Neuronal-visceral GM1 gangliosidosis in a dog with beta-galactosidase deficiency.

A 9-month-old dog with a history of progressive motor dysfunction was shown to have a deficiency in brain beta-galactosidase activity. The canine disease, like that of children with GM1 gangliosidosis, is characterized by accumulation of GM1 ganglioside in the brain, liver, and spleen, and membranous cytoplasmic bodies in neurons. The dog's pedigree suggests an autosomal recessive pattern of inheritance.

Caliber spectra of fibers in the fasciculus gracilis of the cat cervical spinal cord: a quantitative electron microscopic study.

In order to obtain a better understanding of the microscopic structure of the cat fasciculus gracilis, entire cross-sections of the fasciculus were examined with the electron microscope. Twenty-five thousand, two hundred and eighty-four fibers were encountered in one fasciculus. The fiber caliber spectra obtained from the study show that the fasciculus gracilis at cervical level has a unique fiber distribution pattern. The fiber diameters range from less than 1 mu to 15 mu, however, 97 percent of fibers have diameters less than 8 mu; and the majority of the fibers are in the 2-5 mu range.

Morphological characteristics of dendrite bundles in the lumbar spinal cord of the rat.

The finding of motoneuron dendrites organized into small compact bundles in cats, monkeys and pigs suggested that a study of this phenomenon in rats should be undertaken. An analysis was performed with electron microscopy, light microscopy and Golgi methods. An extensive dendrite bundle organization was found in the sixth lumbar segment of the spinal cord. Two discrete bundles were localized bilaterally: a lateral bundle in the ventrolateral gray substance, and a medial bundle in the ventral funiculus. The lateral bundle was found to consist of longitudinally oriented dendrites, neurocytons, glial cells and capillaries. As many as 1678 closely packed dendrites were observed in the lateral bundle. The medial bundle contained dendrites directed across the midline and also longitudinally oriented dendrites. Neurocytons in the medial dendrite bundle were found singly or in clusters, and many radiating bundles of dendrites were observed projecting toward the lateral bundle. Golgi analysis confirmed that neurons in the lateral bundle had most of their dendrites oriented longitudinally. It was possible to trace several dendrites into the lateral bundle from dorsally and medially lying neurons. Electron microscopy substantiated the fact that the bundles were composed of dendrites. It also revealed numerous dendrodendritic and dendrosomatic contacts which were desmosomal in type as well as an abundance of small unidentified processes. Various functions which have been attributed to the dendrite bundles are discussed.

Dermal extracellular lipid in birds.

A light and electron microscopic study of the skin of domestic chickens, seagulls, and antarctic penguins revealed abundant extracellular dermal lipid and intracellular epidermal lipid. Dermal lipid appeared ultrastructurally as extracellular droplets varying from less than 1 micron to more than 25 microns in diameter. The droplets were often irregularly contoured, sometimes round, and of relatively low electron density. Processes of fibrocytes were often seen in contact with extracellular lipid droplets. Sometimes a portion of such a droplet was missing, and this missing part appeared to have been "digested away" by the cell process. In places where cells or cell processes are in contact with fact droplets, there are sometimes extracellular membranous whorls or fragments which have been associated with the presence of fatty acids. Occasionally (in the comb) free fat particles were seen in intimate contact with extravasated erythrocytes. Fat droplets were seen in the lumen of small dermal blood and lymph vessels. We suggest that the dermal extracellular lipid originates in the adipocyte layer and following hydrolysis the free fatty acids diffuse into the epidermis. Here they become the raw material for forming the abundant neutral lipid contained in many of the epidermal cells of both birds and dolphins. The heretofore unreported presence and apparently normal utilization of abundant extracellular lipid in birds, as well as the presence of relatively large droplets of neutral lipid in dermal vessels, pose questions which require a thorough reappraisal of present concepts of the ways in which fat is distributed and utilized in the body.

Pathology of 6-aminonicotinamide toxicosis in the rabbit.

Daily doses of 6-aminonicotinamide (3-5 mg/kg) given by ip injection produced ataxia of the hind limbs progressing to an ascending paresis/paralysis, anorexia, diarrhoea and death in male and female New Zealand White and Dutch Belted rabbits. At autopsy, caecal and gastric distention were seen and the apex of the gall bladder had necrotic foci. Light microscopic lesions included atrophy and necrosis of the white lobe of Harder's gland and atrophy of seminiferous tubules with cellular necrosis, vacuolation and the presence of multinucleated giant cells. Cytoplasmic vacuolation was observed in epithelial cells from many tissues, usually in the basal portion of the cells. Vacuolation of the epithelium of the sacculus rotundus and vermiform appendix was found within the same time frame as histiocytic hyperplasia in these organs. Spongiosis and gliosis were seen in certain parts of the central nervous system. Ultrastructural alterations in the gall bladder epithelium consisted of distention of intercellular space, mild distention of perinuclear space and coalescing, intracytoplasmic, membrane-bound vacuoles, a few of which contained membranous debris. Some alterations of 6-aminonicotinamide toxicosis were prevented by simultaneous administration of nicotinamide with 6-aminonicotinamide.

Polyvinyl alcohol toxicosis as a model of glomerulonephritis in Beagle dogs.

Investigation of pharmacokinetics of certain drugs in experimental models of glomerulonephritis would facilitate development of dose schedules for dogs with this disease. Polymerized polyvinyl alcohol (PVA)-induced glomerulonephritis was investigated in healthy, 15-week-old purebred Beagle dogs. Three dogs were injected daily with 20 ml of 5% (w/v) PVA (125,000 molecular weight, 88% hydrolyzed) in phosphate-buffered saline solution. One control was given only phosphate-buffered saline solution. Determinations were made of complete blood count, PCV, serum urea nitrogen, specific gravity, urine pH, and protein. Tissue specimens were taken for light microscopic and electron microscopic examinations. Injections were stopped after 3 weeks due to severe CNS depression and anemia in the principals. Proteinuria appeared shortly before dogs were euthanatized, but there were no other signs of renal disease. The dominant lesions were foam cell formation in glomeruli and diffuse vacuolation of splenic red pulp cells. Lesions were also visible in electron microscopic sections of glomeruli. Abnormalities were not observed in the control dog. Due to the severity of the nonrenal lesions, PVA (the type used here) is not useful for creating a model of renal disease in dogs.

Ultrastructure of timed isolates of in vitro canine articular chondrocytes.

Articular chondrocytes were enzymatically isolated from the distal end of the adult canine femur. The digestion procedure was conducted for 2- or 6-hour intervals, using 0.25% trypsin and 0.25% collagenase. Cells grown from the 2-hour digestion procedure were polygonal to stellate, had large vesicular nuclei with prominent nucleoli, and exhibited contact inhibition at confluency. Cells grown in cultures from the 6-hour digestion procedure were fusiform, had prominent nuclei with numerous nucleoli, and lacked contact inhibition. Cell cultures established, using cells from both procedures, were examined using the transmission electron microscope. Ultrastructurally, an extensive granular endoplasmic reticulum, prominent golgi complexes, and numerous autophagic vacuoles characterized the 2-hour cell population. The fine structures of the cells grown from the 6-hour process were characterized by numerous cytoplasmic microfilaments randomly dispersed and marginated beneath the plasmalemma of the cells. An extensive dilated rough-endoplasmic reticular system was present. The chondrocytes described in the present study provided morphologic evidence of a heterogeneous cell population in adult canine articular cartilage.

Single intravenous and multiple intramuscular dose pharmacokinetics and tissue residue profile of gentamicin in sheep.

Single and multiple dose gentamicin regimens were compared in sheep to determine the relevant pharmacokinetic differences. Seven mature sheep were given 10 mg/kg of gentamicin by IV bolus. Serum concentrations were monitored for 19 days. Four weeks after the initial bolus, gentamicin was administered IM (3 mg/kg every 8 hours) for 7 days. Ewes were euthanatized and necropsied at 1, 8, and 15 days after termination of the IM regimen and the tissues were assayed for gentamicin. Serum concentrations were analyzed using a triexponential equation. The IV kinetic studies revealed an alpha half-life (t1/2) of 0.31 +/- 0.14 hours, beta t1/2 of 2.4 +/- 0.5 hours, and gamma t1/2 of 30.4 +/- 18.9 hours. Multiple IM dose kinetic studies revealed a beta t1/2 of 2.8 +/- 0.6 hours and gamma t1/2 of 82.1 +/- 17.8 hours. After multiple dosing, gamma t1/2 was significantly longer than after the single IV bolus (P less than 0.05). Twenty-four hour urine collection accounted for 75% to 80% of the total IV dose. Renal cortical gentamicin concentration reached 224 micrograms/g of tissue and then decreased, with a 90-hour t1/2. Renal medullary gentamicin concentration reached 18 micrograms/g with a 42-day t1/2. After multiple dosing, liver gentamicin concentration reached 11 micrograms/g and skeletal muscle concentrations were less than or equal to 0.6 micrograms/g. Route or duration of administration significantly affected the gamma-phase serum concentrations, which may influence gentamicin nephrotoxicosis. The present study also illustrated the complexities in predicting aminoglycoside withdrawal times for food-producing animals before slaughter.

Tamm-Horsfall glycoprotein binds IgG with high affinity.

Tamm-Horsfall protein (THP), a monomeric glycoprotein (M(r) 80 to 100 kDa), is produced by the mammalian kidney's thick ascending limb of Henle cells and excreted into the urine. The function of THP is uncertain. Here we report that a high molecular weight contaminant in sheep THP (sTHP) preparations was identified as sheep IgG by its positive reaction with donkey anti-sheep IgG antibody and with protein G. To answer the question of whether sTHP and sheep IgG co-purified because of a physical interaction between the two proteins, an enzyme-linked immunosorbent assay (ELISA) using immobilized sTHP and soluble sheep IgG was performed. Analysis of the ELISA data identified the presence of two sets of binding sites: a high affinity site (Kd 10(-8) to 10(-9) M) and a lower affinity site (Kd 10(-6) to 10(-7) M) [corrected]. The ELISA detected a similar high affinity interaction between human THP (hTHP) and human IgG. The binding of sheep IgG to immobilized sTHP was inhibited by soluble sTHP. These observations suggest an additional factor to be considered in studies addressing THP's potential immunoregulatory function.

Cation-induced aggregation of cat Tamm-Horsfall glycoprotein and its possible role in feline urolithiasis.

The in vitro cation-induced aggregation properties of cat Tamm-Horsfall protein (cTHP), a urinary glycoprotein, were examined and related to the potential role of cTHP in feline urolithiasis. The aggregation assay involved adding either CaCl2, MgCl2, or NaCl to solutions containing purified cTHP, and then separating the aggregated cTHP by centrifugation. The concentration of cTHP remaining in the supernatant was quantified using a previously developed enzyme-linked immunosorbent assay (ELISA). The effect that buffer pH, cTHP concentration, and urea concentration had on cTHP aggregation also were examined. Of the three salts, CaCl2 consistently was most efficient at precipitating cTHP, while MgCl2 was slightly less efficient. At least ten times more NaCl than CaCl2 or MgCl2 was required for comparable cTHP aggregation. As the pH decreased, increasing concentrations of the salts were required to aggregate cTHP. Increased amounts of CaCl2 and MgCl2 also were required to aggregate cTHP when the urea concentration was increased. As cTHP concentration increased within the physiological range, lower concentrations of CaCl2 and MgCl2 were required to precipitate 50% of the cTHP. Several aspects of the in vitro aggregation properties of cTHP correlate closely with previously identified risk factors for feline urolithiasis, strengthening the theory that cTHP aggregation may be important in this disease.

The fine structure of lipofuscin in the mouse hippocampus.

Lipofuscin was ultrastructurally evaluated in the hippocampus of C57B1/6 male mice at 8, 14, 20 and 24 months of age. The mice were anesthetized, perfused intracardially with 3% glutaraldhyde, and routinely processed for transmission electron microscopic evaluation. Lipofuscin was found in the hippocampus of mice of all age groups. Granules were small and randomly dispersed in the younger animals with clustered complexes being present in the older ones. Lipofuscin was present in neurons, neuroglia, and endothelial cells. Pigment granules in the older mice were observed adjacent to capillaries, were found in vacuolating cytoplasmic structures of pericytes but were not associated with microtubules. This morphological evidence supports the normal removal of lipofuscin from the central nervous system by phagocytosis and enzymatic digestion.

Ochratoxin A and citrinin induced nephrosis in Beagle dogs. III. Terminal renal ultrastructural alterations.

The extent and type of renal ultrastructural changes in Beagle dogs varied with the administration of ochratoxin A and citrinin alone and in the two dosage combinations. The three predominant changes were cytoplasmic vacuolation, myelin figure formation and lesions designated as cytoplasmic disarray. These changes were mainly of the endomembane system of the tubular epithelial cells. Cytoplasmic vacuoles were within proximal and distal tubules and collecting ducts and were most numerous in dogs given 10 mg/kg critrinin. Vacuolation of similar distribution, but less severe, was seen in renal tubular cells of dogs given the higher dose of the combined mycotoxins (0.2 mg/kg ochratoxin A + 10 mg/kg citrinin). This damage was limited to the proximal tubular cells in dogs given only ochratoxin A (0.1 or 0.2 mg/kg). Myelin figures were in proximal epithelial cells of dogs given ochratoxin A alone or combined with citrinin. There was cytoplasmic disarray in dogs of all groups except for dogs given 5 mg/kg citrinin. This lesions was usually limited to the proximal tubules. The lesions, however, was found in cells of the distal tubules of dogs given 10 mg/kg citrinin alone.

Alterations in the hippocampus of aged mice.

The hippocampus of C57B1/6 mice was examined histologically and electron microscopically. Male and female mice at 3 and 8 months of age and female mice at 16 months of age were studied. PAS positive foci, containing particles 1-2 mu in diameter, were observed in the hippocampal region of 8 and 16 month old mice. These particles were diastase sensitive. Electron microscopically, in similar mice, a vacuolating change was observed in the cytoplasm of perithelial cells (pericytes) in the same area.

Citrinin mycotoxicosis in the rabbit: ultrastructural alterations.

Citrinin was given to rabbits as a single oral dose of 120 or 67 mg/kg. Rabbits were killed at 4, 6, 8, 10, and 12 hours post dosing, and the kidneys were fixed by intravascular perfusion. Ultrastructural alterations were evident by 4 hours after treatment. In the proximal tubule, alterations were brush border disruption, cytoplasmic rarefaction, and swelling of interdigitating processes. At higher doses, mitochondria were condensed and distorted. Medullary and straight cortical distal tubules had marked distention of the intercellular spaces and disorganization of interdigitating processes. Changes in cortical and outer medullary collecting ducts were similar but less severe. Renal alterations were suggestive of damage to membrane structure and/or transport functions and interference with cellular bioenergetics. Leukocytic infiltration was associated with damaged tubules indicating a contribution of inflammation to the development of the lesions.

Urinary Tamm-Horsfall glycoprotein concentrations in normal and urolithiasis-affected male cats determined by an ELISA.

A precise and reproducible enzyme-linked immunosorbent assay (ELISA) which measures urinary cat Tamm-Horsfall glycoprotein (cTHP) was developed in order to investigate the possible role of cTHP in the pathogenesis of feline urolithiasis. Reproducible quantification required that the cTHP be disaggregated with 2M urea and 0.05% Tween 20. It was necessary to standardize rigidly the handling of the samples prior to analysis, since the apparent cTHP concentration varied depending on the preanalysis protocols. Using the sample handling protocol of freezing urine at -70 degrees C before dialysis, urinary cTHP was quantified in male cats with no history of urolithiasis ("normal" cats) and in male cats with a history of urolith formation ("urolithiasis" cats). The mean cTHP concentration in adult, male "normal" cats of 49.2 +/- 35.5 micrograms/ml (N = 23) was significantly lower than the mean cTHP concentration of 95.4 +/- 34.1 micrograms/ml (N = 9) in "urolithiasis" cats (p < 0.01, Students' T-test). These findings indicate a correlation between urolithiasis and high urine cTHP concentrations in male cats which warrants further investigation.