Role of Hypoxia in Photodynamic Therapy of Tumors

The photodynamic therapy of tumors is based on a photosensitization reaction that produces oxygen-derived cytotoxic species. The availability of oxygen is therefore a necessary condition to obtain the desired effect. However, most tumors develop regions that have outgrown their vascular supply, and therefore present severe hypoxia. In many hypoxic, yet viable areas, oxygen partial pressures almost two orders of magnitude lower that in normal tissues have been measured by other authors. It is here suggested that hypoxic cells are resistant to the therapy and hence are a source of postirradiation recurrence of the tumors. Methods are reviewed and discussed that can be used to: (a) improve the tumor oxygenation status prior to, or during irradiation; (b) destroy hypoxic cells; and, (c) allow the reoxygenation of the tumor by using fractionated irradiation protocols which increase tumor photosensitivity. Hyperthermia, a therapy to which hypoxic cells are particularly sensitive, is discussed. Cellular and vascular parameters that should be considered when discussing the synergism between hyperthermia and photodynamic therapy are listed. The new research field of hypoxia mapping by nondestructive, noninvasive, imaging techniques is briefly discussed.

Aorto-left ventricular tunnel: a rare cause of heart failure in the newborn

Aorto-left ventricular tunnel is a rare congenital cardiac anomaly, consisting of a short abnormal pathway, usually from a sinus of Valsalva into the left ventricular cavity. It is usually diagnosed with echocardiography. We report a case of a newborn presenting with heart murmur and rapid progression to heart failure and left ventricular enlargement due to an aorto-left ventricular tunnel. Despite successful closure of the tunnel, the patient required a Ross procedure due to progressive aortic disease.

Dipeptidylpeptidase-IV activity and expression reveal decreased damage to the intrahepatic biliary tree in fatty livers submitted to subnormothermic machine-perfusion respect to conventional cold storage

Graft steatosis is a risk factor for poor initial function after liver transplantation. Biliary complications are frequent even after normal liver transplantation. A subnormothermic machine perfusion (MP20) preservation procedure was developed by our group with high potential for reducing injury to hepatocytes and sinusoidal cells of lean and fatty livers respect to conventional cold storage (CS). We report the response of the biliary tree to CS or MP20, in lean and obese Zucker rat liver. Dipeptidylpeptidase-IV (DPP-IV), crucial for the inactivation of incretins and neuropeptides, was used as a marker. Liver morphology and canalicular network of lean livers were similar after CS/reperfusion or MP20/reperfusion. CS preservation of fatty livers induced serious damage to the parenchyma and to the canalicular activity/ expression of DPP-IV, whereas with MP20 the morphology and canalicular network were similar to those of untreated lean liver. CS and MP20 had similar effects on DPP-IV activity and expression in the upper segments of the intrahepatic biliary tree of fatty livers. DPP-IV expression was significantly increased after MP20 respect to CS or to the controls, both for lean and obese animals. Our data support the superiority of MP20 over CS for preserving fatty livers. Dipeptidylpeptidase-IV activity and expression reveal decreased damage to the intrahepatic biliary tree in fatty livers submitted to subnormothermic machine-perfusion respect to conventional cold storage.

Dipeptidylpeptidase--IV, a key enzyme for the degradation of incretins and neuropeptides: activity and expression in the liver of lean and obese rats

Given the scarcity of donors, moderately fatty livers (FLs) are currently being considered as possible grafts for orthotopic liver transplantation (OLT), notwithstanding their poor tolerance to conventional cold preservation. The behaviour of parenchymal and sinusoidal liver cells during transplantation is being studied worldwide. Much less attention has been paid to the biliary tree, although this is considered the Achille's heel even of normal liver transplantation. To evaluate the response of the biliary compartment of FLs to the various phases of OLT reliable markers are necessary. Previously we demonstrated that Alkaline Phosphatase was scarcely active in bile canaliculi of FLs and thus ruled it out as a marker. As an alternative, dipeptidylpeptidase-IV (DPP-IV), was investigated. This ecto-peptidase plays an important role in glucose metabolism, rapidly inactivating insulin secreting hormones (incretins) that are important regulators of glucose metabolism. DPP-IV inhibitors are indeed used to treat Type II diabetes. Neuropeptides regulating bile transport and composition are further important substrates of DPP-IV in the enterohepatic axis. DPP-IV activity was investigated with an azo-coupling method in the liver of fatty Zucker rats (fa/fa), using as controls lean Zucker (fa/+) and normal Wistar rats. Protein expression was studied by immunofluorescence with the monoclonal antibody (clone 5E8). In Wistar rat liver, DPP-IV activity and expression were high in the whole biliary tree, and moderate in sinusoid endothelial cells, in agreement with the literature. Main substrates of DPP-IV in hepatocytes and cholangiocytes could be incretins GLP-1 and GIP, and neuropeptides such as vasoactive intestinal peptide (VIP) and substance P, suggesting that these substances are inactivated or modified through the biliary route. In lean Zucker rat liver the enzyme reaction and protein expression patterns were similar to those of Wistar rat. In obese rat liver the patterns of DPP-IV activity and expression in hepatocytes reflected the morphological alterations induced by steatosis as lipid-rich hepatocytes had scarce activity, located either in deformed bile canaliculi or in the sinusoidal and lateral domains of the plasma membrane. These findings suggest that bile canaliculi in steatotic cells have an impaired capacity to inactivate incretins and neuropeptides. Incretin and/or neuropeptide deregulation is indeed thought to play important roles in obesity and insulin-resistance. No alteration in enzyme activity and expression was found in the upper segments of the biliary tree of obese respect to lean Zucker and Wistar rats. In conclusion, this research demonstrates that DPP-IV is a promising in situ marker of biliary functionality not only of normal but also of fatty rats. The approach, initially devised to investigate the behaviour of the liver during the various phases of transplantation, appears to have a much higher potentiality as it could be further exploited to investigate any pathological or stressful conditions involving the biliary tract (i.e., metabolic syndrome and cholestasis) and the response of the biliary tract to therapy and/or to surgery.

Decreased apoptosis in fatty livers submitted to subnormothermic machine-perfusion respect to cold storage

Machine perfusion at subnormothermic temperature (20°C), MP20, was developed by Vairetti et al. and showed to afford a better preservation of fatty livers respect to traditional cold storage (CS) in terms of enzyme release into the perfusate and bile, glycogen stores, energy charge and oxidative stress. Here we investigated whether it also caused decreased cell death by apoptosis. Fatty and lean Zucker rats were submitted to MP20 or CS for 6 h and reperfused normothermically for 2 h. Apoptotic cells were revealed by immunohistochemistry of activated caspase-3 and M30 (new epitope on CK18 degraded by caspase-3) and by the TUNEL assay. Portal pressure was also determined. A statistically significant reduction of hepatocyte apoptosis, but especially of sinusoidal cells was determined for fatty livers submitted to MP20 respect to CS. Portal pressure was significantly lower after MP20 respect to CS. The reduction of sinusoidal cell death by apoptosis without need for anti-apoptotic therapies appears particularly positive since apoptotic sinusoidal cells hinder microcirculation in the sinusoids and are thrombogenic. These results further confirm the potential of MP20 for preserving fatty livers that would be otherwise discarded as grafts, and thus for increasing the donor pool for liver transplantation.

Altered alkaline phosphatase activity in obese Zucker rats liver respect to lean Zucker and Wistar rats discussed in terms of all putative roles ascribed to the enzyme

Biliary complications often lead to acute and chronic liver injury after orthotopic liver transplantation (OLT). Bile composition and secretion depend on the integrated action of all the components of the biliary tree, starting from hepatocytes. Fatty livers are often discarded as grafts for OLT, since they are extremely vulnerable to conventional cold storage (CS). However, the insufficiency of donors has stimulated research to improve the usage of such marginal organs as well as grafts. Our group has recently developed a machine perfusion system at subnormothermic temperature (20°C; MP20) that allows a marked improvement in preservation of fatty and even of normal rat livers as compared with CS. We sought to evaluate the response of the biliary tree of fatty liver to MP20, and a suitable marker was essential to this purpose. Alkaline phosphatase (AlkP, EC 3.1.3.1), frequently used as marker of membrane transport in hepatocytes and bile ducts, was our first choice. Since no histochemical data were available on AlkP distribution and activity in fatty liver, we have first settled to investigate AlkP activity in the steatotic liver of fatty Zucker rats (fa/fa), using as controls lean Zucker (fa/+) and normal Wistar rats. The AlkP reaction in Wistar rats was in accordance with the existing data and, in particular, was present in bile canaliculi of hepatocytes in the periportal region and midzone, in the canals of Hering and in small bile ducts but not in large bile ducts. In lean ZR liver the AlkP reaction in Hering canals and small bile ducts was similar to Wistar rat liver but hepatocytes had lower canalicular activity and besides presented moderate basolateral reaction. The difference between lean Zucker and Wistar rats, both phenotypically normal animals, could be related to the fact that lean Zucker rats are genotypically heterozygous for a recessive mutated allele. In fatty liver, the activity in ductules and small bile ducts was unchanged, but most hepatocytes were devoid of AlkP activity with the exception of clusters of macrosteatotic hepatocytes in the mid-zone, where the reaction was intense in basolateral domains and in distorted canaliculi, a typical pattern of cholestasis. The interpretation of these data was hindered by the fact that the physiological role of AlkP is still under debate. In the present study, the various functions proposed for the role of the enzyme in bile canaliculi and in cholangiocytes are reviewed. Independently of the AlkP role, our data suggest that AlkP does not seem to be a reliable marker to study the initial step of bile production during OLT of fatty livers, but may still be used to investigate the behaviour of bile ductules and small bile ducts.

Subnormothermic machine perfusion protects against rat liver preservation injury: a comparative evaluation with conventional cold storage

Hypothermic machine perfusion (MP) of the liver has been reported to improve graft function reclaiming marginal livers, such as those from non-heart-beating donors. Livers from obese donors often have fatty infiltrates and are more susceptible to hypothermic conditions. No data exist about MP at temperatures >4 degrees C. This study evaluated liver function after organ preservation by comparing MP at 20 degrees C with conventional cold storage.

METHODS

For MP, rat livers were perfused for 6 hours using an oxygenated Krebs-Henseleit (KH) solution at 20 degrees C (pH 7.4). For cold storage, livers were perfused in situ and preserved with Celsior solution at 4 degrees C for 6 hours. The reperfusion period with KH (2 hours at 37 degrees C) was performed under the same conditions both among livers preserved by MP or cold storage. Hepatic enzyme release (aspartate aminotransferase [AST], alanine aminotransferase [ALT], lactate dehydrogenase [LDH], and gamma-glutamyl transferase [GGT]), bile production, and ATP levels were measured during MP and reperfusion.

RESULTS

At the end of reperfusion, livers preserved by MP showed significantly decreased liver damage compared with cold storage: AST, 18 +/- 4 vs. 45 +/- 6 mU/mL (P < .01); ALT, 1.5 +/- .07 vs. 6 +/- 0.5 mU/mL (P < .01); and LDH, 82 +/- 2 vs. 135 +/- 29 mU/mL (P < .05). No difference was observed between bile production between MP and cold storage. High levels of biliary GGT and LDH were found in cold preserved livers. ATP levels were higher in livers preserved with MP compared with those preserved by cold storage.

CONCLUSIONS

MP at 20 degrees C resulted in a better quality of liver preservation, improving hepatocyte survival, compared with conventional cold storage. This may provide a new method for successful utilization of marginal livers, in particular fatty livers.

[Pulmonary ventricle bypass operations]

Cavopulmonary connections have been extensively used in the palliation of complex forms of congenital heart disease requiring some form of right heart bypass. We examine the mid term outcomes of pulmonary ventricle bypass operations in a single institution and performed by the same surgical team.

POPULATION

Between March 1999 and April 2006, 62 patients underwent pulmonary ventricle bypass operations: bidirectional cavopulmonary anastomosis (Glenn procedure), total cavopulmonary connections (Fontan procedure) and one and a half ventricle correction in two cases. Age at operation averaged three years (range: 0.42-25 years) for the Glenn procedure and seven years (range: 3-14 years) for the Fontan procedure. There were 36 male patients (58%) and 26 female patients (42%). The most common indication for surgery was the single ventricle defect, present in 66% of patients. Associated lesions included: transposition of the great arteries in 16 patients (35.6%), bilateral superior vena cava in four patients (8.9%), situs ambigus in five patients (11%), situs inversus in another patient (2.2%), Ebstein disease in one patient (2.2) and coronary fistula in another patient (2.2%). Sub-aortic stenosis was present in one patient (2.2%). Palliative surgery was performed in all, but three patients (5%), before the Fontan procedure.

RESULTS

Thirty two patients underwent bidirectional cavopulmonary anastomosis and thirty patients underwent cavopulmonary connections, total or 2nd stage. Mean cardiopulmonary bypass times were 50.6+/-21.9 minutes for the Glenn procedure and 88.5+/-26.3 minutes for the Fontan procedure. There was no intra-operative mortality, but two patients (3.2% (died in the first month after surgery; one due to failure of the Glenn circuit and sepsis and the other due to a low cardiac output syndrome and multi-organ dysfunction. Mean ventilation time was 5.2+/-1.7 hours for the Glenn operation and 6.2+/-3.2 hours for the Fontan operation. The mean length of stay in ICU was 3.4+/-2.8 days for patients undergoing the Glenn operation and 4.6+/-3.1 days for patients undergoing the Fontan operation and the mean length of hospital stay was 10.6+/-5.8 days for the Glenn operation and 19.1+/-12.6 days for the Fontan operation respectively. The mean follow up time was 4+/-2.1 years (minimum 0 years and maximum seven years), most patients being in NYHA class I. Epicardiac pacemakers were implanted in three patients due to arrhythmias. Two re-operations (6.7%) were needed, both in the same patient, after the Fontan procedure, this patient eventually died a few years after surgery.

CONCLUSIONS

The immediate and mid term outcomes of pulmonary ventricle bypass operations can have excellent results. From our point of view there has been an improvement, namely in the use of the extracardiac conduit technique in the 2nd stage of the Fontan operation.

Hemopoiesis in the liver of adult tumor-bearing mice

In the liver of adult mice bearing an Ehrlich carcinoma on the leg, progressively hypoxic and displaying reactive hepatitis but not metastatic dissemination, extramedullary hemopoiesis was detected. Electron microscopy revealed mainly erythropoietic islands and scattered megakaryocytes in maturation stages up to the platelet-releasing phase. Erythropoietic cells expressed an embryonic-type of hemoglobin, which is more adequate to oxygenate hypoxic environments than the adult type. They were positive for the peroxidase reaction due to the presence of hemoglobin and could furthermore be visualized by the blue-excited red autofluorescence of protoporphyrin IX. Extramedullary hemopoiesis, one of the various examples of reactivation of fetal features in the liver associated with carcinogenesis, is supposed to be compensatory for the loss of blood cells induced by the tumor. Reviewing this process has the purpose of raising the question whether the fetal features are better adapted than adult ones to the metabolic and physiological characteristics of a tumor-influenced organism.

Cold-induced apoptosis in isolated rat hepatocytes: protective role of glutathione

Liver conservation for transplantation is usually made at 2-4 degrees C. We studied the effect of rewarming to 37 degrees C for up to 3 h of rat hepatocytes kept at 4 degrees C for 20 h, modulating intracellular glutathione (GSH) concentration either with a GSH precursor (N-acetyl-L-cysteine, NAC), or with GSH depleting agents (diethylmaleate and buthionine sulfoximine, DEM/BSO). Untreated hepatocytes showed time-dependent production of reactive oxygen species (ROS), lipid peroxidation, chromatin condensation and membrane blebbing, decrease in GSH concentration, and protein sulfhydryl groups. Fluorochromatization with Propidium Iodide (PI) and Annexin V (AnxV) of cells rewarmed for 1 h caused an increase of AnxV-positive cells without PI staining and any observed lactate dehydrogenase leakage. TUNEL and DNA-laddering tests were negative for all times and treatments, indicating that apoptosis may occur without DNA fragmentation. Cold preservation and rewarming in the presence of NAC induced a significant improvement in the morphology, less oxidative stress and apoptosis. Conversely, DEM/BSO caused a marked deterioration of morphology, increase of oxidative stress and apoptosis. These results suggested that marked changes in GSH status might play a critical role in triggering apoptosis during cold preservation of isolated rat hepatocytes. NAC, added before rewarming, might represent a therapeutic approach for preventing the early events of apoptosis during cold storage.

Enzyme histochemical studies on tumor blood vessels

The oxygenation, the growth rate and the metastatic potential of a solid tumor depend on its vascularization and, in particular, on angiogenesis; a therapeutic approach affecting angiogenesis has been suggested as an alternative to conventional ones. Especially the study of the metabolism in the cells of the vessel wall should be a useful prerequisite for this approach. In this connection, an enzyme histochemical study was performed to characterize the blood vessels in a solid tumor (Ehrlich carcinoma). The following enzymes were considered: (a) alkaline phosphatase, involved in the transcellular phosphate transport and in the response to inflammatory and growth promoting factors; (b) dihydrofolate reductase, involved in the metabolism of tetrahydrofolate (for the synthesis of nucleic acids and the metabolism of serine and glycine); (c) purine nucleoside phosphorylase, involved in the degradation of purines and, in particular, of extracellular ATP and ADP; (d) xanthine oxidoreductase, engaged in the same degradation path and leading to the formation of urate, a strong antioxidant. Various patterns of enzyme activities were observed in the vessel wall. In particular, thin linear capillaries (presumed to be host capillaries penetrating the tumor) were identified for the intense positivity of alkaline phosphatase, dihydrofolate reductase and purine nucleoside phosphorilase; tortuous capillaries with variable diameters (presumed to be induced by angiogenesis from the host vessels) were negative for the alkaline phosphatase and expressed an heterogeneous pattern for the dihydrofolate reductase. All the data suggest a different vessel behaviour concerning the response to cytokines and to inflammatory stimuli.

Outcome of acute renal failure associated with cardiac surgery in infants

OBJECTIVE

To analyze the impact of acute renal failure (ARF) on the evolution of infants undergoing cardiac surgery.

METHODS

We assessed 15 infants undergoing cardiac surgery who developed (ARF). Their demographic, clinical and surgical data, and evolution were analyzed.

RESULTS

Their mean age was 4.4+/-4.0 months (8 days to 24 months). Twelve infants were males, and 4 patients already had ARF at surgery. The primary cause of ARF was immediate acute cardiac dysfunction in 10 infants, cardiac dysfunction associated with sepsis in 2 infants, and isolated sepsis in 3 infants. All children depended on mechanical ventilation during their postoperative period, 14 infants used vasoactive drugs, and 11 had an infectious process associated with ARF. Thirteen infants required dialytic treatment. Eleven infants developed oluguric ARF, and all had to undergo peritoneal dialysis; of the 4 patients with non-oliguric, 2 required dialysis, the main indication being hypervolemia. Of these 13 dialyzed infants, 4 died in the first 24 hours because of the severity of the underlying cardiac disease (mean urea level of 49+/-20 mg/dl). The mortality rate for the entire group was 60%, and it was higher among the patients with oliguria ARF (73% vs 25%, p<0. 001). The cause of death was acute cardiac dysfunction in 6 infants (early type-1 ARF) and sepsis in the 3 remaining infants (late type-2 ARF).

CONCLUSION

The mortality rate of ARF associated with cardiac surgery in infants was hight, being higher among children with oliguria; peritoneal dialysis was indicated due to clinically uncontrolled hypervolemia and not to the uremic hypercatabolic state.

Assessing the antimicrobial prescription request process in a teaching hospital in Brazil: regulations and training

It is known that antimicrobials are often prescribed inappropriately. One method used to deal with this problem is to regulate antimicrobial use by monitoring prescriptions. We report a study of physician compliance with the request for antibiotic process which was prepared and reviewed by a special infection control committee in our hospital the Nosocomial Infection Prevention Service (SCIH). The objective of this study was to identify the profile of inappropriate requests for restricted therapeutic antimicrobials used at Nossa Senhora da Conceição Hospital (HNSC), in Porto Alegre, Brazil. All 3,389 requests for therapeutic antimicrobials made between May 20, and October 31, 1996, were assessed and classified as appropriate and inappropriate. We determined that 17. 8% of the requests were inappropriate (a total of 720 errors). These were categorized according to 12 reasons for inappropriateness. Of these, the 3 most frequent inappropriate requests were deviation from standard use (26.73%), inappropriate length of treatment (23. 19%), and unfounded justification (13.61%). The reasons for inappropriateness were also arranged in three categories considering the following aspects: I. technical (59%); II. compatibility with the institutional program (32.36%), and III. administrative (8.61%). The 720 requests that were initially rejected were evaluated to see how antibiotic use was affected. In approximately 400 (55%), the forms could be appropriately modified after discussion with the physician. We conclude from this study that most of the inappropriate requests for antimicrobials in our hospital can be remedied by educating the staff since the errors were largely technical in nature. Thus, the SCIH should focus more on its role as an educational rather than as a regulatory body. By expanding this educational role, we anticipate improved physician compliance with our guidelines, and more appropriate antimicrobial prescribing and usage.

Biophysical and structural characterization of 1H-NMR-detectable mobile lipid domains in NIH-3T3 fibroblasts

Nature and subcellular localization of 1H-NMR-detectable mobile lipid domains (ML) were investigated by NMR, Nile red fluorescence and electron microscopy, in NIH-3T3 fibroblasts and their H-ras transformants (3T3ras) transfected with a high number of oncogene copies. Substantial ML levels (ratio of (CH2)n/CH3 peak areas R=1. 56+/-0.33) were associated in untransformed fibroblasts with both (a) intramembrane amorphous lipid vesicles, about 60 nm in diameter, distinct from caveolae; and (b) cytoplasmic, osmiophilic lipid bodies surrounded by own membrane, endowed of intramembrane particles. 2D NMR maps demonstrated that ML comprised both mono- and polyunsaturated fatty chains. Lower ML signals were detected in 3T3ras (R=0.76+/-0.37), under various conditions of cell growth. Very few (if any) lipid bodies and vesicles were detected in the cytoplasmic or membrane compartments of 3T3ras cells with R<0.4, while only intramembrane lipid vesicles were associated with moderate R values. Involvement of phosphatidylcholine hydrolysis in ML generation was demonstrated by selective inhibition of endogenous phospholipase C (PC-plc) or by exposure to bacterial PC-plc. This study indicates that: (1) both cytoplasmic lipid bodies and membrane vesicles (possibly in mutual dynamic exchange) may contribute (although to a different extent) to ML signals; and (2) high levels of ras-transfection either inhibit ML formation or facilitate their extrusion from the cell.

Tumor microcirculation and its significance in therapy: possible role of omega-3 fatty acids as rheological modifiers

Despite the great efforts to find new drugs or devices to suppress cancer cells, attempts to modify microcirculation and therefore the state of tumor cells and their surrounding normal tissues have not been given the attention they deserve. Solid tumors are composed of highly heterogeneous populations of malignant, stromal and inflammatory cells in a continuously adapting extracellular matrix. All of the above components interact and regulate each other to produce distinct microenvironments within the tumor mass. Abnormal microcirculation plays a particular role in the maintenance of this anomalous condition and favors the formation of metastasis, but on the other hand provides the therapist with an important site for intervention. In this brief overview we attempt to outline three aspects: (a) how the anomalous tumor blood flow provokes the nonuniform distribution of oxygen and nutrients within the tumor mass, thus determining different responses to the various cancer therapies; (b) how hemorheology is the clinical parameter most easily modified and (c) how omega-3 essential fatty acids are natural drugs that could be used in this sense beyond their antitumoral properties.

Hyperthermic effects on the human metastatic liver: a TEM study

Using ultrastructural analysis, we studied the effects of hyperthermic treatment of one case of human liver metastasis from colon carcinoma. The results indicate that the main hyperthermic response involves the neoplastic and the histiocytic cell population. The drastic decrease in metastatic cells was accompanied by the appearance of cell fragments and apoptotic bodies. Consequently, the histiocytic component (Kupffer cells) showed increased frequency, indicating an activated state. The data are consistent with a direct action of the heat on tumor cells with subsequent activation of Kupffer cells.

Tumor interstitial fluid: misconsidered component of the internal milieu of a solid tumor

The tumor interstitial fluid (TIF) is a fluid phase present in the extracellular space of all tumors whose importance in oncology is seldom recognized. In order to stimulate other researchers to give it the due importance, a review of the available data (including our own) is provided. An hypothesis is presented for the genesis, fate and role of the TIF in the processes of invasion, growth and metastatization. Open questions regarding the TIF's role in tumor response to therapy are raised.

Characterization of the metabolism of perinecrotic cells in solid tumors by enzyme histochemistry

Hypoxic tumor cells resist most therapies and cause tumor regrowth when their environment improves. Identifying the adaptation strategies to hypoxia would help develop better tailored cancer therapies. Ehrlich carcinomas implanted on mice were analyzed histochemically for the following enzyme activities: lactate, succinate and glucose-6-phosphate dehydrogenases, dihydrofolate reductase, purine nucleoside phosphorylase, xanthine oxidoreductase, and acid phosphatase. With the exception of xanthine oxidoreductase, which was not active in tumor cells, and of succinate dehydrogenase the activity of which was not significatively altered, all other activities were much higher in perinecrotic cells with respect to cells close to blood vessels. These data suggest the integration of metabolic paths allowing purine and lipid biosyntheses. Degradation products from the necrosis are presumed to be employed as surrogates of blood-borne nutritive substances by cells distant from the vascularization.

Lysosomal exocytosis induced by hyperthermia: a new model of cancer death. III. Effect on liver metastasis

The purpose of the present study was to evaluate by morphological approaches (light and electron microscopy), the effect of hyperthermic treatment in one case of human liver metastasis. The results demonstrate that hyperthermia causes a significant reduction of the metastatic cells circulating into sinusoids and the "normalization" of the hepatocytes substructure. The data are consistent with a direct and/or indirect action of the temperature on the presence of infiltrating tumor cells. Particular importance is attributed to a general activation of lysosomes present in neoplastic cells, Kupffer cells and hepatocytes.

Changes in the zonation of lactate dehydrogenase activity in lobules of rat liver after experimentally induced colon carcinoma metastases

Visualization of lactate dehydrogenase (LDH) activity with Neotetrazolium as final electron acceptor under anaerobic conditions and an incubation medium containing polyvinyl alcohol showed that under normal physiological conditions a zonal distribution of LDH activity is present in the liver lobule of male rats. Periportal hepatocytes contain more LDH activity than pericentral hepatocytes. This difference is due to the role of LDH both in gluconeogenesis (periportal cells) and glycolysis (pericentral cells). In livers containing metastases from colon carcinoma, areas of the parenchyma which are not affected by tumour growth maintain such zonation in the lobule, whereas areas close to metastatic foci show increased activity which is distributed uniformly over the lobule. This change may be explained by a Cori's cycle-like relationship between malignant cells and the surrounding hepatocytes due to glucose consumption and lactate production by the tumour cells. Within the metastatic foci, a zonation of LDH activity was also observed. Malignant cells close to the edge of the tumours contained the lowest activity, whereas activity increased inwards. Cancer cells directly surrounding necrotic areas showed the highest activity. Such patterns are in line with increasing anaerobic glycolysis towards the inner metastatic regions. Anaerobic glycolysis supplies limited amounts of ATP with concomitant lactate production but also large amounts of metabolites for RNA, DNA, lipid and complex carbohydrate synthesis. Lactate that is produced by the metastases induces adaptive changes in surrounding hepatocytes to convert this excess of lactate effectively.

Quantitative comparison between the gel-film and polyvinyl alcohol methods for dehydrogenase histochemistry reveals different intercellular distribution patterns of glucose-6-phosphate and lactate dehydrogenases in mouse liver

The precise histochemical localization and quantification of the activity of soluble dehydrogenases in unfixed cryostat sections requires the use of tissue protectants. In this study, two protectants, polyvinyl alcohol (PVA) and agarose gel, were compared for assaying the activity of lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G6PDH) in normal female mouse liver. Quantification of enzyme activity was determined cytophotometrically in periportal (PP), pericentral (PC) and midzonal (MZ) areas. No coloured reaction product was present in PVA media after the incubation period. In contrast, the agarose gels appeared to be highly coloured after incubation. As a consequence, sections incubated with gel media were less intensely stained than those incubated in PVA-containing media. The specific G6PDH reaction (test minus control) yielded approximately 75% less formazan in sections incubated by the agarose gel method than with the PVA method. Further, the amount of formazan deposits attributable to G6PDH activity was highest in the midzonal and pericentral zones of the liver lobule with PVA media, and Kupffer cells could be discriminated easily because of their high G6PDH activity. Significant zonal differences or Kupffer cells could not be observed when agarose gel films were used for the detection of G6PDH activity. The LDH localization patterns appeared to be more uniform after incubation with both methods: no significant differences in specific test minus control reactions were seen between PP, PC and MZ. However, less formazan production (33%) was detected in sections incubated with agarose gels when compared with those incubated with PVA media.(ABSTRACT TRUNCATED AT 250 WORDS)

Neglected factors in cancer treatment: cellular interactions and dynamic microenvironment in solid tumors

Solid tumors are "organoids" consisting of highly heterogeneous populations of malignant, stromal and inflammatory cells and dynamic extracellular matrix. In particular, distinct cellular microenvironments are observed. The survival strategies of malignant cells might therefore be highly differentiated, causing the high genotypic and phenotypic instability characteristic of malignant cells in vivo. A constant interplay between the tumor compartments and the host immune and hemostatic systems determines the behavior of the tumor. A description of typical microenvironments and of cellular and matrix interactions is provided. Based on these, it is here postulated that: (a) any cancer treatment, by influencing differently the various tumor compartments, will alter previously established equilibria; (b) the behavior (growth, invasiveness, metastatic potential, resistance to further treatment) of a malignancy after treatment might be altered with respect to what is assumed in terms of effect of the treatment on the malignant cells alone.

Omega-3 fatty acids can improve radioresponse modifying tumor interstitial pressure, blood rheology and membrane peroxidability

Several studies provide evidence that hypoxic cells present in animal and human solid tumors, may be critical for the successful treatment of cancer. In particular hypoxic cells are resistant to ionizing radiation, photodynamic treatment and the large majority of chemotherapeutic drugs. Hypoxia is generally due to the inadequacy of vascular beds supporting the tumor and to an abnormal microcirculation. Three parameters, tumor interstitial fluid, hemorheological factors and lipoperoxidation, are considered and tentatively associated as playing a role in hypoxic cell treatment. Omega three fatty acids modify these factors and are discussed for their possible ability to enhance tumor cells susceptibility to radiotherapy.

Tumor angiogenesis: evidence of new blood channels from plasma infiltrations

Stroma formation in Ehrlich carcinoma, studied with histochemical and TEM techniques, is similar to wound healing. In this tumour mast cells, macrophages, adipocytes, platelets and fibrin seem to co-operate locally with malignant cells in regulating stroma formation. The gaps opened in the tumor parenchyma by plasma outpouring from local blood vessels seem to offer easy routes for endothelial cell migration towards ill-nourished areas, and may explain the irregular aspect of tumor microvascularity.

Tumor hypoxia, reoxygenation and oxygenation strategies: possible role in photodynamic therapy

The concept of hypoxia and its role in tumor therapy are currently under re-evaluation. Poor oxygenation is no longer visualized as an independent feature promoting necrosis and resistance to treatments, but rather as one of the several interdependent microenvironmental parameters associated with impaired blood perfusion. Tumor cells display several survival strategies and remain clonogenic for long periods in nutrient-deprived situations. Reoxygenation may cause lethal damage, improve the response to therapy, or else allow the cell variants adapted to hypoxia to resume proliferation with enhanced aggressiveness and resistance to treatment. The blood supply parameters, oxygenation status and metabolism of malignant cells are discussed here from the standpoint of tumor photodynamic therapy. The role of the tumor interstitial fluid as oxygen- and sensitizer-carrier is discussed. Techniques for assessing tumor oxygenation and for mapping hypoxic territories are described. Strategies for locally improving the oxygenation levels or for selectively destroying the hypoxic populations are outlined.

In situ lactate dehydrogenase patterns as markers of tumour oxygenation

The histochemical patterns of lactate dehydrogenase, LDH, are here proposed as indicators of the local levels of oxygenation of malignant tissue. This parameter has outstanding importance in determining the tumour aggressiveness and response to treatment. The tetrazolium salt reaction previously proposed for the mapping of hypoxia has been improved by the use of polyvinyl alcohol as a tissue stabilizer. The intracellular coloured products of this reaction appear in two distinct forms, diffuse and granular, which we previously postulated to be indicative of LDH isoenzymes soluble and bound, respectively. Solubility is promoted by H-LDH subunits preferentially synthesized under good oxygenation; binding to membranes is favoured by the presence of M-LDH subunits preferentially active under poor oxygeneration. A reversible shift between the two forms apparently regulates the cells' metabolic adaptation to different stress situations. We assume that the anoxic shock protein LDHk exists exclusively in the bound form. In the Ehrlich carcinoma model previously employed, we verify a drift towards the exclusive presence of the granular form as the section's depth increases and/or when the cuff width decreases. This trend is ascribed to a progressive worsening of the local oxygenation levels. At the tumour interface, a chronic inflammatory tissue (notoriously highly hypoxic) is characterized by a granular LDH activity. New models of hypoxia are proposed and discussed for explaining the patterns here described and observed also in other studies, namely those derived from hyperviscosaemia, damaged endothelia, fibrosis, anaemia, poor ventilation and impaired cardio-vascular system.

Stroma formation in Ehrlich carcinoma. I. Oedema phase. A mitosis burst as an index of physiological reoxygenation?

Tumor stroma induction has been shown closely to resemble wound repair process, both involving the replacement of a fibrin gel by vascularized connective tissue. In such a process the initial phase of hyperpermeability of blood vessels leads to diffuse oedema. It is here reported that cell loosening and a remarkably high mitotic burst were observed in Ehrlich carcinoma in regions in contact with the exudate, particularly at the perinecrotic (hypoxic) region. This suggests both an enhanced cell detachment from the tumour parenchyma and an improvement of the microenvironment, the exudate thus appearing as beneficial to the malignant cells contributing to the reoxygenation of formerly hypoxic regions. The temporary and well-localized concentration of mitoses in inner tumour areas has perhaps been disregarded by the pathologists engaged in mitosis counting for tumour grading. Peripheric and intraparenchymal concentrations of mast cells, lipid pools and platelets were seen in apparently key geometric disposition for controlling fibrin deposition and angiogenesis. Hypoxia is known to cause resistance to oxygen-dependent treatments and to facilitate cell detachment; normal fibroblasts respond and survive under hypoxic conditions by exhibiting features of the malignant phenotype. During reoxygenation, gene instability, cellular heterogeneity and increased drug resistance and metastatic spread have been reported. A reoxygenation process can also be deduced from several other histochemical and morphological patterns observed in this study. The findings here reported thus suggest that the oedema phase is a crucial phase regulating growth, invasion and dissemination of tumour cell populations, that should be specifically addressed therapeutically.

Histochemical probes for the detection of hypoxic tumour cells

Hypoxia is thought to be a major cause of failure in cancer treatment. In this paper, we report methods transposable to clinical practice, for identifying hypoxic tumour cells. They consist of histochemical tests for revealing lactate dehydrogenase activity, endogenous lactate and accumulation of neutral fat. An ascites tumour (Yoshida hepatoma) and a solid tumour (Ehrlich carcinoma) were used as the experimental models. A gel film technique was used for visualizing lactate dehydrogenase and "nothing dehydrogenase" (or endogenous lactate). The fluorescent dyes Nile Red and Acridine Orange were used to demonstrate lipid accumulation and to visualize the tumour morphology, respectively. Tumour cells at the edge of areas of necrosis and at a distance of about 130 microns from a blood vessel were presumed to be hypoxic and showed the following features: 1) a dark blue granular pattern of lactate dehydrogenase (LDH) activity, ascribed to intense activity of the LDH5 and/or LDHk isoenzymes bound to membranous structures; 2) an intense granular positivity of "Nothing Dehydrogenase" due to high concentrations of endogenous lactate; 3) neutral lipid droplets emitting an intense yellow fluorescence in Nile Red-stained preparations; 4) a yellow cytoplasmic fluorescence in Acridine Orange-stained sections, attributable to a low cellular RNA content. Electron microscopy revealed moderately osmiophilic lipid globules in close association with damaged mitochondria. Better oxygenated cells showed: (a) a reddish-blue diffuse pattern of LDH, ascribed to moderately active soluble LDH isoenzymes containing H subunits; (b) almost no "Nothing Dehydrogenase" positivity; (c) no cytoplasmic lipid droplets; and (d) an intense orange-red fluorescence in the cytoplasm of Acridine Orange-stained specimens, due to high concentrations of cellular RNA. Nile Red fluorescence showed that the lipids of the solid tumour membranes were more hydrophobic than in the normal surrounding tissue. This suggests that there are abnormal domains of neutral lipids in the tumour cell membranes. In solid tumours, cells with the characteristics attributable to hypoxia were usually observed on the edge of necrosis of cuff-like formations. In very advanced growth stages, however, they were also seen surrounding (and occasionally clogging) blood vessels, or in tentacular formations coming from a necrosis border and polarized towards the vessels. Lipid-loaded cells were also seen in blood vessels distant from the tumour. These observations point towards a chemotactic process of hypoxic cells towards better environments.

Time-resolved fluorescence spectroscopy of hematoporphyrin-derivative in human lymphocytes

This paper reports on time-resolved microfluorimetric measurements on hematoporphyrin-derivative (HpD)-treated lymphocytes. HpD is at present widely used as a tumor-locating and photosensitizing drug. It is therefore of great importance to study the extent to which the HpD uptake process depends on cell functional and structural properties. Time-resolved fluorescence measurements in single cells are very useful in this respect, since they give information on the content of fluorescent molecules through fluorescence peak-intensity, and, indirectly, on the binding properties through the fluorescence decay times. In particular, we studied the dependence of HpD fluorescence on the cellular functional state. To this end, we performed in-cell fluorescence measurements on human lymphocytes, both in quiescent conditions and in the pre-replicative phase, after stimulation with phytohemagglutinin (PHA). We found a higher HpD content in stimulated lymphocytes. Moreover, we found a spectral band around 575 nm, corresponding to a particular porphyrin species, in which the differences between normal and stimulated lymphocytes are more striking. The porphyrin species emitting in this band seems to play a role in the specific interaction of HpD with tumors, since a similar emission band has also been found in tumor cells containing HpD.

Spectroscopic studies of hematoporphyrin-derivative in culture medium

This work reports on studies of hematoporphyrin-derivative (HpD) behaviour in culture medium. Absorption, excitation and emission spectra, together with time-resolved fluorescence measurements, were performed. In previous works, similar studies had been carried out on HpD in saline and in lymphocytes: a new porphyrin species (NPS) and the environmental conditions for its formation in saline were studied. A fluorescent emission similar to that presented by the NPS is reported to be more likely in tumor rather than in normal HpD-treated cells, it was also found in greater amounts in lymphocytes in the pre-replicative phase, as compared with quiescent ones. The higher NPS content in stimulated rather than in quiescent lymphocytes may be due either to a differential uptake, as compared with other HpD components, or to a differential formation rate in cells, because of different microenvironmental conditions. To distinguish between these two main assumptions, the formation of NPS in culture medium was studied. The process was very slow: no NPS appeared within the first 40 h. The incubation time of lymphocytes in culture medium added with HpD in the experiments performed was only 1 h and therefore a differential formation rate of NPS may explain the higher content found in stimulated lymphocytes.

An automatic pulsed laser microfluorometer with high spatial and temporal resolution

The paper describes an automatic pulsed laser microfluorometer with high spatial and temporal resolution, developed in our laboratories. The instrument consists of: (i) a nitrogen-laser-pumped dye-laser for the excitation of the fluorescence, (ii) a microscope with additional optics to focus the excitation beam on the sample and to collect the fluorescence, (iii) filters or monochromators to select the output wavelength, (iv) a fast photomultiplier tube to detect the signal, and (v) a dual time-scale microprocessor-controlled signal averager for the acquisition and processing of the signal. Examples are given that show the potential of the time-resolved fluorescence microscopy in studying, quantitatively and qualitatively, the properties of fluorescent molecules.

The time-dependent behaviour of hematoporphyrin-derivative in saline: a study of spectral modifications

Hematoporphyrin-Derivative (HpD), a widely-used tumor-specific photosensitizer, is a complex mixture of porphyrins whose composition has yet to be clarified. This paper reports on the behaviour of HpD in saline. From a spectroscopic point of view, the fresh solution is characterized by two main absorption peaks, attributable to monomeric and dimeric forms. With aging, a new porphyrin species (NPS) appears. To define the NPS, absorption, excitation and emission spectra were measured in different conditions and time-resolved fluorescence measurements were also performed. This species exhibits an absorption/excitation peak at 405 nm, an emission peak at 575 nm and a fluorescence decay time of approximately 3.5 ns. Its formation is strongly influenced by many environmental factors: in particular, gases diluted in the solution, temperature, pH and concentration. The presence of Oxygen and a pH value outside the 6-8 range may be considered inhibiting factors. The NPS seems to be quite important in the understanding of HpD tumor-specificity, since the presence of an emission band similar to the NPS one seems to be favoured in tumor cells as compared with normal cells.

Time-resolved fluorescence microscopy of hematoporphyrin-derivative in cells

This work presents measurements of time-resolved fluorescence microscopy of hematoporphyrin-derivative (HpD) in single cells of mice tissue (both tumor and normal cells), in HeLa Cells, and in solution. The measurements were performed using a pulsed-laser microfluorometer with high spatial and temporal resolution. In agreement with the results obtained with other techniques, it has been found that the tumor cells examined present an HpD uptake about five times higher than that of the normal cells of the corresponding tissue and that, within a cell, HpD become localized mainly in the cytoplasm. It has also been found that the fluorescence decay time is different in cells as compared with solution, and that the presence of HpD stabilizes cell auto-fluorescence. These results are discussed.

Versatile digital lock-in detection technique: application to spectrofluorometry and other fields

A digital lock-in detection technique which overcomes some practical limitations of the analog lock-in amplifiers is described. An example of implementation is given, based on multichannel pulse analyzers. Some representative results are reported for two typical application fields of lock-in techniques, namely optical spectrometry and semiconductor profiling with C-V techniques. Advantages and limitation of the technique are discussed as well as adaptation to various modulation waveforms.