Detection of genomic deletions of PKP2 in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited myocardial disease that predominantly affects the right ventricle and is associated with ventricular arrhythmias that may lead to sudden cardiac death. Mutations within at least seven separate genes have been identified to cause ARVC, however a genetic culprit remains elusive in approximately 50% of cases. Although negative genetic testing may be secondary to pathogenic mutations within undiscovered genes, an alternative explanation may be the presence of large deletions or duplications involving known genes. These large copy number variants may not be detected with standard clinical genetic testing which is presently limited to direct DNA sequencing. We describe two cases of ARVC possessing large deletions involving plakophilin‐2 (PKP2) identified with microarray analysis and/or multiplex ligation‐dependent probe amplification (MLPA) that would have been classified as genotype negative with standard clinical genetic testing. A deletion of the entire coding region of PKP2 excluding exon 1 was identified in patient 1 and his son. In patient 2, MLPA analysis of PKP2 revealed deletion of the entire gene with subsequent microarray analysis demonstrating a de novo 7.9 Mb deletion of chromosome 12p12.1p11.1. These findings support screening for large copy number variants in clinically suspected ARVC cases without clear disease causing mutations following initial sequencing analysis.     

Age-dependent neurological phenotypes in a mouse model of PRRT2-related diseases

Paroxysmal kinesigenic dyskinesia is an episodic movement disorder caused by dominant mutations in the proline-rich transmembrane protein PRRT2, with onset in childhood and typically with improvement or resolution by middle age. Mutations in the same gene may also cause benign infantile seizures, which begin in the first year of life and typically remit by the age of 2 years. Many details of PRRT2 function at the synapse, and the effects of mutations on neuronal excitability in the pathophysiology of epilepsy and dyskinesia, have emerged through the work of several groups over the last decade. However, the age dependence of the phenotypes has not been explored in detail in transgenic models. Here, we report our findings in heterozygous and homozygous Prrt2 knockout mice that recapitulate the age dependence of dyskinesia seen in the human disease. We show that Prrt2 deletion reduces the levels of synaptic proteins in a dose-dependent manner that is most pronounced at postnatal day 5 (P5), attenuates at P60, and disappears by P180. In a test for foot slippage while crossing a balance beam, transient loss of coordination was most pronounced at P60 and less prominent at age extremes. Slower traverse time was noted in homozygous knockout mice only, consistent with the ataxia seen in rare individuals with biallelic loss of function mutations in Prrt2. We thus identify three age-dependent phenotypic windows in the mouse model, which recapitulate the pattern seen in humans with PRRT2-related diseases.

     

Transfer of patients with acute myocardial infarction for primary or acute angioplasty from hospitals without the facilities to perform angioplasty. Results from the pooled data of the Maximal Individual Therapy in Acute Myocardial Infarction (MITRA) Registry and the Myocardial Infarction Registry (MIR)

In patients with acute myocardial infarction (AMI) admitted at hospitals without angioplasty facilities there are some subgroups of patients which seem to profit from a transfer to primary or acute angioplasty. However, current clinical practice at such hospitals is unknown. We analyzed the pooled data of the German acute myocardial infarction registries MITRA and the MIR. Angioplasty was not available at 221/271 hospitals (81.5%). Out of 14,487 patients with acute myocardial infarction admitted to these hospitals, 50.1% (7,259/14,487) received thrombolysis at the initial hospital and 3.6% (523/14,487) were transferred. Out of the transferred patients, 55.3% (289/523) were treated with primary angioplasty and 44.7% (234/523) received a combination of thrombolysis and angioplasty. The proportion of transferred patients increased from 1.1% in 1994 to 5.5% in 1998 (p for trend = 0.001). One hundred and four hospitals (47.1%) never transferred patients. Patients transferred for primary angioplasty (289 patients) were compared to patients treated with thrombolysis at the initial hospitals (7,259 patients). Multivariate analysis showed the following independent predictors for transfer of patients for primary angioplasty: contraindications for thrombolysis (OR = 17.9), a non-diagnostic first ECG (OR = 4.0), pre-hospital delay > 6 hours (OR = 2.5), unknown symptom onset of the acute myocardial infarction (OR = 2.0) and anterior wall acute myocardial infarction (OR = 1.6). Heart failure at admission was the only independent predictor not to transfer patients (OR = 0.40). In Germany only 47.1% of hospitals without angioplasty facilities transfer patients with acute myocardial infarction to primary or acute angioplasty. The proportion of transferred patients increased from 1.1% in 1994 to 5.5% in 1998. Contraindications for thrombolysis were the strongest predictor to transfer patients to primary angioplasty.     

Primary angioplasty versus no reperfusion therapy in patients with acute myocardial infarction and a pre-hospital delay of > 12-24 hours: results from the pooled data of the maximal individual therapy in acute myocardial infarction (MITRA) registry and the myocardial infarction registry (MIR)

OBJECTIVE: In patients with acute myocardial infarction (AMI), treatment with thrombolysis is superior to no reperfusion therapy only up to 12 hours after the onset of symptoms. There are no data addressing whether this time limit is also justified for treatment with primary angioplasty. DESIGN: The pooled data of two German ST-segment elevation AMI registries, the Maximal Individual Therapy in Acute Myocardial Infarction (MITRA) study and the Myocardial Infarction Registry (MIR), were analyzed. PATIENTS: Out of 22,749 patients, eight hundred and forty-eight with a pre-hospital delay of > 12 hours and < or = 24 hours were treated with either primary angioplasty (94/848; 11.1%) or no reperfusion therapy (754/848; 88.9%). RESULTS: Patients treated with primary angioplasty were 10 years younger (59 years versus 69 years; p = 0.001), more often male [72.3% versus 59.9%; odds ratio (OR) = 0.57; 95% confidence interval (CI) = 0.36-0.92] and less likely to be diabetics (17% versus 27.2%; OR = 0.55; 95% CI = 0.31-0.97). Hospital mortality was 8.5% in patients treated with primary angioplasty compared to 17.1% in patients with no reperfusion therapy (OR = 0.45; 95% CI = 0.21-0.95; p = 0.033) and the combined endpoint (death, reinfarction or stroke) occurred significantly less often (11.7% versus 20.3%; OR = 0.52; 95% CI =0.27-1; p = 0.045). However, multiple logistic regression showed only a non-significant trend for lower mortality (OR = 0.54; 95% CI =0.20-1.23) and the combined endpoint (OR = 0.65; 95% CI = 0.29-1.31) in patients treated with primary angioplasty. CONCLUSIONS: These data show the possibility of a benefit of primary angioplasty over conservative treatment in patients with pre-hospital delays of > 12 up to 24 hours, although multiple logistic regression analysis failed to find significant differences between treatments. This might be due to inadequate study power or a selection bias. These findings encourage further investigation of this subject.     

Reliability and validity of the sideways step test and its correlation with motor function after stroke

[Purpose] This study investigated the intra-rater, inter-rater and test-retest reliability of the sideways step test (SST), its correlation with other indicators of stroke-specific impairment, and the cut-off count best discriminating subjects with stroke from their healthy counterparts. [Subjects and Methods] Forty-three subjects with chronic stroke and 41 healthy subjects older than 50 years participated in this study. The SST was administered along with the Fugl-Meyer motor assessment for the lower extremities (FMA-LE), the five-times sit to stand (5TSTS) test, the Berg Balance Scale (BBS), the movement velocity (MVL) by the limits of stability (LOS) test, the ten-metre walk (10mW) test, the timed “Up and Go” (TUG) test and the Activities-specific Balance Confidence (ABC) scale. [Results] The SST showed good to excellent intra-rater, inter-rater and test-retest reliability. The SST counts correlated with 5TSTS times, 10mW times, TUG times, and the FMA-LE and BBS scores. SST counts of 11 for the paretic leg and 14 for the non-paretic leg were found to distinguish the healthy adults from subjects with stroke. [Conclusion] The sideways step test is a reliable clinical test, which correlates with the functional strength, gait speed, and functional balance of people with chronic stroke.Key words: Balance, Stroke, Rehabilitation     

Assessment of aldehyde dehydrogenase in viable cells

Cytosolic aldehyde dehydrogenase (ALDH), an enzyme responsible for oxidizing intracellular aldehydes, has an important role in ethanol, vitamin A, and cyclophosphamide metabolism. High expression of this enzyme in primitive stem cells from multiple tissues, including bone marrow and intestine, appears to be an important mechanism by which these cells are resistant to cyclophosphamide. However, although hematopoietic stem cells (HSC) express high levels of cytosolic ALDH, isolating viable HSC by their ALDH expression has not been possible because ALDH is an intracellular protein. We found that a fluorescent aldehyde, dansyl aminoacetaldehyde (DAAA), could be used in flow cytometry experiments to isolate viable mouse and human cells based on their ALDH content. The level of dansyl fluorescence exhibited by cells after incubation with DAAA paralleled cytosolic ALDH levels determined by Western blotting and the sensitivity of the cells to cyclophosphamide. Moreover, DAAA appeared to be a more sensitive means of assessing cytosolic ALDH levels than Western blotting. Bone marrow progenitors treated with DAAA proliferated normally. Furthermore, marrow cells expressing high levels of dansyl fluorescence after incubation with DAAA were enriched for hematopoietic progenitors. The ability to isolate viable cells that express high levels of cytosolic ALDH could be an important component of methodology for identifying and purifying HSC and for studying cyclophosphamide-resistant tumor cell populations.     

Protection of murine bone marrow by dexamethasone during cytotoxic chemotherapy

Corticosteroids have the ability to suppress the production of growth factors and cytokines and are thus implicated in the negative regulation of hematopoiesis. We have shown that the corticosteroids, prednisolone and dexamethasone, were able to effectively protect progenitor cells in four strains of mice against cell-cycle-specific antimetabolic chemotherapy agents. The highest levels of protection against 5-fluorouracil (FU; 200 mg/kg) were achieved when two or three intraperitoneal injections of dexamethasone were administered between - 7 and +3 hours at a dose of 7.5 mg/kg/injection (optimal dose) or by continuous infusion between -4 and +20 hours. This protective effect is manifested as an increase in the number of high proliferative potential colony-forming cells that survive in the bone marrow 3 days after treatment with FU from between 0.5% and 11% to between 10% and 34% of normal. The bone marrow progenitors and blood cell numbers return to normal from 3 to 5 days and 1 to 2 days earlier, respectively. Less dexamethasone than prednisolone is required to give an equivalent protective effect, which is consistent with their anti-inflammatory potency. These findings are further evidence of the negative regulatory role played by corticosteroids, and indicate that the treatment schedules of corticosteroids during cancer therapy need to be reexamined to obtain the maximum benefit from their use.