in intact cells. Although quinidine inhibited testosterone 6beta-hydroxylase activity in membranes or in intact cells that expressed recombinant CYP3A4 in the absence of pgp, low concentrations of this compound increased CYP3A4 activity in intact cells that expressed pgp. These results imply that pharmacokinetic drug-drug interactions involving CYP3A4 can be influenced by pgp.

[Prolapse of the urethral mucosa in young girls from the Ivory Coast]

In this retrospective study covering a nine-year period, 65 cases have been analyzed of prolapse of the urethral mucosa in young girls (aged between six weeks and 14 years) from the Ivory Coast. The aim of this study was to describe the etiology of this disorder, and to demonstrate the utility of ambulatory surgery. The main reason for the detection of this disorder was mild genital hemorrhage in 37 cases, which was related to rape in eight instances and to other types of trauma in nine cases, thereby raising serious medico-legal problems. Various forms of treatment were used (medical and/or surgical). The medical approach consisted of antibiotic and antiinflammatory treatment, combined with a local antiseptic. Two surgical approaches were adopted, either the Doria method in which the necrosed tissue is spontaneously eliminated after three to five days, or surgical excision under general anesthesia of the prolapsed mucosa followed by seromucosal stitching. The results were satisfactory in all cases, and in the surgically operated cases no complications or recurrence were noted at one-year follow-up.

Immobilization of antibodies on ultraflat polystyrene surfaces

BACKGROUND

Functional antibody surfaces were prepared on ultraflat polystyrene surfaces by physical adsorption, and the uniform distribution of monoclonal antibodies against hepatitis B surface antigen (anti-HBs) on such surfaces and the presence of dense hepatitis B surface antigen (HBsAg) particles captured by immobilized antibodies were identified.

METHODS

A model polystyrene film was spin-coated directly onto a silicon wafer surface. Atomic force microscopy was used to directly monitor the immobilization of anti-HBs antibodies and their specific molecular interaction with HBsAg. Enzyme immunoassay was also used to characterize functional antibody surfaces.

RESULTS

A mean roughness of 2 A for areas of 25 microm(2) was produced. We found a uniform distribution of anti-HBs antibodies on ultraflat polystyrene surfaces and the presence of dense HBsAg particles bound to such anti-HBs surfaces after incubation with HBsAg.

CONCLUSIONS

This study confirmed the potential of preparing dense, homogeneous, highly specific, and highly stable antibody surfaces by immobilizing antibodies on polystyrene surfaces with controlled roughness. It is expected that such biofunctional surfaces could be of interest for the development of new solid-phase immunoassay techniques and biosensor techniques.

A novel system A isoform mediating Na+/neutral amino acid cotransport

A cDNA clone encoding a plasma membrane alanine-preferring transporter (SAT2) has been isolated from glutamatergic neurons in culture and represents the second member of the system A family of neutral amino acid transporters. SAT2 displays a widespread distribution and is expressed in most tissues, including heart, adrenal gland, skeletal muscle, stomach, fat, brain, spinal cord, colon, and lung, with lower levels detected in spleen. No signal is detected in liver or testis. In the central nervous system, SAT2 is expressed in neurons. SAT2 is significantly up-regulated during differentiation of cerebellar granule cells and is absent from astrocytes in primary culture. The functional properties of SAT2, examined using transfected fibroblasts and in cRNA-injected voltage-clamped Xenopus oocytes, show that small aliphatic neutral amino acids are preferred substrates and that transport is voltage- and Na(+)-dependent (1:1 stoichiometry), pH-sensitive, and inhibited by alpha-(methylamino)isobutyric acid (MeAIB), a specific inhibitor of system A. Kinetic analyses of alanine and MeAIB uptake by SAT2 are saturable, with Michaelis constants (K(m)) of 200-500 microm. In addition to its ubiquitous role as a substrate for oxidative metabolism and a major vehicle of nitrogen transport, SAT2 may provide alanine to function as the amino group donor to alpha-ketoglutarate to provide an alternative source for neurotransmitter synthesis in glutamatergic neurons.

Collective beam-beam effects in hadron colliders

Collective beam-beam effects in hadron colliders were studied with a strong-strong beam-beam simulation on the CERN Large Hadron Collider, including multipole field errors in the lattice and beam-beam interactions at two high-luminosity interaction points. It was found that the beam-beam interaction could result in two distinct dynamics for hadron beams: a slow beam-size growth and an unstable beam-centroid oscillation. The instability of the beam-centroid oscillation has typical characteristics of the chaotic transport, i. e., the amplitude increase of the oscillation consists of slow escape from the remnants of invariant manifolds and fast diffusion in fully developed chaotic regions. The simulation results indicate that there is a threshold of the beam-beam parameter below which no unstable beam-centroid motion was observed. The escape rate of the unstable beam-centroid motion, on the other hand, increases with the nonlinear field errors in the lattice. As the slow beam-size growth is strongly enhanced by the beam-centroid oscillation, an elimination of the centroid motion with feedback can effectively suppress the beam-size growth. No steady state of coherent beam-beam oscillation was observed.