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M Mahon

Publications and source records attributed to M Mahon.

36 records · Page 2Linked to original sources
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↗
PubMed1984

Needle biopsies.

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Biopsy, Needle↗
PubMed1984

Variability of histochemical and morphometric data from needle biopsy specimens of human quadriceps femoris muscle.

Duplicate needle biopsies from the lateral portion of quadriceps femoris muscle from 20 young, healthy males were investigated morphometrically and histochemically. Mean results showed both the size and occurrence of the three main fibre types present to be similar to values obtained from a survey of the literature. However, considerable variations in the proportions of fibre types (coefficients of variation 30-40%) and significant (P less than 0.001) differences in fibre size between individuals were common. Within individuals, comparisons of samples taken at a reference site in the right thigh with samples obtained from deeper, more proximal or contralateral sites also often showed significant differences in fibre size. These results suggest caution is necessary when interpreting apparent changes in such values derived from subsequent biopsies of individuals.

Adenosine Triphosphatases↗
PubMed1984

Histochemical fiber composition of lumbar back muscles in the rabbit.

The present study of the back muscles of the rabbit, using enzyme histochemical techniques and stereological methods, was undertaken with the view to gaining a better understanding of the fiber-type make-up of the lumbar musculature of this animal. The muscles considered were the multifidus, sacrospinalis and the intertransversarii between levels L5 and L6. Gross examination reveals that the multifidus and the sacrospinalis form the bulk of the lumbar musculature and that these muscles appear white. Between and deep to these two muscles are the red intertransversarii. Histochemically the multifidus and the sacrospinalis are also similar in their fiber-type composition, mostly types IIA and IIB and the percentage of connective tissue that they contain. The intertransversarii, in contrast, are for all practical purposes composed of only type-I fibers. The intertransversarii contain significantly more connective tissue than the other two muscles. It may be concluded that the bulk of the lumbar musculature of the rabbit is phasic while the intertransversarii, containing only type-I fibers and a high percentage of connective tissue, are postural muscles.

Adenosine Triphosphatases↗
PubMed1982

Early life undernutrition in rats. 1. Quantitative histology of skeletal muscles from underfed young and refed adult animals.

1. Male rats were undernourished either during the gestational and suckling periods or for a period of time immediately following weaning. Some rats were killed at the end of the period of undernutrition; others were nutritionally rehabilitated for lengthy periods of time before examination. Two muscles, the extensor digitorum longus (EDL) and soleus (SOL) were studied from each rat. Histochemically-stained transverse sections of these muscles were used to determine total number of fibres, the fibre cross-sectional areas and the relative frequency of the various fibre types. 2. All rats killed immediately following undernutrition showed significant deficits in body-weight, muscle weight and fibre cross-sectional area compared to age-matched controls. 3. Animals undernourished during gestation and suckling and then fed normally for 5 months showed persistent and significant deficits in body-weight, muscle weight, muscle weight and total fibre number. There were also significant deficits in mean fibre cross-sectional area of each fibre type except for red fibres in the EDL. No difference in the volume proportion of connective tissue was found. 4. Rats undernourished after weaning and then fed ad lib. for approximately 7 months had normal body-and muscle weights. Their muscles showed no significant differences in total fibre number, relative frequency of the various fibre types, fibre size or volume proportion of connective tissue. 5. These results indicate that, although the effects on rat skeletal muscle of a period of undernutrition after weaning can be rectified, undernutrition before weaning causes lasting deficits.

Age Factors↗
PubMed1982

Early life undernutrition in rats. 2. Some contractile properties of skeletal muscles from adult animals.

1. The contractile properties of soleus and extensor digitorum longus muscles from animals at 12 months of age whose mothers had been undernourished during pregnancy and lactation (PU rats) have been compared with those of muscles from ge-matched controls. 2. Body-weight and muscle wet weight of PU rats was significantly reduced. Muscle:body-weight values were, however, no different from controls. 3. No significant alterations in whole muscle speeds of contraction or relaxation could be detected when compared with those of age-matched controls. 4. Twitch and tetanic forces of both SOL and EDL were greater per unit weight of muscle in PU rats. Apart from SOL twitch these differences were significant. The tetanus:twitch values were, however, not different.

Age Factors↗
PubMedDate not supplied

An adult case of Andersen's disease--Type IV glycogenosis. A clinical, histochemical, ultrastructural and biochemical study.

A middle-aged man presented with a thirty-year history of progressive, asymmetrical limb-girdle weakness. The muscle biopsy revealed a vacuolar myopathy. The vacuoles which did not disrupt the fibre outline, lay in a subsarcolemmal position. They were PAS-positive and the material was partially resistant to diastase digestion. Electron microscopy showed the vacuoles to contain free unbound glycogen with filamentous material. Leucocyte brancher enzyme activity was normal but the muscle activity was less than half the control value. Histochemical and ultrastructural characteristics of the storage material resemble the amylopectin polysaccharide deposits seen in childhood Type IV glycogenosis.

Glycogen Storage Disease↗
PubMedDate not supplied

Quantitative histological changes in the small intestine of rats artificially reared on different milk substitutes.

Growth of the small intestine was studied in rats reared normally by their mothers (MR) or artificially reared (AR) by intragastric infusion of milk substitutes from postnatal day 5. Two milk substitutes were used: one high in carbohydrate and low in protein as compared with rats' milk (Messer) and the other closely resembling rats' milk in its composition (Auestad). Pups reared on these formulae are termed ARM and ARA, respectively. Pups were killed at 7, 12, and 20 days for quantitative histological measurements on transverse sections of duodenum and ileum. They included cross-sectional areas of muscle and of mucosa and submucosa combined (other tissue), internal and external perimeters, and length of longest villus profile. Artificial rearing affected mucosal and submucosal measures, but did not affect muscle. The effects depended on age, type of milk substitute, and site within the small intestine. There was a tendency for deficient growth of small intestine in the early stages of artificial rearing, especially in the ileum of ARA pups. Enhancement of growth as shown by cross-sectional area of mucosa and submucosa and by longest villus profile occurred later--by 12 days in the duodenum and by 20 days in the ileum of ARM pups. Enhanced growth was less evident in ARA rats, being apparent only in the duodenum, and not until 20 days were the cross-sectional area of mucosa and submucosa and the longest villus profile increased.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Muscle morphometry in motor neuron disease.

It has previously been suggested that the pathological abnormalities seen in muscle biopsies from patients with motor neuron disease (MND) are of predictive value in relation to the rate of progression of the disease. In this study, quadriceps muscle biopsies from 19 patients with MND and 20 age matched controls were prepared for histochemistry and analysed morphometrically. Pathological features of denervation and reinnervation were observed in all MND patients although considerable variation between patients was noted. Motor neuron disease biopsies also showed increased connective tissue, an increased variation in fibre size, and a random fibre type distribution. Several of these abnormalities were more severe in female patients. Many of these 'abnormalities' were also frequent, albeit to a milder degree, in control biopsies and emphasize the need for age matched controls. The morphometric data was not related to the age of the patient, disease duration, type of MND or muscle strength, thus suggesting that the progression and severity of MND and its prognosis cannot be judged on the basis of quadriceps muscle pathology alone.

Adult↗
PubMedDate not supplied

Sequential studies of a childhood myopathy: a clinical, histochemical and morphometric investigation.

An unusual inherited progressive distal myopathy of early childhood onset is described in two sisters from a consanguineous Asian family. Motor milestones were normal but gait deteriorated slowly thereafter with development of generalized hypotonia and muscle weakness particularly in the wrist extensors and hand muscles. Muscle biopsies obtained at the ages of 6 and 10 years respectively (Case 1) showed significant differences. At 6 years muscle morphology and histochemical appearance were normal although type I fibres predominated (79%) and a substantial pool of 'undifferentiated' fibres (12%) was present. By 10 years there was a significant reduction in type I fibres (-13%) and in 'undifferentiated' fibres (-10%) with a concomitant increase in type II fibres (+23%). Fibre size and shape were normal at the age of 6 years but no further fibre growth was evident 4 years later. The older sister (Case 2, age 13 years) was similarly affected. The possibility of this progressive myopathy being caused by loss of neural control at two separate stages of development is discussed. The importance of performing sequential morphometric studies of muscle biopsies from patients with unusual childhood myopathies is emphasized.

Adolescent↗