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Biomedical subjects

R R Dubielzig

Publications and source records attributed to R R Dubielzig.

At least 55 records · Page 3Linked to original sources
PubMed1993

The histopathological features of canine keratinizing ameloblastoma.

This paper describes the microscopical features of one variant of canine ameloblastoma. It is composed of islands and strands of odontogenic epithelium that have infiltrated through the surrounding stroma. Most of the basal cells are hyperchromatic, cuboidal and perpendicular to the basement membrane (palisading); in some areas their nuclei are located at the distal ends of the cells (reverse polarization) and their cytoplasm is vacuolated. These are the classical characteristics of the basal cell layer of ameloblastomas. The central cells of these tumours are closely-packed, spindle-shaped and exhibit cellular keratinization and calcification as prominent features. Amyloid is present between the neoplastic epithelial cells in some examples.

Ameloblastoma↗
PubMed1993

Tumorigenicity by human papillomavirus type 16 E6 and E7 in transgenic mice correlates with alterations in epithelial cell growth and differentiation.

The human papillomavirus type 16 (HPV-16) E6 and E7 oncogenes are thought to play a role in the development of most human cervical cancers. These E6 and E7 oncoproteins affect cell growth control at least in part through their association with and inactivation of the cellular tumor suppressor gene products, p53 and Rb. To study the biological activities of the HPV-16 E6 and E7 genes in epithelial cells in vivo, transgenic mice were generated in which expression of E6 and E7 was targeted to the ocular lens. Expression of the transgenes correlated with bilateral microphthalmia and cataracts (100% penetrance) resulting from an efficient impairment of lens fiber cell differentiation and coincident induction of cell proliferation. Lens tumors formed in 40% of adult mice from the mouse lineage with the highest level of E6 and E7 expression. Additionally, when lens cells from neonatal transgenic animals were placed in tissue culture, immortalized cell populations grew out and acquired a tumorigenic phenotype with continuous passage. These observations indicate that genetic changes in addition to the transgenes are likely necessary for tumor formation. These transgenic mice and cell lines provide the basis for further studies into the mechanism of action of E6 and E7 in eliciting the observed pathology and into the genetic alterations required for HPV-16-associated tumor progression.

Animals↗
PubMed1993

Examination of frozen cross sections of cervical spinal intersegments in nine horses with cervical vertebral malformation: lesions associated with spinal cord compression.

Nine horses with clinical and radiographic findings of cervical vertebral malformation that were necropsied and examined using frozen cervical spinal cord cross sections were reviewed. Only cases with actual distortion of the spinal cord due to compression were selected. The goal of the study was to determine the morphologic features responsible for narrowing of the spinal canal and compression of the spinal cord. In individual cases, bony changes are associated with osteochondrosis and osteomyelitis of the dorsal articular facets and osteosclerosis of the dorsal cervical lamina. Soft tissue pathology associated with spinal cord compression included ligamentum flavum hypertrophy, joint capsule swelling and hypertrophy, and synovial cysts. In most cases, a combination of abnormalities was found in horses with spinal cord compression.

Animals↗
PubMed1993

Ischemia/reperfusion injury of the ascending colon in ponies: a correlative study utilizing microvascular histopathology and corrosion casting.

Volvulus of the ascending colon (ACV) in the horse results in microvascular injury and necrosis of the intestinal mucosa. This study investigated the site and type of microvascular injury which occurs within the mucosa and submucosa following ACV. Histopathology of volvulus treated ponies demonstrated mucosal necrosis with microvascular hemorrhage and thrombosis. Thrombi occurred within the subepithelial capillaries and edema and hemorrhage developed throughout the mucosa and submucosa. Vascular casts allowed 3-D viewing of samples obtained from the entire pelvic flexure and demonstrated two distinct microvascular changes: 1) disruption of the colonic glandular capillary network occurred concomitantly with the mucosal injury, and 2) extensive endothelial leakage from the submucosal microvasculature contributes to edema formation. Thus, microcorrosion casting of the equine pelvic flexure provided an effective means to characterize the location and severity of vascular leakage and visualize the extent and severity of injury to the capillary network not easily depicted by histopathology. Microvascular casting in conjunction with routine histopathology provided additional information on the pathomorphologic changes in this model of ischemia/reperfusion injury.

Animals↗
PubMed1993

Cataracts in a laboratory colony of ferrets.

Cataracts were found by use of slit-lamp biomicroscopy in two genetically unrelated ferret populations (A and B). When they were initially examined at the age of 11 to 12 months, 34 of 73 ferrets (46.6%) in population A had lens opacities, which could be categorized into one of three groups. Group-1 ferrets (n = 25) manifested a continuum of lens changes ranging from fine, multifocal, punctate opacification of the superficial posterior lens cortex (n = 3), to changes in both the anterior and posterior cortex (n = 13), to immature (n = 1), or mature/hypermature cataracts (n = 8). Group-2 ferrets (n = 7) had bilateral microphthalmia and cataracts. Group-3 ferrets (n = 2) had minor lens changes involving the nucleus or cortex that were not typical of either group 1 or 2. By the age of 18 months, 41 of the remaining 42 animals in population A had developed fine, multifocal, punctate opacities of the posterior cortex. In group-1 animals, histologic changes in the lens ranged from several 80 x 40-microns, punctate, spheroidal lesions in the posterior cortex, to posterior migration of the lens epithelium, Morganian granules, and a complete mature/hypermature cataract. One group-2 ferret had microphthalmia, filling of the lens capsule with a cell-poor, periodic acid-Schiff stain-positive membranous material, and retinal detachment. Population B consisted of 15 adult and 47 6-month-old juvenile ferrets. Eleven adults had multifocal, fine, punctate, posterior cortical opacities, and one adult had a nuclear cataract.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Idiopathic granulomatous disease with ocular adnexal and cutaneous involvement in a dog.

Idiopathic granulomatous disease was the cause of bilateral eyelid masses and additional ocular adnexal disease in a dog. Histologically similar granulomas developed concurrently in distant sites including the limbs, prepuce, and testicles. Periodic resolution and redevelopment of the masses were observed and were unaffected by corticosteroid treatments. Rapid diminution of some of the masses was found after treatment with polyethylene glycol modified L-asparaginase, but poor client compliance and episodes of spontaneous resolution of some of the masses made it difficult to accurately assess effectiveness of treatment. Clinicians should be aware that ocular adnexal granulomas may simulate neoplasms and be a component of a more widespread disease process.

Animals↗
PubMed1992

Pseudallescheria boydii keratomycosis in a dog.

A dog that had a chronic history of keratoconjunctivitis sicca and was being treated topically with antibiotics and corticosteroids was examined for evaluation of a melting corneal ulcer. Cytologic examination and cultures revealed the pathogen to be Pseudallescheria boydii, a saprophytic fungus. The eye was surgically removed and evaluated histologically. Fungal keratitis is rarely reported in dogs, but needs to be considered in refractory infections or in dogs treated with antibiotics or corticosteroids.

Adrenal Cortex Hormones↗
PubMed1990

Ocular neoplasia in small animals.

Important and rare primary tumors of the globe of dogs and cats are discussed with particular emphasis on biological behavior and morphologic features that predict biological behavior. Classification systems currently thought to be most useful for predicting the behavior of canine and feline ocular melanomas are emphasized. The recently described feline posttraumatic ocular sarcoma is discussed.

Animals↗
PubMed1989

Pseudallescheria boydii keratomycosis in a horse.

The fungal organism Pseudallescheria boydii was isolated from the cornea of a Quarter Horse with ulcerative keratitis. Despite aggressive hourly medication through a subpalpebral lavage system, with drugs including miconazole and natamycin, the cornea developed a stromal abscess. Orbital exenteration was performed after 3 weeks. The fungal isolate was later determined to be resistant to all 8 antifungal drugs tested. Microscopic examination of the cornea revealed fungal hyphae throughout the corneal stroma and penetrating the Descemet membrane. Pseudallescheria boydii has not been implicated previously as a cause of keratomycosis in horses or in other domestic animals, although cases in human beings have been described.

Animals↗
PubMed1989

Experimental Dirofilaria immitis-associated glomerulonephritis induced in part by in situ formation of immune complexes in the glomerular capillary wall.

Eight dogs were immunized with an aqueous-soluble extract of adult Dirofilaria immitis. Subsequent to at least 7-fold increases in antibody titer, the left renal artery of each dog was infused with 6 mg of D. immitis antigen. Fourteen days after infusion, the left kidney was compared to the right kidney and preinfusion biopsies. All dogs developed glomerular lesions in the left kidney characterized by 1 or more of the following: mesangial cell proliferation, neutrophil infiltration, increased periodic acid-Schiff-positive staining of the mesangium and glomerular basement membrane (GBM), fibrin deposition, and thickening of the GBM. Left kidney glomerular immunofluorescence was positive in 7 of the 8 dogs using polyclonal antisera for canine IgG and C3 in a linear or fine granular pattern. Ultrastructural lesions were present in the left kidney of all dogs and consisted of irregular GBM thickening, intramembranous and mesangial electron-dense deposits, and mesangial and endothelial cell proliferation. Antibodies directed against D. immitis antigen were demonstrated in all kidney eluates from the left kidney. The right kidneys of 3 of the dogs developed lesions; however, in comparison to the left kidney, the lesions in the right kidneys were inconsistent, mild, and focal. The histologic findings in the left kidney were similar to those observed in dogs with naturally occurring D. immitis infections. In sham-immunized control dogs, renal arterial infusion of D. immitis antigen did not cause consistent immune complex glomerulonephritis; however, antigen adherence to glomerular capillary walls was observed by immunofluorescent microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Gentamicin-induced nephrotoxicosis in a cow.

Gentamicin-induced nephrotoxicosis developed in a mature Holstein cow without evidence of preexisting renal disease. Factors possibly predisposing to the nephrotoxicosis included coadministration of a nonsteroidal anti-inflammatory drug and severe gram-negative bacterial sepsis. The cow recovered after prolonged hospitalization.

Acute Kidney Injury↗
PubMed1988

Experimental respiratory decompression sickness in sheep.

Respiratory decompression sickness (RDCS, "the chokes") is a potentially lethal consequence of ambient pressure reduction. Lack of a clearly suitable animal model has impeded understanding of this condition. RDCS, unaccompanied by central nervous system signs, occurred in 17 of 18 unanesthetized sheep exposed to compressed air at 230 kPa (2.27 ATA) for 22 h, returned to normal pressure for approximately 40 min, and taken to simulated altitude (0.75 ATA, 570 Torr). Respiratory signs, including tachypnea, sporadic apnea, and labored breathing, were accompanied by precordial Doppler ultrasound evidence of marked venous bubble loading. Pulmonary arterial pressures exceeded 30 Torr in five catheterized sheep that died or became moribund. Hypoxemia (arterial Po2 less than 40 Torr), neutropenia, and thrombocytopenia were observed. Peribronchovascular edema was the most prominent necropsy finding. Chest radiography indicated interstitial edema in most affected sheep. High body weight and catheterization predisposed the sheep to severe RDCS. It appears that this protocol reliably provides a useful animal model for studies of RDCS and obstructive pulmonary hypertension, that the precipitating event is massive pulmonary embolization by bubbles, and that venous bubbles, detected by Doppler ultrasound, can signal impending RDCS.

Altitude↗
PubMed1988

Pulmonary changes in rats following administration of 3-methylindole in cremophore EL.

3-methylindole (3-MI) dissolved in the lipophilic carrier Cremophore EL was administered intraperitoneally to male, twelve-week-old Sprague-Dawley rats. Gross and histopathologic changes in the lungs were studied using light microscopy at three time-periods following administration: 16, 24, and 46 hours. Both 3-MI and Cremophore caused changes in bronchiolar epithelium at 16 hours. By 46 hours, Cremophore-injected rats showed no effects of the carrier; whereas, 3-MI rats showed severe lung changes characterized by airway epithelial and pulmonary vascular endothelial necrosis and sloughing, cellular infiltration by lymphocytes and macrophages, perivascular edema, alveolar edema, and lymph stasis. Grossly, the controls showed no effect of the carrier and none died during the studies. In contrast, 3-MI injected rats quickly became lethargic and displayed tachypnea, anorexia, and progressive respiratory distress. Two of five 3-MI rats in the final group died just prior to 46 hours. All of this group had grossly congested lungs and marked pleural effusion. The lesions and time course showed similarities to those observed in ruminants and mice. We conclude that 3-MI in Cremophore causes an acute progressive pneumonitis in rats and suggest that the rats may be a suitable model for 3-MI-induced and similar toxic lung diseases in domestic animals and people.

Animals↗
PubMed1988

Thermal dosimetry of normal porcine tissue.

The response of normal porcine fat and muscle to graduated doses of hyperthermia provided by an annularly focused acoustic source was measured. Temperatures and exposure times were varied between 43 degrees C (20-90 min), 45 and 47 degrees C (20-60 min), and 49 degrees C (20 min). Response, based on histologic grading of the treated sites 30 days after exposure, was found to correlate well when mapped against several methods of estimating thermal energy deposition. The threshold for damage production was at or near 43 degrees C. For a given temperature, a nearly exponential increase in relative tissue damage as a function of increased exposure time was found. A twofold increase in tissue damage was produced in fat relative to muscle at any given thermal dose.

Adipose Tissue↗