Biodegradation of Polystyrene by Galleria mellonella: Identification of Potential Enzymes Involved in the Degradative Pathway

Galleria mellonella is a lepidopteran whose larval stage has shown the ability to degrade polystyrene (PS), one of the most recalcitrant plastics to biodegradation. In the present study, we fed G. mellonella larvae with PS for 54 days and determined candidate enzymes for its degradation. We first confirmed the biodegradation of PS by Fourier transform infrared spectroscopy- Attenuated total reflectance (FTIR-ATR) and then identified candidate enzymes in the larval gut by proteomic analysis using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Two of these proteins have structural similarities to the styrene-degrading enzymes described so far. In addition, potential hydrolases, isomerases, dehydrogenases, and oxidases were identified that show little similarity to the bacterial enzymes that degrade styrene. However, their response to a diet based solely on polystyrene makes them interesting candidates as a potential new group of polystyrene-metabolizing enzymes in eukaryotes.

Multidisciplinary Treatment of Deep Non-Carious Cervical Lesion With a CAD/CAM Chairside Restoration in Combination With Periodontal Surgery: A 60-Month Follow-Up Technique Report

INTRODUCTION

Restoring function and esthetics are essential aspects of periodontology and restorative dentistry. Depending on their extension and the tissues involved, the treatment of non-carious cervical lesions (NCCLs) associated with gingival recessions may require a multidisciplinary approach, and different periodontal and restorative techniques have been described.

CASE PRESENTATION

This case report presents an innovative approach to treat a deep NCCL combined with a gingival recession in a canine region of a female patient. A Computer Aided Design - Computer Aided Manufacturing (CAD/CAM) chairside ceramic restoration in combination with mucogingival surgery procedures is described. A comprehensive analysis of the selected approach and its clinical implications is presented based on a 60-month follow-up. Conclusions After 60-month follow-up, clinical condition maintained stable, and a successful esthetic outcome was accomplished. Complete root coverage was achieved and kept throughout the whole period of tracing.

Dry eye is matched by increased intrasubject variability in tear osmolarity as confirmed by machine learning approach

OBJECTIVE

Because of high variability, tear film osmolarity measures have been questioned in dry eye assessment. Understanding the origin of such variability would aid data interpretation. This study aims to evaluate osmolarity variability in a clinical setting.

MATERIAL AND METHODS

Twenty dry eyes and 20 control patients were evaluated. Three consecutive osmolarity measurements per eye at 5min intervals were obtained. Variability was represented by the difference between both extreme readings per eye. Machine learning techniques were used to quantify discrimination capacity of tear osmolarity for dry eye.

RESULTS

Mean osmolarities in the control and dry eye groups were 295.1±7.3mOsm/L and 300.6±11.2mOsm/L, respectively (P=.004). Osmolarity variabilities were 7.5±3.6mOsm/L and 16.7±11.9mOsm/L, for the control and dry eye groups, respectively (P<.001). Based on osmolarity, a logistic classifier showed an 85% classification accuracy.

CONCLUSIONS

In the clinical setting, both mean osmolarity and osmolarity variability in the dry eye group were significantly higher than in the control group. Machine learning techniques showed good classification accuracy. It is concluded that higher variability of tear osmolarity is a dry eye feature.

On the prediction of Hodgkin lymphoma treatment response

PURPOSE

The cure rate in Hodgkin lymphoma is high, but the response along with treatment is still unpredictable and highly variable among patients. Detecting those patients who do not respond to treatment at early stages could bring improvements in their treatment. This research tries to identify the main biological prognostic variables currently gathered at diagnosis and design a simple machine learning methodology to help physicians improve the treatment response assessment.

METHODS

We carried out a retrospective analysis of the response to treatment of a cohort of 263 Caucasians who were diagnosed with Hodgkin lymphoma in Asturias (Spain). For that purpose, we used a list of 35 clinical and biological variables that are currently measured at diagnosis before any treatment begins. To establish the list of most discriminatory prognostic variables for treatment response, we designed a machine learning approach based on two different feature selection methods (Fisher's ratio and maximum percentile distance) and backwards recursive feature elimination using a nearest-neighbor classifier (k-NN). The weights of the k-NN classifier were optimized using different terms of the confusion matrix (true- and false-positive rates) to minimize risk in the decisions.

RESULTS AND CONCLUSIONS

We found that the optimum strategy to predict treatment response in Hodgkin lymphoma consists in solving two different binary classification problems, discriminating first if the patient is in progressive disease; if not, then discerning among complete and partial remission. Serum ferritin turned to be the most discriminatory variable in predicting treatment response, followed by alanine aminotransferase and alkaline phosphatase. The importance of these prognostic variables suggests a close relationship between inflammation, iron overload, liver damage and the extension of the disease.

[Experience of the moving day of a general hospital and effect on clinical activity]

OBJECTIVES

To describe the moving day of a general hospital and to analyze the impact on clinical activity in the first few months after the move.

METHODS

We describe the process of patient transfer and analyze the impact on activity of moving a regional general hospital in Catalonia (Spain) to a new building. Activity was compared in two periods: the first 3 months after the move (period 2) and the same 3 months in the previous year (period 1).

RESULTS

We moved 37 patients without incidents. A total of 18,786 patients were admitted to the emergency room in period 1 and 21,266 were admitted in period 2 (+13.2%). The number of admissions from the emergency room vs elective admissions was 1,314/803 in period 1 and 1,427/979 in period 2 (+8.59%/ +21.91%). The number of outpatient visits in period 1 was 32,116 and 30,777 in period 2 (-4.16%).

CONCLUSIONS

Proper planning and coordination allowed the hospital to be moved without incidents and without decreasing activity.

The balance between proinsulin biosynthesis and insulin secretion: where can imbalance lead?

Insulin is stored in pancreatic beta-cells in beta-granules. Whenever insulin is secreted in response to a nutrient secretagogue, there is a complementary increase in proinsulin biosynthesis to replenish intracellular insulin stores. This specific nutrient regulation of proinsulin biosynthesis is predominately regulated at the translational level. Recently, a highly conserved cis-element in the 5'-untranslated region (UTR) of preproinsulin mRNA, named ppIGE, has been identified that is required for specific translational regulation of proinsulin biosynthesis. This ppIGE is also found in the 5'-UTR of certain other translationally regulated beta-granule protein mRNAs, including the proinsulin processing endopeptidases, PC1/3 and PC2. This provides a mechanism whereby proinsulin processing is adaptable to changes in proinsulin biosynthesis. However, relatively few beta-granules undergo secretion, with most remaining in the storage pool for approximately 5 days. Aged beta-granules are retired by intracellular degradation mechanisms, either via crinophagy and/or autophagy, as another long-term means of maintaining beta-granule stores at optimal levels. When a disconnection between insulin production and secretion arises, as may occur in type 2 diabetes, autophagy further increases to maintain beta-granule numbers. However, if this increased autophagy becomes chronic, autophagia-mediated cell death occurs that could then contribute to beta-cell loss in type 2 diabetes.

Arbuscular mycorrhizas in coastal sand dunes of the Paraguaná Peninsula, Venezuela

Arbuscular mycorrhizal colonization was measured in the most abundant plant species of the Paraguaná Peninsula, northwestern Venezuela. These plant species included: Acacia tortuosa, Argusia gnaphalodes, Croton punctatus, Croton rhamnifolius, Egletes prostrata, Melochia tomentosa, Panicum vaginatum, Scaevola plumieri, Sporobolus virginicus, Suriana maritima, Leptothrium rigidum, and Fimbristylis cymosa. Mycorrhizal colonization was assessed using the Trouvelot et al. (1986) method that allows for simultaneous evaluation of frequency of colonization (%F), intensity of colonization (%M), and the proportion of arbuscules (%A) and vesicles (%V) present in the roots. Average frequency of colonization was 69%. The highest frequency of colonization was around 92% in C. rhamnifolius and A. tortuosa; in the other species, it varied from 49 to 86%. L. rigidum and F. cymosa were considered nonmycorrhizal because its colonization was very scarce and at all times appeared without arbuscules. Average intensity of colonization was 7%. The highest intensity of colonization was 18% in C. rhamnifolius. In the other species, it varied from 3 to 15%. Paspalum vaginatum, A. gnaphalodes, M. tomentosa, and S. maritima had their fungal structures tightly packed in modified little ovoid roots. In general, frequency of AM colonization was high and similar to those reported for other tropical ecosystems, whereas the intensity of AM colonization was low and similar to values obtained in analogous studies in disturbed ecosystems.

Self-Expanding Metallic Ureteral Stents for Treatment of Ureteral Stenosis After Kidney Transplantation

The incidence of post-renal transplantation ureteral stenosis ranges from 2%-12%. Because the role of self-expanding ureteral metallic stents for its treatment has been scarcely reported, the aim of this study was to evaluate the efficacy of Nitinol stents. Eleven ureteral stenoses in patients with chronic graft dysfunction (8 cases) or high surgical risk (3 cases) were treated by antegrade percutaneous implantation of Nitinol stents through a nephrostomy tract. The mean follow-up period was 48 +/- 7 months (range, 3-85 months). The patency rate at the moment of return to dialysis, death, or last check-up was 73% (8/11). Three patients (27%) developed stent occlusion. Two patients were treated using a trans-stent double-J catheter and 1 patient using stent removal and pyeloureterostomy using the native ureter. The mean percentage decrease in serum creatinine (Cr) level after stent implantation was 41% (range, 14%-63%). Nitinol ureteral stent implantation is an effective alternative for the treatment of ureteral stenosis in patients with chronic graft dysfunction or high surgical risk.

Wisconsin and Celsior solutions in renal preservation: a comparative preliminary study

The aim of this study was to evaluate the efficacy of the Celsior (C) solution for flushing and cold storage of cadaveric renal allografts. Among 177 cadaveric renal allografts harvested and transplanted in our unit, 138 were preserved with the University of Wisconsin (W) solution and 39 with the C solution. The mean age of the recipients was 48.1 +/- 13.5 years, including 107 men and 70 women. The immunosuppressive regimens were tacrolimus-based (n = 118) or cyclosporine-based (n = 59). Grafts perfused with W solution were obtained from older donors than those perfused with C solution (42.3 +/- 16.9 vs 38.1 +/- 12.5 years; P = .017) and had been transplanted to older recipients (49.5 +/- 14.4 vs 43.3 +/- 13.0 years; P = .017). The prevalence of delayed graft function (DGF) was similar in the 2 groups (39.1% in the W group vs 23.7% in the C group; P = .097), as well as the incidence of primary nonfunction grafts (5.8% vs 2.7%; P = .427). The serum creatinine value at 1 month was significantly higher among grafts preserved with W versus solution (1.9 +/- 0.9 vs 1.5 +/- 0.5 mg/dL; P = .000) as well as at 12 months (1.63 +/- 0.5 vs 1.35 +/- 0.4 mg/dL; P = .003). There were no differences in graft survival at 12 months (97% C group vs 88% W group; P = .069). Our results showed that C solution was equivalent to W solution with respect to DGF and primary function of kidneys. The differences in renal function may have been due to differences in donor and recipient ages.

[Therapy with interferon plus ribavirin in hemodialysis patient with PCR-positive viral hepatitis C]

Traditionally, the treatment of viral hepatitis C (positive Polymerase Chain Reaction -PCR-) was with Interferon. A combination of Interferon plus Ribavirin has been producing better results in last years. Currently, Ribavirin is not indicated for patients with Chronic Kidney Disease because of a high risk of severe anaemia. In a few cases, this treatment is producing good results with previous dose adjustment. We show a case of a 28-year-old man with Chronic Kidney Disease on treatment with periodical hemodialysis and chronic hepatopathy HCV Positive RNA HCV (> 1,000,000 copies/ml) and persistent transaminase elevation. Before kidney transplantation, we decided to use Interferon (3,000,000 IU/48 hours) and Ribavirin (200 mg/24 hours) treatment. After 15 days, we saw normal transaminase values and HCV RNA was negative. The patient required temporary suspension of Ribavirin and two red blood cell transfusions due to severe anaemia. Ribavirin was reintroduced 200 mg/48 h posthemodialysis. The patient did not present any complication again, and could be treated for 14 months. After next 11 months of evolution the patient has normal rates of liver function and negative HCV RNA values.

[Ionic dialysance to control the dose of dialysis. One year experience]

The Diascan equipment (Hospal) measures ionic dialysane which it derives the K and the Kt. If we divide the Kt obtained with Diascan between the Kt/V obtained by a simplified formula, it result a value of V for every patient. Entering this V in the Diascan software we can obtain a Kt/V (Diascan Kt/V), similar in theory to the simplified Kt/V. In the year 2002 we have controlled the delivered dialysis in our unit with the Diascan Kt/V. The aim of the present study was to study the agreement between de Diascan Kt/V and the Lowrie Kt/V. During the year 2002, 63 patients have been dialyzed in monitors with Diascan equipment. We calculated the V of each patient by dividing the Kt Diascan between the Lowrie Kt/V in the same dialysis session. The mea of the two consecutive measurements was considered the V value. Throughout the year 2002, 7 agreement studies were realized. The inter-method variability was assessed by the relative difference (absolute difference Diascan Kt/V-Lowrie Kt/V, divided by the average of both tests). A good agreement was considered when the relative difference was equal or lower than 10%. In the 7 agreement studies realized, the mean of the relative difference oscilled between 5.2 and 6.6%, and the percentage of patients with a relative difference equal or lower than 10% oscilled between 83 and 91%. During a month, the Diascan Kt/V was controlled in all dialysis sessions in 41 patients (554 sessions in total). Failure in the lecture of Kt/V Diascan was observed in 41 sessions (7%). A Diascan Kt/V greater than 1 (the minimum delivered dialysis considered in our unit) was obtained in 93% of the valid sessions. 38 of 41 patients had a mean monthly Diascan Kt/V greater than 1. The coefficient of variability of any patient oscilled between 2.1 and 12.4% (mean 5.1%). Diascan Kt/V is good procedure for the monitoring the delivered dialysis without blood sampling or any additional costs.

Characterization of the bactericidal activity of the natural diterpene kaurenoic acid

Kaurenoic acid is a diterpene with selective antibacterial activity against Gram-positive bacteria. The compound is bacteriolytic for Bacillus cereus. This activity was only partially affected by the composition and pH of the culture medium. Loss of the ability to retain the Gram stain and morphological alterations were produced in B. cereus cells exposed to kaurenoic acid. On the other hand, LPS mutants of Salmonella typhi were resistant to the compound, but spheroplasts of Escherichia coli became more sensitive to kaurenoic acid.

[Rheumatoid arthritis among mapuche aborigines. A 16 years experience in the IX Region of the Chile]

BACKGROUND

Mapuche, Chilean natives, represent approximately 9.8% of Chilean population and in the IX region of the country, they account for 18.4% of population over 15 years old. They preserve some socio-cultural characteristics that make them different to the rest of the population.

AIM

To describe the epidemiological characteristics rheumatoid arthritis among Mapuche natives.

SUBJECTS AND METHODS

Retrospective review of patients of Mapuche origin with rheumatoid arthritis, seen at Temuco Hospital between 1980 and 1996.

RESULTS

Among 308 cases gathered, only 106 (93 women, aged 55 +/- 10 years old) complied with 1987 American College of Rheumatology (ACR) criteria for rheumatoid arthritis. The disease began between 29 and 52 years old in 73% of patients and the mean delay in diagnosis was 4.4 years. At diagnosis, 99% had symmetric poliarthritis, 28.3% had either fatigue, fever or weight loss, and 46.9% were in class III or in class IV of ACR-1991. Fifty three percent of patients developed Sicca syndrome, 36% developed nodules, 23% developed Raynaud phenomenon, 11% developed pulmonary involvement, 7% developed vasculitis, 5% developed neurological manifestations and 19% developed ophthalmologic involvement. Rheumatoid factor was positive in 78% and 73% had erosions. HLA DR4 was (+) in 60% of 30 patients. Thirty percent required 3 or more disease modifying drugs and prednisone over 10 mg/day. There was no correlation between functional capacity and several other features of the disease.

CONCLUSIONS

Mapuche rheumatoid arthritis patients are detected late and have a poor functional capacity at the time of diagnosis. They also have a higher proportion of extraarticular manifestations, more erosions and require more aggressive treatments.

Insulin/insulin-like growth factor-I hybrid receptors with high affinity for insulin are developmentally regulated during neurogenesis

The extensive colocalization of insulin receptor (IR) and insulin-like growth factor-I receptor (IGFR) messenger RNAs during central nervous system development, together with the effects of insulin and IGF-I in neurogenesis, raises the question of how stage- and factor-specific signaling occurs. Thus, it is necessary to characterize the receptor proteins present in vivo to start addressing this issue. Here we have studied the chick embryonic neuroretina at day 6 (E6), when it is predominantly proliferative, and at E12, when neuronal differentiation is advanced. Developmentally regulated high-affinity binding sites for both insulin and IGF-I were detected at E6 and E12. In proliferative neuroretina, typical IGFR with the highest affinity for IGF-I coexisted with separate atypical insulin binding sites, which had similar high affinity for insulin and IGF-I. Immunoprecipitation of ligand-cross-linked receptors with specific antibodies for the IR alpha-subunit, the IR beta-subunit, or the IGFR beta-subunit demonstrated the presence of IR/IGFR hybrids. They were more abundant in E6 than in E12 retina. These hybrid receptors bound most of radiolabeled insulin, but little radiolabeled IGF-I, at tracer concentrations. At E12, the specificity of the insulin binding sites changed, and it was closer to that found with IR in liver, where hybrids were undetectable. The basal autophosphorylation level of these atypical hybrid receptors was high, although insulin and, even more so, IGF-I modestly increased the phosphorylation of two IR beta-subunits of 95 and 105 kDa. The high-affinity/low-discriminative IR/IGFR hybrids predominantly found in a proliferative stage of neurogenesis can mediate the effects of proinsulin and insulin, previously demonstrated in organoculture at this stage. More importantly, this hybrid receptor may be physiologically relevant for the action of the locally produced proinsulin found in early neurogenesis.

Synthesis and differentially regulated processing of proinsulin in developing chick pancreas, liver and neuroretina

Regulated preproinsulin gene expression in nonpancreatic tissues during development has been demonstrated in rodents, Xenopus and chicken. Little is known, however, about the synthesis and processing of the primary protein product, proinsulin, in comparison with these events in pancreas. Using specific antisera and immunocytochemistry, immunoblot and HPLC criteria, we characterize the differential processing of proinsulin in developing neuroretina, liver and pancreas. The chick embryo pancreas expresses the convertase PC2, and largely processes proinsulin to insulin. In contrast, little or no mature PC2 is present in embryonic liver and neuroretina and the (pro)insulin immunoactivity identified is predominantly proinsulin.

(Pro)insulin and insulin-like growth factor I complementary expression and roles in early development

Evidence that the insulin-like growth factors play a role in embryonic as well as postnatal growth and central nervous system development has accumulated recently from studies using knock-out mice models. However, no effects of IGF-I and II have been demonstrated prior to organogenesis in these studies. We summarize here results supporting the role of insulin (or its precursor proinsulin) in vertebrate development prior to the expression of IGFs. (Pro)insulin mRNA is expressed in the chick embryo during neurulation and early organogenesis and its inhibition by antisense oligodeoxynucleotides increase apoptosis. In another system, proliferative neuroretina, (pro)insulin expression predominates over IGF-I expression. Modulation of apoptosis by (pro)insulin in retina may be largely responsible for the observed stimulation of DNA synthesis and neuronal differentiation. These effects are elicited as well by IGF-I, expressed later in neuroretina. Thus, these polypeptides have complementary expression in early embryos which suggests coordinated actions during development.

Protein(s) from the Gram-Positive Bacterium Clavibacter michiganensis subsp. michiganensis Induces a Hypersensitive Response in Plants

ABSTRACT The gram-positive tomato pathogen Clavibacter michiganensis subsp. michiganensis induced a local necrotic response on four-o'clock (Mirabilis jalapa) and tobacco (Nicotiana tabacum) plants. This necrosis response was characteristic of the hypersensitive response (HR). The cell-free culture supernatant from strain CMM623 also induced a necrosis that was phenotypically similar to that induced by the bacteria. Inhibitors of plant metabolism suppressed the necrotic reaction of both M. jalapa and tobacco. The HR-inducing activity present in the supernatant was heat stable, sensitive to proteases, and had an apparent molecular mass in the range of 35 to 50 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The properties observed for the necrosis-inducing activity resembled harpin and PopA described from gram-negative phytopathogenic bacteria.

Role of prepancreatic (pro)insulin and the insulin receptor in prevention of embryonic apoptosis

The characterization of (pro)insulin as an early embryonic growth factor requires demonstration of its expression and cellular effects in vivo. By in situ hybridization, we found widespread preproinsulin transcripts in the chick embryo throughout gastrulation and neurulation, before the beginning of preproinsulin-like growth factor I expression and pancreatic organogenesis. To analyze the prepancreatic (pro)insulin effect on apoptotic cell death, we treated embryos with antisense oligodeoxynucleotides in ovo and in vitro. The specific effect of two preproinsulin messenger RNA (mRNA) antisense oligodeoxynucleotides was confirmed by the decrease in a biosynthetically labeled protein immunoprecipitated with antiinsulin Igs. Insulin receptor mRNA antisense oligodeoxynucleotide applied in ovo increased by 2.7-fold the level of apoptosis in the 1.5-day embryo (neurulation) compared with that in its random sequence control. In a whole embryo culture, apoptosis increased by 25-35% with the addition of preproinsulin or insulin receptor mRNAs antisense oligodeoxynucleotides, respectively, whereas it decreased by 64% after 10 h in the presence of 10(-8) M chicken insulin. Exogenous insulin also rescued the death induced by preproinsulin antisense oligonucleotides. These findings provide evidence for an autocrine/paracrine role ofpreproinsulin gene products acting through the insulin receptor in the control of cell survival/death during early embryonic development.

Effects of short-term zinc supplementation on cellular immunity, respiratory symptoms, and growth of malnourished Equadorian children

OBJECTIVE

To assess the effect of zinc supplementation on respiratory tract disease, immunity and growth in malnourished children.

DESIGN

A randomized double-blind placebo-controlled trial.

SETTING

A day-care center in Quito, Ecuador.

SUBJECTS

Fifty children (12-59 months old) recruited by height-for-age and weight-for-age deficit.

INTERVENTIONS

Twenty-five children (supplemented, S group) received 10 mg/day of zinc as zinc sulfate, and 25 (nonsupplemented, NS group) received a placebo during 60 days. All were also observed during a 60-day postsupplementation period. Two children of the S group dropped out. Daily the clinical presence of cough, respiratory tract secretions, and fever, was recorded. On days 0,60 and 120, the cutaneous delayed-type hypersensitivity (DTH) to multiple antigens, and anthropometric parameters were assessed. On days 0 and 60 serum zinc levels were also measured.

RESULTS

On day 60, DTH was significantly larger (20.8 +/- 7.1 vs 16.1 +/- 9.7 mm), and serum zinc levels were significantly higher (118.6 +/- 47.1 vs 83.1 +/- 24.5 micrograms/dl) in the S group than in the NS group (P <0.05 for each). The incidence of fever [relative risk (RR): 0.30, c.i. = 0.08- 0.95, P =0.02], cough (RR): 0.52, c.i. = 0.32-0.84, P = 0.004) and upper respiratory tract secretions (RR):0.72, c.i. = 0.59-0.88, P = 0.001) was lower in the S group than in the NS group at day 60. At the end of the postsupplementation observation period (day 120), the incidence of fever and upper respiratory tract secretions was the same in both the S and NS groups. The incidence of cough was higher at day 120 in the S group than in the NS group (RR): 2.28, c.i. = 1.37-3.83, P = 0.001).

CONCLUSIONS

This study supports a role for zinc in immunity, and immunity to respiratory infections, while pointing out the need for larger studies.

Autocrine/paracrine role of insulin-related growth factors in neurogenesis: local expression and effects on cell proliferation and differentiation in retina

Early neurogenesis progresses by an initial massive proliferation of neuroepithelial cells followed by a sequential differentiation of the various mature neural cell types. The regulation of these processes by growth factors is poorly understood. We intend to understand, in a well-defined biological system, the embryonic chicken retina, the role of the insulin-related growth factors in neurogenesis. We demonstrate the local presence of signaling elements together with a biological response to the factors. Neuroretina at days 6-8 of embryonic development (E6-E8) expressed proinsulin/insulin and insulin-like growth factor I (IGF-I) mRNAs as well as insulin receptor and IGF type I receptor mRNAs. In parallel with this in vivo gene expression, E5 cultured neuroretinas synthesized and released to the medium a metabolically radiolabeled immunoprecipitable insulin-related peptide. Furthermore, insulin-related immunoreactive material with a HPLC mobility close to that of proinsulin was found in the E6-E8 vitreous humor. Exogenous chicken IGF-I, human insulin, and human proinsulin added to E6 cultured neuroretinas showed relatively close potencies stimulating proliferation, as determined by [methyl-3H]thymidine incorporation, with a plateau reached at 10(-8) M. These factors also stimulated neuronal differentiation, indicated by the expression of the neuron-specific antigen G4. Thus, insulin-related growth factors, interestingly including proinsulin, are present in the developing chicken retina and appear to play an autocrine/paracrine stimulatory role in the progression of neurogenesis.

Increased secretory demand rather than a defect in the proinsulin conversion mechanism causes hyperproinsulinemia in a glucose-infusion rat model of non-insulin-dependent diabetes mellitus

Hyperproinsulinemia in non-insulin-dependent diabetes mellitus (NIDDM) is due to an increased release of proinsulin from pancreatic beta cells. This could reside in increased secretory demand placed on the beta cell by hyperglycemia or in the proinsulin conversion mechanism. In this study, biosynthesis of the proinsulin conversion enzymes (PC2, PC3, and carboxypeptidase-H [CP-H]) and proinsulin, were examined in islets isolated from 48-h infused rats with 50% (wt/vol) glucose (hyperglycemic, hyperinsulinemic, and increased pancreatic proinsulin to insulin ratio), 20% (wt/vol) glucose (normoglycemic but hyperinsulinemic), and 0.45% (wt/vol) saline (controls). A decrease in the islet content of PC2, PC3, and CP-H from hyperglycemic rats was observed. This reduction did not correlate with any deficiency in mRNA levels or biosynthesis of PC2, PC3, CP-H, or proinsulin. Furthermore, proinsulin conversion rate was comparable in islets from hyperglycemic and control rats. However, in islets from hyperglycemic rats an abnormal increased proportion of proinsulin was secreted, that was accompanied by an augmented release of PC2, PC3 and CP-H. Stimulation of the beta cell's secretory pathway by hyperglycemia, resulted in proinsulin being prematurely secreted from islets before its conversion could be completed. Thus, hyperproinsulinemia induced by chronic hyperglycemia likely results from increased beta cell secretory demand, rather than a defect in the proinsulin processing enzymes per se.

A Kex2-related endopeptidase activity present in rat liver specifically processes the insulin proreceptor

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.

[Acquired hemoglobin H disease associated with a myelodysplastic syndrome]

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.

What beta-cell defect could lead to hyperproinsulinemia in NIDDM? Some clues from recent advances made in understanding the proinsulin-processing mechanism

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)

Renal catabolism of truncated glucagon-like peptide 1

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.

The biosynthesis of the subtilisin-related proprotein convertase PC3, but no that of the PC2 convertase, is regulated by glucose in parallel to proinsulin biosynthesis in rat pancreatic islets

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.

Family violence as a determinant factor in juvenile maladjustment

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.

Personality traits in juvenile maladjustment

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.

Lipolytic action of glucagon-like peptides in isolated rat adipocytes

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.

Renal catabolism of human glucagon-like peptides 1 and 2

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.

[Chromosomal changes in 60 patients with acute myeloblastic leukemia. Frequency, characteristics and prognostic significance]

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.

Intraerythrocytic adaptation to anaemia in thalassaemia

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.

Effects of Ca++ depletion on the asexual cell cycle of Plasmodium falciparum

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.