Tetsuya Nakade

Chlamydial infection in canine atherosclerotic lesions.

We attempted to detect chlamydial antigens in canine atherosclerotic lesions from seven dogs by immunohistochemical technique using anti-Chlamydia psittaci (C. psittaci) polyclonal and anti-C. pneumoniae monoclonal antibodies. Immunopositive signals to both antibodies were recognized in the atherosclerotic lesions of the aortas, coronary and splenic arteries of all dogs. Positive signals were found in the foamy cytoplasm of infiltrated macrophages and extracellular matrices in the lesions. In some lesions, cytoplasm of the endothelial cells and smooth muscle cells was also immunopositive against both antibodies. By electron microscopy, chlamydial microorganisms were found in the cytoplasm of endothelial cells and smooth muscle cells. Using polymerase chain reaction (PCR), detection of C. pneumoniae DNAs were performed in the spleen, heart (coronary arteries) and kidney in one of the seven dogs. Positive 314 bp PCR products were obtained in all samples of the dog. These results confirmed the presence of viable Chlamydiae in atheromas and supported the conclusion that the organism may be an active factor in the pathogenesis of canine, as well as human atherosclerosis.

Babesia canis infection in canine-red blood cell-substituted SCID mice

We have developed a mouse model for Babesia canis infection using severe combined immunodeficiency (SCID) mice whose circulating red blood cells had been substituted with canine red blood cells. Substitution of red blood cells in SCID mice was achieved by repetitive transfusions of canine red blood cells, together with administration of an antimouse red blood cell monoclonal antibody. Following inoculation of canine-red blood cell-SCID mice with B. canis, parasites proliferated in the canine red blood cells that had been transfused into the SCID mice, resulting in much higher parasitaemia than that observed in dogs. In an attempt to demonstrate the utility of this mouse model, three antiprotozoal drugs, diminazene diaceturate, clindamycin and oxytetracycline, were examined for their efficacy to inhibit the growth of B. canis in canine-red blood cell-SCID mice. The mouse model clearly showed that diminazene diaceturate and oxytetracycline were capable of eliminating B. canis from the canine-red blood cell-SCID mice, whereas clindamycin exhibited only a static effect as parasitaemia relapsed upon cessation of drug administration.

Lead Poisoning in Whooper and Tundra Swans

Six weak whooper swans (Cygnus cygnus) and two weak tundra swans (Cygnus columbianus) were found at Swamp Miyajima (Hokkaido, Japan) in May 1998. Anorexia, depression, green watery feces, pale conjunctiva, and anemia were observed. Radiographs showed from six to 38 suspected lead pellets in the gizzard. Blood lead concentrations were 2.5–6.7 μg/g (mean±SD=4.6±1.14 μg/g) on day 1. After blood collection, the birds were treated with calcium disodium ethylenediaminetetraacetate (CaEDTA) given intravenously and force fed. Despite treatment, seven birds died the next day. Green, bile-stained livers and pale or green kidneys were observed on necropsy. Microscopically, bile pigment was widespread in the liver and acid-fast intranuclear inclusion bodies were observed in renal tubular epithelium. Lead concentrations in livers and kidneys were 14.0–30.4 μg/g and 30.2–122 μg/g wet weight, respectively. Only one bird survived and this whooper swan continued to be treated with CaEDTA and activated charcoal. No lead shot was observed in the proventriculus and gizzard by radiography on day 64 and the blood lead concentration decreased from 2.9 μg/g to 0.09 μg/g during that same period. After 4 mo of rehabilitation, the whooper swan was returned to the wild. Lead intoxication continues to be a problem at Swamp Miyajima.

CONTRAST AGENT Gd-EOB-DTPA (EOB·Primovist®) FOR LOW-FIELD MAGNETIC RESONANCE IMAGING OF CANINE FOCAL LIVER LESIONS

Contrast-enhanced magnetic resonance (MR) imaging with a new liver-specific contrast agent gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA; EOB·Primovist®) was studied in 14 normal beagles and 9 dogs with focal liver lesions. Gd-EOB-DTPA accumulates in normally functioning hepatocytes 20 min after injection. As with Gd-DTPA, it is also possible to perform a dynamic multiphasic examination of the liver with Gd-EOB-DTPA, including an arterial phase and a portal venous phase. First, a reliable protocol was developed and the appropriate timings for the dynamic study and the parenchymal phase in normal dogs using Gd-EOB-DTPA were determined. Second, the patterns of these images were evaluated in patient dogs with hepatic masses. The optimal time of arterial imaging was from 15 s after injection, and the optimal time for portal venous imaging was from 40 s after injection. Meanwhile, the optimal time to observe changes during the hepatobiliary phase was from 20 min after injection. In patient dogs, 11 lesions were diagnosed as malignant tumors; all were hypointense to the surrounding normal liver parenchyma during the hepatobiliary phase. Even with a low-field MR imaging unit, the sequences afforded images adequate to visualize the liver parenchyma and to detect tumors within an appropriate scan time. Contrast-enhanced MR imaging with Gd-EOB-DTPA provides good demarcation on low-field MR imaging for diagnosing canine focal liver lesions.

Matrix metalloproteinase (MMP) 9 induced in skin and subcutaneous tissue by implanted chitin in rats.

Chitin was found to induce matrix metalloproteinases (MMPs) activity in rat skin and subcutaneous tissue. Sponge type chitin (22.5 mg) was implanted in subcutaneous tissue of 8-week-old rats by skin incision. MMPs activity was more pronounced in the chitin-treated group than only incision group until on day 2.5 postoperatively. Gelatin zymography revealed that the induced MMPs had a molecular mass of 92 and 82 kDa corresponding to MMP-9 and pro MMP-9, respectively. We here discuss the mechanism of MMP induction by chitin.

Surgical resection of twenty-three cases of brain meningioma.

ABSTRACT The aim of this study was to report the effectiveness of MRI scanning during brain meningioma resection surgery in the canine and feline. The subjects were 23 cases from 2006 to 2008 in canines and feline diagnosed with meningioma. All were between 8 and 16 years of ages. There were 12 males and 11 females. An appropriate craniotomy was performed for each case according to the initial MRI taken to diagnose meningioma prior to the surgery. Once the dura mater was exposed, an MRI biopsy needle was placed in the tumor as a guide. The first MRI sequence during the surgery was performed with this needle to confirm the location of the tumor. This MRI image was also processed and displayed by multi planar reconstruction to reveal the tumor extent in three dimensions. A Sonopet was applied to the middle of the tumor to destroy the inner part and release pressure from the entire tumor. Creating some space between the brain tissue and tumor, we treated blood vessels and carefully resected them. This procedure was repeated until complete removal of the tumor was confirmed by MRI. Sixteen of the 23 cases survived for more than 2 years postoperatively. The other seven died due to other disorders within 2 years. Our method with MRI navigation during the surgery improved our surgical performance and contributed to a prolonged survival time for the patients. In order to perform multiple MRI procedures smoothly during the surgery, it is necessary to have skillful assistants.

Sterol composition in polyene antibiotic-sensitive and resistant strains of Malassezia pachydermatis.

The membrane sterol compositions of ten strains ofMalassezia pachydermatis were analysed by gas-liquid chromatography. Six of these were wild-type strains from clinical sources that were sensitive to polyene antibiotics, whereas the other four strains were resistant mutants that had arisen after treatment withN-methyl-N′-nitrosoguanidine or UV radiation.The wild-type strains contained 838.8 to 1291.7 µg of sterol per gram of freeze-dried mycelium. The sterols were composed of 79% ergosterol, 19% fecosterol and 2% lichesterol. The mutant strains contained 277.1 to 348.8 µg/g of sterols composed of 76% ergosterol and 24% fecosterol.

Porencephaly in dogs and cats: relationships between magnetic resonance imaging (MRI) features and hippocampal atrophy

Porencephaly is the congenital cerebral defect and a rare malformation and described few MRI reports in veterinary medicine. MRI features of porencephaly are recognized the coexistence with the unilateral/bilateral hippocampal atrophy, caused by the seizure symptoms in human medicine. We studied 2 dogs and 1 cat with congenital porencephaly to characterize the clinical signs and MRI, and to discuss the associated MRI with hippocampal atrophy. The main clinical sign was the seizure symptoms, and all had hippocampal atrophy at the lesion side or the larger defect side. There is association between hippocampal atrophy or the cyst volume and the severe of clinical signs, and it is suggested that porencephaly coexists with hippocampal atrophy as well as humans in this study.

Comparison between indocyanine green angiography and fluorescein angiography in normal cats

OBJECTIVE To study a new approach to indocyanine green (ICG) angiography for contrasting the ocular fundus in cats. ANIMALS STUDIED Six healthy laboratory cats. PROCEDURES Fluorescein (FLUO) and ICG angiography were performed using an infrared-sensitive charged coupled device-equipped fundus camera on sedated cats. RESULTS At 12.3 ± 3.4 s after ICG administration, the choroidal arteries could be seen extending radially from the optic disk. The choroidal veins became apparent at 16.2 ± 4.1 s alongside the choroidal arteries. Gradual fading of the choroidal vessels began 5.8 ± 1.5 min postdye administration and diffuse fluorescence of the fundus appeared. Diffuse fluorescence of the optic disk faded at about 18.8 ± 2.9 min. Mean arterial blood pressure at 1 and 3 min after ICG administration showed no significant change when compared to pre-administration (P > 0.05). However, 5 min (P = 0.054) and 10 min (P < 0.05) postadministration, a significant drop in blood pressure occurred. The time lapse between FLUO administration and its appearance in the ocular fundus was 15.7 ± 3.8 s. Retinal veins became apparent at 22.0 ± 3.6 s alongside retinal arteries. At 31.2 ± 4.1 s, full venous fluorescence was visualized throughout the entire fundus. CONCLUSIONS While FLUO angiography shows only the retinal vessels, ICG angiography enabled visualization of the choroidal vasculature. ICG angiography provides clear resolution while remaining reliable and simple; thus, a combination of ICG and FLUO angiography shows promise as a diagnostic aid for clinical evaluation of various chorioretinal diseases in cats.

Tolerance of repeated anesthesia with ketamine hydrochloride in dogs.

12頭の雑種成犬を用い, 塩酸ケタミン5mg/kgまたは10mg/kgを3日おきに計10回静脈内に反復投与し, その影響を観察した。痛覚回復, 起立および歩行までに要したそれぞれの時間は, 短縮する傾向がみられ, それは耐性の発現によるものと考えられた。血圧, 心拍数, 呼吸数および体温では, 反復投与の影響は観察されず, また他の特記されるべき副作用もみられなかった。これらのことより, ケタミン反復投与のリスクは小さく, 臨床応用が可能であるが, 使用にあたっては, 耐性の発現と投薬量について検討する必要があると思われた。