Anorectal and sexual functions after preoperative radiotherapy and full-thickness local excision of rectal cancer.

AIMS: Local excision with preoperative radiotherapy may be considered as alternative management to abdominal surgery alone for small cT2-3N0 tumours. However, little is known about anorectal and sexual functions after local excision with preoperative radiotherapy. Evaluation of this issue was a secondary aim of our previously published prospective multicentre study. METHODS: Functional evaluation was based on a questionnaire completed by 44 of 64 eligible disease-free patients treated with preoperative radiotherapy and local excision. Additionally, ex post, these results were confronted with those recorded retrospectively in the control group treated with anterior resection alone (N = 38). RESULTS: In the preoperative radiotherapy and local excision group, the median number of bowel movements was two per day, incontinence of flatus occurred in 51% of patients, incontinence of loose stool in 46%, clustering of stools in 59%, and urgency in 49%; these symptoms occurred often or very often in 11%-21% of patients. Thirty-eight per cent of patients claimed that their quality of life was affected by anorectal dysfunction. Nineteen per cent of men and 20% of women claimed that the treatment negatively influenced their sexual life. The anorectal functions in the preoperative radiotherapy and local excision group were not much different from that observed in the anterior resection alone group. CONCLUSIONS: Our study suggests that anorectal functions after preoperative radiotherapy and local excision may be worse than expected and not much different from that recorded after anterior resection alone. It is possible that radiotherapy compromises the functional effects achieved by local excision.

Acceptance of a 5-mm distal bowel resection margin for rectal cancer: is it safe?

AIM: Acceptance of a short distal bowel margin results in a higher rate of anterior resection but may compromise oncological safety. This study aimed to evaluate the safety of a 5-mm distal margin. METHOD: A retrospective analysis was carried out of 412 consecutive patients with rectal cancer treated with anterior resection with a negative circumferential resection margin. Radiotherapy was given to 63% of patients with an advanced tumour. The median follow up was 75 months. RESULTS: Fewer patients in the group with a distal margin of ≤ 5 mm had a tumour with an advanced pT stage compared to patients in the group with a distal margin of > 5 mm (P = 0.033). Two patients were converted to abdominoperineal resection because of a positive 'doughnut', leaving 410 patients, in whom 5.4% (95% CI, 0-11.3%) of the group with a distal margin of ≤ 5 mm had local recurrence at 5 years compared with 4.2% (95% CI, 2.1-6.3%) of the group with a distal margin of > 5 mm (P = 0.726). The corresponding figures for the 5-year overall survival were 82.4% (95% CI, 72.6-92.2%) vs 76.3% (95% CI, 71.8-80.8%) (P = 0.581). All four anastomotic recurrences occurred in the group with a distal margin of > 5 mm. CONCLUSION: A distal margin of ≤ 5 mm did not compromise oncological safety in patients undergoing preoperative radiation for an advanced rectal cancer.

The hemolysis kinetics of psoriatic red blood cells.

Psoriasis has been reported to be associated with several red blood cell (RBC) membrane alterations including: a membrane fluidity decrease, a significant elevation of Na(+)-K(+)and quantitative changes of erythrocyte membrane proteins that may indicate red cell cytoskeleton impairment. The aim of the present study was to analyse the hemolytic behaviour of psoriatic RBCs. The osmotic behaviour of RBCs was examined by analysing the kinetics of hemolysis. The method is based on the measurement of the transmitted light (lambda=700 nm) scattered by a suspension of red blood cells subjected to osmotic stress in the stopped-flow regime. The transmittance as a function of time, which describes the lysis kinetics, can be satisfactorily fitted with a mathematical model which assumes three cell populations in each sample: cells that do not lyse in the experimental conditions and cells that undergo fast and slow lysis. A comparison of the erythrocyte hemolytic kinetics of blood samples from psoriatic patients and healthy subjects showed distinct differences. The fraction of hemolyzed erythrocytes for control samples was about 20%; for psoriatic ones 12.6% (P<0.001). In control blood samples the fraction of fast-breaking cells was greater (about 61% of lysed cells) than in psoriatic ones (about 56%). The parameter T(fast), describing the time of fast kinetics and T(slow), which reflects the rupturing time of cells belonging to the fraction of slow hemolysing cells were significantly higher for psoriatic erythrocytes than for control cells (P<0.001). It was shown that the psoriatic erythrocyte has a low propensity for hemolysis and that its plasma membrane is distinctly more resistant to osmotic stress, probably related to decreased bilayer fluidity and low cell deformability. The results of this study showed that the kinetics of hemolysis may be a promising method for detecting erythrocytes with defective plasma membrane components and/or defective cytoskeleton organization and indirectly can provide some information on cell function.

Influence of the retinoid acitretin on erythrocyte microrheology in vitro.

OBJECTIVE: To determine in vitro changes in the microrheology of red blood cells (RBCs) treated with acitretin (Ro 10-1670). VOLUNTEERS AND METHODS: Venous blood samples were obtained from 27 healthy donors. Washed erythrocytes (5 x 10(6) cells/ml) were incubated for 30 min at 37 degrees C in solutions of low (25 ng/ml) and high (400 ng/ml) acitretin concentration. The whole red cell deformability was measured using osmotic gradient ektacytometry. To assess the contribution of factors influencing changes in red cell deformability, the biophysical state of the phospholipid bilayer was determined using the cation osmotic hemolysis technique (COH) and the internal viscosity using electron paramagnetic resonance (EPR) spectroscopy. RESULTS: Osmotic deformability studies revealed that cells treated with acitretin at low concentration deformed almost normally in isotonic medium, but RBCs incubated with high acitretin concentration showed distinct loss of deformation. However, in hypotonic medium, cell deformability was reduced to abnormally low values and this change was most marked with high acitretin concentration. CHO measurements showed that incubation of red cells at low acitretin concentration caused a significant increase in hemolysis at ionic strengths from 123.2 - 154.0 mmol/1 NaCl in relation to the control (p < 0.001). A high concentration of acitretin caused a significant increase in COH with high ionic strengths in the range 107.8 - 154.0 mmol/l NaCl (p < 0.001) and at low ionic strengths in the range 15.4 mmol/l NaCl (p < 0.05). The measurement of RBC intracellular microviscosity showed no statistically significant differences between control (6.22+/-0.22 cP) and acitretin-treated (6.29+/-0.25 cP) cells. CONCLUSION: The data show that acitretin, even at low concentration, is capable of inducing the reduction of red cell deformability. A reduced tendency of acitretin-treated RBCs to deform might result from the ability of acitretin to perturb the cell shape and membrane viscoelastic properties.

Changes in erythrocyte microrheology in patients with psoriasis.

Erythrocyte deformability (ED), the ability of red blood cells to change shape during flow in the microcirculation, is the basic rheological property of erythrocytes. It is determined by the surface area to volume ratio, viscoelastic properties of the membrane, and intracellular viscosity. The aim of the present study was to determine changes in erythrocyte microrheology in patients with psoriasis. The whole red cell deformability was measured by flow-channel diffractometry. To assess the contribution of different factors influencing changes in ED, measurements were also made of the biophysical state of the phospholipid bilayer, using an osmotic haemolysis technique, and internal viscosity, using electron paramagnetic resonance spectroscopy. The results showed a significant decrease in ED in patients with psoriasis in comparison with controls, and suggested that the main cause of this may be alterations in intracellular viscosity and membrane viscoelastic behaviour.

The influence of oxidative stress on microviscosity of hemoglobin-containing liposomes.

Encapsulation of hemoglobin (Hb) within a liposome is one of the strategies in the development of artificial oxygen carriers. In this study the effects of oxygen radical generating system (xantine/xantine oxidase) on the internal microviscosity and protein degradation of hemoglobin-containing liposomes ('hemosomes') prepared from dipalmitoylphosphatidylcholine (DPPC) and different amounts of cholesterol (Ch) (0-0.5 mol/mol) were investigated. The results demonstrated a direct relationship between increasing oxidant stress and microviscosity of Hb vesicles and also showed clearly that the increase in internal viscosity was caused mainly by globin degradation. It was shown that the higher content of Ch, the lower Hb degradation and smaller increase in internal viscosity were observed. The significant protection effect against oxygen radicals was observed only for liposomes with the addition of 0.3 mol/mol or more of Ch. It seems that Ch concentration in liposomes is of prime importance for stabilizing of Hb in 'hemosomes'.

In vivo and in vitro influence of etretinate on erythrocyte membrane fluidity.

The molecular mechanisms underlying the action of synthetic retinoids have been studied intensively, but they are not fully understood yet. It is well known that retinoids exert their effects on gene expression via the retinoic acid receptor. Some observations suggest that the main aromatic retinoid etretinate (Tigason) exerts its therapeutic effect in psoriasis also through an action on the cell membrane. In this paper, we present the results of previously unreleased experiments (when Tigason was still in use) concerning the in vivo and in vitro influence of etretinate on erythrocyte membrane fluidity in psoriatic patients. Erythrocytes from healthy subjects and topically treated psoriatics were chosen as control groups. Membrane fluidity was measured by the electron paramagnetic resonance (EPR) spin-labelling technique. Erythrocytes from psoriatic patients had lower membrane fluidity, a lower antioxidant activity and a greater susceptibility to peroxidation than those from healthy subjects. After treatment with etretinate, a significant increase in erythrocyte membrane fluidity and in antioxidant activity as well as a decrease in lipid peroxidation were observed in erythrocytes from patients. Local therapy of psoriatic lesions had no influence on the improvement in membrane fluidity and antioxidant activity of erythrocytes. Incubation of erythrocytes from healthy controls and topically treated psoriatics with etretinate in vitro confirmed its fluidizing effect on erythrocyte membranes. These data may indicate that two mechanisms lead to an increase in erythrocyte membrane fluidity in psoriatic patients treated with Tigason: the first one, indirect, by improvement of the antioxidant defence system and cell protection against lipid peroxidation, and the second one, by a direct fluidizing effect of etretinate on the erythrocyte membrane.

Erythrocyte membrane fluidity changes in psoriasis: an EPR study.

The aim of the study was to find the cause of membrane fluidity decrease in psoriasis, observed by other authors, in different types of cells and its clinical consequences. To this end, we have examined the influence of different clinical and biochemical factors on erythrocyte membrane fluidity changes in psoriatic patients. Membrane fluidity was studied by the electron paramagnetic resonance spin-labeling method. The data revealed that the decrease of membrane fluidity corresponded with exacerbation of skin lesions. The results clearly indicate that the increased lipid peroxidation may be the essential mechanism of membrane fluidity decrease in psoriasis.

In vitro effects of ozone on human erythrocyte membranes: an EPR study.

The effects of ozone at different concentrations (10, 30, 45 g/m3) on fluidity and thermotropic properties of erythrocyte membranes were investigated by EPR using two spin probes: 5-doxylstearic acid (5-DSA) and 16-doxylstearic acid (16-DSA). The effect of ozone on the erythrocyte membrane fluidity was a dose-dependent process. The ozone at concentration of 10 g/m3 caused rigidization of the membrane while at concentration of 45 g/m3 increased fluidity both on the surface and in the deeper hydrocarbon region of the membrane. Temperature transitions close to the polar heads region (monitored by 5-DSA) were not sensitive to an increase in ozone concentration. In the case of 16-DSA, low temperature thermotropic transition (around 20 degrees C) gradually decreased with the increase of ozone concentration. High temperature transition (around 40 degrees C) significantly differed at the ozone concentration of 10 g/m3 and 45 g/m3, being higher and lower, respectively, as compared to untreated cells. For the ozone concentration of 45 g/m3 the disappearance of the low temperature break and the appearance of two breaks at 37 degrees C and 16 degrees C were observed.