Johannes E. Van Lier

BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES-X. SYNTHESES AND ANALYSES OF SULFONATED PHTHALOCYANINES

Abstract— Synthetic methods to obtain selectively sulfonated metallo phthalocyanines are compared. Both condensation and direct sulfonation procedures lead to mixtures of mono‐ to tetrasulfonated products which are resolved by reverse phase liquid chromatography in buffered aqueous‐methanol. The proportion of sulfonated derivatives is examined as a function of the starting reagents in the case of the condensation method, and as a function of the temperature and reaction time in the case of the direct sulfonation procedure. The number of sulfonate groups per phthalocyanine molecule is determined by oxidative degradation of the phthalocyanine ring followed by quantitative chromatographic analysis of the sulfophthalamide and phthalamide fragments.

Biological activities of phthalocyanines--VIII. Cellular distribution in V-79 Chinese hamster cells and phototoxicity of selectively sulfonated aluminum phthalocyanines.

Abstract— Water soluble chloro aluminum phthalocyanines sulfonated to different degrees are studied for phototoxicity and cellular distribution inV–79 Chinese hamster cells. The more hydrophobic disulfonated dyes, with sulfonate substituents on adjacent benzyl groups of the phthalocyanine ring structure, exhibited the best cell penetrating properties and the highest phototoxicity. Fluorescence microscopy revealed that the dye was uniformly distributed in the cytoplasm but absent in the nucleus. The greater cell membrane penetrating properties of the lower as compared to the higher sulfonated dyes are attributed to the amphiphilic nature of the former.

Abnormal in vivo myocardial energy substrate uptake in diet-induced type 2 diabetic cardiomyopathy in rats

The purpose of this study was to determine in vivo myocardial energy metabolism and function in a nutritional model of type 2 diabetes. Wistar rats rendered insulin-resistant and mildly hyperglycemic, hyperinsulinemic, and hypertriglyceridemic with a high-fructose/high-fat diet over a 6-wk period with injection of a small dose of streptozotocin (HFHFS) and control rats were studied using micro-PET (microPET) without or with a euglycemic hyperinsulinemic clamp. During glucose clamp, myocardial metabolic rate of glucose measured with [(18)F]fluorodeoxyglucose ([(18)F]FDG) was reduced by approximately 81% (P < 0.05), whereas myocardial plasma nonesterified fatty acid (NEFA) uptake as determined by [(18)F]fluorothia-6-heptadecanoic acid ([(18)F]FTHA) was not significantly changed in HFHFS vs. control rats. Myocardial oxidative metabolism as assessed by [(11)C]acetate and myocardial perfusion index as assessed by [(13)N]ammonia were similar in both groups, whereas left ventricular ejection fraction as assessed by microPET was reduced by 26% in HFHFS rats (P < 0.05). Without glucose clamp, NEFA uptake was approximately 40% lower in HFHFS rats (P < 0.05). However, myocardial uptake of [(18)F]FTHA administered by gastric gavage was significantly higher in HFHFS rats (P < 0.05). These abnormalities were associated with reduced Glut4 mRNA expression and increased Cd36 mRNA expression and mitochondrial carnitine palmitoyltransferase 1 activity (P < 0.05). HFHFS rats display type 2 diabetes complicated by left ventricular contractile dysfunction with profound reduction in myocardial glucose utilization, activation of fatty acid metabolic pathways, and preserved myocardial oxidative metabolism, suggesting reduced myocardial metabolic efficiency. In this model, increased myocardial fatty acid exposure likely occurs from circulating triglyceride, but not from circulating plasma NEFA.

Mechanism of Reduced Myocardial Glucose Utilization During Acute Hypertriglyceridemia in Rats

PurposeThe purpose of the research is to study the effect of acute inhibition of intravascular lipolysis on myocardial substrate selection during hypertriglyceridemia using in vivo radiotracer analysis and positron emission tomography.ProceduresWe induced acute hypertriglyceridemia in vivo using an intravenous infusion of Intralipid 20% (IL) without and with acute inhibition of fatty acid delivery from circulating triglycerides with injection of Triton WR-1339 (TRI) during a euglycemic–hyperinsulinemic clamp in Wistar rats. We determined the effect of TRI on myocardial uptake of circulating triglycerides and free fatty acids using intravenous injection of [3H]-triolein and [14C]-bromopalmitate, respectively. Myocardial blood flow, oxidative metabolism, and metabolic rate of glucose (MMRG) were determined using micro-positron emission tomography (μPET) with [13N]-ammonia, [11C]-acetate, and 2-deoxy-2-[F-18]fluoro-d-glucose (FDG).ResultsTRI reduced myocardial incorporation of [3H]-triolein but not [14C]-bromopalmitate showing that it selectively reduces myocardial fatty acid delivery from circulating triglycerides but not from free fatty acids. IL reduced myocardial blood flow and MMRG by 37% and 56%, respectively, but did not affect myocardial oxidative metabolism. TRI did not abolish the effect of IL on myocardial blood flow and MMRG.ConclusionsHypertriglyceridemia acutely reduces myocardial blood flow and MMRG in rats, but this effect is not explained by increased myocardial fatty acid delivery through intravascular triglyceride lipolysis.

BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES-XL PHOTOTOXICITY OF SULFONATED ALUMINUM NAPHTHALOCYANINES TOWARDS V-79 CHINESE HAMSTER CELLS

Abstract— The phototoxicity of sulfonated aluminum naphthalocyanines towards V‐79 Chinese hamster cells is investigated. The disulfonated naphthalocyanine exhibits similar photostability, but better cell penetrating properties than the tetrasulfonated dyes. The capacity of the naphthalocyanines to generate singlet oxygen is comparable to that of the corresponding phthalocyanines. However, in contrast to the phthalocyanine dyes, the sulfonated aluminum naphthalocyanines show very little phototoxicity towards the V‐79 cells, suggesting close association with non‐vital cell constituents or extensive formation of photoinactive adducts and aggregates.

Ultra-high sensitivity detection of bimodal probes at ultra-low noise for combined fluorescence and positron emission tomography imaging

Multimodal imaging is quickly becoming a standard in pre-clinical studies, and new developments have already confirmed the strength of acquiring and analyzing parallel information obtained in a single imaging session. One such application is the introduction of an internal reference moiety (e.g. radioisotope) to an activatable fluorescent probe. One of the limitations of this approach consists of working at concentrations which are within the overlapping range of sensitivities of each modality. In the case of PET/Fluorescence imaging, this range is in the order of 10-9 nM. Working in epi-illumination fluorescence imaging at such concentrations remains challenging. Here, we present in vitro and in vivo detection limits of a new fluorescent compound.