Transmembrane Mucin Response in Conjunctival Epithelial Cells Exposed to Wall Shear Stresses

Human conjunctival epithelium cells (HCEC) line the inner surface of the eyelid and cover the sclera and are continuously subjected to wall shear stresses (WSS). The effects of external forces on the conjunctival epithelium are not fully known. The conjunctival epithelium contains stratified squamous cells that synthesize the membrane-spanning mucins MUC1 and MUC16, which play important roles in protecting the ocular surface. Alterations in both gel-forming and membrane-tethered mucins occur in drying ocular surface diseases. The aim of this study was to explore the mechanobiological characteristics of transmembrane mucin secretion and cellular alterations of primary HCEC exposed to airflow-induced WSS perturbations. We exposed the HCEC to a steady WSS of 0.5 dyne/cm2 for durations of 15 and 30 min. Cytoskeletal alterations and MUC1 secretions were studied using immunohistochemically fluorescent staining with specific antibodies. We investigated for the first time an in vitro model of membrane-tethered mucin secretion by HCEC in response to WSS. The exposure of HCEC to WSS increased the polymerization of F-actin, altered the cytoskeletal shape and reduced the secretion of membrane-tethered MUC1.

Controlled amnioreduction for twin-to-twin transfusion syndrome

Background:

Twin-to-twin transfusion syndrome (TTTS) is a severe condition causing preterm delivery, fetal death, and neurodevelopmental disorders. This study presents a data-based controlled amnioreduction (AR) protocol composed of sequential amniodrainage in treatment of TTTS.

Methods:

A total of 18 procedures were performed in 11 TTTS pregnancies at 17 to 34 weeks of gestation. The amniotic pressure was measured along with sequential removal of the amniotic fluid, 500 mL each step. The umbilical artery systolic/diastolic (S/D) ratio for each twin was measured pre- and post-AR. Long-term neurodevelopmental outcomes of all TTTS survivors were evaluated from parental answers to a phone survey.

Results:

The amniotic pressure decreased exponentially with the increased volume of removed amniotic fluid until a plateau was obtained. Changes of the S/D ratio between pre- and post-AR procedure did not reveal a clear tendency. The survival rate was 86.4% although 91% of all twins were at Quintero stage III. Long-term neurodevelopment outcomes in the 19 surviving twins were 68.4% optimal, 26.3% suboptimal, and 5.3% abnormal.

Conclusion:

The controlled AR procedure resulted in a relatively high rate of twin survival with favorable long-term neurodevelopment outcomes.

Biomechanics of Early Life in the Female Reproductive Tract

Early human life that starts at the onset of fertilization and ends with implantation of the embryo in the uterine wall is the foundation for a successful pregnancy. The different stages during this period require biomechanical mechanisms, which are mostly unknown due to difficulties to conduct in vivo studies in humans.

Tissue-engineered arterial intima model exposed to steady wall shear stresses

The arterial intima is continuously under pulsatile wall shear stresses (WSS) imposed by the circulating blood. The knowledge of the contribution of smooth muscle cells (SMC) to the response of endothelial cell (EC) to WSS is still incomplete. We developed a co-culture model of EC on top of SMC that mimics the inner in vivo structure of the arterial intima of large arteries. The co-cultured model, as well as a monolayer model of EC, were developed in custom-designed wells that allowed for mechanobiology experiments. Both the monolayer and co-culture models were exposed to steady flow induced WSS of up to 24 dyne/cm² and for lengths of 60 min. Quantification of WSS induced alterations in the cytoskeletal actin filaments (F-actin) and vascular endothelial cadherin (VE-cadherin) junctions were utilized from confocal images and flow cytometry. High confluency of both models was observed even after exposure to the high WSS. The quantitive analysis revealed larger post WSS amounts of EC F-actin polymerization in the monolayer, which may be explained by the relative help of the SMC to resist the external load of WSS. The VE-cadherin demonstrated morphological alterations in the monolayer model, but without significant changes in their content. The SMC in the co-culture maintained their contractile phenotype post high WSS which is more physiological, but not post low WSS. Generally, the results of this work demonstrate the active role of SMC in the intima performance to resist flow induced WSS.

Analysis of in vivo uterine peristalsis in the non-pregnant female mouse

Uterine peristalsis due to spontaneous contractions of the myometrial smooth muscles has important roles in pre-implantation processes of intra-uterine sperm transport to the fertilization site, and then embryo transport to the implantation sites. We developed a new objective methodology to study in vivo uterine peristalsis in female mice during the pro-oestrus phase. The acquisition procedure of the uterine organ is remote without interfering with the organ function. The uniqueness of the new approach is that video images of physiological pattern were converted using image processing and new algorithms to biological time-dependent signals that can be processed with existing algorithms for signal processing. Using this methodology we found that uterine peristalsis in the pro-oestrus mouse is in the range of 0.008-0.029 Hz, which is about one contraction per minute and with fairly symmetric contractions that occasionally propagate caudally. This rate of contractions is similar to that of human uterine peristalsis acquired in vivo, which is important information for a popular animal model.

Objective Analysis of Vaginal Ultrasound Video Clips for Exploring Uterine Peristalsis Post Vaginal and Cesarean Section Deliveries

The nonpregnant uterus is characterized by cyclic contractions that assist in sperm transport to the fallopian tube, embryo transport to implantation site, and expulsion of menstrual debris. The effect of post-Cesarean section (CS) scar on uterine peristalsis is unclear, while worldwide the prevalence of CS deliveries is increasing. In this study, we developed a new objective method for analysis of dynamic characteristics of the nonpregnant uterus from transvaginal ultrasound (TVUS) recordings when the uterine cavity is not clearly observed, as may be the case in post-CS uteri. The method of active contours was utilized to detect the contours of the endometrium-myometrium interface (EMI) from sagittal cross-section TVUS images of nonpregnant uteri. The contours were straightened along the uterus centerline and registered with respect to the fundal end in order to reduce the noise due to movements of the physician and the participant. A dynamic analysis was conducted on these time-dependent contours in order to explore the frequency and amplitude of the EMI motility. The analysis was conducted on TVUS video clips from 12 nonpregnant participants, 7 post-CS and 5 controls. The frequencies of the EMI motility was 0.010 to 0.064 Hz at days 8 to 17 in the control participants and 0.014 to 0.073 Hz at days 9 to 15 in post-CS participants. The maximal amplitude of motility was 0.67 to 2.00 mm and 0.48 to 2.58 mm for the control and post-CS participants, respectively. In this preliminary study, we have not observed significant difference between the EMI motility of healthy and post-CS uteri.

Ex Vivo Human Placental Perfusion Model for Analysis of Fetal Circulation in the Chorionic Plate

OBJECTIVES

The purpose of this study was to develop an ex vivo placental perfusion model to assess changes in the umbilical artery systolic-to-diastolic (S/D) ratio due to progressive occlusion of the placental arterial system.

METHODS

Ex vivo human placentas were connected to a computerized pulse duplicator mimicking pulsatile flow from the fetal heart. Doppler sonographic measurements were conducted on the umbilical and chorionic arteries of 25 mature placentas. Simulation of placental occlusion was performed by progressive ligature of the chorionic arteries, including one umbilical artery. The correlation between the umbilical artery S/D ratio and the severity of simulated placental occlusion was analyzed.

RESULTS

The normal mean S/D ratio ± SD decreased gradually along the chorionic plate from 2.66 ± 0.47 at the cord insertion to 1.90 ± 0.59 in generation IV of the chorionic vessels. The Doppler index initially increased slowly with simulated placental occlusion. Only when all 4 generations were occluded was the umbilical artery S/D ratio elevated. Complete occlusion of one umbilical artery resulted in a 39% increase in the umbilical artery S/D ratio.

CONCLUSIONS

This unique model combining Doppler sonography with perfusion of an ex vivo placenta can be used for a better understudying of pathologic placental blood flow circulation.

Dimensionless analysis of valveless pumping in a thick-wall elastic tube: Application to the tubular embryonic heart

The physical mechanism that drives blood flow in the valveless tubular embryonic heart is still debatable whether it is peristaltic flow or valveless dynamic suction. Previous studies of valveless pumping were concerned with either the role of the excitation parameters or the mechanisms that generate the unidirectional outflow. In this study, a dimensionless one-dimensional (1D) analysis of the valveless pumping due to local excitation at an asymmetric longitudinal location was performed for non-uniform thick-wall elastic tubes, including tubes with local bulging and tapering. A general tube law that accounts for wall thicknesses was implemented for describing the physically realistic dynamics of the tube and the two-step MacCormack algorithm was utilized for the numerical analysis. A comprehensive analysis was conducted to explore the affecting roles of the system (e.g., tube geometry) and the working (e.g., Strouhal number and flow friction parameter) parameters on the net outflow of the pump. The maximal positive net outflow in all the tested cases always occurred when the natural Strouhal number was about π. Flow reversals were observed only for relatively low friction parameters. A local bulging at the site of excitation and thick walls contributed to larger outflows, while tube tapering reduced the net outflow.

In vitro simulation of placental transport: part I. Biological model of the placental barrier

INTRODUCTION

The placental barrier (PB) is the thin biological membrane made of endothelial cells (EC), trophoblast cells (TC) and basal membrane that separates between maternal and fetal blood circulations within the placenta and facilitates feto-maternal transport characteristics, which are not completely understood.

METHODS

An in vitro biological model of the PB model was co-cultured of human TC (HTR8) and human umbilical vein EC (HUVEC) on both sides of a denuded amniotic membrane (AM) using custom designed wells.

RESULTS

Confocal and transmission electron microscopy (TEM) imaging confirmed the morphology expressions of human EC and TC. Further support on the integrity of the new PB model was obtained from the existence of tight junctions and permeability experiments with fluorescence markers of small and large molecules. The monolayer of EC demonstrated the limiting layer for the transport resistance across this complex barrier.

DISCUSSION AND CONCLUSION

This new in vitro viable model mimics the architecture of the human PB and can be used in in vitro simulations of transplacental transport studies.

One stop screening for multiple cancers: the experience of an integrated cancer prevention center

BACKGROUND

Cancer is a leading cause of mortality worldwide. Screening is a key strategy for reducing cancer morbidity and mortality.

METHODS

We aimed to describe the experience of an integrated cancer prevention center in screening an asymptomatic population for the presence of neoplasia. One-thousand consecutive asymptomatic, apparently healthy adults, aged 20-80 years, were screened for early detection of 11 common cancers that account for 70-80% of cancer mortality.

RESULTS

Malignant and benign lesions were found in 2.4% and 7.1% of the screenees, respectively. The most common malignant lesions were in the gastrointestinal tract and breast followed by gynecological and skin. The compliance rate for the different screening procedures was considerably higher than the actual screening rate in the general Israeli population - 78% compared to 60% for mammography (p<0.001) and 39% compared to 16% for colonoscopy (p<0.001). Advanced age, family history of cancer and certain lifestyle parameters were associated with increased risk. Moreover, polymorphisms in the APC and CD24 genes indicated high cancer risk. When two of the polymorphisms existed in an individual, the risk for a neoplastic lesion was extremely high (OR 2.3 [95% CI 0.94-5.9]).

CONCLUSIONS

One stop shop screening for 11 common cancers in the setting of a multidisciplinary outpatient clinic is feasible and can detect cancer at an early stage.

The hemodynamic basis for positional- and inter-fetal dependent effects in dual arterial supply of mouse pregnancies

In mammalian pregnancy, maternal cardiovascular adaptations must match the requirements of the growing fetus(es), and respond to physiologic and pathologic conditions. Such adaptations are particularly demanding for mammals bearing large-litter pregnancies, with their inherent conflict between the interests of each individual fetus and the welfare of the entire progeny. The mouse is the most common animal model used to study development and genetics, as well as pregnancy-related diseases. Previous studies suggested that in mice, maternal blood flow to the placentas occurs via a single arterial uterine loop generated by arterial-arterial anastomosis of the uterine artery to the uterine branch of the ovarian artery, resulting in counter bi-directional blood flow. However, we provide here experimental evidence that each placenta is actually supplied by two distinct arterial inputs stemming from the uterine artery and from the uterine branch of the ovarian artery, with position-dependent contribution of flow from each source. Moreover, we report significant positional- and inter-fetal dependent alteration of placental perfusion, which were detected by in vivo MRI and fluorescence imaging. Maternal blood flow to the placentas was dependent on litter size and was attenuated for placentas located centrally along the uterine horn. Distinctive apposing, inter-fetal hemodynamic effects of either reduced or elevated maternal blood flow, were measured for placenta of normal fetuses that are positioned adjacent to either pathological, or to hypovascular Akt1-deficient placentas, respectively. The results reported here underscore the critical importance of confounding local and systemic in utero effects on phenotype presentation, in general and in the setting of genetically modified mice. The unique robustness and plasticity of the uterine vasculature architecture, as reported in this study, can explain the ability to accommodate varying litter sizes, sustain large-litter pregnancies and overcome pathologic challenges. Remarkably, the dual arterial supply is evolutionary conserved in mammals bearing a single offspring, including primates.

Modeling Embryo Transfer into a Closed Uterine Cavity

Embryo transfer (ET) is the last manual intervention after extracorporeal fertilization. After the ET procedure is completed, the embryos are conveyed in the uterus for another two to four days due to spontaneous uterine peristalsis until the window time for implantation. The role of intrauterine fluid flow patterns in transporting the embryos to their implantation site during and after ET was simulated by injection of a liquid bolus into a two-dimensional liquid-filled channel with a closed fundal end via a liquid-filled catheter inserted in the channel. Numerical experiments revealed that the intrauterine fluid field and the embryos transport pattern were strongly affected by the closed fundal end. The embryos re-circulated in small loops around the vicinity where they were deposited from the catheter. The transport pattern was controlled by the uterine peristalsis factors, such as amplitude and frequency of the uterine walls motility, as well as the synchronization between the onset of catheter discharge and uterine peristalsis. The outcome of ET was also dependent on operating parameters such as placement of the catheter tip within the uterine cavity and the delivery speed of the catheter load. In conclusion, this modeling study highlighted important parameters that should be considered during ET procedures in order to increase the potential for pregnancy success.

First report on screening an asymptomatic population for cancer: The yield of an integrated cancer prevention center

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Background: Cancer is a leading cause of mortality worldwide. Screening is a key strategy for reducing cancer morbidity and mortality. We aimed to evaluate the utility of cancer screening in an asymptomatic population at an integrated cancer prevention center. Methods: One-thousand consecutive asymptomatic, apparently healthy adults, aged 20-80 years, were screened for early detection of 11 common cancers by routine screening tests. Results: Malignant and benign lesions were found in 2.4% and 7.1% of the screenees, respectively. The most common malignant lesions were in the gastrointestinal tract and breast followed by gynecological and skin. The compliance rate for the different screening procedures was considerably higher than the general Israeli population – 78% compared to 60% for mammography (p<0.001) and 39% compared to 16% for colonoscopy (p<0.001). Advanced age, family history and certain lifestyle parameters were associated with increased risk for cancer. Moreover, polymorphisms in the APC and CD24 genes indicated high cancer risk. When two of the polymorphisms existed in an individual, the risk for a neoplastic lesion was extremely high (OR 2.3 [95% CI 0.94-5.9]). Conclusions: A significant number of neoplastic lesions were diagnosed at an early stage. Polymorphisms in the APC and CD24 genes may identify individuals at an increased risk for cancer. Cancer may be diagnosed at an early stage using the screening facilities of a multidisciplinary outpatient clinic.

A new method for analysis of non-pregnant uterine peristalsis using transvaginal ultrasound

OBJECTIVES

To develop an objective method for analysis of uterine peristalsis using transvaginal sonography (TVS).

METHODS

We performed computerized analysis of 2-5-min video recordings of TVS imaging of a midsagittal cross-section of the uterus during the proliferative and early secretory phases of 18 healthy volunteers aged 28-41 years. The contours of the fluid-endometrial interface (FEI) and the endometrium-myometrium interface (EMI) were detected in each frame, and the data from all frames were used to explore the dynamic motility characteristics of these interfaces at fixed distances from the fundus.

RESULTS

The mean ± SD dominant frequency of peristalsis of the EMI along the midsagittal cross-section was 0.049 ± 0.01 Hz and that of the cavity center was 0.043 ± 0.02 Hz. The maximal amplitudes of the EMI were about 1 ± 0.25 mm, located between 7 and 17 mm from the fundus. The amplitudes of the FEI were in the range 0.05-0.2 mm. The amplitude of the cavity centerline movement was 0.94 ± 0.34 mm, located at the extremes of the unperturbed curve.

CONCLUSIONS

This study provides a simple tool for analysis of uterine peristalsis characteristics using ultrasound data. This is possible at the EMI even when the FEI is invisible or incomplete, such as during the luteal phase, when an intrauterine contraceptive device is in place, and during diagnostic or medical intervention.

Cryptorchidism: incidence and sperm quality in infertile men

In a population of 8500 men attending the andrology outpatient clinic, 200 men (2.35%) were recorded as having some disturbances with the descent of the testes into the scrotum. Medical history of the patients revealed that 51 underwent unilateral orchidopexy; 40 bilateral orchidopexy; and 24 were treated with human chorionic gonadotropin in order to induce descent of their testes. In addition, 6 patients reported spontaneous descent of the testes, and 13 others were found to be unilaterally cryptorchid upon physical examination. Results of semen analysis, hormonal profile, testes position, and testicular volume were compared to those of 105 proven fertile men. The major finding of this study shows that post-partum undescended testes suffer from primary Sertoli cell malfunction as reflected by elevated serum follicle stimulating hormone levels. Serum luteinizing hormone and testosterone levels were within the normal range. Surgical descent of the testes did not improve sperm production, proved by low sperm quality of all the study groups, compared to the cryptorchid group. Among the patients who were operated on, no correlation was found between age at operation and semen variables. All groups showed poor sperm quality which can be defined as oligoteratoasthenozoospermia. The degree of spermatogenic damage was in the following order of diagnosis or treatment: bilateral orchidopexy greater than cryptorchid testes greater than hormonal treatment greater than unilateral orchidopexy greater than late spontaneous descent of the testes. Thus, it is advisable to postpone surgical treatment of cryptorchidism and apply this only after a waiting period, and if the hormonal approach has failed to descend the testis.

Anthropometry of fetal vasculature in the chorionic plate

Normal fetal development is dependent on adequate placental blood perfusion. The functional role of the placenta takes place mainly in the capillary system; however, ultrasound imaging of fetal blood flow is commonly performed on the umbilical artery, or on its first branches over the chorionic plate. The objective of this study was to evaluate the structural organization of the feto-placental vasculature of the chorionic plate. Casting of the placental vasculature was performed on 15 full-term placentas using a dental polymer mixed with colored ink. Observations of the cast models revealed that the branching architecture of the chorionic vessel is a combination of dichotomous and monopodial patterns, where the first two to three generations are always of a dichotomous nature. Analysis of the daughter-to-mother diameter ratios in the chorionic vessels provided a maximum in the range of 0.6-0.8 for the dichotomous branches, whereas in monopodial branches it was in the range of 0.1-0.3. Similar to previous studies, this study reveals that the vasculature architecture is mostly monopodial for the marginal cord insertion and mostly dichotomous for the central insertion. The more marginal the umbilical cord insertion is on the chorionic plate, the more monopodial branching patterns are created to compensate the dichotomous pattern deficiency to perfuse peripheral placental territories.

Neurodevelopmental outcome of children with intrauterine growth retardation: a longitudinal, 10-year prospective study

One hundred twenty-three children with intrauterine growth retardation were prospectively followed from birth to 9 to 10 years of age in order to characterize their specific neurodevelopmental and cognitive difficulties and to identify clinical predictors of such difficulties. Perinatal biometric data and risk factors were collected. Outcome was evaluated at age 9 to 10 by neurodevelopmental, cognitive, and school achievement assessments. Sixty-three children served as controls who were appropriate for gestational age. Significant differences in growth (P < .001), neurodevelopmental scores (P < .001), intelligence quotient (IQ) (P < .0001), and school achievements measured by the Kaufmann Assessment Battery for Children (P < .001) were found between the children with intrauterine growth retardation and controls. Children with intrauterine growth retardation demonstrated a specific profile of neurocognitive difficulties at school age, accounting for lower school achievements. The best perinatal parameter predictive of neurodevelopment and IQ was the Cephalization Index (P < .001). Somatic catch-up growth at age 2 and at age 9 to 10 correlated with favorable outcome at 9 to 10 years of age.

Mathematical model of excitation-contraction in a uterine smooth muscle cell

Uterine contractility is generated by contractions of myometrial smooth muscle cells (SMCs) that compose most of the myometrial layer of the uterine wall. Calcium ion (Ca2+) entry into the cell can be initiated by depolarization of the cell membrane. The increase in the free Ca2+concentration within the cell initiates a chain of reactions, which lead to formation of cross bridges between actin and myosin filaments, and thereby the cell contracts. During contraction the SMC shortens while it exerts forces on neighboring cells. A mathematical model of myometrial SMC contraction has been developed to study this process of excitation and contraction. The model can be used to describe the intracellular Ca2+concentration and stress produced by the cell in response to depolarization of the cell membrane. The model accounts for the operation of three Ca2+control mechanisms: voltage-operated Ca2+channels, Ca2+pumps, and Na+/Ca2+exchangers. The processes of myosin light chain (MLC) phosphorylation and stress production are accounted for using the cross-bridge model of Hai and Murphy ( Am J Physiol Cell Physiol 254: C99–C106, 1988) and are coupled to the Ca2+concentration through the rate constant of myosin phosphorylation. Measurements of Ca2+, MLC phosphorylation, and force in contracting cells were used to set the model parameters and test its ability to predict the cell response to stimulation. The model has been used to reproduce results of voltage-clamp experiments performed in myometrial cells of pregnant rats as well as the results of simultaneous measurements of MLC phosphorylation and force production in human nonpregnant myometrial cells.

Fetal Blood Flow in Branching Models of the Chorionic Arterial Vasculature

Fetal development depends on adequate exchange of materials between the fetus and maternal circulatory systems, which requires optimal distribution of blood vessels over the chorionic plate to ensure perfusion of the whole placental volume. Based on a previous investigation of the architecture of the chorionic vessels in the human placenta, we developed in this study typical models for the dichotomous and monopodial segments of the chorionic arteries of a mature placenta. Each model also included some intraplacental (IP) vessels that branch off into the cotyledons perpendicular to the chorionic arteries. Computational analysis of steady blood flow through these models was performed to explore the distribution of fetal blood over the chorionic plate. The results demonstrated that energy losses are small in the monopodial model, which explains their efficient delivery of fetal blood over the chorionic plate in cases of a marginal cord insertion. On the other hand, the dichotomous model is efficient in distributing a relatively large volume of blood over large areas near the bifurcation. Accordingly, the combination of dichotomous and monopodial bifurcation in a normal chorionic plate ensures a uniform blood perfusion of the placenta. Simulations with narrow daughter and IP vessels did not result in significant changes in the main mother tubes, supporting clinical observations in which umbilical blood flow remains normal although some peripheral vessels may be occluded.

Bioengineering Studies of the Embryo Transfer Procedure

Embryo transfer (ET) is the final manual intervention in extracorporeal fertilization in which an embryo is transferred into the uterus by a transcervical catheter. The low rates of embryo implantation within the uterus are attributed, among other factors, to the ET technique, which depends on a multitude of anatomical, physiological, and mechanical aspects. We developed computational and experimental models to simulate ET to examine the contribution of mechanical features to the success of this procedure. The experimental model allowed laboratory simulations of the dispersion of the catheter load as a result of different injection speeds into a tilted uterine model. The mathematical model analyzed potential trajectories of the transferred embryos resulting from the interaction between the injection velocity and the intrauterine flows caused by uterine peristalsis. The simulations revealed the important contribution of mechanical parameters, such as the position of the uterus and the presence of air in the catheter load. The latter was found to increase the potential for the embryo to be near the fundal area during the time limit for implantation. Based on the results of our simulations, we recommended performing ET in a patient-specific position in which the fundus will be the highest point above the horizon and that the load be delivered slowly, that is, not less than 10 s. We also recommended placing the tip of the catheter at the mid cavity to avoid ectopic pregnancy.

Modeling Myometrial Smooth Muscle Contraction

Existing models of uterine contractions assumed a top-down approach in which the function at the organ or tissue level was explained by the behavior of smaller basic units. A new model of the excitation-contraction process in a single myometrial myocyte was recently developed. This model may be used in a bottom-up approach for the description of the contribution of cellular phenomena to the overall performance of the tissue or organ. In this review, we briefly survey current knowledge of uterine electrophysiology and contractility as well as current modeling techniques, which were successfully used to study the function of various types of muscle cells. In the physiological part of the review, we relate to mechanisms of intracellular Ca(2+) control, Ca(2+) oscillations, and Ca(2+) waves and to the various membranal transport mechanisms regulating ion exchange between the intracellular and extracellular spaces. In addition, we describe the process leading from excitation to contraction. In the modeling part of the review, we present the Hodgkin-Huxley (HH) model of excitation in the squid axon as well as models of Ca(2+) control and the latch-bridge model of Hai and Murphy describing the kinetics of smooth muscle cell (SMC) contraction. We also present integrative models describing more than one of these phenomena. Finally, we suggest how these modeling techniques can be applied to modeling myometrial contraction and thus may significantly contribute to current efforts of research of uterine function.

Analysis of cervical dynamics by ultrasound imaging

Preterm birth is generally due to cervical ripening during the second trimester of pregnancy. The diagnosis of cervical incompetence is mostly based on the measurement of the shortened cervical length from transvaginal ultrasound (TVUS) images. We investigated the cervical dynamic response to spontaneous or imposed variations of intrauterine pressure, which may induce cervical shortening. The TVUS images of the cervix sagittal cross-sections were recorded from six women in mid pregnancy. The cervical dynamics was observed while the subject was either in a supine position, kneeling, or had undergone transfundal pressure in a supine position. Each subject was tested in all three positions, but the dynamic response was observed in only one of them. The time-dependent analysis was performed on consecutive TVUS images at time intervals of 1 s to extract the dynamic response of the funneling geometry and the closed cervical length. The internal os was considered as being a point on the uterine wall and characterized by a sharp gradient of the inner wall of the uterine cavity. Dynamic evaluation of TVUS images revealed that shortening of the cervical length was greater than 30% and that the funneling percentage was greater than 40%. This study demonstrates the clinical potential for dynamic assessment of cervical response due to excessive uterine pressure, in addition to its application for the conventional measurement of cervical length.

Hemodynamic analysis of Hyrtl anastomosis in human placenta

The Hyrtl anastomosis is a common connection between the umbilical arteries near the cord insertion in most human placentas. It has been speculated that it equalizes the blood pressure between the territories supplied by the umbilical arteries. However, its functional role in the regulation and distribution of fetal blood flow to the placenta has not yet been explored. A computational model has been developed for quantitative analysis of hemodynamic characteristic of the Hyrtl anastomosis in cases of discordant blood flow in the umbilical arteries. Simulations were performed for cases of either increased placental resistance at the downstream end or reduced arterial blood flow due to some pathologies upstream of one of the arteries. The results indicate that when placental territories of one artery impose increased resistance to fetal blood flow, the Hyrtl anastomosis redistributes the blood flow into the second artery to reduce the large pressure gradients that are developed in the affected artery. When one of the arteries conducts a smaller blood flow into the placenta and a relatively smaller pressure gradient is developed, the Hyrtl anastomosis rebuilds the pressure gradients in the affected artery and redistributes blood flow from the unaffected artery to the affected one to improve placental perfusion. In conclusion, the Hyrtl anastomosis plays the role of either a safety valve or a pressure stabilizer between the umbilical arteries at the placental insertion.

In vitro simulations of embryo transfer in a laboratory model of the uterus

Embryo transfer (ET) is the final manual intervention during which the newly formed embryo is placed within the uterus by a transcervical catheter. The loading of the syringe-catheter complex with the transferred volume consists of the transfer media (which contains the embryos) separated by air spaces on both sides. The dynamics involved in injecting the syringe-catheter complex is not well understood nor has it been investigated to date. We developed an in vitro experimental setup for simulations of ET into a rigid transparent uterine model. The catheter was loaded in sequences of liquid and air as it is in the clinical setting. The transferred liquid was colored with a dye and its dispersion within the uterine cavity was recorded by a video camera. The results demonstrated, for the first time, the importance of having a gas phase in the catheter load. The resulting air bubbles within the uterus were carried upward towards the fundus by buoyant forces, thereby dragging behind them the transferred liquid which contained the embryos. This could be expected to substantially increase the probability for the embryos to be present near the fundal wall at the time window for implantation. There was also evidence of a dependency of the rate of injection upon the catheter load into the uterus: a low speed generated several air bubbles which led to more of the transferred liquid being carried towards the fundal end, thus possibly enhancing the potential for implantation.

Feto-feto-fetal transfusion syndrome in monozygotic monochorionic triamniotic triplets: vascular evaluation by a cast model

A unique cast model of the placenta in a rare case of feto-feto-fetal triplet transfusion syndrome (FFFTTS) allowed the demonstration of why the transfusion syndrome developed in one fetus and not in the other two in that single placenta. The vasculature anatomy of a monochorionic triamniotic triplet placenta with FFFTTS of three healthy infants (one donor, two recipients) born in the 35th week of gestation was cast by means of dental casting materials. After the cast hardened, the tissue was corroded, revealing the cast blood vessels. The diameters and lengths of the chorionic blood and intraplacental vessels of the cast placenta were measured with a digital caliper. The cast revealed two artery-artery (A-A) anastomoses on the chorionic plate between the two recipients and the donor. Seven artery-vein (A-V) deep anastomoses connected only the arteries of the donor and the veins of the two recipients. The blood vessel connections among the fetuses allowed the evaluation of a pathologic case with its own control in a single placenta. From the vascular appearance, we speculate that the A-A anastomoses between the two fetuses protected them from developing blood transfusions, but that the A-V anastomoses contributed to their development.

Nomograms for the Sonographic Measurement of the Fetal Philtrum and Chin

OBJECTIVE

To generate nomograms for the sonographic measurement of the fetal philtrum and chin during pregnancy.

DESIGN

A prospective, cross-sectional study in normal singleton pregnancies.

SUBJECTS

One hundred and fifty-three fetuses between 13 and 42 weeks of gestation were studied.

METHODS

The philtrum was measured from the base of the columella to the upper lip. The chin was measured from the tip of the lower lip to the skin under the lower tip of the mandible. Predictive models were evaluated to generate graphic description of the 5th, 50th and 95th centiles for the fetal philtrum and chin.

RESULTS

Fetal philtrum length increased with gestational age. The regression equation for the philtrum length (y) according to gestational age in weeks (x) is best predicted by the S-curve (Gompertz) model, as described by the following equation: y = exp(a + b/x), where a = 2.778577, and b = -23.476723 (R(2) = 85.3%, p < 0.0001). The fetal chin length increased with gestational age. The regression equation for the mean chin length (y) according to gestational age in weeks (x) is best predicted by the S-curve model as described in the following equation. y = exp(a + b/x), where a = 3.7922, b = -28.043, (R(2) = 89.0%, p < 0.0001).

CONCLUSIONS

The nomograms generated in this study for the fetal philtrum and chin during pregnancy can be used in confirming subjective impression of facial dysmorphism.

A new power Doppler ultrasound guiding technique for improved testicular sperm extraction

OBJECTIVE

To develop a noninvasive procedure that employs image processing of power Doppler ultrasound (PDUS) images of several orthogonal cross-sections of the testis to construct a three-dimensional (3D) mapping of preferential testicular regions in which spermatozoa are most likely to be found in nonobstructive azoospermic testes.

DESIGN

Clinical study.

SETTING

Ultrasound and andrology units in a large university-affiliated municipal hospital.

PATIENT(S)

Twenty-four nonobstructive azoospermic men.

INTERVENTION(S)

Before testicular sperm extraction was performed, PDUS images were acquired at seven cross-sections to reconstruct a 3D testicular vascularity index (TVI) matrix for spatial mapping of testicular regions in which spermatozoa are most likely to be found. The predictions based on TVI values of 107 regions were compared with the biopsy results.

MAIN OUTCOME MEASURE(S)

Prediction of presence or absence of spermatozoa by TVI values.

RESULT(S)

The prediction rate of the TVI matrix for the presence or absence of spermatozoa was 74.8%. The positive predicted value was 72%, negative predicted value was 75.6%, and specificity was 89.8%, but sensitivity was 47.3%.

CONCLUSION(S)

Our technique may obviate the need for arbitrary multiple biopsies that inflict some degree of damage upon testicular tissue and may increase the success rate of identifying viable spermatozoa in testicular tissue.

A glance into the uterus during in vitro simulation of embryo transfer

BACKGROUND

The currently low implantation rate after embryo transfer (ET) is partially attributed to technical aspects, such as catheter type, catheter load, placement of catheter tip and physician skills.

METHODS

Mock ET simulations were conducted with a transparent laboratory model of the uterine cavity. The catheter was loaded with alternating air and coloured liquid media. The transfer procedure was recorded by a digital video camcorder for later analysis. Different sequences of air and liquid volumes, as well as liquids of different viscosity were simulated.

RESULTS

Injection of liquid with air into the uterus formed an air bubble which blocked the transport of the transferred liquid towards the fundus. The distribution of the transferred matter within the uterine cavity was determined by the composition of the liquid-air sequence and the viscosity ratio between the transferred liquid and the uterine fluid.

CONCLUSIONS

It is suggested that the catheter load should contain minimal volumes of air in order to enhance the embryos' chances of reaching the site of implantation. The viscosity of the transferred liquid should be as close as possible to that of the uterine fluid in order to avoid transport of embryos towards the cervix.

Biofluid Aspects of Embryo Transfer

Embryo transfer (ET) is the last stage of extracorporal fertilization during which the embryo is placed in the uterine cavity with a medium-filled catheter 2-3 days after in vitro fertilization. While fertilization in the laboratory occurs at very high rates (> 90%), the overall success of the procedure (i.e., take home baby) is still very low (< 25%) and assumed to be mainly due to implantation failure. A computational model was developed to simulate ET within the uterine cavity by a fluid-filled catheter inserted into a two-dimensional channel with oscillating walls. The results showed that the speed at which the embryos are injected from the catheter dominates the procedure and controls the velocity of their transport within the uterine cavity. ET at excessively high injection speeds may lead to ectopic pregnancies, while uterine peristalsis affects transverse dispersion only during injection at low injection speeds. The presence of the catheter within the uterus does not affect flow patterns downstream of its tip. The potential risks to implantation failure due to mechanical factors involved in the ET processes are discussed.

Effect of 1 week of oral hydration on the amniotic fluid index

OBJECTIVE

To evaluate the effect of long-term (1-week) oral hydration on amniotic fluid volume in women with an amniotic fluid index (AFI) < 10th percentile.

STUDY DESIGN

This prospective, nonrandomized, interventional study was conducted on 30 women with AFI < 10th percentile. Study inclusion criteria were singleton pregnancy, well-established gestational age, intact membranes, no maternal complications (e.g., hypertension, cardiovascular disease, hyperthyroidism), no evidence of preeclampsia, no fetal structural malformations and no evidence of fetal distress. The women were instructed to drink at least 2L of water daily; their AFI was evaluated before and 1 week after the initiation of oral hydration. The study group was compared to a control group of 30 women matched for age and gestational age, with AFI > 10th and < 90th percentile.

RESULTS

AFI increased from 8.1 +/- 0.73 (mean +/- SD) to 11.8 +/- 2.4 1 week later (P < .01) in 25 (83%) of the study subjects. The AFI was similar before and 1 week after oral hydration in all the controls.

CONCLUSION

Long-term maternal oral hydration seems to significantly increase the AFI in selected women with reduced fluid and possibly prevents oligohydramnios.

Tension-free vaginal tape for stress urinary incontinence: Is there a learning curve?

AIM

To assess the learning curve characteristics of the first 30 tension-free vaginal tape (TVT) procedures carried out in our medical center and to evaluate its safety and short-term effectiveness.

METHODS

A total of 30 incontinent women with urodynamically proven SUI were enrolled. None had undergone any previous anti-incontinence procedure. All were operated on by one surgeon, in accordance with the technique described by Ulmsten et al. in 1996. Mean follow-up was 11.4+/- 3.6 months (range, 5-17 months).

RESULTS

Five (17%) bladder perforations occurred at the beginning of the study, due to inadvertent insertion of the applicator. All perforations were identified by intraoperative cystoscopy. Five other patients (17%) had increased intraoperative bleeding (>200 mL) necessitating vaginal tamponade. Blood transfusions were not required. Eight (27%) patients had immediate postoperative voiding difficulties, necessitating catheterization for 2-10 days, but none needed long-term catheterization. There was no local infection or rejection of the Prolene tape was found. All patients were subjectively cured of their stress incontinence; however, urodynamic evaluation revealed "asymptomatic genuine stress incontinence" in one patient. Sixteen of 21 patients (80%) with preoperative urge syndrome, had persistent postoperative symptoms. No patient developed de novo urge incontinence.

CONCLUSION

The TVT operation is a new, minimally invasive surgical procedure with excellent short- and medium-term cure rates. However, there is a definite learning curve, and we believe that the operation should only be performed by experienced surgeons.

The effect of intrauterine growth restriction on the development and health of children

The neurodevelopmental and cognitive outcome of long-term Intrauterine Growth Restriction (IUGR) has been followed up from pregnancy to school age at the Tel Aviv Child Development Centre.

Prediction of fetal weight by ultrasound: the contribution of additional examiners

OBJECTIVES

To assess the contribution of additional examiners to: the average discrepancy between estimated and actual fetal weights; the correlation between estimated and actual fetal weights; the reduction in major (> 10%) discrepancies between estimated and actual fetal weights.

DESIGN

Three experienced sonographers independently measured fetal biparietal diameter, head circumference, abdominal circumference and femur length in 39 fetuses at term. The estimated fetal weights were calculated for each examiner. Fetal biometric measurements were analyzed to obtain the source of differences in estimations among the examiners. Discrepancy, correlation and number of major (> 10%) discrepancies between the estimated and actual fetal weights were calculated for each examiner, and the contribution of additional examiners was analyzed.

RESULTS

The differences in measurements of the biparietal diameter and femur length were lower than those of the head and abdominal circumferences. For each of the three examiners, the average discrepancy between the estimated and actual fetal weights was 6.1%, 5.9% and 6.3%. When the estimation was based on two examiners, the discrepancy decreased to 4.8-5.6%. The contribution of a third examiner was nil. Major (> 10%) discrepancies between estimated fetal weight and actual birth weight were found in seven, eight and nine estimations of the examiners. Estimation by two examiners decreased the number of major discrepancies, and estimation by all three examiners further decreased by approximately 50% the number of major discrepancies between the estimated and actual fetal weights.

CONCLUSION

Measurements by multiple examiners changes only slightly the average number of discrepancies between estimated and actual fetal weights. However, the reduction in major (> 10%) discrepancies is statistically and clinically significant.

Persistent right umbilical vein: incidence and significance

OBJECTIVES

To conduct a prospective evaluation of the incidence and neonatal outcome of fetuses with persistent right umbilical vein. This condition had traditionally been considered to be extremely rare and to be associated with a very poor neonatal prognosis, but later evidence has raised some doubts about the veracity of these contentions.

METHODS

Between August 1995 and November 1998, 8950 low-risk patients were prospectively evaluated at two medical centers. The sonographic diagnosis of a persistent right umbilical vein was made in a transverse section of the fetal abdomen when the portal vein was curved toward the stomach, and the fetal gall bladder was located medially to the umbilical vein.

RESULTS

Persistent right umbilical vein was detected in 17 fetuses during the study. Four of them had additional malformations, of which three had been detected antenatally.

CONCLUSIONS

We established that the incidence of persistent right umbilical vein in a low-risk population is 1 : 526. We believe that the sonographic finding of this anomaly is an indication for conducting targeted fetal sonography and echocardiography. When the persistent right umbilical vein is connected to the portal system and other anomalies are ruled out, the prognosis can generally be expected to be favorable.

Effect of the supine position on uterine and umbilical blood flow during the third trimester of uncomplicated pregnancies in multiparous patients

We established the effects of the supine position on umbilical blood flow when measured during the third trimester in 30 multiparous, normotensive patients. Blood flow in the umbilical and uterine arteries and blood pressure in the brachial and popliteal arteries were blindly taken by two different observers: first in the lateral and 5 min later in the supine position. There was a significant difference in mean blood pressure between the two postures. However, there was no statistical difference in the pulse pressure or in systolic/diastolic ratio in the umbilical and uterine arteries between the two positions. Postural changes in normotensive multiparous patients do not affect uterine and umbilical blood flow during the third trimester of uncomplicated pregnancies.

Sonographic detection of undescended testes in the third trimester

OBJECTIVE

To assess the sonographic detection rate of fetal undescended testes among a low-risk population during the third trimester.

METHODS

A sonographic evaluation, which included biometric studies and a detailed examination of the fetal genitalia, was performed prospectively on 332 male fetuses of singleton pregnancies between 34 and 40 weeks' gestation. A qualified neonatologist examined the presence of the testes within the scrotum within 3 days after birth.

RESULTS

The scrotum was visible in 294 (89%) of the 332 fetuses who were examined. It was visible in all fetuses evaluated between 34 and 36 weeks' gestation. Nine cases of undescended testes were detected (3%). Of these, the diagnosis of 1 case, examined at 34 weeks' gestation, was revealed after birth to be false-positive. There were no false-negative results.

CONCLUSIONS

Sonographic examination during the late third trimester of pregnancy appears to allow accurate diagnosis of undescended testes prenatally. This early identification will alert the neonatologist of the possibility of cryptorchidism and will permit early postnatal identification and treatment.

The mechanism of hydrosalpinx in embryo implantation

BACKGROUND

Hydrosalpinx adversely affects embryo implantation and contributes to poor implantation rates post embryo transfer. Embryo transport depends on concomitant intrauterine fluid motion induced by uterine wall motility, the result of spontaneous myometrial contractions towards the fundus.

METHODS AND RESULTS

The uterine dynamics of five patients with hydrosalpinx were recorded and analysed by image-processing techniques: the frequency was higher while the amplitudes and passive widths were lower compared with healthy volunteers. The existing peristaltic activity should have induced intrauterine fluid flow; however, the recordings failed to show the expected transport of fluid bolus. This observation was supported by mathematical simulations based on the hypothesis that fluid accumulation in the Fallopian tube of a patient with hydrosalpinx increases tubal pressure and thereby induces a pressure gradient between the fundus and the cervix. This pressure gradient acts adversely to the cervix-to-fundus intrauterine peristalsis and generates reflux currents that may thrust embryos away from the implantation site.

CONCLUSIONS

The reflux phenomenon could explain the reduced implantation rate associated with hydrosalpinx. Resolution of the issue of whether the removal of a Fallopian tube with hydrosalpinx should be undertaken for improving IVF pregnancy rates should be accompanied by prospective randomized clinical trials.

Vascularity index distribution within the testis: a technique for guiding testicular sperm extraction

Azoospermia is defined as the absence of spermatozoa in the ejaculate, although some foci of spermatogenesis may exist in the testes of these men. Currently, there are no clinical, seminal or hormonal parameters for identifying spermatogenesis within the testis sufficient for achieving genetic offspring. As a result, multiple biopsies are performed at several arbitrary sites of both testes in search of spermatozoa. We developed a power Doppler (PD) ultrasound (US) image-based technique that predicts sites with the greatest potential for spermatogenesis. PDUS images of the testes of azoospermic men were acquired at seven cross-sections to reconstruct a 3-D matrix for constructing a spatial map of preferential regions where spermatozoa are most likely to exist. This technique may obviate the need for arbitrary multiple biopsies that inflict some degree of damage upon testicular tissue, and may increase the success rate of identifying viable spermatozoa in testicular biopsies.

Peristaltic flow in a tapered channel: application to embryo transport within the uterine cavity

Cyclic uterine peristalsis plays a central role in assisting the transport of sperm to the fallopian tube and later in the conception process in transporting the embryo to a fundal site for implantation. Fulfillment of these essential events within the time limits of fertilization and implantation depends on concomitant intrauterine fluid motion induced by uterine wall motility. A model of wall-induced fluid flow within a finite tapered two-dimensional channel was developed to simulate intrauterine fluid flow pattern and transport phenomena due to symmetric and asymmetric wall displacements. The analysis showed that the transport phenomena are strongly dependent on the phase shift of wall displacement and the angle between the walls. The velocities, flow rates, pressure and the axial transport of massless particles are reduced to zero when contractions are completely out of phase. Cases of reflux and trapping in a tapered channel are discussed for the first time. The reflux phenomenon is most likely to occur when wall motility is asymmetric, especially when the angle between the walls increases, while trapping is enhanced as the asymmetric motility and the angle between the channel walls decrease. The relevance of the results to intrauterine fluid transport phenomena, embryo transfer and hydrosalpinx was explored.

Characteristics of uterine peristalsis in spontaneous and induced cycles

OBJECTIVE

To characterize the dynamics of the intrauterine fluid-wall interface (IUFWI) from in vivo transvaginal ultrasound images by new techniques of image processing of sagittal cross-sections of the uterus, in healthy women with normal cycles and patients treated with clomiphen citrate (CC).

DESIGN

Clinical study.

SETTING

An ultrasound unit in a large university-affiliated municipal hospital.

PATIENT(S)

Twenty-five patients with normal spontaneous cycles (group A) and nine patients treated by CC (group B).

INTERVENTION(S)

Transvaginal ultrasound examinations.

MAIN OUTCOME MEASURE(S)

Transvaginal ultrasound images were processed to carry out a computational analysis of the resultant IUFWI.

RESULT(S)

The amplitude and the width of the IUFWI were higher in group B, but the ratio of these measurements was similar in both groups. The frequency of wall motility of group A was lower and its pattern was more symmetrical than that of group B.

CONCLUSION(S)

The differences in the dynamic characteristics of spontaneous and CC-induced cycles may constitute an additional parameter that should be considered in embryo transport.

First trimester PAPP-A in the detection of non-Down syndrome aneuploidy

Combined first trimester screening using pregnancy associated plasma protein-A (PAPP-A), free beta-human chorionic gonadotrophin, and nuchal translucency (NT), is currently accepted as probably the best combination for the detection of Down syndrome (DS). Current first trimester algorithms provide computed risks only for DS. However, low PAPP-A is also associated with other chromosome anomalies such as trisomy 13, 18, and sex chromosome aneuploidy. Thus, using currently available algorithms, some chromosome anomalies may not be detected. The purpose of the present study was to establish a low-end cut-off value for PAPP-A that would increase the detection rates for non-DS chromosome anomalies. The study included 1408 patients who underwent combined first trimester screening. To determine a low-end cut-off value for PAPP-A, a Receiver-Operator Characteristic (ROC) curve analysis was performed. In the entire study group there were 18 cases of chromosome anomalies (trisomy 21, 13, 18, sex chromosome anomalies), 14 of which were among screen-positive patients, a detection rate of 77.7% for all chromosome anomalies (95% CI: 55.7-99.7%). ROC curve analysis detected a statistically significant cut-off for PAPP-A at 0.25 MoM. If the definition of screen-positive were to also include patients with PAPP-A<0.25 MoM, the detection rate would increase to 88.8% for all chromosome anomalies (95% CI: 71.6-106%). This low cut-off value may be used until specific algorithms are implemented for non-Down syndrome aneuploidy.