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  • Author or Editor: Robert J. Washabau x
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Abstract

Objectives—To determine the role of myosin light chain phosphorylation in feline colonic smooth muscle contraction.

Sample Population—Colonic tissue was obtained from eight 12- to 24-month-old cats.

Procedure—Colonic longitudinal smooth muscle strips were attached to isometric force transducers for measurements of isometric stress. Myosin light chain phosphorylation was determined by isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Stress and phosphorylation were determined following stimulation with ACh or SP, in the absence or presence of a calmodulin antagonist (W-7; 0.1 to 1.0 mM), myosin light chain kinase inhibitor (ML-9; 1 to 10 µM), or extracellular calcium - free solutions.

Results—Unstimulated longitudinal colonic smooth muscle contained low amounts (6.9 ± 3.2%) of phosphorylated myosin light chain. Phosphorylation of the myosin light chains was dose and time dependent with maximal values of 58.5% at 30 seconds of stimulation with 100 µM Ach and 60.2% at 45 seconds of stimulation with 100 nM SP. Active isometric stress development closely paralleled phosphorylation of the myosin light chains in ACh- or SP-stimulated muscle. W-7 and ML-9 dose dependently inhibited myosin light chain phosphorylation and isometric stress development associated with ACh or SP stimulation. Removal of extracellular calcium inhibited myosin light chain phosphorylation and isometric stress development in ACh-stimulated smooth muscle.

Conclusions and Clinical Relevance—Feline longitudinal colonic smooth muscle contraction is calcium-, calmodulin-, and myosin light chain kinasedependent. Myosin light chain phosphorylation is necessary for the initiation of contraction in feline longitudinal colonic smooth muscle. These findings may prove useful in determining the biochemical and molecular defects that accompany feline colonic motility disorders. (Am J Vet Res 2002;63:695–702)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the incidence and prognostic significance of low plasma ionized calcium concentration in cats with clinical signs of acute pancreatitis (AP).

Design—Retrospective study.

Animals—46 cats with AP and 92 control cats with nonpancreatic diseases.

Procedure—Medical records were reviewed, and results of clinicopathologic testing, including plasma ionized and total calcium concentrations, acid-base values, and electrolyte concentrations, were recorded. Cats with AP were grouped on the basis of outcome (survived vs died or were euthanatized), and plasma ionized calcium concentrations, acid-base values, and electrolyte concentrations were compared between groups.

Results—Serum total calcium concentration was low in 19 (41%) cats with AP, and plasma ionized calcium concentration was low in 28 (61%). Cats with AP had a significantly lower median plasma ionized calcium concentration (1.07 mmol/L) than did control cats (1.12 mmol/L). Nineteen (41%) cats with AP died or were euthanatized; these cats had a significantly lower median plasma ionized calcium concentration (1.00 mmol/L) than did cats that survived (1.12 mmol/L). Ten of the 13 cats with AP that had plasma ionized calcium concentrations ≤ 1.00 mmol/L died or were euthanatized.

Conclusions and Clinical Relevance—Results suggest that low plasma ionized calcium concentration is common in cats with AP and is associated with a poorer outcome. A grave prognosis and aggressive medical treatment are warranted for cats with AP that have a plasma ionized calcium concentration ≤ 1.00 mmol/L. (J Am Vet Med Assoc 2001;219:1105–1109)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine effects of short-chain fatty acids (SCFA) on canine colonic smooth muscle.

Sample Population—Colonic tissue obtained from 14 healthy dogs.

Procedure—Short-chain fatty acid (SCFA; acetate, propionate, and butyrate; 1 to 100 mmol/L)-induced contractions were compared with responses obtained with acetylmethylcholine (AMCh; 10-4 mol/L). Roles of enteric neurons, cholinergic receptors, calcium stores in the sarcoplasmic reticulum, and extracellular calcium in the SCFA-induced responses were investigated by incubating muscle strips with tetrodotoxin (1 µmol/L), atropine (1 µmol/L), ryanodine (10 µmol/L), nifedipine (1 µmol/L), ethylene glycol-bis (β-aminoethylether)-N,N,N',N'-tetra-acetate (EGTA; 0.1 mmol/L), or an extracellular calciumdepleted (zero extracellular calcium) solution prior to the addition of propionate or butyrate.

Results—Incubation with SCFA elicited isometric stress responses (0.25 to 2.15 × 104 N/m2) in colonic longitudinal smooth muscle. Maximal responses to butyrate and propionate (50 mmol/L) were 37 and 23%, respectively, of the maximal AMCh response. Acetate was least effective in stimulating contractile responses. Tetrodotoxin and atropine did not affect SCFA-induced contractions. Nifedipine and zero extracellular calcium solution abolished responses to butyrate and propionate, whereas EGTA attenuated (> 60%) but did not abolish those responses. Ryanodine did not affect SCFA-induced contractile responses. The SCFA did not affect colonic circular smooth muscle.

Conclusions and Clinical Relevance—The SCFA stimulate longitudinal but not circular colonic smooth muscle contractions via a direct effect on smooth muscle. The mechanism of the SCFA effect appears to involve the influx of extracellular calcium. These findings may account for some of the effects of canine colonisc motility. (Am J Vet Res 2002;63:295–300 )

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in American Journal of Veterinary Research

Abstract

Objective—To determine ultrasonographic findings in cats with clinical, gross pathologic, and histologic evidence of acute pancreatic necrosis.

Design—Retrospective study.

Animals—20 cats.

Procedure—Ultrasound reports and permanent ultrasonographic images were reviewed, and ultrasonographic findings were recorded. Thoracic and abdominal radiographs were also reviewed, when available. Anatomic localization of pancreatic necrosis was determined from the gross pathology report; duration and severity of pancreatic necrosis were determined by reviewing histologic specimens. The presence of concurrent disease was recorded from the final pathology report.

Results—The pancreas was considered ultrasonographically normal in 10 cats and was not observed in 3. Ultrasonographic findings were considered compatible with pancreatitis in the remaining 7 cats. Gross pathologic findings indicated that pancreatitis was multifocal in all 7 of these cats; histologically, pancreatitis was acute or subacute in 5 and associated with severe or moderate necrosis in 6. In the remaining 13 cats, gross pathologic findings indicated that pancreatitis was multifocal (n = 8) or focal (2), or gross pathologic findings were normal (3). Histologically, pancreatitis was peracute or acute in 11 of these 13 cats and associated with severe or moderate necrosis in 8. Thoracic and abdominal radiographic findings were nonspecific.

Conclusions and Clinical Relevance—Results of ultrasonography were consistent with a diagnosis of pancreatitis in only 7 of 20 cats with acute pancreatic necrosis in the present study. This suggests that new diagnostic criteria must be established if abdominal ultrasonography is to be an effective tool in the diagnosis of pancreatitis in cats. (J Am Vet Med Assoc 2002;221:1724–1730)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine signalment, history, and outcome of cats with gastrointestinal tract intussusception and to identify physical examination, diagnostic imaging, surgical, histologic, and necropsy findings in affected cats.

Design—Retrospective case series.

Animals—20 cats with intussusception.

Procedures—Medical records were evaluated for information on signalment; history; physical examination, diagnostic imaging, surgical, histologic, and necropsy findings; and outcome.

Results—Ten cats were < 1 year old, and 9 were ≥ 6 years old. Anorexia (14/17), lethargy (12/17), and vomiting (12/17) were the most common reasons for examination. Dehydration (13/18), poor body condition (12/18), signs of abdominal pain (8/18), and an abdominal mass (8/18) were the most common physical examination findings. Abdominal radiography revealed intestinal obstruction in all 10 cats in which it was performed; abdominal ultrasonography revealed intussusception in all 7 cats in which it was performed. The most common intussusception was jejuno-jejunal (8/20), and no intussusceptions were found proximal to the duodenum. Eleven of 13 cats that underwent laparotomy required intestinal resection and anastomosis. Histologic examination revealed intestinal lymphoma or inflammatory bowel disease in 7 of 8 cats ≥ 6 years old and idiopathic intussusception in 7 of 8 cats < 1 year old.

Conclusions and Clinical Relevance—Results suggested that in cats, intussusception has a bimodal age distribution, is most commonly jejuno-jejunal, often requires surgical resection and anastomosis, is often associated with alimentary lymphoma or inflammatory bowel disease in older cats, and is readily diagnosed by means of ultrasonography.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether glutamine (GLN), tryptophan (TRP), and tryptophan metabolite concentrations are higher in cerebralspinal fluid (CSF) dogs with naturally occurring portosystemic shunts (PSS), compared with control dogs.

Animals—11 dogs with confirmed PSS and 12 control dogs fed low- and high-protein diets.

Procedure—Cerebrospinal fluid and blood samples were collected from all dogs. Serum and CSF concentrations of GLN, alanine, serine, TRP, 5-hydroxyindoleacetic acid (5-HIAA), and quinolinic acid (QUIN) were measured.

Results—Cerebrospinal fluid concentrations of GLN, TRP, and 5-HIAA were significantly higher in PSS dogs, compared with control dogs fed high- or lowprotein diets. Cerebrospinal fluid QUIN concentration was significantly higher in PSS dogs, compared with control dogs fed the low-protein diet. Serum QUIN concentration was significantly lower in PSS dogs, compared with control dogs fed either high- or lowprotein diets.

Conclusions and Clinical Relevance—An increase in CNS GLN concentration is associated with high CSF concentrations of TRP and TRP metabolites in dogs with PSS. High CSF 5-HIAA concentrations indicate an increased flux of TRP through the CNS serotonin metabolic pathway, whereas high CSF QUIN concentrations indicate an increased metabolism of TRP through the indolamine-2,3-dioxygenase pathway. The high CSF QUIN concentrations in the face of low serum QUIN concentrations in dogs with PSS indicates that QUIN production from TRP is occurring in the CNS. High concentrations of QUIN and other TRP metabolites in the CNS may contribute to neurologic abnormalities found in dogs with PSS and hepatic encephalopathy. (Am J Vet Res 2002;63:1167–1171)

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in American Journal of Veterinary Research

Abstract

Objective—To characterize the clinical, clinicopathologic, and imaging findings in dogs with intestinal lymphangiectasia and to compare the histologic grade of lymphangiectasia with clinicopathologic and imaging abnormalities.

Design—Retrospective study.

Animals—17 dogs with a histologic diagnosis of intestinal lymphangiectasia.

Procedure—Medical records of dogs with a histologic diagnosis of intestinal lymphangiectasia were reviewed for signalment, history, clinical signs, results of exploratory laparotomy, and clinicopathologic, radiographic, ultrasonographic, and histologic findings.

Results—Mean age of dogs was 8.3 years; the most common clinical signs were diarrhea, anorexia, lethargy, vomiting, and weight loss. Abnormal physical examination findings included dehydration, ascites, and signs of pain on palpation of the abdomen. The most notable clinicopathologic findings were low serum ionized calcium concentration and hypoalbuminemia. Abdominal ultrasonography was performed in 12 dogs and revealed intestinal abnormalities in 8 dogs and peritoneal effusion in 7 dogs. Exploratory laparotomy revealed abnormalities in 9 of 16 dogs including thickened small intestine, dilated lacteals, lymphadenopathy, and adhesions. On histologic examination of the small intestine, concurrent inflammation was observed in 15 of 17 dogs, crypt ectasia in 5 of 17, and lipogranulomas in 2 of 17.

Conclusions and Clinical Relevance—Intestinal lymphangiectasia in dogs appears to be a heterogeneous disorder characterized by various degrees of panhypoproteinemia, hypocholesterolemia, lymphocytopenia, and imaging abnormalities. In most dogs, the severity of hypoalbuminemia appears to offer the best correlation with severity of histologic lesions of lymphangiectasia. Imaging abnormalities are common in dogs with intestinal lymphangiectasia but are not specific enough to differentiate this disorder from other gastrointestinal disorders, nor are they predictive of histologic severity. (J Am Vet Med Assoc 2001;219:197–202)

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in Journal of the American Veterinary Medical Association

Abstract

Case Description—1 dog evaluated because of inappetence and lameness of the left hind limb of 1 day's duration and 1 dog evaluated because of inappetence, fever, and lymphadenopathy of 2 weeks' duration.

Clinical Findings—Histologic examination of excisional biopsy specimens from lymph nodes revealed pyogranulomatous lymphadenitis in both dogs. Quantitative real-time PCR assays detected Bartonella henselae DNA in blood samples and affected lymph node specimens from both dogs. Antibodies against B henselae were not detected via immunofluorescent antibody testing during active disease in either dog.

Treatment and Outcome—1 dog recovered after 6 weeks of treatment with doxycycline (5 mg/kg [2.3 mg/lb], PO, q 12 h), whereas the other dog recovered after receiving a combination of azithromycin (14.5 mg/kg [6.6 mg/lb], PO, q 24 h for 21 days), doxycycline (17.3 mg/kg [7.9 mg/lb], PO, q 24 h for 4 weeks), and immunosuppressive corticosteroid (prednisone [3 mg/kg {1.4 mg/lb}, PO, q 24 h], tapered by decreasing the daily dose by 25% every 2 weeks) treatment.

Clinical RelevanceB henselae is implicated as a possible cause or a cofactor in the development of pyogranulomatous lymphadenitis in dogs. In dogs with pyogranulomatous lymphadenitis, immunofluorescent assays may not detect antibodies against B henselae. Molecular testing, including PCR assay of affected tissues, may provide an alternative diagnostic method for detection of B henselae DNA in pyogranulomatous lymph nodes.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To characterize clinical, clinicopathologic, radiographic, and ultrasonographic findings in cats with histologically confirmed acute necrotizing pancreatitis (ANP) or chronic nonsuppurative pancreatitis (CP) and identify features that may be useful in the antemortem differentiation of these disorders.

Design—Retrospective study.

Animals—63 cats with histologically confirmed ANP (n = 30) or CP (33).

Procedure—Medical records were reviewed for signalment, clinical signs, concurrent diseases, clinicopathologic findings, and results of radiography and ultrasonography.

Results—Cats in both groups had similar nonspecific clinical signs, physical examination findings, and radiographic and ultrasonographic abnormalities. Abdominal ultrasonographic abnormalities, including hypoechoic pancreas, hyperechoic mesentery, and abdominal effusion, were found in cats in both groups and, therefore, were not specific for ANP. Cats with CP were significantly more likely to have concurrent diseases than were cats with ANP (100 and 83%, respectively). Clinicopathologic abnormalities were similar between groups; however, serum alanine aminotransferase and alkaline phosphatase activities were significantly higher in cats with CP.

Conclusions and Clinical Relevance—Results suggest that ANP and CP in cats cannot be distinguished from each other solely on the basis of history, physical examination findings, results of clinicopathologic testing, radiographic abnormalities, or ultrasonographic abnormalities. (J Am Vet Med Assoc 2003;223:469–474)

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in Journal of the American Veterinary Medical Association