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Biomedical subjects

J L Long

Publications and source records attributed to J L Long.

17 recordsLinked to original sources
PubMed1999

In vivo measurement of solute transport rates in a bioartificial organ.

A radioactive tracer technique was used to evaluate the in vivo mass transfer properties of a tissue engineered bioartificial organ. To obtain these measurements, bioartificial organs were first implanted in ten rats and allowed to vascularize for 4 weeks. After vascularization, radioactive inulin was placed within the cell chamber of the device. Following the addition of tracer, blood samples were taken over a 4-h time period and inulin levels were determined. The results of these experiments were interpreted using a compartmental model that describes the transport of inulin from the cell chamber, across the immunoisolation membrane, and into the neovascularized region contained within the adjacent scaffold material. Nonlinear regression analysis of the plasma inulin levels using a four-compartment pharmacokinetic model provided estimates of the membrane permeability, the product of the capillary wall surface area and capillary permeability, and the glomerular filtration rate (GFR). The permeability of the membrane was found to be 3.50 x 10(-5) +/- 1.15 x 10(-5) cm/sec (95% confidence interval, n = 10), which compares favorably to previous in vitro permeability data for this membrane. The capillary wall permeability was found to be 0. 0087 6 0.0029 cm(3)/sec/100 g of tissue. This compares well to a reported value for inulin of 0.01 cm(3)/sec/100 g of tissue. The GFR was found to be 0.44 +/- 0.07 ml/h/g BW, which compares well with a reported value of 0.40 ml/hr/g BW. The inulin tracer technique reported here is a useful tool for assessing the in vivo transport characteristics of a bioartificial organ as well as the vascularization within tissue engineered structures.

Animals↗
PubMed1996

[Myocardial diverticulum of the left ventricle. Review of the literature apropos of a case].

Left ventricular myocardial diverticular rare, as they represent 0.05% of all forms of diagnosed congenital heart disease. The circumstances of diagnosis are as variable as the multiplicity of symptoms with which they are associated. Consequently, treatments (or very often conservative management) are also varied and a standardized procedure has not been defined in this field, apart from a common sense approach.

Cardiomyopathies↗
PubMed1984

[Association of an interauricular communication of the sinus venosus type with obstructive myocardiopathy. Surgical treatment].

The authors report the case of a 46 year old man in congestive cardiac failure for 4 years due to the association of a sinus venosus atrial septal defect and hypertrophic obstructive cardiomyopathy. Surgery was attempted because of the poor response to medical therapy. The operation consisted in a trans aortic left ventricular myotomy with mitral valve replacement, enlargement of the atrial septum by a patch and correction of the sinus venosus also by a patch. The result was excellent, with regression of the clinical signs of cardiac failure, maintained after 6 months' follow-up. This is certainly a very rare pathological association of which we were unable to find any previous reported case in the literature. Two cases of ostium secundum atrial septal defect with hypertrophic obstructive cardiomyopathy have been operated on previously, one successfully and the other one without success. A rational surgical approach is suggested, based on the analysis of the physiopathological consequences of this rare association.

Cardiomyopathy, Hypertrophic↗
PubMed1983

Gastric manifestations of North American Burkitt's lymphoma.

Stomach involvement is rare in American Burkitt's lymphoma. Three cases were noted in 66 patients, and all were associated with large left upper quadrant masses. The appearance of Burkitt's lymphoma of the stomach is similar to other lymphomas and consists of diffuse infiltration of the wall, mucosal thickening, ulcerations, and intra- and extragastric masses. Extension into the oesophagus was noted twice, and small bowel masses were associated with two cases. CT scanning and ultrasound are useful for defining extragastric extent of tumour. Rapid reversion to a more normal appearance is noted following chemotherapy.

Adolescent↗
PubMed1982

[A complication of peritoneojugular shunt for ascites: peritoneal migration of the shunt tubing].

A peritoneojugular shunt operation was done in a cirrhotic patient with ascites. The Le Veen valve functioned correctly for six months. The patient then experienced recurrence of ascites following an uncommon complication: migration of the shunt tubing into the peritoneal cavity. The tubing could no longer be felt in the cervical or thoracic regions. Plain roentgenograms of the abdomen showed that the shunt tubing was in the peritoneal cavity.

Ascites↗
PubMed1981

Morphological profiles of cryptorchid XXY mouse testes.

Two mice with an XXY karyotype and cryptorchid testes appeared spontaneously in a colony. The animals were H-Y antigen-positive, and had elevated serum levels of follicle-stimulating (FSH) and luteinizing (LH) hormones. Testes of the affected mice were atrophic, containing a few solid seminiferous cords surrounded by vast amounts of compact interstitial material. The cords were delimited by a broad tunica propria in which the basal lamina was irregularly thickened and stratified into a number of alternating dense and less dense layers. Most sex cords were populated by mature Sertoli cells and small pleomorphic elements resembling monocytic-derived macrophages. Within some cords, the macrophages aggregated into a central mass with which identifiable Sertoli cells and (PAS) periodic acid Schiff-positive fragments of basal lamina were associated. In more severely damaged cords, the basal lamina and peripheral carpet of Sertoli cells were totally missing. Such cords were populated only the the central macrophages with fragments of basal lamina and degenerating Sertoli cells. Finally, a few collapsed remnants of cords contained compact nodules of macrophages surrounded by what appeared to be the outer part of the tunica propria. The interstitial area, as well as the outer walls of the seminiferous cords were also heavily infiltrated by macrophages. Overall, the morphological picture was one of severe immunological injury. We do not know what role, if any, the genetic constitution and/or intra-abdominal environment may play in the expression of these bizarre pathologies. However, such severe changes have not been reported in either Klinefelter's syndrome or the undescended testes of any human or subprimate species.

Animals↗
PubMed1969

Simplified method for the production of carbohydrate antigen from Neisseria meningitidis.

The Gotschlich procedure for the production of carbohydrate antigens from the supernatant fluids of cultures of Neisseria meningitidis groups A and C was modified. Steps involving digestion with nucleases and gel filtration through Sephadex G-50 were added, the number of extractions was greatly reduced, and high-speed centrifugations were eliminated. The antigens thus obtained appeared to be entirely comparable to those described by Gotschlich et al. in physical, chemical, and antigenic properties. A slight degree of protection of mice was repeatedly demonstrated with extraordinarily large doses of antigen (50 mug/mouse), but not with smaller doses. Toxicity of the antigens for laboratory animals was very slight.

Absorption↗
PubMedDate not supplied

Evaluation of an immunoisolation membrane formed by incorporating a polyvinyl alcohol hydrogel within a microporous filter support.

An immunoisolation membrane formed by incorporating a high water content polyvinyl alcohol (PVA) hydrogel into a microporous polyether sulfone (PES) filter has been investigated in this study. The PVA hydrogel is formed in situ within the filter pores via glutaraldehyde (GA) crosslinking under acidic conditions. The tortuous nature of the microporous filter pores securely anchors the embedded hydrogel to provide excellent structural integrity. The high void fraction of the PES filter support (>80%) and high water content of the PVA hydrogel (>85% water by weight) allow excellent solute transport rates, while an appropriate level of glutaraldehyde crosslinking supplies the required molecular size selectivity. In vitro permeability measurements made with solutes covering a wide range of molecular sizes demonstrate high transport rates for small nutrient molecules with rapidly diminishing permeabilities above a molecular weight of approximately 1,000 Dalton. Implantation experiments show that the membrane properties are not deleteriously affected by prolonged in vivo exposure or common sterilization techniques. Thus, this hybrid hydrogel/filter membrane system offers a promising approach to the immunoisolation of implanted cells.

Animals↗
PubMedDate not supplied

[Right pulmonary artery-left atrium communication : a rare cause of refractory hypoxia in newborn infants].

Two cases of right pulmonary artery to left atrium in the newborn are described. Both patients presented with refractory hypoxemia cardiomegaly, hypovascular lung fields. Moreover one patient presented with continuous murmur and localised X-ray shadow. Echocardiographic left atrium enlargement suggested diagnosis and angiography confirmed it. Spontaneous improvement in one child is due to a decrease in pulmonary vascular resistance and has allowed the patient to attain an age and a weight in which surgical ligation has been performed more safely.

Abnormalities, Multiple↗