Optimization of High-Yield Biological Synthesis of Single-Crystalline Gold Nanoplates

In this work, single-crystalline gold nanoplates were obtained by reducing aqueous chloroauric acid solution with the extract of Sargassum sp. (brown seaweed) at room temperature. The gold nanoplates so obtained were characterized by UV-vis spectroscopy, X-ray diffraction, atomic force microscopy, and transmission electron microscopy. The formation of gold nanoplates was found to depend on a number of environmental factors, such as the time taken to age the seaweed extract, pH of the reaction medium, reaction temperature, reaction time, and initial reactant concentrations. The size of the gold nanoplates could be controlled to between 200 and 800 nm by manipulating the initial reactant concentrations. The yield of the flat gold nanocrystals relative to the total number of nanoparticles formed was as high as approximately 80-90%.

Treatment of tremor in Parkinson's disease by subthalamic nucleus stimulation

The recent resurgent interest in functional surgery for the treatment of Parkinson's disease (PD) has focused on the effects on akinesia and levodopa-induced dyskinesia. Stimulation of the subthalamic nucleus (STN) improves akinesia and rigidity but its effects on tremor have not been studied. The objective of this study was to assess the efficacy of STN stimulation on tremor in patients with the complete parkinsonian triad with motor fluctuations. Of 27 consecutive patients with STN stimulation (26 bilateral), 15 exhibited tremor rated at least 2/4 according to item 20 (rest tremor) of the Unified Parkinson's Disease Rating Scale (UPDRS) in at least one limb. The mean preoperative tremor score was 11.3+/-5.6 in off-drug and 1.2+/-2.4 in on-drug conditions. The postoperative tremor scores at the last follow up (from 1-12 months) were 2.2+/-2.2 off-drug/on-stimulation and 0.2+/-0.4 on-drug/on-stimulation. Both rest and action tremors were improved in all patients. The UPDRS tremor score was reduced by 80%, rigidity score by 65%, and akinesia score by 51% on average. For the three symptoms, the stimulation effect was close to that induced before surgery by a suprathreshold dose of levodopa given in the morning. STN stimulation can be considered an interesting alternative to thalamic or internal pallidal surgery even in PD patients with severe high-amplitude tremor. In keeping with electrophysiological data in monkeys rendered parkinsonian by MPTP injections, our results emphasize the importance of the oscillation of a neuronal loop involving the STN in the pathophysiology of parkinsonian tremor.

Sum1 and Hst1 repress middle sporulation-specific gene expression during mitosis in Saccharomyces cerevisiae

Meiotic development in yeast is characterized by the sequential induction of temporally distinct classes of genes. Genes that are induced at the middle stages of the pathway share a promoter element, termed the middle sporulation element (MSE), which interacts with the Ndt80 transcriptional activator. We have found that a subclass of MSEs are strong repressor sites during mitosis. SUM1 and HST1, genes previously associated with transcriptional silencing, are required for MSE-mediated repression. Sum1 binds specifically in vitro to MSEs that function as strong repressor sites in vivo. Repression by Sum1 is gene specific and does not extend to neighboring genes. These results suggest that mechanisms used to silence large regions of chromatin may also be used to regulate the expression of specific genes during development. NDT80 is regulated during mitosis by both the Sum1 and Ume6 repressors. These results suggest that progression through sporulation may be controlled by the regulated competition between the Sum1 repressor and Ndt80 activator at key MSEs.

Quantitative measurement of cerebral physiology using respiratory-calibrated MRI

Functional magnetic resonance imaging typically measures signal increases arising from changes in the transverse relaxation rate over small regions of the brain and associates these with local changes in cerebral blood flow, blood volume and oxygen metabolism. Recent developments in pulse sequences and image analysis methods have improved the specificity of the measurements by focussing on changes in blood flow or changes in blood volume alone. However, FMRI is still unable to match the physiological information obtainable from positron emission tomography (PET), which is capable of quantitative measurements of blood flow and volume, and can indirectly measure resting metabolism. The disadvantages of PET are its cost, its availability, its poor spatial resolution and its use of ionising radiation. The MRI techniques introduced here address some of these limitations and provide physiological data comparable with PET measurements. We present an 18-minute MRI protocol that produces multi-slice whole-brain coverage and yields quantitative images of resting cerebral blood flow, cerebral blood volume, oxygen extraction fraction, CMRO(2), arterial arrival time and cerebrovascular reactivity of the human brain in the absence of any specific functional task. The technique uses a combined hyperoxia and hypercapnia paradigm with a modified arterial spin labelling sequence.

A frequent activated smoothened mutation in sporadic basal cell carcinomas

Basal-cell carcinomas (BCCs) are the most common cancer in Caucasians. It has been reported that the patched gene is inactivated in 30-40% sporadic BCCs and 20% sporadic medulloblastomas via loss of heterozygosity and nonsense mutations. Recently, two activating smoothened mutations have been found in the sporadic basal cell carcinomas. One, at base pair 1604 (G-to-T transversion) of exon 9, changes codon 535 from tryptophan to leucine, and the other, at base pair 1685 (G-to-A transition) of exon 10, changes codon 562 from arginine to glutamine (Xie et al., 1998). In our study, 1604G-->T was found in 20 out of 97 (20.6%) sporadic BCCs. The high prevalence indicates that 1604G is the mutation hot spot in our tumor samples. This mutation was detected in all three histological subtypes of BCCs, suggesting that smoothened mutation is an early event during the development of the tumor. Our finding of a high smoothened mutation rate, together with high frequent patched gene mutations reported recently, indicates that activation of the hedgehog signal transduction pathway is the most common and early event in the development of sporadic BCCs. Additionally, to determine whether smoothened, like patched, is also involved in the carcinogenesis of medulloblastomas, we screened medulloblastoma samples for these two mutations by restriction analysis. We have found the 1604G-->T mutation in 1 out of 21 medulloblastomas. This result confirmed smoothened gene involvement in the carcinogenesis of medulloblastoma.

Self-assembly of frameworks with specific topologies: construction and anion exchange properties of M3L2 architectures by tripodal ligands and silver(I) salts

Three five-component architectures, compounds 3, 4, and 5 were obtained by self-assembly of tripodal 1,3,5-tris(imidazol-1-ylmethyl )-2,4,6-trimethylbenzene (6) and 1,3,5-tris(benzimidazol-2-ylmethyl)benzene (7) ligands with silver(I) salts. The structures of these novel complexes have been determined by X-ray crystallography. The results of structural analysis indicate that these frameworks have same M3L2 components, but different structures. Compounds 3 and 4 are both M3L2 type cage-like complexes, while the 5 is an open trinuclear complex. The complex 3 is a cylindrical cage with simultaneous inclusion of a perchlorate anion inside of the cage as a guest molecule. Such guests can be exchanged for other anions through the open edge of the cage as evidenced by crystal structure of 4. The results demonstrate that the molecular M3L2 type cage can act as a host for anions and provide a nice example of supramolecular architectures with interesting properties and possible applications.

Effects of cell volume fraction changes on apparent diffusion in human cells

Diffusion-weighted imaging was used to study the relationship between apparent diffusion coefficient (ADC) and cell volume fraction in cell suspensions and packed arrays. Cell volume fraction was varied by changing extracellular fluid osmolarity (for human glial cells) and by changing cell density (for human glial and red blood cells). In packed arrays of glial cells, ADC increased 10% when cells shrank and decreased 13% when cells swelled. ADC decreased 34% as cell density increased from 0 to 72%. In erythrocyte suspensions, ADC decreased 90% as the cell density increased from 0 to 89%. These results agree with theoretical predictions.

Adverse effects of interrupting precordial compression during cardiopulmonary resuscitation

OBJECTIVES

In the current operation of automated external defibrillators, substantial time may be consumed for a "hands off" interval during which precordial compression is discontinued to allow for automated rhythm analyses before delivery of the electric countershock. The effects of such a pause on the outcomes of cardiopulmonary resuscitation were investigated.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

Research laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Ventricular fibrillation was electrically induced in 25 Sprague-Dawley rats. After 4 mins of untreated ventricular fibrillation, precordial compression was begun and continued for 6 mins. Animals were then randomized to receive an immediate defibrillation shock or the defibrillation attempt was delayed for intervals of 10, 20, 30, or 40 secs.

MEASUREMENTS AND MAIN RESULTS

Immediate defibrillation restored spontaneous circulation in each instance. When defibrillation was delayed for 10 or 20 secs, spontaneous circulation was restored in three of five animals in each group. After a 30-sec delay, spontaneous circulation was restored in only one of five animals (p < .05). No animal was successfully resuscitated after a 40-sec delay (p < .01). With increasing delays, 24- and 48-hr survival rates were correspondingly reduced.

CONCLUSIONS

During resuscitation from ventricular fibrillation, prolongation of the interval between discontinuation of precordial compression and delivery of the first electric countershock substantially compromises the success of cardiac resuscitation. Accordingly, automated defibrillators are likely to be maximally effective if they are programmed to secure minimal "hands off" delay before delivery of the electric countershock.

Randomised placebo-controlled trial of use of topical recombinant bovine basic fibroblast growth factor for second-degree burns

BACKGROUND

Wound healing is a dynamic process that could be accelerated by growth factors. We investigated the effect of recombinant bovine basic fibroblast growth factor (rbFGF) on burn healing in a randomised placebo-controlled trial.

METHODS

We recruited 600 patients with superficial or deep second-degree burns. Patients received 150 AU/cm2 daily topical rbFGF (n=300) or placebo (n=300) plus vehicle. We assessed healing by photography, punch-biopsy, and clinical examination.

FINDINGS

All patients treated with rbFGF had faster granulation tissue formation and epidermal regeneration than those in the placebo group. Superficial and deep second-degree burns treated with rbFGF healed in a mean of 9.9 (SD 2.5) days and 17.0 (4.6) days, respectively, compared with 12.4 (2.7) and 21.2 (4.9) days (p=0.0008 and p=0.0003, respectively). No adverse effects were seen locally or systemically with rbFGF.

INTERPRETATION

rbFGF effectively decreased healing time and improved healing quality. Clinical benefits would be shorter hospital stays and the patient's skin quickly becoming available for harvesting and grafting.

SNAP-25 deficit and hippocampal connectivity in schizophrenia

Regional abnormalities of brain connectivity may be an important substrate for the expression of schizophrenia, a severe form of mental illness. Brain imaging and postmortem morphometric studies indicate hippocampal structure is abnormal in schizophrenia. To study molecular components of hippocampal connectivity the presynaptic proteins SNAP-25 and synaptophysin were assayed in postmortem samples. Immunocytochemical studies indicated reduced SNAP-25 immunoreactivity in schizophrenia compared to controls, particularly in the terminal fields of entorhinal cortex projections. Although there were no overall changes in synaptophysin immunoreactivity, in the granule cell layer of the dentate gyrus synaptophysin immunoreactivity was increased in schizophrenia. These results indicate that disconnection of a subset of hippocampal circuitry from the entorhinal cortex, as well as intrinsic changes in hippocampal connectivity, may contribute to the mechanism of illness in schizophrenia.

Effect of chronic bilateral subthalamic nucleus (STN) stimulation on postural control in Parkinson's disease

Postural instability is one of the most incapacitating factors in Parkinson's disease (PD). The underlying deficits and the effects of treatment are still not well understood. The aims of the present study were: (i) to identify abnormalities of postural control in PD patients during unperturbed stance and externally perturbed stance (anterior-posterior tilts of the support surface and of the visual scene); (ii) to assess the effects of L-dopa medication and subthalamic nucleus (STN) stimulation on posture control; and (iii) to characterize potential differential or additive effects of both treatments. Eight PD patients under chronic STN stimulation were investigated and compared with 10 normal controls. The assessment was performed in a crossover design (+/- STN stimulation, +/- L-dopa). During unperturbed stance, we recorded measures of spontaneous sway in terms of displacement, velocity and frequency of the centre of pressure (COP), lower body (LB) and upper body (UB) excursions. In addition, inter-segmental UB-LB coupling was investigated as a measure of axial stiffness. All these measures were abnormally large in patients OFF treatment. Under L-dopa treatment, the velocity, frequency and coupling measures were reduced, whereas sway amplitude increased. Very similar effects were obtained under STN stimulation, and these effects became more pronounced in the combined treatment condition. In these data, reduction of inter-segmental coupling correlated with increase in sway amplitude. The finding suggests that axial stiffness reduction under treatment revealed a treatment- resistant deficit in the sensorimotor postural control loop. However, these two effects did not correlate with the motor subscores of the unified Parkinson's disease rating scale (UPDRS), which indicates that they are of minor functional relevance for posture control. A frequency peak in the COP excursions at 0.7-1.1 Hz, which we take to indicate a resonance behaviour of the postural control loop, became reduced under therapy. The reduction of this peak did correlate with most improvements in the UPDRS under therapy. Support surface tilt revealed that an UB righting on the LB segment, which is present in normal controls, is missing in the patients. The postural responses to visual tilt were abnormally large in patients, independent of whether the support was stable or slightly moving, while the control subjects clearly profited from a stable support. This finding suggests that PD patients lack the ability of normal subjects to use sensory or cognitive information when suppressing the destabilizing effect of visual tilt. These abnormal tilt reactions of the patients were resistant to treatment with L-dopa, STN stimulation and a combination of the two. Overall, the effects of STN stimulation on posture control essentially paralleled those of L-dopa during both unperturbed and externally perturbed stance.

In vitro bond strength of two adhesives to enamel and dentin under normal and contaminated conditions

In vitro bond strengths of human enamel and dentin treated with five contaminants were measured with air, water and damp conditions as controls. Two commercial bonding agents (a lower-viscosity, solvent-containing type, AB, and a higher-viscosity, hydrophilic monomer type, SB) and their composites were applied to tooth structure under two conditions (contaminated and re-etched). Samples were debonded in tension after 24 h using an inverted, truncated cone test. Among the controls, the highest bond strengths were obtained with damp conditions for AB (24 MPa) and damp conditions or air for SB (22 MPa) with small differences between enamel and dentin. Most contaminants lowered the bond strength. Re-etching without additional mechanical preparation resulted in bond strengths similar to controls. Bond strengths to tooth structure with the bonding agents tested may be less sensitive to common forms of contamination than typically assumed.

Amivantamab plus chemotherapy with and without lazertinib in EGFR-mutant advanced NSCLC after disease progression on osimertinib: primary results from the phase III MARIPOSA-2 study

BACKGROUND

Amivantamab plus carboplatin-pemetrexed (chemotherapy) with and without lazertinib demonstrated antitumor activity in patients with refractory epidermal growth factor receptor (EGFR)-mutated advanced non-small-cell lung cancer (NSCLC) in phase I studies. These combinations were evaluated in a global phase III trial.

PATIENTS AND METHODS

A total of 657 patients with EGFR-mutated (exon 19 deletions or L858R) locally advanced or metastatic NSCLC after disease progression on osimertinib were randomized 2 : 2 : 1 to receive amivantamab-lazertinib-chemotherapy, chemotherapy, or amivantamab-chemotherapy. The dual primary endpoints were progression-free survival (PFS) of amivantamab-chemotherapy and amivantamab-lazertinib-chemotherapy versus chemotherapy. During the study, hematologic toxicities observed in the amivantamab-lazertinib-chemotherapy arm necessitated a regimen change to start lazertinib after carboplatin completion.

RESULTS

All baseline characteristics were well balanced across the three arms, including by history of brain metastases and prior brain radiation. PFS was significantly longer for amivantamab-chemotherapy and amivantamab-lazertinib-chemotherapy versus chemotherapy [hazard ratio (HR) for disease progression or death 0.48 and 0.44, respectively; P < 0.001 for both; median of 6.3 and 8.3 versus 4.2 months, respectively]. Consistent PFS results were seen by investigator assessment (HR for disease progression or death 0.41 and 0.38 for amivantamab-chemotherapy and amivantamab-lazertinib-chemotherapy, respectively; P < 0.001 for both; median of 8.2 and 8.3 versus 4.2 months, respectively). Objective response rate was significantly higher for amivantamab-chemotherapy and amivantamab-lazertinib-chemotherapy versus chemotherapy (64% and 63% versus 36%, respectively; P < 0.001 for both). Median intracranial PFS was 12.5 and 12.8 versus 8.3 months for amivantamab-chemotherapy and amivantamab-lazertinib-chemotherapy versus chemotherapy (HR for intracranial disease progression or death 0.55 and 0.58, respectively). Predominant adverse events (AEs) in the amivantamab-containing regimens were hematologic, EGFR-, and MET-related toxicities. Amivantamab-chemotherapy had lower rates of hematologic AEs than amivantamab-lazertinib-chemotherapy.

CONCLUSIONS

Amivantamab-chemotherapy and amivantamab-lazertinib-chemotherapy improved PFS and intracranial PFS versus chemotherapy in a population with limited options after disease progression on osimertinib. Longer follow-up is needed for the modified amivantamab-lazertinib-chemotherapy regimen.

Identification of a large Myc-binding protein that contains RCC1-like repeats

The protooncogene MYC plays an important role in the regulation of cellular proliferation, differentiation, and apoptosis and has been implicated in a variety of human tumors. MYC and the closely related MYCN encode highly conserved nuclear phosphoproteins (Myc and NMyc) that apparently function as transcription factors in the cell. We have identified a large and highly conserved nuclear protein that interacts directly with the transcriptional activating domain of Myc (designated "protein associated with Myc" or Pam). Pam contains an extended amino acid sequence with similarities to a protein known as regulator of chromosome condensation (RCC1), which may play a role in the function of chromatin. The gene encoding Pam (PAM) is expressed in all of the human tissue examined, but expression is exceptionally abundant in brain and thymus. Pam binds specifically to Myc, but not NMyc. The region in Myc required for binding to Pam includes a domain that is essential for the function of Myc and that is frequently mutated in Burkitt's lymphomas. PAM is located within a 300-kb region on chromosome 13q22.

Cingulate cortex synaptic terminal proteins and neural cell adhesion molecule in schizophrenia

The neuronal organization and patterns of afferent innervation are abnormal in the cingulate cortex in schizophrenia, and associated changes in synaptic terminals could be present. A panel of monoclonal antibodies was defined with biochemical and fusion protein studies as detecting syntaxin (antibody SP6), synaptophysin (antibody SP4) and synaptosomal-associated protein-25 (antibody SP12). These antibodies and a polyclonal antibody reactive with neural cell adhesion molecule were used to investigate the cingulate cortex in schizophrenia. Immunocytochemistry indicated that syntaxin immunoreactivity had a considerably wider distribution than synaptophysin. Overall, multivariate analysis indicated increased synaptic terminal protein immunoreactivity in schizophrenia compared to controls (P=0.004). Controlled for age and post mortem interval, syntaxin immunoreactivity was significantly elevated in schizophrenia (P=0.004), and neural cell adhesion molecule immunoreactivity was also elevated (P=0.05). The neural cell adhesion molecule to synaptophysin ratio was increased (P=0.005), possibly indicating the presence of less mature synapses in schizophrenia. Elevated syntaxin immunoreactivity is consistent with increased glutamatergic afferents to the cingulate cortex in schizophrenia, and combined with the neural cell adhesion molecule to synaptophysin ratio results suggests that synaptic function in this region in schizophrenia may be abnormal.

Direct extraction of specific pharmacophoric flavonoids from gingko leaves using a molecularly imprinted polymer for quercetin

A new straightforward approach to extract active components from Chinese traditional herb was reported by using a molecularly imprinted polymer (MIP) as the sorbent material. The MIP was prepared using quercetin, a typical active compound of the flavonoid family in gingko leaves as the template. Acrylamide was used as the functional monomer and two polar solvent tetrahydrofuran was used as the porogen. Afterwards, the polymer was evaluated by chromatographic analysis. It exhibited high selectivity for quercetin and good affinity to its structural analogues. Specific binding amount of quercetin on the MIP in the solvent methanol was 12 microg/g polymer by the cartridge test. The MIP cartridge could directly trap a specific class of compounds including quercetin and kaempferol from the hydrolyzate of gingko leaves. The result demonstrated the possibility of direct extraction of certain pharmacophoric constituents from herb by MIP technology. The compounds extracted were confirmed by time-of-flight mass spectrometry.

The prevalence of schizophrenia in mainland China: evidence from epidemiological surveys

OBJECTIVE

Schizophrenia is a severe mental disorder. Its prevalence appears inconsistent in different regions of China; thus, we conducted this meta-analysis to estimate the prevalence of schizophrenia in mainland China.

METHOD

Studies on the prevalence of schizophrenia in mainland China were identified from electronic databases up to July 2013. Meta-analysis was used for prevalence of schizophrenia estimate.

RESULTS

For lifetime prevalence of schizophrenia, prevalence of 5.44 per 1000 (overall), 5.33 per 1000 (males), 5.51 per 1000 (females), 6.60 per 1000 (urban) and 4.73 per 1000 (rural) were estimated; there was no significant difference between males and females, while prevalence for urban dwellers was higher than for rural (OR=1.44, 95%CI: 1.30-1.59). For point prevalence of schizophrenia, prevalence of 4.62 per 1000 (overall), 4.63 per 1000 (males), 4.95 per 1000 (females), 5.15 per 1000 (urban) and 4.44 per 1000 (rural) were estimated; no statistical difference was found in males and females, but prevalence for urban dwellers was higher than for rural (OR=1.20; 95%CI: 1.02-1.41).

CONCLUSION

The prevalence estimate results were consistent with the international prevalence estimate of schizophrenia in mainland China. There was no significant difference between males and females, while prevalence for urban dwellers was higher than for rural.

Controlled delivery of mesenchymal stem cells and growth factors using a nanofiber scaffold for tendon repair

Outcomes after tendon repair are often unsatisfactory, despite improvements in surgical techniques and rehabilitation methods. Recent studies aimed at enhancing repair have targeted the paucicellular nature of tendon for enhancing repair; however, most approaches for delivering growth factors and cells have not been designed for dense connective tissues such as tendon. Therefore, we developed a scaffold capable of delivering growth factors and cells in a surgically manageable form for tendon repair. Platelet-derived growth factor BB (PDGF-BB), along with adipose-derived mesenchymal stem cells (ASCs), were incorporated into a heparin/fibrin-based delivery system (HBDS). This hydrogel was then layered with an electrospun nanofiber poly(lactic-co-glycolic acid) (PLGA) backbone. The HBDS allowed for the concurrent delivery of PDGF-BB and ASCs in a controlled manner, while the PLGA backbone provided structural integrity for surgical handling and tendon implantation. In vitro studies verified that the cells remained viable, and that sustained growth factor release was achieved. In vivo studies in a large animal tendon model verified that the approach was clinically relevant, and that the cells remained viable in the tendon repair environment. Only a mild immunoresponse was seen at dissection, histologically, and at the mRNA level; fluorescently labeled ASCs and the scaffold were found at the repair site 9days post-operatively; and increased total DNA was observed in ASC-treated tendons. The novel layered scaffold has the potential for improving tendon healing due to its ability to deliver both cells and growth factors simultaneously in a surgically convenient manner.

Effect of bilateral subthalamic nucleus stimulation on gait in Parkinson's disease

The fundamental disturbance of the parkinsonian gait is the reduction in walking velocity. This is mainly due to reduction in stride length, while cadence (steps/min) is slightly enhanced. Treatment with L-dopa increases stride length while cadence is unchanged. Chronic stimulation of the thalamus has no effect on Parkinsonian gait. The efficacy of electrical stimulation of the subthalamic nucleus (STN) on gait in advanced Parkinson's disease has been clearly demonstrated clinically. The aim of the present study was to quantify the changes in gait measures induced by STN stimulation and L-dopa and to assess possible differential or additive effects. Eight Parkinson's disease patients (mean +/- SD age 48.1 +/- 7.3 years) with chronic bilateral STN stimulation (mean duration of disease 13.3 +/- 2.4 years, mean stimulation time 15.4 +/- 10.6 months) and 12 age-matched controls were investigated. Subjects walked on a special treadmill with a closed-loop ultrasound control system that used the subject's position to adjust treadmill speed continuously for the actual walking velocity. In an appropriate crossover design, spatiotemporal gait measures and leg joint angle movements were assessed for at least 120 stride cycles in four treatment conditions: with and without stimulation and with and without a suprathreshold dose of L-dopa. With STN stimulation, there were increases of almost threefold in mean walking velocity (from 0.35 to 0.96 m/s) and stride length (from 0.34 to 0.99 m). Cadence remained constant. The range of motion of the major leg joints also increased. L-Dopa alone had a slightly weaker effect, with an increase in walking velocity to 0.94 m/s and in stride length to 0.92 m at a similar cadence. These increased values were in the range of those for healthy age-matched subjects performing the same task. The combination of both treatments further increased the mean walking velocity to 1.19 m/s and stride length to 1.20 m at an unchanged cadence. However, not all patients receiving STN stimulation improved further when they also received L-dopa. These results demonstrate that chronic bilateral STN stimulation, like treatment with L-dopa, improves walking velocity by increasing stride length without changing cadence. STN stimulation almost exclusively affects mechanisms involved in the control of spatial gait measures rather than rhythmicity. The gait measures obtained with STN stimulation alone are in the range of control subjects.

Social consensus through the influence of committed minorities

We show how the prevailing majority opinion in a population can be rapidly reversed by a small fraction p of randomly distributed committed agents who consistently proselytize the opposing opinion and are immune to influence. Specifically, we show that when the committed fraction grows beyond a critical value p(c) ≈ 10%, there is a dramatic decrease in the time T(c) taken for the entire population to adopt the committed opinion. In particular, for complete graphs we show that when p < pc, T(c) ~ exp [α(p)N], whereas for p>p(c), T(c) ~ ln N. We conclude with simulation results for Erdős-Rényi random graphs and scale-free networks which show qualitatively similar behavior.

Bending of blood vessel wall: stress-strain laws of the intima-media and adventitial layers

In order to determine the stress-strain relationship of the inner (intima and media) and outer (adventitia) layers of blood vessels in the neighborhood of the zero-stress state, bending experiments were performed on aortic strips of rats. In the experiments, one end of a strip was clamped, and a force was applied on the other end. The deflection curves of the strips were measured. By regarding the aortic strip as a curved beam, the classical beam theory was employed to analyze the strain distribution from the experimental data. A computer program dealing with nonlinear equations and nonlinear least squares optimization was developed. Strains were referred to the zero-stress state. The load-deflection relationship was then used to determine the stress-strain relationship. Certain forms of the stress-strain laws were assumed. The linear laws fit the experimental data accurately, probably because the strains during bending are quite small, although the rotations are large. The Young's modulus of the inner layer, which consists of endothelial and smooth muscle cells and elastic lamina, was found to be three to four times larger than that of the outer layer which consists of collagen with a small amount of fibroblasts and elastin. The residual stresses and strains at the no-load state were calculated from the deduced stress-strain relationship. It is shown that large errors (up to 50 percent) in the values of the residual strains will occur if the wall material was treated as homogeneous, i.e., if the layered constitution was ignored.

Nitric oxide production in experimental alcoholic liver disease in the rat: role in protection from injury

BACKGROUND & AIMS

Regulation of blood flow and oxygen supply are important pathogenetic factors in alcoholic liver disease. Because nitric oxide may have an important role, its effects on alcoholic liver injury were investigated.

METHODS

Rats were fed ethanol intragastrically with either saturated fat or corn oil. Spontaneous production of NO by liver nonparenchymal cells was compared in the two dietary groups. Two additional groups of rats fed corn oil and ethanol were treated with either an NO inhibitor (L-NAME) or supplemented with L-arginine. Liver pathology and plasma NO production were evaluated.

RESULTS

In the corn oil and ethanol group, a progressive decrease in liver nonparenchymal cell NO production and increased plasma NO levels were associated with liver injury. Reduced nicotinamide adenine dinucleotide phosphate diaphorase staining showed increased centrilobular staining of hepatocytes in the corn oil and ethanol group and L-NAME-treated group. Moreover, L-NAME increased the severity, whereas L-arginine supplementation completely prevented liver injury. In the saturated fat and ethanol group, in which there was no liver injury, the levels of NO2- in nonparenchymal supernatant were 5-10-fold higher than in the corn oil and ethanol group.

CONCLUSIONS

Decreased NO production by nonparenchymal cells may contribute to liver injury in ethanol-fed rats, and the compensatory increase in hepatocyte NO production may contribute to centrilobular liver injury.