Correlation of subcellular and intratumoral photosensitizer localization with ultrastructural features after photodynamic therapy

Photodynamic therapy (PDT) of cancer typically involves systemic administration of tumor-localizing photosensitizers followed 48-72 h later by exposure to light of appropriate wavelengths. Knowledge about the distribution of photosensitizers in tissues is still fragmentary. In particular, little is known as to the detailed localization patterns of photosensitizers in neoplastic and normal tissues as well as the relationship between such patterns and the actual targets for the photosensitizing effect. This review focuses on ultrastructural features seen in treated cells and tumors. An attempt is made to correlate these findings with the subcellular/intratumoral localization pattern of the photosensitizers in tumor cell lines in vitro and in tumor models in vivo. Several subcellular sites are main targets of PDT with different sulfonated aluminum phthalocyanines (AIPcSn) in the human tumor cell line LOX. Nuclei are not among the primary targets. Overall, the ultrastructural changes correlate well with the data about the subcellular localization patterns for each analogue of AIPcSn in the same cell line. Similar findings are also obtained for the family of sulfonated mesotetraphenylporphines (TPPSn) in the NHIK 3025 cell line. The mechanisms involved in the killing of tumors by PDT seem to be a complex interplay between direct and indirect (via vascular damage) effects on neoplastic cells according to the intratumoral localization pattern of the applied dye. Several factors can affect the localization pattern of a drug, such as its chemical character, the mode of drug delivery, the time interval between drug administration and light exposure, and tumor type. Furthermore, whether local immune reactions (such as macrophages) and apoptosis (programmed cell death) are involved in the destruction of neoplastic cells by PDT in vivo is still an enigma. A general model for PDT-induced tumor destruction is suggested.     

Investigation of the role of 5-HT3 receptors in the secretion of prolactin, ACTH and renin

Photodynamic therapy using i.v. injected porphyrin photosensitizers have been used to treat selected cases of superficial bladder cancer. Since cutaneous photosensitivity, lasting 6-8 weeks, is a well known undesirable side effect of this therapy, we instilled the photosensitizers intravesically in rats and compared the uptake of photosensitizers in different tissues by this route of administration with the uptake after intravenous injection. The intravesical mode of delivery enhanced photosensitizer uptake in the bladder wall, while giving low concentrations in extravesical organs. Intravesical instillation of the photosensitizers may therefore increase their efficacy and reduce phototoxicity as compared with intravenous injection. Comparing the results obtained by two assays, one based on porphyrin fluorescence and the other based on the application of radioactively labelled photosensitizers, it was concluded that the i.v. administration route may result in tissue uptake of significant amounts of aggregated non-fluorescent, supposedly inactive drug, while the intravesical administration led to less uptake of aggregates relative to active drug monomers.     

Effect of lipoproteins on cultured human mesangial cells

It was recently reported that low-density lipoprotein (LDL) promotes mesangial cell proliferation, and oxidized LDL is cytotoxic for mesangial cells. However, there have been few studies about the effects of other lipoproteins on mesangial cells. Accordingly, we investigated the effect of various lipoproteins on cultured human mesangial cells using 3H-thymidine (3H-TdR) incorporation and cell counting assays. We also investigated the levels of several cytokines in mesangial cell culture supernatants after stimulation by the lipoproteins. Addition of very-low-density lipoprotein (VLDL) at concentrations up to 100 micrograms/mL, intermediate-density lipoprotein (IDL) at up to 50 micrograms/mL, and LDL at up to 50 micrograms/mL induced the proliferation of cultured human mesangial cells, whereas cell growth was inhibited at higher concentrations. Oxidized LDL caused a concentration-dependent decrease of 3H-TdR incorporation. High-density lipoprotein (HDL) had no proliferative effective effect at any concentration. Exposure to VLDL, IDL, LDL, or a high concentration of HDL enhanced the secretion of interleukin-6, platelet-derived growth factor, and transforming growth factor-beta by mesangial cells, whereas tumor necrosis factor-alpha secretion was stimulated by oxidized LDL. These finding indicate that triglyceride (TG)-rich lipoproteins (VLDL and IDL) promote mesangial cell proliferation as well as LDL, whereas oxidized LDL has the reverse effect. These effects of lipoproteins may be related to modulation of various cytokines. Accordingly, TG-rich lipoproteins, LDL, and oxidized LDL may be involved in mesangial cell proliferation and injury in patients with mesangial proliferative glomerulonephritis.     

Comparison of two indices of caries patterns in 3-6 year old Brazilian children from areas with different fluoridation histories

The interactions of sulfonated chloroaluminum phthalocyanine (AlPcSn) with human low-density lipoproteins (LDL) were studied in vitro in human plasma and in an isolated LDL fraction, in order to understand the potential effects of the sensitizer against LDL. The AlPcSn added to plasma distributes in all lipoproteins as observed by the drastic color changes of the separated fractions by ultracentrifugation. In isolated LDL, incubation with AlPcSn causes fluorescence quenching of the apoprotein tryptophan residues. Furthermore, AlPcSn incorporates in liposomes, with a lipid composition similar to the external monolayer of human LDL, as indicated by absorbance spectroscopy. The photosensitizing properties of AlPcSn in LDL particles were studied on the basis of the fluorescence quenching of previously incorporated cis-parinaric acid (PnA), used as an oxidation probe, and of O2 consumption. The photooxidation of either PnA or LDL lipids is highly dependent on irradiation time and on the dye concentration. Moreover, photooxidation of LDL proceeds only during the illumination period. After stopping the illumination and upon addition of Cu2+ to the LDL solution, the oxidative rate is resumed, probably due to hydroperoxide cleavage and formation of species able to propagate the oxidative reaction. Thus, our data indicate that AlPcSn distributes in human plasma lipoproteins and, in isolated LDL, it can interact either with the lipid phase or the apoprotein. The photooxidation of LDL induced by AlPcSn seems to involve singlet oxygen as the main reactive species in the degradative process.     

Chloroaluminum sulfonated phthalocyanine partitioning in normal and intimal hyperplastic artery in the rat. Implications for photodynamic therapy

Photodynamic therapy, the light activation of photosensitizers into cytotoxic mediators, has been a successful treatment for experimental intimal hyperplasia (IH). To understand the basis of the photosensitizer chloroaluminum sulfonated phthalocyanine (CASPc)-mediated photoinhibition of intimal hyperplasia in the rat common carotid artery model, we studied photosensitizer partitioning in hyperplastic as compared to normal arterial tissue. Serum clearance of CASPc is exponential with, a half-life of 300 minutes. Laser-induced fluorescence and spectrofluorimetric analyses of artery tissue demonstrated an approximately 60% lower uptake and retention of CASPc by normal arterial tissue as compared to arteries with IH; the differences become more pronounced at 24 h. Fluorescent microscopy of arterial tissue demonstrated increased uptake of the CASPc by the artery with IH. However, by 24 h it is primarily the IH tissue that has retained the CASPc, with clearance of the dye from the media of normal or hyperplastic arteries. These data demonstrate that IH, like neoplastic tissue, has an increased accumulation of CASPc compared to normal artery. The preferential partitioning into hyperplastic tissue has implications for therapeutic targeting of this cellular population with photodynamic therapy.     

The RAD52 epistasis group in mammalian double strand break repair

The receptor-mediated transfer of lipids between cells and lipoproteins plays an important role in lipoprotein metabolism and cardiovascular disease. Although there have been many valuable studies of HDL binding to tissues, cells and membranes, and of the potential role of such binding in the transport of lipids between HDL and cells, much less is known about HDL receptors than about receptors for other lipoproteins (e.g. LDL, chylomicrons, vitellogenin). Here we review recent studies of the class B, type I scavenger receptor, which appears to be a physiologically relevant, cell surface HDL receptor that mediates the selective uptake of lipids by cells.     

Update on antitumor pharmacology: reality and perspectives in 1998]

Tubulointerstitial changes, characterized by the accumulation of extracellular matrix proteins (ECM) and fibrosis, are often associated with primary glomerular injury. Furthermore, these changes may be better prognostic indicators for decline in renal function than the anatomical changes seen within the glomerulus itself. Although hyperlipidemia and the increased renal accumulation of atherogenic lipoproteins are commonly seen in both human and experimental models of renal disease, the possible role that atherogenic lipoproteins may play in the cellular and molecular events associated with the development of tubulointerstitial injury remains unclear. Since atherogenic lipoproteins have been shown to be mediators of renal injury, we examined the effects of native LDL and oxidatively-modified LDL (ox-LDL, a more atherogenic form of LDL) on fibronectin protein synthesis and gene expression in proximal tubular epithelial cells (TEC). Human LDL was freshly isolated and ox-LDL prepared by incubation of LDL with 100 microM CuS04. Incubation of TEC with LDL or ox-LDL (25-50 micrograms/ml) for 24 h increased the steady-state mRNA expression of fibronectin by 16-135% over control as measured by Northern blot analysis and the effect was greater with ox-LDL than native LDL. Additional studies were done to examine whether the increased fibronectin message in response to lipoprotein activation was translated into TEC protein synthesis. The activation of TEC by LDL or ox-LDL stimulated the synthesis and secretion of fibronectin (52-150%, over control) as measured by Western blot analysis. The data show that LDL and ox-LDL stimulate TEC fibronectin gene message and protein synthesis supporting a pathobiological role for these atherogenic lipoproteins in tubulointerstitial fibrosis.     

Effect of hyperosmotic solutions on human brain tumour vasculature

Reversible opening of the blood-brain barrier (BBB) has been used to increase delivery of chemotherapeutic agents into brain tumours, but it is complicated and requires general anaesthesia. Without affecting the normal BBB, and avoiding the complications of BBB modification by hyperosmotic solution, we tried an adequate minimal BBB disruption in brain tumours. Although the effect of BBB disruption on normal brain has been described, there are no reports of the effect of an impaired BBB on microcirculation. In this study, four patients underwent surgical resection of a glioblastoma multiforme (GM; n = 1), astrocytoma (n = 2), or metastatic brain tumour (n = 1). Epicerebral microcirculation was observed in the operative field. Serial fluorescein microangiograms of the tumour and peritumoural area were obtained before and after BBB disruption was introduced intra-operatively by retrograde infusion of mannitol introducing a catheter via the temporal superficial artery back to the carotid bifurcation. On the initial microangiogram, staining by the fluorescein dye was observed in the GM and metastatic tumour but not in the astrocytoma; no extravasation of fluorescein dye was observed in the peritumoural areas. After BBB disruption, fluorescein perfusion increased and extravasation of fluorescein dye from the venules was observed in the GM and the metastatic tumour and in the peritumoural area of both lesions; BBB disruption started from venules in the peritumoural area without affecting the normal brain. However, such effects were not observed in the astrocytomas after BBB disruption nor in normal brain tissue in any patient. It appears that the integrity of the BBB is less stable in the peritumoural area of GM and metastatic brain tumours than it is in astrocytomas or normal brain. Osmotic BBB disruption may offer a method for achieving global delivery of therapeutic agents to brain tumours and peritumoural areas.     

Photodynamic therapy with local photosensitizer delivery inhibits experimental intimal hyperplasia

BACKGROUND: Photodynamic therapy (PDT), the light activation of photosensitizer dyes for the production of free radicals, effectively inhibits experimental intimal hyperplasia with systemic administration of the photosensitizer. The local application of the photosensitizer directly into a vascular lesion to avoid systemic side effects and tightly control dose administration has theoretical appeal. The aim of this study was to quantify serum and arterial tissue uptake after site-specific photosensitizer delivery and, following PDT, determine its effectiveness at inhibiting intimal hyperplasia. STUDY DESIGN/MATERIALS AND METHODS: The rat common carotid artery was balloon-injured, pressurized at 400 mm Hg for 2 minutes with the photosensitizer dye benzoporphyrin-derivative (BPD), and irradiated with 690 nm laser light at a fluence of 100 J/cm2. Control animals were pressurized with saline only, or received no additional treatment than balloon-injury. RESULTS: Pressurization with BPD resulted in complete penetration of the intima and media and was associated with relatively high tissue, but almost no detectable serum BPD concentrations. No skin photosensitization or other systemic side effects were observed with photosensitizer administration. After 9 days, PDT-treated arteries displayed a significantly lower number of smooth muscle cells in the arterial wall than balloon-injured (P < 0.001) or saline-pressurized arteries (P < 0.0002), and no intimal hyperplasia. At 21 days, IH after PDT was significantly reduced as compared with balloon-injured (P < 0.0004), or saline-pressurized arteries (P < 0.003) with no arterial dilatation. CONCLUSIONS: Site-specific delivery of liposomal BPD followed by PDT represents a safe method to treat arteries, and may be effectively used in vivo to inhibit the development of intimal hyperplasia.     

Bacterial lipopolysaccharide binds and stimulates cytokine-producing cells before neutralization by endogenous lipoproteins can occur

Lipoproteins are able to bind to lipopolysaccharide (LPS) and neutralize its deleterious effects. However, it is not clear why the LPS-binding capacity of circulating lipoproteins, which is 10- to 10 000-fold above the maximal LPS concentrations found in septic patients, is not sufficient to inhibit the effects of LPS during an infection, whereas infusion of exogenous lipoproteins has a potent inhibitory action. In this study, the kinetics of LPS-neutralization by VLDL, LDL, and HDL were investigated, at lipoprotein-to-LPS ratios found in severe Gram-negative sepsis. At least 4-8-h preincubation of LPS with either LDL or HDL were necessary to inhibit 50% of the LPS-induced TNF-alpha production by human peripheral blood mononuclear cells (PBMC), whereas after 24 h of preincubation LDL or HDL strongly inhibited the TNF-alpha synthesis (70-90%, P<0.01). VLDL was the least effective lipoprotein fraction. In contrast, FITC-LPS bound to PBMC much more rapidly, with 70% of the total binding after 30 min, and 90% after 1-h incubation. The increase of LDL or HDL concentrations up to 10-fold (as in experimental models of hyperlipoproteinaemia) was able not only to further decrease TNF-alpha production after long LPS-lipoproteins preincubation periods, but also to improve the kinetics of LPS neutralization. In conclusion, LPS binds and stimulates the mononuclear cells in circulation before neutralization by endogenous lipoproteins can occur. Additional increase in the lipoprotein-to-LPS molar ratio (e.g. by infusion of exogenous lipoproteins) accelerates the kinetics of LPS neutralization, and may be useful as adjunctive therapy in severe Gram-negative infections.     

Secretory sphingomyelinase, a product of the acid sphingomyelinase gene, can hydrolyze atherogenic lipoproteins at neutral pH. Implications for atherosclerotic lesion development

The subendothelial aggregation and retention of low density lipoprotein (LDL) are key events in atherogenesis, but the mechanisms in vivo are not known. Previous studies have shown that treatment of LDL with bacterial sphingomyelinase (SMase) in vitro leads to the formation of lesion-like LDL aggregates that become retained on extracellular matrix and stimulate macrophage foam cell formation. In addition, aggregated human lesional LDL, but not unaggregated lesional LDL or plasma LDL, shows evidence of hydrolysis by an arterial wall SMase in vivo, and several arterial wall cell types secrete a SMase (S-SMase). S-SMase, however, has a sharp acid pH optimum using a standard in vitro SM-micelle assay. Thus, a critical issue regarding the potential role of S-SMase in atherogenesis is whether the enzyme can hydrolyze lipoprotein-SM, particularly at neutral pH. We now show that S-SMase can hydrolyze and aggregate native plasma LDL at pH 5.5 but not at pH 7.4. Remarkably, LDL modified by oxidation, treatment with phospholipase A2, or enrichment with apolipoprotein CIII, which are modifications associated with increased atherogenesis, is hydrolyzed readily by S-SMase at pH 7.4. In addition, lipoproteins from the plasma of apolipoprotein E knock-out mice, which develop extensive atherosclerosis, are highly susceptible to hydrolysis and aggregation by S-SMase at pH 7.4; a high SM:PC ratio in these lipoproteins appears to be an important factor in their susceptibility to S-SMase. Most importantly, LDL extracted from human atherosclerotic lesions, which is enriched in sphingomyelin compared with plasma LDL, is hydrolyzed by S-SMase at pH 7.4 10-fold more than same donor plasma LDL, suggesting that LDL is modified in the arterial wall to increase its susceptibility to S-SMase. In summary, atherogenic lipoproteins are excellent substrates for S-SMase, even at neutral pH, making this enzyme a leading candidate for the arterial wall SMase that hydrolyzes LDL-SM and causes subendothelial LDL aggregation.     

有机染料敏化TiO_2纳米薄膜太阳能电池研究进展

染料敏化TiO2纳米薄膜太阳能电池是一种新型太阳能电池,其结合了有机染料光敏剂和无机半导体的优势,具有较宽的光谱响应范围,制造工艺简单,成本较低,绿色环保,是国内外研究的热点。本文介绍了染料敏化纳米薄膜太阳能电池的结构和工作原理,并对其组成要素如染料敏化、TiO2纳米膜、电解质等最新研究进展进行了简述。     

Cholesterol or triglyceride loading of human monocyte-derived macrophages by incubation with modified lipoproteins does not induce tissue factor expression

Macrophages/foam cells localized in cholesterol- and triglyceride-rich regions of atherosclerotic plaques express high levels of tissue factor (TF), the essential cofactor and receptor of factor VIIa. It is not clear whether modified lipoproteins, for which several agonistic effects on macrophages have been described, are independent stimuli of TF expression in these cells. Therefore, we studied the effect of short-term (1 day) and long-term (4 to 7 days) incubation of human monocyte-derived macrophages cultured in suspension with modified and native LDLs or VLDLs on the expression of TF mRNA, antigen, and activity. We used native LDL or VLDL, moderately oxidized LDL or VLDL, severely oxidized LDL or VLDL, acetylated LDL, and beta-VLDL at a protein concentration of 100 microg/mL. Cholesterol loading occurred within 9 hours after the addition of acetylated LDL and continued during long-term incubation. Incubation of severely oxidized LDL for 7 days resulted in a slight increase in cholesterol content. Triglyceride loading was observed during short-term and long-term incubation with native and modified VLDLs. Neither cholesterol nor triglyceride loading resulted in expression of TF. Bacterial LPS still could induce TF expression in lipid-laden macrophages. Our results show that incubation with modified lipoproteins or lipid loading does not lead to TF expression in monocyte-derived macrophages cultured in suspension. This suggests that induction of TF expression in foam cells in the atherosclerotic lesion is triggered by additional or other components.     

CLA-1 is an 85-kD plasma membrane glycoprotein that acts as a high-affinity receptor for both native (HDL, LDL, and VLDL) and modified (OxLDL and AcLDL) lipoproteins

Lipoprotein metabolism is regulated by the functional interplay between lipoprotein components and the receptors and enzymes with which they interact. Recent evidence indicates that the structurally related glycoproteins CD36 and SR-BI act as cell surface receptors for some lipoproteins. Thus, CD36 has been reported to bind oxidized LDL (OxLDL) and acetylated LDL (AcLDL), while SR-BI also binds native LDL and HDL. The cDNA of human CLA-1 predicts a protein 509 amino acids long that displays a 30% and an 80% amino acid identity with CD36 and mouse or hamster SR-BI, respectively. In this report, we describe the structural characterization of CLA-1 as an 85-kD plasma membrane protein enriched in N-linked carbohydrates. The expression of CLA-1 on mammalian and insect cells has been used to demonstrate that CLA-1 is a high-affinity specific receptor for the lipoproteins HDL, LDL, VLDL, OxLDL, and AcLDL. Northern blot analysis of the tissue distribution of CLA-1 in humans indicated that its expression is mostly restricted to tissues performing very active cholesterol metabolism (liver and steroidogenic tissues). This finding, in the context of the capability of this receptor to bind to both native and modified lipoproteins, strongly suggests that the CLA-1 receptor contributes to lipid metabolism and atherogenesis.     

NeuroD regulates multiple functions in the developing neural retina in rodent

Platelet-activating factor acetylhydrolase (PAF-AH) is transported by lipoproteins in plasma and is thought to possess both anti-inflammatory and anti-oxidative activity. It has been reported that PAF-AH is recovered primarily in small, dense LDL and HDL following ultracentrifugal separation of lipoproteins. In the present studies, we aimed to further define the distribution of PAF-AH among lipoprotein fractions and subfractions, and to determine whether these distributions are affected by the lipoprotein isolation strategy (FPLC versus sequential ultracentrifugation) and LDL particle distribution profile. When lipoproteins were isolated by FPLC, the bulk (approximately 85%) of plasma PAF-AH activity was recovered within LDL-containing fractions, whereas with ultracentrifugation, there was a redistribution to HDL (which contained approximately 18% of the activity) and the d>1.21 g/ml fraction (which contained approximately 32%). Notably, re-ultracentrifugation of isolated LDL did not result in any further movement of PAF-AH to higher densities, suggesting the presence of dissociable and nondissociable forms of the enzyme on LDL. Differences were noted in the distribution of PAF-AH activity among LDL subfractions from subjects exhibiting the pattern A (primarily large, buoyant LDL) versus pattern B (primarily small, dense LDL) phenotype. In the latter group, there was a relative depletion of PAF-AH activity in subfractions in the intermediate to dense range (d=1.039-1.047 g/ml) with a corresponding increase in enzyme activity recovered within the d>1.21 g/ml ultracentrifugal fraction. Thus, there appears to be a greater proportion of the dissociable form of PAF-AH in pattern B subjects. In both populations, most of the nondissociable activity was recovered in a minor small, dense LDL subfraction. Based on conjugated dienes as a measure of lipid peroxidation, variations in PAF-AH activity appeared to contribute to variations in oxidative behavior among ultracentrifugally isolated LDL subfractions. The physiologic relevance of PAF-AH dissociability and the minor PAF-AH-enriched oxidation-resistant LDL subpopulation remains to be determined.     

Pharmacological characterization of nociceptin receptor: an in vitro study

Pancreatic cancer is difficult to treat, even for tumours localized to the pancreas. Photodynamic therapy (PDT) is a non-thermal technique for producing localized tissue necrosis with light after prior administration of a photosensitizing drug and it could have a role in the local treatment of these cancers. We studied PDT in a transplanted cancer in the hamster pancreas using the photosensitizer mTHPC (meta-tetrahydroxyphenylchlorin). Fluorescence microscopy showed maximum levels of mTHPC in normal pancreas 2-4 days after sensitization and in tumour at 4-5 days. For PDT, animals were given 0.1 or 0.3 mg kg(-1) mTHPC and the tumour was treated at laparotomy 2 or 4 days later with red light (50 J at 650 nm, continuous or fractionated) delivered via a single fibre touching the tumour surface. The maximum zone of tumour necrosis (seen 3 days after PDT) was 8.7 mm in diameter with continuous irradiation, increasing to 12.4 mm with light fractionation (four equal fractions with 3 min between fractions). The main complication was sealed duodenal perforation, seen in 3 of 16 animals, probably due to inadequate shielding of the duodenum from the light. The duodenal problems seen in hamsters are unlikely to cause trouble in the much thicker human duodenum. PDT tumour necrosis in this animal model has now been shown with a range of photosensitizers, but mTHPC is attractive as it is likely to produce the largest volumes of necrosis around each treatment point with short light exposure times. This technique could have a role in the treatment of localized cancers of the pancreas in patients unsuitable for surgery and can now be considered for preliminary clinical trials.     

The NH2-terminal region of apolipoprotein B is sufficient for lipoprotein association with glycosaminoglycans

An initial event in atherosclerosis is the retention of lipoproteins within the intima of the vessel wall. The co-localization of apolipoprotein (apo) B and proteoglycans within lesions has suggested that retention is due to lipoprotein interaction with these highly electronegative glycoconjugates. Both apoB100- and apoB48-containing lipoproteins, i.e. low density lipoproteins (LDLs) and chylomicron remnants, are atherogenic. This suggests that retention is due to determinants in the initial 48% of apoB. To test this, the interaction of an apoB fragment (apoB17), and apoB48- and apoB100- containing lipoproteins with heparin, subendothelial matrix, and artery wall purified proteoglycans was studied. ApoB100-containing LDL from humans and human apoB transgenic mice and apoB48-containing LDLs from apoE knockout mice were used. Despite the lack of the carboxyl-terminal 52% of apoB, the apoB48-LDL bound to heparin-affinity gel as well as did apoB100-LDL. An NH2-terminal fragment containing 17% of full-length apoB was made using a recombinant adenovirus; apoB17 bound to heparin as well as did LDL. Monoclonal antibodies against the NH2-terminal region of apoB decreased apoB100 LDL binding to heparin, whereas antibodies against the LDL receptor-binding region did not alter LDL-heparin interaction. The role of the NH2-terminal region of apoB in LDL interaction with matrix molecules was also assessed. Media containing apoB17 decreased LDL binding to subendothelial matrix by 42%. Moreover, removal of the apoB17 by immunoprecipitation abrogated the inhibitory effect of these media. Antibodies to the NH2-terminal region decreased LDL binding to matrix and dermatan sulfate proteoglycans. Purified apoB17 effectively competed for binding of LDL to artery derived decorin and to subendothelial matrix. Thus, despite the presence of multiple basic amino acids near the LDL receptor-binding domain of LDL, the NH2-terminal region of apoB is sufficient for the interaction of lipoproteins with glycoconjugates produced by endothelial and smooth muscle cells. The presence of a proteoglycan-binding site in the NH2-terminal region of apoB may explain why apoB48- and apoB100-containing lipoproteins are equally atherogenic.     

Quantitative studies of the kinetics of 5-aminolaevulinic acid-induced fluorescence in bladder transitional cell carcinoma

Photodynamic therapy is a potential treatment for superficial bladder cancer that utilizes photosensitizer drugs, which are activated by light to cause tissue destruction. However, first-generation photosensitizers cause prolonged phototoxicity, have poor tumour specificity and can accumulate within detrusor muscle, resulting in permanent loss of bladder capacity following treatment. A newer drug, called 5-aminolaevulinic acid (ALA), generates a sensitizer called protoporphyrin IX (PpIX) in situ and has been shown, qualitatively, to be more tumour specific. The fluorescence kinetics of ALA-induced PpIX was investigated in patient biopsies of bladder tumour, normal urothelium and detrusor muscle, both in vitro after incubation of specimens in ALA-rich culture medium for various times and in vivo after instillation of intravesical ALA before endoscopic resection. The fluorescence in tumour tissue was twice that of normal urothelium in vitro and up to tenfold in vivo. There was little ALA-induced fluorescence in detrusor muscle, both in vitro and in vivo. Most importantly, no patients experienced phototoxicity or other adverse events following intravesical instillation of ALA.     

Construction and analysis of a semi-quantitative energy profile for the reaction catalyzed by the radical enzyme galactose oxidase

The investigation of the effect of oxidized lipoproteins on platelet activity is important for the understanding of the plague formation under atherosclerosis. In the present work, we examined the influence of low density lipoproteins (LDL) on ADP-induced platelet aggregation in the platelet rich plasma. In was demonstrated that mixing of plasma and LDL was accompanied by the decrease of ADP-induced aggregation parameters as compared to control (mixing with buffer). After 1 h incubation, platelet ADP-aggregation in the sample containing oxidized LDL (oxLDL) exceeded the ADP-aggregation in the control sample. The dependence of the aggregation parameters on the incubation time and on the degree of LDL oxidation were obtained. No difference in the cholesterol and phospholipid content was observed between cells incubated with buffer, native or oxidized LDL. Therefore, the possible oxLDL-induced accumulation of cholesterol in platelet membranes is excluded as a reason for the increased cell aggregation.