Is lower extremity revascularization worthwhile in patients with end-stage renal disease?

BACKGROUND: The purpose of this study was to review the results of lower extremity revascularization in patients with end-stage renal disease and to determine in these patients the functional benefit and cost of an aggressive approach to limb preservation. METHODS: During a 5-year period at our institution, 33 bypass operations were performed on 31 limbs of 23 dialysis-dependent patients. Indications for revascularization were limited (18) or extensive (12) tissue loss or ischemia without tissue loss (3). Procedures included aortobifemoral bypass (1), femoropopliteal bypass (10), and femorotibial/pedal bypass (22). A digital or transmetatarsal amputation was performed in 57% of limbs. RESULTS: The 30-day primary patency was 100%. Cumulative primary and secondary patency rates at 2 years were 65% and 79%, respectively. Limb salvage was 67% and 59% at 1 and 2 years, respectively. Patient survival was poor (47% at 2 years). Peritoneal dialysis was predictive of poor survival (P <.001). Four of 5 patients on peritoneal dialysis died within 3 months of intervention. Extensive tissue loss was predictive of a diminished rate of limb salvage (P =.027). Only 39% of limbs with extensive tissue loss were salvaged at 1 year compared with 78% and 100% of limbs with limited and no tissue loss, respectively. The average hospital cost was $44,308 per year of limb salvage. CONCLUSIONS: Although revascularization of ischemic limbs in dialysis patients can be achieved with an excellent initial graft patency and reasonable limb salvage, patient survival is poor and costs are high. A selective approach to revascularization in these complicated patients may be indicated. For patients treated with peritoneal dialysis and for those with extensive tissue loss, primary amputation may be the preferred approach.

Sensitivity to macrophages decreases with tumor progression in the AKR lymphoma.

Resistance to immune reactions, innate or acquired, may be one of the mechanisms responsible for the progression of tumors. We have, indeed shown higher numbers of macrophages surrounding low- as compared to high-malignancy cells. In the present study we examined the level of cell surface molecules known to determine sensitivity to macrophages, namely galactose (GAL) and sialic acid (SA) residues. A histochemical assay for identification of SA by electron microscopy showed a higher cell surface content on metastatic (MT) than on primary (PT) tumor cells. The FACS data seen with fluorescent lectins showed a higher binding of Sambucus nigra agglutinin, which identifies SA attached to terminal GAL in -2.6 or -2.3 linkage, in MT than in PT cells. Binding of Maakia amurensis lectin (MAL-1), which identifies SA at position 3 of GAL, showed that the MT cells contain two subpopulations, one binding more MAL-1 and another less. Cell sorting showed a more aggressive behavior of the first population. The comparison of Peanut agglutinin (PNA) binding, which identifies GAL, demonstrated a decreased amount of PNA receptors in MT as compared to PT cells. Western blot analysis of the membranal proteins with different lectins, identified 3 sialylated glycoproteins. The 88 kDa glycoprotein had no significance for metastatic potential. The 130 kDa glycoprotein was higher in MT than on PT cells. The 220 kDa glycoprotein was practically present only on MT cells. The tendency observed was of a higher level of membranal glycoconjugates terminally sialylated with subterminal galactose residues, inMT cells as compared to PT cells. This may explain the recently found decrease in apoptotic cell death with increasing aggressiveness of the AKR lymphoma and suggests a lower sensitivity to macrophages with tumor progression. Treatment based on the reduction in sialic acid content might render the tumor cells more vulnerable to macrophages. We found, indeed, that Wheat germ agglutinin (WGA) injected in vivo, exerted an inhibitory effect on growth of the lymphoma. We found moreover that WGA-treated tumor cells were more sensitive than nontreated cells to macrophages in vitro.

Acute exercise induces GLUT4 translocation in skeletal muscle of normal human subjects and subjects with type 2 diabetes.

Total GLUT4 content in skeletal muscle from individuals with type 2 diabetes is normal; however, recent studies have demonstrated that translocation of GLUT4 to the plasma membrane is decreased in response to insulin stimulation. It is not known whether physical exercise stimulates GLUT4 translocation in skeletal muscle of individuals with type 2 diabetes. Five subjects (two men, three women) with type 2 diabetes and five normal control subjects (5 men), as determined by a standard 75-g oral glucose tolerance test, were recruited to determine whether an acute bout of cycle exercise activates the translocation of GLUT4 to the plasma membrane in skeletal muscle. Each subject had two open biopsies of vastus lateralis muscle; one at rest and one 3-6 weeks later from the opposite leg after 45-60 min of cycle exercise at 60-70% of VO2max. Skeletal muscle plasma membranes were prepared by subcellular fractionation, and GLUT4 content was determined by Western blotting. Plasma membrane GLUT4 increased in each subject in response to exercise. The mean increase in plasma membrane GLUT4 for the subjects with type 2 diabetes was 74 +/-20% above resting values, and for the normal subjects the increase was 71+/-18% above resting values. Although plasma membrane GLUT4 content was approximately 32% lower at rest and after exercise in the muscle of the subjects with type 2 diabetes, the differences were not statistically significant. We conclude that in contrast to the previously reported defect in insulin-stimulated GLUT4 translocation in skeletal muscle of individuals with type 2 diabetes, a single bout of exercise results in the translocation of GLUT4 to the plasma membrane in skeletal muscle of individuals with type 2 diabetes. These data provide the first direct evidence that GLUT4 translocation is an important cellular mechanism through which exercise enhances skeletal muscle glucose uptake in individuals with type 2 diabetes.

Videoscopic harvest of the inferior epigastric artery.

The inferior epigastric artery has been found to be a useful conduit for performing arterial coronary revascularization. The present report describes a minimally invasive port access technique for harvesting the inferior epigastric artery.

Identification of the active-site nucleophile in 6-phospho-beta-galactosidase from Staphylococcus aureus by labelling with synthetic inhibitors.

Kinetic parameters for the inactivation of the 6-phospho-beta-galactosidase of Staphylococcus aureus by a series (fluoro, chloro, bromo) of 2,4-dinitrophenyl-2-deoxy-2-halogeno- galactoside-6-phosphates have been determined. These inhibitors function by the formation of a stabilised glycosyl-enzyme intermediate. Inactivation and reactivation studies indicate that the fluoro derivative is formed most rapidly, but is also hydrolysed fastest. The chloro derivative forms the most stable covalent intermediate. HPLC profiles of V8-protease digestion of native and inhibited protein show significant differences, whereas the inhibited 6-phospho-beta-galactosidase and a point mutant of 6-phospho-beta- galactosidase (E375Q) yield the same proteolytic fragments. The suggestion that E375 is derivatised is strengthened by matrix-assisted laser-desorption ionisation mass spectrometry experiments which show that the two peptides, residues 336-375 and 376-383, are not produced, due to the absence of the expected cleavage at residues 375 and 376. The reason for the altered proteolysis pattern of the inhibited protein is blocking of the respective V8 cleavage site due to the chemical reaction of the inhibitor at position 375. Specific modification of the glycosyl bond between the inhibitor and E375 by aminolysis with benzylamine generated a glutamatic-acid-5-benzylamide complex at that position in the peptide. The Edman derivative of the modified E375 appears to be stable and was isolated by Edman degradation of trypsin-digested V8-peptide. It was shown to be identical to an authentic, synthetic sample. From this, it is evident that E375 is the active-site nucleophile of 6-phospho-galactosidase, consistent with previous findings for enzymes in this family.

Antitumoral activity of an immunomodulatory fraction of Nocardia opaca: mechanism of action.

Immunomodulatory substances have been used as antineoplastic agents in experimental and human systems. Many of these agents were derived from microorganisms. Several biologically active fractions have been isolated from Nocardia. These derivatives were shown to induce interferon production, to activate natural killer cells and macrophages and to exert an antitumoral effect. We attempted to examine the mechanism of the antitumoral activity of the Nocardia water-soluble mitogen (NWSM). The tumor tested was the Lewis lung carcinoma (3LL). Regular histological examination and identification of the cellular immune reaction by monoclonal antibodies against macrophages (Mac 1 antigen), B- (IgG expressing) and T-lymphocytes (anti-Lyt-1), analysed by flow cytometry, were performed on samples of the tumor site and of the spleen. Intratumoral administration of the immunomodulators resulted in a massive accumulation of inflammatory cells around the tumor in mice treated with NWSM. The thick rim of infiltrating cells consisted of macrophages and lymphocytes, while the nontreated tumor was found to provoke only a scanty lymphocyte infiltration. Macrophages were, therefore, present at the tumor site and were directly implicated in the antitumoral effect of the Nocardia immunomodulator. T-lymphocytes were also observed at the site of the tumor. The spleen reaction consisted of marked extramedullary hematopoiesis and enlarged follicles containing prominent germinal centres (assessed also by a FACS-demonstrated increase in B-lymphocytes). In view of the inefficiency of chemotherapy in the treatment of advanced cancer, it is of major importance to explore alternative cancer treatment modalities. Immunotherapy is a particularly interesting alternative since it can potentially affect metastatic disease.

Changes in distribution of lectin receptors in macrophages activated by Nocardia water soluble molecules.

Lectin-histochemical studies were performed on macrophages activated by Nocardia opaca water soluble molecules (NWSM) and elicited by phosphate buffered saline (PBS) as control to demonstrate the pattern of carbohydrate residues. Ten different biotinylated lectins were used as probes and avidin-biotin-peroxidase complex (ABC) was used as visualizer. The lectins wheat germ agglutinin (WGA) and Griffonia simplicifolia agglutinin-I (GS-I) stained macrophages only after activation by NWSM and not macrophages elicited by PBS. Both macrophages did not stain by succinylated wheat germ agglutinin (S-WGA). The difference in lectin-binding patterns between NWSM-activated and PBS-elicited macrophages, suggests that activation of macrophages by the NWSM is associated with modification in the distribution of specific membrane carbohydrates, including enhancement in the expression of sialyl and alpha-galactosyl residues.

Macrophage involvement in the antitumoral effect of Nocardia-delipidated cell mitogen (NDCM).

Several immunomodulatory fractions derived from Nocardia have been found to inhibit the growth of several experimental tumors, including Lewis lung carcinoma (3LL). An involvement of both macrophages and lymphocytes in the antitumoral effect of Nocardia fractions has been suggested. The mechanism of the Nocardia delipidated Cell Mitogen (NDCM)-induced tumor-inhibiting effect was investigated further in the present study. Macrophages activated by NDCM exerted a cytotoxic effect on 3LL cells in vitro, indicating a direct influence of macrophages on the tumor cells. These results correlate with previous findings which showed a local accumulation of macrophages (but also lymphocytes) at the tumor site in NDCM-treated mice. In tumor-bearing mice--both treated and non-treated with NDCM--a splenomegaly due to a pronounced extramedullary hematopoiesis was seen. Concomitant with the gradual evolution of the extramedullary hematopoiesis in the red pulp, a depletion in white pulp component was observed, more pronounced in the control 3LL-bearing mice than in the 3LL-inoculated NDCM-treated animals. The disappearance of the lymphatic follicles in 3LL-bearing mice may be responsible for the failure to cope with the tumor. It is therefore possible that by delaying white pulp depletion, NDCM favors a better host defense against the tumor. Examination of lungs in 3LL-bearing mice treated by NDCM showed a rich infiltration of macrophages in the vicinity of isolated tumor cells, probably indicating a defensive role of NDCM-activated macrophages against metastatic spread of the tumor. Although the macrophage appears to be of major importance in the NDCM-induced host response against the tumor, other components of the immune system are probably system are probably also activated by the Nocardia fraction in defense against the neoplasm.

Differential sensitivity to hyperthermia of the F1 and F10 B16 melanoma variants.

The currently available antitumoral therapeutic modalities are most often inefficient against metastatic disease. The metastatic phenotype has been shown to be largely determined by cell membrane properties. The cell membrane could therefore be considered as a possible target for antimetastatic drugs. In the present study we examined the effect of hyperthermia (the antitumoral effect of which is based, at least partly, on an action on the cell membrane) on the F1 and F10 variants of B16 melanoma. Cells of the more malignant variant, F10, were found to be markedly more sensitive to hyperthermic treatment than those of the less malignant one, F1. One hour in-vitro treatment by supranormal temperatures (ranging from 40 to 46 degrees C) resulted in a differential effect with regard to both proliferating capacity of the cells in vitro and tumorigenic ability following inoculation to mice. Our present results in the B16 melanoma corroborate data obtained by us in another tumour system, the AKR lymphoma. Study of the effect of membrane-acting agents on tumour variants differing in degree of malignancy might result in the finding of antitumoral agents efficient against advanced cancer.

Local cellular host response induced by Nocardia-delipidated cell mitogen in Lewis lung carcinoma-bearing mice.

Various Nocardial fractions have been shown to exert inhibitory effects against several experimental tumors, via a host response mechanism. With the aim of obtaining further information on the mechanism of action of these immunomodulators, we examined in the present study the local cellular host response induced by intratumoral administration of one of these fractions, the Nocardia-delipidated cell mitogen (NDCM), at the site of the tumor (Lewis lung carcinoma-3LL). The tumor itself was found to provoke a scanty cellular infiltration surrounding the tumor mass, mainly composed of lymphocytes. The site of the tumor in NDCM-treated mice was surrounded by a very thick rim of inflammatory cells, consisting of macrophages and lymphocytes. Although recognized decades ago, the existence of tumor infiltrating leukocytes still constitutes a puzzle. The composition and significance of these host cells, in both non-treated and treated tumors has not yet been elucidated. Since lymphocytes were also found around non-treated tumors and they apparently did not prevent tumor development, it is possible that macrophages play a more important role in the NDCM-elicited host defense against the Lewis lung carcinoma.

Sensitivity to thermochemotherapy of AKR lymphoma and B16 melanoma variants of malignancy.

Drug resistance, which so often accompanies tumor progression, has been shown to be related to changes in membrane properties which may result in decreased drug accumulation in the tumor cell. A correlation between sensitivity to thermochemotherapy and degree of malignancy was found in the AKR lymphoma system. Hyperthermia increased adriamycin (ADR) uptake and concomitantly its cytotoxicity to AKR lymphoma cells. Moreover, these effects were more pronounced on a variant of high malignancy (HM) than on a low malignancy (LM) one. Fluorescent microscopy, as well as cytofluorometry, indicated that lymphoma cells treated by ADR at 43 degrees C were more permeable to the cytotoxic agent than those exposed to the chemotherapeutic substance at 37 degrees C. Cytofluorometry indicated the presence of a minor cell subpopulation with low ADR uptake in the HM variant, not found in the LM one. Fluorocytometry also showed that the temperature-dependent increased ADR uptake was more marked in the HM than in the LM variant, explaining the differential effect of thermochemotherapy on the two lymphoma variants. However, correlation between degree of malignancy and sensitivity to thermochemotherapy is not a general feature. In contrast to the results obtained in the AKR lymphoma system, in the B16 melanoma the low malignancy variant, F1, was more markedly affected by the combined treatment than the F10 variant. The increased cytotoxic effect of ADR by supranormal temperatures in the F1 variant was shown to be due to an augmented drug uptake. The results suggest that drug resistance in late stages of tumor progression can be overcome by an agent acting on the cell membrane. However, the data also indicate the necessity of assaying cancer treatment modalities, including those designed to circumvent drug resistance, on various tumor system models.

Combined effect in vitro of chemotherapy with agents acting on the cell membrane of Lewis lung carcinoma.

The treatment of cancer is often impeded by the emergence of drug-resistant clones. Drug resistance is in many cases due to a decreased drug accumulation in the tumor cell. Membrane-acting agents, by increasing cell permeability, might counteract the loss of sensitivity to drugs. In the present study, the effect of two membrane-acting agents, hyperthermia and the calcium channel blocker verapamil, on the action of adriamycin (ADR) on Lewis lung carcinoma (3LL) was examined. Hyperthermia increased drastically the antitumoral effect of ADR. The effectiveness of the combined ADR-hyperthermia treatment was proportional to the ADR dose and to the degree of hyperthermia. Verapamil had a similar effect but at higher ADR doses. Treatment modalities designed for the circumvention of drug resistance could be one approach in the attempt to find a way to control cancer.

The distribution of lectin receptor sites in human breast lesions.

Conflicting data regarding the status of A, B, H and T antigens in epithelium of normal, mastopathies, fibroadenomas and carcinomas of the breast stimulated us to re-examine the carbohydrate residues in these condition. Currently, we extended the number of carbohydrate residues studied by using ten different biotinylated lectins as probes and avidin-biotin-peroxidase complex (ABC) as a visualant. In addition, the pattern of lectin staining of cancerous cells in primary and metastatic sites was compared. In primary and metastatic breast carcinomas, lectin receptor sites were stained more intensely with Concanavalia ensiformi agglutinin (*Con A), Ricinus communis agglutinin-I (RCA-I) and wheat germ agglutinin (WGA), than in normal breast, in mastopathies or in fibroadenomas. Cryptic receptor sites for peanut agglutinin (PNA) were stained in all cases of breast carcinomas, while free PNA sites stained only in a few cases of well-differentiated carcinomas. Receptors sites for Ulex europaeus agglutinin-I (UEA-I) stained non-malignant epithelium of patients with blood group H but did not stain malignant cells. The results show significant differences in lectin-binding patterns and staining intensities between normal and non-malignant, and malignant epithelial breast cells. Furthermore, these results indicate that in malignant cells, there is an increased content of sialic acid-rich carbohydrates but not of asialylated glycoconjugates.

Effect of splenectomy on treatment of Lewis lung carcinoma by an immunomodulatory polysaccharide and a cytotoxic agent.

The effect of the spleen on the efficiency of chemotherapy (cyclophosphamide) and immunotherapy (the polysaccharide levan) of C57BL mice bearing the Lewis lung carcinoma was studied. The development of Lewis lung carcinoma caused a gradual splenomegaly in the C57BL mice. Splenectomy did not, however, affect tumor growth in the nontreated host. Levan induced a pronounced splenomegaly. Splenectomy reduced markedly the antitumoral effect of the polysaccharide. These results indicate that spleen elements participate in the inhibitory activity of levan. By contrast, splenectomy had no effect on the efficiency of treatment of cyclophosphamide.

A model for cancer treatment in advanced compared to early cancer.

Loss of sensitivity to drugs following tumor progression constitutes the main reason for failure of treatment in advanced cancer. In view of the dynamic nature of neoplasms, models of tumor progression should be used for the testing of drugs. In the present study, two variants of malignancy of AKR lymphoma were used as a model of tumor progression to test various treatment modalities. The two variants, TAU-39 (of low-malignancy) and TAU-38 (of high-malignancy) differed in the pattern of local tumor growth as well as in the rate of metastatic spread and mice killing capacity. The efficiency of chemotherapy, immunotherapy and hyperthermia on the two variants was compared. The low-malignancy tumor was more sensitive to adriamycin than the high-malignancy one. Administration of levan-activated macrophages at the tumor site inhibited the growth of TAU-39. However, growth of the high-malignancy variant was stimulated by macrophages. Hyperthermic treatment was, in contrast to the other treatments, more effective against the high - than against the low-malignancy tumor. Models of tumor progression used in tests for antitumoral drugs may help in the discovery of treatment modalities effective also for advanced stages of cancer.

In vitro effect of levan-activated macrophages on Lewis lung carcinoma cells.

The polysaccharide levan (polyfructose) has previously been shown to exert an inhibitory effect on the growth of several murine tumors. This activity is mediated by a host reaction, involving mainly macrophages but also other elements of the immune system. It was not clear, however, whether levan-activated macrophages act by a direct cytocidal effect on the tumor cells or via the activation of a specific immune response to the tumor. In the present study, the possibility of a direct cytotoxicity of levan-activated macrophages against Lewis lung carcinoma cells was tested by coculture in vitro. It was found that levan-induced (as well as paraffin oil induced) macrophages actually exert a direct cytotoxic effect on Lewis lung carcinoma cells. The tumor cell killing is mediated by cell to cell contact. A cytoplasmic bridge was often seen between the macrophage and the tumor cell. The remaining tumor cells in the lysed area appear slender, shrunken and non-dividing.

Lysis and growth stimulation of a murine melanoma determined by density of macrophage populations.

Activated macrophages were found to induce opposite effects on the growth of the F10 variant of B16 melanoma in both in vivo and in vitro systems. Low macrophage numbers had lytic effects and high numbers stimulated the growth of the melanoma. In fact, the number of macrophages per area (namely, their density) was found to determine whether lysis or growth stimulation would occur. Low density macrophages were found to be structurally and functionally different from high density macrophages. Macrophages in sparse cultures were round, separate, and lysed tumor cells, while crowded macrophages appeared spread, with pseudopodia, and caused enhancement of tumor growth.

Change from inhibition to stimulation by levan of AKR lymphoma following serial transfers.

A progressive increase in malignancy following serial passages of AKR lymphoma is often accompanied by loss in sensitivity to the antitumor agent, levan. In further transfers, stimulation of tumor growth, instead of inhibition, is sometimes observed. It is proposed that the shift from inhibition to stimulation of tumor growth by the immunomodulator levan may be due to a change during tumor progression in the sensitivity of the tumor cells to the reported dual effect of macrophages, inhibitory or stimulatory, on tumor growth.

Electrostatic dust protection for optical elements.

The application of electrostatic technology to the protection of optical components in earth-mounted and satellite orbital systems has been investigated. Theory and experiment indicate it is quite practical to prevent dust deposition in an earth environment. A mathematical analysis indicates even better results should be obtained in an orbital vehicle.