Atrial natriuretic factor in the pleural fluid of congestive heart failure patients

To investigate the possibility that atrial natriuretic factor might be secreted into the pleural fluid of patients with congestive heart failure who are known to have high concentrations of this new peptide hormone circulating in their plasma, six patients with class 2 New York Heart Association classified congestive heart failure had simultaneos measurement of plasma and pleural fluid atrial natriuretic factor concentrations. Atrial natriuretic factor was found in high concentrations in the pleural fluid of all of these patients. The concentration of atrial natriuretic factor in pleural fluid was nearly equal to the concentration in plasma of these patients. Their plasma levels were double the plasma concentration of this peptide hormone in 54 persons without congestive heart failure. These preliminary findings demonstrate that atrial natriuretic factor is present in pleural fluid of patients with congestive heart failure, but whether or not this secretion of atrial natriuretic factor into the pleural fluid helps the lung clear the fluid present in the lung in congestive heart failure cannot be determined from the present investigation.     

Ultraviolet light-induced modification of crosslinked hyaluronan gels

Hyaluronan (HA) gels (hylans) crosslinked with divinyl sulfone (DVS) are highly biocompatible and can be structurally modified to obtain desired mechanical properties that are attractive for their use as tissue-engineering scaffolds. However, unmodified hylan gels are not good substrates for cell attachment or infiltration, likely as a result of their smooth surface and the highly anionic nature of HA. This study investigated whether the cell-adhering characteristics of hylan gels could be enhanced by irradiation with ultraviolet (UV) light, with or without prior dehydration. The attachment and proliferation of neonatal rat smooth muscle cells atop these gels was compared with that on unmodified (control; C) or dehydrated (D) gels. UV-induced changes to gel structure and chemistry were characterized by confocal and electron microscopy, and fluorphore-assisted carbohydrate electrophoresis (FACE). Cell attachment was sparse on both unmodified (C) and dehydrated (D) gels. Significantly higher levels of cell attachment were observed on the surface of irradiated (UV) and dehydrated-irradiated (DUV) gels, likely because of texturing of the gel surface by UV light. In addition, dehydration of gels before UV irradiation created irregular pore-like structures through which cells appeared to migrate into the interior. FACE assays demonstrated that UV-irradiation alters the chemistry of HA, causing limited breakdown of HA chains and DVS crosslinks within gel and possibly creating new crosslinks that have not yet been identified. Because the hylan gels are altered structurally and chemically, binding of cells to the material is likely to be more permanent than possible by other approaches, such as coating of cell-adhesive matrix factors on the gel surface, described previously. The significance of this work is that we have developed a technique for the modification of DVS-crosslinked HA (hylans) to enhance their performance as a cellular scaffold for tissue-engineering applications.     

A simple breathing circuit to maintain isocapnia during measurements of the hypoxic ventilatory response

We report the development and testing of a simple breathing circuit that maintains isocapnia in human subjects during hypoxic hyperpnea. In addition, the circuit permits rapid switching between two gas mixtures with different partial pressures of oxygen. Eleven volunteers breathed repeated cycles of exposure to air (2 min of 21% O(2), balance N(2)) and hypoxia (2 min of 8.3+/-0.1% O(2), balance N(2)). Hypoxia induced significant increases in minute ventilation, breathing frequency and tidal volume (P < 0.05) that were consistent over repeated cycles of hypoxia (P > 0.1, one-way ANOVA). The system successfully maintained isocapnia in all subjects, with an average change in end-tidal CO(2) of only -0.2 mmHg during hyperventilation in hypoxia (range 0.4 to -0.8 mmHg). This system may be suitable for repeated tests of the hypoxic ventilatory response (HVR) and may prove useful for exploring intra- and inter-individual variability of HVR in humans.     

Loss of chondroitin 6-sulfate and hyaluronan from failed porcine bioprosthetic valves

Explanted porcine bioprosthetic valves have a thinned spongiosa, partially because of an overall loss of glycosaminoglycans (GAGs). We measured the concentrations of specific GAG classes in explanted bioprosthetic valves (n = 14, implanted 12.0 +/- 4.7 years) compared with glutaraldehyde-fixed porcine controls. After extraction with NaOH, GAGs were analyzed using either a hexuronic acid assay or fluorophore-assisted carbohydrate electrophoresis to quantify the individual GAG classes. The total GAG concentration in explants was 198 +/- 95 pmol/mg wet weight-93% less than freshly fixed controls. Explants also contained altered proportions of the different GAG classes relative to controls. The proportions of hyaluronan and chondroitin/dermatan-6-sulfate were reduced from 39 to 7% and 34 to 18% of total GAGs, respectively. The predominant explant GAG class was chondroitin/dermatan-4-sulfate (proportion elevated from 14 to 70%). This GAG is commonly found in the collagen-associated proteoglycan decorin, which is likely well crosslinked by glutaraldehyde. Chondroitin-6-sulfate is commonly found in the water- and hyaluronan-binding proteoglycan versican, which is likely poorly crosslinked. The loss of versican and its associated water-binding capacity is consistent with the thinned spongiosa. The resultant compromise of hydration, compressive resistance, and viscoelasticity may be responsible for the deterioration of the bioprosthesis in vivo.     

Prevalence study of Prader-Willi syndrome in North Dakota

A prevalence study of Prader-Willi syndrome (PWS) has been conducted in North Dakota. All pediatricians, neurologists, child psychiatrists, psychologists, and clinical geneticists were surveyed. The state's comprehensive evaluation center, the state hospital, the state institution for the mentally retarded, and group homes for the developmentally disabled, including one for persons with PWS, were also contacted. Seventeen patients were identified, 8 males, 8 females, and one patient whose sex was not specified. This suggests a prevalence rate of 1 per 16,062 in North Dakota.     

Congenital absence of the pericardium and its relationship to the ligamentum arteriosum

Summary An anatomic and embryologic study of congenital absence of the pericardium and the relationship of the ligamentum arteriosum to this defect was carried out by the authors. A case report is presented to clinically correlate the anatomic and radiologic findings in this anomaly. The authors propose that visualization of the ligamentum arteriosum by computed tomography is a characteristic sign for congenital absence of the left pericardium.

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Absence congénitale de péricarde, ses relations avec le ligament artériel

Résumé Les auteurs ont effectué une étude anatomique et embryologique de l'absence congénitale du péricarde et des relations entre le ligament artériel et cette absence. Ils rapportent une observation à propos de laquelle ils établisent les corrélations cliniques des données anatomiques et radiologiques de cette variation. Ils suggèrent que la visualisation du ligament artériel par tomodensitométrie soit interprétée comme un signe caractéristique de l'absence congénitale du péricarde gauche.