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Biomedical subjects

M Jacobs

Publications and source records attributed to M Jacobs.

At least 307 records · Page 17Linked to original sources
PubMedDate not supplied

Reversal of fenestration flow during ventricular systole in Fontan patients in junctional or ventricular paced rhythm.

Sinus node dysfunction is relatively common in patients with Fontan palliation for single ventricle congenital heart disease, and such patients often are in junctional rhythm or may have pacemaker systems for bradycardia. Because the physiologic determinants of left atrial pressure play a major role in determining pulmonary blood flow and therefore cardiac output in Fontan patients, the loss of atrioventricular (AV) synchrony in junctional rhythm or demand ventricular pacing in these patients might be expected to influence cardiac output. We report two cases of Fontan patients with the absence of AV synchrony that resulted in reversal of flow through the Fontan fenestration during ventricular systole. In both cases, restoration of AV synchrony by atrial pacing resulted in the elimination of retrograde fenestration flow, increased cardiac output, and improved clinical status.

Cardiac Catheterization↗
PubMedDate not supplied

Dengue: emergence as a global public health problem and prospects for control.

Dengue causes more illness and death than any other arboviral infection: there are at least 20 million infections in the world each year and several hundred thousand cases of a severe, life-threatening syndrome known as dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS). In recent years, the geographical range of dengue has extended and DHF/DSS is occurring in new areas and with increased incidence. The reasons for the resurgence are complex, but parallel demographic changes and reduced efforts towards disease control. Control of dengue currently depends on controlling its mosquito vector. However, development of a vaccine offers greater hope in the long-term. The dengue group of flaviviruses is unique in that it comprises 4 distinct serotypes which have the potential to cause sequential infections with increased severity. It is reasoned, therefore, that any vaccine should induce solid immunity to all 4 serotypes. Knowledge regarding dengue immunity and pathogenesis is rapidly advancing and it is reasonable to believe that this information can be used to devise a safe and efficacious vaccine for dengue, but it seems unlikely that this will become available in the near future.

Dengue↗
PubMedDate not supplied

Low-density lipoproteins inhibit endothelium-dependent relaxation in rabbit aorta.

The vascular endothelium, in response to pulsatile flow and vasoactive agents including acetylcholine, secretes the endothelium-derived relaxing factor (EDRF), a substance which regulates vascular tone. Recent interest in EDRF has focused on its possible dysfunction in atherosclerosis. In animal models of the disease, endothelium-dependent relaxation is markedly reduced. The continuous exposure of the endothelium in hyperlipidaemia to high concentrations of low-density lipoprotein (LDL), a known atherogenic risk factor, may explain this dysfunction. Here, we demonstrate that pathophysiological concentrations of LDL directly inhibit endothelium-dependent relaxation. Chemically modified LDL, in contrast, is inactive, implying that the inhibition is through a receptor-dependent mechanism.

Acetylcholine↗