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Biomedical subjects

A G Weddell

Publications and source records attributed to A G Weddell.

At least 19 recordsLinked to original sources
PubMed1985

Long term effects of cryosurgery on cutaneous sensation.

In a study of the time course and nature of the sensory loss after cryosurgery the forearms of nine normal subjects were treated with liquid nitrogen using freeze times currently employed in clinical practice in Britain. Ability to appreciate touch, pinprick, and cold in the treated areas was tested at regular intervals and biopsy samples taken to investigate the pathogenesis. Appreciation of all three modalities of sensation was initially reduced in all nine subjects for all freeze times, yet complete recovery occurred in the seven patients completing follow up. This recovery, however, took up to one and a half years for the longest freeze, with even a 10 second freeze taking up to 10 months. Patients may be reassured that sensory loss after cryosurgery for up to two periods of 30 seconds will almost certainly recover, though it may take up to 18 months to do so.

Adult↗
PubMed1984

A morphometric study of intrafascicular vessels of mammalian sciatic nerve.

Intrafascicular vessel profiles were measured with a Quantimet image analyzer in 1-micron transverse sections of sciatic nerves of rats and compared with those of ("white") skeletal muscle. Blood vessels occupy the same percentage of the total tissue area in nerve and muscle tissues. The nerve, however, has much larger capillaries (about 1.7 X) spaced farther apart (about 2.5 X). Comparison of 3 1/2 month with 1-year-old rats showed that muscle capillaries increased in diameter (slightly, but significantly) at maturity, but those of the nerve decreased (also significantly). Vascular percentages of total tissue areas did not change. Nerve and muscle samples from monkey, rabbit, mouse, and cat show that the same striking pattern of large, widely spaced vessels distinguishes the nerve from other tissues. Minor interspecies variations exist. The nerve may contain as much blood as the muscle but its angioarchitecture suggests a lower exchange capacity.

Age Factors↗
PubMed1984

A descriptive study of the blood vessels of the sciatic nerve in the rat, man and other mammals.

The gross blood supply and internal vascular organization of the sciatic nerve in the rat (and other mammals including man) have been studied by injection, dissection, and microradiographic methods, in thick sections stained for alkaline phosphatase and semithin sections, and by electron microscopy. In the rat, an anastomotic vascular connection from the arteria comitans to the medial femoral circumflex artery is illustrated. In all species studied, the microvascular network of the nerve has an unusually large calibre and wide spacing, particularly when compared with that of skeletal muscle. Arterioles and venules are present within fascicles; the arterioles are thin-walled, with only rudimentary internal elastic laminae. Endoneurial capillaries are large, continuous and nonfenestrated, with prominent (often multiple) basal laminae and an unusually complete pericyte investment. Endothelial junctions appear to vary in type; not all are tight. Pinocytosis is common. The extensively interconnected vascular network of the nerve fascicle may act as an adaptable in situ reservoir for blood in the precise maintenance of the endoneurial milieu.

Alkaline Phosphatase↗
PubMed1978

A quantitative study of peripheral nerve fibres in the mouse following the administration of drugs. 1. Age changes in untreated CBA mice from 3 to 21 months of age.

This study is concerned with the quantification of changes which occur in peripheral nerves of normal mice from the onset of maturity to old age. The parameters chosen were total fibre area and axon area. Size distributions of these were expressed in the form of histograms. From the area data notional fibre and axon diameters were calculated, together with the thickness of the myelin sheath. The notional diameters were contrasted with the comparable myelin sheath thickness in the form of scatter diagrams. These results are intended to provide a reference scale for subsequent assessment of changes induced by drugs administered throughout life. The are in general accord with previous observations, but were obtained quickly, and with less margins of error, by using a Quantimet 720.

Aging↗
PubMed1975

The testis in mice infected with Mycobacterium leprae.

Following inoculation either locally or intravenously with Mycobact. leprae of human origin, the histopathology and bacteriology of the testis in experimental mice is described. Normal mice, and mice rendered immunologically deficient by thymectomy and whole-body irradiation, were studied. Attention is drawn to a heavy bacillation of the testis in mice from both groups. Bacilli were found in and beneath the tunica albuginea, but mainly in interstitial cells and in macrophages surrounding the tubules. The percentage of solidly staining bacilli was high, and globi were frequent. The study showed that the testis in mice is particularly favourable for the lodgement and multiplication of Mycobact. laprae following either local or intravenous inoculation. The significance of this in relation to the metabolism of the leprosy bacillus and to the frequent occurrence of testicular damage in the lepromatous male patient is discussed. This work was supported by grants to A. G. M. Weddell and A. C. McDougall from the Medical Research Council and the British Leprosy Relief Association (LEPRA).

Animals↗
PubMed1975

The histopathology of lepromatous leprosy in the nose.

On the basis of clinical, histological and bacteriological assessments, 31 patients in Central India were selected and classified as having active but early lepromatous leprosy and 4 patients as having early borderline leprosy. From the nose of each patient an average of 4 biopsies were taken from particular sites of the septum and turbinates either by punch biopsy or dissection with a scalpel. The nasal tissues from all the lepromatous patients contained many acid-fast bacilli; no bacilli or abnormalities were seen in nasal tissues from the borderline patients. The histopathology of these highly bacilliferous tissues is described. Bacilli were universally seen in macrophages, but they were also seen in blood monocytes and polymorphs, fibroblasts, squamous and pseudo-columnar epithelium, keratin, peri- and endo-neurial cells of tiny nerve bundles, erectile tissue, vascular plain muscle, perivascular histiocytes and frequently and abundantly in the cytoplasm of endothelial lining cells of lymphatics and of small blood vessels and free within the lumina of these vessels. Five basic mechanisms of escape of bacilli from the submucosa on to the surface, and thus into the external environment, are described. Secondary infection, in the presence of an expansile lepromatous infiltrate, together with simple trauma to the surface epithelium, are the main factors in the discharge of bacilli. These histopathological observations are consistent with the findings from other recent studies on the nose in leprosy regarding (1) the large numbers of morphologically intact and viable Myco. leprae excreted in the nasal mucus of lepromatous patients; (2) the clinical changes observed in the nose of such patients, and (3) the similar nasal involvement and excretion of Myco. leprae from the nose of mice inoculated with leprosy bacilli of human origin. Of particular interest was the frequency and intensity of bacilli within the endothelial lining cells of small blood and lymph vessels and the presence of bacilli free within the lumina of these vessels or within monocytes and polymorphs. The possible dynamic significance of these observations in the pathogenesis of leprosy is discussed. The significance of all these observations in relation to (1) the spread of leprosy; (2) local factors in the nose which might favour the growth of Myco. leprae, and (3) the nose as a portal of entry, are discussed.

Biopsy↗
PubMed1975

The penetration of dapsone, rifampicin, isoniazid and pyrazinamide into peripheral nerves.

1 Dapsone, rifampicin, isoniazid and pyrazinamide were shown to penetrate readily into the sciatic nerves of the dog and sheep. 2 These findings suggest that the continued persistence of viable drug-sensitive leprosy bacilli in the peripheral nerves of patients treated for long periods with either dapsone or rifampicin is not due to inadequate intraneural drug penetration.

Animals↗
PubMed1975

The behaviour of the nasal mucosa towards blood borne colloidal carbon in experimental animals.

A single dose of 8-16 mg of carbon C11/1431a was injected intravenously into rats, guinea-pigs, mice, goats and two pigs. Examination with the naked eye, dissecting microscope, light microscope and electron microscope of tissues from these animals sacrificed minutes, hours, weeks and up to 23 months after the injection revealed phogocytosis of most of the infected carbon by the professional phagocytes of the reticuloendothelial system (RES). However, in the non-RES sites carbon was trapped in significant amounts in the endothelial cells, the interendothelial spaces, pericytes and perivascular macrophages of the subepithelial capillaries and venules in the anterior nasal mucosa. The catchment area often showed partially fenestrated capillaries and redundant porous basement membrane around the venules. The leakage of carbon through these vessels was through these vessels was thought to be caused partly by the unusual porosity of the vascular walls and partly due to vascular stasis induced by constant loss of heat to the inspired air stream in post-natal life. The importance of these findings in the predilective localization of several granulomatous diseases and various forms of vasculitis in the nasal mucosa id discussed.

Animals↗