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Biomedical subjects

M C Roberts

Publications and source records attributed to M C Roberts.

At least 253 records · Page 14Linked to original sources
PubMed1975

Malabsorption in the horse associated with alimentary lymphosarcoma.

Three horses suffering from malabsorption were shown to have alimentary lymphosarcoma predominantly affecting the small intestine and the associated lymph nodes. The diffuse cellular infiltration in two of the case produced marked changes in the villous architecture reducing the available mucosal surface area, and, with lowered or barely detectable disaccharidase activities, contributed to the impairment of digestive-absorptive processes. One of the horses maintained a voracious appetite and was not diarrhoeic, but failed to gain weight, indicating differences in the production and utilisation of energy sources absorbed from the small and the large intestines. A large proportion of plasma cells in the infiltrate, and the resulting morphological changes in two of the cases bore a striking resemblance to features of alpha chain disease, an immunodeficiency disease of man, although immunological studies were not conducted on these horses.

Animals↗
PubMed1975

The development and distribution of mucosal enzymes in the small intestine of the fetus and young foal.

Lactase and cellobiase were detectable in the fetal intestine by the 3rd month of gestation, and although there was little change by the 9th month, maximal levels were reached at birth and steadily declined after 4 months. Conversely maltase, sucrase and trehalase were barely discernible in the fetus, maltase being present at low levels at birth, but all increased during the suckling period to attain adult levels by 7 months of age. Alkaline phosphatase activity matured earlier than did disaccharidase activity. Mucosal enzymes other than alkaline phosphatase were virtually absent from meconium and the large intestine. Continued ingestion of lactose could be detrimental in foals suffering from severe diarrhoea.

Alkaline Phosphatase↗
PubMed1975

Carbohydrate digestion and absorption in the equine small intestine.

Dietary carbohydrates, which constitute a most important source of equine nutrition, are digested and absorbed by a series of complex processes principally in the small intestine, beginning with intraluminal starch hydrolysis by the action of pancreatic amylase. The continuous secretion of a copious volume of pancreatic juice, low in enzyme activity, presumably releases sufficient oligosaccharides for further hydrolysis at the intestinal cell surface by brush border enzymes. Active carrier mediated mechanisms then transport the final hexose products across the intestinal cell for uptake in the hepatic portal system. Brush border disaccharidase activities in the equine small intestine are of the same order of magnitude, and have a similar distribution pattern, to those reported in omnivorous and carnivorous species. The disaccharidase development patterns are characteristic and reflect the ability of the horse to digest the major nutrient sources adequately at various stages of life. The efficiency of the mucosal disaccharidases and the monosaccharide transport systems in the equine small intestine have been established by a series of oral disaccharide and monosaccharide tolerance tests. Horses older than three years of age are unable to hydrolyse lactose, but young and adult horses are fully capable of rapidly hydrolysing sucrose and maltose loads. Several tests have clinical application for assessing small intestinal dysfunction in the investigation of diarrhoea and malabsorption. The deficient digestion or absorption of carbohydrate, whether primary or secondary, can almost always be localized to a defect in the enzymic or transport capacity of the small intestinal surface cell. The continued ingestion of lactose could be detrimental in severely diarrhoeic foals.

Animals↗
PubMed1975

Carbohydrate digestion and absorption studies in the horse.

The ability of the horse to digest and absorb soluble carbohydrates was assessed using a series of oral disaccharide tolerance tests followed in the same animals by tolerance tests with the constituent monosaccharides. In horses older than three years, lactose did not produce an increase in the plasma glucose levels but induced the passing of soft faeces, indicating that adult horses are lactose intolerant. Horses of all ages could absorb the glucose: galactose mixture without any change in the faeces. The tolerance is due to a failure to hydrolyse lactose and does not involve the monosaccharide transport systems. These findings correspond to the known development pattern of brush border lactase activity in the equine small intestine. Both sucrose and maltose were rapidly hydrolysed, the resulting tolerance curves closely approximating to those for the constituent monosaccharides. Galactose was absorbed at a similar rate to glucose, although a dose of 1g/kg was necessary to produce galactosaemia. An oral lactose tolerance test (1 g/kg as a 20 per cent solution) could be of clinical value to determine small intestinal mucosal damage in diarrhoeic foals when the continued ingestion of lactose might be detrimental.

Animals↗
PubMed1973

Small intestinal beta-galactosidase activity in the horse.

Two enzymes having lactase activity are present in the equine small intestine. The first, the digestive enzyme, neutral beta-galactosidase, declines in activity from birth to three years, disappearing completely between 3 and 4 years of age. The other, the soluble lysosomal enzyme, acid beta-galactosidase, having affinity for lactose and a synthetic beta-galactoside, shows a decrease in activity in the first three months of life and thereafter varies little in activity and represents the lactase enzyme in the adult horse. This pattern may parallel the development of lactase activity in many other mammals and in the majority of the world's human population.

Age Factors↗
PubMedDate not supplied

Evaluating outpatient pediatric psychology services in a primary care setting.

OBJECTIVE: To provide descriptive and outcome information of an outpatient pediatric psychology clinic based in a medical center in a major metropolitan area. METHODS: We coded the characteristics and outcomes of 100 patients prospectively on a number of dimensions. Surveys and interviews were used to gather follow-up information. RESULTS: The majority of patients were Caucasian boys (n = 56 out of 100) between 2 and 12 years of age. The most common reasons for initiating contact with the clinic were assessment of school problems, behavior problems, anger, attention problems, depression, and temper tantrums. Eighty-one percent of the patients saw a therapist for brief treatment, between one and five sessions, and behavioral treatments were administered for the majority. The children's behavior for which the parents sought treatment improved significantly from pre- to posttreatment, as rated by parents and therapists. CONCLUSIONS: Overall, parents were satisfied with the services received and indicated that the recommendations given during therapy were helpful and easy to implement. This study provides general evidence for the effectiveness of pediatric psychology services.

Adolescent↗
PubMedDate not supplied

Agar dilution method for determination of antibiotic susceptibility of Ureaplasma urealyticum.

The agar dilution method was adapted for use in determining antibiotic sensitivities of clinical isolates of Ureaplasma urealyticum. The reproducibility of end points (minimal inhibitory concentrations) for tetracycline was excellent within one dilution; however, for spectinomycin and erythromycin end points increased 2-fold between 3 and 4 days of incubation. When incubation times were held constant for these antibiotics the method was reproducible within two dilutions (4-fold). The use of a Steers' replicator permitted many strains to be tested. Although it is recognized that ureaplasmas present unique problems among mycoplasmas because of their small colony size, suitable developmental studies will make agar dilution an important method for determining antibiotic susceptibilities of ureaplasmas.

Culture Media↗
PubMedDate not supplied

TetM tetracycline-resistant determinants in Ureaplasma urealyticum.

Ureaplasma urealyticum is an organism usually considered susceptible to tetracycline, with a minimal inhibitory concentration of 1 microgram/ml or less. Sixty-three clinical strains of U. urealyticum and serovars 1 through 9 were screened for resistance to tetracycline. Thirteen clinical isolates of U. urealyticum and one serovar (9) were resistant to high levels of tetracycline. They differed from each other on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and immunoblotting. All 14 strains contained DNA sequences homologous to the streptococcal determinant tetM which suggests the spread of this gene to the genus Ureaplasma.

Drug Resistance, Microbial↗
PubMedDate not supplied

Frequency in the United States of non-beta-lactamase-producing strains of Neisseria gonorrhoeae possessing the 24.5-Mdal conjugative plasmid.

We characterized 475 non-beta-lactamase-producing gonococcal isolates from five U.S. cities by auxotype, serovar, and plasmid content to determine the frequency of isolates with the 24.5-Mdal gonococcal conjugative plasmid. A total of 150 (32%) of all isolates possessed the 24.5-Mdal plasmid; these isolates represented between 10% and 53% of isolates from each city. Isolates possessing the 24.5-Mdal plasmid belonged to 45 (56%) of 81 auxotype/serovar (A/S) classes, or between 24% and 70% of the A/S classes isolated in each city. Overall, a higher proportion of strains isolated in the southern cities possessed the 24.5-Mdal plasmid than did those from northeastern or northwestern cities. These strains appear to have spread independently of the spread of beta-lactamase-producing Neisseria gonorrhoeae strains. The prevalence of N. gonorrhoeae strains with the 24.5-Mdal conjugative plasmid has increased substantially and may have important implications for the epidemiology of gonorrhea caused by beta-lactamase-producing strains.

Conjugation, Genetic↗