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Biomedical subjects

M Mahon

Publications and source records attributed to M Mahon.

At least 19 recordsLinked to original sources
PubMed1997

Production of consistent crush lesions of murine skeletal muscle in vivo using an electromechanical device.

The crush model of injury in skeletal muscle is widely used in the investigation of tissue degeneration and regeneration. Previously, such trauma has been induced by using forceps to crush the muscle, commonly applying sufficient pressure to bring the mid-arms of the forceps together. This report introduces a reliable electromechanical device designed to generate reproducible focal lesions in skeletal muscle of mice. The tibialis anterior was crushed in 17 young adult mice. Two days after injury, the muscles were examined microscopically. By morphometric analysis, it was determined that the volumes of the lesions produced were similar (mean 0.499 mm3 +/- 0.098, range 0.278 - 0.601 mm3), and that the full extent of the damaged muscle was easily distinguished and readily quantifiable. This will allow a more precise comparison in future investigations into regenerative differences between age groups, satellite cell activation and the inflammatory response.

Animals↗
PubMed1996

Influence of LDL oxidation on the proliferation of human breast cancer cells.

The effects of lipid peroxidation and the antioxidant vitamin E contained in LDL isolated from control plasma (LDL--) and from plasma preincubated with 0.5 mmol/ml alpha-tocopherol (LDL+) on the proliferation of estrogen-receptor positive (ER+ : ZR-75, T-47-D, MCF-7) and negative (ER--: HBL-100, MDA-MB-231) human breast cancer cells were studied. Human skin fibroblasts served as controls. Incubation of plasma with 0.5 mmol/ml alpha-tocopherol resulted in a 3-fold increase of its content and a significant reduction in lipid hydroperoxides and conjugated dienes in LDL. Incubation of fibroblasts or ER+ tumor cells with LDL- or LDL+ had an effect on neither cell proliferation nor on the cellular levels of peroxidation products as compared to control incubations in the absence of LDL. In ER- cells, however, LDL+ stimulated the proliferation, whereas LDL- yielded a cytotoxic effect. Moreover, LDL- supplementation resulted in an increase in the content of hydroperoxides and conjugated dienes. LDL+ supplemented cells exhibited hydroperoxide levels in these tumor cells comparable to the basal levels measured in the absence of LDL. Our data suggested that peroxidation products in LDL are cytotoxic to estrogen-receptor negative breast tumor cells and vitamin E counteracts this effect.

Breast Neoplasms↗
PubMed1996

Evaluation of the E2L toy test as a screening procedure in clinical practice.

Early identification of hearing loss in young children is essential in order to avoid the potentially disabling effects of deafness. This necessitates effective screening measures with proven positive predictive value (McCormick 1977, 1988; Mahon et al., 1993). Previous studies (Marcuson et al., 1988; Bellman and Marcuson, 1991) have indicated that the E2L Toy Test, designed as a word discrimination test for evaluating the hearing of children who have English as a second language (E2L), could be such a measure. The results of diagnostic audiological testing, including the E2L test, are reported in 264 children. Comparison of E2L results with audiometric testing shows the E2L test to have a sensitivity of 87% and specificity of 90% in identifying children with an average hearing threshold of greater than 25 dB HL (and 78% sensitivity: 94% specificity where the average hearing threshold level is above 20 dB HL). This is the case for both E2L children and for children whose first language is English, suggesting that the E2L Toy Test would be useful in hearing screening test batteries throughout the UK. The results of screening hearing using the E2L Toy Test in 500 children aged 2-7 years from a wide geographical area in the UK are also presented.

Audiometry, Pure-Tone↗
PubMed1995

Dual-channel laser scanning microscopy for the identification and quantification of proliferating skeletal muscle satellite cells following synergist ablation.

Proliferating skeletal muscle satellite cells are the source of additional myonuclei which allow skeletal muscle to grow and regenerate. Previously, proliferating satellite cells were identified in situ by techniques which were limited either by tissue processing time or inability to observe complete muscle sections, or by errors made in separating these cells from proliferating nonmyogenic cells. To overcome these problems a new method has been devised for the identification and quantification of proliferating satellite cells in situ by light microscopy. The technique involves dual-channel laser scanning imaging of whole muscle sections for the localisation of both the muscle fibre basal lamina and the cell division marker bromodeoxyuridine. Using this technique satellite cell proliferation was quantified in mouse limb muscle following synergist ablation. Dual-channel laser scanning microscopy allowed precise localisation of proliferating satellite cells in the experimental model and, after 4 d, synergist ablation was shown to have produced significant satellite cell proliferation when compared with contralateral and sham-operated controls.

Animals↗
PubMed1994

Measuring quality of life in hospice patients using a newly developed Hospice Quality of Life Index.

The purpose of this study was to evaluate the validity and reliability of the newly developed Hospice Quality of Life Index (HQLI). Sixty-eight patient/caregiver dyads from one hospice were asked to fill out the HQLI on admission and after 3 weeks of hospice care. Hospice experts evaluated the items on the tool to assess content validity. The content validity index (0.83) and the alpha coefficients (r = 0.87 and 0.83) supported the validity and reliability of the HQLI. Item analysis revealed items with which patients were most satisfied and aspects of quality of life that were considered to be most important.

Adult↗
PubMed1994

Mid dermal elastolysis: case report and review of the literature.

A new case of typical mid dermal elastolysis was studied with electron microscopy. Elastic fibers were irregularly branched or lumpy, but subcomponents of these fibers were often normal. In some fibers, loose assembly of skeleton fibrils and aggregation of dense substances were observed. Phagocytosis of normal and abnormal elastic fibers by dermal macrophages was observed.

Adult↗
PubMed1994

The impact of hospice services on the quality of life of primary caregivers.

PURPOSE/OBJECTIVES: To evaluate the effects of hospice services on the quality of life of primary caregivers and to evaluate the validity and reliability of a new tool. DESIGN: Exploratory, descriptive. SETTING: A nonprofit hospice in Florida; clients are cared for primarily in the home. SAMPLE: 68 adult primary caregivers of 68 patients with cancer enrolled in hospice care and 62 noncaregiving adults. METHODS: Subjects were recruited on admission to hospice and completed the Caregiver Quality of Life Index (CQLI) and the Hospice Quality of Life Index (HQLI) on admission and during week four of hospice care. MAIN RESEARCH VARIABLES: Caregivers' assessment of their own physical, social, financial, and emotional quality of life; patients' assessment of their physical, psychological, spiritual, social, and financial well-being. FINDINGS: No significant differences were found in caregiver quality-of-life scores from admission to week four, and no correlations existed between quality-of-life scores and age or education. A significant positive correlation was found between the caregivers' quality of life and their estimate of the patients' quality of life. Evidence exists that the CQLI is valid and reliable. CONCLUSIONS: Caregivers of terminally ill people with cancer can maintain their quality of life during the first month of hospice care. The caregiver's perception of the patient's quality of life may affect the caregiver's quality of life. IMPLICATIONS FOR NURSING PRACTICE: When offering support to primary caregivers, the hospice team should include the four domains (physical, emotional, social, and financial) and should focus on the interrelatedness of the patient's and caregiver's quality of life.

Adult↗
PubMed1994

A study of quality of life of hospice patients on admission and at week 3.

The purpose of this study was to evaluate the patient's quality of life as perceived by the patient and primary caregiver at admission and after hospice services had been implemented. The sample consisted of newly admitted patients and their primary caregivers. Thirty-one patient/caregiver dyads were included in the study. The patient's quality of life was assessed using the Sendera Quality of Life Index (SQLI), a 25-item visual analogue scale. Total scores may range from 0 to 100. The SQLI was administered to both patients and caregivers at admission and at week 3 after hospice services were implemented. Although there was no significant difference in the patients' mean scores from admission to week 3 (45.2 to 45.7), 50% of patients did report an improvement in quality of life over the 3-week period. Caregivers reported a significant increase in the patient's quality of life from admission to week 3 (means 47 to 53). The correlations between patient and caregiver scores for admission (r = 0.45) and week 3 (r = 0.39) were moderate. Results show that hospice services may have a positive influence on some aspects of quality of life for some persons who are near death. Further research is needed to explore variables that are most influenced by hospice services.

Activities of Daily Living↗
PubMed1990

Histomorphometric and histopathological study of the human cricopharyngeus muscle: in health and in motor neuron disease.

Abnormalities in muscle histology have been reported frequently for the cricopharyngeus muscle of patients with oculopharyngeal muscular dystrophy, motor neuron disease and other neurological disorders in which dysphagia is a common clinical sign. However, there are few detailed reports of the normal structure of this muscle nor quantitative baseline data with which to compare the diseased state. In this study, cricopharyngeus muscles from 21 healthy individuals and four patients with motor neuron disease underwent quantitative histological and histochemical examination. In addition to the extensive connective tissue content (40%), comprising abundant elastic fibres, cricopharyngeus muscles from normal individuals possessed small calibre striated muscle fibres (mean narrow diameter 30 microns) of widely varying size (coefficient of variation 41%). The majority of fibres were histochemically type I (82%) and highly oxidative. All muscles comprised numerous muscle fibres with aberrant histological and histochemical features (internalized nuclei, 'ragged red' crescents, splits, degenerating fibres, 'moth-eaten' fibres, or nemaline rods.) The histomorphometric and histopathological features were similar in males and females and some showed a correlation with age. There were increases in fibre size and roundedness and decreases in the numerical density and percentage of type I and split fibres in the specimens from older individuals. Cricopharyngeus muscles from patients with motor neuron disease were not significantly different from the controls for most parameters. It is therefore suggested that previous descriptions of specific cricopharyngeal pathology accompanying neuromuscular disease or dysphagia be interpreted with caution. The importance of obtaining normal structural, morphometric and histopathological data from muscles other than the usually biopsied limb muscles, is emphasized.

Adult↗
PubMed1990

Morphological variations of the human vastus lateralis muscle.

Variations in the gross morphology of quadriceps femoris were assessed in 40 cadavers. An additional (fifth) head was present in about one third of the limbs. Distally, fusion between vastus lateralis and vastus intermedius varied from almost complete fusion to less than one third of the interface between the muscles. Discrete tendinous laminae arising from vastus lateralis were present in 29% of the limbs. In half the cadavers there were differences in quadriceps topography on right and left sides but there were no significant differences between muscles from male and female subjects. These findings may have important implications in clinical and microscopic studies of the quadriceps muscle.

Aged↗
PubMed1989

Familial thrombocytopenia and myopathy.

We report a family in which a combination of myopathy and thrombocytopenia is transmitted as an autosomal dominant characteristic through three generations. The myopathy has unusual histological features with type II fibre atrophy and vacuolation while the thrombocytopenia appears to be due to a defect in megakaryocyte maturation, platelet morphology and function being normal. The haematological findings in such a family have not been described previously.

Adult↗
PubMed1989

An unusual familial muscle disorder.

Autosomal dominant inheritance of an unusual muscle disease is reported in a family. The pathological appearance, of regularly arranged markedly atrophic muscle fibres without other evidence of disturbed innervation, are similar in each case. However, the onset of the disease, its distribution and its progression has varied within the family.

Adolescent↗
PubMed1988

Familial myopathy associated with thrombocytopenia: a clinical and histomorphometric study.

We describe an unusual vacuolar myopathy with tubular aggregates in a mother and son from a family presenting with a slowly progressive, predominantly limb girdle, weakness and distal upper limb weakness in association with reduced blood clotting ability. To our knowledge this is the first report of a familial clinical defect of both muscle and platelets in the same individuals. The possibility that the primary defect may be due to an abnormality of the tubular intramembranous systems in muscle cells and platelet precursors is discussed.

Adolescent↗
PubMed1988

Changes in jejunal permeability and passive permeation of sugars in intestinal biopsies in coeliac disease and Crohn's disease.

1. The relative effects of changes in mucosal surface area and mucosal permeability on the passive uptakes of mannitol and raffinose have been studied in vitro using jejunal biopsies from 48 controls, 32 patients with coeliac disease and 11 patients with Crohn's disease. Total mucosal permeation was corrected for surface area measured morphometrically to provide an index of mucosal permeability. 2. In untreated coeliac disease, permeation of mannitol was reduced by 35% (P = 0.006) and that of raffinose was increased by 66% (P = 0.0095) compared with controls, whereas mucosal permeability to mannitol was increased twofold (P = 0.009) and to raffinose fivefold (P = 0.0001). Mucosal permeability was similar for each sugar. 3. In treated coeliac disease, permeation and permeability for mannitol were normal, but remained elevated for raffinose by 23% (P = 0.036) and 41% (P = 0.024), respectively. 4. In Crohn's disease, permeation of mannitol was reduced by 21%, but that of raffinose and mucosal permeability to both sugars were normal. 5. These findings suggest that surface area is quantitatively more important than mucosal permeability in determining the total permeation of mannitol, while the converse is true for raffinose. The findings are compatible with paracellular uptake of raffinose, but with both paracellular and transcellular uptake of mannitol. Both pathways are affected in coeliac disease, whereas only transcellular uptake is affected in Crohn's disease.

Adolescent↗
PubMed1988

A histological and histochemical study of the cricopharyngeus muscle in man.

The human cricopharyngeus muscle was investigated by dissection and by histological, histochemical and morphometric methods. Muscle fibres in the cricopharyngeus were found to be similar in appearance to those of the lateral part of the quadriceps femoris, although they were generally much smaller and more variable in size. The endomysial connective tissue was markedly increased in the cricopharyngeus and muscle spindles were not found. Certain features normally considered to be pathological were also noted in the cricopharyngeus muscles. The fibre type population consisted mainly of histochemically 'slow-twitch' richly oxidative fibres. This finding is consistent with the proposed function of this muscle in its sphincteric role in deglutition, vomiting, eructation and in the control of aerophagia.

Adenosine Triphosphatases↗
PubMed1987

A histological and histochemical study of the cricopharyngeus muscle in the guinea-pig.

Histological, histochemical and morphometric methods were used to investigate the cricopharyngeus muscle in the guinea-pig and to compare it with the extensor digitorum longus and soleus muscles. The cricopharyngeus comprised uniformly small diameter fibres otherwise similar in appearance to those found in skeletal limb muscles. Several fibre type profiles were distinguished within the cricopharyngeus, all of which had homogeneously high oxidative activity, whilst the majority were histochemically fast (Type II). Muscle spindles were not observed in the cricopharyngeus muscles. Compared to the surrounding musculature the cricopharyngeus has a higher oxidative activity and may thus be suitably adapted for the maintenance of tonic contraction, forming a part of the upper oesophageal sphincter.

Adenosine Triphosphatases↗