Comparison of abdominal ultrasound and magnetic resonance imaging for detection of abdominal lymphadenopathy in dogs with metastatic apocrine gland adenocarcinoma of the anal sac.

Imaging studies in humans with anal and rectal cancer indicate that magnetic resonance imaging (MRI) is a more sensitive technique than abdominal ultrasound (AUS) for the detection of abdominal lymphadenopathy. The purpose of this retrospective study was to directly compare the efficacy of these two techniques in detecting abdominal lymphadenopathy in dogs with apocrine gland adenocarcinoma of the anal sac (AGAAS). Six dogs with histologically confirmed AGAAS and histopathologic confirmation of metastasis to abdominal lymph nodes (LNs) had AUS and abdominal MRI. AUS identified lymphadenopathy in two of six dogs, whereas MRI identified lymphadenopathy in all the six dogs. Lymphadenopathy was predominantly sacral in location, with involvement of the medial iliac and hypogastric LNs in only two cases. These data suggest that MRI is more sensitive than AUS for detecting sacral abdominal lymphadenopathy in dogs with AGAAS. As such, MRI could be considered in any patient with AGAAS for initial staging of this disease.

In situ hybridization for the identification of filamentous fungi in tissue section.

Identification of fungi in tissue sections can be difficult because of limited biopsy tissue with only a few organisms present, or mycelial elements may be the only forms present, rendering common organism types indistinguishable from one another. In situ hybridization may assist in the rapid and accurate identification of such fungi. In this study, DNA probes were directed against the 5S or 18S ribosomal RNA sequences of three groups of fungi with a high degree of specificity for each. Two of the three, Aspergillus and Zygomycetes species, are usually seen in tissue purely in their hyphal forms. The third, Candida species is seen less commonly as predominantly mycelial elements. Probes were tested on 61 formalin-fixed, paraffin-embedded tissue specimens, each with culture-proven involvement by one of these organisms (Candida species, n = 21; Aspergillus species, n = 27; Zygomycetes, n = 13). Accuracy of both in situ hybridization (ISH) and morphology, based on the examination of Grocott methanamine silver (GMS)- and periodic acid-Schiff (PAS)-stained slides, was compared with culture. The results showed that morphologic examination (GMS and PAS) showed a slightly greater sensitivity in detecting the presence of fungi (98%) compared with in situ hybridization (95%). DNA probes, however, were more accurate in correctly identifying those organisms present. Although ISH specific probes showed 97% positive predictive value (PPV), examination of GMS-and PAS-stained slides had an 86% PPV when compared with culture-based identification methods. These results show that ISH, directed against ribosomal RNA, provides a rapid and accurate technique for the identification of mycelial fungal organisms in histologic tissue sections. Its primary use lies in the ability to accurately distinguish between organisms that have similar or identical morphologic features by light microscopy.

Functional interaction between fluorodeoxyuridine-induced cellular alterations and replication of a ribonucleotide reductase-negative herpes simplex virus.

G207 is an oncolytic herpes simplex virus (HSV) which is attenuated by inactivation of viral ribonucleotide reductase (RR) and deletion of both gamma(1)34.5 genes. The cellular counterparts that can functionally substitute for viral RR and the carboxyl-terminal domain of ICP34.5 are cellular RR and the corresponding homologous domain of the growth arrest and DNA damage protein 34 (GADD34), respectively. Because the thymidylate synthetase (TS) inhibitor fluorodeoxyuridine (FUdR) can alter expression of cellular RR and GADD34, we examined the effect of FUdR on G207 bioactivity with the hypothesis that FUdR-induced cellular changes will alter viral proliferation and cytotoxicity. Replication of wild-type HSV-1 was impaired in the presence of 10 nM FUdR, whereas G207 demonstrated increased replication under the same conditions. Combined use of FUdR and G207 resulted in synergistic cytotoxicity. FUdR exposure caused elevation of RR activity at 10 and 100 nM, whereas GADD34 was induced only at 100 nM. The effect of enhanced viral replication by FUdR was suppressed by hydroxyurea, a known inhibitor of RR. These results demonstrate that the growth advantage of G207 in FUdR-treated cells is primarily based on an RR-dependent mechanism. Although our findings show that TS inhibition impairs viral replication, the FUdR-induced RR elevation may overcome this disadvantage, resulting in enhanced replication of G207. These data provide the cellular basis for the combined use of RR-negative HSV mutants and TS inhibitors in the treatment of cancer.

Quantitative hepatobiliary scintigraphy in normal cats and in cats with experimental cholangiohepatitis.

Quantitative hepatobiliary scintigraphy using 99mTc-mebrofenin was performed on eight normal cats and on the same cats after induction of experimental cholangiohepatitis by infection with the liver fluke Platynosomum concinnum. Hepatobiliary scintigraphy was performed 3 times at 10 weeks, 4 months and 6 months after infection. In addition, routine biochemical tests, hepatic ultrasound and ultrasound guided hepatic biopsy samples were obtained at the same time points, and the results compared with hepatobiliary scintigraphy. The normal hepatic extraction fraction was determined to be 85%, and the normal hepatic excretion half time (T 1/2) was 14 minutes. There was no significant change in scintigraphic parameters compared to pre-infection values at any time following infection with the liver fluke. No correlation between scintigraphic parameters and histologic scores was found; however, significant correlation was identified between parasite burden and histologic scores 6 months following infection. Despite the presence of severe multifocal histologic abnormalities, minimal clinical, biochemical and scintigraphic derangements were identified using this model of cholangiohepatitis. Based on this study, hepatobiliary scintigraphy appears to be an insensitive test for structural hepatobiliary abnormalities. The role of hepatobiliary scintigraphy in functional hepatobiliary abnormalities of the feline liver has not been determined.

In situ hybridization for the identification of yeastlike organisms in tissue section.

The identification of yeast and yeastlike organisms in tissue sections can be very difficult. Biopsy tissues may be limited, with only occasional organisms present. In addition, several common species have overlapping histologic features. Deoxyribonucleic acid probes were designed to detect both the 18S and 28S ribosomal ribonucleic acid sequences of five fungal organisms with a high degree of specificity for each fungus. Each of these organisms--Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum, and Sporothrix schenckii--can be manifested histologically as round, yeastlike structures, often within a similar size range. Probes were tested against 98 archived, formalin-fixed, paraffin-embedded tissue specimens, each of which had culture-proved involvement by one of these organisms. Assessment of accuracy was based on the presence of yeastlike organisms in consecutive Grocott's methanemine silver (GMS)-stained tissue sections, and agreement with culture results. The results indicated that GMS had a greater overall sensitivity in detecting fungal organisms (95.9%) compared with in situ hybridization (ISH; 82.7%). ISH with oligonucleotide deoxyribonucleic acid probes, however, was more specific, with all species-specific probes yielding 100% specificity (compared with 96.2-100% specificity based on morphology alone). ISH also had a higher positive predictive value (100% in all cases) compared with GMS (83.3-100%). In addition, four cases with rare organisms present (4.1% of cases tested) were detected by ISH but not by GMS staining. These results show that ISH, directed against ribosomal ribonucleic acid, provides a rapid, accurate technique for the identification of yeastlike organisms in histologic tissue sections. Its primary strength lies in the ability to speciate organisms accurately that are too few or atypical to identify based solely on morphologic features.

Ramichloridium mackenziei brain abscess: report of two cases and review of the literature.

We report two cases of brain abscesses caused by Ramichloridium mackenziei, a neurotropic dematiaceous fungus that seems to be geographically restricted to the Middle East. One of the patients had chronic myelomonocytic leukemia but did not receive any chemotherapeutic agents. The other patient was a normal host. Both cases had a fatal outcome despite aggressive antifungal therapy and surgical intervention. Herein, we review all previously described cases in the literature, and discuss the epidemiology, mycology and histopathology of this life-threatening organism.

Sporotrichosis masquerading as pyoderma gangrenosum: case report and review of 19 cases of sporotrichosis.

We present the case of a 59-year-old woman who had large ulcerations on her right leg that were diagnosed initially as pyoderma gangrenosum and treated with three immunosuppressive agents (cyclosporin, prednisone and azathioprine) for 6 months. Results of a biopsy at 6 months showed numerous cigar-shaped bodies consistent with Sporothrix schenckii; identification was confirmed by tissue culture. A retrospective review was performed for all cases diagnosed as sporotrichosis from tissue culture or biopsy specimens at the Mayo Clinic. Nineteen cases were identified. The present case was the only one in which fungal organisms were visible on histological examination. The present case emphasizes the importance of making a definitive histological diagnosis in unusual ulcer cases or in suspected cases of pyoderma gangrenosum before the initiation of immunosuppressive therapy. The large number of cigar-shaped bodies in the tissue is a rare finding in sporothrix infection and has been reported in only two cases previously.

Thoracic vertebral chordoma in a domestic ferret (Mustela putorius furo).

A castrated adult male 1.0-kg domestic ferret (Mustela putorius furo) was referred for evaluation of a mass of >5 mo duration that was associated with the thoracic spine. The ferret had motor dysfunction and no conscious proprioception or pain perception in either hind limb. Segmental reflexes were present. Survey radiography, myelography, and magnetic resonance imaging showed a mass involving the ninth and 10 thoracic vertebrae and compressing the spinal cord. Decompressive surgery was performed, but clinical signs persisted. A diagnosis of chordoma was made using histopathology and immunohistochemistry. This is the first reported case of a chordoma involving the thoracic vertebrae in a domestic ferret.

Ultrasonographic features of canine gastrointestinal pythiosis.

Pythiosis is a chronic pyogranulomatous infection of the gastrointestinal tract or skin caused by the water borne pathogen Pythium insidiosum. The ultrasonographic features of nine dogs with gastrointestinal pythiosis are reported. The stomach, duodenum, jejunum or colon were affected. All dogs had thickening of the gastrointestinal wall and areas with obliteration of the normal layered appearance. In one dog an eccentric mass was found arising from the serosal surface of the wall of the colon with mild diffuse wall thickening. Regional lymph node enlargement was seen in seven of the nine dogs. One dog had invasion of the pancreas and signs compatible with extrahepatic biliary obstruction. When compared to previous reports of gastrointestinal neoplasia, the features of wall thickening, loss of layering and regional lymphadenopathy are not considered specific for gastrointestinal pythiosis. Histological examination of tissue specimens is required for diagnosis.

The diagnosis and incidence of allergic fungal sinusitis.

OBJECTIVE: To reevaluate the current criteria for diagnosing allergic fungal sinusitis (AFS) and determine the incidence of AFS in patients with chronic rhinosinusitis (CRS). METHODS: This prospective study evaluated the incidence of AFS in 210 consecutive patients with CRS with or without polyposis, of whom 101 were treated surgically. Collecting and culturing fungi from nasal mucus require special handling, and novel methods are described. Surgical specimen handling emphasizes histologic examination to visualize fungi and eosinophils in the mucin. The value of allergy testing in the diagnosis of AFS is examined. RESULTS: Fungal cultures of nasal secretions were positive in 202 (96%) of 210 consecutive CRS patients. Allergic mucin was found in 97 (96%) of 101 consecutive surgical cases of CRS. Allergic fungal sinusitis was diagnosed in 94 (93%) of 101 consecutive surgical cases with CRS, based on histopathologic findings and culture results. Immunoglobulin E-mediated hypersensitivity to fungal allergens was not evident in the majority of AFS patients. CONCLUSION: The data presented indicate that the diagnostic criteria for AFS are present in the majority of patients with CRS with or without polyposis. Since the presence of eosinophils in the allergic mucin, and not a type I hypersensitivity, is likely the common denominator in the pathophysiology of AFS, we propose a change in terminology from AFS to eosinophilic fungal rhinosinusitis.

Recurrent cutaneous melanoma of the head and neck.

INTRODUCTION: Recurrent cutaneous melanoma is generally regarded as having an extremely poor prognosis, particularly when regional lymph nodes are involved. A few reports have documented long-term survival among those patients treated for regionally recurrent melanoma. METHODS: This article reviews patients at our institution undergoing complete neck dissection for recurrent head and neck melanoma. RESULTS: Twenty-six patients with locoregionally recurrent cutaneous melanoma of the head and neck underwent complete neck dissection with or without parotidectomy. Seventeen of these procedures were for clinically evident cervical lymphadenopathy, whereas 9 of the neck dissections were done electively. Fourteen of the 17 patients with clinical adenopathy were confirmed to have cervical lymph node metastases. Two of the 9 patients who underwent elective neck dissections had pathologic lymph nodes. At 5 years, 38% of the patients with isolated neck recurrences not also having concurrent primary site recurrence were alive without disease. CONCLUSIONS: These results provide further evidence suggesting a benefit in the form of long-term survival or cure for patients receiving aggressive surgical treatment for resectable recurrent head and neck melanoma involving cervical lymphatics in the absence of distant metastases.

The dural tail sign in the diagnosis of meningiomas.

In humans the dural tail is a sign seen on contrast enhanced T1 weighted magnetic resonance images. This finding is considered specific for meningioma. The purpose of this study was to determine how often the dural tail occurs in cats and dogs and whether it is a specific sign for meningiomas in these species. MR examinations for eighteen dogs and four cats with proven diagnoses were reviewed. Diagnoses included ten meningiomas (seven dogs and three cats), three gliomas, two pituitary tumors, single examples of two other tumor types and five patients with mass lesions due to inflammatory disease. Contrast enhanced T1 weighted images were evaluated independently by three of the authors for the presence of a dural tail, without knowledge of the diagnoses. The results were compared to the diagnosis for each patient and the performance of individual reviewers compared. When their results were averaged, the reviewers reported the presence of a dural tail in 6 of 10 (60%) meningiomas, although detection varied between observers from 40% to 80%. Each reviewer had one false positive result, two reported a dural tail with a chromophobe adenocarcinoma and one with a toxoplasma meningoencephalitis. When a dural tail is seen an associated mass is most likely a meningioma. It is uncertain whether the dural tail represents neoplastic infiltration beyond the margins of the meningioma. This should be considered when planning treatment.

Correlations between ultrasonographic findings and specific hepatic diseases in cats: 72 cases (1985-1997).

OBJECTIVE: To identify correlations between ultrasonographic findings and specific hepatic diseases in cats. DESIGN: Retrospective study. SAMPLE POPULATION: Medical records of 72 cats with a histopathologic diagnosis of hepatic disease and diagnostic-quality abdominal ultrasonograms between 1985 and 1997. PROCEDURE: Abdominal ultrasonographic findings in 72 cats with histologically confirmed hepatic disease (hepatic lipidosis excluded) were reviewed. Rather than attempt to combine individual ultrasonographic findings with specific hepatic diseases, 2 classification trees were created as models to correlate certain groups of abnormalities with specific hepatic diseases or with malignant and benign lesions of the liver. Sensitivity and specificity of classification trees were calculated. RESULTS: Use of a classification tree resulted in correct classification of malignant versus benign hepatic lesions in 88.9% of cats that had hepatic disease (sensitivity, 90.7%; specificity, 86.1%). Use of a classification tree to distinguish individual types of hepatic diseases resulted in mostly accurate classification of hepatic lymphosarcoma (sensitivity, 70.5%; specificity, 98.2%), cholangitis-cholangiohepatitis syndrome (sensitivity, 87%; specificity, 90%), and benign lesions of the liver (sensitivity, 84.6%; specificity, 86.4%). Criteria that helped most in differentiating among various hepatic diseases were abnormalities within other organs (spleen, lymph nodes) and appearance of the hepatic portal system. A correlation was not found between focal or multifocal appearance of hepatic lesions and specific hepatic diseases. CLINICAL IMPLICATIONS: Use of classification trees to distinguish among specific hepatic diseases or between malignant and benign hepatic lesions provides potentially useful algorithms for ultrasonographic evaluation of cats with hepatic disease.

Histologic parameters predictive of mycobacterial infection.

Tissue specimens from a wide variety of anatomic locations are frequently examined for mycobacteria using a combination of cultures and special stains. Auramine-rhodamine (AR) staining is a sensitive method for detecting acid-fast bacilli (AFB) in tissue sections. We reviewed 85 AR-positive and 275 randomly selected AR-negative biopsy specimens collected during the past 2 years at the Mayo Clinic, Rochester, Minn. Pathologic diagnoses and culture results were also reviewed. Biopsy specimens containing necrotizing granulomas yielded the highest positivity rate for AFB (61 [47.7%]), followed by nonnecrotizing granulomas (14 [17.7%]). Poorly formed granulomas (5 [16.1%]) and acute inflammation (5 [15.6%]) were less frequently positive. Cases with fibrotic or hyalinized granulomas, nonspecific chronic inflammation, nonspecific reactive or reparative changes, no significant histologic abnormality, or malignancy failed to disclose AFB. These specimens, which were consistently negative for AFB, were responsible for 25% of the samples submitted. Of the 360 tissue specimens submitted, 166 had a corresponding mycobacterial culture. Mycobacteria were cultured only from the biopsy specimens that contained necrotizing granulomas (38.2%), nonnecrotizing granulomas (32.4%), poorly formed granulomas (30.0%), or acute inflammation (15.8%). Tissues with fibrotic or hyalinized granulomas, nonspecific chronic inflammation, nonspecific reactive or reparative changes, no significant histologic abnormality, or malignancy failed to yield positive cultures. These data suggest that biopsy specimens with these latter diagnoses are inappropriate specimens for mycobacterial culture or AR staining.

Lag screw stabilization of a cervical vertebral fracture by use of computed tomography in a horse.

A traumatic fracture of C2 was diagnosed radiographically in a 1-year-old German Warm-blood stallion. Fracture configuration was difficult to see on survey radiographs. Computed tomography yielded a more accurate assessment of the fracture and facilitated fracture repair with cortical lag screws. Precise screw placement, to avoid spinal cord damage, was obtained by use of computed tomography. Follow-up radiography revealed normal bone healing, and the horse was in dressage schooling 24 months after surgery.

Allergic fungal sinusitis: the Mayo Clinic experience.

The diagnosis of allergic fungal sinusitis (AFS) is difficult to establish. The clinical presentation is not diagnostic. We define current criteria for diagnosis and the role of total and specific immunoglobulin E (IgE) and immunoglobulin G (IgG) levels in the disease process and review the clinical features of this disease. Fifty-one cases were identified in 44 patients who demonstrated characteristic allergic mucin. Thirty-one of these cases satisfied rigid criteria for the diagnosis of AFS. Twenty of these cases were classified as AFS-like syndrome. The prevalence of strictly defined AFS was 4.0%. Dematiaceous fungi were the predominant agents cultured. All our patients had polyps, 23 (54%) had asthma, 12 (27%) had aspirin sensitivity, 20 (65%) had eosinophilia, and 9 (69%) had increased total IgE levels.

Infections due to nontuberculous mycobacteria in kidney, heart, and liver transplant recipients.

Infections due to nontuberculous mycobacteria (NTM) in solid-organ transplant recipients are infrequent but may be a major cause of morbidity. We describe four cases of NTM infection in solid-organ transplant recipients. The manifestations included a nodule secondary to Mycobacterium kansasii infection in a heart transplant recipient, a cutaneous lesion and a pulmonary nodule secondary to M. kansasii infection in a renal transplant recipient, tenosynovitis secondary to Mycobacterium chelonae infection in a renal transplant recipient, and cutaneous lesions secondary to M. chelonae infection in a liver transplant recipient. We also summarize previously reported cases of NTM infections in solid-organ transplant recipients; common manifestations of NTM infections in solid-organ transplant recipients include cutaneous lesions of the extremities, tenosynovitis, and joint infection. Histopathologic examination of aspirates or biopsy specimens from involved areas and staining and culture for mycobacteria are essential for diagnosis. Treatment of NTM infection most commonly involves surgery, reduction in doses of immunosuppressive medications, and/or therapy with antimycobacterial medications; these treatments are often associated with a good outcome.

Integration of mass spectrometry in analytical biotechnology.

Mass spectrometry (MS) has become an indispensable tool for peptide and protein structure analysis because of three unique capabilities that enable it to be used to solve structural problems not easily handled by conventional techniques. First, MS is able to provide accurate molecular weight information on low-picomole amounts of peptides and proteins independent of covalent modifications that may be present. Second, this information is obtainable for peptides present in complex mixtures such as those that result from a proteolytic digest of a protein. Third, by using tandem MS, partial to complete sequence information may be obtained for peptides containing up to 25 amino acid residues, even if the peptides are present in mixtures. Sensitivity and speed of the MS-based approaches now equal (and in some cases exceed) that of Edman-based sequence analysis. In this perspective we discuss how MS, tandem high-performance MS, and on-line liquid chromatography/MS using fast atom bombardment or electrospray ionization have been integrated with more conventional techniques in order to increase the accuracy and speed of peptide and protein structure characterization. The expanding role of matrix-assisted laser desorption MS in protein analysis is also described. The unique niche that MS occupies for locating and structurally characterizing posttranslational modifications of proteins is emphasized. Examples chosen from the authors' laboratory illustrate how MS is used to sequence blocked proteins, define N- and C-terminal sequence heterogeneity, locate and correct errors in DNA- and cDNA-deduced protein sequences, identify sites of deamidation, isoaspartyl formation, phosphorylation, oxidation, disulfide bond formation, and glycosylation, and define the structural class of carbohydrate at specific attachment sites in glycoproteins.

Human immunodeficiency virus-1 protease. 1. Initial velocity studies and kinetic characterization of reaction intermediates by 18O isotope exchange.

The peptidolytic reaction of HIV-1 protease has been investigated by using four oligopeptide substrates, Ac-Ser-Gln-Asn-Tyr-Pro-Val-Val-NH2, Ac-Arg-Ala-Ser-Gln-Asn-Tyr-Pro-Val-Val-NH2, Ac-Ser-Gln-Ser-Tyr-Pro-Val-Val-NH2, and Ac-Arg-Lys-Ile-Leu-Phe-Leu-Asp-Gly-NH2, that resemble two cleavage sites found within the naturally occurring polyprotein substrates Pr55gag and Pr160gag-pol. The values for the kinetic parameters V/KEt and V/Et were 0.16-7.5 mM-1 s-1 and 0.24-29 s-1, respectively, at pH 6.0, 0.2 M NaCl, and 37 degrees C. By use of a variety of inorganic salts, it was concluded that the peptidolytic reaction is nonspecifically activated by increasing ionic strength. V/K increased in an apparently parabolic fashion with increasing ionic strength, while V was either increased or decreased slightly. From product inhibition studies, the kinetic mechanism of the protease is either random or ordered uni-bi, depending on the substrate studied. The reverse reaction or a partial reverse reaction (as measured by isotope exchange of the carboxylic product into substrate) was negligible for most of the oligopeptide substrates, but the enzyme catalyzed the formation of Ac-Ser-Gln-Asn-Tyr-Phe-Leu-Asp-Gly-NH2 from the products Ac-Ser-Gln-Asn-Tyr and Phe-Leu-Asp-Gly-NH2. The protease-catalyzed exchange of an atom of 18O from H2 18O into the re-formed substrates occurred at a rate which was 0.01-0.12 times that of the forward peptidolytic reaction. The results of these studies are in accord with the formation of a kinetically competent enzyme-bound amide hydrate intermediate, the collapse of which is the rate-limiting chemical step in the reaction pathway.

Nontuberculous mycobacterial infections of the skin. Report of fourteen cases and review of the literature.

This study comprised 14 patients from whose skin nontuberculous mycobacteria were recovered. Most clinical manifestations were relatively nonspecific. Various histopathologic patterns were observed in 22 biopsy specimens. Recurrences were common and prolonged treatment was often necessary. Culture of tissue remains the definitive diagnostic procedure. Cutaneous lesions can be the first or only site of nontuberculous mycobacteriosis.