Agglutination of single catalyst particles during fluid catalytic cracking as observed by X-ray nanotomography.

Metal accumulation at the catalyst particle surface plays a role in particle agglutination during fluid catalytic cracking.

Full-field transmission x-ray microscopy for bio-imaging.

A full-field hard-x-ray microscope at SSRL has successfully imaged samples of biological and environmental origin at 40 nm resolution. Phase contrast imaging of trabeculae from a female mouse tibia, loaded in vivo to study the effects of weight-bearing on bone structure, revealed a complex network of osteocytes and canaliculi. Imaging of cordgrass roots exposed to mercury revealed nanoparticles with strong absorption contrast. 3D tomography of yeast cells grown in selenium rich media showed internal structure.

Renal amino acid, fat and glucose metabolism in type 1 diabetic and non-diabetic humans: effects of acute insulin withdrawal.

AIMS/HYPOTHESIS: The aim of this study was to test the hypothesis that type 1 diabetes alters renal amino acid, glucose and fatty acid metabolism. MATERIALS AND METHODS: We studied five C-peptide-negative, type 1 diabetic subjects during insulin replacement (glucose 5.6 mmol/l) and insulin deprivation (glucose 15.5 mmol/l) and compared them with six non-diabetic subjects. Leucine, phenylalanine, tyrosine, glucose and palmitate tracers were infused after an overnight fast and samples were obtained from the renal vein, femoral vein and femoral artery. RESULTS: Insulin deprivation significantly increased whole-body fluxes (20-25%) of phenylalanine, tyrosine and leucine, and leucine oxidation (50%). Kidney contributed 5-10% to the whole-body leucine and phenylalanine flux. A net uptake of phenylalanine, conversion of phenylalanine to tyrosine (5 micromol/min) and net release of tyrosine (approximately 5 micromol/min) occurred across the kidney. Whole-body (three-fold) and leg (two-fold) leucine transamination increased but amino acid metabolism in the kidney did not alter with diabetes or insulin deprivation. Insulin deprivation doubled endogenous glucose production, renal glucose production was unaltered by insulin deprivation and diabetes (ranging between 100 and 140 micromol/min). Renal palmitate exchange was unaltered by insulin deprivation. CONCLUSIONS/INTERPRETATION: In conclusion, kidney post-absorptively accounts for 5-10% of whole-body protein turnover, 15-20% of leucine transamination and 10-15% of endogenous glucose production, and actively converts phenylalanine to tyrosine. During insulin deprivation, leg becomes a major site for leucine transamination but insulin deprivation does not affect renal phenylalanine, leucine, palmitate or glucose metabolism. Despite its key metabolic role, insulin deprivation in type 1 diabetic patients does not alter many of these metabolic functions.

Does meta-chlorophenylpiperazine (mCPP) activate human platelets?

mCPP (meta-chlorophenylpiperazine), an agonist at serotonin (5-hydroxytryptamine, 5-HT) 5-HT2 receptors, has been used as a probe of serotonergic function. We assessed its effect on platelet activation by measuring median platelet volume (MPV), the Sonoclot (SCT) pattern and plasma and intraplatelet serotonin. (a) In vitro study: MPV was measured (n = 7) using a high-resolution channelyzer: Saline (median and range (5.23 fl; 5.10-6.18) vs. mCPP (5.36; 5.10-6.44) P = 0.03; ADP (5.42; 5.29-6.44) vs. ADP + mCPP (5.67; 5.42-6.63) P = 0.02; mCPP (5.36; 5.10-6.44) vs. ADP + mCPP (5.67; 5.42-6.63) P = 0.02. Therefore, mCPP increases the MPV and enhances the effect of ADP. (b) In vivo study: The SCT time to inflection (TI) and time to peak (TP) were measured following the oral administration of mCPP (0.5 mg/kg) or aspirin (300 mg) (n = 10). Ingestion of mCPP significantly shortened TI and TP indicating platelet activation. TI: 0 h (mean +/- SD: 10.2 +/- 2.0 min) vs. 6 h (9.3 +/- 1.5) P = 0.03; TP: 0 h (31.9 +/- 7.6) vs. 6 h (23.1 +/- 2.9) P = 0.01. Aspirin had no effect on TI or TP. There were no significant changes in plasma and intraplatelet 5-HT. It is concluded that mCPP activates human platelets via 5-HT receptors.

Preoperative detection of pancreatic insulinomas on multiphasic helical CT.

OBJECTIVE: The objective was to analyze enhancement characteristics of insulinomas and to determine the ability of multiphase CT to localize these tumors. MATERIALS AND METHODS: Prospective interpretations of multiphase helical CT scans were reviewed in 30 patients who had insulinomas resected over a 5-year period. CT scans were retrospectively reviewed to determine enhancement characteristics, tumor conspicuity in each phase of enhancement, and potential causes for false-negative findings. RESULTS: Sixty-three percent (19/30) of tumors were identified on CT prospectively. An additional six tumors were visualized in retrospect, allowing characterization of 25 (83%) of 30 tumors. Most tumors were hyperdense on at least one phase (n = 19), three tumors were hypoattenuating, and three were isodense and pedunculated. Insulinomas were most conspicuous on the early phase in 15 patients and in the portal venous phase in three. All tumors that underwent pancreatic phase imaging were seen (13/13), whereas three of 18 arterial and six of 25 portal venous phase findings were inconclusive for tumor. In the six examinations with false-negative findings in which the tumor could be seen in retrospect, two tumors were isodense and pedunculated, three were in close proximity to vessels, and one had a cystic appearance. CONCLUSION: Multiphasic CT has a moderate sensitivity in the detection of insulinomas. Most tumors are more conspicuous on the earlier phases of enhancement. The pancreatic phase may be more useful than the arterial phase. Potential sources of false-negative results include tumors adjacent to vessels, pedunculated morphology, or nonhyperattenuating lesions.

Percutaneous transhepatic endoluminal biliary biopsy with use of a 19-gauge gun.

A technique was developed to perform endoluminal biliary biopsy with use of a commercially available 19-g gun. In 18 patients, a biopsy set consisting of an outer 7-F, 50-cm sheath, an inner curved 14-g metal cannula, and a 60-cm, 19-g biopsy gun with a 20-mm throw was employed to obtain tissue from suspicious-appearing biliary strictures via preexisting transhepatic tracts. The endoluminal biopsy was positive for neoplasm in 13 of 18 cases with three false negatives, one true negative, and one patient with insufficient follow-up. One biopsy was complicated by a hepatic artery pseudoaneurysm, which was successfully treated with coil embolization.

Diagnosis of endolymphatic hydrops in vivo with magnetic resonance imaging.

HYPOTHESIS: High-resolution magnetic resonance imaging (MRI) at 1.5 T preferentially enhances the perilymph over endolymph after administration of contrast with gadodiamide, which allows for differentiation of the membranous labyrinth. Furthermore, this imaging allows for the detection of endolymphatic hydrops. BACKGROUND: Endolymphatic hydrops is believed to be associated with a number of ear diseases, including Ménière's disease. Although the pathologic changes of overaccumulation of endolymph in the inner ear are obvious on postmortem histologic examination of the temporal bone, they have yet to be observed in a living organism. Previous attempts to visualize this condition with high-resolution contrast-enhanced computed tomographic imaging and MRI have been unsuccessful. METHODS: Healthy pigmented guinea pigs underwent a unilateral surgical ablation of the endolymphatic sac to create endolymphatic hydrops in the ear. High-resolution temporal bone imaging was performed by use of a 1.5-T MRI system. Two-dimensional images were acquired by a spin-echo technique with and without contrast enhancement by gadodiamide. RESULTS: T1-weighted gadodiamide contrast-enhanced MRI of the midmodiolar level of the cochlea demonstrated that the perilymph appeared to be preferentially enhanced relative to the endolymph, resulting in a clear distinction between the scalae of the inner ear. The contrast-enhanced T1-weighted MRI of the midmodiolar level of the hydropic cochlea demonstrated a significantly enlarged scala media in comparison with the normal cochlea in the same animal. CONCLUSION: The demonstration of endolymphatic hydrops has been possible for the first time in vivo by the use of a standard 1.5-T MRI system. This research has important clinical implications: Specifically, this technique may allow for the noninvasive diagnosis of Ménière's disease.

Superior vena cava syndrome: relief with a modified saphenojugular bypass graft.

Superior vena cava (SVC) syndrome is a disabling and potentially life-threatening complication. SVC revascularization can be achieved by means of endovascular or direct surgical reconstructions. In the patient on whom we report, these two options were not possible, and a peripheral venous bypass grafting procedure was done with a technical innovation. Right upper-extremity swelling developed in a 55-year-old woman after radiation therapy for lung carcinoma. A left subclavian vein Port-A-Cath induced extensive thrombosis of the left innominate, axillosubclavian, and jugular veins. She was referred to our institution with very symptomatic SVC syndrome after two failed endovascular interventions. The occlusion of both innominate veins and chronic thrombus extending into the left axillosubclavian and internal jugular veins was confirmed by means of a venogram. A third endovascular attempt failed. The presternal skin had severe radiation-induced damage precluding direct SVC reconstruction. A bypass grafting procedure from the right internal jugular to the femoral vein was performed with spliced bilateral greater saphenous veins tunneled inside an externally supported expanded polytetrafluoroethylene graft. Postoperatively, the patient had no symptoms, and graft patency was confirmed by means of duplex ultrasound scanning. A saphenojugular bypass grafting procedure can offer prompt and durable relief of SVC syndrome when endovascular or direct surgical reconstructions are not possible. This rarely used peripheral venous bypass grafting procedure was modified by tunneling the vein graft inside an externally supported polytetrafluoroethylene graft to prevent kinking or compression.

Balloon dilation compared to stenting of dominant strictures in primary sclerosing cholangitis.

OBJECTIVE: In some patients with primary sclerosing cholangitis (PSC), a localized, high-grade (dominant) stricture may be the principal cause of symptoms and hyperbilirubinemia. The aim of this retrospective study was to compare the beneficial effects and risk of balloon dilation alone versus dilation followed by stenting in PSC patients with dominant strictures. METHODS: Charts from a group of 1009 patients with PSC seen over 10 yr were reviewed to identify those patients who had undergone endoscopic or percutaneous therapeutic intervention. Procedural and clinical data were recorded. RESULTS: A total of 71 PSC patients, median age of 49 yr (range 18-78 yr) were identified. Thirty-four patients were treated with endoscopic balloon dilation alone, and 37 patients were treated with balloon dilation plus stent placement. Stents were placed percutaneously (n = 19), endoscopically (n = 14), or using both interventions (n = 4). Both groups were comparable at baseline with regards to age, symptoms, and bilirubin level. The median duration of follow-up after intervention was similar in both groups. The number of intervention-related complications (30 vs 6, p = 0.001) as well as the incidence of acute cholangitis (p = 0.004) were more common in the stent group compared to the balloon dilation group. There were more complications related to percutaneous stent placement than endoscopic placement (23 vs 7. p = 0.001). There was no significant difference between the two groups with regards to improving cholestasis. CONCLUSIONS: There was no additional obvious benefit from stenting after balloon dilation in the treatment of dominant strictures in PSC patients. Stenting was associated with more complications, and its role after dilation should be assessed in a randomized trial rather than being accepted as routinely indicated in this setting.

Polyarteritis nodosa: spectrum of angiographic findings.

The purpose of this study was to review the positive angiographic findings in patients with polyarteritis nodosa (PAN). The authors reviewed the angiograms of 56 consecutive patients (25 women and 31 men; age range, 18-81 years; mean age, 55 years) with PAN and arterial abnormalities consistent with necrotizing vasculitis. Aneurysms were present in 27 patients and segments of ectasia were present in seven patients, for a total of 34 (61%) of 56 patients with aneurysmal lesions. The remaining 22 (39%) patients had arterial lesions that were occlusive: luminal irregularity, stenosis, or occlusion. All but one of the patients with an aneurysm also had occlusive lesions. Therefore, 55 (98%) of the 56 patients were found to have occlusive lesions. Skeletal muscle arteries were affected in 18 patients, nine in the extremities. The most frequent finding in patients with PAN was occlusive arterial lesions. Although the presence of aneurysms increases specificity for the diagnosis of PAN, many patients have only occlusive lesions. Involvement of skeletal muscle arteries was common.

Noninsulinoma pancreatogenous hypoglycemia syndrome: an update in 10 surgically treated patients.

BACKGROUND: Neuroglycopenia from endogenous hyperinsulinism usually is caused by insulinomas in adults. We recently reported a novel hypoglycemic disorder in 5 patients (patients 1 to 5) with postprandial neuroglycopenia, negative 72-hour fasts, negative perioperative imaging studies, but positive calcium stimulation tests and islet hypertrophy and nesidioblastosis in the gradient-guided resected pancreata. METHODS: In this report we compare our experience with 5 additional patients (patients 6 to 10) with this syndrome to that in the original report. RESULTS: The clinical features of patients 6 to 10 were similar to those of patients 1 to 5. Each had positive calcium stimulation testing that guided the extent of the distal pancreatectomy and histologic evidence of islet cell hypertrophy or nesidioblastosis. All 10 patients are alive from 9 to 50 months after operation, 1 of whom had no amelioration of neuroglycopenia. Minor perioperative complications occurred in 3 patients. One patient has experienced repeated bouts of acute pancreatitis, pseudocyst formation, and exocrine insufficiency. CONCLUSIONS: We have identified adult patients with severe, postprandial hyperinsulinemic hypoglycemia from diffuse islet cell disease, 80% of whom have been well palliated with surgery. The results in 7 men have been better than those in the 3 women for reasons that are not obvious.

Auditory threshold and inner ear pressure: measurements in experimental endolymphatic hydrops.

HYPOTHESIS: Experimental endolymphatic hydrops leads to an endolymph-perilymph pressure imbalance that is responsible for the loss of auditory sensitivity in the ear. BACKGROUND: This study investigates whether intralabyrinthine pressure is a factor in the auditory dysfunction of experimental endolymphatic hydrops. METHODS: Auditory function was investigated in 10 guinea pigs 90 to 120 days after endolymphatic sac ablation by measuring compound action potentials in response to acoustic stimuli including alternating clicks and tone bursts of 0.5, 1, 2, 4, and 8 kHz. After auditory thresholds to the various stimuli were established, endolymphatic and perilymphatic pressures were measured with a no-flow micropressure measuring system. The cause of the hearing loss in Meniere's disease, especially in the early phases of this condition, remains an enigma. Histologic temporal bone preparations show a disproportion in the volume of endolymph to perilymph with an expanded and distorted membranous labyrinth. Speculation as to whether an endolymph-perilymph fluid pressure imbalance is responsible for these morphologic changes were raised by Hallpike and Cairns (1) in their initial report of the histopathology of Meniere's disease. Further speculation has questioned whether this pressure imbalance may be responsible for the symptoms and physical finding of this condition, including hearing loss. The ability to produce experimental endolymphatic hydrops in the guinea pig secondary to surgical occlusion of the endolymphatic sac and duct has been useful in studying various aspects of Meniere's disease (2). Investigators have been able to demonstrate auditory threshold shifts with hydrops. Elevated endolymph-perilymph pressure gradients have also been demonstrated (3). This RESULTS: Increased auditory thresholds were noted in the hydrops ears at all tested parameters (p < 0.03). A relative increase in endolymph over perilymph pressure was found in hydrops ears as previously reported. The increase in endolymph-perilymph pressure of hydrops could not be correlated directly to the elevated auditory threshold shift. CONCLUSION: Endolymphatic hydrops is a complex pathologic state with multiple inner ear alterations including abnormal intralabyrinthine pressure. Factors other than or in addition to pressure contribute to the auditory threshold shift of hydrops.

Aortic fenestration for acute or chronic aortic dissection: an uncommon but effective procedure.

BACKGROUND: Aortic fenestration is rarely required for patients with acute or chronic aortic dissection. To better define its role and the indications for its use and to evaluate its success at relieving organ or limb malperfusion, we reviewed our experience with direct fenestration of the aorta. METHODS: A retrospective analysis of all consecutive aortic fenestrations performed between January 1, 1979, and December 31, 1999, was performed. Fourteen patients, 12 men and two women (mean age, 59.6 years; range, 43-81), underwent fenestration of the aorta. All patients were hypertensive and had a history of tobacco use. By Stanford classification, there were three type A and 11 type B patients. In the acute dissection group (n = 7), indications for surgery were malperfusion in six patients (leg ischemia, 4; renal ischemia, 5; bowel ischemia, 3) and intra-abdominal bleeding from rupture in two. In the chronic dissection group (n = 7), indications for surgery were abdominal aortic aneurysm in 4 patients (infrarenal, 3; pararenal, 1), thoracoabdominal aneurysm in 1, hypertension from coarctation of the thoracic aorta in 1, and aortic occlusion with disabling claudication in 1. RESULTS: Emergency aortic fenestration was performed in seven patients (surgically for 6 and percutaneously for 1). Fenestration level was infrarenal in four and pararenal in three. Concomitant abdominal aortic graft replacement was performed in four patients, combined with ascending aortic replacement (n = 1) and bilateral aortorenal bypasses (n = 1). In two patients, acute fenestration was performed for organ malperfusion after prior proximal aortic replacement (ascending aorta, 1; descending thoracic aorta, 1). Seven elective aortic fenestrations were performed for chronic dissection (descending thoracic aorta, 2; paravisceral aorta, 2; infrarenal aorta, 2 and pararenal aorta, 1). Concomitant aortic replacement was performed in six patients (abdominal aorta, 5; thoracoabdominal aorta, 1). Fenestration was successful at restoring flow in all 10 patients with malperfusion. Operative mortality for emergency fenestration was 43% (3/7). The three deaths that occurred were of patients with anuria or bowel ischemia, or both. There were no postoperative deaths for elective fenestration. At a mean follow-up of 5.1 years, there were no recurrences of malperfusion and no false aneurysm formations at the fenestration site. CONCLUSION: Fenestration of the aorta can effectively relieve organ or limb ischemia. Bowel ischemia and anuria are indicators of dismal prognosis and emergency fenestration in these patients carries a high mortality. Elective fenestration combined with aortic replacement can be performed safely in chronic dissection. Aortic fenestration is indicated for carefully selected patients with malperfusion and offers durable benefits.

Hemosuccus pancreaticus complicating chronic pancreatitis: an obscure cause of upper gastrointestinal bleeding.

BACKGROUND: Hemosuccus pancreaticus, a rare form of upper gastrointestinal bleeding, may complicate chronic pancreatitis and pose a significant diagnostic and therapeutic dilemma. AIM: To present our experience with this potentially life-threatening complication of chronic pancreatitis. METHODS: We reviewed our experience with management (both operative as well as angiographic embolization) of patients with hemosuccus pancreaticus complicating histologically documented chronic pancreatitis between 1976 and 1997. Diagnosis of hemosuccus pancreaticus was based on clinical presentation, preoperative endoscopic and radiographic imaging, operative findings, and pathologic evaluation. RESULTS: During the period, we managed eight patients with hemosuccus pancreaticus (1.5% of all patients with chronic pancreatitis treated surgically). Gastrointestinal bleeding presented as hematemesis in three and hematochezia in three, but all had recent melena and were anemic; three of these patients were hemodynamically unstable. Abdominal pain was present in six. When performed, angiography (n=6) was diagnostic of a pseudoaneurysm; computed tomography (n=7) showed a pseudoaneurysm in two and a pseudocyst in five. Endoscopy (n=8) revealed blood issuing from the ampullary papilla in two patients. Operative management (n=6) involved distal pancreatectomy, pancreatoduodenectomy, or total pancreatectomy in two patients each. Angiographic embolization was successful in one patient, but the other died from uncontrollable hemorrhage. CONCLUSIONS: Hemosuccus pancreaticus is rare, but should be considered in patients with chronic pancreatitis and gastrointestinal bleeding. In the absence of pancreatitis-related indications for surgery, angiographic embolization can be definitive treatment. If there are pancreatitis-related indications for operation, angiographic embolization may allow an elective operative procedure based on structural changes of the pancreas. If embolization fails, pancreatic resection is usually required, often on an emergent basis.

Gastric mucosal responses to intrahepatic portosystemic shunting in patients with cirrhosis.

BACKGROUND & AIMS: The response of gastric mucosal lesions in cirrhotic patients with portal hypertension, namely, portal hypertensive gastropathy (PHG) and gastric vascular ectasia (GVE), to transjugular intrahepatic portosystemic shunts (TIPS) is not known. METHODS: Clinical and laboratory evaluation, upper gastrointestinal endoscopy, and Doppler ultrasonography were performed before placement of TIPS and 6 weeks, 3 months, and 6 months after TIPS in 54 patients. Thirty patients had mild PHG, 10 had severe PHG, and 14 had GVE. RESULTS: Approximately 75% of the patients with severe PHG responded to TIPS as shown by improvement in endoscopic findings and by a decrease in transfusion requirements; 89% of patients with mild PHG had endoscopic resolution. Patients with GVE had neither endoscopic resolution nor a decrease in transfusion requirements after TIPS. There was no difference in mortality between the 2 groups. CONCLUSIONS: The results support the position that severe PHG and GVE may be different lesions. Mild and severe PHG respond to TIPS. Because GVE does not respond to TIPS, we recommend that TIPS be avoided for the treatment of gastrointestinal bleeding associated with GVE.

The roles of the pastor in the interdisciplinary rehabilitation team.

People with chronic illnesses and functional limitations may face a lifetime of changes and adjustments. Often, the onset of a long-term illness or disease requires a person to rethink values and develop new coping strategies in order to adapt to a life-changing event. At such times, people may draw on sources of spiritual support, finding comfort from a pastor or other clergy. This article describes key roles taken by the clergy who provide these services. Patients discharged from inpatient rehabilitation units have reported using faith and prayer as effective coping strategies. Religious faith can have a positive influence on emotions and may be directly related to improved functional ability. Disciplines of faith, such as solitude, silence, and meditation, may promote mental health. Although this article presents information from a Christian church perspective, readers should note that services should be considered from a wide range of spiritual representatives.