How does a beta -hairpin fold/unfold? competition between topology and heterogeneity in a solvable model

We study the competition between topological effects and sequence inhomogeneities in determining the thermodynamics and the un/folding kinetics of a beta-hairpin. Our work utilizes a new exactly solvable model that allows for arbitrary configurations of native contacts. In general, the competition between heterogeneity and topology results in a crossover of the dominant transition state. Interestingly, near this crossover, the single reaction coordinate picture can be seriously misleading. Our results also suggest that inferring the folding pathway from unfolding simulations is not always justified.

Multielectron effects on single-electron strong field ionization

An apparently simple phenomenon of single-electron strong field ionization involves subtle factors related to multielectron effects. A single electron in an atom or molecule can feel a distinctly different screening strength when exposed to strong fields as opposed to weak fields, and this electron screening due to multielectron motion influences single-electron ionization. The concept and a corresponding model developed in the paper allow a generalization of the Ammosov-Delone-Krainov model for predicting strong field ionization rates of more complicated atoms and molecules. This general approach explains the recently observed anomalous low single ionization rate in O2.

[A study on incidence of injury and its socio-economic loss in children and young adults]

OBJECTIVES

To study the current status of incidence of injury among children and young adults and the causes of common injuries, and to estimate its socio-economic loss and extent of harmfulness.

METHODS

Pupils in 19 primary and middle schools aged 7 to 18 years, totaling 14,533, were recruited with stratified cluster sampling during 1998 to 1999 in Guangzhou, Maoming, Jiangmen and Shantou. Judgement for injury was based on the following criteria: (1) diagnosed and treated in hospitals or school clinics, (2) a half-day off or more due to injury, and (3) emergency management by pupils' parents or teachers.

RESULTS

There were 6 941 pupils suffered from varied injures during the year, with an incidence rate of 47.76% (50.08% for boys and 45.02% for girls). Incidence rate of injury was higher in the middle school pupils (13 - 18 years old, 58.49%) than that in the primary school pupils (7 - 12 years old, 40.08%). The incidence increased significantly with age, with a peak at ages of 13 - 15. Major causes of injuries resulted from falls, injury by sharp articles, collision, traffic injuries and burn/scalds, etc, which usually occurred due to carelessness in sports, playing, walking, bike-riding and working. Frequency of multiple injuries related to the educational level of parents and depended on whether or not an only-child in family. There were 2,173 injured pupils (accounting for 31.3% of the total) visited clinics or emergency department in hospitals and 627 (9.0%) hospitalized for treatment. Twenty-eight percent of the injured pupils were absent from school, with an average absenteeism of 5.6 days. There were 154 injured pupils with transient disability and 53 with permanent disability, with a disability rate of 410.47 per 100,000. Cost for their medical care averaged 81.5 yuan RMB per injured pupil.

CONCLUSIONS

Injury was a common and frequently-happened incident among children and young adults and could seriously affect their health, development and growth, studying and their future of children and young adults. Health education, safety-promotion and removing hidden danger for injury are the major measures to prevent from injury, and the government and the whole society should pay great attention to injury issues in children and young adults.

Behavioral and emotional problems in Chinese children of divorced parents

OBJECTIVE

This study examined the behavioral problems in Chinese children of divorced parents.

METHOD

A total of 58 children of divorce and 116 gender-, age-, and school class-matched controls were ascertained from a general population sample of children aged 6 through 15 years. Parents completed the Child Behavior Checklist (CBCL), and teachers completed the Teacher's Report Form (TRF) and Conners Hyperkinesis Index.

RESULTS

Parent-reported problem scores on the CBCL total scale and each subscale, and prevalence of all CBCL syndromes except for Somatic Complaints, were significantly higher in children of divorce than in controls. Teacher-reported problem scores on the TRF total scale and Social and Attention Problems and prevalence of Attention Problems were significantly different for the 2 groups of children. Social competence was rated significantly lower in children of divorce than in controls. Discriminant function analysis showed that behavioral problems in children of divorce were characterized by aggressive behavior, withdrawal, and social problems.

CONCLUSIONS

The findings emanating from China provide the first evidence of the link between parental divorce and children's psychopathology and clarify the psychopathological dimensions in Chinese children of divorced parents.

[The development of degenerative disc animal model in rhesus monkey]

OBJECTIVE

To develop the degenerative disc animal model with histological and MRI observation.

METHODS

Eight adult Rhesus monkeys were divided randomly into two groups after the lumbar discs MRI scan. The operated group, 6 monkeys, was subjected to annulus resection. A 5 mm x 3 mm cut was made in the left anterolateral part of the fibrosus annulus on L(4,5), L(5,6) and L(6,7) discs. The operated discs were scanned with MRI at 1 week, 4 weeks, 8 weeks, 13 weeks and 20 weeks postoperatively and observed histologically at 4 weeks, 8 weeks and 20 weeks after operation.

RESULTS

The histological structure of Rhesus monkey was similar to that of human being. The percentage of high signal intensity area in the operated discs reduced significantly at 8, 13, 20 weeks after operation (P < 0.05). The fibroplasia outside the annular tear could be observed in all 6 operated discs at 4 weeks postoperatively. Two of 6 operated discs underwent fibroplasia at 20 weeks after operation. No heal evidence in the inner tear was showed after operation.

CONCLUSIONS

The animal model for human lumbar disc degeneration could be obtained by anterio-lateral annulus resection. The early-stage degenerative evidence could be observed without injury by measuring the percentage of the high intensity area of the operated discs on T2WI of MRI.

Left ventricular tachycardia originating near the left main coronary artery

Eight patients with idiopathic ventricular tachycardia (VT) underwent mapping and radiofrequency ablation. Mapping showed VT originating in the high posterolateral left ventricular outflow tract in proximity to the left main and proximal circumflex coronary arteries. Ablation was not attempted due to this proximity to the left main and proximal circumflex coronary arteries. Ablation was not attempted due to this proximity in 2 patients and limited in 1 patient. It was successful in VT suppression in 5 of 6 patients.

Genetic polymorphism of 4 STR loci on chromosome 17 in Chinese Han

OBJECTIVE

To analyze genetic polymorphism of D17S1290, D17S1293, D17S1303 and D17S1308 in Chinese Hans.

METHODS

Fifty unrelated individuals were analyzed by PCR amplification fragment length polymorphism analysis method.

RESULTS

9, 7, 5, 5 alleles were observed at these 4 STR loci respectively, the genotypes distributions in Chinese Hans were in accordance with Hardy-Weinberg equilibrium, the expected heterozygosities for these loci were 0.770, 0.828, 0.608, 0.669 respectively, the polymorphism information contents(PIC) were 0.763, 0.820, 0.602, 0.662 respectively.

CONCLUSION

The results demonstrate these 4 STR loci can be used for genetic analysis.

Structural phase transition of aluminum induced by electronic excitation

The dynamics of a structural phase transition induced by interband electronic excitation in aluminum is studied by determining the time evolution of the dielectric constant at 1.55 eV through the measurement of the transient reflectivity induced by an ultrafast pump pulse. The threshold fluence and the time scale for this transition are significantly less than the values necessary for ultrafast heat-induced melting, indicating that this phase change is caused by band structure collapse and lattice instability resulting from strong electronic excitation.

Loss of heterozygosity at 1p36 independently predicts for disease progression but not decreased overall survival probability in neuroblastoma patients: a Children's Cancer Group study

PURPOSE

To determine the independent prognostic significance of 1p36 loss of heterozygosity (LOH) in a representative group of neuroblastoma patients.

PATIENTS AND METHODS

Diagnostic tumor specimens from 238 patients registered onto the most recent Children's Cancer Group phase III clinical trials were assayed for LOH with 13 microsatellite polymorphic markers spanning chromosome band 1p36. Allelic status at 1p36 was correlated with other prognostic variables and disease outcome.

RESULTS

LOH at 1p36 was detected in 83 (35%) of 238 neuroblastomas. There was a correlation of 1p36 LOH with age at diagnosis greater than 1 year (P = .026), metastatic disease (P<.001), elevated serum ferritin level (P<.001), unfavorable histopathology (P<.001), and MYCN oncogene amplification (P<.001). LOH at 1p36 was associated with decreased event-free survival (EFS) and overall survival (OS) probabilities (P<.0001). For the 180 cases with single-copy MYCN, 1p36 LOH status was highly correlated with decreased EFS (P = .0002) but not OS (P = .1212). Entering 1p36 LOH into a multivariate regression model suggested a trend toward an independent association with decreased EFS (P = .0558) but not with decreased OS (P = .3687). Furthermore, allelic status at 1p36 was the only prognostic variable that was significantly associated with decreased EFS in low-risk neuroblastoma patients (P = .0148).

CONCLUSION

LOH at 1p36 is independently associated with decreased EFS, but not OS, in neuroblastoma patients. Determination of 1p36 allelic status may be useful for predicting which neuroblastoma patients with otherwise favorable clinical and biologic features are more likely to have disease progression.

Two state behavior in a solvable model of beta-hairpin folding

Understanding the mechanism of protein secondary structure formation is an essential part of the protein-folding puzzle. Here we describe a simple model for the formation of a beta hairpin, motivated by the fact that folding of a beta hairpin captures much of the basic physics of protein folding. The modeled hairpin is composed of two interacting Gaussian chains with one pairwise (two-body) and two many-body interactions. We show that these many-body interactions, arising from side chain packing effects, are responsible for producing an "all-or-none" folding transition. We also estimate the (single exponential) folding/unfolding rate via calculating the thermodynamic weight of the "critical" droplet/bubble.

[Genetic polymorphism of 5 STR loci on chromosome 14 in Chinese Han]

OBJECTIVE

To understand the distribution of genes and genotypes of 5 STR loci on chromosome 14 in Chinese Han.

METHODS

PCR and polyacrylamide gel electrophoresis were used to analyze the polymorphism of 5 STR loci (D14S742, D14S306, D14S606, D14S617, D14S611) on chromosome 14 in Chinese Han.

RESULTS

5 alleles and 13 genotypes, 5 alleles and 13 genotypes, 6 alleles and 13 genotypes, 9 alleles and 21 genotypes, and 6 alleles and 13 genotypes were observed at D14S742, D14S306, D14S606, D14S617 and D14S611, respectively. The frequencies of the most common allele at these five loci were 0.31, 0.31, 0.47, 0.35 and 0.29 respectively.

CONCLUSION

These five loci are highly polymorphic in Chinese Han and their allele distribution is in good agreement with Hardy-Weinberg equilibrium.

A noninvasive transesophageal signal averaging technique for detection of sinus node electrogram

We have developed a noninvasive transesophageal signal averaging technique for direct recording of sinus node electrogram. In this study, sinus node electrograms were recorded from 106 of 138 patients (77%), comparable to that (46%) recorded by conventional transesophageal technique, 59 were male and 47 were female ranging in age from 10-74 years (mean 44.2+/-12.4 years). The signals from lead I, surface averaged lead and esophagus averaged lead were amplified (up to 100 microV/cm), filtered (0.1-50 Hz), AD converted to 16-bit accuracy at a sampling rate of 2 KHz and averaged by using the three channel low-noise amplifier. The signal averaged esophageal sinus node potentials are deflections of low-amplitude and low-frequency preceding the P wave. Two morphologies, the domed wave (64 of 106 patients, 60%) and the smooth upstroke slope (42 of 106 patients, 40%), can be seen. The directly recorded sinoatrial conduction time was 82.3 +/-18.6 msec (mean+/-2 SD), ranged from 23-112 msec, amplitude was 3.8-27.7 microV and dv/dt was 0.42-1.92 mV/sec. The sinoatrial conduction time recorded by the transesophageal catheter technique was comparable to that (80.4+/-18. 1 msec) recorded by the transvenous catheter method perfectly. We think that signal averaged sinus node electrogram could be recorded in sinus rhythm in most patients with normal sinus node function and proper filter settings, high amplification and anti-drift technique are important in recording signal averaged esophageal sinus node electrogram.

Mitogenic signaling in androgen sensitive and insensitive prostate cancer cell lines

PURPOSE

To investigate the role of a specific mitogen activated protein kinase, extracellular signal-regulated kinase (ERK), in regulating cell proliferation induced by three potentially important prostate cancer mitogens that signal via different classes of receptors.

MATERIALS AND METHODS

Androgen sensitive (LNCaP) and insensitive (PC-3) prostate cancer cell lines were used in these studies. Epidermal growth factor (EGF), lysophosphatidic acid (LPA), and dihydrotestosterone (DHT) were the mitogenic stimulants and AG1478, a receptor tyrosine kinase inhibitor, and PD98059, an inhibitor of MEK, were the chemical inhibitors used in this study. Cell proliferation was measured using the WST-1 assay and ERK expression and activation was determined by immunoblotting for phospho- and total ERK.

RESULTS

In androgen-sensitive LNCaP cells, epidermal growth factor (EGF) and dihydrotestosterone (DHT) both enhanced cell proliferation. EGF-stimulation dramatically increased ERK phosphorylation while DHT did not. In the androgen-insensitive cell line, PC-3, EGF- and LPA-induced ERK phosphorylation and cell proliferation. Inhibition of EGF- and LPA- induced ERK activation with the EGF receptor inhibitor, AG1478, or the MEK inhibitor, PD98059, attenuated their proliferative effects. Neither inhibitor had an effect on DHT stimulated cell proliferation.

CONCLUSIONS

These data demonstrate heterogeneity of mitogenic signaling in prostate cancer cells, and support the hypothesis that androgens and growth factors utilize divergent signaling pathways in prostate cancer to induce proliferation.

Conservation and novelty in the evolution of cell adhesion and extracellular matrix genes

New proteins and modules have been invented throughout evolution. Gene "birth dates" in Caenorhabditis elegans range from the origins of cellular life through adaptation to a soil habitat. Possibly half are "metazoan" genes, having arisen sometime between the yeast-metazoan and nematode-chordate separations. These include basement membrane and cell adhesion molecules implicated in tissue organization. By contrast, epithelial surfaces facing the environment have specialized components invented within the nematode lineage. Moreover, interstitial matrices were likely elaborated within the vertebrate lineage. A strategy for concerted evolution of new gene families, as well as conservation of adaptive genes, may underlie the differences between heterochromatin and euchromatin.

Behavioral and emotional problems in Chinese children: teacher reports for ages 6 to 11

This study examined the applicability of the Chinese Version of Teacher's Report Form (TRF-CV) and estimated the prevalence of behavioral problems in a general population sample of 2,936 children aged 6 through 11 years in the Shandong Province of China. Teachers completed the TRF-CV and the Conners Hyperkinesis Index (CHI). The TRF-CV total scale showed satisfactory 2-week test-retest reliability (r = .83) and internal consistency (Cronbach's alpha = .94). The TRF-CV Total Problems, Attention Problems, Delinquent Behavior, and Aggressive Behavior had acceptable concurrent validity with the CHI (mean r = .62). With the TRF-CV Total Problems score of 26 as a cutoff, an overall correct classification rate of 90% for clinical sample and nonreferral required children was obtained. Exploratory factor analysis yielded six syndromes: Aggressive/Delinquent Behavior, Withdrawn/Depressed, Somatic Complaints, Attention Problems, Social Problems, and Thought Problems, with significant correlations with corresponding American cross-informant syndromes (mean r = .84). The overall prevalence rate of behavioral problems was 15.5% (95% CI = 14.2-16.8%), with a boy-to-girl ratio of 2.0:1 (chi2 = 59.70, p < .001). Younger boys exhibited more externalizing problems. These findings indicate that the TRF-CV is applicable for Chinese children, and the prevalence of behavioral problems shown by it among Chinese children seems comparable to that found in other countries. Although most of the American syndromes were well replicated, the differences in the present subjects, when submitted to principal components analysis, from American samples from whom the original syndromes were derived, could have prevented the study from replicating distinctions between aggressive vs. delinquent and depressed vs. withdrawn syndromes.

Outer-ring stereochemical modulation of cytotoxicity in cephalostatins

[structure: see text] 20- and 25'-epimers of cephalostatin 7, prepared by directed unsymmetrical pyrazine synthesis, address outer-ring topographical and stability questions and intimate an oxacarbenium ion rationale for the role in bioactivity of the spiroketal (E/F, E'/F') rings of this class of antitumor agents.

[Study on luminescence of the serial new ternary or tetradic complexes complexes of Eu (III) with beta-diketone]

The UV absorption, fluorescence, unstable spectra and quantum yields of five ternary or tetradic complexes of Eu (III) with beta-diketone (dibenzoyl methane, thenoyltrifluoroacetone), acrylic acid and other ligands were reported. The influences of the first and second ligands on absorption and luminescence spectra were found. The lifetimes and the processes of energy transfer of Eu3+ from 5D1 to 5D0 in complex solutions were measured. It was found that the lifetimes of Eu3+ complexes with TTA are approximate to each other and larger than those of complexes with DBM.

A thermodynamic model for receptor clustering

Intracellular signaling often arises from ligand-induced oligomerization of cell surface receptors. This oligomerization or clustering process is fundamentally a cooperative behavior between near-neighbor receptor molecules; the properties of this cooperative process clearly affect the signal transduction. Recent investigations have revealed the molecular basis of receptor-receptor interactions, but a simple theoretical framework for using these data to predict cluster formation has been lacking. Here, we propose a simple, coarse-grained, phenomenological model for ligand-modulated receptor interactions and discuss its equilibrium properties via mean-field theory. The existence of a first-order transition for this model has immediate implications for the robustness of the cellular signaling response.

Activation of extracellular signal-regulated kinase in human prostate cancer

PURPOSE

To investigate the level of expression, activation state, and functional significance of extracellular signal regulated kinase (ERK) in prostate cancer.

MATERIALS AND METHODS

Human prostate tissue samples (n = 22) were obtained from patients undergoing radical prostatectomy for localized adenocarcinoma of the prostate (n = 16, age range 44 to 72 years) or normal prostate specimens (n = 6, age ranges 19 to 47 years) obtained from rapid autopsy. Immunoblots, in vitro kinase assays, and immunohistochemistry were used to determine the expression and activation state of ERK in human prostate cancer.

RESULTS

Immunoblot and in vitro kinase assays demonstrated a 15-fold increase in ERK activation in prostate cancer specimens compared with normal human prostate tissue; however, ERK expression levels were only 1.3-fold higher in cancer. Immunohistochemical analysis demonstrated similar expression of ERK in cancer and normal tissues; however, phosphorylated ERK demonstrated greater intensity in the cancer specimens. Experiments conducted on a prostate cancer cell line demonstrated that EGF induced activation of ERK and cellular proliferation was partially inhibited by PD98059, a chemical inhibitor of the immediate upstream signaling component responsible of activation of ERK.

CONCLUSIONS

Collectively, these data demonstrate a dramatic increase in ERK activation in prostate cancer compared with normal prostate tissue and suggest that inhibitors designed to target this signal transduction cascade might have therapeutic benefit in the treatment of prostate cancer.

[Mapping the gene responsible for Smith-Fineman-Myers syndrome to Xq25]

OBJECTIVE

To map and eventually identify the gene responsible for Smith-Fineman-Myers syndrome.

METHODS

The short tandem repeat markers(STRs) distributed on X chromosome at 8-10cM interval were used in the initial mapping to look for the candidate region for Smith-Fineman-Myers syndrome locus and the linked marker. The additional STRs flanking the linked marker were tested to confirm the candidate region and decide the interval of disease gene.

RESULTS

Thirteen DNA samples from a Chinese family with Smith-Fineman-Myers syndrome were genotyped using 20 polymorphic STRs which cover the whole X chromosome. Of 20 STRs, DXS1001 on Xq25 suggested linkage and yielded a lod score of 3.01 at straight theta = 0 additional STRs flanking DXS1001 were tested. Fourteen polymorphic STRs out of 27 confirmed that Smith-Fineman-Myers syndrome locus is linked to several markers on Xq25. Haplotype analysis placed the disease locus within a 14.6cM interval bounded by DXS8064 and DXS8050.

CONCLUSION

The gene responsible for Smith-Fineman-Myers syndrome is mapped to a 14.6cM interval between DXS8064 and DXS8050 on Xq25. This result will be helpful for the identification of disease gene.