OBJECTIVE To compare conventional MRI and nonenhanced 3-D time-of-flight (TOF) magnetic resonance angiography (MRA) findings between dogs with meningioma and dogs with intracranial histiocytic sarcoma (IHS).
DESIGN Retrospective case series.
ANIMALS 14 dogs with meningioma and 5 dogs with IHS.
PROCEDURES Medical records of dogs with meningioma or IHS that were examined at a tertiary veterinary hospital from 2010 through 2014 and underwent 3-D TOF MRA in conjunction with conventional MRI were reviewed. Findings for conventional MRI and 3-D TOF MRA were compared between the 2 groups of dogs to evaluate whether there were any characteristics that could be used to differentiate meningioma from IHS.
RESULTS Tumor type was significantly associated with signal intensity on conventional T2-weighted and fluid-attenuated inversion recovery MRI images; most meningiomas were hyperintense, and most IHSs were isointense or hypointense on those images. Tumor type was not associated with signal uniformity, tumor location, tumor origin, or the presence of edema, midline shift, or brain herniation. On MRA, blood vessels adjacent to the tumor were identified and characterized for 9 of 14 dogs with meningioma and all 5 dogs with IHS. Vessels adjacent to meningiomas were displaced in 8 of 9 dogs, whereas vessels adjacent to IHSs were not displaced.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated nonenhanced 3-D TOF MRA findings provided additional information that can be assessed in conjunction with conventional MRI findings to help differentiate meningiomas from IHSs in dogs.
Objective—To investigate age-related and regional differences in estimated metabolite concentrations in the brain of healthy dogs by means of magnetic resonance spectroscopy (MRS).
Animals—15 healthy Beagles.
Procedures—Dogs were grouped according to age as young (n = 5; all dogs were 2 months old), adult (5; mean age, 4.5 years), or geriatric (5; all dogs were 12 years old). Imaging was performed by use of a 1.5-T MRI system with T1- and T2-weighted spin-echo and fluid-attenuated inversion recovery sequences. Signal intensity measurements for N-acetyl aspartate, creatine, choline, and lactate-alanine (the spectroscopic peaks associated with alanine and lactate could not be reliably differentiated) were determined with MRS, and areas under the spectroscopic peaks (representing concentration estimates) were calculated. Ratios of these metabolite values were compared among age groups and among brain regions with regression analysis.
Results—The choline-to-creatine ratio was significantly higher in young dogs, compared with other age groups. The N-acetyl aspartate-to-choline ratio was significantly lower in young dogs and geriatric dogs than in adult dogs. When all age groups were considered, the choline-to-creatine ratio was significantly higher and N-acetyl aspartate-to-choline ratio was significantly lower in the frontal lobe than in all other regions. The N-acetyl aspartate-to-creatine ratio was significantly lower in the cerebellum than in other regions.
Conclusions and Clinical Relevance—Metabolite ratios varied significantly among age groups and brain regions in healthy dogs. Future studies should evaluate absolute concentration differences in a larger number of dogs and assess clinical applications in dogs with neurologic diseases.
Objective—To assess plasma viral RNA concentration
in cats naturally infected with feline immunodeficiency
Animals—28 FIV-infected cats.
Procedure—Cats were categorized into 1 of the 3 following
stages on the basis of clinical signs: asymptomatic
(nonclinical) carrier (AC; n = 11), acquired
immunodeficiency syndrome-related complex (ARC;
9), or acquired immunodeficiency syndrome (AIDS;
8). Concentration of viral RNA in plasma (copies per
ml) was determined by use of a quantitative competitive
polymerase chain reaction (QC-PCR) assay. Total
lymphocyte count, CD4+ cell and CD8+ cell counts,
and the CD4+ cell count-to-CD8+ cell count ratio were
determined by use of flow cytometry.
Results—Plasma viral RNA concentration was significantly
higher in cats in the AIDS stage, compared
with cats in AC and ARC stages. Most (5/7) cats in the
AIDS stage had low total lymphocyte, CD4+ cell, and
CD8+ cell counts.
Conclusions and Clinical Relevance—Concentration
of plasma viral RNA is a good indicator of disease progression
in FIV-infected cats, particularly as cats
progress from the ARC to the AIDS stage.
Determination of CD4+ and CD8+ cell counts can be
used as supportive indicators of disease progression.
(Am J Vet Res 2000;61:1609–1613)
Objective—To evaluate aberrations of the p53 tumor
suppressor gene in naturally developing tumors in
Sample Population—Tumor specimens from 15
dogs with various tumors, including malignant lymphoma
(7 dogs), monocytic leukemia (1), mammary
gland adenoma (1), mammary gland benign mixed
tumor (1), rhabdomyosarcoma (1), colon cancer (1),
and osteosarcoma (3).
Procedure—Aberrations of the p53 gene in these
tumor tissues were examined by reverse transcriptase-
polymerase chain reaction and single-strand conformation
polymorphism analysis, using 3 fragments
that covered the entire open reading frame of the
canine p53 gene, followed by nucleotide sequencing
of the abnormal bands.
Results—Point mutations, deletions, and insertions
resulting in a number of amino acid substitutions of
wild-type p53 were detected in 7 of the 15 tumor
specimens from dogs with malignant lymphoma,
monocytic leukemia, rhabdomyosarcoma, colon cancer,
and osteosarcoma. Of these 7 dogs, 2 had aberrations
of the p53 gene on both alleles, whereas 5
had aberrations of the p53 gene on 1 allele and concurrently
lacked the wild-type p53 transcript. Many of
the aberrations of the p53 gene detected in these
tumors were located in the transactivation, DNA binding,
and oligomerization domains.
Conclusions and Clinical Relevance—Various naturally
developing tumors in dogs often have inactivation
of the p53 tumor suppressor gene, which may be
1 of the multiple step-wise genetic changes during
tumorigenesis. This study indicates that p53 gene can
be a target for gene therapy for tumors in dogs. (Am
J Vet Res 2001;62:433–439)
Objective—To evaluate the mechanism of multidrug
resistance in feline lymphoma cell lines.
Sample Population—A feline lymphoma cell line
(FT-1) and its adriamycin (ADM)-resistant subline
Procedures—The FT-1 cell line was cultivated in the
presence of a gradually increasing concentration of
ADM to generate its ADM-resistant subline
(FT-1/ADM). Susceptibility of cells from the parental
FT-1 cell line and the FT-1/ADM subline to antineoplastic
drugs was determined. From the complementary
DNA (cDNA) template of FT-1/ADM cells, feline
MDR1 cDNA was amplified by use of polymerase
chain reaction (PCR) and sequenced. Reverse transcription
(RT)-PCR and Western blot analyses were
performed to assess expression of the MDR1 gene
and P-glycoprotein (P-gp) in FT-1/ADM cells, compared
with that in FT-1 cells.
Results—A drug sensitivity assay revealed that
FT-1/ADM cells were much more resistant to ADM
and vincristine than the parental FT-1 cells. The feline
MDR1 cDNA amplified by use of PCR was 3,489
base pairs long, corresponding to approximately
90% of the whole open reading frame of human
MDR1 cDNA; its amino acid sequence was 91.5,
87.0, and 79.4% identical to that of human MDR1,
mouse mdr1a, and mdr1b cDNA, respectively. By
RT-PCR analysis, expression of MDR1 messenger
RNA was clearly detected in FT-1/ADM cells but not
in the parental FT-1 cells. Western blot analysis also
revealed the expression of P-gp encoded by the
MDR1 gene in FT-1/ADM cells but not in FT-1 cells.
Conclusions—The basic structure of the feline
MDR1 gene was essentially the same as that of multidrug-
resistance genes of other species. Expression
of P-gp appeared to be one of the mechanisms
responsible for the development of multidrug resistance
in feline lymphoma cell lines in vitro. (Am J Vet