Biomedical subjects

Hayat Dagher

Publications and source records attributed to Hayat Dagher.

8 recordsLinked to original sources

PubMed2006

Characterization of the peripheral retinopathy in X-linked and autosomal recessive Alport syndrome.

BACKGROUND: Alport syndrome is an inherited disease resulting in kidney failure, hearing loss and ocular abnormalities. Alport syndrome is however often unrecognized, and the aim of this study was to characterize the associated but rarely described peripheral retinopathy and determine whether its demonstration was diagnostically helpful. METHODS: Index cases were diagnosed with Alport syndrome on renal biopsy in themselves or a family member. Inheritance and affected status were determined using microsatellite markers at the COL4A5 and COL4A3/COL4A4 loci, respectively. Participants' eyes were dilated, and examined with direct and indirect ophthalmoscopy, and slit lamp biomicroscopy by an expert ophthalmologist who was unaware of the patients' disease status. RESULTS: Ten males and nine females with X-linked Alport syndrome and seven with autosomal recessive disease were studied. Of the 26 patients, 16 had central retinopathy (62%), and 19 patients had peripheral retinopathy (74%). The peripheral changes occurred in both males and females with X-linked and autosomal recessive Alport syndrome, and were more common when renal failure, hearing loss, lenticonus and the central changes were present, but were also noted in 3 X-linked carriers with normal renal function. CONCLUSIONS: The peripheral retinopathy occurs in X-linked and autosomal recessive Alport syndrome even when the central retinopathy is absent. Careful retinal examination and photography that includes the periphery is a safe and inexpensive method that may help in the diagnosis of Alport syndrome especially in carriers of X-linked disease.

Adolescent↗

PubMed2006

Vascular endothelial growth factor induction by rhinovirus infection.

Vascular participation manifested by a runny nose (rhinorrhea) is a prominent feature of the acute consequences of rhinovirus infection. Vascular endothelial growth factor (VEGF) is an angiogenic factor that also induces potent increases in vascular permeability; it is a candidate mediator of rhinorrhea in response to rhinovirus infection as well as contributing to enhanced vascular leakage in rhinovirus-linked asthma exacerbations. It has been shown that rhinovirus induces significant increases in both VEGF protein and mRNA in primary airway fibroblasts [Ghildyal et al. (2005): J Med Virol 75:608-615]. The current studies assessed VEGF responses to rhinovirus in primary culture airway epithelium, in epithelial and fibroblast cell lines and in rhinovirus-infected nasal secretions. Epithelial and fibroblast cells were infected with rhinovirus serotype 16 and VEGF protein and isoforms assessed by ELISA and RT-PCR, respectively. VEGF protein was released by both epithelial and fibroblast cell lines and primary airway epithelial cells in culture but was not increased following rhinovirus infection. PCR products coding for four or five of the six known VEGF isoforms were produced (121, 145, 165 and 183, and/or 189 amino acids) in cell lines and primary culture cells, but no specific isoform was linked to rhinovirus infection. Nasal VEGF was also measured in a cohort of asthmatics with verified rhinovirus and respiratory syncytial virus (RSV) infection. VEGF was not raised following rhinovirus infection alone, but was increased significantly if concomitant RSV infection was present. The data suggest that fibroblasts rather than the epithelium may play a key role in VEGF mediated vascular responses after rhinovirus infection. This may aid recruitment of inflammatory cells and contribute to airway inflammation and bronchial obstruction.

Asthma↗

PubMed2005

Rhinovirus infects primary human airway fibroblasts and induces a neutrophil chemokine and a permeability factor.

The events linking rhinovirus (RV) infection to airway symptoms are poorly understood. The virus initially infects airway epithelium followed by a vigorous inflammatory response that may entail spread of RV from epithelium to other cells in the airway wall. However, RV has fastidious growth characteristics and to date reproductive infection of primary cells other than human airway epithelium has not been confirmed. Airway fibroblasts are adjacent to and in contact with epithelial cells, play a key role in innate immune responses, and may participate in the evolution of inflammation. To investigate fibroblast actions, we first determined whether RV could infect and replicate in primary culture human lung fibroblasts. RV serotype 16 (RV16) was used to infect fibroblasts grown from lung tissue, and virus infection with replication was demonstrated by a combination of techniques. RT-PCR was used to show an increase in RV transcription; confocal microscopy demonstrated colocalization of the replicative form of RV genome (double-stranded RNA) and RV16 proteins; infectious virus was also recovered from the culture supernatant of infected fibroblasts. Functional consequences of RV infection were next examined. RV infection of fibroblasts was followed by an increase in epithelial neutrophil-activating peptide-78 (ENA-78) mRNA and protein. The permeability factor vascular endothelial growth factor (VEGF) was also induced over a similar time course. These data suggest that interactions between RV and human fibroblasts are feasible, may coordinate neutrophil chemoattraction with enhanced vascular permeability and that fibroblasts may contribute to inflammatory responses following RV infections.

Cells, Cultured↗

PubMed2004

Rhinovirus detection: comparison of real-time and conventional PCR.

Rhinoviruses are important human respiratory viruses and the major causative agents of the common cold. Historically, detection of rhinovirus has been by virus culture and this was significantly improved by the use of PCR assays. Recently real-time PCR was developed but to date there have been no reported comparisons of conventional and real-time PCR assays for detection of rhinovirus. In this study, we first compared real-time PCR (SYBR Green I) to conventional PCR for the detection of rhinovirus in serially diluted standard DNA and rhinovirus stock to determine the limits of detection. Next, assays were compared for sensitivity to detect rhinovirus in cell culture with a known number of infected cells. Finally, the assays were compared using clinical samples known to contain rhinovirus. Real-time PCR was 10-fold more sensitive than conventional PCR to detect rhinovirus in standard DNA and in virus stock and >10-fold more sensitive to detect rhinovirus in cultured cells. Real-time PCR was significantly superior for detection of rhinovirus in patients' nasal aspirates (sensitivity 72% versus 39%, P < 0.05). In summary, we found that real-time PCR was more sensitive than conventional PCR and reduced post-PCR processing. Hence, real-time PCR is suitable for both research and clinical purposes.

Common Cold↗

PubMed2003

Clinical, histopathologic, and genetic studies in nine families with focal segmental glomerulosclerosis.

BACKGROUND: Familial forms of focal segmental glomerulosclerosis (FSGS) are caused by mutations in genes at 1q25-31 (gene for steroid-resistant nephrotic syndrome 2 [NPHS2]), 11q21-22, 19q13 (gene for alpha-actinin 4 and NPHS1), and at additional unidentified chromosomal loci. METHODS: We describe clinical and histopathologic features and results of linkage analysis in nine consecutive index cases with familial FSGS who, together with their families, were referred for genetic studies. RESULTS: Two of the index cases presented in childhood (22%) and seven cases presented in adolescence or adulthood (78%). Six of their families (67%), including the two cases with childhood-onset disease, showed probable autosomal recessive inheritance. FSGS segregated at the 1q25-31 locus in two of these families and at the 11q21-22 locus in four families. None had disease caused by mutations in genes at the 19q13 locus, and no locus was identified in the three remaining families. Clinical features of proteinuria, minimal hematuria, hypertension, preeclampsia, and progressive renal impairment were usually present with autosomal recessive or dominant inheritance and with disease that segregated at the different loci. Eighteen renal biopsies from affected members of eight families showed a strong correlation between tubulointerstitial damage and percentage of obsolescent glomeruli (rho = +0.76; P < 0.01). None of the 13 patients from eight families who underwent transplantation developed recurrent FSGS in their grafts. In general, carriers of autosomal recessive disease had no distinctive clinical features apart from the development of preeclampsia in successive pregnancies. CONCLUSION: Familial forms of FSGS are not uncommon, and presentation frequently is in adolescence or adulthood, even when inheritance is autosomal recessive. Furthermore, carriers of autosomal recessive FSGS often have no distinctive phenotype.

Adolescent↗

PubMed2003

Thin basement membrane nephropathy.

Thin basement membrane nephropathy. Thin basement membrane nephropathy (TBMN) is the most common cause of persistent glomerular bleeding in children and adults, and occurs in at least 1% of the population. Most affected individuals have, in addition to the hematuria, minimal proteinuria, normal renal function, a uniformly thinned glomerular basement membrane (GBM) and a family history of hematuria. Their clinical course is usually benign. However, some adults with TBMN have proteinuria >500 mg/day or renal impairment. This is more likely in hospital-based series of biopsied patients than in the uninvestigated, but affected, family members. The cause of renal impairment in TBMN is usually not known, but may be due to secondary focal segmental glomerulosclerosis (FSGS) or immunoglobulin A (IgA) glomerulonephritis, to misdiagnosed IgA disease or X-linked Alport syndrome, or because of coincidental disease. About 40% families with TBMN have hematuria that segregates with the COL4A3/COL4A4 locus, and many COL4A3 and COL4A4 mutations have now been described. These genes are also affected in autosomal-recessive Alport syndrome, and at least some cases of TBMN represent the carrier state for this condition. Families with TBMN in whom hematuria does not segregate with the COL4A3/COL4A4 locus can be explained by de novo mutations, incomplete penetrance of hematuria, coincidental hematuria in family members without COL4A3 or COL4A4 mutations, and by a novel gene locus for TBMN. A renal biopsy is warranted in TBMN only if there are atypical features, or if IgA disease or X-linked Alport syndrome cannot be excluded clinically. In IgA disease, there is usually no family history of hematuria. X-linked Alport syndrome is much less common than TBMN and can often be identified in family members by its typical clinical features (including retinopathy), a lamellated GBM without the collagen alpha3(IV), alpha4(IV), and alpha5(IV) chains, and by gene linkage studies or the demonstration of a COL4A5 mutation. Technical difficulties in the demonstration and interpretation of COL4A3 and COL4A4 mutations mean that mutation detection is not used routinely in the diagnosis of TBMN.

Basement Membrane↗

PubMed2003

Mutations in the COL4A4 gene in thin basement membrane disease.

BACKGROUND: Patients with thin basement membrane disease (TBMD) are often from families where hematuria segregates with the COL4A3 and COL4A4 genes. These genes also are affected in autosomal recessive Alport syndrome. The aim of this study was to demonstrate COL4A4 mutations in TBMD. METHODS: Forty-eight unrelated individuals with TBMD who had no family members with autosomal recessive Alport syndrome were examined for COL4A4 mutations. The diagnosis of TBMD had been confirmed by renal biopsy (43/48, 90%) or by a family history of hematuria but without a renal biopsy (5/48, 10%). The 47 coding exons of COL4A4 were screened for mutations with the methods of enzyme mismatch cleavage or single stranded conformational polymorphism (SSCP) analysis, and exons that demonstrated electrophoretic abnormalities were sequenced. RESULTS: Nine variants that altered the coding sequences were identified. These were nonsense and frameshift mutations that resulted in stop codons (N = 3), and glycine (N = 3) and non-glycine missense variants (N = 3). Four intronic variants and three neutral polymorphisms were also detected. In total, four variants were considered 'pathogenic' principally because they resulted in stop codons or were not present in non-hematuric normal subjects. Three variants were considered 'possibly pathogenic' but two of these were each present in one of 46 non-hematuric normal subjects. CONCLUSIONS: Pathogenic COL4A4 mutations were demonstrated in three of the nine (33%) families in whom hematuria segregated with the COL4A3/COL4A4 locus. Two stop codons (R1377X and 2788/91delG) and a glycine substitution (G960R) resulted in hematuria in all 16 members who were tested from these three families. The S969X mutation described here in TBMD for the first time, as well as the R1377X mutation, also occur in autosomal recessive Alport syndrome.

Adolescent↗

PubMed2002

Three novel COL4A4 mutations resulting in stop codons and their clinical effects in autosomal recessive Alport syndrome.

Autosomal recessive Alport syndrome is caused by mutations in the COL4A3 and COL4A4 genes which code for the alpha3 and alpha4 chains of type IV collagen. These mutations result in haematuria, progressive renal impairment and often hearing loss, lenticonus and retinopathy. We describe here the mutations demonstrated by screening the 47 coding exons of the COL4A4 gene in six families with autosomal recessive Alport syndrome using PCR-single stranded conformational polymorphism (SSCP) analysis. Six sequence variants were identified. These included three novel mutations (2846delG, 2952delG and S969X) in exons 30 - 32 that all resulted in premature stop codons. These mutations were demonstrated in the heterozygous form in 3 families, and the S969X mutation was also present in the homozygous form in one of the two consanguinous families. These three mutations accounted for 40% (4/10) of the total mutant alleles in the six families studied. Six of the seven (86%) individuals with autosomal recessive Alport syndrome who had these mutations in the compound heterozygous or homozygous forms developed renal failure in adulthood, as well as hearing loss and ocular abnormalities. Haematuria was present in 15 of the 17 (88%) heterozygous mutation carriers. The other non-pathogenic sequence variants noted in COL4A4 included a nonglycine missense variant (L1004P), an intronic variant (4731-8 T>C) and a neutral polymorphism (V1516V).

Adult↗