Anti-inflammatory effects of pentoxifylline in claudication

Increase in tumor oxygenation and potentiation of radiation effects using pentoxifylline, vinpocetine and ticlopidine hydrochloride

The purpose of the present study was to investigate the effects of Pentoxifylline (PTX), Vinpocetine (VPT) and Ticlopidine Hydrochloride (TCD), used commonly for vascular disorders in humans, on the pO2 in SCCVII tumors of C3H/HeJ mice and on the radioresponse of SCCVII tumors. The pO2 in the SCCVII tumors, which were measured 30 min after intraperitoneal (i.p.) injection of PTX (5 mg/kg), VPT (5 mg/kg), or TCD (10 mg/kg) using polarography, was compared to that in saline-treated control tumors. All the three drugs, PTX, VPT and TCD, yielded significant increase of the pO2 in the SCCVII tumors from 25.6 to 26.9 mmHg, from 18.6 to 22.9 mmHg, and from 22.6 to 25.9 mmHg, respectively. Frequency histogram of the pO2 distribution in the saline-treated SCCVII tumors did not show hypoxic fraction of less than 10 mmHg. The radioresponses of the drugs were investigated by tumor growth delay assay. In the drug-treated groups, the SCCVII tumors were irradiated with a single dose of 15 Gy 30 min after injection of the drugs at the same doses as those used in the experiments for intratumoral pO2 measurement. Compared with the irradiation alone group, significant tumor growth delays were observed in all the drug-treated groups. The time required to reach a four-fold increase in the initial tumor volume were 4 days in the saline-treated control group, 22 days in the irradiation (IR) alone group, 28 days in the PTX + IR group, 29 days in the VPT + IR group, and 32 days in TCD + IR group. In conclusion, VPT and TCD are potentially promising drugs for increasing the intratumoral pO2 although the mechanism for radiopotentiation observed in the present study is unknown due to small hypoxic fraction in the SCCVII tumors. Further studies on other mechanisms for radiopotentiation of PTX, VPT or TCD, besides of increasing the pO2 in the tumor, are needed.

The importance of obtaining ankle-brachial indexes in older adults: The other vital sign

As the aging population increases, so does the need to identify specific health problems associated with that age group and to develop and implement strategies to manage those problems efficiently. Peripheral arterial disease, a known threat to older adults' health and independence, often leads to decreased functional ability and potential limb loss. Nurses are in a unique position to screen older adults for the disease and to implement strategies to manage the problem. An overview of arterial physiology will be presented along with identification of risk factors, how to obtain ankle-brachial indexes and interpret the results, and treatment options for mild, moderate, and severe disease. Identifying the disease in its early stages and minimizing the effects will help keep older adults living independently and improve their quality of life.

Pharmacologic treatment for intermittent claudication

In contradistinction to chronic critical limb ischemia, the peripheral arterial disease patient with intermittent claudication is at relatively low risk for limb loss. As a result, initial claudication management should employ non-interventional therapies rather than immediate catheter-based or surgical revascularization. Although exercise therapy is the most efficacious conservative treatment for claudication, supervised exercise programs are not widely available at present. Consequently, a pharmacologic agent can be utilized to lessen the symptoms and improve the function of the claudicant. This manuscript provides a comprehensive review of the various pharmacotherapies that have been investigated for improving walking distance in the setting of intermittent claudication. Cilostazol, a phosphodiesterase III inhibitor, appears to provide the greatest benefit, significantly improving not only walking distance but quality of life as well. Early trials indicate that propionyl-L-carnitine, oral prostaglandins, L-arginine, and therapeutic angiogenesis may eventually yield significant benefit in lessening the symptoms of intermittent claudication.

Failure of pentoxifylline or cilostazol to improve blood and plasma viscosity, fibrinogen, and erythrocyte deformability in claudication

Peripheral artery disease is associated with altered blood rheologic properties, including increased viscosity and decreased red blood cell (RBC) deformability. Pentoxifylline and cilostazol are available therapies for intermittent claudication. Improvement of blood viscosity and erythrocyte deformability have been cited as potential mechanisms of action for pentoxifylline. Cilostazol is a new drug with antiplatelet and vasodilating activity, but the mechanism by which it promotes an improvement in walking is not known. This study was performed to evaluate and compare the hemorheologic effects of pentoxifylline and cilostazol on viscosity, fibrinogen levels, and erythrocyte deformability when administered to adults with moderate to severe claudication. A double-blind, controlled study was conducted and included 59 patients (46 male, 13 female; mean age 65 yr) randomized to pentoxifylline 400 mg orally thrice daily (n=20), cilostazol 100 mg orally twice daily (n=19), or placebo (n=20); all subjects were observed for 24 weeks. Walking ability was assessed before, during, and at the conclusion of treatment by standard constant speed, variable grade treadmill testing. Erythrocyte deformability was measured by passage of washed RBCs, 10% hematocrit in phosphate buffered saline (PBS), through a polycarbonate membrane with 4.7 to 5.0 microm pores. Whole blood and plasma viscosity were measured using a cone/plate viscometer at variable shear rates (from 4.5 to 450 sec(-1)). Erythrocyte sedimentation rate was measured by a modified Westergren technique. Fibrinogen was assayed by a commercial reference laboratory. Plasma viscosities did not change significantly in any treatment group. Within-group comparisons demonstrated a significant (p<0.01) drop in whole blood viscosity (week 24 compared with week 0) for cilostazol-treated subjects (at shear rates of 45, 90, 225, and 450 sec(-1)), but these changes were not significantly different from those in the placebo group. There were no significant changes in whole blood viscosity for subjects treated with pentoxifylline or placebo. There were no significant changes in erythrocyte deformability, fibrinogen, or erythrocyte sedimentation rate. A trend toward improved walking distances was noted for both pentoxifylline and cilostazol in comparison with placebo. This trend was not correlated with changes in any underlying rheologic parameter. Ex vivo rheologic characteristics of blood from patients with intermittent claudication are not significantly affected by long-term administration of pentoxifylline or cilostazol. Pentoxifylline did not modulate viscosity or red cell deformability, a finding at variance with its putative mechanism of action. Pentoxifylline cannot be differentiated from cilostazol based on specific hemorheologic effects evaluated in this study. Different mechanisms of action for these medications should be considered.

Effects of pentoxifylline on the different steps during adhesion and transendothelial migration of flowing neutrophils

We used a flow system to observe the stepwise adhesion and migration of neutrophils on cultured human umbilical vein endothelial cells (HUVEC) stimulated with tumour necrosis factor-alpha (TNF) for 4 h, and to evaluate the effects of pentoxifylline (PTX) at each step. When HUVEC had been stimulated with 100 U ml(-1) TNF, treatment of neutrophils with PTX did not reduce the number captured from flow but did cause nearly all adherent cells ( > 90%) to roll, whereas most untreated cells became immobilized and approximately 30% transmigrated within minutes. On washout of the PTX, many rolling cells halted and started to migrate. Treatment of the HUVEC with PTX at the same time as 100 U ml(-1) TNF did not affect the number of neutrophils adhering, but there was a significant increase in the percentage of cells rolling even though PTX was no longer present. Thus PTX reduced presentation of activating agents by HUVEC, as well as inhibiting the response by neutrophils to surface-presented activating agent(s). If HUVEC were stimulated with 10 U ml(-1) TNF with PTX, the adhesion of flowing neutrophils was greatly inhibited compared to TNF alone. Surface ELISA indicated that PTX reduced TNF-induced upregulation of E-selectin. This reduction was only sufficient to reduce capture of neutrophils at the low dose of TNF. Thus, by using a flow-based model, we have been able to separate the effects of a multipotent agent such as pentoxifylline, which acts on leucocytes and endothelial cells, at each stage of migration.

Peripheral arterial disease of the lower extremity

Peripheral arterial disease is becoming more prevalent due to the increasing age of the population. To better evaluate and care for patients with this disease, it is essential to understand its pathophysiology and etiology. Understanding the sequelae of events and treatments associated with peripheral arterial disease will help the nurse to provide a comprehensive, outcome-focused plan of care and education plan. Nurses are in a unique position to reduce the risks associated with lower extremity arterial disease.

Comparative effects of cilostazol and other therapies for intermittent claudication

Many patients with peripheral arterial disease (PAD) have intermittent claudication or problems with ambulation and mobility. Exercise and smoking cessation are primary therapies for claudication, but drug treatment may provide additional benefit. The data supporting use of pentoxifylline for claudication are weak, and pentoxifylline is not generally accepted as efficacious. Cilostazol is a new drug for the treatment of claudication. It appears to modestly benefit walking ability and it has other potentially useful effects, including inhibition of platelet aggregation and beneficial effects on serum lipids. In a randomized, prospective, double-blind trial examining walking ability in patients with PAD with moderate-to-severe claudication, cilostazol was superior to both placebo and pentoxifylline.

Effect of nicotinamide and pentoxifylline on normal tissue and FSA tumor oxygenation

Nicotinamide (NA) and pentoxifylline (PTX) sensitize experimental murine tumors to radiation without sensitizing normal tissues. They are presumed to exert this effect by reducing hypoxia in tumors. The present study evaluated the individual and combined effects of NA and PTX on oxygen levels in subcutaneous normal tissue and subcutaneous FSa fibrosarcoma tumors in the hind foot dorsum of C3H mice. Oxygen measurements were made using a polarographic needle electrode inserted into the tissue immediately before and/or 15-60 min after intraperitoneal administration of 500 mg/kg of NA, 50 mg/kg of PTX, or saline. The median tumor pO2 increased from a mean +/- S.E.M. of 4.1 +/- 1.1 mm Hg in saline-treated control mice to 6.8 +/- 1.9 mm Hg 15 min after NA, 7.6 +/- 1.4 mm Hg 60 min after PTX, and 6.7 +/- 1.1 mm Hg after NA and PTX in combination. PTX raised the median tumor pO2 level from 21% to 39% of the median subcutaneous normal tissue pO2 (p < 0.01). PTX also significantly reduced the proportion of tumor pO2 values < or = 2 mm Hg from 41 +/- 10% to 8 +/- 7% (p = 0.02). Although NA did increase the proportion of tumor that was well oxygenated, it did not significantly reduce the proportion of tumor pO2 values < or = 2 mm Hg (p = 0.34). The combination of NA and PTX did not add to the tumor oxygenation enhancement achieved by PTX alone. NA increased the median subcutaneous normal tissue pO2 by an average of 5.1 +/- 2.2 mm Hg from a baseline of 17.1 +/- 2.2 mm Hg (p = 0.04). PTX had no effect on the median normal tissue pO2 (p = 0.93). PTX showed greater therapeutic potential in this model system than did NA.

Age and functional correlations of markers of coagulation and inflammation in the elderly: functional implications of elevated crosslinked fibrin degradation products (D-dimers)

OBJECTIVE

To measure markers of inflammation in a cohort of young and old subjects and relate these findings to the functional level of the individuals.

DESIGN

For the pilot study, blood samples were obtained from 18 young (age 20-35 years) and 18 old (age 68-83 years) subjects. The main study population included community-dwelling subjects between the ages of 70 and 79. The group consisted of 282 subjects with minimal physical limitations, 17 subjects from the middle third, and 16 from the lower third of physical function rankings.

METHODS

Plasma markers were measured by ELISA techniques, and certain biochemical values were obtained through routine clinical tests performed by a commercial laboratory.

RESULTS

D-Dimers were higher for physically impaired subjects in all groups, but most prominently among black females, who also had significantly higher D-Dimer levels in every functional group. To inquire whether higher D-Dimers were associated with markers of inflammation, we also examined the macrophage metabolite, neopterin, the neutrophil product, elastase complexed to antitrypsin (E/a), and the albumin globulin ratio (A/G ratio). No differences were found in neopterin or E/a levels on the basis of gender, race, or functional status. The A/G ratio was significantly lower in functionally impaired subjects.

CONCLUSION

These preliminary findings demonstrate racial/ethnic and gender differences in D-Dimers in a population of community-dwelling elderly, and suggest that factors influencing hemostasis may be particularly relevant to physical functional status in black women. A sample containing more subjects with lower physical function will be needed to establish the relationship between inflammation, altered hemostasis, and physical function decline.

Increase in tumor blood flow by pentoxifylline

PURPOSE

The effect of pentoxifylline (PTX) on the blood flow in experimental rodent tumors was investigated.

METHODS AND MATERIALS

When the R3230 AC adenocarcinoma implanted in the leg of Fischer 344 rats grew to about 1 g, the effect of PTX on the blood flow in the tumor and in the skin and muscle was determined with the microsphere method using 85Sr labelled 25 microns diameter microspheres. The SCK mammary carcinoma was induced subcutaneously in the leg or foot of A/J mice and the effect of PTX on the tumors was investigated: the blood perfusion in the leg tumors (7 mm in diameter) was determined with the 86Rb uptake method and that in the foot tumors (5 mm diameter) was determined with the laser Doppler flow (LDF) method.

RESULTS

The blood flow in the R3230 AC adenocarcinoma significantly increased when measured 30 min after an IP injection of 50 mg/kg PTX while the blood flow in the normal skin and muscle remained unchanged. The 86Rb uptake in the SCK tumor slightly increased 30 min after an IP injection of 50 mg/kg PTX. The LDF in the SCK tumors grown in the foot began to increase 5-10 min after an injection of 25 mg/kg PTX reaching 1.5-2.0 times in 20-30 min and it returned to the original level at 60 min.

CONCLUSION

The results in the present study together with our previous observation that PTX increases the tumor pO2 in rodent tumors strongly suggest that PTX may be useful for increasing the radiosensitivity of human tumors.

Platinum drug delivery and radiation for locally advanced prostate cancer

Combined therapies of cisplatin and radiation have resulted in clinical reports of apparent efficacious control of locoregional cancer and enhanced survival. Mechanisms of interaction between platinum and radiation that may explain these clinical observations all have in common the prediction that higher concentrations of platinum in all tumor cells close in time to irradiation should lead to greater potentiation of radiation-induced killing of those cells. Cisplatin is thus viewed as providing some radiation-equivalent, or a radiation dose-effect factor, for sterilization of tumors. One disease site that has not been well investigated for response to cisplatin plus radiation therapy, but that could benefit from it, is locally advanced prostate cancer. A body of literature now supports the view that local control of stage C (T3, N0, M0) prostate cancer is correlated with disease-free survival. This correlation makes prostate cancer a candidate for potentially achieving improved cure rates following local tumor sterilization by combining cisplatin with radiation therapy. The need and approaches to optimize delivery of cisplatin within tumor tissue is explored. Increasing cisplatin concentration to all the cells of a tumor, i.e., homogeneously delivering systemic high-dose cisplatin, should benefit the efficacious response otherwise expected for cisplatin combined with radiation. Strategies to increase the homogeneity of cisplatin delivery to a tumor are considered to be those that increase perfusion to that tumor. Vasoactive agents used in anticancer protocols are especially considered for their potential value in serving to increase tumor perfusion. These protocol-inclusive agents include certain cytokines and L-arginine antagonists, and should be better managed and accepted in practice compared to other vasoactive agents that need to be developed as specific additives to protocol designs.