Insulin receptor substrate-1, p70S6K, and cell size in transformation and differentiation of hemopoietic cells

After an initial burst of cell proliferation, the type 1 insulin-like growth factor receptor (IGF-IR) induces granulocytic differentiation of 32D IGF-IR cells, an interleukin-3-dependent murine hemopoietic cell line devoid of insulin receptor substrate-1 (IRS-1). The combined expression of the IGF-IR and IRS-1 (32D IGF-IR/IRS-1 cells) inhibits IGF-I-mediated differentiation, and causes malignant transformation of 32D cells. Because of the role of IRS-1 in changing the fate of 32D IGF-IR cells from differentiation (and subsequent cell death) to malignant transformation, we have looked for differences in IGF-IR signaling between 32D IGF-IR and 32D IGF-IR/IRS-1 cells. In this report, we have focused on p70(S6K), which is activated by the IRS-1 pathway. We find that the ectopic expression of IRS-1 and the inhibition of differentiation correlated with a sustained activation of p70(S6K) and an increase in cell size. Phosphorylation in vivo of threonine 389 and, to a lesser extent, of threonine 421/serine 424 of p70(S6K) seemed to be a requirement for inhibition of differentiation. A role of IRS-1 and p70(S6K) in the alternative between transformation or differentiation of 32D IGF-IR cells was confirmed by findings that inhibition of p70(S6K) activation or IRS-1 signaling, by rapamycin or okadaic acid, induced differentiation of 32D IGF-IR/IRS-1 cells. We have also found that the expression of myeloperoxidase mRNA (a marker of differentiation, which sharply increases in 32D IGF-IR cells), does not increase in 32D IGF-IR/IRS-1 cells, suggesting that the expression of IRS-1 in 32D IGF-IR cells causes the extinction of the differentiation program initiated by the IGF-IR, while leaving intact its proliferation program.

[Adjuvant chemotherapy of non-seminoma stage I germ cell tumors of the testis]

OBJECTIVE

To review the treatment of stage I nonseminomatous germ cell testicular tumor with adjuvant chemotherapy.

METHODS

The literature on this subject was reviewed.

RESULTS/CONCLUSIONS

Overall, 30% of stage I nonseminomatous germ cell testicular tumors that are followed recur within two subsequent years. Several factors associated with a higher risk have been described. The most important are the presence of venous or lymphatic infiltration, the presence of a carcinoembryonic component and the absence of tumor of the endodermal sinus. Patients with the foregoing characteristics have a recurrence rate of approximately 50%. Over the last few years, some experience using two cycles of BEP adjuvant chemotherapy in patients at a higher risk have shown that this recurrence rate can be reduced to less than 5% with minimal late toxicity.

Cholesterol biosynthesis in normocholesterolemic patients after cholesterol removal by plasmapheresis

Plasmapheresis and low-density lipoprotein (LDL)-apheresis are recognized procedures for the treatment of hyperlipidemia resistant to diet and lipid-lowering drugs and provide information on cholesterol synthesis in hypercholesterolemic patients. However, cholesterol synthesis after acute cholesterol removal from plasma has never been investigated in normocholesterolemic patients. In this study, cholesterol synthesis was evaluated in three normocholesterolemic patients by determination of plasma lathosterol, lathosterol-to-cholesterol ratio, and plasma mevalonic acid. In a short-term kinetic study, samples were collected before and after plasmapheresis and every 6 hours during 24 hours. In the second part of the study, cholesterol synthesis was evaluated daily for 3 days. In normocholesterolemic patients, cholesterol returns to basal levels in 3 days. However, cholesterol removal did not result in a significant increase in lathosterol-to-cholesterol ratio or in plasma mevalonic acid, despite a slight increase in lathosterol. In contrast, when repeated plasma exchanges induced a dramatic hypocholesterolemia (< 1 mmol/liter), an acute but transient stimulation of cholesterol synthesis was observed (lathosterol/cholesterol ratio and MVA, respectively, increase from 8.2 to 22.3 and from 28 nmol/liter to 98 nmol/liter). This study shows that cholesterol synthesis is not stimulated by plasmapheresis in normocholesterolemic patients but is enhanced in dramatic hypocholesterolemic patients (< 1 mmol/liter).

Peripheral versus central effects of glucagon-like peptide-1 receptor agonists on satiety and body weight loss in Zucker obese rats

The present study explores the potential utility of peripheral versus central administration of glucagon-like peptide-1 (GLP-1) receptor agonists in the regulation of feeding behavior in Wistar and Zucker obese rats. Acute central (intracerebroventricular [i.c.v.]) and peripheral (subcutaneous [s.c.]) administration of both GLP-1 (7-36) amide and exendin-4 resulted in a reduction in food intake for at least 4 hours, exendin-4 being much more potent than GLP-1 (7-36) amide, especially after peripheral administration. Both Zucker obese rats (fa/fa) and their lean littermates (Fa/-) responded to acute central and peripheral administration of exendin-4. Moreover, in situ hybridization revealed specific labeling for the mRNA for GLP-1 receptors in several brain areas of both the obese and lean rats. The presence of this receptor was also detected by affinity cross-linking assays. Long-term s.c. administration of exendin-4 (1 single injection per day, 1 hour prior to the onset of the dark phase of the cycle) decreased daily food intake and practically blocked weight gain in obese rats. In contrast to previous studies, these findings show that peripheral (s.c.) administration of both GLP-1 receptor agonists also induces satiety and weight loss in rats, and suggest the potential usefulness of exendin-4 as a therapeutic tool for the treatment of diabetes and/or obesity.

Reversal of dopamine D(2) receptor responses by an anandamide transport inhibitor

We characterized the pharmacological properties of the anandamide transport inhibitor N-(4-hydroxyphenyl)-arachidonamide (AM404) in rats and investigated the effects of this drug on behavioral responses associated with activation of dopamine D(2) family receptors. Rat brain slices accumulated [(3)H]anandamide via a high-affinity transport mechanism that was blocked by AM404. When administered alone in vivo, AM404 caused a mild and slow-developing hypokinesia that was significant 60 min after intracerebroventricular injection of the drug and was reversed by the CB1 cannabinoid receptor antagonist SR141716A. AM404 produced no significant catalepsy or analgesia, two typical effects of direct-acting cannabinoid agonists. However, AM404 prevented the stereotypic yawning produced by systemic administration of a low dose of apomorphine, an effect that was dose-dependent and blocked by SR141716A. Furthermore, AM404 reduced the stimulation of motor behaviors elicited by the selective D(2) family receptor agonist quinpirole. Finally, AM404 reduced hyperactivity in juvenile spontaneously hypertensive rats, a putative model of attention deficit hyperactivity disorder. The results support a primary role of the endocannabinoid system in the regulation of psychomotor activity and point to anandamide transport as a potential target for neuropsychiatric medicines.

Does treatment of bladder dysfunction prior to renal transplant improve outcome in patients with posterior urethral valves?

Fourteen patients with posterior urethral valves and end-stage renal failure were urodynamically evaluated in order to identify and correct any bladder dysfunction before renal transplant. Of the 14 patients, during filling, six had normal bladder function, two had an over-distended bladder (one with instability), one had instability, four had poor compliance, and one had a very reduced bladder capacity. During the voiding phase, one had a myogenic failure and another had detrusor-sphincteric dyssynergia. Four patients underwent bladder augmentation. Three were managed with anticholinergic therapy and two required clean intermittent catheterization owing to post-voiding residual urine. A renal transplant was performed in all of these patients at a mean age of 8.2 years. We compared outcome in these 14 patients with bladder dysfunction treated before transplantation with outcome in a matched control group of 14 transplant patients. Graft function and survival were similar in both groups. We believe that urodynamic studies must be included in the pretransplant evaluation of patients with posterior urethral valves in order to diagnose any bladder dysfunction and commence appropriate treatment to avoid any negative influence on graft function.

Insulin-like growth factor I receptor signaling in differentiation of neuronal H19-7 cells

The type I insulin-like growth factor receptor (IGF-IR) is known to send two seemingly contradictory signals inducing either cell proliferation or cell differentiation, depending on cell type and/or conditions. H19-7 cells are rat hippocampal neuronal cells immortalized by a temperature-sensitive SV40 large T antigen that grow at 34 degrees C in epidermal growth factor or serum but differentiate at 39 degrees C when induced by basic fibroblast growth factor. At 39 degrees C, expression of the human IGF-IR in H19-7 cells induces an insulin-like growth factor (IGF) I-dependent differentiation. We have investigated the domains of the IGF-IR required for differentiation of H19-7 cells. The tyrosine 950 residue and serines 1280-1283 in the COOH terminus of the receptor are required for IGF-I-induced differentiation at 39 degrees C, although they are dispensable for IGF-I-mediated growth at 34 degrees C. Both domains have to be mutated to inactivate the differentiating function. The inability of these mutant receptors to induce differentiation correlates with mitogen-activated protein kinase activation. In contrast, inhibitors of phosphatidylinositol 3'-kinase have no effect on IGF-I-mediated differentiation of H19-7 cells, although they do inhibit the mitogenic response.

Standardized approach for microsatellite instability detection in colorectal carcinomas

BACKGROUND

Ubiquitous mutations in microsatellite DNA sequences define a specific type of genetic instability, termed microsatellite instability (MSI). Various approaches have been used to identify the presence and degree of MSI. To define standard diagnostic criteria for MSI, we developed and tested a mathematical model.

METHODS

We designed an algorithm for the efficient characterization of MSI and used it to analyze data on six microsatellite markers in colorectal carcinoma and normal tissues from 415 patients. Theoretical models considering one, two, or three populations were tested against the data collected.

RESULTS

The observed frequencies of MSI in our series of samples best fit a two-population model, stable and unstable, defined by instability in two or more of four to six markers analyzed. MSI was observed in 7.5% of the tumors. The misclassification rate was less than 5% when any four loci were analyzed and less than 1% when the six markers were used. A stepwise strategy, consisting first of a bulk screening of two loci and then a second screening of two to four additional markers, provided excellent sensitivity (>/=97%) and specificity (100%). Tumors with MSI had distinctive genetic and clinicopathologic features, including better patient survival.

CONCLUSION

To assess the presence of MSI in colorectal cancer, we have developed a simple, sensitive, and specific approach based on the apparent good fit of the data to a two-population model. Its application to a prospective series of patients with colorectal carcinomas demonstrates that the presence of MSI characterizes a subset of less aggressive tumors.

Irinotecan combined with fluorouracil compared with fluorouracil alone as first-line treatment for metastatic colorectal cancer: a multicentre randomised trial

BACKGROUND

Irinotecan is active against colorectal cancer in patients whose disease is refractory to fluorouracil. We investigated the efficacy of these two agents combined for first-line treatment of metastatic colorectal cancer.

METHODS

387 patients previously untreated with chemotherapy (other than adjuvant) for advanced colorectal cancer were randomly assigned open-label irinotecan plus fluorouracil and calcium folinate (irinotecan group, n=199) or fluorouracil and calcium folinate alone (no-irinotecan group, n=188). Infusion schedules were once weekly or every 2 weeks, and were chosen by each centre. We assessed response rates and time to progression, and also response duration, survival, and quality of life. Analyses were done on the intention-to-treat population and on evaluable patients.

FINDINGS

The response rate was significantly higher in patients in the irinotecan group than in those in the no-irinotecan group (49 vs 31%, p<0.001 for evaluable patients, 35 vs 22%, p<0.005 by intention to treat). Time to progression was significantly longer in the irinotecan group than in the no-irinotecan group (median 6.7 vs 4.4 months, p<0.001), and overall survival was higher (median 17.4 vs 14.1 months, p=0.031). Some grade 3 and 4 toxic effects were significantly more frequent in the irinotecan group than in the no-irinotecan group, but effects were predictible, reversible, non-cumulative, and manageable.

INTERPRETATION

Irinotecan combined with fluorouracil and calcium folinate was well-tolerated and increased response rate, time to progression, and survival, with a later deterioration in quality of life. This combination should be considered as a reference first-line treatment for metastatic colorectal cancer.

Determination of lithium in human serum by electrothermal atomic absorption spectrometry

An efficient method was developed for the determination of nanogram levels of lithium in biological samples. Serum samples from human subjects from southeastern Spain, treated or not treated with lithium carbonate, were analyzed by electrothermal atomic absorption spectrometry. The samples were previously treated with a matrix modifier consisting of 0.1% Triton X-100 and injected through a graphite tube with L'vov platform. The Li concentrations measured by the procedure described for the 3 certified reference samples used were not significantly different (p > 0.05) than certified levels. Sample recoveries and variability during several days, with coefficients of variation from 4.00 to 14.8%, demonstrated the reliability and accuracy of this technique. Mean Li concentration determined in the serum of individuals with psychiatric disorders treated with Li (n = 117, 5.077 +/- 1.795 microg Li/mL) was significantly higher (p < 0.001) than that in individuals not treated with Li (n = 24, 1.902 +/- 2.054 ng Li/mL).

Analysis of chromosome 6p in Spanish families with recessive polycystic kidney disease

Several previous reports have suggested that autosomal recessive polycystic kidney disease (ARPKD) is caused by mutations in a single gene (the PKDH1 gene). Linkage analysis showed a positive linkage for polymorphic markers at the short arm of chromosome 6 (6p) in all families. PKHD1 has not been cloned. Recombinants in the critical region would permit the narrowing of the 6p interval containing the PKHD1 gene, thus facilitating the final identification (cloning) of this gene. Our study included 30 Spanish families. Each family consisted of both parents and at least two children, with at least one diagnosed with ARPKD by clinical and pathological parameters. DNA was obtained and 6p microsatellite markers were used to establish haplotypes for each family. A positive linkage to chromosome 6p was found for all families. In 2 cases, recombinants in the region containing the PKHD1 gene were found. These families will help narrow the size of the 6p region, facilitating the efforts to position and clone the PKHD1 gene. In conclusion, our analysis of Spanish ARPKD families confirms the lack of linkage heterogeneity. This suggests that mutations at a single locus on chromosome 6p21.1-p12 are responsible for the broad clinical spectrum of variable phenotypes.

Massive intrahepatic extramedullary hematopoiesis in myelofibrosis

We describe the sonographic (US) and computed tomographic appearances of a large, solitary tumor in the liver produced by extramedullary hematopoiesis in an 82-year-old patient with agnogenic myeloid metaplasia. Confirmation of this diagnosis was made by US-guided fine-needle aspiration biopsy.

Single-tube balanced heminested PCR for detecting Mycobacterium tuberculosis in smear-negative samples

In order to achieve more sensitive and specific results for the rapid diagnosis of tuberculosis, we have developed a new method, named balanced heminested PCR, which avoids the inconvenience of asymmetric amplification and has the advantages of single-tube heminested PCR. This was achieved by replacing the outer primer that participates in both rounds of amplification in the standard heminested technique by another primer containing the sequence of the inner primer attached at its 5' end. When both techniques were tested for the IS6110 target of Mycobacterium tuberculosis complex in 80 smear-negative culture-positive sputum samples and 60 control samples, the results showed 100% specificity for both techniques and sensitivities of 60 and 75% for heminested PCR and balanced heminested PCR, respectively (P = 0.02). In conclusion, the balanced heminested technique shows a higher sensitivity than that of the standard heminested, and it could be applied to any PCR by attaching the inner primer at the 5' end of the opposite outer primer. Thus, the balanced heminested technique provides a target for the inner primer in both strands, avoiding asymmetric amplification and thereby resulting in a more efficient amplification, and, in practice, a higher sensitivity without loss of specificity and with a minimum risk of cross-contamination.

Maternal exposure to the synthetic cannabinoid HU-210: effects on the endocrine and immune systems of the adult male offspring

Natural and synthetic cannabinoid receptor agonists have been described to exert profound effects on both the neuroendocrine integration and the functional responses of the immune system. In the present study, Wistar rats were exposed to the highly potent cannabinoid agonist HU-210 (1, 5 and 25 microg/kg) during gestation and lactation and the ensuing effects on several endocrine and immune parameters of the adult male offspring were analyzed. Perinatal exposure to HU-210 partially affected the distribution of lymphocyte subpopulations in the spleen and peripheral blood. The major changes observed occur after maternal exposure to the 25 microg/kg dose of HU-210. There was a reduction in the T-helper subpopulation in the spleen and a dose-related decrease in the rate of T(helper)/T(cytotoxic) in peripheral blood lymphocytes. Concanavalin-A and lipopolysaccharide-induced proliferation were normal in all the groups tested. In the same animals, perinatal exposure to HU-210 did not affect basal levels of growth hormone, IGF-1, prolactin, or follicle-stimulating hormone. Basal values of luteinizing hormone were elevated in animals given the 1 microg/kg dose of HU-210. Corticosterone levels were reduced in the animals exposed to the higher dose of HU-210 during gestation and lactation. These animals exhibited a decreased responsiveness of the hypothalamo-pituitary-adrenal (HPA) axis to the stimulation with a single injection of HU-210 (20 microg/kg, i.v.) at adult ages, which may reflect the onset of long-lasting tolerance to the HPA-activating properties of cannabinoids. The opposite pattern of response was found in the animals given the 1 microg/kg dose, in which a sensitization of the corticosterone response to acute HU-210 was observed. The present work reveals that maternal exposure to cannabinoids results in minor changes in the development of the immune system, but may induce long-lasting alterations in the functional status of the HPA axis.

Increased serum levels of soluble L-selectin (CD62L) in patients with active systemic lupus erythematosus (SLE)

The adhesion molecule L-selectin (CD62L) mediates lymphocyte recirculation and leucocyte rolling on vascular endothelium at sites of inflammation. Serum levels of soluble L-selectin (sL-selectin) were measured in patients with SLE in order to relate these levels to clinical activity and immunological parameters. An ELISA was used to detect the soluble form of human L-selectin (CD62L) in 42 patients with SLE and in 33 healthy individuals. The mean +/- s.e.m. values of sL-selectin were 1285 +/- 121 ng/ml for patients with SLE and 986 +/- 180 ng/ml for healthy blood donors, but there was no significant difference. When patients with active SLE were analysed, higher levels of circulating sL-selectin were found when compared with patients without activity (1497 +/- 167 ng/ml versus 941 +/- 150 ng/ml; P = 0.028). We found a significant correlation between the levels of sL-selectin and of dsDNA antibodies (r = 0.36, P = 0. 044) and between levels of sL-selectin and SLE Disease Activity Index (SLEDAI) score (r = 0.42, P = 0.003). Patients with active SLE studied cross-sectionally showed significant elevations of sL-selectin (CD62L) compared with controls. Thus, the levels of this soluble adhesion molecule correlated with active disease and levels of anti-dsDNA antibodies.

Lessons learned from enrollment in the BEST study--a multicenter, randomized trial of group psychosocial support in metastatic breast cancer

The BEST study, a multicenter randomized trial of group psychosocial support in metastatic breast cancer, had several unusual features that may have influenced recruitment, notably the group nature of the intervention and the need for close collaboration between medical and psychosocial investigators. The recruitment process was examined in light of these features. Establishment of study centers was facilitated by involvement of experienced medical investigators who had successfully collaborated in previous research projects. Systematic evaluation of potential subjects or direct recruitment by psychosocial investigators optimized recruitment; however, the group nature of the intervention prolonged recruitment. Overall, 652 women were approached and 237 (43.3% of those medically eligible) randomized. Using population-based estimates, 24.3% of women with metastatic breast cancer were assessed for the study and 8.7% randomized. A randomization ratio of 2:1 was required to form and maintain groups. Competing clinical trials were the greatest barrier to recruitment. Five lessons were learned during recruitment for this trial: (1) multicenter randomized trials of psychosocial interventions are feasible, even in very ill patients, (2) the use of a group intervention effectively increased the required sample size by 50%, (3) similarity of randomization rates suggests that generalizability of study results will probably be comparable to that of other randomized cancer trials, (4) multidisciplinary collaborations and involvement of experienced researchers facilitated enrollment, and (5) most challenges encountered in recruitment were similar to those seen in all clinical trials.

PTEN tumour suppressor is linked to the cell cycle control through the retinoblastoma protein

The tumour suppressor PTEN, also named MMAC1 or TEP1, is associated with a number of malignancies in human populations. This protein has a dual protein phosphatase activity, being also capable to dephosphorylate phosphatidylinositol 3,4,5 triphosphate. We have studied the mechanism of growth suppression attributable to PTEN. We observed that PTEN overexpression inhibits cell growth in a variety of normal and transformed, human and murine cells. Bromodeoxyuridine (BrdU) incorporation and TUNEL labelling experiments in transiently transfected cells demonstrate that this inhibition is due to a cell cycle arrest rather than induction of apoptosis. Given that PTEN is unable to cause cell growth arrest in retinoblastoma (Rb)-deficient cell lines, we have explored the possible requirement for pRb in the PTEN-induced inhibition of cell proliferation. We found that the co-expression of SV40 antigen, but not a mutant form (which binds exclusively to p53), and cyclin D1/cdk4 are able to overcome the PTEN-mediated growth suppression. In addition, the reintroduction of a functional pRb, but not its relatives p107 or p130, in Rb-deficient cells restores the sensitivity to PTEN-induced arrest. Finally, the hyperphosphorylation of transfected pRb is inhibited by PTEN co-expression and restored by PI-3K co-expression. Accordingly, PTEN gene is mostly expressed, in parallel to Akt, in mid-late G1 phase during cell cycle progression prior to pRb hyperphosphorylation. Finally, we have studied the signal transduction pathways modulated by PTEN expression. We found that PTEN-induced growth arrest can be rescued by the co-expression of active PI-3K and downstream effectors such as Akt or PDK1, and also certain small GTPases such as Rac1 and Cdc42, but not by active Ha-ras, raf or RhoA. Collectively, our data link the tumour suppressor activities of PTEN to the machinery controlling cell cycle through the modulation of signalling molecules whose final target is the functional inactivation of the retinoblastoma gene product.

The involvement of kallikrein-kinin system in diabetes type I (insulitis)

Islet inflammation or insulitis is followed by selective destruction of the insulin secreting B-cell. Animal models of insulin-dependent diabetes mellitus (IDDM) have been used to characterize more fully insulitis, and our results with C57/BL/Ks mdb with low doses of streptozotocin (STZ) confirmed the disease. B1 receptor antagonist [Leu8]des-Arg9-BK has shown a significant effect on diabetic glycemia and renal control parameters. Compared to insulin, the drug was effective to prevent the insulitis and the renal damage. On the other hand, B2 receptor antagonist (HOE 140) and ACE-I (captopril) were only able to control the urinary diabetic proteinuria.