Biomedical subjects

Amir Kaviani

Publications and source records attributed to Amir Kaviani.

11 recordsLinked to original sources

PubMed2006

Diaphragmatic repair through fetal tissue engineering: a comparison between mesenchymal amniocyte- and myoblast-based constructs.

PURPOSE: We have previously shown that fetal tissue engineering is a preferred alternative to diaphragmatic repair in a large animal model. This study was aimed at comparing diaphragmatic constructs seeded with mesenchymal amniocytes and fetal myoblasts in this model. METHODS: Neonatal lambs (n = 14) underwent repair of an experimental diaphragmatic defect with identical scaffolds, either seeded with labeled autologous cells (mesenchymal amniocytes in group 1 and fetal myoblasts in group 2) or as an acellular graft (group 3). At 1 to 12 months postoperatively, implants were harvested for multiple analyses. RESULTS: Repair failure (reherniation or eventration) was significantly higher in group 3 than in groups 1 and 2, with no difference between groups 1 and 2. Seeded fetal myoblasts quickly lost their myogenic phenotype in vivo. All grafts contained cells with a fibroblastic-myofibroblastic profile. Elastin concentrations and both modular and ultimate tensile strengths were significantly higher in group 1 than in groups 2 and 3. There were no differences in glycosaminoglycans and type I collagen levels among the groups. CONCLUSIONS: Diaphragmatic repair with a mesenchymal amniocyte-based engineered tendon leads to improved structural outcomes when compared with equivalent fetal myoblast-based and acellular grafts. The amniotic fluid is a preferred cell source for tissue-engineered diaphragmatic reconstruction.

Animals↗

PubMed2006

Infected carotid pseudoaneurysm and carotid-cutaneous fistula as a late complication of carotid artery stenting.

Carotid stenosis after neck irradiation is a well-described entity. A 78-year-old man presented with left eye amaurosis fugax 11 years after radical neck dissection and neck irradiation for mucoepidermoid carcinoma. The patient underwent carotid artery stenting for a high-grade stenosis of the left internal carotid artery. Twenty months after the procedure, a pulsatile neck mass developed with intermittent arterial bleeding. After control of the bleeding, he underwent resection of the left carotid bifurcation, including the indwelling stent and reconstruction with a saphenous vein interposition graft. A pectoralis myocutaneous flap was used for wound closure. In this case, localized infection of the stented carotid artery led to mycotic degeneration, pseudoaneurysm formation, and erosion to the skin surface. As carotid artery stenting becomes more widely used, previously unreported late complications associated with this procedure are likely to become apparent, and continued close follow-up is warranted.

Aged↗

PubMed2006

Current status of branched stent-graft technology in treatment of thoracoabdominal aneurysms.

Endovascular aortic aneurysm repair has been established as an alternative to open surgical reconstruction in appropriately selected patients. Until recently, this approach has been limited to aneurysms not involving critical aortic branches due to the complex nature of designing devices that would preserve important end-organ flow. This article reviews the current status of endovascular approaches to aneurysms involving the thoracoabdominal aorta. The evolution of fenestrated devices and further developments, including reinforced fenestrated branched grafts and directional branches for more complex aneurysms are discussed.

Aged↗

PubMed2005

Intratracheal pulmonary ventilation improves gas exchange during laparoscopy in a pediatric lung injury model.

BACKGROUND/PURPOSE: This study was aimed at determining whether intraoperative intratracheal pulmonary ventilation (ITPV) could prevent/treat respiratory complications of laparoscopy in a model of pediatric pulmonary insufficiency. METHODS: Severe lung injury was induced in 0- to 2-month-old lambs (n = 5) by endotracheal saline lavage. Animals then underwent establishment of CO2 pneumoperitoneum. Intraperitoneal pressures were progressively raised from 0 to 15 mm Hg, at intervals of 5 mm Hg. At each interval, blood gas and hemodynamic data were recorded, 20 minutes after initiation of both conventional ventilation and pure ITPV. All ventilatory parameters were constant and identical on both modes of ventilation. RESULTS: On conventional ventilation, severe respiratory acidosis and hypoxemia ensued at intraperitoneal pressures of 5 mm Hg and 10 mm Hg or more, respectively. Compared with conventional ventilation, ITPV led to statistically significant decreases in PCO2 at intraperitoneal pressures of 5 mm Hg (43.2 +/- 5.2 vs 56.1 +/- 6.6 mm Hg) and 10 mm Hg (45.1 +/- 3.2 vs 61 +/- 6.3 mm Hg) and to significant increases in PO2 at 10 mm Hg (92 +/- 10.2 vs 61 +/- 8.1 mm Hg), resolving the acidosis and hypoxemia at those pressure levels. CONCLUSIONS: Compared with conventional ventilation, ITPV improves both CO2 removal and oxygenation during CO2 pneumoperitoneum in a pediatric lung injury model. Intratracheal pulmonary ventilation may be a safer intraoperative mode of ventilation for neonates and children with respiratory failure who require laparoscopy.

Acidosis, Respiratory↗

PubMed2004

Diaphragmatic reconstruction with autologous tendon engineered from mesenchymal amniocytes.

PURPOSE: This study examined the effects of amniocyte-based engineered tendons on partial diaphragmatic replacement. METHODS: Ovine mesenchymal amniocytes were labeled with green fluorescent protein (GFP), expanded, and seeded into a collagen hydrogel. Composite grafts (20 to 25 cm2) based on acellular dermis (group I), or acellular small intestinal submucosa (group II) received either a cell-seeded or an acellular hydrogel within their layers. Newborn lambs (n = 20) underwent partial diaphragmatic replacement with either an acellular or a cellular autologous construct from either group. At 3 to 12 months' postoperatively, implants were subjected to multiple analyses. RESULTS: Diaphragmatic hernia recurrence was significantly higher in animals with acellular grafts (5 of 5) then in animals with cellular ones (1 of 4) in group I (P <.05) but not in group II (3 of 6 and 4 of 5, respectively). Cellular grafts had higher modular (5.27 +/- 1.98 v. 1.27 +/- 0.38 MPa) and ultimate (1.94 +/- 0.70 v. 0.29 +/- 0.05 MPa) tensile strength than acellular implants in group I (P <.05), but not in group II. Quantitative analyses showed no differences in extracellular matrix components between cellular and acellular implants in either group. All cellular implants showed GFP-positive cells. CONCLUSIONS: Diaphragmatic repair with an autologous tendon engineered from mesenchymal amniocytes leads to improved mechanical and functional outcomes when compared with an equivalent acellular bioprosthetic repair, depending on scaffold composition. The amniotic fluid may be a preferred cell source for engineered diaphragmatic reconstruction.

Amniotic Fluid↗

PubMed2004

In situ inhibition of uterine activity by indomethacin: possible relevance to preterm labor prevention after fetal surgery.

PURPOSE: This report is an analysis of the effects of local indomethacin delivery on uterine activity in vitro. METHODS: Isolated strips of time-dated pregnant rats' myometrium were placed within controlled tissue baths. Spontaneous muscular activity was recorded by a force transducer connected to a polygraph at cumulative concentrations of indomethacin. Statistical analysis was by single-factor analysis of variance (ANOVA), with P values of less than.05 considered significant. RESULTS: Within a narrow concentration range, the effects of indomethacin on frequency and amplitude of myometrial contractions were nonmonotonic, with an increase in frequency at levels that began to depress amplitude. However, both amplitude and frequency were significantly depressed and eventually totally abolished at most concentrations studied (P <.05). CONCLUSIONS: Indomethacin administered in situ consistently inhibits or completely arrests overall myometrial activity. The concept of local myometrial delivery of indomethacin, possibly via slow release systems, may prove clinically useful as an adjuvant to its systemic administration in preterm labor prevention after fetal surgery, warranting further trials in vivo.

Animals↗

PubMed2004

The Zenith AAA endovascular graft.

The Zenith endovascular graft is the culmination of a worldwide collaboration of experts whose experience and developments were compiled, resulting in an endovascular prosthesis designed to treat infrarenal abdominal aortic aneurysms. The device is made of stainless steel, self-expanding Z-stents and polyester fabric. It has an uncovered stent with barbs (for fixation) that extend into the suprarenal aorta and is modular in design and allows for disparity in the length and diameter of the iliac arteries that are incorporated into the repair. A prospective study contrasting endovascular and open surgical patients was completed in 2002 and resulted in US Food and Drug Administration approval of the device for commercial sale within the USA. Although long-term data from the trial are still being evaluated, the worldwide experience with this device and its predicate devices has allowed for certain conclusions to be made with respect to performance expectations and aneurysm sac behavior. The periprocedural mortality in healthy patients with anatomy meeting the device instructions for use should be under 2%. The expected risk of endoleak (mostly Type II) was 7.4% at 12 months and 5.4% at 24 months. Migration (based on the reporting standards for endovascular aneurysm repair recommended by the vascular surgical societies, published in the Journal of Vascular Surgery in 2001) was not seen in any patients over 12 months. The majority of the aneurysms shrink at 1 and 2 years, and any patient exhibiting aneurysm growth had a detectable cause and required treatment. Coupled with European and Australian data, including several device explants, the device integrity issues are limited to barb separation (which has about a 2% incidence and appears incidental in the US trial) and suprarenal stent detachment (six cases detected worldwide). In order to address the latter problem, a design alteration was implemented with a double suture attachment, significantly increasing the tensile strength of the device. No separations have been noted since the change instituted at the conclusion of the US trial.

Angioplasty↗

PubMed2003

Trophic enteral nutrition increases hepatic glutathione and protects against peroxidative damage after exposure to endotoxin.

BACKGROUND: During total parenteral nutrition (TPN), hepatic concentration of the important intracellular antioxidant glutathione (GSH) is decreased. This study sought to determine whether enteral trophic (small quantity) feeding of GSH precursors would increase hepatic GSH levels during TPN and result in decreased peroxidative injury after endotoxin exposure. METHODS: Sprague-Dawley rats received full TPN for 7 days with postpyloric infusions of either (1) amino acid GSH precursors (cysteine, 60 mg/d; glycine, 86 mg/d; glutamate, 31 mg/d; F1); (2) iso-nitrogenous alanine (132 mg/d; F2); or (3) normal saline (SA). Hepatic GSH concentration was measured by gas chromatography/mass spectrometry. In a parallel study, animals were given TPN and either F1 or SA for 7 days, and endotoxin was administered intravenously before death. Hepatic lipid peroxidation and histology were assessed. RESULTS: Hepatic GSH concentration measured 11.7 +/- 0.6 micromol/g in F1. This was significantly higher (P <.001) than in F2 (7.0 +/- 0.8 micromol/g) or SA (5.0 +/- 0.4 micromol/g). F2 and SA were not significantly different. Hepatic malondialdehyde concentration after exposure to endotoxin was significantly higher in SA (10.36 micromol/g +/- 0.65) than in F1 (7.38 micromol/g +/- 0.77; P <.01). All SA animals had histologic evidence of hepatic necrosis, whereas none of the F1 group showed these changes. CONCLUSIONS: Targeted trophic feeding of GSH amino acid precursors during parenteral nutrition markedly increased hepatic GSH concentration. This was associated with decreased lipid peroxidation and enhanced hepatocellular protection after endotoxin challenge. Thus, targeted trophic feedings may aid in the prevention of TPN-related liver disease.

Amino Acids↗

PubMed2003

Fetal tissue engineering from amniotic fluid.

BACKGROUND: We have recently shown, in an animal model, that amniotic fluid can be a source of cells for fetal tissue engineering. This study was aimed at determining whether fetal tissue constructs could also be engineered from cells normally found in human amniotic fluid. STUDY DESIGN: Cells obtained from the amniotic fluid of pregnant women at 15 to 19 weeks of gestation (n=6) were cultured in Dulbecco's Modified Eagle's medium (Sigma Chemical, St Louis, MO) containing 20% fetal bovine serum and 5 ng/mL basic fibroblast growth factor in a 95% humidified, 5% CO(2) chamber at 37 degrees C. A subpopulation of morphologically distinct cells was then mechanically isolated from the rest and selectively expanded. The lineage of this subpopulation of amniocytes was determined by immunofluorescent staining with antibodies against standard intermediate filaments and surface antigens. Cell proliferation rates were determined by oxidation assay. After cell expansion, colonies of amniocytes were statically and dynamically seeded onto both unwoven, 1-mm-thick polyglycolic acid polymer scaffold and acellular human dermis for 72 hours. The resulting constructs were analyzed by scanning electron microscopy. RESULTS: Amniocytes stained positively for smooth muscle actin, vimentin, cytokeratin 18, and fibroblast surface protein, and negatively for desmin, cluster of differentiation 31, and von Willebrand's factor (Dako, Carpenteria, CA). These findings are consistent with a mesenchymal, fibroblast-myofibroblast cell lineage. Mesenchymal amniocytes could be rapidly expanded in culture, based on results of the proliferation assay. Scanning electron microscopy of amniocyte constructs revealed dense, confluent layers of cells surrounding the polymer matrices and firm cell adhesion to both PGA and Alloderm (Lifecell Corp, Branchburg, NJ) scaffolds. No evidence of cell death was observed. CONCLUSIONS: Subpopulations of fetal mesenchymal cells can be consistently isolated from human amniotic fluid and rapidly expanded in vitro. Human mesenchymal amniocytes attach firmly to both polyglycolic acid polymer and acellular human dermis. The amniotic fluid can be a valuable and practical cell source for fetal tissue engineering.

Amniotic Fluid↗

PubMed2002

The placenta as a cell source in fetal tissue engineering.

PURPOSE: This study was aimed at determining whether fetal tissue constructs can be engineered from cells derived from the placenta. METHODS: A subpopulation of morphologically distinct cells was isolated mechanically from specimens of human placenta (n = 6) and selectively expanded. The lineage of these cells was determined by immunofluorescent staining against multiple intermediate filaments and surface antigens. Cell proliferation rates were determined by oxidation assays and compared with those of immunocytochemically identical cells derived from human amniotic fluid samples (n = 6). Statistical analysis was by analysis of variance (ANOVA). After expansion, the cells were seeded onto a polyglycolic acid polymer/poly-4-hydroxybutyrate scaffold. The resulting construct was analyzed by both optical and scanning electron microscopy. RESULTS: The immunocytochemical profile of expanded placental cells was consistent with a nontrophoblastic, mesenchymal origin. Their proliferation rate in culture was not significantly different when compared with mesenchymal fetal cells isolated from human amniotic fluid; however, it was greater than previously reported rates for similar cells obtained from postnatal or adult tissues. Construct analysis showed dense layers of cells firmly attached to the scaffold without evidence of cell death. CONCLUSIONS: Subpopulations of nontrophoblastic, mesenchymal cells can be isolated consistently from the human placenta. These cells proliferate as rapidly as fetal mesenchymal amniocytes in vitro and attach firmly to polyglycolic acid scaffolds. The placenta can be a valuable and practical source of cells for the engineering of select fetal tissue constructs.

Cells, Cultured↗

PubMed2002

Positive intrapulmonary oncotic pressure enhances short-term lung growth acceleration after fetal tracheal occlusion.

PURPOSE: This study was aimed at determining whether positive oncotic pressure induced in the fetal lung liquid could safely maximize accelerated lung growth after tracheal occlusion. METHODS: Fetal lambs (n = 21) were divided into 4 groups: group I (n = 5) consisted of sham-operated controls; group II (n = 5) underwent simple tracheal occlusion (TO); group III (n = 5) received TO and 60 mL of saline injected into the trachea; and group IV (n = 6) underwent TO and intratracheal infusion of 60 mL of iso-osmotic, 6% Dextran 70. All fetuses were delivered near term, at a mean of 15.9 +/- 1 days postoperatively. Their lungs were studied by standard morphometric techniques, and the basic chemical profile of the lung liquid was analyzed. Statistical comparisons were by 1-way analysis of variance (ANOVA) and post-hoc analyses by the Bonferroni correction for multiple comparisons, with P values less than.05 considered significant. RESULTS: The lung volume-to-body-weight ratio (LV:BW) was significantly different among groups. Pairwise comparisons of LV:BW showed that it was higher in group IV than in all other groups, but there was no difference between groups II and III. Airspace fraction was not significantly different among groups, and histologic appearance was normal in all lung samples. There were no differences in lung liquid osmolarity, pH level, and electrolyte concentrations. CONCLUSION: Positive intrapulmonary oncotic pressure by an isosmotic agent boosts short-term lung growth acceleration after fetal tracheal occlusion with no evidence of cell damage.

Animals↗