The Impact of Anti-SARS-CoV-2 Vaccine in Patients with Systemic Lupus Erythematosus: A Multicentre Cohort Study

Vulnerable subjects, including systemic lupus erythematosus (SLE) patients, have been prioritised to receive anti-SARS-CoV-2 vaccines. Few data about the safety of these vaccines in SLE are available. The aim of our study is to investigate the safety of anti-SARS-CoV-2 vaccines in SLE. We included 452 SLE patients, referring to seven tertiary centres, who were immunised. A total of 119 (26%) reported side effects (SE) after the first and/or the second shot (the most frequent SE were fever, local reaction, fatigue, and arthralgia). Patients with constitutional symptoms and those on an immunosuppressive regimen (especially belimumab) showed more SE. In addition, 19 (4%) had a flare after the immunisation (flares classified by organ involvement: six musculoskeletal with constitutional symptoms, four renal, three cardio-respiratory, three haematological, two mucocutaneous). None of the patients needed hospitalisation and none died. Moreover, 15 required a transient increase in corticosteroids and four were treated with steroid pulses. One patient required an additional rituximab course. Anti-dsDNA, moderate/high DAS before vaccine, and belimumab were found more frequently in patients with disease flare. Anti-SARS-CoV-2 vaccines are safe in SLE patients, and they should be recommended in these patients, as the potential benefits widely outweigh the risk of SE. Treatment adjustment might be considered with the aim of minimising SE risk and flare.

Evaluation of the antifungal effect of EDTA, a metal chelator agent, on Candida albicans biofilm

OBJECTIVE

Candida albicans biofilm is frequently found on artificial surfaces and the infections related to biofilm are difficult to eliminate, as they require the removal of artificial devices and treatment with antifungal drugs. Nowadays, fungal growth in biofilms is difficult to eradicate with conventional antifungal drugs such as fluconazole. Among chelating agents, disodium salt-Ethylene Diamine Tetraacetic Acid (EDTA) is known to have antifungal activity. In this study, we examined the in vitro activity of the EDTA and the antifungal drug fluconazole against C. albicans mature biofilm.

MATERIALS AND METHODS

C. albicans ATCC 20191, fluconazole-susceptible strain, was grown at an inoculum starter of 1 x 106 cells/ml for 72 h in 24-well microtiter plates and was further treated for 24 h with EDTA and/or fluconazole. Antifungal activities in biofilms were expressed as reduction in optical density (OD) determined by a 2,3-bis (2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide (XTT) colorimetric assay and compared to untreated biofilms.

RESULTS

Colorimetric readings revealed that EDTA alone (at 25 and 2.5 mM) significantly reduced fungal metabolic activity in preformed biofilms. Also, EDTA combined with fluconazole significantly reduced the growth of biofilm when compared to biofilm treated with fluconazole alone (at 25 and 2.5 µg/ml).

CONCLUSIONS

Our data suggest that the employment of EDTA or other chemicals destabilizers of the biofilm matrix, in combination with antifungal drugs, could lead to the development of new strategies for the management of infections associated to Candida biofilm. Another relevant result of our study suggests that the initial cell concentration, probably through mechanisms of quorum sensing, affects the cellular viability during the process of biofilm formation.

In vitro and in vivo conditional sensitization of hepatocellular carcinoma cells to TNF-induced apoptosis by taxol

High mortality among hepatocellular carcinoma (HCC) patients reflects both late diagnosis and low curability, due to pharmacoresistance. Taxol (TAX) is toxic for many human HCC-derived cell lines, yet its clinical efficacy on HCCs is poor. Combining TAX with other drugs appears a promising possibility to overcome such refractoriness. We analyzed whether combining tumor necrosis factor (TNF) with TAX would improve their toxicity. Human HCC-derived cell lines were treated with TAX or TNF, alone or combined. Apoptosis was assessed by morphology and flow-cytometry. Several pro- and anti-apoptotic molecules were evaluated by western blotting and/or enzymatic assay. After a 24 hour treatment, TNF was ineffective and TAX modestly cytotoxic, whereas HCC cells were conditionally sensitized to TNF by TAX. Indeed some relevant parameters were shifted to a prodeath setting: TNF-receptor 1 was increased, SOCS3, c-FLIP and pSTAT3 were markedly downregulated. These observations provide a significant clue to critically improve the drug susceptibility of HCC cells by combining 2 agents, TAX and TNF. The sequential application of TAX at a low dosage followed by TNF for only a short time triggered a strong apoptotic response. Of interest, prior TAX administration could also sensitize to TNF-induced apoptosis in the Yoshida AH-130 hepatoma transplanted in mice. Therefore, scrutinizing the possibility to develop similar combination drug regimens in suitable preclinical models seems highly advisable.

[Energy expenditure in construction industry]

The aim of this study is to show the results obtained from measuring energy expenditure (EE) during work, through portable devices, in a group of male construction workers. After defining cardio-respiratory parameters in laboratory, authors applied to all subjects an heart rate monitor for measuring the heart rate (HR) and, at the same time, a calorimeter for measuring energy expenditure (EE). To analyse data obtained, authors calculate the Relative Aerobic Strain (RAS), both for the measurements of EE and for HR detected. Results confirm that in many of the typical activities of construction industry, in particular in those characterised by an higher component of manual engagement compared to foreman, workloads are exceeding limits of the probable threshold fatigue (33% of RAS), both for energy expenditure than for HR measured.

Cytotoxic properties of clofibrate and other peroxisome proliferators: relevance to cancer progression

The biological activity of peroxisome proliferators (PPs) is mediated by a class of receptors, known as PPARs (PP-Activated Receptor), belonging to the nuclear receptor superfamily. Upon ligand binding, PPARs dimerize with retinoid receptors, translocate to the nucleus, recognize specific PP-responsive elements on DNA and transactivate a number of genes. Several processes are regulated by PPARs, such as mitochondrial and peroxisomal fatty acid uptake and beta-oxidation, inflammation, intracellular lipid trafficking, cell proliferation and death. In addition, PPARs have been proposed to act as tumor suppressors or as tumor promoters, depending on the circumstances. In particular, PPs have been extensively studied for their hepatocarcinogenic action in rodents, most often ascribed to their antiapoptotic action. Recent evidence, however, has been provided about the antiproliferative, proapoptotic, and differentiation-promoting activities displayed by PPAR ligands. The present review will focus on the cytotoxic effects exerted by several PPs, among which clofibrate, on different types of tumor cells, with particular reference to the mechanisms of cell death and to their relevance to cancer induction and progression.

Deacetylase inhibitors modulate the myostatin/follistatin axis without improving cachexia in tumor-bearing mice

Muscle wasting, as occurring in cancer cachexia, is primarily characterized by protein hypercatabolism and increased expression of ubiquitin ligases, such as atrogin-1/MAFbx and MuRF-1. Myostatin, a member of the TGFbeta superfamily, negatively regulates skeletal muscle mass and we showed that increased myostatin signaling occurs in experimental cancer cachexia. On the other hand, enhanced expression of follistatin, an antagonist of myostatin, by inhibitors of histone deacetylases, such as valproic acid or trichostatin-A, has been shown to increase myogenesis and myofiber size in mdx mice. For this reason, in the present study we evaluated whether valproic acid or trichostatin-A can restore muscle mass in C26 tumor-bearing mice. Tumor growth induces a marked and progressive loss of body and muscle weight, associated with increased expression of myostatin and ubiquitin ligases. Treatment with valproic acid decreases muscle myostatin levels and enhances both follistatin expression and the inactivating phosphorylation of GSK-3beta, while these parameters are not affected by trichostatin-A. Neither agent, however, counteracts muscle atrophy or ubiquitin ligase hyperexpression. Therefore, modulation of the myostatin/follistatin axis in itself does not appear sufficient to correct muscle atrophy in cancer cachexia.

Mechanisms of clofibrate-induced apoptosis in Yoshida AH-130 hepatoma cells

Peroxisome proliferators (PPs) are a class of compounds that exert their nominal effects through the peroxisome proliferator-activated receptors. PPs, among which clofibrate (CF), have been extensively studied for their hepatocarcinogenic properties in rodents, generally ascribed to their antiapoptotic action. However, previous results demonstrated that various PPs may also have apoptogenic properties. CF, in particular, promptly induces a massive apoptotic death in cell lines established from murine or human hepatomas and from breast or lung cancers as well. The present study was aimed at elucidating the apoptotic pathway(s) triggered by CF in AH-130 cells. The results show that CF-induced cell death is completely blocked by the poly-caspase inhibitor z-VAD-fmk and that caspases 3, 8, and 9 are early activated. Consistently, cytochrome c is released from mitochondria, and CF cytotoxicity is inhibited by cyclosporine A, partially at least. In addition, the occurrence of endoplasmic reticulum (ER) stress is suggested by the observation that the levels of phosphorylated eIF2alpha and JNK increase in CF-treated cells, while the caspase 2 precursor protein levels are concurrently reduced. Finally, some degree of calpain activation also takes place, as suggested by the appearance of fodrin cleavage products. The present findings demonstrate that CF-induced apoptosis in the Yoshida AH-130 cells basically is a caspase-dependent process that involves more than a single mechanisms. Activation of the intrinsic apoptotic pathway and ER stress both play a major and concurrent role, while calpain activation seems to have only a marginal part in the process.

Muscle myostatin signalling is enhanced in experimental cancer cachexia

BACKGROUND/AIMS

Myostatin belongs to the transforming growth factor-beta superfamily and negatively regulates skeletal muscle mass. Its deletion induces muscle overgrowth, while, on the contrary, its overexpression or systemic administration cause muscle atrophy. The present study was aimed at investigating whether muscle depletion as occurring in an experimental model of cancer cachexia, the rat bearing the Yoshida AH-130 hepatoma, is associated with modulations of myostatin signalling and whether the cytokine tumour necrosis factor-alpha may be relevant in this regard.

MATERIALS AND METHODS

Protein levels of myostatin, follistatin (myostatin endogenous inhibitor) and the activin receptor type IIB have been evaluated in the gastrocnemius of tumour-bearing rats by Western blotting. Circulating myostatin and follistatin in tumour hosts were evaluated by immunoprecipitation, while the DNA-binding activity of the SMAD transcription factors was determined by electrophoretic-mobility shift assay.

RESULTS

In day 4 tumour hosts muscle myostatin levels were comparable to controls, yet follistatin was reduced, and SMAD DNA-binding activity was enhanced. At day 7, both myostatin and follistatin increased in tumour bearers, while SMAD DNA-binding activity was unchanged. To investigate whether tumour necrosis factor-alpha contributed to induce such changes, rats were administered pentoxifylline, an inhibitor of tumour necrosis factor-alpha synthesis that partially corrects muscle depletion in tumour-bearing rats. The drug reduced both myostatin expression and SMAD DNA-binding activity in day 4 tumour hosts and up-regulated follistatin at day 7.

CONCLUSIONS

These observations suggest that myostatin pathway should be regarded as a potential therapeutic target in cancer cachexia.

Intracellular free iron and acidic pathways mediate TNF-induced death of rat hepatoma cells

Rat hepatoma HTC cells are intrinsically resistant to various apoptosis-inducing agents. Strategies to induce death in hepatoma cells are needed and the present experimental study was aimed to investigate the sensitivity of HTC cells to TNF and to clarify the mechanisms of action of this cytokine. Cells were treated with TNF and death mechanisms characterized employing an integration of morphological and biochemical techniques. HTC cells, sensitized to TNF toxicity with cycloheximide, died in a caspase-independent apoptosis-like manner. Although we found no evidence for a direct involvement of lysosomal cathepsins, bafilomycin A1 and ammonium chloride significantly attenuated TNF toxicity. Also desferrioxamine mesylate, an iron chelator, partly protected the cells from TNF, while a complete protection was afforded by combining ammonium chloride and iron chelator. Moreover, HTC were protected from TNF also by lipophylic antioxidants and diphenylene iodonium chloride, a NADPH oxidase inhibitor. These data depict a novel mechanism of TNF-mediated cytotoxicity in HTC cells, in which the endo-lysosomal compartment, NADPH oxidase and an iron-mediated pro-oxidant status contribute in determining a caspase-independent, apoptosis-like cell death.

Skeletal muscle wasting in tumor-bearing rats is associated with MyoD down-regulation

Cachexia is a syndrome characterized by profound skeletal muscle wasting that frequently complicates malignancies. A number of studies indicate that protein hypercatabolism, largely mediated by classical hormones and cytokines, is the major component of muscle depletion. Impaired regeneration has been suggested to contribute to the reduction of muscle size. In particular, it has been shown that the expression of MyoD, a muscle-specific transcription factor, is down-regulated by cytokines such as TNFalpha and IFNgamma in a NF-kappaB-dependent posttranscriptional manner. The present study investigated whether modulations of the transcription factor MyoD are associated with the onset of muscle wasting in a well established model of cancer cachexia. Rats bearing the Yoshida AH-130 hepatoma develop a condition of muscle protein hypercatabolism, largely dependent on TNFalpha bioactivity. In the gastrocnemius of these animals the expression of MyoD was markedly reduced, paralleling the decrease of muscle weight. This pattern is associated with increased nuclear translocation of AP-1, while DNA-binding assays did not detect any change in NF-kappaB activity. This is the first observation demonstrating that muscle depletion in tumor-bearing rats is associated with a down-regulation of MyoD levels. Although the underlying mechanisms remain to be clarified, this change is compatible with the hypothesis that a reduced expression of molecules involved in the regulation of the regenerative response may concur to muscle wasting in cancer cachexia.

Mice lacking TNFalpha receptors 1 and 2 are resistant to death and fulminant liver injury induced by agonistic anti-Fas antibody

The liver is particularly susceptible to Fas-mediated cytotoxicity. Mice given an adequate parenteral dose of agonistic anti-Fas antibody (aFas) or of FasL are known to develop a devastating liver injury and to die in a few hours. The present work shows that mice lacking TNFR1 and TNFR2 (R(-)) both survive a single dose of aFas, otherwise rapidly lethal, and develop a mild form of hepatic damage, compared to the much more severe liver injury that in a few hours strikes wild-type mice (R(+)), eventually involving increased activity of proteases of different families (caspase 3-, 8-, and 9-like, calpains, cathepsin B). Neither the overall tissue levels of Fas and FasL nor Fas expression at the hepatocyte surface are altered in the liver of R(-) animals. The DNA-binding activity of the NF-kappaB transcription factor is enhanced after aFas treatment, but much more markedly in R(-) than in R(+) mice. Bcl2, while unchanged in untreated animals, is markedly upregulated in R(-) but not in R(+) mice challenged with aFas. The requirement of a normal TNFR1/TNFR2 phenotype for full deployment of the general and liver-specific aFas toxicity in mice most likely implies that treatment with aFas in some way results in activation of the TNFalpha-TNFRs system and that this activation synergizes with Fas-mediated signals in causing the fulminant liver injury and the animal death. The precise cellular and molecular details underlying this interplay between Fas- and TNFRs-mediated signaling systems in the general and liver-specific aFas toxicity largely remain to be clarified.

Anticytokine treatment prevents the increase in the activity of ATP-ubiquitin- and Ca(2+)-dependent proteolytic systems in the muscle of tumour-bearing rats

The ascites hepatoma Yoshida AH-130 induces loss of body weight and tissue waste. Tumour necrosis factor alpha (TNF-alpha) plays a pivotal role in the pathogenesis of muscle wasting in this model system, but other cytokines, such as interleukin-6, may be involved. In order to verify whether a combined anticytokine treatment may synergistically counteract muscle protein degradation, tumour bearing rats were treated with pentoxyfilline (PTX, an inhibitor of TNF-alpha synthesis), or with suramin (SUR, an antiprotozoal drug blocking the peripheral action of several cytokines including IL-6 and TNF-alpha), or both the drugs, and the effects on muscle proteolytic systems were assessed. Muscle protein loss in the AH-130-bearing rats was associated with increased activity of both the ATP-ubiquitin- and the calpain- dependent proteolytic pathways (246% and 230% of controls, respectively). Both PTX and SUR, either alone or in combination, prevented the depletion of muscle mass and significantly reduced the activity of muscle proteolytic systems. In particular, treatment with SUR, either alone or with PTX, induced a decrease in enzymatic activities to values similar to those of controls. The results obtained in the present paper demonstrate that: (i) muscle depletion in this model is indeed associated with increased proteasome- and calpain-dependent proteolysis, as previously suggested by increased mRNA expression of molecules pertaining to both pathways; (ii) anticytokine treatments effectively reduce muscle protein loss by down-regulating the activity of at least two major proteolitic systems; (iii) SUR is more effective than PTX in reducing the activity of proteolytic systems, possibly because of its multiple anticytokine action.

Cryosurgery plus adjuvant systemic alpha2-interferon for HPV-associated lesions

OBJECTIVE

The authors report their experience in patients with adjuvant systemic 2-interferon with the aim of defining the effectiveness, side-effects, indications and limitations of this treatment.

MATERIALS AND METHODS

From January 1989 to December 1996, 123 patients with genital, anorectal and perineal HPV lesions were treated with cryosurgery; adjuvant systemic a2-interferon was administered to 38 of them. There were 76 female and 47 male patients (median age of 29 years, range; 15-56 years). Clinical examinations included: digital rectal examination, head and neck examination, urethral meatus inspection and, in female patients, gynaecological examination; they underwent colposcopylurethroscopy, proctosigmoidoscopy, cystoscopy (in advanced disease); scraping for cytology and PCR analysis, and biopsy for histology. Twenty-three percent of patients had more than one site involved; upper digestive tract involvement was observed in 6.6% and 47% had lesions larger than 6 sqcm. Twenty-five females with genital lesions had esocervical lesions only; ten of them had SIL1, while seven a SIL3.

RESULTS

Ninety-eight out of 123 patients (79.7%) were recurrence-free after a median follow-up of 32 months. A recurrence was observed in 25 patients: in univariate analysis, recurrence of disease occurred more frequently in females (p = 0.04), in patients with longer duration of symptoms (p = 0.0002),with wider lesions (p = 0.00015), with head and neck involvement (p < 0.01), and in HIV-positive patients (p = 0.03). In multivariate analysis, duration of symptoms (p = 0.005), head and neck involvement (p = 0.01), and width of lesion > 3 sq cm (p = 0.025) were associated with increased risk

CONCLUSION

Our findings confirm the value of cryosurgery in the treatment HPV lesions; it is less traumatic, and gives good aesthetic and functional results; moreover, large lesions may be treated and the depth of cryonecrosis is more suitably adapted. Patients amenable to adjuvant treatment with a2-interferon should have multiorgan involvement, HPV type 16 or 18, lesions >3 sqcm, long lasting symptoms (>6 months) and presence of SIL.

Expression of protein kinase C beta1 confers resistance to TNFalpha- and paclitaxel-induced apoptosis in HT-29 colon carcinoma cells

The expression of different protein kinase C (PKC) isoenzymes has been shown to vary with proliferation rates, differentiation or apoptosis in normal colon crypts. In addition, the activity of some PKC isoenzymes appears to be reduced in colorectal cancer. The aim of the present work was to determine whether modulation of PKC expression would affect the susceptibility of a p53-defective colon carcinoma cell line to different apoptotic treatments. HT-29 cells exhibited sensitivity to paclitaxel (Taxol) and tumor necrosis factor alpha (TNFalpha) in a dose- and time-dependent manner but were relatively resistant to etoposide. Inhibition of PKC activity augmented the susceptibility of HT-29 cells to apoptosis, and phorbol ester induction of PKC reduced such susceptibility. Transfected HT-29(PKC) cells, hyper-expressing the beta1 isoform of PKC, were less sensitive to TNFalpha and paclitaxel than the normal counterpart. The present data 1) indicate that the expression of PKC influences the susceptibility of HT-29 colon cancer cells to apoptotic drugs apparently regardless of their mechanism of action, and 2) suggest paclitaxel as a potential candidate for the treatment of colon cancer, possibly in association with inhibitors of PKC (alpha and beta) at doses not cytotoxic per se.

Implication of Bcl-2 family genes in basal and D-amphetamine-induced apoptosis in preneoplastic and neoplastic rat liver lesions

Molecular mechanisms of basal and D-amphetamine (AMPH)-induced apoptosis were studied in rat liver nodules, 12 (N12) and 30 (N30) weeks after initiation, and in hepatocellular carcinoma (HCC) induced by diethylnitrosamine in rats subjected to resistant hepatocyte model. Basal apoptosis in hematoxylin/eosin- and propidium iodide-stained sections was higher in nodules and HCC than in normal livers. It sharply increased in all tissues 4 hours after AMPH treatment (10 mg/kg), and declined to basal levels at 8 to 12 hours in liver and N12, but remained high up to 18 hours in N30 and HCC. c-myc, Tgf-alpha, p53, and Bcl-X(S) messenger RNA (mRNA) levels were higher, and Bcl-2 mRNA was lower in N12 and/or N30 and HCC than in normal liver. Four hours after AMPH injection, increase in c-myc and decreases in Bcl-2 and Bcl-X(L) mRNAs occurred in all tissues, whereas p53, Bax, and Bcl-X(S) mRNAs increased in N30 and HCC. These changes disappeared in liver and N12 at 18 hours, but persisted in N30 and HCC. c-Myc, P53, Bcl-2, and Bax proteins in normal liver and HCC +/- AMPH showed similar patterns. Tgf-beta1, Tgf-beta-RIII, CD95, and CD95L mRNA levels underwent slight or no changes in any tissue +/- AMPH. Basal Hsp27 expression was high in nodules and HCC, and was stimulated by AMPH in liver and N12, but not in N30 and HCC. These data suggest a role of dysregulation of Bcl-2 family genes and, at least in atypical lesions, of p53 overexpression, in basal and AMPH-induced apoptosis in nodules and HCCs. Hsp27 does not appear to sufficiently protect atypical lesions against apoptosis.

Peroxisome proliferators induce apoptosis in hepatoma cells

In the AH-130 hepatoma, a poorly differentiated tumor, maintained by weekly transplantations in rats, a low percentage of cells spontaneously underwent apoptosis, mainly during the transition from logarithmic- to stationary-growth phase. It was possible to induce massive apoptosis of cells by treating them with clofibrate, a peroxisome proliferator and hypolipidemic drug. Similar results were obtained with HepG2 cells. With 1 mM clofibrate, apoptosis began to manifest itself after 1 h of treatment in vitro, and was assessed by morphological analysis, by DNA fragmentation carried out with agarose gel electrophoresis, and with flow cytometric determination of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling. The mechanisms whereby clofibrate induces apoptosis are still unclear. Since the peroxisome proliferator-activated receptor was expressed at a very low level and was not stimulated by clofibrate in the AH-130 hepatoma cells, its involvement seems unlikely. Moreover, lipid peroxidation was not increased after clofibrate treatment. Phospholipids and cholesterol were significantly decreased. The decreased cholesterol content might suggest an inhibition of the mevalonate pathway and, therefore, of isoprenylation of proteins involved in cell proliferation.

Rapid and extensive lethal action of clofibrate on hepatoma cells in vitro

Clofibrate, for a long time in use as a hypolipidemic drug, is a well known peroxisomal proliferator (PP) and hepatocarcinogen in rodents. We show here that in vitro 1 mM clofibrate induces a rapid and massive death of rat AH-130 hepatoma cells. Cell death was prominent already after 4 h of treatment, with a characteristic ;apoptotic' pattern by conventional microscopy. This was further supported by the pronounced chromatin condensation detectable on 4',6-diamine-2'-phenylindole dihydrochloride (DAPI) staining, the clearcut internucleosomal DNA fragmentation on agarose-gel electrophoresis (ladder pattern), and the accumulation of markedly hypochromic cells observed in flow cytometric DNA histograms. Consistently with the apoptotic features of the process, some parameters commonly used to detect cell death, such as plasma membrane permeabilization to trypan blue or propidium iodide, lack of mitochondrial retention of rhodamine 123, or extracellular release of lactate dehydrogenase, were all virtually negative. However, these same parameters became markedly positive after 24 h of treatment, which was suggestive for the occurrence of ;secondary' necrosis among AH-130 cells. By a combination of flow cytometric parameters, after 4 h on 1 mM clofibrate only 41% of the AH-130 cells could still be categorized as viable (i.e., non-apoptotic and non-necrotic), while 46% of cells appeared apoptotic and 13% necrotic. At 24 h, 67% of cells were necrotic, 20% apoptotic and only 13% non-apoptotic and non-necrotic. Apoptosis was also extensive in AH-130 cells treated with another PP such as nafenopin at 1 mM concentration and in human hepatoma HepG2 cells treated with clofibrate. By contrast, clofibrate did not cause apoptosis on primary rat hepatocyte cultures. These observations indicate that: (i) apart from their well-known cell growth-promoting action, PPs such as clofibrate or nafenopin may exert a substantial cytotoxic action on targets such as the AH-130 or HepG2 hepatoma cells; (ii) this cell death evolves from an initial 'apoptotic' to an eventual ;necrotic' pattern; (iii) detection of cell death requires the adoption of a full panel of tests, adequate to cover the whole evolving death pattern, while such tests may even be substantially misleading whenever applied individually; (iv) the cytotoxicity of clofibrate and similar agents on normal and, particularly, tumoural cells may deserve careful reevaluation.

Decreased expression of the high-mobility group protein T160 by antisense RNA impairs the growth of mouse fibroblasts

The T160 protein belongs to the HMG-1 box protein family and preferentially binds to non-B-DNA conformations with no sequence specificity. Its exact role has yet to be defined, though it seems to participate in processes involving DNA, such as replication, transcription and recombination. We have used an antisense RNA strategy to investigate its role in cell growth and proliferation. T160 expression is strongly suppressed by stable introduction of an antisense construct into NIH3T3 cells, and this decrease is accompanied by substantial changes in the growth properties of the stable transfectants. Impaired growth of T160- cells was mainly related to two mechanisms: i) decreased rates of cell proliferation at normal serum concentration; and ii) occurrence of cell death by apoptosis at low serum concentration, as demonstrated by both flow cytometry and microscopy. The finding that decreased T160 availability affects cell proliferation, provides further evidence of its involvement in a basic cell function, such as DNA replication.

Differential targeting and processing of procathepsin D in normal and transformed murine 3T3 fibroblasts

The kinetics of transport and the processing of procathepsin D (proCD), the precursor of a lysosomal aspartyl protease involved in tumor-cell proliferation and metastasis, were compared in normal and SV-40- or benzo[a]pyrene-transformed 3T3 mouse fibroblasts. Sorting of newly synthesized proCD in normal cells was almost complete within 3 hr, while in transformed cells a fraction of the precursor survives a long time. In both normal and transformed 3T3 cultures, secretion of proCD started at 3 hr of chase. However, in normal cells secretion of proCD remained constant between 3 and 24 hr of chase, while in transformed cells it increased along with the chase incubation. The efficiency of formation of the mannose-6-phosphate group on proCD varied among the 3 cell types, being minimal in benzo[a]pyrene-transformed 3T3 cells. Ammonium chloride, a drug known to disrupt the segregation and to enhance the secretion of lysosomal proenzymes, was 2-fold more effective in normal than in transformed 3T3 cells. Despite vacuolar alkalinization, about one third of proCD was segregated into the endosomal-lysosomal pathway in normal and in transformed 3T3 fibroblasts, indicating the existence in these cells of alternative, mannose-6-phosphate receptor-independent mechanisms for targeting proCD. Thus, while hypersecretion of proCD and reduced sensitivity to vacuolar alkalinization are common features of both transformed cell types, the mechanisms responsible for inefficient segregation of proCD may differ between virally and chemically transformed 3T3 cells.

Apoptosis of L929 cells by etoposide: a quantitative and kinetic approach

Exponentially growing L929 cells were continuously exposed to 1 or 10 microM etoposide (VP-16). The effects of such treatment on cell growth, cycle distribution, morphology, and selected biochemical events were examined. DNA synthesis rates were markedly decreased and the protein/DNA ratio increased (unbalanced growth). Growth was blocked, with most cells being cycle arrested by 24 h in (late S-)G2-M. An asynchronous process of cell death then developed. Cells initially shrank into eosinophilic, trypan blue-excluding bodies, which were then released into the medium, and eventually became permeable to trypan blue. Transmission electron microscopy confirmed that dying cells acquired an apoptotic morphotype, with compaction and margination of chromatin, loss of microvilli, and shrinkage of cytoplasm and nucleus. Tissue transglutaminase activity and intensity of immunostaining rapidly increased in treated cultures. Internucleosomal DNA fragmentation could not be detected by agarose gel electrophoresis, yet flow cytometry revealed that the apoptotic bodies had a very low DNA fluorescence (< or = 10% of the 2n value). In agreement with the microscopic findings, this suggested that extensive DNA degradation had occurred in dead cells. While rates of cell loss from the monolayer amounted to 21 and 57% day(-1) (1 and 10 microM VP-16, respectively), apoptotic indexes largely underestimated the extent of the process. These indexes only measured the accumulation of apoptotic bodies, i.e., the balance between their generation and disposal. The latter occurred by mechanisms similar to those that operate in tissues: "secondary necrosis" or phagocytosis by viable homotypic cells in the monolayer ("homophagy").

[Various personality traits of patients with psoriatic arthropathy]

It is well known that patients affected by rheumatic diseases may present specific pathological trends in personality structure, as has been extensively reported in literature. Our study was aimed at investigating several aspects of the personality traits of 20 patients with psoriatic arthropathy, compared with a group of 20 patients with rheumatoid arthritis. All patients were evaluated with appropriate rating scales assigned in auto and hetero-administration. The study results points to a personality trait disturbance in psoriatic arthritis patients, which can be clearly differentiated from the anxious habitus and/or reactive-depressive state observed in patients with rheumatoid arthritis.

Effect of 4-Hydroxynonenal on cell cycle progression and expression of differentiation-associated antigens in HL-60 cells

4-Hydroxynonenal (HNE) is a highly reactive aldehyde produced by lipid peroxidation of cellular membranes that inhibits growth and induces differentiation in HL-60 cells. Its mechanisms of action were investigated by analyzing the cell cycle distribution and the appearance of differentiated phenotypes in HL-60 cells. Data obtained by exposing cells to DMSO for 7.5 h (same time as for HNE treatment) or for the whole length of the experiments (5 d) were used for comparison. HNE induced a marked increase in the proportion of G0/G1 cells after 1 and 2 d. The brief DMSO treatment did not affect the distribution, whereas continuous exposure led to a progressive accumulation of cells in G0/G1 (maximal at day 5). The proportion of phagocytic cells gradually increased in HNE-treated and DMSO long-exposed cultures from day 2 and peaked at day 5 (35 and 63%, respectively), whereas the effect of the brief DMSO treatment was negligible. The expression of CD11b and CD67 increased in cells treated with HNE or continuously exposed to DMSO, whereas CD36 was expressed at low levels on both treatments. These results indicate that the pathway of the granulocytic differentiation induced by HNE in HL-60 cells differs from that of DMSO: with HNE, growth inhibition precedes the onset of differentiation, whereas in DMSO-treated cells the two processes are chronologically associated.

Synthesis, maturation and extracellular release of procathepsin D as influenced by cell proliferation or transformation

The relationship between cell growth and intra- and extracellular accumulation of cathepsin D (CD), a lysosomal endopeptidase involved in cell protein breakdown, was examined in cultures of normal and transformed BALB/c mouse 3T3 fibroblasts grown at various cell densities. In crowded cultures of normal 3T3 cells (doubling time, Td, 53 hr) intracellular CD activity was 2-fold higher than in sparse, rapidly-growing (Td, 27 hr) cultures. In uncrowded (Td, 18 hr) and crowded (Td, 32 hr) cultures of benzo[a]pyrene-transformed cells intracellular CD levels were one third and two thirds, respectively, of those measured in hyperconfluent 3T3 cultures. Regardless of cell density, SV-40-virus-transformed cells (Td, 12 hr) contained one third of CD levels found in hyperconfluent 3T3 cells. Both transformed cell lines released into the medium a higher proportion of CD, compared with their untransformed counterpart, yet the amount secreted was not sufficient to account for the reduced intracellular level of the enzyme. Serum withdrawal induced a marked increase of both intra- and extracellular levels of CD activity. In both normal and virally or chemically transformed 3T3 cells CD comprised a precursor (52 kDa) and processed mature polypeptides; the latter were mostly represented by a 48-kDa peptide, but a minor part was in a double-chain form (31 and 16 kDa respectively). The proportion of mature enzyme vs. precursor was much higher in confluent, slowly-growing cells than in fast-growing cells, whether normal or transformed. In the latter, conversion of mature 48-kDa peptide into the double-chain form occurred more efficiently.

Role of mitogen-induced calcium influx in the control of the cell cycle in Balb-c 3T3 fibroblasts

The role of mitogen-activated calcium influx from the extracellular medium in the control of cell proliferation was studied in Balb-c 3T3 fibroblasts. Stimulation of serum-deprived, quiescent cells with 10% foetal calf serum (FCS) induced a long-lasting (up to 70 min) elevation of intracellular free calcium concentration ([Ca2+]i). Both the sustained [Ca2+]i increase and the related inward current, described in a previous paper [Lovisolo D. Munaron L. Baccino FM. Bonelli G. (1992) Potassium and calcium currents activated by foetal calf serum in Balb-c 3T3 fibroblasts. Biochim. Biophys. Acta, 1104, 73-82], could be abolished either by chelation of extracellular calcium with EGTA or by SK&F 96365, an imidazole derivative that can block receptor-activated calcium channels. The effect of the abolition of these ionic signals on FCS-induced proliferation was investigated by adding either EGTA or SK&F 96365 to the culture medium during the first hours of stimulation of quiescent cells with 10% FCS. As measured after 24 h, a 22% inhibition of growth was observed when SK&F 96365 was added for the first hour, and stronger inhibitions, up to 56%, were obtained by adding the blocker for the first 2 or 4 h. Similar effects were observed with addition of 3 mM EGTA, though the inhibition was less marked for the 4 h treatment. By contrast, incubation with either substance in the next 4 h of serum stimulation did not influence cell growth, except for a slight inhibition observed when SK&F 96365 was applied from the 4th to the 8th hour. The reduction in growth resulting from the abolition of the early calcium influx was paralleled by an accumulation of cells in the G2/M phase. Both growth inhibition and G2/M accumulation were reversible, since after further 24 h in 10% FCS cells had fully recovered the exponential growth. These data indicate that the early calcium influx seen in response to mitogen stimulation develops on a timescale long enough to play a significant role in cell cycle progression, and that its block in the early G1 phase can lead to a reduction of proliferation by arresting cells in later stages of the cycle.

Sustained calcium influx activated by basic fibroblast growth factor in Balb-c 3T3 fibroblasts

1. We have investigated the ionic events elicited in Balb-c 3T3 fibroblasts by basic fibroblast growth factor (bFGF), a peptide that binds to membrane receptors with tyrosine kinase activity and has a mitogenic action on many cell types. The peptide (0.2-100 ng ml-1) caused the appearance of an inward current, as observed in whole-cell patch-clamp experiments at a holding potential of -50 mV, that could last for tens of minutes and had a peak density of 4.6 +/- 2.6 pA pF-1. The reversal potential was 18.8 +/- 16.7 mV. 2. The current was reversibly abolished by removal of bFGF from the external bath. Inhibition of low-affinity FGF receptors had no effect on the activation of the inward current; it was completely abolished when cells were pre-incubated with tyrphostin or 5'-methylthioadenosine (MTA), two inhibitors of the tyrosine kinase activity of the high-affinity FGF receptors. The inward current was not activated by the emptying of internal calcium stores, as tested with 200 nM thapsigargin. 3. Values of peak current density comparable to control ones were obtained when either all Na+ ions or all Ca2+ ions were removed from the external solution; when both ions were completely removed, no inward current could be observed. The inward current was not affected by 2 microM nifedipine, and was reversibly blocked by the imidazole derivative SK&F 96365-A. 4. Measurements of free intracellular calcium concentration ([Ca2+]i) with the dye fura-2 showed that bFGF elicited sustained increases in [Ca2+]i that were completely dependent on external calcium and on the presence of the agonist and could last more than 1 h. 5. Single channel currents (conductance 7.9 pS) in response to bFGF stimulation could be recorded in the cell-attached configuration with 100 mM CaCl2 in the pipette. When the resting potential was brought near to 0 mV by external perfusion in a high-K+ solution, Vrev was about 0 mV. 6. We conclude that in Balb-c 3T3 cells bFGF induces an inward current that is carried at least partially by Ca2+ ions; this current in turn causes a long-lasting increase in intracellular Ca2+ concentration. The amplitude and time course of these bFGF-activated ionic events are compatible with their involvement in the control of cell proliferation.

Intracellular ionic variations in the apoptotic death of L cells by inhibitors of cell cycle progression

Treatment with VP-16 (1-50 microM) or excess thymidine (5 mM) caused a block of L cells at different steps in their progression through the replicative cycle. The arrest was followed by an asynchronous process of cell death that conformed to criteria for apoptosis. Careful monitoring of this process in the whole cell population by flow cytometry showed a virtual absence of necrosis, an increase in side light scattering, followed by the occurrence of a population with subdiploid DNA fluorescence as well as reduced forward and side light scattering. The development of apoptosis required sufficient time and adequate ion gradients in the cells. By the combined use of flow cytometry and fluorescence microscopy data were obtained suggesting that (i) intracellular free Ca2+ and pH and/or their drug-induced alterations had to be adequately controlled for the apoptotic process to evolve; (ii) mitochondria were compromised earlier than the plasma membrane or lysosomes; and (iii) K+ extrusion possibly played a role in the final loss of cell volume. Interfering with the control of ion gradients and/or their changes in drug-treated cells resulted in cell death by necrosis.

Cell death induced in L-cells by treatment with thymidine: staging of the process and relationship to apoptosis

The purpose of this study was to characterize the stages in the development of thymidine-induced cell death. L-cells were characterized by both morphologic and quantitative techniques and evaluated at 24, 48, and 72 h of treatment. Cells first enlarged (stage I); about 50% of these enlarged cells then decreased in size with blebbing and compacting (stage II). This residual cell body transformed into a smooth eosinophilic hyaline body (stage III) by 72 h, many of which could be identified within the vacuolar system of viable cells. These changes were reflected in morphologic counts and Coulter sizing. Cell death (loss of labeled DNA) began in stage II and was most prominent in stage III. No cleavage of DNA into oligonucleosomal fragments was detected by agarose gel electrophoresis at any stage. The similarity of these changes to the complete spectrum of apoptosis in vivo is discussed.

Potassium and calcium currents activated by foetal calf serum in Balb-c 3T3 fibroblasts

In quiescent Balb-c mouse 3T3 fibroblasts, the application of whole or dialyzed 10% foetal calf serum elicits a biphasic electrical response, consisting of a transient outward current, flowing through Ca(2+)-activated K+ channels, followed by an inward one, lasting up to 15 min. On the basis of experiments with ion substitutions and blockers, the inward current can be attributed to the opening of cationic channels permeable to Na+ and Ca2+ ions. This current could mediate the calcium influx involved in the sustained elevation of [Ca2+]i that has been observed in many preparations in response to mitogen stimulation and that is involved in triggering cell proliferation.

Two currents activated by epidermal growth factor in EGFR-T17 fibroblasts

Application of 10 nM Epidermal Growth Factor (EGF) to single EGFR-T17 fibroblasts induced a marked hyperpolarization that could last for tens of minutes; in many cases the first transient was followed by a series of oscillations of the membrane potential. The outward current responsible for the hyperpolarizing response could be recorded simultaneously to an increase in the intracellular calcium concentration, as measured with the fluorescent indicator fura-2. The conductance was nearly linear in the voltage range from -100 to +50 mV. While the EGF-induced current had many characteristics of a K+ current and was strongly reduced by 50 nM charybdotoxin (ChTx), its reversal potential was apparently more negative than the potassium equilibrium potential (VK). The application of 2 microM ouabain prior to EGF stimulation produced responses that were similar to those obtained without ouabain; however, under these conditions the EGF-induced current showed a reversal potential of -96.6 +/- 3.2 mV, very close to VK. Simultaneous application of both 2 microM ouabain and 50 nM ChTx completely abolished the response. It can be concluded that the response to EGF stimulation in EGFR-T17 cells consists of two components: the first is a current carried through Ca(2+)-activated K+ channels; the second is due to the acceleration of the operation of the Na+/K(+)-ATPase.

Regulation of cell turnover in the livers of tumour-bearing rats: occurrence of apoptosis

Growth of a highly-deviated ascites hepatoma (Yoshida AH-130) in rats caused initial hyperplastic enlargement of the liver, followed by progressive reduction to a size lower than that seen in controls. The time-course of this biphasic change in liver weight roughly corresponded to the exponential and stationary phases of tumour growth. Histologically, scattered small foci of perilobular necrosis were observed during the hyperplastic phase and these were consistently associated with a moderate elevation of glutamate-pyruvate transaminase (GPT) activity in the blood plasma. By contrast, signs of necrosis were absent and plasma GTP levels had returned to normal during the phase of hepatic involution, which was characterized by enhanced apoptosis, a type of single-cell death known to be involved in the regulation of tissue size under both normal and pathological conditions. Biochemically, alterations in liver protein mass resulted from changed rates of tissue protein degradation. The apoptotic bodies could either be lost from the liver via blood, lymph and bile, or phagocytosed and degraded by adjacent cells. Disposal of the apoptotic bodies is likely to account, at least in part, for the enhanced rates of liver protein turnover that characterize hepatic involution.

Effect of two aliphatic aldehydes, methylglyoxal and 4-hydroxypentenal, on the growth of Yoshida ascites hepatoma AH-130

The influence of a ketoaldehyde, methylglyoxal (MG), and a hydroxyalkenal, 4-hydroxypentenal (HPE), on the growth of a highly-deviated tumour has been investigated. MG and HPE, administered intraperitoneally, strongly depressed in rats the proliferative activity of the Yoshida ascites hepatoma AH-130, reducing its mitotic and labelling indices as well as the proportion of cycling cells (growth fraction). Monitoring the effects on the cell cycle by the labelled mitoses method showed that the percentage of labelled mitoses was markedly lowered after either aldehyde, which is indicative for a blocking effect in the S phase. In addition, the mean cell cycle time was slightly prolonged by MG, probably due to accumulation of cells in G1, whereas HPE delayed the first mitotic peak and increased the mean DNA synthetic period without modifying the overall cycle time. The effects of HPE on the cell cycle were prevented by pretreatment with polyamines. Repeated doses of MG significantly increased the fraction of tumour-bearing rats surviving at 90 days ('indefinite' survivors) as well as the survival time of those which succumbed, implying that the carcinostatic effect of MG persisted over several cell cycles. By contrast, HPE did not significantly modify the survival of AH-130-bearing rats, suggesting that its influence on tumour growth was rapidly reversible.

Potassium and calcium currents and action potentials in mouse Balb/c 3T3 fibroblasts

The electrical properties of Balb/c 3T3 mouse fibroblasts were studied with the whole-cell patch clamp technique. In current clamp mode a resting potential of -75.5 +/- 2.1 mV was recorded. In voltage clamp mode an inward current was also observed at potentials negative to Vm. This current crossed the 0-current axis at a voltage near Vm, and rectified at more positive potentials; the degree of rectification was dependent on [K+]o. At potentials positive to -30 mV a transient inward current was observed, showing a peak amplitude of -193 +/- 36 pA at +10 mV; the current amplitude was dependent on voltage and [Ca2+]o, it was strongly increased by 20 mM BaCl2 and abolished by 2 microM verapamil and 1 microM nifedipine. These cells, in response to depolarizing stimuli, develop slow action potentials, probably supported by the Ca2+ current.

Purification and properties of cathepsin D from rat Yoshida ascites hepatoma AH-130

Cathepsin D was affinity-purified on pepstatin-Sepharose from control rat liver, from Yoshida ascites hepatoma (AH-130) cells, and from the liver of AH-130 tumour-bearing rats. Apparent molecular mass and immunological reactivity, as determined by SDS-PAGE and immunoblotting, were identical for the three enzyme preparations. The active enzyme concentrations were determined by active-site titration. Catalytic parameters were measured for the three enzymes using two synthetic chromogenic peptides as substrates, and inhibition constants were determined for the proteinases with a number of naturally-occurring as well as synthetic inhibitors. All three enzymes were clearly distinguished from cathepsin E, since none of them was affected by the protein inhibitor from Ascaris lumbricoides. The cathepsin D isolated from AH-130 cells was indistinguishable in its kinetic properties from rat liver cathepsin D, except in its susceptibility to inhibition by isovaleryl-pepstatin. On isoelectrofocusing, the isoenzyme pattern of the tumour enzyme was shifted somewhat towards more basic pI values by comparison with rat liver cathepsin D. These findings are considered with respect to the possibility of an alteration in the S4 subsite of the enzyme active site cleft.

Regulation of protein turnover versus growth state. Studies on the mechanism(s) of initiation of acidic vacuolar proteolysis in cells of stationary ascites hepatoma

1. After transplantation, the rat AH-130 Yoshida ascites hepatoma enters a phase of exponential (log) growth, followed by a quasi-stationary (sta) state. Combining measurements made in vivo and in vitro, cessation of protein accumulation (growth) in sta phase has previously been shown to result from convergent reduction of protein synthesis and enhancement of protein breakdown [Tessitore, Bonelli, Cecchini, Amenta & Baccino (1987) Arch. Biochem. Biophys. 255, 372-384]. 2. One day after labelling in the animal with [3H]leucine, AH-130 cells were processed for short-term assays in vitro to measure rates of endogenous protein breakdown. 3. Exposure of AH-130 cells to inhibitors interfering with different steps of the acidic vacuolar pathway (AVP) showed that: (i) in log tumour cells the AVP was extensively suppressed; (ii) in sta tumour cells virtually all of the proteolytic acceleration was accounted for by activation of the AVP. 4. Treating log tumour cells with glucagon, cyclic AMP, or nutritional deprivation failed to elevate substantially the proteolytic rates. Nor could the elevation in proteolysis be explained by changes in free amino acids, which were more concentrated in the ascitic fluid of sta tumours. 5. The enhanced proteolysis in sta tumour cells was not associated with any increase in the intracellular activity levels of lysosomal cathepsins B, D, H, and L. 6. The above growth-related modulation of protein breakdown in AH-130 cells was probably a reflection of the tumour growth state rather than the direct effect of environmental stimuli.

Optics for the x-ray imaging concentrators aboard the x-ray astronomy satellite SAX

The scientific instrumentation onboard the Italian satellite for x-ray astronomy (SAX) foresees x-ray imaging concentrators operating in the 0.1-10-keV energy range with a spatial resolution of 1 min of arc. The optics is composed of thirty confocal-nested very thin double-cone mirrors. To achieve good optical quality and to allow the construction of several concentrators at an acceptable cost, a replica technique by electroforming the mirrors from masters is used. This paper presents the results obtained from a set of electroformed mirrors mounted on a concentrator prototype.

Regulation of protein turnover versus growth state: ascites hepatoma as a model for studies both in the animal and in vitro

Cell protein turnover states as related to growth phase have been analyzed in a rat ascites hepatoma (Yoshida AH-130), which after transplantation entered a period of exponential growth, followed by a quasi-stationary state. Evaluation of AH-130 cell protein turnover in the animal (slow-turnover protein pool) was combined with rapid assays of proteolytic rates of cells transferred in vitro. Protein accumulation in the exponential phase reflected the balance between sustained synthetic rates and relatively low degradative rates. Cessation of growth resulted from convergent reduction of synthesis (from 3.10 to 1.49%/h) and enhancement of protein breakdown (from 0.61 to 1.43%/h). Endogenous proteolytic rates in vitro were very close to the above degradation rates. As shown by incubation with ammonia or other lysosomal inhibitors, the acidic vacuolar pathway for protein degradation, while totally suppressed in exponential tumor cells, was activated in cells from stationary tumors to such an extent that it fully accounted for the enhanced proteolysis. In contrast, energy metabolism inhibitors were effective on cells in either growth state, the residual ongoing proteolysis being similar in both cells. The possible contribution of cell death to activation of the acidic vacuolar proteolysis in stationary tumors is discussed.

Italian multicenter study of reversible cerebral ischemic attacks. Part 5. Risk factors and cerebral atherosclerosis

As part of a prospective study, the influence of several premorbid and environmental factors on the presence, extent and severity of cerebral vessel atherosclerosis was studied in 462 patients with clinical diagnosis of RIA who underwent cerebral angiography. The extent and severity of atherosclerosis of the cerebral vessels was quantified using extracranial and intracranial cerebrovascular scores (ECS, ICS) based on the number and severity of the lesions in 11 extracranial and 21 intracranial arterial segments. Results of univariate and multivariate analyses indicate that the presence of atherosclerotic changes of cerebral vessels, as shown by angiography, was strongly related with age in both sexes. The lesions were more frequent in males, in particular under age 55. Elevated cholesterol was associated with a higher incidence of atherosclerotic lesions. Smoking was associated with a higher incidence of extracranial lesions. Age, smoking and history of hypertension were the best predictors of the extent and severity of cerebral vessel atherosclerosis.

Early development of protein metabolic perturbations in the liver and skeletal muscle of tumour-bearing rats. A model system for cancer cachexia

In rats into which a fast-growing ascites hepatoma (Yoshida AH-130) had been transplanted, tumour growth elicited a marked loss of body weight until the animal's death in about 2 weeks. Overall tissue protein metabolism was simultaneously studied in vivo in the gastrocnemius muscle and liver after labelling with [14C]bicarbonate. Early and progressive atrophy developed in the gastrocnemius muscle, the underlying metabolic imbalance being expressed by an elevation in the apparent protein-degradation rate, with no changes in the apparent synthesis rate. A transient hyperplastic response preceded waste in the liver, both states being associated with alterations in protein-degradation rate: an initial decrease during liver growth, then an acceleration as liver regressed. Protein-synthesis rates, virtually unchanged during liver growth, were elevated in the subsequent phase, although not sufficient to balance the enhanced breakdown. Thus, in the tumour host tissues examined, altered states of protein turnover appeared to result mostly from changes in rates of protein breakdown. In sharp contrast with the negative protein balance in the host, the ascites hepatoma cells had the ability to grow or at least, in advanced stages, to maintain a stationary state.

Aliphatic aldehydes inhibit the proliferative response of human peripheral blood lymphocytes to phytohemagglutinin and alloantigens

The effect of methyl glyoxal (MG) and various 4-hydroxyalkenals on the response of human peripheral blood lymphocytes (PBL) to phytohemagglutinin (PHA) or allogeneic cells has been investigated. Pretreatment of PBL with aldehydes significantly reduced the percentage of blast-transformed cells and [3H]thymidine incorporation into DNA in both PHA- and alloantigen-stimulated cultures, hydroxyalkenals being more effective than MG. Further experiments showed that these aldehydes also affected the proliferation of pre-activated lymphocytes. The percentage of blasts as well as [3H]thymidine incorporation into DNA were significantly decreased when the aldehydes were added until 72 h after application of the mitogenic stimulus.

Cellular distribution of lysosomal hydrolase activities in the regenerating rat liver

Cathepsins B and D, beta-galactosidase, and acid phosphatase activities were found to be decreased in the regenerating rat liver, the reduction being maximal around the peak of hepatocyte mitoses (30 h). To investigate whether these changes could be heterogeneously distributed among hepatic cells, total cell populations from control or two-thirds hepatectomized rat livers were dissociated by the collagenase perfusion technique and analysed by different procedures. Isopycnic centrifugation in a Metrizamide gradient satisfactorily resolved hepatocytes and non-parenchymal cells from control animals but was not adequate when applied to 30-h regenerating liver cells. Colchicine treatment of the hepatectomized animals, resulted in substantial accumulation of phase M-hepatocytes. Subpopulations considerably enriched in fast-sedimenting phase M-cells were obtained by sedimentation at 1 g of the total liver cell population, and subsequently analysed by isopycnic equilibration. Phase M-hepatocytes were shown to have markedly reduced levels of beta-galactosidase, acid phosphatase, and cathepsin B activities in comparison, not only with control hepatocytes, but also with those parenchymal cells which were not metaphase-arrested in the same regenerating livers. Therefore, in partially-hepatectomized rats, hepatocytes progressing up to metaphase in the first mitotic cycle exhibited a selective depletion of lysosomal enzyme activities. The mechanism(s) underlying this change remain(s) presently unknown.

Comparative studies on protein turnover regulations in tumor cells and host tissues: development and analysis of an experimental model

The protein mass of cells and tissues is determined by the relative rates of protein synthesis (PS) and degradation (PD). A convergent modulation of both PS and PD is operated by many cell types to regulate protein accumulation and thus growth. Transformed and neoplastic cells may show markedly defective PD regulations. Yet even highly-deviated cells such as those of the transplantable Yoshida ascites hepatoma AH-130 cease growth when attaining a conspicuous population size, by operating a combined reduction of PS and acceleration of PD. As in normal cells, PD acceleration is effected through an activation of the acidic-vacuolar (lysosomal) mechanism. AH-130 tumor-bearing rats develop a markedly negative nitrogen balance early after transplantation. Tumor growth involves pronounced perturbations in host body and tissue protein metabolism. Apparently, these changes occur mostly at the level of PD rather than PS, at least in liver and skeletal muscle (gastrocnemius). These observations indicate that either tumor and host cells sense different signals for PD regulations or their thresholds for the same signals are poised differently. This model seems most suitable for further studies to elucidate which signals and mechanisms are involved in these protein metabolic perturbations and possibly, to develop the rationale for adequate corrective strategies.

Changes in rat liver immunoreactive cathepsin D after cycloheximide

A rocket immunoelectrophoretic procedure has been developed for the assay of cathepsin D (EC 3.4.23.5) immunoreactive protein, in a 10-100 ng range, directly on crude soluble liver homogenate extracts. By this method, the drop in activity of rat liver cathepsin D effected by repeated doses of cycloheximide, a protein synthesis inhibitor, reflects a parallel change in total enzyme protein content, the specific activity being stable in the course of the treatment. These observations are compatible with the hypothesis that ongoing enzyme degradation, coupled with impaired synthesis, accounts for such a decline of cathepsin D.

Effect of methylglyoxal on tumour microtubular protein

Methylglyoxal inhibits cell division, exerting an antiproliferative action on tumour cells. Supernatants from ascites hepatoma cell homogenate, previously incubated with the aldehyde, showed a decrease in colchicine binding activity dependent on methylglyoxal concentration. In contrast, in vivo treatment of tumour-bearing rats apparently did not cause a significant impairment of microtubular protein, suggesting that the aldehyde interaction with microtubules cannot be considered responsible for its carcinostatic action.