Search PubMed⌕ Search

Biomedical subjects

M L Wilson

Publications and source records attributed to M L Wilson.

At least 127 records · Page 7Linked to original sources
PubMed1990

The development of a sedation model in dogs.

The effect of various sedatives (ketamine, valium, acetylpromazine) on the saliva flow rate, swallowing capacity, muscle rigidity and ability to immobilize in an upright position was investigated in dogs. Ten healthy beagle dogs (3, six months old, 3, six years old, and 4 fourteen years old) were used for this study. A combination of ketamine (5 mg/kg) and acetylpromazine (0.175 mg/kg) produced the desired effect of normal saliva flow rate, swallowing capacity and muscle rigidity; immobilization in an upright position was attained. The saliva flow rate (unsedated) was found to decrease with increasing age of the dogs. The time to recovery from the ketamine/acetylpromazine sedation increased with increasing age of the dogs.

Aging↗
PubMed1989

Rapid emergence of a focal epidemic of Lyme disease in coastal Massachusetts.

We describe a focal epidemic of Lyme disease, which spread from a nature preserve and affected an adjacent community of permanent residents in coastal Massachusetts. The attack rate from 1980 through 1987 was 35 percent among 190 residents living within 5 km of the nature preserve and was greatest (66 percent) among those living closest to the preserve. The risk of infection bore little relation to sex or age. Late Lyme disease, which clustered near the preserve, occurred mainly in residents infected early in the epidemic who did not have a history of erythema migrans and did not receive antibiotic therapy. All the residents with serologic evidence of infection had early or late clinical manifestations of Lyme disease, or both, during the period of study. The seasonal risk of infection was bimodal--greatest in June, with a secondary peak in October--and corresponded to periods of increased transmission. In the nature preserve, the density of the vector tick, Ixodes dammini, exceeded that in other New England sites. The zoonosis rapidly became endemic, and the severity of its impact correlated with the abundance of deer. This epidemic of Lyme disease demonstrated that outbreaks can be focal and can spread rapidly within a community of permanent residents.

Animals↗
PubMed1989

Comparing the relative potential of rodents as reservoirs of the Lyme disease spirochete (Borrelia burgdorferi).

The authors compared the contribution of white-footed mice (Peromyscus leucopus), chipmunks (Tamias striatus), and meadow voles (Microtus pennsylvanicus) to infection of vector ticks with the Lyme disease spirochete, Borrelia burgddorferi. At one Massachusetts location where Lyme disease is endemic, all three species of rodents were found to be infected. Prevalence of infection, however, varied from 90% for mice, and 75% for chipmunks to just 5.5% for meadow voles. Infectivity of these hosts for larval Ixodes dammini also varied, but mice were found to be the most infective, followed by chipmunks and meadow voles. Density estimates of these three hosts, collected between 1981 and 1986 in three coastal Massachusetts locations, revealed that mice were more abundant than the other two rodents in areas in which ticks were abundant. In addition, mice were infested more abundantly with larval I. dammini than the other two host species. Integrating these results, we determined each species' "reservoir potential," a novel term which describes the relative contribution made by a host species to the horizontal infection of a vector population. The authors' findings demonstrate that, at least in coastal Massachusetts, P. leucopus is the most important small mammal reservoir for B. burgdorferi.

Animals↗
PubMed1988

Overproduction of the MotA protein of Escherichia coli and estimation of its wild-type level.

The motA gene of Escherichia coli was placed under the control of a high-level promoter, that of the tryptophan operon of Serratia marcescens. In the presence of the inducer beta-indoleacrylic acid, MotA was synthesized at greatly elevated levels and inserted without apparent limit into the inner membrane. Growth and motility were impaired, but not drastically so, indicating that MotA by itself does not act as a proton ionophore. Antibody raised against the overproduced protein was used to estimate that a wild-type cell contained 600 +/- 250 copies of MotA. This number is more than would be needed to surround each flagellar basal body with a single circlet of MotA protein; possible interpretations of the result are discussed. The antibody was also used to establish that the MotA protein of Salmonella typhimurium has a similar molecular weight to that of E. coli and is immunologically cross-reactive with it; functional complementation of S. typhimurium motA mutants by the E. coli gene was established.

Bacterial Proteins↗
PubMed1988

Incompetence of deer as reservoirs of the Lyme disease spirochete.

To determine whether deer may serve as reservoir hosts for the Lyme disease spirochete, we sought evidence of infection in nymphal Ixodes dammini derived from larvae that had engorged on white-tailed deer. A total of 19 deer were shot in two Lyme disease foci in Massachusetts during September 1986, the season in which larvae were most abundant. An average of 342 larval ticks of this species were collected from each deer. Of those that developed to the nymphal stage, the gut contents of 185 were examined for Borrelia burgdorferi by a direct fluorescent antibody test. Spirochetes were detected in about 1% of these nymphs, a rate of infection attributable to transovarial transmission. In contrast, infection was detected in 23% of 39 field-swept nymphal ticks of the same cohort that were collected during the following season. Although deer may be infested by numerous larval I. dammini, such ticks appear not to become infected by Lyme disease spirochetes.

Animals↗
PubMed1988

Reference activity and the external user: confluence of community needs at a medical school branch library.

The allocation of reference services between primary and secondary users constantly challenges academic medical libraries. Routine statistics at a medical school branch library suggested that over 40% of its reference transactions involved persons not affiliated with the university. To investigate this finding, a survey of reference activity was conducted using measurement techniques unobtrusive to the user. Fifteen data items were recorded, including user status, type of question, intended use of information requested, status of staff taking request, and staff time spent. Survey results showed that nonaffiliates accounted for 51% of reference activity. Based on this documented data, definitive reference guidelines addressing hours, priority of requests, charges, and staffing patterns can now be developed. Findings will also assist in evaluating the library's regional role, in formulating marketing strategies, and in determining library objectives.

Community-Institutional Relations↗
PubMed1986

Longitudinal assessment of the clinical and epidemiological features of Lyme disease in a defined population.

From 1979 to 1983, Lyme disease was studied longitudinally in the 162 long-term residents of Great Island, Massachusetts. In retrospect, the index case occurred in 1962, and the peak years of disease transmission (about three new cases per 100 residents per year) were the late 1970s. Thereafter, during the period of active surveillance, attack rates declined by half. Altogether, 26 (16%) of the 162 residents developed symptoms of the disease. Most of those affected had erythema chronicum migrans, and when untreated, they subsequently developed arthritis or, in one instance, myocarditis. A minority of individuals, mostly children, had arthritis alone. Of 121 asymptomatic residents who gave blood samples, 10 adults (8%) had high titers of IgG antibodies to the Lyme disease spirochete; these titers sometimes persisted for years. From 1981 to 1983, the estimated ratio of apparent-to-inapparent infection was 1:1. The high frequency of Lyme disease on Great Island underscores the need for surveillance and control programs.

Adolescent↗
PubMed1986

Effect of charge on hepatic specific nature of vesicle encapsulated insulin in conscious dogs.

Positively [(+)-VEI] and negatively [(-)-VEI] charged formulations of vesicle encapsulated insulin (VEI) were compared with insulin on the basis of their ability to suppress hepatic glucose production (hepatic Ra) and stimulate glucose utilization (Rd) in conscious dogs. Our results indicate that (-)-VEI and insulin have an equivalent capacity to suppress hepatic glucose production at dose levels of 0.2, 1.2, and 2.4 mU X kg-1 X min-1. (+)-VEI is less effective at suppressing hepatic Ra than both insulin and (-)-VEI at dose levels of 1.2 and 2.4 mU X kg-1 X min-1. Both (+)-VEI and (-)-VEI induced significantly less glucose utilization than a comparable amount of insulin at dose levels of 1.2 and 2.4 mU X kg-1 X min-1. The amount of glucose utilization stimulated by (+)-VEI was significantly less than that induced by insulin at 0.6 mU X kg-1 X min-1. This difference was not evident with (-)-VEI. These results suggest that the insulin contained in (+)-VEI is less bioavailable than that contained in (-)-VEI. This difference in bioavailability is believed to be the result of greater serum stability of (+)-VEI vesicles when compared with that of (-)-VEI. In conclusion, both (+)-VEI and (-)-VEI have the capacity to shield encapsulated insulin from interacting with peripheral tissues and deliver insulin selectively to the liver. Both formulations afford one an opportunity to expand the therapeutic window for hepatically active compounds where their utility is limited by systemic toxicity.

Animals↗
PubMed1985

Racial and socioeconomic disparities in childhood mortality in Boston.

We examined racial and income-related patterns of mortality from birth through adolescence in Boston, where residents have high access to tertiary medical care. Childhood mortality was significantly higher among black children (odds ratio, 1.24; P less than 0.05) and low-income children (odds ratio, 1.47; P less than 0.001). Socioeconomic effects varied for different age groups and causes of death. The largest relative disparity occurred in the neonatal and postneonatal periods, and the smallest in adolescence. Of the total racial differential in neonatal mortality (6.88 deaths per 1000 live births), 51.2 per cent occurred in premature infants, 13.4 per cent in term infants who were small for their gestational age, and 25.9 per cent in neonates who were both premature and small for their age. Black neonatal mortality was elevated at all income levels. Beyond the neonatal period, mortality from respiratory disease, fire, and homicide had strong inverse relationships with income, and mortality from injuries to the occupants of motor vehicles was directly related to income. These data suggest that despite access to tertiary medical services, substantial social differentiation in mortality may exist throughout childhood. Equity in childhood survival will probably require policies that emphasize preventive goals.

Accidents, Traffic↗
PubMed1985

Membrane protein conformational change dependent on the hydrophobic environment.

Two conformational states of the coat protein of the filamentous bacteriophage M13 have been detected in detergent solution by using magnetic resonance techniques. When 3-fluorotyrosine is incorporated in place of the two tyrosine residues in the protein, four 19F nuclear magnetic resonance signals are observed, two for each conformer of the protein. The equilibrium between the two forms can be modulated by pH, temperature, and detergent structure. The rate of interconversion of the isomers is rapid on the minutes time scale but is slow relative to the T1 relaxation time of the fluorine resonances of approximately 50 ms. The conformational change between the conformers results in the perturbation of a basic residue in the protein such that this group has a pKa of approximately 9.5 in one state which shifts to 10.5 or more in the other conformational state. The temperature dependence of the equilibrium suggests an enthalpy difference of about 10 kcal/mol which is offset by entropy to give nearly zero free energy difference between the states at pH 8.3 in deoxycholate solution at room temperature. This suggests a substantial reorganization of the noncovalent interactions defining the two conformational states. The conformational equilibrium is strongly dependent on detergent structure and the presence of phospholipid in the detergent micelle. The results are not consistent with a strong, specific lipid binding to the protein but appear to be consistent with a more general effect of the overall micelle structure on the conformational state of the protein.

Coliphages↗
PubMed1985

Mice as reservoirs of the Lyme disease spirochete.

In evaluating the white-footed mouse as a reservoir host for the Lyme disease spirochete, we compared spirochete infection in vector ticks (Ixodes dammini) having different histories of attachment to these mice, estimated their relative importance as hosts for immature I. dammini and compared the seasonality of tick activity and spirochetemia in mice. Infection in trapped white-footed mice appears to be universal. Prevalence of spirochetal infection in I. dammini correlates with frequency of attachment to mice, and in mice, with the season of vector activity. The relative abundance of this mouse makes it numerically the most important host for I. dammini. Most immature I. dammini appear to attach to white-footed mice. Taken together, these considerations demonstrate that the white-footed mouse serves as reservoir for the Lyme disease spirochete in coastal Massachusetts.

Animals↗
PubMed1983

A simple quantitative method for the determination of 3-fluorotyrosine substitution in proteins.

A rapid quantitative method is described for determining 3-fluorotyrosine incorporation into proteins. Derivatives of tyrosine and 3-fluorotyrosine with o-phthalaldehyde are well separated from one another by a reverse-phase high-performance liquid chromatography system used for routine analyses of o-phthalaldehyde-amino acid derivatives. Since both amino acids are well resolved from all other derivatized amino acids, the method is useful for amino acid analyses of proteins. Determination of the fluorotyrosine content of proteins by this method involves a single separation step, is reproducible, and requires no corrections for stability or yield. Further, the o-phthalaldehyde derivatives of 5-fluorotryptophan, 2-fluorophenylalanine, 3-fluorophenylalanine, and 4-fluorophenylalanine can also be resolved. The method may be generally applicable to fluorinated aromatic amino acid-labeled proteins that are studied structurally and dynamically by nuclear magnetic resonance.

Chromatography, High Pressure Liquid↗