RESUMO
Arbutin is known to suppress melanin production in murine B16 melanoma cells and inhibit phospholipase action. This encourages the possibility to stabilize it in lipid aggregates for its administration in medical applications. Thus, it was of interest to demonstrate that monomyristoylphosphatidylcholine (14:0 lysoPC) and arbutin may form association complexes. This was studied by Electron Microscopy (EM), 31P Nuclear Magnetic Resonance (31P NMR), Electronic Paramagnetic Resonance (EPR) and Fourier Transform Infrared Spectroscopy (FTIR). EM images show the formation of particles of c.a. 6 nm in diameter. For a 1:1 lysoPC-arbutin molar ratio 31P NMR shows a spectrum with a shoulder that resembles the axially symmetric spectrum characteristic of vesicles. The addition of La3+ ions to the arbutin-lysoPC complex allows one to distinguish two phosphorous populations. These results suggest that arbutin-lysoPC forms vesicles with bilayers stabilized in an interdigitated array. FTIR spectroscopy shows that arbutin interacts with the hydrated population of the carbonyl groups and with the phosphates through the formation of hydrogen bonds. It is interpreted that hydrophobic interactions among the phenol group of arbutin and the acyl chain of lysoPC are responsible for the decrease in acyl chain mobility observed at the 5th C level by EPR. A model proposing the formation of interdigitated bilayers of arbutin-lysoPC could explain the experimental results.
Assuntos
Arbutina/química , Bicamadas Lipídicas , Lisofosfatidilcolinas/química , Animais , Linhagem Celular Tumoral , Espectroscopia de Ressonância de Spin Eletrônica , Espectroscopia de Ressonância Magnética , Camundongos , Microscopia Eletrônica de Transmissão , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
The effect of arbutin, a 4-hydroxyphenyl-beta-glucopyranoside, on dimyristoylphosphatidylcholine (DMPC) bilayers was studied by turbidimetry, EPR and FTIR spectroscopies. The disruption of DMPC multilamellar vesicles (MLV's) with monomyristoylphosphatidylcholine (lysoPC), a product of hydrolysis of phospholipase A(2) (PLA(2)), is more efficient at 18 degrees C, where DMPC MLV's are known to be in the ripple P(beta') phase, than at 10 degrees C (L(beta') flat gel phase). Disruption at 18 degrees C was inhibited by increasing concentrations of arbutin in the solution. This inhibition was correlated with the disappearance of the ripple phase in MLV's when arbutin is present. Shifts in FTIR carbonyl bands caused by arbutin or by temperature changes allow us to propose a model. It is interpreted that the changes in the water-hydrocarbon interface caused by arbutin, forcing a reaccommodation of the carbonyl groups, eliminate the topological defects in the lattice due to mismatches among regions with different area per lipid where lysoPC can insert.
Assuntos
Arbutina/farmacologia , Dimiristoilfosfatidilcolina/química , Bicamadas Lipídicas , Espectroscopia de Ressonância de Spin Eletrônica , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
A study of 50 liver biopsies (LB) is presented from a series of 45 patients with Hodgkin's disease as diagnosed by node biopsy in 40, by laparoscopic liver biopsy (LLB) or surgery in 5, with a simultaneous positive bone marrow study in one case. A total of 34 LLB and 16 blind liver biopsies were carried out For diagnosis of the disease the LB was positive in 2/7 or 28.5%. In order to establish the clinical status as a pre-treatment staging procedure in 30 cases, the biopsy was useful in 10% of the cases; whereas during the evolution of the disease in order to establish restaging in 13 patients, positivity was observed in 1 case (7.6%). In 7/34 with laparoscopic changes of the hepatic surface, invasion was later determined by LLB, surgery or autopsy in 71%, whereas with a normal surface infiltration was only established in 18.5% In 12 patients with liver invasion as demonstrated by LLB, laparotomy or autopsy, alkaline phosphatase was increased in 91.6%. We consider that the elevated number of false negatives (58.3%) is due fundamentally to the single biopsy technique performed some years ago with the Vim-Silverman needle instead of the procedure in use at present o repeated biopsies in both lobes when possible. Our experience of 50 LB in these 45 patients has been most useful in arriving at a diagnosis in 2, determining a change in stage on 3 occasions, demonstrating peritoneal and spleen involvement in 2 cases in addition to revealing other hepatic alterations.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Doença de Hodgkin/patologia , Neoplasias Hepáticas/patologia , Fígado/patologia , Adolescente , Adulto , Idoso , Fosfatase Alcalina/análise , Biópsia , Reações Falso-Negativas , Feminino , Humanos , Laparoscopia , Fígado/enzimologia , Masculino , Pessoa de Meia-Idade , Estadiamento de NeoplasiasAssuntos
Adolescente , Adulto , Pessoa de Meia-Idade , Idoso , Humanos , Masculino , Feminino , Doença de Hodgkin , FígadoRESUMO
A study of 50 liver biopsies (LB) is presented from a series of 45 patients with Hodgkins disease as diagnosed by node biopsy in 40, by laparoscopic liver biopsy (LLB) or surgery in 5, with a simultaneous positive bone marrow study in one case. A total of 34 LLB and 16 blind liver biopsies were carried out For diagnosis of the disease the LB was positive in 2/7 or 28.5
. In order to establish the clinical status as a pre-treatment staging procedure in 30 cases, the biopsy was useful in 10
of the cases; whereas during the evolution of the disease in order to establish restaging in 13 patients, positivity was observed in 1 case (7.6
). In 7/34 with laparoscopic changes of the hepatic surface, invasion was later determined by LLB, surgery or autopsy in 71
, whereas with a normal surface infiltration was only established in 18.5
In 12 patients with liver invasion as demonstrated by LLB, laparotomy or autopsy, alkaline phosphatase was increased in 91.6
. We consider that the elevated number of false negatives (58.3
) is due fundamentally to the single biopsy technique performed some years ago with the Vim-Silverman needle instead of the procedure in use at present o repeated biopsies in both lobes when possible. Our experience of 50 LB in these 45 patients has been most useful in arriving at a diagnosis in 2, determining a change in stage on 3 occasions, demonstrating peritoneal and spleen involvement in 2 cases in addition to revealing other hepatic alterations.(ABSTRACT TRUNCATED AT 250 WORDS)