Telomere-based neo-Darwinian selection of yeast clonal subpopulations

In Saccharomyces cerevisiae, imbalance of the genes coding for the heterochromatin components Sir3p and histone H4 (namely, overdosage of SIR3 and lack of one of the two genes coding for H4) causes modifications in telomere length and telomere sequence organization, favoring the insertion of Y' elements into a stably shortened (C1-3A)n repeat tract. We report here that the newly inserted Y' elements are unstable and are lost with high frequency, generating clonal subpopulations with short telomeres, as revealed by the analysis of a specific telomere (LIII) and of the overall population of telomeres. Moreover, the growth rates of the subpopulations with and without Y' elements on LIII are different, the Y'-less individuals reproducing 20% more slowly than individuals bearing Y' elements. When grown together with Y'-bearing individuals, the subpopulations with the normal LIII telomere (which are viable and genetically stable if grown alone) are rapidly competed out. Hence, genetic imbalance for the structural components of heterochromatin results in a complex and rapidly changing mixture of subpopulations in such cultures. Thus, in situations where subpopulations are allowed to compete, heterochromatin-based differential growth rates result in neo-Darwinian clonal selection.

Enhanced liver blood concentrations of adenine arabinoside accomplished by lactosaminated poly-L-lysine coupling: implications for regional chemotherapy of hepatic micrometastases

Conjugates of antiviral and antiblastic nucleoside analogs (NAs) with galactosyl-terminating peptides selectively enter hepatocytes after binding of the carrier galactose residues to the asialoglycoprotein receptor. Since NAs, when set free from the carrier within hepatocytes, partly exit from these cells into the bloodstream, we considered the possibility that administration of galactosyl-terminating conjugates of NAs could result in plasma concentrations of these drugs that would be higher in liver sinusoids than in capillaries of other organs. In the present study we demonstrated the validity of this hypothesis. We injected rats with a conjugate of adenine arabinoside (ara-A) with lactosaminated poly-L-lysine and found that the plasma concentrations of ara-A were >2-fold higher in blood of liver than in systemic circulation. Liver blood was collected from the inferior vena cava after closing below and above the outflows of the hepatic veins. The present result suggests that conjugation with galactosyl-terminating peptides might be a way to selectively increase the concentrations of NAs not only in hepatocytes, which have the asialoglycoprotein receptor, but also in cells infiltrating the liver, such as neoplastic cells of micrometastases nourished by hepatic sinusoids.

The asialoglycoprotein receptor in human hepatocellular carcinomas: its expression on proliferating cells

The expression of the asialoglycoprotein receptor (ASGP-R) on human hepatocellular carcinoma (HCC) cells might be exploited to reduce the extrahepatic toxicity of DNA synthesis inhibitors by their conjugation with galactosyl-terminating peptides. In the present study we first assessed the frequency of ASGP-R expression in 60 HCCs. Secondly, we investigated whether the receptor was maintained on the plasma membranes of DNA synthesizing cancer cells. Needle biopsies of HCC were evaluated. Diagnosis and grading of HCC were performed on routine haematoxylin and eosin-stained sections according to Edmondson and Steiner (1953). Thirty-five tumours were grade I and II and were classified as well differentiated, while 25 tumours were grade III and IV and were classified as poorly differentiated. Sections from formalin-fixed, paraffin-embedded samples were incubated, after antigen retrieval, with an anti-ASGP-R monoclonal antibody revealed by secondary biotinylated antibody and streptavidin-biotin-peroxidase-diaminobenzidine reaction. A clear immunolabelling of plasma membranes of HCC cells was observed in 28 out of 35 (80%) well differentiated (grade I and II) and in five out of 25 (20%) poorly differentiated (grade III and IV) HCCs. The presence of the ASGP-R on the surface of DNA synthesizing cancer cells was also investigated after in vitro bromodeoxyuridine (BrdU) labelling of HCC samples by immunohistochemical visualization of both the ASGP-R and incorporated BrdU on the same section. The results obtained clearly demonstrated that DNA synthesizing cancer cells expressed the ASGP-R on their surface. The presence of ASGP-R on cell plasma membrane in the majority of differentiated HCCs and its maintenance on proliferating cells encourages studies in order to restrict the action of the inhibitors of DNA synthesis of HCC cells by their conjugation with galactosyl-terminating carriers internalized through this receptor.

The asialoglycoprotein receptor in human hepatocellular carcinomas: its expression on proliferating cells

The expression of the asialoglycoprotein receptor (ASGP-R) on human hepatocellular carcinoma (HCC) cells might be exploited to reduce the extrahepatic toxicity of DNA synthesis inhibitors by their conjugation with galactosyl-terminating peptides. In the present study we first assessed the frequency of ASGP-R expression in 60 HCCs. Secondly, we investigated whether the receptor was maintained on the plasma membranes of DNA synthesizing cancer cells. Needle biopsies of HCC were evaluated. Diagnosis and grading of HCC were performed on routine haematoxylin and eosin-stained sections according to Edmondson and Steiner (1953). Thirty-five tumours were grade I and II and were classified as well differentiated, while 25 tumours were grade III and IV and were classified as poorly differentiated. Sections from formalin-fixed, paraffin-embedded samples were incubated, after antigen retrieval, with an anti-ASGP-R monoclonal antibody revealed by secondary biotinylated antibody and streptavidin-biotin-peroxidase-diaminobenzidine reaction. A clear immunolabelling of plasma membranes of HCC cells was observed in 28 out of 35 (80%) well differentiated (grade I and II) and in five out of 25 (20%) poorly differentiated (grade III and IV) HCCs. The presence of the ASGP-R on the surface of DNA synthesizing cancer cells was also investigated after in vitro bromodeoxyuridine (BrdU) labelling of HCC samples by immunohistochemical visualization of both the ASGP-R and incorporated BrdU on the same section. The results obtained clearly demonstrated that DNA synthesizing cancer cells expressed the ASGP-R on their surface. The presence of ASGP-R on cell plasma membrane in the majority of differentiated HCCs and its maintenance on proliferating cells encourages studies in order to restrict the action of the inhibitors of DNA synthesis of HCC cells by their conjugation with galactosyl-terminating carriers internalized through this receptor.

Imbalance in dosage of the genes for the heterochromatin components Sir3p and histone H4 results in changes in the length and sequence organization of yeast telomeres

Telomeric heterochromatin plays an essential role in telomere function, including the regulation of telomere length. We observe that in Saccharomyces cerevisiae an imbalance in the dosage of genes for two protein components of heterochromatin (namely Sir3p and histone H4) causes modifications in telomere length and telomere sequence organization. The effects of Sir3p/H4 imbalance were analyzed in yeast strains in which the wild-type SIR3 gene (normally a single-copy gene) was either absent or present in 20-30 copies, and both histone H4 genes (HHF1 and HHF2) were present or HHF1 was deleted, thus covering a wide range of viable gene-dosage combinations. Modifications of telomeres and of subtelomeric regions were identified by analyzing both the overall telomere population and by focusing on two single telomeric regions: the left telomere of chromosome III (LIII) and the right telomere of chromosome XI (RXI). The modifications induced by alteration of the Sir3p/H4 ratio consist of a reduction in the length and an increase in the instability of the terminal block of (C(1-3)A)n repeats and in susceptibility to insertion of Y' elements into this repeat element. Restoration of the wild-type gene ratio (by removal of the extra copies of SIR3 or by complementation with the missing second copy of HHF) restored the original telomere organization, both with respect to the length of the (C(1-3)A)n repeat stretch and the absence of Y' elements. This behavior shows that the stability of the wild-type sequence organization requires maintenance of the normal structure of telomeric heterochromatin.

Dietary restriction modulates synaptic structural dynamics in the aging hippocampus

A computer-assisted morphometric study has been carried out on the synaptic ultrastructural features in the hippocampus of 14-month old (DR14) and 27-month old (DR27) dietary restricted (-50% lipids and -35% carbohydrates) rats. Age-matched controls were maintained on an ad libitum (AL) feeding schedule. Synaptic numeric density (Nv), surface density (Sv) and average area (S) were the parameters measured. In old AL vs. adult AL animals, Nv decreased to a not significant extent, while S increased and Sv decreased significantly. In DR14 rats vs. AL littermates Nv increased significantly, but S and Sv were unchanged. DR27 rats vs. age-matched AL controls showed a significant increase of Nv and Sv while S was significantly decreased. Comparing DR14 vs. DR27, no significant difference due to age was documented. Both in DR14 and in DR27 groups the percent distribution of S showed a marked increase of smaller contact zones. Despite reporting on discrete aspects of synaptic ultrastructure, Nv and S are supported to be in an inverse relationship which aims at maintaining Sv constant. Thus, these three ultrastructural parameters when taken together per experimental group, appear to provide information on synaptic morphological rearrangements. In this context, the percent increase of smaller synapses in DR animals is consistent with the idea of a marked remodelling process. Considering previous data from the same groups of rats reporting significant changes in neuronal membrane lipid composition and fluidity, we interpret our findings to account for a positive modulation of dietary restriction on the synaptic structural dynamics.

In vivo amifostine (WR-2721) prevents chemotherapy-induced apoptosis of peripheral blood lymphocytes from cancer patients

Aim of this work was to evaluate whether in vivo amifostine (WR-2721, ethanethiol, 2-[(3-aminopropyl)amino]-,dihydrogen phosphate (ester), Ethyol) pretreatment was able to prevent the apoptosis of peripheral blood lymphocytes (PBLs) induced by cytotoxic drugs. The study included 19 patients with advanced gynaecological cancers who received neoadjuvant polychemotherapy consisting of three cycles of cysplatin, adriamycin, and cyclophosphamide. Five patients received randomly amifostine pretreatment (910 mg/m2). PBLs apoptosis was measured through flow-cytometry using two different methods: a) DNA fragmentation of PBLs cultured in vitro for one hour; b) measurement of early apoptotic cells through Apostain uptake by fresh PBLs. The percentage of apoptotic PBLs was increased in all patients 24 hr after the first chemotherapy cycle (27.1 +/- 15.6 vs 6.3 +/- 6.2, p<.0001). A similar increase was observed in the following chemotherapy cycle. Amifostine pretreatment prevented the apoptosis of PBLs induced by chemotherapeutic drugs. Amifostine also prevented the reduction of lymphocyte number determined by chemotherapy. The results demonstrate that amifostine protects peripheral lymphocytes from the apoptotic damage induced by chemotherapy. This effect may explain the mechanism by which amifostine prevents the chemotherapy-associated reduction of leukocyte number.

Inhibition of [3H]thymidine incorporation into DNA of rat regenerating liver by 2',2'-difluorodeoxycytidine coupled to lactosaminated poly-L-lysine

The expression of asialoglycoprotein receptor (ASGP-R) on human hepatocarcinoma cells might be exploited to reduce the extrahepatic toxicity of DNA synthesis inhibitors by their conjugation with galactosyl- terminating peptides. We conjugated 2',2'-difluorodeoxycytidine (dFdC), an inhibitor of DNA synthesis active on solid tumors, with lactosaminated poly-L-lysine (L-poly(LYS)). In experiments in vitro, L-poly(LYS)-dFdC inhibited proliferation of Hep G2 cells, a human hepatocarcinoma cell line which maintains the ASGP-R. Inhibition was rescued by asialofetuin. To study the pharmacological action of the conjugate in vivo, we used rats 18-24 hr after 2/3 hepatectomy and observed that regenerating hepatocytes expressed ASGP-R on their surface and internalized L-poly(LYS)-dFdC. Conjugate uptake by bone marrow, spleen, and intestine was negligible. We also found that L-poly(LYS)-dFdC inhibited [3H]thymidine incorporation into DNA of regenerating liver. These results indicated that hepatectomized rats were a suitable animal model to study the pharmacological action, on DNA-synthesizing hepatocytes, of conjugates binding to ASGP-R and carrying inhibitors of DNA synthesis. L-poly(LYS)-dFdC also inhibited [3H]thymidine incorporation in bone marrow, spleen, and intestine. Evidence was obtained that inhibition of DNA synthesis in extrahepatic tissues was a consequence of drug release from hepatocytes into blood-stream after the bond with the carrier has been broken down within liver cells. Possible ways of reducing the exit of dFdC from liver cells, thereby obtaining an inhibition of DNA synthesis restricted to dividing hepatocytes, were discussed.

Using obese-specific charts of height and height velocity for assessment of growth in obese children and adolescents during weight excess reduction

OBJECTIVE

The influence of weight excess reduction on height and height velocity of obese subjects should be evaluated on the basis of appropriate standards, since the pattern of growth of obese subjects is different from that of normal weight subjects.

DESIGN, SUBJECTS AND MEASUREMENTS

Height, weight and triceps skinfold thickness were recorded from 17987 school subjects (9256 males and 8731 females), 3-18 y of age, from three provinces of central Italy, and a growth reference curve of height was constructed. Using BMI (as computed using the tables of Rolland-Cachera et al) and triceps skinfold thickness, normal-weight subjects (NWS) and obese subjects (OS) were identified and specific reference curves (mean+/-s.d. every sixth month of age) were developed for both groups. Centiles of height were also calculated for OS. Various (2-4) measurements of height in school subjects were performed and a graph of height velocity (HV) was constructed in NWS and in OS using the JPPS method. The yearly mean +/-s.d. of HV was also calculated, based on square root transformed data (in order to realise a Gaussian distribution), deriving from successive measurements in total subjects, in NWS and in OS. The z-scores of height and of the square root of HV were calculated in 217 obese subjects (125 males and 92 females) before and during a weight excess reduction programme (WERP). Obese subjects in WERP who showed a reduction of z-score of BMI were considered as 'responsive'; those who either maintained or showed an increase of z-score of BMI were considered as 'non-responsive'. Obese subjects in WERP were followed for 1-4 y, giving the following results: 0-1 y, 142 responsives and 75 non-responsives; 0-2 y, 76 responsives and 33 non-responsives; 0-3 y, 35 responsives and 30 non-responsives; 0-4 y, 24 responsives and 18 non-responsives.

RESULTS

Compared to NWS, OS showed a significantly greater HV in 4-9y males and in 4-8y females, but in older children the pubertal spurt was reduced and more precocious. As a result, the height of OS, which was greater in 3-13 year-old males and in 3-11.5 year-old females, subsequently showed a reduction, as compared to that of NWS, in 16-18 year-old males and in 13-18 year-old females. In both responsive and non-responsive groups of obese subjects in WERP, the z-scores of height showed a reduction during WERP when evaluated using the reference curve of the total school population. In contrast, when their growth was evaluated according to the obese-specific reference curve, no significant variation was observed comparing both z-scores before and during the WERP.

CONCLUSIONS

More appropriate information on the growth of obese subjects may be obtained when evaluating the height and HV according to obese-specific reference standards from the same population of origin. Adopting this modality, no significant variation of height resulted during WERP in obese children.

Fasting serum leptin levels in the analysis of body mass index cut-off values: are they useful for overweight screening in children and adolescents? A school population-based survey in three provinces of central Italy

OBJECTIVE

Body mass index (BMI) was determined in a population of school students from three provinces of central Italy. Fasting serum leptin concentrations were assayed in a large number of subjects from the same area, to determine their distribution as plotted against the standard deviation score (z-score) of BMI.

DESIGN, SUBJECTS AND MEASUREMENTS

Height and weight were recorded from 31170 subjects (16175 male and 14995 female), aged 3-18 y, to construct BMI charts of children and adolescents from central Italy. Percentiles and z-score were calculated using the LMS method of Cole. Serum leptin concentrations were assayed in 1929 subjects (996 male and 933 female) after overnight fasting.

RESULTS

BMI percentiles of central Italy were higher than those from standards of other European and USA populations. When plotted against the z-score of BMI, serum leptin values were distributed according to an exponential curve, showing a steep pattern and a wide distribution, as BMI values increased. The hypothesis of the existence of two subgroups, based on a different relation between leptin and BMI, was verified and a separation point between the two subgroups was identified using cluster analysis, discriminant analysis and a novel method developed by our group, hereafter referred to as 'regression clustering'. This method allows identification of the value of the independent variable (z-score of BMI) which can be taken as a separation point. This analysis provided the best results and indicated the following separation points: central Italy standard, z-score = 0.72 (76.4th percentile) for males and z-score = 0.69 (75.5th percentile) for females; French standard (the one suggested for a European population by the European Childhood Obesity Group, ECOG), z-score = 1.46 (92.8th percentile) for males and z-score = 1.96 (97.5th percentile) for females. Similar but variable results were obtained when the same analysis was performed on serum leptin concentration, subdivided according to pubertal development (stage I, stage II-III, stage IV-V).

CONCLUSIONS

Children and adolescents from central Italy had greater BMI percentiles when compared to other European populations. Fasting serum leptin concentrations showed a distribution pattern related to z-score, thus allowing to identification of two different subgroups. The z-scores of BMI, identified as separation points, indicated a trend to leptin production by adipocytes that could be taken as indicators of significant increases of fat mass. This study proposes criteria and a statistical approach that could be useful in the identification of BMI cut-off values when screening children and adolescents for overweight.

Effect of zinc or zinc plus arginine supplementation on antibody titre and lymphocyte subsets after influenza vaccination in elderly subjects: a randomized controlled trial

OBJECTIVE

to evaluate whether oral supplementation with zinc or zinc/arginine increases the antibody response to influenza vaccine or modulates the lymphocyte phenotype in elderly subjects.

DESIGN

a randomized controlled trial with two supplemented groups and one control group.

SETTING

a community nursing home.

PARTICIPANTS

384 subjects aged 64-100 (mean age 82 years) examined in three separate studies.

INTERVENTION

oral supplementation with zinc (400 mg/day) or zinc plus arginine (4 g/day) for 60 days starting 15 days before influenza vaccination. The control groups received vaccine only.

MEASUREMENTS

haematological and nutritional indices, antibody titre against influenza viral antigens, lymphocyte phenotype.

RESULTS

supplementation with zinc or zinc plus arginine increased zinc plasma concentrations restoring the age-related impairment in zinc concentrations to values found in younger people. The antibody titre against influenza viral antigens was not increased in zinc or zinc/arginine supplemented groups in comparison with subjects receiving vaccine alone. The number of CD3, CD4 or CD8 lymphocytes was not affected by zinc or zinc/arginine supplementation.

CONCLUSION

prolonged supplementation with zinc or zinc/arginine restores zinc plasma concentrations but is ineffective in inducing or ameliorating the antibody response after influenza vaccination in elderly subjects.

Attitude of potential users in Sicily towards preimplantation genetic diagnosis for beta-thalassaemia and aneuploidies

This study aims to report the willingness of different populations of high-risk couples to undergo preimplantation genetic diagnosis (PGD) for beta-thalassaemia as an alternative to prenatal genetic diagnosis (PND), and the willingness of infertile couples to undergo PGD for aneuploidies. An information sheet and questionnaire presenting PGD and PND procedures were distributed to four population types: 54 high-risk couples for beta-thalassaemia coming for their first PND (population A); 51 similar couples coming for their second or further PND without previous experience of therapeutic abortion (population B-na); 50 similar couples coming for their second or further PND with previous experience of therapeutic abortion for beta-thalassaemia-affected fetus (population B-ab); and 74 infertile couples undergoing routine in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) (population C). Favourable first impressions towards PGD compared with PND were observed in all four populations in the following proportions: 79.6% population A; 76.5% population B-na; 92.0% population B-ab; and 96.0% population C. Willingness to undergo PGD for beta-thalassaemia was as follows: 44.4% population A; 47.1% population B-na; and 72.0% population B-ab. We conclude that previous experience of PND for beta-thalassaemia is a crucial point in the willingness to accept the PGD procedure, and that couples belonging to population B-ab are the most suitable to undergo PGD for beta-thalassaemia. Some 96.0% of infertile couples in population C were ready to undergo PGD for aneuploidies.

Flow cytometric analysis of CD3/TCR complex, zinc, and glucocorticoid-mediated regulation of apoptosis and cell cycle distribution in thymocytes from old mice

Apoptosis represents the main mechanism involved in the intrathymic cell selection. The involution and atrophy of the thymic gland during aging has been associated with an altered representation of thymocyte subsets and particularly of CD4+CD8+ double-positive (DP) thymocytes, i.e., the cell population mainly involved in thymocyte selection. The aim of the present study was to evaluate the responsiveness of thymocytes from old mice to factors regulating the apoptotic cell death, such as antibodies to CD3/T cell receptor complex, zinc, and dexamethasone (DEX). Balb/c mice were used at the ages of 2 months (young), 21-22 months (old), and 24-26 months (very old). Thymocytes from these mice were incubated overnight with anti-CD3 monoclonal antibody (8 microg/ml), Zn2+ (150 microM), or DEX (10[-7] M) and then analysed for number of apoptotic nuclei, cell cycle phase, and phenotype by flow cytometry. A significant decrease of both the total number and the proportion of DP thymocytes was present in old and very old mice in comparison with young animals. Antibodies to CD3 antigen induced thymocyte apoptosis in both young and old mice. The stimulation of the CD3/TCR complex was more effective in giving apoptosis in very-old than in old and young mice. An impairment of the inhibiting effect of zinc on apoptosis induced by either serum deprivation or DEX was found in old and very old mice, whereas zinc was less effective in inhibiting CD3-induced apoptosis only in very old animals. Reduced DEX-induced apoptosis was also present in old age; this effect was more evident in very old than in old mice. Thymocyte apoptosis in old mice required protein synthesis being blocked with cycloheximide. Apoptosis was exerted on thymocytes in a specific cell cycle phase, i.e., on G0/G1 phase cells. Anti-CD3 antibodies, Zn2+, or DEX regulated apoptosis by modulating the proportion of DP thymocytes. The results demonstrate an altered in vitro responsiveness of thymocytes from old and very old mice to factors regulating apoptosis and suggest further investigations to determine if this altered responsiveness is associated with increased apoptosis of thymocyte populations occurring with increasing age.

Conjugation of 5-fluoro-2'-deoxyuridine with lactosaminated poly-l-lysine to reduce extrahepatic toxicity in the treatment of hepatocarcinomas

BACKGROUND

The hepatocyte receptor for asialoglycoproteins, which binds and internalizes galactosyl-terminating peptides, was found to be expressed also on the cells of well differentiated hepatocarcinomas.

AIMS

We explored the possibility of obtaining a delivery of antiblastic drugs to hepatocarcinoma cells through this receptor.

METHODS

We conjugated 5-fluoro-2'-deoxyuridine (FUDR) with lactosaminated poly-L-lysine. 5-fluoro-2'-deoxyuridine is an active drug in the treatment of solid tumours, but with toxic effects on intestine and bone marrow. Poly-L-lysine is an galactosyl-terminating carrier which enables preparation of conjugates with very high drug load. We studied the pharmacological activity of poly-L-lysine-5-fluoro-2'-deoxyuridine conjugate on in vitro proliferation of Hep G2 cells, a human hepatocarcinoma cell line. Moreover, we compared the levels of radioactivity in liver, intestine and heart of mice injected with free or conjugated [3H]5-fluoro-2'-deoxyuridine.

RESULTS

We found that poly-L-lysine-5-fluoro-2'-deoxyuridine enters into Hep G2 cells through the asialoglycoprotein receptor and, after intracellular penetration, releases the drug in a pharmacologically active form. Administered to mice, the conjugate leads to enhanced accumulation of the drug in liver versus the intestine and the heart.

CONCLUSIONS

These data support conjugation with poly-L-lysine as a way to obtain drug targeting to those hepatocellular carcinomas which maintain the asialoglycoprotein receptor.

Generation of human lymphokine-activated killer cells following an IL-2 pulse in elderly cancer patients

The toxicity of high-dose interleukin 2 (IL-2) treatments limits its use in tumour therapies, particularly in older age groups, characterized by a reduced tolerance to antineoplastic therapies. Here, we evaluated the possibility to induce cytotoxic lymphokine-activated killer (LAK) cells through a brief exposure (1-h pulse) of peripheral blood mononuclear cells (PBMC) from elderly cancer patients to high concentrations of IL-2. The cytotoxic activity, phenotype, apoptosis, and cell cycle phase of IL-2 pulsed PBMC were determined and compared with those of non-pulsed PBMC cultured continuously in IL-2. Significant levels of LAK cytotoxicity were obtained in pulsed PBMC from all patients examined. The mean values of lytic activity on day 6 of culture were lower, even if not significantly, in pulsed than non-pulsed cultures. The pulsed cells were phenotypically similar to non-pulsed lymphocytes with regards to the expression of CD3, CD4, CD8, CD16, and CD56 antigens. The induction of activation markers, like CD25 and CD122 IL-2 receptors and CD71 transferrin receptor, was also comparable in pulsed and non-pulsed cultures. When a lower cytotoxicity was found in pulsed cultures, a lower number of CD54+ (ICAM-1) cells was also found. LAK cell cytotoxicity and number of CD54 cells were significantly correlated. No difference was found between pulsed and non-pulsed cultures in their cell cycle phase or in the percentage of apoptotic cells. Autologous plasma did not inhibit the differentiation of pulsed PBMC into LAK cells. The IL-2 pulse of PBMC from healthy young donors resulted in the induction of LAK cytotoxicity as observed in elderly cancer patients. The results demonstrate the effectiveness of IL-2 pulse to generate cytotoxic LAK cells in elderly cancer patients suggesting the potential application of pulsing procedures to treatment of older age groups.

Liver targeting of antiviral nucleoside analogues through the asialoglycoprotein receptor

In order to reduce the extrahepatic side-effects of antiviral nucleoside analogues in the treatment of chronic viral hepatitis, these drugs are conjugated with galactosyl-terminating macromolecules. The conjugates selectively enter hepatocytes after interaction of the carrier galactose residues with the asialoglycoprotein receptor present in large amounts and high affinity only on these cells. Within hepatocytes the conjugates are delivered to lysosomes where enzymes split the bond between the carrier and the drug, allowing the latter to become concentrated in the liver. The validity of this chemotherapeutic strategy has been endorsed by a clinical study. Adenine arabinoside monophosphate (ara-AMP), conjugated with lactosaminated human serum albumin (L-HSA) and administered to hepatitis B virus (HBV)-infected patients for 28 days, exerted an antiviral activity to the same extent as the free drug without producing any clinical side-effects, including the severe neurotoxicity caused by the free drug. Preclinical studies are now underway with conjugates obtained using lactosaminated poly-L-lysine (Lac-poly(Lys)) as the hepatotropic carrier. These new conjugates have some advantages over those prepared with L-HSA: they can be administered by the intramuscular route; they are obtained entirely by chemical synthesis, thus eliminating the problems involved in the use of haemoderivatives; they have a heavy drug load, which permits administration of smaller quantities of conjugate that are more easily digested in lysosomes; and they enable higher quantities of drug to be introduced into hepatocytes. The results of the experiments with two Lac-poly(Lys) conjugates, one with ara-AMP and one with ribavirin, are reported in this review.

Leptin serum levels in normal weight and obese children and adolescents: relationship with age, sex, pubertal development, body mass index and insulin

OBJECTIVE

Leptin, the product of the ob gene, is present in higher concentrations in blood of obese subjects than of lean subjects. There is scarce information on the role of leptin in the pathogenesis of human obesity and little is known about leptin serum levels in obese children.

DESIGN, SUBJECTS AND MEASUREMENTS

To evaluate the influences of age, sex, pubertal development and weight excess on serum leptin levels, we have studied 390 obese subjects (OS) and 320 normal weight subjects (NWS) aged 5-16 y. Fasting insulin concentrations were assayed in NWS, and an oral glucose tolerance test was carried out in OS and total insulin area under the curve (TIA) was calculated.

RESULTS

Log-transformed values of leptin serum concentrations appeared to be distributed according to an acceptable Gaussian pattern. As observed in adults, serum leptin concentrations in children and adolescents were also increased (4-5 times) in OS as compared to NWS. In both males and females, subdivided according to pubertal stages, serum leptin varied significantly in stage IV-V as compared to the lower stages, with a reduction in males and an increase in females. On comparing the two sexes, greater serum leptin concentrations were observed in females of both NWS and OS. A significant linear correlation was found in both groups, subdivided according to sex and pubertal stage, between log values of serum leptin and standard deviation scores (SDS) of body mass index (BMI), and log-transformed relative body weight (RBW). Using partial correlation analysis in subjects subdivided according to sex and pubertal stages, log values of serum leptin and fasting insulin values, adjusted by age and SDS of BMI, correlated significantly with a weaker correlation in males than in females. In OS, the leptin concentrations correlated better with TIA than with fasting insulin. A weight reduction program (WRP) was carried out in 141 OS and significant reductions of serum leptin and fasting insulin were observed, showing a reduction of RBW. There was a correlation between the reduction of RBW and of serum leptin, but not of fasting insulin. No variation was found in non-responsive OS. RBW reduction correlated with leptin, but not with insulin (fasting and TIA), evaluated before the therapeutic program started.

CONCLUSION

As observed in adults, obese children and adolescents have higher serum leptin concentrations. However, several conditions should be taken into account when evaluating leptin concentrations in children. There are differences, independent of BMI, relative to pubertal stage and sex, females having greater leptin concentrations than males. There is evidence of a possible role for leptin in the effectiveness of a weight reduction program in OS.

Enhanced accumulation of ribavirin and its metabolites in liver versus erythrocytes in mice administered with the liver targeted drug

BACKGROUND

Ribavirin increases the efficacy of alpha-interferon in chronic hepatitis C, but accumulates in erythrocytes causing haemolysis.

AIMS

To reduce this side effect we conjugated ribavirin with lactosaminated poly-L-lysine.

METHODS

In mice administered with the same dose of free or conjugated [3H]ribavirin we determined the levels of radioactivity in liver and erythrocytes and measured the hepatic concentrations of ribavirin triphosphate. Moreover, we determined the doses of free and conjugated ribavirin producing a 50% reduction in the virus titre (ED50) in liver of mice infected with murine hepatitis virus.

RESULTS

In mice treated with the conjugate, the ratio dpm in liver/dpm in erythrocytes was 2.2- or 4.7-fold higher than in animals administered with the free drug given intramuscularly or orally, respectively. The concentration of [3H]ribavirin triphosphate was found to be 2-fold higher in mice injected with the conjugated drug than in animals orally treated with free ribavirin. In murine hepatitis virus infected mice, the ED50 was 27.4 micrograms/g for conjugated ribavirin and 47.2 micrograms/g for the free drug.

CONCLUSIONS

These results support the possibility that conjugated ribavirin may produce the same pharmacological activity in liver as the free drug but with a reduced haemolysis.

Ribavirin conjugated with lactosaminated poly-L-lysine: selective delivery to the liver and increased antiviral activity in mice with viral hepatitis

Ribavirin (RIBV) is a useful drug in the treatment of chronic type C hepatitis but displays a toxicity for red blood cells (RBC), which limits its dosage and necessitates withdrawal in some patients. Selective concentration of RIBV in liver should improve therapeutic results. Liver targeting can be achieved by coupling the drug to galactosyl-terminating peptides, which specifically enter hepatocytes. In the present work, we conjugated RIBV to lactosaminated poly-L-lysine (L-Poly(Lys)), a hepatotropic carrier enabling intramuscular (IM) administration of conjugates. The L-Poly(Lys)-RIBV conjugate had a heavy drug load (312-327 microg of RIBV in 1 mg of conjugate) and was very soluble in 0.9% NaCl (200 mg/mL). The conjugate was devoid of acute toxicity in mouse. When incubated with human or mouse blood, it did not release the drug. After IM administration to mice, the conjugate was selectively taken up by the liver, where the drug was released in a pharmacologically active form. This was demonstrated using mice infected with a strain of murine hepatitis virus (MHV) sensitive to RIBV. Coupled RIBV, IM injected, inhibited MHV replication in liver at a daily dose two to three times lower than that of the free drug. In mice IM injected with a conjugate tritiated in the RIBV moiety, the ratios between the levels of radioactivity in liver and RBC were two times higher than in animals injected with free tritiated RIBV. In conclusion, the present results support the possibility that the chemotherapeutic index of RIBV in chronic type C hepatitis can be increased by conjugation with L-Poly(Lys).

Incidence of bladder cancer in areas “at risk”

– Cancer of the bladder is closely correlated to life style and exposure to environmental and occupational chemical substances. This study, based on data taken from the tumour register of the Province of Ragusa for the period 1988–1992, has shown that bladder cancer is higher in terms of incidence and mortality than the national average. Epidemiological data would seem to back up the suspicion that there is a link between bladder cancer and phytopharmaceuticals, which could act as “initiator” and/or “promoter” agents according to the “carcinogenesis in two stages” theory. Further research will also be carried out with specific toxicological studies.