Phenobarbital dosage for control of neonatal seizures

The relationship of the initial phenobarbital dose to weight, gestational age, blood level, and seizure control was studied in 39 neonates. The blood proportional to the dosage per kilogram, and was not related to weight or gestational age. Seizures remitted only at blood phenobarbital concentrations above 16.9 micrograms per milliliter. Therapeutic levels can be achieved by the intravenous or intramuscular administration of 16 to 23 mg per kilogram of phenobarbital.     

Comparison of in vitro proliferative capacity of human periodontal ligament cells in juvenile and aged donors

OBJECTIVE: The aim of this study is to compare the in vitro proliferative capacity of periodontal ligament (PDL) cells from aged and juvenile donors.
MATERIALS AND METHODS: Flow-cytometric analysis of the cell cycle was used to compare the length of each cell cycle, and the ratio of the cells progressing through the cycles between four PDL cells from juvenile donors and four cells from aged donors. Then, replicative capacity of the PDL cells from three juvenile and three aged donors was compared by serial cultureS. Finally, expression of c-fos was compared between cells proliferating and cells which had reached senescent.
RESULTS: Flow-cytometric analysis of the cell cycle had revealed that although there were no differences in the length of each phase of the cell cycle, significant differences were found in the ratio of the cells entering from Gap 1 to DNA synthesis phase of the cell cycle ( P < 0.025).Replicative capacity was much longer in two cells from juvenile donors (about 20 population doublings), while all cells from aged donors showed short dividing abilities (less than eight population doublings), hence entered senescent phases shortly. Additionally, no c-fos was detected in cells which had reached senescence upon stimulation with serum.
CONCLUSIONS: It is generally believed that aged humans have an impaired wound healing ability. We believe that more fibrotic PDL tissues seen in aged humans might be the reason for this, and suggest that this phenomena might be due to the progressive accumulation of senescent cell populations.     

Prevalence and clinical relevance of the morphological substrate of ventricular arrhythmias in patients without known cardiac conditions detected by cardiovascular MR

Objective

Cardiac MR (CMR) identifies the substrate of ventricular arrhythmia (VA) in cardiomyopathies and coronary heart disease. However, little is known about the value of CMR in patients with VA without previously known cardiac disorders.

Methods

76 patients with VA (Lown ≥2) without known cardiac disease after regular diagnostic work-up were studied with CMR, and findings were correlated with electrocardiogram (ECG) and electrophysiological stimulation (EPS). Structural abnormalities matching the VA origin as defined by ECG and/or EPS, or a CMR-detected cardiac condition known to cause arrhythmia were defined as VA substrate. CMR findings were defined as clinically relevant, if resulting in a new diagnosis, change of treatment or additional diagnostic procedure.

Results

44/76 patients demonstrated pathological CMR findings. In 24/76 patients, the pathology was detected by CMR and not by echocardiography. CMR-based diagnoses of cardiac disease were established in 20/76 patients, and all were morphological substrates for VA. In seven patients, the location of the CMR finding (scar) directly matched the VA origin. CMR findings resulted in a change of treatment in 21 patients and/or additional diagnostics in 8 patients.

Conclusion

Undetected cardiac conditions are frequent causes of VA. This is the first study demonstrating the value of CMR for detection of morphological substrate and/or underlying cardiac disorders in VA patients without known cardiac disease.

Advances in knowledge

The high incidence of clinically relevant CMR findings which were not detected during initial diagnostic work-up strongly supports the use of CMR to screen VA patients for underlying heart disease.Although the value of cardiac MR (CMR) for the diagnosis of cardiac diseases such as myocarditis is undisputed, CMR is also predictive of patients at high risk for ventricular arrhythmias (VAs) with conditions such as hypertrophic cardiomyopathy (HCM) and coronary heart disease (CHD).^1–3 Recent studies have demonstrated the ability of CMR to identify the anatomical correlate of VA in those patients. This anatomical correlate has been characterized by CMR as a structural abnormality (e.g. fibrosis or peri-infarct region), which may go undetected using other non-invasive imaging modalities.^4,5 A number of studies have been undertaken, or are ongoing, to further elucidate the added value of CMR in patients with known cardiac conditions, to improve risk stratification for VA and to optimize therapy.^1,6–8 However, little is known to date regarding the added value of CMR for detection of an arrhythmogenic substrate or underlying cardiac condition in patients who present with VAs without known cardiac disease.Thus, the purpose of this study was to investigate the added value of CMR in patients with VAs for detection of underlying heart disease and an arrhythmogenic morphological substrate, and also to investigate the clinical relevance of CMR in those patients with positive findings.