Microvasculature of the feline stomach

The feline gastric microvasculature was studied by corrosion of the injected vascular bed, which allowed evaluation of the vascular pattern of the different tunics. The serosal pattern consisted of numerous interconnected capillary vessels, forming a delicate network. Submucosal arteries supplied the muscular tunic through numerous anastomosing vessels that followed the direction of the smooth muscle fibers. The entire mucosal tunic was supplied by arterioles derived from the submucosal plexus; these gave rise to capillaries that surrounded the gastric glands and terminated in a diffuse, anastomosing subepithelial capillary network. Venules coursed through the mucosa in a perpendicular manner, forming submucosal veins.     

Recombinant feline leukemia virus genes detected in naturally occurring feline lymphosarcomas.

Using a polymerase chain reaction strategy aimed at detecting recombinant feline leukemia virus (FeLV) genomes with 5' env sequences originating from an endogenous source and 3' env sequences resulting from FeLV subgroup A (FeLV-A), we detected recombinant proviruses in approximately three-fourths of naturally occurring thymic and alimentary feline lymphosarcomas (LSAs) and one-third of the multicentric LSAs from cats determined to be FeLV capsid antigen positive by immunofluorescence assay. In contrast, only 1 of 22 naturally arising FeLV-negative feline LSAs contained recombinant proviruses, and no recombinant env gene was detected in seven samples from normal tissues or tissues from FeLV-positive animals that died from other diseases. Four preferred structural motifs were identified in the recombinants; one is FeLV-B like (recognizing that FeLV-B itself is a product of recombination between FeLV-A and endogenous env genes), and three contain variable amounts of endogenous-like env gene before crossing over to FeLV-A-related sequences: (i) a combination of full-length and deleted env genes with recombination at sites in the middle of the surface glycoprotein (SU), (ii) the entire SU encoded by endogenous-like sequences, and (iii) the entire SU and approximately half of the transmembrane protein encoded by endogenous-like sequences. Additionally, three of the thymic tumors contained recombinant proviruses with mutations in the vicinity of the major neutralizing determinant for the SU protein. These molecular genetic analyses of the LSA DNAs correspond to our previous results in vitro and support the occurrence and association of viral recombinants and mutants in vivo in FeLV-induced leukemogenesis.     

Recombinant feline herpesviruses expressing feline leukemia virus envelope and gag proteins.

We constructed recombinant feline herpesviruses (FHVs) expressing the envelope (env) and gag genes of feline leukemia virus (FeLV). Expression cassettes, utilizing the human cytomegalovirus immediate-early promoter, were inserted within the thymidine kinase gene of FHV. The FeLV env glycoprotein expressed by recombinant FHV was processed and transported to the cell surface much as in FeLV infection, with the exception that proteolytic processing to yield the mature gp70 and p15E proteins was less efficient in the context of herpesvirus infection. Glycosylation of the env protein was not affected; modification continued in the absence of efficient proteolytic processing to generate terminally glycosylated gp85 and gp70 proteins. A recombinant FHV containing the FeLV gag and protease genes expressed both gag and gag-protease precursor proteins. Functional protease was produced which mediated the proteolytic maturation of the FeLV gag proteins as in authentic FeLV infection. Use of these recombinant FHVs as live-virus vaccines may provide insight as to the role of specific retroviral proteins in protective immunity. The current use of conventional attenuated FHV vaccines speaks to the wider potential of recombinant FHVs for vaccination in cats.     

Prevalence of feline immunodeficiency virus and feline leukemia virus infections in random-source cats.

Retroviral serologic profiles were generated for 506 random-source cats (Felis catus) that were received by our facility during a twenty-month period. Feline leukemia virus antigens were detected in plasma samples from 26 (5.1%) of the cats. Antibodies to feline immunodeficiency virus were present in 24 (4.7%) of the samples tested. A single cat (0.2%) was positive for both viruses. Neither gender nor vendor correlation with retroviral seropositivity could be demonstrated.     

Low temperature compartment formation in feline immunodeficiency virus-infected and uninfected feline kidney cells

Summary This study was to determine if feline immunodeficiency virus (FIV)-infected and uninfected Crandall feline kidney (CRFK) cells exhibited a low temperature (16°C) block in membrane trafficking between transitional endoplasmic reticulum and Golgi apparatus represented by intermediate compartment formation. Cells were cultured at different temperatures and membrane changes involving the Golgi apparatus and Golgi apparatus-associated membrane structures were monitored by electron microscopy and quantitated. With 30 min of incubation, membranes of the Golgi apparatus stack increased in amount at temperatures of 16°C and below compared to temperatures above 18°C. The increase was greatest along the major polarity axis as evidenced by an increased stack height. Neither the number of cisternae per stack nor the average stack diameter (width) was affected by temperature. The response was maximal between 15 and 30 min of low temperature treatment of the cells. Results with cells infected and uninfected with feline immunodeficiency virus were similar. The increase in stack height was due primarily to an increase of membranes at the cis face (cis Golgi apparatus network). At 18°C, membranes of the trans Golgi apparatus network accumulated suggesting that import from the cis Golgi network could proceed at this temperature, whereas exit from the trans Golgi network was still at least partially blocked. Also increased at 16°C and below were numbers of transition vesicles in the space between the Golgi apparatus and the transitional endoplasmic reticulum associated with the cis Golgi apparatus face. The results suggested interruption of the orderly flux of membranes into the Golgi apparatus at 16°C and below. Moreover, the block appeared to be reversible. Upon transfer from 16°C to 37°C, there was a time-dependent decrease in the accumulations of cis compartment membrane accompanied by a corresponding equivalent increase in the membranes of the trans Golgi apparatus compartment.     

Morphometry of feline neutrophil granule genesis

During neutrophil granule genesis, the formation of primary granules is generally thought to be limited to the promyelocyte stage; whereas synthesis of secondary granules is thought to occur only at the myelocyte stage. This hypothesis was tested morphometrically in feline neutrophils that are known to contain both granule types. Marrow specimens obtained from six cats were stained with peroxidase for identification of neutrophil primary granules and counterstained with periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) for identification of secondary granules. By regression analysis using arithmetic models, numbers of cytoplasmic granules in 311 cells were correlated with the degree of nuclear chromatin condensation, which was shown to be an adequate parameter for cell maturation. Promyelocytes and myelocytes had similar mean numbers of peroxidase-positive granules per unit area. A significant increase (p less than or equal to 0.0001) in the numbers of peroxidase-positive granules was noted between the metamyelocyte and the mature neutrophil stage, despite the lack of peroxidase activity in endoplasmic reticulum and Golgi lamellae. By contrast, a significant increase of peroxidase-negative granules between the metamyelocyte and the mature neutrophil stage was not clearly established with these methods. The increase in peroxidase-positive granules may indicate continued production of peroxidase-containing granules and/or redistribution of peroxidase among lysosomal organelles in late feline neutrophils.     

Resuscitation of canine and feline neonates

Fetal depression following dystocia and Cesarean section has two primary causes; the first (and often most important) cause is hypoxia, and the second is depression from anesthetic agents given to the dam. Resuscitation efforts should be provided in the following order: warmth, airway, breathing, circulation, and drugs. Adequate time should be allowed for correction of hypoxia using ventilatory and circulatory support before drugs are used, with the exception of drugs given to reverse anesthetic and analgesic agents that were given to the dam prior to delivery of the neonates.     

Cortical microvasculature of the feline kidney

Scanning electron microscopy of corrosion casts was used to study the ultrastructural morphology of the microcirculation in the feline kidney. The technique used enabled us to examine the renal microvasculature by obtaining stable and consistent replicas of the vasculature. Corrosion casts were evaluated at three different levels, namely subcapsular, midcortical and the corticomedullary junction. The interlobular arteries, given off by the arcuate arteries, coursed through the cortex in a radial fashion and afferent arterioles were given off at varying intervals. Large afferent arterioles formed the glomerular capillary lobules which consisted of very tortuous capillaries. Smaller-diameter efferent arterioles were formed at the vascular pole and ran in the opposite direction to the afferent arteriole. The peritubular plexuses were seen as interconnecting capillaries at both the subcapsular, midcortical and corticomedullary junction. Numerous efferent arterioles, derived from the corticomedullary glomeruli, were seen as large, radiating vessels running towards the renal papilla.     

Characterization of the feline c-abl proto-oncogene

Analysis of total feline DNA by genomic blot hybridization, using the viral oncogene of Abelson murine leukemia virus as a specific probe, has led to the identification of multiple v-abl homologous genetic sequences in the cat genome. Upon restriction endonuclease BamHI digestion, the combined size of the v-abl homologous DNA fragments was about 31 kbp. To characterize these sequences further, four independent v-abl homologous cosmid clones with overlapping cellular inserts have been isolated from a gene library of cat lung genomic DNA. These inserts represent a contiguous region of cellular DNA sequences of 56 kbp in length. Within this region of the feline genome, the v-abl homologous sequences are discontinuously dispersed over a region of about 34 kbp. They represent the complete feline v-abl cellular homolog and are colinear with the viral v-abl oncogene. Nine regions of highly repetitive DNA sequences have been mapped in close proximity to v-abl homologous sequences. These results establish the presence of only a single c-abl proto-oncogene in the cat genome and present its genetic organization.     

Three-dimensional model of the feline hindlimb

This article describes a three-dimensional musculoskeletal model of the feline hindlimb based on digitized musculoskeletal anatomy. The model consists of seven degrees of freedom: three at the hip and two each at the knee and ankle. Lines of action and via points for 32 major muscles of the limb are described. Interspecimen variability of muscle paths was surprisingly low; most via points displayed a scatter of only a few millimeters. Joint axes identified by mechanical techniques as noncoincident and nonorthogonal were further honed to yield moment arms consistent with previous reports. Interspecimen variability in joint axes was greater than that of muscle paths and highlights the importance of joint axes in kinematic models. The contribution of specific muscles to the direction of endpoint force generation is discussed.     

Microvasculature of the feline renal medulla

The microvascular pattern of the feline renal medulla was studied by scanning electron microscopy using corrosion casts. At the corticomedullary junction, numerous efferent arterioles were observed giving rise to peritubular capillary plexuses and arteriole rectae. Considerable differences in vessel diameters were seen. Arteriolae rectae coursed around interlobar veins before returning to the corticomedullary area, as venulae rectae. Diffuse capillary papillary plexuses were seen protruding into the renal pelvis.     

Immunogenic proteins of feline rhinotracheitis virus

Feline rhinotracheitis virus is an upper-respiratory-tract pathogen of cats. It may also cause generalized infections or abortions. Antigens present in [35S]methionine- or [14C]glucosamine-labeled purified virions, in Nonident P-40 (NP-40) extracts of a mixture of virions and infected cells, and in virion-free cell culture medium, along with mock-infected Crandell -Rees feline kidney cell controls, were analyzed by direct sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) or by SDS-PAGE preceded by Staphylococcus aureus protein A immunoprecipitation. The direct SDS-PAGE analysis revealed at least 17 virus-specific peptides with molecular weights ranging from less than 200,000 ( 200K ) to more than 30K . Three of these peptides were glycosylated and had molecular weights of 105K , 68K , and 60K. Immunoprecipitates of purified virions and NP-40 extracts contained three major glycoproteins with the same estimated molecular weights as those found by the direct analysis. A prominent 105K glycoprotein was present in virion-free cell culture medium immunoprecipitates. In addition, a number of nonglycosylated feline rhinotracheitis virus-specific polypeptides (eight in virions, three in NP-40 extracts, and nine in virion-free cell culture medium), ranging in molecular weight from 145K to 32K, were present in the various immunoprecipitates.     

Lectin histochemistry of feline sphingomyelinosis.

The brain from a Siamese cat with sphingomyelinosis was examined with lectin histochemistry. Swollen neurons were stained with Canavalia ensiformis agglutinin (Con A). Some of them were also stained with Ricinus communis agglutinin-I (RCA-I) and Ulex europaeus agglutinin-I (UEA-I). A small number of axonal spheroids and glia cells were positive for Con A, RCA-I, UEA-I and wheat germ agglutinin. Control tissues were weakly stained with Con A, but not with any of the other lectins. These results indicate that affected neurons contain mannose and glucose residues in addition to sphingomyelin. This study points to the possibility that the characteristics of lectin histochemical study might be helpful for the diagnosis of sphingomyelinosis.