Sensitivity, specificity, and diagnostic accuracy of WHO 2013 criteria for diagnosis of gestational diabetes mellitus in low risk early pregnancies: international, prospective, multicentre cohort study

Objective

To evaluate the predictability of gestational diabetes mellitus wth a 75 g oral glucose tolerance test (OGTT) in early pregnancy, based on the 2013 criteria of the World Health Organization, and to test newly proposed cut-off values.

Design

International, prospective, multicentre cohort study.

Setting

Six university or cantonal departments in Austria, Germany, and Switzerland, from 1 May 2016 to 31 January 2019.

Participants

Low risk cohort of 829 participants aged 18-45 years with singleton pregnancies attending first trimester screening and consenting to have an early 75 g OGTT at 12-15 weeks of gestation. Participants and healthcare providers were blinded to the results.

Main outcome measures

Fasting, one hour, and two hour plasma glucose concentrations after an early 75 g OGTT (12-15 weeks of gestation) and a late 75 g OGTT (24-28 weeks of gestation).

Results

Of 636 participants, 74 (12%) developed gestational diabetes mellitus, according to World Health Organization 2013 criteria, at 24-28 weeks of gestation. Applying WHO 2013 criteria to the early OGTT with at least one abnormal value gave a low sensitivity of 0.35 (95% confidence interval 0.24 to 0.47), high specificity of 0.96 (0.95 to 0.98), positive predictive value of 0.57 (0.41 to 0.71), negative predictive value of 0.92 (0.89 to 0.94), positive likelihood ratio of 10.46 (6.21 to 17.63), negative likelihood ratio of 0.65 (0.55 to 0.78), and diagnostic odds ratio of 15.98 (8.38 to 30.47). Lowering the postload glucose values (75 g OGTT cut-off values of 5.1, 8.9, and 7.8 mmol/L) improved the detection rate (53%, 95% confidence interval 41% to 64%) and negative predictive value (0.94, 0.91 to 0.95), but decreased the specificity (0.91, 0.88 to 0.93) and positive predictive value (0.42, 0.32 to 0.53) at a false positive rate of 9% (positive likelihood ratio 5.59, 4.0 to 7.81; negative likelihood ratio 0.64, 0.52 to 0.77; and diagnostic odds ratio 10.07, 6.26 to 18.31).

Conclusions

The results of this prospective low risk cohort study indicated that the 75 g OGTT as a screening tool in early pregnancy is not sensitive enough when applying WHO 2013 criteria. Postload glucose values were higher in early pregnancy complicated by diabetes in pregnancy. Lowering the postload cut-off values identified a high risk group for later development of gestational diabetes mellitus or those who might benefit from earlier treatment. Results from randomised controlled trials showing a beneficial effect of early intervention are unclear.

Trial registration

ClinicalTrials.gov NCT02035059.

2D pelvic floor ultrasound imaging in identifying levator ani muscle trauma agrees highly with 4D ultrasound imaging

INTRODUCTION AND HYPOTHESIS

The objective was to evaluate the agreement between 2D and 4D translabial ultrasound (TLUS) technique in showing levator ani muscle (LAM) states after vaginal birth.

METHODS

In a prospective observational cohort study between March 2017 and April 2019 we evaluated LAM states (intact, hematoma, partial, complete avulsion) of primiparous women having given birth vaginally with singletons in vertex presentation ≥ 36+0 gestational weeks by using 2D and 4D TLUS within 1-4 days postpartum (assessment A1) and again 6-10 weeks postpartum (assessment A2). Cohen's Kappa analysis was performed for each side separately to evaluate the test agreement between the two ultrasound techniques at every assessment period.

RESULTS

A total of 224 women participated at A1 and 213 at A2. The agreement between the two ultrasound techniques was good to very good at A1 (Cohen`s kappa right-sided 0.78, left-sided 0.82) and very good at A2 (Cohen`s kappa both sides 0.88). The agreement was best when assessing an intact LAM or a complete avulsion (Cohen`s kappa between 0.78-0.92 for complete avulsions).

CONCLUSIONS

The comparison between 2D and 4D TLUS showed a good to very good agreement in LAM trauma immediately after birth as well as 6-10 weeks postpartum. Therefore, 2D ultrasound could also be a valuable method for demonstrating a LAM abnormality and could be used in settings where 3D/4D ultrasound equipment is not available.

The evolution of levator ani muscle trauma over the first 9 months after vaginal birth

INTRODUCTION AND HYPOTHESIS

The objective was to investigate the evolution of levator ani muscle (LAM) trauma over the first 9 months after birth and to evaluate their agreement between different assessment periods.

METHODS

From March 2017 to April 2019 we prospectively evaluated LAM states (intact, hematoma, partial or complete avulsion) of primiparous women after vaginal birth by using 4D translabial ultrasound (TLUS) at three different assessment periods. All women were examined 1-4 days (A1) and 6-10 weeks (A2) postpartum, and women with a trauma additionally 6-9 months postpartum (A3). Cohen's Kappa analysis was performed to evaluate the test agreement between the assessment periods.

RESULTS

Thirty-two percent of the women at A1 had a LAM trauma and 24% at A2. The higher number of LAM injuries at A1 can be explained by hematomas (14%), of which 51% spontaneously resolved at A2, 35% revealed themselves as partial, and 12% as complete avulsions. At A3, we observed anatomical improvement from complete to partial avulsions (23%) and few partial avulsions changed into an intact LAM (3%); none of the complete avulsions changed into an intact LAM. The agreement of 4D TLUS between A1 and A2 was moderate to good (0.64 for the right-sided LAM/0.60 for the left-sided LAM) and between A2 and A3 good to very good (0.76 right-sided/0.84 left-sided).

CONCLUSIONS

Levator ani muscle trauma can reliably be diagnosed during all assessment periods. However, the agreement between A1 and A2 was only moderate to good. This can be explained by hematomas inside the LAM that were only observed early postpartum. We observed some anatomical improvement at A3, but no complete avulsion improved to an intact LAM.

Location of obstetric anal sphincter injury scars on translabial tomographic ultrasound

OBJECTIVE

Obstetric anal sphincter injury (OASI) is a common preventable cause of anal incontinence. Both diagnosis and primary repair of OASI are often suboptimal, partly owing to the absence of effective clinical audit. The aim of this study was to evaluate the location of scars or defects of the external anal sphincter (EAS), diagnosed by translabial ultrasound (TLUS), following primary OASI repair.

METHODS

This was a retrospective analysis of 309 women who were seen at a tertiary obstetric unit after primary repair of OASI between June 2012 and May 2019. All women underwent a standardized interview, including St Mark's incontinence score, followed by clinical examination and TLUS assessment within 2-9 months after OASI repair. Postprocessing of TLUS volume datasets was performed by an investigator who was blinded to all other information. Tomographic ultrasound imaging was used to evaluate the presence of a scar or defect in the proximal and distal parts of the EAS. Women were classified into four groups according to the imaging findings: (1) no visible defect or distortion (likely false positive); (2) only proximal OASI; (3) only distal OASI; and (4) both proximal and distal OASI.

RESULTS

Of the 309 women seen during the study period, 34 were excluded because they were referred for reasons other than recent (< 1 year) OASI, 16 owing to missing data and four owing to poor image quality, leaving 255 patients for analysis. Women were seen on average 0.25 ± 0.1 years after the index birth, and their mean age at delivery was 29.1 ± 4.6 years. Anal incontinence was reported by 97 (38.0%) women. A scar or defect was seen only in the proximal part of the EAS in 64 (25.1%) women and only in the distal part in 19 (7.5%) (P < 0.001). In 165 (64.7%) women, the damage affected both the proximal and distal EAS.

CONCLUSIONS

EAS scars after primary OASI repair commonly affect the entire length of the EAS; however, partial tears seem to be more likely to occur proximally. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Birth tears after spontaneous and vacuum-assisted births with different vacuum cup systems - a retrospective cohort study

Objectives Birth tears are a common complication of vaginal childbirth. We aimed to evaluate the outcomes of birth tears first by comparing the mode of vaginal birth (VB) and then comparing different vacuum cups in instrumental VBs in order to better advise childbearing women and obstetrical professionals. Methods In a retrospective cohort study, we analyzed nulliparous and multiparous women with a singleton pregnancy in vertex presentation at ≥37 + 0 gestational weeks who gave birth vaginally at our tertiary care center between 06/2012 and 12/2016. We compared the distribution of tear types in spontaneous births (SBs) vs. vacuum-assisted VBs. We then compared the tear distribution in the vacuum group when using the Kiwi Omnicup or Bird's anterior metal cup. Outcome parameters were the incidence and distribution of the different tear types dependent on the mode of delivery and type of vacuum cup. Results A total of 4549 SBs and 907 VBs were analyzed. Birth tear distribution differed significantly between the birth modes. In 15.2% of women with an SB an episiotomy was performed vs. 58.5% in women with a VB. Any kind of perineal tear was seen in 45.7% after SB and in 32.7% after VB. High-grade obstetric anal sphincter injuries (OASIS) appeared in 1.1% after SB and in 3.1% after VB. No significant changes in tear distribution were found between the two different VB modes. Conclusions There were more episiotomies, vaginal tears and OASIS after VB than after SB. In contrast, there were more low-grade perineal and labial tears after SB. No significant differences were found between different vacuum cup systems, just a slight trend toward different tear patterns.

Association between levator ani muscle avulsions and technique of vacuum extraction - a prospective exploratory study

AIMS OF THE STUDY

Trauma of the levator ani muscle in the form of partial or complete avulsions is common after vaginal births, especially after vaginal-operative births. As there is little information available regarding associations between the technique of vaginal-operative births and levator ani muscle trauma, we aimed to evaluate the association between the process of vacuum extraction and the occurrence of levator ani muscle trauma.

METHODS

As part of a prospective cohort study at the University Hospital of Zurich between March 2017 and April 2019, we sub-analysed vacuum extractions in nulliparous women with singletons in vertex presentation &ge;36+0 gestational weeks. We evaluated their pelvic floor for partial and complete levator ani muscle avulsions using translabial ultrasound 6&ndash;10 weeks postpartum and calculated the association of the vacuum procedure itself, along with other fetal, maternal and obstetrical characteristics, with levator ani muscle trauma.

RESULTS

Levator ani muscle trauma was present in 17 (34.7%) out of 49 women. There were no associations between the different factors evaluated and levator ani muscle trauma in vacuum-assisted births, except that the levator ani muscle group had insufficient uterine contractions.

CONCLUSIONS

We found no fetal, maternal or obstetrical characteristics or parameters of vacuum technique that were associated with the occurrence of levator ani muscle trauma after vacuum extraction, except for insufficient uterine contractions. Nevertheless, there might be influencing factors that have not yet been evaluated, or are not easily accessible for evaluation, like the adaptations of the fetus inside the birth canal and within the hiatus of the levator ani muscle, and the adaptations of the birth canal to the fetus passing through. This should be the subject of further research with a sample size adequately powered to answer this question properly. (Trial registration number: BASEC-Nr.2016-00908.) &nbsp.

[Placental Locations in Subsequent Pregnancies - A Retrospective Study]

INTRODUCTION

Different locations of the placenta are associated with specific risks during pregnancy and labor. Knowledge of the placental location helps to provide better care for the expectant mother and her unborn child. Whereas multiple studies show a higher risk for a recurrent placenta previa, hardly any such data is available for any other placental location. The aim of this study was to analyze the frequency of distribution of different placental locations and to evaluate correlations between placental locations in subsequent pregnancies.

MATERIAL AND METHODS

In a retrospective cohort study women with singleton pregnancies ≥ 24 gestational weeks who had at least one ultrasound with identification of the placental location and gave birth to their firstborn and at least one more following child at our hospital between 2007 and 2016 were evaluated. Exclusion criteria were multiple pregnancies, abortions, intrauterine fetal death, and fetal malformations. Placental locations were classified into anterior, posterior, fundal, right, left, and previa.

RESULTS

Data of 1657 women were analyzed. The most frequent location was anterior, followed by posterior, fundal and lateral, and previa. Statistical analysis showed no significant correlations in subsequent pregnancies regarding placental locations.

CONCLUSION

Placental locations in subsequent pregnancies seem not to be influenced by previous pregnancies. Therefore no prognosis for placental location can be made concerning future pregnancies.

Association between the side of levator Ani muscle trauma and fetal position at birth - a prospective observational study

INTRODUCTION

Trauma of the levator ani muscle (LAM) is common after vaginal birth and can most reliably be diagnosed by 3-dimensional (3D) translabial ultrasound (TLUS). Multiple risk factors are known in general, but not in association to a specific side of the body. Therefore, our aim was to evaluate different impact factors which cause LAM trauma on either side of the body or bilateral by focusing on the fetal position at birth.

MATERIAL AND METHODS

As part of a prospective cohort study between 3/2017 and 4/2019, we analyzed vaginal births of nulliparous women with singletons in vertex presentation≥36+0 gestational weeks. We evaluated their pelvic floor for hematomas, partial and complete LAM avulsions by 3D TLUS 2-4 days postpartum and searched for an association between the affected body side and different fetal, maternal and obstetrical factors.

RESULTS

71 out of 213 women (33.3%) suffered from LAM trauma - 17 (23.9%) on the right side, 20 (28.2%) on the left side and 34 (47.9%) bilateral. No association between the different evaluated factors and the affected body side could be identified, except for the quality of fetal heart rate tracing.

CONCLUSIONS

No significant impact factors of LAM trauma could be associated with a specific side of the body. Other possible mechanisms need investigation in the future, such as the time of the birth canal and the fetus to adapt to each other, including adequate time for the tissue to stretch and the fetus to rotate into the ideal position within the LAM hiatus.

EINLEITUNG

Levatormuskelverletzungen sind häufig nach Vaginalgeburten und können zuverlässig mittels translabialem 3D-Ultraschall diagnostiziert werden. Diverse Risikofaktoren sind hierfür bekannt, allerdings keine hinsichtlich der Assoziation zu einer der beiden Körperseiten. Daher war das Ziel dieser Arbeit, verschiedene Einflussfaktoren im Rahmen vaginaler Geburten zu evaluieren, welche eine Levatorverletzung auf einer der beiden Körperseiten bzw. beidseitig begünstigen, v. a. hinsichtlich der Kindsposition im Geburtskanal.

MATERIAL UND METHODIK

In einer prospektiven Kohortenstudie analysierten wir von 3/2017-4/2019 Erstgebärende mit vaginalen Einlingsgeburten aus Schädellage≥36+0 SSW. Wir evaluierten 2-4 Tage postpartal ihren Beckenboden mittels 3D-Ultraschall hinsichtlich Hämatomen sowie partiellen und kompletten Levatoravulsionen und suchten nach Assoziationen zwischen der betroffenen Körperseite und fetalen, maternalen und geburtshilflichen Einflussfaktoren.

ERGEBNISSE

Von 213 Frauen erlitten 71 (33.3%) eine Levatorverletzung - 17 (23.9%) rechtsseitig, 20 (28.2%) linksseitig und 34 (47.9%) beidseitig. Es wurden keine Assoziationen zwischen den untersuchten Einflussfaktoren und der betroffenen Körperseite gefunden, bis auf die Qualität der fetalen Herzfrequenz.

DISKUSSION

Es konnten keine signifikanten Einflussfaktoren für das Auftreten einer Levatorverletzung einer spezifischen Körperseite eruiert werden. Daher bedarf es in Zukunft der Untersuchung weiterer Mechanismen, wie der Adaptationsvorgänge von Geburtskanal und Fet und der adäquaten Zeit für das Gewebe zur notwendigen Dehnung, v. a. im Bereich der Levatoröffnung.

Birth Lacerations in Different Genital Compartments and their Effect on Maternal Subjective Outcome: A Prospective Observational Study

Introduction Lacerations are common in vaginal births, but little is known about tears other than perineal tears and their association with maternal impairment. This study aimed to evaluate the frequency and distribution of birth lacerations and their association with maternal discomfort.

Methods From 2/2015 to 12/2016, we conducted a prospective observational study on 140 women with singletons in vertex presentation at term, who gave birth vaginally in our center and were affected by a laceration. The lacerations were assigned objectively and subjectively to eight genital tract compartments. The presence and effect of lacerations on maternal health were assessed by questionnaires for the time before birth (T1), 1–4 days (T2), and 6–8 weeks postpartum (T3).

Results The number of affected compartments was 1.33 objectively and 2.99 at T2 and 1.27 at T3 subjectively. The most affected compartment was the right perineum (73%) followed by the right inner posterior (21%) and the right outer anterior (14%) compartment. Subjective and objective assessment concurred in 83% at T2 and 69% of cases at T3. Overall, impairment of women was low, reversible, and not directly associated with the location of lacerations, although women were psychologically affected.

Conclusion Birth lacerations predominantly appear at the right perineum. Physical impairment from these lacerations is generally low, reversible, and not directly associated with the location of lacerations, although psychological impairment is not negligible.

Assoziation zwischen Geburtsverletzungen und der Einführung geburtshilflicher Observationsmaßnahmen: eine retrospektive Kohortenstudie

Einführung Ein Großteil aller Geburten geht mit irgendeiner Form von Geburtsverletzung einher. Dies kann enorme physische wie auch psychische Auswirkungen auf die betroffenen Frauen haben. Die Bemühungen von Geburtshelfern und Hebammen zielen daher darauf ab, Geburtsverletzungen weitestgehend zu reduzieren. Hierzu haben wir die Assoziation zwischen der Einführung verschiedener geburtshilflicher Observationsmaßnahmen in der Gebärabteilung und der Inzidenz und Lokalisation der verschiedenen Arten von Geburtsverletzungen untersucht.

Material und Methode In einer retrospektiven Datenanalyse evaluierten wir nullipare und multipare Frauen mit Einlingsschwangerschaften in Schädellage, die in unserem Universitätsspital zwischen Oktober 2014 und September 2015 vaginal ein Kind zur Welt brachten. Wir untersuchten 3 unterschiedliche Zeitintervalle zu je 4 Monaten (T1=4 Monate vor Einführung der Observationsmaßnahmen, T2=0–4 Monate danach und T3=5–8 Monate danach). Zielparameter waren die Inzidenz und Verteilung der verschiedenen Typen der Geburtsverletzungen während der 3 unterschiedlichen Zeiträume.

Resultate Die Inzidenz aller Arten von Geburtsverletzungen sank nicht signifikant von 95,52% bei Nulliparen und 68,53% bei Multiparen während T1 auf 89,92% und 62,27% während T3, v. a. in Form eines Rückgangs an perinealen und vulvären/labialen Verletzungen hin zu einem Anstieg an vaginalen Verletzungen. Die Rate an Episiotomien und höhergradigen Dammrissen blieb zwischen den Zeitintervallen hierbei jedoch stabil (Nullipare 33 und 3%, Multipare 10 und 0,4%)

Schlussfolgerung Die Inzidenz von Geburtsverletzungen ist gesamthaft hoch, wobei Verletzungen hauptsächlich in Form von Dammrissen ersten und zweiten Grades sowie als Vaginal- und Labienrisse auftreten. Die Einführung verschiedener geburtshilflicher Observationsmaßnahmen in der Gebärabteilung ist mit einer Veränderung in der Inzidenz von Geburtsverletzungen und mit einer Verlagerung derselben von extern nach intern vergesellschaftet, wahrscheinlich bedingt durch ein bedachteres Handeln des geburtshilflichen Personals. Die Einführung solcher Observationsmaßnahmen könnte daher eine Verbesserung geburtshilflichen Handelns bringen, wovon Frauen unter der Geburt profitieren könnten. Nichts desto trotz darf der alleinige Effekt, den eine Beobachtung und Überwachung während des Verlaufs von Observationsstudien bringt, nicht außer Acht gelassen werden.

Video analysis for the evaluation of vaginal births: a prospective observational study

AIMS OF THE STUDY Video documentation is nowadays well established in many fields of medicine, but mostly in unreal situations such as simulation training. We here present the application of video for teaching and learning purposes during the birth process. The aim of video documentation during labour is to provide an observational tool for obstetric care by midwives and obstetricians, with the opportunity for evaluation and education afterwards, especially in absence of the woman in labour and her family. METHODS Between February 2015 and June 2017, we conducted a prospective observational study on women aged over 18 years with singleton pregnancies with vertex presentation at term, who gave birth vaginally in the labour ward at the Division of Obstetrics of the University Hospital of Zurich. The end of birth (crowning of the head and fetal extraction) with the manual actions and manoeuvers performed was recorded on video in 100 births. Procedures were analysed afterwards by a senior consultant and evaluated with the staff involved. RESULTS We found frequent notable omissions during vaginal deliveries, concerning technical and nontechnical skills. Those aspects included inappropriate aseptic technique (e.g., no sterile underlay or sterile gloves), improper fetal head slowdown during expulsion, lack of visualisation of the perineum during fetal extraction/expulsion, lack of hip, shoulder and arm guiding while extracting the fetus, inappropriate episiotomy technique (wrong handling of the scissors, cutting angle too steep) and improper communication between the woman giving birth and the staff. During vacuum extractions, incorrect positioning of the cup, and inappropriate direction of pulling and handling of the cup were recorded. CONCLUSIONS Video analysis of obstetric procedures in the labour ward is an easily applicable and very useful tool for teaching and learning purposes. It contributes to showing and improving the quality of procedures and the interactions of the staff and can be used for staff evaluation. ​ Registered at ClinicalTrials.gov (registration number NCT02295904)

Video analysis for the evaluation of vaginal births: a prospective observational study

AIMS OF THE STUDY

Video documentation is nowadays well established in many fields of medicine, but mostly in unreal situations such as simulation training. We here present the application of video for teaching and learning purposes during the birth process. The aim of video documentation during labour is to provide an observational tool for obstetric care by midwives and obstetricians, with the opportunity for evaluation and education afterwards, especially in absence of the woman in labour and her family.

METHODS

Between February 2015 and June 2017, we conducted a prospective observational study on women aged over 18 years with singleton pregnancies with vertex presentation at term, who gave birth vaginally in the labour ward at the Division of Obstetrics of the University Hospital of Zurich. The end of birth (crowning of the head and fetal extraction) with the manual actions and manoeuvers performed was recorded on video in 100 births. Procedures were analysed afterwards by a senior consultant and evaluated with the staff involved.

RESULTS

We found frequent notable omissions during vaginal deliveries, concerning technical and nontechnical skills. Those aspects included inappropriate aseptic technique (e.g., no sterile underlay or sterile gloves), improper fetal head slowdown during expulsion, lack of visualisation of the perineum during fetal extraction/expulsion, lack of hip, shoulder and arm guiding while extracting the fetus, inappropriate episiotomy technique (wrong handling of the scissors, cutting angle too steep) and improper communication between the woman giving birth and the staff. During vacuum extractions, incorrect positioning of the cup, and inappropriate direction of pulling and handling of the cup were recorded.

CONCLUSIONS

Video analysis of obstetric procedures in the labour ward is an easily applicable and very useful tool for teaching and learning purposes. It contributes to showing and improving the quality of procedures and the interactions of the staff and can be used for staff evaluation.

Presenilin PS1∆E9 disrupts mobility of secretory organelles in rat astrocytes

AIM

Alzheimer's disease (AD) is largely considered a neuron-derived insult, but also involves failure of astroglia. A recent study indicated that mutated presenilin 1 (PS1M146V), a putative endoplasmic reticulum (ER) Ca²⁺ channel with decreased Ca²⁺ conductance, impairs the traffic of astroglial peptidergic vesicles. Whether other pathogenically relevant PS1 mutants, such as PS1ΔE9, which code for ER channel with putative increased Ca²⁺ conductance, similarly affect vesicle traffic, is unknown.

METHODS

Here, we cotransfected rat astrocytes with plasmids encoding mutant PS1ΔE9 and atrial natriuretic peptide or vesicular glutamate transporter 1 tagged with fluorescent proteins (pANP.emd or pVGLUT1-EGFP respectively), to microscopically examine whether alterations in vesicle mobility and Ca²⁺ -regulated release of gliosignalling molecules manifest as a general vesicle-based defect; control cells were transfected to co-express exogenous or native wild-type PS1 and pANP.emd or pVGLUT1-EGFP. The vesicle mobility was analysed at rest and after ATP stimulation that increased intracellular calcium activity.

RESULTS

In PS1ΔE9 astrocytes, spontaneous mobility of both vesicle types was reduced (P < .001) when compared to controls. Post-stimulatory recovery of fast vesicle mobility was hampered in PS1ΔE9 astrocytes. The ATP-evoked peptide release was less efficient in PS1ΔE9 astrocytes than in the controls (P < .05), as was the pre-stimulatory mobility of these vesicles.

CONCLUSION

Although the PS1 mutants PS1M146V and PS1ΔE9 differently affect ER Ca²⁺ conductance, our results revealed a common, vesicle-type indiscriminate trafficking defect in PS1ΔE9 astrocytes, indicating that reduced secretory vesicle-based signalling is a general deficit in AD astrocytes.

Impact factors on cervical dilation rates in the first stage of labor

AIMS

To assess cervical dilation rates of nulliparous and multiparous women in the active first stage of labor and to evaluate significant impact factors.

METHODS

In a retrospective cohort study between January 2007 and July 2014 at the University Hospital of Zurich in Switzerland, we analyzed 8378 women with singleton pregnancies in vertex presentation with a vaginal delivery at 34+0 to 42+5 gestational weeks. Median cervical dilation rates were calculated and different impact factors evaluated.

RESULTS

Cervical dilation rates increase during labor progress with faster rates in multiparous compared with nulliparous women (P<0.001). Dilation rates exceed 1 cm/h at a dilatation of 6-7 cm, but are very individual. Accelerating impact factors are multiparity, a greater amount of cervical dilation and fetal occipitoanterior position, whereas the use of epidural anesthesia, a higher fetal weight and head circumference decelerate dilation (P<0.001).

CONCLUSION

Cervical dilation is a hyperbolic increasing process, with faster dilation rates in multiparous compared to nulliparous women and a reversal point of labor around 6-7 cm, respectively. Besides, cervical dilation is highly individual and affected by several impact factors. The diagnosis of labor arrest or prolonged labor should therefore be based on such rates and on the individual evaluation of every woman.

Screening of gestational diabetes mellitus in early pregnancy by oral glucose tolerance test and glycosylated fibronectin: study protocol for an international, prospective, multicentre cohort trial

INTRODUCTION

As the accurate diagnosis and treatment of gestational diabetes mellitus (GDM) is of increasing importance; new diagnostic approaches for the assessment of GDM in early pregnancy were recently suggested. We evaluate the diagnostic power of an 'early' oral glucose tolerance test (OGTT) 75 g and glycosylated fibronectin (glyFn) for GDM screening in a normal cohort.

METHODS AND ANALYSIS

In a prospective cohort study, 748 singleton pregnancies are recruited in 6 centres in Switzerland, Austria and Germany. Women are screened for pre-existing diabetes mellitus and GDM by an 'early' OGTT 75 g and/or the new biomarker, glyFn, at 12-15 weeks of gestation. Different screening strategies are compared to evaluate the impact on detection of GDM by an OGTT 75 g at 24-28 weeks of gestation as recommended by the International Association of Diabetes and Pregnancy Study Groups (IADPSG). A new screening algorithm is created by using multivariable risk estimation based on 'early' OGTT 75 g and/or glyFn results, incorporating maternal risk factors. Recruitment began in May 2014.

ETHICS AND DISSEMINATION

This study received ethical approval from the ethics committees in Basel, Zurich, Vienna, Salzburg and Freiburg. It was registered under http://www.ClinicalTrials.gov (NCT02035059) on 12 January 2014. Data will be presented at international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT02035059.

Maternal and neonatal outcome of labour induction at term comparing two regimens of misoprostol

AIM

To compare the efficacy and safety of two misoprostol dosing regimens for induction of labour in primiparous (1P) and multiparous (>1P) women.

METHODS

Retrospective study of induction of labour using vaginal misoprostol 25 μg vs. 50 μg every 6 h in 942 women at a tertiary centre. The main outcome variables are induction-to-delivery interval, latency period duration, vaginal delivery within 24 h, and maternal and foetal safety outcome.

RESULTS

With the 50 μg regimen, induction-to-delivery intervals were significantly shorter: 18.4 h vs. 24.6 h (1P) and 14 h vs. 17.9 h (>1P), as was latency period duration (by 5.4 and 4 h, respectively). Vaginal delivery within 24 h was significantly more frequent, as were non-reassuring foetal heart rate (1P: 20% vs. 14%) and tachysystole (1P: 31% vs. 11%; >1P: 21% vs. 7%). No uterine rupture was reported. Neonatal outcomes were similar except for significantly more frequent infant referral to neonatal intensive care in the >1P group receiving the 50 μg regimen (11% vs. 4%).

CONCLUSION

Vaginal misoprostol 25 μg seems to maintain efficacy with more acceptable maternal and neonatal safety. As induction of labour is an off-label use for misoprostol, safety should be prioritised with the lower dosage regimen despite the longer induction-to-delivery interval.

Alterations of calcium homoeostasis in cultured rat astrocytes evoked by bioactive sphingolipids

AIM

In the brain, alterations in sphingolipid metabolism contribute to several neurological disorders; however, their effect on astrocytes is largely unknown. Here, we identified bioactive sphingolipids that affect intracellular free calcium concentration ([Ca(2+)]i), mobility of peptidergic secretory vesicles, signalling pathways involved in alterations of calcium homoeostasis and explored the relationship between the stimulus-evoked increase in [Ca(2+)]i and attenuation of vesicle mobility.

METHODS

Confocal time-lapse images were acquired to explore [Ca(2+)]i signals, the mobility of fluorescently tagged peptidergic vesicles and the structural integrity of the microtubules and actin filaments before and after the addition of exogenous sphingolipids to astrocytes.

RESULTS

Fingolimod (FTY720), a recently introduced therapeutic for multiple sclerosis, and sphingosine, a releasable constituent of membrane sphingolipids, evoked long-lasting increases in [Ca(2+)]i in the presence and absence of extracellular Ca(2+); the evoked responses were diminished in the absence of extracellular Ca(2+). Activation of phospholipase C and inositol-1,4,5-triphosphate receptors was necessary and sufficient to evoke increases in [Ca(2+)]i as revealed by the pharmacologic inhibitors; Ca(2+) flux from the extracellular space intensified these responses several fold. The lipid-evoked increases in [Ca(2+)]i coincided with the attenuated vesicle mobility. High and positive correlation between increase in [Ca(2+)]i and decrease in peptidergic vesicle mobility was confirmed independently in astrocytes exposed to evoked, transient Ca(2+) signalling triggered by purinergic and glutamatergic stimulation.

CONCLUSION

Exogenously added cell-permeable sphingosine-like lipids exert complex, Ca(2+)-dependent effects on astrocytes and likely alter their homeostatic function in vivo.

A survey on Swiss women's preferred menstrual/withdrawal bleeding pattern over different phases of reproductive life and with use of hormonal contraception

BACKGROUND

Today, options for bleeding-free lifestyle are actively promoted by the media, the pharmaceutical industry and health specialists. With regard to contraceptive counselling it is important to find out what women really want.

METHODS

In the present study we collected information on women's attitudes towards monthly bleeding and preferences, if they could have the option to modify their individual bleeding pattern. Furthermore we evaluated the preferences with use of combined hormonal contraceptives (CHCs). Switzerland has never been surveyed before with regard to these issues. Questionnaires were distributed in our family planning clinic and two outdoor offices to clients aged 15 to 19 years, 25 to 34 years, and 45 to 49 years.

RESULTS

Of 530 questionnaires, 292 were eligible for analysis. Around 50 of the participants would appreciate having fewer menstrual period-related symptoms. Some 37% preferred experiencing a monthly bleeding; 32% opted for every 2 to 6 months; and 29%, for no bleeding at all. This heterogeneous distribution did not differ between clients with and without menstrual symptoms. With regard to CHC use, predictable bleeding was rated as very positive and breakthrough bleeding as negative.

CONCLUSION

Contraceptive counsellors should be aware that women's wishes differ widely. Predictability of bleeding seems to be more important to them than postponing it.

Signaling events mediated by α3β1 integrin are essential for mammary tumorigenesis

The constitutive activation of β-catenin signaling in the mammary basal epithelial cell layer in transgenic K5ΔNβcat mice leads to basal-type tumor development. Integrins of the β1 family and integrin-mediated signaling events have an important role in breast tumor growth and progression. We show here that the deletion of α3β1 integrin, a major laminin receptor, from the basal layer of the mammary epithelium of K5ΔNβcat mice completely prevented the tumorigenesis induced by β-catenin signaling. Moreover, the depletion of α3β1 integrin from a spontaneously transformed mouse mammary basal epithelial cell line (MEC) prevented the cells from forming colonies in soft agar and greatly reduced tumor development in orthotopic grafts. Inhibition of the integrin signaling intermediates Rac1 or PAK1 (P21-activated Kinase 1) in MEC affected tumor cell growth in soft agar, whereas the expression of activated forms of these effectors in α3-depleted cells rescued the capacity of these cells to grow in non-adherent conditions. Similarly, the tumorigenic potential of α3-depleted cells was restored by the expression of activated PAK1, as assessed by orthotopic transplantation assay. In three-dimensional Matrigel culture, MEC survival and proliferation were affected by the depletion of α3β1 integrin, which also significantly decreased the activation of focal adhesion kinase (FAK), mitogen-activated protein kinase (MAPK) and c-Jun NH2-terminal kinase (JNK). Our data suggest that the activation of signaling cascades downstream from α3β1 and involving the Rac1/PAK1 pathway, MAPK and JNK, promotes prosurvival and proproliferative signals required for the malignant growth of basal mammary epithelial cells, providing further insight into the molecular mechanisms underlying breast cancer initiation and progression.

Correcting the axial shrinkage of skeletal muscle thick sections visualized by confocal microscopy

Confocal microscopy is a suitable method for measurements and visualization of skeletal muscle fibres and the neighbouring capillaries. When using 3D images of thick sections the tissue deformation effects should be avoided. We studied the deformation in thick sections of the rat skeletal muscle from complete stacks of images captured with confocal microscope. We measured the apparent thickness of the stacks and compared it to the slice thickness deduced from calibrated microtome settings. The ratio of both values yielded the axial scaling factor for every image stack. Careful sample preparation and treatment of the tissue cryosections with cold Ringer solution minimize the tissue deformation. We conclude that rescaling by the inverse of the axial scaling factor of the stack of optical slices in the direction of the microscope optical axis satisfactorily corrects the axial deformation of skeletal muscle samples.

Amyotrophic lateral sclerosis immunoglobulins G enhance the mobility of Lysotracker-labelled vesicles in cultured rat astrocytes

AIM

We examined the effect of purified immunoglobulins G (IgG) from patients with amyotrophic lateral sclerosis (ALS) on the mobility and exocytotic release from Lysotracker-stained vesicles in cultured rat astrocytes.

METHODS

Time-lapse confocal images were acquired, and vesicle mobility was analysed before and after the application of ALS IgG. The vesicle counts were obtained to assess cargo exocytosis from stained organelles.

RESULTS

At rest, when mobility was monitored for 2 min in bath with Ca(2+), two vesicle populations were discovered: (1) non-mobile vesicles (6.1%) with total track length (TL) < 1 μm, averaging at 0.33 ± 0.01 μm (n = 1305) and (2) mobile vesicles (93.9%) with TL > 1 μm, averaging at 3.03 ± 0.01 μm (n = 20,200). ALS IgG (0.1 mg mL(-1)) from 12 of 13 patients increased the TL of mobile vesicles by approx. 24% and maximal displacement (MD) by approx. 26% within 4 min, while the IgG from control group did not alter the vesicle mobility. The mobility enhancement by ALS IgG was reduced in extracellular solution devoid of Ca(2+), indicating that ALS IgG vesicle mobility enhancement involves changes in Ca(2+) homeostasis. To examine whether enhanced mobility relates to elevated Ca(2+) activity, cells were stimulated by 1 mm ATP, a cytosolic Ca(2+) increasing agent, in the presence (2 mm) and in the absence of extracellular Ca(2+). ATP stimulation triggered an increase in TL by approx. 7% and 12% and a decrease in MD by approx. 11% and 1%, within 4 min respectively. Interestingly, none of the stimuli triggered the release of vesicle cargo.

CONCLUSION

Amyotrophic lateral sclerosis-IgG-enhanced vesicle mobility in astrocytes engages changes in calcium homeostasis.

Aluminium-induced changes of fusion pore properties attenuate prolactin secretion in rat pituitary lactotrophs

Hormone secretion is mediated by Ca(2+)-regulated exocytosis. The key step of this process consists of the merger of the vesicle and the plasma membranes, leading to the formation of a fusion pore. This is an aqueous channel through which molecules stored in the vesicle lumen exit into the extracellular space on stimulation. Here we studied the effect of sub-lethal dose of aluminium on prolactin secretion in isolated rat pituitary lactotrophs with an enzyme immunoassay and by monitoring electrophysiologically the interaction of a single vesicle with the plasma membrane in real time, by monitoring membrane capacitance. After 24-h exposure to sub-lethal AlCl(3) (30 μM), the secretion of prolactin was reduced by 14±8% and 46±11% under spontaneous and K(+)-stimulated conditions, respectively. The frequency of unitary exocytotic events, recorded by the high-resolution patch-clamp monitoring of membrane capacitance, a parameter linearly related to the membrane area, under spontaneous and stimulated conditions, was decreased in aluminium-treated cells. Moreover, while the fusion pore dwell-time was increased in the presence of aluminium, the fusion pore conductance, a measure of fusion pore diameter, was reduced, both under spontaneous and stimulated conditions. These results suggest that sub-lethal aluminium concentrations reduce prolactin secretion downstream of the stimulus secretion coupling by decreasing the frequency of unitary exocytotic events and by stabilizing the fusion pore diameter to a value smaller than prolactin molecule, thus preventing its discharge into the extracellular space.

Caffeine and theophylline block insulin-stimulated glucose uptake and PKB phosphorylation in rat skeletal muscles

AIM

Caffeine and theophylline inhibit phosphatidylinositol 3-kinase (PI3-kinase) activity and insulin-stimulated protein kinase B (PKB) phosphorylation. Insulin-stimulated glucose uptake involves PI3-kinase/PKB, and the aim of the present study was to test the hypothesis that caffeine and theophylline inhibit insulin-stimulated glucose uptake in skeletal muscles.

METHODS

Rat epitrochlearis muscles and soleus strips were incubated with insulin and different concentrations of caffeine and theophylline for measurement of glucose uptake, force development and PKB phosphorylation. The effect of caffeine was also investigated in muscles stimulated electrically.

RESULTS

Caffeine and theophylline completely blocked insulin-stimulated glucose uptake in both soleus and epitrochlearis muscles at 10 mm. Furthermore, insulin-stimulated PKB Ser(473) and Thr(308) and GSK-3beta Ser(9) phosphorylation were blocked by caffeine and theophylline. Caffeine reduced and theophylline blocked insulin-stimulated glycogen synthase activation. Caffeine stimulates Ca(2+) release and force development increased rapidly to 10-20% of maximal tetanic contraction. Dantrolene (25 microm), a well-known inhibitor of Ca(2+)-release, prevented caffeine-induced force development, but caffeine inhibited insulin-stimulated glucose uptake in the presence of dantrolene. Contraction, like insulin, stimulates glucose uptake via translocation of glucose transporter-4 (GLUT4). Caffeine and theophylline reduced contraction-stimulated glucose uptake by about 50%, whereas contraction-stimulated glycogen breakdown was normal.

CONCLUSION

Caffeine and theophylline block insulin-stimulated glucose uptake independently of Ca(2+) release, and the likely mechanism is via blockade of insulin-stimulated PI3-kinase/PKB activation. Caffeine and theophylline also reduced contraction-stimulated glucose uptake, which occurs independently of PI3-kinase/PKB, and we hypothesize that caffeine and theophylline also inhibit glucose uptake in skeletal muscles via an additional and hitherto unknown molecule involved in GLUT4 translocation.

Deep brain stimulation to reward circuitry alleviates anhedonia in refractory major depression

Deep brain stimulation (DBS) to different sites allows interfering with dysfunctional network function implicated in major depression. Because a prominent clinical feature of depression is anhedonia--the inability to experience pleasure from previously pleasurable activities--and because there is clear evidence of dysfunctions of the reward system in depression, DBS to the nucleus accumbens might offer a new possibility to target depressive symptomatology in otherwise treatment-resistant depression. Three patients suffering from extremely resistant forms of depression, who did not respond to pharmacotherapy, psychotherapy, and electroconvulsive therapy, were implanted with bilateral DBS electrodes in the nucleus accumbens. Stimulation parameters were modified in a double-blind manner, and clinical ratings were assessed at each modification. Additionally, brain metabolism was assessed 1 week before and 1 week after stimulation onset. Clinical ratings improved in all three patients when the stimulator was on, and worsened in all three patients when the stimulator was turned off. Effects were observable immediately, and no side effects occurred in any of the patients. Using FDG-PET, significant changes in brain metabolism as a function of the stimulation in fronto-striatal networks were observed. No unwanted effects of DBS other than those directly related to the surgical procedure (eg pain at sites of implantation) were observed. Dysfunctions of the reward system--in which the nucleus accumbens is a key structure--are implicated in the neurobiology of major depression and might be responsible for impaired reward processing, as evidenced by the symptom of anhedonia. These preliminary findings suggest that DBS to the nucleus accumbens might be a hypothesis-guided approach for refractory major depression.

Distinct labelling of fusion events in rat lactotrophs by FM 1-43 and FM 4-64 is associated with conformational differences

AIM

Conformational analysis of fluorescent styryl dyes FM 1-43 and FM 4-64 was undertaken to clarify if distinct activity-dependent labelling of single lactotrophs vesicles and plasma membrane by two dyes is associated with their structural differences.

METHODS

The activity-dependent labelling of single vesicles and plasma membrane by FM 1-43 and FM 4-64 was studied using confocal microscopy. The fluorescence intensity of vesicles fused with the plasma membrane, and the plasma membrane alone was measured; the ratio of their respective peak amplitudes was calculated. The conformational analysis of FM 1-43 and FM 4-64 was further undertaken by employing the Monte Carlo approach to search the conformational space of these molecules.

RESULTS

In FM 1-43 staining of vesicles and plasma membrane, the ratio of the fluorescence peak amplitudes (vesicle vs. plasma membrane) was 2.6 times higher in comparison with FM 4-64 staining. In FM 4-64 molecule the low-energy conformations are distributed in three conformational states (consisting of 3, 4 and 2 conformers respectively) in which the proportion of the molecules residing in a given state is 62%, 28% and 9% respectively. In FM 1-43 the conformation distribution is limited to just one conformational state with three approximately equally populated conformers what can be explained by greater intrinsic rigidity of the molecule.

CONCLUSIONS

The observed structural characteristics of FM 1-43 molecules may account for a higher increase in quantum yield and/or binding affinity upon incorporation of the dye into the vesicle matrix and therefore stronger fluorescence emission in comparison with FM 4-64.

Distinct role of Rab3A and Rab3B in secretory activity of rat melanotrophs

Members of the Rab3 (A-D) subfamily of small GTPases are believed to play a key role in regulated exocytosis. These proteins share approximately 80% identity at amino acid level. The question of whether isoforms of Rab3 are functionally redundant was the subject of this study. We used RT-PCR analysis, in situ hybridization histochemistry, and confocal microscope-based analysis of immunocytochemistry to show that rat melanotrophs contain about equal amounts of Rab3A and Rab3B transcripts as well as proteins. Therefore, these cells are a suitable model to study the subcellular distribution and the role of these paralogous isoforms in regulated exocytosis. Secretory activity of single cells was monitored with patch-clamp capacitance measurements, and the cytosol was dialyzed with a high-calcium-containing patch pipette solution. Preinjection of antisense oligodeoxyribonucleotides specific to Rab3A, but not to Rab3B, induced a specific blockage of calcium-dependent secretory responses, indicating an exclusive requirement for Rab3A in melanotroph cell-regulated secretion. Although the injection of purified Rab3B protein was ineffective, the injection of recombinant Rab3A proteins into rat melanotrophs revealed that regulated secretion was stimulated by a GTP-bound Rab3A with an intact COOH terminus and inhibited by Rab3AT36N, impaired in GTP binding. These results indicate that Rab3A, but not Rab3B, enhances secretory output from rat melanotrophs and that their function is not redundant.

FM1-43 measurements of local exocytotic events in rat melanotrophs

We have explored the existence of fusion- and secretion-competent sites on the plasma membrane of peptide secreting rat pituitary melanotrophs at rest, and following stimulation with glutamate. We monitored changes in fluorescence of FM1-43, a styryl dye which labels plasma membrane. The results show spontaneous local increases in FM1-43 reporting changes in membrane surface area due to cumulative exocytosis. Addition of glutamate, further increased the occurrence of these events. Statistical analysis of local FM1-43 fluorescence changes suggests that this is due to the recruitment of inactive exocytotic domains and due to the stimulation of already active exocytotic domains.

Automated high through-put colocalization analysis of multichannel confocal images

The laser scanning confocal microscope (LSCM) generates images of multiple labelled fluorescent samples. Colocalization of fluorescent labels is frequently examined. Here we present an example where localization of fluorescent analogues of cloned protein were referenced to fluorescent antibodies directed against the proteins of cellular compartments. Colocalization is usually evaluated by visual inspection of signal overlap or by using commercially available software tools, but there are limited possibilities to automate the analysis of large amounts of data. We developed a simple tool using Matlab to automate the colocalization procedure and to exclude the biased estimations resulting from visual inspections of images. The script in Matlab language code automatically imports confocal images and converts them into arrays. The contrast of all images is uniformly set by linearly reassigning the values of pixel intensities to use the full 8-bit range (0-255). Images are binarized on several threshold levels. The area above a certain threshold level is summed for each channel of the image and for colocalized regions. As a result, count of pixels above several threshold levels in any number of images is saved in an ASCII file. In addition Pearson's r correlation coefficient is calculated for fluorescence intensities of both confocal channels. Using this approach quick quantitative analysis of colocalization of hundreds of images is possible. In addition, such automated procedure is not biased by the examiner's subject visualization.

Properties of exocytotic response in vertebrate photoreceptors

Synaptic transmission at the photoreceptor synapse is characterized by continuous release of glutamate in darkness. Release is regulated by the intracellular calcium concentration ([Ca2+]i). We here examined the physiological properties of exocytosis in tiger salamander (Ambystoma tigrinum) retinal rods and cones. Patch-clamp capacitance measurements were used to monitor exocytosis elicited by a rapid and uniform increase in [Ca2+]i by photolysis of the caged Ca2+ compound NP-EGTA. The amplitude of flash-induced increases in membrane capacitance (Cm) varied monotonically with [Ca2+]i beyond approximately 15 microM. The following two types of kinetic responses in Cm were recorded in both rods and cones: 1) a single exponential rise (39% of cells) or 2) a double-exponential rise (61%). Average rate constants of rapid and slow exocytotic responses were 420 +/- 168 and 7.85 +/- 5.02 s-1, respectively. The rate constant for the single exponential exocytotic response was 17.5 +/- 12.4 s-1, not significantly different from that of the slow exocytotic response. Beyond the threshold [Ca2+]i of approximately 15 microM, the average amplitude of rapid, slow, and single Cm response were 0.84 +/- 0.35, 0.82 +/- 0.20, and 0.70 +/- 0.23 pF, respectively. Antibodies against synaptotagmin I, a vesicle protein associated with fast exocytosis, strongly stained the synaptic terminal of isolated photoreceptors, suggesting the presence of fusion-competent vesicles. Our results confirm that photoreceptors possess a large rapidly releasable pool activated by a low-affinity Ca2+ sensor whose kinetic and calcium-dependent properties are similar to those reported in retinal bipolar cells and cochlear hair cells.

Apoptosis triggered redistribution of caspase-9 from cytoplasm to mitochondria

Caspase-9 is an apoptosis initiator protease activated as a response to the mitochondrial damage in the cytoplasmic complex apoptosome. By fluorescence labelling of proteins, confocal microscopy and subcellular fractionations we demonstrate that caspase-9 is in the cytoplasm of non-apoptotic pituitary cells. The activation of apoptosis with rotenone triggers the redistribution of caspase-9 to mitochondria. Experiments using the general caspase inhibitor z-VAD.fmk and the specific caspase-9 inhibitor z-LEHD.fmk show that the caspase-9 redistribution is a regulated process and requires the activity of a caspase other than the caspase-9. We propose that this spatial regulation is required to control the activity of caspase-9.

Synaptotagmin I increases the probability of vesicle fusion at low [Ca2+] in pituitary cells

Synaptotagmin I (Syt I), a low-affinity Ca(2+)-binding protein, is thought to serve as the Ca(2+) sensor in the release of neurotransmitter. However, functional studies on the calyx of Held synapse revealed that the rapid release of neurotransmitter requires only approximately micromolar [Ca(2+)], suggesting that Syt I may play a more complex role in determining the high-affinity Ca(2+) dependence of exocytosis. Here we tested this hypothesis by studying pituitary cells, which possess high- and low-affinity Ca(2+)-dependent exocytic pathways and express Syt I. Using patch-clamp capacitance measurements to monitor secretion and the acute antisense deletion of Syt I from differentiated cells, we have shown that the rapid and the most Ca(2+)-sensitive pathway of exocytosis in rat melanotrophs requires Syt I. Furthermore, stimulation of the Ca(2+)-dependent exocytosis by cytosol dialysis with solutions containing 1 microM [Ca(2+)] was completely abolished in the absence of Syt I. Similar results were obtained by the preinjection of antibodies against the CAPS (Ca(2+)-dependent activator protein for secretion) protein. These results indicate that synaptotagmin I and CAPS proteins increase the probability of vesicle fusion at low cytosolic [Ca(2+)].

Two different mutations in the cytoplasmic domain of the integrin beta 4 subunit in nonlethal forms of epidermolysis bullosa prevent interaction of beta 4 with plectin

The integrin alpha 6 beta 4 plays a crucial role in the assembly and maintenance of hemidesmosomes. Previous work has shown that the recruitment of plectin into hemidesmosomes is dependent on beta 4 and involves a region of the beta 4 cytoplasmic domain, which contains the first two fibronectin (FNIII) repeats and a short region of the connecting segment. Two missense mutations (R1225H and R1281W) in beta 4 that are responsible for nonlethal forms of epidermolysis bullosa are located in the second FNIII repeat. One of them is confined to a loop region that connects two beta strands (EC') whereas the other is located at the N-terminal end of the second FNIII repeat. We here report that these mutations render beta 4 unable to interact with plectin and prevent the localization of plectin in hemidesmosomes. Substitution of a lysine residue (K1279W) that forms part of the same loop as R1281 had no effect on the ability of beta 4 to recruit plectin. Furthermore, we show that an extended loop structure in beta 4, composed of the amino acids DDN (1262--1264), which resembles the RGD integrin-binding loop in fibronectin, is not involved in the binding to plectin. These results further demonstrate that binding of beta 4 to plectin is essential for the proper formation and function of hemidesmosomes and that loss of the interaction between beta 4 and plectin is associated with a mild form of epidermolysis bullosa.

Rapid regulated dense-core vesicle exocytosis requires the CAPS protein

Although many proteins essential for regulated neurotransmitter and peptide hormone secretion have been identified, little is understood about their precise roles at specific stages of the multistep pathway of exocytosis. To study the function of CAPS (Ca(2+)-dependent activator protein for secretion), a protein required for Ca(2+)-dependent exocytosis of dense-core vesicles, secretory responses in single rat melanotrophs were monitored by patch-clamp membrane capacitance measurements. Flash photolysis of caged Ca(2+) elicited biphasic capacitance increases consisting of rapid and slow components with distinct Ca(2+) dependencies. A threshold of approximately 10 microM Ca(2+) was required to trigger the slow component, while the rapid capacitance increase was recorded already at a intracellular Ca(2+) activity < 10 microM. Both kinetic membrane capacitance components were abolished by botulinum neurotoxin B or E treatment, suggesting involvement of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)-dependent vesicle fusion. The rapid but not the slow component was inhibited by CAPS antibody. These results were further clarified by immunocytochemical studies that revealed that CAPS was present on only a subset of dense-core vesicles. Overall, the results indicate that dense-core vesicle exocytosis in melanotrophs occurs by two parallel pathways. The faster pathway exhibits high sensitivity to Ca(2+) and requires the presence of CAPS, which appears to act at a late stage in the secretory pathway.

Transient and permanent fusion of vesicles in Zea mays coleoptile protoplasts measured in the cell-attached configuration

Exocytosis in protoplasts from Zea mays L. coleoptiles was studied using patch-clamp techniques. Fusion of individual vesicles with the plasma membrane was monitored as a step increase of the membrane capacitance (Cm). Vesicle fusion was observed as (i) An irreversible step increase in Cm. (ii) Occasionally, irreversible Cm steps were preceded by transient changes in Cm, suggesting that the electrical connection between the vesicle with the plasma membrane opens and closes reversibly before full connection is achieved. (iii) Most frequently, however, stepwise transient changes in Cm did not lead to an irreversible Cm step. Within one patch of membrane capacitance steps due to transient and irreversible fusions were of similar amplitude. This suggests that the exocytosis events do not result from the fusion of vesicles with different sizes but are due to kinetically different states in a fusion process of the same vesicle type. The dwell time histogram of the transient fusion events peaked at about 100 msec. Fusion can be described with a circular three-state model for the fusion process of two fused states and one nonfused state. It predicts that energy input is required to drive the system into a prevailing direction.

The heterotrimeric Gi(3) protein acts in slow but not in fast exocytosis of rat melanotrophs

Besides having a role in signal transduction some trimeric G-proteins may be involved in a late stage of exocytosis. Using immunocytochemistry and confocal microscopy we found that Gi(3)-protein resides mainly in the plasma membrane, whereas Gi(1/2-)protein is preferentially associated with secretory granules. To study the function of trimeric Gi(3)- and Gi(1/2)-proteins, secretory responses in single rat melanotrophs were monitored by patch-clamp membrane capacitance measurements. We report here that mastoparan, an activator of trimeric G-proteins, enhances calcium-induced secretory activity in rat melanotrophs. The introduction of synthetic peptides corresponding to the C-terminal domain of the (α)-subunit of Gi(3)- and Gi(1/2)-proteins indicated that Gi(3)peptide specifically blocked the mastoparan-stimulated secretory activity, which indicates an involvement of a trimeric Gi(3)-protein in mastoparan-stimulated secretory activity. Flash photolysis of caged Ca(2+)-elicited biphasic capacitance increases consisting of a fast and a slower component. Injection of anti-Gi(3) antibodies selectively inhibited the slow but not the fast component of secretory activity in rat melanotrophs. We propose that the plasma membrane-bound Gi(3)-protein may be involved in regulated secretion by specifically controlling the slower kinetic component of exocytosis.

Modulation of the unitary exocytic event amplitude by cAMP in rat melanotrophs

1. Secretory responses were measured in single rat pituitary melanotrophs as the relative increase in membrane capacitance (Cm) 8 min after the start of dialysis with solutions containing 0.45 microM Ca2+. In the added presence of cAMP (0.2 mM) in the patch pipette solution, capacitance responses increased 2- to 3-fold in comparison with controls. 2. To study whether cAMP-dependent mechanisms affect cytosolic calcium activity ([Ca2+]i), dibutyryl cyclic AMP (dbcAMP, 10 mM) was added to intact melanotrophs and [Ca2+]i was measured using fura-2 AM. Addition of dbcAMP caused a transient reduction in [Ca2+]i to 82 +/- 21 nM from a resting value of 100 +/- 19 nM (mean +/- S.E.M., n = 32, P < 0.002), indicating that the cAMP-induced increase in secretory activity was not the result of cAMP acting to increase [Ca2+]i, which then increased secretory activity. 3. To investigate whether cAMP affects the secretory apparatus directly, the interaction of a single secretory granule with the plasmalemma was monitored by measuring discrete femtofarad steps in Cm. The signal-to-noise ratio of recordings was increased by pre-incubating the cells with a hydrophobic anion, dipicrylamine. 4. Recordings of unitary exocytic events (discrete 'on' steps in Cm) showed that the amplitude of 'on' steps - a parameter correlated to the size of exocytosing secretory granules - increased from 4.2 +/- 0.2 fF (n = 356) in controls to 7.9 +/- 0.2 fF in the presence of cAMP (n = 329, P < 0.001), while the frequency of unitary exocytic events was similar in controls and in the presence of cAMP. 5. The results suggest that a cAMP-dependent mechanism mediates the fusion of larger granules with the plasmalemma.

[Withdrawal therapy of patients with alcoholism and nicotine dependence with carcinomas in the area of the head and neck. Luxury or necessity?]

PURPOSE

Alcohol and nicotine abuse play a major role in the etiology of oral squamous cell carcinomas. In the present study, we investigated the number of patients with oral/oropharyngeal carcinomas who regularly consume alcohol and nicotine and what type of specific treatment should be prescribed for the addiction.

PATIENTS AND METHOD

A total of 105 patients (90 men, 15 women) with oral/oropharyngeal squamous cell carcinomas were studied based on catamnestic data as well as a special questionnaire designed to assess drinking and smoking habits (40 g alcohol/day for men and 20 g alcohol/day for women was taken as the standard measure for those considered at risk for alcoholism). For smokers, the number of packs smoked per year was determined and compared to clinical data (i.e., tumor size, location) and laboratory data (gamma-GT). Particular attention was given to the addiction behavior before and after tumor therapy (recorded at least 1 year after successful tumor treatment).

RESULTS

At the time of diagnosis, 83.1% regularly drank alcohol (71.9% reported drinking over 40 g/ 20 g of alcohol per day). Another 17.9% stopped drinking after therapy. Of the alcoholics 59.8% had been exposed to a daily consumption level above the threshold amount for more than 20 years. Some 70% of the patients reported that they exclusively drank beer. Tobacco consumption came from cigarette smoking 92.7% and 89.7% reported that they smoked before therapy--after therapy only 37.8% smoked. Carcinomas of the floor of the mouth indicated a prevalence toward alcohol and nicotine abuse. Of the patients with a T3 and T4 carcinoma 84% had daily alcohol consumption levels over the threshold value stated above. None of the 105 patients underwent specific alcohol treatment therapy.

CONCLUSION

In light of the high prevalence of carcinomas of the oral cavity in patients with alcohol and nicotine addiction, mandatory withdrawal therapy should be offered in the form of postoperative treatment to prevent recurrence or the development of second primary tumors, as well as to improve the quality of life and encourage social rehabilitation. Before further treatment, for example, with retinoids, a successful withdrawal treatment should be completed.

Cell-attached measurements of attofarad capacitance steps in rat melanotrophs

Capacitance changes in cell-attached patches of rat melanotrophs were measured by a high-frequency lock-in amplifier. The background noise of around 30 aF allowed the detection of discrete steps due to fission (endocytosis) and fusion (exocytosis) of vesicles with diameters as small as 60 nm. The amplitude of both types of steps was similar with a modal value of around 300 aF. The frequency of these steps was not changed, if secretagougues such as ionomycin and/or dibutyril cAMP, were applied to the bathing solution. Moreover, this treatment did not result in an increased appearance of expected 2000 to 3000 aF steps due to exocytosis of secretory granules. We conclude that the likely explanation for recorded capacitance steps is that they represent the constitutive vesicle traffic. From the typical frequency and amplitude of these events (around 1 min-1, 300 aF) in a membrane patch (26 fF) it is estimated that the whole membrane of a rat melanotroph may be ingested under our conditions in 1 to 2 h.