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Biomedical subjects

D T Rowlands

Publications and source records attributed to D T Rowlands.

At least 37 records · Page 2Linked to original sources
PubMed1977

Studies of the modified venous allograft.

Segments of rat inferior vena cava were modified by proteolytic digestion and dialdehyde starch tanning in an attempt to alter their antigenic nature and increase their tensile strength. These tissues were found to retain their ability to sensitize allogeneic recipients in both the intradermal and intra-aortic positions in all 50 experimental animals. Furthermore, these grafts had a very high aneurysm formation (100%), and aneurysm rupture (54%) rate even in isogeneic recipients, suggesting that the modification procedure so damages the structural integrity of venous tissue that its use in clinical situations may have disastrous consequences. Histologic evidence of intimal thickening, elastic disruption, and often severe acute and chronic inflammation supported the gross evidence of mechanical and immunologic damage and suggests that a mild brief course of immunosuppression may be indicated in clinical trials in situation in which autogenous saphenous vein in unavailable. Although the use of prosthetic mesh support for the graft may help to avoid structural changes, the introduction of synthetic materials may offset the theoretical advantages of the venous tissue.

Aldehydes↗
PubMed1977

Levamisole: anthelmintic activity in calves following dermal application.

A series of seven experiments designed to evaluate the anthelmintic efficacy of levamisole (1-tetramisole) by dermal application is described. This work involved use of 181 artificially infested calves. The drug was formulated at a concentration of 10% m/v levamisole base in a solvent system promoting dermal absorption and was applied to both sides of the spine in the lumber region at a dose rate of 10 mg levamisole base per kg livemass. A consistent performance was achieved in these investigations, the results from all of which were based upon necropsy findings. Efficacy of treatment was assessed against the third and fourth larval stages and fifth stage larvae/adult worms of six nematode species; the respective efficacies obtained were Haemonchus placei 72,0%; 99,3%; and 100%: Ostertagia ostertagi 85,5%; 38,1% and 74,5%: Cooperia spp. 98,9%; 99,9% and 100%: Bunostomum phlebotomum 83,0%; 100% and 98,5%: Oesophagostomum radiatum 47,4%; 94,9% and 99,6% and Dictyocaulus viviparus 79,5%; 94,1%; 90.9% (fifth stage larvae) and 93,8% (adult worms). The anthelmintic efficacy of levamisole in these experiments is of the same order as that achieved by orthodox methods of administration at dose rates between 7,5 and 10,0 mg levamisole HC1 per kg livemass. These findings add a new dimension to the use of levamisole and to anthelmintic therapy in general.

Administration, Topical↗
PubMed1977

Tubulointerstitial nephritis and glomerulonephritis in Brown-Norway rats immunized with heterologous glomerular basement membrane.

Tubulointerstitial nephritis and glomerulonephritis were produced in Brown-Norway rats (BN) by a single immunization with 2 mg of lyophilized bovine glomerular basement membrane. Tubulointerstitial nephritis was evident before glomerulonephritis. Antibody first bound to tubular basement membranes (TBM), and then the renal cortex was infiltrated with inflammatory cells. The TBM was split, and many renal tubules, especially proximal tubules, were destroyed. Approximately 14 days after the beginning of the tubular phase, antibody was observed to be bound to glomerular basement membranes (GBM) in linear fashion. There was epithelial and mesangial cell proliferation, splitting and reduplication of GBM, crescent formation, and glomerular scarring and atrophy.

Animals↗
PubMed1976

Humoral immune responses in Rana catesbiana frogs and tadpoles.

Rana catesbiana adult frogs and tadpoles were immunized with the bacteriophage F2, 0X-174, and T4 and the haptens 2,4 dinitrophenyl (DNP) and fluorescein (FTC). The haptens were conjugated with bovine serum albumin (BSA), bovine gamma globulin (BGG), or horsehoe crab hemocyanin (Hycn). Sera were obtained from immunized animals at invervals up to six months after immunization. The antibody activities were measured by bacteriophage neutralization techniques. Sucrose density gradients were used to separate the antibody classes. Both adults and tadpoles responded to each of the antigens tested. High molecular weight antibodies were predominant in both groups of animals. Low molecular weight antibody activity was not found in adults until nine weeks post immunization but, thereafter, this fraction increased throughout the immune response. Low molecular weight antibodies could also be identified in serum of tadpoles, but only under certain conditions.

Animals↗
PubMed1976

Antibodies to T cells in sarcoidosis.

Antibodies to a proportion of T lymphocytes were detected in the sera of 9 of 15 patients with sarcoidosis. Patients were studied within one year of tissue diagnosis, none were taking steroids, and all had hilar adenopathy with pulmonary infiltrates (Stage II). Antibodies were identified by three assays using a panel of T cells purified (greater than or equal to 90%) from the peripheral blood of healthy donors by the nylon column technique. Nine of fifteen sarcoid inhibited the capacity of normal T cells to adhere to sheep red blood cells (E rosettes) with an average reduction of 33% (range 21-46%) from control values. Antibodies to T cells were also identified using the indirect immunofluorescent method; 7 of 15 sera contained antibodies (IgM and IgG) to a portion of T cells (mean 36%, range 24-52%). Four of these sera were also cytotoxic to a fraction (18-31%) of T cells when incubated (15 degrees, 90 min) in the presence of rabbit complement. The antibodies to T cells identified in the sera of sarcoid patients may account for some of the immunological abnormalities found in this disease.

Animals↗
PubMed1976

Lymphocyte subpopulations in sarcoidosis: correlation with disease aetivity and duration.

We studied lymphocytes from the peripheral blood of 29 sarcoid patients to relate T- and B-cell populations with disease activity and duration. In patients with acute (less than 1 year) and chronic (greater than or equal to 9 years) active disease, the absolute lymphocyte count was reduced; the absolute number of T cells was reduced; and the proliferative response of lymphocytes to phytohemagglutinin was depressed compared with control subjects. Ten of 21 patients with active disease had 5% to 32% atypical lymphocytes. The proportion of cells bearing surface immunoglobulin (Ig) was increased in patients with active disease, but the absolute number of cells bearing surface Ig did not differ significantly from controls. However, studies using overnight in-vitro culture indicated that a large fraction of these cells bound exogenous Ig. The number of cells indentified by complement receptors was significantly reduced in patients with active disease. In contrast, patients who had complete reasolution of their disease showed no significant differences from controls in either T- or B-cell populations or in the proliferative response of their lymphocytes to phytohemagglutinin.

Acute Disease↗
PubMed1976

The antigenicity of venous allografts.

Segments of rat inferior vena cava modified by proteolytic digestion and dialdehyde starch tanning were found to retain their ability to sensitize allogeneic recipients both in the intradermal and intra-aortic positions. Furthermore, these grafts had a very high aneurysm formation (100%) and aneurysm rupture rate (63%), even when used as isografts, suggesting that the modification procedure so damages the structural integrity of the grafts that use in clinical situations may have disastrous consequences. Clinical trials must be undertaken with great caution and a mild, brief course of immunosuppression may be indicated when modified venous allografts are contemplated in potential organ transplant recipients. Furthermore, prosthetic mesh may be required for support whenever modified allogeneic veins are used for arterial substitutes. In the absence of autologous tissue, the bovine xenograft is probably the material of choice for reconstruction or bypass of small vessels.

Animals↗
PubMed1975

Persistent lymphocytosis with chromosomal evidence of malignancy.

An inappropriate, sustained and absolute lymphocytosis in a young man was investigated using technics which attempted to define the more detailed features of these cells and their T and B subpopulations. The results of the tests for lymphocyte RFC (E) and complement (EAC) rosette formation, immunofluorescence, in vitro phytohemagglutin (PHA) stimulation and 14C-cyclo-phosphamide binding assays, when evaluated in a combined and interrelated fashion, indicated that the lymphocytosis was mainly but not solely, due to an absolute elevation in circulating T lymphocytes. Moreover, an aneuploid cell line with 47 chromosomes, presumably T cells, also was detected in PHA-stimulated cultures. These data, associated with the patient's anemia, lymphocyte-infiltrated bone marrow, hepatosplenomegaly, pharyngeal lymphoid tumor and the clonal proliferation of lymphocytes bearing an abnormal karyotype, furnish evidence that the lymphocytosis is more than an unremitting leukemoid reaction and is potentially neoplastic. The detection of the chromosomal abnormality at this patient's age and point in disease may make him especially unique in that he could be a clinical prototype for other patients with lymphoreticular tumors which remain undetected at their onset.

Adult↗
PubMed1975

Immunocompetent cells from the lower respiratory tract of normal human lungs.

Subpopulations of lymphocytes in the broncho-alveolar air spaces of normal human lungs were compared with those in peripheral blood. Bone marrow-derived (bursal-equivalent) cells (B cells) were identified by complement receptors (EAC rosettes) and by surface immunoglobulin. Thymus-derived lymphocytes (T cells) were identified by their proliferative response to mitogens and the E rosette technique. Cells in lung air spaces were recovered from eight healthy nonsmoking volunteers by segmental lavage with the flexible bronchofiberscope. On the average, macrophages constituted 78% and lymphocytes 17% of the cells in the aspirates. B cells detected by surface immunoglobulin and complement receptors equaled 22% and 15% of lung lymphocytes, respectively. The distribution of lung B cells into heavy chain immunoglobulin classes revealed IgM and IgG to be the predominant classes, with mean values of 14.5% and 9.3%, respectively; the corresponding value for IgA was 5%. A comparable order of frequency (IgM greater than IgG greater than IgA) was observed for purified peripheral blood lymphocytes in the same and other control subjects. T cells comprised the majority (47%) of identifiable lung lymphocytes by the E rosette method. The presence of lung T cells was also corroborated by their proliferative response to mitogens (phytohemagglutinin and concanavallin A), but the response was less than that of equal numbers of peripheral blood lymphocytes from the same subjects. The B/T cell ratio for lung lymphocytes was comparable to results with peripheral blood lymphocytes in the same subjects, but a higher proportion of lung lymphocytes could not be identified as either T or B cells. It is postulated that lung lymphocytes participate in the local immune defenses of the lung.

Adult↗