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Biomedical subjects

M E Clouse

Publications and source records attributed to M E Clouse.

At least 127 records · Page 7Linked to original sources

Hepatic transplantation survival: correlation with adenine nucleotide level in donor liver.

The hypothesis was tested that human donor livers with higher ATP content and energy charge achieve better results after hepatic transplantation. Biopsies were obtained from 25 donor livers immediately prior to implantation and analyzed for adenine nucleotides using high-performance liquid chromatography. The results were correlated with organ histology, transplant function and outcome. Significantly higher concentrations of ATP (4.22 +/- 2.87 vs. 0.71 +/- 0.69 nmoles per mg protein, p less than 0.01), ADP (8.75 +/- 2.96 vs. 4.49 +/- 1.95 nmoles per mg protein, p less than 0.01) and energy charge (0.43 +/- 0.15 vs. 0.21 +/- 0.04, p less than 0.02) were found in successful (n = 20) relative to failed (n = 5) livers. No significant differences were found in AMP, xanthine or hypoxanthine for the two groups, although the average values were higher in failed livers. Fifteen recipients with liver ATP concentration above 2 nmoles per mg protein and energy charge above 0.3 recovered well. Five other successful patients with lower ATP concentration (0.70 +/- 0.39 nmoles per mg protein) and energy charge (0.20 +/- 0.03) had postoperative courses complicated by infection or prolonged hyperbilirubinemia. In five patients whose livers failed, all had low ATP content and energy charge. Of these, three received a replacement liver and two died shortly after the transplantation. The study demonstrates a direct correlation between high ATP content and good posttransplant outcome.

Adenine Nucleotides↗

Transfemoral repositioning of malpositioned central venous catheters.

PURPOSE: To determine the efficacy of the transfemoral vein approach to repositioning malpositioned central venous catheters. METHODS: During a 4(1/2)-year period, malpositioned central venous catheters were repositioned 91 times in 83 patients via the transfemoral vein approach. All repositioning was initially attempted with a Grollman catheter or other pigtail catheter and a tip-deflecting wire. If these techniques failed or the venous anatomy was unfavorable, gooseneck or long loop snares were used. RESULTS: During 48 repositionings, rotating a pigtail-type catheter alone was used successfully in 39 (81%). In 6 of 9 failures, the addition of a tip-deflecting wire also failed. A Grollman catheter and tip-deflecting wire were used initially in 39 repositionings (6 failures; 85% success). Successful repositioning required a snare in 8 (4 as the primary repositioning technique) and a long-loop technique in 5. All repositionings were ultimately successful and there were no complications. CONCLUSION: Central venous catheters can be repositioned consistently by the transfemoral route. Pigtail catheters or tip-deflecting wires alone are successful in over 80% of cases.

Catheterization, Central Venous↗

Acute aortic occlusion as a late complication of coarctation repair.

Late morbidity and mortality following surgical correction of coarctation of the aorta in adults are primarily related to associated cardiovascular disease, especially persistent systemic hypertension and its sequelae. complications related to the site of coarctation repair are relatively uncommon in this age group and include residual and recurrent coarctation and aneurysm formation. An unusual case is presented in which dehiscence of the proximal suture line of a Dacron tube graft resulted in a flap-valve effect, pseudoaneurysm formation, and acute functional occlusion of the aorta. The angiographic findings are described and the relevant literature reviewed.

Adult↗

Biliary duct stones: percutaneous transhepatic removal.

Percutaneous transhepatic removal of common bile duct stones was performed 57 times in 53 patients with a success rate of 93%. All patients had contraindications to surgery or had undergone unsuccessful attempts at endoscopic retrograde cholangiopancreatography and papillotomy. A modified Dormia basket was inserted through a percutaneous transhepatic approach and the stones or fragments were advanced into the duodenum. Monooctanoin (26 patients) or methyl tertiary butyl ether (4 patients) was infused to reduce stone size or remove residual debris. The average time for complete stone removal was 8.5 days. Morbidity was 12% and mortality was 4%, results which compare favorably with those of surgery.

Adult↗

Hepatic arterial chemoembolization for metastatic endocrine tumors.

PURPOSE: In patients with hepatic metastases from endocrine tumors, the safety and effectiveness of chemoembolization with ethiodized oil was determined and compared with those of embolization with particulate matter alone. PATIENTS AND METHODS: Twenty patients with hepatic islet cell or carcinoid tumor metastases were treated with selective hepatic artery injection of doxorubicin and iopamidol emulsified in ethiodized oil, followed by gelatin foam powder embolization. RESULTS: In 16 patients with hormonally active tumors, hormone secretion decreased 90% (range, 69%-98%) in 10 days, with relief of symptoms in all patients. Average tumor size decrease was 84%; average hospitalization was 8 days. Seventeen patients are alive 6-27 months after embolization, and all are asymptomatic. Three patients died within 1 year after embolization of progressive disease outside the liver. CONCLUSION: Chemoembolization with doxorubicin emulsified in ethiodized oil and iopamidol is effective in the treatment of hepatic metastases from endocrine tumors. This technique appears to result in less morbidity than particulate embolization alone.

Adenoma, Islet Cell↗

Chemoembolization for hepatocellular carcinoma: epinephrine followed by a doxorubicin-ethiodized oil emulsion and gelatin sponge powder.

PURPOSE: This study evaluates chemoembolization (CE) of the liver with minimal vasoconstriction followed by selective intraarterial delivery of an emulsion of iopamidol, doxorubicin, and ethiodized oil and temporary occlusion of hepatic artery with gelatin sponge powder in patients with hepatocellular carcinoma. PATIENTS AND METHODS: Since 1988, 30 patients with nonresectable hepatocellular carcinoma underwent CE with the above protocol. Intraarterial epinephrine (0.5-1 microgram diluted in 10 mL of saline) was rapidly injected directly into the proper hepatic artery or selectively into the right or left hepatic arteries and was followed by 40-60 mg of doxorubicin dissolved in 10 mL of iopamidol and emulsified in 20 mL of ethiodized oil. The chemoembolic mixture was injected at the rate of arterial flow. Liver function and clotting parameters were monitored three times a day until there was a downward trend toward preembolic levels. Computed tomography (CT) was performed immediately after embolization and at 1-3-month intervals. Embolization was repeated when CT demonstrated recurrent or progressive disease. RESULTS: Disease recurred or progressed in 11 patients at 2-17 months after embolization. CE was repeated in four patients; one individual underwent three embolizations. Re-embolization was performed up to 14 months after initial embolization (median, 10 months). Five patients (16.7%) died within 1 month of embolization. Ten patients died at 3-33 months after CE. Two of these patients died of cirrhosis at 6 and 14 months, without evidence of recurrent tumor. Fifteen patients remain alive 5-28 months after CE. Kaplan-Meier estimation of probability of survival curves demonstrates a median survival of 14 months. Sixty-one percent of patients were alive at 1 year and 36% at 2 years after the procedure. CONCLUSION: CE with use of the above technique is effective for palliating inoperable hepatocellular carcinoma. It causes a significant prolongation of survival over the expected 18-24 weeks in untreated patients; this may occur because high doses of chemotherapeutic agents are delivered and come in contact with the tumor for a longer period, followed by ischemia brought about by temporary arterial occlusion.

Adult↗

In vivo and in vitro analysis of the effectiveness of doxorubicin combined with temporary arterial occlusion in liver tumors.

PURPOSE: The authors evaluated the effects of daunomycin (daunorubicin)--an analogue of doxorubicin--ethiodized oil, and arterial occlusion on an in vitro hepatoma analogue and on in vivo rat liver tumors. MATERIALS AND METHODS: A human Sk hepatoma cell monolayer sandwich system was used to determine uptake of 3H-daunomycin under normoxic/hypoxic conditions with use of autoradiography. Fluorescence microscopy was used to evaluate the biodistribution of doxorubicin in cell cultures (human Sk hepatoma and colon carcinoma). Microvascular flow adjacent to and within liver tumors and the intrahepatic effects of doxorubicin and ethiodized oil were studied with in vivo video microscopy on exteriorized rat livers containing peripheral hepatomas. RESULTS: Increased uptake of 3H-daunomycin by hepatoma cells occurred under hypoxic conditions. Intrahepatic arterial administration of ethiodized oil caused temporary occlusion of peripheral sinusoids following passage through arterioportal anastomoses. Tumors received portal venous and neovascular blood supply and ethiodized oil occluded but did not enter the narrow neovasculature perfusing the tumors. CONCLUSION: Hypoxia increases uptake of 3H-daunomycin by human Sk hepatoma and colon carcinoma cell cultures. Selective hepatic arterial occlusion (and perhaps the resultant hypoxia) may facilitate increased uptake of doxorubicin analogues into liver tumors. Hepatomas receive both arterial and portal venous blood supply, and ethiodized oil reaches the tumor via arterioportal anastomoses that perfuse the tumor periphery.

Animals↗

Percutaneous intraarterial thrombolysis: analysis of factors affecting outcome.

PURPOSE: The authors report results of high-dose thrombolytic therapy in native arteries and vein grafts and discuss the various factors affecting outcome. PATIENTS AND METHODS: In a retrospective study, the outcome of 82 high-dose urokinase infusions in 76 patients was examined. Comorbid risk factors as they relate to outcome were studied extensively with log-linear analysis. Positive thrombolytic outcome (PTO) is defined as complete thrombolysis of a previously occluded segment with restoration of antegrade flow augmented by angioplasty or operative intervention to clear symptoms for 30 days. RESULTS: The procedure resulted in a PTO in 63 of 82 instances (77%). The treatment was with urokinase alone in 39 cases (47%) and urokinase followed by surgery in 34 (41%), by angioplasty in four (5%), and by angioplasty in the proximal artery and peripheral vein grafting in five (6%). All stenoses associated with grafts were treated surgically. None of the following affected thrombolytic outcome: age of occlusion, heparin dose, catheter type, length or location of graft, or artery versus graft occlusion. The 30-day mortality was 6.1%, with a procedure-related mortality rate of 2.4%. Overall amputation rate was 18% (74% for patients in whom lysis failed by 30 days). CONCLUSION: The presence of at least one runoff vessel was the most important factor affecting outcome (PTO, 95%; P = .00001, chi 2). The most important comorbid risk factor for failed thrombolysis was coronary artery disease (P = .03, chi 2).

Angioplasty↗

Targeting of different ethiodized oil-doxorubicin mixtures to hypovascular hepatic metastases with intraarterial and intraportal injections.

PURPOSE: The distribution of different ethiodized oil-doxorubicin mixtures within and around hypovascular liver metastases in athymic nude mice was compared following either intraarterial or intraportal injections. MATERIALS AND METHODS: Six different mixtures of doxorubicin and ethiodized oil in water-soluble contrast material, shaken for 5, 10, 15, and 30 minutes, respectively, were prepared and the size of the oil droplets in the mixtures evaluated. Intraarterial and intraportal injections of mixtures shaken for 10 and 15 minutes were performed in mice bearing hypovascular hepatic colorectal metastases. In vivo video microscopy was used to evaluate microvascular flow and the biodistribution and the size of the oil droplets within and around the tumors. RESULTS: Oil droplets smaller than 20 microns in diameter were taken up by tumor nodules. There was no significant difference in oil droplet accumulation within the tumor between intraarterial and intraportal injections. Oil droplets larger than 20 microns occluded small and medium portal branches. The optimum combination was 0.1 mL of ethiodized oil in 2 mL of diatrizoate sodium meglumine (Renografin-76) shaken for 15 minutes at 800 rpm, which formed droplets smaller than 20 microns (92%). CONCLUSION: Avascular regions of hepatic metastases may be embolized with ethiodized oil-anticancer drug mixtures containing oil droplets smaller than 20 microns. Since these droplets penetrate to the tumor interstitium with either intraarterial or intraportal injections, chemoembolization via the arterial route seems preferable for treatment of unresectable hypovascular hepatic metastases since it is easier to perform. The conclusions drawn from this study are limited to the animal model for experimental hypovascular hepatic metastases.

Animals↗

Halothane-induced intrahepatic portovenous shunting reduces hepatic microvascular sinusoidal perfusion during contrast angiographic procedures.

PURPOSE: Reduced intrahepatic perfusion that occurs during contrast angiography performed after administration of halothane anesthesia is thought to result from halothane-induced systemic hemodynamic alterations, such as reduced splanchnic blood flow, rather than intrahepatic microvascular alterations. The authors postulate that intrinsic hepatic effects caused by inhalational anesthetic agents rather than contrast materials, further reduce liver perfusion. MATERIALS AND METHODS: With use of dynamic video microscopy, intrahepatic microvascular flow rates and patterns, hepatic cord/sinusoidal diameters, portal venous pressure changes, and quantitative and qualitative Kupffer cell phagocytic activity were continuously recorded in isolated perfused rat livers before and during exposure to 1.5% halothane in O2/CO2, with and without the addition of iothalamate meglumine. RESULTS: Exposure of livers to halothane resulted in intrahepatic portovenous shunting secondary to obstruction to sinusoidal outflow, diminished sinusoidal perfusion, and a mean elevation in terminal portal venous pressure of 12.8 mm Hg. Kupffer cell phagocytic activity was reduced even when normalized for flow within sinusoids. None of these changes were attributed to use of contrast material. CONCLUSIONS: Alterations in hepatic blood flow during exposure to halothane result, in part, from increased intrinsic hepatic vascular resistance, sinusoidal outflow obstruction, and portovenous shunting, and not only from systemic hemodynamic changes. Iothalamate meglumine produced no microvascular alterations.

Anesthetics, Inhalation↗

Percutaneous radiofrequency tissue ablation: optimization of pulsed-radiofrequency technique to increase coagulation necrosis.

PURPOSE: To develop a computerized algorithm for pulsed, high-current percutaneous radiofrequency (RF) ablation, which maximally increases the extent of induced coagulation necrosis. MATERIALS AND METHODS: An automated, programmable algorithm for pulsed-RF deposition was designed to permit high-current deposition by periodically reducing current for 5-30 seconds during RF application. Two strategies for pulsed-RF deposition were evaluated: (i) constant peak current (900-1,800 mA) of variable duration and (ii) variable peak current (1,200-2,000 mA) for a specified minimum duration. The extent of induced coagulation was compared to results obtained with continuous (lower current) RF application. Trials were performed in ex vivo calf liver (n = 115) and in vivo porcine liver (n = 30) and muscle (n = 18) with use of 2-4-cm tip, internally cooled electrodes. RESULTS: For 3-cm electrodes in ex vivo liver, applying pulsed-RF with constant peak current for 12 minutes produced 3.5 cm +/- 0.2 of necrosis. Greater necrosis was produced with use of the variable current strategy, in which 4.5 cm +/- 0.2 of coagulation was achieved with use of an initial current > or =1,500 mA (minimum peak-RF duration of 10 sec, with 15 sec of reduced current to 100 mA between peaks; P < .01). This variable peak current algorithm also produced 3.7 cm +/- 0.6 of necrosis in in vivo liver, and 6.5 cm +/- 0.9 in in vivo muscle. Without pulsing, a maximum of 750 mA, 1,100 mA, and 1,500 mA could be applied in ex vivo liver, in vivo liver, and in vivo muscle, respectively, which resulted in 2.9 cm +/- 0.2, 2.4 cm +/- 0.2, and 5.1 cm +/- 0.4 of coagulation (P < .05, all comparisons). CONCLUSIONS: A variable peak current algorithm for pulsed-RF deposition can increase coagulation necrosis diameter over other ablation strategies. This innovation may ultimately enable the percutaneous treatment of larger tumors.

Animals↗

MR imaging in myelofibrosis.

Two patients with myelofibrosis demonstrated decreased signal intensity from the bone marrow due to replacement of marrow fat with fibrosis and cellular elements.

Aged↗

Chemoembolization of hepatic neoplasms: safety, complications, and when to worry.

Chemoembolization of the liver for unresectable malignancy, although controversial, is being used with increasing frequency. Chemoembolization can be difficult, and there is great potential for causing complications. There are also findings after chemoembolization, particularly on computed tomographic scans, that may appear to indicate complications but are common and of no concern. Chemoembolization requires an understanding of the congenital and acquired variations of arterial anatomy that may be seen supplying the liver. Assessment of the patency of the portal vein is also required. An abnormal portal vein demands significant changes in technique to allow safe chemoembolization. Partial or complete occlusion of the portal vein is associated with significantly decreased survival but does not prevent a worthwhile response to chemoembolization and is not an absolute contraindication. The presence of chemoembolization material in the gallbladder is not uncommon; with the technique used by the authors, the chemoembolization material infrequently causes cholecystitis or gallbladder infarction. Extrahepatic chemoembolization material is commonly seen in other organs but usually does not cause problems, presumably because the dose deposited outside the liver is small compared with the dose delivered to the liver. Other complications include pseudocirrhosis, liver infarction and abscess formation, carcinoid crisis, hepatorenal syndrome, and liver rupture.

Antineoplastic Combined Chemotherapy Protocols↗