A confocal microscopy study of the very early cellular response to oxidative stress induced by zinc phthalocyanine sensitization

Oxidative stress has been involved in several biological and pathological processes. Reactive oxygen species have been shown to play both beneficial and deleterious roles. The present work contributes to the understanding of the very early events of cellular response to oxidative stress. Oxidative stress was produced intracellularly by light activation of zinc phthalocyanine (ZnPc) at a light dose that did not lead to apoptosis or necrosis. Phthalocyanine was photoactivated using the 647-nm laser line of a confocal microscope through the objective lens causing oxidative stress and allowing observation of the evoked phenomena at the single cell level and in real time. Mitochondria membrane potential (DeltaPsi(m)), intracellular pH, calcium concentration, and generation of reactive oxygen species (ROS) were recorded using specific vital fluorescent probes and quantified by image processing and analysis. Subcellular localization of ZnPc was also studied in order to determine the primary and intermediate ROS target.

Human fibroblast alterations induced by low power laser irradiation at the single cell level using confocal microscopy

Low power laser irradiation is regarded to have a significant role in triggering cellular proliferation and in treating diseases of diverse etiologies. The present work contributes to the understanding of the mechanisms of action by studying low power laser effects in human fibroblasts. Confocal laser scanning microscopy is used for irradiation and observation of the same area of interest allowing the imaging of laser effects at the single cell level and in real time. Coverslip cultures were placed in a small incubation chamber for in vivo microscopic observation. Laser stimulation of the cells was performed using the 647 nm line of the confocal laser through the objective lens of the microscope. Mitochondrial membrane potential (delta psi(m)), intracellular pH, calcium alterations and generation of reactive oxygen species (ROS) were monitored using specific fluorescent vital probes. The induced effects were quantified using digital image processing techniques. After laser irradiation, a gradual alkalinization of the cytosolic pH and an increase in mitochondrial membrane potential were observed. Recurrent spikes of intracellular calcium concentration were also triggered by laser. Reactive oxygen species were generated as a result of biostimulation. No such effects were monitored in microscopic fields other than the irradiated ones.

Microscopical examination of the localisation patterns of two novel rhodamine derivatives in normal and neoplastic colonic mucosa

Tissue characterisation by fluorescence imaging, using exogenous fluorophores, is a promising method for cancer detection. Histochemical alterations in the composition of mucins, when neoplastic transformations occur, could be exploited to derive more selective fluoroprobes indicative of early malignant transformation. The aim of this work was to develop and examine tumour selective fluoroprobes for colon cancer diagnosis, as well as to determine the morphological components where selective dye accumulation has occurred. Two novel fluoroprobes: rhodamine B-L-leucine amide and rhodamine B-phenylboronic acid were synthesised and examined together with Mayer's mucicarmine, alexa 350-wheat germ agglutinin (WGA) and tetramethyl rhodamine-concanavalin A (ConA). Fluorescence microscopy studies were performed with deparaffinised human colon sections, using an epifluorescence microscope equipped with a colour CCD camera. The intense accumulation of the novel fluoroprobes was localised in the amorphous material in the lumen of neoplastic crypts. To gain insight into the localisation patterns, mucicarmine, alexa 350-WGA and tetramethyl rhodamine-ConA were used. Alexa 350-WGA reacted primarily with mucin secreted in the malignant crypt lumen suggesting that this material is rich in sialic acid and N-acetylglucosaminyl residues. These derivatives clearly and consistently distinguished non-neoplastic from neoplastic human colon tissue sections. The intense accumulation at the altered mucins indicates that they could be used as fluoroprobes of biochemical alterations for carcinoma detection.

Relatively low red cell folate levels and acute coronary syndromes

BACKGROUND

Low folate levels are related to increased risk for coronary artery disease in humans, while experimental work has shown that folate deficiency is thrombogenic. We hypothesized that relatively low folate levels are related to the development of acute coronary syndromes in patients with previously stable coronary artery disease.

METHODS

One hundred and forty-one men were studied: 53 consecutive patients with acute coronary syndromes, 41 with stable coronary artery disease and 47 control participants. Known clinical and lipid risk factors were identified in all subjects and in addition plasma B12, plasma and red cell folate levels were measured.

RESULTS

Red cell folate levels were significantly lower in patients with acute coronary syndromes (510+/-178 nmol/l) than in both stable coronary artery disease patients (638+/-264 nmol/l, P< 0.005) and controls (615+/-193 nmol/l, P< 0.05 respectively). Plasma folate and B12 levels were similar in all three groups. Multiple logistic regression analysis identified red cell folate levels as the only independent predictor of acute coronary events in the whole population of patients with known coronary artery disease and in the subgroup of non-smokers (P=0.010 and P=0.031).

CONCLUSIONS

The present study suggests that relatively low red cell folate levels are associated with acute coronary syndromes and are an independent predictor of acute coronary events.

Receptorphin: a conserved peptide derived from the sequence of the opioid receptor, with opioid displacement activity and potent antiproliferative actions in tumor cells

BACKGROUND

In addition to endogenous opioids, a number of peptide sequences, derived from endogenous (hemorphins, alphaS1-casomorphin), and exogenous proteins (casomorphins, exorphins) have been reported, possessing opioid activity. In the present work, we report the identification of a new peptide, receptorphin (Tyr-Ile-Phe-Asn-Leu), derived from the sequence of the second transmembrane loop of the opioid receptor. This sequence is unique for the opioid receptor, and conserved in all species and receptor-types.

RESULTS AND DISCUSSION

Receptorphin competes for opioid binding, presenting a kappa-receptor interaction, while it binds equally to delta- and mu- opioid and somatostatin-binding sites, and inhibits the cell proliferation of a number of human cancer cell lines, in a dose-dependent and reversible manner, at the picomolar or the nanomolar range. Receptorphin shows a preferential action on prostate cancer cells.

CONCLUSION

Our work identifies, for the first time a peptide, in a receptor sequence, possessing ligand-agonistic activities. A hypothesis, based on receptorphin liberation after cell death, is presented, which could tentatively explain the time-lag observed during opioid antiproliferative action.

Texture analysis of fluorescence microscopic images of colonic tissue sections

The aim of this study was to assess the potential of texture analysis for the characterization of fluorescence images from colonic tissue sections stained with a novel and selective fluoroprobe, Rhodamine B-phenylboronic acid. Fluorescence microscopy images of colonic healthy mucosa (n = 35) and adenocarcinomas (n = 35) were digitally captured and subjected to image texture analysis. Textural features derived from the grey level co-occurrence matrix were calculated. A modified version of the multiple discriminant analysis criterion was used to choose an appropriate subset of features. A minimum Mahalanobis distance, linear discriminant classifier and a simple evaluation 'score' method were used to classify image feature data into the two categories. A subset of four textural features was selected and used for the description and classification of each image field. They were found appropriate to correctly classify 95% of the images into the two classes, using two different classifiers. These features contained information about local homogeneity and grey level linear dependencies of the image. This study demonstrated that texture analysis techniques could provide valuable diagnostic decision support in a complex domain such as colorectal tissue.

Somatostatin and opioid receptors in mammary tissue. Role in cancer cell growth

Somatostatin and opioid systems, are the two main inhibitory systems in mammals. Both classes of substances have been identified in normal and malignant mammary gland, as well as their cognitive receptors. They have been implied in the inhibition of cell growth of cancer cells and cell lines, in a dose-dependent and reversible manner. Somatostatin acts through homologous receptors (SSTRs), belonging to five distinct classes (SSTR1-5). We, and others have identified SSTR2 and 3 as been the only SSTRs present in the breast. Furthermore, opioids act through the three classes of opioid receptors (mu, delta,kappa). In the breast, kappa opioid receptor subtypes (kappa 1-kappa 3) are the most widely expressed. We further have shown that opioids, in addition to their binding to opioid receptors, compete for binding to SSTRs. This functional interaction, together with other identified modes of opioid action in the breast (modulation of steroid receptors, proteases' secretion, interaction with cytoskeletal elements), will be discussed, taking into consideration also the possible local production of casomorphins (casein-derived opioids), which are very potent antiproliferative agents.

Agents facilitating the electric field-induced fusion of intact rabbit erythrocytes

In the recent years, the role of specific membrane active agents in the electrofusion process has started to draw attention, and it has been found that the presence of various substances in the cell medium can affect the fusion process either in a positive or negative way. In this work, the effect of several proteins, bivalent cations and antibiotics was tested with respect to their ability to protect intact erythrocytes from hemolysis and facilitate the fusion process. The effect of different sugars was also studied. Among the different proteins, pronase and proteinase were found to be the most effective. With respect to bivalent cations, Ca2+ and Mn2+ were more effective while Mg2+ was less important. From the antibiotics, penicillin caused a negative effect while streptomycin acted positively. Finally, glucose medium was found to be the most effective compared to all sugars tested. The results indicated that there are strong differentiations of the induced effects caused by each substance, and some possible mechanisms of action of these agents on the erythrocyte membrane were discussed.

The use of soft and flexible guidewires in the treatment of chronic total coronary occlusions by activated guidewire angioplasty

Activated guidewire angioplasty (AGA) is a new technique which has been designed to assist in angioplasty of total occlusions. The purpose of this study was to determine the safety and efficacy of using flexible relatively soft guidewires (floppy wires) in conjunction with this technique and also to determine the predictors of lesion crossing and final success by this technique in patients with chronic total coronary occlusions. 73 patients with 73 chronic total coronary occlusions in whom coronary angioplasty using conventional techniques had failed were treated with AGA using floppy guidewires. The success of crossing these lesions was 65.7% (48/73) resulting in a final angioplasty success of 56.1% (41/73). Angioplasty success was reduced compared with crossing success in seven arteries in which complications occurred during balloon angioplasty. Multiple stepwise logistic regression analysis identified the location of the occlusion (right coronary artery, p = 0.005) as independent predictor of crossing success of this technique and the male gender (p = 0.03), the duration of occlusion (p = 0.05), the lesion length (p = 0.01) and the location of the occlusion (right coronary artery, p = 0.02) as independent predictors of final procedural success of the method.

Use of vibrational angioplasty for the treatment of chronic total coronary occlusions: preliminary results

The aim of the study was to investigate the feasibility and clinical safety of vibrational angioplasty in the treatment of chronic total coronary occlusions and evaluate the clinical and angiographic factors that are predictive of the procedural success and complications of the procedure. Seventy-eight patients with chronic total occlusions (>3 months) resistant to conventional techniques were treated by vibrational angioplasty using a variety of conventional guidewires. Lesions were successfully crossed in 67 (85.9%) cases and antegrade flow was achieved in 59 (75.5%). Major complications (myocardial infarction and tamponade) occurred in two (2.5%) patients, but no fatalities ensued. Angiographically detectable dissections were seen in 23 (29.5%) patients but only resulted in vessel compromise and reclosure in 5 cases. Multiple stepwise logistic regression analysis identified the duration (<6 months, P = 0.008) and the length of the occlusion (<15 mm, P = 0.03) as independent predictors of final success and the age of the patient (<55 years, P = 0.006) as the only independent predictor of procedural complications. Vibrational angioplasty is a safe technique useful in the treatment of chronic coronary occlusive disease. Patients in whom the procedure is likely to prove most successful may be easily identified by clinical and angiographic features (duration and length of occlusion).

Loading of intact rabbit erythrocytes with fluorophores and the enzyme pronase by means of electroporation

The application of electric field pulses in cell suspensions is known to alter membrane integrity, resulting in increased membrane permeabilization. This field-induced membrane poration provides the means to load cells with a variety of external substances, useful for clinical applications. In this work, intact rabbit erythrocytes were successfully loaded with low molecular weight fluorescent probes and with the high molecular weight enzyme pronase, which has been shown to mimic the effects of insulin. Attachment of the enzyme onto the cell surface was also achieved by modifying the applied pulse parameters. Both applications were efficient and accompanied by high cell survival rates. In this way, biological carriers loaded with active substances were produced, offering the potentials for useful clinical applications, either for diagnostic or therapeutic purposes.

Identification of a novel opioid peptide (Tyr-Val-Pro-Phe-Pro) derived from human alpha S1 casein (alpha S1-casomorphin, and alpha S1-casomorphin amide)

A new casomorphin pentapeptide (alpha S1-casomorphin) has been isolated from the sequence of human alpha S1-casein [alpha S1-casein-(158-162)], with the sequence Tyr-Val-Pro-Phe-Pro. This peptide was found to bind with high affinity to all three subtypes of the kappa-opioid receptor (kappa 1-kappa 2). When amidated at the C-terminus, alpha S1-casomorphin amide binds to the delta- and kappa 3-opioid sites. Both alpha S1-casomorphin and its amide inhibit in a dose-dependent and reversible manner the proliferation of T47D human breast cancer cells. This anti-proliferative activity was greater for alpha S1-casomorphin, which was the most potent opioid in inhibiting T47D cell proliferation. In T47D breast cancer cells, other casomorphins have been found to bind to somatostatin receptors in addition to opioid sites. In contrast, alpha S1-casomorphin and its amide do not interact with somatostatin receptors in our system.

Photodynamic effects of hypericin on photosynthetic electron transport and fluorescence of Anacystis nidulans (Synechococcus 6301)

We investigated the photodynamic action of hypericin, a natural naphthodianthrone, on photosynthetic electron transport and fluorescence of the cyanobacterium Anacystis nidulans (Synechococcus 6301). The most drastic effect was the inactivation of photosynthetic oxygen evolution in the presence of the electron acceptor phenyl-p-benzoquinone in aerobic cells which required 1 hypericin/5 chlorophyll a for half-maximal effect. Anaerobic A. nidulans was only partially inactivated and variable chlorophyll a fluorescence remained unperturbed suggesting that photoreaction center II was not a target. Further, hypericin, stimulated photoinduced oxygen uptake in the presence of methylviologen in aerobic cells. This action was less specific than the inactivation of oxygen evolution (1 hypericin/0.5-0.7 chlorophyll a for half-maximal effect). Results point to the involvement of molecular oxygen in two ways. Type I mechanism (Henderson BW and Dougherty TJ (1992) Photochem Photobiol 55: 145-157) in which ground state oxygen reacts with excited substrate triplets appears probable for the inactivation of oxygen evolution. On the other hand, Type II mechanism in which excited oxygen singlets react with ground state substrate molecules appears probable in the stimulation of methylviologen mediated oxygen uptake.

Interpretation of diagnostic implications of fluorescence parameters for atherosclerosis in fibrous, calcified and normal arteries

Fluorescence spectroscopy presents great interest for the diagnosis of atherosclerosis. Nevertheless there are some difficulties in the interpretation of diagnostic information. This could be overcome by precise methods of extraction of the diagnostic parameters and convenient statistical analysis, which are the subject of this work. Fluorescence excitation-emission matrices from different categories of coronary arteries were developed and used to derive the optimum excitation wavelength on the one hand and to assign the spectra to specific chromophores on the other hand. Simple dimensionless functions (Fi) were formed by the ratio of the intensities at selected wavelength and the logistic model was used for statistical analysis. Decision surfaces were drawn and it was estimated that the probability of correct classification is 88%. The algorithm correctly diagnoses 97% of healthy from diseased samples and 80% of fibrous from calcified coronary arteries.

Wide geographic variations of sensitivity to MOTT sensitins in Greece

Several studies have suggested that large bodies of water are a main source of infection with mycobacteria other than tuberculosis (MOTT). If this is correct, there should be a gradient in the infection rate with MOTT between mountainous and seaside areas. To test this hypothesis, we performed skin testing with tuberculin and sensitins in 19,470 Greek Armed Forces recruits. Initially, several MOTT sensitins were used, but when it became clear that the Mycobacterium scrofulaceum sensitin was the most appropriate, the study was continued with it alone in 17,403 recruits. Finally, in order to evaluate the geographical distribution of sensitivity to sensitins, we studied the results of 8,507 of these recruits living in or near their birthplace. They were divided into three geophysical areas: seaside 3,389 recruits; mountains 2,692 recruits; and inland plains 2,426 recruits. MOTT sensitivity rates were 4.1% in mountainous areas and 7.1% in seaside areas. All small Aegean islands had high MOTT rates (above 8%). In inland plains, high MOTT rates (above 8%) were observed among those living near big rivers. This geographical distribution of MOTT sensitivity supports the theory that large bodies of water are a main source of infection with MOTT.

Wide geographic variations of sensitivity to MOTT sensitins in Greece

Several studies have suggested that large bodies of water are a main source of infection with mycobacteria other than tuberculosis (MOTT). If this is correct, there should be a gradient in the infection rate with MOTT between mountainous and seaside areas. To test this hypothesis, we performed skin testing with tuberculin and sensitins in 19,470 Greek Armed Forces recruits. Initially, several MOTT sensitins were used, but when it became clear that the Mycobacterium scrofulaceum sensitin was the most appropriate, the study was continued with it alone in 17,403 recruits. Finally, in order to evaluate the geographical distribution of sensitivity to sensitins, we studied the results of 8,507 of these recruits living in or near their birthplace. They were divided into three geophysical areas: seaside 3,389 recruits; mountains 2,692 recruits; and inland plains 2,426 recruits. MOTT sensitivity rates were 4.1% in mountainous areas and 7.1% in seaside areas. All small Aegean islands had high MOTT rates (above 8%). In inland plains, high MOTT rates (above 8%) were observed among those living near big rivers. This geographical distribution of MOTT sensitivity supports the theory that large bodies of water are a main source of infection with MOTT.

Purification to homogeneity of an active opioid receptor from rat brain by affinity chromatography

Active opioid binding proteins were solubilized from rat brain membranes in high yield with sodium deoxycholate in the presence of NaCl. Purification of opioid binding proteins was accomplished by opioid antagonist affinity chromatography. Chromatography using the delta-opioid antagonist N,N-diallyl-Tyr-D-Leu-Gly-Tyr-Leu attached to omega-aminododecyl-agarose (Affi-G) (procedure A) yielded a partially purified protein that binds selectively the delta-opioid agonist [3H]Tyr-D-Ser-Gly-Phe-Leu-Thr ([3H]DSLET), with a Kd of 19 +/- 3 nM and a Bmax of 5.1 +/- 0.4 nmol/mg of protein. Subsequently, Lens culinaris agglutinin-Sepharose 4B chromatography of the Affi-G eluate resulted in isolation of an electrophoretically homogeneous protein of 58 kDa that binds selectively [3H]DSLET with a Kd of 21 +/- 3 nM and a Bmax of 16.5 +/- 1.0 nmol/mg of protein. Chromatography using the nonselective antagonist 6-aminonaloxone coupled to 6-aminohexanoic acid-Sepharose 4B (Affi-NAL) (procedure B) resulted in isolation of a protein that binds selectively [3H]DSLET with a Kd of 32 +/- 2 nM and a Bmax of 12.4 +/- 0.5 nmol/mg of protein, and NaDodSO4/PAGE revealed a major band of apparent molecular mass 58 kDa. Polyclonal antibodies (Anti-R IgG) raised against the Affi-NAL protein inhibit the specific [3H]DSLET binding to the Affi-NAL eluate and to the solubilized membranes. Moreover, the Anti-R IgG inhibits the specific binding of radiolabeled Tyr-D-Ala-Gly-N-methyl-Phe-Gly-ol (DAMGO; mu-agonist), DSLET (delta-agonist), and naloxone to homogenates of rat brain membranes with equal potency. Furthermore, immunoaffinity chromatography of solubilized membranes resulted in the retention of a major protein of apparent molecular mass 58 kDa. In addition, immunoblotting of solubilized membranes and purified proteins from the Affi-G and Affi-NAL matrices revealed that the Anti-R IgG interacts with a protein of 58 kDa.

Photolabile opioid derivatives of D-Ala2-Leu5-enkephalin and their interactions with the opiate receptor

Photolabile derivatives of D-Ala2-Leu5-enkephalin were prepared by synthetic procedures in which a 2-nitro-4-azidophenyl group is linked to the terminal carboxyl group of the enkephalin by means of an ethylenediamine or ethylenediamine beta-alanine spacer. These peptides bind to opiate receptors with nanomolar affinities and inhibit electrically stimulated contractions of the mouse vas deferens and adenylate cyclase activity of NG108-15 neuroblastoma x glioma hybrid cell membranes. Both inhibitions are reversed by the opiate antagonist naloxone. Photolysis of the ligands bound to rat brain membranes results in the loss of approximately 50% of the receptor sites. This decrease in receptor number is blocked by naloxone and requires light. A photolabile [3H]enkephalin derivative labels an equivalent number of sites under similar irradiation conditions.

Opioid activities and structures of alpha-casein-derived exorphins

Exorphins, peptides with opioid activity, have previously been isolated from pepsin hydrolysates of alpha-casein [Zioudrou, C., Streaty, R. A., & Klee, W. A. (1979) J. Biol. Chem. 254, 2446-2449]. Analysis of these peptides shows that they correspond to the sequences 90-96, Arg-Tyr-Leu-Gly-Tyr-Leu-Glu, and 90-95, Arg-Tyr-Leu-Gly-Tyr-Leu, of alpha-casein. These peptides, as well as two of their analogues Tyr-Leu-Gly-Tyr-Leu-Glu (91-96) and Tyr-Leu-Gly-Tyr-Leu (91-95), have now been synthesized and characterized. Their opioid activity was examined by three different bioassays: (a) displacement of D-2-alanyl[tyrosyl-3,5-3H]enkephalin-(5-L-methioninamide) and [3H]dihydromorphine from rat brain membranes; (b) naloxone-reversible inhibition of adenylate cyclase in homogenates of neuroblastoma x glioma hybrid cells; (c) naloxone-reversible inhibition of electrically stimulated contractions of the mouse vas deferens. The synthetic peptide of sequence 90-96 was the most potent opioid in all three bioassays and its potency was similar to that of the isolated alpha-casein exorphins. The synthetic peptides were totally resistant to hydrolysis by trypsin and homogenates of rat brain membranes, but were partially inactivated by chymotrypsin and subtilisin. The difference in opioid activity of alpha-casein exorphins may be related to differences in conformational flexibility observed by NMR spectroscopy.

Photolabile ligands for opiate receptors

The 2-nitro-4-azidophenyl(NAP)-D-Ala2-Leu5-Enkephalin derivatives: Try-D-Ala-Gly-Phe-Leu CONCH2CH2NH-NAP (E-NAP-EDA) and Try-D-Ala-Gly-Phe-Leu CONCH2CH2NH-COCH2CH2NHNAP(E-NAP- -Ala-EDA) were synthesized by conventional peptide methods. Their structure was determined by amino acid analysis, ultra violet, visible and infra red spectroscopy. Both peptides were shown a) to bind with high affinity to the opiate receptors of rat brain membranes and b) to inhibit strongly the contractions of electrically stimulated vas deferens and the adenyl cyclase of the NG 108-15 cell membranes. These effects were reversed by the antagonist naloxone. Photoloysis of the rat brain membranes-(E-NAP- -Ala-EDA) complex caused a 20-30% inactivation of the opiate receptors. Inactivation was prevented when the complex was irradiated in the presence of naloxone. The radio-labeled derivatives of these enkephalin analogs may prove useful photochemical labels of the opiate receptor.