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Biomedical subjects

K F Tabbara

Publications and source records attributed to K F Tabbara.

At least 37 records · Page 2Linked to original sources
PubMed1999

HLA class I and II typing of the patients with Behçet's disease in Saudi Arabia.

Thirteen Saudi Arabian patients with Behçet's disease (BD) were typed for HLA-A and -B alleles by the conventional serologic typing and for HLA-DRB1, -DQB1 and -DPB1 alleles by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. As a result, the phenotype frequency of the B51 antigen was significantly increased in the patient group as compared to the ethnically matched control group (76.9% in patients vs. 22.20% in controls), but no significant difference was observed in HLA-A, -DRB1, -DQB1 or -DPB1 alleles between the patients and controls, as previously observed in Japanese BD. Further, by HLA-B51 allelic genotyping performed by the polymerase chain reaction-sequence specific primers (PCR-SSP) method, all of the B51-positive patients and controls were found to carry one particular allele, B*5101, except one patient with B*5108.

Behcet Syndrome↗
PubMed1999

Efficacy of nedocromil 2% versus fluorometholone 0.1%: a randomised, double masked trial comparing the effects on severe vernal keratoconjunctivitis.

AIMS: To compare the efficacy of topical nedocromil 2% with fluorometholone 0.1% in vernal keratoconjunctivitis (VKC). METHODS: In a double masked random design, 24 patients with severe vernal keratoconjunctivitis were placed at random on nedocromil 2% eye drops in one eye and fluorometholone 0.1% in the fellow eye. At the end of the 2 week treatment period, the patient crossed over the eye drops (if asymptomatic in one eye), or continued with nedocromil sodium in both eyes (if asymptomatic in both eyes). All patients were examined weekly and ocular surface temperature recorded for a period of 6 weeks. RESULTS: Improvement in the watering, discharge, conjunctival hyperaemia, papillary hypertrophy, and Trantas' dots was noted in both groups, but overall fluorometholone was significantly more effective than nedocromil. Eyes treated with fluorometholone showed a significant decrease in ocular surface temperature compared with nedocromil treated eyes (p = 0.03). CONCLUSIONS: Both nedocromil and fluorometholone were effective in ameliorating the signs and symptoms of vernal keratoconjunctivitis. No adverse effects were noted in the nedocromil group.

Adolescent↗
PubMed1999

Ocular complications of vernal keratoconjunctivitis.

BACKGROUND: The objective of this study was to assess the ocular complications and visual loss among patients with severe vernal keratoconjunctivitis (VKC). METHODS: A total of 58 consecutive patients (52 boys and 6 girls aged 8 to 17 [mean 12.2] years) with severe active VKC were examined at two tertiary care facilities in Riyadh, Saudi Arabia, between 1995 and 1997. Patients were deemed to have severe VKC if they had had symptoms for at least 2 years, had diffuse palpebral conjunctival edema and thickening with papillary hypertrophy (P3) and giant papillary conjunctivitis, and had limbal infiltration of 180 degrees or more. Visual acuity was measured with the standard Snellen visual acuity chart. Visual impairment was assessed by means of the World Health Organization criteria for visual disabilities. Visual loss was defined as either blindness or visual impairment. RESULTS: Twelve patients (21%) had a best corrected visual acuity in one or both eyes of 20/200 or less, 20 (34%) had 20/50 to 20/200 vision, and 26 (45%) had 20/20 to 20/50 vision. The ocular complications that led to visual loss among 32 patients included steroid-induced cataract (8 patients), steroid-induced glaucoma (4), central corneal scars (7), irregular astigmatism (4), keratoconus (3) and limbal tissue hyperplasia (3). Of the 32 patients 12 had dry eye syndrome, which may have contributed to the visual loss. INTERPRETATION: Severe VKC in developing countries is a potentially blinding disease. Visual loss may be due to corneal complications, including corneal scars, astigmatism and keratoconus, as well as complications of the unsupervised use of topically administered corticosteroids.

Adolescent↗
PubMed1998

Ocular levels of azithromycin.

OBJECTIVE: To assess azithromycin levels in human serum, aqueous humor, tear fluid, and conjunctival tissue specimens after administration of a single 1-g oral dose of azithromycin. METHODS: Sixty patients undergoing cataract surgery were included in this analysis. Serum, aqueous, and tear specimens were collected 3, 6, and 12 hours and 1, 2, 3, and 4 days after azithromycin administration. Conjunctival tissue biopsy specimens were collected 1, 2, 3, 4, 6, 8, 10, 12, and 14 days after azithromycin administration. All specimens were subjected to analysis by high-performance liquid chromatography-mass spectrometry. RESULTS: Azithromycin concentration ranges during the specified sampling times were as follows: serum, 21 to 974 ng/mL; tear, 82 to 2892 ng/mL; aqueous, 10 to 69 ng/mL; and conjunctival, 0.7 to 32 micrograms/g. Levels above the 90% minimal inhibitory concentration (MIC90) for Chlamydia trachomatis were detected after 4 days in all tear samples and after 14 days in all conjunctival tissue specimens following oral azithromycin administration. CONCLUSION: We demonstrated prolonged high levels of azithromycin in drug-targeted ocular tissue. Prolonged high concentrations of azithromycin in conjunctival tissue make this drug suitable for treatment of conjunctivitis caused by chlamydiae and other susceptible organisms.

Administration, Oral↗
PubMed1998

Hospital construction-associated outbreak of ocular aspergillosis after cataract surgery.

OBJECTIVE: This study aimed to report an outbreak of Aspergillus endophthalmitis after cataract extraction during hospital construction. DESIGN: The study design is a case series of an outbreak of Aspergillus endophthalmitis. PARTICIPANTS: Five patients in whom Aspergillus endophthalmitis developed during a period of hospital construction in Jeddah, Saudi Arabia, participated. Severe postoperative uveitis occurred in all five patients and failed to subside with topical steroid therapy. The patients were referred to the King Khaled Eye Specialist Hospital for treatment. The causative organism was identified as Aspergillus fumigatus in each case. INTERVENTION: All five patients were subjected to aqueous or vitreous tap. Three patients had vitrectomy. Patients were given systemic, periocular, and intravitreous antifungal agents. MAIN OUTCOME: The final outcome in each patient was evisceration or enucleation, despite an intensive course of antifungal therapy. RESULTS: There were five patients, three females and two males, ranging in age from 51 to 65 years. Postoperative signs of infection developed in the patients 4 to 15 days after surgery. In all five cases, cultures of aqueous or vitreous grew A. fumigatus. CONCLUSION: Aspergillus endophthalmitis is a serious and devastating complication of ocular surgery. The outbreak, herewith, may have been related to hospital construction. The infection can be prevented, notably, by proper maintenance of old, "sick" buildings and by following certain procedures during hospital construction.

Aged↗
PubMed1998

Heparin surface-modified intraocular lenses in patients with inactive uveitis or diabetes.

OBJECTIVE: This study aimed to determine whether heparin surface-modified (HSM) intraocular lenses (IOLs) with a hydrophilic surface would reduce cell adherence and other postoperative changes compared with the conventional polymethylmethacrylate (PMMA) IOLs in patients with either diabetes mellitus or inactive uveitis. DESIGN: The study design was a randomized, double-masked, clinical trial. PARTICIPANTS: Twenty-five patients with bilateral cataracts, 14 with inactive anterior uveitis and 11 with diabetes, with an age range of 11 to 81 years (mean, 52.8 years) participated. INTERVENTION: Bilateral cataract extraction with posterior chamber IOL implantation was measured, each patient receiving an HSM lens in one eye and a PMMA lens in the other. Pharmacia one-piece HSM and PMMA IOLs were used. Postoperative ocular changes were evaluated at regular intervals for 24 months in patients with inactive uveitis and for 6 months in patients with diabetes. Patients and physicians alike were unaware of which eye contained which lens until postoperative results were compiled. Records were kept by a study coordinator. MAIN OUTCOME MEASURES: Comparisons of posterior synechiae, IOL cellular deposits, and posterior capsular fibrosis between PMMA and HSM IOLs were measured. RESULTS: Using the chi-square test, no statistically significant difference was found between the HSM and PMMA IOLs in the number of cellular deposits found on the anterior IOL surface, the number of adhesions between the iris and IOL, or the incidence of capsular opacification. CONCLUSION: The HSM and PMMA IOLs showed similar postoperative results in patients with inactive uveitis or diabetes mellitus.

Adolescent↗
PubMed1998

Demyelination of retinal myelinated nerve fibers in Behcet's disease.

A 39 year-old Behcet's patient had demyelination of retinal myelinated nerve fibers after recurrent papillitis and vitritis. Oral Prednisolone, cyclosporine, and later periocular corticosteroids and oral colchicine were used but demyelination continued over a 5 year-period. A pseudobulbar palsy with urinary incontinence and pyramidal tract signs developed and azathioprine and corticosteroids were used. Demyelination of retinal nerve fibers stopped and while treatment was underway, the central nervous system (CNS) signs were stable. While the ocular pathology of Behcet's can mirror the CNS signs, indeed optic nerve ischemic demyelination may signal the potential for CNS involvement; azathioprine with prednisone may be more effective in the long-term for optic nerve and CNS involvement than cyclosporine with prednisone.

Adult↗
PubMed1998

Vogt-Koyanagi-Harada syndrome in children compared to adults.

PURPOSE: To study the course and visual outcome of Vogt-Koyanagi-Harada (VKH) syndrome in children. METHODS: The medical records of 97 consecutive patients with VKH syndrome were reviewed. Patients had been seen at King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia. The records were divided into two groups: those in whom the onset of the disease occurred at the age of 14 years or younger (pediatric group) and those in whom the disease manifested after the age of 14 years (adult group). RESULTS: Eight (61%) of the 13 children required cataract surgery compared to 14(17%) of 84 adult patients. Despite medical and surgical therapy, eight (61%) of the pediatric group had a final visual acuity of 20/200 or worse compared with 22 (26%) of the 84 adult patients (p=0.0103). CONCLUSION: The course of early-onset VKH (before the age of 14 years) appears to be aggressive. The ocular complications are more severe in children than in adults, leading to rapid deterioration in vision. Despite therapy, the final visual outcome of VKH in children is poor.

Adolescent↗
PubMed1998

Immunopathogenesis of conjunctival scarring in trachoma.

PURPOSE: Trachoma, a chronic follicular conjunctivitis caused by infection with Chlamydia trachomatis, is the leading cause of preventable blindness. The blinding complications are associated with progressive conjunctival scarring that may result from immunologically mediated responses. We studied the processes involved in the regulation of inflammation and fibrosis in trachoma by investigating the expression of fibrogenic cytokines in the conjunctiva. METHODS: We studied conjunctival biopsy specimens obtained from nine subjects with active trachoma and from four control subjects. We used immunohistochemical techniques and a panel of monoclonal and polyclonal antibodies directed against interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and platelet-derived growth factor (PDGF). In addition, we characterised the composition of the inflammatory infiltrate by the use of a panel of monoclonal antibodies. Sirius red and Van Gieson stains were used to characterise the extent of fibrous tissue in the substantia propria. RESULTS: Trachoma specimens showed greater numbers of inflammatory cells than control specimens. The expression of cytokines was absent in the normal conjunctiva. Cytoplasmic IL-1 alpha and IL-1 beta expression was noted in the conjunctival epithelium in all trachoma specimens. IL-1 alpha, IL-1 beta, TNF-alpha and PDGF were detected in macrophages infiltrating the substantia propria. B lymphocytes predominated over T lymphocytes in six trachoma biopsies with fibrosis confined to the deep substantia propria, whereas T lymphocytes predominated over B lymphocytes in three biopsies with more extensive fibrosis. In all trachoma biopsies helper/inducer T lymphocytes outnumbered suppressor/cytotoxic T lymphocytes. CONCLUSIONS: The upregulated local production of IL-1 alpha, IL-beta, TNF-alpha and PDGF might contribute to conjunctival damage and scarring in trachoma.

Adolescent↗
PubMed1998

Collagen content and types in trachomatous conjunctivitis.

PURPOSE: To study alterations in conjunctival collagen in the conjunctiva of patients with active trachoma. METHODS: We studied conjunctival biopsy specimens obtained from nine subjects with active trachoma and from four control subjects. We used immunohistochemical techniques and a panel of monoclonal and polyclonal antibodies directed against types I, III, IV and V collagen. RESULTS: In normal conjunctiva, the staining for types I and III collagen was localised to the substantia propria. Type IV collagen was located in the epithelial and capillary endothelial basement membranes. The staining for type V collagen was absent. In trachoma biopsy specimens, staining for types I and III collagen showed collagen fibrils among epithelial cells, patchy increase in staining intensity in the upper stroma, and thicker and irregularly arranged collagen fibrils in the substantia propria. Staining for type IV collagen showed irregularly thickened epithelial basement membrane. Staining for type V collagen showed patchy staining in the upper substantia propria; it was also noted in the cytoplasm of fibroblasts, in the walls of blood vessels in the substantia propria, and in the walls of accessory lacrimal glands. CONCLUSIONS: Our data indicate new type V collagen formation, and increased types I, III and IV collagen content, in the conjunctiva from patients with active trachoma.

Adolescent↗
PubMed1998

An immunohistochemical study of collagens in trachoma and vernal keratoconjunctivitis.

PURPOSE: To analyse the distribution and types of collagen in the conjunctiva of patients with trachoma and vernal keratoconjunctivitis (VKC). METHODS: Conjunctival biopsy specimens were collected from 9 patients with active trachoma, 9 patients with scarred trachoma, 6 patients with active VKC and 9 control subjects. The presence and distribution of collagen was assessed microscopically with immunohistochemical techniques and a panel of monoclonal and polyclonal antibodies directed against types I, III, IV and V collagen. RESULTS: In normal conjunctiva, the staining for types I and III collagen was localised to the substantia propria. Type IV collagen was located in the epithelial, vascular endothelial and accessory lacrimal gland basement membranes. Staining for type V collagen was absent. New type V collagen deposition close to basement membranes was noted in active trachoma, scarred trachoma and VKC. The extent of deposition of type V collagen was markedly increased in scarred trachoma when compared with active trachoma. Staining for type IV collagen showed irregularly thickened epithelial basement membrane in active trachoma, and a marked increase in basement membrane type IV collagen was noted in scarred trachoma. Immunoreactivity of types I and III collagen increased in active trachoma and decreased in scarred trachoma. VKC conjunctiva contained increased amounts of types I, III and IV collagen due to marked increase in the thickness of vascular endothelial basement membrane and very prominent deposition of types I and III collagen around stromal vessels. CONCLUSIONS: Our data indicate new type V collagen formation in the conjunctiva from patients with active trachoma, scarred trachoma and VKC. Increased deposition of types I, III and IV collagen is noted in VKC and active trachoma. Our findings suggest that increased deposition of type IV collagen and new type V collagen formation contributes to the development of conjunctival fibrosis in scarred trachoma.

Adolescent↗
PubMed1998

Dry eye syndrome.

The present review is of dry eye syndrome, an entity caused by various conditions that lead to tear film abnormalities. The tear film consists of aqueous, mucin, proteins and lipids. Dry eye syndrome may be caused by local ocular disorders or systemic diseases. The symptoms include foreign body sensation, redness, photophobia and burning sensation. Clinical tests such as the Schirmer test, fluorescein staining test and Rose Bengal test are useful diagnostic tools. Laboratory tests are important assets in the diagnosis and identification of the underlying systemic disease. Biopsy of the accessory salivary gland is important in the diagnosis of Sjogren's syndrome. The management of dry eye syndrome includes replacing the deficient tear film and prolonging its residence time on the ocular surface.

Journal Article↗
PubMed1997

Secondary squamous cell carcinoma of the orbit.

OBJECTIVE: To evaluate the origin and biological behavior of secondary orbital squamous cell (SCC) and mucoepidermoid carcinoma. METHODS: A retrospective review of 30 consecutive patients with SCC and mucoepidermoid carcinoma of the orbit seen over a period of 8 years at a large ophthalmic hospital in Saudi Arabia. RESULTS: A total of 51 secondary orbital tumors were seen in the 8-year period from 1983 through 1991; 30 (60%) of the 51 cases were SCC. There were 16 male and 14 female patients, with an age range of 38 to 80 years and a mean age of 65 years. In 28 (93%) of the 30 patients, the tumor originated in the conjunctiva. Orbital involvement by conjunctival SCC was the most common cause of secondary orbital tumors encountered in patients older than 19 years. Four patients had concomitant paranasal sinus involvement, 4 patients exhibited intraocular invasion, and 2 others were found to have intracranial extension of the SCC. Six (20%) of the 28 patients developed regional lymph node metastases during the course of their illness. All patients were treated by orbital exenteration, with or without radiation therapy. Seven (23%) of the 28 patients died of their disease. CONCLUSIONS: Orbital SCC is an aggressive and life-threatening condition. Most cases result from secondary extension of conjunctival SCC, a common disease in Saudi Arabia. Several factors contribute to the aggressiveness of conjunctival SCC in this geographic location, including continual exposure to UV rays, chronic irritation, and genetic factors. Delay in presentation for treatment, inadequate initial resection of conjunctival lesions, and the aggressive mucoepidermoid carcinoma variant of SCC are also factors contributing to orbital invasion.

Adult↗
PubMed1997

Heparin and heparin-surface-modification reduce Staphylococcus epidermidis adhesion to intraocular lenses.

Bacterial adherence to intraocular lenses (IOLs) could be the cause of endophthalmitis following cataract surgery and lens implantation. The majority of cases of postoperative endophthalmitis are caused by microflora that reside on or near the eye of the patient. Staphylococcus epidermidis commonly colonizes the eyelid margin and conjunctiva and is the most common organism causing postoperative endophthalmitis. In this study, the in vitro adherence of S. epidermidis to regular poly-methyl methacrylate (PMMA) IOLs and to heparin-surface-modified (HSM) PMMA IOLs was investigated. The effects of heparin and antibiotics in solution on the adherence of bacteria to regular PMMA IOLs were evaluated. Adhesion of bacterial cells to IOLs was determined by counting the viable cells attached to the lenses. Significantly, fewer S. epidermidis attached to HSM-PMMA IOLs and to regular PMMA IOLs treated with heparin than to PMMA IOLs (p < 0.001). Furthermore, bacteria attached in significantly lower numbers to regular PMMA IOLs treated with heparin than to HSM-PMMA IOLs (p = 0.0031). Antibiotics in solution had no significant effect on bacterial adherence to PMMA IOLs. These data indicate that the use of HSM-PMMA IOLs and treatment of PMMA IOLs with heparin could diminish the incidence of postoperative endophthalmitis and intraocular inflammation associated with IOL implantation.

Anti-Bacterial Agents↗
PubMed1997

Retinal vasculitis.

Inflammation of the retinal vasculature may occur as a manifestation of an infectious disease, as part of a systemic inflammatory disease, or as part of an isolated retinal disease, and can result in severe and permanent visual loss. The search for a cause in patients with retinal vasculitis requires appropriate systemic evaluation and testing. Discrimination between the infectious or noninfectious etiology of retinal vasculitis is important because the treatment is different.

Fluorescein Angiography↗
PubMed1997

Trinucleotide repeat polymorphism within exon 5 of the MICA gene (MHC class I chain-related gene A): allele frequency data in the nine population groups Japanese, Northern Han, Hui, Uygur, Kazakhstan, Iranian, Saudi Arabian, Greek and Italian.

We recently identified a trinucleotide repeat polymorphism, (GCT)n, within the transmembrane (TM) segment of the human MHC class I MICA gene (MHC class I chain-related gene A). Five distinct alleles (A4, A5, A5.1, A6, A9) corresponding to 4, 5, 5 with one nucleotide insertion, 6 and 9 repetitions, respectively, have been detected in various HLA-homozygous B cell lines. Here we present allele frequencies for this trimeric short tandem repeat (STR) in 604 unrelated individuals collected from nine human populations (Japanese, Northern Han, Hui, Uygur, Kazakhstan, Iranian, Saudi Arabian, Greek and Italian) determined using the polymerase chain reaction (PCR) combined with fluorescent-based automated fragment detection technology. All alleles were present in each population, but allelic distributions varied from one population to another. No new alleles (such as A7 or A8) were identified. The evolutionary and structural significance of these data as well as the potential application to forensic medicine is discussed.

Alleles↗