Molecular methods for colorectal cancer screening: Progress with next-generation sequencing evolution

Currently, colorectal cancer (CRC) represents the third most common malignancy and the second most deadly cancer worldwide, with a higher incidence in developed countries. Like other solid tumors, CRC is a heterogeneous genomic disease in which various alterations, such as point mutations, genomic rearrangements, gene fusions or chromosomal copy number alterations, can contribute to the disease development. However, because of its orderly natural history, easily accessible onset location and high lifetime incidence, CRC is ideally suited for preventive intervention, but the many screening efforts of the last decades have been compromised by performance limitations and low penetrance of the standard screening tools. The advent of next-generation sequencing (NGS) has both facilitated the identification of previously unrecognized CRC features such as its relationship with gut microbial pathogens and revolutionized the speed and throughput of cataloguing CRC-related genomic alterations. Hence, in this review, we summarized the several diagnostic tools used for CRC screening in the past and the present, focusing on recent NGS approaches and their revolutionary role in the identification of novel genomic CRC characteristics, the advancement of understanding the CRC carcinogenesis and the screening of clinically actionable targets for personalized medicine.

Molecular mechanisms underlying the defects of two novel mutations in the HSD17B3 gene found in the Tunisian population

17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) converts Δ4-androstene-3,17-dione (androstenedione) to testosterone. It is expressed almost exclusively in the testes and is essential for appropriate male sexual development. More than 70 mutations in the HSD17B3 gene that cause 17β-HSD3 deficiency and result in 46,XY Disorders of Sex Development (46,XY DSD) have been reported. This study describes three novel Tunisian cases with mutations in HSD17B3. The first patient is homozygous for the previously reported mutation p.C206X. The inheritance of this mutation seemed to be independent of consanguineous marriage, which can be explained by its high frequency in the Tunisian population. The second patient has a novel splice site mutation in intron 6 at position c.490 -6 T > C. A splicing assay revealed a complete omission of exon 7 in the resulting HSD17B3 mRNA transcript. Skipping of exon 7 in HSD17B3 is predicted to cause a frame shift in exon 8 that affects the catalytic site and results in a truncation in exon 9, leading to an inactive enzyme. The third patient is homozygous for the novel missense mutation p.K202M, representing the first mutation identified in the catalytic tetrad of 17β-HSD3. Site-directed mutagenesis and enzyme activity measurements revealed a completely abolished 17β-HSD3 activity of the p.K202M mutant, despite unaffected protein expression, compared to the wild-type enzyme. Furthermore, the present study emphasizes the importance of genetic counselling, detabooization of 46,XY DSD, and a sensitization of the Tunisian population for the risks of consanguineous marriage.

Germ Cell Tumors Revealing a Familial Persistent Müllerian Duct Syndrome

Persistent Mullerian duct syndrome (PMDS) is a congenital disorder related to male sexual development. PMDS is usually diagnosed during an inguinal hernia cure. The diagnosis of PMDS following a testicular germ cell tumor is less common. We report the cases of three infertile male patients who were diagnosed with PMDS after surgery for germ cell tumors. They were 39, 27, and 37 years old men with a medical history of neglected cryptorchidism. All patients had a male karyotype and the ELISA test for the anti-Mullerian hormone was undetectable. Patients underwent chemotherapy followed by resection of residual mass in one patient. One patient is currently alive and disease-free. The two other patients died of systemic relapse. These cases highlight how early recognition and treatment of PMDS can prevent malignant germ cell tumors. The diagnosis of PMDS relies on a systemic assessment and analysis of mutations in the gene coding for AMH and AMHR-II. Key words: Persistent Müllerian duct syndrome (PMDS), anti mullerian hormone, germ cell neoplasm.

Update meta-analysis from biomedical literature about MTHFR'polymorphisms and the CML' risk

BACKGROUND

The MTHFR gene polymorphisms are closely related to the chronic myeloid leukemia (CML). Case-control studies have associated the MTHFR polymorphisms and susceptibility to CML but the results were not conclusive.

AIM

To assess this association through an update meta-analysis.

METHODS

A descriptive and qualitative study was conducted among students in the 6th year of the faculty during the academic year 2020/2021. The data were collected through a questionnaire written in french evaluating the teaching methods. A focus group of ten persons was led to understand better student's opinions.

RESULTS

Totally, 17 and 12 case-control studies including CML cases and controls were enrolled in the meta-analysis respectively for C677T and A1298C polymorphism and CML risk. A poor association between the C677T (T vs C ; OR= 1,28; IC95%= [1,01;1,63]; p=0,04) and the one not significant between the A1298C (C vs A ; OR= 1,52; IC95%= [0,92; 2,51]; p= 0,1) polymorphisms and the CML risk for overall population were found.

CONCLUSION

The results of this meta-analysis suggested no significant association between C677T and A1298C polymorphisms and CML risk leading to consider other factors such us folic acid intake, gene-gene and gene- environment interactions.

SRD5A3-CDG: 3D structure modeling, clinical spectrum, and computer-based dysmorphic facial recognition

Pathogenic variants in Steroid 5 alpha reductase type 3 (SRD5A3) cause rare inherited congenital disorder of glycosylation known as SRD5A3-CDG (MIM# 612379). To date, 43 affected individuals have been reported. Despite the development of various dysmorphic features in significant number of patients, facial recognition entity has not yet been established for SRD5A3-CDG. Herein, we reported a novel SRD5A3 missense pathogenic variant c.460 T > C p.(Ser154Pro). The 3D structural modeling of the SRD5A3 protein revealed additional transmembrane α-helices and predicted that the p.(Ser154Pro) variant is located in a potential active site and is capable of reducing its catalytic efficiency. Based on phenotypes of our patients and all published SRD5A3-CDG cases, we identified the most common clinical features as well as some recurrent dysmorphic features such as arched eyebrows, wide eyes, shallow nasal bridge, short nose, and large mouth. Based on facial digital 2D images, we successfully designed and validated a SRD5A3-CDG computer based dysmorphic facial analysis, which achieved 92.5% accuracy. The current work integrates genotypic, 3D structural modeling and phenotypic characteristics of CDG-SRD5A3 cases with the successful development of computer tool for accurate facial recognition of CDG-SRD5A3 complex cases to assist in the diagnosis of this particular disorder globally.

Involvement of C677T MTHFR variant but not A1298C in methotrexate-induced toxicity in acute lymphoblastic leukemia

BACKGROUND

Methotrexate (MTX) is a key drug in acute lymphoblastic leukemia (ALL) treatment; it inhibits DNA replication by blocking the conversion of 5, 10 Methylenetetrahydrofolate to 5-methylene tetrahydrofolate by methylenetetrahydrofolate reductase (MTHFR). Variants of the Methylenetetrahydrofolate reductase (MTHFR) and MTX related toxicities were largely investigated in several populations, nevertheless, the results are conflicting.

OBJECTIVE

This study aimed to assess the prevalence of MTHFR SNVs: C677>T and A1298>C in Tunisian patients with ALL and the relation to the frequency of drug-induced complications.

METHODS

28 ALL patients were included in the study. They were treated according to EORTOC, in which a high dose of MTX (HDMTX) was prescribed. A toxicity score (ST) is calculated for each patient, summing the grades of toxicities. Genotyping of MTHFR variants was done with a PCR-based restriction fragment length polymorphism assay.

RESULTS

The toxicity's score (TS) was higher with C677T variant compared to wild genotype (C677C) (TS = 4; IC95% [-2.65-13.32] versus TS = 2.5; IC95% [1.65-4.55], respectively; p = 0.2); but lower with the A1298C mutation compared to those with the wild genotype (A1298A) (TS = 2.5; IC95% [0.48-4.77], versus TS =3; IC95% [1.9-5.69], p = 0.4). HDMTX-related toxicity is associated with the 677CT genotype in ALL patients (RR = 1.41, p = 0.2); not for the A1298C [OR = 0.46, [0.08-2.61], p = 0.18].

CONCLUSION

Our preliminary findings highlight the impact of the C677T variant of MTHFR, but not the A1289C; in HD-MTX chemotherapy-related adverse effects in younger Tunisian ALL.

Renal angiomyolipoma: Clinico-pathologic study of 17 cases with emphasis on the epithelioid histology and p53 gene abnormalities

BACKGROUND

Epithelioid angiomyolipoma (EAML) is a rare potentially malignant variant of renal angiomyolipoma (RAML). This study aims to determine whether RAML clinico-pathologic and molecular features (i.e. p53 gene abnormalities) differ significantly with regards to its histologic variant or to the presence of an epithelioid component within it.

METHODS

Consecutively resected RAML were reviewed, tumours comprising at least 80% of epithelioid cells were considered as EAML according to the 2016 World Health Organization classification of tumours of the kidney. P53 gene abnormalities were investigated using both immunohistochemical and molecular analysis.

RESULTS

A total of 3 EAML among 17 RAML were identified, accounting for 3.9% of the total AML cases. Fatty aspect on imaging was more observed within tumours devoid of an epithelioid component. EAML showed a higher mitotic rate and a stronger p53 staining, no renal poles involvement and was not treated by nephron sparing surgeries. RAML comprising an epithelioid component demonstrated severer nuclear atypia as well as stronger p53 staining. P53 gene sequencing revealed a missense mutation (c.747G > C) in one classic AML harbouring a strong labelling with p53.

CONCLUSIONS

Strong p53 staining in a RAML, even in the absence of gene mutation, may suggest the presence of an epithelioid component or of a truly EAML. To the best of our knowledge, c.747G > C p53 gene mutation is being reported for the first time in a RAML, although its role in AML pathogenesis is still unknown.

The first concurrent detection of mitochondrial DNA m.3243A>G mutation, deletion, and depletion in a family with mitochondrial diabetes

BACKGROUND

Mitochondrial diabetes (MD) is a rare monogenic form of diabetes and divided into type l and type 2. It is characterized by a strong familial clustering of diabetes with the presence of maternal transmission in conjunction with bilateral hearing impairment in most of the carriers. The most common form of MD is associated with the m.3243A>G mutation in the mitochondrial MT-TL1, but there are also association with a range of other point mutations, deletion, and depletion in mtDNA.

METHODS

The mitochondrial genome anomalies were investigated in a family with clinical features of MD, which includes a proband presenting severe MD conditions including cardiomyopathy, retinopathy, and psychomotor retardation.

RESULTS

By investigating the patient's blood leukocytes and skeletal muscle, we identified the m.3243A>G mutation in heteroplasmic state. This mutation was absent in the rest of the family members. In addition, our analysis revealed in the proband a large mtDNA heteroplasmic deletion (~1 kb) and a reduction in mtDNA copy number.

CONCLUSION

Our study points out, for the first time, a severe phenotypic expression of the m.3243A>G point mutation in association with mtDNA deletion and depletion in MD.

A homozygous ABCB4 mutation causing an LPAC syndrome evolves into cholangiocarcinoma

Low phospholipid-associated cholelithiasis (LPAC) is characterized by the association of ABCB4 mutations and low biliary phospholipid concentration with symptomatic and recurring cholelithiasis. In the present study, we reported a case of a 63-year-old woman, who presented a biliary pain beginning at the age of 30, recurrent after cholecystectomy, along with "comet-tail shadows" revealed by ultrasonography thus, fulfilling the diagnosis of LPAC. This disease evolved into a cholangiocarcinoma. To understand the molecular basis of this phenotype, we performed the ABCB4 gene sequencing, followed by in silico analysis and Q-RT-PCR assay. The results displayed a homozygous missense sequence variation (c.140G > A, p.Arg47Gln), predicted as pathogenic according to MutPred. Accordingly, this gave rise to a decreased hepatic ABCB4 mRNA level and structural alterations of the mutated protein. Eventually, we reported, here, the first description of an ABCB4 missense mutation (p.Arg47Gln) at homozygous state in a Tunisian LPAC syndrome. An elucidation of its functional consequences was performed. Besides, this case suggests that the delayed diagnosis of LPAC syndrome and the lack of UDCA treatment may contribute in the development of complications, such as cholangiocarcinoma.

Thyroid involvement in Chanarin-Dorfman syndrome in adults in the largest series of patients carrying the same founder mutation in ABHD5 gene

Background

Chanarin-Dorfman syndrome (CDS) is a rare syndromic disease related to an accumulation of triacylglycerol in most organs. The aim of our study was to investigate various organs in a large series of CDS patients.

Results

We report for the first time thyroid function impairment in CDS. Among 12 investigated patients, 7 showed thyroid function impairment. All of them were over 30 of age. The 5 remaining investigated patients with normal thyroid function were under 30. Thyroid loss of function is an unknown clinical feature of CDS that could gradually develop with age. Thyroid ultrasound showed an abnormal aspect in all investigated patients (6 with thyroid impairment and 3 with normal thyroid function). Cervical MRI done in 2 patients with thyroid impairment showed fat infiltration of thyroid parenchyma. Audiogram carried out in 8 of our patients showed sensorineural hearing impairment in all patients, although only 2 patients suffered from clinical hypoacusia. We also demonstrated that kidney could be a more commonly involved organ than previously reported in the literature. A poorly differentiated kidney parenchyma is a common feature in our series. One patient showed cerebellar atrophy and T2 hypersignal of brain’s white matter in MRI. All patients carried the same founder mutation c.773(− 1)G > A in the ABDH5 gene.

Discussion

Aside from the congenital ichthyosiform erythroderma, the most common symptom of CDS, in addition to other organs involvement frequently reported in the literature, we described thyroid dysfunction, an unreported feature, probably related to the lipid infiltration of the thyroid parenchyma. The association found between age and hypothyroidism in CDS patients could explain the gradually development of thyroid disease with age.

Conclusion

We reported a thyroid dysfunction and unreported ultrasonographic aspects of kidneys and cerebral MRI in CDS patients.

Methods

We performed clinical analyses in 15 patients in whom thyroid, liver, ocular, kidney, skeletal muscle and neurological involvement were explored. Genetic and molecular explorations were performed by direct sequence analysis. Software SPSS, Fisher’s exact test and ANOVA were used for statistical analyses.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1095-4) contains supplementary material, which is available to authorized users.

Analysis of two susceptibility SNPs in HLA region and evidence of interaction between rs6457617 in HLA-DQB1 and HLA-DRB1*04 locus on Tunisian rheumatoid arthritis

Previous genomewide association studies (GWAS) and meta-analyses have enumerated several genes/loci in major histocompatibility complex region, which are consistently associated with rheumatoid arthritis (RA) in different ethnic populations. Given the genetic heterogeneity of the disease, it is necessary to replicate these susceptibility loci in other populations. In this case, we investigate the analysis of two SNPs, rs13192471 and rs6457617, from the human leukocyte antigen (HLA) region with the risk of RA in Tunisian population. These SNPs were previously identified to have a strong RA association signal in several GWAS studies. A case-control sample composed of 142 RA patients and 123 healthy controls was analysed. Genotyping of rs13192471 and rs6457617 was carried out using real-time PCR methods by TaqMan allelic discrimination assay. A trend of significant association was found in rs6457617 TT genotype with susceptibility to RA (P = 0.04, pc = 0.08, OR = 1.73). Moreover, using multivariable analysis, the combination of rs6457617*TT-HLA-DRB1*04+ increased risk of RA (OR = 2.38), which suggest a gene-gene interaction event between rs6457617 located within the HLA-DQB1 and HLA-DRB1. Additionally, haplotypic analysis highlighted a significant association of rs6457617*T-HLA-DRB1*04+ haplotype with susceptibility to RA (P = 0.018, p_c = 0.036, OR = 1.72). An evidence of association was shown subsequently in antiCCP+ subgroup with rs6457617 both in T allele and TT genotype (P = 0.01, p_c = 0.03, OR = 1.66 and P = 0.008, p_c = 0.024, OR = 1.28, respectively). However, no association was shown for rs13192471 polymorphism with susceptibility and severity to RA. This study suggests the involvement of rs6457617 locus as risk variant for susceptibility/severity to RA in Tunisian population. Secondly, it highlights the gene-gene interaction between HLA-DQB1 and HLA-DRB1.

Cytochrome C oxydase deficiency: SURF1 gene investigation in patients with Leigh syndrome

Leigh syndrome (LS) is a rare progressive neurodegenerative disorder occurring in infancy. The most common clinical signs reported in LS are growth retardation, optic atrophy, ataxia, psychomotor retardation, dystonia, hypotonia, seizures and respiratory disorders. The paper reported a manifestation of 3 Tunisian patients presented with LS syndrome. The aim of this study is the MT[HYPHEN]ATP6 and SURF1 gene screening in Tunisian patients affected with classical Leigh syndrome and the computational investigation of the effect of detected mutations on its structure and functions by clinical and bioinformatics analyses. After clinical investigations, three Tunisian patients were tested for mutations in both MT-ATP6 and SURF1 genes by direct sequencing followed by in silico analyses to predict the effects of sequence variation. The result of mutational analysis revealed the absence of mitochondrial mutations in MT-ATP6 gene and the presence of a known homozygous splice site mutation c.516-517delAG in sibling patients added to the presence of a novel double het mutations in LS patient (c.752-18 A > C/c. c.751 + 16G > A). In silico analyses of theses intronic variations showed that it could alters splicing processes as well as SURF1 protein translation. Leigh syndrome (LS) is a rare progressive neurodegenerative disorder occurring in infancy. The most common clinical signs reported in LS are growth retardation, optic atrophy, ataxia, psychomotor retardation, dystonia, hypotonia, seizures and respiratory disorders. The paper reported a manifestation of 3 Tunisian patients presented with LS syndrome. The aim of this study is MT-ATP6 and SURF1 genes screening in Tunisian patients affected with classical Leigh syndrome and the computational investigation of the effect of detected mutations on its structure and functions. After clinical investigations, three Tunisian patients were tested for mutations in both MT-ATP6 and SURF1 genes by direct sequencing followed by in silico analysis to predict the effects of sequence variation. The result of mutational analysis revealed the absence of mitochondrial mutations in MT-ATP6 gene and the presence of a known homozygous splice site mutation c.516-517delAG in sibling patients added to the presence of a novel double het mutations in LS patient (c.752-18 A>C/ c.751+16G>A). In silico analysis of theses intronic vaiations showed that it could alters splicing processes as well as SURF1 protein translation.

First description of a novel mitochondrial mutation in the MT-TI gene associated with multiple mitochondrial DNA deletion and depletion in family with severe dilated mitochondrial cardiomyopathy

Mitochondria are essential for early cardiac development and impaired mitochondrial function was described associated with heart diseases such as hypertrophic or dilated mitochondrial cardiomyopathy. In this study, we report a family including two individuals with severe dilated mitochondrial cardiomyopathy. The whole mitochondrial genome screening showed the presence of several variations and a novel homoplasmic mutation m.4318-4322delC in the MT-TI gene shared by the two patients and their mother and leading to a disruption of the tRNA^Ile secondary structure. In addition, a mitochondrial depletion was present in blood leucocyte of the two affected brother whereas a de novo heteroplasmic multiple deletion in the major arc of mtDNA was present in blood leucocyte and mucosa of only one of them. These deletions in the major arc of the mtDNA resulted to the loss of several protein-encoding genes and also some tRNA genes. The mtDNA deletion and depletion could result to an impairment of the oxidative phosphorylation and energy metabolism in the respiratory chain in the studied patients. Our report is the first description of a family with severe lethal dilated mitochondrial cardiomyopathy and presenting several mtDNA abnormalities including punctual mutation, deletion and depletion.

Clinical, Molecular, and Computational Analysis in two cases with mitochondrial encephalomyopathy associated with SUCLG1 mutation in a consanguineous family

Deficiency of the mitochondrial enzyme succinyl COA ligase (SUCL) is associated with encephalomyopathic mtDNA depletion syndrome and methylmalonic aciduria. This disorder is caused by mutations in both SUCL subunits genes: SUCLG1 (α subnit) and SUCLA2 (β subnit). We report here, two Tunisian patients belonging to a consanguineous family with mitochondrial encephalomyopathy, hearing loss, lactic acidosis, hypotonia, psychomotor retardation and methylmalonic aciduria. Mutational analysis of SUCLG1 gene showed, for the first time, the presence of c.41T > C in the exon 1 at homozygous state. In-silico analysis revealed that this mutation substitutes a conserved methionine residue to a threonine at position 14 (p.M14T) located at the SUCLG1 protein mitochondrial targeting sequence. Moreover, these analysis predicted that this mutation alter stability structure and mitochondrial translocation of the protein. In Addition, a decrease in mtDNA copy number was revealed by real time PCR in the peripheral blood leukocytes in the two patients compared with controls.

Measurement of absolute copy number variation of Glutathione S-Transferase M1 gene by digital droplet PCR and association analysis in Tunisian Rheumatoid Arthritis population

BACKGROUND

The investigation of copy number variations (CNVs) analysis of candidate genes is currently an important research area in modulating human diseases. We aimed to quantify CNVs in glutathione S-transferase M1 (GSTM1) gene and determine its genetic contribution in Tunisian rheumatoid arthritis (RA) and its subsets through an innovative technique for quantification.

METHODS

A total of 165 RA cases and 102 healthy controls were included in the study. Using a recently powerful approach of digital droplet PCR (ddPCR), we quantified GSTM1 gene to determine the presence of no, one, or multiple copy number (CN) at high levels of sensitivity and specificity. Odds ratio and Fisher exact test were performed to estimate the association risk for GSTM1CNVs in RA.

RESULTS

Copy number identified by ddPCR was 0, 1, and 2 copies per diploid genome. A high frequency of '0' copy was revealed with 54% in RA patients. The deletion ('0' copy) of GSTM1 was found to be a significant risk factor for anti-cyclic citrullinated peptide (anti-CCP) positive RA (OR=4.16, CI_95% =[1.17-14.7]). In addition, a lack of association was found when comparing between the CNVs of RA patients and those of controls.

CONCLUSION

This study highlights the powerful accuracy of ddPCR for the quantification of CNVs and suggests that the variation in the CN of GSTM1 is associated with anti-CCP positivity in RA. However, it does not indicate a specific role in the susceptibility to the disease in our Tunisian sample.

Splicing Defects in the AAAS Gene Leading to both Exon Skipping and Partial Intron Retention in a Tunisian Patient with Allgrove Syndrome

BACKGROUND/AIMS

Allgrove syndrome is a rare autosomal recessive disorder characterized by the triad of adrenal insufficiency, achalasia, and alacrima. This syndrome is caused by mutations in the AAAS gene. A major splice site mutation c.1331+1G>A was found previously in North African families affected by Allgrove syndrome. In this study, we analyzed in vivo and in silico the effect of this mutation on the splicing process.

METHODS

Using reverse transcriptase-polymerase chain reaction, sequencing and bioinformatics tools, we analyzed all transcripts produced by the AAAS gene containing this splice site mutation.

RESULTS

The altered splicing of mRNA produces two aberrant transcripts: one with exon 14 skipping, the other with concurrent exon 14 skipping and retention of 99 bp of intron 14, both outcomes resulting in frameshifts with a new stop codon generation in the untranslated region of the last exon. Using in silico bioinformatics tools, we demonstrated that this mutation abolishes the splice donor site of exon 14 and activates a new intronic cryptic splice site in intron 14.

CONCLUSION

This study demonstrated that a single splicing mutation affects the AAAS transcripts and consequently the ALADIN protein structure and function.

A duplex polymerase chain reaction-restriction fragment length polymorphism for rapid screening of methylenetetrahydrofolate reductase gene variants: Genotyping in acute leukemia

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR; NM_005957.4) is the key enzyme for folate metabolism which plays in DNA biosynthesis and the epigenetic process of DNA methylation. MTHFR gene polymorphisms, the c. 677C>T and c. 1298A>C have been implicated as risk factors for several types of cancers as the acute leukemia.

AIM

We have optimized a duplex polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP) for the simultaneous detection of both variants in acute leukemia patients, from Tunisia.

METHODS

Genomic DNA was extracted from EDTA-anticoagulant blood samples from a total of 50 patients suffering from acute leukemia (AL). After DNA extraction, the polymerase chain reaction using specific primers, designed using Primer 3 Software. Restriction Fragment Length Polymorphism (RFLP) was performed in two separate tubes followed by agarose gel electrophoresis.

CONCLUSION

This new method has proved to be a rapid, simple, and reliable method that should facilitate high throughput genotyping of MTHFR polymorphisms in acute leukemia.

Novel cases of Tunisian patients with mutations in the gene encoding 17β-hydroxysteroid dehydrogenase type 3 and a founder effect

17β-Hydroxysteroid dehydrogenase type 3 (17β-HSD3) is expressed almost exclusively in the testis and converts Δ4-androstene-3,17-dione to testosterone. Mutations in the HSD17B3 gene causing 17β-HSD3 deficiency are responsible for a rare recessive form of 46, XY Disorders of Sex Development (46, XY DSD). We report novel cases of Tunisian patients with 17β-HSD3 deficiency due to previously reported mutations, i.e. p.C206X and p.G133R, as well as a case with the novel compound heterozygous mutations p.C206X and p.Q176P. Moreover, the previously reported polymorphism p.G289S was identified in a heterozygous state in combination with a novel non-coding variant c.54G>T, also in a heterozygous state, in a male patient presenting with micropenis and low testosterone levels. The identification of four different mutations in a cohort of eight patients confirms the generally observed genetic heterogeneity of 17β-HSD3 deficiency. Nevertheless, analysis of DNA from 272 randomly selected healthy controls from the same geographic area (region of Sfax) revealed a high carrier frequency for the p.C206X mutation of approximately 1 in 40. Genotype reconstruction of the affected pedigree members revealed that all p.C206X mutation carriers harbored the same haplotype, indicating inheritance of the mutation from a common ancestor. Thus, the identification of a founder effect and the elevated carrier frequency of the p.C206X mutation emphasize the importance to consider this mutation in the diagnosis and genetic counseling of affected 17β-HSD3 deficiency pedigrees in Tunisia.

Molecular Analysis of Libyan Families with Allgrove Syndrome: Geographic Expansion of the Ancestral Mutation c.1331+1G>A in North Africa

BACKGROUND/AIMS

Allgrove syndrome is a rare autosomal recessive disorder characterized by alacrima, achalasia, and adrenal insufficiency. It is caused by mutations of the AAAS gene located on chromosome 12q13 encoding the WD-repeat protein ALADIN. The c.1331+1G>A mutation is one of the most common mutations described in the literature and was identified in Tunisian and Algerian populations. Herein, we describe the clinical and genetic profile of two families from Libya in North Africa associated with Allgrove syndrome.

METHODS

Two unrelated families clinically diagnosed with Allgrove syndrome were evaluated for sequence variations in the AAAS gene. Blood samples were collected, and isolated DNA derived from the subjects was amplified. The entire sequence of the AAAS gene was analyzed by PCR-RFLP and direct sequencing.

RESULTS

Molecular analysis revealed the major homozygous mutation (c.1331+1G>A) in all patients. The presence of a major mutation in Tunisia, Algeria and, as discovered in this report, in Libya in patients with Allgrove syndrome suggests the existence of an ancestral mutation and a founder effect in North Africa.

CONCLUSIONS

The findings allow for a fast genetic counseling in North African families with Allgrove syndrome. To the best of our knowledge, this is the first report of Allgrove syndrome in Libya.

In silico investigation of the impact of synonymous variants in ABCB4 gene on mRNA stability/structure, splicing accuracy and codon usage: Potential contribution to PFIC3 disease

Progressive Familial Intrahepatic Cholestasis type 3 (PFIC3) is an autosomal-recessive liver disease due to mutations in the ABCB4 gene encoding for the MDR3 protein. In the present study, we performed molecular and bioinformatic analyses in PFIC3 patients in order to understand the molecular basis of the disease. The three studied patients with PFIC3 were screened by PCR amplification followed by direct sequencing of the 27 coding exons of ABCB4. In silico analysis was performed by bioinformatic programs. We revealed three synonymous polymorphisms c.175C>T, c.504C>T, c.711A>T respectively in exon 4, 6, 8 and an intronic c.3487-16T>C variation in intron 26. The computational study of these polymorphic variants using Human Splicing Finder, ex-skip, Mfold and kineFold tools showed the putative impact on the composition of the cis-acting regulatory elements of splicing as well as on the mRNA structure and stability. Moreover, the protein level was affected by codon usage changes estimated by the calculation of ΔRSCU and ΔLog Ratio of codon frequencies interfering as consequence with the accurate folding of the MDR3 protein. As the first initiative of the mutational study of ABCB4 genes in Tunisia, our results are suggestive of a potential downstream molecular effect for the described polymorphisms on the expression pattern of the ABCB4 underlining the importance of synonymous variants.

A de-novo large deletion of 2.8 kb produced in the ABCD1 gene causing adrenoleukodystrophy disease

X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative disorder caused by mutations in the ABCD1 gene, which encodes an ATP-binding cassette transporter protein, ALDP. The disease is characterized by increased concentrations of very long chain fatty acids (VLCFAs) in plasma, adrenal, testicular, and nerve tissues. For this study, our objective was to conduct clinical, molecular, and genetic studies of a Tunisian patient with X-ALD. The diagnosis was based on clinical indications, biochemical analyses, typical brain-scan patterns, and molecular biology; the molecular analyses were based on PCR, long-range PCR, and sequencing. The molecular analysis by long-range PCR and direct sequencing of the ABCD1 gene showed the presence of a de-novo 2794 bp deletion covering the whole of exon 2. Using bioinformatics tools, we demonstrate that the large deletion is located in a region rich with Alu sequences. Furthermore, we suggest that the AluJb sequence could be the cause of the large deletion of intron 1, exon 2, and intron 2, and the creation of a premature stop codon within exon 3. This report is the first report in which we demonstrate the breakpoints and the size of a large deletion in a Tunisian with X-ALD.

Antioxidant effect of hydroxytyrosol on human sperm quality during in vitro incubation

The aim of the study was to evaluate the antioxidant potential of hydroxytyrosol (HT) on human sperm quality during incubation in vitro. Semen samples collected from men attending the Laboratory of Histology-Embryology of Sfax Faculty of Medicine (Tunisia) for infertility investigations were evaluated for initial sperm parameters. Only normal selected ejaculates (n = 15) were centrifuged and incubated further with or without HT (200ug ml^-1 ) at room temperature for 45 min. After incubation, sperm motility and viability, DNA oxidation and reactive oxygen species (ROS) production were assessed. The results showed that centrifugation significantly influenced sperm motility and viability. The supplementation of HT in incubating media improved (P = 0.01) significantly sperm viability and decreased sperm DNA oxidation (P < 0.001) and ROS levels (P = 0.03) following centrifugation. It can be concluded that supplementation of HT might be helpful to maintain the human spermatozoon after centrifugation.

Mitochondrial DNA triplication and punctual mutations in patients with mitochondrial neuromuscular disorders

Mitochondrial diseases are a heterogeneous group of disorders caused by the impairment of the mitochondrial oxidative phosphorylation system which have been associated with various mutations of the mitochondrial DNA (mtDNA) and nuclear gene mutations. The clinical phenotypes are very diverse and the spectrum is still expanding. As brain and muscle are highly dependent on OXPHOS, consequently, neurological disorders and myopathy are common features of mtDNA mutations. Mutations in mtDNA can be classified into three categories: large-scale rearrangements, point mutations in tRNA or rRNA genes and point mutations in protein coding genes. In the present report, we screened mitochondrial genes of complex I, III, IV and V in 2 patients with mitochondrial neuromuscular disorders. The results showed the presence the pathogenic heteroplasmic m.9157G>A variation (A211T) in the MT-ATP6 gene in the first patient. We also reported the first case of triplication of 9 bp in the mitochondrial NC7 region in Africa and Tunisia, in association with the novel m.14924T>C in the MT-CYB gene in the second patient with mitochondrial neuromuscular disorder.

Mutational analysis in patients with neuromuscular disorders: Detection of mitochondrial deletion and double mutations in the MT-ATP6 gene

Mitochondrial diseases encompass a wide variety of pathologies characterized by a dysfunction of the mitochondrial respiratory chain resulting in an energy deficiency. The respiratory chain consists of five multi-protein complexes providing coupling between nutrient oxidation and phosphorylation of ADP to ATP. In the present report, we studied mitochondrial genes of complex I, III, IV and V in 2 Tunisian patients with mitochondrial neuromuscular disorders. In the first patient, we detected the m.8392C>T variation (P136S) in the mitochondrial ATPase6 gene and the m.8527A>G transition at the junction MT-ATP6/MT-ATP8 which change the initiation codon AUG to GUG. The presence of these two variations in such an important gene could probably affect the ATP synthesis in the studied patient. In the second patient, we detected several known variations in addition to a mitochondrial deletion in the major arc of the mtDNA eliminating tRNA and respiratory chain protein genes. This deletion could be responsible of an inefficient translation leading to an inefficient mitochondrial protein synthesis in P2.

Biochemical analyses and molecular modeling explain the functional loss of 17β-hydroxysteroid dehydrogenase 3 mutant G133R in three Tunisian patients with 46, XY Disorders of Sex Development

Mutations in the HSD17B3 gene resulting in 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) deficiency cause 46, XY Disorders of Sex Development (46, XY DSD). Approximately 40 different mutations in HSD17B3 have been reported; only few mutant enzymes have been mechanistically investigated. Here, we report novel compound heterozygous mutations in HSD17B3, composed of the nonsense mutation C206X and the missense mutation G133R, in three Tunisian patients from two non-consanguineous families. Mutants C206X and G133R were constructed by site-directed mutagenesis and expressed in HEK-293 cells. The truncated C206X enzyme, lacking part of the substrate binding pocket, was moderately expressed and completely lost its enzymatic activity. Wild-type 17β-HSD3 and mutant G133R showed comparable expression levels and intracellular localization. The conversion of Δ4-androstene-3,17-dione (androstenedione) to testosterone was almost completely abolished for mutant G133R compared with wild-type 17β-HSD3. To obtain further mechanistic insight, G133 was mutated to alanine, phenylalanine and glutamine. G133Q and G133F were almost completely inactive, whereas G133A displayed about 70% of wild-type activity. Sequence analysis revealed that G133 on 17β-HSD3 is located in a motif highly conserved in 17β-HSDs and other short-chain dehydrogenase/reductase (SDR) enzymes. A homology model of 17β-HSD3 predicted that arginine or any other bulky residue at position 133 causes steric hindrance of cofactor NADPH binding, whereas substrate binding seems to be unaffected. The results indicate an essential role of G133 in the arrangement of the cofactor binding pocket, thus explaining the loss-of-function of 17β-HSD3 mutant G133R in the patients investigated.

Phenotypic variability in a Tunisian family with X-linked adrenoleukodystrophy caused by the p.Gln316Pro novel mutation

INTRODUCTION

X-linked adrenoleukodystrophy is a neurodegenerative recessive disorder that affects the brain white matter and associated with adrenal insufficiency. It is characterized by an abnormal function of the peroxisomes, which leads to an accumulation of the Very Long Chain Fatty Acids (VLCFA) in plasma and tissues, especially in the cortex of the adrenal glands and the white matter of the central nervous system. Mutations in the ABCD1 gene affect the function of the encoded protein ALDP, an ATP-binding cassette transporter located in the peroxisomal membrane protein.

PATIENTS AND METHODS

The present study reports the clinical, biochemical and molecular investigation in a Tunisian family with two affected males with childhood cerebral adrenoleukodystrophy.

RESULTS

The ABCD1 gene sequencing indicated a novel hemizygous missense mutation c.947A>C (p.Gln316Pro) in the exon 2 of the ABCD1 gene in the patients, their mother and their sisters. This missense variation was predicted to be possibly damaging by the PolyPhen and SIFT prediction software. Although presence of the same mutation c.947A>C in both siblings, they present different clinical signs.

CONCLUSIONS

Based on the disease's progress, the clinical signs and biochemical aspects between the two siblings, we demonstrate that there is no correlation genotype-phenotype.

Association study of MICA gene polymorphisms with rheumatoid arthritis susceptibility in south Tunisian population

The aim of this study was to investigate the role of major histocompatibility complex (MHC) class I chain-related gene A (MICA) polymorphisms, important in natural killer (NK) cell function, in patients with rheumatoid arthritis (RA). A transmembrane (TM) alanine-encoding GCT repeats, termed A4, A5, A5.1, A6 and A9 in the MICA gene, and single-nucleotide polymorphisms (SNPs): the Met129Val polymorphism (rs1051792) and the nonsynonymously coding SNP (rs1051794) were genotyped in 142 patients with RA and 123 unrelated healthy individuals using, respectively, PCR fluorescent method, nested PCR-RFLP and allele specific PCR (ASP). Association was assessed based on the χ2 test, genotype relative risk (GRR) and odds ratio (OR) with 95% confidence intervals (CIs). Our results show a trend of association of the different MICA genotypes G/G, G/A and A/A (P = 0.029) which did not attain the significance after Bonferroni's correction (pc = 0.08). Although, we revealed a significant association of the genotype A/A of MICA-250 in patients with RA compared to healthy controls (pc = 0.033). In contrast, no significant differences between alleles and genotypes frequencies were found either with MICA-TM or MICA met129 val (P > 0.05) in our sample. Moreover, stratification of patients with RA according to clinical and immunological data for the different polymorphisms studied shows a significant association of both MICA-250 G allele (pc = 0.0075) and MICA-250 GG genotype (pc = 0.008) and both allelic (val) (pc = 0.021) and genotypic (val/val) distribution (pc = 0.0095) for MICA met129 val in the RF-positive subgroup compared to RF-negative patients with RA. In contrast, we found a strong association of the MICA-TM A9 allele in RF-negative patients with RA (pc = 0.0003). This study indicates the involvement of the MICA-250 polymorphism in the genetic susceptibility and severity to RA and suggests that variations in MICA-TM and MICA met129 val may have an effect on RA severity in our south Tunisian sample.

Molecular detection of Chlamydia trachomatis and other sexually transmitted bacteria in semen of male partners of infertile couples in Tunisia: the effect on semen parameters and spermatozoa apoptosis markers

This study was undertaken to determine the prevalence of Chlamydia trachomatis, Mycoplasmas, and Ureaplasmas in semen samples of the male partners of infertile couples and to investigate whether Chlamydia trachomatis could initiate apoptosis in human spermatozoa. A total of 85 males partners of infertile couples undergoing routine semen analysis according to World Health Organization guidelines were included. Specimens were examined for the presence of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum and Ureaplasma parvum by Real time PCR (qPCR). Semen specimens were analysed for the appearance of apoptotic markers (sperm DNA fragmentation, activated caspase 3 levels, mitochondrial membrane potential (ΔΨm)) using flow cytometry. C. trachomatis, N. gonorrhoeae, U. urealyticum, M genitalium were detected in semen samples of 13 (15.2%), 5 (5.8%), 5 (5.8%) and 3 (3.5%) male partners of infertile couples, respectively. M. hominis and U. parvum were detected in semen sample of only one patient (1.1%). The semen of infertile men positive for C. trachomatis showed lower mean of semen count and lower rapid progressive motility (category [a]) of spermatozoa compared to uninfected men with statistically significances (p = 0.02 and p = 0.04, respectively). Flow cytometry analyses demonstrated a significant increase of the mean rate of semen with low ΔΨm and caspase 3 activation of infertile men positive for C. trachomatis compared to uninfected men (p = 0.006 and p = 0.001, respectively). DNA fragmentation was also increased in sperm of infertile men positive for C. trachomatis compared to uninfected men but without statistical significances (p = 0.62). Chlamydial infection was associated to loss of ΔΨm and caspase 3activation. Thus, C. trachomatis infection could be incriminated in apoptosis induction of spermatozoa. These effects may explain the negative direct impact of C. trachomatis infection on sperm fertilizing ability.

Quercetin attenuates lambda cyhalothrin-induced reproductive toxicity in male rats

The aim of this study was to evaluate the possible protective effects of Quercetin (Qe) against oxidative stress induced by λ cyhalothrin (LTC) in reproductive system. Thirty-two male rats were divided into four groups. First group was allocated as the control group. Second group was given a Qe alone while the third group received a LTC alone. Animals in the fourth group were given a Qe with LTC. Caudae epididymis was removed for sperm analysis. Lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), and reduced glutathione (GSH) were determined in the testis. Additionally, the different histopathologic changes were observed in the testis of animals. LTC exposure significantly increased the abnormal morphology and LPO. On the contrary, sperm motility, viability and count, levels of GSH, and activities of SOD, CAT, GPx, and GST were significantly decreased compared to controls. Qe with LTC offset the decrease in functional sperm parameters, antioxidants enzymatic activities, and nonenzymatic antioxidant levels when compared with LTC-treated rats. Furthermore, LTC showed irregular seminiferous tubules containing only Sertoli cells and Qe with LTC caused regular seminiferous tubules showing spermatogenesis at level of spermatocytes. We conclude that LTC-induced oxidative stress and functional sperm parameters in male rats, and dietary of Qe attenuates the reproductive toxicity of LTC to restore the antioxidant system and sperm parameters in male rats.

Assessment of chromatin maturity in human spermatozoa: useful aniline blue assay for routine diagnosis of male infertility

During spermatogenesis, sperm chromatin undergoes structural changes and results in a high condensation. This nuclear compaction would be useful as a predictor of sperm fertilization capacity and pregnancy outcome. We purpose to evaluate firstly the relationship among chromatin maturity assessed by aniline blue staining (AB) and the semen parameters in infertile men. Secondly, we analyzed whether the sperm gradient density centrifugation is effective to select mature spermatozoa. Fifty-one ejaculates were investigated by semen analysis and stained for chromatin condensation with AB to distinguish between unstained mature sperm and stained immature sperm. AB was applied also on 12 ejaculates which proceeded by density gradient centrifugation to compare the rates of immature sperm before and after selection. Neat semen were divided into two groups: G1 (n = 31): immature sperm <20% and G2 (n = 20): immature sperm ≥20%. No significant differences were detected in sperm concentration, motility, and normal morphology between G1 and G2. However, the rates of some morphology abnormalities were higher in G2: head abnormalities (P = 0.01) and microcephalic sperm (P = 0.02). We founded significant correlation between sperm immaturity and acrosome abnormalities (r = 0.292; P = 0.03). Sperm selection has significantly reduced the rates of immature sperm. A better understanding of chromatin structure and its impact on the sperm potential is needed to explore male infertility.

Caffeic acid and quercetin protect erythrocytes against the oxidative stress and the genotoxic effects of lambda-cyhalothrin in vitro

Lambda-cyhalothrin (LTC) is a synthetic pyrethroid with a broad spectrum of insecticidal and acaricidal activities used to control wide range of insect pests in a variety of applications. The aim of this study was to examine (i) the potency of LTC to induce oxidative stress response in rat erythrocytes in vitro and (ii) the role of caffeic acid (20 μM) and/or quercetin (10 μM) in preventing the cytotoxic effects. Erythrocytes were divided into four portions. The erythrocytes of the first portion were incubated for 4 h at 37°C with different concentrations (0, 50 and 100 μM) of LTC. The others portions were pretreated with caffeic acid and/or quercetin for 30 min prior to LTC incubation. Lipid peroxidation, protein oxidation, antioxidant enzyme activities and DNA damage were examined. LTC at different concentrations causes increased levels of lipid peroxidation, protein oxidation, DNA damage and decreased antioxidant enzyme activities. Combined caffeic acid and quercetin pretreatments significantly reduced the levels of lipid peroxidation markers, that is thiobarbituric acid reactive substance (TBARS), protein carbonyls (PCO) and decreased DNA damage in LTC portion. Further, combined caffeic acid and quercetin pretreatment maintain antioxidant enzyme activities and glutathione content near to normal values. These results suggest that LTC exerts its toxic effect by increasing lipid peroxidation, altering the antioxidant enzyme activities and DNA damage. Caffeic acid and quercetin pretreatments prevent the toxic effects of LTC, suggesting their role as a potential antioxidant.

Protective role of caffeic acid on lambda cyhalothrin-induced changes in sperm characteristics and testicular oxidative damage in rats

The synthetic pyrethroids are expected to cause deleterious effects on most of the organs and especially on the male reproductive system. The current study was performed to assess the adverse effect of lambda cyhalothrin (LC) on reproductive organs and fertility in male rats and to evaluate the protective role of caffeic acid phenethyl ester (CAPE) in alleviating the detrimental effect of LC on male fertility. A total of 48 male rats were divided into 4 groups (12 rats each): control group received distilled water ad libitum and 1 ml of vehicle solution given intraperitoneally (i.p.); CAPE-treated group received a single i.p. dose of CAPE (10 μmol kg⁻¹ day⁻¹); LC-treated group received 668 ppm of LC through drinking water; and CAPE + LC-treated group received an i.p. injection of CAPE (10 μmol kg⁻¹ day⁻¹) 12 h before the LC administration. The experiment was conducted for 10 consecutive weeks. LC caused a significant increase in testicular malondialdehyde, catalase, superoxide dismutase, glutathione-S-transferase activities, and sperm abnormalities and a significant reduction in testicular glutathione concentration, sperm count, sperm motility, and a live sperm percentage. Conversely, treatment with CAPE improved the reduction in the sperm characteristics, LC-induced oxidative damage of testes and the testicular histopathological alterations. Results indicate that LC exerts significant harmful effects on the male reproductive system and that CAPE reduced the deleterious effects of LC on male fertility.

Analysis of azoospermia factor loci polymorphisms among Tunisian infertile men with varicocele

AIMS

The preponderance of experimental data from clinical and animal models demonstrates an adverse effect of varicocele on spermatogenesis. The review of the literature shows that there may be an underlying genetic etiology in varicocele. Here, we explore the Yq microdeletions among infertile men to evaluate their involvement in varicocele development and sperm production defect.

RESULTS

Microdeletions of 14 sequence-tagged-sites in the Yq11 region were screened in 210 infertile men using polymerase chain reaction techniques. Out of 210 infertile men, 69 (33%) men were with varicocele. Our results showed that the risk to develop varicocele is increased among infertile men with spermatogenesis (oligo-normospermia) (odds ratio = 3.57, confidence interval 95%: 1.49-8.84). However, we did not find any relationship between Y chromosome microdeletions and varicocele appearance (p = 0.73). In addition, a significant association was found between Y microdeletions and oligospermia (p < 10(-8)) or azoospermia (p < 10(-8)) using patients with normospermic characteristics as a control.

CONCLUSION

Our work showed the absence of relationship between Y chromosome microdeletions and varicocele development and the association of the two factors, independently, with sperm production defect.

EVALUATION OF DAZ MICRODELETIONS IN 34 INFERTILE MEN

Microdeletions in Yq11 are a common molecular cause of spermatogenic failure in men and are recurrently detected in about 10-15% of idiopathic azoospermia and severe oligozoospermia. Screening for AZF microdeletions is often performed by multiplex PCR. AZFc deletions, involving the DAZ gene, form the majority of these deletions. The aim of this study was to evaluate in a group of 34 Tunisian infertile patients (16 oligozoospermic and 18 azoospermic men) the prevalence of DAZ microdeletions using a rapid molecular strategy: the PCR-DGGE method based on the high degree of homology between the DAZ gene and its autosomally equivalent DAZLA gene. DAZ microdeletions were detected in 8.8% of patients. The three deleted patients have a 46, XY karyotype. Two of them were azoospermic and the other had an extreme oligo-asthenoteratozoospermia with a predominant abnormality: small round head spermatozoa (Y46). Our findings suggest that PCR-DGGE method, for detection of DAZ gene deletion, could be particularly useful as a first step in the diagnosis workup of nonobstructive azoospermia and severe oligozoospermia for three reasons. First, it is a simple and fast system; second, DAZ microdeletions are the most common Y deletions; and third, partial DAZ microdeletions and mosaicism may be recognized by PCR-DGGE while only deletions removing the whole DAZ gene cluster can be detected by STS-PCR [211]. Nevertheless, this procedure has limitations because other deletions of AZFa and AZFb may go undetected. Therefore, molecular investigation by multiplex PCR must be conducted in a second step according to European guidelines for the molecular diagnosis of Y chromosome microdeletions, particularly before ICSI procedures.

Ureaplasma urealyticum, Ureaplasma parvum, Mycoplasma hominis and Mycoplasma genitalium infections and semen quality of infertile men

Background

Genital ureaplasmas (Ureaplasma urealyticum and Ureaplasma parvum) and mycoplasmas (Mycoplasma genitalium and Mycoplasma hominis) are potentially pathogenic species playing an etiologic role in both genital infections and male infertility. Reports are, however, controversial regarding the effects of these microorganisms infections in the sperm seminological variables. This study aimed at determining the frequency of genital ureplasmas and mycoplasmas in semen specimens collected from infertile men, and at comparing the seminological variables of semen from infected and non-infected men with these microorganisms.

Methods

A total of 120 semen samples collected from infertile men were investigated. Semen specimens were examined by in-house PCR-microtiter plate hybridization assay for the presence of genital ureaplasmas and mycoplasmas DNA. Semen analysis was assessed according to the guidelines of the World Health Organization. Standard parametric techniques (t-tests) and nonparametric techniques (Wilcoxon tests) were used for statistical analysis.

Results

The frequency of genital ureaplasmas and mycoplasmas detected in semen samples of infertile men was respectively 19.2% (23/120) and 15.8% (19/120). The frequency of Ureaplasma urealyticum (15%) was higher than that of Mycoplasma hominis (10.8%), Ureaplasma parvum (4.2%) and Mycoplasma genitalium (5%). Mixed species of mycoplasmas and ureaplasmas were detected in 6.7% of semen samples.

Comparison of the parameters of the standard semen analysis between the male partners of the infertile couples with and without genital ureaplasmas and mycoplasmas infection showed that the presence of Mycoplasma hominis DNA in semen samples is associated with low sperm concentration (p = 0.007) and abnormal sperm morphology (p = 0.03) and a negative correlation between sperm concentration and the detection of Mycoplasma genitalium in semen samples of infertile men (p = 0.05). The mean values of seminal volume, pH, vitality, motility and leukocyte count were not significantly related either to the detection of genital mycoplasmas DNA or to the detection of ureaplasmas DNA in semen specimens.

Conclusion

Our results demonstrate that genital mycoplasmas and ureaplasmas seem to be widespread among the male partners of infertile couples in Tunisia. Genital mycoplasmas infections of the male genital tract could negatively influence semen quality. Our results also indicate that PCR-microtiter plate hybridization assay method provides a rapid and effective technique to detect human genital mycoplasmas and ureaplasmas which is useful for etiological and epidemiological studies of these pathogens.

Date seed oil limit oxidative injuries induced by hydrogen peroxide in human skin organ culture

The skin is chronically exposed to pro-oxidant agents, leading to the generation of reactive oxygen species (ROS). To protect the skin against an over-load of oxidant species, we studied the chemoprotective effect of one new natural product: "date seed oil: DSO". This oil may serve as a potential source of natural antioxidants such as phenols and tocopherols. Here, the antioxidative potential of DSO was compared that of to extra virgin olive oil. Adult human skin was maintained in organ culture in the presence of the DSO and extra virgin olive oil before the addition of hydrogen peroxide (H2O2), in order to prevent the tissue from its oxidizing effects. Skin specimens were collected for histology and for melanin studies. In the investigated model system, DSO protects skin against oxidative injuries. It has a significant chemoprotective effect, by inhibition of damage caused by H_{2}O_{2} compared with specimens without such addition endowing with a radical scavenging ability. The various components from DSO were much more potent antioxidant and more free radical scavengers of the H2O2 than those of olive oil. Our study shows that topical DSO treatment of the skin stimulates events in the epidermis leading to repair skin damage possibly due to antioxidant synergisms.

[Hemodynamics and microcirculation in a rat poisoned by scorpion venom]]

The clinic table of serious scorpionic envenimation is dominated by cardiovascular and pulmonary perturbations. The physiopathology of cardiac failure in man as well as at animal is again badly elucidated. The aim of our study has consisted in evaluating the hemodynamic variations of the Rat poisoned by the venom of the Buthus occitanus scorpion and to contribute through the analyse of plasmatic concentrations of catecholamines and by an histomorphometric study of muscular microcirculation to explain the mechanism of the hemodynamic perturbations and cardiac failure. 51 rats corresponding to 9 groups (witness and poisoned) have been used. The venom of the scorpion Buthus occitanus has been administrated at 850 micrograms/kg. Two groups have been served for hemodynamic study, three groups for the dosage of catecholamines and four groups for histomorphometric study. It has been observed a biphasic variation of arterial pressure and cardiac frequency after venom injection. Four minutes after envenimation, the plasmatic level of catecholamines was strongly higher in the poisoned according to the witness one. Histomorphometric study of muscular skeletal microcirculation has shown a decrease of relative vascular volume contemporary with the increase of plasmatic catecholamines concentration and the peak of arteriel pressure appeared just after envenimation. 10 and 20 minutes after envenimation, the relative vascular volume has significantly increased as well as that interstitium according to witness lot. These hemodynamic perturbations can be attributed to the important dump in catecholamines. This hyperadrenergy was contemporary with decrease of relative muscular vascular volume. This decrease would be explained by a constriction of vessels. On the other hand, the second increase of the vascular relative volume suggests the possibility of development of venous stasis at the muscular microcirculation. It would be induced by a cardiac failure and/or the effect of vasoplegic mediators being able to entail an interstitial oedema in the muscular skeletal that would led to increase the relative interstitial volume observed in this study.

Intra- and inter-individual variability in human sperm concentration, motility and vitality assessment during a workshop involving ten laboratories

The aim of the present study was to assess variability in the evaluation of human sperm concentration, motility and vitality. Technicians and biologists from 10 teams involved in multicentre studies on semen quality attended the same laboratory, each team using its own methods and equipment to analyse the same semen samples. Inter-individual variability was assessed from 17 fresh semen samples of varying quality. Intra-individual variability was assessed from pools of frozen samples for sperm concentration and motility and stained smears for vitality with three blind evaluations by sample and smear. The mean inter-individual coefficients of variation were 22.9, 21.8 and 17.5% for sperm concentration, motility and vitality respectively. There was no statistical difference among participants for sperm concentration assessment, but significant differences for both motility and vitality (both P: < 0.05). The mean intra-individual coefficients of variation were 15.8, 26.2 and 13.1% for sperm concentration, motility and vitality respectively, with marked differences between expert and novice participants: concentration 9.8% versus 28.0%; motility 22.8% versus 33.0%; and vitality 10.0% versus 19.3%. The present data confirm the need for external quality control schemes for diagnostic purposes, and indicate their utmost importance in multicentre studies on semen quality.

The reactivation of demembranated human spermatozoa lacking outer dynein arms is independent of pH

The effect of pH, Mg-ATP, and free calcium on activity of the inner dynein arm was investigated using demembranated human spermatozoa lacking the outer dynein arms (LODA). The results were compared with those obtained for demembranated-reactivated normal spermatozoa to evaluate the functional properties of the inner and outer dynein arms in axonemal motility. The reactivation of Triton X-100-demembranated LODA spermatozoa was analysed at various pHs and concentrations of Mg-ATP and calcium using video recordings. The percentage of reactivated LODA spermatozoa as a function of Mg-ATP concentration was not dependent on pH, whereas reactivation of normal human spermatozoa is pH dependent. This suggests that there may be a pH-dependent regulatory mechanism associated with the outer dynein arms. A delay in the principal bend propagation of normal and LODA reactivated cells was found at pH 7.1. This disappeared at pH 7.8 in normal but not in LODA populations. This suggests a role for outer dynein arms in the initiation of the propagation of flagellar bends at alkaline pH. The level of LODA and normal sperm reactivation both depended on the calcium concentration in the medium. At lower free calcium concentrations, the reactivation level and beat frequency of reactivated cells were higher. Our results suggest a functional difference between outer and inner dynein arms of human spermatozoa based on a differential pH sensitivity. Moreover, calcium seems to exert its regulatory action elsewhere than on the outer dynein arms.