3D Motion Adapted Gating: Eine neue Navigatortechnik zur Verkürzung der Messzeit bei der MR-Koronarangiographie

PURPOSE

A major problem of free breathing coronary MR angiography (MRA) with respiratory navigator gating is low navigator efficiency and prolonged scan time due to irregular breathing patterns. 3D motion adapted gating (MAG) is a new adaptive navigator technique, which adapts in real time to changes of the end-expiratory position of diaphragm. This study evaluates the influence of 3D MAG on coronary MRA.

METHODS AND MATERIALS

In 3D MAG, two additional gating windows are grouped around the conventional window. Additionally, each gating window is divided into three bands assigned to different portions of the k-space. The scan is terminated when three consecutive bands are filled and one complete image data set is collected. Free breathing navigator-gated coronary MRA was performed on 48 patients with suspected coronary artery disease. In random order, each patient underwent an ECG-gated, a 3D segmented k-space gradient echo sequence using 3D MAG and a conventional navigator technique. The coronary MRA was evaluated and compared using the following parameters: 1. navigator efficiency and scan time; 2. visualized coronary artery length; 3. qualitative assessment of image quality; and 4. detection of stenoses > 50 % in comparison with catheter angiography.

RESULTS

Coronary MRA with 3D MAG had a significant increase in the average navigator efficiency (46 % +/- 12 % vs. 38 % +/- 12 %, p < 0.05), resulting in a significantly shorter scan time (mean: 18 % +/- 4 %, p < 0.05) for coronary MRA with 3D MAG compared to conventional navigator technique. Scans with and without 3D MAG had no significant differences in the continuously visualized vessel lengths, in the assessed image quality and in the sensitivity and specificity (83 % and 89 % vs. 83 % and 88 %, p > 0.05) of detecting coronary artery stenoses > 50 %.

CONCLUSION

The 3D MAG technique improves the navigator efficiency and significantly (p < 0.05) shortens the scan time of navigator gated coronary MRA while maintaining image quality and diagnostic accuracy in the detection of coronary artery stenoses.

Amiodarone-associated "torsade de pointes". Relevance of concomitant cardiovascular medication in a patient with atrial fibrillation and structural heart disease

A 69 year old female with history of coronary heart disease, myocardial infarction and paroxysmal atrial fibrillation suffered from occipital apoplexy. Under treatment with amiodarone 600 mg daily and concomitant medication with beta-acetyldigoxine (0.1 mg daily) and bisoprolole (1.25 mg daily), significant QT-prolongation (max. 700 ms; QTc: 614 ms) could be documented. Out of normofrequent sinus rhythm but as well out of bradycardia, the patient developed repetitive short-lasting "torsade de pointes" tachycardias (320 bpm) which terminated spontaneously. Serum electrolytes, plasma levels of digoxine (1.76 ng/ml) and amiodarone (1.9 mcg/ml) were within therapeutic range. This case report is the first to describe induction of amiodarone-associated "torsade de pointes" tachycardia during concomitant beta-blocker and digitalis medication in a patient with atrial fibrillation and structural heart disease. This points towards an elevated risk for proarrhythmia under this triple therapy.

Heart rate variability in patients suffering from structural heart disease and decreased AV-nodal conduction capacity

METHODS

Time and frequency domain analysis were conducted during a period of 600 s each. We performed a special protocol consisting of five different "pacing" periods: 1) recording of normal sinus rhythm (SR1); 2) atrial pacing with a rate 15% higher than the intrinsic heart rate; 3) ventricular pacing triggered by atrial activation (VAT, with a short AV-delay of 80 ms); 4) AV-sequential pacing with an atrial rate 15% higher than the intrinsic heart rate and a very short AV delay of 80 ms (DDD); 5) normal sinus rhythm (SR2). Only patients with normal AV-nodal conduction or with AV-block I degrees were included. The influence of a structural heart disease as well as a non-sustained VT on Holter ECG and a depressed EF on HRV parameters were analyzed using a multivariate analysis. All patients were lying in a supine position. Blood pressure was measured continuously and the frequency of breathing was controlled.

RESULTS

No differences in HRV between the two sinus rhythm periods SR1 versus SR2 could be detected. Neither SR1 vs VAT showed a significant difference for SDNN and r-MSSD. In contrast, HRV during SR1 compared to AAI, and HRV during VAT compared to AAI were significantly different (p < 0.001). When comparing HRV during DDD, which should be zero, and AAI, we found a significantly lower SDNN and r-MSSD (1.2 ms vs 4 ms, p < 0.04). The presence of structural heart disease, a non-sustained ventricular tachycardia, a depressed ejection fraction of less than 0.50 did not reveal a significant influence on the HRV parameters (multivariate analysis). The mean Wenckebach in patients with structural heart disease tended to be greater (437 ms vs 350 ms, p = 0.05); an increase in the Wenckebach was not correlated to a change in HRV parameters (p = ns).

CONCLUSION

Heart rate variability derived from consecutive RR-intervals is predominantly caused by periodicity in sinus-node impulse formation. A conduction variability of the AV-node exists, but is very low. The presence of a structural heart disease, a non-sustained ventricular tachycardia on Holter ECG, as well as a depressed ejection fraction of less than 0.50 showed no significant influence on the HRV parameters. Therefore, one can apply the calculation of heart rate variability for risk stratification in patients suffering from structural heart disease and moderate AV-nodal conduction disturbances. Attenuation of the oscillation of the heart rate, i. e. heart rate variability (HRV), is associated with an increased risk for mortality in patients with structural heart disease. Many of these patients also suffer from conduction disturbances, e. g. AV-nodal conduction delays. Whether the calculation of HRV in those patients is recommendable has not been investigated yet. Therefore, we conducted a study consisting of 20 consecutive patients in order to determine the formation of HRV, the influence of structural heart disease, the presence of a nonsustained ventricular tachycardia (VT), and a reduced ejection fraction (EF) on the HRV parameters during an elective electrophysiologic study.

In vitro cytotoxicity testing with fluorescence-based assays in cultured human lung and dermal cells

An in vitro study using human cultured cells was conducted to determine the reliability of fluorescence-based cell viability indicators with traditional in vitro cytotoxicity testing methods. Human lung epithelial carcinoma (A549) cells, and human embryonic skin (WS1) and lung (HFLI) fibroblasts were studied in culture to evaluate their potential to screen for cytotoxicity and to compare to previous protocols conducted in our laboratory. Confluent monolayers were incubated in the absence or presence of increasing concentrations of test chemicals for 24 h, and fluorescent-labeled probes were used to assess toxicity. Eight chemicals, including mercuric chloride, copper sulfate, sodium fluoride, thioridazine HCl, paraquat, amitriptyline-HCl, verapamil-HCl and chloroquine sulfate, were tested with each cell line using calcein-AM and Sytox. The data suggest that fluorescent probes are sensitive indicators of cytotoxicity and contribute to understanding the mechanisms for each chemical. In combination with previously published reports, the similarity of results among cell lines may be explained by the origin of the cell lines rather than by the diversity of the methods and indicators employed.

[Cardiac resynchronization therapy by biventricular pacing. How many patients with left ventricular dysfunction are eligible?]

BACKGROUND AND OBJECTIVE

Cardiac resynchronization therapy by multisite biventricular pacing presents an additive therapeutic option in the treatment of severe congestive heart failure. The objective of the study was to evaluate how many patients with left ventricular dysfunction may potentially benefit from this therapy.

METHODS

A total of 975 patients were screened for the prevalence of left ventricular dysfunction. Patients with a left ventricular ejection fraction (LVEF) <45 % were included into the investigation. Potential benefit of biventricular pacing was presumed in the presence of: LVEF < 35 %, severe heart failure (NHYA class III or IV), intrinsic left bundle branch block pattern with QRS interval > 150 ms and the absence of atrial fibrillation in the last 3 months before study inclusion.

RESULTS

In 203 patients (168 male, 35 female, mean age: 64 +/- 11) an LVEF <45 % was found. A total of 12 of these patients (6 %) or 12 of 113 patients (11 %) with an LVEF <35 % were identified as appropiate candidates for biventricular resynchronization therapy.

CONCLUSIONS

Cardiac biventricular pacing currently serves as a therapeutic option for a relatively small subgroup of patients with left ventricular dysfunction. Focusing on estimations that the incidence of heart failure in Germany amounts to more than 100.000 cases per year our results suggest that after all more than 6.000 patients per year may potentially benefit from electric resynchronization therapy. This number may increase substantially if prospective studies can prove that patients with heart failure and atrial fibrillation or left ventricular conduction delay due to univentricular pacing also benefit from cardiac resynchronization therapy.

Decremental intravenous pulse propagation during extrastimulus pacing: relevance for catheter ablation of focal atrial fibrillation

We report a case study demonstrating delayed circumferential intrapulmonary-venous conduction characteristics during coronary sinus extrastimulus pacing. This phenomenon allowed the unmasking and discrimination of a localized left atrial to PV breakthrough from secondarily activated PV muscle in a common left-sided PV ostium. Thus, this pacing manoeuvre may serve to guide RF delivery in the treatment of focal AF.

Stress incontinence observed with real time sonography and dynamic fastscan magnetic resonance imaging--insights into pathophysiology

Our concepts of pathophysiology of stress urinary continence have been greatly shaped by developments in radiographic imaging. Simple radiographs with and without contrast initially revealed the importance of urethral descent in pathogenesis. More recently, magnetic resonance imaging (MRI) and real time ultrasonography are showing soft tissue detail within both a global pelvic and a local urethral context. Careful examination of these studies can extend our concepts of pathophysiology and lead us beyond existing paradigms. We propose a unified theory of stress incontinence based on our dynamic fastscan MRI and real time ultrasonograms of stress incontinence, incorporating known details of pelvic anatomy, sphincteric location and function. The hypothesis introduces the concept of a continence threshold at which the urethra is subjected simultaneously to both shearing and explusive forces. If these forces are sufficient to overcome urethral coaptation at threshold, leakage results. The model proposes an anatomical sequence of changes through which the incontinent urethra cycles between periods of rest and increased abdominal pressure, and suggests a way in which repeated episodes of prolpase and urethral traction by shearing forces exerted by the vagina on the urethra may contribute to the development of intrinsic sphincteric deficiency.

Subacute cytotoxicity testing with cultured human lung cells

This study was designed to evaluate the potential of an in vitro cell culture method for its ability to determine subacute cytotoxicity and to compare the cytotoxic concentrations with rodent LD(50)s and clinical human toxicity data. Human fetal lung fibroblasts (HFL1) were incubated in the absence or presence of increasing concentrations of test chemicals for 72 h, and cell proliferation was used as a marker for toxicity. Inhibitory concentrations were extrapolated from concentration-effect curves after linear regression analysis. Comparison of the cytotoxicity data from testing 50 chemicals, with available human lethal concentrations for the same chemicals, revealed that the 72-h experimental IC(50)s are as accurate predictors of human toxicity as equivalent toxic blood concentrations derived from rodent LD(50)s. In addition, our results demonstrate that subacute 72-h exposure of HFL1 cells more accurately predicts cytotoxicity than a 24-h mitochondrial assay previously conducted in our laboratory, although the experimental IC(50) values were not statistically different in the two assays. It is anticipated that this procedure, together with a related battery of tests, may supplement or replace currently used animal protocols to screen chemicals for human risk assessment.

Expression of p53-related protein p63 in the gastrointestinal tract and in esophageal metaplastic and neoplastic disorders

p63 is a p53-related DNA-binding protein that helps regulate differentiation and proliferation in epithelial progenitor cells. Its expression has never been evaluated in the human gastrointestinal tract. The aim of this study was to evaluate the expression of p63 in the esophagus and related metaplastic and neoplastic disorders to gain insight into the pathogenesis of these processes. Of particular interest was the expression of p63 in Barrett esophagus (BE) and in BE-associated multilayered epithelium. Multilayered epithelium has been postulated to represent an early precursor to the development of BE primarily because it shares morphologic and immunophenotypic features of both squamous and columnar epithelium, and has been shown prospectively to be highly associated with BE. Routinely processed mucosal biopsy or resection specimens that contained normal esophageal squamous epithelium (n = 20), squamous dysplasia (n = 4), squamous cell carcinoma (n = 7), BE (n = 10), BE-associated multilayered epithelium (n = 13), esophageal mucosal gland ducts (n = 10), BE-associated dysplasia (n = 12), and BE-associated adenocarcinoma (n = 7) were immunostained for p63 to determine the extent and location of staining. p63 staining was compared with the staining patterns observed for p53, Ki 67 (proliferation marker), and cytokeratins (CKs) 13 (squamous marker), 14 (basal squamous marker), 8/18 (columnar marker), and 19 (basal/columnar marker). Expression of p63 messenger RNA (mRNA) isoforms was also analyzed by reverse-transcription polymerase chain reaction of freshly isolated tissues. In the normal esophagus, p63 was expressed in the basal and suprabasal layers of the squamous epithelium and in basal cells that line the mucosal gland ducts but was negative in all other epithelia of the gastrointestinal tract, including the stomach, small intestine, and colon. Similarly, p63 was not expressed in BE, but it, was present in the basal layer of multilayered epithelium in 9 of 13 cases (69%). p63-positive cells in multilayered epithelium and in the mucosal gland duct epithelium were positive for CK8/18 (100%) and CK13 (67% and 30%, respectively) and negative for CK14 (0%), in contrast to p63-positive cells in squamous epithelium, which were positive for CK14 and CK13 (100%) but negative for CK8/18. In neoplastic tissues, p63 was diffusely expressed in all cases of esophageal squamous cell dysplasia and carcinoma but was negative in all cases of esophageal and colorectal adenocarcinoma. The DeltaN isoform of p63 mRNA predominated in all benign and neoplastic squamous tissues examined. p63 may represent a marker of 2 distinct epithelial progenitor cells (basal squamous epithelium and gland duct epithelium) in the esophagus. P63 is upregulated in squamous neoplastic conditions and in this manner may play a role in squamous carcinogenesis. These data also indicate that multilayered epithelium is phenotypically similar to, and may share a lineage relationship with, mucosal gland duct epithelium.

[Surgery of substernal goiter]

OBJECTIVE

To study the surgical approaches and operative techniques for substernal goiter.

METHOD

A retrospective study of 27 cases with substernal thyroid nodules was made in our hospital.

RESULT

The operations on 27 patients with substernal nodules have been successfully carried out. Among them, 10 were goiters, 9 adenomas, 4 malignancy and 4 were thyroid cancer metastasizing to paratracheal or substernal nodes. Resection via cervical collar incision was adequate in 23 cases. Three thyroid cancers with paratracheal node metastasis were completely resected by sternotomy and only one thyroid cancer with paratracheal and substernal nodes metastasis was resected by combined thoracotomy and cervical collar incision.

CONCLUSION

Resection via cervical collar incision for all retrosternal thyroid nodules were advised. The preliminary experience with this procedure suggests that it has some advantages in the management of substernal goiter, including: 1. ease of operation compared to both sternotomy and thoracotomy; 2. relatively low morbidity; 3. safe and reliable.

In vitro and in vivo evaluations of biodegradable implants for hormone replacement therapy: effect of system design and PK-PD relationship

This investigation evaluated the feasibility of using subdermally implantable devices fabricated by nonconventional 3-dimensional printing technology for controlled delivery of ethinyl estradiol (EE2). In vitro release kinetics of EE2 and in vivo pharmacokinetics/pharmacodynamics in ovariectomized New Zealand White rabbits were carried out to study 3 implant prototypes: implant I (single-channel EE2 distribution in polycaprolactone polymer core), implant II (homogeneous EE2 distribution in polycaprolactone polymer matrix), and implant III (concentration-gradient EE2 distribution in polycaprolactone and poly(dl-lactide-co-glycolide) (50:50 matrix). EE2 was found to be released from all the implants in a nonlinear pattern with an order of implant III > implant II > implant I. The noncompartmental pharmacokinetic analysis of plasma EE2 profiles in rabbits indicated a significant difference (p < .05) in Cmax, tmax, and mean residence time between implant I and implants II and III, but no difference in the area under the plasma concentration time curves calculated by trapezoidal rule (AUC) among the implants. For pharmacodynamic studies, endogenous follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were observed to be suppressed following implantation of all implants, which demonstrated that a therapeutically effective dose of EE2 had been delivered. Furthermore, the noncompartmental analysis of plasma FSH and LH profiles in rabbits showed a significant difference (p < .05) in AUC and the mean residence time between implant III and implants I and II. A good in vivo/in vitro relationship was observed between daily amounts of EE2 released and plasma profiles of EE2 for all implants. This relationship suggests that plasma profiles of EE2 could be predicted from in vitro measurement of daily amount of EE2 released. Therefore, performing in vitro drug release studies may aid in the development of an EE2 implant with the desired in vivo release rate.

Histologic and immunophenotypic classification of cervical carcinomas by expression of the p53 homologue p63: a study of 250 cases

Recent studies of the p53 homologue p63 indicate that this gene is preferentially expressed in basal and immature cervical squamous epithelium. This study correlated p63 expression with morphologic phenotype and human papillomavirus (HPV) type in a wide range of cervical neoplasms. Two hundred fifty cases of cervical carcinoma, including squamous cell carcinoma (SCCA; n = 178), adenocarcinoma (ADCA; n = 28), adenosquamous carcinoma (ASCA; n = 8), neuroendocrine carcinoma (NECA; n = 15), and other variant or mixed types (n = 21) were studied. Ninety-seven percent of SCCA, 0% of ADCA, and 0% of SCUC showed strong (>75% v <30%) positivity for p63 (P<.001). p63 sharply distinguished SCCA (p63+) from ADCA (p63-), Large-cell, poorly differentiated carcinomas were distinguished as putative glandular (glassy cell) or squamous (lymphoepithelial-like or spindle cell) types based on p63 staining. Eight (73%) of 11 neuroendocrine tumors tested were chromogranin positive; all showed no or low (<30%) levels of p63 immunostaining. Absence of p63 was also associated with a subset of nonneuroendocrine undifferentiated carcinomas. Transitions from squamous to columnar or undifferentiated morphology coincided with loss of p63 expression. A strong association between HPV 16 and p63 positivity was identified because of the colocalization of both within tumors of squamous phenotype. p63 is a powerful marker for squamous differentiation and, when diffusely expressed, excludes a glandular or neuroendocrine differentiation. p63 may be useful for differentiating pure squamous or glandular from adenosquamous carcinomas, tracking shifts in differentiation within tumors, supporting (by its absence) the diagnosis of neuroendocrine carcinomas, and clarifying the spectrum of poorly differentiated carcinomas lacking either squamous or neuroendocrine differentiation.

Hay-Wells syndrome is caused by heterozygous missense mutations in the SAM domain of p63

Hay-Wells syndrome, also known as ankyloblepharon-ectodermal dysplasia-clefting (AEC) syndrome (OMIM 106260), is a rare autosomal dominant disorder characterized by congenital ectodermal dysplasia, including alopecia, scalp infections, dystrophic nails, hypodontia, ankyloblepharon and cleft lip and/or cleft palate. This constellation of clinical signs is unique, but some overlap can be recognized with other ectodermal dysplasia syndromes, for example ectrodactyly--ectodermal dysplasia--cleft lip/palate (EEC; OMIM 604292), limb--mammary syndrome (LMS; OMIM 603543), acro-dermato-ungual-lacrimal-tooth syndrome (ADULT; OMIM 103285) and recessive cleft lip/palate--ectodermal dysplasia (CLPED1; OMIM 225060). We have recently demonstrated that heterozygous mutations in the p63 gene are the major cause of EEC syndrome. Linkage studies suggest that the related LMS and ADULT syndromes are also caused by mutations in the p63 gene. Thus, it appears that p63 gene mutations have highly pleiotropic effects. We have analysed p63 in AEC syndrome patients and identified missense mutations in eight families. All mutations give rise to amino acid substitutions in the sterile alpha motif (SAM) domain, and are predicted to affect protein--protein interactions. In contrast, the vast majority of the mutations found in EEC syndrome are amino acid substitutions in the DNA-binding domain. Thus, a clear genotype--phenotype correlation can be recognized for EEC and AEC syndromes.