Biomedical subjects

E Waterfield

Publications and source records attributed to E Waterfield.

10 recordsLinked to original sources

PubMed1995

Accelerated myelopoietic recovery in irradiated mice treated with Photofrin.

The porphyrin photosensitizer, Photofrin porfimer sodium (Photofrin), has been widely studied for its capacity to evoke destruction of malignant tissues. In addition to its photosensitizing properties, Photofrin may exert myelostimulatory effects in normal and immunosuppressed mice in the absence of activating light. In the present set of experiments, we examined the effect of Photofrin upon the immunohematopoietic axis of sublethally irradiated DBA/2 mice. Administration of Photofrin (10 mg/kg) 1 and 4 days following irradiation (4 Gy) significantly enhanced the recovery of spleen cellularity, spleen and bone granulocyte/macrophage progenitors (colony-forming units, CFU-GM) and peripheral blood leukocytes levels. Proliferative responses to the T-cell mitogen concanavalin A by spleen cells prepared from Photofrin-treated mice were significantly less than those of cells from irradiated control mice 8 and 15 days post-irradiation. Photofrin given 1, 4 and 7 days following irradiation elevated splenic CFU-GM 3 to 4-fold 10 days post-irradiation relative to the irradiated controls and mice given only two injections of Photofrin. In contrast to the effect of two injections, multiple (three or four) injections of Photofrin did not elevate bone marrow CFU-GM above control levels beyond 8 days post-irradiation. In addition, splenic CFU-GM levels in animals receiving three or four injections of Photofrin were no different than those of the irradiated controls later than 10 days post-irradiation. These findings indicate that prolonged exposure to Photofrin in sublethally irradiated mice may induce regulatory factors which dampen the enhanced myelopoietic recovery stimulated by only two injections of the drug.

Animals↗

PubMed1993

Liposomal delivery of a photosensitizer, benzoporphyrin derivative monoacid ring A (BPD), to tumor tissue in a mouse tumor model.

Biodistribution studies were carried out on 14C-labeled benzoporphyrin derivative monoacid ring A (BPD), which had been formulated as a unilamellar liposome or taken from a stock solution in dimethyl sulfoxide diluted into phosphate-buffered saline immediately before intravenous injection into DBA/2 mice. By and large the general distribution of BPD to various organs and tissues was comparable for both formulations. It was noted, however, that liposomal material appeared to enter tissues more rapidly and to be cleared more rapidly, as demonstrated by shorter half-lives for a number of tissues including skin, lung and fat, and generally lower levels in most tissues 24 h following administration. Accumulation in tumor tissue was slightly higher with liposomal BPD, and clearance rates for this tissue were equivalent (half-lives 16.1 h for liposomal BPD and 16.9 h for aqueous BPD). When the two preparations were tested in a bioassay in tumor-bearing mice, photodynamic therapy (PDT) with liposomal BPD proved to be superior to the aqueous preparation when PDT was administered 3 h following intravenous administration of BPD. Plasma distribution studies in vitro demonstrated that 91.1 +/- 0.3% of the liposomal BPD distributed to the lipoprotein fraction within the first hour of mixing, whereas only 49.1 +/- 2.6% of nonliposomal BPD was associated with lipoprotein under the same conditions. Furthermore, while lipoprotein-associated liposomal BPD distributed evenly between all three types of lipoprotein (high, low and very low density), a majority of nonliposomal BPD associated with the high-density lipoprotein fraction.

Animals↗

PubMed1992

Photosensitizing efficiency of two regioisomers of the benzoporphyrin derivative monoacid ring A (BPD-MA).

Benzoporphyrin derivative, monoacid ring A (BPD-MA), currently in clinical trials as a photosensitizer for photodynamic therapy for cancer, consists of two regioisomers (A1 and A2) present in equal proportions. The contribution of the regioisomers to the overall photosensitizing potency of BPD-MA was tested in vitro and in vivo. The in vitro photosensitizing potencies of BPD-MA-A1 and -A2 were tested in a standard cytotoxicity assay using M1 (rhabdomyosarcoma of DBA/2 mice) tumor cells and were found to be equivalent. The in vivo photosensitizing efficacies of the regioisomers were tested in the M1 tumor model in DBA/2 mice and were also found to be equivalent. Biodistribution of the regioisomers in mouse plasma, tumor and liver was studied in M1 tumor-bearing DBA/2 mice at 15 min and 3 hr post intravenous injection of [14C]BPD-MA-A1/A2 at 4 mg/kg body weight. Plasma and extracts from tumor and liver were analysed by HPLC and tested for radioactivity. The two regioisomers were eliminated from plasma and liver at different rates, which resulted in A1:A2 ratios of 1:0.28 in plasma and 1:0.75 in liver at 3 hr post injection. The differential elimination was not observed to any significant degree in the tumor, where even at 3 hr post injection the A1:A2 ratio was 1:1.15. Therefore, we concluded that in tumor tissue, at 3 hr post injection, the time at which laser photodynamic therapy is carried out, both regioisomers were present in about equal proportions. Further, both regioisomers were fully active as determined by an in vitro cytotoxicity assay following extraction.

Animals↗

PubMed1991

Photosensitising potency of structural analogues of benzoporphyrin derivative (BPD) in a mouse tumour model.

The in vivo characteristics of four analogues of benzoporphyrin derivative (BPD) have been investigated. Biodistribution data obtained in DBA/2J mice with BPD-MA (monoacid ring A analogue) which had been tritiated or internally labelled with 14C showed that both labelled materials acted in an essentially identical manner during the period of study. Biodistribution and clearance studies showed that relative distribution in a variety of mouse tissues was similar for all BPD analogues. M1 tumour cells (rhabdomyosarcoma in DBA/2J mice) taken from tumours excised from animals treated 3 h earlier with BPD, and tested in vitro for photosensitivity provided evidence that significant levels of photosensitiser detected in tumour was both active and associated with tumour cells. The monoacid forms of BPD were found to be much more photodynamically active in this test than were the diacid analogues. The ability of the analogues to ablate tumours in mice by photodynamic therapy was also tested. Again, BPD-MA and BPD-MB proved to be measurably better than the diacid analogues. These findings are discussed in reference to structural and physical differences between the analogues.

Animals↗

PubMed1991

The effects of plasma lipoproteins on in vitro tumor cell killing and in vivo tumor photosensitization with benzoporphyrin derivative.

The influence of lipoprotein association on in vitro tumor cell killing and in vivo tumor photosensitization with benzoporphyrin derivative (BPD) has been investigated in M-1 tumor bearing mice. The association of benzoporphyrin mono acid ring A with either low or high density lipoprotein increased tumor cell killing in an in vivo/in vitro cytotoxicity assay performed 3 h post intravenous drug administration. Eight hours following photosensitizer injection only low density lipoprotein (LDL) mixtures produced significant (P less than or equal to 0.005) increases in tumor cell killing compared to BPD in unfractionated plasma. The efficacy of in vivo photosensitization in the presence of lipoproteins correlated with the in vivo/in vitro cytotoxicity. Association of BPD with low or high density lipoproteins resulted in delayed tumor regrowth and higher cure rates when light exposure (125J/cm2) was performed 3 h post drug administration. When light exposure was performed 8 h post-injection only LDL-BPD mixtures led to enhanced tumor eradication compared to BPD administered in aqueous solution or unfractionated plasma.

Animals↗

PubMed1991

Mouse skin photosensitization with benzoporphyrin derivatives and Photofrin: macroscopic and microscopic evaluation.

A comparative study, at both the macroscopic and microscopic level, of skin photosensitivity caused by four isomeric forms of benzoporphyrin derivative (BPD) has been carried out, and compared to effects of Photofrin. Animals injected intravenously with BPD analogues and exposed to light 3 h later showed extensive photosensitivity. Animals receiving the monoacid derivatives of BPD (BPD-MA and BPD-MB) showed markedly more photosensitivity than those receiving the diacid derivatives (BPD-DA and BPD-DB). Animals receiving BPD analogues which were exposed to light 24 h or more later showed only minimal reactivity. Histological examination of biopsies taken after photosensitizer injection and light exposure showed extensive changes in epidermis and dermis, including epidermal erosion, degranulation of the stratum granulosum, spongiosis, depletion in cellularity and mast cell degranulation. These changes were noted to be similar to changes caused by Photofrin.

Animals↗

PubMed1990

In vitro evaluation of phototoxic properties of four structurally related benzoporphyrin derivatives.

Four structural analogs of benzoporphyrin derivative (BPD) have been studied and compared for photosensitizing activity in vitro. All analogs have an identical reduced tetrapyrrol porphyrin ring, and differ by the position of a cyclohexadiene ring (fused at either ring A or ring B of the porphyrin) and the presence of either two acid groups or one acid and one ester group at rings C and D of the porphyrin. Photosensitizer activity was tested with the M1 tumor cell line using an assay (the MTT assay) which detects mitochondrial hydrogenases as a measure of cell viability. This assay was shown to be equivalent to the standard clonogenicity or [3H]thymidine uptake assay. Comparative studies with the BPD analogs showed that the monoacid derivatives had equivalent cytotoxicity and were about five-fold more active than the diacid forms. This was the case whether the assays were performed in the presence or absence of fetal calf serum.

Animals↗

PubMed1980

Restriction specificities, alloreactivity, and allotolerance expressed by T cells from nude mice reconstituted with H-2-compatible or -incompatible thymus grafts.

Congenitally thymusless nude mice that lacked functional T cells were reconstituted with H-2-compatible or -incompatible thymus grafts taken from either fetal, newborn, or adult mice and transplanted under the kidney capsule or subcutaneously. Transplantation with unirradiated fetal (15--17 d) or newborn thymus grafts reconstituted the nude mice as assessed by their subsequent generation of virus-specific cytotoxic T cells in vivo or alloreactive T cells in vitro. The restriction specificity of T cells from homozygous mice was exclusively for the nude host H-2, as shown by direct cytolysis or by cold target competitive inhibition assays. irrespective of whether nude mice were reconstituted with H-2-compatible, semiallogeneic, or H-2-incompatible, unirradiated newborn or fetal thymus grafts (in order of decreasing efficiency of reconstitution). The restriction specificity for the nonhost H-2 of the thymus could not be demonstrated even after primary or secondary sensitization in an infected appropriate F1 environment. These nude mice reconstituted with fetal or newborn grafts were tolerant to the H-2 of the thymus donors. Nude mice transplanted with irradiated adult thymus grafts were reconstituted functionally with syngeneic or semisyngeneic but not with allogeneic thymus grafts. In homozygous nu/nu irradiated heterozygous recipients of F1 thymus grafts, the restriction specificity for the nonhost thymic H-2 could not be elicited upon adoptive sensitization in irradiated and infected F1 heterozygote stimulator mice; in fact, these chimeras' lymphocytes were not tolerant to the nonhost H-2. The discrepancy between the restorative capacity of unirradiated vs. irradiated thymus grafts suggests that precursors of T cells in nude mice can acquire restriction specificity and immunocompetence independently of a conventional, functioning H-2-compatible thymus if exposed to an allogeneic fetal or a newborn thymus that contains functioning thymocytes of donor type but not if reconstituted with an irradiated adult allogeneic thymus.

Animals↗

PubMed1977

Characterization of human adenoid cells using surface and functional markers for lymphocyte subpopulations.

Adenoid lymphocytes from children undergoing adenoidectomy were compared with blood cells from the same children using techniques for identifying T cells and B cells. A high proportion of adenoid lymphocytes were immunoglobulin positive cells. Of these only a minor fraction carried receptors for the Fc part of IgG. Adenoid B lymphocytes respond poorly if at all to polyclonal B-cell activators, such as LPS or PPD, which show a different reactivity compared to human splenic cells. The response to anti B2-microglobulin was also different; blood cells responded better than adenoid cells. Thus distinct subpopulations of B lymphocytes reside in different lymphoid organs. The adenoid lymphocyte reactivity might reflect their function in the defence mechanism against infections.

Adenoids↗

PubMedDate not supplied

Lymphocyte activation by Con A.

Con A can activate cytotoxic effector cells, helper cells and suppressor cells. In all cases Con A activates polyclonally and thus the entire T cell repertoir can be revealed by Con A activation. Nylon purified T cells cannot be activated by Con A. however, in the presence of helper cells, such as adherent cells, or in the presence of serum from several species, Con A activates purified T cells. The serum factors that are responsible for Con A activation of purified T cells are present in the albumin fraction. It is suggested that Ia molecules may be responsible for the ability of Con A to activate purified T cells and a general hypothesis for T cell activation is outlined.

Albumins↗