Polyorchidism in a young Sprague-Dawley rat.

Duplicate testes lined in series were observed in the right scrotum of a 6-week-old Sprague-Dawley rat in a single-dose toxicity study. Of the two right testicles, one was spherical and less than half the size of a normal testis. The other was oval-shaped, slightly smaller than a normal testis, and possessed clear, tortuous blood vessels similar to those of a normal testis. Each right testis was grossly separated but faced the intertesticular adipose tissue and was sparsely joined by thin cord-like structures. Only one epididymis covered or encompassed the two right testes. The caput epididymis was attached to the smaller spherical testis, whereas the cauda epididymis was attached to the oval testis. Histopathological examination revealed that the smaller spherical testis on the right side and the testis on the left side were normal. The oval-shaped testis on the right exhibited markedly dilated degenerative seminiferous tubules with one to two layers of Sertoli or germ cells, and almost no spermatogenesis was observed. Multinucleated germ cells were observed in the lumen of the degenerated seminiferous tubules. The right epididymis was morphologically normal and contained few sperm in the epididymal duct of the tail. The cord-like structures between duplicate testes comprised fibrous and adipose tissues. Single efferent ductules, ectopic cartilage, and skeletal muscle tissues were buried in the adipose tissue. To our knowledge, this is the first report of spontaneous polyorchidism in a rodent.

Select Toxicologic Pathology Case Studies of the Hepatobiliary System.

This case study session of the hepatobiliary system was held during the 42nd Annual Society of Toxicologic Pathology Symposium in Summerlin, Nevada. The case studies highlighed potential hepatic and biliary toxicity liabilities. This article comprises several of the case studies that were presented during the session which included copper-associated hepatitis in a dog, sinusoidal obstruction syndrome in non-human primates, hepatic cytoplasmic alteration in mice and rats, and Kupffer cell hyperplasia/granulomatous inflammation in rats. Presenters, when applicable, provided case signalment, anatomic/clinical pathology data, and diagnoses and discussed potential pathogeneses.

Immunohistochemical phenotyping of macrophages and T lymphocytes infiltrating in peripheral nerve lesions of dourine-affected horses.

Dourine is a deadly protozoan disease in equids caused by infection with Trypanosoma equiperdum. Neurological signs in the later stage of infection may be caused by peripheral polyneuritis and related axonal degeneration. This neuritis involves T lymphocytes, B lymphocytes, and macrophages, and is observed in cases without obvious neurological signs. However, the pathogenesis of neuritis remains unclear. We identified M2 macrophages and CD8 T cells as the predominant phenotypes in neuritis of dourine-affected horses with or without neurological signs. In contrast, the populations of M1 macrophages and CD4 T cells were small. This result indicates that inflammation was chronic and suggests that dourine-associated neuritis occurs at the early stage of infection.

Polyradiculoneuropathy in dourine-affected horses.

Dourine is an equine protozoan disease caused by Trypanosoma equiperdum. Dourine-afflicted animals die after developing neurological clinical signs, such as unilateral paresis. The disease has been a problem for many years; however, the pathogenesis regarding the neurological clinical signs of dourine has been unclear. In the present study, we conducted a histopathological examination in order to investigate the mechanisms by which dourine-afflicted horses develop the accompanying neurological clinical signs. Four dourine-afflicted horses in Mongolia were evaluated. An apparently healthy horse exhibited multifocal neuritis without axonal or myelin degeneration. The other horses, which had obvious neurological clinical signs, also exhibited multifocal neuritis. In particular, the nerves that innervated areas associated with neurological clinical signs exhibited neuritis with demyelination in the latter horses. Inflamed, non-demyelinating nerves were infiltrated with B lymphocytes and T lymphocytes; while inflamed, demyelinating nerves were infiltrated with mononuclear phagocytes. Our observations revealed lesion progression in the nerves, such that polyradiculoneuropathy could explain the accompanying neurological clinical signs of dourine. To our knowledge, this is the first report to describe a pathogenic mechanism for the development of the neurological clinical signs found in dourine-afflicted horses.

Molecular and histopathological characterization of Cryptosporidium and Eimeria species in bats in Japan.

Bats are potential reservoirs of Cryptosporidium and Eimeria. The genus Cryptosporidium infects various vertebrates and causes a diarrheal disease known as cryptosporidiosis. Many epidemiological studies in wild animals have been performed; however, most of them relied on only PCR-based detection because of the difficulty of performing pathological analyses. Accordingly, the natural host and pathogenicity of Cryptosporidium bat genotypes remain unclear. In this study, we captured Eptesicus nilssonii (Northern bats) in Hokkaido, Japan. Of the three intestinal samples obtained, two were positive for Cryptosporidium spp. and one was positive for Eimeria spp. The corresponding microorganisms were also confirmed histopathologically. We detected the novel Cryptosporidium bat genotype XII and Eimeria rioarribaensis in bat intestine.

Histopathological study of encephalomalacia in neonatal calves and application of neuronal and axonal degeneration marker.

Five calves that had shown neurological symptoms within 9 days after birth were histopathologically diagnosed as encephalomalacia. Two calves showed bilateral laminar cerebrocortical necrosis and neuronal necrosis in the corpus striatum and hippocampus. Since the distributional pattern of the lesions was consistent with that of global ischemia in other species, the lesions were probably hypoxic/ischemic encephalopathy consistent with the history of dystocia and perinatal asphyxia. One calf also showed bilateral laminar cerebrocortical necrosis. However, the lesions were chronic ones, because the calf had survived for long time and necropsied at postnatal day 118. Additionally, the lesions did not involve the corpus striatum and hippocampus. The other two calves showed multifocal necrosis with vascular lesions characterized by fibrin thrombi, perivascular edema and perivascular hyaline droplets in the cerebral cortex, corpus striatum, thalamus, brain stem and cerebellum. Considering the age of onsets and histopathological appearance, it was possible that latter three calves were also hypoxic/ischemic encephalopathy, however, exact cause of them was not revealed. In all calves, degenerated/necrotic neurons showed positive reactions for Fluoro-Jade C and degenerated axons showed immunoreactivity for Alzheimer precursor protein A4. Therefore, these markers were applicable to examination of brain injury in neonatal calves.

A clinical case of neosporosis in a 4-week-old holstein friesian calf which developed hindlimb paresis postnatally.

A 4-week-old female Holstein Friesian calf presented with hindlimb paresis. Neurologic examination of spinal reflexes revealed depressed or absent reflexes of the hindlimbs. Menace responses on both sides disappeared on examination of cranial nerves. The calf was finally diagnosed with Neospora caninum infection by pathological findings including nonsuppurative inflammation associated with cysts in the cerebrum and spinal cord. High levels of antibody against recombinant surface antigen 1 of N. caninum (NcSAG1) were detected by ELISA from both serum and cerebrospinal fluid (CSF) samples. This result suggests that detection of antibodies against N. caninum by NcSAG1-ELISA in serum and CSF could be useful for the clinical diagnosis of neosporosis in calves with acquired neurological signs.

Fibrinous pericarditis secondary to bacterial infection in a cat.

A three-year-old spayed domestic short-haired cat presented for evaluation of weight loss, cardiomegaly and pleural effusion. Echocardiographic examination demonstrated a thickened pericardium with mild pericardial effusion and a large volume of pleural effusion characterized by exudate. Although the cat was treated with antibiotics, the clinical symptoms did not improve. The cat developed dyspnea and died on day 7. Necropsy revealed a large amount of modified transudates ascites, pleural effusion and markedly dilated pericardium. Histopathological examination revealed severe exudation of fibrin and granulation tissue in a thick layer of the epicardium. The cat was diagnosed with fibrinous pericarditis secondary to bacterial infection.

Periventricular leukomalacia in a neonatal calf.

A 10-day-old, Japanese Black, female calf had shown astasia since just after birth. Focal symmetrical periventricular malacic lesions of the cerebrum and suppurative arthritis of the left hip joint were observed in macroscopic examination. Histologically, the cerebral lesions were confirmed as periventricular leukomalacia (PVL). The location and histological features of the lesions were similar to PVL in humans, caused by neonatal ischemia/hypovolemia. This is the first report of PVL in a neonatal calf.

Dextran sulfate inhibits acute Toxoplama gondii infection in pigs.

BACKGROUND: Toxoplasma gondii is a highly prevalent protozoan that can infect all warm-blooded animals, including humans. Its definitive hosts are Felidae and its intermediate hosts include various other mammals and birds, including pigs. It is found in the meat of livestock which is a major source of human infection. Hence the control of toxoplasmosis in pigs is important for public health. We previously showed that dextran sulfate (DS), especially DS10 (dextran sulfate MW 10 kDa), is effective against T. gondii infection both in vitro and in mice. In this study, we asked whether DS affects T. gondii infection of pigs, one of the main animal sources of toxoplasmosis transmission to humans. METHODS: Fourteen-day-old male pigs (n = 10) were infected with T. gondii and then immediately treated with different doses of DS10; clinical, pathological, and immunological analyses were performed 5 days post-infection. RESULTS: DS10 had an inhibitory effect on toxoplasmosis in pigs. Intravenous injection of DS10 prevented the symptoms of toxoplasmosis and reduced the parasite burden and inflammation induced by T. gondii infection. High-dose DS10 (500 µg per head) caused reversible hepatocellular degeneration of the liver; middle-dose DS10 (50 µg per head) was effective against toxoplasmosis in pigs without causing this side effect. CONCLUSIONS: Our data suggest that middle-dose DS10 led to minimal clinical symptoms of T. gondii infection and caused little hepatocellular degeneration in our pig model, thereby demonstrating its potential as a new treatment for toxoplasmosis. These data should be very beneficial to those interested in the control of toxoplasmosis in pigs.

Enhanced proliferation of hepatic progenitor cells in rats after portal branch occlusion.

It is known that hepatic progenitor cells increase in number after liver injury caused by carcinogens, but this injury cannot be reproduced in humans. In order to create a practical source of hepatic progenitor cells, changes in the number of liver epithelial cells (LECs), a type of hepatic progenitor cell, were examined following partial interruption of the portal flow. Efficiency in this isolation procedure was investigated, and isolated LECs were transplanted into livers to demonstrate their differentiation into hepatocytes in vivo.A volume of 70% of Sprague-Dawley rat's livers was exposed to portal vein ligation. LECs, identified as alpha-fetoprotein (AFP)-positive and albumin-negative cells, were counted and LECs isolated from the portal vein ligated-lobe were characterized by immunostaining and Western blotting. Isolated cells were subjected to a 1-week-culture, and the number of colonies formed on dishes was counted. The cells were then transplanted to the livers of genetic analbuminemic rats and identified by immunohistochemistry. The number of LECs in the portal ligated-lobes on day 7 was 14.7 +/- 6.5 cells/1,000 hepatocytes: 18 times higher than numbers in a normal liver. A significant increase was noted from day 3 until day 28. Isolated LECs were AFP-positive, albumin-negative, and cytokeratin-19-positive cells. The number of colonies on the 7th day following portal vein ligation was 42 times higher than in a normal liver. After transplantation of the LECs to the analbuminemic rat, a cluster of albumin-producing cells was present until day 56, suggesting that they differentiate into hepatocytes. We conclude that after portal vein occlusion, the liver can be a good source of hepatic progenitor cell. These results open up the possibility of cellular transplantation for liver functional support in clinical settings.

Role of positron emission tomography with 2-deoxy-2-[18F]fluoro-D-glucose in evaluating the effects of arterial infusion chemotherapy and radiotherapy on pancreatic cancer.

BACKGROUND: This study evaluated the usefulness of positron emission tomography with 2-deoxy-2-[18F]fluoro-D-glucose (FDG-PET) in monitoring the response to continuous arterial infusion chemotherapy (CAI) combined with external radiation therapy (ERT) for unresectable pancreatic carcinomas. METHODS: Ten patients with unresectable pancreatic cancer were enrolled in this study. Computed tomography (CT) and FDG-PET were done before and after CAI (5-fluorouracil [FU], 500 mg/body per day) combined with ERT (50.4 Gy total dose). Tumor regression was evaluated by standardized uptake value (SUV) with FDG-PET, tumor size on CT, and changes in blood levels of carbohydrate antigen (CA) 19-9. The three methods of evaluation were compared. RESULTS: The ten patients were classified in three categories. In category I, tumor changes evident on CT and FDG-PET were consistent. In category II, CT could not accurately detect the area of the tumor. However, tumor uptake on FDG-PET decreased markedly after the treatment in category II patients. In category III, both CT and FDG-PET detected the tumor, as in category I. Although there was no definite change in tumor size on CT, FDG-PET uptake was markedly reduced immediately after the treatment. Reduction in tumor size did not appear on CT until 2 months later. CONCLUSIONS: FDG-PET aids in analysis of the effectiveness of chemotherapy and/or radiotherapy.

Outcomes and indications of segmental pancreatectomy. Comparison with distal pancreatectomy.

BACKGROUND/AIM: To preserve pancreatic function, segmental pancreatectomy has been proposed for benign or low-malignancy tumors in the pancreatic body. Indications for the procedure, however, are still controversial. METHODS: In this study, we investigated the advantages and disadvantages of segmental pancreatectomy compared with distal pancreatectomy and subsequently determined indications for segmental pancreatectomy. RESULTS: The distal pancreatectomy patients had shorter operation times, lower incidence of operative complications, and shorter hospital stays compared to segmental pancreatectomy patients. Endocrine function in distal pancreatectomy patients deteriorated compared to that of segmental pancreatectomy patients. The postoperative 75-gram oral glucose tolerance test showed a diabetic pattern in 3 of 7 distal pancreatectomy patients, whereas none of the segmental pancreatectomy patients became diabetic after surgery. The relation between the length of the removed pancreas and plasma glucose at 2 h after the 75-gram glucose intake showed a significant correlation. CONCLUSION: According to our results, if the length of removed pancreas is longer than 12 cm, the patients will have a risk of acquiring diabetes. In those cases, the segmental pancreatectomy should be considered.

Efficacy of continuous infusion of prostaglandin E1 through the superior mesenteric artery against ischemic liver cell necrosis after hepatic artery occlusion.

BACKGROUND: Hepatic artery occlusion (HAO) can cause severe ischemic liver injury, especially after an interruption of collateral circulation after extensive hepatobiliary surgery. To minimize a decrease in oxygen delivery after HAO, a continuous infusion of prostaglandin (PG)E1 through the superior mesenteric artery (SMA) was studied in comparison with other infusion routes. METHODS: Twenty-four pigs were assigned to four groups: HAO without PGE1 (control group); HAO with PGE1 (0.02 microg/kg/min, continuously) through the jugular vein (intravenous group); HAO with PGE1 through the portal vein (PV group); and HAO with PGE1 through the SMA (SMA group). PV flow, hepatic oxygen delivery, and serum aspartate aminotransferase were measured after infusion. In addition, 72-hr survival rates were observed, and histologic examination of liver specimens was performed. RESULTS: PGE1 infusion through the SMA seems to affect PV flow and elevate the oxygen content of portal blood, whereas other routes of administration do not. The reduction of hepatic oxygen delivery after HAO was 51% in the control group, 46% in the intravenous group, and 49% in the PV group, whereas it was limited to 13% in the SMA group. Serum aspartate aminotransferase values 24 hr after HAO were lowest in the SMA group, which was statistically significant, as confirmed by histology. The survival rate of animals was 100% in the SMA group and 33% in the other three groups. CONCLUSION: These findings indicate that continuous PGE1 infusion through the SMA may prove useful in clinical settings to prevent liver damage after HAO.

Treatment for postoperative liver failure after major hepatectomy under hepatic total vascular exclusion.

Hepatic total vascular exclusion (HTVE) with clamping of the portal triad and the inferior vena cava below and above the liver is a useful technique in the resection of major hepatic lesions situated close to the hepatic veins and inferior vena cava. From 1996 to 2000, five patients underwent major hepatectomy under HTVE; among these, liver failure occurred in two patients because of liver cirrhosis or hepatic artery interruption. In the former case, apheresis therapy (plasma exchange: 9 times), continuous prostaglandin E, (PGE,) infusion via the hepatic artery(0.01 tg/kg/min) for 7 days, and hyperbaric oxygen therapy (3 times: 2 ATA, 60 min) were applied. In the latter case, apheresis therapy (plasma exchange: 9 times, continuous hemodiafiltration: 12 days) and continuous PGE, infusion via the superior mesenteric artery for 7 days were applied. With these treatment modalities, both cases were cured of postoperative liver failure.

Jejunal varix with extrahepatic portal obstruction treated by embolization using interventional radiology: report of a case.

We report a case of relapsing jejunal varix with extrahepatic portal obstruction, which was successfully treated by embolization using interventional radiology. A 79-year-old woman suffered repeated episodes of tarry stools 2 years after undergoing jejunal resection for a jejunal varix. The bleeding point was inferred to be in the small intestine, and abdominal angiography revealed extrahepatic portal obstruction and the development of a jejunal varix around the hepaticojejunostomy. Because surgical obliteration of the varices or a shunt operation for portal decompression may have been very invasive due to severe adhesions, the jejunal varix was embolized with anhydrous ethanol and interlocking detachable coils. There were no changes in liver enzymes, the clearance rate of indocyanine green, or portal pressure, and there has been no sign of rebleeding for 13 months. Our experience shows that hemostasis can last, as long as the embolization can be done without aggravating portal hypertension. In conclusion, embolization using interventional radiology is a safe and useful method of treating intestinal varices.

Two cases of hepatic artery interruption after hepatopancreatobiliary surgery treated by prostaglandin E(1) infusion via the superior mesenteric artery.

In two cases of hepatic arterial flow interruption after hepatopancreatic surgery, continuous PGE(1) infusion from the superior mesenteric artery (SMA) was applied to oxygenate the liver through the portal vein. Case 1 was a 69-year-old woman with a non-functioning islet cell tumor of the pancreas. She underwent pancreatic resection following hepatic arterial infusion of anticancer drugs. Serum alanine aminotransferase (ALT) was elevated to 5500 IU/l on postoperative day (POD) 2; angiography revealed complete celiac artery obstruction. Continuous PGE(1) was administered from SMA at a rate of 0.01 &mgr;g/kg/min for 7 days. Serum ALT was normalized within 2 weeks and the peak level of serum total bilirubin (T. Bil) was 4.5 mg/dl. Case 2 was a 66-year-old man suffering from metastatic liver cancer. Complete obstruction of the proper hepatic artery was noted at the time of liver resection after hepatic arterial chemotherapy. Serum ALT was elevated to 2930 IU/l on POD 1, and PGE(1) infusion from SMA was done for the succeeding 7 days. Necrotic area was so vast that serum T. Bil rose to 19 mg/dl. However, it decreased with time. Both cases required 3 months for necrotic liver shrinkage. Doppler ultrasonography revealed that PGE(1) infusion actually increased portal blood flow. In conclusion, based on the preceding experimental backgrounds and clinical experiences, continuous PGE(1) infusion via the SMA can be a useful measure to prevent severe liver damage after hepatic arterial flow interruption through portal blood oxygenation.

Positron emission tomography with 2-deoxy-2-[(18)F] fluoro- d-glucose for diagnosis of intraductal papillary mucinous tumor of the pancreas with parenchymal invasion.

We used positron emission tomography with 2-deoxy-2-[(18)F]fluoro- d-glucose (FDG-PET) in the diagnosis of two cases of malignant intraductal papillary mucinous tumor (IPMT) of the pancreas. A 56-year-old man and a 72-year-old man, both with tumors in the pancreatic head, were referred to Akita University Medical Center. Computed tomography revealed tumors with multiple cystic components in both patients. FDG-PET images showed markedly high FDG uptake in the area corresponding to a solid component found in one patient and diffuse faint uptake, higher than that of the surrounding tissue, in the other patient, who had no solid component. Histological examination of the resected specimens after pancreatectomy showed invasive carcinoma involving the pancreatic parenchyma in both patients. Although our experience is limited and preliminary, FDG-PET seems to be useful for the detection of malignancy in IPMT, especially in patients not showing any solid component on conventional diagnostic images such as computed tomography.

Management of pancreatic mass accompanying chronic pancreatitis.

We report two patients with focal, chronic pancreatitis that was diagnosed by dynamic computed tomography (CT) combined with intraoperative biopsy. In case 1, serum carbohydrate antigen (CA) 19-9 level rose to 160 U/ml. Abdominal ultrasonography, CT, and magnetic resonance imaging demonstrated a mass, of 4.5 cm in diameter, in the pancreatic head. On dynamic CT, the mass was enhanced similarly to the normal pancreatic parenchyma. In case 2, dynamic CT demonstrated a mass, of 3.0 cm in diameter, in the pancreatic head, which was enhanced similarly to the normal pancreatic parenchyma. From such characteristics of enhancement, both masses were suspected to be chronic pancreatitis rather than cancer, and the diagnosis was confirmed by intraoperative biopsy. Three years in case 1 and 2 years in case 2 have passed since their operations, and the size of each mass has not changed. With the use of dynamic CT combined with intraoperative biopsy, focal chronic pancreatitis could be diagnosed more accurately, and this may lead to a reduction in unnecessary pancreatic resection.

Uptake of indocyanine green by hepatocytes under inflow occlusion of the liver.

BACKGROUND: It is not clear that hepatic venous backflow actually contributes to hepatic tissue oxygenation under inflow occlusion of the liver. In order to prove that substances delivered via the hepatic vein can be utilized and/or metabolized in hepatocytes during inflow occlusion, hepatic uptake in bile and excretion of indocyanine green (ICG) were investigated in pigs. MATERIALS AND METHODS: Animals were divided into two groups: an inflow occlusion (IO) group (N = 6) and a total hepatic vascular exclusion (THVE) group (N = 3) using a bypass. One milligram of ICG per kilogram body weight was administered at the beginning of blood flow occlusion, the retention rate in the blood (ICG R) measured, and the ICG in the hepatic tissue measured by near-infrared (NIR) spectroscopy. Furthermore, the ICG concentration was measured in bile excreted by intermittent perfusion of the liver. RESULTS: ICG R declined with time in both groups; however, ICG R in the IO group decreased much faster than in the THVE group. There were significant differences between the two groups after 30 min of occlusion (P < 0.05). ICG in the hepatic tissue could be detected as a peak at 805 nm 10 min after ICG injection, and the peak became steeper with time. On the other hand, ICG was not detected at all in the hepatic tissue after 180 min in the THVE group. ICG was excreted in the bile after 60 min under IO and increased with time. On the contrary, ICG was not excreted in the bile at all under THVE. There were significant differences between the two groups after 90 min (P < 0.05). CONCLUSION: These results indicate that ICG can be extracted in hepatocytes and excreted in bile under IO of the liver. Consequently, substances such as oxygen and drugs, which are delivered via the hepatic vein, can be utilized and/or metabolized in hepatocytes under IO.