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The insulin proreceptor is cleaved by limited proteolysis post-translationally at an Arg-Lys-Arg-Arg site to generate its mature alpha- and beta-subunit form. An 35S-labelled insulin proreceptor substrate preparation and a 15-mer peptide substrate that mimics the amino acid sequence around and including the insulin proreceptor processing site (IRP-peptide) has revealed an endopeptidase activity that catalyses insulin proreceptor cleavage in a rat liver subcellular fraction. Under optimal conditions, normal 35S-labelled insulin proreceptor substrate processing by this fraction was quantitative. This fraction was not able to process an 35S-labelled insulin proreceptor variant substrate (where the Arg-1 of the tetrabasic cleavage site had been replaced by Ala-1), similarly to previous in vivo observations, suggesting that this endopeptidase activity has physiological relevance. Biochemical characterization of the insulin proreceptor/IRP-peptide processing revealed this rat liver endopeptidase activity to have a broad pH range (> 70% maximal activity between pH 5.5 and 10.0) and a pH optimum of pH 8-10. It was Ca(2+)-dependent activity, maximally active between 0.5 and 5 mM Ca2+ and half-maximally activated between 50 and 90 microM Ca2+. Endoproteolytic activity was not inhibited by group-specific inhibitors of serine-, cysteinyl or aspartyl proteinases or by 1,10-phenanthroline; however, EDTA and 1,2-cyclohexanediaminetetraacetic acid did inhibit the activity, but this was accounted for by Ca2+ chelation. The IRP-peptide substrate assay enabled measurement of an apparent Km of 22 microM and a Vmax of 18.6 pmol/min for this endopeptidase activity. These biochemical characteristics suggest that insulin proreceptor processing endopeptidase activity to be a legitimate member of the Kex2-related proprotein convertase family. Immunoblotting detected furin and PACE4 proteins (both members of this family) to be present in the rat liver subcellular fraction containing insulin proreceptor processing activity. Since the biochemical characteristics of the insulin proreceptor processing endopeptidase activity mostly resembled those of furin activity, it is likely that insulin proreceptor proteolytic maturation can be catalysed by furin in the liver.

Some patients found to have clonal panmyelopathies develop an acquired defect of haemoglobin synthesis clinically similar to haemoglobin H disease. A 58 year-old male diagnosed of simple refractory anaemia developed microcytosis and hypochromia. At the same time, his myelodysplastic syndrome became a refractory anaemia with excess of blasts. 33% of the red blood cells had "golf ball" inclusions after incubation with brilliant cresyl blue. Cellulose acetate electrophoresis revealed an haemoglobin H band. The globin chain synthesis alpha/beta ratio was 0.69. The molecular analysis demonstrated the integrity of both alpha genes in each chromosome. There were no familiar antecedent of haemoglobinopathy.

Pancreatic beta-cell dysfunction is a characteristic of non-insulin-dependent diabetes mellitus (NIDDM). An aspect of this dysfunction is that an increased proportion of proinsulin is secreted, but an actual beta-cell defect that leads to hyperproinsulinemia is unknown. Nevertheless, an impairment in beta-cell proinsulin conversion mechanism has been suggested as the most likely cause. Insulin is produced from its precursor molecule, proinsulin, by limited proteolytic cleavage at two dibasic sequences (Arg31, Arg32 and Lys64, Arg65). Two endopeptidase activities catalyze this cleavage: PC2 and PC3. PC2 endopeptidase cleaves predominately at Lys64, Arg65, and PC3 endopeptidase cleaves at Arg31, Arg32. The recent identification and characterization of these endopeptidases has enabled a better understanding of the human proinsulin-processing mechanism. In particular, experimental evidence suggests that the majority of human proinsulin processing is sequential. PC3 cleaves proinsulin first to generate a proinsulin conversion intermediate that is the preferred substrate of PC2. Both PC2 and PC3 activities are influenced by Ca2+ and pH, but the more stringent Ca2+ and pH requirements of PC3 suggest it as the most likely enzyme to regulate proinsulin conversion, as well as initiate it. When an increased demand is placed on the proinsulin-processing mechanism by a glucose-stimulated increase in proinsulin biosynthesis, there is a coordinate increase in PC3 biosynthesis (but not in PC2). This supports PC3 as the key endopeptidase that regulates proinsulin processing. In this perspective, the current concepts of the enzymology and regulation of proinsulin conversion at a molecular level are reviewed.(ABSTRACT TRUNCATED AT 250 WORDS)

We have searched for the contribution of the kidney to the catabolism of glucagon-like peptide-1 (7-36)amide or tGLP-1 by analyzing the disappearance of the [125I]tGLP-1 both in vivo, from the plasma of bilaterally nephrectomized (BNX), ureteral-ligated (BUL) and normal rats and in vitro from the perfusate of an isolated rat kidney system. Also, we have measured the degradation of the peptide by the isolated renal tubules. Results from in vivo studies demonstrated that the disappearance half-time (t1/2) of [125I]tGLP-1 was significantly lower in the control than in BUL or BNX rats with the metabolic clearance rate (MCR) being higher in the control than in BUL and BNX group; no difference was found for both parameters between BUL and BNX rats. The urinary excretion of the peptide was negligible. The data from the isolated kidney experiments showed a disappearance of the peptide, which was not due to its spontaneous degradation nor to enzymes released from the kidney to the perfusate. Degradation of the peptide also occurred in the presence of isolated tubules. It was dependent upon the concentration of tubules. This could possibly be due to the action of the brush border-associated peptidases. In conclusion, our results demonstrate that, in the rat, the kidney removes the exogenous tGLP-1 from the peripheral circulation, by a mechanism that involves glomerular filtration and tubular catabolism.

From October 1984 to March 1992, 21 patients of Hospital Nacional Guillermo Almenara Irigoyen-IPSS, Lima, Perú, with esophageal achalasia were treated with pneumatic dilatation using a 3.5 cm diameter Rider-Moeller balloon. The mean age was 40.5 years (range: 24-54). Six were men and 15 women. The mean time with dysphagia previous to treatment was 5.3 years. A total of 29 sessions were performed, 1.38 sessions per patient. The follow-up of the first 10 patients was carried for a mean time of 48.3 months (range:6-91). A satisfactory response to treatment was obtained in 8 patients (80%). Two patients (20%) relapsed after 2 and 3 treatment sessions needing surgery. One patient suffered a esophageal perforation recovering after surgical treatment. We conclude that pneumatic dilatation with Rider-Moeller balloon is a safe and not difficult medical procedure for esophagus achalasia.

The biosynthesis of proinsulin is specifically stimulated by glucose in the pancreatic beta-cell, and this, in turn, places an increased demand on the mechanism for proinsulin to insulin conversion. Proteolytic proinsulin processing is catalyzed by two endopeptidases putatively identified as the subtilisin-related PC2 and PC3 convertases (Bennett, D. L., Bailyes, E. M., Nielson, E., Guest, P. C., Rutherford, N. G., Arden, S. D., and Hutton, J. C. (1992) J. Biol. Chem. 267, 15229-15236; Bailyes, E. M., Shennan, K. I. J., Seal, A. J., Smeekens, S. P., Steiner, D. F., Hutton, J. C., and Docherty, K. (1992) Biochem. J. 285, 391-394). In this study, we demonstrate in isolated rat pancreatic islets that the biosynthesis of PC3 was specifically stimulated by glucose relatively parallel to that of proinsulin. In contrast, however, PC2 biosynthesis was not glucose-regulated. The stimulation of PC3 and proinsulin biosynthesis was observed above a threshold of 4 mM glucose and reached a maximum (about 7-10-fold) above 10 mM glucose concentrations. Glucose stimulation for PC3 and proinsulin biosynthesis was rapid (occurring within 20 min and reaching a maximum by 60 min) and was not affected by the additional presence of actinomycin D, suggesting regulation predominantly at the translational level. Moreover, the intracellular signals for glucose-stimulated PC3 and proinsulin biosynthesis appeared to be similar, requiring the metabolism of glucose. PC3 has been implicated as the key endopeptidase in proinsulin to insulin conversion, in that it is the enzyme which preferentially initiates the process (Rhodes, C. J., Lincoln, B., and Shoelson, S. E. (1992) J. Biol. Chem. 267, 22719-22727). We suggest that co-ordinate stimulation of PC3 biosynthesis, along with that of its proinsulin substrate, elucidates an additional control point by which the mechanism of proprotein processing might be regulated.

The family is one of the major socialization agencies for children. Parents are one of the most important models from whom the child and adolescent acquire a wide variety of behavior patterns, attitudes, values, and norms. The aim of this study was to determine the importance of factors related to family conflicts in the genesis of social maladjustment. A total of 189 young people (110 boys and 79 girls) from training schools connected with the juvenile court in Murcia (Spain) were studied. The subjects' ages ranged from 11 to 18 years (mean 13.51, SD 0.16). Our sample comprised a group of minors who experienced a high incidence of intrafamilial pathology, which was found to be a significant discriminant factor. Aggressive behavior, rules, norms, values, opinions, and attitudes toward aggressivity can be learned in the family setting.

The lipolytic effect of GLP-1(1-36)-amide, GLP-1(7-36) amide and GLP-2 [proglucagon(126-159)] has been studied in isolated rat adipocytes. Glycerol release and cyclic AMP content were measured after incubation of adipocytes with GLPs and results have been compared with those obtained in the presence of glucagon. GLP-1(7-36)-amide and GLP-1(1-36)-amide at 10(-8), 10(-7) and 10(-6) M concentrations activated glycerol release, the truncated peptide having a more potent effect. On the other hand, GLP-2 had no effect on glycerol release. Also, it has been found that 10(-6) M GLP-1(7-36)-amide increases cyclic AMP content in adipocytes and does not compete with glucagon binding. These results demonstrate that GLP-1(7-36)-amide has a lipolytic effect on isolated rat adipocytes through different receptors than glucagon.

The aim of this study was to establish the role of some personality traits, measured by psychological tests, in minors and adolescents experiencing problems in their social integration. We studied 189 subjects (110 male, 79 female) ranging in age from 11 to 18 years. All the subjects were from centers under the administration of the juvenile court of Murcia, Spain. Each subject underwent individual clinical psychological examination as well as psychometric and psychological studies. Our results show a statistically significant association between the scores on some of the tests used and variables related to familial and social maladjustment. These personality traits define a set of individuals with a characteristic profile, for whom unfavorable biographical events have made integration in, and adaptation to, the established social milieu difficult.

The coagulation abnormalities in 20 cases of acute promyelocytic leukemia (APL) treated at a single institution were reviewed. A remarkably uniform picture of defibrination and increased FDPs with well-preserved levels of other coagulation factors including AT-III was seen. Our data, together with those available in the literature, do not support DIC as the underlying mechanism of bleeding but seem rather to point to increased proteolysis as the cause.

The renal catabolism of [125I]glucagon-like peptide 1 (GLP-1) and [125I]glucagon-like peptide 2 (GLP-2) has been studied both in vivo, by the disappearance of these peptides from the plasma of bilaterally nephrectomized (BNX), ureteral-ligated (BUL) or normal rats, and in vitro, analyzing their catabolism by the isolated, perfused rat kidney. Results from in vivo studies demonstrated that half-disappearance time for both peptides was lower in controls than in BUL rats, and this value in BUL rats was not significantly different from that in BNX rats. In addition, metabolic clearance rate of GLP-1 was higher in control rats than in the other two groups of animals. Urinary clearance rate of both peptides was negligible. In isolated kidney experiments, values for organ clearance of both [125I]GLP-1 and [125I]GLP-2 were similar to those of inulin clearance, which represents the glomerular filtration rate. Urinary clearance of trichloroacetic acid precipitable radioactivity represented less than 1% of total clearance. In conclusion, these results demonstrate a significant role for the kidney in the plasma removal of [125I]GLP-1 and [125I]GLP-2 by a mechanism that involves glomerular filtration and tubular catabolism.

Sixty patients diagnosed of acute myeloblastic leukaemia (AML) on whom a chromosomal study was performed at diagnosis were evaluated. Their median age was 43 years (range: 8-89). Normal karyotype was present in 59% of the cases, it being abnormal in the remaining 41%. Chromosomal alterations appeared in 64% of the patients with M-4 morphology, in 43% of M-5, 40% of those with M-1, 33% of the M-2, and in 14% of the cases with M-3 morphology. The two patients with M-6 had abnormal karyotype. No correlations could be established between normal or abnormal karyotype and the clinical or laboratory data. Structural alterations were commonest amongst the patients with abnormal karyotype. Such alterations included t(8; 21), t(9; 22); t(7; 22), del 11q23, inv 16 (p13;q22), plus multiple major abnormalities in the M-6 patients. A strikingly low incidence of t(15; 17) was found in the acute promyelocytic leukaemia cases. Two chromosomal alterations not previously reported in AML were found in this series, namely, inv 13 (p11;q32) and t(21;1) (q22;q22). The finding of an abnormal karyotype had no unfavourable influence on the complete remission (CR) rate, which reached 65% of the patients with normal karyotype and 81% of those with abnormal karyotype. No differences were found in the duration of CR in this connection (80 and 77 weeks, respectively). Despite the lack of definite prognostic significance, the study of the karyotype appears as an important information in the diagnosis of AML.

A study is made in the Intensive Care Unit of "José L. Miranda" Provincial Pediatric Teaching Hospital in Santa Clara in order to know the sequence with which the father occupies the place of the mother in the care of hospitalized children. With this objective, 54 male companions are surveyed in the first trimester of 1987. The prevailing occupational profile was that of worker. A higher number of the respondents were between 17 and 25 years of age. The school level of secondary school prevailed among patient companions. Most of them reported no economic inconveniences during the child's disease. The desire to remain at the bedside and the inability of the mother to do so were the major reasons for their stay. The advantages recognized by the nursing personnel in male companions are made known.

Effects of aescine and aesculine, active principles of the horsechestnut, on urinary excretion of water and electrolytes, were investigated in saline loaded rats. Results indicate that aesculin shows a moderated diuretic activity, increasing significantly the renal loss of sodium, chloride and potassium. Nevertheless, only the highest dose of aescine caused the same degree of minease in saluresis with aesculin, where a doses-response relationship was observed.

Ca++ was shown to be indispensable for the normal growth of cultures of Plasmodium falciparum. Inclusion of ethyleneglycolbis (beta-amino-ethylether) N,N'-tetra-acetic acid (EGTA) caused blocking of the asexual cell cycle of the parasite in two sites, the first blockage occurring between 20 and 26 hours after invasion of the erythrocyte. It proved to be irreversible by additions of Mg++ or Ca++, and to lead to morphologically abnormal parasites arrested in the mature trophozoite stage of the cycle. The second site of inhibition was probably one of the steps in the process of invasion of the erythrocyte by the merozoite. When 1 mM EGTA was added 24--30 hours after the culture was synchronized the cell cycle of the parasite continued without any interference in the normal maturation until the development of schizonts and release of merozoites into the medium. However, reinvasion of fresh erythrocytes by these merozoites was impeded. The inhibition of reinvasion caused by EGTA was overcome by the addition of an excess of Ca++ but not by an excess of Mg++. After the addition of Ca++ to cultures blocked just before the invasion phase as schizonts, the merozoites were again rendered fully infective and the rate of invasion was similar to that in an untreated control culture. Implications of the effects of Ca++ depletion on the asexual cell cycle and possible applications of EGTA as a reversible inhibitor of the invasion process are discussed.

Red cell 2.3-diphosphoglycerate (2.3-DPG) response to anaemia is evaluated in 83 patients with different types of heterozygous thalassaemias, and 40 patients with chronic ferropenic anaemia and 120 healthy subjects are used as control groups. In heterozygous beta, beta delta, and alpha thalassaemic patients the 2.3 DPG concentration is appropriate for the degree of anaemia present.