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Biomedical subjects

H Campbell

Publications and source records attributed to H Campbell.

At least 145 records · Page 8Linked to original sources
PubMed1987

Atypical presentation of empyema of the gall bladder.

A case of empyema of the gall bladder complicated by liver abscesses is reported. The mode of presentation was atypical for both the empyema and the abscesses and computed tomography (CT) played a significant role in the diagnosis and management.

Cholecystitis↗
PubMed1987

Imported malaria in the UK: advice given by general practitioners to British residents travelling to malaria endemic areas.

General practitioners are in a key position to provide advice to those travelling to malaria endemic areas. A study of at-risk travellers revealed that 54% visited their general practitioner before their intended trip overseas and of these 79% were given advice about antimalarial precautions. Of those advised 98% carried antimalarial tablets with them on their trip but only 46% had any knowledge of other methods of personal protection against malaria. Fewer non-white than white British residents received information from their general practitioners.It is suggested that general practitioners should be better informed about current malaria transmission and currently recommended chemoprophylactic drugs and dosages. It is also suggested that the major public health priority should be to stimulate a greater involvement of non-health service agencies in order to make the public aware of the risk of malaria and seek medical advice before travel.

Adolescent↗
PubMed1986

Femoro-distal bypass for critical ischemia: is the use of prosthetic grafts justified?

The results of 240 femoro-distal bypass operations for critical ischemia have been reviewed. Autologous saphenous vein was the graft material in 112 cases (46.7%) and prosthetic grafts were used in the other 128 cases (53.3%). A distal arteriovenous shunt (AVS) was employed as an adjunct to 72 grafts (30%). The cumulative patency rate at 4 years was 53% for all of the grafts together and the cumulative limb salvage rate was 70%. When autologous saphenous vein was available the actual patency rate at one year after operation was 70% for popliteal grafts and 53% for tibial grafts. In the case of prosthetic grafts the equivalent patency rates were 51% and 35%. In view of the poor success rate of prosthetic grafts anastomosed to distal tibial vessels these procedures are of doubtful value in routine clinical practice.

Adult↗
PubMed1985

Epitope-specific regulation of the T cell repertoire: carrier recognition in association with I-E or I-A does not influence the restriction of hapten-specific T cells.

The T cell repertoire of BALB/c mice contains clones capable of recognizing p-azobenzenearsonate (ABA)-tyrosine (Tyr) in association with both I-A and I-E-encoded class II molecules. Immunization of BALB/c animals with ABA-GAT (terpolymer of L-Glu60-L-Ala30-L-Tyr10) or ABA-GLT (terpolymer of L-Glu51-L-Lys34-L-Tyr15) instead of ABA-Tyr reduces the secondary proliferative response to ABA-Tyr in vitro. Limiting dilution experiments indicate that this situation corresponds to the recruitment of fewer ABA-specific T cells in vivo. The same experiments, performed in A.TH mice, which are nonresponder to both GAT and GLT, demonstrate that the number of ABA-specific T cells stimulated in vivo with ABA conjugates depends on the Ir gene-controlled immunogenicity of the carrier rather than on the ABA epitope density on the immunogen. Although GAT is preferentially recognized in association with A, and GLT with E, ABA-GAT and ABA-GLT stimulate both A and E-restricted ABA T cells in vivo and in vitro. The ABA-Tyr-specific T cell repertoire is not qualitatively affected by the carrier. This demonstrates that the inhibition of hapten-specific T cell expression upon immunization with ABA conjugates does not result from a competition between hapten and carrier-specific T cells for epitope recognition in association with the same Ia molecule on antigen-presenting cells.

Animals↗
PubMed1985

Arterial steal phenomenon in femoro-tibial bypass with arterio-venous shunt.

Arterio-venous shunts are sometimes constructed at the distal anastomosis of femoro-tibial bypass grafts in order to increase blood flow velocity within the graft. However, the use of such a shunt may "steal' blood from an already ischaemic distal arterial bed. The aim of this study was to determine the conditions under which this might happen. Experiments were carried out on an in vitro model of the femoro-tibial bypass under steady flow conditions. The simple resistance model of Hyman and Brewer (J. Biomechanics 13, 469-675, 1980), modified to take into account the nonlinear pressure flow relationship through a stenosis, was used to interpret experimental data. Good agreement was obtained between measured and calculated steal.

Arterial Occlusive Diseases↗
PubMed1985

Debendox revisited.

Two further studies re-examine the findings by Golding et al. (1983) in Oxford that mothers of children born with oral clefts had been more frequently prescribed Debendox (Bendectin) than had the mothers of matched controls. In Cardiff, 86 283 total births between 1965 and 1979 included 139 infants with oral clefts. Detailed information was obtained about 93 of these infants and matched controls. The relative risk of the birth of an infant with an oral cleft to women prescribed Debendox within 69 days of the first day of their last menstrual period was 0.64 (95% confidence limits 0.12-3.34). No increased effect was found amongst women who smoked. In Aberdeen, 17 640 livebirths between 1976 and 1979 included 31 children with oral clefts. Compared with the non-exposed group the risk of a birth of an infant with an oral cleft to a woman prescribed Debendox in early pregnancy was 0.37 (95% confidence limits 0.09-1.47). These results do not confirm the previous findings in Oxford of a possible association between exposure to Debendox in early pregnancy and the occurrence of oral clefts in the child.

Abnormalities, Drug-Induced↗
PubMed1984

Experimental evaluation of arterial steal in in vitro models of femoro-tibial bypass with adjuvant arteriovenous shunt.

Arteriovenous shunts are now increasingly used with long femoro-tibial grafts in critical ischaemia of the lower limb. This might result in reduction in blood flow to an already compromised tibial artery, a condition known as arterial 'steal'. In vitro models of the femoro-tibial bypass with adjuvant arteriovenous shunt were investigated in terms of flow rate distribution. Results show that arterial steal will occur at high flow rates through the shunt only when a significant proximal stenosis is present. The degree of steal was independent of the configuration and size of the shunts studied. A simple resistance model was used to predict steal under various flow conditions. The clinical significance of the results is discussed.

Arteriovenous Shunt, Surgical↗
PubMed1984

Contact dermatitis from the epoxy resins tetraglycidyl-4,4'-methylene dianiline and o-diglycidyl phthalate in composite material.

An outbreak of dermatitis occurred in an aircraft factory using epoxy resin composite material. Of 25 operatives, 14 gave positive patch test reactions to the composite material and/or diglycidylether of bisphenol A (DGEBA), tetraglycidyl-4,4'-methylene dianiline (TGMDA), and o-diglycidyl phthalate. This report seems to be the first to demonstrate contact allergy to the two last mentioned epoxy resins. The diglycidylether of bisphenol A used in routine test series picked up only 3 cases of 12 tested.

Aniline Compounds↗
PubMed1984

Helper functions of antigen-induced specific and autoreactive T cell colonies.

Helper T cells have been distinguished on the basis of whether they provide carrier-specific or nonspecific helper functions. In previous experiments we determined that the predominant class of helper T cell in populations of primed lymph node cells is a nonspecific helper T cell unable to provide carrier-specific signals. Initial induction of nonspecific helper T cells in vitro requires restimulation with the immunogen. This suggested that such T cells may express antigen-specific receptors. In this case they would constitute a unique subpopulation distinct from T cells with identical antigen-specificity that are able to provide carrier-specific help. Alternatively, the requirement for antigen restimulation might reflect a role for antigen-specific T cells in the recruitment of T cells with unrelated specificity. To distinguish between these possibilities we have characterized the specificity and function of helper T cell colonies selected from primed lymph node cells. We report here isolation of autoreactive as well as antigen-specific helper T cells. All antigen-specific T cell colonies provide carrier-specific help in the presence of the homologous hapten-carrier conjugate. Only autoreactive T cells are limited to providing nonspecific helper function. Although selection of autoreactive T cells is initially dependent on antigen restimulation in vitro, activation of an established autoreactive T cell line requires restimulation with MHC-syngeneic spleen cells but does not require restimulation with either the immunogen or fetal calf serum. These results suggest that nonspecific helper T cells induced in the course of a normal immune response to randomly chosen foreign antigens are autoreactive. Such T cells may serve to enhance proliferation and maturation to immunoglobulin secretion of B cells activated by limiting numbers of carrier-specific helper T cells. The demonstration of large numbers of precursors to MHC-specific autoreactive T cells in antigen-primed populations raises important issues concerning regulation of the expansion of autoreactive T cells in vivo.

Animals↗
PubMed1983

Adjuvant distal arteriovenous shunt with femorotibial bypass for critical ischaemia.

In a series of 59 femorotibial bypass operations for critical ischaemia an arteriovenous (A-V) shunt was constructed at the distal anastomosis in 36 patients whose pedal angiograms showed an occlusion in the primary pedal arch. Mean blood flow recorded in the grafts without the shunt in the patients whose primary pedal arch was occluded was 83.6 +/- 9.9 ml/min (mean +/- s.e.m.) compared with 152 +/- 16.2 ml/min in those patients whose primary pedal arch was intact (P less than 0.01). This increased to 236 +/- 20.5 ml/min with the shunt open (P less than 0.001). Twelve months after operation the cumulative patency rate for grafts with an A-V shunt was 46.5 per cent compared with 40.5 per cent for grafts in the better risk patients with a patent primary pedal arch who did not receive a shunt. No side effects were observed due to the presence of a shunt. The importance of the primary pedal arch and the rationale of adjuvant distal arteriovenous shunt are discussed. The results indicate that the addition of an arteriovenous shunt at the distal anastomosis of a long femorotibial bypass is of benefit when blood flow through the graft is limited by occlusive disease in the pedal arteries.

Aged↗
PubMed1983

Iodide enhances IgG synthesis by human peripheral blood lymphocytes in vitro.

Several studies have suggested that iodide may increase thyroiditis and autoantibody synthesis. We have investigated the effect of iodide in vitro at physiologically relevant concentrations on immunoglobulin synthesis by normal human peripheral blood lymphocytes stimulated with pokeweed mitogen. Both the number of cells which synthesised IgG and the amount of IgG released into the culture supernatant increased significantly after culture in a medium with added iodide compared to a medium with added chloride. No effect of increasing concentrations of the added iodide from 10(-3) mM to 10 mM was observed. These findings suggest that iodides may have a role in enhancing antibody synthesis which may be important when programmes of iodide supplementation are introduced into areas which are deficient.

Adult↗