Biomedical subjects

M Mohammadi

Publications and source records attributed to M Mohammadi.

At least 19 recordsLinked to original sources

PubMed2006

The prediction of transmitted dose distributions using a 3D treatment planning system.

Patient dose verification is becoming increasingly important with the advent of new complex radiotherapy techniques such as conformal radiotherapy (CRT) and intensity-modulated radiotherapy (IMRT). An electronic portal imaging device (EPID) has potential application for in vivo dosimetry. In the current work, an EPID has been modelled using a treatment planning system (TPS) to predict transmitted dose maps. A thin slab of RW3 material used to initially represent the EPID. A homogeneous RW3 phantom and the thin RW3 slab placed at a clinical distance away from the phantom were scanned using a CT simulator. The resulting CT images were transferred via DICOM to the TPS and the density of the CT data corresponding to the thin RW3 slab was changed to 1 g/cm3. Transmitted dose maps (TDMs) in the modelled EPID were calculated by the TPS using the collapsed-cone (C-C) convolution superposition (C/S) algorithm. A 6 MV beam was used in the simulation to deliver 300 MU to the homogenous phantom using an isocentric and SSD (source-to-surface) technique. The phantom thickness was varied and the calculated TDMs in the modelled EPID were compared with corresponding measurements obtained from a calibrated scanning liquid-filled ionisation chamber (SLIC) EPID. The two TDMs were compared using the gamma evaluation technique of Low et al. The predicted and measured TDMs agree to within 2 % (averaged over all phantom thicknesses) on the central beam axis. More than 90 % of points in the dose maps (excluding field edges) produce a gamma index less than or equal to 1, for dose difference (averaged over all phantom thicknesses), and distance-to-agreement criteria of 4 %, 3.8 mm, respectively. In addition, the noise level on the central axis in the predicted dose maps is less than 0.1 %. We found that phantom thickness changes of approximately 1 mm, which correspond to dose changes on the central beam axis of less than 0.6 %, can be detected in the predicted transmitted dose distributions.

Algorithms↗

PubMed2006

Comparison of two-dimensional transmitted dose maps: evaluation of existing algorithms.

Composite analysis and the gamma function are often used to assess the agreement between a reference and an evaluated two-dimensional dose maps. The intent of the study is to compare advantages, disadvantages and limitations of dose evaluation tools reported in the literature. In addition, in order to improve the gamma function output, a "Signed Matrix" was introduced using the ratio of relative dose difference maps. Transmitted dose maps were acquired for a range of homogeneous phantoms using Extended Dose Range (EDR2) films and a Scanning Liquid Ionization Chamber Electronic Portal Imaging Device (SLIC-EPID). For inhomogeneous case, the transmitted dose maps were obtained from EDR2 films measurement and a Treatment Planning System (TPS). The corresponding dose maps were compared based on composite and gamma function algorithms. The results showed that the agreement between reference and evaluated dose maps for the composite analysis were generally greater than those obtained using the gamma function. For homogeneous phantom comparison, the difference between the agreeing fractions calculated using composite analysis and gamma function increases with the increase of phantom thickness for deltaD = 0.5% and 1%. For inhomogeneous cases, a significant difference (approximately 5% for deltaD = 1.5%) was observed between the percentage agreement as calculated by composite and gamma function techniques. The concept of the composite model is closer than gamma function to the idea of the two-dimensional dose verification protocol proposed originally by van Dyk. However, the composite model results only display the passed or failed regions in the dose maps. On the other hand, the gamma function provides continuos information by distinguishing the points within each region. The overdosed/underdosed regions (the ratio of reference and evaluated doses at a given point) and the direction of the misalignment can be recognized with the enhanced gamma map convolved with a "Signed Matrix".

Algorithms↗

PubMed2006

[Hepatitis C and diabetes mellitus: effect of diabetes on the course of the liver disease].

UNLABELLED: The prevalence of diabetes mellitus is higher in chronic hepatitis C than in hepatitis B, even without cirrhosis. OBJECTIVE: To study the host, specific viral factors associated with diabetes mellitus and the influence of diabetes mellitus on the intensity of steatosis and the severity of fibrosis. MATERIAL AND METHODS: The following data were collected in a cohort of 1249 patients with chronic hepatitis C established between December 1991 and June 2004: age, gender, body mass index (BMI). None of the patients were under treatment for their liver disease. Serum transaminase level and hepatitis C serology with search for viral RNA, viral load and genotype were obtained. The Metavir score, iron overload using the Perls score (0-4) and steatosis class (0-3) were determined on liver biopsies. RESULTS: Mean patient age was 52.5+/-10 years (56% male). Mean BMI was 24.6+/-24 kg/m2. Forty-three patients (17.2%) presented diabetes mellitus. The mean duration of their diabetes was 8.9 years. Genotype 1 predominated (60.4%) and mean viral load was 7.7x10(6) eq.v/ml. Steatosis was present in 69.7% of the diabetic patients versus 17% of the non-diabetic patients. Grade 2 fibrosis (F2) was observed in 32.5% of diabetic patients versus 29% in non-diabetic patients and F3, F4 in 73% of the diabetic patients versus 57% of the non-diabetic patients. Comparison between diabetic and non-diabetic patients demonstrated an absence of statistically significant difference (at 5%) between the groups for gender, viral load and genotype. Diabetic persons were older (58.7 years against 51 years) and liver biopsy revealed steatosis and fibrosis (F3, F4) more often in diabetic patients (69.7% versus 49.5%). CONCLUSION: These findings suggest that steatosis could favor progression of fibrosis in diabetics with chronic hepatitis C.

Adolescent↗

PubMed2006

Thyroid disorders during interferon alpha therapy in 625 patients with chronic hepatitis C: a prospective cohort study.

AIM: to report the prevalence, risk factors, management and long-term outcome of thyroid disorders caused by INFalpha in patients with chronic hepatitis C. PATIENTS AND METHODS: From January 1991 to December 2004, 625 patients with chronic hepatitis C underwent INFalpha therapy. TSH assay was normal and antithyroperoxidase antibodies (anti-TPO) was performed before onset antiviral treatment; then TSH was performed every 2 months in all patients during therapy, and every 3 months after treatment. RESULTS: 58 patients developed thyroid disorder (8.9%). Mean age was 50.6+/-13 years; sex ratio: 1 M/2 F; the anti-TPO antibodies were positive before onset antiviral treatment in 9 patients (13.8%). 26 patients developed hypothyroidism (44.8%), 9 patients developed hyperthyroidism (15.5%) and among them 3 cases of Grave's disease. Biphasic thyroiditis occurred in 21 patients (36.2%), anti-TPO increase during treatment in 2 patients (3.5%) without hypothyroidism. The dysthyroidism was more frequent in risk in female gender (p<0.05) and in the group with positive antiTPO antibodies before treatment (p<0.02). CONCLUSION: Female gender and positive antiTPO antibodies are the predictive factors of development of the thyroid dysfunction during INFalpha therapy.

Antiviral Agents↗

PubMed2005

A study about geographical distribution of root lesion nematode (Pratylenchus loosi, Loof 1960) in tea gardens at Guilan Province, Iran.

Root lesion nematode of tea (Pratylenchus loosi) is one of the most dangerous and distractive pests in all over areas in the world where tea grows. In Iran, this species was one of the quarantine pests that for first time it were separated from the Japan imported tea slips and reported by Maafi (1993). Nowadays it has been distributed in some tea growth areas of Guilan and Mazandaran provinces (North of Iran). In this study, geographical distribution of this pest is reported on some tea growth areas of Guilan province. In order to, 147 samples from root and soil around them were investigated. These samples were gathered from various gardens of Guilan province. They were transferred to nematology lab with suitable temperature and moisture conditions and were stored at 5-10 degrees C until extraction time. Centrifugal methods for nematode extraction from soil (Jenkins, 1964) and from root (Coolen & D'Herde, 1972) were used. The nematode was identified by Handoo & Golden (1989) and Frederick & Tarjan (1989) diagnostic keys. According to this study different infested areas and geographical distribution were detected in Guilan province. Results indicated that many important tea growth areas in Guilan were infested by this nematode. In addition, it seems that it has been distributed during short time.

Animals↗

PubMed2005

Chitinase gene transformation through Agrobacteriumand its explanation in soybean in order to induce resistance to root rot caused by Rhizoctonia solani.

Chitinase gene (chi) of bean which has been cloned in recombinant binary plasmid vector, pBI121 with 35s promoter of Cauliflower mosaic virus (CaMV), were used for transformation of soybean using strain LBA4404 of Agrobacterium. The plasmid contained nptII gene that is a resistant gene to kanomycin as selector marker and Gus gene as reporter. Cotyledon explants of Williams and Clark cultivars were inoculated by Agrobacterium suspension with pBI121 and were cultured in regeneration medium. After complete regeneration of explants to seedling in B5 medium amended with kanomycin, polymerase chain reaction analysis were conducted to ensure conjugation of nptII, Gus, CHN genes in transformants seedling of soybean. Results showed that some lines of soybean contained Gus and CHN genes. More ever, chitinase activity in leaf extract of transformed soybean lines was significantly more than untransformed soybean, exception one sample. Bioassay of chitinase activity of transgenic lines on in vitro condition prevented mycelial growth of Rhizoctonia solani in comparison with untransformed control leaf extract.

Chitinases↗

PubMed2005

Occurrence and physico-serological properties of potato virus S (PVS) in Iran.

1818 collected samples of potato plant showing virus infection symptoms from 85 fields were tested for PVS infection using DAS-ELISA. Average of infection to this virus varied from 0 to 100%. Least infection was belonging to fields with new introduced varieties. On the other hand native and old introduced cultivars showed heavy infection. In field condition, PVS infected plants didn't show very obvious symptoms, so some infected plants may be missed in field sample collecting. The physical properties of 3 isolates, Avaj, Stanboly and Agria No 15 were determined. TIP 55-60 degrees C, DEP 10(-3) and Liv measured 3-4 days. Ouchterlony agar double diffusion test using SDS was useful for virus detection and precipitation lines didn't show any spur between isolates, although isolates differs slightly in symptomatology. SDS-Page and Western blotting methods used successfully for virus detection and determining and measuring viral protein components.

Carlavirus↗

PubMed2004

Facial hemangioma, and associated malformations: a case report.

Facial hemangioma can be isolated lesions or associated with a wide variety of systemic findings. We report a 9-month-old girl who shows an extensive facial hemangioma, intracranial and extracranial vascular malformations, a Dandy-Walker malformation and congenital cardiac malformations. This patient serves as an ample reason why children with similar cutaneous lesions should be carefully evaluated for other associated defects.

Abnormalities, Multiple↗

PubMed2004

Influence of inoculum density of Verticillium dahliae, temperature and relative humidity on epidemics of verticillium wilt of cotton in northern Iran.

During 1992--2003, frequency of Verticillium dahliae propagules, disease incidence and severity of verticillium wilt of cotton were determined in several cotton growing fields in Golestan province, northeastern Iran. Inoculum density varied among fields and different years ranging between 2-47 propagules/g of air-dried soil with an average of 18.96+/-0.73. In addition, the pattern of diseased plants varied with type of field and year. Simple regression analysis showed a linear relationship between inoculum density of V. dahliae at planting time on one hand, disease incidence and severity for all years on the other. The straight line model described the increase in disease intensity index over the accumulated physiological time from sowing. The number of days above 28 degrees C (T) and the area under relative humidity (RH) had significant effects on inoculum density in soil (MS) and final disease development (Y) and fitted the Y = 65.840 - 0.0034 RH + 0.57 MS - 1.7T model with R2 = 0.859 and significant F-function (p<0.0001).

Climate↗

PubMed2004

Changes in specific activities of peroxidase, chitinase and phenylalanine ammonia-lyase and phenolic content in cucumber leaves inoculated with Podosphaera fusca, the causal agent of powdery mildew.

In this investigation, the effects of powdery mildew disease [caused by Podosphaera fusca (syn. Sphaerotheca fuliginea)] on specific activities of several defense-related enzymes and phenolic content were studied in cucumber leaves. Spore suspension of the fungus was sprayed on cucumber (cv. Super Dominus) plants in greenhouse and leaves from both inoculated and non-inoculated control plants were sampled at 0, 24, 48, 72 and 144 hours after inoculation (HAI). Spore germination and tissue colonization of P. fusca were microscopically studied on the inoculated surface of leaf samples. Further, Phenolic content (PHE) and specific activities of peroxidase (POX), chitinase (CHI) and phenylalanine ammonia-lyase (PAL) were spectrophotometrically measured in leaf extracts. Time-course of disease progress on the leaf surface showed that maximum spore germination occurred within 24 HAI and host penetration and disease development process began during 24-48 HAI. Evaluation of enzyme activities showed that POX specific activity in inoculated plants significantly increased at 72 HAI onwards and reached 2.5 times of that of control at 144 HAI. CHI specific activity showed a transient reduction in inoculated plants between 48-72 HAI and thereafter increased significantly in relation to control. PAL specific activity in inoculated plants was not significantly different from that of control. PHE in inoculated plants showed a significant increase compared to control at 48 HAI and thereafter. Comparison of time-course of disease progress with changes in enzyme activities indicated that POX activity had an increasing trend during disease progress whereas CHI activity showed a transient decrease at the early stages and then increased during the later stages of infection: PAL activity did not show any changes during the infection and PHE increased at the early stages of infection process and remained constant at rest of the time.

Ascomycota↗

PubMed2004

Effects of Acibenzolar-S-methyl on the specific activities of peroxidase, chitinase and phenylalanine ammonia-lyase and phenolic content of host leaves in cucumber-powdery mildew interaction.

One of the properties of systemic acquired resistance in plants is its concomitance with the biochemical changes including enhancement of activities of defense-related enzymes. In this study, the effects of Acibenzolar-S-methyl (ACI) on the some of defense responses of the cucumber plants (healthy or inoculated with spore suspension of Podosphaerafusca, the causal agent of cucumber powdery mildew) were surveyed via in vivo tests. Changes of defense responses in ACI-treated cucumber plants, inoculated with pathogen or not, were studied and compared with those of non-treated control plants. Results indicated that specific activity of peroxidase increased significantly in treated plants. Increase in enzyme activity was higher in pathogen-inoculated than non-inoculated plants, thus pathogen attack stress to plant plays a role in enhancement of enzyme activity. Specific activity of phenylalanine ammonialyase showed no changes in ACI-treated non-inoculated plants, but in inoculated plants it Increased due to interaction between ACI treatment and pathogen attack stress. Specific activity of chitinase increased in both inoculated and non-inoculated ACI-treated plants at 24 hours after treatment onwards, and pathogen attack stress did not affect it. Phenolic content of ACI-treated plant tissues, despite of small fluctuations, did not show any definite pattern of changes.

Chitinases↗

PubMed2004

Contraception continuation rates and reasons for discontinuation in Zahedan, Islamic Republic of Iran.

We evaluated contraception continuation rates and discontinuation reasons in Zahedan among 1741 women from 1998-2000. By Kaplan-Meier technique continuation rates were 92% for low dose combined hormonal oral contraceptives (OC), 86% for a levonorgestrel-releasing implant, 82% for intrauterine devices (IUD) and 53% for medroxyprogesterone acetate at the first year. After 3 years, continuation was 78% for levonorgestrel implant, 70% for OC, 60% for IUD and 44% for medroxyprogesterone acetate. The commonest reason for discontinuing OC and medroxyprogesterone acetate was changing method; for IUD and levonorgestrel-releasing implant, the commonest reason was side-effects. By Cox regression model, continuation rate and contraceptive type were significantly related to health centre.

Adult↗

PubMed2003

Salvia officinalis extract in the treatment of patients with mild to moderate Alzheimer's disease: a double blind, randomized and placebo-controlled trial.

BACKGROUND: Alzheimer's disease is characterized by a slow, progressive decline in cognitive function and behaviour. Acetylcholine esterase inhibitors are the only agents approved by the Food and Drug Administration for the treatment of Alzheimer's disease. All other agents prescribed for the treatment of Alzheimer's disease are used on an off-label basis. Current research into new drugs is focused on agents that will prevent, slow down and/or halt the progress of the disease process. Salvia officinalis has been used in herbal medicine for many centuries. It has been suggested, on the basis of traditional medicine, its in vitro cholinergic binding properties and modulation of mood and cognitive performance in humans, that Salvia officinalis might potentially provide a novel natural treatment for Alzheimer's disease. The objective of this study was to assess the efficacy and safety of Salvia officinalis extract using a fixed dose (60 drops/day), in patients with mild to moderate Alzheimer's disease, over a 4-month period. METHODS: This was a 4-month, parallel group, placebo-controlled trial undertaken in three centres in Tehran, Iran. Patients with mild to moderate Alzheimer's disease aged between 65 and 80 years (n = 42, 18 women) with a score of > or = 12 on the cognitive subscale of Alzheimer's Disease Assessment Scale (ADAS-cog) and < or = 2 on the Clinical Dementia Rating (CDR) were randomized to placebo or fixed dose of S. officinalis extract. Over the 16 weeks, the main efficacy measures were the change in the ADAS-cog and CDR-Sum of Boxes scores compared with baseline. In addition, side-effects were systematically recorded throughout the study using a checklist. RESULTS: At 4 months, S. officinalis extract produced a significant better outcome on cognitive functions than placebo (ADAS-cog: F = 4.77, d.f. = 1, P = 0.03) (CDR-SB: F = 10.84, d.f. = 1, P < 0.003). There were no significant differences in the two groups in terms of observed side-effects except agitation that appears to be more frequent in the placebo group (P = 0.09). CONCLUSIONS: The results of this study indicate the efficacy of S. officinalis extract in the management of mild to moderate Alzheimer's disease. Moreover, S. officinalis may well reduce agitation of patients but this needs to be confirmed.

Administration, Oral↗

PubMed2003

Performance of PCR-restriction fragment length polymorphism analysis of the Helicobacter pylori ureB gene in differentiating gene variants.

Recently, PCR-restriction fragment length polymorphism (PCR-RFLP) of the urease genes of Helicobacter pylori was evaluated in a meta-analysis; acceptable discriminatory indices of the ureAB and C genes were found. In the present investigation, we found a discriminatory index of 0.95 for 191 unrelated clinical H. pylori isolates with PCR-RFLP typing of the ureB gene (933 bp), combining the results obtained with restriction enzymes HaeIII and Sau3A, and a mixture of the enzymes. We therefore find that PCR-RFLP typing of the ureB gene of H. pylori with restriction enzymes HaeIII and Sau3A is comparable to typing of other H. pylori urease genes.

DNA, Bacterial↗

PubMed2003

Melissa officinalis extract in the treatment of patients with mild to moderate Alzheimer's disease: a double blind, randomised, placebo controlled trial.

OBJECTIVE: To assess the efficacy and safety of Melissa officinalis extract using a fixed dose (60 drops/day) in patients with mild to moderate Alzheimer's disease. DESIGN: A four month, parallel group, placebo controlled trial undertaken in three centres in Tehran, Iran. METHODS: Patients with mild to moderate Alzheimer's disease aged between 65 and 80 years (n = 42; 18 women, 24 men) with a score of >or= 12 on the cognitive subscale of Alzheimer's disease assessment scale (ADAS-cog) and <or= 2 on the clinical dementia rating (CDR) were randomised to placebo or fixed dose of Melissa officinalis extract. The main efficacy measures were the change in the ADAS-cog and CDR-SB scores compared with baseline. Side effects were systematically recorded. RESULTS: At four months, Melissa officinalis extract produced a significantly better outcome on cognitive function than placebo (ADAS-cog: df = 1, F = 6.93, p = 0.01; CDR: df = 1, F = 16.87, p < 0.0001). There were no significant differences in the two groups in terms of observed side effects except agitation, which was more common in the placebo group (p = 0.03). CONCLUSIONS: Melissa officinalis extract is of value in the management of mild to moderate Alzheimer's disease and has a positive effect on agitation in such patients.

Aged↗

PubMed2003

Prevalence of Helicobacter pylori vacuolating cytotoxin and its allelic mosaicism as a predictive marker for Iranian dyspeptic patients.

Helicobacter pylori infects the majority of the population in the developing countries. However, the rate of gastrointestinal complications such as peptic ulcers and gastric malignancies has no parallel with the infection. In order to determine whether cytotoxin (vacA) and its allelic polymorphism can serve as screening markers for such a population, H. pylori strains were isolated from one hundred and thirty two dyspeptic patients. H. pylori genomic DNA was extracted and underwent PCR-amplification for the cytotoxin alleles. Genotyping of the signal sequence region of the vacA gene identified 68% (70 out of 103) of patients with non ulcer dyspepsia (NUD) and 79% (23 out of 29) of the patients with peptic ulcer disease (PUD) possessing the s1 genotype. S1 strains were significantly more prevalent among patients with PUD as compared to the NUD (p < 0.05). In regard to the middle region, 55% of the patient isolates belonged to the m2 genotype with no correlation to disease. The s1m2 genotype was the most prevalent among all patients and significantly correlated with the PUD group (p < 0.05).

Adult↗

PubMed2003

Cloning and expression of pinB gene from Triticum monococum seeds.

Puroindolines (PIN) are low molecular weight, cysteine-rich, endosperm-specific, basic proteins with a unique tryptophan-rich domain found in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) as well as other members of Triticaceae. PINs appear to be involved in both flour softness as well as resistance against fungal diseases. These proteins are known to be the major components of 'friabilin' associated with the surface of water washed starch grains and possess lipid binding properties. Structural characterization of puroindolines from Triticum monococum was initiated by amplifying and subsequently cloning the corresponding pin gene into an expression vector, known as pET-32a(+). The protein contains five tryptophanin domains and ten cysteine residues. The pinB gene was fused with the 109aa Trx.Tag thioredoxin for a high-level expression. The cloning sites used for producing fusion proteins also contained cleavable His.Tag and S.tag sequences for detection and purification. After transformation of competent Origami cells, fusion protein expression was detected by growing a transformant in LB medium in the presence of 0.1 mM IPTG at room temperature for 6 hrs on a shaker. Both soluble and insoluble fusion proteins were extracted from Origami cells after sonication. Ni-NTA column (Qiagen) was used to extract and purify these fractions. Following an overnight digestion of the recombinant protein with enterokinase at room temperature, the corresponding fractions were electrophoresed in polyacrylamide gel, electroblotted onto a nitrocellulose membrane and cross-reacted with the anti-friabilin monoclonal antibody. We found that the recombinant PINB protein had a molecular weight of 16 kDa whereas TrxB was 21 kDa. Fusion protein ran at 34 kDa. PINB protein from wheat was shown to be immunologically related to a homologue, tryptophanin, in oat seed. Further study is currently underway to characterize these proteins structurally using NMR.

Cloning, Molecular↗

PubMed2003

Identification of physiological races of Blumeria graminis f. sp. tritici and evaluation of powdery mildew resistance in wheat cultivars in Sistan province, Iran.

Powdery mildew of wheat caused by Blumeria graminis f. sp. tritici (Bgt) is one of the most important fungal diseases in Iran. During the years 1998-2001, wheat fields in Sistan province were surveyed and powdery mildew infected samples were collected from various areas and transferred to the laboratory. In the greenhouse, fungal spores were purified and inoculated onto susceptible wheat cultivars using single pustule and single spore procedures. Selected pure isolates were inoculated onto the first leaves of eight differential wheat varieties for identifying physiological races. The results showed the existence of Bgt races 5, 11, 14, 19, 21, 24, 27, 28, 31, 32, 44, 50, 53, 58, 66, 73 and 84 in Sistan. These races were new to Sistan province and Iran as a whole. Among 17 races studied, races 11, 53 and 73 were important dominant races thus constituting 40% of total population. Race 53 constituted 16% of all isolates and was the dominant race in the area with 62.5% pathogenicity. Therefore, this race was introduced as the most virulent race during the period of this study. This study showed that Bgt isolates were compatible with host plant genes pm8, pm3 and pm3b but incompatible with gene pm4b. Powdery mildew resistance was evaluated using race 11 on 70 wheat cultivars during seedling stage as well as adult plant under both greenhouse and field conditions between 1999 and 2001. Among wheat lines tested for resistance against powdery mildew, cultivar Hirmand resembled the differential line Weihenst M1 in that both may possess gene pm4b and showed no symptoms under the greenhouse and field conditions. Cultivar Chamran was found to be highly resistant whereas Sorkhtokhm was susceptible. Other cutivars showed partial and gradual resistance against the powdery mildew disease.

Ascomycota↗