Eric Breisch

Myocardial characteristics of thyroxine stimulated hypertrophy a structural and functional study

SummaryThe effects of thyroxine-stimulated hypertrophy (TSH) were studied in the porcine left ventricular myocardium. Hypertrophy was produced in six adult pigs by administration of triiodothyronine (1 mg/kg; i.v) for eight days. Six pigs served as controls. The degree of hypertrophy, determined by left ventricular-to-body weight ratio, was 47%. With hypertrophy there was a significant increase in heart rate, blood pressure and myocardial blood flows. Minimal coronary resistance measured during adenosine infusion was lower in the TSH group compared with the control group. Anatomic studies revealed a balanced proliferative response of mitochondria, myofibrils and the t-tubular system during TSH. Analysis of the microvasculature indicated that the capillary and arteriolar beds both experienced growth which paralleled myocyte growth during TSH. These results suggest that thyroxine administration promotes angiogenesis in the microvascular bed which provides a partial anatomic rationale for the lowered minimal coronary resistance.

Nephrogenic Systemic Fibrosis with Multiorgan Involvement in a Teenage Male After Lymphoma, Ewing's Sarcoma, End-Stage Renal Disease, and Hemodialysis

Nephrogenic systemic fibrosis (NSF) is a rare condition that always occurs after acute or chronic renal failure with or without dialysis. The vast majority of cases in the literature are adults, and postmortem findings have been reported in only 5 cases. We report a 15-year-old male who developed NSF with multiorgan involvement after successful treatment of renal lymphoma and a subsequent sacral Ewings sarcoma, and end-stage renal disease treated with hemodialysis. At autopsy, he was found to have diffuse dural osseous metaplasia, transmural bronchiolar fibrosis, diaphragmatic central tendon fibrosis, and fibrous plaques of the mitral valve. These previously unreported findings expand the spectrum of multiorgan involvement in NSF providing additional evidence that it is an emerging systemic disorder.

Ultrastructural morphometry of the myocardium of Thunnus alalunga.

SummaryThe common ventricle in the heart of the Thunnus alalunga was studied. The ventricular myocardium consists of an outer compact layer and a thick inner spongy layer. The compact layer has slightly larger cells (4–6 μm diameter) than the spongy layer (2.5–5 μm diameter).Ultrastructurally the myocardium displays normal arrangements of myofibrils and mitochondria. The sarcoplasmic reticulum is poorly developed. The intercalated discs are simple with the fascia adherens being the most frequent junctional type observed; occasionally a desmosome was seen. Nexus type junctions are present but are unassociated with the intercalated discs. There are no t-tubules evident but the plasmalemma exhibits numerous caveolae which rarely form couplings with the sarcoplasmic reticulum.A morphometric analysis of the volume percent of mitochondria and myofibrils showed that the myocardial cells in the spongy layer of the heart have a significantly greater volume percentage of mitochondria than the compact layer. No significant differences were found between myocardial regions when the volume percentages of myofibrils were compared. The physiological studies revealed that the albacore tuna has heart rates (120 bpm) and ventricular blood pressures (100 mmHg) that are among the highest reported for fish.

A morphometric analysis of the infant calvarium and dura

Literature addressing the anatomic development of the dura and calvarium during childhood is limited. Nevertheless, histological features of a subdural neomembrane (NM), including its thickness and vascularity, developing in response to an acute subdural hematoma (SDH) have been compared to the dura of adults to estimate when an injury occurred. Therefore, we measured the morphometric growth of the calvarium and dura and the vascular density within the dura during infancy. The mean thicknesses of the calvarium and dura as a function of occipitofrontal circumference (OFC), as well as the mean number of vessels per 25× field, were determined from the right parasagittal midparietal bone lateral to the sagittal suture of 128 infants without a history of head trauma. Our results showed that as OFC increased, the mean thicknesses of the calvarium and dura increased while the vascular density within the dura decreased. Our morphometric data may assist in the interpretation of subdural NM occurring during infancy. We recommend future investigations to confirm and extend our present data, especially by evaluating cases during later infancy and beyond as well as by sampling other anatomic sites from the calvarium. We also recommend morphometric evaluation of subdural NM associated with SDH in infancy and childhood.

Myocardial lysosomes in pressure-overload hypertrophy*

SummaryCombined electron microscopic and cytochemical studies were used to investigate the effects of chronic-pressure overload hypertrophy on myocardial lysosomes, mitochondria, and myofibrils in the left ventricle of the cat. Myocardial hypertrophy was induced by an 84% banding constriction of the ascending aorta. After one month of aortic constriction the experimental animals demonstrated a 51% increase in left ventricular mass. No qualitative ultrastructural differences were noted between the myocardial tissues of the hypertrophy and normal group. However, the cytochemical reaction product to acid phosphatase appeared more frequently in the myocardium of the hypertrophy group compared to that of the normal group. By use of quantitative morphometry the percentage of mitochondria, myofibrils and lysosomes per myocardial cell was determined in both hypertrophy and normal groups of animals. Despite significant increases in the left ventricular mass of hypertrophy animals, a normal balance of mitochondria and myofibrils was maintained within the myocardium. Further analysis indicated an enhanced lysosomal population in the hypertrophy group compared to the normal group.

Congenital Cerebellar Malignant Rhabdoid Tumor in an Infant with Junctional Epidermolysis Bullosa

Epidermolysis bullosa (EB), a hereditary blistering condition of the skin, is divided into simplex, hemidesmosomal, junctional, and dystrophic types. It may be complicated by the development of squamous cell carcinoma of the skin, but other neoplasms, especially those separate from involved skin, are distinctly rare. We report a male infant with junctional EB who died of Pseudomonas sepsis and was found at autopsy to have a clinically unrecognized cerebellar malignant rhabdoid tumor (MRT). This is the first reported case of an infant with EB and a coincident extracutaneous neoplasm. It is also the first known case of EB associated with a pathologically confirmed malignant brain tumor. Cytogenetic results from the infant and his tumor and both of his parents suggest the infants EB and MRT were not genetically linked.