As a result of the low yield of cartilage from primary patient harvests and a high demand for autologous cartilage for reconstructive surgery and structural repair, primary explant cartilage must be augmented by tissue engineering techniques. In this study, chondrocytes seeded on PLLA/PGA scaffolds in static culture and a direct perfusion bioreactor were biochemically and histologically analyzed to determine the effects of fluid flow and media pH on matrix assembly. A gradual media pH change was maintained in the bioreactor within 7.4-6.96 over 2 weeks compared to a more rapid decrease from 7.4 to 6.58 in static culture over 3 days. Seeded scaffolds subjected to 1 microm/s flow demonstrated a 118% increase (p < 0.05) in DNA content, a 184% increase (p < 0.05) in GAG content, and a 155% (p < 0.05) increase in hydroxyproline content compared to static culture. Distinct differences were noted in tissue morphology, including more intense staining for proteoglycans by safranin-O and alignment of cells in the direction of media flow. Culture of chondrocyte seeded matrices thus offers the possibility of rapid in vitro expansion of donor cartilage for the repair of structural defects, tracheal injury, and vascularized tissue damage.

Bioreactors↗

PubMedDate not supplied

Macroscopic geometric heterogeneity effects in radiation dose distribution analysis for boron neutron capture therapy.

Calculations of radiation flux and dose distributions for boron neutron capture therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This paper describes such a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for the tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for this model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous-tissue model. Comparison of the results showed that peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10%-20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.

Animals↗

PubMedDate not supplied

Biochemical and histopathological findings after a long-term intraperitoneal fat infusion. An experimental study in rats.

The object of this work was to see the possible side effects that a long-term intraperitoneal (IP) fat infusion would have. We used 56 female Wistar rats weighing 250 g, divided into a control group (CG) of eight and three groups of 16 in each one. These three groups were administered a 20% Intralipid infusion in a daily amount of 4 g/kg over 5, 10, and 15 days, respectively (groups I, II, and III) intraperitoneally. Twenty-four hr after the last infusion the animals were anesthetized and after having drawn 3 ml of blood, 5% glutaraldehyde (GTH) was instilled in situ and optical and electron microscopic specimens were taken of the lung, liver, right diaphragm, and parietal peritoneum. The results show a decrease in triglyceride (TG) rate 24 hr after the last infusion in each group, but blood glucose, cholesterol, bilirubin, glucose oxidase test (GOT), glutamic pyruvic transaminase (GPT), nor other serum parameters varied. No alterations were noticed in the lung or liver under optical or electron microscopes in the groups than had under gone treatment, except for an increase in circulating macrophages with fat in the lung. In the diaphragm we observed hyperplasia in the serous layer of the peritoneum and an increase in fat in the lymphatic channels of the right diaphragm. The possibility of using IP infusions in order to study parenteral nutrition solutions was put forward as well as their possible clinical use in alternative nutrition techniques on both a short-term and long-term basis.

Animals↗

PubMedDate not supplied

Long term peritoneal nutrition in dogs, both normal and after intestinal resection.

We carried out total and prolonged peritoneal nutrition (PN) in a group of healthy dogs and in another group that had previously undergone an 80% resection of the small intestine. A third group of animals underwent the same operation but did not receive intraperitoneal nutrition, as they formed the control group. A nutritive mixture was used, composed of glucose fat emulsion, aminoacids, ions, trace elements, insulin and vitamins. The caloric rate was 45 kcal/kg/day. Peritoneal nutrition lasted 30 days. Periodical clinical controls were made for biochemical, hematological, microbiological and histopathological analyses. We found two episodes of peritonitis out of a total of 19 dogs subjected to PN. Hyper- and hypoglycemia occurred in the animals with PN and that had not undergone intestinal resection there were also increases in triglyceride, free fatty acid and cholesterol levels as well as a reduction of albumin. We observed a greater decrease in albumin and urea nitrogen and a greater weight loss in the animals underwent intestinal resection. The quantity absorbed was greater than 95% of the volume infused over the four week period. In all the animals subjected to PN we found hyperplasia and phagocytic phenomena in the peritoneal mesothelium cells after 30 days of peritoneal nutrition, symptoms which disappeared one month after this kind of nutrition was stopped.

Animals↗

PubMedDate not supplied

Long-term peritoneal nutrition in dogs: metabolic and histopathologic results.

In order to test the use of the peritoneal cavity in prolonged nutrition, seven dogs were fed for 22 days via peritoneal catheter. The nutritive preparations were composed of 10% crystalline amino acids, 20% fat emulsion, 40% glucose, trace elements, Na+, K+, insulin and a multivitamin compound. The caloric rate was 45kcal/kg/24h plus 0.5g/kg/24h of amino acids. These animals were compared to another group of six dogs, which were catheterized and infused with a 3% saline solution in addition to an oral intake of 45kcal/kg/24h. Both groups had free use of water. There was a case of slight peritonitis in one dog on peritoneal nutrition but no deaths and no weight changes occurred throughout the experiment. Increases in serum levels of TG, FFA and cholesterol were observed in the animals treated with peritoneal nutrition as well as a decrease in albumin serum levels. Peritoneal hyperplasia and phagocytosis were noted in the animals on peritoneal nutrition but no damage was recorded in other organs.

Animals↗

PubMedDate not supplied

Peritoneal nutrition in dogs after intestinal resection: comparative study.

A total of 18 adult dogs were kept on peritoneal nutrition (PeN) for 30 days via peritoneal catheter. Eleven dogs were put on peritoneal nutrition immediately, receiving a caloric rate of 45 kcal/kg per day, half of which was supplied by glucose and the other half by 20% intralipid, along with 0.5 g/kg per day of protein, as well as ions, trace elements, and vitamins. Two-thirds of the glucose was administered separately. Seven other animals underwent an 80% resection of the small intestine and were kept on special oral nutrition for 6 weeks. After this time, peritoneal nutrition was applied with the same caloric rate as in the previous group but with a protein dose of 1 g/kg per day and administration of the nutrients every 6 hours. We found two cases of peritonitis in the group without intestinal resection, whereas no infectious outbreaks occurred in the group subjected to intestinal resection. This group showed an exacerbated nutritional state, with a consequently greater loss of weight and albumin and a negative nitrogen balance. The peritoneal membrane showed signs of cellular hyperplasia and hypertrophy following peritoneal nutrition. These phenomena disappeared 1 month after PeN was terminated.

Animals↗

PubMedDate not supplied

Initial clinical experience with a more efficient hollow fiber oxygenator of unique design.

The first 90 cardiac surgery cases perfused with a new hollow fiber membrane oxygenator in which the gas flows through the fibers and blood flows around the fibers are reported. The fibers are microporous polypropylene with a pore size of 0.03 microns. Membrane surface area is 2.0 M2 and priming volume is 480 ml, including heat exchanger PaO2 is controlled by FIO2 and PaCO2 by gas flow rate. Patients as large as 2.36 M2 were perfused up to 348 min using hemodilution and hypothermia. The mean PaO2 was 200 mmHg and the mean PaCO2 39.5 mmHg. Oxygen transfer was as high as 230 ml/min. This low prime device transfers large volumes of gas, an efficiency which results from a crossed arrangement of the fibers to break up laminar flow of the blood around them. The low priming volume makes it appropriate for use in all but the smallest patients.

Adult↗

PubMedDate not supplied

Direct measurement of unilateral renal blood flow by dye dilution method.

Explore the source record for details and available documents.

Aminohippuric Acids↗