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Biomedical subjects

J V Moore

Publications and source records attributed to J V Moore.

At least 73 records · Page 4Linked to original sources
PubMed1989

The photodynamic effects of photofrin II, hematoporphyrin derivative, hematoporphyrin, and tetrasodium-mesotetra(4-sulfonatophenyl)porphine in vitro: clonogenic cell survival and drug uptake studies.

The human colon adenocarcinoma cell line, WiDr, was exposed to Photofrin II, hematoporphyrin derivative (HPD), hematoporphyrin (HP) or tetrasodium-meso-tetra(4-sulfonatophyenyl)porphine (TPPS4) followed by irradiation with light. Clonogenicity was determined and the resultant survival curves compared and shown to be qualitatively similar in shape. However, for equal amounts of drug in the medium, there were large differences in photosensitizing efficiency with Photofrin II approximately 5, 25 and 50 fold more effective than HPD, HP and TTPS4, respectively. For the same power used, all drugs were less efficient photosensitizers under red light (600-1100 nm) than under white light (300-110 nm). For all drugs this could be explained in terms of changes in light absorption over the two wavelength ranges. Differences in clonogenic cell survival could not be explained in terms of differences in singlet oxygen production (from published values). A reduction in drug uptake into the cells was sufficient to explain the differences between Photofrin II, HPD and HP, while TPPS4 was 5-fold less effective compared to other drugs than would be expected from drug uptake measurements. Two methods for measuring drug uptake were compared and shown to give different results for Photofrin II. Measurements of drug fluorescence in 0.1 N NaOH yielded 5-fold lower values than when measurements were in 1 N HCl following heat treatment to monomerise aggregated drug. Clearly the reliability of the method used in determining drug uptake must be carefully ascertained.

Adenocarcinoma↗
PubMed1989

Flow cytometric analysis of intracellular hematoporphyrin derivative in human tumor cells and multicellular spheroids.

Flow cytometry (FCM) has been used to investigate the intracellular fluorescence of hematoporphyrin derivative (HPD) in monolayer and spheroid cultures of WiDr cells. For exponentially-growing monolayer cultures mean cellular fluorescence was directly proportion to the external HPD levels in the range 5-100 micrograms ml-1 (r = 0.99). Heterogeneity of cellular fluorescence was quantified by determining the ratio of the fluorescence value below which were observed values for 98% of the cell population compared to the fluorescence value for 2%. In exponentially-growing cultures, decreasing levels of HPD in the medium led to an increase in the 98:2% ratio, i.e. an increase in heterogeneity of intracellular drug levels. The growth of cells as multicellular spheroids confers a spheroid-size-dependent resistance to photodynamic treatment. With increasing spheroid size (100, 250, 500, 750 and 1000 microns diam.) there was a decrease in mean intracellular HPD levels and a large linear increase in the 98:2% ratio (r = 0.94).

Adenocarcinoma↗
PubMed1989

The response of murine intestinal crypts to short-range promethium-147 beta irradiation: deductions concerning clonogenic cell numbers and positions.

An exteriorized loop of mouse intestine was exposed to 147Pm low-energy electrons, where the dose rate decreased by a factor of 5 from the base of the crypt to the top of the proliferative zone. A crypt survival curve was obtained, expressed in terms of exposure time. The shape of the curve was interpreted in terms of survival parameters for colony-forming cells (clonogens) derived using 137Cs gamma rays and the depth-dose curve measured for 147Pm electrons. It is concluded that the shape of the crypt survival curve using 147Pm electrons is inconsistent with the notion of either the presence of a large number of clonogens or a small number near the top of the proliferative zone. A computer fitting procedure showed that the best agreement between predicted and observed curves was achieved with 2.7 +/- 0.5 clonogens at cell position 5.6 +/- 0.6, in the putative stem-cell zone.

Animals↗
PubMed1988

Vascular function and the probability of skin necrosis after photodynamic therapy: an experimental study.

The clearance of an intradermally-injected solution of 133Xenon in 0.9% saline has been used to study the impairment and recovery of blood flow in mouse tail for 5 days following photodynamic therapy (PDT) with 2mg TPPS i.v. per mouse and a range of doses of white light. Impairment of blood flow was observed within 10 min of light exposure. Blood flow increased between day 1 and day 5 at light doses less than 151J cm-2 and had returned to control levels by day 5 at light doses less than 129J cm-2. In mice treated with a light dose that caused a 50% incidence of necrosis, there was no significant difference in the initial xenon clearance half-time (measured at 10 min and 1 day after PDT) between those mice which developed tail necrosis and those which healed. However, the latter showed significantly greater improvement in vascular function on days 2, 3 and 4. This suggests that the timing and extent of recovery of blood flow determined the risk of necrosis in individual mice.

Animals↗
PubMed1988

The effect of fractionation of light treatment on necrosis and vascular function of normal skin following photodynamic therapy.

Sparing of normal tissue, mouse tail skin, by fractionation of light treatment in photodynamic therapy has been demonstrated in BDF1 mice injected with 2 mg tetrasodium-meso-tetra(4-sulphophenyl)porphine dodecahydrate i.v. When the time between 2 fractions of 67.5 J cm-2 and 90 J cm-2 was increased to 2 and 4 days respectively the incidence of necrosis fell to that expected after a single fraction. Blood flow in the tail skin 5 days after the second light fraction, as measured by the clearance of an intradermally injected solution of 133xenon in 0.9% saline, returned to control values when the time between 2 fractions was 2 days with 67.5 J cm-2 fractions, and 3 days with 90 J cm-2 fractions. The time course of recovery of normal mouse tail skin from photodynamic therapy, as shown by these split dose experiments, was found to be similar to the time course for the recovery of blood flow following a single light treatment.

Animals↗
PubMed1988

Cell survival characteristics of a human colon adenocarcinoma cell line after photodynamic treatment: a comparison of Photofrin II and TPPS.

A comparison has been made of the in vitro light-activated drug cytotoxicities of two different porphyrin compounds, Photofrin II and TPPS4. An early passage human colon adenocarcinoma cell line, WiDr, has been exposed to either drug for 24 h, the excess drug washed from the cells and the cells irradiated with light using quartz-tungsten-halogen lamps. Neither light nor drug alone under the experimental conditions employed was toxic to WiDr cells. Together, considerable cytotoxicity could be seen and the shapes of the cell survival curves following exposure to either drug then irradiation with light, were similar. For equal amounts of drug in the medium, Photofrin II was a more efficient photosensitizer of WiDr cells than TPPS4, and differences in cellular uptake could only partly explain this. When the experimental procedure was changed by reducing the temperature of irradiation, a reduction in photosensitizing efficiency could be demonstrated. This was more pronounced for Photofrin II, and was seen as a change in the slope of the final portion of the survival curve; and as a change in the shoulder for TPPS4. Two different batches of the two drugs were compared and shown to give slightly different results for Photofrin II (change in shoulder) but not to differ for TPPS4.

Adenocarcinoma↗
PubMed1988

The dynamics of tumor cords in an irradiated mouse mammary carcinoma with a large hypoxic cell component.

The tumor cord model represents a histologically based framework for interpretation of radiobiological phenomena, particularly the resistance to radiation conferred by absence of oxygen. For the mammary carcinoma T50/80 grown in B6D2F1 male mice, average oxygenation was poor, based on tumor growth delay after irradiation. There was no improvement in radiobiological oxygenation for several days after a high dose of radiation. This was consistent with events in the cords of the tumor, where although up to 20% of all cells became pyknotic by 8 hr, the cords did not shrink for at least 2 days. The cellular kinetics of populations of intact and dead cells, adjacent to and remote from the capillaries of the cords, were examined for up to 60 hr after irradiation and it was found that: (i) before treatment, average LI (adjacent) was 13% and LI (remote) was 2%, (ii) after irradiation, cells expressed pyknosis after passing through the S phase of the cell cycle, so that (iii) at early intervals there was a larger proportional rise in pyknotic cells in the adjacent than the remote zone. However, (iv) at later intervals there was always a higher proportion of dead cells in the remote zone.

Animals↗
PubMed1987

Estimates of the number of clonogenic cells in crypts of murine small intestine.

There is a proliferative cell hierarchy in the mouse intestinal crypt with ancestral stem cells which can regenerate all components of the lineage after injury (clonogenic cells). The number of these clonogenic or regenerative cells per crypt can be estimated from radiobiological experiments where doses of radiation are used to kill cells and ablate crypts. Various approaches can be adopted which provide different estimates of this number of cells. One of the conventional approaches used in the past provided estimates of about 70-80 clonogenic cells per crypt (i.e. about 50% of the proliferative or 30% of all crypt cells). A technically simpler approach has recently been suggested. This has been used here to provide many independent estimates of the number of crypt clonogenic cells. These suggest about 32 clonogenic cells exist per crypt i.e. about half the previous estimate and about twice the number of putative "functional" stem cells (those which operate as stem cells in the normal steady-state crypt). The reasons for the differences are discussed. The new estimates are compatible with the hypothesis that the crypt contains a ring of about 16 functional stem cells which are expected to be clonogenic, besides which there is a second ring of 16 clonogenic cells which represent early transit cells (the immediate daughters of the stem cells) which can act as clonogenic cells if required after radiation injury.

Age Factors↗
PubMed1987

Deriving cell survival curves from the overall responses of irradiated tumours: analysis of published data for tumour spheroids.

Curves of growth delay (GD) or 'cure' after graded doses of radiation have been analysed for 16 lines of human and animal tumours grown as multicellular spheroids in vitro. Dose-survival curves were derived for those cellular units from which spheroids regrow after unsuccessful irradiation (spheroid-regenerating cellular units, SRU). For 10 sets of data from 6 spheroid lines, the Do's and extrapolation numbers of the SRU derived by GD could be compared with the response of the clonogenic cells of the spheroids. For Do, a good correlation (r = 0.910) was found between the two; this was true also for Do derived from curves of spheroid 'cure' (7 sets of data from 6 spheroid lines) and clonogenic cells (r = 0.986). Using GD, the correlation of extrapolation numbers was less good (r = 0.682), the values for SRU commonly being higher than those for clonogenic cells. This may reflect features of the growth curves of spheroids after the lower range of doses of radiation. For human and animal tumour spheroids of 250 microns or less, derived Do ranged from 0.5 to 2.5 Gy. For spheroids of 350 microns or more, derived Do for animal tumour lines ranged from 3.4 to 4.2 Gy, for human lines from 1.5 to 2.1 Gy.

Animals↗
PubMed1987

Radiobiology and stathmokinetics of intestinal crypts associated with patches of Peyer.

The stathmokinetics and radiobiology of intestinal crypts directly adjoining the lymphoid patches of Peyer, have been compared with those of non-patch-associated crypts. Patch crypts contain an additional one to two rings of cells, the Mitotic Index for the whole crypt is higher than in non-patch crypts, and the apparent cell cycle time is insignificantly lower. Using single and split doses of gamma-rays, dose-survival curves were obtained for whole intestinal crypts, from which single-cell survival curves were derived for the clonogenic cells of the crypt. For a single-hit, multitarget, model, the extrapolation numbers of the cell survival curves for patch and non-patch crypts were the same (approximately 35) but the final D0 for cells of the patch crypts was significantly higher (2.1 versus 1.7 Gy). A linear-quadratic fit gave a similar ratio of alpha/beta (approximately 10) for the two curves. For a given level of crypt depletion, the number of clonogenic cells per crypt derived by the use of equal split doses of radiation, was the same for patch and non-patch crypts. This number is a function of the dose regime employed: the higher the level of crypt depletion, the higher the derived number of cells (range 10 to 45, for non-patch crypts).

Animals↗
PubMed1986

Dose-response relationships for photodynamic injury to murine skin.

Oedema and necrosis of murine tail skin have been measured after intravenous injection of haematoporphyrin derivative ("Photofrin", or PhI) followed 24 h later by graded exposures of the tail to full-spectrum visible light from a quartz-halogen lamp. End-points were degree of oedema and the proportion of mice in a dose-group that developed skin necrosis and tail atrophy. Oedema developed within 24 h of illumination and was a function of PhI dose and duration of light exposure. Onset of necrosis occurred after a minimum of 5 days and onset time was an inverse function of exposure time. Probit plots of proportion of necroses versus light exposure yielded values for ND50 (exposure corresponding to 50% incidence of necrosis) and l/slope. At the high but non-toxic dose of 2 mg PhI/mouse, ND50 was 18 min, l/slope 4 min, for pigmented BDF1 mice. Halving the PhI dose increased ND50 by a factor of 1.9. Albino BALB/c mice were markedly more sensitive to 2 mg PhI plus light than BDF1 mice: the ND50 was 7 min. Temporary occlusion of the blood supply to the tail (10 min before and during illumination) abrogated totally the oedematous and necrotic reactions to photodynamic therapy.

Animals↗
PubMed1985

Clonogenic response of cells of murine intestinal crypts to 12 cytotoxic drugs.

The in situ response of clonogenic cells in murine intestinal crypts to graded doses of 12 clinically used cytotoxic drugs has been measured by the crypt microcolony assay. For the alkylating agents mechlorethamine hydrochloride and BCNU, survival curves down to three logs of crypt depletion could be obtained. However, with isopropyl methane sulphonate only one log of depletion was measurable, and for a fourth alkylating agent, cyclophosphamide, no crypt killing occurred before other toxicities resulted in death of the animal in less than 3-4 days. This is the major constraint on the use of the microcolony assay with cytotoxic drugs. Of four antibiotics, survival curves were obtainable for adriamycin, bleomycin and mitomycin C, but not for actinomycin D. 5-Fluorouracil gave only a limited degree of crypt kill. Of three S-phase-specific drugs, hydroxyurea and vincristine resulted in little or no crypt depletion, but there was dose-dependent crypt depletion after methotrexate. The complexities of applying cellular-kinetic classifications of cytotoxic drugs to in situ endpoints are discussed.

Alkylating Agents↗