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Biomedical subjects

J Mayo

Publications and source records attributed to J Mayo.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Psoas abscess. The diagnostic and therapeutic considerations in 5 patients].

Five cases of psoas abscesses are discussed, four pyogenes and one tuberculous, the current etiology of this process, together with its pathogenesis and clinical manifestations are discussed. In all of them the guided punction through Computerized Axial Tomography (CAT) has been the way to diagnose and treat the process. Utility of this technique considering both aspects is discussed because it allows to determine the etiology and avoids the surgical drainage; even tough this therapy should be individualized in each case, probably is in primary staphylococci abscesses where this therapeutic option is best indicated.

Adult↗
PubMed1992

Influence of blood handling techniques on lactic acid concentrations.

Despite the popularity of measuring blood lactic acid concentrations, many of the common variations in technique have not been evaluated. The purposes of this study were to: 1) establish the relationship between plasma and blood lactate concentrations, 2) determine the inter-analyzer reliability, and 3) assess the stability of lactate concentration in blood stored for up to one week. Blood was sampled from 26 volunteers before exercise, at 80% of estimated maximum heart rate, and 5 minutes after a treadmill run to exhaustion. Inter-machine reliability was tested between two Yellow Springs Instruments analyzers with buffer treated with a lysing agent and between two without. Blood lactate levels at all three levels could be predicted from plasma with R2 greater than .95. Correlations between duplicates on the same machine were greater than .96 for blood and .97 for plasma. In the worst cases, between duplicate differences and between machine differences were 2%. Lactate in stored blood was in some cases significantly different after 24 hours of storage. Moderate and high lactate concentrations in plasma were not significantly altered after 2 days of storage.

Adult↗
PubMed1990

Extrathymic selection of TCR gamma delta + T cells by class II major histocompatibility complex molecules.

The influence of MHC antigens on TCR gamma delta usage in CD8+ intraepithelial lymphocytes (IELs) was examined using a pan-reactive and V delta 4 region-specific MAb. While an average of 30% of IELs from the majority of mice of various MHC haplotypes were V delta 4+, a 2-fold or greater percentage of IELs from H-2k mice were V delta 4+. Analysis of IELs from F1 mice indicated that the increase in TCRs using V delta 4 was likely to be the result of positive selection. The V delta 4 usage patterns of IELs from recombinant inbred strains and from mice recombinant within H-2 revealed that the increase in V delta 4 usage mapped to H-2 and required I-E expression. Moreover, selection of TCRs using V delta 4 occurred in chimeric mice in the absence of a thymus. The results demonstrate an extrathymic selective mechanism for gamma delta TCRs of CD8+ IELs and suggest that these cells may exhibit MHC class II-restricted antigen recognition.

Animals↗
PubMed1990

Interstudy reproducibility of dimensional and functional measurements between cine magnetic resonance studies in the morphologically abnormal left ventricle.

The validity of geometric formulas to derive mass and volumes in the morphologically abnormal left ventricle is problematic. Imaging techniques that are tomographic and therefore inherently three-dimensional should be more reliable and reproducible between studies in such ventricles. Determination of reproducibility between studies is essential to define the limits of an imaging technique for evaluating the response to therapy. Sequential cine magnetic resonance (MR) studies were performed on patients with dilated cardiomyopathy (n = 11) and left ventricular hypertrophy (n = 8) within a short interval in order to assess interstudy reproducibility. Left ventricular mass, volumes, ejection fraction, and end-systolic wall stress were determined by two independent observers. Between studies, left ventricular mass was highly reproducible for hypertrophied and dilated ventricles, with percent variability less than 6%. Ejection fraction and end-diastolic volume showed close reproducibility between studies, with percent variability less than 5% End-systolic volume varied by 4.3% and 4.5% in dilated cardiomyopathy and 8.4% and 7.2% in left ventricular hypertrophy for the two observers. End-systolic wall stress, which is derived from multiple measurements, varied the greatest, with percent variability of 17.2% and 15.7% in dilated cardiomyopathy and 14.8% and 13% in left ventricular hypertrophy, respectively. The results of this study demonstrate that mass, volume, and functional measurements are reproducible in morphologically abnormal ventricles.

Adult↗
PubMed1990

Normal left ventricular dimensions and function: interstudy reproducibility of measurements with cine MR imaging.

The authors evaluated the reproducibility of measurements of ventricular dimensions obtained with cine magnetic resonance (MR) imaging performed on two occasions in 11 healthy subjects. Two reviewers analyzed the studies in a blinded fashion to determine interobserver and interstudy variability of measurements of left ventricular (LV) mass, volume, ejection fraction, and systolic wall stress. LV mass showed good reproducibility between studies, with 3.6% and 3.8% variability for LV end-systolic mass for the two observers. LV end-diastolic volume varied by 5.2% and 3.9%, and LV end-systolic volume, by 9.7% and 0.9%. Variability for LV ejection fraction was 5.0% and 4.9%. The largest interstudy variability was end-systolic wall stress, 11.1% and 13.5%, which was due mostly to changes in arterial pressure between the two studies. It is concluded that anatomic and functional measurements from cine MR images are reproducible between studies. The small interstudy variability is likely related to the fact the measurements are derived directly from cine MR images that encompass the entire heart rather than depend on measurements of only sample images and the use of geometric models.

Adult↗
PubMed1989

The lesion of multiple sclerosis: imaging of acute and chronic stages.

Increased blood-brain barrier (BBB) permeability, important in the pathogenesis of MS, may be demonstrated as lesion enhancement with high-volume delayed CT (HVDCT). We studied 40 MS patients with history, neurologic examination, HVDCT, and MRI. In addition, 7 of the patients with enhancing CT lesions were followed with serial MRI for up to 3 years and 7 months. In 3 of these patients we repeated the HVDCT. Patients with enhancing lesions on CT were younger, had shorter duration of disease, and had more frequent clinical relapses than did patients without enhancement. More than half (56%) of the enhancing CT lesions were in the deep white matter, 23% were periventricular, and 21% were at the gray/white matter junction. Half the CT enhancing lesions, when followed by serial MRI, showed significant changes in lesion size. Although the majority (59%) of these lesions faded, some remained actively changing (25%) or became confluent with adjacent lesions (16%). In 48% of the MRI examinations that showed activity, some lesions were increasing in size while others were simultaneously decreasing in size. This study confirms that MS is a dynamic process in which recurrent episodes of BBB disruption and inflammation play a major role. Recurrent episodes of inflammation may well be a prelude to the largely irreversible changes of demyelination and gliosis.

Acute Disease↗
PubMed1987

Microencapsulated tumor assay: new short-term assay for in vivo evaluation of the effects of anticancer drugs on human tumor cell lines.

A new in vivo has been developed for evaluating the antitumor activity of chemotherapeutic drugs. The assay is based on a microencapsulation technology developed by Damon Biotech, Inc., Boston, MA, which makes it possible to encapsulate human tumor cells in small (about 1 mm in diameter) microcapsules with semipermeable membranes. Microcapsules containing human tumor cells were injected i.p. into nude or C57BL/6 mice and drugs were administered i.v. The microcapsules were recovered at various intervals following treatment and determinations of drug effects were made based on the differences in the number of tumor cells recovered from the treated and nontreated animals. Using this assay we found that (a) encapsulated tumor cells grew better in the in vivo system than in vitro under the conditions tested; (b) drugs crossed the capsular membrane and killed or inhibited the proliferation of tumor cells; and (c) the antitumor effect was consistent with the relative therapeutic efficacy of drugs or level of resistance of tumor cells detected by other in vitro or in vivo tests. The tumor microencapsulation assay offers several properties which make it attractive for use in new drug development: (a) the antitumor activity of drugs can be tested against human tumor cells under conditions which provide for three-dimensional growth and in vivo supply of nutrients; (b) the sensitivity of tumor cells can be assessed following exposure to drugs at concentrations which are achievable in vivo; (c) compounds requiring in vivo metabolic activation can be tested; (d) the effect of each drug injection can be quickly evaluated; (e) inhibition of tumor cell proliferation versus cytoreductive effects of drugs can be discriminated; (f) the test is applicable to virtually all histological types of human tumor cells; and (g) the tumor microencapsulation assay is a short-term, simple, and relatively inexpensive assay.

Animals↗
PubMed1987

Pulmonary lymphangitic spread of carcinoma: appearance on CT scans.

Chest computed tomography (CT), including high-resolution CT with thin (1.5-mm) sections was used to evaluate proved (pathologically or clinically) lymphangitic spread (LS) of tumor in 12 patients. These appearances were compared with thin-section scans obtained in 11 healthy subjects. Thin-section CT demonstrated findings consistent with thickening of the normal lung interstitium. In all patients, thin sections showed an increase in the number of peripheral lines (1-2 cm in length) that were diffuse in generalized disease and localized in focal disease. Normal peripheral arcades were not increased in number, but the limbs forming the arcades were thickened in all patients. A diffuse increase in linear and curvilinear structures (reticular pattern) was seen toward the center of the lung. Polygonal structures 1-2 cm in diameter were seen in seven patients with LS but not in healthy subjects. Fissures were thickened in nine patients. Selected 1.5-mm-thick CT sections are recommended through abnormal areas (seen at CT or on chest radiographs) or if these are normal at three levels (midapex, hilus, and 3 cm above the diaphragm) when scanning patients with tumors known to cause LS.

Adult↗
PubMed1987

Disappearing iliac vessels: an MR phase cancellation phenomenon.

Magnetic resonance images often fail to distinguish the iliac vessels on one side. Phantom studies and theoretical analysis demonstrated that this phenomenon arises from a loss of the flow void effect. At a certain angle, the additional phase accumulation that results from motion in the section-selection direction exactly cancels the additional phase accumulation from motion in the frequency-encoding direction. Thus, vessels that cut through the imaging plane near this critical angle have substantial signal intensity. This artifact can be eliminated by alternating the direction of the section-selection gradient on sequential phase encodings.

Humans↗
PubMed1987

Magnetic resonance imaging in pediatric vascular disease.

Magnetic resonance imaging (MRI) was used to study eight children with known vascular disease proved by angiography. Congenital and acquired large vessel disease was equally well demonstrated noninvasively by both MRI and angiography, and in one patient MRI provided superior information about pulmonary artery patency.

Adolescent↗
PubMed1986

Foot-and-mouth disease virus (FMDV) experimental infection: susceptibility and immune response of adult mice.

Adult mice are susceptible to foot-and-mouth disease virus (FMDV) infection only under some experimental conditions. This paper report the results of pathogenesis studies on 4 different strains of mice (CF1, C3H, NIH-nude, BALB-c/J) infected with the cloned and uncloned 0(1)C strain of FMDV. High virus titers were detected in blood and pancreas 12-24 h after infection (p.i.); these persisted for up to 48 h p.i. in CF1 and BALB-c/J mice and 72 h p.i. in the two other mouse strains. Virus titers observed in other organs were lower than those found in blood. In pancreas, and occasionally in salivary glands, oropharynx, heart and testicles, viral antigen was detected by direct immunofluorescent assay. Circulating neutralizing antibodies appeared in CF1 and C3H mice at 72 and 96 h p.i. respectively, and their titers remained unchanged during the 30-day experimental period. Antibodies against viral infection-associated antigen (VIA) were detected for a shorter period. In animals irradiated with 1 LD 50 (total body irradiation), viremia persisted up to 14 days p.i. and a low antibody response was observed which began at the end of viremia. No differences in the response of mice to cloned or uncloned FMDV were observed.

Animals↗
PubMed1986

Ductus arteriosus aneurysm in Marfan syndrome.

We report the angiographic and magnetic resonance imaging findings of an aneurysm of the ductus arteriosus in a woman with Marfan syndrome. This is the first reported ductus aneurysm diagnosed in an adult with Marfan syndrome.

Adult↗