Laparoscopic appendectomy and cholecystectomy versus open: a study in 1999 pregnant patients.

BACKGROUND: When pregnant patients require surgery, whether to perform an operation open or laparoscopic is often debated. We evaluated the impact of laparoscopy for common general surgical problems in pregnancy to determine safety and trends in operative approach over time. METHODS: Pregnant patients undergoing appendectomy or cholecystectomy were identified using the National Surgical Quality Improvement Program (NSQIP) database. We analyzed demographics, operative characteristics, and outcomes. Univariate comparison and multivariate regression analysis (MVA) were performed adjusting for confounding factors: age, body mass index (BMI), diabetes, and smoking, and an additional MVA was performed for perforated cases. RESULTS: A total of 1999 pregnant patients between 2005 and 2012 were evaluated. Of 1335 appendectomies, 894 were performed laparoscopically (LA) and 441 open (OA). For 664 cholecystectomies, 606 were laparoscopic (LC) and 58 open (OC). There were no deaths. For LA versus OA, patient characteristics were not different {age: 27.7 vs. 28.2 years, p = 0.19; diabetes: 1.8 vs. 0.9%, p = 0.24; smoking: 19 vs. 16.1%, p = 0.2} except for BMI (27.9 vs. 28.4 kg/m(2); p = 0.03). LA had shorter operative times (ORT), length of stay (LOS), and fewer postoperative complications compared to OA. In MVA, difference between approaches remained statistically significant for ORT (<0.0001), LOS (<0.01), and wound complications (<0.01). MVA was performed for perforated cases alone: LA had equal ORT (p = 0.19) yet shorter LOS (p = <0.001). The majority of LA were performed in the last 4 years versus the first 4 years (61 vs. 39%, p < 0.001). For LC versus OC, patient characteristics were not different: age (28.3 vs. 28.7 years; p = 0.33), BMI (31.4 vs. 33.2 kg/m(2), p = 0.25), diabetes (2.8 vs. 3.5%, p = 0.68), and smoking (21.1 vs. 25.9%, p = 0.4). LC had a shorter ORT, LOS, and fewer postoperative complications than OC. In MVA, the difference between approaches remained statistically significant for ORT (<0.0001), LOS (<0.0001), and minor complications (<0.01). In MVA for cholecystitis with perforation, no difference was seen for LOS, ORT, or postoperative complications (p > 0.05). The percentage of LC cases appeared to increase over time (89 vs. 93%, p = 0.06). CONCLUSION: While fetal events are unknown, LA and LC in pregnant patients demonstrated shorter ORT, LOS, and reduced complications and were performed more frequently over time. Even in perforated cases, laparoscopy appears safe in pregnant patients.

Risk factors for postoperative sepsis in laparoscopic gastric bypass.

INTRODUCTION: Postoperative sepsis is a rare but serious complication following elective surgery. The purpose of this study was to identify the rate of postoperative sepsis following elective laparoscopic gastric bypass (LGBP) and to identify patients' modifiable, preoperative risk factors. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was queried from 2005 to 2013 for factors associated with the development of postoperative sepsis following elective LGBP. Patients who developed sepsis were compared to those who did not. Results were analyzed using the Chi-square test for categorical variables and Wilcoxon two-sample test for continuous variables. A multivariate logistic regression analysis was utilized to calculate adjusted odds ratios for factors contributing to sepsis. RESULTS: During the study period, 66,838 patients underwent LGBP. Of those, 546 patients developed postoperative sepsis (0.82%). The development of sepsis was associated with increased operative time (161 ± 77.8 vs. 135.10 ± 56.5 min; p < 0.0001) and a greater number of preoperative comorbidities, including diabetes (39.6 vs. 30.6%; p < 0.0001), hypertension requiring medication (65.2 vs. 54%; p < 0.0001), current tobacco use (16.7 vs. 11.5%; p = 0.0002), and increased pack-year history of smoking (8.6 ± 18.3 vs. 5.6 ± 14.2; p = 0.0006), and the Charlson Comorbidity Index (0.51 ± 0.74 vs. 0.35 ± 0.57, p < 0.0001). Sepsis resulted in an increased length of stay (10.1 ± 14.4 vs. 2.4 ± 4.8 days; p < 0.0001) and a 30 times greater chance of 30-day mortality (4.03 vs. 0.11%, p < 0.0001). Multivariate logistic regression analysis showed that current smokers had a 63% greater chance of developing sepsis compared to non-smokers, controlling for age, race, gender, BMI, and CCI score (OR 1.63, 95% CI 1.23-2.14; p = 0.0006). CONCLUSIONS: Laparoscopic gastric bypass is uncommonly associated with postoperative sepsis. When it occurs, it portends a 30 times increased risk of death. A patient history of diabetes, hypertension, and increasing pack-years of smoking portend an increased risk of sepsis. Current smoking status, a preoperative modifiable risk factor, is independently associated with the chance of postoperative sepsis. Preoperative patient optimization and risk reduction should be a priority for elective surgery, and patients should be encouraged to stop smoking prior to gastric bypass.

The ontology of craniofacial development and malformation for translational craniofacial research.

We introduce the Ontology of Craniofacial Development and Malformation (OCDM) as a mechanism for representing knowledge about craniofacial development and malformation, and for using that knowledge to facilitate integrating craniofacial data obtained via multiple techniques from multiple labs and at multiple levels of granularity. The OCDM is a project of the NIDCR-sponsored FaceBase Consortium, whose goal is to promote and enable research into the genetic and epigenetic causes of specific craniofacial abnormalities through the provision of publicly accessible, integrated craniofacial data. However, the OCDM should be usable for integrating any web-accessible craniofacial data, not just those data available through FaceBase. The OCDM is based on the Foundational Model of Anatomy (FMA), our comprehensive ontology of canonical human adult anatomy, and includes modules to represent adult and developmental craniofacial anatomy in both human and mouse, mappings between homologous structures in human and mouse, and associated malformations. We describe these modules, as well as prototype uses of the OCDM for integrating craniofacial data. By using the terms from the OCDM to annotate data, and by combining queries over the ontology with those over annotated data, it becomes possible to create "intelligent" queries that can, for example, find gene expression data obtained from mouse structures that are precursors to homologous human structures involved in malformations such as cleft lip. We suggest that the OCDM can be useful not only for integrating craniofacial data, but also for expressing new knowledge gained from analyzing the integrated data.

Genotype and clinical care correlations in craniosynostosis: findings from a cohort of 630 Australian and New Zealand patients.

Craniosynostosis is one of the most common craniofacial disorders encountered in clinical genetics practice, with an overall incidence of 1 in 2,500. Between 30% and 70% of syndromic craniosynostoses are caused by mutations in hotspots in the fibroblast growth factor receptor (FGFR) genes or in the TWIST1 gene with the difference in detection rates likely to be related to different study populations within craniofacial centers. Here we present results from molecular testing of an Australia and New Zealand cohort of 630 individuals with a diagnosis of craniosynostosis. Data were obtained by Sanger sequencing of FGFR1, FGFR2, and FGFR3 hotspot exons and the TWIST1 gene, as well as copy number detection of TWIST1. Of the 630 probands, there were 231 who had one of 80 distinct mutations (36%). Among the 80 mutations, 17 novel sequence variants were detected in three of the four genes screened. In addition to the proband cohort there were 96 individuals who underwent predictive or prenatal testing as part of family studies. Dysmorphic features consistent with the known FGFR1-3/TWIST1-associated syndromes were predictive for mutation detection. We also show a statistically significant association between splice site mutations in FGFR2 and a clinical diagnosis of Pfeiffer syndrome, more severe clinical phenotypes associated with FGFR2 exon 10 versus exon 8 mutations, and more frequent surgical procedures in the presence of a pathogenic mutation. Targeting gene hot spot areas for mutation analysis is a useful strategy to maximize the success of molecular diagnosis for individuals with craniosynostosis.

Simulated Colonoscopy Objective Performance Evaluation (SCOPE): a non-computer-based tool for assessment of endoscopic skills.

BACKGROUND: The Simulated Colonoscopy Objective Performance Evaluation (SCOPE) was developed to fill the need for a lower-cost, non-virtual-reality (VR)-based assessment tool. This study aimed to evaluate the ability of SCOPE to assess endoscopic skills objectively. METHODS: Four tasks were created using the Kyoto Kagaku colonoscopy model (Kyoto Kagaku Co., Ltd., Kyoto, Japan). The SCOPE tasks included Scope Manipulation (SM) requiring torque and tip deflection to align a shape in the colon with a matching shape on the monitor; Tool Targeting (TT) requiring coordination with biopsy forceps to contact a metal target; Loop Management (LM) requiring prevention, recognition, and reduction of a redundant sigmoid colon with navigation to the cecum; and Mucosal Inspection (MI) requiring identification of simulated polyps during withdrawal and retroflexion. Key performance metrics were identified, and a normalized scoring system was developed. For the study, 35 subjects were stratified into three cohorts based on colonoscopy experience: novice (0-50 colonoscopies; n = 11), intermediate (51-139 colonoscopies; n = 13), and experienced (>140 colonoscopies; n = 11). The subjects performed two trials of all four tasks. RESULTS: Across all four tasks, the experienced endoscopists (E) consistently outperformed the intermediates (I), who in turn outperformed the novices (N). The mean normalized scores with 95 % confidence intervals (CI) are as follows: SM: N (54; range, 26-82), I (92; range, 79-106), E (106; range, 93-118) (p = 0.0006). TT: N (40; range, 24-55), I (77; range, 63-91), E (88; range, 72-105) (p < 0.0001). LM: N (51; range, 24-79), I (80; range, 59-101), E (101; range, 98-105) (p = 0.003). MI: N (73; range, 53-92), I (85; range, 76-95), E (100; range, 91-108) (p = 0.013). Total score: N (218; range, 155-280), I (335; range, 299-371), E (395; range, 371-419) (p < 0.0001). The test-retest reliability (0.6) for the expert total score was respectable. CONCLUSIONS: The validity evidence from this study shows that scores on SCOPE tasks can differentiate between groups expected to have different levels of technical skill. This model shows promise as a low-technology tool for objective assessment or training of endoscopic skills.

Massively Increased Caries Susceptibility in an Irf6 Cleft Lip/Palate Model.

Patients with cleft lip/palate (CLP) have been reported, in some studies, to exhibit an increased prevalence of caries, although the underlying cause for this increase is unknown. In genetically defined mouse models, studies of postnatal sequelae associated with CLP have been hampered by neonatal lethality. Using a conditional targeting approach, we ablated the major CLP gene Irf6 only in the late embryonic oral epithelium ( Irf6 cKO), bypassing the role of the gene in lip and palate morphogenesis and thus ensuring survival to adulthood. We report that Irf6 cKO mice present with 1) dysplastic salivary glands due to disruptions of epithelial junctional complexes, likely secondary to elevated activation of RHO GTPases, and 2) increased salivary cell proliferation. These changes result in significantly reduced saliva flow rate and buffering capacity and increased mucus acidity. A marked decrease in expression of CCL27, one of the major mucosal and skin cytokines, was found that correlated with increased bacterial colonization of the oral cavity with the cariogenic pathogen Streptococcus mutans and other bacteria. When placed on a high-sugar diet, Irf6 cKO mice show a 35-fold increase in presentation and severity of dental caries as compared with wild-type control mice. Strikingly, within the 8-wk test period, many molars extensively dissolved, and there was progressive loss of the alveolar bone, likely as a result of increased colonization of periodontal pathogens. These data provide the first mechanistic insight into the heightened caries susceptibility associated with CLP and indicate a direct role for the major CLP gene Irf6 in salivary gland development and a significant role in regulating oral immunity. Our data suggest that careful evaluation of salivary gland function and the implementation of early oral health preventive strategies are warranted to reduce the burden of dental care in this at-risk population.

Quality of life and outcomes for femoral hernia repair: does laparoscopy have an advantage?

BACKGROUND: Due to their relative scarcity and to limit single-center bias, multi-center data are needed to study femoral hernias. The aim of this study was to evaluate outcomes and quality of life (QOL) following laparoscopic vs. open repair of femoral hernias. METHODS: The International Hernia Mesh Registry was queried for femoral hernia repairs. Laparoscopic vs. open techniques were assessed for outcomes and QOL, as quantified by the Carolinas Comfort Scale (CCS), preoperatively and at 1, 6, 12, and 24 months postoperatively. Outcomes were evaluated using the standard statistical analysis. RESULTS: A total of 80 femoral hernia repairs were performed in 73 patients: 37 laparoscopic and 43 open. There was no difference in mean age (54.7 ± 14.6 years), body mass index (24.2 ± 3.8 kg/m2), gender (60.3 % female), or comorbidities (p > 0.05). The hernias were recurrent in 21 % of the cases with an average of 1.23 ± 0.6 prior repairs (p > 0.1). Preoperative CCS scores were similar for both groups and indicated that 59.7 % of patients reported pain and 46.4 % had movement limitations (p > 0.05). Operative time was equivalent (47.2 ± 21.2 vs. 45.9 ± 14.8 min, p = 0.82). There was no difference in postoperative complications, with an overall 8.2 % abdominal wall complications rate (p > 0.05). The length of stay was shorter in the laparoscopic group (0.5 ± 0.6 vs. 1.3 ± 1.6 days, p = 0.02). Follow-up was somewhat longer in the open group (23.8 ± 10.2 vs. 17.3 ± 10.9 months, p = 0.02). There was one recurrence, which was in the laparoscopic group (3.1 vs. 0 %, p = 0.4). QOL outcomes at all time points demonstrated no difference for pain, movement limitation, or mesh sensation. Postoperative QOL scores improved for both groups when compared to preoperative scores. CONCLUSION: In this prospective international multi-institution study of 80 femoral hernia repairs, no difference was found for operative times, long-term outcomes, or QOL in the treatment of femoral hernias when comparing laparoscopic vs. open techniques. After repair, QOL at all time-points postoperatively improved compared to QOL scores preoperatively for laparoscopic and open femoral hernia repair. While international data supports improved outcomes with laparoscopic approach for femoral hernia repair, no data had existed prior to this study on the difference of approach impacting QOL. In the setting where recurrence and complication rates are equal after femoral hernia repair for either approach, surgeons should perform the technique with which they are most confident, as the operative approach does not appear to change QOL outcomes after femoral hernia repair.

Disrupted IRF6-NME1/2 Complexes as a Cause of Cleft Lip/Palate.

Mutations and common polymorphisms in interferon regulatory factor 6 ( IRF6) are associated with both syndromic and nonsyndromic forms of cleft lip/palate (CLP). To date, much of the focus on this transcription factor has been on identifying its direct targets and the gene regulatory network in which it operates. Notably, however, IRF6 is found predominantly in the cytoplasm, with its import into the nucleus tightly regulated like other members of the IRF family. To provide further insight into the role of IRF6 in the pathogenesis of CLP, we sought to identify direct IRF6 protein interactors using a combination of yeast 2-hybrid screens and co-immunoprecipitation assays. Using this approach, we identified NME1 and NME2, well-known regulators of Rho-type GTPases, E-cadherin endocytosis, and epithelial junctional remodeling, as bona fide IRF6 partner proteins. The NME proteins co-localize with IRF6 in the cytoplasm of primary palatal epithelial cells in vivo, and their interaction with IRF6 is significantly enhanced by phosphorylation of key serine residues in the IRF6 C-terminus. Furthermore, CLP associated IRF6 missense mutations disrupt the ability of IRF6 to bind the NME proteins and result in elevated activation of Rac1 and RhoA, compared to wild-type IRF6, when ectopically expressed in 293T epithelial cells. Significantly, we also report the identification of 2 unique missense mutations in the NME proteins in patients with CLP (NME1 R18Q in an IRF6 and GRHL3 mutation-negative patient with van der Woude syndrome and NME2 G71V in a patient with nonsyndromic CLP). Both variants disrupted the ability of the respective proteins to interact with IRF6. The data presented suggest an important role for cytoplasmic IRF6 in regulating the availability or localization of the NME1/2 complex and thus the dynamic behavior of epithelia during lip/palate development.

Effect of verapamil on in vitro cytotoxicity of adriamycin and vinblastine in human tumor cells.

Verapamil has been shown to reverse acquired drug resistance to Adriamycin (ADR) and vinblastine in the P388 leukemia and Ehrlich ascites carcinoma model systems. Because of its potential clinical application, we evaluated the ability of verapamil to modulate the effect of ADR and vinblastine on the in vitro cloning of fresh human tumor cells. Fifty-three tumors were cloned in a soft agar system. Continuous exposure to verapamil at concentrations of 1.0, 5.0, and 10.0 micrograms/ml, did not significantly modulate the overall inhibitory activity of ADR and vinblastine (P greater than 0.05). There was no evidence of an effect when results were analyzed by tumor type or previous treatment except in the subgroup of 13 tumors obtained from patients who previously had a clinical response to ADR but were relapsing at the time the tumor specimen was obtained. In this population, at three concentrations of ADR, there was a significant modulation of drug effect (P = 0.10, 0.03, 0.03, respectively). In each subgroup, some tumors showed marked modulation of drug effect by verapamil. These results suggest that the mechanisms of acquired in vivo resistance to ADR may be similar to those occurring in cell lines. However, the effect on human tumors was minor as compared to the results with cell lines. The in vivo significance of this finding remains to be determined.

Full Spectrum of Postnatal Tooth Phenotypes in a Novel Irf6 Cleft Lip Model.

Clefting of the lip, with or without palatal involvement (CLP), is associated with a higher incidence of developmental tooth abnormalities, including hypodontia and supernumerary teeth, aberrant crown and root morphologies, and enamel defects, although the underlying mechanistic link is poorly understood. As most CLP genes are expressed throughout the oral epithelium, the authors hypothesized that the expression of CLP genes may persist in the dental epithelium and thus, in addition to their earlier role in labiopalatine development, may play an important functional role in subsequent tooth patterning and amelogenesis. To address this, the authors generated a unique conditional knockout model involving the major CLP gene, Irf6, that overcomes the previously reported perinatal lethality to enable assessment of any posteruption dental phenotypes. A dental epithelium-specific Irf6 conditional knockout (Irf6-cKO) mouse was generated via a Pitx2-Cre driver line. Dental development was analyzed by microcomputed tomography, scanning electron microscopy, histology, immunohistochemistry, and quantitative polymerase chain reaction. Irf6-cKO mice displayed variable hypodontia, occasional supernumerary incisors and molars, as well as crown and root patterning anomalies, including peg-shaped first molars and taurodontic and C-shaped mandibular second molars. Enamel density was reduced in preeruption Irf6-cKO mice, and some shearing of enamel rods was noted in posteruption incisors. There was also rapid attrition of Irf6-cKO molars following eruption. Histologically, Irf6-cKO ameloblasts exhibited disturbances in adhesion and polarity, and delayed enamel formation was confirmed immunohistochemically. Altered structure of Hertwig's epithelial root sheath was also observed. These data support a role for IRF6 in tooth number, crown and root morphology and amelogenesis that is likely due to a functional role of Irf6 in organization and polarity of epithelial cell types. This data reinforce the notion that various isolated tooth defects could be considered part of the CLP spectrum in relatives of an affected individual.

Potassium dependence of sodium transport in frog skin.

22Na+ and 42K+ fluxes across the basolateral membrane of the isolated epithelium of frog skin were investigated with regard to dependence on K+ in the basolateral solution. When K+ was removed from the basolateral solution (K+-free Ringer), there was a transient rise in short circuit current (Isc) that could be eliminated by pretreatment with ouabain. Concurrently, the apparent sodium efflux across the basolateral membrane (JNa*13) showed either no change or an immediate (1-2 min) small decrease (approximately equal to 10%) that was followed by a small transient increase. K+ fluxes showed either no change or a small decrease under these conditions. JNa*13 was partially ouabain sensitive during all of the above treatments. Furosemide partially inhibited both sodium and potassium flux after K+-free treatment. The pump, as defined by ouabain sensitivity of Na+ flux, continued to work even after 20 minutes of K+-free treatment. Pump activity may be maintained by potassium leaking from the cells that is recycled by the pump. However, the ouabain-sensitive transient rise in Isc after K+-free treatment cannot readily be explained by changes in either Na+ or K+ flux. A change in pump coupling ratio provides one explanation for these data.

Effects of isoproterenol on Na+ and K+ transport in frog skin epithelium.

The acute effects of isoproterenol on Na+ extrusion and K+ uptake across the basolateral membrane of the isolated epithelium of the frog skin were examined. A chloride-free sulfate Ringer was used in all experiments. Isoproterenol caused an approximate doubling of the short-circuit current (Isc) and the transepithelial Na+ flux (J13Na). Isc remained equal to J13Na. After isoproterenol treatment, ouabain inhibited Isc and J13Na in a manner similar to control tissues. Ouabain-sensitive K+ uptake was also measured under comparable conditions. In two sets of experiments, K+ uptake was increased on average by only 5 and 17 percent after isoproterenol treatment. Thus, isoproterenol caused Na+ flux to more than double while K+ uptake increased by only 5-17%. These data cannot be readily accounted for by a pump with a fixed Na+/K+ exchange ratio.

Na+ and K+ transport at basolateral membranes of epithelial cells. I. Stoichiometry of the Na,K-ATPase.

The stoichiometry of pump-mediated Na/K exchange was studied in isolated epithelial sheets of frog skin. 42K influx across basolateral membranes was measured with tissues in a steady state and incubated in either beakers or in chambers. The short-circuit current provided estimates of Na+ influx at the apical membranes of the cells. 42K influx of tissues bathed in Cl- or SO4-Ringer solution averaged approximately 8 microA/cm2. Ouabain inhibited 94% of the 42K influx. Furosemide was without effect on pre-ouabain-treated tissues but inhibited a ouabain-induced and Cl--dependent component of 42K influx. After taking into account the contribution of the Na+ load to the pump by way of basolateral membrane recycling of Na+, the stoichiometry was found to increase from approximately 2 to 6 as the pump-mediated Na+ transport rate increased from 10 to 70 microA/cm2. Extrapolation of the data to low rates of Na+ transport (less than 10 microA/cm2) indicated that the stoichiometry would be in the vicinity of 3:2. As pump-mediated K+ influx saturates with increasing rates of Na+ transport, Na+ efflux cannot be obligatorily coupled to K+ influx at all rates of transepithelial Na+ transport. These results are similar to those of Mullins and Brinley (1969. Journal of General Physiology. 53:504-740) in studies of the squid axon.

Na+ and K+ transport at basolateral membranes of epithelial cells. II. K+ efflux and stoichiometry of the Na,K-ATPase.

Changes of 42K efflux (J23K) caused by ouabain and/or furosemide were measured in isolated epithelia of frog skin. From the kinetics of 42K influx (J32K) studied first over 8-9 h, K+ appeared to be distributed into readily and poorly exchangeable cellular pools of K+. The readily exchangeable pool of K+ was increased by amiloride and decreased by ouabain and/or K+-free extracellular Ringer solution. 42K efflux studies were carried out with tissues shortcircuited in chambers. Ouabain caused an immediate (less than 1 min) increase of the 42K efflux to approximately 174% of control in tissues incubated either in SO4-Ringer solution or in Cl-Ringer solution containing furosemide. Whereas furosemide had no effect on J23K in control tissues bathed in Cl-rich or Cl-free solutions, ouabain induced a furosemide-inhibitable and time-dependent increase of a neutral Cl-dependent component of the J23K. Electroconductive K+ transport occurred via a single-filing K+ channel with an n' of 2.9 K+ efflux before ouabain, normalized to post-ouabain (+/- furosemide) values of short-circuit current, averaged 8-10 microA/cm2. In agreement with the conclusions of the preceding article, the macroscopic stoichiometry of ouabain-inhibitable Na+/K+ exchange by the pump was variable, ranging between 1.7 and 7.2. With increasing rates of transepithelial Na+ transport, pump-mediated K+ influx saturated, whereas Na+ efflux continued to increase with increases of pump current. In the usual range of transepithelial Na+ transport, regulation of Na+ transport occurs via changes of pump-mediated Na+ efflux, with no obligatory coupling to pump-mediated K+ influx.

Na+ and K+ transport at basolateral membranes of epithelial cells. III. Voltage independence of basolateral membrane Na+ efflux.

Na+ efflux across basolateral membranes of isolated epithelia of frog skin was tested for voltage sensitivity. The intracellular Na+ transport pool was loaded with 24Na from the apical solution and the rate of isotope appearance in the basolateral solution (JNa23) was measured at timed intervals of 30 s. Basolateral membrane voltage was depolarized by either 50 mM K+, 5 mM Ba++, or 80 mM NH+4. Whereas within 30 s ouabain caused inhibition of JNa23, depolarization of Vb by 30-60 mV caused no significant change of JNa23. Thus, both pump-mediated and leak Na+ effluxes were voltage independent. Although the pumps are electrogenic, pump-mediated Na+ efflux is voltage independent, perhaps because of a nonlinear relationship between pump current and transmembrane voltage. Voltage independence of the leak Na+ efflux confirms a previous suggestion (Cox and Helman, 1983. American Journal of Physiology. 245:F312-F321) that basolateral membrane Na+ leak fluxes are electroneutral.

Hormonal control of apical membrane Na transport in epithelia. Studies with fluctuation analysis.

To study the mechanisms by which antidiuretic hormone and prostaglandins regulate Na transport at the apical membranes of the cells of anuran tissues, studies were done with fluctuation analysis. Epithelia of frog skin (Rana pipiens) were treated with vasopressin alone, or treated with vasopressin after inhibition of Na transport by indomethacin. The tissues were bathed symmetrically with a Cl-HCO3 Ringer solution and short-circuited continuously. In this experimental circumstance, the amiloride-induced current noise power density spectra were of the Lorentzian type with little or no l/f noise, provided that "scraped" skins were used for study. Despite large changes of Na transport, especially in epithelia treated with indomethacin and vasopressin, the single-channel Na current remained essentially unchanged, whereas the density of amiloride-inhibitable, electrically conductive Na channels was increased by vasopressin and decreased by indomethacin.

Automated Detection of 3D Landmarks for the Elimination of Non-Biological Variation in Geometric Morphometric Analyses.

Landmark-based morphometric analyses are used by anthropologists, developmental and evolutionary biologists to understand shape and size differences (eg. in the cranioskeleton) between groups of specimens. The standard, labor intensive approach is for researchers to manually place landmarks on 3D image datasets. As landmark recognition is subject to inaccuracies of human perception, digitization of landmark coordinates is typically repeated (often by more than one person) and the mean coordinates are used. In an attempt to improve efficiency and reproducibility between researchers, we have developed an algorithm to locate landmarks on CT mouse hemi-mandible data. The method is evaluated on 3D meshes of 28-day old mice, and results compared to landmarks manually identified by experts. Quantitative shape comparison between two inbred mouse strains demonstrate that data obtained using our algorithm also has enhanced statistical power when compared to data obtained by manual landmarking.

A very high density microsatellite map (1 STR/41 kb) of 1.7 Mb on Xp22 spanning the microphthalmia with linear skin defects (MLS) syndrome critical region.

Microphthalmia with linear skin defects (MLS) syndrome is an X-linked disorder presenting only in XX individuals. It is characterised by dysmorphic features such as microphthalmia, sclerocornea, and linear streaks of erythematous and hypoplastic skin restricted to the head and neck. Karyotype analyses have so far revealed a terminal deletion or translocation causing monosomy for the distal Xp region (Xp22.3) in all patients. We have used existing cosmid clones from the region to perform a saturation screen for AC-type microsatellites with the goal of facilitating analysis of five novel patients with features of MLS. Three of these cases had an Xp22.3 abnormality, while the other two showed some characteristic features of MLS but had apparently normal karyotypes. Forty-two novel microsatellite markers have now been developed from the 1.7 Mb cloned interval. Ninety-three percent of the novel markers exhibited allelic variation, representing an average of one polymorphic PCR-based marker (STR) every 41 kb.

Posterior circulation stroke in childhood: risk factors and recurrence.

OBJECTIVE: To ascertain whether posterior circulation stroke in children has distinctive clinical or radiologic features. METHODS: Patients were identified retrospectively from two pediatric neurology centers. Clinical details were ascertained by chart review, and radiologic data were reviewed by three neuroradiologists. RESULTS: Twenty-two cases were identified (17 boys). Twenty children had evidence of vertebrobasilar arterial abnormalities, which were multifocal in 12. The etiology of these was vertebral artery dissection in 10 cases and unclear in the remaining 10. Cardiac abnormalities were rare (n = 4). Other risk factors for stroke in childhood were hypertension (n = 9), the thermolabile methylene tetrahydrofolate reductase gene mutation (n = 4), and the factor V Leiden mutation (n = 2). Two children had subluxation of the upper cervical spine at the extreme of normal limits. In follow-up for 6 months to 11 years (median 4 years), five patients had further strokes and seven had TIA. Overall, 12 patients had no residual neurologic deficits. CONCLUSIONS: The male preponderance, frequency of arterial dissection, rarity of cardiac embolism, and >20% recurrence were notable. Cerebral angiography is usually indicated if a definitive diagnosis is not made on MRI. Additional investigations should include echocardiography and cervical spine radiography in flexion and extension.

Cerebral siderosis: a complication of anticoagulant therapy?

The authors report a case of cerebral siderosis, a rare disease that generally follows multiple small episodes of subarachnoid hemorrhage from any source, following long-term anticoagulation and minor head injury, and document the features on MR, which demonstrates characteristic hypointensity in the meninges on T2-weighted scans.