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Biomedical subjects

A J Davies

Publications and source records attributed to A J Davies.

At least 19 recordsLinked to original sources
PubMed1979

Fibrinolytic activity of tissue surfaces during surgery.

A non-invasive method has been developed for the study of tissue surface fibrinolytic activity during surgery in man. Surface exudate was collected using a filter-paper disc which was then applied directly to a fibrin plate or used to prepare a euglobulin fraction. The method detected the intraoperative increase in fibrinolytic activity. At 45 minutes from the start of surgery the increase in lytic activity for tissues was four to eight times greater than that of venous blood taken simultaneously. The technique may be used to compare regional differences in tissue fibrinolysis, to determine the effect of excess local fibrinolysis on postoperative bleeding, and to study the relation between low fibrinolytic activity and postoperative adhesion formation.

Exudates and Transudates↗
PubMed1979

Studies on hyperlymphoid mice.

Injection of syngeneic, but chromosomally distinguishable, lymph node or spleen cells into adult mice resulted in both T- and B-lymphocyte chimaerism. In spleen-injected mice haematopoietic chimaerism was also established. It appeared that the donor T lymphocytes were added to the host recirculating T-cell pool so that a hyperlymphoid state was produced. The percentage of donor T lymphocytes declined very slowly in normal mice, but remained stable in adult-thymectomized animals. There was no evidence of a homeostatic mechanism involving destruction of excess peripheral T lymphocytes or grossly affecting the flow of T lymphocytes from the thymus into the recirculating T-cell pool. A preliminary model of the T-lymphocyte system is proposed.

Animals↗
PubMed1979

Adult and pre-adult thymectomy of mice: contrasting effects on immune responsiveness, and on numbers of mitogen-responsive and Thy-1+ lymphocytes.

Peripheral lymphoid tissues of mice which have been thymectomized at 2 or 4 weeks of age, that is, before they achieve adult body weight, have been shown to be lacking in cells responsive to the T-cell mitogen, phytohaemagglutinin, when the animals became adult, and these mice have also been shown to have a deficient immune response against sheep erythrocytes. It is suggested these effects of pre-adult thymectomy are consequent upon removal of the prime source of T cells prior to the animal having acquired complete T-cell populations of the adult. Spleens and lymph nodes of mice thymectomized at 8 weeks of age were found to have reduced numbers of cells susceptible to the cytotoxic effects of anti-Thy-1 serum as early as 4 weeks after the operation, whereas the number of lymphocytes responsive to T-cell mitogens in these lymphoid tissues was not reduced at this time. The number of spleen-borne antibody-producing cells in a primary or secondary response was not affected by 8-week thymectomy, either when the response was tested in the operated animal, or after transfer of cells from such an animal to an irradiated recipient. The results are discussed with respect to other work on the effects of thymectomy of mice during the post-neonatal and pre-adult period.

Age Factors↗
PubMed1979

Hapten specific unresponsiveness in mice. I. Characteristics of unresponsiveness induced by 2,4,6-trinitrobenzene sulphonic acid.

Injection of mice with the chemically reactive hapten 2,4,6-trinitrobenzene sulphonic acid (TNBSA) induces a specific unresponsiveness as judged by reduction or abolition of the anti-TNP response to TNP-KLH. The normal response to a nonrelated hapten, oxazolone, bound to the same carrier (OX-KLH) is unaffected. Reduction of the anti-TNP response was also observed after TNBSA treatment, in nude mice (nu/nu) and their littermates (nu/+) challenged with TNP-POL, an antigen to which the response is thymus independent. Injection of the chemically non-reactive hapten TNP-glycyl-glycine did not induce unresponsiveness. A similar failure was observed with TNP autologous red cells or serum proteins from mice previously injected with TNBSA. The specific unresponsiveness of spleen cells of TNBSA injected mice was maintained after their transfer into lethally irradiated syngeneic host mice. Finally tolerant cells do not inhibit specifically an adoptive anti-TNP secondary response.

Animals↗
PubMed1978

Very early abortion by prostaglandins.

309 women whose menstruation was delayed by 3-35 days were treated with intrauterine or vaginal prostaglandins. Of 275 confirmed pregnancies, 229 were successfully terminated without further abortifacient therapy. A successful outcome was often associated with episodes of vomiting, diarrhoea, and uterine cramps in the 24 hours after prostaglandin administration, but the incidence was related to prostaglandin dosage and gastrointestinal side-effects were more common after vaginal administration. The best results were achieved by the analogue 16:16 dimethyl P.G.E2 as a vaginal pessary. 14 patients (6.1%) required uterine curettage for escessive or prolonged bleeding, while 2 patients required blood transfusion. One patient, who had an intrauterine contraceptive device left in situ during treatment, developed acute pelvic sepsis. No deleterious side-effects occurred in 34 patients who were subsequently proven not to be pregnant at the time of treatment. Treatment by intrauterine or vaginal prostaglandins offers promise as a method of pregnancy termination which avoids much of the physical and emotional trauma associated with surgical termination, and has the advantage of not requiring hospital admission in the majority of cases. The present study shows the safety of the method, and its potential as a self-administration technique.

Abortifacient Agents, Nonsteroidal↗
PubMed1978

Growth of human gliomas in immune-deficient mice: a possible model for pre-clinical therapy studies.

Thirteen gliomas from 55 neurosurgical specimens, derived from 25 adults and 30 children, have been successfully grown as subcutaneous xenografts in immune-deprived or nude mice. Only 2 of the 30 paediatric specimens implanted (6.7%), a medulloblastoma and an astrocytoma Grade III, have grown compared with 11 of the 25 adult specimen (44%) which were mostly astrocytomas Grade III. Tumour growth usually occurred several months after implantation, and karyotypic analysis confirmed their human origin in all cases. The histopathology of xenografted tumours correlated with the original surgical material, both after initial implantation and when tumours had been passaged several times. Observations on tumour growth in various types of immune-deprived mice indicated that, within certain limits, the immunological competence of the host mouse did not relate to take rates of primary implants, but could affect the take rate of passaged tumours.

Animals↗
PubMed1978

Coccidian parasites of intertidal fishes from Wales: systematics, development, and cytochemistry.

Examination of littoral fish Blennius pholis and Cottus bubalis caught at Aberystwyth and Porth Cwyfan, Wales, U.K. revealed 2 species of coccidia. Eimeria dingleyi sp. n. Oocysts spherical (16.1-19.2) to subspherical (13.9-14.2 X 18.8-20.0) micron, with thin walls; sporulation outside the host to produce ellipsoid sporocysts; endogenous phases in epithelial cells throughout intestine; 26 of 58 B. pholis infected. Eimeria variabilis (Théohan) Reichenow. Oocysts spherical (11.9-14.6) to subspherical (9.2-10.9 X 13.9-14.3) micron, sporulation in lining of pyloric ceca and rectum; previously unrecorded schizonts and gametocytes present; 21 of 25 C. bubalis infected. Electron microscopy revealed that the oocyst wall of E. variabilis consists of a thin membrane whereas the sporocyst wall is thick and 3-layered. Typical oocyst wall-forming bodies were absent from the macrogamete. Cytochemical tests on the endogenous stages of E. dingleyi and E. variabilis indicated that in general they resembled other coccidia in their chemical constitution.

Animals↗
PubMed1978

Studies of hyperthymic mice. I. The influence of multiple thymus grafts on the size of the peripheral T cell pool and immunological performance.

Following the implantation of syngeneic chromosomally marked thymuses under the kidney capsule of normal adult mice, donor T cells were found in the blood and other lymphoid organs. The mice were found to have increased numbers of Thy.1-positive cells in spleen and lymph nodes, increased peripheral blood lymphocyte levels and also augmented immune responses to sheep erythrocytes. The contribution made by an individual graft to the donor T cell pool was independent of the number of thymuses grafted as was the growth of the grafts themselves. The results reaffirm that there is no homeostatic feedback control of thymus growth in adult mice.

Animals↗
PubMed1978

Studies of hyperthymic mice. II. The influence of thymus grafts on cell flow through the peripheral T-cell pool.

In normal CBA/H mice implanted under the kidney capsule with eight CBA/H.T6T6 neonatal thymus lobes it was observed that the percentage of marked thymus-graft derived T cells in the periphery, after building up to a peak, showed a biphasic exponential decline. The initial decline was very rapid and appeared to be due to loss of the thymus-graft derived cells from the system. The later decline was slower and was the same as that of an introduced cohort of lymph-node lymphocytes. The second rate of decline was, however, considerably more rapid than that of lymph-node cohort in non thymus-grafted mice. We conclude that in multiply thymus-grafted mice the flow of cells through the T-cell pool is more rapid than in normal mice and that in this sense the thymus can be thought to drive the lymphoid system.

Animals↗
PubMed1978

The immunological response of CBA mice to P. yoelii. II. The passive transfer of immunity with serum and cells.

CBA mice infected with the malaria parasite Plasmodium berghei yoelii (P. yoelii) develop a self-resolving infection lasting 15-18 days; on recovery from a primary infection they are immune to further infection. Cell and serum transfers from immune to non-immune mice were used to analyse the mechanism of resistance. Whereas serum from mice which had recovered from a single infection was ineffective in transferring immunity, hyperimmune serum (from mice repeatedly challenged with P. yoelii) protected against challenge inocula of 10(4) and 5 X 10(4) but was ineffective against higher inocula (10(5)). Doses of serum which completely protected intact mice were ineffective when administered to T-cell deprived recipients. The injection of spleen cells from recovered mice conferred immunity on both normal and T cell deprived mice. Pretreatment of immune cell donors with cyclophosphamide reduce the ability of spleen cells to transfer immunity. Treatment of the immune cells with an anti-Thy 1 antiserum and complement in vitro did not abrogate their protective effect. The significance of these results is discussed in relation to the effector mechanisms which might operate in murine malaria.

Animals↗
PubMed1977

Clinical significance and prognostic value of the T-B immunological classification of human primary acute lymphoid leukaemias.

50 cases of primary acute lymphoid leukaemia (A.L.L.) were analysed for the presence of T and B membrane markers on bone-marrow and/or peripheral-blood cells. 26% of cases were predominantly T-cell in type, 4% were B, the remaining 70%, without detectable membrane markers, were classified as "null" cell A.L.L. Of particular interest is the correlation between this immunological classification and the prognosis, since T-cell and B-cell A.L.L. were associated with a poorer prognosis than null-cell A.L.L. in terms of both median length of first complete remission and median survival. With one exception the T-cell cases were, according to the W.H.O. classification, of either the prolymphocytic or macrolymphoblastic type of A.L.L. and were more extensive than the comparable null-cell A.L.L. In contrast, cases of the W.H.O. prolymphoblastic and microlymphoblastic types were all found to be null-cell A.L.L. and were associated with the worst and best prognosis respectively. The correlation found between the immunological classification of A.L.L. and the prognosis means that patients with a poor prognosis can be selected for more intensive therapy.

Adolescent↗