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Biomedical subjects

A M MacLeod

Publications and source records attributed to A M MacLeod.

At least 109 records · Page 6Linked to original sources
PubMed1988

Intraoral mucosal reconstruction with microvascular free jejunal autografts: an experimental study.

This experimental study investigated the problem of covering bare bone adequately in the oral cavity to provide a stable, functionally acceptable reconstruction. In eight dogs, intraoral mucosal defects were created whilst preserving the mandibular arch. The defects were reconstructed with a microvascular jejunal patch. Six animals had their reconstructions stressed postoperatively by the administration of irradiation and by feeding solid food. Two control dogs did not receive irradiation. Grafts were assessed clinically and histologically for 6 months. Rapid mucosal healing occurred in seven of eight dogs. The grafts conformed well to the mandibular contour and were tolerant of postoperative radiotherapy and the chewing of solid food. Structural integrity of seven grafts was maintained although subtotal villous atrophy occurred in irradiated grafts and to a lesser extent in control grafts. In one animal whose graft mucosa sloughed, the wound was re-epithelialized from the adjacent buccal mucosa. Microvascular jejunal patches therefore provided a durable, functionally adequate reconstruction of the mouth floor.

Animals↗
PubMed1988

Reconstruction of mandibular defects with metallic prostheses and microvascular jejunal autografts: an experimental study.

A study was undertaken to determine the adequacy of vascularised jejunum to provide stable mucosal cover over a non-biological mandibular substitute. Employing a canine model, composite intra-oral bone-mucosal defects were created and reconstructed with a metal plate covered by a microvascular jejunal patch. These were followed for six months and were assessed clinically, histologically and radiologically. Rapid mucosal healing occurred in all cases. The autografts conformed to the contour of the prosthesis and adequate tongue mobility was preserved. All mandibles remained stable throughout the follow-up period. Histologically, short villi covered the jejunal grafts to three months whilst at six months both normal and abnormal jejunal mucosal morphology was evident.

Animals↗
PubMed1988

Renal transplantation: HLA-linked, non-cytotoxic antibodies develop after blood transfusion.

1. A previously untransfused dialysis patient was given blood from a single donor on three occasions and sera were obtained from the recipient before and after transfusion. 2. The sera were tested against B-lymphocytes from the blood donor and his family in the erythrocyte-antibody rosette inhibition assay to determine whether any Fc-receptor-blocking activity which developed was HLA linked. 3. Antibody activity was noted after the second transfusion and was directed toward B-lymphocytes from the blood donor and his family members sharing the haplotype HLA A11, B12 with him. 4. These antibodies were removed by the absorption of active sera with lymphocytes from the blood donor but not from (a) his sibling who shared no HLA antigens with him or (b) the transfusion recipient. Absorption of the active sera with platelets from the blood donor did not remove activity. 5. These results indicate that Fc-receptor-blocking antibodies developing after blood transfusion are directed to HLA-linked antigens on donor lymphocytes.

Absorption↗
PubMed1988

Anastomosis of vessels of unequal diameter using an interpositional vein graft.

In this study, 100 rabbits were used to assess the efficacy of five different methods of microvascular anastomosis where a vessel diameter discrepancy of 5:1 existed. The inferior vena cava of the rabbit was used as a graft in the femoral artery. In 50 percent of the rabbits the graft was reversed to assess the effects on flow. When explored between 7 and 10 days after anastomosis, an overall patency rate of 96 percent was recorded. Three grafts were not patent in the reversed group and one was not patent in the nonreversed group. There was no significant statistical difference in patency rates between any of the groups, as calculated by the Fisher's exact probability test. The tapered end-to-end and side-to-end anastomoses were found to be the most rapid and simplest methods to perform.

Anastomosis, Surgical↗
PubMed1988

Antiidiotypic activity in sera from sensitised potential transplant recipients.

Antiidiotypic activity was determined in non-cytotoxic sera from highly sensitised dialysis patients who previously possessed broad-spectrum lymphocytotoxic antibodies. At least four non-cytotoxic sera from six transfused patients were tested in the short antiidiotypic antibody assay against lymphocytes known to be lysed by cytotoxic sera from the same patient. Of 87 sera/cell combinations studied, antiidiotypic activity was detected in 42 (48%). Antiidiotypic activity was present in IgG fractions and F(ab')2 fragments of two active sera. These results indicate that non-cytotoxic sera from patients who were once highly sensitised possess antiidiotypic activity. Fluctuating levels of lymphocytotoxic antibodies frequently encountered in sera from dialysis patients may be explained at least in part by the development of antiidiotypic antibodies.

Adolescent↗
PubMed1987

The free radial forearm flap with and without bone for closure of large palatal fistulae.

Three cases of palatal fistulae closed by microvascular transfer of radial forearm flaps are presented. Vascularised bone was included in one flap and all operations were free of complications. Facial scarring is minimal and the secondary deformity in the arm has not been significant. It is suggested that this procedure presents fewer difficulties than other techniques for treating the large palatal fistula and may prevent the collapse of the alveolar arch which follows the scarring associated with closure by local tissue.

Adolescent↗
PubMed1987

Intraluminal pH measurement to monitor the vascular perfusion of free jejunal autografts: an experimental study.

An evaluation of the effect of ischaemia upon the intraluminal pH of microvascular free jejunal autografts was undertaken with a view to developing a monitoring system to be used clinically. Employing a canine model, the intraluminal pH of isolated jejunal segments was measured during normal perfusion and under conditions of arterial and venous occlusion. Ischaemia induced a rapid, easily measured fall in intraluminal pH reversible after 1 h of normothermic ischaemia. The most rapid pH change occurred within the first 10 min. It is felt that continuous intraluminal pH measurement may form a reliable method of monitoring the postoperative vascular perfusion of clinical free jejunal transfers.

Animals↗
PubMed1987

Non-cytotoxic antibodies in chronic lymphocytic leukaemia.

Non-cytotoxic Fc receptor blocking antibodies against autologous B lymphocytes were sought in sera from patients with chronic lymphocytic leukaemia (CLL), using a rosette inhibition assay. They were found in 11 of 52 (21%) of patients with CLL, but were not associated with previous blood transfusion or pregnancy, suggesting that they were unlikely to have resulted from allogeneic stimulation. Fc receptor blockade was more commonly detected in sera from patients with stage B rather than stage A CLL (Binet classification), though this did not achieve significance beyond the 90% level, and it was noted in 62.5% of those with lymphocyte doubling times of less than one year, compared with 36.3% of those whose lymphocyte doubling time was more than one year. The results indicate that autologous Fc receptor blocking antibody activity occurs in sera from patients with CLL, is more likely to be generated by the tumour itself than by allogeneic stimulation, and is associated with increased tumour load. Such antibodies may permit tolerance of tumour by the host.

Autoantibodies↗
PubMed1986

Functional evaluation of the hand and foot after one-stage toe-to-hand transfer.

Twenty toe-to-hand transfers in 17 patients with an average follow-up of 54 months have been reviewed to quantify hand function and donor morbidity. Eleven toe-to-thumb and nine toe-to-finger procedures were performed. Surgical and follow-up data were available for all patients. Twelve patients (14 procedures) were reviewed in detail, with particular attention given to foot and hand function. Total active motion after toe-to-thumb transfer was 48 degrees and 106 degrees after toe-to-finger transfer. Two-point discrimination was less than or equal to 15 mm in 13 digits (65%). Grip and pinch power were related to the number of digits present on the reconstructed hand and to the presence or absence of functioning thenar muscles. Eleven of 12 patients can walk and run normally (mean of 5 years after surgery). Six (50%) cannot wear thongs or heavy boots, but all can wear normal shoes. The transferred great toe decreased in volume by an average of 10% over the years since the operation. Transferred toes became useful digits in the hand, and foot morbidity was minor and not progressive.

Adolescent↗
PubMed1986

Maternal antibodies to paternal B-lymphocytes in normal and abnormal pregnancy.

Sera were obtained prior to conception and during the first trimester of subsequent pregnancies from 22 women over 27 pregnancies; on 15 occasions these pregnancies ended in spontaneous abortion, whereas the remaining 12 achieved live normal babies. In only one pregnancy ending in abortion could antibodies directed to paternal B-lymphocytes determined by the EA rosette inhibition (EAI) assay be detected in the mother's serum, whereas five of the 12 successful pregnancies were associated with such detectable antibodies. Cytotoxic antibodies were also found in all but one of these EAI-positive pregnancies and no antibody activity was present in sera obtained from five primigravidae. These results indicated that normal, but not abnormal, pregnancies were often associated with blocking antibody formation, suggesting that such antibodies may protect the fetus from abortion. However, the failure to detect antibody activity in sera from first trimester primigravidae argues against a central role for blocking antibody, alone, in the maintenance of outbred pregnancy.

Abortion, Spontaneous↗
PubMed1986

Differential expression of trophoblast lymphocyte cross-reactive (TLX) antigens on T and B lymphocytes.

Heterologous sera raised to human trophoblast (TLX antisera) have been shown to recognize peripheral blood lymphocytes (PBL); in unrelated studies noncytotoxic Fc receptors blocking B lymphocyte antibodies have been found in the sera of women during normal pregnancies. This study aimed to determine whether (a) there was any relation between Fc receptor blocking and cytotoxic anti-TLX activity in ten TLX sera and (b) different reactivity patterns arose when ten TLX antisera were tested in the cytotoxicity assay against separated T and B lymphocytes. Independent factor analysis showed four antisera with T lymphocytotoxicity patterns giving a loading high on one mathematical factor and low on a second. Three sera shared the opposite pattern and three were intermediate. The groups were similar but more discrete than those obtained when PBL were used as targets. Patterns of B lymphocytoxicity were dissimilar from T and both differed from the erythrocyte antibody rosette inhibition activity. Activity did not correlate with the HLA-A, -B, or -DR types carried by the panel cells. These data indicate that TLX antisera contain antibodies directly cytotoxic to antigens differentially expressed on T and B lymphocytes and that noncytotoxic Fc receptor blocking antibodies are not associated with any TLX groupings.

Animals↗
PubMed1986

Identification of HLA-linked antigens by pregnancy-associated non-cytotoxic alloantisera.

Non-cytotoxic sera obtained from post-partum primiparous and multiparous women were examined by a rosette inhibition technique for the presence of antibodies mediating blockade of human B lymphocyte Fc receptors. Selective activity was demonstrated against a panel of normal human B lymphocytes and lymphocytes from patients with chronic lymphocytic leukaemia (CLL). A pattern of specific activity was found in sera and in their IgG fractions, which was not accounted for by antibodies directed to known HLA-A, -B or -DR antigens. Several sera were identified with selective activity in this assay. As the results of testing sera in a direct binding assay correlated with those of the EA inhibition assay, and since EA inhibitory activity occurred in F(ab')2 fractions of sera, it is possible that these non-cytotoxic antibodies bind directly to B cell surface antigens. Sera may therefore have been identified which possess antibodies to hitherto undefined HLA antigens.

Antibodies↗