Emergence and scattering of multiple neurofibromatosis (NF1)-related sequences during hominoid evolution suggest a process of pericentromeric interchromosomal transposition

Type 1 neurofibromatosis (NF1) gene encodes for a member of the GTPase activating protein family and is considered to be a tumor suppressor gene. Its very high rate of de novo mutation in humans led us to study a specific feature of this gene: the presence of numerous NF1-related sequences. According to our results, the human genome contains at least 11 NF1-related sequences, nine of which are scattered near centromeric sequences of seven different chromosomes. These NF1-related sequences, whose extent is quite varied according to loci, are unprocessed copies of the NF1 gene, and bear numerous mutations. A phylogenetic analysis of the six largest sequences indicates that they are all derived from a common ancestor, which would have appeared 22-33 million years ago, and was subsequently duplicated several times during hominoid evolution. The most recent duplication and interchromosomal transposition occurred in the last million years suggesting that the process could still be ongoing. Intriguing similarities between the evolution of alpha- satellite DNA and NF1-related sequences suggest the involvement of a common genetic mechanism for the generation and pericentric spreading of these NF1 partial copies.      

Aortic Remodelling in Chronic Nicotine-Administered Rat

Vascular remodelling is an adaptive mechanism, which counteracts pressure changes in blood circulation. Nicotine content in cigarette increases the risk of hypertension. The exact relationship between nicotine and vascular remodelling still remain unknown. Current study was aimed to determine the effect of clinically relevant dosage of nicotine (equivalent to light smoker) on aortic reactivity, oxidative stress markers and histomorphological changes. Twelve age-matched male Sprague-Dawley rats were randomly divided into two groups, i.e.: normal saline as control or 0.6 mg/kg nicotine for 28 days (i.p., n=6 per group). On day-29, the rats were sacrificed and the thoracic aorta was dissected immediately for further studies. Mean arterial pressure (MAP) and pulse pressure (PP) of nicotine-treated vs. control were significantly increased (p<0.05). Nicotine-treated group showed significant (p<0.05) increase tunica media thickness, and decrease in lumen diameter, suggesting vascular remodelling which lead to prior hypertension state. The phenylephrine (PE)-induced contractile response in nicotine group was significantly higher than control group (ED₅₀=1.44×10⁵ M vs. 4.9×10⁶ M) (p<0.05~0.001). However, nicotine-treated rat showed significantly lower endothelium-dependent relaxation response to acetylcholine (ACh) than in control group (ED₅₀=6.17×10⁷ M vs. 2.82×10⁷ M) (p<0.05), indicating loss of primary vascular function. Malondialdehyde (MDA), a lipid peroxidation marker was significantly higher in nicotine group. Superoxide dismutase (SOD) enzymatic activity and glutathione (GSH) were all reduced in nicotine group (p<0.05) vs. control, suggesting nicotine induces oxidative imbalance. In short, chronic nicotine administration impaired aortic reactivity, probably via redox imbalance and vascular remodelling mechanism.     

Effects of tropism and virulence of Leishmania parasites on cytokine production by infected human monocytes

The nature of early interactions between Leishmania and macrophages which determine the outcome of infection can be related directly to parasite biological properties. Here we compared the capacity of L. major (Lm) strains, reported to be high (LmHV) and low virulent and (LmLV) in the mouse model and L. infantum (Li) strains, dermotropic (LiD) and viscerotropic (LiV), to infect and modulate cytokine production in human peripheral blood derived monocytes. Monocytes were infected with metacyclic promastigotes for 24, 48 and 72 h. Parasite burden was significantly higher in Lm‐ than in Li‐infected monocytes. LmHV and LiD induced a significantly higher parasite burden than LmLV and LiV respectively. Cytokine production was evaluated in monocytes infected for 24 h. Contrary to interleukin (IL)‐12p70, monocyte chemotactic protein‐1 and transforming growth factor‐β production was increased significantly in infected monocytes with no differences between strains. Lm isolates induced significantly higher quantities of tumour necrosis factor (TNF)‐α than Li isolates. Low levels of IL‐10 were induced by all Leishmania strains and, interestingly, co‐stimulation with lipopolysaccharide (LPS) was accompanied by a dramatic increase in IL‐10 production by infected monocytes. In conclusion, Lm isolates displaying different levels of virulence in mice exhibited significant differences in parasite burden but similar abilities to modulate cytokine production in human monocytes. Li strains showed weaker infectivity and TNF‐α inducing‐capacity compared with Lm strains. The dramatic increase of IL‐10 production in infected monocytes co‐stimulated by LPS may play a role in disease progression considering the presence of LPS during bacterial superinfections observed during human leishmaniasis.     

The protective effect of aqueous extracts of roselle (Hibiscus sabdariffa L. UKMR-2) against red blood cell membrane oxidative stress in rats with streptozotocin-induced diabetes

OBJECTIVES:

The aim of this study was to investigate the protective effects of aqueous extracts of roselle (Hibiscus sabdariffa L. UKMR-2) against red blood cell (RBC) membrane oxidative stress in rats with streptozotocin-induced diabetes.

METHODS:

Forty male Sprague-Dawley rats weighing 230-250 g were randomly divided into four groups (n = 10 rats each): control group (N), roselle-treated control group, diabetic group, and roselle-treated diabetic group. Roselle was administered by force-feeding with aqueous extracts of roselle (100 mg/kg body weight) for 28 days.

RESULTS:

The results demonstrated that the malondialdehyde levels of the red blood cell membranes in the diabetic group were significantly higher than the levels in the roselle-treated control and roselle-treated diabetic groups. The protein carbonyl level was significantly higher in the roselle-treated diabetic group than in the roselle-treated control group but lower than that in the diabetic group. A significant increase in the red blood cell membrane superoxide dismutase enzyme was found in roselle-treated diabetic rats compared with roselle-treated control rats and diabetic rats. The total protein level of the red blood cell membrane, osmotic fragility, and red blood cell morphology were maintained.

CONCLUSION:

The present study demonstrates that aqueous extracts of roselle possess a protective effect against red blood cell membrane oxidative stress in rats with streptozotocin-induced diabetes. These data suggest that roselle can be used as a natural antioxidative supplement in the prevention of oxidative damage in diabetic patients.     

Circulation and Molecular Epidemiology of Enteroviruses in Paralyzed,Immunodeficient and Healthy Individuals in Tunisia,a Country with a Polio-Free Status for Decades

This report is an overview of enterovirus (EV) detection in Tunisian polio-suspected paralytic cases (acute flaccid paralysis (AFP) cases), healthy contacts and patients with primary immunodeficiencies (PID) during an 11-year period. A total of 2735 clinical samples were analyzed for EV isolation and type identification, according to the recommended protocols of the World Health Organization. Three poliovirus (PV) serotypes and 28 different nonpolio enteroviruses (NPEVs) were detected. The NPEV detection rate was 4.3%, 2.8% and 12.4% in AFP cases, healthy contacts and PID patients, respectively. The predominant species was EV-B, and the circulation of viruses from species EV-A was noted since 2011. All PVs detected were of Sabin origin. The PV detection rate was higher in PID patients compared to AFP cases and contacts (6.8%, 1.5% and 1.3% respectively). PV2 was not detected since 2015. Using nucleotide sequencing of the entire VP1 region, 61 strains were characterized as Sabin-like. Among them, six strains of types 1 and 3 PV were identified as pre-vaccine-derived polioviruses (VDPVs). Five type 2 PV, four strains belonging to type 1 PV and two strains belonging to type 3 PV, were classified as iVDPVs. The data presented provide a comprehensive picture of EVs circulating in Tunisia over an 11-year period, reveal changes in their epidemiology as compared to previous studies and highlight the need to set up a warning system to avoid unnoticed PVs.     

Primary ciliary dyskinesia gene contribution in Tunisia: Identification of a major Mediterranean allele

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disease of motile cilia. Even though PCD is widely studied, North‐African patients have been rarely explored. In this study, we aim at confirming the clinical diagnosis and explore the genetic spectrum of PCD in a cohort of Tunisian patients. Forty clinically diagnosed patients with PCD belonging to 34 families were recruited from Tunisian pediatric departments. In each proband, targeted capture PCD panel sequencing of the 40 PCD genes was performed. PCD panel sequencing identified bi‐allelic mutations in 82% of the families in eight PCD genes. Remarkably, 23.5% of patients carried the same c.2190del CCDC39 mutation. Single nucleotide polymorphism profiling in six unrelated patients carrying this mutation has revealed a founder effect in North‐African patients. This mutation is estimated to date back at least 1,400–1,750 years ago. The identification of this major allele allowed us to suggest a cost‐effective genetic diagnostic strategy in North‐African patients with PCD.     

Lésions kystiques cérébrales : Pensez au kyste hydatique

Background. Hydatidosis is an endemic parasitosis in Tunisia that affect mostly the liver and the lung. Brain involvment is rare. Aim. To focus on diagnostic, therapeutic and evolutive characteristics of cerebral hydatidosis. Methods. We report all cases of cerebral hydatidosis seen in the infectious diseases and neurosurgery departments between January 2013 and June 2020. Results. Six cases of intracranial hydatid cyst were reported. The male to female ratio was 3:3. Age ranged from 3 to 60 years with a median age of 20,5 years. All patients lived in rural areas. The clinical symptomatology was progressive in 4 cases. It was dominated by headache (all cases). Brain imaging confirmed the diagnosis in all cases. The hydatid cyst was solitary and supratentorial in 3 cases. All the patients were operated. Albendazole was prescribed immediately after surgery, for 6 months in 5 cases and for 3 years in the case of disseminated hydatidosis. The outcome was favorable without recurrence in all patients with an average follow-up of 3,5 ± 0,5 years. Conclusion. Hydatid cyst of the brain is characterized by the severity of the neurological signs, the mandatory use of surgery because of life threatening and the excellent outcomes.     

Bone mineral density in healthy Tunisian women

Interpretation of densitometric results requires a comparison with reference bone mineral density (BMD) values of normal age and sex-matched persons. Thus the aim of this study was to determine these values for healthy Tunisian women, to estimate the prevalence of osteoporosis and to compare our findings with other populations. A cross-sectional study of 1378 Tunisian women aged between 20 and 96 years was carried out using DXA (GE-Lunar Prodigy). Subjects with suspected conditions affecting bone metabolism were excluded. Measurements were taken at the lumbar spine and femoral neck. These values were expressed at T-scores, with reference to the mean BMD values of the group aged 20–40 years. The peak bone mass, estimated in this age group was 1.174 + 0.127 g/cm² at the lumbar spine and 1.016 ± 0.118 g/cm² at the femoral site. It was attained respectively within the age of 25 years and 36 years. For both sites, the expected decline in BMD was shown when the successive age groups [40–49 years] and [50–59 years] were compared. Bone loss was rapid during the first 5 years after menopause. Thereafter BMD declined slowly but continually. The prevalence of osteoporosis in the women over 50 years of age, taking account of peak bone mass observed in our cohort, was 23.3% at the spine and 17.3% at the femoral neck with a combined prevalence of 23.4%. These rates attained respectively 30.4%, 11.8% and 32.9% when we considered the Italian values, which demonstrate the variability of osteodensitometric depending to the reference population adopted.     

Distribution of HLA-B27 and its alleles in patients with reactive arthritis and with ankylosing spondylitis in Tunisia

The purpose of the present study is to investigate the frequency of HLA-B27 and its alleles in reactive arthritis (ReA) and in ankylosing spondylitis (AS) in Tunisia. HLA-B27 alleles were typed by PCR amplification with sequence-specific primers. We studied 17 patients with ReA associated with urethritis or with gastrointestinal infection; 42 HLA-B27-positive patients with AS and 100 healthy controls. Eleven ReA patients (67.7%) were HLA-B27 positive. There was an increased frequencies of HLA-B27 (P = 7.76 × 10⁻¹², OR = 59.30) and a moderate increase of HLA-B51 (P = 0.015; OR = 4.91) alleles in ReA patients when compared with healthy controls. Four B27 subtypes were identified: B*2702, 05, 09 and B*2712. The distribution of these alleles in the ReA patients was 37.5% for B*2702 and B*2705. Only these two subtypes were detected in 18 (42.8%) and 24 (57.1%), respectively, of the AS patients. B*2709 and B*2712 were relatively rare in ReA patients and were identified in one case each. Our results showed a restricted number of HLA-B27 subtypes associated with ReA and AS. B*2702 and 2705 were common in ReA and AS patients.     

Relevant factors in mitral valve reconstructive surgery. Report of 150 cases

150 patients had mitral valve repair for mitral valve incompetence. There were 57 males and 93 females with a mean age of 22 years, 39% were less than 15 years of age. 60% of the patients were in Class II NYHA and 40% in Class III and IV. According to Carpentier's classification, isolated type I was present in 18 patients (12%), type II in 98 patients (64%) and type III in 34 cases (24%). Mitral repair included correction of valve prolapse, valvular enlargement with pericardial patch and annuloplasty with semi-rigid ring in 128 cases and PTFE patch along the posterior leaflet in 12 cases. The perioperative mortality rate was 2.6% (4 patients). All patients had early post-operative echocardiography. According to this, mitral regurgitation was absent or tiny in 135 patients (92%), grade II in 10 cases and grade III in 2 cases. It was moderate or important in twelve patients (8%). In the late post-operative period, three patients were lost to follow-up. All the others patients were reoperated upon for mitral dysfunction in a mean time of 37 months. The reason for reoperation was in the majority of the cases the recurrence of mitral regurgitation related to increase of valvular and sub valvular disease. The late mortality rate is 7% (10 patients). Out of 126 reviewed survivors on the long run, 71 patients (56%) are asymptomatic in class I, 53 patients (42%) in class II and 2 patients in class III NYHA. Mitral valvuloplasty is the preferred procedure in mitral insufficiency surgical management. It is associated to a low early mortality and morbidity rate. Despite the need for reoperation in about 10% of the cases in the long follow-up, mitral repair offers a good quality of life without anticoagulant treatment.