Perioperative Platelet Count Ratio Predicts Long-Term Survival after Left Pancreatectomy and Splenectomy for Pancreatic Adenocarcinoma

BACKGROUND

The value of platelet characteristics as a prognostic factor in patients with pancreatic adenocarcinoma (PDAC) remains unclear.

METHODS

We assessed the prognostic ability of post-splenectomy thrombocytosis in patients who underwent left pancreatectomy for PDAC. Perioperative platelet count ratio (PPR), defined as the ratio between the maximum platelet count during the first five days following surgery and the preoperative level, was assessed in relation to long-term outcomes in patients who underwent left pancreatectomy for PDAC between November 2008 and October 2022.

RESULTS

A comparative cohort of 245 patients who underwent pancreaticoduodenectomy for PDAC was also evaluated. The median PPR among 106 patients who underwent left pancreatectomy was 1.4 (IQR1.1, 1.8). Forty-six had a PPR ≥ 1.5 (median 1.9, IQR1.7, 2.4) and 60 had a PPR < 1.5 (median 1.2, IQR1.0, 1.3). Patients with a PPR ≥ 1.5 had increased median overall survival (OS) compared to patients with a PPR < 1.5 (40 months vs. 20 months, p < 0.001). In multivariate analysis, PPR < 1.5 remained a strong predictor of worse OS (HR 2.24, p = 0.008). Among patients who underwent pancreaticoduodenectomy, the median PPR was 1.1 (IQR1.0, 1.3), which was significantly lower compared to patients who underwent left pancreatectomy (p > 0.001) and did not predict OS.

CONCLUSION

PPR is a biomarker for OS after left pancreatectomy for PDAC. Further studies are warranted to consolidate these findings.

Validation of machine-learning model for first-trimester prediction of pre-eclampsia using cohort from PREVAL study

OBJECTIVE

Effective first-trimester screening for pre-eclampsia (PE) can be achieved using a competing-risks model that combines risk factors from the maternal history with multiples of the median (MoM) values of biomarkers. A new model using artificial intelligence through machine-learning methods has been shown to achieve similar screening performance without the need for conversion of raw data of biomarkers into MoM. This study aimed to investigate whether this model can be used across populations without specific adaptations.

METHODS

Previously, a machine-learning model derived with the use of a fully connected neural network for first-trimester prediction of early (< 34 weeks), preterm (< 37 weeks) and all PE was developed and tested in a cohort of pregnant women in the UK. The model was based on maternal risk factors and mean arterial blood pressure (MAP), uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF) and pregnancy-associated plasma protein-A (PAPP-A). In this study, the model was applied to a dataset of 10 110 singleton pregnancies examined in Spain who participated in the first-trimester PE validation (PREVAL) study, in which first-trimester screening for PE was carried out using the Fetal Medicine Foundation (FMF) competing-risks model. The performance of screening was assessed by examining the area under the receiver-operating-characteristics curve (AUC) and detection rate (DR) at a 10% screen-positive rate (SPR). These indices were compared with those derived from the application of the FMF competing-risks model. The performance of screening was poor if no adjustment was made for the analyzer used to measure PlGF, which was different in the UK and Spain. Therefore, adjustment for the analyzer used was performed using simple linear regression.

RESULTS

The DRs at 10% SPR for early, preterm and all PE with the machine-learning model were 84.4% (95% CI, 67.2-94.7%), 77.8% (95% CI, 66.4-86.7%) and 55.7% (95% CI, 49.0-62.2%), respectively, with the corresponding AUCs of 0.920 (95% CI, 0.864-0.975), 0.913 (95% CI, 0.882-0.944) and 0.846 (95% CI, 0.820-0.872). This performance was achieved with the use of three of the biomarkers (MAP, UtA-PI and PlGF); inclusion of PAPP-A did not provide significant improvement in DR. The machine-learning model had similar performance to that achieved by the FMF competing-risks model (DR at 10% SPR, 82.7% (95% CI, 69.6-95.8%) for early PE, 72.7% (95% CI, 62.9-82.6%) for preterm PE and 55.1% (95% CI, 48.8-61.4%) for all PE) without requiring specific adaptations to the population.

CONCLUSIONS

A machine-learning model for first-trimester prediction of PE based on a neural network provides effective screening for PE that can be applied in different populations. However, before doing so, it is essential to make adjustments for the analyzer used for biochemical testing. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Change in prevalence of preterm birth in Israel following publication of national guidelines recommending routine sonographic cervical-length measurement at 19-25 weeks' gestation

OBJECTIVE

To compare the prevalence of preterm birth (PTB) (delivery before 37 weeks) in Israel before and after publication of national guidelines recommending second-trimester sonographic cervical-length (CL) measurement.

METHODS

The Israeli Society of Obstetrics and Gynecology (ISOG) guidelines, issued on 1 January 2012, specified that CL should be measured transabdominally or, if this is not possible, transvaginally, at the 19-25-week ultrasound anomaly scan and that CL < 25 mm should indicate further work-up and treatment, although the type of treatment was unspecified. In 2000, the Israel Ministry of Health issued a legal requirement for the submission of delivery records to a national registry. These data were used to compare PTB prevalence in the period before (2000-2011) and that after (2012-2020) publication of the guidelines, as well as trends within each time period. Information was available on singleton and multiple pregnancy and maternal age and parity, as well as low birth weight (< 2500 g).

RESULTS

During the period 2000-2020, there were 3 403 976 infants liveborn in Israel: 1 797 657 before and 1 606 319 after publication of the ISOG guidelines. There were 247 187 PTBs overall, with a prevalence of 7.64% (95% CI, 7.52-7.77%) before publication of the guidelines and 6.84% (95% CI, 6.43-7.24%) afterwards (P < 0.0002, two-tailed). The annual PTB prevalence was static in the first time period but declined by 0.18% per annum during the second period, after publication of the guidelines. The proportionate reduction in PTB prevalence after compared with before publication of the guidelines was 10% overall, 9% for PTB at 33-36 weeks, 18% for PTB at 28-32 weeks and 24% for PTB at < 28 weeks. After publication of the guidelines, reduced prevalence of PTB was observed among singletons (5.49% before vs 4.83% after, P < 0.0001), but not among infants in twin or higher-order multiple pregnancy. There was a statistically significant reduction in the rate of PTB following publication of the guidelines in both nulliparous and parous women and in the 19-39-year-old maternal-age group. Although reductions in PTB prevalence were also noted in high-risk age groups (maternal age < 19 years and ≥ 40 years), these did not reach statistical significance. Following publication of the guidelines, there was a statistically significant reduction in the prevalence of birth weight under 2500 g, of a magnitude similar to that for PTB prevalence.

CONCLUSIONS

The publication of national guidelines recommending routine CL measurement at the time of the second-trimester anomaly scan was associated with a fall in PTB prevalence in singleton pregnancies. Whilst direct evidence linking screening with this fall in prevalence is lacking, it is likely that implementation of routine CL screening played an important role in the reduction of PTB rate. Our experience indicates that screening can be incorporated into the second-trimester anomaly scan. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Outcomes of Laser-Assisted Closure (SiLaC) Surgery for Chronic Pilonidal Sinus Disease

Background: Management of pilonidal sinus (PNS) disease has changed notably in the past decade, with the introduction of novel surgical techniques and technological innovation. In this study, we summarized our initial experience with sinus laser-assisted closure (SiLaC) of pilonidal disease. Methods: A retrospective analysis of a prospective database of all patients who underwent minimally invasive surgery combined with laser therapy for PNS between September 2018 and December 2020 was performed. Patients' demographics, clinical and perioperative data, as well postoperative outcomes were recorded and analyzed. Results: A total of 92 patients (86 males, 93.4%) underwent SiLaC surgery for pilonidal sinus disease during the study period. Patients' median age was 22 (range 16-62 years), and 60.8% of them previously underwent abscess drainage due to PNS. SiLaC was performed under local anesthesia in 85.7% of cases (78 patients) with a median energy of 1081 J (range 13-5035 J). One patient was lost to follow-up, leaving 91 patients for final analysis. The primary outcome was complete healing rate, standing at 81.3% (74/91 patients). In 8 patients (8.8%), there was minor incomplete healing that did not require reintervention. Recurrent/nonhealing disease was seen in 9 patients (9.9%), requiring reoperation in 7 patients (8.4%). Of those, 4 patients underwent repeat SiLaC and 3 patients underwent wide excision. Analysis of risk factors for PNS recurrence demonstrated that general anesthesia (P = .02) was associated with increased risk for recurrence along with a trend for increased risk in patients with significant hairiness (P = .078). No differences were seen in age (P = .621), gender (P = .475), median sinus length (P = .397), and energy used (P = .904). Conclusion: Primary healing rate after SiLaC surgery for chronic PNS was >80% in our series. Ten percent of patients did not achieve complete healing but did not require surgery due to lack of symptoms.

Machine-learning-based prediction of pre-eclampsia using first-trimester maternal characteristics and biomarkers

OBJECTIVE

To evaluate the accuracy of predicting the risk of developing pre-eclampsia (PE) according to first-trimester maternal demographic characteristics, medical history and biomarkers using artificial-intelligence and machine-learning methods.

METHODS

The data were derived from prospective non-interventional screening for PE at 11-13 weeks' gestation at two maternity hospitals in the UK. The data were divided into three subsets. The first set, including 30 437 subjects, was used to develop the training process, the second set of 10 000 subjects was utilized to optimize the machine-learning hyperparameters and the third set of 20 352 subjects was coded and used for model validation. An artificial neural network was used to predict from the demographic characteristics and medical history the prior risk that was then combined with biomarker values to determine the risk of PE and preterm PE with delivery at < 37 weeks' gestation. An additional network was trained without including race as input. Biomarkers included uterine artery pulsatility index (UtA-PI), mean arterial blood pressure (MAP), placental growth factor (PlGF) and pregnancy-associated plasma protein-A. All markers were entered using raw values without conversion into standardized multiples of the median. The prediction accuracy was estimated using the area under the receiver-operating-characteristics curve (AUC). We further computed the detection rate at 10%, 20% and 40% false-positive rates (FPR). The impact of taking aspirin was also added. Shapley values were calculated to evaluate the contribution of each parameter to the prediction of risk. We used a non-parametric test to compare the expected AUC with the one obtained when we randomly scrambled the labels and kept the predictions. For the general prediction, we performed 10 000 permutations of the labels. When the AUC was higher than the one obtained in all 10 000 permutations, we reported a P-value of < 0.0001. For the race-specific analysis, we performed 1000 permutations. When the AUC was higher than the AUC in permutations, we reported a P-value of < 0.001.

RESULTS

The detection rate for preterm PE vs no PE, at a 10% FPR, was 53.3% when screening by maternal factors only, and the corresponding AUC was 0.816; these increased to 75.3% and 0.909, respectively, with the addition of biomarkers into the model. Information on race was important for the prediction accuracy; when race was not used to train the model, at a 10% FPR, the detection rate of preterm PE vs no PE decreased to 34.5-45.5% (for different races) when screening by maternal factors only and to 55.0-62.1% when biomarkers were added. The major predictors of PE were high MAP and UtA-PI, and low PlGF. The accuracy of prediction of all PE cases was lower than that for preterm PE. Aspirin use was recommended for cases who were at high risk of preterm PE. The AUC of all PE vs no PE was 0.770 when screening by maternal factors and 0.817 when the biomarkers were added; the respective detection rates, at a 10% FPR, were 41.3% and 52.9%.

CONCLUSIONS

Screening for PE using a non-linear machine-learning-based approach does not require a population-based normalization, and its performance is similar to that of logistic regression. Removing race information from the model reduces its prediction accuracy, especially for the non-white populations when only maternal factors are considered. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Regulation of acetylcholine liberation from presynaptic nerve terminals

Acetylcholine is liberated from motor nerve terminals either as a molecular leakage or as quantal packages; the latter form of release is responsible for signaling across the neuromuscular synapse. Three main factors determine the number of quanta liberated by the nerve impulse: the degree of presynaptic depolarisation, the frequency of activation of the nerve terminal, and calcium ion concentration in the extracellular medium. These factors seem to act yb changing the free calcium ion concentration [Ca]in in the presynaptic nerve terminal. Thus, processes that change [Ca]in will determine efficiency of synaptic transmission. These processes include fluxes of calcium ions across the presynaptic membrane and reversible translocation by intracellular organelles such as mitochondria, vesicles and soluble molecules. The level of intracellular [Ca] can be changed by ion-containing liposomes. One of the main physiological determinants of the level of transmitter release is potentiation, where the increase in transmitter release is caused by transmembranal processes and intracellular translocation.

Placental protein 13 and decidual zones of necrosis: an immunologic diversion that may be linked to preeclampsia

We evaluated the role of placental protein 13 (PP13; galectin 13) in the process of trophoblast invasion and decidual necrosis. Immunohistochemical analysis for PP13, immune cells, human placental lactogen, cytokeratin, and apoptosis markers was performed on 20 elective pregnancy termination specimens between 6 and 15 weeks of gestation. Placental protein 13 was localized to syncytiotrophoblasts in the chorionic villi and to occasional multinucleated luminal trophoblasts within converted decidual spiral arterioles. Cytotrophoblasts, anchoring trophoblasts, and invasive trophoblasts did not stain for PP13. Extracellular PP13 aggregates were found around decidual veins associated with T-cell-, neutrophil- and macrophage-containing decidual zones of necrosis (ZONEs). We hypothesize that PP13 is secreted into the intervillus space, drains through the decidua basalis veins, and forms perivenous PP13 aggregates which attract and activate maternal immune cells. Thus, syncytiotrophoblast-derived PP13 may create a ZONE that facilitates trophoblast invasion and conversion of the maternal spiral arterioles.

Placenta-bound and body fluid PP13 and its mRNA in normal pregnancy compared to preeclampsia, HELLP and preterm delivery

OBJECTIVES

To compare the distribution of placental protein 13 (PP13) in fetal and maternal blood and amnionic fluid and to correlate it with PP13 protein and mRNA in the placenta.

METHODS

Umbilical arterial serum, amnionic fluid, maternal venous serum and placental tissues were collected from normal outcome pregnancies (N = 63) (GA>37), early onset preeclampsia (PE) (N = 12, GA: 26-33), and HELLP syndrome (N = 5, GA: 27-29). Because PE and HELLP cases delivered preterm, cases of preterm delivery (PTD) (N = 6, GA: 31-36) served as additional control. PP13 was determined by ELISA, Western blot, and immunohistochemistry. PP13 mRNA was measured by PCR (RT-PCR). Continuous parameters were compared by t-test, P < 0.05 was considered significant.

RESULTS

In women with normal pregnancy outcome significantly higher PP13 levels were found in maternal serum compared to amnionic fluid and negligible amount was found in fetal serum. A similar pattern was identified in cases of PTD with concentrations similar to term control. In PE and HELLP cases PP13 levels in amnionic fluid level were more than twice compared to maternal serum (P < 0.001). Umbilical cord level was negligible in PE but high in HELLP corresponding to the much higher level of PP13 in this patient group compared to all others. In the placenta PP13 level in term controls was higher compared to PTD. In PE and HELLP (similar early delivery time as PTD) the level was significantly higher (P < 0.01) compared to PTD or term controls. PP13 mRNA levels in term control and PTD were similar while PP13 mRNA levels in PE and HELLP placentas were significantly lower compared to term controls or PTD or the two combined. Syncytiotrophoblast labeling appeared stronger in PE and HELLP compared to term controls and PTD.

CONCLUSIONS

In all cases but HELLP, PP13 in fetal blood is very low indicating that routing of PP13 to fetal blood is limited and that the fetus is unlikely to generate PP13. PP13 mRNA is lower in the third trimester at the time of disease while protein level accumulates and become higher creating an unparallel change in the level of the mRNA and the corresponding protein.

Placental and trophoblastic in vitro models to study preventive and therapeutic agents for preeclampsia

In the field of preeclampsia, enormous efforts are ongoing to identify biomarkers predicting the syndrome already in the first trimester of pregnancy. At the same time, there is the need for in vitro models to test such biomarkers prior to their use in clinical trials. In addition, in vitro models may accelerate the development and evaluation of the benefit of any putative therapeutics. Therefore, in vitro systems have been established to evaluate the release of biomarkers and measure the effect of putative therapeutics using placental villous explants as well as the choriocarcinoma cell line BeWo. For explants, a cryogenic method to freeze, transport and thaw villous explants was developed to use such tissues for a multi-site tissue culture evaluation. Here we focus on three out of many in vitro models that have been established for human placental trophoblast. (1) Choriocarcinoma cell lines such as BeWo, Jeg-3 and Jar cells (2) isolated primary trophoblast cells, and (2) villous explants from normal placentas delivered at term. Cell lines were used to assess the effect of differentiation and fusion on the expression and release of a preeclampsia marker (placental protein 13; PP13) and beta-hCG. Moreover, cell lines were used to study the effect of putative preeclampsia therapeutics such as vitamins C and E, heparin and aspirin on marker release and viability. Cryopreservation of villous explants enabled shipment to a remote laboratory and testing of parameters in different countries using explants from one and the same placenta. Recently published data make it tempting to speculate that the choriocarcinoma cell line BeWo as well as fresh and cryogenically stored placental villous explants may well serve as in vitro models to study preventive and therapeutic agents in the field of preeclampsia.

Microarray profiling reveals that placental transcriptomes of early-onset HELLP syndrome and preeclampsia are similar

BACKGROUND

The involvement of the placenta in the pathogenesis of preeclampsia and HELLP syndrome is well established, and placental lesions are also similar in these two syndromes. Here we aimed to examine the placental transcriptome and to identify candidate biomarkers in early-onset preeclampsia and HELLP syndrome.

METHODS

Placental specimens were obtained at C-sections from women with early-onset preeclampsia and HELLP syndrome, and from controls who delivered preterm or at term. After histopathological examination, fresh-frozen placental specimens were used for microarray profiling and validation by qRT-PCR. Differential expression was analysed using log-linear models while adjusting for gestational age. Gene ontology and pathway analyses were used to interpret gene expression changes. Tissue microarrays were constructed from paraffin-embedded placental specimens and immunostained.

RESULTS

Placental gene expression was gestational age-dependent among preterm and term controls. Out of the 350 differentially expressed genes in preeclampsia and 554 genes in HELLP syndrome, 224 genes (including LEP, CGB, LHB, INHA, SIGLEC6, PAPPA2, TREM1, and FLT1) changed in the same direction (elevated or reduced) in both syndromes. Many of these encode proteins that have been implicated as biomarkers for preeclampsia. Enrichment analyses revealed similar biological processes, cellular compartments and biological pathways enriched in early-onset preeclampsia and HELLP syndrome; however, some processes and pathways (e.g., cytokine-cytokine receptor interaction) were over-represented only in HELLP syndrome.

CONCLUSION

High-throughput transcriptional and tissue microarray expression profiling revealed that placental transcriptomes of early-onset preeclampsia and HELLP syndrome largely overlap, underlying a potential common cause and pathophysiologic processes in these syndromes. However, gene expression changes may also suggest a more severe placental pathology and pronounced inflammatory response in HELLP syndrome than in preeclampsia.

Effects of calcium, magnesium, low-dose aspirin and low-molecular-weight heparin on the release of PP13 from placental explants

BACKGROUND

Preeclampsia is one of the leading causes for maternal and fetal morbidity. Attempts to prevent preeclampsia have already been made using low-dose aspirin, low-molecular-weight heparin (LMWH), and calcium supplementation. Magnesium sulphate is used at the time of disease to prevent eclampsia. Here we investigated the effect of these agents on PP13 release from placental explants.

METHODS

Placentas harvested after C-section of term or preterm control and preeclampsia cases or first trimester terminations were used to obtain explants. Explants were incubated for 24h with/without respective agents, harvested, weighed and subjected to PP13 determination in the culture medium and the explant. LDH was used to determine viability. Dose response curves were obtained for each drug. P < 0.05 was considered significant.

RESULTS

Exposure to magnesium (0.7-7g/day) slightly decreased PP13 release from controls, and slightly increased it in preeclampsia and first trimester termination. Calcium (0. 3-6g/day) showed a tendency to decrease the release in control and preeclampsia, whereas in first trimester release was increased in a bell-shaped manner. Aspirin (0-250 mg/day) tended to decrease the release in controls but increased it in a bell-shaped manner in first trimester and preeclampsia. LMWH showed no effect from 0 to 80 mg/day in controls but tended to decrease PP13 release in preeclampsia and first trimester.

CONCLUSION

This data might point to a beneficial effect of aspirin and calcium supplementation in the first trimester of pregnancy and aspirin at the time of disease, although the interaction with the maternal system still needs to be elucidated.

First-trimester markers for the prediction of pre-eclampsia in women with a-priori high risk

OBJECTIVE

To investigate the predictive value of the combination of first-trimester serum placental protein 13 (PP13), uterine artery Doppler pulsatility index (PI) and pulse wave analysis (augmentation index at a heart rate of 75 beats per min (AIx-75)), and to evaluate concurrent and contingent strategies using this combination for assessing the risk of pre-eclampsia in high-risk women.

METHODS

In this nested case-control study, serum PP13, uterine artery mean PI and AIx-75 were measured at between 11 + 0 and 13 + 6 weeks' gestation in women at increased risk of pre-eclampsia. For each case of pre-eclampsia (n = 42), five matched controls were randomly selected from the study group. Gestation specific multiples of the median (MoMs) were adjusted for body mass index, ethnicity, smoking, age and parity. MoMs were compared between cases and controls using the Wilcoxon rank sum test. Sensitivities and specificities were derived from receiver-operating characteristics curves.

RESULTS

Compared with controls, women who developed pre-eclampsia had lower PP13, higher uterine artery mean PI and higher AIx-75 (P < 0.001). For a 10% false-positive rate, the best detection rate for pre-eclampsia (85.7% (95% CI, 71.5-94.6%)) and pre-eclampsia requiring delivery before 34 weeks (92.9% (95% CI, 66.1-99.8%)) was achieved by concurrent testing with all three markers. The best contingency screening sequences for pre-eclampsia were (AIx-75 --> PP13 --> mean PI) and (PP13 --> AIx-75 --> mean PI), with an 86% detection rate for false-positive rates of 9 and 10%, respectively. These two sequences would require 410 and 414 tests, respectively, compared with 756 tests in concurrent testing.

CONCLUSION

Combination of first-trimester PP13, uterine artery mean PI and pulse-wave analysis is promising for the prediction of pre-eclampsia in women at increased a-priori risk and may be useful in clinical practice. Contingency screening achieved similar detection rates to concurrent testing, but required almost 50% fewer tests, making it a more cost-effective option.

IFPA meeting 2008 workshops report

Workshops are an important part of the IFPA annual meeting. At the IFPA meeting 2008 diverse topics were discussed in 12 themed workshops. Topics covered included: immunology of placentation; galectins and trophoblast invasion; signaling in implantation and invasion; markers to identify trophoblast subpopulations; placental pathology; placental toxicology; stereology; placental transport of fatty acids; placental mesenchymal stem cells; comparative placentation; trophoblast and neoplasia; trophoblast differentiation. This report is a summary of the various topics covered.

First-trimester maternal serum PP-13, PAPP-A and second-trimester uterine artery Doppler pulsatility index as markers of pre-eclampsia

OBJECTIVE

To evaluate whether measurement of maternal serum placental protein-13 (PP-13) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks of gestation alone or in combination with second-trimester uterine artery pulsitility measured by Doppler velocimetry is useful in predicting those women who will develop pre-eclampsia

METHODS

This was a nested case-control study of pre-eclampsia cases with controls matched for gestational age and storage time for the maternal serum. Samples were collected as part of a first-trimester prenatal chromosomal anomaly screening program and were routinely tested for PAPP-A. PP-13 was tested using an enzyme linked immunosorbent assay (ELISA) by an examiner who was blinded to pregnancy outcome. All patients also underwent uterine artery Doppler flow velocimetry to measure the mean pulsatility index (PI) at 22-24 weeks' gestation.

RESULTS

There were 446 controls and 44 cases with early pre-eclampsia where delivery was induced prior to 35 weeks. In addition there were a further 44 cases with pre-eclampsia in which delivery was not induced before term. Median PP-13 levels for controls, all cases and early pre-eclampsia cases were 176.9, 121.9 and 111.7 pg/mL, with multiples of the median (MoMs) of 1.00, 0.69 and 0.63, respectively (P < 0.001). PAPP-A MoMs were 1.00, 0.89 (P = 0.076) and 0.89 (P = 0.042) and mean PIs were 1.0, 1.6 (P < 0.001) and 1.7 (P < 0.001) for controls, all cases and early cases, respectively. Receiver-operating characteristics (ROC) curve analysis for either all cases or early cases vs. controls yielded areas under the curve for PP-13, PAPP-A and PI respectively of 0.68 (95% CI, 0.61-0.74; P < 0.001), 0.56 (95% CI, 0.49-0.63; P = 0.076) and 0.79 (95% CI, 0.72-0.87; P < 0.001) for all cases and 0.71 (95% CI, 0.63-0.79; P < 0.001), 0.59 (95% CI, 0.51-0.68; P = 0.076) and 0.86 (95% CI, 0.77-0.94; P < 0.001) for early cases. At a specificity set to 0.80 the sensitivities were 0.50, 0.23 and 0.76 for PP-13, PAPP-A and PI in the early cases and 0.44, 0.24 and 0.73 in all cases. Combining PP-13 and PI using logistic regression analysis yielded an area under the curve of 0.84 (95% CI, 0.78-0.90; P < 0.001) and a sensitivity of 0.74 in all cases, and 0.90 (95% CI, 0.84-0.96; P < 0.001) and a sensitivity of 0.79 for early cases. PAPP-A with PI gave an area under the curve of 0.82 (95% CI, 0.76-0.90; P < 0.001) and a sensitivity of 0.76 in all cases. Combining PAPP-A with PP-13 and PI did not add significantly to the sensitivity.

CONCLUSION

First-trimester PP-13 levels may be useful in predicting pre-eclampsia and early pre-eclampsia, and the accuracy of the method increases when coupled with second-trimester Doppler PI measurement. First-trimester PAPP-A provides some prediction for pre-eclamspia when combined with PI but does not add to the prediction of early pre-eclampsia when PP-13 and PI are used together. Further studies are required to establish the real value of PP-13 in first-trimester screening for pre-eclampsia.

A novel approach to first-trimester screening for early pre-eclampsia combining serum PP-13 and Doppler ultrasound

OBJECTIVE

To investigate the value of maternal serum placental protein 13 (PP-13) measurement and uterine artery Doppler during first-trimester screening in the prediction of early pre-eclampsia.

METHODS

This was a nested case-control prospective study of pregnancies at 11 + 0 to 13 + 6 weeks of gestation. The pulsatility index (PI) of blood flow in the uterine arteries and the maternal serum concentration of PP-13 were measured in 10 women who went on to develop pre-eclampsia that necessitated delivery before 34 weeks, and in 423 unaffected women. Results were expressed as multiples of the gestation-specific median in controls (MoM). A logistic regression model was used to predict detection and false-positive rates.

RESULTS

In the cases that developed pre-eclampsia requiring delivery before 34 weeks, compared with the unaffected pregnancies, the median uterine artery PI was higher (1.43 MoM) and the median serum PP-13 level was lower (0.07 MoM; P < 0.001, Wilcoxon rank sum test for both). Modeling predicted that for a 90% detection rate of pre-eclampsia requiring delivery before 34 weeks, the false-positive rate of screening by PP-13 was 12%, by uterine artery PI was 31% and by a combination of the two methods was 9%. A policy of contingency screening, whereby all women are screened by maternal serum PP-13 and only the 14% at highest risk are then screened by Doppler, achieved a detection rate of 90% with an overall false-positive rate of 6%.

CONCLUSION

Effective screening for pre-eclampsia requiring delivery before 34 weeks can potentially be provided by assessment of a combination of maternal serum PP-13 and uterine artery Doppler in the first trimester of pregnancy.

Placental protein 13 (PP-13): effects on cultured trophoblasts, and its detection in human body fluids in normal and pathological pregnancies

Placental tissue protein 13 (PP-13), one of the 56 known placental proteins identified till today, was purified from placentas obtained from women at delivery, and used to evoke antibodies against it. The purified PP-13 was lysed to peptides, which were sequenced, leading to the full-length cDNA sequencing and its expression in Escherichia coli. Sequence analysis in databases showed homology to the galectin family. Of the various antibody preparations developed, a pair of monoclonal antibodies (MAbs) coupled to the recombinant PP-13 (PP-13-R) was used for the immunodetection of PP-13 in pregnant women's serum with the solid-phase ELISA format. With a dynamic range of 25-500 pg/mL with no background in non-pregnant women's serum and men's serum, the ELISA test was suitable for the detection of PP-13 in the 1st, 2nd, and 3rd trimesters. PP-13 levels slowly increase during pregnancy. In the 1st trimester, lower than normal PP-13 levels were found in fetal growth restriction (IUGR), preeclampsia (PE), and particularly in early PE (<34 weeks of gestation). In the 2nd and 3rd trimesters, higher than normal concentrations were found in PE, IUGR and in preterm delivery (PTD). Application of PP-13 to cultured trophoblasts elicited depolarization carried by calcium ions, followed by liberation of linoleic and arachidonic acids from the trophoblast membrane, and a subsequent elevation of prostacyclin and thromboxane. These effects were negligible when PP-13 derived from the placentas of patients with IUGR, PE or PTD was used. The results are discussed in view of the potential utilization of PP-13 for early serum screening to assess the risk to develop placental insufficiency, coupled to a differential analysis of the various pathologies by analyzing cultured trophoblasts.

Calcitriol therapy modulates the cellular immune responses in hemodialysis patients

We studied the in vitro and in vivo effects of calcitriol (1,25D) on the cellular immune responses in 19 hemodialysis (HD) patients. In vitro 5-day treatment with 1,25D markedly reduced the HLA-DR expression by peripheral blood CD14(+) monocytes from both HD patients and normal subjects in a similar fashion. The HLA-DR expression by monocytes and the phorbol myristate acetate (PMA)-induced superoxide production (SOP) by neutrophils were significantly higher in the HD patients than in the normal subjects (p < 0.01 and p < 0.05, respectively). The phagocytic activity in the HD patients was significantly lower than that in the normal subjects (p < 0.05). Moreover, the mitogen response of HD peripheral blood lymphocytes against pokeweed mitogen (PWM) was significantly lower than that of the controls (p < 0.01) but was only slightly and insignificantly lower against Con A. Oral 1,25D pulse therapy resulted in a marked decrease in the HLA-DR expression by peripheral blood monocytes 2 and 4 days after the first 1,25D administration (p < 0.01) in HD patients. Moreover, the treatment significantly enhanced the PMA-induced SOP 2 days after the treatment (p < 0.01). However, the phagocytic activity by neutrophils and the mitogen responses to Con A and PWM by lymphocytes were not significantly affected by this treatment. These results suggest that 1,25D plays a significant role in the regulation of both the monocyte and neutrophil functions in HD patients.

Rhythmic opening and closing of vesicles during constitutive exo- and endocytosis in chromaffin cells

Constitutive exo- and endocytic events are expected to increase and diminish the cell surface area in small spontaneous steps. Indeed, cell-attached patch-clamp measurements in resting chromaffin cells revealed spontaneous upward and downward steps in the electrical capacitance of the plasma membrane. The most frequent step size indicated cell surface changes of <0.04 microm(2), corresponding to vesicles of <110 nm diameter. Often downward steps followed upward steps within seconds, and vice versa, as if vesicles transiently opened and closed their lumen to the external space. Transient openings and closings sometimes alternated rhythmically for tens of seconds. The kinase inhibitor staurosporine dramatically increased the occurrence of such rhythmic episodes by making vesicle closure incomplete and by inhibiting fission. Staurosporine also promoted transient closures of large endocytic vesicles possibly representing remnants of secretory granules. We suggest that staurosporine blocks a late step in the endocytosis of both small and large vesicles, and that endocytosis involves a reaction cascade that can act as a chemical oscillator.

[The management selection of renal angiomyolipoma]

BACKGROUND

Nephron-sparing surgery is ideal in the treatment of renal angiomyolipoma (AML). But, in fact, occasional cases are found in post-ruptured AML and/or in bilateral multiple AMLs, that is seen in tuberous sclerosis. And we cannot perform nephron sparing surgery so easily. We proposed the treatment selection in such complicated AML.

METHODS

We experienced 10 cases (12 kidneys) for about ten years, and studied our treatment selection and prognosis on each cases retrospectively.

RESULTS

Of the 5 kidneys with AML less than 4 cm in diameter, 4 have not encountered with rupture. Of the 7 kidneys with AML more than 4 cm in diameter, 4 kidneys had rupture. Of the 3 kidneys unruptured AML more than 4 cm in diameter, 2 kidneys were treated by enucleation and we performed preventive embolization for rupture in residual one kidney. The patients was suffered from tuberculosis sclerosis, and she had bilateral multiple AMLs. Of the 4 kidneys with ruptured AML, 2 kidneys were treated by enucleation, and the other 2 kidneys were entirely resected. We succeeded enucleation in 2 of 4 kidneys with ruptured complicated AML. In those cases, we did long term watching after rupture and in-situ perfusion technique at the operation.

CONCLUSIONS

Active treatment of AML, that is more than 4 cm in diameter, might be recommended. Because most of those will be ruptured. The ideal treatment, nephron-sparing surgery is difficult in complicated situation, such as after rupture and bilateral multiple AMLs. In our opinion, the point of success of nephron-sparing surgery might be long term watching after rupture and in-situ perfusion technique at the operation.

The difference in shape of spontaneous and uniquantal evoked synaptic potentials in frog muscle

1. Spontaneous and stimulation-induced uniquantal synaptic activity at the frog cutaneous pectoris muscle, treated with neostigmine, was recorded by focal extracellular microelectrodes. A monoexponential curve was fitted to the decay of each synaptic response. 2. A highly significant positive relationship was found between the amplitude and the decay time constant of spontaneous extracellular miniature endplate potentials (MEPPs(o)), whereas the relationship displayed by evoked uniquantal extracellular endplate potentials (EPPs(o)) was only slightly greater than zero. 3. The difference did not stem from changes in the muscle membrane conductance or from inclusion of outstanding MEPPs(o) formed as a result of the block of acetylcholinesterase. 4. The dependence of the rise time on the amplitude was also stronger in MEPPs(o) than in EPPs(o). 5. In the absence of neostigmine, MEPPs(o) exhibited a positive correlation between decay time constant and amplitude, while EPPs(o) did not show such a correlation. 6. In view of previously published models of transmitter release, it is suggested that spontaneous secretion of quanta occurs both within and outside the active zones facing postsynaptic areas of variable receptor density.

Resonant behavior and frequency preferences of thalamic neurons

1. We studied the voltage responses of thalamocortical neurons to a periodic current input of variable frequency, in slices of mediodorsal thalamus (guinea pig). The ratio of the Fourier transform of the voltage response to the Fourier transform of the oscillatory current input was used to calculate the frequency response of the neurons at different resting and imposed membrane potentials. 2. Most neurons displayed a resonant hump in the frequency response curve. A narrow band of low-frequency (2-4 Hz) resonance occurred near the resting level [-66 +/- 8 mV (SD)] and at imposed membrane potentials in a range of -60 to -80 mV. An additional wide band (12-26 Hz) of peak resonant frequencies was observed at depolarized levels. 3. The low-frequency resonance was insensitive to tetrodotoxin (TTX) application in concentrations (0.5-1 microM) that blocked a depolarization activated inward rectifier and Na(+)-dependent action potentials. TTX, however, eliminated the wide-band resonant hump centered at 12-26 Hz that we observed at depolarized membrane potentials. 4. Application of Ni2+ (0.5-1 mM) reversibly blocked all slow spikes and greatly reduced the low-frequency resonant humps, without changing the resting potential. Octanol in concentrations of 50 microM had similar effects. 5. Application of Cs+ (3-5 mM), a blocker of the hyperpolarization activated inward rectifier, produced a 5- to 10-mV depolarization and completely blocked the rectification. Cs+ did not alter the low-frequency resonant hump or its dependence on membrane voltage.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of different S4 parts in the voltage dependency of Na channel gating

Three synthetic peptides corresponding to parts of S4 of the first repeat of eel electroplax sodium channel were synthesized. The basic peptide was C1+ which corresponds to amino acids 210-223 (eel channel numbering) and two subfractions: an external fraction, C1+ex (amino acid 210-217); and an internal part, C1+in (amino acid 218-221). Peptide C1+ includes four of the charged amino acids of this domain; peptide C1+ex includes three of the charged amino acids and is closer to the external membrane surface (according to channel models) than peptide C1+in which includes the fourth charged amino acid alone. Antibodies generated in rabbits against these peptides were shown to be site specific. Using the whole-cell patch-clamp technique, we found that in rat dorsal root ganglion (DRG) cells, the antibodies against C1+in but not against C1+ex had an effect on the gating parameters. They shifted the Na-channel inactivation curve towards hyperpolarization and decreased the slope of the Na-channel activation curve. These results demonstrate that during the conformational changes associated with channel gating, the fourth charged amino acid of S4 must be accessible to antibodies given to the external solution. Furthermore, they indicate a specific involvement of S4 in the voltage dependency of the gating processes.

Aluminium modifies the electrical response of neuroblastoma cells to a short hypertonic pulse

The effect of aluminium (50-100 micrograms/ml) on the electrical response of N1E-115 neuroblastoma cells to a short hypertonic pulse was examined using conventional electrophysiological techniques and computer assisted analysis. Application of a small dose of hypertonic solution in the vicinity of the cell evoked depolarization of the membrane potential and a biphasic change in input resistance: an initial increase followed by a profound decrease. Upon washout of the hypertonic stimulus, repolarization of membrane potential and complete recovery of the input resistance were observed. In the presence of aluminium application of hypertonic solution had a reversible effect which showed a prolonged duration of the response without a change in its amplitude. It is suggested that the retardation in recovery from hypertonically induced shock may be due to rigidification of the plasma membrane in the presence of aluminium. Possible implications to human diseases associated with accumulation of aluminium in brain tissue are discussed.

Depolarization exposes the voltage sensor of the sodium channels to the extracellular region

Two domains of Na channels were mapped with site-specific antibodies raised in rabbit against synthetic peptides corresponding to a part of the voltage sensor of internal repeat 1-C1+ (amino acids 210-223) and to a region designated dipole (amino acids 1690-1699) of eel electroplax sodium channels. The antibodies bind to their respective domains in both purified and membrane-bound channels and immunoprecipitate the channels from eel electroplax and rat brain synaptosomes. Anti-C1+ depresses the action potential of rat sciatic nerve in a concentration-dependent way. It binds to the external side of rat brain synaptosomal vesicle, and its binding is potentiated by depolarization. Anti-dipole binds to the inner side of the vesicle, and the binding is inhibited by depolarization.

Postsynaptic effects of DMSO at the frog neuromuscular junction

Postsynaptic effects of dimethylsulfoxide (DMSO) were studied at the frog cutaneous pectoris neuromuscular junction using electrophysiological techniques and computer assisted analysis. It was found that the average amplitude of extracellularly recorded miniature end-plate potentials (meppse) as well as the time constant of their monoexponential decay (tau) were both elevated in the presence of DMSO. In spite of increased scatter of individual values, amplitude and tau of meppse highly correlated with each other. These results imply that DMSO partially blocked the activity of acetylcholine esterase in addition to its already known presynaptic action of acetylcholine release enhancement. Inhibitory action of DMSO on activity of isolated acetylcholine esterase was previously demonstrated by biochemical methods.

Protein phosphatase inhibitor okadaic acid enhances transmitter release at neuromuscular junctions

To test the hypothesis that continual phosphorylation and dephosphorylation of protein components of nerve terminals might be important determinants of synaptic efficacy, the effect of okadaic acid, a potent natural inhibitor of two serine threonine protein phosphatases (phosphatase 1 and phosphatase 2A), was examined on synaptic transmission at frog (cholinergic) and lobster (glutamatergic and GABAergic) neuromuscular junctions. At frog junctions, the addition of 1 microM okadaic acid to the extracellular fluid caused almost a doubling of the amplitude of the end-plate potential. The effect of okadaic acid was reversible. Quantal analysis showed that the augmenting effect was presynaptic, resulting from an increase in the number of quanta of transmitter released by a nerve impulse. Where was no significant change in the amplitude of spontaneously liberated miniature end-plate potentials, but their frequency of release increased in parallel with the increase in amplitude of the nerve-evoked synaptic potential. Similar studies with lobster neuromuscular junctions showed increases in the size of both excitatory and inhibitory synaptic responses that were similar in magnitude to the effects seen in the frog junctions. No significant changes in membrane potential or in input resistance accompanied the increased response size. These results suggest that transmitter release at a variety of junctions using different transmitters is constantly modulated by phosphorylation and dephosphorylation of important protein components within nerve terminals.

Effects of aluminium on electrical and mechanical properties of frog atrial muscle

1. The effects of aluminium on membrane ionic currents were studied in single cardiac myocytes. Most of the work was done on frog atrial cells, but some experiments were also carried out on single cells isolated from rabbit ventricles and atria. 2. The effects of aluminium on the force of contraction of frog atrial trabeculae were also investigated. 3. Aluminium was prepared from AlCl3 as a stock 0.5 M solution which has a pH of 3.5. Before each experiment, this solution was added to the control solution, to give a final concentration of 20-100 micrograms ml-1 aluminium (0.75-3.75 mM AlCl3). The solutions were brought to a pH of 7.4 or 7.6. at which they consist of a mixture of amorphous aluminium hydroxides and a very small amount of soluble ionic aluminium complexes: free aluminium cations (less than 10 pM), aluminohydroxide anions (less than 8 microM). The addition of this suspension reduced the peak inward calcium currents in single rabbit atrial and ventricular cells and in frog atrial cells. In the latter, the peak current was reduced (at + 10 mV) to 45% of control (mean of 9 cells). This effect was reversible upon washout, and was obtained at all membrane potentials, with no shift of the calcium current voltage relationship along the voltage axis. 4. Aluminium also reduced the time-dependent potassium current IK. This reduction was observed at all membrane potentials. For example, at + 10 mV, the mean reduction of IK (n = 9) was to 69% of the control amplitude. This effect, which was very difficult to reverse, was not due to IK rundown. The fully activated current-voltage relationships (obtained by standard 'tail' analysis) showed that the effect of aluminium was due mainly to a decrease in conductance and not to a shift in the activation range of IK. The mean voltage of half activation was shifted by 8 mV in the depolarizing direction (n = 5). 5. The background potassium current IK1 was also slightly but consistently changed in a complex fashion, with an outward shift at membrane potentials positive to -60 mV. For example, at a membrane potential of -40mV, the mean shift was by 22 + 4pA. At more negative potentials, there was an inward shift in the current amplitudes. For example, for steps to -I00 mV the current elicited was larger (more inward) by 53 pA (mean value, n = 10). The reversal potential was slightly shifted (<10 mV) in the hyperpolarizing direction. 6. The force of contraction of frog atrial trabeculae was altered by aluminium in a complex manner, which showed marked seasonal variation. During most of the year, 50-100,ug ml-1 aluminium caused a biphasic change, with an early small and consistent decrease, followed by a large increase in twitch amplitude. For a short period corresponding to the (local) winter months the sensitivity to aluminium was greatly enhanced. Aluminium lOOupgml-1 totally abolished contraction (n = 5), while a lower concentration (20,ug ml- 1) produced a sustained reduction in the force of contraction. Similar biphasic and seasonal responses have been reported to be induced by lanthanum. 7. The biphasic changes in twitch amplitude were independent of the transmembrane sodium gradient. Aluminium produced the same effects when 90% of the extracellular sodium was replaced by lithium. Caffeine (5 mM) attenuated or even inverted the positive inotropic effect of aluminium. These results imply that aluminium alters the release of calcium from intracellular, caffeine-sensitive stores. This could be effected either by augmenting the amount released during each activation, and/or by increasing the loading of stores prior to release.

Colchicine prevents recovery of nerve conduction at chronic demyelination

A colchicine cuff was applied to rat sciatic nerve proximal to a demyelinating region produced by a focal injection of lysophosphatidylcholine (LPC). The colchicine cuff prevented the recovery of function normally seen within 6-8 days after LPC-induced demyelination. Colchicine blocked the delivery of sodium channels to the demyelinated region and induced their accumulation proximal to the cuff. The dual effect of colchicine in blocking both the recovery of impulse propagation through the demyelinated region and the delivery of sodium channels suggests a central role for fast axonal transport of sodium channels in the recovery of function at demyelination.

Structural and developmental differences between three types of Na channels in dorsal root ganglion cells of newborn rats

The changes in Na current during development were studied in the dorsal root ganglion (DRG) cells using the whole-cell patch-clamp technique. Cells obtained from rats 1-3 and 5-8 days after birth were cultured and their Na currents were compared. On top of the two types of Na currents reported in these cells (fast-FA current and slow-S current) a new fast current was found (FN). The main characteristics of the three currents are: (i) The voltages of activation are -37, -36 and -23 mV for the FN, FA and S currents, respectively. (ii) The activation and inactivation kinetics of FN and FA currents are about five times faster than those of the S current. (iii) The voltages at which inactivation reaches 50% are -139, -75 and -23 mV for the FN, FA and S currents, respectively. The kinetics and voltage-dependent parameters of the three currents and their density do not change during the first eight days after birth. However, their relative frequency in the cells changes. In the 1-3 day-old rats the percent of cells with S, FA, and mixed S + FN currents is 22, 18, and 60% of the cells, respectively. In the 5-8 day-old, the percent of cells with S, FA, and FN + S is 10, 66 and 22%. The relative increase in the frequency of cells with FA current during development can contribute to the ease of action potential generation compared with cells with FN currents, which are almost completely inactivated under physiological conditions. The predominance of FA cells also results in a significant decrease in the relative frequency of cells with the high-threshold, slow current. Antibodies directed against a part of the S4 region of internal repeat I of the sodium channel (C1+, amino acids 210-223, eel channel numbering) were found to shift the voltage dependence of FA current inactivation (but not of FN or S currents) to more negative potentials. The effect was found only when the antibodies were applied externally. The results suggest that FN, FA and S types of Na currents are generated by channels, which are different in the topography of the C1+ region in the membrane.

Vasopressin produces long-lasting increase in transmitter release

Arginine-vasopressin has a widespread distribution in the nervous system, and has been implicated in cellular and behavioral functions. Its effect on the neuromuscular synapse reveals that it produces long-lasting augmentation in synaptic transmission due to an increase in spontaneous and nerve stimulation evoked quantal transmitter release. No significant postsynaptic effect was detected.

Acetylcholine release at identified nerve terminals in the organ-cultured frog neuromuscular preparation

1. The frog cutaneous pectoris neuromuscular preparation was maintained in organ culture for a few days, at either 24 or 14 degrees C. The synaptic activity of identified nerve terminals was repeatedly examined in order to describe the sequence and time course of changes from normal synaptic activity to a complete synaptic silence. 2. We found that the 'transient stage' (stage II, according to Ko, 1981) consists of at least three distinct periods each characterized by a unique trend of change in synaptic activity. The initial change involved a simultaneous decay of both spontaneous and nerve stimulation-evoked release of acetylcholine (sub-stage II1). Subsequently, the frequency of spontaneous miniature endplate potentials (MEPPs) increased gradually, while the evoked release continued its monotonous decay (sub-stage II2). During the third sub-stage spontaneous MEPPs, but no evoked endplate potentials (EPPs), were observed (sub-stage II3). 3. Statistical properties of acetylcholine release in still-transmitting junctions at sub-stage II2 and in non-transmitting junctions at sub-stage II3 were investigated. MEPPs with skewed amplitude histograms and bursting behaviour were evident at both sub-stages. However, the incidence and the extent of these distortions were higher in the non-transmitting junctions. 4. An inverse relation between the quantal content of evoked release and the rate of spontaneous secretion was found in the transmitting junctions. 5. These results suggest that some of the deterioration of synaptic activity in organ culture is caused by an impairment of the release process itself. Possible cellular mechanisms are discussed.

Characterization of sodium currents in mammalian sensory neurons cultured in serum-free defined medium with and without nerve growth factor

The influence of nerve growth factor (NGF) on Na currents of rat dorsal root ganglia (DRG) was studied in neurons obtained from newborns and cultured for 2-30 hr in serum-free defined medium (SFM). Cell survival for the period studied was 78-87% both with and without NGF. Na currents were detected in all cells cultured for 6-9 hr. They were also detected after 2 hr in culture in 21.5% of the cells cultured without NGF (-NGF cells), and in 91.5% of the cells cultured with NGF (+NGF cells). Current density of the -NGF cells was 2.3 and 2 pA/microns 2 after growth for 2 and 6-9 hr, respectively, compared to 3.0 and 3.9 pA/microns 2 for the +NGF cells. The +NGF cells were separated into fast (F), Intermediate (I) and slow (S) cells, based on the Na current they expressed, while -NGF cells were all of the I type. F, I and S currents differed in their voltage-dependent inactivation (Vh50 = -79, -28 and -20 mV), kinetics of inactivation (tau h = 0.55, 1.3 and 7.75 msec), and TTX sensitivity (Ki = 60, 550 and 1100 nM). All currents were depressed by [Ca]0 with a KdCa of 22, 17 and 8 mM for F, I and S currents, respectively. Current density of F and S currents was 5.5 and 5 pA/micron 2 for the I current. The concentration-dependent curve of I current vs. TTX indicated that I current has two sites: one with F-like and another with S-like Ki for TTX. Hybridization of F and S currents yielded I-like currents. Thus, the major effect of NGF on Na currents in SFM is the acceleration of Na current acquisition and diversity, reflected in an increase of either the S or F type in a cell.

Toxic effects of alumino-silicates on nerve cells

The recently reported presence of alumino-silicates in the core of Alzheimer's senile plaques raises a number of questions concerning the little studied area of interactions between solid particles and neuronal tissue. In this preliminary study we report that contact between crystalline alumino-silicates and cultured neuroblastoma cells selectively caused a rapid increase in membrane electrical conductance and loss of excitable activity. Severe morphological deterioration was subsequently evident within 30 min of exposure. Similar effects were induced by a magnesium silicate mineral but not by aluminum hydroxides or by silicon in the form of quartz. Homogeneously charged synthetic particles did not induce changes in electrical function of the cells. These results suggest that a layout incorporating both negative and positive charges, as can be found on the broken edges of platy clay metallo-silicates, and the non-isodiametrical geometry of the particles may be necessary for the acute neurotoxic interaction observed.

Modification of the Na-dependent action potential in myelinated fibers of rat sciatic nerve exposed to phorbol ester

Exposure of rat sciatic nerve to the active phorbol 1,2-beta-myristate-13-acetate (b-PMA), but not to the active analogue 4-alpha-phorbol-12,13-didecanoate (a-PDD), is followed by a decrease of the compound action potential amplitude, rate of rise, and conduction velocity, and an increase of the threshold, and of the duration of the refractory period. The effect is concentration-dependent, the Kd being 250 nM. The attenuated Na-dependent action potential is tetrodotoxin (TTX)-sensitive, but after exposure to b-PMA the sensitivity to TTX is decreased from Kd = 45 nM to 400 nM. Action potential depression is larger when Ca is replaced by Mg (but not by Ba), or when Na is replaced by Li. The replacement of K by Cs, or exposure to potassium channel blockers such as 4-aminopyridine (4AP) and tetra-ethyl ammonium (TEA) has no effect. The results indicate that in the myelinated axons of rat sciatic nerve, exposure to b-PMA induces modification of Na channels.

Differentiated neuroblastoma cells are more susceptible to aluminium toxicity than developing cells

The influence of aluminium (20-50 micrograms/ml) on neuronal function was examined using electrophysiological techniques and neuroblastoma clone cells which offer a convenient model of differentiating and fully active neurons. Two specific questions were addressed: 1) Can differentiated cells maintain their normal excitable function when exposed to aluminium? 2) Can proper development of electrophysiological properties be achieved in its presence? We report that aluminium caused premature onset of deterioration in fully differentiated cells. Within 4-6 days they depolarized from -29.3 +/- 0.9 mV to levels lower than -15 mV; compound polyphasic action potentials were gradually replaced by slow monophasic spikes before the final loss of excitable properties and structural deformations was noticed. Developing cells followed the normal pattern of differentiation in the presence of aluminium: within 7 days they extended neurites, hyperpolarized and exhibited polyphasic spikes. These results show that neuroblastoma cells are apparently less susceptible to aluminium's toxicity during the process of development than after differentiation. Possible mechanisms by which aluminium may exert its effects are discussed in view of these observations.

The specific binding of [3H]EO-122, a radiolabeled class I antiarrhythmic drug to rat heart membranes

[3H]EO-122, a radiolabeled class I antiarrhythmic drug, has been used to characterize a new specific binding system to rat heart membranes. The binding is saturable and competitive with unlabeled EO-122 and other antiarrhythmic drugs. In this system, [3H]EO-122 binds to two sites. Site A with an apparent Kd of 33.5 +/- 1.5 nM, Bmax of 1.05 +/- 0.15 pmol/mg protein and Hill coefficient nH = 4. Site B with an apparent Kd of 233 +/- 25 nM, Bmax equals 5.7 +/- 0.61 pmol/mg proteins and nH = 6. The binding to site B indicates that this site is pharmacologically relevant to known class IA antiarrhythmic drugs such as quinidine and procainamide. Lidocaine (class IB) does not interact with this site. Interpretation of the high Hill coefficient suggests that the binding of an antiarrhythmic drug to its pharmacologically relevant binding site exposes additional binding sites and/or modulates the affinity of adjacent binding sites.

Impaired control of information transfer at an isolated synapse treated by aluminum: is it related to dementia?

Information transfer across an isolated cholinergic synapse exposed to aluminum was investigated using conventional electrophysiological techniques and computer-assisted analysis. Spontaneous and stimulation-induced release of neurotransmitter from frog motor nerve endings was augmented in the presence of aluminum (6-200 micrograms/ml). The release-enhancing effect of aluminum was dose-dependent and it was independent of the concentration of calcium ions in the extracellular solution. These results indicate that aluminum at concentrations similar to those found in the diseased brain of demented patients modulates synaptic transmission.

Mapping a region associated with Na channel inactivation using antibodies to a synthetic peptide corresponding to a part of the channel

Antibodies to the synthetic peptide (carrier-coupled) corresponding to amino acids 210-223 of the primary sequence of eel Na channel (C1+ peptide) were generated. The antipeptide antibodies were used to identify functional roles as well as the accessibility from the external membrane surface of the C1+ domains. Rabbit antipeptide antibodies bound specifically to the C1+ synthetic peptide and to an eel membrane fraction bearing a high density of Na channels. When applied to the external surface of cultured dorsal root ganglion cells obtained from newborn rats, the antibodies modify Na channel inactivation by shifting the steady-state Na current-inactivation parameter, h infinity, curve to more negative potentials in fast and slow Na currents. The rate of inactivation of the slow channel is shown to be increased. The antibodies do not have a significant effect on activation of the channels. Part of the amino acid sequence corresponding to C1+ peptide is therefore accessible, in the mammalian Na channel, from the external membrane surface and is associated with the inactivation gate.

Developmental changes in the response of cardiac Purkinje fibers to SC-72-14

We used standard microelectrode techniques to study the effects of SC-72-14, a monoclonal antibody to eel electroplax, and tetrodotoxin (TTX) on the electrophysiological properties of neonatal and adult canine Purkinje fibers. SC-72-14, 7 ng/ml, depressed maximum upstroke potential (Vmax) and membrane responsiveness of adult but not neonatal fibers. In contrast, we previously had shown TTX to have a greater effect on neonatal than adult fibers (29). Even in the presence of SC-72-14, TTX continued to have a greater effect on the neonatal fibers. The effects of TTX and SC-72-14 were cumulative over the concentration range studied, and our results are consistent with their acting at different sites.