Alzheimer's disease: the relationship between the density of senile plaques, neurofibrillary tangles and A4 protein in human patients.

The numerical density of senile plaques (SP) and neurofibrillary tangles (NFT) as revealed by the Glees silver method was compared with SP and NFT revealed by the Gallyas method and with amyloid (A4) deposits in immunostained sections in 6 elderly cases of Alzheimer's disease. The density of NFT was generally greater and A4 lower in tissue from hippocampus compared with the neocortex suggesting that A4 deposition was less important than the degree of paired helical filament (PHF) related damage in the hippocampus. The density of Glees SP was positively correlated Gallyas SP weakly correlated with A4 deposit number. A stepwise multiple regression analysis which included A4 deposit and Gallyas SP density and accounted for 54% of the variation in Glees SP density. Hence, different populations of SP were revealed by the different staining methods. The results suggested that the Glees method may stain a population of SP in a region of cortex where both amyloid deposition and neurofibrillary changes have occurred.     

Characterisation of the human GFRalpha-3 locus and investigation of the gene in Hirschsprung disease

BACKGROUND—The GDNF family receptor alpha (GFRα) proteins are extracellular cell surface bound molecules that act as adapters in binding of the GDNF family of soluble neurotrophic factors to the RET receptor. These molecules are essential for development of many neural crest derived cell types and the kidney. Mutations in RET and in two members of the GDNF ligand family are associated with Hirschsprung disease (HSCR), a congenital absence of the enteric ganglia. Members of the GFRα family are also candidates for HSCR mutations. One such gene is GFRα-3, which is expressed in the peripheral nervous system and developing nerves.
OBJECTIVE—We have characterised the structure of the human GFRα-3 locus and investigated the gene for sequence variants in a panel of HSCR patients.
METHODS—Long range PCR or subcloning of PAC clones was used to investigate GFRα-3 intron-exon boundaries. A combination of single strand conformation polymorphism (SSCP) analysis and direct sequencing was used to investigate GFRα-3 sequence variants.
RESULTS—GFRα-3 spans eight coding exons and has a gene structure and organisation similar to that of GFRα-1. We identified three polymorphic variants in GFRα-3 in a normal control population, a subset of which also occurred in HSCR patients. We did not detect any sequence variants within the coding sequence of GFRα-3. We found a base substitution in the 5' UTR of GFRα-3, 15 base pairs upstream of the translation start site. A second substitution was identified in intron 4 (IVS4-30G>A) between the splice branch site and the splice acceptor site. The final variant was a 2 base pair insertion within the splice donor consensus sequence of exon 7 (IVS7+4ins GG).
CONCLUSIONS—We did not detect any correlation between variants of GFRα-3 and the HSCR phenotype. Our data suggest that mutations of this gene are not a cause of HSCR.


Keywords: GFRα-3; Hirschsprung disease; RET     

Early time course of the acute phase protein response in man.

The rate at which the acute phase protein response occurred after both major and minor surgery was explored. Increases in the plasma concentration of C-reactive protein (CRP), alpha-1-acid glycoprotein (alpha 1 AG) and fibrinogen were not detected until 6-8 h after the initial incision. The peak concentration of CRP occurred at 48 h and that of fibrinogen at 96 h; alpha 1 AG concentrations rose rapidly until 48 h followed by little change until about 120 h. Although there was widespread variation in the concentrations of individual proteins in patients, severity of injury did not seem to have a significant effect on the time course of the change. Plasma cortisol concentration and the total white blood cell count (WBC) reached their peaks before the acute phase proteins, cortisol at 6 h and WBC at 12 h.     

Changes in Ca2+ ion activity within unrestrained rat's hippocampus perfused with alcohol or acetaldehyde

In the freely moving rat, the kinetics of Ca²⁺ ion activity were determined at circumscribed sites in the hippocampus, which was perfused with ethanol, tertiary-butyl alcohol or acetaldehyde. Initially, a region in CA1 or other cell field of the dorsal hippocampus was prelabelled by microinjection of⁴⁵Ca²⁺ through a permanently implanted guide tube. Then the tip of a concentric push-pull cannula assembly was lowered through the guide tube to the labelled site, and an isotonic artificial cerebrospinal fluid was repeatedly perfused at a rate of 25 μ1/min. Each perfusion was timed for 5.0min with a 5.0 min interval between each. Once the washout curve of⁴⁵Ca²⁺ activity had begun to approach its asymptote, ordinarily in the midpoint of a series of perfusions, an isotonic solution of ethanol (188–942 mM), tertiary-butyl alcohol (12–580 mM) or acetaldehyde (10–98 mM) was added to the fourth perfusate. Thereafter, the hippocampal site was again perfused with the normal cerebrospinal fluid for the remainder of the experiment. Although the lowest concentration of ethanol exerted no effect on⁴⁵Ca²⁺ ion activity, an intermediate concentration caused mixed effects in either enhancing or suppressing the efflux into the perfusate of this cation. The highest concentration of ethanol produced in most experiments an initial suppression in Ca²⁺ ion efflux which was followed frequently by an elevation in the release of⁴⁵Ca²⁺. Similar changes in Ca²⁺ ion activity were produced by tertiary-butyl alcohol, but the magnitude of its effect was generally less than that of ethanol, suggesting that its effect on brain tissue differs from that of ethanol. Acetaldehyde evoked an intense and concentration-dependent enhancement of Ca²⁺ ion efflux from the perfused tissue at all of the sites in the hippocampus examined.These results suggest that in the unrestrained rat ethanol could unbind Ca²⁺ ions from hippocampal membranes or retard their uptake into cells of the hippocampus. The dual excitatory and inhibitory effect of ethanol on Ca²⁺ ion activity corresponds to the electrophysiological effects of this alcohol and could alter neurotransmitter release from neurons in this subcortical structure. The mechanism of action of acetaldehyde is envisaged to be due to its affinity to membrane sulfhydryl groups which alters protein conformation and thus interferes with both Ca²⁺channels and Ca²⁺ binding properties.     

Considerations in using linkage analysis as a presymptomatic test for Huntington''s disease.

The polymorphic locus D4S10 that is genetically linked to the locus for Huntington's disease (HD) has made possible a presymptomatic test for those at risk. Because the symptoms of this progressively debilitating and fatal illness are not usually manifest until adulthood, the outcome of the test will influence major decisions about career, marriage, and procreation. Several differential diagnoses must be considered before using the test if HD is not confirmed in at least one family member. Review of a large number of pedigrees has shown that 40% of persons at risk do not have appropriate family structure for a linkage test. Furthermore, uncooperative or inaccessible relatives may make this test infeasible for many others who wish to be tested. Linkage phase, which must be known in the affected parent for an informative test, can be determined using one or more of 12 probe-enzyme combinations for D4S10. Although the polymorphism information content (PIC) value for any one RFLP is less than 40%, the PIC value for the haplotype of the two G8 HindIII, pK083 EcoRI, and R7 BglII RFLPs is greater than 88%. We have developed a scheme to incorporate linkage data and age at onset information adjusted for censored observations, sex of affected parent, and familial correlation for age at onset, using the computer program MLINK for calculation of risk of having HD. Simulated experiments showed that proper age at onset adjustment is crucial to the calculation of the probability of risk. A formal presymptomatic testing protocol, including pre- and post-test counselling, psychological testing, and paternity testing is recommended. Many of these considerations are illustrated in several actual test cases.     

Bactericidal Activity of Blood of Rabbits Vaccinated With Homologous Antigens of Campylobacter fetus (Vibrio fetus)

Rabbits were vaccinated with the following Campylobacter fetus var. venerealis (Vibrio fetus) antigens: whole-cell (WC), autoclaved (A), boiled (B), and purified postgrowth broth (PGB). Bactericidal activity of freshly drawn heparinized blood against the organism was determined after each vaccination. In all cases bactericidal activity of the blood of vaccinated rabbits was higher than for nonvaccinated rabbits. The in vitro bactericidal activity of the blood was determined in two separate experiments. In experiment I the bactericidal activity of the blood of rabbits vaccinated with PGB antigen was the same as that of rabbits vaccinated with WC antigen and higher than that of rabbits vaccinated with A antigen after the third vaccination. In experiment II the bactericidal activity of blood of rabbits vaccinated with PGB antigen was the same as that of those vaccinated with WC antigen after the second and third vaccinations and higher than for rabbits vaccinated with A antigen after the third vaccination. Blood of rabbits vaccinated with A antigen was less bactericidal than blood of rabbits vaccinated with B antigen after the third vaccination, indicating the presence of a surface antigen destroyed by autoclaving but not by boiling. The in vivo and in vitro whole blood bactericidal tests are more sensitive for measuring the response of rabbits vaccinated with WC, B, A, or PGB antigens than is the plate agglutination test.     

Sedative but not anxiolytic properties of benzodiazepines are mediated by the GABA(A) receptor alpha1 subtype

Inhibitory neurotransmission in the brain is largely mediated by GABA(A) receptors. Potentiation of GABA receptor activation through an allosteric benzodiazepine (BZ) site produces the sedative, anxiolytic, muscle relaxant, anticonvulsant and cognition-impairing effects of clinically used BZs such as diazepam. We created genetically modified mice (alpha1 H101R) with a diazepam-insensitive alpha1 subtype and a selective BZ site ligand, L-838,417, to explore GABA(A) receptor subtypes mediating specific physiological effects. These two complimentary approaches revealed that the alpha1 subtype mediated the sedative, but not the anxiolytic effects of benzodiazepines. This finding suggests ways to improve anxiolytics and to develop drugs for other neurological disorders based on their specificity for GABA(A) receptor subtypes in distinct neuronal circuits.     

Immunohistochemical evaluation of T cells in oral lesions from human immunodeficiency virus-positive persons with oropharyngeal candidiasis

Oropharyngeal candidiasis (OPC), caused by Candida albicans, is the most frequent opportunistic fungal infection in human immunodeficiency virus (HIV)-positive persons. Although Th1-type CD4(+) T cells are considered important for host defense against mucosal C. albicans infections, there is a paucity of information regarding the presence and/or role of T cells in OPC lesions. In pursuit of this, initial chromophore immunohistochemical studies showed a majority of CD8(+) rather than CD4(+) cells equally distributed throughout the buccal mucosa of OPC(-) persons (HIV(-) or HIV(+)), irrespective of blood CD4(+) cell numbers. In contrast, CD8(+) cells in lesions from HIV(+) OPC(+) persons were in significantly higher numbers and concentrated at the lamina propria-epithelium interface, a considerable distance from the Candida at the outer epithelium. Dual fluorescence and confocal microscopy confirmed that the majority of CD8(+), but not CD4(+), cells were T cells by the presence or absence, respectively, of CD3 on each cell type. These results suggest that CD8(+) T cells may be important for oral host defense against OPC, especially when CD4 cell numbers are reduced, with a potential CD8 cell-specific dysfunction associated with susceptibility to OPC.     

Conditioned changes in appetitive and consummatory responses to flavors paired with oral or nutrient reinforcement among adult rats

Recent studies of the behavioral organization of conditioned flavor preferences have suggested the involvement of at least two separate learning systems-an appetitive response system sensitive to the oral hedonic properties of the reinforcer, and a consummatory response system sensitive to its nutrient properties. However, these prior studies were conducted with weanling rats, that differ from adults in terms of their prior experience with food, their learning competencies, and the peculiar ontogenetic constraints on their behavior. It is, therefore, unknown whether flavor preference behaviors are similarly organized in adult rats. In this experiment, adult rats were trained to associate a specific CS flavor with either the sweet taste or the postingestive nutrient effects of sucrose. Conditioned appetitive orienting and consummatory oral responding to the CS flavors were then measured. Unlike weanling rats, adult rats exhibited both conditioned appetitive behavior and conditioned consummatory behavior in response a CS that was previously paired with either oral hedonic or nutrient reinforcement. These results suggest a set of important developmental changes in the neurobehavioral mechanisms of flavor preference learning in the postweaning period.