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Biomedical subjects

M Loizidou

Publications and source records attributed to M Loizidou.

At least 37 records · Page 2Linked to original sources
PubMed1999

Electrochemical oxidation of a textile dye wastewater using a Pt/Ti electrode.

Textile dye wastewater (TDW) from a reactive azo dyeing process was treated by an electrochemical oxidation method using Ti/Pt as anode and stainless steel 304 as cathode. Due to the strong oxidizing potential of the chemicals produced (chlorine, oxygen, hydroxyl radicals and other oxidants) when the wastewater was passed through the electrolytic cell the organic pollutants were oxidized to carbon dioxide and water. A number of experiments were run in a batch, laboratory-scale, pilot-plant, and the results are reported here according to residence time and initial addition of HCl in raw wastewater. When of 2 ml of HCl 36% were added and after 18 min of electrolysis at 0.89 A/cm(2), chemical oxygen demand (COD) was reduced by 86%, biochemical oxygen demand (BOD(5)) was reduced by 71%, ADMI color units were reduced by 100%, and TKN was reduced by 35%. The biodegradability of the wastewater was improved because the COD/BOD ratio decreased from 2.16 to 1.52. At the same time the efficiency of the electrode was about 170 g h(-1) A(-1) m(-2). and the mean energy consumption was 21 kW h/kg of COD. These results indicate that this electrolytic method could be used for effective TDW oxidation or as a feasible detoxification and color removal pretreatment stage for biological post treatment.

Coloring Agents↗
PubMed1999

Effect of gamma-linolenic acid on cellular uptake of structurally related anthracyclines in human drug sensitive and multidrug resistant bladder and breast cancer cell lines.

This study investigated the effect on drug uptake in multidrug resistant cells by the incorporation of the essential fatty acid gamma-linolenic acid (GLA). The cell lines used were the MCF-7/R resistant human breast cancer and MGH-U1/R bladder cancer. Uptake of drug (doxorubicin, epirubicin, mitoxantrone and idarubicin) after the incorporation of GLA was investigated quantitatively by flow cytometry and qualitatively by confocal microscopy. There was no observable overall increase in drug uptake due to GLA incorporation into the cells as shown by flow cytometry. However, an increase in uptake of the chemotherapeutic agent idarubicin was observed in GLA-treated resistant cells compared with untreated cells using the confocal microscope. This overall increase in cellular drug uptake was not accompanied by a change in cellular drug distribution. Only one drug, mitoxantrone, displayed a change in intracellular drug distribution due to GLA incorporation into MCF-7/R cells. This suggests that essential fatty acid incorporation into the cellular membranes of some resistant cells may cause a shift in the intracellular distribution of certain chemotherapeutic drugs.

Anthracyclines↗
PubMed1999

Noradrenaline improves the tumour to normal blood flow ratio and drug delivery in a model of liver metastases.

BACKGROUND: Vasopressors administered via the hepatic artery appear to increase drug delivery to colorectal liver metastases, but are limited by a short duration of action. This study measured their effect on blood flow and drug delivery during a prolonged infusion in a model of liver metastases. METHODS: In Hooded Lister rats with liver metastases, blood flow in tumour and adjacent normal liver was measured using laser Doppler flowmetry during a 30-min hepatic arterial infusion of endothelin 1, angiotensin II, vasopressin, N-nitro-L-arginine methyl ester (L-NAME), noradrenaline or saline (n = 6 per group). The same agents were co-administered with radiolabelled 5-fluorouracil (5-FU) (n = 6 per group) and uptake in the tumour and normal liver was measured. RESULTS: The mean(s.d.) duration of effect and resulting percentage changes in tumour to normal blood flow ratio of the vasopressors during this period were: noradrenaline, 2.9(0.4) min and 34(5) per cent (P < 0.05); angiotensin II, 4.2(0.2) min and 10(2) per cent (P < 0.05); vasopressin, 11.1(0.9) min and 7(2) per cent (P < 0.05); endothelin 1, 21.5(2.3) min and 14(5) per cent (P < 0.05); and L-NAME, 22.6(3.3) min and 2(1) per cent (P not significant). The mean(s.d.) uptake of radiolabelled 5-FU by the tumour in the groups studied was: saline, 5.1(3.2) x 10(5) c.p.m. per g tissue; angiotensin II, 5.1(1.4) x 10(5) c.p.m. per g; endothelin 1, 15.8(14.2) x 10(5) c.p.m. per g; L-NAME, 3.5(1.3) x 10(5) c.p.m. per g; and vasopressin, 6.8(3.5) x 10(5) c.p.m. per g. Significant improvements in 5-FU uptake only resulted from noradrenaline infusion (22.0(9.8) x 10(5) c.p.m. per g; P < 0.05). CONCLUSION: These findings suggest that hepatic arterially infused noradrenaline might be used to improve drug delivery to liver metastases.

Animals↗
PubMed1998

Endothelin-1 and tumour development.

There has been a growing conviction amongst oncologists that cancer is a disease characterized by changes in specific molecules. These changes include alteration in the structure, regulation or quantity of growth factors and their receptors, signal transducers and the proteins encoded by dominant or suppressor/recessive oncogenes. The role of endothelin (vasoactive peptide) in tumour cell signal transduction and mitogenesis and induction of endothelial cell growth and angiogenesis in tumour growth is discussed in this article.

Endothelin-1↗
PubMed1998

Raised endothelin 1 levels in patients with colorectal liver metastases.

BACKGROUND: Endothelin 1 (ET-1), a vasoconstrictor peptide, has been implicated as a tumour growth stimulator and an angiogenesis factor. METHODS: To assess the involvement of ET-1 in colorectal cancer, immunoelectron microscopy for ET-1 was performed in colorectal liver metastases and normal liver (n = 6). ET-1 plasma levels were measured by radioimmunoassay in patients with colorectal cancer, with (n = 18) and without (n = 12) liver metastases, and in controls (n = 22). RESULTS: In normal liver, ET-1 was present in endothelial cells; in tumour, it was observed in endothelial cells, tumour cells and myofibroblasts. Mean(s.d.) plasma ET-1 levels were 2.75 (1.37) pg/ml in controls, 4.53(1.61) pg/ml in patients with colorectal liver metastases (P = 0.001) and 3.92(1.32) pg/ml in patients without metastases (P = 0.02). CONCLUSION: ET-1 was present in various cell types within colorectal liver metastases and raised levels were found in the plasma of patients with colorectal cancer. ET-1 may not only modulate tumour vascular tone but also act on tumour growth and angiogenesis, both locally and systemically.

Aged↗
PubMed1997

Blood vessels in liver metastases from both sarcoma and carcinoma lack perivascular innervation and smooth muscle cells.

Hepatic arterial infusion (HAI) chemotherapy as treatment for human colorectal liver metastases is promising, but not entirely satisfactory. Improved drug delivery during HAI may be achieved by manipulating the different control mechanisms of normal versus tumour blood vessels. The peptidergic/aminergic innervation of vessels in normal liver and in two animal models of liver metastasis (Lister Hooded rat with syngeneic MC28 sarcoma; athymic (nude) rat with human HT29 carcinoma) was investigated to assess the suitability of these models for future pharmacological studies. Normal liver and metastases were studied immunohistochemically for the presence of protein gene product 9.5 (PGP), neuropeptide Y (NPY), tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP) and substance P (SP). Perivascular innervation was also examined by transmission electron microscopy. In Lister rat normal livers, perivascular immunoreactive nerve fibres containing PGP, NPY, TH, CGRP and SP were observed around the interlobular blood vessels near the hilum and in the portal tracts. The highest density was seen for PGP, followed in decreasing order, by NPY, TH, CGRP and SP. VIP-immunoreactive nerves were absent. No immunoreactive nerves were observed in the hepatic lobule. In athymic rat livers, the pattern of innervation was similar, except that SP immunoreactivity was more sparse. No perivascular immunoreactive nerves were observed in either MC28 or HT29 tumours. Electron microscopy confirmed the absence of perivascular nerves. Smooth muscle cells were not observed in tumour blood vessel walls. These results are comparable with previous observations on human liver metastases and suggest that the animal models may be suitable for pharmacological studies on vascular manipulation of HAI chemotherapy.

Animals↗
PubMed1997

Increase in immunoreactivity for endothelin-1 in blood vessels of rat liver metastases: experimental sarcoma and carcinoma.

Using electron immunocytochemistry, blood vessels in the normal rat liver and in 2 different animal models of liver metastases: (1) Hooded Lister rat with MC28 tumour, a sarcoma, and (2) nude rat with HT29 tumour, a carcinoma, were investigated for the presence of endothelin-1. In the normal livers, small subpopulations of vascular endothelial cells displayed discrete immunoreactivity for endothelin-1. In the livers with malignant tumours, there was a substantial increase in endothelin-1-immunoreactive endothelial cells in vessels located at the tumour periphery. In the controls, antibody to endothelin-1 also labelled sporadically some fibroblast/fibroblast-like cells associated with the blood vessels. In contrast, intense immunoreactivity for endothelin-1 was frequently associated with the tumour cells and/or fibroblast cells in both types of tumour examined.

Animals↗
PubMed1994

Helix pomatia agglutinin binding is a useful prognostic indicator in colorectal carcinoma.

BACKGROUND: Most deaths from colorectal carcinoma are due to metastases. A relatively reliable prognostic indicator at surgery to date is the Dukes' stage, but this is a morphologic approach that does not elucidate biochemical changes to explain why cells became metastatic. The binding sites for the lectin from the Roman snail Helix pomatia (HPA) were shown to be good prognostic indicators in breast and gastric cancer, and accordingly, this study was performed to evaluate the use of HPA binding sites as prognostic markers in colorectal carcinoma. METHODS: The histochemically detected expression of HPA binding sites in colorectal carcinomas (n = 130) was increased. The results of the histochemical findings were correlated with patient survival and tumor recurrence. RESULTS: The results indicated that the prognosis for the groups of patients whose colorectal cancer cells binded to HPA in tissue sections was almost as bad as those with Dukes' Stage C disease. CONCLUSION: Because HPA binds to N-acetylgalactosamine, the authors' results indicate that this sugar residue is at least partly involved in the process of human colorectal carcinoma cells metastasizing to regional lymph nodes and possibly also to distant sites.

Acetylgalactosamine↗
PubMed1993

Effect of leachate from landfills on underground water quality.

A study was performed in order to evaluate the effect of leachate from a landfill, in the Athens region, to the underground water of the surrounding area. A number of physical chemical parameters were monitored, including metals from various sampling sites, covering an area up to 3 km from the landfill. The experimental results indicate that the underground water quality has been greatly affected by the leachate, since most of the parameters examined show increased concentrations.

Ammonia↗
PubMed1992

Biodistribution of Lipiodol following hepatic arterial injection.

Thirteen patients undergoing selective coeliac angiography before insertion of an indwelling hepatic arterial cannula underwent injection of 3 ml radiolabelled Lipiodol (2 MBq 131I) into the hepatic artery at the end of the procedure. At subsequent laparotomy 1-9 days later, biopsies were taken from normal liver and metastases. The radioactivity of this material was measured to establish the tumour:liver ratios. Two patients with large metastases (> 10 cm in diameter) had low ratios. In the remainder, the median ratio at 24 h was 1.5:1 (range 1.1-2.5:1; n = 5) and 2.6:1 (range 1.5-64.0:1; n = 6) at 3-9 days. Four patients underwent single photon emission computed tomography, which confirmed selective retention of Lipiodol in small metastases, although no activity was detected in a large deposit (> 15 cm) 10 days after injection. The tumour:liver ratio in the other three patients increased from 3.0-5.6:1 on day 1 to 4.5-7.2:1 on day 6. This study suggests that Lipiodol may be a useful therapeutic delivery agent to small colorectal liver metastases.

Humans↗
PubMed1992

The effect of Warfarin and factor VII on tissue procoagulant activity and pulmonary seeding.

Peri-tumour fibrin is a consistent feature of tumour stroma and is deposited shortly after tumour cell inoculation. Since there are several ways in which fibrin may be beneficial to tumour growth, it is possible that the ability of normal or malignant tissue to generate fibrin may influence metastasis. Many normal tissues and tumour cells possess a procoagulant activity that is due to a complex of tissue factor and factor VII. We have measured this tissue procoagulant activity in normal rats, rats stabilised on Warfarin and similarly anticoagulated animals injected with factor VII. The effect of Warfarin and factor VII administration on pulmonary seeding following injection of MC28 fibrosarcoma cells was also assessed. Procoagulant activity in adrenal, lung and colon was significantly reduced by Warfarin (P less than 0.001). Administration of factor VII significantly increased lung and adrenal tissue procoagulant activity in anticoagulated rats (P less than 0.02). Warfarinised rats had significantly slower primary tumour growth (P less than 0.001) and fewer lung deposits than control animals (P less than 0.001). Injection of factor VII restored pulmonary seeding to control levels (P less than 0.001). Warfarin did not affect the ability of the cells to adhere in vitro and did not reduce the number of tumour cells physically trapped in the lungs after intravenous injection. It is concluded that the procoagulant activity of normal tissues may influence their ability to support tumour growth and that the antimetastatic effect of Warfarin may be at least partly due to a reduction in the availability of the factor VII required for this activity.

Adrenal Glands↗
PubMed1992

Biodistribution of lipiodol following hepatic arterial injection.

Lipiodol, a derivative of poppy seed oil, has been used angiographically to improve visualisation of small liver tumours. We have utilised this finding to determine whether intrahepatic arterial injection of lipiodol can be used as a vehicle to deliver selectively 131I into liver tumours. Two groups of rats were studied. Group 1 (control, no liver tumour) received 0.1 ml 131I-lipiodol (1 microCi) into the hepatic artery. Animals were killed at regular time intervals over 30 days and organs were submitted to well-counting. Over 90% of activity remained in the liver at 6 h. Eighty per cent activity was lost from the normal liver, to be excreted in the urine over 30 days. Group 2 animals received intraportal injections of 7.5 x 10(5) MC28 sarcoma cells. Multiple liver metastases were present after 14 days. Animals were similarly studied at each time interval and samples from tumour and normal liver were submitted to well-counting. Lipiodol was selectively retained within tumour and cleared from normal liver. 131I-lipiodol may prove valuable as a delivery agent for radio/chemotherapy to liver metastases.

Animals↗
PubMed1991

Importance of the omentum in the development of intra-abdominal metastases.

Areas of trauma are preferred sites for metastatic tumour growth. In extensive intra-abdominal tumour recurrence the omentum is invariably involved. The importance of the omentum in the development of tumours at sites of intra-abdominal trauma has been investigated. Colonic anastomoses were performed in Hooded-Lister rats with and without omentectomy. Animals received intraluminal or intraperitoneal injections of a syngeneic tumour. With intraluminal injection, tumour occurred at the anastomosis and in the omentum in 38 and 43 per cent of animals respectively but following omentectomy the values were 14 and 9 per cent (omental remnant). With intraperitoneal administration tumour occurred in 53 per cent at the anastomosis and in 79 per cent in the omentum compared with 16 and 29 per cent (in omental remnant) following omentectomy. In this model a reduced ability of an anastomosis to support 'seeded' tumour following removal of the omentum is demonstrated and the development of local recurrence from spilled tumour cells during operation may be enhanced by, or be dependent on, the proximity of the omentum.

Anastomosis, Surgical↗
PubMed1991

Acute exposure to cadmium causes time-dependent liver injury in rats.

1. Serum enzymes activities of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT), after intraperitoneal injection of CdCl2 showed a maximum increase at 12 hours, contrary to the alkaline phosphatase (ALP) that showed a permanent decrease by that time. 2. Cadmium concentration in liver showed an increase at 6 and 12 hours, a decrease at 18, and a re-establishment to the initial values at 24 hours. 3. Liver microsomal membrane fluidity showed an increase at 6 hours followed by a decrease within 24 hours. Free radical generation was decreasing gradually up to 24 hours. 4. Gradually increasing changes were observed from the histological study.

Alanine Transaminase↗
PubMed1991

Integrin alpha 6/beta 4 complex is located in hemidesmosomes, suggesting a major role in epidermal cell-basement membrane adhesion.

The alpha 6/beta 4 complex is a member of the integrin family of adhesion receptors. It is found on a variety of epithelial cell types, but is most strongly expressed on stratified squamous epithelia. Fluorescent antibody staining of human epidermis suggests that the beta 4 subunit is strongly localized to the basal region showing a similar distribution to that of the 230-kD bullous pemphigoid antigen. The alpha 6 subunit is also strongly localized to the basal region but in addition is present over the entire surfaces of basal cells and some cells in the immediate suprabasal region. By contrast staining for beta 1, alpha 2, and alpha 3 subunits was very weak basally, but strong on all other surfaces of basal epidermal cells. These results suggest that different integrin complexes play differing roles in cell-cell and cell-matrix adhesion in the epidermis. Immunoelectron microscopy showed that the alpha 6/beta 4 complex at the basal epidermal surface is strongly localized to hemidesmosomes. This result provides the first well-characterized monoclonal antibody markers for hemidesmosomes and suggests that the alpha 6/beta 4 complex plays a major role in epidermal cell-basement membrane adhesion. We suggest that the cytoplasmic domains of these transmembrane glycoproteins may contribute to the structure of hemidesmosomal plaques. Immunoultrastructural localization of the BP antigen suggests that it may be involved in bridging between hemidesmosomal plaques and keratin intermediate filaments of the cytoskeleton.

Animals↗
PubMed1991

Monocyte-derived giant cell formation in patients with breast cancer.

Recent reports of monocyte-derived giant cell formation in breast cancer and associated retroviral findings have attracted much interest in the scientific literature and with the media, revitalising hypotheses of a viral role in the aetiology of the disease. We describe an assay developed to investigate further the giant cell forming phenomenon and report results which conflict with earlier work. We observed a smaller proportion of patients with breast cancer forming giant cells than in previous reports. Conversely, a much larger proportion of controls formed giant cells. Using our assay to calculate a fusion index the formation of giant cells, as defined in earlier work, was found to be a poor indicator of the degree of cell fusion in our samples. We discuss our experiences with the assay and suggest the calculation of a fusion index as a more comparable and quantitative measurement of cell fusion.

Adolescent↗