Pharmacokinetics of Three Contrast Media in Experimental Pancreatography

Diatrizoate, iohexol and ioxaglate were compared in experimental pancreatography in piglets. Outflow of contrast medium (CM) through the pancreatic papilla was permitted (n=14) or impaired (n=17) during examination. The CM concentrations were measured in portal and systemic plasma and in lymph to study the absorption of CM. Absorption of diatrizoate and iohexol was similar in both types of experiment, but radiographically, diatrizoate escaped significantly earlier from the pancreatic duct when outflow was permitted (p<0.01), suggesting that the CM was absorbed mainly during injection. Ioxaglate concentrations rose more slowly in systemic plasma and lymph, and fell more slowly in the portal plasma than those of diatrizoate and iohexol, which suggests that ioxaglate was absorbed over a longer period. When outflow was impaired, ioxaglate concentrations remained on a lower level, indicating less penetration in the pancreatic parenchyma. CM absorption varied markedly within each group, suggesting that variations in intraductal pressure and flow are more important in absorption than the type of CM used.

Ionic and Non-Ionic Contrast Media Used for Contrast-Enhanced Computed Tomography in Experimental Pancreatitis

Contrast enhancement of the pancreas was studied in pigs using dynamic computed tomography in experimental oedematous and haemorrhagic/necrotizing pancreatitis during the first two minutes after injection of an intravenous bolus of non-ionic contrast medium (iohexol). The prospects of separating the two forms of the disease, known to be possible with ionic contrast media, were tested with a non-ionic contrast medium. In the oedematous form, contrast enhancement after 5 hours of the disease was significantly higher than in the haemorrhagic/necrotizing form. Contrast enhancement after 30 hours of disease tended to vary with the severity of the disease, showing that the course of oedematous pancreatitis is dynamic. Intermediate forms occur and follow-up studies are needed during the disease. A non-ionic contrast medium proved as good for separating the two forms of the disease in the early phase as were ionic contrast media. In severely ill patients, non-ionic contrast media should therefore be used.

Effects of a germ-free environment on gut immune regulation and diabetes progression in non-obese diabetic (NOD) mice

AIMS/HYPOTHESIS

Microbial factors influence the development of diabetes in NOD mice. Studies in germ-free animals have revealed important roles of microbiota in the regulation of Th17 and forkhead box P3 (FOXP3)(+) T regulatory (Treg) activation in the intestine. However, the effects of intestinal microbiota in immune regulation and diabetes development in NOD mice are still poorly understood.

METHODS

A colony of germ-free NOD mice was established to evaluate the effects of intestinal microbiota on regulatory immunity in the gut, and on the development of insulitis and diabetes in NOD mice.

RESULTS

Diabetes developed in roughly equal numbers in germ-free and specific pathogen-free NOD mice. Insulitis was accentuated in germ-free NOD mice; yet insulin preservation was unaltered. Germ-free NOD mice showed increased levels of Il17 (also known as Il17a) mRNA in the colon, and of Th17 and Th1 cells in the mesenteric and pancreatic lymph nodes, while Foxp3 mRNA and FOXP3(+) Tregs were reduced. In the islet infiltrates, FOXP3(+)CD4(+) T cells were slightly increased in germ-free mice. B cells appeared less activated in the peritoneum and were less abundant in islet infiltrates.

CONCLUSIONS/INTERPRETATION

These results indicate that lack of intestinal microbiota promotes an imbalance between Th1, Th17 and Treg differentiation in the intestine. This imbalance is associated with accelerated insulitis, but intact recruitment of FOXP3(+) Tregs into islets, suggesting: (1) a microbial dependence of local induction of Treg in the gut and draining lymph nodes; but (2) a potentially compensatory function of naturally occurring Tregs in the islets, which may help control diabetogenic T cells.

Giant enhancement of second-harmonic generation in multiple diffraction orders from sub-wavelength resonant waveguide grating

We demonstrate a purely dielectric resonant waveguide structure that enhances the efficiency of second-harmonic generation by a factor of at least 5500 compared to a flat reference surface in the same geometry. We also show that the structure emits second-harmonic radiation in four different directions when the sample is illuminated with fundamental radiation incident at the resonant angle of the sample.

Sweating impairment in patients with multiple sclerosis

OBJECTIVES

To measure sweating in patients with multiple sclerosis (MS).

MATERIALS AND METHODS

Sweating was measured by an evaporimeter after a heating stimulus in 29 MS patients and in 15 healthy control subjects.

RESULTS

The MS patients sweated markedly less than the controls. After 10 min of heating the sweating was significantly lower in the forehead (P = 0.034), feet (right, P = 0.033; left, P = 0.037) and legs (right, P = 0.043; left, P = 0.029) of the MS patients than in those of the controls. After 15 min of heating the difference was statistically significant only in the feet (right, P = 0.043; left, P = 0.029). The Expanded Disability Status Scale score correlated inversely with sweating at 15 min of heating in the left hand (r = 0.42, P < 0.05), and in the left (r = 0.36, P < 0.05) and right foot (r = 0.37, P < 0.05).

CONCLUSIONS

MS is associated with an impairment in thermoregulatory sweating which seems to be related to the disease severity.

Sympathetic skin responses in multiple sclerosis

OBJECTIVES

This study assessed the sympathetic skin responses (SSRs) and their correlation with brain lesion volumes in patients with multiple sclerosis (MS).

MATERIALS AND METHODS

The SSRs were measured in 27 patients with MS and 27 healthy controls. The volumes of the proton density-weighted MS lesions in the brain were measured using MRI.

RESULTS

The SSRs were abnormal in 52% of the patients with MS, but absent only in clinically severe MS. The total lesion volume in the whole brain correlated significantly with both the severity of MS expressed by the EDSS score (P < 0.001) and the decreased SSR amplitudes in the feet (P < 0.01). Focal lesion volumes in the temporal lobe (P < 0.01), in the pons (P < 0.01) and in the cerebellum (P < 0.01) were also separately associated with abnormal SSR reflexes.

CONCLUSIONS

Sudomotor regulation failure in MS is associated with certain focal MS lesions.

Modelling the bioelectric behaviour of halo pin-patient structures during magnetic resonance imaging

Bioelectric compatibility of electrically conductive halo fixation devices and magnetic resonance (MR) imaging has been largely based on resulting image quality. Previous studies have focused primarily on improving image quality and, although the electrical characteristics of the system during imaging may have been noted, they have not been studied in depth. Utilizing both a theoretical and experimental approximation, this study focuses on the bioelectric characteristics of the pin-patient structures typically enountered in clinical halo fixation systems. Results indicate that the halo pin-patient system can be modelled using a resistor-inductor-capacitor circuit and that simple attempts at improving compatibility through increasing interface resistance by the use of insulated pins may not be an effective approach to improving halo instrumentation compatibility with new, stronger magnetic and higher-frequency resonance imaging systems.

Cardiovascular autonomic dysfunction correlates with brain MRI lesion load in MS

OBJECTIVE

The aim of the present study was to investigate the cardiovascular autonomic control in clinically definite multiple sclerosis (MS) patients with a standardised battery of cardiovascular tests and to correlate these findings with the brain magnetic resonance imaging (MRI) lesion load.

METHODS

Fifty-one patients with MS and 50 healthy controls were studied. Brain MRI was performed in all patients showing typical MS lesions. The cardiovascular tests were carried out using a standardised battery.

RESULTS

Heart rate (HR) responses to deep breathing (P < 0.05) and tilt table testing (P < 0.001) were significantly decreased in MS patients when compared to those of the controls. Blood pressure (BP) responses in the tilt table test were also impaired in MS patients (diastolic P < 0.001, systolic P < 0.05). Of the different brain areas investigated the total volume of the midbrain MRI lesions (P < 0.05) was the one most clearly associated with the impaired BP responses.

CONCLUSIONS

MS results in both reduced HR variation and decreased BP reactions indicating disturbed cardiovascular regulation. In particular, the midbrain lesions found in MS are associated with cardiovascular dysfunction.

Bioelectric properties of human cystic fibrosis and non-cystic fibrosis fetal tracheal xenografts in SCID mice

We measured, the bioelectric properties of 14 cystic fibrosis (CF) and 33 non-CF human fetal tracheal xenografts in severe combined immunodeficiency (SCID) mice. All xenografts exhibited a mature airway-type epithelium irrespective of their gestational age, duration of engraftment, and genotype. The in vivo potential difference and the in vitro baseline short-circuit current (Isc) were significantly higher in non-CF than in CF xenografts. In non-CF xenografts, sequential addition of amiloride, forskolin, and ATP resulted in a 39.4% decrease, a 24.1% increase, and a 43.6% increase in Isc, respectively. In CF xenografts, forskolin had no significant effect on Isc, whereas amiloride- and ATP-induced changes in Isc were proportionally higher than in non-CF xenografts (-60.0 and +68.8%, respectively). These results indicate that the bioelectric properties of non-CF xenografts are similar to those of postnatal airways and that CF xenografts exhibit lower baseline electrogenic activity than non-CF xenografts but similar regulation of ion transport processes to postnatal CF airways. This model of mature human fetal tracheal mucosa may help gain insight into early CF airway pathogenesis.

Myelitis associated with influenza A virus infection

We report a patient presenting with myelitis after respiratory symptoms. A high level of antibodies to influenza A virus was measured in serum and cerebrospinal fluid (CSF), and the serum/CSF antibody ratio was 1.7, suggesting specific antibody production in the central nervous system. Magnetic resonance imaging of the spinal canal showed a contrast-enhanced swelling on the cervical medulla. Such a case would have warranted the use of antiviral therapy and calls to mind the neurotropic potential of influenza A viruses.

Comparison of somatostatin and vasopressin in bleeding esophageal varices

Somatostatin (ST) and vasopressin (VP) infusions were compared in the treatment of actively bleeding esophageal varices. Fifty-four patients with liver cirrhosis were included in the study. Thirty-two were given ST 4.2 micrograms/min, and 22 patients were given VP 0.4 IU/min for 72 h after endoscopic diagnosis. The role of alcoholic cirrhosis was similar in both groups. Initial control of bleeding was achieved significantly more often (p = 0.0281) when ST was used (84.4%) than during VP treatment (57.1%). Rebleeding occurred in 18.8% and 4.8%, respectively. Side effects of treatment were significantly more common when VP was used than during ST treatment (p = 0.0021). Overall mortality was high in both groups, being 34% in the ST group and 36% in the VP group. ST infusion seems to be more effective and safer than VP in the treatment of acute variceal bleeding. However, the high frequency of rebleeding during ST treatment means that, after primary hemostasis with ST infusion, other methods, such as surgery or sclerotherapy, are needed to prevent the serious complications of rebleeding.

Experimental chronic pancreatitis in the pig

Chronic pancreatitis was induced in 22 piglets by dividing all pancreatic attachments to the duodenum; five sham-operated piglets served as controls. Two piglets died of postoperative complications. The animals were autopsied 2, 4, or 6 weeks postoperatively. All operated animals developed chronic pancreatitis. Concomitant with the development of interstitial fibrosis, an increasing progressive atrophy of the exocrine parenchyma occurred, with preservation of the islets of Langerhans. This atrophy and fibrosis were considerable already after 2 weeks. In one piglet only there was some acute inflammation and fat necrosis, whereas all showed at least moderate chronic inflammation, which did not change with time. The growth of the piglets stopped, and all had diarrhoea, which was thought to reflect exocrine insufficiency. Two animals (9%) developed a large pancreatic pseudocyst, and all animals had wide pancreatic ducts. The endocrine function was undisturbed. Intravenous glucose tolerance tests showed that the animals did not become diabetic. This model is appropriate for the study of experimental pancreatitis.

Microangiography and dynamic computed tomography in experimental chronic pancreatitis in the pig

Chronic pancreatitis was induced in 22 piglets by dividing all pancreatic attachments to the duodenum. Ten piglets served as controls. The animals were subjected to dynamic computed tomography (CT) two, four or six weeks after operation. Microangiography was also performed on the pancreas two, four or six weeks after operation, following dynamic computed tomography. Microangiography revealed significant changes in the vasculature in advanced chronic pancreatitis. The arteries and arterioles were fewer than normal, their walls were thickened and their diameters exhibited variation. The capillary network was loose and the capillaries were not as well filled as in healthy animals. Contrast enhancement of the pancreas was, however, similar in all experimental animals to that in the healthy controls. It was concluded that the morphological changes seen in chronic pancreatitis histologically and on microangiography could not adversely affect contrast-enhanced CT because there were no changes in the function of the capillary network. On the basis of these results, dynamic CT should give no more information than CT with intravenous contrast medium in chronic pancreatitis.

Treatment of pancreatic fistulas with somatostatin and total parenteral nutrition

Nineteen pancreatic fistulas were treated with somatostatin (ST) and total parenteral nutrition (TPN). Five of the fistulas developed in an uninflamed pancreas, whereas 14 fistulas developed secondary to a necrotizing or chronic pancreatitis. Fistular output varied between 20 and 800 ml/day (median, 160 ml) during TPN before ST treatment; amylase concentration was 10,500-800,000 UI/l. Twelve of 16 (75%) fistulas were contaminated with bacteria. Thirteen of 19 (68%) fistulas closed after a median treatment of 7 (range, 2-14) days. Seven of eight fistulas with open drainage to the bowel healed, whereas only one of six with obstructed drainage closed. All of the uninfected fistulas and half of the infected fistulas closed. The findings suggest that somatostatin treatment speeds up the closure of pancreatic fistulas with open drainage to the bowel but is not beneficial when the intestinal drainage of the fistular region to the bowel is obstructed.

Pharmacokinetics of three contrast media in experimental pancreatography

Diatrizoate, iohexol and ioxaglate were compared in experimental pancreatography in piglets. Outflow of contrast medium (CM) through the pancreatic papilla was permitted (n = 14) or impaired (n = 17) during examination. The CM concentrations were measured in portal and systemic plasma and in lymph to study the absorption of CM. Absorption of diatrizoate and iohexol was similar in both types of experiment, but radiographically, diatrizoate escaped significantly earlier from the pancreatic duct when outflow was permitted (p less than 0.01), suggesting that the CM was absorbed mainly during injection. Ioxaglate concentrations rose more slowly in systemic plasma and lymph, and fell more slowly in the portal plasma than those of diatrizoate and iohexol, which suggests that ioxaglate was absorbed over a longer period. When outflow was impaired, ioxaglate concentrations remained on a lower level, indicating less penetration in the pancreatic parenchyma. CM absorption varied markedly within each group, suggesting that variations in intraductal pressure and flow are more important in absorption than the type of CM used.

Pheochromocytoma combined with malignant schwannoma: unusual neoplasm of the adrenal medulla

A 38-year-old woman was operated on to remove a large tumor that replaced the left adrenal gland. The tumor was encapsulated and showed small areas typical of pheochromocytoma, and spindle cell or undifferentiated round cell sarcoma in most areas. Metastases of primitive round cell appearance were operated from the abdominal cavity and abdominal wall shortly after the initial surgery. Eighteen months after the first operation, the patient was alive with metastases in liver and retroperitoneal space. The pheochromocytomalike component showed a typical ultrastructural and immunohistochemical profile of pheochromocytoma and was positive for neurofilaments, synaptophysin, neuron-specific enolase, and S-100 protein in the sustentacular cells. The sarcomatous areas showed fibroblastoid spindle cells that were often surrounded by a basal lamina. Immunohistochemistry revealed S-100 protein positivity in many spindle cells, but markers of pheochromocytoma or epithelial differentiation were absent. The metastases lacked all markers except for vimentin, and the cells were undifferentiated by electron microscopy. These findings suggest that the neoplasm was a compound tumor with a typical pheochromocytoma component and a sarcoma resembling a malignant schwannoma. Neoplastic proliferation of the S-100 protein-positive Schwann-cell-like sustentacular cells of the pheochromocytoma would be an explanation for the genesis of this sarcoma associated with pheochromocytoma.

Pharmacokinetics of contrast medium in experimental pancreatography

The pharmacokinetics of a contrast medium in experimental pancreatography of 17 piglets were studied by repeated radiographs of the pancreas and by measuring the concentration of I125-labelled CM in the portal vein, inferior vena cava and in the thoracic duct. Intraduodenal and portal vein injections were performed for comparison. Contrast enhancement of the pancreas after pancreatography was measured by CT. High concentrations of CM were seen in the portal vein 40 seconds after pancreatography, demonstrating direct absorption into the local veins. The concentration of CM in lymph exceeded the systemic concentration 15 minutes after injection, suggesting absorption into lymphatic vessels from the pancreas. CT revealed parenchymal filling of the pancreas even though no acinar filling was seen in normal radiographs. This suggests "invisible" parenchymal filling during normal pancreatography.

Ionic and non-ionic contrast media used for contrast-enhanced computed tomography in experimental pancreatitis

Contrast enhancement of the pancreas was studied in pigs using dynamic computed tomography in experimental oedematous and haemorrhagic/necrotizing pancreatitis during the first two minutes after injection of an intravenous bolus of non-ionic contrast medium (iohexol). The prospects of separating the two forms of the disease, known to be possible with ionic contrast media, were tested with a non-ionic contrast medium. In the oedematous form, contrast enhancement after 5 hours of the disease was significantly higher than in the haemorrhagic/necrotizing form. Contrast enhancement after 30 hours of disease tended to vary with the severity of the disease, showing that the course of oedematous pancreatitis is dynamic. Intermediate forms occur and follow-up studies are needed during the disease. A non-ionic contrast medium proved as good for separating the two forms of the disease in the early phase as were ionic contrast media. In severely ill patients, non-ionic contrast media should therefore be used.

Experimental pancreatography: a comparison of three contrast media

Twenty-five piglets were subjected to experimental transduodenal pancreatography, using three contrast media (CM), namely sodium meglumine diatrizoate (Urografin), meglumine ioxaglate (Hexabrix), and iohexol (Omnipaque), all diluted to a concentration of 300 mg/ml of iodine. The emptying of CM from pancreatic ducts was studied by repeated roentgenograms, and pancreatic irritation by serum amylase and phospholipase A2 measurements. On the 3rd day after pancreatography the glands were removed for histologic examination of tissue damage. Hyperamylasaemia was seen in 53% of the animals 12 to 15 h after examination, to equal extents in each group. Minimal acinar destruction was seen on histologic examination in all cases. The changes were least when diatrizoate was used. The difference from the changes seen in the ioxaglate group was significant (p less than 0.05). Emptying of CM from the ducts was highly significantly (p less than 0.001) faster in the diatrizoate group than in the other groups. Rapid emptying may be an advantage in clinical endoscopic retrograde pancreaticocholangiography.