The distribution of erythrocyte phospholipids in hereditary spherocytosis demonstrates a minimal role for erythrocyte spectrin on phospholipid diffusion and asymmetry

In the human erythrocyte membrane phosphatidylcholine and sphingomyelin reside mainly in the outer leaflet, whereas the aminophospholipids, phosphatidylethanolamine and phosphatidylserine, are mainly found in the inner leaflet. Maintenance of phospholipid asymmetry has been assumed to involve interactions between the aminophospholipids and the membrane skeleton, in particular spectrin. To investigate whether spectrin contributes to maintaining the phospholipid transbilayer distribution and kinetics of redistribution, we studied erythrocytes from hereditary spherocytosis patients whose spectrin levels ranged from 34% to 82% of normal. The phospholipid composition and the accessibility of membrane phospholipids to hydrolysis by phospholipases were in the normal range. Spin-labeled phosphatidylserine and phosphatidylethanolamine analogues that had been introduced into the outer leaflet were rapidly transported at 37 degrees C to the inner leaflet, whereas the redistribution of spin-labeled phosphatidylcholine was slower. The kinetics of transbilayer movement of these spin-labeled phospholipid in all samples was in the normal range and was not affected by the level of spectrin. Although these erythrocyte membranes contained as little as 34% of the normal level of spectrin and were characterized by several physical abnormalities, the composition, distribution, and transbilayer kinetics of the phospholipids were found to be normal. We therefore conclude that spectrin plays, at best, only a minor role in maintaining the distribution of erythrocyte membrane phospholipid.     

Recognition of beta 2-microglobulin-negative (beta 2m-) T-cell blasts by natural killer cells from normal but not from beta 2m- mice: nonresponsiveness controlled by beta 2m- bone marrow in chimeric mice.

The role of major histocompatibility complex (MHC) class I expression in control of the sensitivity of normal cells to natural killer (NK) cells was studied by the use of mutant mice made deficient for expression of beta 2-microglobulin (beta 2m) through homologous recombination in embryonal stem cells. T-cell blasts from beta 2m-deficient (beta 2m -/-) mice were killed by NK cells from normal mice in vitro, while beta 2m +/- blasts were resistant. The beta 2m defect also affected the NK effector cell repertoire: NK cells from beta 2m -/- mice failed to kill beta 2m -/- blasts, while they retained the ability to kill the prototype NK cell target lymphoma YAC-1, although at reduced levels. The inability to recognize beta 2m -/- blasts could be transferred with beta 2m -/- bone marrow to irradiated beta 2m-expressing mice. In contrast, the development of CD8+ T cells (deficient in beta 2m -/- mice) was restored in such chimera. These results indicate that loss of MHC class I/beta 2m expression is sufficient to render normal cells sensitive to NK cells, and that the same defect in the hemopoietic system of a mouse renders its NK cells tolerant to beta 2m-deficient but otherwise normal cells. In the beta 2m -/- mice, NK cells may be selected or educated by other bone marrow cells to tolerate the MHC class I deficiency. Alternatively, the specificity may be controlled directly by the class I molecules on the NK cells themselves.     

Phospholipase A2 levels in acute chest syndrome of sickle cell disease

Acute chest syndrome (ACS) is associated with significant morbidity and is the leading cause of death in patients with sickle cell disease (SCD). Recent reports suggest that bone marrow fat embolism can be detected in many cases of severe ACS. Secretory phospholipase A2 (sPLA2) is an important inflammatory mediator and liberates free fatty acids, which are felt to be responsible for the acute lung injury of the fat embolism syndrome. We measured SPLA2 levels in 35 SCD patients during 20 admissions for ACS, 10 admissions for vaso-occlusive crisis, and during 12 clinic visits when patients were at the steady state. Eleven non-SCD patients with pneumonia were also evaluated. To determine if there was a relationship between sPLA2 and the severity of ACS we correlated SPLA2 levels with the clinical course of the patient. In comparison with normal controls (mean = 3.1 +/- 1.1 ng/mL), the non- SCD patients with pneumonia (mean = 68.6 +/- 82.9 ng/mL) and all three SCD patient groups had an elevation of SPLA2 (steady state mean = 10.0 +/- 8.4 ng/mL; vaso-occlusive crisis mean = 23.7 +/- 40.5 ng/mL; ACS mean = 336 +/- 209 ng/mL). In patients with ACS sPLA2 levels were 100- fold greater than normal control values, 35 times greater than values in SCD patients at baseline, and five times greater than non-SCD patients with pneumonia. The degree of SPLA2 elevation in ACS correlated with three different measures of clinical severity and, in patients followed sequentially, the rise in SPLA2 coincided with the onset of ACS. The dramatic elevation of SPLA2 in patients with ACS but not in patients with vaso-occlusive crisis or non-SCD patients with pneumonia and the correlation between levels of SPLA2 and clinical severity suggest a role for SPLA2 in the diagnosis and, perhaps, in the pathophysiology of patients with ACS.     

Success,complications, and restenosis following rotational and transluminal extraction atherectomy of ostial stenoses

Our objectives were to determine procedural success, clinical complications, and follow-up restenosis rates after rotational burr and transluminal extraction atherectomy of coronary artery and saphenous vein graft ostial stenoses. Balloon angioplasty of ostial lesions has been associated with low rates of success and high rates of clinical complications and restenosis compared to nonostial lesions. Atherectomy, due to its ability to excise (extraction atherectomy) or pulverize (rotational atherectomy) atheroma and the internal elastic lamina, may result in improved procedural outcome. We retrospectively studied 101 patients with ostial stenoses treated by rotational burr and transluminal extraction atherectomy over a 3-yr period. Quantitative angiography and clinical follow-up were reviewed to determine success, complication, and restenosis rates. Rotational burr (n = 29) and transluminal extraction (n = 72) atherectomy were associated with high procedural success (93% and 90%, respectively) and a low incidence of complications (6.9% and 4.2%, respectively). Postatherectomy angiographic success was low (52% and 69%, respectively) and required adjunctive balloon angioplasty in 85% of patients overall. This lower success rate likely reflects device undersizing as the overall postatherectomy artery to device ratio was near unity (0.95). The rates of angiographic ostial restenosis remain high (39.1% and 65.9%, respectively, P < 0.05). The high rate of restenosis after transluminal extraction atherectomy was due to the higher rate of restenosis in saphenous vein grafts (80%) compared to TEC treated coronary arteries (59%). When only coronary artery lesions were compared, there was no significant difference between atherectomy device groups with respect to restenosis rates or late loss. Rotational or transluminal extraction atherectomy of ostial stenoses is associated with high procedural success rates and a low incidence of complications; however, the rates of restenosis in these lesions remain high.     

Percutaneous implantation of permanent pacemakers (author's transl)

2 methods for the implantation of permanent pacemakers with percutaneous puncture of the subclavian vein are described. The first one was used in 44 patients with the aid of an introducing catheter-set Desilets-Hoffman consisting of guide-wire, inner Teflon dummy catheter and outer thin-walled sheath; through this a shoulder-less electrode catheter no. 8 could be inserted for permanent pacing. The other technique was applied to 20 patients and used thinner special electrodes no. 6F, which could be introduced directly through a plastic cannula inserted with a puncture-needle. The advantages are: diminished risk of infections, local anesthesia instead of general anesthesia, applicability by the cardiologist in the catheterization-laboratory or under a simple fluoroscopy-unit, short stay of patients in the hospital without transfers to other departments, few personnel (1 scrubbed doctor, 1 non-scrubbed nurse), recognition of venous anomalies (singular left superior caval vein) without useless incisions for the patient. Complications such as pneumothorax, puncture of the subclavian artery, and dislocations of the electrodes have also been encountered.     

Postcardiac injury syndrome following radiofrequeny ablation of atrial flutter

We report the case of a 64-year-old woman who was admitted to our hospital for radiofrequency ablation of isthmus-dependent counterclockwise atrial flutter. Following an initially uncomplicated right atrial linear isthmus ablation that was associated with conversion of atrial flutter to sinus rhythm and evidence of complete isthmus block, the patient developed a small pericardial effusion, a marked and recurrent left-sided pleural effusion, and had significantly elevated inflammatory markers. After an extensive diagnostic work-up which excluded infectious, malignant and thromboembolic causes of the effusions, a diagnosis of postcardiac injury syndrome was made and the patient was treated with oral corticosteroids and nonsteroidal anti-inflammatory drugs. Over a treatment period of 2 months there was complete resolution of the pericardial and left-sided pleural effusions and normalization of inflammatory markers. Postcardiac injury syndrome is a rare complication of radiofrequency ablation that is characterized by signs of pericardial, pleural and pulmonary parenchymal inflammation.     

Discharge of pulmonary rapidly adapting stretch receptors during HFO ventilation.

High-frequency oscillatory ventilation (HFOV) has been shown to stimulate slowly adapting pulmonary stretch receptors (PSR) and thereby to inhibit spontaneous breathing, i.e. HFOV prolongs expiration or even elicits normocapnic apnea. However, during HFOV respiratory effects possibly mediated by pulmonary rapidly adapting receptors (RAR) have also been observed, e.g., diaphragmatic activation or augmented breaths. Therefore, we analyzed HFOV-induced changes in RAR activity in anaesthetized rabbits by mean of single fibre preparations of vagal RAR afferents. HFOV was applied in several combinations of airway pressure (Paw) and oscillation frequency (fOsc). In the sample of 60 RAR fibres prepared in 20 rabbits we found a wide spectrum of discharge patterns during HFOV. The inspiratory discharge rate during HFOV was increased in 38, decreased in 10, and unchanged in 12 RAR. The expiratory discharge rate was increased in 34, decreased in 17, and unchanged in 9 RAR. The effects of gradually changing Paw or of fOsc during HFOV were different in different fibres. In 17 fibres both inspiratory and expiratory discharge rates rose with increasing Paw during HFOV, whereas 19 fibres were not affected by increasing Paw. In some fibres either the inspiratory (12) or the expiratory (9) activity was inhibited in proportion to increasing Paw. From these results we conclude, that (a) the changes of RAR activity during HFOV are heterogeneous and the reflex effects of RAR stimulation may be balanced by RAR with decreased activity; (b) this heterogeneity of RAR discharge patterns explains the dominancy in the control of breathing during HFOV of the homogeneously stimulated PSR; and (c) depending on HFOV ventilatory parameters used the overall RAR stimulation may be strong enough to overrule the inspiration-inhibiting effects of PSR.     

Effects of aripiprazole on circadian prolactin secretion related to pharmacogenetics in healthy volunteers

Aripiprazole treatment in schizophrenic patients was previously associated with lower or normalized prolactin levels. Genetic variants in cytochrome P450 (CYP) (CYP2D6), dopamine receptor (DRD2, DRD3) and serotonin receptor (HTR2A, HTR2C) genes were previously associated with antipsychotic‐induced hyperprolactinaemia. Our aim was to evaluate whether aripiprazole affects prolactin secretion and its relationship with pharmacogenetics. Thirty‐one healthy volunteers receiving a 10‐mg single oral dose of aripiprazole were genotyped for 12 polymorphisms in CYP2D6, DRD2, DRD3, HTR2A and HTR2C genes by qPCR. Aripiprazole and dehydro‐aripiprazole plasma concentrations were measured by HPLC‐MS/MS. Prolactin concentrations of the 31 volunteers taking aripiprazole and 12 volunteers receiving ibuprofen were determined by ELISA. Prolactin concentrations after ibuprofen intake were considered as control, since it is known to cause no effect. Prolactin concentrations were slightly higher in the aripiprazole group compared to the ibuprofen group. All prolactin pharmacokinetic parameters were higher in females than in males. CYP2D6 poor and intermediate metabolizers had notably higher prolactin C_max and AUC_0‐12 than normal and ultrarapid metabolizers. The DRD3 rs6280 polymorphism affected prolactin levels: volunteers carrying Ser/Ser genotype had significantly lower prolactin levels than volunteers carrying the Gly allele. Furthermore, HTR2C rs3813929 C/C homozygotes had significantly lower prolactin levels than T allele carriers. Nevertheless, aripiprazole did increase prolactin levels compared to ibuprofen.     

Determinants of Successful Weight Loss After Using a Commercial Web-Based Weight Reduction Program for Six Months: Cohort Study

Background

The Internet is widely available and commonly used for health information; therefore, Web-based weight loss programs could provide support to large parts of the population in self-guided weight loss. Previous studies showed that Web-based weight loss interventions can be effective, depending on the quality of the program. The most effective program tools are visual progress charts or tools for the self-monitoring of weight, diet, and exercises. KiloCoach, a commercial program currently available in German-speaking countries, incorporates these features. A previous investigation showed that the program effectively supports users in losing weight.

Objective

We investigated weight loss dynamics stratified by weight loss success after 6-month use of KiloCoach. Furthermore, we analyzed possible associations between intensity of program use and weight loss. The results are intended for tailoring user recommendations for weight-loss Internet platforms.

Methods

Datasets of KiloCoach users (January 1, 2008 to December 31, 2011) who actively used the platform for 6 months or more were assigned to this retrospective analysis. Users (N=479) were 42.2% men, mean age of 44.0 years (SD 11.7), with a mean body mass index (BMI) of 31.7 kg/m² (SD 3.2). Based on the weight loss achieved after 6 months, 3 success groups were generated. The unsuccessful group lost <5%, the moderate success group lost 5%-9.9%, and the high success group lost ≥10% of their baseline body weight. At baseline, the unsuccessful (n=261, 54.5%), moderate success (n=133, 27.8%), and high success (n=85, 17.8%) groups were similar in age, weight, BMI, and gender distribution.

Results

After 6 months, the unsuccessful group lost 1.2% (SD 2.4), the moderate success group lost 7.4% (SD 1.5), and the high success group lost 14.2% (SD 3.8) of their initial weight (P<.001). Multivariate regression showed that early weight loss (weeks 3-4), the total number of dietary protocols, and the total number of weight entries were independent predictors for 6-month weight reduction (all P<.001) explaining 52% of the variance in weight reduction. Sensitivity analysis by baseline carried forward method confirmed all independent predictors of 6-month weight loss and reduced the model fit by only 11%. The high success group lost weight faster and maintained weight loss more efficiently than the other groups (P<.001). Early weight loss was associated with weight maintenance after 1 year and 2 years (both P<.001). Weight dynamics did not differ between men and women over 6 months when adjusted for baseline and usage parameters (P=.91). The percentage of male long-term users was unusually high (42.2%).

Conclusions

Our results suggest that early weight loss and close program adherence (ie, 5 dietary protocols per week and weekly entering of current weight), especially in the early phase of program usage, can improve weight loss outcome.