On the effect of irregular uterine activity during a vaginal delivery using an electro-chemo-mechanical constitutive model.

During a normal vaginal delivery, the muscle cells propagate electrical signals throughout the uterine wall, resulting in uterine contractions. However, uncoordinated uterine activity may disturb the uterine contractions pattern and negatively impact fetal and maternal health. Some of the abnormalities identified by the specialists are excessively short resting intervals and tachysystole. This work aims to investigate the influence of abnormal uterine activity in terms of maximum principal stress distribution and collagen fibers stretch in the uterine tissue during vaginal delivery with (i) excessively short resting intervals without changing the contraction time, and (ii) tachysystole (contraction and reduced resting times). These patterns are compared with a normal uterine contraction pattern. To achieve our aims, a biomechanical model was developed, including finite element models of the uterus and the fetus, and an electro-chemo-mechanical constitutive model. Generally, the excessively short resting intervals exhibit higher average maximum principal stresses during the contraction and resting stages, lower average fibers stretch values in the longitudinal direction and higher stretch in the circumferential direction. On the other hand, the tachysystole exhibit generally lower stress values during the uterine contraction and higher stress values during the resting stages, higher stretch in the longitudinal direction, and lower stretch in the circumferential direction.

Mechanical Effects of a Maylard Scar During a Vaginal Birth After a Previous Caesarean.

Caesarean section is one of the most common surgeries worldwide, even though there is no evidence supporting maternal and perinatal long-term benefits. Furthermore, the mechanical behavior of a caesarean scar during a vaginal birth after caesarean (VBAC) is not well understood since there are several questions regarding the uterine wound healing process. The aim of this study is to investigate the biomechanical Maylard fiber reorientation and stiffness influence during a VBAC through computational methods. A biomechanical model comprising a fetus and a uterus was developed, and a chemical-mechanical constitutive model that triggers uterine contractions was used, where some of the parameters were adjusted to account for the matrix and fiber stiffness increase in the caesarean scar. Several mechanical simulations were performed to analyze different scar fibers arrangements, considering different values for the respective matrix and fibers stiffness. The results revealed that a random fiber arrangement in the Maylard scar has a much higher impact on its mechanical behavior during a VBAC than the common fibers arrangement present in the uninjured uterine tissue. An increase of the matrix scar stiffness exhibits a lower impact, while an increase of the fiber's stiffness has no significant influence.

Attomolar protein detection in complex sample matrices with semi-homogeneous fluidic force discrimination assays.

We describe a semi-homogenous (SH) implementation of a fluidic force discrimination (FFD) assay using only two reagent mixtures and three assay steps that can be performed in as little as 10min. Previously microbead labels and FFD have been combined to achieve multiplexed, femtomolar nucleic acid hybridization and immunoassays in a microarray format [Mulvaney, S.P., Cole, C.L., Kniller, M.D., Malito, M., Tamanaha, C.R., Rife, J.C., Stanton, M.W., Whitman, L.J., 2007. Biosen. Bioelectron. 23, 191-200.]. In SH FFD assays, the microbeads and any required intermediate receptors (e.g., secondary antibodies) are first mixed directly with a sample, allowing target analytes to be efficiently captured onto the beads. The target-loaded beads are then specifically captured onto a microarray surface, with nonspecifically bound beads removed by controlled, laminar fluidic forces. The remaining beads on each microarray capture spot are counted to determine the targets' identities and concentrations. SH target collection provides a 1000-fold improvement in the assay sensitivity, down to attomolar concentrations, as demonstrated by our detection of staphylococcal enterotoxin B (SEB) at 35 aM (1 fg/ml). We also show that SH assays are adaptable for extraction, preconcentration, and identification of analytes in complex sample matrices, including assays for SEB and ricin toxoid in serum and whole blood. Finally, we present a detailed model of the reaction kinetics that reveals how capturing the targets onto the beads in solution provides a significant kinetic advantage at low target concentrations where mass transport to a microarray surface is most limited.

Mechanical and biochemical properties of human cervical tissue.

The mechanical integrity of cervical tissue is crucial for maintaining a healthy gestation. Altered tissue biochemistry can cause drastic changes in the mechanical properties of the cervix and contribute to premature cervical dilation and delivery. We present an investigation of the mechanical and biochemical properties of cervical samples from human hysterectomy specimens. Three clinical cases were investigated: nonpregnant hysterectomy patients with previous vaginal deliveries; nonpregnant hysterectomy patients with no previous vaginal deliveries; and pregnant hysterectomy patients at time of cesarean section. Tissue samples were tested in confined compression, unconfined compression and tension. Cervical tissue samples for the three clinical cases were also subjected to biochemical analysis. Biochemical assays measured cervical tissue hydration, collagen content, collagen extractability and sulfated glycosaminoglycan (GAG) content. Results from the mechanical tests indicate that cervical stroma has a nonlinear, time-dependent stress response with varying degrees of conditioning and hysteresis depending on its obstetric background. It was found that the nonpregnant tissue was significantly stiffer than the pregnant tissue in both tension and compression. Further, collagen extractability, sulfated GAG content and hydration were substantially higher in the pregnant tissue. This study is the first important step towards the attainment of an improved understanding of the complex interplay between the molecular structure of cervical tissue and its macroscopic mechanical properties.

Mechanisms of fear extinction.

Excessive fear and anxiety are hallmarks of a variety of disabling anxiety disorders that affect millions of people throughout the world. Hence, a greater understanding of the brain mechanisms involved in the inhibition of fear and anxiety is attracting increasing interest in the research community. In the laboratory, fear inhibition most often is studied through a procedure in which a previously fear conditioned organism is exposed to a fear-eliciting cue in the absence of any aversive event. This procedure results in a decline in conditioned fear responses that is attributed to a process called fear extinction. Extensive empirical work by behavioral psychologists has revealed basic behavioral characteristics of extinction, and theoretical accounts have emphasized extinction as a form of inhibitory learning as opposed to an erasure of acquired fear. Guided by this work, neuroscientists have begun to dissect the neural mechanisms involved, including the regions in which extinction-related plasticity occurs and the cellular and molecular processes that are engaged. The present paper will cover behavioral, theoretical and neurobiological work, and will conclude with a discussion of clinical implications.

Molecular identification of Yersinia enterocolitica isolated from pasteurized whole milk using DNA microarray chip hybridization.

A DNA microarray chip of four virulence genes and 16S ribosomal DNA gene conserved region among all Gram negative species, including Yersinia, as a positive control was developed and evaluated using 22 Yersinia enterocolitica isolates. Eight different oligonucleotide probes (oligoprobes) with an average size of 22 bp, complementary to the unique sequences of each gene, were designed and immobilized on the surface of chemically modified slides. Multiplex PCR was used to simultaneously amplify DNA target regions of all five genes, and single stranded DNA (ssDNA) samples for microarray analysis were prepared by using a primer extension of amplicons in the presence of one primer of all genes. The presence of genes in Y. enterocolitica was established by hybridization of the fluorescently labeled ssDNA representing different samples of the microarray gene-specific oligoprobes and confirmed by PCR. Results of the study showed specificity of genotyping Y. enterocolitica using multiple microarray-based assays. Final validation of the chip's ability to identify Y. enterocolitica genes from adulterated pasteurized whole milk was confirmed and successful. The limit of chip detection of virulence genes in pasteurized whole milk was found to be 1000 CFU per hybridization.

Genotyping of Clostridium perfringens toxins using multiple oligonucleotide microarray hybridization.

A microarray-based method for characterization of six Clostridium perfringens toxin genes: iA (iota toxin), cpa (alpha toxin), cpe (enterotoxin E), etxD (epsilon toxin), cpb1 (beta toxin 1),and cpb2 (beta toxin 2) was developed and evaluated using 17 C. perfringens isolates. Three individual oligonucleotide probes (oligoprobes), complementary to the unique sequences of each toxin gene, were designed and immobilized on a surface of aldehyde-coated glass slides. Multiplex PCR was used to simultaneously amplify DNA target regions of all six genes. Single-stranded DNA (ssDNA) samples for microarray analysis were prepared by following a primer extension of amplicons in the presence of one primer. Fluorescent moieties (Cy3) were incorporated into the ssDNA by chemical modification of guanine bases. The presence of toxin genes in C. perfringens was established by hybridization of the fluorescently labeled ssDNA representing different samples to the microarray gene-specific oligoprobes. Results of the study showed sensitivity and specificity of genotyping C. perfringens using multiple microarray-based assays.

Unscheduled DNA replication precedes apoptosis of photoreceptors expressing SV40 T antigen.

Expression of simian virus 40 T antigen (Tag) in the rod photoreceptors of transgenic mice leads to cell death that is completed by the end of the third week of postnatal development. To understand the mechanistic link between Tag expression and the death of the expressing photoreceptors, cell cycle activity was followed in a transgenic mouse family that expresses Tag directed by the mouse opsin promoter. Tag-expressing photoreceptors also expressed rhodopsin suggesting that these cells were differentiated. The presence of Tag in the photoreceptors induced the expression of both proliferating cell nuclear antigen (PCNA) and thymidine kinase (TK). The abnormally high levels of PCNA and TK continued until the complete disappearance of the cells expressing Tag. Photoreceptor cell death was also associated with continued DNA synthesis that ceased shortly after postnatal day 16. The specific loss of the rod photoreceptors that re-entered the cell cycle accounted entirely for the loss of photoreceptors from the outer nuclear layer. The antiproliferative nature of the mature retina is directly involved in the apoptotic death of photoreceptors expressing Tag.

Bcl-2 protects neural cells from cyanide/aglycemia-induced lipid oxidation, mitochondrial injury, and loss of viability.

The protooncogene bcl-2 rescues cells from a wide variety of insults. Recent evidence suggests that the mechanism of action of Bcl-2 involves antioxidant activity. The involvement of free radicals in ischemia/reperfusion injury to neural cells has led us to investigate the effect of Bcl-2 in a model of delayed neural cell death. We have examined the survival of control and bcl-2 transfectants of a hypothalamic tumor cell line, GT1-7, exposed to potassium cyanide in the absence of glucose (chemical hypoxia/aglycemia). After 30 min of treatment, no loss of viability was evident in control or bcl-2 transfectants; however, Bcl-2-expressing cells were protected from delayed cell death measured following 24-72 h of reoxygenation. Under these conditions, the rate and extent of ATP depletion in response to treatment with cyanide in the absence of glucose and the rate of recovery of ATP during reenergization were similar in control and Bcl-2-expressing cells. Bcl-2-expressing cells were protected from oxidative damage resulting from this treatment, as indicated by significantly lower levels of oxidized lipids. Mitochondrial respiration in control but not Bcl-2-expressing cells was compromised immediately following hypoxic treatment. These results indicate that Bcl-2 can protect neural cells from delayed death resulting from chemical hypoxia and reenergization, and may do so by an antioxidant mechanism. The results thereby provide evidence that Bcl-2 or a Bcl-2 mimetic has potential therapeutic application in the treatment of neuropathologies involving oxidative stress, including focal and global cerebral ischemia.

Increased retinal synthesis of heparan sulfate proteoglycan and HNK-1 glycoproteins following photoreceptor degeneration.

In an earlier analysis of the retinal biosynthesis of proteoglycan, we noted that, following photoreceptor degeneration in the rd (retinal degeneration) mouse, the remaining inner retina exhibited a marked elevation in synthesis of heparan sulfate proteoglycan (HSPG), well above the level observed in the normal (nondegenerate) retina, as well as a pronounced increase in sulfation of protein substrates. Biochemical and autoradiographic results of 35S-amino acid utilization reported here confirm that the 35SO4(2-) differences seen previously are accompanied by increased protein synthesis in the rd retina. An intact photoreceptor cell layer is neither a barrier to nor a sink for the amino acid precursor. Further, we have examined sulfate utilization in four other rodent strains with photoreceptor degenerations. In each of the models examined, an increase in retinal synthesis of 35SO4(2-)-labeled HSPG and glycoproteins occurs following photoreceptor degeneration. We have metabolically labeled with Na2(35)SO4 isolated retinal cultures from the following: (a) mice with light-induced photoreceptor degeneration; (b) rd mice; (c) transgenic mice with photoreceptor degeneration; (d) RCS rats; and (e) rats with light-induced photoreceptor degeneration. Comparisons were made with concurrent cultures of control nondegenerate retinal tissues. Protein and proteoglycan-enriched fractions were prepared from the incubation media and guanidine HCl/detergent extracts of the retinas by ion-exchange chromatography. The 35SO4(2-)-proteoglycans were identified by chondroitinase ABC and nitrous acid treatments. Retinas lacking photoreceptors produced at least five times the amount of 35SO4(2-)-HSPG found in control incubations. The RCS and light-damaged rats also showed increased synthesis of 35SO4(2-)-chondroitin sulfate proteoglycan relative to the control, through the increase was of lesser magnitude than the HSPG effect. 35SO4(2-)-protein in degenerate and light-damaged retinas always contained at least twice the radioactivity found in comparable control preparations. The bulk of the increased radiolabeling was found in N-linked oligosaccharides, including several recognized by the HNK-1 antibody. These data suggest that a sustained increase in HSPG and HNK-1 glycoprotein synthesis is a consistent response of inner retinal cells following loss of photoreceptors and is independent of the cause of photoreceptor degeneration.

Interphotoreceptor matrix in the human retina: cone-like domains surround a small population of rod photoreceptors.

The interphotoreceptor matrix (IPM) in mammalian retinas is subdivided into rod and cone specific compartments: peanut agglutinin (PNA) binding glycoconjugates are associated with cones, whereas wheat germ agglutinin (WGA) binding glycoconjugates are associated with rods. To establish the identity of a photoreceptor cell type in the human retina with rod dimensions but with a matrix domain which stains with PNA, double label studies, using PNA-ferritin to decorate the extracellular domains and immunocytochemical techniques using a rod specific anti-opsin antibody were conducted. The PNA-binding domains were observed in the cone-associated IPM as well as in the IPM surrounding a small population of rod-shaped photoreceptors. The outer segments of these rod-shaped photoreceptors showed intense labeling with a rod specific anti-opsin antibody as did all other rods which were free of PNA-labeling. A quantitative analysis of all retinal quadrants indicates that this novel rod represents approximately 0.3% of the total rod population in the human retina.

Effect of vasopressin administration and deficiency upon 3H-AVP binding sites in the CNS and periphery during development.

Arginine8-vasopressin (AVP, 40 micrograms/100 g b.wt., SC) was administered to male Long-Evans (LE) pups from day 1 to 7 of life and the pups were sacrificed on day 8 or 60. 3H-AVP binding was performed on membranes prepared from the liver, kidney, and septum. No significant changes were observed in the kidney or septum of animals 8 or 60 days old. However, the chronic AVP treatment did result in a significant increase in the density of 3H-AVP binding sites in the liver when compared to control day 8 pups (control 44 +/- 2 vs. AVP 56 +/- 3 fmol/mg protein), with no change in affinity. This effect was maintained into adulthood, as the day 60 AVP-treated LE rats also showed a significant increase in liver 3H-AVP binding sites compared to control (control 186 +/- 9 vs. AVP 239 +/- 14 fmol/mg protein), with no change in affinity. A comparison of 3H-AVP binding sites in 8-day-old LE, heterozygous Brattleboro (HET-BB), and homozygous Brattleboro rats (HOM-BB) was performed to assess the effect of complete (HOM-BB) and partial (HET-BB) VP deficiency on binding sites in the CNS and periphery. The liver again was the only tissue in which a change in 3H-AVP binding characteristics was noted. The HOM-BB rat (Bmax 144 +/- 6 fmol/mg protein) displayed a significant increase in AVP binding sites from the LE rat (Bmax 100 +/- 7 fmol/mg protein), while the 3H-AVP binding sites in the HET-BB rat liver (Bmax 69.8 +/- 9 fmol/mg protein) were significantly lower than LE rats. Thus hepatic AVP receptors appear most sensitive to the presence or absence of vasopressin during the early postnatal period.

Light-cured interim palatal augmentation prosthesis. A clinical report.

The interim palatal augmentation prosthesis produced a significant improvement in function within a short period of time. With the visible light-curing system, modifications of the prosthesis were made quickly and easily. The methods described enable the treatment team to immediately assess the results of prosthesis modifications.

Characterization of a 3H-arginine8-vasopressin binding site in the cingulate gyrus of the rat pup.

Autoradiographic analysis of 1, 8, 16 and 26-day-old rat brains showed 3H-arginine8-vasopressin (3H-AVP) binding to the cingulate gyrus-dorsal hippocampus (CG) only in the 8-day-old rat brain. Saturation analysis of CG membranes prepared from pups (7-10 days) and adults (90 days) revealed a small but significant increase in binding site concentration in adults compared to pups. However, the Kd of the 3H-AVP binding site increased significantly with age. The Kd of 3H-AVP binding to pup CG membranes was 0.9 +/- 0.1 nM, while the adult CG was 5.7 +/- 1.0 nM. The pharmacological specificity of 3H-AVP binding sites in the pup and adult CG was similar, but differed markedly from the profile observed in adult septal membranes. The primary specificity difference between the pup CG and septum was the reduced potency of certain V1 receptor antagonists. In competition experiments the CG binding site showed a reduced affinity for the V1 antagonist, [d(CH2)5, Tyr(Me)]AVP. This reduced affinity for the V1 antagonist was also documented autoradiographically using 3H-[d(CH2)5, Tyr(Me)]AVP. The data suggest that the 3H-AVP binding site expressed in the pup CG is not identical to the V1 type receptor present in the periphery and brain of the adult rat.

The fears expressed by elderly men and women: a lifespan approach.

This article reports one of the first studies of adult fears, specifically in an elderly population. Results indicated that older women expressed greater fearfulness than older men, a sex differential also observed in children and adolescents. When compared to other adult groups, significant differences were noted on several categories of fears. The elderly group ranked aging and sickness as their foremost fears, although the absolute degree of fearfulness did not differ from the comparison groups. Considered with previous investigations, these results suggest that some fears may change or intensify over the lifespan, and that within each period females report greater fearfulness than males. Additionally, this article describes a new entity, "fisity," which accounts for the popularity and the intensity of fears in a single measure.

Adult fears of four ethnic groups: whites, Chinese, Japanese and "boat people".

The paper reports the first study of adult fears according to ethnicity. The Chinese endorsed greater fearfulness than the whites. This difference was more marked for the women than the men. However, the Chinese and Japanese, two well-acculturated Asian minorities, expressed no differences in their fears; and Chinese living in two different sites demonstrated only small changes in their pattern of fears. By contrast, Vietnamese "boat people" expressed greatly increased total fearfulness as well as increased fear in all individual fear categories studied. However, unlike the Chinese and whites, sex had no effect on the "boat people's" fears. These results suggest that ethnicity influences overall fearfulness and the patterns of fears held by adults. Furthermore, sex and socioenvironmental factors may interact with ethnicity to modify the pattern of these fears.

Demographic features of adult fears.

This paper reports one of the first investigations of adult fears. Demographic variables included: sex, race, college degree status, and sibling position for a broadly defined middle class population. Additionally, it reports a new entity, "fisity" which accounts for both the popularity and strength of a fear in a single calculated measure. Women, in general, endorsed greater overall fearfulness than men, but this differential was not observed in an all white subsample. This male-female difference is similar to trends noted in studies of children's fears. However, college degree status did not correlate with fearfulness for the total population, or for an all white male subsample; although non-degreed females did express significantly greater fearfulness than their degreed cohort. Finally, increasing birth order in the sibship also correlated with increasing fearfulness.

Fears of physicians and other professionals groups.

Physicians, attorneys, and professors express a significantly different degree of fearfulness, although they prioritize their fears similarly. Physicians appear particularly to fear sickness and ageing, issues directly relevant to their chosen profession. The other two groups, however, do not demonstrate any specific outstanding fears. Results are discussed for a mixed sex, and an all male sample.