Clinical signs, imaging features, neuropathology, and outcome in cats and dogs with central nervous system cryptococcosis from California.

BACKGROUND: Cryptococcus spp. is a fungal pathogen with a predilection for the central nervous system (CNS). OBJECTIVES: To compare the clinical, advanced imaging, and neuropathologic findings in dogs and cats with CNS cryptococcosis, and to evaluate outcome of treatment in these animals. ANIMALS: Twenty-six cats and 21 dogs with CNS cryptococcosis. METHODS: Medical records were reviewed for clinical findings and results of CNS imaging. Archived cerebrospinal fluid and CNS tissue specimens were reviewed for pathology. Findings in cats were compared with those in dogs and the effects of variables on survival were determined by survival curve analysis. RESULTS: When present, pain was localized to the cervical region in dogs and was generalized or localized to the thoracolumbar spine or pelvic limbs in cats. Magnetic resonance imaging (MRI) findings were variable but correlated with CNS histopathological findings of meningitis, meningitis with gelatinous pseudocyst formation, and granulomatous mass lesions. Peripherally enhancing brain lesions were seen only in cats. Histopathologically, the inflammatory response was milder in cats compared with dogs. Remissions of ≥1 year occurred in 32% of treated animals. Altered mentation was associated with negative outcome. Glucocorticoid use after diagnosis was associated with improved survival in the first 10 days. CONCLUSIONS AND CLINICAL IMPORTANCE: Lesions seen on MRI reflected neuropathological findings and were similar to those reported in human patients. The immune response to infection may differ between cats and dogs, or relate to the infecting cryptococcal species. Long-term (>6 month median survival time) survival may be possible in animals surviving ≥4 days after diagnosis.

Iron pyronine and alcian blue for staining acid mucin in plastic-embedded sections.

Iron pyronine Y and Alcian blue demonstrated sulfated and nonsulfated acid mucin, respectively, in plastic-embedded sections. Safran used in combination with these two dyes stained collagen and some reticulum fibers. Sulfated acid mucin was red, while nonsulfated acid mucin stained blue; collagen appeared yellow to greenish yellow. The iron pyronine Y-Alcian blue-safran staining method, when used as in the present article, produces excellent cellular visualization of sulfated and nonsulfated acid mucin.

Nonspecific esterase activity in plastic-embedded tissues using Meldola Blue.

A method for the demonstration of nonspecific esterase activity in plastic-embedded tissues using Meldola Blue is described. Although Meldola Blue does not function as an electron carrier in this method, it may account for the short incubation time and excellent localization of the reaction product. Use of Meldola Blue is an advancement in the demonstration of enzyme activity in plastic sections.

A metabolic profile of the rat caudate microvasculature: a histochemical study.

Arterioles of the rat caudate nucleus were examined histochemically to determine their metabolic profile. These microvessels appear capable of aerobic and anaerobic metabolism with a potential for nucleic acid and protein synthesis. Little intramural lipid storage occurs and any fatty acids utilized are provided via the blood supply. Likewise, glycogen is not seen in the arteriolar wall and may be rapidly turned over as a substrate for anaerobic metabolism.

A histochemical examination of the metabolic profiles of rat ventral tegmental area and substantia nigra arterioles.

To determine the metabolic profiles of arterioles of the rat ventral tegmental area and zona compacta and zona reticulata of the substantia nigra (SN), the distribution of selected enzymes, or by-products, of key metabolic pathways were examined histologically. Arterioles of all three regions expressed the enzymes required for aerobic and anaerobic metabolism. However, the relative abundance of the enzymes and byproducts suggests a lower metabolic capacity for the SN than the ventral tegmentum, while lipid catabolism in both regions appears non-operative. Moreover, the larger ventral tegmental arterioles possess a greater potential for nucleic acid and protein synthesis. Together, these results suggest the larger ventral tegmental arterioles possess a greater capacity for proliferation and repair.

A rapid histological technique for localizing recording sites in single unit electrophysiological studies in vitro.

Recording sites from single unit electrophysiological studies in vitro can be precisely localized by first marking the recording locus either by depositing Fast Green dye (for micropipette studies) or electrolytic lesioning (for metal electrode studies). The slices are then fixed in paraformaldehyde, placed in sucrose and attached to a coverslip by the surface tension of water. The slices are attached to a base brain in a cryostat so that the sections can be cut at the proper angle. The slices are then stained using a Nissl staining protocol. This procedure provides intact sections from small tissue slices with the recording locus clearly demarcated.

Identification of dopamine-containing cell bodies in the dorsal and median raphe nuclei of the rat brain using tyrosine hydroxylase immunochemistry.

Using immunohistochemical methods with antibodies specific to tyrosine hydroxylase, we examined the distribution of dopaminergic cells in the dorsal and median raphe nucleus of the rat brain. Although dopamine-containing cell bodies were previously thought to be almost exclusively confined to the substantia nigra pars compacta, ventral tegmental area, and tuberoinfundibular system, we found numerous cell bodies which stained for tyrosine hydroxylase in the dorsal and median raphe nuclei.

Effects of chronic methamphetamine on the nigral-striatal dopamine system in rat brain: tyrosine hydroxylase immunochemistry and quantitative light microscopic studies.

Chronic administration of methamphetamine (20 mg/kg, IP, every 12 hours for 10 days) produced a large decrease in tyrosine hydroxylase staining axons and terminal boutons in the caudate nucleus in rats when examined 60 days following the final methamphetamine injection. This effect was quantitated using the Leitz Data Acquisition and Display System (DADS) revealing that there was a 74% decrease in tyrosine hydroxylase positive processes in the caudate nucleus. Furthermore, this treatment also produced a large decrease in the number of tyrosine hydroxylase positive staining neuronal perikarya in the pars compacta of the substantia nigra. This effect was also quantitative using the Leitz-(DADS) system, revealing a decrease of 89% in tyrosine hydroxylase positive material. These data demonstrate that chronic administration of methamphetamine produces a long-term loss of tyrosine hydroxylase enzyme in both the cell bodies of the substantia nigra and the nerve terminals in the caudate nucleus. Whether this effect is due to the degeneration of the neurons or some metabolic effect remains to be determined.

Tyrosine hydroxylase immunochemistry and quantitative light microscopic studies of the mesolimbic dopamine system in rat brain: effects of chronic methamphetamine administration.

Long-term treatment of rats with methamphetamine (20 mg/kg, IP, every 12 hours for 10 days) resulted in a large decrease in tyrosine hydroxylase staining axons and terminal boutons in the nucleus accumbens and frontal cortex, as well as the ventral tegmental area of the midbrain, when examined 60 days following termination of the drug treatment regimen. Quantitative analysis showed a 71 and 78% decrease in tyrosine hydroxylase staining processes in the nucleus accumbens and frontal cortex, respectively, and a 90% decrease in tyrosine hydroxylase positive material in the ventral tegmental area. Thus, tyrosine hydroxylase enzyme in both the cell bodies of the midbrain ventral tegmental area as well as in the nerve terminals in post-synaptic target regions of the forebrain is depleted by chronic methamphetamine administration.

The anatomy of the parotoid gland in Bufonidae with some histochemical findings. II. Bufo alvarius.

The gross and microscopic anatomy of the venom producing parotoid glands of Bufo alvarius has been studied by light and electron microscopy. Histochemical reactions for the presence of venom constituents and of components in biochemical pathways in the synthesis and release of venom were performed. The gland is composed of numerous lobules. Each lobule is an individual unit with a lumen surrounded by a double cell layer. Microvilli of the outer layer interdigitate with microvilli of the inner layer. Cells of the outer layer resemble smooth muscle cells, are rich in adenosine triphosphatase and glucose-6-phosphatase, and contain numerous pinocytotic vesicles, glycogen granules and various organelles. These organelles include "crystalloids" of what seem to be highly organized agranular reticulum. These outer layer cells probably function in some aspects of venom synthesis, active cellular transport and contraction in the discharge of the secretory product. The inner cell layer demonstrates a positive chromaffin reaction, contains steroid material, various organelles, some pinocytotic vesicles and glycogen granules, and appears devoid of a plasmalemma on its inner surface. This layer is probably involved in venom formation and release via an apocrine type of secretion. Bufo alvarius parotid gland shows significant morphological and histochemical differences from that of B. marinus and more nearly resembles a typical steroid producing organ.

Intracellular calcium localization in stimulated and non-stimulated extraorbital lacrimal glands of rats.

Acinar cells of extraorbital lacrimal glands from control, pilocarpine-treated, atropine-treated and atropine + pilocarpine-treated rats were studied using a potassium pyroantimonate technique and X-ray microanalysis for calcium localization at the ultrastructural level. This was done in order to identify intracellular compartmentalization of calcium and to elucidate any calcium translocation that might occur during the secretory process. Calcium-pyroantimonate complexes were identified in the mitochondria, plasma membrane and cytoplasmic vesicles of the untreated specimens and in the plasma membrane of atropine-treated specimens, these complexes decreased drastically in the actively-secreting cells. The function of calcium in lacrimal gland secretion and the action of pilocarpine and atropine on membrane calcium are discussed.

A histochemical study of the metabolism of rat renal arteries and arterioles.

A histochemical study of the metabolism of rat renal arteries and arterioles. Rat renal arteries and arterioles were examined histochemically to determine their metabolic profiles. Succinate, malate and NAD-isocitrate dehydrogenase, cytochrome oxidase and ubiquinone were assessed to determine aerobic metabolism. Glucose-6-phosphate dehydrogenase and DPN diaphorase were evaluated to determine hexose-monophosphate-shunt activity. Anaerobic metabolism was evaluated via lactate dehydrogenase, and the substrate, glycogen. Gomori's lipase, beta-hydroxybutyrate dehydrogenase and amounts of neutral fat and free fatty acids were assessed as indicators of lipid utilization. Myosin ATPase activity was evaluated as an index of ATP utilization for contraction. Deoxyribonucleic and ribonucleic acids were appraised as indicators of protein synthesis. In general, the oxidative enzymes and myosin ATPase demonstrate considerable activity in renal arteries and arterioles which suggests aerobic metabolism and ATP usage. Renal arteries and arterioles also appear capable of anaerobic metabolism as indicated by strong lactate dehydrogenase reactivity and by the presence of slight to moderate quantities of glycogen, while high levels of glucose-6-phosphate dehydrogenase and moderate amounts of deoxyribonucleic acid suggest a potential for beta-hydroxybutyrate dehydrogenase, minimal lipase activity, and the absence of fatty acids with substantial amounts of neutral fat, indicate limited lipid catabolism.

Ultrastructural changes in livers of young and aging rats exposed to methylated benzenes.

ULtrastructural examination was conducted on livers of young rats which were given (intraperitoneal injection) several methylated benzenes (73 mg/kg of body weight) for 3 consecutive days and on livers of aging rats (12 to 19 months old) which were fed methylated benzenes in the diet (200 mg/1,000 g of feed) for periods of 1, 2, 3, and 6 months. The young animals demonstrated white, raised, nodular lesions along the free margins of the liver. The lesions in young animals consisted of lipid droplets surrounded by macrophages and fibroblasts. Some fibroblasts in these lesions appeared to be active in collagen synthesis. Mast cells and eosinophils also occurred in the lesions. Hepatocytes in these young animals appeared morphologically normal. In contrast, hepatocytes in the aging rats developed 2 types of vacuoles. The 1st type of vacuole was bound by a double-unit membrane--the other unit membrane possibly derived from smooth endoplasmic reticulum; it contained a mottled, globular, electron-lucent material. The 2nd type of vacuole was peripherally located in hepatocytes, was single membrane-bound, and occasionally was observed opening into the space of Disse (spatium perisinusoideum). Our observations indicated that acute exposures (3 days) to at least some methylated benzenes does not cause ultrastructurally observable abnormalities in hepatocytes of young rats, but chronic oral ingestion of some can cause formation of vacuolar structures in aging rat hepatocytes.

Evidence for increased protein synthesis in myocardial microvessels after chronic sympathectomy in the dog.

Using histochemical methods, evidence of increased protein synthesis was observed in microvessels (diameter less than 100 micrometers) from dog hearts which had been sympathectomized 2 weeks earlier when compared to controls. Such evidence consisted of increased staining intensity for the enzyme glucose-6-phosphate dehydrogenase and for the nucleic acids RNA and DNA. Increases in reaction intensities were noted in approximately 30% of the microvessels examined from the sympathectomized hearts, and may imply a vascular proliferation in these hearts. However, since no increase in capillary density was observed in sympathectomized hearts, a vascular proliferation, if it occurred, may have been involved in development of the coronary collateral circulation. These data support previous results indicating that collateral resistances are reduced following chronic cardiac sympathectomy while resistance of the coronary vascular bed itself is not altered.

Meldola Blue for the cytochemical demonstration of leukocyte dehydrogenases.

The new electron carrier Meldola Blue was employed in the cytochemical demonstration of succinate, lactate, and glucose-6-phosphate dehydrogenases in leukocytes. A significant increase in dehydrogenase activity, with better localization and less diffusion of the reaction product, was observed when compared to enzyme reactivity carried out without Meldola Blue. Meldola Blue can facilitate the demonstration of both bound and soluble leukocyte dehydrogenases. Current methods which could yield better visualization of leukocyte dehydrogenases, particularly succinate, lactate, and glucose-6-phosphate dehydrogenases in neutrophils, suggest excellent use can be made of Meldola Blue in the clinical laboratory. Reliable histochemical determination of these enzymes can aid in differentiating younger from older neutrophils. In addition, glucose-6-phosphate dehydrogenase might be used in conjunction with the nitroblue tetrazolium (NBT) test in separating persons with bacterial infections from those with nonbacterial illness. Furthermore, histochemical visualization of this enzyme may also prove beneficial in identifying glucose-6-phosphate dehydrogenase-deficient individuals.