Ruy Tchao - Academia.edu (original) (raw)

Papers by Ruy Tchao

Research paper thumbnail of The distribution of heterologous tumour cells in chick embryos following intravenous injection

European journal of cancer, Jun 1, 1969

Research paper thumbnail of In vitro Study of the Effects of UV–B on Cultured Human Repinal Pigment Epithelial Cells : UV – Blocking Efficacy of Intraocular Lenses

Research paper thumbnail of Analysis of some tissue processes involved in the propagation of cancer using histophysiologic gradient culture

Research paper thumbnail of Interactions of tumor cells with human amnion membrane: a model for studying tumor invasion in vitro

PubMed, 1982

The human amnion membrane consisting of a single layer of epithelium attached to the continuous b... more The human amnion membrane consisting of a single layer of epithelium attached to the continuous basement membrane and the underlying collagenous stroma has been used to study tumor invasion in vitro by means of electron microscopy. Three cell lines utilized in these experiments were established from surgical specimens of human squamous cell carcinomas of the tongue and larynx. The cultivation of amnion membrane for 48h or longer leads to some alterations in the morphological appearance. All three carcinomas form aggregates which appear firmly attached to the amnion epithelium and are able to establish contacts to the basement membrane within 96h. In two cases the basement membrane reveals local defects and some cells have extended processes into the collagenous tissue. However, none of the tumor cells of the three carcinomas have broken through the basement membrane and grown into the collagenous stroma. Some differences of interaction between amnion epithelial cells and tumor cells of the three carcinomas are apparent. These ultrastructural findings show, that the amnion membrane model allows morphological analysis of various steps of tumor invasion under standardized conditions.

Research paper thumbnail of Histophysiologic gradient culture of stratified epithelium

Research paper thumbnail of Interaction of human carcinoma cells with an epithelial layer and the underlying basement membrane. A new model

PubMed, 1981

We have developed a new in-vitro model to study the interaction of malignant tumour cells with a ... more We have developed a new in-vitro model to study the interaction of malignant tumour cells with a normal epithelium and a subsequent invasion and penetration of the epithelium. The system involves the culture of human amnions obtained after caesarean section. The amnion with its intact basement membrane and the underlying collagenous stroma was cultured on an agar coated grid, tumour cells were added on top of the amnoin and co-cultured for up to 7 days. We report on human tumour cell lines, HeLa I also broke through the basement membrane and grew into the collagenous stroma. Normal cells were accepted by the amnoin and the amnoin epithelium grew over the fibroblasts. This system should provide a useful model to study the factors controlling tumour cell invasion, such as the role of proteolytic and collagenolytic enzymes, cell adhesion and locomotion.

Research paper thumbnail of Comparison of invasiveness and non-invasiveness of two epithelial cell lines in vitro

PubMed, 1984

Two epithelial cell lines of urological origin have been compared for their invasiveness in an in... more Two epithelial cell lines of urological origin have been compared for their invasiveness in an in vitro three-dimensional culture system, using embryonic chick cardiac muscle as host tissue. Cells from the Nara bladder tumor line (NBT-II), an invasive tumor in the rat, invaded and progressively occupied the cardiac muscle which degenerated. Cells from a dog kidney line (MDCK), which are of low tumorigenicity in nude mice, failed to invade into the cardiac muscle in vitro. MDCK cells formed a structurally polarized epithelium around the heart tissue. MDCK is the first established epithelial cell line that has been found to grow in this invasion assay culture system and yet did not invade the heart fragment.

Research paper thumbnail of The effect of vitamin A on the migration and DNA synthesis of rat bladder tumor cell line NBT II in culture

PubMed, May 1, 1979

In the presence of vitamin A, NBT II cells, derived from a carcinoma of rat bladder, grew as a mo... more In the presence of vitamin A, NBT II cells, derived from a carcinoma of rat bladder, grew as a monolayer with diminished piling up. Keratinization, which normally appeared within stratified cells in postconfluent cultures, was inhibited. A "wounding" technique suitable for quantitative analysis of cell migration was developed for confluent cultures grown on glass coverslips. Vitamin A treatment enhanced the migration of cells from the wound edge. In dense postconfluent monolayer cultures, vitamin A treatment maintained a higher percentage of cells in DNA synthesis than in the control cultures, as determined by 3H-TdR uptake and autoradiography. In contrast, in sparse cultures vitamin A did not stimulate DNA synthesis or increase the mitotic index. This stimulatory effect, limited to dense cultures, may be attributable to vitamin A causing viable cells to be shed into the medium, thereby maintaining the monolayer just at confluence. Thus vitamin A inhibits squamous cell differentiation, enhances migration, and maintains the culture in the proliferative phase. In a different system of high cell density, NBT II aggregates cultured in a combined matrix of chick plasma clot and collagen-coated sponge, vitamin A also enhanced the migration of cells. These results may explain, in part, the failure of vitamin A to inhibit completely the growth of some established tumors.

Research paper thumbnail of The growth of heterologous tumour cells in chick embryos

European journal of cancer, Jun 1, 1969

Research paper thumbnail of A New In-Vitro Model to Study Tumour Cell Invasion

Springer eBooks, 1980

There is an urgent need to develop suitable models to study tumour cell invasion in tumour metast... more There is an urgent need to develop suitable models to study tumour cell invasion in tumour metastasis, however, there are only few available models (Leighton and Kline, 1954; Easty and Easty, 1963, 1974; Schleich et al., 1974; De Ridder et al., 1977; Kramer and Nicolson, 1979).

Research paper thumbnail of Effect of a novel multipurpose contact lens solution on human corneal epithelial barrier function

Contact Lens and Anterior Eye, Dec 1, 2010

To explore the effect of a novel multipurpose contact lens solution (MPS) on the junction protein... more To explore the effect of a novel multipurpose contact lens solution (MPS) on the junction protein distribution and barrier function of cultured human corneal epithelial cell monolayers. Methods: Cultured human corneal epithelial cells (HCEpiC) were exposed to a novel MPS (MPS A; Biotrue TM multipurpose solution, Bausch & Lomb Incorporated) at 50%, 75% and 100% for 10 or 30 min. Four commercially available MPS products, MPS B (AQuify, Ciba Vision), MPS C (COMPLETE MPS Easy Rub, AMO), MPS D (OPTI-FREE Express, Alcon) and MPS E (OPTI-FREE RepleniSH, Alcon) were tested in parallel. Tight junction structure and integrity were evaluated by confocal microscopy using ZO-1 antibody and scanning microscopy (SEM). Quantitative evaluation of MPSs on epithelial barrier function was determined by measuring transepithelial electrical resistance (TEER) across HCEpiC grown on Transwell Clear permeable supports and on electric cell-substrate impedance sensing (ECIS) electrode arrays. Results: Overall after exposure to the three concentrations (50%, 75%, and 100%) of MPS A, ZO-1 distribution and fluorescent intensity on the cell surface appeared similar to the media control with continuous tight junctions and clear intercellular junctions. At all measured time points after exposure to MPS A (50% or 75%) there was also no effect on the TEER using both resistance methodologies, and SEM showed that MPS A appeared similar to the Hank's balanced salt solution (HBSS) control. In cells exposed to MPS D there was a dose-dependent change in the distribution of ZO-1, some cell detachment, and a decrease in monolayer resistance at all time points measured. Ultrastructurally, MPS D caused gross changes, including damage to cell junctions and plasma membranes. To a lesser extent, the remaining three commercial MPS products demonstrated some effects on tight junction ZO-1 distribution and/or TEER. Conclusions: Based on the in vitro measurements of tight junction protein expression, monolayer integrity, and transepithelial electrical resistance, the novel multipurpose contact lens solution (MPS A) did not alter corneal barrier function as compared to media, PBS or HBSS control. Clinical significance of the observed differences in epithelial barrier function among the MPSs tested needs further investigation.

Research paper thumbnail of Physical characterization of thin semi-porous poly(L-lactic acid)/poly(ethylene glycol) membranes for tissue engineering

Journal of Biomaterials Science-polymer Edition, 2007

This study examines physical properties of solvent-cast poly(L-lactic acid) (PLLA): poly(ethylene... more This study examines physical properties of solvent-cast poly(L-lactic acid) (PLLA): poly(ethylene glycol) PEG membranes as a function of PEG molecular weight (MW) and incubation in vitro for 6 weeks. PEGs of MW 400, 1450 and 8000 were used. The morphological, thermal, mechanical and permeability properties of the membranes were studied prior to and after 3 and 6 weeks of incubation in phosphate-buffered saline (PBS) at 37 degrees C. The membranes showed a thickness of about 35+/-5 microm and were found to be semi-porous, with a non-porous surface as well as a porous surface with pore-diameters of 0.5-5 microm. The surface pore size was found to be a function of PEG MW used. All membranes were mechanically strong, with elastic moduli and tensile strength of 150-440 MPa and 7-36 MPa, respectively, all through the 6-week incubation period. The lower-MW PEGs plasticized PLLA based on high initial percent elongation; however, the effect was lost after 3 weeks of incubation in PBS. All membranes except those fabricated with PEG 8000 were impermeable for up to 6 weeks of incubation in PBS. Permeability studies showed that only PLLA:PEG 8000 membranes were permeable to methylene blue after 3 weeks of degradation.

Research paper thumbnail of Drug Assays on Organ Cultures of Biopsies from Human Tumours

BMJ, Aug 22, 1964

Hypogammaglobulinaemia-Allen and Hadden MMIBALTJORH the presence of the hypogammaglobulinaemia ge... more Hypogammaglobulinaemia-Allen and Hadden MMIBALTJORH the presence of the hypogammaglobulinaemia gene on the X chromosome. The X is a long chromosome, with about 150 cross-over units, and linkage cannot be detected between genes approaching 50 cross-over units apart. The appearance of close linkage must probably be understood as a matter of chance, but this family can nevertheless be used as an illustration of how informative a real close linkage with a marker gene could be (Fig. 4). II 2 is heterozygous XgaXg, for she is Xg(a +) and has Xg(a-) children. To her two sons, III 3 and III 4, she has given Xg gene and her hypogammaglobulinaemia gene ; but to her daughter, III 2, she has given her Xga gene and, barring crossing over, a gene not determining hypogammaglobulinaemia. III 2 should therefore not be a carrier: that she appears not to be, by having two normal sons, is probably a matter of chance; for the close linkage invoked in this demonstration, we must repeat, in all probability does not exist.

Research paper thumbnail of Conversion of Proliferative Endometrium to Secretory Endometrium by Progesterone in Organ Culture

Journal of Endocrinology, Nov 1, 1969

Human proliferative endometrial tissue was maintained in organ culture. Glandular cells in the fr... more Human proliferative endometrial tissue was maintained in organ culture. Glandular cells in the fragments were stimulated to secrete by adding progesterone to the culture medium\p=m-\but not by insulin, oestradiol or cortisol; insulin enhanced the effect of progesterone. With progesterone, subnuclear vacuolation appeared in the glandular cells after 2-3 days. As the culture continued, these vacuoles disappeared and secretion into the lumen occurred.

Research paper thumbnail of Effect of chemotherapeutic agents and hormones on organ cultures of human tumours

European journal of cancer, Mar 1, 1968

Research paper thumbnail of Increased Cell Membrane Sensitivity to Shear Force Resulting from Adherence on an Anisotropic Polymer Surface

Research paper thumbnail of The Induction of Tumours in the Guinea-pig with Methylcholanthrene and Diethylnitrosamine and their Propagation In Vivo and in vitro

British Journal of Cancer, Jun 1, 1973

Research paper thumbnail of The Use of 32P Labelled Orthophosphate for the Assay of Chemotherapeutic Agents on Tumours Maintained in Organ Culture

British Journal of Cancer, Dec 1, 1967

Research paper thumbnail of Can cell morphology in monolayer reveal its behaviour in aggregates?

Cell Biology International Reports, Jul 1, 1978

Ihe morphology of HeLa cells was altered to stellate shape by 0.2-1.0 &fbutyric acid. At similar ... more Ihe morphology of HeLa cells was altered to stellate shape by 0.2-1.0 &fbutyric acid. At similar concentrations butyric acid did not alter the ability of HeLa cells to aggregate, but did inhibit the ~emdelling of the aggregates. Papaverine at 10 +Cl, on the other hand, had no effect on cells in mnolayer, but severely inhibited the ability of cells to aggregate and the remdelling of the aggregates. Our results shw that the effect of a drug on the mxphology of He.La cells in mmolayer does not predict its effect in aggregates of cells which mre faithfully approximate the behaviour of cells in tissue than the monolayer. Recentlyanu&erofworkershave sl-min thatadditionof di-butyrylcyclicN4P (dbc#MP) to themedimchanges themorphology of cells in monolayer culture (Review by Willingham, 1976). Studies on transformed fibroblasts showed that dbcAMp altered cell adhesion

Research paper thumbnail of The chick embryo in toxicology: an alternative to the rabbit eye

Food and Chemical Toxicology, Feb 1, 1985

The chorioallantoic membrane (CAM) of the chick embryo is readily accessible for experimentation.... more The chorioallantoic membrane (CAM) of the chick embryo is readily accessible for experimentation. It is a complete tissue that responds to injury with classical inflammatory reactions. It is limited to the late phase of embryologic life. and is without the sense of pain. Focal topical application of various household products onto the CAM results in local injury and reactions that differ in severity from one product to another. For any single product, tested as a sequence of dilutions on a series of membranes, the CAM responds with decreasing intensity that parallels the decreasing dosage. The membrane is prepared for study according to the method of Zwilling (Transplantn Bull 1959, 6, 115). The test material is applied in a Teflon ring to the 14-day-old CAM, to localize the application site. The macroscopic response is scored on day 17 of incubation. The results of analysis of histological preparations are found to correlate with macroscopic appearance. When a series of preparations was ranked according to the severity of the response each induced on the CAM, there was a good correlation with the ranking of the same preparations in the Draize test.

Research paper thumbnail of The distribution of heterologous tumour cells in chick embryos following intravenous injection

European journal of cancer, Jun 1, 1969

Research paper thumbnail of In vitro Study of the Effects of UV–B on Cultured Human Repinal Pigment Epithelial Cells : UV – Blocking Efficacy of Intraocular Lenses

Research paper thumbnail of Analysis of some tissue processes involved in the propagation of cancer using histophysiologic gradient culture

Research paper thumbnail of Interactions of tumor cells with human amnion membrane: a model for studying tumor invasion in vitro

PubMed, 1982

The human amnion membrane consisting of a single layer of epithelium attached to the continuous b... more The human amnion membrane consisting of a single layer of epithelium attached to the continuous basement membrane and the underlying collagenous stroma has been used to study tumor invasion in vitro by means of electron microscopy. Three cell lines utilized in these experiments were established from surgical specimens of human squamous cell carcinomas of the tongue and larynx. The cultivation of amnion membrane for 48h or longer leads to some alterations in the morphological appearance. All three carcinomas form aggregates which appear firmly attached to the amnion epithelium and are able to establish contacts to the basement membrane within 96h. In two cases the basement membrane reveals local defects and some cells have extended processes into the collagenous tissue. However, none of the tumor cells of the three carcinomas have broken through the basement membrane and grown into the collagenous stroma. Some differences of interaction between amnion epithelial cells and tumor cells of the three carcinomas are apparent. These ultrastructural findings show, that the amnion membrane model allows morphological analysis of various steps of tumor invasion under standardized conditions.

Research paper thumbnail of Histophysiologic gradient culture of stratified epithelium

Research paper thumbnail of Interaction of human carcinoma cells with an epithelial layer and the underlying basement membrane. A new model

PubMed, 1981

We have developed a new in-vitro model to study the interaction of malignant tumour cells with a ... more We have developed a new in-vitro model to study the interaction of malignant tumour cells with a normal epithelium and a subsequent invasion and penetration of the epithelium. The system involves the culture of human amnions obtained after caesarean section. The amnion with its intact basement membrane and the underlying collagenous stroma was cultured on an agar coated grid, tumour cells were added on top of the amnoin and co-cultured for up to 7 days. We report on human tumour cell lines, HeLa I also broke through the basement membrane and grew into the collagenous stroma. Normal cells were accepted by the amnoin and the amnoin epithelium grew over the fibroblasts. This system should provide a useful model to study the factors controlling tumour cell invasion, such as the role of proteolytic and collagenolytic enzymes, cell adhesion and locomotion.

Research paper thumbnail of Comparison of invasiveness and non-invasiveness of two epithelial cell lines in vitro

PubMed, 1984

Two epithelial cell lines of urological origin have been compared for their invasiveness in an in... more Two epithelial cell lines of urological origin have been compared for their invasiveness in an in vitro three-dimensional culture system, using embryonic chick cardiac muscle as host tissue. Cells from the Nara bladder tumor line (NBT-II), an invasive tumor in the rat, invaded and progressively occupied the cardiac muscle which degenerated. Cells from a dog kidney line (MDCK), which are of low tumorigenicity in nude mice, failed to invade into the cardiac muscle in vitro. MDCK cells formed a structurally polarized epithelium around the heart tissue. MDCK is the first established epithelial cell line that has been found to grow in this invasion assay culture system and yet did not invade the heart fragment.

Research paper thumbnail of The effect of vitamin A on the migration and DNA synthesis of rat bladder tumor cell line NBT II in culture

PubMed, May 1, 1979

In the presence of vitamin A, NBT II cells, derived from a carcinoma of rat bladder, grew as a mo... more In the presence of vitamin A, NBT II cells, derived from a carcinoma of rat bladder, grew as a monolayer with diminished piling up. Keratinization, which normally appeared within stratified cells in postconfluent cultures, was inhibited. A "wounding" technique suitable for quantitative analysis of cell migration was developed for confluent cultures grown on glass coverslips. Vitamin A treatment enhanced the migration of cells from the wound edge. In dense postconfluent monolayer cultures, vitamin A treatment maintained a higher percentage of cells in DNA synthesis than in the control cultures, as determined by 3H-TdR uptake and autoradiography. In contrast, in sparse cultures vitamin A did not stimulate DNA synthesis or increase the mitotic index. This stimulatory effect, limited to dense cultures, may be attributable to vitamin A causing viable cells to be shed into the medium, thereby maintaining the monolayer just at confluence. Thus vitamin A inhibits squamous cell differentiation, enhances migration, and maintains the culture in the proliferative phase. In a different system of high cell density, NBT II aggregates cultured in a combined matrix of chick plasma clot and collagen-coated sponge, vitamin A also enhanced the migration of cells. These results may explain, in part, the failure of vitamin A to inhibit completely the growth of some established tumors.

Research paper thumbnail of The growth of heterologous tumour cells in chick embryos

European journal of cancer, Jun 1, 1969

Research paper thumbnail of A New In-Vitro Model to Study Tumour Cell Invasion

Springer eBooks, 1980

There is an urgent need to develop suitable models to study tumour cell invasion in tumour metast... more There is an urgent need to develop suitable models to study tumour cell invasion in tumour metastasis, however, there are only few available models (Leighton and Kline, 1954; Easty and Easty, 1963, 1974; Schleich et al., 1974; De Ridder et al., 1977; Kramer and Nicolson, 1979).

Research paper thumbnail of Effect of a novel multipurpose contact lens solution on human corneal epithelial barrier function

Contact Lens and Anterior Eye, Dec 1, 2010

To explore the effect of a novel multipurpose contact lens solution (MPS) on the junction protein... more To explore the effect of a novel multipurpose contact lens solution (MPS) on the junction protein distribution and barrier function of cultured human corneal epithelial cell monolayers. Methods: Cultured human corneal epithelial cells (HCEpiC) were exposed to a novel MPS (MPS A; Biotrue TM multipurpose solution, Bausch & Lomb Incorporated) at 50%, 75% and 100% for 10 or 30 min. Four commercially available MPS products, MPS B (AQuify, Ciba Vision), MPS C (COMPLETE MPS Easy Rub, AMO), MPS D (OPTI-FREE Express, Alcon) and MPS E (OPTI-FREE RepleniSH, Alcon) were tested in parallel. Tight junction structure and integrity were evaluated by confocal microscopy using ZO-1 antibody and scanning microscopy (SEM). Quantitative evaluation of MPSs on epithelial barrier function was determined by measuring transepithelial electrical resistance (TEER) across HCEpiC grown on Transwell Clear permeable supports and on electric cell-substrate impedance sensing (ECIS) electrode arrays. Results: Overall after exposure to the three concentrations (50%, 75%, and 100%) of MPS A, ZO-1 distribution and fluorescent intensity on the cell surface appeared similar to the media control with continuous tight junctions and clear intercellular junctions. At all measured time points after exposure to MPS A (50% or 75%) there was also no effect on the TEER using both resistance methodologies, and SEM showed that MPS A appeared similar to the Hank's balanced salt solution (HBSS) control. In cells exposed to MPS D there was a dose-dependent change in the distribution of ZO-1, some cell detachment, and a decrease in monolayer resistance at all time points measured. Ultrastructurally, MPS D caused gross changes, including damage to cell junctions and plasma membranes. To a lesser extent, the remaining three commercial MPS products demonstrated some effects on tight junction ZO-1 distribution and/or TEER. Conclusions: Based on the in vitro measurements of tight junction protein expression, monolayer integrity, and transepithelial electrical resistance, the novel multipurpose contact lens solution (MPS A) did not alter corneal barrier function as compared to media, PBS or HBSS control. Clinical significance of the observed differences in epithelial barrier function among the MPSs tested needs further investigation.

Research paper thumbnail of Physical characterization of thin semi-porous poly(L-lactic acid)/poly(ethylene glycol) membranes for tissue engineering

Journal of Biomaterials Science-polymer Edition, 2007

This study examines physical properties of solvent-cast poly(L-lactic acid) (PLLA): poly(ethylene... more This study examines physical properties of solvent-cast poly(L-lactic acid) (PLLA): poly(ethylene glycol) PEG membranes as a function of PEG molecular weight (MW) and incubation in vitro for 6 weeks. PEGs of MW 400, 1450 and 8000 were used. The morphological, thermal, mechanical and permeability properties of the membranes were studied prior to and after 3 and 6 weeks of incubation in phosphate-buffered saline (PBS) at 37 degrees C. The membranes showed a thickness of about 35+/-5 microm and were found to be semi-porous, with a non-porous surface as well as a porous surface with pore-diameters of 0.5-5 microm. The surface pore size was found to be a function of PEG MW used. All membranes were mechanically strong, with elastic moduli and tensile strength of 150-440 MPa and 7-36 MPa, respectively, all through the 6-week incubation period. The lower-MW PEGs plasticized PLLA based on high initial percent elongation; however, the effect was lost after 3 weeks of incubation in PBS. All membranes except those fabricated with PEG 8000 were impermeable for up to 6 weeks of incubation in PBS. Permeability studies showed that only PLLA:PEG 8000 membranes were permeable to methylene blue after 3 weeks of degradation.

Research paper thumbnail of Drug Assays on Organ Cultures of Biopsies from Human Tumours

BMJ, Aug 22, 1964

Hypogammaglobulinaemia-Allen and Hadden MMIBALTJORH the presence of the hypogammaglobulinaemia ge... more Hypogammaglobulinaemia-Allen and Hadden MMIBALTJORH the presence of the hypogammaglobulinaemia gene on the X chromosome. The X is a long chromosome, with about 150 cross-over units, and linkage cannot be detected between genes approaching 50 cross-over units apart. The appearance of close linkage must probably be understood as a matter of chance, but this family can nevertheless be used as an illustration of how informative a real close linkage with a marker gene could be (Fig. 4). II 2 is heterozygous XgaXg, for she is Xg(a +) and has Xg(a-) children. To her two sons, III 3 and III 4, she has given Xg gene and her hypogammaglobulinaemia gene ; but to her daughter, III 2, she has given her Xga gene and, barring crossing over, a gene not determining hypogammaglobulinaemia. III 2 should therefore not be a carrier: that she appears not to be, by having two normal sons, is probably a matter of chance; for the close linkage invoked in this demonstration, we must repeat, in all probability does not exist.

Research paper thumbnail of Conversion of Proliferative Endometrium to Secretory Endometrium by Progesterone in Organ Culture

Journal of Endocrinology, Nov 1, 1969

Human proliferative endometrial tissue was maintained in organ culture. Glandular cells in the fr... more Human proliferative endometrial tissue was maintained in organ culture. Glandular cells in the fragments were stimulated to secrete by adding progesterone to the culture medium\p=m-\but not by insulin, oestradiol or cortisol; insulin enhanced the effect of progesterone. With progesterone, subnuclear vacuolation appeared in the glandular cells after 2-3 days. As the culture continued, these vacuoles disappeared and secretion into the lumen occurred.

Research paper thumbnail of Effect of chemotherapeutic agents and hormones on organ cultures of human tumours

European journal of cancer, Mar 1, 1968

Research paper thumbnail of Increased Cell Membrane Sensitivity to Shear Force Resulting from Adherence on an Anisotropic Polymer Surface

Research paper thumbnail of The Induction of Tumours in the Guinea-pig with Methylcholanthrene and Diethylnitrosamine and their Propagation In Vivo and in vitro

British Journal of Cancer, Jun 1, 1973

Research paper thumbnail of The Use of 32P Labelled Orthophosphate for the Assay of Chemotherapeutic Agents on Tumours Maintained in Organ Culture

British Journal of Cancer, Dec 1, 1967

Research paper thumbnail of Can cell morphology in monolayer reveal its behaviour in aggregates?

Cell Biology International Reports, Jul 1, 1978

Ihe morphology of HeLa cells was altered to stellate shape by 0.2-1.0 &fbutyric acid. At similar ... more Ihe morphology of HeLa cells was altered to stellate shape by 0.2-1.0 &fbutyric acid. At similar concentrations butyric acid did not alter the ability of HeLa cells to aggregate, but did inhibit the ~emdelling of the aggregates. Papaverine at 10 +Cl, on the other hand, had no effect on cells in mnolayer, but severely inhibited the ability of cells to aggregate and the remdelling of the aggregates. Our results shw that the effect of a drug on the mxphology of He.La cells in mmolayer does not predict its effect in aggregates of cells which mre faithfully approximate the behaviour of cells in tissue than the monolayer. Recentlyanu&erofworkershave sl-min thatadditionof di-butyrylcyclicN4P (dbc#MP) to themedimchanges themorphology of cells in monolayer culture (Review by Willingham, 1976). Studies on transformed fibroblasts showed that dbcAMp altered cell adhesion

Research paper thumbnail of The chick embryo in toxicology: an alternative to the rabbit eye

Food and Chemical Toxicology, Feb 1, 1985

The chorioallantoic membrane (CAM) of the chick embryo is readily accessible for experimentation.... more The chorioallantoic membrane (CAM) of the chick embryo is readily accessible for experimentation. It is a complete tissue that responds to injury with classical inflammatory reactions. It is limited to the late phase of embryologic life. and is without the sense of pain. Focal topical application of various household products onto the CAM results in local injury and reactions that differ in severity from one product to another. For any single product, tested as a sequence of dilutions on a series of membranes, the CAM responds with decreasing intensity that parallels the decreasing dosage. The membrane is prepared for study according to the method of Zwilling (Transplantn Bull 1959, 6, 115). The test material is applied in a Teflon ring to the 14-day-old CAM, to localize the application site. The macroscopic response is scored on day 17 of incubation. The results of analysis of histological preparations are found to correlate with macroscopic appearance. When a series of preparations was ranked according to the severity of the response each induced on the CAM, there was a good correlation with the ranking of the same preparations in the Draize test.