COVID-19 associated Brugada pattern electrocardiogram: systematic review of case reports

Objective

To summarize published case reports of patients diagnosed with COVID-19 infection and Brugada pattern electrocardiogram (ECG).

Background

Fever is a common clinical manifestation of COVID-19 infection. Fever has also been associated with unmasking Brugada pattern ECG in patients and may result in life-threatening arrhythmia. Little is known regarding COVID-19 associated Brugada pattern ECG. There is paucity of data and guidance in how to manage these patients.

Methods

To identify all published case reports, the latest Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist was followed. A literature search was conducted using PubMed, EMBASE, and Scopus through September 2021. A systematic review was performed to identify the incidence, clinical characteristics, and management outcomes of COVID-19 patients with a Brugada pattern ECG.

Results

A total of 18 cases were collected. The mean age was 47.1 years and 11.1% were women. No patient had prior confirmed diagnosis of Brugada syndrome. The most common presenting clinical symptoms were fever (83.3%), chest pain (38.8%), shortness of breath (38.8%), and syncope (16.6%). All 18 patients presented with type 1 Brugada pattern ECG. Four patients (22.2%) underwent left heart catheterization, and none demonstrated the presence of obstructive coronary disease. The most common reported therapies included antipyretics (55.5%), hydroxychloroquine (27.7%), and antibiotics (16.6%). One patient (5.5%) died during hospitalization. Three patients (16.6%) who presented with syncope received either an implantable cardioverter defibrillator or wearable cardioverter defibrillator at discharge. At follow up, thirteen patients (72.2%) had resolution of type 1 Brugada pattern ECG.

Conclusion

COVID-19 associated Brugada pattern ECG is rare. Most patients may see resolution of the ECG pattern once their symptoms have improved. Increased awareness and timely use of antipyretics is warranted in this population.

Funding Acknowledgement

Type of funding sources: None.

Clinical and health status outcomes in nonagenarians undergoing transcatheter mitral valve repair

Background

Transcatheter mitral valve repair (TMVR) has emerged as an effective treatment in patients with mitral regurgitation due to degenerative valve disease and increased surgical risk. However, nonagenarians were excluded from the original TMVR trials and there is paucity of data.

Purpose

The aim of this study was to investigate the clinical and health status outcomes in nonagenarians undergoing TMVR.

Methods

This is a retrospective observational study of patients who underwent TMVR at a community hospital between June 2012 and December 2019. Baseline clinical characteristics and post-operative outcomes were collected and compared. This cohort of patients was stratified into three groups, age <80 (n=57), 80–89 (n=150) and ≥90 (n=40). Clinical outcomes assessed were procedural complications and 30-day and 1-year mortality. Health status was assessed using the 12-item Kansas City Cardiomyopathy Questionnaire overall summary score (KCCQ-OS) at baseline and at 1-month and 12-month follow-up.

Results

Overall there was no significant difference in procedural complications between the three groups (Table 1). Although not statistically significant, nonagenarians had higher rates of stroke (0% vs 0.6% vs 5%, p=0.053). 30-day and 1-year mortality were similar (p=0.796 and p=0.599). At baseline, there was significance difference in KCCQ-OS between three groups (27.0±20.8 vs 45.3±26.4 vs 41.1±26.2, p=0.ehab724.16483). However, there were no difference in KCCQ-OS at 1-month or 12-months (p=0.731 and p=0.561).

Conclusion

In our single center retrospective study, nonagenarians who underwent TMVR had similar clinical and health status outcomes compared to other age groups. TMVR appeared to be a safe and effective procedure in this patient population.

Funding Acknowledgement

Type of funding sources: None.

Early experience utilizing bivalirudin as anticoagulation in extracorporeal membrane oxygen in coronavirus disease 2019

Background

Extracorporeal membrane oxygenation (ECMO) is utilized as rescue therapy in patients diagnosed with coronavirus disease 2019 (COVID-19) with refractory respiratory or cardiogenic failure. Systemic anticoagulation with heparin remains the initial choice for thromboembolism prophylaxis in ECMO-treated patients. However, heparin carries the risk of severe complications, such as heparin-induced thrombocytopenia (HIT), and acquired antithrombin deficiency. Bivalirudin has been suggested as an alternative anticoagulant since it neither requires anti-thrombin III monitoring nor triggers HIT.

Purpose

There is very limited data on the utilization of bivalirudin in patients with COVID-19 treated with ECMO. We report the clinical safety and efficacy of using bivalirudin at our institution.

Methods

We retrospectively reviewed 17 patients diagnosed with COVID-19, who were treated with ECMO from 7/31/2020 to 12/20/2020. All patients received bivalirudin for thromboprophylaxis while on ECMO support.

Results

The mean age of our study cohort was forty-five years. Thirteen patients (76.4%) were of either Hispanic or African American descent. Of the seventeen patients, six (35.3%) patients developed deep venous thrombosis and one (5.9%) patient developed pulmonary embolism. Two (11.8%) patients developed a clotted circuit that required exchange. Fifteen (88.2%) patients had hemorrhage requiring transfusion with the gastrointestinal tract as the most common bleeding site. Nine (52.9%) patients developed thrombocytopenia. Six (35.3%) patients were discharged home or to a long-term acute care center; eleven (64.7%) patients died. The average length of stay was thirty-seven days.

Conclusion

In our small case series, the rates of complications and mortality remained high while using bivalirudin as anticoagulation of choice in patients diagnosed with COVID-19 and treated with ECMO. Further studies are needed to investigate the optimal anticoagulant in this population.

Funding Acknowledgement

Type of funding sources: None.

Transoral vertical ramus osteotomy fixed with Kirschner pins

Transoral vertical ramus osteotomy (VRO) has been condemned because the condyle has the potential to sag, and because it needs lengthy maxillomandibular fixation. We have therefore introduced a simple method of fixation, and examined its effectiveness and complications. After the osteotomy, the proximal and distal segments are trimmed to adapt to each other. Four Kirschner (K) pins 0.9mm in diameter are inserted percutaneously from the proximal to the distal segment while the condyle is positioned in the glenoid fossa. This is followed by a brief period of maxillomandibular fixation. We have reviewed the records of 95 patients who had unilateral or bilateral vertical ramus osteotomy fixed with K pins, after which the mean (SD) period of fixation was 19 (11) days. Fixation failed in two patients because excursion of the jaw was either too heavy or too early. The fixations were redone. All other fixations remained stable, including the 20 dual-jaw procedures in which VRO preceded maxillary osteotomy. The mean (SD) maximal mouth opening at final follow-up was 44 (7) mm, and in only one patient was it less than 30mm. Numbness of the lip or chin developed in seven patients, five of whom had other anterior mandibular procedures. Four patients had discomfort on palpation of the site of the pins, and one required removal. The new method was effective, and resulted in few complications within its limitations.

A Model of Yeast Cell-Cycle Regulation Based on a Standard Component Modeling Strategy for Protein Regulatory Networks

To understand the molecular mechanisms that regulate cell cycle progression in eukaryotes, a variety of mathematical modeling approaches have been employed, ranging from Boolean networks and differential equations to stochastic simulations. Each approach has its own characteristic strengths and weaknesses. In this paper, we propose a “standard component” modeling strategy that combines advantageous features of Boolean networks, differential equations and stochastic simulations in a framework that acknowledges the typical sorts of reactions found in protein regulatory networks. Applying this strategy to a comprehensive mechanism of the budding yeast cell cycle, we illustrate the potential value of standard component modeling. The deterministic version of our model reproduces the phenotypic properties of wild-type cells and of 125 mutant strains. The stochastic version of our model reproduces the cell-to-cell variability of wild-type cells and the partial viability of the CLB2-dbΔ clb5Δ mutant strain. Our simulations show that mathematical modeling with “standard components” can capture in quantitative detail many essential properties of cell cycle control in budding yeast.

Differential Gene Expression Profiles Reflecting Macrophage Polarization in Aging and Periodontitis Gingival Tissues

Recent evidence has determined a phenotypic and functional heterogeneity for macrophage populations. This plasticity of macrophage function has been related to specific properties of subsets (M1 and M2) of these cells in inflammation, adaptive immune responses and resolution of tissue destructive processes. This investigation hypothesized that targeted alterations in the distribution of macrophage phenotypes in aged individuals, and with periodontitis would be skewed towards M1 inflammatory macrophages in gingival tissues. The study used a non-human primate model to evaluate gene expression profiles as footprints of macrophage variation in healthy and periodontitis gingival tissues from animals 3-23 years of age and in periodontitis tissues in adult and aged animals. Significant increases in multiple genes reflecting overall increases in macrophage activities were observed in healthy aged tissues, and were significantly increased in periodontitis tissues from both adults and aged animals. Generally, gene expression patterns for M2 macrophages were similar in healthy young, adolescent and adult tissues. However, modest increases were noted in healthy aged tissues, similar to those seen in periodontitis tissues from both age groups. M1 macrophage gene transcription patterns increased significantly over the age range in healthy tissues, with multiple genes (e.g. CCL13, CCL19, CCR7 and TLR4) significantly increased in aged animals. Additionally, gene expression patterns for M1 macrophages were significantly increased in adult health versus periodontitis and aged healthy versus periodontitis. The findings supported a significant increase in macrophages with aging and in periodontitis. The primary increases in both healthy aged tissues and, particularly periodontitis tissues appeared in the M1 phenotype.

Experimental testing of a new integrated model of the budding yeast Start transition

Mathematical modeling of the cell cycle has unveiled recurrent features and emergent behaviors of cellular networks. Constructing new mutants and performing experimental tests during development of a new model of the budding yeast cell cycle yields a more efficient modeling process and results in several testable hypotheses.

The cell cycle is composed of bistable molecular switches that govern the transitions between gap phases (G1 and G2) and the phases in which DNA is replicated (S) and partitioned between daughter cells (M). Many molecular details of the budding yeast G1–S transition (Start) have been elucidated in recent years, especially with regard to its switch-like behavior due to positive feedback mechanisms. These results led us to reevaluate and expand a previous mathematical model of the yeast cell cycle. The new model incorporates Whi3 inhibition of Cln3 activity, Whi5 inhibition of SBF and MBF transcription factors, and feedback inhibition of Whi5 by G1–S cyclins. We tested the accuracy of the model by simulating various mutants not described in the literature. We then constructed these novel mutant strains and compared their observed phenotypes to the model’s simulations. The experimental results reported here led to further changes of the model, which will be fully described in a later article. Our study demonstrates the advantages of combining model design, simulation, and testing in a coordinated effort to better understand a complex biological network.

Quantifying midbrain serotonin transporter in depression: a preliminary study of diagnosis and naturalistic treatment outcome

INTRODUCTION

Serotonin may play an important role in the pathology of major depressive disorder (MDD). However, the relationship between serotonin transporter (SERT) availability and the medical outcome of antidepressant treatment is uncertain.

METHODS

In this naturalistic study, SERT availability (expressed as the specific uptake ratio, SUR) in the midbrain of 17 drug-free patients with MDD and 17 controls matched for age and gender was measured using SPECT with [(123)I]ADAM. The severity of MDD was measured by the Hamilton Depression Rating Scale before, and after 6 weeks of non-standardized antidepressant treatment.

RESULTS

A total of 12 patients completed the study. The SUR of the patients with MDD was significantly lower than that of the healthy controls. The SUR of SERT was not found to have a linear relationship with the treatment outcome; however, supplemental analysis found a curvilinear relationship between treatment outcome and the SUR of SERT.

DISCUSSION

The findings indicate that the SUR of SERT is lower in patients with MDD; however it did not predict treatment outcome in a linear fashion. Studies with larger sample sizes are required.

Experimental and numerical insights into isotropic spreading and deterministic dewetting of dielectrowetted films

Dielectrowetting effects of surface wrinkling, isotropic vs anisotropic spreading, electrode geometry, and deterministic dewetting are presented both experimentally and by 3D numerical modeling. The numerical results are generated by COMSOL in conjunction with the phase-field and electrohydrodynamic methods, including comparisons to experimental data. The dynamic behavior of the two-phase system has been accurately characterized on both the macro- and microscopic level. This work provides a deeper theoretical insight into the operating physics of dielectrowetting superspreading devices.

P300 waveform and dopamine transporter availability: a controlled EEG and SPECT study in medication-naive patients with schizophrenia and a meta-analysis

BACKGROUND

Reduced P300 event-related potential (ERP) amplitude and latency prolongation have been reported in patients with schizophrenia compared to healthy controls. However, the influence of antipsychotics (and dopamine) on ERP measures are poorly understood and medication confounding remains a possibility.

METHOD

We explored ERP differences between 36 drug-naive patients with schizophrenia and 138 healthy controls and examined whether P300 performance was related to dopamine transporter (DAT) availability, both without the confounding effects of medication. We also conducted a random effects meta-analysis of the available literature, synthesizing the results of three comparable published articles and our local study.

RESULTS

No overall significant difference was found in mean P300 ERP between patients and controls in latency or in amplitude. There was a significant gender effect, with females showing greater P300 amplitude than males. A difference between patients and controls in P300 latency was evident with ageing, with latency increasing faster in patients. No effect of DAT availability on P300 latency or amplitude was detected. The meta-analysis computed the latency pooled standardized effect size (PSES; Cohen's d) of -0.13 and the amplitude PSES (Cohen's d) of 0.48, with patients showing a significant reduction in amplitude.

CONCLUSIONS

Our findings suggest the P300 ERP is not altered in the early stages of schizophrenia before medication is introduced, and the DAT availability does not influence the P300 ERP amplitude or latency. P300 ERP amplitude reduction could be an indicator of the progression of illness and chronicity.

Efficient spin-light emitting diodes based on InGaN/GaN quantum disks at room temperature: a new self-polarized paradigm

A well-behaved spin-light emitting diode (LED) composed of InGaN/GaN multiple quantum disks (MQDs), ferromagnetic contact, and Fe3O4 nanoparticles has been designed, fabricated, and characterized. The degree of circular polarization of electroluminescence (EL) can reach up to a high value of 10.9% at room temperature in a low magnetic field of 0.35 T, which overcomes a very low degree of spin polarization in nitride semiconductors due to the weak spin-orbit interaction. Several underlying mechanisms play significant roles simultaneously in this newly designed device for the achievement of such a high performance. Most of all, the vacancy between nanodisks can be filled by half-metal nanoparticles with suitable energy band alignment, which enables selective transfer of spin polarized electrons and holes and leads to the enhanced output spin polarization of LED. Unlike previously reported mechanisms, this new process leads to a weak dependence of spin relaxation on temperature. Additionally, the internal strain in planar InGaN/GaN multiple quantum wells can be relaxed in the nanodisk formation process, which leads to the disappearance of Rashba Hamiltonian and enhances the spin relaxation time. Our approach therefore opens up a new route for the further research and development of semiconductor spintronics.

Lower availability of midbrain serotonin transporter between healthy subjects with and without a family history of major depressive disorder - a preliminary two-ligand SPECT study

PURPOSE

Serotonin transporter (SERT) and dopamine transporter (DAT) levels differ in patients with major depressive disorder (MDD) who are in a depressed state in comparison with healthy controls. In addition, a family history of depression is a potent risk factor for developing depression, and inherited vulnerability to serotonergic and dopaminergic dysfunction is suspected in this. The aim of this study was to examine the availabilities of midbrain SERT and striatal DAT in healthy subjects with and without a first-degree family history of MDD.

METHODS

Eight healthy subjects with first-degree relatives with MDD and 16 sex- and age-matched healthy controls were recruited. The availabilities of SERT and DAT were approximated using SPECT, employing [¹²³I] 2-((2-((dimethylamino) methyl) phenyl)thio)-5-iodophenylamine (ADAM) and [(⁹⁹m)Tc] TRODAT-1 as the ligands, respectively. There are missing data for one participant with a first-degree family history of MDD from the ADAM study, due to a lack of the radio-ligand at the time of experiment.

RESULTS

SERT availability in the midbrain was significantly lower in subjects with a first-degree family history of MDD than in healthy subjects. However, DAT availability was no different between two groups.

CONCLUSIONS

The results with regard to the midbrain SERT level suggest the heritability of MDD.

Top-down network analysis to drive bottom-up modeling of physiological processes

Top-down analyses in systems biology can automatically find correlations among genes and proteins in large-scale datasets. However, it is often difficult to design experiments from these results. In contrast, bottom-up approaches painstakingly craft detailed models that can be simulated computationally to suggest wet lab experiments. However, developing the models is a manual process that can take many years. These approaches have largely been developed independently. We present LINKER, an efficient and automated data-driven method that can analyze molecular interactomes to propose extensions to models that can be simulated. LINKER combines teleporting random walks and k-shortest path computations to discover connections from a source protein to a set of proteins collectively involved in a particular cellular process. We evaluate the efficacy of LINKER by applying it to a well-known dynamic model of the cell division cycle in Saccharomyces cerevisiae. Compared to other state-of-the-art methods, subnetworks computed by LINKER are heavily enriched in Gene Ontology (GO) terms relevant to the cell cycle. Finally, we highlight how networks computed by LINKER elucidate the role of a protein kinase (Cdc5) in the mitotic exit network of a dynamic model of the cell cycle.

Optimization and model reduction in the high dimensional parameter space of a budding yeast cell cycle model

Background

Parameter estimation from experimental data is critical for mathematical modeling of protein regulatory networks. For realistic networks with dozens of species and reactions, parameter estimation is an especially challenging task. In this study, we present an approach for parameter estimation that is effective in fitting a model of the budding yeast cell cycle (comprising 26 nonlinear ordinary differential equations containing 126 rate constants) to the experimentally observed phenotypes (viable or inviable) of 119 genetic strains carrying mutations of cell cycle genes.

Results

Starting from an initial guess of the parameter values, which correctly captures the phenotypes of only 72 genetic strains, our parameter estimation algorithm quickly improves the success rate of the model to 105–111 of the 119 strains. This success rate is comparable to the best values achieved by a skilled modeler manually choosing parameters over many weeks. The algorithm combines two search and optimization strategies. First, we use Latin hypercube sampling to explore a region surrounding the initial guess. From these samples, we choose ∼20 different sets of parameter values that correctly capture wild type viability. These sets form the starting generation of differential evolution that selects new parameter values that perform better in terms of their success rate in capturing phenotypes. In addition to producing highly successful combinations of parameter values, we analyze the results to determine the parameters that are most critical for matching experimental outcomes and the most competitive strains whose correct outcome with a given parameter vector forces numerous other strains to have incorrect outcomes. These “most critical parameters” and “most competitive strains” provide biological insights into the model. Conversely, the “least critical parameters” and “least competitive strains” suggest ways to reduce the computational complexity of the optimization.

Conclusions

Our approach proves to be a useful tool to help systems biologists fit complex dynamical models to large experimental datasets. In the process of fitting the model to the data, the tool identifies suggestive correlations among aspects of the model and the data.

Treadmill exercise improved adriamycin-induced nephropathy

Adriamycin nephropathy (AN) or doxorubicin-induced chronic kidney disease (DRCKD) has several strengths as an experimental model of renal diseases involving glomerulosclerosis, tubulointerstitial inflammation and fibrosis. Exercise has shown to be beneficial to many chronic diseases. We hypothesize that treadmill exercise may improve AN, and an investigation was carried out with the AN SD rat model. Treadmill exercise was conducted three times per week, each time for 30 and 60 min. DR induced swelling of glomeruli, collagen deposition in the interstitium and renal cortex, and increased the serum levels of MDA, IL-6, PDGF-BB, MMP-2, MMP-9, TGF-beta, p-PDGFR, uric acid, serum cholesterol, triglycerides, BUN, creatinine, blood platelet count, ratio of kidney to body weight, glomerular volume, and urinary BUN and protein. Conversely, levels of serum SOD, TNF-alpha, p-PI3K, p-Akt, albumin, WBC, RBC, and urinary creatinine were decreased. Treadmill exercise ameliorated most of these damaging effects, better outcome was found for the 60-min exercise training. Conclusively, the endurance exercise is more associated with the normalization of signaling expressions involving TGF-beta, PDGF-BB, p-PDGFR, p-PI3K, and p-Akt, which may help CKD patients to restore cell survival, proliferation, and growth. As rehabilitation is a personalized medicine, an appropriate design to fit individual feasibility has to be well figured out.

Ileocolorectal intussusception due to caecal hamartoma

Although 75% of intussusceptions occur within the first two years of life, they can also develop in teenage years. This is a case report of a 13-year old boy with an ileocolorectal intussusception from a large caecal hamartoma (10 x 6 x 2 cm3) adjacent to the ileocaecal valve. Partial resection of the ascending colon and terminal ileum was performed, and the pathology of the resected mass revealed a hamartoma. Ileocolorectal intussusception secondary to hamartoma represents a particularly rare event in the paediatric population. With early surgical intervention, this patient's outcome was uneventful.

Oscillatory dynamics of cell cycle proteins in single yeast cells analyzed by imaging cytometry

Progression through the cell division cycle is orchestrated by a complex network of interacting genes and proteins. Some of these proteins are known to fluctuate periodically during the cell cycle, but a systematic study of the fluctuations of a broad sample of cell-cycle proteins has not been made until now. Using time-lapse fluorescence microscopy, we profiled 16 strains of budding yeast, each containing GFP fused to a single gene involved in cell cycle regulation. The dynamics of protein abundance and localization were characterized by extracting the amplitude, period, and other indicators from a series of images. Oscillations of protein abundance could clearly be identified for Cdc15, Clb2, Cln1, Cln2, Mcm1, Net1, Sic1, and Whi5. The period of oscillation of the fluorescently tagged proteins is generally in good agreement with the inter-bud time. The very strong oscillations of Net1 and Mcm1 expression are remarkable since little is known about the temporal expression of these genes. By collecting data from large samples of single cells, we quantified some aspects of cell-to-cell variability due presumably to intrinsic and extrinsic noise affecting the cell cycle.

Stochastic exit from mitosis in budding yeast: model predictions and experimental observations

Unlike many mutants that are completely viable or inviable, the CLB2-dbΔ clb5Δ mutant of Saccharomyces cerevisiae is inviable in glucose but partially viable on slower growth media such as raffinose. On raffinose, the mutant cells can bud and divide but in each cycle there is a chance that a cell will fail to divide (telophase arrest), causing it to exit the cell cycle. This effect gives rise to a stochastic phenotype that cannot be explained by a deterministic model. We measure the inter-bud times of wild type and mutant cells growing on raffinose and compute statistics and distributions to characterize the mutant's behavior. We convert a detailed deterministic model of the budding yeast cell cycle to a stochastic model and determine the extent to which it captures the stochastic phenotype of the mutant strain. Predictions of the mathematical model are in reasonable agreement with our experimental data and suggest directions for improving the model. Ultimately, the ability to accurately model stochastic phenotypes may prove critical to understanding disease and therapeutic interventions in higher eukaryotes.

Microstructures and Mechanical Properties of Two-Phase Alloys Based on NbCr2

A two-phase, NbCrTi alloy (bce + C15 Laves phase) has been developed using several alloy design methodologies. In efforts to understand processing-microstructure-property relationships, different processing routes were employed. The resulting microstructures and mechanical properties are discussed and compared. Plasma arc melted (PAM) samples served to establish baseline, as-cast properties. In addition, a novel processing technique, involving decomposition of a supersaturated and metastable precursor phase during hot isostatic pressing (HIP), was used to produce a refined, equilibrium two-phase microstructure. Quasi-static compression tests as a function of temperature were performed on both alloy types. Different deformation mechanisms were encountered based upon temperature and microstructure.

Clustering and phases of compartmentalized granular gases

This paper experimentally investigates the clustering conditions for compartmentalized monodisperse granular gases, determining the critical particle number and condensation granular temperature at the gas-clustering transition. When one heavier intruding particle is added to a monodisperse gas, it is found that the condensation temperature decreases with the ratio of the mass of the intruding particle to that of the background particle. This phenomenon can be mathematically characterized by a proposed linear relation, which is reminiscent of a relation between the freezing point depression for a solvent and the concentration of an added solute. Finally we perform various tests by changing the numbers of two types of particles in bidisperse granular mixtures to construct the phase diagrams, which present the range of the five different states, namely, homogeneous gas, unstable-gas, one-clustering, two-clustering, and granular oscillation states.

A large chest wall tumour in an asymptomatic 15-year-old girl

A 15-year-old asymptomatic girl was found to have a large left lower chest wall mass associated with chest wall invasion on an opportunistic chest radiograph. The tumour was excised and shown to be a clear cell sarcoma. Adjuvant chemotherapy was administered and she was disease free at her 10 month follow up.

Global challenges as inspiration: a classroom strategy to foster social responsibility

Social responsibility is at the heart of the Engineer's Creed embodied in the pledge that we will dedicate [our] professional knowledge and skill to the advancement and betterment of human welfare... [placing] public welfare above all other considerations. However, half century after the original creed was written, we find ourselves in a world with great technological advances and great global-scale technologically-enabled peril. These issues can be naturally integrated into the engineering curriculum in a way that enhances the development of the technological skill set. We have found that these global challenges create a natural opportunity to foster social responsibility within the engineering students whom we educate. In freshman through senior-level materials engineering courses, we used five guiding principles to shape several different classroom activities and assignments. Upon testing an initial cohort of 28 students had classroom experiences based on these five principles, we saw a shift in attitude: before the experience, 18% of the cohort viewed engineers as playing an active role in solving global problems; after the experiences, 79% recognized the engineer's role in solving global-scale problems. In this paper, we present how global issues can be used to stimulate thinking for socially-responsible engineering solutions. We set forth five guiding principles that can foster the mindset for socially responsible actions along with examples of how these principles translate into classroom activities.

Analysis of a generic model of eukaryotic cell-cycle regulation

We propose a protein interaction network for the regulation of DNA synthesis and mitosis that emphasizes the universality of the regulatory system among eukaryotic cells. The idiosyncrasies of cell cycle regulation in particular organisms can be attributed, we claim, to specific settings of rate constants in the dynamic network of chemical reactions. The values of these rate constants are determined ultimately by the genetic makeup of an organism. To support these claims, we convert the reaction mechanism into a set of governing kinetic equations and provide parameter values (specific to budding yeast, fission yeast, frog eggs, and mammalian cells) that account for many curious features of cell cycle regulation in these organisms. Using one-parameter bifurcation diagrams, we show how overall cell growth drives progression through the cell cycle, how cell-size homeostasis can be achieved by two different strategies, and how mutations remodel bifurcation diagrams and create unusual cell-division phenotypes. The relation between gene dosage and phenotype can be summarized compactly in two-parameter bifurcation diagrams. Our approach provides a theoretical framework in which to understand both the universality and particularity of cell cycle regulation, and to construct, in modular fashion, increasingly complex models of the networks controlling cell growth and division.

Computer evaluation of network dynamics models with application to cell cycle control in budding yeast

Cellular processes are governed by complex networks of interacting genes and proteins. Theoretical molecular biologists attempt to describe these processes via mathematical models by writing biochemical reaction equations. Modellers are building increasingly larger and complex mathematical models to describe these cellular processes, making model evaluation a time consuming and difficult task. The authors describe an automatable process for model evaluation and a software system that implements this process. The software is adaptable to many types of models and is freely available along with all needed data files. The cell cycle control system for budding yeast is known in fine detail and constrained by more than 100 phenotypic observations in mutant strains. As an example, the authors apply their process to a model of cell cycle control in budding yeast containing dozens of regulatory equations and explaining nearly all of the known mutant phenotypes.

Quantitative characterization of a mitotic cyclin threshold regulating exit from mitosis

Regulation of cyclin abundance is central to eukaryotic cell cycle control. Strong overexpression of mitotic cyclins is known to lock the system in mitosis, but the quantitative behavior of the control system as this threshold is approached has only been characterized in the in vitro Xenopus extract system. Here, we quantitate the threshold for mitotic block in budding yeast caused by constitutive overexpression of the mitotic cyclin Clb2. Near this threshold, the system displays marked loss of robustness, in that loss or even heterozygosity for some regulators becomes deleterious or lethal, even though complete loss of these regulators is tolerated at normal cyclin expression levels. Recently, we presented a quantitative kinetic model of the budding yeast cell cycle. Here, we use this model to generate biochemical predictions for Clb2 levels, asynchronous as well as through the cell cycle, as the Clb2 overexpression threshold is approached. The model predictions compare well with biochemical data, even though no data of this type were available during model generation. The loss of robustness of the Clb2 overexpressing system is also predicted by the model. These results provide strong confirmation of the model's predictive ability.

Cloning and expression of the genes associated with lipid metabolism in Tsaiya ducks

Sterol regulatory element binding protein 1 (SREBP1) drives the expression of several lipogenic genes, whereas SREBP2 dictates the expression of every gene involved in cholesterolgenesis in mammals. In the current study, we cloned the cDNA fragments for SREBP1, SREBP2, fatty acid synthase (FAS), 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase), and very low density apolipoprotein-II (apoVLDL-II), the genes associated with lipid metabolism. Fifteen ducks immediately before the first egg was laid (18 wk old) and 15 ducks from the same population at an egg production rate of 80% were killed. Total RNA was extracted from liver and used to amplify the targeted genes by reverse transcription-PCR and screening of a cDNA library. The sequence data showed that Tsaiya duck SREBP1, SREBP2, FAS, and HMG-CoA reductase were highly homologous to that of chicken. Tsaiya duck SREBP1 mRNA was expressed in adipose tissue, cardiac muscle, skeletal muscle, liver, and ovary. The SREBP2 mRNA concentration was highest in liver and ovary. Concentrations of FAS and HMG-CoA reductase mRNA were high in liver and lower in other tissues. The apoVLDL-II mRNA was specifically expressed in the liver. The differences between mRNA concentrations of SREBP1, SREBP2, and FAS in the livers of laying and prelay ducks were not significant. However, the concentrations of hepatic HMG-CoA reductase and apoVLDL-II mRNA were higher in the laying ducks than in prelay ducks. Therefore, laying may affect particular aspects of lipid metabolism, especially biochemical pathways that involved apoVLDL-II and HMG-CoA reductase.

Integrative analysis of cell cycle control in budding yeast

The adaptive responses of a living cell to internal and external signals are controlled by networks of proteins whose interactions are so complex that the functional integration of the network cannot be comprehended by intuitive reasoning alone. Mathematical modeling, based on biochemical rate equations, provides a rigorous and reliable tool for unraveling the complexities of molecular regulatory networks. The budding yeast cell cycle is a challenging test case for this approach, because the control system is known in exquisite detail and its function is constrained by the phenotypic properties of >100 genetically engineered strains. We show that a mathematical model built on a consensus picture of this control system is largely successful in explaining the phenotypes of mutants described so far. A few inconsistencies between the model and experiments indicate aspects of the mechanism that require revision. In addition, the model allows one to frame and critique hypotheses about how the division cycle is regulated in wild-type and mutant cells, to predict the phenotypes of new mutant combinations, and to estimate the effective values of biochemical rate constants that are difficult to measure directly in vivo.

Modeling regulatory networks at Virginia Tech

The life of a cell is governed by the physicochemical properties of a complex network of interacting macromolecules (primarily genes and proteins). Hence, a full scientific understanding of and rational engineering approach to cell physiology require accurate mathematical models of the spatial and temporal dynamics of these macromolecular assemblies, especially the networks involved in integrating signals and regulating cellular responses. The Virginia Tech Consortium is involved in three specific goals of DARPA's computational biology program (Bio-COMP): to create effective software tools for modeling gene-protein-metabolite networks, to employ these tools in creating a new generation of realistic models, and to test and refine these models by well-conceived experimental studies. The special emphasis of this group is to understand the mechanisms of cell cycle control in eukaryotes (yeast cells and frog eggs). The software tools developed at Virginia Tech are designed to meet general requirements of modeling regulatory networks and are collected in a problem-solving environment called JigCell.

Cycling without the cyclosome: modeling a yeast strain lacking the APC

The construction of viable Saccharomyces cerevisiae strains that lack the anaphase promoting complex (APC) was recently reported. The normally lethal deletions of APC genes were suppressed by the double deletion of the PDS1 and CLB5 genes in conjunction with the insertion of multiple copies of the SIC1 gene controlled by its endogenous promoter. It was proposed that cyclic expression and degradation of Sic1 results in oscillations of Clb/CDK activity necessary for the cell cycle. We have used an updated version of a mathematical model of the yeast cell cycle to model strains that lack the APC. With a few modifications, the model accurately simulates the viability of Apc- strains, as well as the phenotypes of 27 other previously characterized strains. We discuss a few minor inconsistencies between the model and experiment, and how these may inform future revisions to the model.

Neurotrophic effects of vascular endothelial growth factor and neurotrophins on cultured major pelvic ganglia

OBJECTIVE

To investigate the feasibility of using a ganglial culture system to screen various growth factors as potential therapeutic agents for pelvic nerve injuries.

MATERIALS AND METHODS

The major pelvic ganglia (MPG) were isolated from male rats and attached to culture dishes with the aid of Matrigel (Becton Dickinson, Mountain View, CA, USA). Alternatively, the dorso-caudal region (DCR) of MPG, from which the cavernous nerves originate, was dissected and then attached to a Matrigel-coated coverslip. The MPG or DCR was cultured in serum-free medium supplemented with phosphate-buffered saline (PBS, control), 50 ng/mL of vascular endothelial growth factor (VEGF), 20 ng/mL of a neurotrophin (BDNF, NT3, or NT4), or combinations of these growth factors. After 2 days of incubation, the ganglial tissues with their outgrowing nerve fibres were stained for the expression of NADPH-diaphorase, tyrosine hydroxylase (TH) and acetylcholinesterase (AChE). The length and staining intensity of nerve fibres were analysed.

RESULTS

The outgrowing fibres were significantly longer in MPG treated with any of the four tested growth factors than in PBS-treated MPG. The combination of VEGF and NT3 induced the best fibre growth. Improvements to the culturing conditions allowed a histological examination of the outgrowing fibres for the expression of nitric oxide synthase (NOS), TH and AChE. VEGF and BDNF were equally capable of inducing NOS- and TH-expressing fibres. BDNF was much weaker than VEGF for inducing AChE-expressing fibres.

CONCLUSIONS

This improved culturing system is potentially useful for screening nerve-regenerating factors; VEGF had neurotrophic effects comparable with BDNF, NT3, or NT4.

Sniffers, buzzers, toggles and blinkers: dynamics of regulatory and signaling pathways in the cell

The physiological responses of cells to external and internal stimuli are governed by genes and proteins interacting in complex networks whose dynamical properties are impossible to understand by intuitive reasoning alone. Recent advances by theoretical biologists have demonstrated that molecular regulatory networks can be accurately modeled in mathematical terms. These models shed light on the design principles of biological control systems and make predictions that have been verified experimentally.

Ductal adenocarcinoma of the prostate with endometrioid features in a 69-year-old man

We describe a case of ductal adenocarcinoma of the prostate with endometrioid characteristics presenting as painless hematuria and intraurethral tumor. A 69-year-old man had intermittent painless hematuria for 2 months. The serum prostate-specific antigen concentration was elevated (22.0 ng/mL). An enlarged prostate with a necrotic tumor was noted in the right lobe of the prostate on computerized tomography and magnetic resonance imaging studies. A polypoid and worm-like tumor was found within the prostatic urethra near the verumontanum. The tumor had a distinctly papillary configuration with a focal glandular structure on microscopy. Radical prostatectomy was performed and histology of the tumor specimen revealed it to be composed of a closely packed glandular structure lined by single layers of high columnar cells with focal stratification. Frequent papillary projections of glandular epithelium and intraglandular bridging were noted, with a histopathologic appearance similar to endometrioid carcinoma of the uterus. Androgen deprivation therapy was started immediately following surgery. No evidence of recurrence or metastasis was found at follow-up 27 months postoperatively. Distinct features of ductal adenocarcinoma of the prostate include intraurethral papillary tumor close to the verumontanum, urethral obstruction, and easy bleeding of the tumor. Its more aggressive behavior than classical microacinar adenocarcinoma of the prostate makes early recognition of this type of prostatic malignancy important.

Gene expression profiling of an arteriogenic impotence model

Penile arterial insufficiency is one of the most common causes of ED. We have established a traumatic arteriogenic insufficiency rat model by the ligation of the pudendal arteries. To simulate both acute and chronic traumatic injuries, five ligation periods (6 h, 3 days, 7 days, 3 weeks, and 6 weeks) were chosen. By electrostimulation of the cavernous nerve, the intracavernous pressure was determined to be between 20 and 40-cm H(2)O for the ligated rats compared to around 100-cm H(2)O for the control rats. The erectile tissue in the corpus cavernosum of these rats was then subjected to microarray analysis, in which an array that contains cDNA fragments representing 1176 rat genes was used. The results demonstrated that normal rat corpus cavernosum expressed approximately 200 genes at detectable levels and that ligation produced differential expression of approximately 25 genes, depending on the duration of ligation. The most highly ligation-induced gene was apolipoprotein D (ApoD), with peak expression in the 3- and 7-day ligated rats. Three of the insulin-like growth factor binding proteins (IGFBP-1, 3, and 5) were upregulated in all ligated rats. IGFBP-6, which was one of the most highly expressed genes in the normal corpus cavernosum, was down-regulated in all ligated rats. Cysteine proteases of the cathepsin family were also differentially expressed between control and ligated rats, with cathepsin K being down-regulated most. A few genes were upregulated only in the 6-week ligated rats, including angiotensin-converting enzyme. Finally, VEGF, whose induction has been identified in many other ischemic tissues, was not induced in corpus cavernous tissue of ligated rats.

Duodenojejunal intussusception secondary to hamartomatous polyps of duodenum surrounding the ampulla of Vater

Duodenojejunal intussusception is a rare pediatric emergency. A case of duodenojejunal intussusception secondary to hamartomatous polyps of the second portion of duodenum in a 10-month-old boy is reported. Surgical excision of the polyps and reduction of the intussusception were performed. Pathologic examination found hamartomatous polyps. This is the third case report of children in literature, but this is the first case of a child with intussusception surrounding the ampulla of Vater and a successful excision performed without damaging the ampulla of Vater.

Purification and characterization of isoforms of beta-galactosidases in mung bean seedlings

Five isoforms of beta-galactosidase (EC 3.2.1.23), designated as beta-galactosidases I-V, were isolated from five-day-old mung bean (Vigna radiata) seedlings. Beta-galactosidases II and III were purified to electrophoretic homogeneity by a procedure involving acid precipitation, ammonium sulfate fractionation, chromatography on diethylaminoethyl-cellulose (DEAE-Cellulose) and con A-Sepharose. and chromatofocusing. Beta-galactosidases I, II and III have the same molecular mass of 87 kDa. comprising two nonidentical subunits with molecular masses of 38 and 48 kDa, while beta-galactosidases IV and V have molecular masses of 45 and 73 kDa, respectively. All the enzymes were active against p-nitrophenyl-beta-D-galactoside, and to a lesser extent, p-nitrophenyl-alpha-L-arabinoside and p-nitrophenyl-beta-D-fucoside. The enzymes were inhibited by D-galactono-1,4-lactone, D-galactose, Hg2+, Ag+ and sodium dodecyl sulfate (SDS). Beta-galactosidases I, II and III were shown to be competitively inhibited by either D-galactono-1, 4-lactone or D-galactose. Isoforms I, II and III have a common optimal pH of 3.6, while isoforms IV and V have pH optima at 3.8 and 4.0, respectively. Isoelectric points of isoforms I, II and III were 7.7, 7.5 and 7.3, respectively. Double immunodiffusion analysis indicated that beta-galactosidases I, II, III and V are immunologically similar to each other, while beta-galactosidase IV shares partially identical antigenic determinants with the other four isoforms. The purified beta-galactosidases II and III were capable of releasing D-galactose residue from the hemicellulose fraction isolated from mung bean seeds.

Dynamics of changes in micronucleus frequencies in subjects post cessation of chronic low-dose radiation exposure

To assess DNA damage remaining in peripheral lymphocytes, 48 individuals were evaluated twice for lymphocyte micronucleus frequencies by the cytokinesis-blocking cytochalasin B (CBMN) analysis post relocation from radio-contaminated apartments after various periods of time. The frequencies of CBMN at the first evaluation were significantly higher than those at the second examination (Chang et al., 1999c). These individuals were categorized into three groups: those with cumulative exposure of >300 mSv (defined as high exposure, HDose), those with 100-300 mSv (MDose) and those with <100 mSv (LDose). Using the Poisson mixed-effect model (Little et al., 1996), the estimated mean CBMN frequencies ( per thousand) for individuals in HDose, MDose and LDose exposure categories when they had only recently relocated were 21.8, 17.6 and 15.4, respectively. The estimated mean duration post relocation for the CBMN frequencies of these individuals to reduce to 10.2, the second CBMN frequency, on average, was 47.5, 37.2 and 28.3 months in the three exposure groups, respectively. The rates of change in CBMN frequencies were shown to be significantly higher in the HDose group than in the MDose and LDose groups. The results suggested a characteristic dose-dependent decline in the CBMN frequencies in the exposed population post cessation of chronic low-dose ionizing radiation exposure.

Legal and ethical considerations of assisted reproductive technology and surrogate motherhood in AOFOG countries

With increasing use of assisted reproductive technologies (ART) and its related issues, the Ethics Committee of the Asia-Oceania Federation of Obstetrics and Gynecology (AOFOG), after discussion at its council meeting, took up the mission to understand the current legal and ethical aspects of this special subject in Asia-Oceania area before making proper recommendations. This Committee drafted a questionnaire to all 22 country member societies in 1995, and again conducted the same survey in 2000 to track changes in each country/region's laws and regulations. The results show that the current attitude and status of country member societies vary in a wide range and do not have formal legal codes in majority regulating the ethical aspects of ART. The use of ART and surrogacy is obviously affected by local traditions, popularity in the use of such techniques and cultural/religious concerns. The changes in 5 years are not major. Three countries do not as yet practice such techniques. However, liberalization of surrogate motherhood has become a trend. Five countries, compared with two only in 1995, are now available for surrogate motherhood, though regulated by strict criteria. Based on the data collected and issues discussed, a detailed guideline may not be generally applicable as each region has its own rules, reflecting differences in the management of ART, especially in the surrogate motherhood. This Committee therefore recommends that ART must be performed by a board certified gynecologist in a certification laboratory and surrogate motherhood must be used only for medical reasons and not be commercialized. The patients of this special group must be treated individually, based on this recommendation and the regulations of their own country/region.

Juvenile papillomatosis of the breast in a 9-year-old girl

Juvenile papillomatosis (JP) is a rare benign, proliferative breast tumor in children. We observed a 9-year-old girl with a large soft-tissue mass at the lower outer quadrant of the left breast. Ultrasonography showed an ill-defined, inhomogeneous mass with numerous small, hypoechoic areas. The tumor was completely excised. Histopathology revealed JP of the breast. The case is presented and the literature is reviewed.

Epilepsy-induced decrease of L-type Ca2+ channel activity and coordinate regulation of subunit mRNA in single neurons of rat hippocampal 'zipper' slices

L-type voltage-sensitive Ca2+ channels (VSCCs) preferentially modulate several neuronal processes that are thought to be important in epileptogenesis, including the slow afterhyperpolarization (AHP), LTP, and trophic factor gene expression. However, little is yet known about the roles of L-type VSCCs in the epileptogenic process. Here, we used cell-attached patch recording techniques and single cell mRNA analyses to study L-type VSCCs in CA1 neurons from partially dissociated (zipper) hippocampal slices from entorhinally-kindled rats. L-type Ca2+-channel activity was reduced by >50% at 1.5-3 months after kindling. Following recording, the same single neurons were extracted and collected for mRNA analysis using a recently developed method that does not amputate major dendritic processes. Therefore, neurons contained essentially full complements of mRNA. For each collected neuron, mRNA contents for the L-type pore-forming alpha1D/Ca(v)1.3-subunit and for calmodulin were then analyzed by semiquantitative kinetic RT-PCR. L-type alpha1D-subunit mRNA was correlated with L-type Ca2+-channel activity across single cells, whereas calmodulin mRNA was not. Thus, these results appear to provide the first direct evidence at the single channel and gene expression levels that chronic expression of an identified Ca2+-channel type is modulated by epileptiform activity. Moreover, the present data suggest the hypothesis that down regulation of alpha1D-gene expression by kindling may contribute to the long-term maintenance of epileptiform activity, possibly through reduced Ca2+-dependent AHP and/or altered expression of other relevant genes.

Diffusion of molecules in brain extracellular space: theory and experiment

Volume transmission depends on the migration of informational substances through brain extracellular space (ECS) and almost always involves diffusion; basic concepts of diffusion are outlined from both the microscopic viewpoint based on random walks and the macroscopic viewpoint based on the solution of equations embodying Fick's Laws. In a complex medium like the brain, diffusing molecules are constrained by the local volume fraction of the ECS and tortuosity, a measure of the hindrance imposed by cellular obstacles. Molecules can also experience varying degrees of uptake or clearance. Bulk flow and the extracellular matrix may also play a role. Examples of recent work on diffusion of tetramethylammonium (molecular weight, 74) in brain slices, using iontophoretic application and ion-selective microelectrodes, are reviewed. In slices, the volume fraction is about 20% and tortuosity about 1.6, both similar to values found in the intact brain. Using integrative optical imaging, results obtained with dextrans and albumins up to a molecular weight of 70,000 are summarized, for such large molecules the tortuosity is about 2.3. Experiments using synthetic long-chain PHPMA polymers up to 1,000,000 molecular weight show that these molecules also diffuse in the ECS but with a tortuosity of about 1.6. Studies with osmotic challenge show that volume fraction and tortuosity do not vary together as expected when the size of the ECS changes; a model is presented that explains the osmotic-challenge on the basis of changes in cell shape. Finally, new analytical insights are provided into the complex movement of potassium in the brain.

Effects of Nd:YAG laser irradiation on cultured human gingival fibroblasts

BACKGROUND AND OBJECTIVE

The Nd:YAG laser has been proposed to apply in minor soft tissue surgery, including various periodontal procedures. However, little information is available regarding the direct effect of Nd:YAG laser on gingival fibroblasts, which play an important role in the early healing processes of periodontal repair.

STUDY DESIGN/MATERIALS AND METHODS

Nd:YAG laser irradiation was performed in pulsed mode on human gingival fibroblasts, which was derived from healthy human gingiva by an explant method. The size of laser diode was 400 microm in diameter. The parameters in laser delivery were pulse energy (50-150 mJ), power output (1.0-3.0 W), pulse rate (10-30 pps), and fixed duration of irradiation (10 seconds). The cell cultures were analysed by cytomorphologic examination under phase-contrast and scanning electron microscope. The vitality was also examined with the help of MTT staining.

RESULTS

The area of laser damage on cell culture was circular in shape, with diameter beyond the size of laser diode. By scanning electron microscopy, we observed the cellular damage of cultured gingival fibroblasts induced by Nd:YAG laser irradiation, comparable with the progressive increased power settings. The cytomorphologic changes ranged from disappearance of cellular boundary, loss of identifiable cellular nucleus, and finally cell contraction and vacuolization. Significant decrease in cellular vitality (14% approximately 44%) after laser treatment with irradiation distance of nearly contact was noted. However, 2 mm defocusing irradiation with the same power settings did not significantly decrease cellular vitality.

CONCLUSION

Our study demonstrated the cell damaging effects of Nd:YAG laser, ranging from degeneratively cytomorphologic change to cell death, on the cultured human gingival fibroblasts. It provided the dentist a chance to understand the potential hazard of laser application in periodontal treatment. If the energy output is enough for the clinical purposes, Nd:YAG laser with lower pulse energy and corresponding pulse rate should be selected to minimize the damage on adjacent soft tissue.

Measurement of the size and orientation of human masseter and medial pterygoid muscles

To gain a better understanding of biting and chewing performance, the size and orientation of the masseter and medial pterygoid muscles in living humans were studied. Twenty-seven young males having complete dentition, class I dental occlusion and normal muscle and jaw function were examined using magnetic resonance images of the head between the zygomatic arch and hyoid bone. The sections were parallel to the palatal plane, and the thickness was 3 mm without a gap. A computer software program (Medical Dental Image, MDI) was developed to identify and calculate the area of each cross section of the muscle, and the volume of the muscle was then estimated. The axis of the muscle was determined by connecting the centroids of the sections in the lower and upper 1/3 of the whole muscle. The effective muscle cross section area was then calculated by resectioning the muscle perpendicularly to the muscle axis. It was found that the mean masseter muscle volume was around 31 cm3, and that the mean medial pterygoid muscle volume was 11 cm3. Their mean effective cross section areas were around 6.2 cm2 and 3.5 cm2, respectively. The axis of the masseter muscle was more perpendicular to the palatal plane and parallel to the sagittal plane than was the medial pterygoid muscle. The results suggest that the use of magnetic resonance images (MRI) is an effective noninvasive measurement technique for determining the size and orientation of masseter and medial pterygoid muscles. This technique can be employed in future studies on human bite force evaluation and masticatory function.

Vitamin D hormone confers neuroprotection in parallel with downregulation of L-type calcium channel expression in hippocampal neurons

Although vitamin D hormone (VDH; 1,25-dihydroxyvitamin D(3)), the active metabolite of vitamin D, is the major Ca(2+)-regulatory steroid hormone in the periphery, it is not known whether it also modulates Ca(2+) homeostasis in brain neurons. Recently, chronic treatment with VDH was reported to protect brain neurons in both aging and animal models of stroke. However, it is unclear whether those actions were attributable to direct effects on brain cells or indirect effects mediated via peripheral pathways. VDH modulates L-type voltage-sensitive Ca(2+) channels (L-VSCCs) in peripheral tissues, and an increase in L-VSCCs appears linked to both brain aging and neuronal vulnerability. Therefore, we tested the hypothesis that VDH has direct neuroprotective actions and, in parallel, targets L-VSCCs in hippocampal neurons. Primary rat hippocampal cultures, treated for several days with VDH, exhibited a U-shaped concentration-response curve for neuroprotection against excitotoxic insults: lower concentrations of VDH (1-100 nm) were protective, but higher, nonphysiological concentrations (500-1000 nm) were not. Parallel studies using patch-clamp techniques found a similar U-shaped curve in which L-VSCC current was reduced at lower VDH concentrations and increased at higher (500 nm) concentrations. Real-time PCR studies demonstrated that VDH monotonically downregulated mRNA expression for the alpha(1C) and alpha(1D) pore-forming subunits of L-VSCCs. However, 500 nm VDH also nonspecifically reduced a range of other mRNA species. Thus, these studies provide the first evidence of (1) direct neuroprotective actions of VDH at relatively low concentrations, and (2) selective downregulation of L-VSCC expression in brain neurons at the same, lower concentrations.

Correlation of cervical vertebra maturation with hand-wrist maturation in children

The purpose of this study was to evaluate the reliability of cervical vertebra maturation as an indicator of skeletal age during the circumpubertal period. This was determined by correlating cervical vertebra maturation to hand-wrist maturation. The vertebral skeletal age was assessed using lateral cephalometric radiographs according to maturity indicators modified from Lamparski. The hand-wrist skeletal age was evaluated in radiographs with the system developed by Fishman. The sample consisted of 503 subjects (244 boys and 259 girls), aged 8 through 18 years. The Spearman rank correlation coefficients and Wilcoxon sign rank test showed that a statistically significant relationship existed between the two assessments. Both the intra- and inter-judge tests of reliability displayed no significant differences. The results of this study indicate that skeletal age assessment made from the maturational changes of cervical vertebrae were reliable, reproducible and valid.

Perinatal outcome of oligohydramnios without associated premature rupture of membranes and fetal anomalies

To investigate the perinatal outcome of patients with oligohydramnios (amniotic fluid index < or = 5 cm), but without premature rupture of membranes and fetal congenital anomalies, data from 245 singleton pregnancies were analyzed and compared to those with normal amniotic fluid volumes (5 < amniotic fluid index < 24 cm, n=27,261). Significantly higher incidences of primiparity, pregnancy-induced hypertension, premature separation of placenta, past history of intrauterine fetal death, past history of preterm delivery, postterm pregnancy, and advanced maternal age were noted to be associated with the occurrence of oligohydramnios. Pregnancies complicated by a markedly diminished amniotic fluid volume assessed antenatally by ultrasound were significantly more frequently associated with adverse perinatal outcomes such as preterm delivery, low or very low birth weight, low Apgar scores, intrauterine fetal death, small-for-gestational-age newborns, meconium staining, cesarean delivery, neonatal intensive care, and neonatal death.

Comparison of landmark identification in traditional versus computer-aided digital cephalometry

The aim of this study was to assess landmark identification on digital images in comparison with those obtained from original radiographs. Ten cephalometric radiographs were selected randomly. Seven orthodontic residents identified 19 cephalometric landmarks on both the original radiographs and the digital images. To assess the concordance between landmarks identified on the original radiographs and on their digital counterparts, the x, y coordinates for each landmark in the 2 modalities were transformed with the identical references. The placement differences for 19 landmarks between 2 methods were calculated and their components in horizontal and vertical directions were analyzed respectively. Multivariate analysis of variance showed that the "cephalometric radiograph" and "landmark" variation had greater influence than that from "method" (landmark identification on digital / original radiograph). It was also noted that the differences of landmark identification between original radiographs and their digital counterparts were statistically significant. The landmarks with significant differences of horizontal component on the x-axis were Me, Gn, ANS, PNS, LIA. The differences were generally under 1 mm with the exception of Or, Me, PNS, LIA. The landmarks with significant differences of vertical component on the y-axis were Po, Or, Gn. The inter-observer error for each landmark in digital images was generally larger than that in the original radiographs. However, statistically significant differences of inter-observer errors between 2 modalities were only found for 4 of the 19 landmarks. These 4 landmarks, Po, Ar, ANS, and UM, should be scrutinized more carefully during potential applications of digital cephalometry.

Expression of functional type 1 protease-activated thrombin receptors by mouse primary palatal mesenchymal cells in vitro

Development of the primary palate involves a series of processes including cell growth, differentiation, and morphogenesis. To study the molecular and cellular processes during mouse primary palatogenesis, mesenchymal cells were isolated from the primary palate of BALB/cBy embryos (day-11, hour 20). Most of the primary palatal mesenchymal (PPM) cells were morphologically similar to fibroblasts. The population doubling time was about 36 h. At concentrations of 5 and 10 unit/ml, alpha-thrombin significantly stimulated the proliferation of these palatal cells by 2- to 2. 4-fold compared to untreated controls over a 72 hour incubation period. Reverse transcriptase-polymerase chain reaction using primers based on the mouse type 1 protease-activated thrombin receptor (PAR1) detected PAR1 mRNA in the PPM cells, the authenticity of which was confirmed by partial DNA sequencing. Blocking of the alpha-thrombin proteolytic site with the highly specific inhibitor D-phenylalanyl-prolyl-arginyl chloromethyl ketone significantly suppressed the mitogenic effect of thrombin on the PPM cells by 71%. These results suggest that PAR1 is present on PPM cells in the mouse embryo and that serine protease activity is important for the receptor activation.

Dissection of the XChk1 signaling pathway in Xenopus laevis embryos

Checkpoint pathways inhibit cyclin-dependent kinases (Cdks) to arrest cell cycles when DNA is damaged or unreplicated. Early embryonic cell cycles of Xenopus laevis lack these checkpoints. Completion of 12 divisions marks the midblastula transition (MBT), when the cell cycle lengthens, acquiring gap phases and checkpoints of a somatic cell cycle. Although Xenopus embryos lack checkpoints prior to the MBT, checkpoints are observed in cell-free egg extracts supplemented with sperm nuclei. These checkpoints depend upon the Xenopus Chk1 (XChk1)-signaling pathway. To understand why Xenopus embryos lack checkpoints, xchk1 was cloned, and its expression was examined and manipulated in Xenopus embryos. Although XChk1 mRNA is degraded at the MBT, XChk1 protein persists throughout development, including pre-MBT cell cycles that lack checkpoints. However, when DNA replication is blocked, XChk1 is activated only after stage 7, two cell cycles prior to the MBT. Likewise, DNA damage activates XChk1 only after the MBT. Furthermore, overexpression of XChk1 in Xenopus embryos creates a checkpoint in which cell division arrests, and both Cdc2 and Cdk2 are phosphorylated on tyrosine 15 and inhibited in catalytic activity. These data indicate that XChk1 signaling is intact but blocked upstream of XChk1 until the MBT.