Modifications of the excitotoxic neurotransmitter theory of cellular damage are necessary to explain abnormalities in Alzheimer's disease. Reductions in enzymes of oxidative metabolism in Alzheimer brain and the subsequent histotoxic hypoxia may be a pathophysiological link to the neurotransmitter changes. Similar mechanisms may underlie the greater susceptibility of the aged brain to metabolic insults and this interaction may explain the age-related nature of Alzheimer's disease.

Aging↗

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Antigenic relationship between chikungunya virus strains and o'nyong nyong virus using monoclonal antibodies.

Chikungunya (CHIK) strains from Africa and Asia were shown to be antigenically closely related using a panel of monoclonal antibodies (mAb) prepared against strains H817 from Africa and PhH15483 from Asia. The one-way antigenic relationship between CHIK and o'nyong nyong (ONN) viruses was demonstrated at the epitope level using the immunofluorescence and haemagglutination inhibition techniques. Results of tests with mAb against ONN virus suggest that, while ONN virus has retained most of the CHIK antigenic sites, many of the ONN epitopes have undergone sufficient conformational change such that mAbs prepared against them do not recognize sites on CHIK virus.

Antibodies, Monoclonal↗

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Developmental evolution: going beyond the 'just so'.

Two new protocols for infecting non-mammalian embryos with viruses, together with RNA inhibition, have provided evolutionary developmental biologists with the tools to study the effects of manipulating gene activity in a wide range of species, allowing them to test hypotheses rather than rely on inference from similarity.

Animals↗

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Axial variation in the three-spine stickleback: genetic and environmental factors.

Subtle differences in the pattern of arrangement of types of vertebrae and associated median skeletal structures between a benthic and limnetic species pair of three-spine stickleback from Paxton Lake, British Columbia, are typical of those found throughout the range of the Gasterosteus aculeatus species complex. We established laboratory colonies from just three individuals of each species, and studied the effect of three generations of inbreeding on axial morphology. There was sufficient divergence in the location of individual elements between families to regenerate close to the entire range of axial diversity seen in threespine sticklebacks worldwide. Analysis of the patterns of variance and covariance between the axial locations of elements provides evidence for the action of both meristic and homeotic processes in the generation of morphological divergence within each species. Hybrid sticklebacks produced by the cross of limnetic and benthic parents tend to have intermediate morphologies, with dominance of either parental type evident for some elements. Effects of temperature and salinity were found to be small in direct comparison with between-family effects, and varied according to genetic background. These results demonstrate that considerable genetic variation for axial morphology is maintained in natural populations of three-spine stickleback, and that differences between populations may be brought about rapidly by changes in frequency of alleles that have coordinated effects along the body axis.

Animals↗

PubMedDate not supplied

Genetic variation for the positioning of wing veins in Drosophila melanogaster.

To define the components of variation for wing shape in Drosophila in relation to what is known about the developmental control of wing patterning, we have characterized shape variation in the wings of 12 randomly chosen highly inbred lines. Despite large differences in wing size between males and females, and between flies reared at 18 degrees C or 25 degrees C, wing shape is remarkably unaffected by these variables and is highly line specific. The shape of each intervein region of the wing appears to be independently regulated at the genetic level, consistent with the role of secreted growth factors in establishing the locations of wing veins. Sex and temperature were found to have different effects on cell number in two intervein regions, with the result that wing shape is to a large extent independent of cell density. Dietary cholesterol was also shown to affect the breadth of the central intervein region, consistent with an effect on the strength of Hedgehog signaling during wing development. We conclude that wing shape is under tighter genetic control than wing size, and hypothesize that this control is achieved in large part by gene activity at the level of wing vein determination and differentiation.

Animals↗

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The role of salivary function on oropharyngeal colonization.

Aspiration of oropharyngeal flora is the most common route of acquiring Gram-negative pneumonia, a major nosocomial infection. Epidemiologic studies indicate that the elderly are at increased risk for developing these life-threatening pneumonias. The primary objective of this study was to determine the effects of salivary oral defenses against Gram-negative colonization. The study population consisted of 41 male outpatients, age 70 and older, seen at the Denver VAMC. The group included subjects with both diminished and normal salivary flow. Each subject answered a questionnaire regarding overall health, medication use, and symptoms of salivary dysfunction. We then collected whole saliva, unstimulated and stimulated parotid saliva, and performed a throat swab on each patient. For each throat culture, analysis was done to identify Gram-negative bacteria. Flow rates between colonized (n = 6) and noncolonized subjects (n = 34) were compared. While there were no significant differences in the flow rates between the two groups, a trend was noticed in that flow rates were lower for all three flow measures in the colonized group (whole, 22% decrease; unstimulated, 22% decrease; and stimulated, 28% decrease). These preliminary findings suggest that subjects with diminished salivary flow may possibly be at increased risk for oropharyngeal Gram-negative colonization. Research on the role that saliva plays in oropharyngeal bacterial colonization is continuing.

Aged↗

PubMedDate not supplied

The level of cariogenic micro-organisms in patients with Sjögren's syndrome.

Sixteen patients with caries-inactive sjögren's syndrome with low parotid salivary flow rates (< 0.25 mL/min) and 18 caries-inactive control subjects with higher salivary flow rates were compared. Mutans streptococci (MS) and lactobacilli (LB) counts were measured by means of Dentocult SM strip mutans and LB assays. The group with Sjögren's syndrome displayed higher counts of MS (P = 0.014) and LB (p = 0.003) when compared with controls. The results of this study indicate that patients with caries-inactive Sjögren's syndrome and low salivary flow may have higher colonization of cariogenic micro-organisms than healthy individuals.

Aged↗

PubMedDate not supplied

Aging and oral health for the 21st century.

Americans' oral health, along with their life expectancy, has improved dramatically during the 20th century. The 21st century offers dental professionals the opportunity to help patients maintain their oral health for a lifetime. This article describes trends in health and wellness among older adults that will affect use of dental services; reviews risk factors such as chronic diseases, medications, and nursing home placement that will increase oral diseases in older adults; and concludes with opportunities for dental leadership to improve the oral health of aging Americans.

Aged↗

PubMedDate not supplied

Converting a teaching hospital medical clinic to a group practice: patients vote with their feet.

Traditional general medical clinics (GMCs) have been criticized as providing less than optimal primary care while losing money for the sponsoring teaching hospital. In addition, the GMC has become less attractive as a site for training house staff. In response, a number of teaching hospitals have sponsored the development of a primary care group practice as a more efficient alternative to the GMC. Under the new model, certain measures of patient care frequently improve, house staff receive better training, and the hospital may be able to trim financial losses. While the literature contains numerous descriptions of such conversions, very little information is available about the compliance of patients who are transferred to the new model with relatively little preparation or choice. Institutions that convert their GMCs may do so to attract new clientele. But they have a responsibility to their long-time patients and certainly should address the question of whom they expect to transfer successfully and what the dropout rate will be. New York City's Mount Sinai Hospital completed conversion of its GMC to a primary care group practice in 1983. A sampling of patients taken before the conversion, then followed up 6 months latter, revealed that 82 percent of the former GMC patients were successfully referred to the new model. Patients given specific appointments rather than instructions to call for their own appointment had a better "show" rate. Noncompliers were more likely to be female, Medicaid-covered, 46-65 years old, and living outside the hospital's immediate service area. Our data suggest that when hospitals close a GMC and transfer patients to a hospital sponsored alternative, they can expect to refer most patients successfully.

Adult↗

PubMedDate not supplied