Israel Medical Association Journal

Background: The need for aortic valve replacement in children and young adults poses a special problem to cardiologists and surgeons. Replacing the sick aortic valve with the patient’s pulmonary valve as described by Ross has proven to be a good option in this special age group.

Objective: To review our initial experience in order to assess the short-term results.

Methods: From January 1996 to June 1999, 40 patients (age 8 months to 41 years) underwent aortic valve replacement with pulmonary autograft. Indications for surgery were congenital aortic valve disease in 30 patients, bacterial endocarditis in 5, rheumatic fever in 3, and complex left ventricular outflow tract obstruction in 3. Trans-esophageal echocardiography was performed preoperatively and post-bypass in all patients, and transthoracic echocardiography was done prior to discharge and on follow-up.

Results: There was no preoperative or late mortality. All patients remain in functional class I (New York Heart Association) and are free of complications and medication. None showed progression of autograft insufficiency or LVOT obstruction. Homograft insufficiency in the pulmonary position has progressed from mild to moderate in one patient, and three developed mild homograft stenosis.

Conclusions: The Ross procedure can be performed with good results in the young population and is considered an elegant surgical alternative to prosthetic valves and homografts.

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LVOT = left ventricular outflow tract

Background: The etiology of bone marrow failure, a prominent feature of paroxysmal nocturnal hemoglobulinuria, is presently unknown.

Objectives: To evaluate the possible influence of cellular immune mechanisms in the bone marrow failure of PNH.

Methods: We studied marrow erythroid colony formation in a patient with paroxysmal nocturnal hemoglobinuria without hypoplastic/aplastic marrow complications.

Results: In vitro assays revealed a pronounced inhibition of primitive erythroid (BFU-E) progenitor cell growth by marrow T lymphocytes. Removal of T cells prior to culture resulted in a 4.5-fold enhancement of BFU-E numbers. Reevaluation of in vitro erythropoiesis during steroid administration indicated a persistent, albeit less prominent, T cell inhibitory effect.

Conclusion: Our findings provide the first direct evidence for a cellular immune inhibitory phenomenon accompanying PNH.

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PNH= paroxysmal nocturnal hemoglobinuria

Background: The growth plate increases its activity in response to exercise. Likewise, decreased physical activity exerts a negative effect on bone growth and development, leading to rarefaction of the subepiphyseal bone. Limb immobilization inhibits the growth plate’s activity, indirectly shown by a recorded arrest in longitudinal growth of the long bones. However, there is no direct evidence concerning the growth plate itself.

Objective: To determine whether the growth plate exhibits measurable microstructural changes in response to decreased levels of physical activity.

Methods: Histomorphometric analysis was used to qualitatively and quantitatively assess the changes in the epiphyseal plate in response to single hind limb immobilization in the rat. In 16 of 25 Sprague-Dawley male rats the left hind limb was immobilized for 3 weeks; the remaining 9 rats served as controls. The left proximal tibia of each animal was examined by computerized image analysis.

Results: There was a decrease in epiphyseal height, cell column density and subepiphyseal trabecular area - all indices of growth plate activity. Metaphyseal cortical thickness was also depressed, thereby confirming the efficacy of the immobilization method applied.

Conclusions: Limb immobilization in the rat induces inhibitory histological changes in the epiphyseal growth plate, which are in contrast to the excitatory microscopic changes seen with exercise. These changes can be assessed quantitatively. Their potential for reversibility remains to be determined by future experiments.

Objectives: This article reviews 25 years (1973–98) of experience in bone banking in Israel.

Methods: A nationwide survey on the clinical application of the banked musculoskeletal tissues during 1996 was conducted by means of a written questionnaire sent to all orthopedic departments in Israel.

Results:  The response rate to the questionnaire was 84%. A total of 257 cases were allocated bone allografts: the majority comprised 225 spongy bones, 26 were massive bone allografts and 6 were soft tissue allografts.

Conclusion:  Improvement of quality control and quality assurance of the banked tissues, together with development of skills in the use of osteoinductive and osteoconductive materials, cast the future of musculoskeletal tissue banking.

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 * A Tribute to Professor Henry Horoszowski