In vitro electrophysiological drug testing using human embryonic stem cell derived cardiomyocytes

Pro-arrhythmia (development of cardiac arrhythmias as a pharmacological side effect) has become the single most common cause of the withdrawal or restrictions of previously marketed drugs. The development of new medications, free from these side effects, is hampered by the lack of an in vitro assay for human cardiac tissue. We hypothesized that human embryonic stem cell-derived cardiomyocytes (hESC-CMs) assessed with a combination of single cell electrophysiology and microelectrode array (MEA) mapping can serve as a novel model for electrophysiological drug screening. Current-clamp studies revealed that E-4031 and Sotalol (IKr blockers) significantly increased hESC-CM's action potential duration and also induced after-depolarizations (the in vitro correlates of increased arrhythmogenic potential). Multicellular aggregates of hESC-CMs were then analyzed with the MEA technique. Application of class I (Quinidine, Procaineamide) and class III (Sotalol) antiarrhythmic agents, E-4031, and Cisapride (a noncardiogenic agent known to lengthen QT) resulted in dose-dependent prolongation of the corrected field potential duration (cFPD). We next utilized the MEA technique to also assess pharmacological effects on conduction. Activation maps demonstrated significant conduction slowing following administration of Na channel blockers (Quinidine and Propafenone) and of the gap junction blocker (1-heptanol). While most attention has been focused on the prospects of using hESC-derived cardiomyocytes for regenerative medicine, this study highlights the possible utilization of these unique cells also for cardiac electrophysiological studies, drug screening, and target validation.     

Impact of self-assembly properties on antibacterial activity of short acyl-lysine oligomers

We investigated both the structural and functional consequences of modifying the hydrophobic, lipopeptide-mimetic oligo-acyl-lysine (OAK) N(alpha)-hexadecanoyl-l-lysyl-l-lysyl-aminododecanoyl-l-lysyl-amide (c(16)KKc(12)K) to its unsaturated analog hexadecenoyl-KKc(12)K [c(16(omega7))KKc(12)K]. Despite similar tendencies for self-assembly in solution (critical aggregation concentrations, approximately 10 muM), the analogous OAKs displayed dissimilar antibacterial properties (e.g., bactericidal kinetics taking minutes versus hours). Diverse experimental evidence provided insight into these discrepancies: whereas c(16(omega7))KKc(12)K created wiry interconnected nanofiber networks, c(16)KKc(12)K formed both wider and stiffer fibers which displayed distinct binding properties to phospholipid membranes. Unsaturation also shifted their gel-to-liquid transition temperatures and altered their light-scattering properties, suggesting the disassembly of c(16(omega7))KKc(12)K in the presence of bacteria. Collectively, the data indicated that the higher efficiency in interfering with bacterial viability emanated from a wobbly packing imposed by a single double bond. This suggests that similar strategies might improve hydrophobic OAKs and related lipopeptide antibiotics.     

Predicting genetic loading from symptom patterns in obsessive- compulsive disorder: a latent variable analysis

Background: Some symptom dimensions in obsessive‐compulsive disorder (OCD) patients have a familial and putative genetic foundation, based on replicated findings in studies of sib‐pairs with OCD. However, these symptom dimensions are all from exploratory factor analyses of Yale‐Brown Obsessive‐Compulsive Scale Symptom Checklist ratings based on non‐empirically derived symptom categories, rather than individual symptoms. Methods: In this study, we used a novel latent variable mixture model analysis to identify meaningful patient subgroupings. This was preceded by a confirmatory factor analysis of a 65‐item OCD symptom inventory from 398 OCD probands, which yielded a five‐factor solution. Data from all five symptom factors were used in a latent variable mixture model analysis, which identified two statistically separate OCD subpopulations. Results: One group of probands had a significantly higher proportion of OCD‐affected afflicted relatives (parents or close parental relatives), whereas the other group had a less prevalent familial OCD. The group with the more familial OCD was also found to have an earlier age of OCD onset, more severe OCD symptoms, and greater psychiatric comorbidity and impairment. Conclusions: Especially if the results are verified in other samples, this research paradigm, which identified characteristics of individuals with familial OCD, should prove useful in carrying out genome‐wide linkage and association studies of OCD and may provide a model for other symptom‐based studies of additional medical disorders. Depression and Anxiety 25:680–688, 2008. Published 2008 Wiley‐Liss, Inc.     

Breast augmentation under general anesthesia versus monitored anesthesia care: a retrospective comparative study

Breast augmentation is one of the leading esthetic surgeries, enjoying high satisfaction rates. Pain, nausea, and vomiting are frequent shortcomings of the immediate postoperative period. The aim of this study was to compare breast augmentation from the anesthetic point of view: general anesthesia (GA) versus monitored anesthesia care (MAC). The charts of 115 patients were reviewed in this retrospective study performed over a period of 2 years. Sixty-nine women chose to have the surgery done under MAC, and 46 under GA. Statistically significant differences were noted in both postoperative hospital stay (16.1 +/- 6.78 hours vs. 11.7 +/- 6.10 hours) and frequency of vomiting (mean, 0.5 vs. 0.22 times per patient) after GA and MAC, respectively (Mann-Whitney, P < 0.01). Postoperative pain, assessed using the visual analog scale, was significantly higher (mean visual analog scale, 5 vs. 3.27) when the prosthesis was placed in the submuscular plane compared with the subglandular plane (Mann-Whitney, P = 0.043). When offered a choice, more women preferred MAC over GA for their breast augmentation procedure. Less vomiting and shorter postoperative hospitalization were prominent in the MAC group.     

Staged reconstruction for resection wounds in sarcoma patients treated with brachytherapy

Adjuvant brachytherapy reduces local recurrences following wide local excision of large, high-grade sarcomas, but its use with immediate flap reconstruction is associated with a high wound complication rate following previous radiotherapy. To avoid flap irradiation and reduce wound-healing morbidity, a treatment strategy using negative-pressure wound therapy (NPWT) for temporary wound coverage during brachytherapy followed by delayed flap reconstruction was used in 3 previously irradiated sarcoma patients. NPWT was continued after brachytherapy catheter removal to stimulate vascularization, granulation, and wound contraction. Flap reconstructions were performed after the adequacy of the resection margins was pathologically confirmed and the wound bed appeared grossly vascularized. Prior to reconstruction, 2 patients required additional excision of positive or close permanent-section surgical margins. There were no major wound-healing complications during 9-18 months' follow-up. Staged closure using this approach may have advantages over immediate flap reconstruction in some sarcoma patients. Potential advantages include avoiding flap irradiation, reducing wound size and magnitude of the reconstructive procedure, and ensuring tumor-free surgical margins before definitive reconstruction.     

Comparison of the CobraPLA (Cobra Perilaryngeal Airway) and the Laryngeal Mask Airway Unique in children under pressure controlled ventilation

Background: The Laryngeal Mask Airway‐Unique (LMAU) and CobraPLA^TM (Cobra Perilaryngeal Airway) are supraglottic airway devices. There are no published studies comparing these devices in children breathing with pressure controlled ventilation (PCV). Methods: Eighty pediatric patients, scheduled for elective general surgery of short duration, were randomly assigned to have either a CobraPLA^TM or a LMAU used for airway management using PCV. We compared the devices with respect to (i) ability to form an effective cuff seal, (ii) oxygenation, (iii) endtidal carbon dioxide level, (iv) time to achieve an effective airway, (v) airway interventions required for insertion, (vi) fiberoptic score, (vii) respiratory variables and (vii) adverse events. Results: Cuff seal pressure was significantly higher for CobraPLA^TM (27.08 ± 4.15 cmH₂O) than for LMAU (20.91 ± 2.47 cmH₂O). Oxygenation was similar in both groups while the mean endtidal CO₂ in the CobraPLA^TM group was significantly higher than in the LMAU group (36.47 ± 1.93 mmHg vs 34.71 ± 3.05 mmHg, P = 0.021). Time and ease of insertion were similar, with CobraPLA^TM requiring more frequent jaw lift and LMAU requiring more frequent adjustment of the head and neck to achieve a proper position. Fiberoptic scores were excellent with both devices. Respiratory variables were similar with the exception that the plateau pressure and mean peak pressures were significantly lower with CobraPLA^TM. There was a low rate of blood mucosal staining of the devices. No patient in either group reported a sore throat. Conclusions: Both devices appear to be safe and effective in establishing an adequate airway in healthy children undergoing surgery of short duration with PCV.     

Urethral and bladder current perception thresholds: normative data in women

PURPOSE: Given increased evidence of sensory dysfunction in lower urinary tract pathology, we determined normative current perception threshold values in the lower urinary tract of asymptomatic women. MATERIALS AND METHODS: After receiving institutional review board approval women without lower urinary tract symptoms underwent current perception threshold testing of the urethra and bladder using a Neurometer constant current stimulator. Current perception threshold values were determined at 3 frequencies, including 2,000 Hz (corresponding to A-beta fibers), 250 Hz (corresponding to A-delta fibers) and 5 Hz (corresponding to C fibers). RESULTS: A total of 48 women with a mean age of 38 years (range 23 to 67) underwent current perception threshold testing. Normative values were established for the urethra and bladder at 2,000, 250 and 5 Hz. Median urethral current perception thresholds at 2,000, 250 and 5 Hz were 1.2 (IQR 0.76-1.5), 0.45 (IQR 0.33-0.56) and 0.11 mA (IQR 0.07-0.24), respectively. Median bladder current perception thresholds at 2,000, 250 and 5 Hz were 4.1 (IQR 2.0-6.3), 2.3 (IQR 0.87-5.5) and 1.4 mA (IQR 0.22-2.9), respectively. Urethral and bladder current perception thresholds increased significantly with subject age at all 3 frequencies (p<0.0005). Prior pelvic surgery was associated with an increased bladder current perception threshold at all 3 frequencies (p<0.005) but not with the urethral current perception threshold. CONCLUSIONS: We report urethral and bladder current perception thresholds for a large sample of asymptomatic women. These reference values may help elucidate changes in afferent nerve function in women with lower urinary tract dysfunction.     

Reticulolinear aplasia cutis congenita of the face and neck: a distinctive cutaneous manifestation in several syndromes linked to Xp22

A distinct form of aplasia cutis congenita presenting as linear facial skin defects has been described under a variety of names as Xp deletion syndrome, MIDAS ( mi crophthalmia, d ermal a plasia and s clerocornea) syndrome, MLS ( m icrophthalmia and l inear s kin defects) and Gazali–Temple syndrome. The syndrome is lethal in males, and its severity in females varies from a relatively mild residual facial scarring with short stature to lethal developmental organ malformations. A new case with peculiar ultrastructural findings is presented. A review of the literature suggests that these associations represent a series of contiguous–gene syndromes.     

Effect of a niobium-containing titanium alloy on osteoblast behavior in culture

Background: The chemistry of titanium is a key factor in determining implant–tissue interactions. Reports that a vanadium-based titanium alloy (Ti–6Al–4V) exhibits some cytotoxicity led to a search for an alternative.
Aim: The aim of the present study was to investigate the behavior of human osteoblast-like cells (Saos-2) cultured on Ti–6Al–4V or Ti–6Al–7Nb disks with a rough or a machined surface.
Results: In all four groups, the cells proliferated rapidly between days 1 and 3, and then plateaued. On day 1 of culture, the highest proliferation rate was of cells cultured on disks containing Nb with a machined surface. On day 7, there was no significant difference in cell density on all the tested surfaces. Alkaline phosphatase (ALP) activity was lower on the machined surfaces, regardless of the material used, suggesting that cells on rough surfaces exhibit a more mature phenotype. On day 3, cells cultured on rough disks made of Ti–6Al–7Nb showed the highest ALP activity; the lowest activity was observed on the machined Ti–6Al–4V surface. The highest level of osteocalcin (day 7) was found in the cells cultured on rough Ti–6Al–7Nb disks. Also, higher levels of transforming growth factor (TGFβ) were noted for cells cultured on the rough Ti–6Al–7Nb disks, suggesting that the Nb-containing alloy supports more rapid maturation of the osteoblast.
Conclusions: The results of the present study suggest that according to our cell culture preclinical model, Ti–6Al–7Nb may replace the Ti–6Al–4V alloy as an implant material.