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Biomedical subjects

Michael D Darcy

Publications and source records attributed to Michael D Darcy.

11 recordsLinked to original sources
PubMed2005

Effects of Schwann cells and donor antigen on long-nerve allograft regeneration.

Nerve allotransplantation has been used successfully in human subjects to restore function after traumatic nerve injury and avoid subsequent limb amputation. However, due to the morbidity associated with nonspecific immunosuppression, this reconstructive approach has been limited to patients with particularly severe nerve injuries. It would be desirable to broaden the indications for such procedures through development of less toxic antirejection therapies. A miniature swine model of nerve transplantation was used to investigate the effects of preoperative ultraviolet-B (UV-B)-irradiated donor alloantigen portal venous infusion and injection of cultured major histocompatibility complex (MHC)-matched Schwann cells into the nerve graft. The transplanted ulnar nerves were harvested at 20 weeks. Histomorphometry showed marked enhancement in nerve regeneration through allografts injected with Schwann cells. Serial mixed lymphocyte assays demonstrated suppression of the recipient immune response to the donor antigen after pretreatment, but no additional neuroregenerative effect of donor alloantigen pretreatment.

Animals↗
PubMed2005

Hepatic arterial chemoembolization for hepatocellular carcinoma: comparison of survival rates with different embolic agents.

PURPOSE: The optimal embolic agent for transhepatic arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) has not been identified. This study reports outcomes of TACE for HCC with Gelfoam powder and polyvinyl alcohol (PVA). MATERIALS AND METHODS: Eighty-one patients underwent 152 TACE sessions with Gelfoam powder (n = 41) or polyvinyl alcohol (PVA) and Ethiodol (n = 40) as the embolic agent. Chemotherapeutic drugs were the same for all patients (50 mg cisplatin, 20 mg doxorubicin, 10 mg mitomycin-c). The groups were compared based on number of TACE sessions, maximum tumor size, bilirubin level, aspartate and alanine aminotransferase levels, Child-Pugh score, Model for End-stage Liver Disease score, and hepatitis B or C virus positivity. The number of cases of each Child class in each group was also evaluated. Survival starting from the first TACE session was calculated according to Kaplan-Meier analysis. Forty-eight patients died during the study period, 19 received transplants, and 14 were alive at the end of the study period. RESULTS: The groups were statistically similar in all categories regarding liver function, Child-Pugh score, tumor size, hepatitis status, and percentage of patients with Child class A, B, and C disease. The number of TACE sessions was significantly greater for the Gelfoam powder group (mean, 2.2) versus the PVA group (mean, 1.6; P = .01). Overall survival was similar between groups whether patients who received transplants were included in the analysis (mean, 659 days +/- 83 with Gelfoam powder vs 565 days +/- 71 with PVA; P = .42) or were excluded (mean, 519 days +/- 80 with Gelfoam powder vs 511 days +/- 75 with PVA; P = .93). CONCLUSION: In similar patient groups, survival after treatment of HCC with TACE with Gelfoam powder or PVA and Ethiodol was similar.

Antineoplastic Agents↗
PubMed2004

Comparison of MELD and Child-Pugh scores to predict survival after chemoembolization for hepatocellular carcinoma.

PURPOSE: To compare the value of the Child-Pugh and Model for End-stage Liver Disease (MELD) scores to predict patient survival rates after transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Eighty-seven patients underwent 169 TACE sessions. Child-Pugh and MELD values were calculated before initial treatment. Survival length was tracked from the date of the first TACE procedure. Transplant recipients were censored from the study at the time of surgery. Child-Pugh and MELD scores as well as bilirubin and albumin levels and International Normalized Ratio were placed in high and low categories defined by their respective medians. Patient survival was compared at 3 months, 6 months, 12 months, and 24 months, and patterns were tested with chi2 or Fisher exact tests. Survival over the entire period was examined with Kaplan-Meier analysis and differences were tested with log-rank tests. RESULTS: Mean and median survival times for all patients were 24 and 17 months, respectively. Sixteen patients were censored for transplantation at a mean of 12.9 months. MELD and Child-Pugh scores correlated well with each other (r = 0.68). Child-Pugh score (r = -0.35, P = .04) correlated more strongly with 12-month survival than did MELD score (r = -0.26, P = .12). After high/low score category division, a significantly greater survival difference was predicted by Child-Pugh score (27.2 months vs 10.3 months; P = .03) versus MELD score (27.5 months vs 15.8 months; P = .19). An albumin level greater than 3.4 g/dL was also associated with significantly improved survival (29.3 months vs 10.1 months; P = .0032). Survival differences between high-risk and low-risk groups at the 3-, 6-, 12-, and 24-month intervals were significant for low Child-Pugh scores and for albumin levels greater than 3.4 g/dL. Statistical significance was not approached at any of the time lengths with MELD scores. CONCLUSIONS: Child-Pugh score correlates better than MELD score to overall patient survival and is a better predictor than MELD score of survival at specific time points. Of the components of the Child-Pugh and MELD systems, albumin level is the most useful predictor of survival.

Albumins↗
PubMed2003

Doppler evaluation of transjugular intrahepatic portosystemic shunts.

Transjugular intrahepatic portosystemic shunts are becoming an increasingly popular technique for the treatment of portal hypertension and its complications. However, to maintain patency, revisions are periodically required to treat stenosis and thrombosis. At many centers, Doppler sonography is used for routine follow-up. A variety of hemodynamic parameters, including main portal vein velocity, maximum stent velocity, minimum stent velocity, velocity gradient in the stent, temporal changes in stent velocity, flow direction in the intrahepatic portal and hepatic veins, and pulsatility of flow in the stent can be used. Many studies have confirmed that Doppler sonography is a valuable, noninvasive means of detecting stent malfunction, although the criteria vary somewhat at different institutions.

Blood Flow Velocity↗
PubMed2003

Endovascular recanalization of the thrombosed filter-bearing inferior vena cava.

PURPOSE: To evaluate the authors' preliminary experience with use of endovascular methods to treat inferior vena cava (IVC) thrombosis in patients with IVC filters. MATERIALS AND METHODS: Catheter-directed thrombolysis, balloon maceration, mechanical thrombectomy, and stent placement were used to treat 10 patients with thrombosis of filter-bearing IVCs causing symptoms in 18 limbs. Procedural challenges, technical and clinical success, complications, postprocedural filter status, and postprocedural pulmonary embolism (PE) prophylaxis were monitored. RESULTS: Technical and clinical success were achieved in 15 of 18 (83%) and 14 of 18 symptomatic limbs (78%), respectively. Major bleeding (muscular hematoma) occurred in one patient (10%). Postprocedural PE prophylaxis included anticoagulation (n = 8) and placement of a new filter into a newly placed Wallstent (n = 1). During clinical follow-up, no clinically detectable PE was observed. Data pertaining to late limb status were available at a median of 19 months (range 1-46 months) follow-up in seven patients: three patients were asymptomatic, two patients had ambulatory edema only, one patient had constant mild edema, and one patient had constant severe edema. Postprocedural filter stability was radiographically documented at a median of 255 days (range, 4-1021 d) of follow-up. CONCLUSION: Endovascular recanalization of the occluded IVC is feasible even in the presence of an IVC filter.

Adult↗
PubMed2002

Safety and efficacy of transjugular intrahepatic portosystemic shunt creation for the treatment of hepatic hydrothorax.

PURPOSE: To evaluate safety and efficacy of transjugular intrahepatic portosystemic shunt (TIPS) creation for hepatic hydrothorax (HHyd). MATERIALS AND METHODS: Twenty-one patients underwent TIPS creation for HHyd. A prospective TIPS database and medical records were reviewed. Clinical and radiographic outcomes were recorded as complete (symptom/effusion resolution), partial (improved symptoms/effusion), or none. Data patterns were examined with chi(2) tests and Kaplan-Meier analysis. RESULTS: Patients included 12 women and nine men, with a mean age of 56 years, all with Child class B (n = 7) or C (n = 14) disease. The technical success rate was 100%. Mean follow-up was 223 days. Twenty-nine percent (six of 21) died within 30 days of TIPS creation, 10% (two of 21) underwent transplantation within 30 days, and 62% (13 of 21) survived beyond 30 days. Data were incomplete in two patients. Clinical response was classified as complete in 63% (12 of 19), partial in 11% (two of 19), and none in 26% (five of 19). Radiographic response was classified as complete in 30% (six of 20), partial in 50% (10 of 20), and none in 20% (four of 20). Nonresponders had multisystem organ failure, and all but one died within 30 days. However, of the 13 patients surviving longer than 30 days, 10 (77%) had a complete clinical response. CONCLUSION: TIPS is a relatively safe and effective method of controlling HHyd. The majority of patients experienced improvement or resolution of clinical symptoms with a variable reduction in the quantity of pleural fluid. There was a tendency among nonresponders to die within 30 days.

Adult↗