Gastric Ollulanus tricuspis infection identified in captive cheetahs (Acinonyx jubatus) with chronic vomiting.

Gastritis, vomition and weight loss are common in captive cheetahs (Acinonyx jubatus). Gastric spiral bacteria (Helicobacter spp.) and the very small, viviparous nematode Ollulanus tricuspis, a stomach worm of cats, are believed to be important causes. Three sibling cheetahs at Wellington Zoo, New Zealand, developed chronic vomiting, diarrhoea and debility. Their parents were both South African-born. Response to antibacterial treatment was poor. Endoscopic examinations revealed chronic lymphoplasmacytic gastritis and Ollulanus infection. Treatment with oxfendazole and pyrantel embonate resulted in clinical improvement; however, 1 cheetah, which died 7 months later as a result of a ruptured liver due to hepatic amyloidosis, still had Ollulanus worms present in her stomach. Ollulanus tricuspis is a significant cause of gastritis and vomiting in captive cheetahs, lions and tigers, as well as wild cougars and tigers. The parasite has not yet been found in sub-Saharan Africa. Because of the unusual characteristics of this parasite, the literature on its life history and techniques for diagnosis is reviewed.

Mechanism and prevention of neurotoxicity caused by beta-amyloid peptides: relation to Alzheimer's disease.

In Alzheimer's disease, neurotoxic beta-amyloid peptides cause a deleterious influx of calcium ions into neurons. This increase in [Ca2+]int is expected to trigger intracellular events that eventually cause cell dysfunction and cell death. We find that the aggregated beta-amyloid peptide beta AP25-35 opens irreversibly a Ca(2+)-carrying channel, as does aggregated beta AP1-42. The opening of this channel is unaffected by DL-AP5, but it is blocked by Mg2+, CNQX and DNQX, suggesting a non-NMDA channel. External calcium enters and cytosolic calcium levels rise several-fold, as measured by fura-2 ratiometric analysis. Our findings illustrate a very early molecular event in the neurotoxicity of Alzheimer's disease. To combat the neurotoxic effect of aggregated beta-amyloid peptides, we have devised a series of very short antagonistic peptides. Using a combinatorial library of hexapeptides made from D-amino acids, we have selected peptides by their ability to complex with the tagged beta-amyloid peptide beta AP25-35. Certain of these so-called 'decoy peptides', as well as some modified decoy peptides, are able to abolish the calcium influx caused by aggregated, probably fibrillar, beta-amyloid peptides beta AP25-35 and beta AP1-42.

Hyperphosphorylation of human TAU by brain kinase PK40erk beyond phosphorylation by cAMP-dependent PKA: relation to Alzheimer's disease.

Abnormal hyperphosphorylation of the cytoskeletal protein TAU is seen in the characteristic paired helical filaments [neurofibrillary tangles] of Alzheimer's disease [AD]. A recently described protein kinase, PK40erk, (1) a member of the ERK family of kinases, can produce in vitro many of the properties of Alzheimer-like hyperphosphorylated TAU. cAMP-dependent protein kinase A [PKA] phosphorylates TAU to a lesser extent; however, the product is not like the hyperphosphorylated TAU of AD in several important respects. We now report that in vitro PK40erk, a candidate for the enzyme responsible for TAU hyperphosphorylation in AD, will further phosphorylate TAU that was previously saturated by protein kinase A, provided that the concentrations of free uncomplexed ATP are low. Interestingly, the actions of different kinases on TAU are not independent, but may depend on the order in which they work on TAU; i.e., prior phosphorylation by PKA partially inhibits the action of PK40erk.

Localization of a putative human brain sodium channel gene (SCN1A) to chromosome band 2q24.

We have identified four putative human sodium channel gene sequences, 55 bp each, using the polymerase chain reaction (PCR) on total human placental DNA with primers specific for the cDNA sequence of the rat brain sodium channel I alpha (Scn1a) gene. One of these sequences was extended bidirectionally by genomic inverse-PCR to obtain a 1.6-kb fragment. Sequencing of this 1,556-bp fragment showed a 282-bp complete exon, which has 95% and 94% homology at the nucleotide and amino acid levels, respectively, with the rat Scn1a gene. We putatively assign this sequence as belonging to the gene coding the alpha-subunit of a human brain type I sodium channel (SCN1A). PCR on human x rodent somatic cell hybrids with primers derived from SCN1A localized this gene to chromosome 2. Fluorescence in situ hybridization to human metaphase chromosomes sublocalized the gene to chromosome band 2q24.

A mitochondrial DNA deletion in normally aging and in Alzheimer brain tissue.

By quantitative polymerase chain reaction (PCR) of total cellular DNA, the known 4977 bp deletion in human mitochondrial DNA (mtDNA delta 4977) was not detected in rapidly dividing tissue such as placenta and lymphocytes, nor in brain tissue from fetuses and in frontal cortex from two individuals 24 and 56 years old. However, in frontal cortex from individuals 71-95 years 0.13% deleted/undeleted mtDNA was found, with no significant difference between Alzheimer patients (0.14%) and age-matched controls (0.12%). We hypothesize that the age-related accumulation of this deletion (and other expected deletions) contributes to the down-regulation of adenosine triphosphate (ATP) production in neurons and other non-dividing cells, a fundamental mechanism common to aging and Alzheimer's disease.

Age-related neurofilament phosphorylation in normal human brains.

An age-related phosphorylation of the 200kD neurofilament protein (NF200) has been observed in the axons of cerebellar basket cells of normal human fixed brain tissue from individuals older than 60 years, but not in younger individuals. The probe for this study was the monoclonal antibody SMI-34 which detects a phosphorylated epitope on NF200 which appears to be different from the more frequent NF200 phosphorylated epitope found by another monoclonal antibody, SMI-31. The SMI-31 epitope was detected in our specimens at all ages examined. In sections of brainstems from normal individuals older than 52 years, from Alzheimer's disease individuals older than 65 years and from older Down's syndrome individuals (greater than 56 years) certain axons in the medial longitudinal fasciculus and in the mesencephalic trigeminal tract react positively with SMI-34, the antibody which detects the "age-related" phosphorylation epitope. All our Alzheimer's disease specimens and all our Down's syndrome specimens, even the younger ones, show staining of these fibers with SMI-31. The biochemistry of the "age-related" phosphorylation of NF200 remains to be explained.