SYK-3BP2 Pathway Activity in Parenchymal and Myeloid Cells Is a Key Pathogenic Factor in Metabolic Steatohepatitis

BACKGROUND & AIMS

Spleen tyrosine kinase (SYK) signaling pathway regulates critical processes in innate immunity, but its role in parenchymal cells remains elusive in chronic liver diseases. We investigate the relative contribution of SYK and its substrate c-Abl Src homology 3 domain-binding protein-2 (3BP2) in both myeloid cells and hepatocytes in the onset of metabolic steatohepatitis.

METHODS

Hepatic SYK-3BP2 pathway was evaluated in mouse models of metabolic-associated fatty liver diseases (MAFLD) and in obese patients with biopsy-proven MAFLD (n = 33). Its role in liver complications was evaluated in Sh3bp2 KO and myeloid-specific Syk KO mice challenged with methionine and choline deficient diet and in homozygous Sh3bp2^KI/KI mice with and without SYK expression in myeloid cells.

RESULTS

Here we report that hepatic expression of 3BP2 and SYK correlated with metabolic steatohepatitis severity in mice. 3BP2 deficiency and SYK deletion in myeloid cells mediated the same protective effects on liver inflammation, injury, and fibrosis priming upon diet-induced steatohepatitis. In primary hepatocytes, the targeting of 3BP2 or SYK strongly decreased the lipopolysaccharide-mediated inflammatory mediator expression and 3BP2-regulated SYK expression. In homozygous Sh3bp2^KI/KI mice, the chronic inflammation mediated by the proteasome-resistant 3BP2 mutant promoted severe hepatitis and liver fibrosis with augmented liver SYK expression. In these mice, the deletion of SYK in myeloid cells was sufficient to prevent these liver lesions. The hepatic expression of SYK is also up-regulated with metabolic steatohepatitis and correlates with liver macrophages in biopsy-proven MAFLD patients.

CONCLUSIONS

Collectively, these data suggest an important role for the SYK-3BP2 pathway in the pathogenesis of chronic liver inflammatory diseases and highlight its targeting in hepatocytes and myeloid cells as a potential strategy to treat metabolic steatohepatitis.

Electrochemical impedance spectroscopy characterization of beverages

This paper compares the results of standard chemical analytical processes and electrochemical impedance spectroscopy (EIS) in the characterization of different beverages, namely ground coffee, soluble coffee, coffee substitutes, barley, cow milk, vegetable drinks, tea, plant infusions and plant mixtures. For the two approaches, the similarities between the experimental data are assessed by means of the Euclidean and Canberra distances. The resulting information is processed by means of the multidimensional scaling (MDS) clustering and visualization algorithm. The results of the chemical analytical processes and EIS reveal identical clusters for the two adopted distances. Furthermore, the robustness of the experimental and computational scheme are assessed by means of the Procrustes technique. The results confirm the effectiveness of combining the EIS and MDS.

Natural Killer Cells and Type 1 Innate Lymphoid Cells Are New Actors in Non-alcoholic Fatty Liver Disease

Obesity and associated liver diseases (Non Alcoholic Fatty Liver Disease, NAFLD) are a major public health problem with increasing incidence in Western countries (25% of the affected population). These complications develop from a fatty liver (steatosis) to an inflammatory state (steatohepatitis) evolving toward fibrosis and hepatocellular carcinoma. Lipid accumulation in the liver contributes to hepatocyte cell death and promotes liver injury. Local immune cells are activated either by Danger Associated Molecular Patterns (DAMPS) released by dead hepatocytes or by bacterial products (PAMPS) reaching the liver due to increased intestinal permeability. The resulting low-grade inflammatory state promotes the progression of liver complications toward more severe grades. Innate lymphoid cells (ILC) are an heterogeneous family of five subsets including circulating Natural Killer (NK) cells, ILC1, ILC2, ILC3, and lymphocytes tissue-inducer cells (LTi). NK cells and tissue-resident ILCs, mainly located at epithelial surfaces, are prompt to rapidly react to environmental changes to mount appropriate immune responses. Recent works have demonstrated the interplay between ILCs subsets and the environment within metabolic active organs such as liver, adipose tissue and gut during diet-induced obesity leading or not to hepatic abnormalities. Here, we provide an overview of the newly roles of NK cells and ILC1 in metabolism focusing on their contribution to the development of NAFLD. We also discuss recent studies that demonstrate the ability of these two subsets to influence tissue-specific metabolism and how their function and homeostasis are affected during metabolic disorders.

Quality of life and adherence to treatment in early-treated Brazilian phenylketonuria pediatric patients

Early dietary treatment of phenylketonuria (PKU), an inborn error of phenylalanine (Phe) metabolism, results in normal cognitive development. Although health-related quality of life (HRQoL) of PKU patients has been reported as unaffected in high-income countries, there are scarce data concerning HRQoL and adherence to treatment of PKU children and adolescents from Brazil. The present study compared HRQoL scores in core dimensions of Brazilian early-treated PKU pediatric patients with those of a reference population, and explored possible relationships between adherence to treatment and HRQoL. Early-treated PKU pediatric patient HRQoL was evaluated by self- and parent-proxy reports of the Pediatric Quality of Life Inventory (PedsQL) core scales. Adherence to treatment was evaluated by median Phe levels and percentage of results within the therapeutic target range in two periods. Means for total and core scales scores of PedsQL self- and parent proxy-reports of PKU patients were significantly lower than their respective means for controls. Adequacy of median Phe concentrations and the mean percentage of values in the target range fell substantially from the first year of life to the last year of this study. There was no significant difference in mean total and core scale scores for self- and parent proxy-reports between patients with adequate and those with inadequate median Phe concentrations. The harmful consequences for intellectual capacity caused by poor adherence to dietary treatment could explain the observed decrease in all HRQoL scales, especially in school functioning. Healthcare system and financial difficulties may also have influenced negatively all HRQoL dimensions.

Role of the clock gene Rev-erbα in metabolism and in the endocrine pancreas

Several hormones are regulated by circadian rhythms to adjust the metabolism to the light/dark cycles and feeding/activity patterns throughout the day. Circadian rhythms are mainly governed by the central clock located in the suprachiasmatic nucleus but also by clocks present in peripheral organs, like the endocrine pancreas. Plasma glucose levels and the main pancreatic hormones insulin and glucagon also exhibit daily variations. Alterations in circadian rhythms are associated with metabolic disturbances and pathologies such as obesity and diabetes. The molecular components of central and peripheral clocks and their regulatory mechanisms are well established. Among the different clock genes, Rev-erbα is considered one of the key links between circadian rhythms and metabolism. Rev-erbα is a critical part of a negative feedback loop in the core circadian clock and modulates the clock oscillatory properties. In addition, Rev-erbα plays an important role in the regulation of lipid and glucose metabolism, thermogenesis, adipocyte and muscle differentiation as well as mitochondrial function. In the endocrine pancreas, Rev-erbα regulates insulin and glucagon secretion and pancreatic β-cell proliferation. In the present review, we discuss all these subjects and, particularly, the role of the clock gene Rev-erbα in the endocrine pancreas.

Head-to head comparison of mGlu1 and mGlu5 receptor activation in chronic treatment of absence epilepsy in WAG/Rij rats

Acute treatment with positive allosteric modulators (PAMs) of mGlu1 and mGlu5 metabotropic glutamate receptors (RO0711401 and VU0360172, respectively) reduces the incidence of spike-and wave discharges in the WAG/Rij rat model of absence epilepsy. However, from the therapeutic standpoint, it was important to establish whether tolerance developed to the action of these drugs. We administered either VU0360172 (3 mg/kg, s.c.) or RO0711401 (10 mg/kg, s.c.) to WAG/Rij rats twice daily for ten days. VU0360172 maintained its activity during the treatment, whereas rats developed tolerance to RO0711401 since the 3rd day of treatment and were still refractory to the drug two days after treatment withdrawal. In response to VU0360172, expression of mGlu5 receptors increased in the thalamus of WAG/Rij rats after 1 day of treatment, and remained elevated afterwards. VU0360172 also enhanced mGlu5 receptor expression in the cortex after 8 days of treatment without changing the expression of mGlu1a receptors. Treatment with RO0711401 enhanced the expression of both mGlu1a and mGlu5 receptors in the thalamus and cortex of WAG/Rij rats after 3-8 days of treatment. These data were different from those obtained in non-epileptic rats, in which repeated injections of RO0711401 and VU0360172 down-regulated the expression of mGlu1a and mGlu5 receptors. Levels of VU0360172 in the thalamus and cortex remained unaltered during the treatment, whereas levels of RO0711401 were reduced in the cortex at day 8 of treatment. These findings suggest that mGlu5 receptor PAMs are potential candidates for the treatment of absence epilepsy in humans.

Leptin downregulates expression of the gene encoding glucagon in alphaTC1-9 cells and mouse islets

AIMS/HYPOTHESIS

Leptin, released by adipocytes, can modulate glucose homeostasis through direct actions on pancreatic alpha and beta cells. Although this hormone rapidly regulates alpha cell exocytosis, its long-term effects on glucagon gene expression are currently unknown.

METHODS

We analysed glucagon mRNA levels and protein content in alphaTC1-9 cells and isolated mouse islets cultured with leptin, as well as in islets from mice treated in vivo with leptin. We also studied the involvement of the signal transducers and activators of transcription (STAT) pathway by western blot, immunofluorescence and interference RNA.

RESULTS

Leptin incubation (0.0625-18.75 nmol/l) for 24 h inhibited glucagon gene expression in alphaTC1-9 cells. This inhibitory effect was also observed in isolated mouse islets cultured with leptin, as well as in islets from mice treated with leptin for 5 days. In contrast, no changes were detected in islets from db/db mice, which lack leptin receptors. Leptin treatment also reduced the glucagon protein content in alphaTC1-9 cells and mouse islets. Moreover, leptin induced phosphorylation of STAT3 and its translocation to the nucleus, which was confirmed by western blot analysis in alphaTC1-9 cells and by immunofluorescence in isolated alpha cells. Interestingly, the effect of leptin on glucagon mRNA levels was significantly reduced by Stat3 knockdown. In contrast, pharmacological inhibition of the phosphoinositide 3-kinase pathway did not affect leptin actions.

CONCLUSIONS/INTERPRETATION

Our results demonstrate that leptin can regulate glucagon gene expression in alpha cells via a STAT3 pathway, and are important for understanding the role of leptin in glucose homeostasis.

Switch in the expression of mGlu1 and mGlu5 metabotropic glutamate receptors in the cerebellum of mice developing experimental autoimmune encephalomyelitis and in autoptic cerebellar samples from patients with multiple sclerosis

Recent evidence suggests that changes in the expression of membrane receptors/ion channels in cerebellar Purkinje cells contribute to the onset of cerebellar motor symptoms in patients with multiple sclerosis (MS). We examined the expression of group-I metabotropic glutamate receptors (mGlu1 and mGlu5 receptors) in the cerebellum of mice developing experimental autoimmune encephalomyelitis (EAE) and in autoptic cerebellar samples of MS patients. EAE was induced in mice by immunization with the 35-55 fragment of MOG (myelin oligodendrocyte glycoprotein). EAE mice showed a progressive loss of mGlu1a receptors in the cerebellum, associated with an increased expression of mGlu5 receptors. These changes were restricted to Purkinje cells and their dendritic arborization, as shown by immunohistochemistry. A reduced expression of mGlu1a receptors in cerebellar Purkinje cells was also found in 7 of 9 MS patients. In addition, a light/moderate to very strong mGlu5 receptor immunoreactivity was detected in Purkinje cells of 8 MS patients, but was always absent in non-MS control patients. In EAE mice, an acute treatment with the mGlu1 receptor enhancer, 9H-xanthene-9-carboxylic acid (4-trifluoromethyl-oxazol-2-yl)-amide (RO0711401), significantly improved motor coordination, whereas treatment with the mGlu5 receptor antagonists, 2-methyl-6-(phenylethynyl)-pyridine (MPEP) and 6-methyl-2-(phenylazo)-3-pyridinol (SIB-1757), had no effect. We conclude that mGlu1 receptor enhancers improve motor symptoms associated with EAE and might be helpful as symptomatic drugs in patients with MS.

Single nucleotide polymorphisms in the apo(a) kringle IV type 8 domain are not associated with atherothrombotic serum lipoprotein (a) concentration, in a Portuguese paediatric population

Lipoprotein (a) (Lp[a]) is a complex of apolipoprotein (a) (apo[a]) and low-density lipoprotein (LDL), associated with atherothrombotic disease. Most of the interindividual variations in plasma levels of Lp(a) can be attributed to sequence differences linked to the apo(a) gene locus. The aim of this study was to investigate a possible link between single nucleotide polymorphisms (SNPs) in the apo(a) kringle (K) IV type 8 domain and atherothrombotic serum Lp(a) concentrations. Direct sequencing of the two exons and flanking intronic sequences of the apo(a) K IV type 8 domain was performed in a group of 97 paediatric patients, 51 with serum Lp(a) concentration above and 46 with concentration below 30 mg/dl,. We found three SNPs, two in exon 1 (c.66A>C and c.133G>A) and one in intron 1 (c.160+1G>A). The c.66A>C polymorphism was the most common with a heterozygosity frequency of 15.46%. The c.133G>A and c.160+1G>A polymorphisms were found at a frequency of 5.15% and 1.03%, respectively. No statistically significant difference was found in the genotype distribution between the two groups of patients. Our results suggest that these SNPs in the apo(a) K IV 8 domain are not directly associated with atherothrombotic serum Lp(a) concentration in our population.

Glucose inhibits glucagon secretion by a direct effect on mouse pancreatic alpha cells

AIMS/HYPOTHESIS

The mechanisms by which glucose regulates glucagon release are poorly understood. The present study aimed to clarify the direct effects of glucose on the glucagon-releasing alpha cells and those effects mediated by paracrine islet factors.

MATERIALS AND METHODS

Glucagon, insulin and somatostatin release were measured from incubated mouse pancreatic islets and the cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) recorded in isolated mouse alpha cells.

RESULTS

Glucose inhibited glucagon release with maximal effect at 7 mmol/l. Since this concentration corresponded to threshold stimulation of insulin secretion, it is unlikely that inhibition of glucagon secretion is mediated by beta cell factors. Although somatostatin secretion data seemed consistent with a role of this hormone in glucose-inhibited glucagon release, a somatostatin receptor type 2 antagonist stimulated glucagon release without diminishing the inhibitory effect of glucose. In islets exposed to tolbutamide plus 8 mmol/l K(+), glucose inhibited glucagon secretion without stimulating the release of insulin and somatostatin, indicating a direct inhibitory effect on the alpha cells that was independent of ATP-sensitive K(+) channels. Glucose lowered [Ca(2+)](i) of individual alpha cells independently of somatostatin and beta cell factors (insulin, Zn(2+) and gamma-aminobutyric acid). Glucose suppression of glucagon release was prevented by inhibitors of the sarco(endo)plasmic reticulum Ca(2+)-ATPase, which abolished the [Ca(2+)](i)-lowering effect of glucose on isolated alpha cells.

CONCLUSIONS/INTERPRETATION

Beta cell factors or somatostatin do not seem to mediate glucose inhibition of glucagon secretion. We instead propose that glucose has a direct inhibitory effect on mouse alpha cells by suppressing a depolarising Ca(2+) store-operated current.

Determination of neutrophil Fcgamma receptor IIIb antigens (HNA-1a, HNA-1b and HNA-1c) by fluorescence-primed allele-specific polymerase chain reaction

We evaluate a technique for genotyping HNA-1a, -1b and -1c antigens, resorting to fluorescence-primed allele-specific polymerase chain reaction (FPAS-PCR), and determine the frequency of the different genotypes in a normal Portuguese population. Our results indicate that the FPAS-PCR system is a reliable and simple tool for genotyping the neutrophil Fcgamma receptor IIIB antigens. The HNA-1a, -1b and -1c gene frequencies of 42.98, 84.21 and 6.14%, respectively, found in this study are similar to those reported for other white populations.

[Influence of Gilbert's syndrome on serum bilirubin levels and gallstone formation in children with chronic hemolytic disease]

To determine whether Gilbert's syndrome increases the risk of gallstone formation in children with chronic hemolytic disease, we studied 44 children with this diagnosis. Gallstones were detected by abdominal ultrasonography. This took place annually in scheduled examinations or in the context of acute abdominal pain. In all patients, the mean values of hemoglobin, reticulocyte and serum bilirubin in the chronic phase were recorded. In addition, TA insertion in the A(TA)nTATAA motif within the promoter region of the enzyme uridine-diphosphate-glucuronyl transferase (UGT1A1) was screened, since this is typically associated with GS.We found 10 (22.7 %) homozygotes for the mutated allele TA*7/TA*7, 12 (27.3 %) TA*6/TA*6 heterozygotes and 22 (50 %) homozygotes for the wild-type allele TA*6/TA*6. No statistically significant differences were found in the values of hemoglobin (Kruskal-Wallis test 2.496; p > 0.05) or in reticulocyte count (Kruskal-Wallis test 1.696; p > 0,05) between the three groups of patients, suggesting a similar degree of hemolysis. Patients with the UGT1A1 TA*7/TA*7 genotype showed higher mean serum bilirubin levels than did patients who were homozygous for the wild-type allele (Mann-Whitney test 35.5; p < 0.05). None of the patients with the TA*6/TA*6 genotype developed gallstones, whereas this complication was found in 2 of 12 (16.6 %) heterozygotes and 6 of 10 (60 %) homozygotes for the allele with TA insertion. In this latter group, 4 patients presented acute pancreatitis as a consequence of gallstone formation.The association between increased bilirubin load due to chronic hemolytic disease and diminished hepatic conjugation leads to raised serum bilirubin levels and consequently to an increased risk of gallstone formation. Therefore, we recommend screening for Gilbert's syndrome in children in the initial phases of chronic hemolytic diseases.

Positive allosteric modulators of metabotropic glutamate 1 receptor: characterization, mechanism of action, and binding site

We have identified two chemical series of compounds acting as selective positive allosteric modulators (enhancers) of native and recombinant metabotropic glutamate 1 (mGlu1) receptors. These compounds did not directly activate mGlu1 receptors but markedly potentiated agonist-stimulated responses, increasing potency and maximum efficacy. Binding of these compounds increased the affinity of a radiolabeled glutamate-site agonist at its extracellular N-terminal binding site. Chimeric and mutated receptors were used to localize amino acids in the receptor transmembrane region critical for these enhancing properties. Finally, the compounds potentiated synaptically evoked mGlu1 receptor responses in rat brain slices. The discovery of selective positive allosteric modulators of mGlu1 receptors opens up the possibility to develop a similar class of compounds for other family 3 G protein-coupled receptors.

Piperidine renin inhibitors: from leads to drug candidates

Non-peptidomimetic renin inhibitors of the piperidine type represent a novel structural class of compounds potentially free of the drawbacks seen with peptidomimetic compounds so far. Synthetic optimization in two structural series focusing on improvement of potency, as well as on physicochemical properties and metabolic stability, has led to the identification of two candidate compounds 14 and 23. Both display potent and long-lasting blood pressure lowering effects in conscious sodium-depleted marmoset monkeys and double transgenic rats harboring both the human angiotensinogen and the human renin genes. In addition, 14 normalizes albuminuria and kidney tissue damage in these rats when given over a period of 4 weeks. These data suggest that treatment of chronic renal failure patients with a renin inhibitor might result in a significant improvement of the disease status.

Use of nucleotides in weanling rats with diarrhea induced by a lactose overload: effect on the evolution of diarrhea and weight and on the histopathology of intestine, liver and spleen

Until recently, dietary sources of nucleotides were thought not to be essential for good nutrition. Certain states with higher metabolic demands may require larger amounts that cannot be provided by endogenous production. The objective of the present study was to determine the action of nucleotides on the recovery from lactose-induced diarrhea in weaned rats. Thirty-six weanling Fisher rats were divided into two groups. Group 1 received a standard diet and group 2 received a diet containing lactose in place of starch. On the 10th day, six animals per group were sacrificed for histopathological evaluation. The remaining animals were divided into two other subgroups, each with 6 animals, receiving a control diet, a control diet with nucleotides (0.05% adenosine monophosphate, 0.05% guanosine monophosphate, 0.05% cytidine monophosphate, 0.05% uridine monophosphate and 0.05% inosine monophosphate), a diet with lactose, and a diet with lactose and nucleotides. On the 32nd day of the experiment all animals were sacrificed. Animals with diarrhea weighed less than animals without diarrhea. The introduction of nucleotides did not lead to weight gain. Mean diet consumption was lower in the group that continued to ingest lactose, with the group receiving lactose plus nucleotides showing a lower mean consumption. Animals receiving lactose had inflammatory reaction and deposits of periodic acid-Schiff-positive material in intestinal, hepatic and splenic tissues. The introduction of nucleotides led to an improvement of the intestinal inflammatory reaction. In lactose-induced diarrhea, when the stimulus is maintained--lactose overload--the nucleotides have a limited action on the weight gain and on recovery of intestinal morphology, although they have a protective effect on hepatic injury and improve the inflammatory response.

P73 expression in neuroblastoma: a role in the biology of advanced tumors?

p73, a recently identified gene showing high homology to p53 and mapping to 1p36.33, was presented as a candidate gene for neuroblastoma. In this study the authors evaluate the levels and allelic nature of p73 expression in primary neuroblastomas using reverse transcription-polymerase chain reaction-restriction fragment length polymorphism strategies based on intragenic polymorphisms. From 32 neuroblastoma patients, 11 were heterozygous for the p73 polymorphisms analyzed. p73 expression was found to be low in the correspondent tumors and while all 6 stages 1 and 2 tumors presented biallelic expression, 4 out of the 5 stage 4 tumors showed only one active p73 allele. Analysis of blood samples from 8 healthy donors and 4 neuroblastoma patients revealed much higher levels of p73 expression, and exclusively of biallelic nature. These results are supportive of a role for p73 in the biology of neuroblastoma, particularly in some advanced tumors. Nevertheless, the G81A/C91T polymorphism, previously implicated in regulating the expression of p73, did not show any significant association with neuroblastoma development.

Transcriptional regulatory effects of lymphoma-associated NFKB2/lyt10 protooncogenes

C-terminal truncations of the NFKB2 p100 gene product have been observed in a number of cases of human cutaneous T cell lymphomas, as well as human B-cell lymphomas and myelomas. The contribution of these alterations to lymphomagenesis is not understood; however, truncation at amino acid 666 to generate 80 - 85 kD proteins in the HUT78 cell line is associated with addition of a short (serine-alanine-serine) fusion at the 3' end of p80HT, as well as with increased expression of NFKB2 mRNA. We therefore examined the effects of p80HT on the regulation of NFKB2 expression, as well as the properties of a series of other tumor-associated, and site directed mutations of NFKB2. While p80HT had not itself acquired novel transcriptional activation properties with respect to the NFKB2 P1 or P2 promoters or the IL-6 kappaB promoter, p80HT had lost the potent inhibitory (IkappaB-like) activity associated with the wild-type, p100 gene product. Loss of the inhibitory property depended on the SAS residues in the fusion protein, direct truncation at aa666 was fully inhibitory, as was a substitution of three alanines for the SAS residues. The presence of as few as two C-terminal ankyrin motifs was sufficient for inhibition of NF-kappaB-mediated transcriptional activation. Assays of a series of additional lymphoma-associated NF-kappaB-2 truncation suggested that the C-terminal truncation associated with these proteins was also associated with a loss of the IkappaB-like activities of p100 NF-kappaB-2, for at least some NF-kappaB target promoters. Thus, the loss of IkappaB-like activity of lymphoma-associated NFKB2 mutations may play an important role in the genesis of a subset of human lymphomas.

Glucose-6-phosphate dehydrogenase aveiro: a de novo mutation associated with chronic nonspherocytic hemolytic anemia

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked enzyme abnormality. The clinical phenotype is variable but often predictable from the molecular lesion. Class I variants (the most severe forms of the disease) cluster within exon 10, in a region that, at the protein level, is believed to be involved in dimerization. Here we describe a de novo mutation (C269Y) of a new class I variant (G6PD Aveiro) that maps to exon 8. Mutant and normal alleles were found in both hematopoietic and buccal cells, indicating the presence of mosaicism. The available model of the protein predicts that this lesion lies in proximity to the dimer interface of the molecule. A possible mechanism to explain the severity of the defect is proposed. (Blood. 2000;95:1499-1501)

The effects of Shaker beta-subunits on the human lymphocyte K+ channel Kv1.3

The activation of T-lymphocytes is dependent upon, and accompanied by, an increase in voltage-gated K+ conductance. Kv1.3, a Shaker family K+ channel protein, appears to play an essential role in the activation of peripheral human T cells. Although Kv1.3-mediated K+ currents increase markedly during the activation process in mice, and to a lesser degree in humans, Kv1.3 mRNA levels in these organisms do not, indicating post-transcriptional regulation. In other tissues Shaker K+ channel proteins physically associate with cytoplasmic beta-subunits (Kvbeta1-3). Recently it has been shown that Kvbeta1 and Kvbeta2 are expressed in mouse T cells and that they are up-regulated during mitogen-stimulated activation. In this study, we show that the human Kvbeta subunits substantially increase K+ current amplitudes when coexpressed with their Kv1.3 counterpart, and that unlike in mouse, protein levels of human Kvbeta2 remain constant upon activation. Differences in Kvbeta2 expression between mice and humans may explain the differential K+ conductance increases which accompany T-cell proliferation in these organisms.

[Acute lymphoblastic leukemia in childhood. A 10-year experience with the DFCI 81-01 protocol]

Acute lymphoblastic leukemia is the most frequently encountered pediatric cancer. Approximately 70% of cases can be cured of the disease. In this article, we describe the experience of our Center in the last ten years with a treatment protocol adapted from protocol DFCI 81-01 (from the Dana Farber Cancer Institute, Boston). We conclude that it is easily accomplished, well tolerated and that it allowed us to significantly improve the outcome of our patients (80% 5 year-survival). Nevertheless, we are currently in the process of changing to a new protocol--one that will hopefully achieve a comparable cure rate with less long-term toxicity.

Piperidine-renin inhibitors compounds with improved physicochemical properties

Piperidine renin inhibitors with heterocyclic core modifications or hydrophilic attachments show improved physical properties (lower lipophilicity, improved solubility). Tetrahydroquinoline derivative rac-30 with a molecular weight of 517 and a log D(pH 7.4) of 1.9 displays potent and long lasting blood pressure lowering effects after oral administration to sodium depleted conscious marmosets.

Substituted piperidines--highly potent renin inhibitors due to induced fit adaptation of the active site

The identification, synthesis and activity of a novel class of piperidine renin inhibitors is presented. The most active compounds show activities in the picomolar range and are among the most potent renin inhibitors ever identified.

Renin inhibition by substituted piperidines: a novel paradigm for the inhibition of monomeric aspartic proteinases?

BACKGROUND

The aspartic proteinase renin catalyses the first and rate-limiting step in the conversion of angiotensinogen to the hormone angiotensin II, and therefore plays an important physiological role in the regulation of blood pressure. Numerous potent peptidomimetic inhibitors of this important drug target have been developed, but none of these compounds have progressed past clinical phase II trials. Limited oral bioavailability or excessive production costs have prevented these inhibitors from becoming new antihypertensive drugs. We were interested in developing new nonpeptidomimetic renin inhibitors.

RESULTS

High-throughput screening of the Roche compound library identified a simple 3, 4-disubstituted piperidine lead compound. We determined the crystal structures of recombinant human renin complexed with two representatives of this new class. Binding of these substituted piperidine derivatives is accompanied by major induced-fit adaptations around the enzyme's active site.

CONCLUSIONS

The efficient optimisation of the piperidine inhibitors was facilitated by structural analysis of the renin active site in two renin-inhibitor complexes (some of the piperidine derivatives have picomolar affinities for renin). These structural changes provide the basis for a novel paradigm for inhibition of monomeric aspartic proteinases.

[The role of external radiotherapy in the treatment of medullary carcinoma of the thyroid]

Medullary carcinoma of the thyroid represents 3 to 10% of all thyroid cancers. Surgery is the main treatment. External beam radiotherapy has a fundamental role in the treatment of residual disease following surgery, in cases of cervical node involvement, and in unresectable tumors. Between 1975 and 1993, 12 patients with medullary carcinoma of the thyroid were treated at the Department of Radiotherapy of the Portuguese Institute of Oncology in Oporto. Nine of these patients (75%) were male and 3 (25%) female, ranging from 24 to 80 years of age (mean = 43). All of them had residual tumor after surgery and underwent treatment with external beam radiotherapy. The follow-up period ranged from 36 to 180 months, with a median of 78 months; 8 patients (66.7%) are alive, 5 of them show no evidence of disease. Average survival was 70 months, and 4 patients (33%) died with metastatic disease. The aim of this paper is to analyse the role of external beam radiotherapy in local control of these tumors, with a brief review of the literature.

[Gliosarcomas]

Gliosarcomas are rare tumors of the central nervous system with a poor prognosis. Histologically these tumors are characterized by an admixture of neoplastic glial cells and sarcomatous elements. Due to the scarcity of data in literature, the diagnosis is often missed and treatment is difficult. The authors report three cases of cerebral gliosarcomas and review the literature on this subject.

[Monoclonal antibodies. General approach and radioimmunotherapy]

Two major obstacles to systemic cancer therapy are the lack of specificity of therapeutic modalities and the intrapatient and interpatient heterogeneity of cancer cells. Because of their natural specificity, antibodies directed against tumor specific or tumor associated antigens have been raising interest in oncology. This article makes an overview of the basic principles of monoclonal antibodies, their limitations and perspectives, with particular attention to Immunoradioconjugates. The most important Immunoradiotherapy clinical studies are also reviewed.

Squamous cell carcinoma of the cervix metastatic to the spleen--case report

Squamous cell carcinoma of the cervix metastatic to the spleen is an uncommon occurrence which has only been reported in small numbers in autopsy series. We present a case of a 47-year-old patient with a Stage IIb carcinoma of the cervix, treated with radiotherapy in 1990. Four years after completion of primary treatment she presented with a voluminous left hypochondrium and epigastrium mass. An exploratory laparotomy was performed and a splenic cyst 19 cm in diameter was found. The pathological examination revealed metastatic squamous cell carcinoma of the cervix in the spleen. Peritoneal washings were positive for malignant cells, due to incidental rupture of the cyst capsule. The patient received six courses of chemotherapy with a palliative intent and is alive, without further evidence of disease, 15 months posttreatment. To our knowledge this is the only case reported in the literature of squamous cell carcinoma of the uterine cervix metastatic to the spleen, diagnosed clinically as the only site of distant spread.

Angiomatoid fibrous histiocytoma of the arm treated by radiotherapy for local recurrence--case report

The Angiomatoid Fibrous Histiocytoma is a rare tumor of soft tissues, which occurs mainly in children and young adults, with low malignancy grade. It has the capacity of local recurrence, but rarely metastizes. It is frequently difficult to differentiate this from vascular tumors, namely hemangioendotheliomas and angiosarcomas, or simply organized hematomas. The authors present a case of a patient with an angiomatoid fibrous histiocytoma of the arm, treated with radiotherapy after three postsurgical recurrences.

Hemangioendothelioma: a rare vascular tumor in childhood and adolescence

Most vascular tumors occurring in children are benign. They are recognized by their ability to form angiomatous structures. In some instances, there is no clear-cut line between a benign vascular tumor (or angioma) and a malignant vascular tumor (or angiosarcoma). The hemangioendothelioma is a rare tumor of vascular origin, involving bone or soft tissue, and represents 1% of all vascular neoplasms. Accurate diagnosis is critical in recommending the most appropriate therapy for each patient. The aim of this paper is to give a brief review of the literature of this rare entity, particularly in childhood and adolescence.

[Primary lymphomas of the brain not related to immunodeficiency]

Primary brain lymphoma (PBL) is a rare disease, the study of which is based on small series and case reports. The AA review new cases of PBL not associated to immunodeficiency at the Portuguese Institute of Oncology of Porto since 1978. Five male patients were found with lymphoma primarily located in the brain, with aggressive histology, IE staging, detected by CAT, NMR or brain scintigraphy and with histologic material collected by stereotaxic biopsy (3 cases) or by craniotomy (2 cases). Three patients were in complete remission (25,5 and 1 year) and 2 were dead with a survival of 12 and 17 months. The cases and literature are discussed.

Ciprokiren (Ro 44-9375). A renin inhibitor with increasing effects on chronic treatment

The present study characterizes the new transition-state renin inhibitor ciprokiren (Ro 44-9375) in squirrel monkeys. Arterial blood pressure was monitored by telemetry in freely moving, chronically instrumented conscious animals. In vitro at pH 7.4, ciprokiren inhibited human renin in buffer and human plasma with an IC50 of 0.07 and 0.65 nmol/L, respectively. It was equipotent against primate plasma renin and also inhibited plasma renin from dog and guinea pig in the nanomolar range (IC50, 29 and 65 nmol/L, respectively). After acute oral administration it reduced arterial blood pressure dose dependently in normotensive sodium-depleted and cyclosporin-induced hypertensive squirrel monkeys, starting with the minimal oral dose of 3 micrograms/kg. Daily oral doses of 1 microgram/kg showed a progressive blood pressure decrease, with a maximal response reached after 1 week. The drug could also be applied transdermally with similar hemodynamic effects without any decrease of plasma renin activity or plasma immunoreactive angiotensin II. Thus, ciprokiren is characterized in squirrel monkeys as a renin inhibitor with high in vivo potency that might act mainly in the tissular compartment.

Effects of water and saline irrigation during bone cutting on bone healing

The healing of standardized bony defects prepared in the mandibles of 24 vervet monkeys with a rotating bur uncooled, or cooled with saline or water, was studied. The experiment showed no difference in healing after 56 days irrespective of the coolant used or whether the bone was cut with or without a cooling agent.

Effects of intermittent 0.5% nitrous oxide/air (v/v) on the fertility of male rats and the post-natal growth of their offspring

In a study of male rat fertility male Wistar albino rats were exposed to 0.5% nitrous oxide/air mixtures (v/v) for 30 days and control rats were exposed to oil-free air for the same time period. Thereafter each male was mated with three nulliparous female rats and mated again with three more nulliparous rats after a 6-month recovery period. The offspring were weighed and measured for 8 weeks postnatally. There was a significant reduction in mean litter size of the female rats mated with the male rats directly after the nitrous oxide exposure period. The offspring from the female rats mated with the males directly after the exposure period were significantly smaller in size than the control group. These results show a reversible reduction in male Wistar rat fertility, after exposure to 0.5% nitrous oxide in air (v/v), as well as a postnatal growth depression.