Improved adherence of genetically modified endothelial cells to small-diameter expanded polytetrafluoroethylene grafts in a canine model

PURPOSE: A significant limitation to using genetically modified endothelial cells (ECs) to seed prosthetic grafts before implantation has been poor cell adherence to the graft lumen. Methodologic changes to improve cell adherence were evaluated in a canine carotid interposition graft model using 4 mm interior diameter expanded polytetrafluoroethylene. METHODS: ECs harvested from external jugular veins were grown in culture, with 80% of the cells from each culture transduced by incubation with an LXSN-type retroviral vector carrying a gene for human prourokinase and a neomycin resistance gene for selection in antibiotic G418. Control grafts had passive luminal coating with fibronectin and were seeded with transduced ECs immediately after G418 selection; these grafts were incubated for 2 days before implantation. Experimental grafts had fibronectin forcefully squeezed through the interstices and were seeded with ECs that had recovered in culture for 5 days after G418 selection; these grafts were incubated for 4 days before implantation. For each control (n = 9) and experimental (n = 12) graft, a graft prepared in the same fashion but seeded with the remaining autologous nontransduced cells was placed in the contralateral carotid artery. Grafts were explanted after 30 days and were evaluated for patency, thrombus-free surface area, and cell-free surface area. RESULTS: No significant differences in patency rates were seen between any groups. The thrombus-free surface area was improved for experimental grafts (90%) compared with control grafts (76%), but this improvement did not achieve statistical significance. The cell-free surface area for transduced cells on experimental grafts was 65% compared with 96% for control grafts (p = 0.021) and was comparable with that for nontransduced cells on both control grafts (62%) and experimental grafts (51%; p = 0.201). CONCLUSIONS: Adherence of genetically modified endothelial cells to small-diameter expanded polytetrafluoroethylene grafts in an in vivo physiologic flow model is significantly improved when cells have a more prolonged recovery from G418 selection, when the graft lumen is more uniformly coated with fibronectin before EC seeding, and when seeded grafts are left longer in culture before implantation to develop cell lining stability. The short-term patency rate of these seeded grafts is not affected by increased cell retention; long-term graft patency data and luminal healing require further evaluation.     

Use of expanded polytetrafluoroethylene grafts for vascular access in hemodialysis: laboratory and clinical evaluation

Vascular access for chronic hemodialysis has evolved considerably over the past 10 years with development of vascular substitutes. The bovine heterograft is the choice of most dialysis centers when a subcutaneous conduit is needed in lieu of an in situ arteriovenous fistula. Bovine grafts have solved some problems, but further improvement in blood access prostheses is needed. Polytetrafluoroethylene (PTFE) grafts were evaluated in a laboratory and clinical study. In animals, PTFE proved to be satisfactory for fistula construction based on patency, incorporation into tissue, and ease of puncture. Ten patients underwent 11 vascular access procedures using PTFE grafts as a conduit. There were no technical operative complications. One graft was occluded by extravasation during dialysis and flow could not be restored. Otherwise, all grafts are patent 9 to 18 months postoperatively. Grafts of 8.0 mm in diameter have not given desirable flow rates, whereas 6.0 mm grafts have. Prolonged bleeding from puncture has been a problem in some cases. Otherwise, PTFE appears to be a satisfactory conduit for hemodialysis vascular access.     

Clinical trial of new polyurethane vascular grafts for hemodialysis: compared with expanded polytetrafluoroethylene grafts

We developed a new polyurethane vascular access graft coated with gelatin and reinforced with knitted polyester fibers (PE-PEUG). Advantages over expanded-polytetrafluoroethylene graft (E-PTFEG) were previously reported in experimental studies. Between May 1990 and August 1992, 39 PE-PEUGs including 34 loop and 5 straight and 18 E-PTFEGs including 18 loop were implanted to create arteriovenous (AV) fistulas in a total of 52 adult patients on maintenance hemodialysis (HD). They were followed up until October 1994. Hemostasis on the suture line was achieved within 3 min in all patients implanted with PE-PEUGs. Bleeding from the needle holes of PE-PEUG stopped within 10 min with gentle finger pressure. Minimal local edema developed in only a few patients implanted with PE-PEUG while most patients implanted with E-PTFEG developed moderate local edema. One seroma formation was found in an E-PTFE case. Aneurysmal dilatations were observed twice in a PE-PEUG patient 9 and 17 months after the implantation and once in a E-PTFEG patient 2 years after the implantation. The cumulative patency rate at 1 year in the PE-PEUG and E-PTFEG groups were 53.2 and 70.8%, respectively. Our clinical study showed that the PE-PEUG had several advantages over E-PTFEG: prompt hemostasis, no persistent edema and no formation of seroma, no change in elasticity, and sufficient mechanical strength. However, the cumulative patency rate was inferior to that with E-PTFEG implanted in our series. Further modifications are therefore necessary to improve the patency rate.     

Effects of omental wrap on performance of small-caliber high-porosity expanded polytetrafluoroethylene grafts

The purpose of this study was to evaluate the effects of omental wrap on the performance of small-caliber expanded polytetrafluoroethylene (ePTFE) grafts, with a special reference to transmural capillary ingrowth. High-porosity ePTFE grafts with a fibril length of 60 micrometer, an internal diameter of 4 mm, and 40 mm in length were implanted into the canine bilateral carotid arteries. The grafts on the right side were wrapped in an omental pedicle flap (omentum-wrap grafts), while those on the left were not (nonwrap grafts). The grafts were retrieved at intervals of 4 and 12 weeks. At 4 weeks, the patency rates of the omentum-wrap grafts and nonwrap grafts were almost the same (5/6 vs 6/6). At 12 weeks, patency tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (3/5 vs 1/5). At 4 weeks, the thrombus-free surface score (TFS) was significantly higher in the omentum-wrap grafts than in the nonwrap grafts (44.8% vs 30.2%, P < 0.05). At 12 weeks, the TFS tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (84.6% vs 62.4%). At 4 weeks, both the capillary transsectional area score (CTS) and capillary density were significantly higher in the omentum-wrap grafts than in the nonwrap grafts (CTS, 3.3% vs 1.1%, P < 0.05; capillary density, 196.0/mm2 vs 83.3/mm2, P < 0.05). At 12 weeks, both CTS and capillary density tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (CTS, 1.1% vs 0%; capillary density, 69.4/mm2 vs 0/mm2). At 4 weeks, in the omentum-wrap grafts, extracellular matrices and cells in the interstices of the graft were stained with an antibody against VEGF. In conclusion, the omental wrap enhances transmural capillary ingrowth and thereby promotes endothelialization in small-caliber high-porosity ePTFE grafts. VEGF appears to play an active role in transmural capillary ingrowth enhanced by omental wrap.     

A comparison of CORVITA and expanded polytetrafluoroethylene vascular grafts implanted in the abdominal aortas of dogs

The utility of CORVITA vascular grafts, composed of an inner layer of meshed polyurethane fibers and an outer layer of meshed Dacron reinforcement, for replacement of the abdominal aorta was assessed in a canine model and compared with expanded polytetrafluoroethylene (ePTFE) grafts. CORVITA or ePTFE vascular grafts were implanted and left in place for 3 or 6 months. After removal, they were inspected macroscopically and histologically. Microspectrophotometry was used to quantify smooth muscle cells (SMCs), elastin (EL), and collagen (CL) in the media of the native artery. The patency rate of the CORVITA grafts after 6 months was 100%, whereas that of the ePTFE grafts was only 50%. Moreover, stenoses were apparent in all of the ePTFE grafts, but in only 43% of the CORVITA grafts. The intimal thickness at the distal anastomosis was significantly greater at 3 months in the ePTFE grafts (P < 0.01), and there were significantly more SMCs in the host arterial media at the proximal and distal anastomoses in these grafts. Thus, better long-term patency can be expected with CORVITA grafts than with ePTFE grafts. This conferred advantage is most likely attributable to the less pronounced intimal hyperplasia which results from the proliferation of SMCs in the media of the native artery.     

Prophylactic balloon angioplasty fails to prolong the patency of expanded polytetrafluoroethylene arteriovenous grafts: results of a prospective randomized study

PURPOSE: Maintenance of hemodialysis access grafts represents an enormous social and clinical problem. Current grafts and graft salvage techniques are inadequate. Consequently, there has been increasing interest in the use of minimally invasive catheter techniques to prophylactically treat stenoses in functioning arteriovenous grafts. Prophylactic balloon angioplasty has been widely suggested as prolonging assisted primary patency. We have performed a prospective randomized trial to compare patients who underwent percutaneous transluminal angioplasty (PTA) for graft stenoses > 50% with a control group that received no intervention. Our hypothesis was that to be efficacious a minimal benefit of 20% prolongation in patency would be necessary. METHODS: Color flow duplex scanning was used to detect > 50% stenoses in functioning expanded polytetrafluoroethylene grafts. Patients were then subjected to confirmatory angiographic evaluation. Those who had angiographic stenoses > 50% were randomized to balloon angioplasty or observation. Patients were followed-up with duplex scanning every 2 months. Statistical analysis was performed using the Kaplan-Meier technique. Although demographically the patient groups were well matched, there were more prior interventions and concurrent central stenoses in the treatment group. Outcomes were graft thrombosis, graft dysfunction that precluded dialysis, and six or more PTA procedures within 18 months. RESULTS: In the treatment and observation groups, the 6-month patency rates were 69% +/- 7% and 70% +/- 7%, respectively. The 12-month patency rates for the treatment and observation groups were 51% +/- 6% and 47% +/- 4%, respectively. There was no significant difference between these two groups (p = 0.97), with an 80% confidence limit for detection of a difference greater than 20%. CONCLUSIONS: This study demonstrates that a generic approach of PTA to treat all polytetrafluoroethylene grafts with stenoses > 50% does not prolong patency and cannot be supported.     

In vitro evaluation of cell/biomaterial interaction by MTT assay

The nonlinear propagation of ultrasound was demonstrated using Doppler transducers on two commercial duplex machines. The influence of nonlinear propagation on Doppler measurements was studied on both a flow phantom and a string phantom. It was found that although the pulse waveforms showed clearly different degrees of nonlinear distortion, no effect due to the nonlinearity could be detected on the received Doppler spectrum both in terms of the maximum frequency or underlying Doppler spectral profile.     

In vitro assessment of a collagen sponge for engineering urothelial grafts

OBJECTIVE: To investigate the deposition of urinary crystals and the growth characteristics of urothelial cells on a collagen sponge, as a preliminary step in engineering urothelial autologous grafts. MATERIALS AND METHODS: Collagen sponges were exposed to a continuous flow of urine at pH 5.3 and 6.3 for 1 week. The sponges were examined microscopically for crystal deposition and analysed for their calcium content. Two cell lines, RT112, derived from a well-differentiated transitional cell carcinoma, and UROtsa, an immortalized urothelial cell line, were seeded on the collagen sponges. Cells were cultured for 6, 12 and 21 days. The pattern of growth was analysed by histology and immunostaining with a pan-cytokeratin antibody. Growth was assayed to quantify cell proliferation on the sponges. RESULTS: No crystals were evident on any of the collagen sponges. Calcium deposition was negligible at pH 5.3. Although calcium levels were measurable at pH 6.3, the levels were very low. Both cell lines attached and grew in a stratified manner on the collagen sponge, RT112 forming a layer 6-8 cells thick, and UROtsa a layer 4-6 cells thick; cell proliferation was maximal at 5-10 days. The sponge remained easy to handle after 3 weeks in culture. CONCLUSION: These findings show that collagen sponges support the growth and stratification of urothelial cells, and indicate that the collagen sponge is a suitable substrate for developing urothelial autologous grafts.     

In vitro evaluation of inflammatory cell response after CF4 plasma surface modification of poly(methyl methacrylate) intraocular lenses

Nasal intermittent positive pressure ventilation (NIPPV) provides effective ventilatory support in patients with nocturnal hypoventilation. Nasal pressure support ventilation (NPSV), which only provides ventilation in response to patient triggering, may also be effective, simpler, and cheaper, but has not been evaluated. NIPPV and NPSV were compared in 12 patients with nocturnal hypoventilation, requiring domiciliary ventilatory support. The patients were studied on three consecutive nights, in random order: a control night without ventilation and a night on each mode of ventilatory support using the bilevel positive airway pressure (BiPAP) ventilator. Both NIPPV and NPSV significantly increased mean arterial oxygen saturation (SaO2) compared to the control night (NIPPV mean increase 4.1%; 95% confidence interval (CI) 2.2 to 6.1, NPSV 4.4%; CI 2.1 to 6.6) with no significant difference between the two modes. The percentage of the study night spent below 90% SaO2 was significantly reduced by both ventilator modes compared to the control night (median reduction on NIPPV 37%; CI -54 to -10, reduction on NPSV 31%; CI -53 to -9, with no significant difference between NPSV and NIPPV. NPSV was as effective as NIPPV in patients with nocturnal hypoventilation, which suggests that these patients are able to trigger the ventilator adequately. The lower cost of NPSV will make it accessible to more patients with chronic lung disease.     

Chronic in vitro shear stress stimulates endothelial cell retention on prosthetic vascular grafts and reduces subsequent in vivo neointimal thickness

OBJECTIVE: The absence of endothelial cells at the luminal surface of a prosthetic vascular graft potentiates thrombosis and neointimal hyperplasia, which are common causes of graft failure in humans. This study tested the hypothesis that pretreatment with chronic in vitro shear stress enhances subsequent endothelial cell retention on vascular grafts implanted in vivo. METHODS: Cultured endothelial cells derived from Fischer 344 rat aorta were seeded onto the luminal surface of 1.5-mm internal diameter polyurethane vascular grafts. The seeded grafts were treated for 3 days with 1 dyne/cm2 shear stress and then for an additional 3 days with 1 or 25 dyne/cm2 shear stress in vitro. The grafts then were implanted as aortic interposition grafts into syngeneic rats in vivo. Grafts that were similarly seeded with endothelial cells but not treated with shear stress and grafts that were not seeded with endothelial cells served as controls. The surgical hemostasis time was monitored. Endothelial cell identity, density, and graft patency rate were evaluated 24 hours after implantation. Endothelial cell identity in vivo was confirmed with cells transduced in vitro with beta-galactosidase complementary DNA in a replication-deficient adenoviral vector. Histologic, scanning electron microscopic, and immunohistochemical analyses were performed 1 week and 3 months after implantation to establish cell identity and to measure neointimal thickness. RESULTS: The pretreatment with 25 dyne/cm2 but not with 0 or 1 dyne/cm2 shear stress resulted in the retention of fully confluent endothelial cell monolayers on the grafts 24 hours after implantation in vivo. Retention of seeded endothelial cells was confirmed by the observation that beta-galactosidase transduced cells were retained as a monolayer 24 hours after implantation in vivo. In the grafts with adherent endothelial cells that were pretreated with shear stress, immediate graft thrombosis was inhibited and surgical hemostasis time was significantly prolonged. Confluent intimal endothelial cell monolayers also were present 1 week and 3 months after implantation. However, 1 week after implantation, macrophage infiltration was observed beneath the luminal cell monolayer. Three months after the implantation in vivo, subendothelial neointimal cells that contained alpha-smooth muscle actin were present. The thickness of this neointima averaged 41 +/- 12 micrometer and 60 +/- 23 micrometer in endothelial cell-seeded grafts that were pretreated with 25 dyne/cm2 shear stress and 1 dyne/cm2 shear stress, respectively, and 158 +/- 46 micrometer in grafts that were not seeded with endothelial cells. CONCLUSION: The effect of chronic shear stress on the enhancement of endothelial cell retention in vitro can be exploited to fully endothelialize synthetic vascular grafts, which reduces immediate in vivo graft thrombosis and subsequent neointimal thickness.     

Performance of small diameter synthetic vascular prostheses with confluent autologous endothelial cell linings

Autologous grafts are superior to their synthetic counter-parts for grafting arteries smaller than 6-mm diameter both in terms of acute thrombogenicity and chronic intimal hyperplasia. Endothelial cell (EC) coating of the blood contacting surface may reduce thrombogenicity of synthetic small diameter vascular prostheses. In this study, the survival of EC monolayers on synthetic 4-mm diameter arterial prostheses over short-term implantations (< or = 6 weeks) was examined. Graft types examined were expanded polytetra-fluoroethylene (ePTFE) and microporous polyurethane (PU). Lumenal coverage with ECs was achieved by culturing ovine ECs on prostheses treated by either physical adsorption or covalent binding of ovine fibronectin (Fn). An ovine carotid interposition model was used to examine the performance of EC coated ePTFE and microporous PU over implantation periods of 1, 3, and 6 weeks. Outcomes assessed at the end of each experiment were graft patency, area covered by ECs, and thrombus free surface area (TFSA). Fn concentration, cell density at the time of coating and prostacyclin production in vitro were similar for both graft types. Occlusion occurred more frequently in unseeded grafts compared with EC coated grafts over 3 and 6 week implantation periods; however, the difference was not significant (p = 0.099). In prostheses precoated with ECs, approximately 40-60% of the surface area remained covered with endothelial-like cells following the first postoperative week. Recovery of EC layers occurred rapidly thereafter with 80-90% coverage at 3 weeks. TFSA remained low in comparison to EC cover in these prostheses until between 3 and 6 weeks postoperatively, suggesting a lag phase in recovery of EC function of seeded cells. In contrast, EC cover of unseeded prostheses only achieved 10-30% at 3 weeks, primarily by pannus EC ingrowth from the adjacent artery. TFSA of unseeded grafts increased in direct proportion to EC cover over time suggesting that there was no lag phase in function of these ingrowing cells.     

In vitro angiogenic and proteolytic properties of bovine lymphatic endothelial cells

The aim of the present study was to determine whether angiogenic cytokines, which induce neovascularization in the blood vascular system, might also be operative in the lymphatic system. In an assay of spontaneous in vitro angiogenesis, endothelial cells isolated from bovine lymphatic vessels retained their histotypic morphogenetic properties by forming capillary-like tubes. In a second assay, in which endothelial cells could be induced to invade a three-dimensional collagen gel within which they formed tube-like structures, lymphatic endothelial cells responded to basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) in a manner similar to what has previously been observed with endothelial cells derived from the blood vascular system. Finally, since angiogenesis is believed to require extracellular proteolytic activity, we investigated the effects of bFGF and VEGF on lymphatic endothelial cell proteolytic properties by focussing on the plasminogen activator (PA) system. bFGF and VEGF increased urokinase, urokinase receptor, and tissue-type PA expression. This was accompanied by an increase in PA inhibitor-1, which is thought to play an important permissive role in angiogenesis by protecting the extracellular matrix against excessive proteolytic degradation. Taken together, these results demonstrate that with respect to in vitro morphogenetic and proteolytic properties, lymphatic endothelial cells respond to the previously described angiogenic factors, bFGF and VEGF, in a manner very similar to what has been described for endothelial cells derived from the blood vascular system.     

PCL reconstruction. In vitro biomechanical comparison of ''isometric'' versus single and double-bundled ''anatomic'' grafts

The analgesic tramadol inhibits the neuronal reuptake of norepinephrine and 5-hydroxytryptamine, facilitates 5-hydroxytryptamine release, and activates mu-opioid receptors. Each of these actions is likely to influence thermoregulatory control. We therefore tested the hypothesis that tramadol inhibits thermoregulatory control. Eight volunteers were evaluated on four study days, on which they received no drugs, tramadol 125 mg, tramadol 250 mg, and tramadol 250 mg with naloxone, respectively. Skin and core temperatures were gradually increased until sweating was observed and then decreased until vasoconstriction and shivering were detected. The core temperature triggering each response defined its threshold. Tramadol decreased the sweating threshold by -1.03 +/- 0.67 degrees C microgram-1.mL (r2 = 0.90 +/- 0.12). Tramadol also decreased the vasoconstriction threshold by -3.0 +/- 4.0 degrees C microgram-1.mL (r2 = 0.94 +/- 0.98) and the shivering threshold by -4.2 +/- 4.0 degrees C microgram-1.mL(r2 = 0.98 +/- 0.98). The sweating to vasoconstriction interthreshold range nearly doubled from 0.3 +/- 0.4 degree C to 0.7 +/- 0.6 degree C during the administration of large-dose tramadol (P = 0.04). The addition of naloxone only partially reversed the thermoregulatory effects of tramadol. The thermoregulatory effects of tramadol thus most resemble those of midazolam, another drug that slightly decreases the thresholds triggering all three major autonomic thermoregulatory defenses. In this respect, both drugs reduce the "setpoint" rather than produce a generalized impairment of thermoregulatory control. Nonetheless, tramadol nearly doubled the interthreshold range at a concentration near 200 ng/mL. This indicates that tramadol slightly decreases the precision of thermoregulatory control in addition to reducing the setpoint. IMPLICATIONS: The authors evaluated the effects of the analgesic tramadol on the three major thermoregulatory responses: sweating, vasoconstriction, and shivering. Tramadol had only slight thermoregulatory effects. Its use is thus unlikely to provoke hypothermia or to facilitate fever.     

In vitro evaluation of a new injectable calcium phosphate material

BACKGROUND: Verbal autopsies have been widely used to determine the levels and causes of maternal death but few studies have assessed the reliability of various methods. METHODS: We compared the levels and causes of maternal mortality in three data sources from Matlab, Bangladesh: (1) maternal deaths identified through a unique demographic surveillance system (DSS); (2) maternal deaths identified as a result of a previous detailed investigation into the levels and causes of maternal mortality; and (3) maternal deaths identified in the current special study. All studies used lay reporting, but differed in terms of the nature of the study, the sex of the interviewer, the format of the questionnaire and the procedure to derive the diagnosis. RESULTS: There were substantial disagreements between the routine reporting and the special studies. The DSS identified 67.2% of all deaths occurring during pregnancy or within 42 days postpartum (82.3% of direct obstetric deaths, 70.0% of deaths due to induced abortions and 42.4% of indirect obstetric deaths). Extending the definition of maternal deaths to 90 days postpartum increased the numbers of maternal deaths between 1987 and 1993 from 174 to 196. The two special studies also disagreed in the ascertainment of the causes of maternal deaths and yielded different cause of death distributions; the proportion of direct obstetric deaths (excluding abortion) was 50.4% in the current system compared to 44.5% previously (P = 0.001). CONCLUSIONS: This study confirms the known difficulties in the ascertainment of the levels and causes of maternal mortality. The large disparities in the levels and causes of maternal mortality using three different methods of lay reporting in a population with an almost complete vital registration system add to the growing concern about the inaccuracies in the measurement of maternal mortality.     

In vitro evaluation of the long-body On-X bileaflet heart valve

AIM: To determine the staining pattern of vascular endothelial growth factor (VEGF) at different stages of diabetic retinopathy (including post-laser photocoagulation) and to compare staining in excised fibrovascular and fibrocellular (non-diabetic) preretinal membranes. METHODS: Immunohistochemical localisation of VEGF, using antibodies raised against VEGF165 and VEGF121,165,189, was carried out on specimens of normal human retina (n = 15), diabetic retinas ((a) with no overt retinopathy (n = 19), (b) with intraretinal vascular abnormalities but no proliferative retinopathy (n = 6), (c) with active proliferative retinopathy (n = 6), (d) with no residual proliferative retinopathy after photocoagulation therapy (n = 15)), excised diabetic fibrovascular membranes (n = 19), and non-diabetic fibrocellular membranes (n = 7). The degree and pattern of immunostaining was recorded. RESULTS: In general, VEGF was absent from the majority of normal retinas. VEGF staining was apparent in most diabetic tissues but the staining pattern was dependent on both the specificity of the antibody used and the category of tissue. Staining with the VEGF165 antibody was generally confined to endothelial cells adn perivascular regions while the VEGF121,165,189 antibody was also associated with extravascular components of the inner retina. Intensity of immunostaining of diabetic eyes was dependent on the severity of retinopathy being least in diabetics with no overt retinopathy and greatest in retinas with proliferative retinopathy. Interestingly, the intensity of immunostaining in diabetic retinas which had undergone laser surgery for proliferative retinopathy was reduced to basal levels. Moderate to intense immunostaining was observed in all fibrovascular and fibrocellular membranes examined. CONCLUSIONS: This study supports a circumstantial role for VEGF in the pathogenesis of both the preclinical and proliferative stages of diabetic retinopathy.     

In vitro evaluation of medicinal plant extracts against Pestalotiopsis mangiferae

A serious leaf-spot disease of Mangifera indica was noted during the last 10 years in Satpura plateau of India. On the basis of characteristic symptoms and cultural characters, the pathogen was identified as Pestalotiopsis mangiferae which is hitherto not reported from Satpura plateau of India. Screening of 17-medicinal plants against the test pathogen revealed 14 antimycotic whereas 3-plants, viz., Argemone mexicana, Caesalpinia bonducella, and Casia fistula acclerated the growth of the pathogen. The maximum activity was shown by Eucalyptus globulus (88%) and Catharanthus roseus (88%) followed by Ocimum sanctum (85.50%), Azadirachta indica (84.66%), Ricinus communis (75%) and Lawsonia inermis (74.33%) while the minimum activity was exhibited by Jatropha curcas (10%).     

Prospective evaluation of corneal endothelial cell loss after pediatric cataract surgery

PURPOSE: To study the alterations in endothelial cell count and morphology after pediatric cataract surgery using currently practiced techniques. SETTING: L.V. Prasad Eye Institute, Hyderabad, India. METHODS: In a prospective nonrandomized series comprising 20 eyes of 14 children with congenital or developmental cataract, endothelial cell loss from cataract surgery was evaluated. Mean patient age was 9.3 years (range 5 to 15 years). Extracapsular cataract extraction (ECCE) with intraocular lens (IOL) implantation was performed in 11 eyes (Group 1). Primary posterior capsulotomy and anterior vitrectomy were performed with ECCE and IOL implantation in 9 eyes (Group 2). Noncontact specular microscopy was done preoperatively and 6 to 8 and 24 to 36 weeks postoperatively. Endothelial cell loss, alteration in the coefficient of variation, and the change in the number of hexagonal cells were determined by semiautomated analysis of endothelial pictures. RESULTS: Mean endothelial cell loss was 198.39 cells/mm2 (5.28%) in Group 1 and 295.17 cells/mm2 (7.50%) in Group 2 at 24 to 36 weeks. There was no statistically significant difference in alteration in endothelial cell count and morphology between the 2 groups. CONCLUSIONS: The results suggest that endothelial cell loss with currently practiced techniques of pediatric cataract surgery is within acceptable limits.     

Production of plasminogen activator inhibitor-1 by human saphenous vein endothelial cells seeded onto endarterectomy surfaces in vitro

PURPOSE: Endothelial cells produce many biologically important factors that may be used as functional markers, including plasminogen activators and their inhibitors (PAI). PAI-1 is a common peptide with a central role in the balance of thrombosis and fibrinolysis in vivo, and its production by vascular endothelial cells has been demonstrated for many in vitro cell lines. METHODS: The basal rate of PAI-1 release from cultured human adult endothelial cells was studied in both a well-plate-seeding model and after seeding onto human endarterectomy specimens. The effect of nonspecific stimulation with thrombin on PAI-1 release was examined in well-plate cultures. PAI-1 was measured by enzyme-linked immunosorbent assay. RESULTS: Cultured human saphenous endothelial cells release PAI-1 constitutively at a steady rate, which can be increased in the short term by the addition of thrombin. CONCLUSION: After seeding onto endarterectomy specimens, seeded endothelial cells release significant amounts of PAI-1, which suggests that they retain functional integrity and may potentially influence thrombosis in vivo after seeding.     

In vitro evaluation of three-dimensional ultrasonography based on magnetic scanhead tracking

The objective of this study was to evaluate the accuracy and precision of a magnetic position sensor system for acquisition of three-dimensional (3D) ultrasound images in volume estimation of phantoms in vitro. Installation of either 0.9% solution of saline at 37 degrees C or distilled water at 20 degrees C to a condom was performed. Scanning was performed either by a continuous or stepwise acquisition. This 3D ultrasound system demonstrated good correlation (r = 0.99-1.0, n = 8) between estimated (EV) and true volumes (TV). The errors were in the range 1.3%+/-0.3% (SEM) to 1.9%+/-0.6%, independent of sound velocity. Scanning through a porcine abdominal wall positioned at the fluid surface yielded a systematic underestimation of the volume: mean (EV - TV) = -7.2+/-0.8 ml. Eight repeated scans of the same volume yielded a coefficient of variation of 1.1%. Interobserver error of the tracing procedure was 2.6%+/-0.9%. This 3D ultrasound system gave high accuracy and precision in volume estimation in vitro, and yielded low interobserver error. A change in ultrasound velocity of approximately 60 m/s did not influence the accuracy significantly. Scanning through an abdominal wall underestimated volumes slightly.