Histological and chemical damage induced by microcystin-LR and microcystin-RR on land snail Helix aspersa tissues after acute exposure

Microcystins (MCs) are the most common cyanotoxins with more than 200 variants. Among these cyanotoxins, microcystin-LR (MC-LR) and microcystin-RR (MC-RR) are the most studied congeners due to their high toxicity and frequent occurrence in surface waters. MC-LR has been detected in more than 75% of natural cyanobacteria bloom, along with other toxic and less toxic congeners. Accumulation of several microcystins variants (MC-LR and MC-RR) has been confirmed in aquatic snails exposed naturally or in the laboratory to toxic blooms. Thus, this paper aims to compare the biochemical and histological impact of both toxic variants (microcystin-LR and microcystin-RR) and their mixed form on a bioindicator, the land snail Helix aspersa. During experiments, snails were gavaged with a single acute dose (0.5 μg/g) of purified MC-LR, MC-RR, or mixed MC-LR + MC-RR (0.25 + 0.25 μg/g). After 96 h of exposure, effects on the hepatopancreas, kidney, intestine and lungs were assessed by histological observations and analysis of oxidative stress biomarkers. The results show that a small dose of MCs variants can increase the non-enzymatic antioxidant glutathione (GSH), inhibit glutathione-s-transferase (GST) level and trigger a defense system by activating glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD). Microcystin-RR causes serious anomalies in the hepatopancreas and kidney than Microcystin-LR. The organ most affected is the kidney. The damage caused by MC-LR + MC-RR is greater than that caused by single variants.

Les polyphénols de l’extrait n-butanol de Crataegus oxyacantha : évaluation de leur pouvoir antioxydant et protecteur vis-à-vis de la toxicité de la doxorubicine

La doxorubicine (DOX) est un médicament utilisé en chimiothérapie anticancéreuse, son utilisation clinique est limitée en raison de plusieurs effets secondaires qui lui ont été attribués, comme la cardiotoxicité, la néphrotoxicité et l’hépatotoxicité. Dans la présente étude, nous avons étudié l’efficacité protectrice de l’extrait n-butanol d’une plante médicinale de la famille des Rosacées (Crataegus oxyacantha) contre la toxicité cardiaque, rénale et hépatique induite par la DOX chez des rats Wistar femelles en utilisant des paramètres biochimiques. Les rats ont été soumis à un traitement oral pré- et postphylactique concomitant par l’extrait n-butanol (100 mg/kg) contre la toxicité induite par injection intrapéritonéale unique de la DOX (150 mg/kg). La néphrotoxicité et l’hépatotoxicité ont été évaluées en mesurant les taux sériques de la créatinine, de l’urée, de l’aspartateaminotransférase (ASAT), de l’alanine-aminotransférase (ALAT) et du lactate-déshydrogénase (LDH). Le profil lipidique a également été mesuré. Le traitement par l’extrait n-butanol a considérablement diminué les taux des marqueurs sériques de la toxicité provoquée par la DOX. Les résultats biochimiques qui ont montré que la DOX a causé des dommages importants au niveau des tissus étudiés ont été inversés par l’extrait n-butanol. Les résultats suggèrent que l’extrait n-butanol atténue les lésions rénales, cardiaques et hépatiques induites par la DOX. Les tests antioxydants in vitro (piégeage du radical 2,2-diphényl-1-picrylhydrazyl et inhibition de la peroxydation lipidique) de l’extrait n-butanol ont révélé qu’il présente un pouvoir antioxydant très important ; ces activités sont fortement corrélées avec les teneurs en flavonoïdes et en phénols totaux.

Development and Initial Biogeochemical Applications of Compound-Specific Sulfur Isotope Analysis

Compound-specific isotope analysis (CSIA) has been extended to the 32S and 34S stable isotopes of sulfur (δ34S) through the combination of gas chromatography (GC) and multi-collector inductively coupled mass spectrometry (ICPMS). The molecular level resolution of sulfur-CSIA is greatly expanding the biogeochemical applications ofexisting sulfur isotope methods, particularly with respect to organic sulfur compounds. Sulfur participates in a variety of important biogeochemical and redox processes, with distinctive isotopic fractionations accompanying many of these. For example, hydrogen sulfideproduced duringmicrobial sulfate reduction can be strongly depleted in 34S (up to 66‰ in δ34S) compared to the source sulfate. An improved understanding of sulfur biogeochemistry at the molecular level will assist in the interpretation of studies of sulfur cycling associated with the modern and paleo-environments. A comparison of δ34S values between organic and inorganic sulfurspecies mayhelp to illuminate the complex role of sulfur in sedimentary organic diagenesis and the pathways of organic sulfurformation. The δ34S values of individual organic sulfur compounds from natural settings can be currently measured by GC-ICPMS with impressive accuracy, precision (<0.5‰) and sensitivity (≥20 pmol S) over a broad range of analyte volatility. The new sulfur-CSIA capability has already been used to study pathways of early diagenetic organic sulfurisation, volatile sulfur emission from the oceans, oil correlations, thermochemical sulfate reduction of petroleum hydrocarbons, and the relationship between OSCs and mineralising sulfides of large metal deposits.

[Factors influencing the development of chondrolysis in children treated for slipped capital femoral epiphysis]

INTRODUCTION

Chondrolysis is an infrequent but serious complication of the treatment of slipped capital femoral epiphysis. The objective of this study was to identify factors influencing the development of chondrolysis.

PATIENTS AND METHODS

The medical records of the patients operated on between 1989 and 2009 at the Rabat Children's Hospital for treatment of slipped capital femoral epiphysis were retrospectively evaluated. The minimum follow-up was 24 months. The risk of development of chondrolysis was correlated with various parameters. Statistical analysis was performed using a logistic regression model (binary outcome).

RESULTS

A total of 140 patients were included in this study. The average age was 13 years and 4 months. The incidence of chondrolysis was 11.4% (16 patients). Chondrolysis was significantly associated with obesity (25%, P<0.001) and with a delay in the diagnosis of slipped capital femoral epiphysis exceeding 60 days (75%, P=0.01) DISCUSSION: In this series, intra-articular pin penetration is not a risk factor for chondrolysis. The association of obesity and a diagnosis delay beyond 60 days increases the risk of occurrence of chondrolysis in children operated on for slipped capital femoral epiphysis. Chondrolysis can be prevented mainly through early diagnosis of slipped capital femoral epiphysis.

Membrane-bound oxygen reductases of the anaerobic sulfate-reducing Desulfovibrio vulgaris Hildenborough: roles in oxygen defence and electron link with periplasmic hydrogen oxidation

Cytoplasmic membranes of the strictly anaerobic sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough contain two terminal oxygen reductases, a bd quinol oxidase and a cc(b/o)o3 cytochrome oxidase (Cox). Viability assays pointed out that single Δbd, Δcox and double ΔbdΔcox deletion mutant strains were more sensitive to oxygen exposure than the WT strain, showing the involvement of these oxygen reductases in the detoxification of oxygen. The Δcox strain was slightly more sensitive than the Δbd strain, pointing to the importance of the cc(b/o)o3 cytochrome oxidase in oxygen protection. Decreased O2 reduction rates were measured in mutant cells and membranes using lactate, NADH, ubiquinol and menadiol as substrates. The affinity for oxygen measured with the bd quinol oxidase (Km, 300 nM) was higher than that of the cc(b/o)o3 cytochrome oxidase (Km, 620 nM). The total membrane activity of the bd quinol oxidase was higher than that of the cytochrome oxidase activity in line with the higher expression of the bd oxidase genes. In addition, analysis of the ΔbdΔcox mutant strain indicated the presence of at least one O2-scavenging membrane-bound system able to reduce O2 with menaquinol as electron donor with an O2 affinity that was two orders of magnitude lower than that of the bd quinol oxidase. The lower O2 reductase activity in mutant cells with hydrogen as electron donor and the use of specific inhibitors indicated an electron transfer link between periplasmic H2 oxidation and membrane-bound oxygen reduction via the menaquinol pool. This linkage is crucial in defence of the strictly anaerobic bacterium Desulfovibrio against oxygen stress.

[Glomus tumor of the finger pulp: an unusual pediatric case]

Glomus tumor is a rare benign tumor. Diagnosis is often delayed because of the absence of specific symptoms and confirmation can only be made by histological study. Treatment is always surgical. We report a clinical case of glomus tumor of the thumb pulp in a 6-year-old girl, and we discuss clinical, radiological and histological aspects of this tumor.

Displaced femoral neck fractures in children: are complications predictable?

INTRODUCTION

Serious complications can occur in the management of displaced femoral neck fractures in children. Are there ways to anticipate this risk and better define eventual contributing factors?

PATIENTS AND METHODS

Twenty-one children (14 boys and 7 girls) were treated between 1999 and 2006 for displaced femoral neck fractures. Nine type II, 10 type III and two type IV fractures were observed according to the Delbet's classification. Anatomical open reduction was performed in 13 patients and closed reduction in eight patients. At a mean follow-up of 26.4 months, the outcome was assessed according to the Ratliff criteria. Postoperative complications were analysed according to the age, fracture type, time-to-surgery and open or closed reduction.

RESULTS

The mean age was 12.1 years. The final outcome was defined as good in 14 patients(66.66%), fair in one patient (4.76%) and poor in six patients (28.58%). Complications occurred in seven patients (33.33%), avascular necrosis (AVN) of the femoral head being the most frequent one (28.58%). In all cases, necrosis was observed in children older than 12 years (p < 0.05) and when time-to-surgery exceeded 48 h (p < 0.05). Necrosis occurred in 44.44% of type II fractures and in 20% of type III fractures (p > 0.05). Only one materialised after closed reduction (p < 0.05).

DISCUSSION

Various factors may contribute to the development of complications in children with femoral neck fractures. Our study supports the hypothesis that older age, late surgery and open reduction are definite predictors of avascular necrosis occurrence.

LEVEL OF EVIDENCE

Retrospective study, level IV.

[Risk factors of osteonecrosis of the femoral head following slipped capital femoral epiphysis]

Osteonecrosis is a serious complication of the treatment of slipped capital femoral epiphysis. The purpose of this study was to identify factors predisposing to the development of this complication. We reviewed retrospectively 127 patients (150 hips) treated for slipped capital femoral epiphysis in our institution between 1980 and 2004. Clinical and radiological data were analyzed before and after treatment, and at consecutive follow-up examination. Osteonecrosis was defined in the basis of radiological criteria. The risk of development of osteonecrosis was correlated with multiple clinical and radiographic parameters.

RESULTS

12 hips in 11 patients (8%) had development of osteonecrosis. Ten of them had an unstable slip. From 130 stable hips, regardless of grade, two had development of osteonecrosis. In patients who had presented with an unstable hip, the risk of osteonecrosis increased with the grade of the slip. Osteonecrosis was more likely to develop in hips that had been treated with multiple screws than in those who had been treated with a single screw. In conclusion, partial or complete reduction of an unstable slipped capital femoral epiphysis increases the risk of development of osteonecrosis. Pinning in situ without reduction with a single screw is the method of choice of the treatment of a slipped capital femoral epiphysis.

[Supra and intercondylar elbow fractures in children]

Supra- and intercondylar elbow fractures are rare in children. The treatment of these fractures is controversial. The purpose of this report is to discuss diagnosis and treatment of this unusual injury. Our study looked at nine patients between six and 15 years old (average age: 11.5). In four patients, the fracture was T-condylar and in five patients, the fracture was epiphyseal-diaphyseal. Communition was noted in five cases. All fractures are secondary to high-energy trauma. All patients were treated by open reduction and internal fixation. Three patients had associated nervous lesions. Patients were reviewed at an average of 30 months follow-up and the results evaluated according to the criteria of Flynn. The results were good or excellent in six patients, fair in two patients and poor in one. Cubitus varus and limitation of elbow motion were the main complication. Supra- and intercondylar elbow fractures should be differentiated from the more common supracondylar humerus fractures. We recommended open reduction with internal fixation. Complications are due to the severity of the initial trauma and sometimes to defective treatment especially in the case of complex fracture.

Pronator teres transfer to correct pronation deformity of the forearm after an obstetrical brachial plexus injury

A pronation deformity of the forearm following an obstetric brachial plexus injury causes functional and cosmetic disability. We evaluated the results of pronator teres transfer to correct their deformity in 14 children treated over a period of four years. The mean age at surgery was 7.6 years (5 to 15). The indication for surgery in each case was impairment of active supination in a forearm that could be passively supinated provided that there was no medial contracture of the shoulder and normal function of the hand. The median follow-up was 20.4 months (8 to 42). No patient was lost to follow-up. Qualitative results were also assessed. The median active supination improved from 5 degrees (0 degrees to 10 degrees ) to 75 degrees (70 degrees to 80 degrees ) with no loss of pronation. A passively correctible pronation contracture can be corrected safely and effectively by the transfer of pronator teres.

False aneurysm of the radial artery: Unusual complication of both-bone forearm fracture in children: A case report

False aneurysm or pseudo aneurysm of an artery in close proximity to fractured bone is a well-recognized entity, and fewer various cases, involving different sites have been reported in the literature. We report new case of a Moroccan's patient who had 10-year-old boy presented with a right non displaced both-bone forearm fracture; the patient was placed in a long arm splint. After, six weeks, the cast was removed. And a pulsatile mass on the volar-radial aspect of the forearm was decouvred. The mass was non-tender and the patient had radial and ulnar pulse. An Ultrasound and brachial angiography showed a false aneurysm of distal radial and the radial artery was ligated.In conclusion, pseudoaneurysm of the radial artery can be associated with any bone fracture despite non displacing fractures related to the elasticity of the bone in this age and orthopedic surgeons should be aware of this potential complication.

Marked genetic differences in the regulation of blood glucose under immune and restraint stress in mice reveals a wide range of corticosensitivity

Male and female mice from different control strains (C57BL/6, DBA/2, BALB/c) and the nonobese diabetic (NOD) strain, a spontaneous model of type 1 diabetes, were subjected to various stressors (restraint, lipopolysaccharide or interleukin-1 injection). Significant differences were measured among strains in blood glucose, insulin and corticosterone levels and, for restraint, IL-6. Addition of dexamethasone, a glucocorticoid receptor agonist, to inhibit the expression of several proteins by LPS-stimulated bone marrow-derived macrophages in vitro showed a gradient among control strains: C57BL/6>DBA/2>BALB/c corroborating the pattern of corticosensitivity suggested by their stress-induced glucose responses at the systemic level.

[Muscular tuberculosis: an unusual focus of Koch bacillus]

We report an exceptional case of tuberculosis in an 8-year-old girl. The focus of infection was situated in the anterior muscle compartment of the left thigh. Diagnosis was established on the basis of histological findings. A 12-month antituberculosis regimen was given. Outcome was good with no general or functional sequelae. Based on this case and data reported in the literature, we discuss the routes of dissemination of the Koch bacillus explaining this unusual sporadic localization.

[Role of laparoscopy in intra-abdominal testes in children. 35 case reports]

The impalpable testicles account for approximately 10 to 20% of the total of the not descended testicles. The importance of laparoscopy is increasingly significant, because apart from its diagnostic role recently a therapeutic interest was added. Thirty-five nonpalpable testicles took advantage of laparoscopic exploration at the pediatric's emergency surgery ward at the children's hospital of Rabat within the last 2 years. In 9 cases, total testicular agenesis was found. In 6 cases the testicles were situated very high in the abdomen, so that a first time laparoscopy was performed where the testicles were lowered. In 10 cases, one laparoscopic intervention for lowering the testicles was sufficient. In 10 cases, laparoscopic surgery showed that the vas deferens and the spermatic vessels reunified in the inguinal; so that, Inguinal exploration was necessary. The time of hospitalisation was 24 h with no complications noticed. We present this work to sensitise the surgeons on the new therapeutic approach to optimise the taking care of cryptorchid boys.

[Medico-economic study of percutaneous and surgical closure of ostium secundum type interatrial communications]

The aim of this study was the medico-economic evaluation of the closure of ostium secundum type interatrial communications in 32 patients, treated by cardiac catheterisation (group A: n = 17) or by surgery (group B: n = 15). The success rate was 100% with the 2 techniques. With national cost scale data we evaluated the overall cost of the 2 treatments using the information system medical program, starting from homogenous groups of patients: 150 catheterisation, 169 and 170 surgery. As the value for the homogenous group of 150 patients was much lower than the price of the material used for catheterisation, an adjusted group of 150 patients including the price of this material was created. An evaluation in terms of an artificial index of activity was also performed. The average duration of hospital stay for group A was reduced by 6.1 days compared to group B (p < 0.001). The overall cost was lower in group A than in group B (p < 0.001), using the real and "adjusted" homogenous group of 150 patients, with a respective reduction of 7,582 Euros and 3,731 Euros. Surgery and catheterisation scored 8,167 points (17,756 Euros) and 2,726 points (5,926 Euros) per patient respectively on the artificial activity index. In conclusion, catheterisation reduced the duration of hospital stay and brought an economic benefit for the Assurance Maladie compared to surgery. However, surgery is more profitable for the hospital than catheterisation because of the high cost of the prosthesis, which is not taken into account with a homogenous group of non-specific patients. This could hamper the development of this innovative technique in a hospital subjected to overall budgetary constraints.

[Renal hydatid cyst in children: report of 6 cases]

Echinococcosis or hydatid cyst disease of the kidney is extremely rare in children and constitutes only 2-4% of all cases of hydatid disease. We present six pediatric case of hydatid cyst of the kidney. The presentation is a cystic space occupying lesion of the kidney. Three patients have another involvement (lung, liver, and brain). Several diagnostic methods are available, ultrasonography may be sufficient. Surgical conservative treatment is still necessary, range from excision of the cyst. Significant surgical morbidity can be expected.

[An unusual localization of solitary bone cyst in a child: the lumbar spine]

Solitary bone cysts involving the spine in children are extremely rare. We report such a lesion in a 7-year-old girl who presented with an expansible, bubbly cystic lesion of the third lumbar vertebra. The intraoperative findings and histologic examination indicated the diagnosis of a solitary bone cyst. She was treated successfully with curettage and bone grafting.

["Small left colon" syndrome (two case reports)]

CASE REPORTS

Two newborns, one female and male were treated for neonatal bowel obstruction. A contrast enema led to the diagnosis of small left colon syndrome and treated those newborns successfully.

CONCLUSION

Small left colon syndrome is a very rare cause of neonatal bowel obstruction. The diagnosis and treatment are assured by a simple contrast enema.

[The square pronator: an "aspirin" strip in antalgic surgery for painful neuromas of the wrist]

From June 96 to January 2001, 25 patients have been operated on for painful neuromas localised at the wrist. They were between 10 and 52 years of age. These neuromas were located in at the median nerve 17 cases, at the ulnar nerve in seven cases and at the radial nerve in one case. In all cases the pain was not spontaneous but triggered off by external stimulus. All these neuromas were in continuity except 1 case at the median nerve where a total severing was present. After external neurolysis, the quadratus pronatus muscle is wrapped around the neuromas in 24 cases and around epineurial suture in one case. No internal neurolysis was done. This flap was vascularized by the anterior interosseous artery in 23 cases and by the posterior interosseous artery in two cases of distal ulnar nerve neuroma. All patients have been improved by using this method. In 21 cases (84%) (17 median, 4 ulnar nerves) the pain has completely disappeared and in four cases (3 ulnar, 1 radial), the pain has considerably decreased but without total disappearance. In the cases of median nerve neuromas the dysaesthesia has greatly decreased. No complications and no sequelae on the donor site are reported.

[Laryngeal dyspnea caused by cervical hydatidosis: apropos of a case]

Hydatid cysts rarely present as a cervical tumor. We report a case of hydatid cyst of the neck in a child with multiple hydatid cysts in the liver, which was revealed by laryngeal dyspnea. Symptoms occurred in a six year-old country dweller, who presented with progressive laryngeal dyspnea. The chest radiographs showed extrinsic tracheal compression. A cervical ultrasonography showed a liquid filled mass evocative of hydatid cyst type 1. Explorative cervicotomy confirmed the diagnosis. The treatment was conservative after destruction of the parasite using a hypertonic saline solution. The immediate result was the disappearance of the laryngeal dyspnea.

Expansion of the antigenic repertoire of a single T cell receptor upon T cell activation

Activated T cells and their naive precursors display different functional avidities for peptide/MHC, but are thought to have identical antigenic repertoires. We show that, following activation with a cognate mimotope (NRP), diabetogenic CD8(+) T cells expressing a single TCR (8.3) respond vigorously to numerous peptide analogs of NRP that were unable to elicit any responses from naive 8.3-CD8(+) T cells, even at high concentrations. The NRP-reactive, in vivo activated CD8(+) cells arising in pancreatic islets of nonobese diabetic mice are similarly promiscuous for peptide/MHC, and paradoxically this promiscuity expands as the aviditiy of the T cell population for NRP/MHC increases with age. Thus, activation and avidity maturation of T lymphocyte populations can lead to dramatic expansions in the range of peptides that elicit functional T cell responses.

Progression of autoimmune diabetes driven by avidity maturation of a T-cell population

For unknown reasons, autoimmune diseases such as type 1 diabetes develop after prolonged periods of inflammation of mononuclear cells in target tissues. Here we show that progression of pancreatic islet inflammation to overt diabetes in nonobese diabetic (NOD) mice is driven by the 'avidity maturation' of a prevailing, pancreatic beta-cell-specific T-lymphocyte population carrying the CD8 antigen. This T-lymphocyte population recognizes two related peptides (NRP and NRP-A7) in the context of H-2Kd class I molecules of the major histocompatibility complex (MHC). As pre-diabetic NOD mice age, their islet-associated CD8+ T lymphocytes contain increasing numbers of NRP-A7-reactive cells, and these cells bind NRP-A7/H-2Kd tetramers with increased specificity, increased avidity and longer half-lives. Repeated treatment of pre-diabetic NOD mice with soluble NRP-A7 peptide blunts the avidity maturation of the NRP-A7-reactive CD8+ T-cell population by selectively deleting those clonotypes expressing T-cell receptors with the highest affinity and lowest dissociation rates for peptide-MHC binding. This inhibits the local production of T cells that are cytotoxic to beta cells, and halts the progression from severe insulitis to diabetes. We conclude that avidity maturation of pathogenic T-cell populations may be the key event in the progression of benign inflammation to overt disease in autoimmunity.

Ly-49P activates NK-mediated lysis by recognizing H-2Dd

Little is known regarding the ligand specificity of Ly-49 activating receptor subfamily members expressed by NK cells. A new Ly-49 activating receptor related to Ly-49A in its extracellular domain, designated Ly-49P, was recently cloned from 129 strain mice. We independently cloned an apparent allele of Ly-49P expressed by nonobese diabetic and nonobese diabetes-resistant mouse strain NK cells. We found it to be reactive with the A1 Ab thought to recognize a polymorphic epitope expressed only by the Ly-49A inhibitory receptor of the C57BL/6 strain. Rat RNK-16 cells transfected with Ly-49P mediated reverse Ab-dependent cellular cytotoxicity of FcR-positive target cells, indicating that Ly-49P can activate NK-mediated lysis. We determined that RNK-16 lysis of Con A blasts induced by Ly-49P was MHC dependent, resulting in efficient lysis of H-2Dd-bearing targets. We found that the Dd alpha1/alpha2 domain is required for Ly-49P-mediated RNK-16 activation, as determined by exon shuffling and transfection. Thus, Ly-49P is the second activating Ly-49 receptor demonstrated to induce NK cytotoxicity by recognizing a class I MHC molecule.

IL-1alpha, IL-1beta, and IFN-gamma mark beta cells for Fas-dependent destruction by diabetogenic CD4(+) T lymphocytes

Cytokines such as IL-1alpha, IL-1beta, and IFN-gamma have long been implicated in the pathogenesis of autoimmune diabetes, but the mechanisms through which they promote diabetogenesis remain unclear. Here we show that CD4(+) T lymphocytes propagated from transgenic nonobese diabetic (NOD) mice expressing the highly diabetogenic, beta cell-specific 4.1-T-cell receptor (4.1-TCR) can kill IL-1alpha-, IL-1beta-, and IFN-gamma-treated beta cells from NOD mice. Untreated NOD beta cells and cytokine-treated beta cells from Fas-deficient NOD.lpr mice are not targeted by these T cells. Killing of islet cells in vitro was associated with cytokine-induced upregulation of Fas on islet cells and was independent of MHC class II expression. Abrogation of Fas expression in 4.1-TCR-transgenic NOD mice afforded nearly complete protection from diabetes and did not interfere with the development of the transgenic CD4(+) T cells or with their ability to cause insulitis. In contrast, abrogation of perforin expression did not affect beta cell-specific cytotoxicity or the diabetogenic potential of these T cells. These data demonstrate a novel mechanism of action of IL-1alpha, IL-1beta, and IFN-gamma in autoimmune diabetes, whereby these cytokines mark beta cells for Fas-dependent lysis by autoreactive CD4(+) T cells.

Prevalent CD8(+) T cell response against one peptide/MHC complex in autoimmune diabetes

Spontaneous autoimmune diabetes in nonobese diabetic (NOD) mice is the result of a CD4(+) and CD8(+) T cell-dependent autoimmune process directed against the pancreatic beta cells. CD8(+) T cells play a critical role in the initiation and progression of diabetes, but the specificity and diversity of their antigenic repertoire remain unknown. Here, we define the structure of a peptide mimotope that elicits the proliferation, cytokine secretion, differentiation, and cytotoxicity of a diabetogenic H-2K(d)-restricted CD8(+) T cell specificity (NY8.3) that uses a T cell receptor alpha (TCRalpha) rearrangement frequently expressed by CD8(+) T cells propagated from the earliest insulitic lesions of NOD mice (Valpha17-Jalpha42 elements, often joined by the N-region sequence M-R-D/E). Stimulation of splenic CD8(+) T cells from single-chain 8. 3-TCRbeta-transgenic NOD mice with this mimotope leads to preferential expansion of T cells bearing an endogenously derived TCRalpha chain identical to the one used by their islet-associated CD8(+) T cells, which is also identical to the 8.3-TCRalpha sequence. Cytotoxicity assays using islet-derived CD8(+) T cell clones from nontransgenic NOD mice as effectors and peptide-pulsed H-2K(d)-transfected RMA-S cells as targets indicate that nearly half of the CD8(+) T cells recruited to islets in NOD mice specifically recognize the same peptide/H-2K(d) complex. This work demonstrates that beta cell-reactive CD8(+) T cells mount a prevalent response against a single peptide/MHC complex and provides one peptide ligand for CD8(+) T cells in autoimmune diabetes.

Autoantigen-independent deletion of diabetogenic CD4+ thymocytes by protective MHC class II molecules

Some MHC class II genes provide dominant resistance to certain autoimmune diseases via mechanisms that remain unclear. We have shown that thymocytes bearing a highly diabetogenic, I-Ag7-restricted beta-cell-reactive TCR (4.1-TCR) undergo negative selection in diabetes-resistant H-2g7/x mice by engaging several different antidiabetogenic MHC class II molecules on thymic (but not peripheral) hemopoietic cells, independently of endogenous superantigens. Here we have investigated 1) whether this TCR can also engage protective MHC class II molecules (I-Ab) on cortical thymic epithelial cells in the absence of diabetogenic (I-Ag7) molecules, and 2) whether deletion of 4.1-CD4+ thymocytes in I-Ab-expressing mice might result from the ability of I-Ab molecules to present the target beta-cell autoantigen of the 4.1-TCR. We show that, unlike I-Ag7 molecules, I-Ab molecules can restrict neither the positive selection of 4.1-CD4+ thymocytes in the thymic cortex nor the presentation of their target autoantigen in the periphery. Deletion of 4.1-CD4+ thymocytes by I-Ab molecules in the thymic medulla, however, is a peptide-specific process, since it can be triggered by hemopoietic cells expressing heterogeneous peptide/I-Ab complexes, but not by hemopoietic cells expressing single peptide/I-Ab complexes. Thus, unlike MHC-autoreactive or alloreactive TCRs, which can engage deleting MHC molecules in the thymic cortex, thymic medulla, and peripheral APCs, the 4.1-TCR can only engage deleting MHC molecules (I-Ab) in the thymic medulla. We therefore conclude that this form of MHC-induced protection from diabetes is based on the presentation of an anatomically restricted, nonautoantigenic peptide to highly diabetogenic thymocytes.

Perforin-independent beta-cell destruction by diabetogenic CD8(+) T lymphocytes in transgenic nonobese diabetic mice

Autoimmune diabetes in nonobese diabetic (NOD) mice results from destruction of pancreatic beta cells by T lymphocytes. It is believed that CD8(+) cytotoxic T lymphocytes (CTLs) effect the initial beta-cell insult in diabetes, but the mechanisms remain unclear. Studies of NOD.lpr mice have suggested that disease initiation is a Fas-dependent process, yet perforin-deficient NOD mice rarely develop diabetes despite expressing Fas. Here, we have investigated the role of perforin and Fas in the ability of beta cell-reactive CD8(+) T cells bearing a T-cell receptor (8.3-TCR) that is representative of TCRs used by CD8(+) CTLs propagated from the earliest insulitic lesions of NOD mice, and that targets an immunodominant peptide/H-2Kd complex on beta cells, to effect beta-cell damage in vitro and in vivo. In vitro, 8.3-CTLs killed antigenic peptide-pulsed non-beta-cell targets via both perforin and Fas, but they killed NOD beta cells via Fas exclusively. Perforin-deficient 8.3-TCR-transgenic NOD mice expressing an oligoclonal or monoclonal T-cell repertoire developed diabetes even more frequently than their perforin-competent littermates. These results demonstrate that diabetogenic CD8(+) CTLs representative of CTLs putatively involved in the initiation of autoimmune diabetes kill beta cells in a Fas-dependent and perforin-independent manner.

Two mechanisms for the non-MHC-linked resistance to spontaneous autoimmunity

Genetic susceptibility and resistance to most autoimmune disorders are associated with highly polymorphic genes of the MHC and with non-MHC-linked polygenic modifiers. It is known that non-MHC-linked polymorphisms can override or enhance the susceptibility to an autoimmune disease provided by pathogenic MHC genes, but the mechanisms remain elusive. In this study, we have followed the fate of two highly diabetogenic beta cell-specific T cell receptors (Kd and I-Ag7 restricted, respectively) in NOR/Lt mice, which are resistant to autoimmune diabetes despite expressing two copies of the diabetogenic MHC haplotype H-2g7. We show that at least two mechanisms of non-MHC-linked control of pathogenic T cells operate in these mice. One segregates as a recessive trait and is associated with a reduction in the peripheral frequency of diabetogenic CD8+ (but not CD4+) T cells. The other segregates as a dominant trait and is mediated by IL-4- and TGF-beta1-independent immune suppressive functions provided by lymphocytes that target diabetogenic CD4+ and CD8+ T cells, without causing their deletion, anergy, immune deviation, or ignorance. These results provide explanations as to how non-MHC-linked polymorphisms can override the susceptibility to an autoimmune disease provided by pathogenic MHC haplotypes, and demonstrate that protective non-MHC-linked genes may selectively target specific lymphoid cell types in cellularly complex autoimmune responses.

[Congenital urethrocele in children. A case report]

Congenital urethrocele is a fairly rare disease in children. The authors report the case of a 9-year-old child presenting with a penoscrotal mass. Pressure on the mass produced urine. The diagnosis of urethrocele was established by ultrasonography and cystourethrography. Urethroplasty was successfully performed.

Papaya glutamine cyclase, a plant enzyme highly resistant to proteolysis, adopts an all-beta conformation

Glutamine cyclases catalyse the conversion of L-glutaminyl-peptides into 5-oxoprolyl-peptides with the concomitant liberation of ammonia. We report here biophysical characterisation of the glutamine cyclase present in the laticiferous cells of the plant Carica papaya. After purification to near homogeneity, this enzyme was subjected to limited proteolysis and found to exhibit a high resistance to degradation and nicking. The structural reasons for this property were examined using circular dichroism and infrared spectroscopies. By combining the analyses of the infrared and CD spectra of papaya glutamine cyclase, its susceptibility to proteolysis, and its hydrogen-deuterium exchange characteristics, we conclude that this protein contains extensive beta-sheet structure and is likely to have only short immobile loops connecting its beta-strands.

Purification and characterization of papaya glutamine cyclotransferase, a plant enzyme highly resistant to chemical, acid and thermal denaturation

Papaya glutamine cyclotransferase (PQC), present in the laticiferous cells of the tropical species Carica papaya, was purified near to homogeneity. Starting from the soluble fraction of the collected plant latex, a combination of ion-exchange chromatography on SP-Sepharose Fast Flow, hydrophobic interaction chromatography on Fractogel TSK Butyl-650 and affinity chromatography on immobilized trypsin provided a purification factor of 279 with an overall yield of 80%. In the course of the purification procedure, the two solvent accessible thiol functions located on the hydrophobic surface of the enzyme were converted into their S-methylthioderivatives. Papaya QC, a glycoprotein with a molecular mass of 33000 Da, contains a unique and highly basic polypeptide chain devoid of disulfide bridges as well as of covalently attached phosphate groups. Its absorption spectrum is dominated by the chromophores tyrosine which, nonetheless, do not contribute to the fluorescence emission of the plant enzyme. With a lambdamax of emission at 338 nm and a moderate susceptibility to be quenched by acrylamide, most of the tryptophyl residues of papaya QC appear to be sterically shielded by surrounding protein atoms. Fluorescence can thus be used to monitor unfolding of this enzyme. Preliminary experiments show that papaya QC is exceptionally resistant to chemical (guanidinium hydrochloride), acid and thermal denaturation. At first sight also, this enzyme exhibits high resistance to proteolysis by the papaya cysteine proteinases, yet present in great excess (around 100 mol of proteinases per mol of PQC) in the plant latex. Altogether, these results awaken much curiosity and interest to further investigate how the structure of this plant enzyme is specified.

Glucose homeostasis in the nonobese diabetic mouse at the prediabetic stage

Because few data were available on glucose homeostasis at the early prediabetic stage in the nonobese diabetic (NOD) mouse, we investigated glycemia, insulinemia, and pancreatic insulin content under basal conditions in both sexes of 4-, 6-, and 8-week-old fed NOD mice, compared with sex- and age-matched fed C57BL/6 mice. We also investigated glucose tolerance in both sexes of fasting 8-week-old NOD and C57BL/6 mice. The main results obtained under basal fed conditions, when comparing both strains, were lower glycemia and higher insulinemia in NOD females at all ages investigated and in NOD males (particularly at 6 weeks of age). Glucose tolerance tests showed that: 1) the blood glucose response to 1 g/kg i.p. glucose was less sustained in both sexes of 8-week-old NOD mice than in their control counterparts; 2) the blood insulin response to glucose (1 g/kg i.p.) appeared earlier in both sexes of NOD mice than in sex-matched C57BL/6 mice; 3) an unusual sexual dimorphism existed in NOD mice, compared with controls, with females secreting, in response to glucose, twice as much insulin as males; 4) dose-response studies (1-6 g/kg glucose) confirmed the lower increase in blood glucose levels in both sexes of NOD mice and their unusual sexual dimorphism in insulin secretion; and 5) glucose tolerance tests in 4- to 8-week-old NOD mice showed that although the sexual dimorphism in insulin secretion was not observed in 4-week-old mice, it was particularly striking at 6 weeks of age. Taken together, these results suggest that beta-cell hyperactivity exists in the NOD mouse at the early prediabetic stage, especially in NOD females.

[Reconstruction of the penis after necrosis due to circumcision]

Total necrosis of the penis is a very serious complication of circumcision with an electrical scalpel. Reconstruction of the penis was achieved by mobilization of the corpora cavernosa and detachment from the ischiopubic rami, which was then placed in a scrotal tunnel to avoid recurrent adhesion to ischiopubic rami and to ensure skin cover of the penis. After a follow-up of 6 months, this child urinated with a good stream and presented spontaneous erections.

[Polyps of the posterior urethra in children. Apropos of a case]

Posterior urethral polyp is a rare disease, predominantly affecting boys. The authors report the case of an 10-month-old boy admitted to hospital with acute urine retention. The diagnosis of polyp was established on cystourethrography, ultrasonography and endoscopy. The polyp was resected via a bladder incision after failure of transurethral resection. Posterior urethral polyp is a benign tumour whose clinical presentation is dominated by signs of lower urinary tract obstruction. Cystourethrography and ultrasonography confirm the diagnosis and assess the repercussions on kidneys and bladder. Endoscopy has a double role: diagnostic and therapeutic.

Carica papaya latex is a rich source of a class II chitinase

A class II chitinase is present in the latex of the tropical species Carica papaya. The enzyme may be readily purified by using a combination of hydrophobic interaction- and cation-exchange chromatography. This enzyme preparation is homogeneous with respect to the three physico-chemical criteria of charge, M(r) (28,000) and hydrophobicity. It is also completely free of any proteolytic and bacteriolytic activities. The enzyme was classified as a class II chitinase on the basis of its N-terminal amino acid sequence up to the 30th residue. In agreement with this classification, the enzyme preparation hydrolyses chitinase substrates only very slowly and several free thiol functions are present in the polypeptide chain. These free thiol functions are buried, and to be available for titration with 2,2'-dipyridyldisulphide, the enzyme must be denatured. Unfolding of papaya chitinase requires particularly drastic conditions, not less than 4 M guanidinium hydrochloride at 25 degrees and pH 6.8.

Spontaneous autoimmune diabetes in monoclonal T cell nonobese diabetic mice

It has been established that insulin-dependent diabetes mellitus (IDDM) in nonobese diabetic (NOD) mice results from a CD4+ and CD8+ T cell-dependent autoimmune process directed against the pancreatic beta cells. The precise roles that beta cell-reactive CD8+ and CD4+ T cells play in the disease process, however, remain ill defined. Here we have investigated whether naive beta cell-specific CD8+ and CD4+ T cells can spontaneously accumulate in pancreatic islets, differentiate into effector cells, and destroy beta cells in the absence of other T cell specificities. This was done by introducing Kd- or I-Ag7-restricted beta cell-specific T cell receptor (TCR) transgenes that are highly diabetogenic in NOD mice (8.3- and 4.1-TCR, respectively), into recombination-activating gene (RAG)-2-deficient NOD mice, which cannot rearrange endogenous TCR genes and thus bear monoclonal TCR repertoires. We show that while RAG-2(-/-) 4.1-NOD mice, which only bear beta cell-specific CD4+ T cells, develop diabetes as early and as frequently as RAG-2+ 4.1-NOD mice, RAG-2(-/-) 8.3-NOD mice, which only bear beta cell-specific CD8+ T cells, develop diabetes less frequently and significantly later than RAG-2(+) 8.3-NOD mice. The monoclonal CD8+ T cells of RAG-2(-/-) 8.3-NOD mice mature properly, proliferate vigorously in response to antigenic stimulation in vitro, and can differentiate into beta cell-cytotoxic T cells in vivo, but do not efficiently accumulate in islets in the absence of a CD4+ T cell-derived signal, which can be provided by splenic CD4+ T cells from nontransgenic NOD mice. These results demonstrate that naive beta cell- specific CD8+ and CD4+ T cells can trigger diabetes in the absence of other T or B cell specificities, but suggest that efficient recruitment of naive diabetogenic beta cell-reactive CD8+ T cells to islets requires the assistance of beta cell-reactive CD4+ T cells.

Interleukin-1 effect on glycemia in the non-obese diabetic mouse at the pre-diabetic stage

Cytokines, particularly interleukin 1 (IL-1) and tumor necrosis factor, are known to induce hypoglycemia in normal rodents or different experimental models of type II diabetes. We investigated, at the pre-diabetic stage, the effect of short-term administration of murine recombinant interleukin-1 alpha (mrIL-1 alpha) on the levels of glucose, insulin and corticosterone in the non-obese diabetic (NOD) mouse, a spontaneous model of type I diabetes. Two-month-old, pre-diabetic NOD mice of both sexes were insensitive to mrIL-1 alpha (12.5 and 50 micrograms/kg) 2 h after administration, the time at which the maximal decrease (around 50%) was observed in the C57BL/6 mouse strain. Kinetic studies however showed that mrIL-1 alpha lowered glycemia in both sexes of NOD mice, but the effect was limited and delayed. In the NOD and C57BL/6 strains, mrIL-1 alpha had no influence on insulin levels in females, but significantly increased them in males (P < 0.0001). Castration of NOD males abrogated the stimulatory effect of mrIL-1 alpha on insulin secretion. Corticosterone secretion was stimulated by mrIL-1 alpha in both sexes of NOD and C57BL/6 mice, and this effect was faster and greater in NOD females than in C57BL/6 females. The incomplete hypoglycemic response to mrIL-1 alpha in females may be attributed to the anti-insulin effect of glucocorticoids, an effect which can be demonstrated when mrIL-1 alpha is administered to adrenalectomized animals or when mrIL-1 alpha is administered together with the glucocorticoid antagonist RU38486. In NOD males, in contrast, glucocorticoids did not play a major role in the limited hypoglycemic response to mrIL-1 alpha, since RU38486 and adrenalectomy were not able to unmask a hypoglycemic effect. Moreover, NOD mice of both sexes were less sensitive than C57BL/6 mice to the hypoglycemic effect of insulin (2.5 U/kg), which suggests some degree of insulin-resistance in NOD mice. With regard to the effect of IL-1 on NOD mouse glycemia, therefore, these results suggest that glucocorticoids and/or androgens, according to the animal's sex, may induce a state of insulin-resistance.

PCR analysis of interleukin-1 receptor gene in the nonobese diabetic mouse

Insulin-dependent diabetes mellitus (IDDM) is characterized by a progressive autoimmune destruction of pancreatic beta cells. Many data suggest that interleukin 1 (IL-1) plays a fundamental role in the pathogenesis of the disease. In the nonobese diabetic (NOD) mouse, a spontaneous model of IDDM, it was put forward that the disease is linked to a susceptibility locus, called idd5, which contains the IL-1 receptor (IL-1R) gene. The polymerase chain reaction (PCR) was used to characterize the IL-1R gene in our NOD mouse colony and in two mouse strains taken as controls. Using primers to amplify the IL-1R gene between bp-106 and +378, a 580 bp fragment was obtained from C57BL/6 DNA but not from DBA/2 and NOD DNA. However, amplification of the IL-1R gene region between bp +1 and +378 in the three strains yielded amplicons 480 bp long. The specificity of the amplification was confirmed by restriction analysis. Our results suggest, depending on the strain, the presence of one or two introns: one (480 bp) in the 5'-untranslated region and the other (100 bp) in the region coding for amino acids between 69 and 126, and an exon-intron organization of the mouse IL-1R gene different than that described in the human genome.

Localization and characterization of interleukin-1 receptors in the islets of Langerhans from control and nonobese diabetic mice

Numerous in vivo and in vitro studies have shown the effects of interleukin-1 (IL-1) on insulin and glucagon secretion. To understand the mechanism of these effects, we performed localization and characterization of IL-1 receptors (IL-1R) in pancreas using a quantitative autoradiography method and recombinant human (rh) [125I]IL-1 alpha as a ligand. Frozen sections of pancreas were studied in control (C3H/He) and nonobese diabetic (NOD) mice (a model of autoimmune type I diabetes). Compared to splenic IL-1R, a very high density of specific IL-1R (> 4-fold that in spleen) was found on the islets of Langerhans in both strains. In C3H/He mice, competition experiments demonstrated the presence of one high affinity binding site (Ki = 3.4 and 3.2 x 10(-10) M; binding capacity, 137 and 122 fmol/mg protein for rhIL-1 alpha and rhIL-1 beta, respectively), comparable to type I IL-1R described on T-lymphocytes. In prediabetic NOD mice, these IL-1R were expressed with the same density, affinity, and specificity as in the control strain. Before the onset of diabetes, the expression of IL-1R protein on the islet cells appears to be entirely normal. In contrast, in diabetic NOD mice, IL-1R are sharply decreased, correlating with the intensity of islet destruction. In conclusion, the localization and high density of IL-1R on the mouse islets of Langerhans complement previous studies showing the presence of messenger RNA for type I IL-1R on the islets of Langerhans. These results support a direct physiological effect of IL-1 on pancreatic hormones, such as insulin and glucagon, and a potential role of IL-1R in the pathogenesis of type I diabetes.