Dynamics of {beta}-amyloid reductions in brain, cerebrospinal fluid, and plasma of {beta}-amyloid precursor protein transgenic mice treated with a {gamma}-secretase inhibitor

gamma-Secretase inhibitors are one promising approach to the development of a therapeutic for Alzheimer's disease (AD). gamma-Secretase inhibitors reduce brain beta-amyloid peptide (Abeta), which is believed to be a major contributor in the etiology of AD. Transgenic mice overexpressing the human beta-amyloid precursor protein (APP) are valuable models to examine the dynamics of Abeta changes with gamma-secretase inhibitors in plaque-free and plaque-bearing animals. BMS-299897 2-[(1R)-1-[[(4-chlorophenyl)sulfony](2,5-difluorophenyl)amino]ethyl]-5-fluorobenzenepropanoic acid, a gamma-secretase inhibitor, showed dose- and time dependent reductions of Abeta in brain, cerebrospinal fluid (CSF), and plasma in young transgenic mice, with a significant correlation between brain and CSF Abeta levels. Because CSF and brain interstitial fluid are distinct compartments in composition and location, this correlation could not be assumed. In contrast, aged transgenic mice with large accumulations of Abeta in plaques showed reductions in CSF Abeta in the absence of measurable changes in plaque Abeta in the brain after up to 2 weeks of treatment. Hence, CSF Abeta levels were a valuable measure of gamma-secretase activity in the central nervous system in either the presence or absence of plaques. Transgenic mice were also used to examine potential side effects due to Notch inhibition. BMS-299897 was 15-fold more effective at preventing the cleavage of APP than of Notch in vitro. No changes in the maturation of CD8(+) thymocytes or of intestinal goblet cells were observed in mice treated with BMS-299897, showing that it is possible for gamma-secretase inhibitors to reduce brain Abeta without causing Notch-mediated toxicity.

Regulation of inflammatory responses by oncostatin M

Oncostatin M (OM) is a pleiotropic cytokine produced late in the activation cycle of T cells and macrophages. In vitro it shares properties with related proteins of the IL-6 family of cytokines; however, its in vivo properties and physiological function are as yet ill defined. We show that administration of OM inhibited bacterial LPS-induced production of TNF-alpha and lethality in a dose-dependent manner. Consistent with these findings, OM potently suppressed inflammation and tissue destruction in murine models of rheumatoid arthritis and multiple sclerosis. T cell function and Ab production were not impaired by OM treatment. Taken together these data indicate the activities of this cytokine in vivo are antiinflammatory without concordant immunosuppression.

Oncostatin M: development of a pleiotropic cytokine

Oncostatin M (OM) is a member of the interleukin-6 (IL-6) cytokine subfamily. The binding of OM to its receptor initiates signal transduction through JAK-signal transducers and activators of transcription (STAT) pathways and activates transcription activators through mitogen-activated protein (MAP) kinases. Results of in vitro assays documented that OM modulates cytokine expression and alters the production of proteases that down-regulate inflammation. Administration of OM to lipopolysaccharide (LPS)-challenged mice lowered serum tumor necrosis factor-alpha (TNF-alpha) levels and decreased the lethal effects of LPS administration. OM also reduced inflammation in animal models of human disease, including inflammatory bowel disease, antibody-induced arthritis, and experimental autoimmune encephalomyelitis. Preclinical safety studies have been conducted in the mouse and monkey. Mice were administered OM (subcutaneously) at 72, 360, or 1,560 micrograms/kg/day in a 2-wk toxicity study. Decreased body weights occurred at 1,560 micrograms/kg. Drug-related changes at 360 and 1,560 micrograms/kg consisted of dermal irritation at the injection site, leukopenia, and thymic lymphoid depletion; all changes were reversible following a 2-wk recovery period. In a 2-wk subcutaneous study in monkeys, OM was administered at 1, 5, 15, 45, or 150 micrograms/kg/day. At all doses there was reversible, transient inappetence and dermal irritation at the injection site. Drug-related changes at 5, 15, 45, and 150 micrograms/kg consisted of reversible elevations in both serum amyloid A and IL-6, and reversible thymic lymphoid depletion. Transient increases in body temperature occurred at 15, 45, and 150 micrograms/kg. The observed spectrum of immunomodulatory effects suggests that OM may have therapeutic utility in treating chronic inflammatory diseases.

Molecular phylogeny and in situ detection of the etiologic agent of necrotizing hepatopancreatitis in shrimp

Necrotizing hepatopancreatitis (NHP) is a severe disease of farm-raised Penaeus vannamei that has been associated with mortality losses ranging from 20 to 95%. NHP was first recognized in Texas in 1985 (S. K. Johnson, p. 16, in Handbook of Shrimp Diseases, 1989) and is an economically important disease that has limited the ability to culture shrimp in Texas. The putative cause of NHP is a gram-negative, pleomorphic, intracellular, rickettsia-like bacterium that remains uncultured in part because of the absence of established shrimp cell lines. The inability to culture the NHP bacterium necessitated the use of molecular methods for phylogenetic placement of the NHP bacterium. The gene encoding the 16S rRNA (16S rDNA) of this shrimp pathogen was amplified by PCR, cloned, and sequenced. Sequence analysis of the cloned 16S rDNA indicates that the NHP bacterium is a member of the alpha subclass of the Proteobacteria. Within the alpha subclass, the NHP bacterium is shown to be most closely related to bacterial endosymbionts of protozoa, Caedibacter caryophila and Holospora obtusa. Also, the NHP bacterium is distinct from but related to members of the typhus group (Rickettsia typhi and R. prowazekii) and spotted fever group (R. rickettsii) of the family Rickettsiaceae. Fluorescently labeled oligonucleotide DNA probes that bind to variable regions (V2, V6, and V8) of 16S rRNA of the NHP bacterium were used to detect the bacterium in infected shrimp by in situ hybridization. This technique provided direct visual evidence that the 16S rDNA that was amplified, cloned, and sequenced was derived from the intracellular bacterium that infects the hepatopancreas of farm-raised P. vannamei shrimp.

Neutrophil infiltration, glial reaction, and neurological disease in transgenic mice expressing the chemokine N51/KC in oligodendrocytes

Chemokines (pro-inflammatory chemoattractant cytokines) are expressed in pathological conditions of the central nervous system (CNS). Previous studies suggested that the CNS is relatively resistant to leukocyte diapedesis after chemokine injection, leaving their functional role unresolved. The CNS function of N51/KC, a neutrophil-selective chemokine, was addressed by expressing N51/KC under control of the myelin basic protein (MBP) promoter in transgenic (tg) mice (MBP-N51/KC mice). CNS-specific N51/KC expression produced remarkable neutrophil infiltration into perivascular, meningeal, and parenchymal sites, demonstrating that this chemokine exerts the multiple functions in vivo required to recruit leukocytes into the CNS. MBP-N5 1/KC mice represent an incisive model for the molecular dissection of neutrophil entry into the CNS. Unexpectedly, MBP-N51/KC mice developed a neurological syndrome of pronounced postural instability and rigidity at high frequency beginning at 40 days of age, well after peak chemokine expression. 68/182 mice in one tg fine were found dead before one year of age, with prominent neurological symptoms premortem in 26 (38%). Florid microglial activation and blood-brain barrier disruption without dysmyelination were the major neuropathological alterations. Late-onset neurological symptoms in MBP-N51/KC mice may indicate unanticipated consequences of CNS chemokine expression.

Specific, nonradioactive detection of the NHP bacterium in Penaeus vannamei by in situ hybridization

Necrotizing hepatopancreatitis (NHP) is a disease of farm-raised Pacific white shrimp (Penaeus vannamei) caused by a pleomorphic intracellular bacterium. A DNA probe that is specific for the etiologic agent of necrotizing hepatopancreatitis was devised and tested in an in situ hybridization assay. A procedure was developed for labeling a single-stranded DNA probe with digoxigenin by the polymerase chain reaction. The DNA probe encompasses the V1 and V2 variable regions of the 16S ribosomal RNA (rRNA) gene and is designed to hybridize to complementary sequences of the 16S rRNA of the NHP bacterium. The probe was tested on fixed, paraffin-embedded specimens, and an intense, specific hybridization signal was localized to the cytoplasm of hepatopancreatic epithelial cells that were infected with the NHP bacterium, as demonstrated by serial sections stained with hematoxylin and eosin or the Steiner and Steiner method. Negative results were obtained from normal shrimp and from shrimp infected with Vibrio spp. The specificity of the probe was confirmed using either mammalian or avian tissues infected with other intracellular bacteria, including Ehrlichia canis, Salmonella enteritidis, Brucella abortus, and Chlymidia spp., and using another species of shrimp (P. monodon) infected with a different rickettisa-like intracellular bacterium.

Nasopharyngeal conidiobolomycosis in a horse

Nasopharyngeal conidiobolomycosis caused by Conidiobolus coronatus was diagnosed in a horse after endoscopic and histopathologic examinations of a biopsy specimen. The fungal lesions in the nasopharynx were substantially reduced in size after intralesional injection of amphotericin B through the biopsy channel of a videoendoscope in combination with i.v. administration of sodium iodide and oral administration of potassium iodide during a 2-month period. Endoscopy performed 15 months after initial examination revealed regression of the granulomatous masses in the nasopharynx and complete disappearance of the nasal masses. Two months later, clinical signs recurred, and the owner elected euthanasia without evaluation and treatment. Nasopharyngeal conidiobolomycosis may be treated successfully with intralesional injection of amphotericin B in combination with administration of sodium iodide and potassium iodide, but there is a possibility of recrudescence of infection.

Vertebral fracture associated with trauma during movement and restraint of cattle

Two female Limousin calves in a group of 68 calves suffered fractures of a lumbar vertebra subsequent to moving through a chute and being restrained to facilitate administration of vaccines. One calf collapsed as it exited the chute, whereas the second calf collapsed 10 minutes after it was released from the chute. Both heifers were euthanatized. The fractures, of the first lumbar and of the third lumbar vertebral bodies, respectively, were not associated with mineral imbalances. Fractures were determined to be the result of calves attempting to escape through a gap formed by erosion of the area beneath a gate in the holding pen of the corral system. By moving cattle in such a way as to bypass the gate, further injuries were avoided. The calves described here underscore the importance of the use of corral systems appropriate for cattle of various sizes and the necessity of maintaining properly repaired corral systems to prevent injuries to cattle.

Splenic vein thrombosis resulting in acute anemia: an unusual manifestation of nephrotic syndrome in a Chinese shar pei with reactive amyloidosis

Nephrotic syndrome in a seven-year-old Chinese shar pei resulted in oliguric renal failure, coagulopathy, and acute anemia. Renal amyloidosis and widespread thromboses were diagnosed postmortem. Splenic vein thrombosis caused significant splenic congestion, coagulative necrosis, and acute anemia. Splenic vein thrombosis is reported here as an unusual consequence of nephrotic syndrome in the dog.

Eosinophilic gastroenteritis with encapsulated nematodes in a horse

A 3-year-old Quarter Horse gelding admitted for evaluation of weight loss, signs of depression, and dermatitis of the coronary bands was found to have eosinophilic gastroenteritis. Intralesional nematodes identified as Strongylus edentatus were seen in multiple microscopic sections of the small colon, suggesting a parasitic cause of the disease.