Caffeine modulates apoptosis, oxidative stress, and inflammation damage induced by tramadol in cerebellum of male rats

Tramadol, an opioid used as analgesic, can induce neurotoxic effects associated to cognitive dysfunction. Moreover, caffeine has been reported to have neuroprotective effects. In this regard, we hypothesized that administration of caffeine can modulate tramadol-induced damages in cerebellum. For this study, forty male Wistar rats were divided into four groups: the control group, the tramadol group (50mg/kg), the caffeine group (37.5mg/kg), and the tramadol+caffeine group (50mg/kg tramadol+37.5mg/kg caffeine). At the end of study (day 21), after performing rotarod behavioral test, cerebellum tissue samples were removed and prepared for further evaluations including biochemical profile markers (MDA, GPx, and SOD), immunohistochemistry for Caspase-3, as well as the expression of genes involved in cellular processes such as inflammation markers (IL-1β, HMGB1, IL-6, and TNF), apoptosis markers (Caspase-3, Caspase-8, Bax, and P21), and autophagy markers (LAMP2, ATG5, BECN1, and ATG12). Stereological evaluations were performed to determine the total volume of granular and molecular layers and white matter of cerebellum tissue and numerical density of the Purkinje cells. Our results showed that the stereological parameters, biochemical profiles (except MDA) and behavioral function were significantly higher in the tramadol+caffeine group compared to the tramadol group. Autophagy-related genes were significantly upregulated in tramadol+caffeine group compared to the tramadol group. While the expression of inflammatory and apoptosis genes, MDA level, as well as density of apoptosis cells were significantly lower in the tramadol+caffeine group compared to the tramadol group. Briefly, it can be concluded that administration of caffeine has neuroprotective effects in cerebellar damages induced by tramadol.

Report of a Novel Bilateral Variation of Sciatic and Inferior Gluteal Nerve: A Case Study

Introduction:

The sciatic nerve is the thickest nerve of the sacral plexus which innervates many muscles and vast areas of the skin of the lower limb. It leaves the pelvis via the greater sciatic foramen, emerges into the gluteal region by passing under the piriformis muscle, and descends beneath the gluteus maximus to divide into its terminal branches; the tibial and common peroneal nerve at the superior angle of the popliteal fossa. In some cases, the sciatic nerve divides into the tibial and common peroneal nerves at a higher level and one of them or both passes through or over the piriformis muscle.

Case Presentation:

We find an interesting bilateral variation of sciatic nerve accompanying a very thick inferior gluteal nerve on the right side and unusual route and branching of tibial and common peroneal nerves on the left side.

Conclusion:

As in conditions like intramuscular injections, gluteal surgeries, and piriformis syndrome such variations may increase the risk of injury, it is important for the medical team to be aware of them. In this paper, by reporting many variations in a cadaver, we emphasize the importance of anatomical variations, especially for surgeons and nurses.

Histopathologic Characteristics of Invasive and Non-invasive Ductal Tumors have Relationship with Different Phenotypes of ER / PR Receptors in Breast Cancer Patients

Objective: Contradictory reports have been published regarding the expression levels of the hormone receptors of estrogen and progesterone (ER / PR) and theirclinical importance in diagnosis of breast cancer. The aim of this study was to evaluate the relationship between pathological features of invasive and non-invasive ductal tumors by different ER / PR phenotypes. Methods: This descriptive-analytical study was performed on 74 specimens of breast cancer referred to Isfahan Hospitals for diagnosis between 2015 - 2018. After fixation of the specimens in formalin, tissue passage, cross section and H / E staining, the specimens were divided into two groups: non- invasive and Invasive ductal Carcinoma. After removing of mask, expression of different ER / PR phenotypes was performed using primary monoclonal antibody and immunohistochemically methods. Results: From 74 malignant specimens, 61 (82.4%) were in the category of invasive ductal tumors and 13 cases (17.6%) were in the category of non-invasive ductal tumors. Out of 73 patients with positive ER or PR phenotype 47 samples (63.5%) had ER + / PR +phenotypes, 6 samples had (8.1%) ER+ / PR –phenotype, 20 samples (27%) had ER- / PR + phenotype and only one sample (1.4%) had the ER- / PR- phenotype and was in the category of invasive ductal tumors. There was not detected ER- / PR- phenotype expression in non-invasive ductal tumor. Further analysis showed that there were not significant difference between ER / PR phenotype and tumor stage (p =0.36) or with tumor Grade (P=0.38), high age of menopause or post menopause (P> 0.05). Conclusion: Our data shows that expression of ER- / PR- phenotype only was detected in invasive ductal tumor. It is thought that the tumor type maybe affects the expression of different types of ER / PR hormone receptor phenotypes in breast cancer patients.

Effects of curcumin nanoparticle on the histological changes and apoptotic factors expression in testis tissue after methylphenidate administration in rats

The present article sought to evaluate the impact of curcumin-loaded superparamagnetic iron oxide (Fe3O4) nanoparticles (NPs) on the histological variables and apoptotic agents in adult male rats after 3-weeks of methylphenidate (MPH) oral administration (20 mg/kg) versus vehicle therapy on the testis. Twenty-four male rats have been categorized randomly into four groups, in which Group 1 has been chosen as the controls, and Group 2 has been a vehicle and taken the sesame oil as curcumin carrier. Moreover, Group 3 has been taken MPH (20 mg/kg by gavage for 21 consecutive days). Group 4 received MPH plus Curcumin nanoparticles (5.4 mg/100 g) for twenty-one consecutive days. Then, testis histology, apoptosis as well as stereology have been examined. According to the examinations, curcumin nanoparticles are significantly capable of improving the sperms and stereological variables; for example, round spermatid and Leydig cells by enhancing the level of the serum testosterone in comparison with the MPH and vehicle groups. Besides, it was found that the gene expression in inflammation pathways and apoptosis genes largely diminished in the treatment group by curcumin nanoparticles in comparison with the MPH and vehicle groups, also we observed considerable differences for the weight of testes between the examined groups. Therefore, Curcumin effectively inhibited the testis damages and MPH-induced apoptosis, indicating possible protecting features of the Curcumin nanoparticles in opposition to MPH.

The effects of two types of renin-angiotensin system inhibitors on the hypertension induced by new pressor protein associated with beta-factor XIIa in rats

Background and purpose:

New pressor protein (NPP) is a human plasma enzyme, which is structurally related to the beta-fragment of activated factor XII. The present study aimed to compare the effects of angiotensin converting enzyme inhibitors (captopril) and angiotensin type 1 receptor blocker (losartan) on the hypertension induced by NPP injection in normal (sham-2NX) and bilaterally nephrectomized rats (2NX).

Experimental approach:

In total, 60 male Wistar rats were sham operated or bilaterally nephrectomized under anesthesia. After 24 h of anesthesia with Inactin® (100 mg/kg), their systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were measured before and after the intravenous administration of captopril, losartan, and NPP.

Findings / Results:

In the sham-2NX group, after NPP injection, changes were observed in SBP (145.99 ± 3.6 mmHg), DBP (93.9 ± 3.87 mmHg), and HR (400.29 ± 12.78 bpm). In the captopril group, SBP and DBP had no significant changes, while HR increased significantly (P = 0.001). In the losartan group, SBP and DBP decreased (P = 0.001 and P = 0.000, respectively), while HR had no significant changes. In the 2NX group, after NPP injection, changes were denoted in SBP (127.89 ± 9.03 mmHg), DBP (65.86 ± 5.69 mmHg), and HR (333.35 ± 11.47 bpm). In addition, captopril injection increased DBP (P = 0.016) and HR (P = 0.036) in response to NPP injection, while losartan injection had no significant effects in this regard.

Conclusion and implications:

It could be concluded that losartan could improve hypertension in normal rats, while captopril deteriorated hypertension in bilaterally nephrectomized rats in this hypertension model.

Evaluation of Glutathione Bioactivity on Toxoplasma Gondii in BALB/c Mice Post Impact of Selenium and Calcium Supplementation

BACKGROUND

Studies have shown that selenium is an essential component of glutathione as an important antioxidant to reduce oxidative stress and inhibit intracellular parasites' growth. In contrast, calcium in the cytosol of such parasites plays a key role in the entry of the parasite into the host cell and its primary motility.

AIMS AND OBJECTIVES

The present study was designed to evaluate and compare glutathione peroxidase bioactivity effects post administration of selenium and calcium in BALB/c mice infected by Toxoplasma gondii.

METHODS

Sixty BALB/c mice susceptible to T. gondii were randomly divided into twelve groups of case and control groups. There were six control groups including two positive controls infected only with the parasites either 10⁴ or 5×10⁴, non-infected and untreated groups. Treated controls received only calcium, selenium, or both respectively. Case groups were infected with 10⁴ or 5×10⁴ parasites. While each set of three case groups separately received minerals alone or together. Mice were orally fed with 200 μg selenium, 50 μg calcium or their combination for 7 days. Mice were infected by parasite's tachyzoites. Sera of mice were kept and the peritoneal macrophages were isolated for counting tachyzoites during infection.

RESULTS

The results showed that selenium unlike calcium was significantly effective in reducing Toxoplasma tachyzoites compared to control groups. Moreover, glutathione peroxidase [GPX] activity was elevated in mice treated with selenium and vice versa decreased in mice treated with calcium.

CONCLUSION

Administration of selenium unlike calcium reduced Toxoplasma tachyzoites proliferation by elevating bioactivity of selenium-dependent detoxification enzyme, GPX.

Protective impacts of erythropoietin on myelinization of oligodendrocytes and schwann cells in CNS and PNS following cuprizone-induced multiple sclerosis- histology, molecular, and functional studies

BACKGROUND

Multiple sclerosis (MS) is known as one of the chronic inflammatory diseases characterized by lesions in the central nervous system (CNS) and peripheral nervous system(PNS) resulting in serious cognitive or physical disabilities as well as neurological disorders. Thus, protective effects of erythropoietin(EPO) on myelinization of oligodendrocytes and schwann cells respectively in CNS and PNS following MS induced by cuprizone (CPZ) administration in young female mice.

METHODOLOGY

To meet the objectives of this study; a chow with 0.2 % CPZ was used to feed young female C57BL/6 J mice for six weeks. After three weeks, EPO (5000 IU/kg body weight) was administered via daily intra-peritoneal injection for simultaneous treatment of the mice. Measurement of latency and amplitude of the compound muscle action potential (CMAP) of gastrocnemius muscle was also performed every week during a six-week demyelination interval, and then examinations were fulfilled on the histological sections of the brain and sciatic nerve. Therefore, we focused on the removal of the sciatic and sciatic nerve specimens and analysis of the use of the stereological procedures, western blot, immuno-histochemistry, and gene expression.

RESULTS

According to the results of this study, MBP levels increased in oligodendrocytes (OLs) in the treated mice. Moreover, EPO could concurrently enhance motor coordination and muscle activity. Analysis showed the significant enhancement of the gene expression of MBP, MAG, and S100, as well as stereological variables in the treatment group in comparison with the cuprizone (CPZ) group.

CONCLUSION

Findings could help further understand the alleviation of the detrimental impacts of CPZ using the OLs that would be capable of increasing the level of S100, MAG, and MBP.

A single nucleotide polymorphism in codon F31I and V57I of the AURKA gene in invasive ductal breast carcinoma in Middle East

Although few studies have suggested a carcinogenic role for polymorphism of F31I and V57I codons of AURKA gene in invasive ductal carcinoma, contradictory results from different populations mandates regional investigations. We aimed to determine polymorphisms of F31I and V57I codons of AURKA gene and their association with cancer prognosis in patients compared with controls in an eastern population of Iran.A case-control study was conducted on specimens from 100 patients and 100 age- and gender-matched controls. DNA was extracted and the codons F31I and V57I were amplified. The different genotypes were analyzed by PCR-RFLP and electrophoresis.In codon F31I, the frequency of Phe/Ile was 70% and 82% in patients and healthy controls respectively, whereas (Ile/Ile) was 30% in patients and 18% in healthy (P = .047). Analyzing V57I genotypes showed a higher homozygote Val/Val genotype in patients compared with controls (76% vs 68%), whereas the frequency of heterozygous Val/Ile genotype was lower in patients (17%) than controls (30%), yielding a marginal association between breast cancer and Val/Val genotype (P = .048). No association was observed between SNPs of either F31I or V57I genotypes and histological grades. However, there was a significant association between tumor stages and F31I genotype (P for trend = .003).This is the first report of F31I and V57I polymorphisms in AURKA gene in breast cancer in Iran. Determination of allelic polymorphism of those codons will help to understand background genetic predisposition and could have prognostic value in management of breast cancer in the target population.

Prognostic Role of PTEN Gene Expression and Length of Survival of Breast Cancer Patients in the North East of Iran

PTEN protein is an important tumour suppressor factor detectable by immunohistochemistry. The goal of the present study was to investigate the prognostic role of PTEN gene expression focusing on length of survival in breast cancer patients. This descriptive-analytical study was conducted on 100 breast cancer cases referred to Sabzevar hospitals in the north east of Iran between 2010 and 2011, followed up to 2015. The PTEN gene expression of tumour tissue samples was determined using specific monoclonal antibodies. The data were analyzed using Chi-square test and Fisher's exact test. Patient length of survival was analyzed after 4 years of follow-up using the Cox regression model. The PTEN gene was expressed in 70 of 100 samples, while being found at a high level in all noncancerous samples. There was an inverse significant relationship between expression of PTEN and tumour stage and grade (p<0.001). In addition, expression of PTEN in invasive ductal tumours was less than in non-invasive tumours. There was also an inverse significant relationship between the likelihood of death and PTEN gene expression (p<0.01). These findings indicate that lack of PTEN gene expression can be sign for a poor prognosis in breast cancer.

Allelic polymorphism in codon 72 of p53 gene: prognosis value, survival rates, and their association with breast cancer

PURPOSE OF INVESTIGATION

There are controversial findings to establish relationship between genotype polymorphism of codon 72 of P53 gene, its prognosis value, and survival rate of the patients in breast cancer. For the first time this study has shown such relationship in Sabzevar, Iran.

MATERIALS AND METHODS

A descriptive analytical case-control study was conducted on 160 people (80 patients and 80 controls). DNA was extracted and codon 72 of the p53 gene was amplified. The genotype of the p53 gene was determined by electrophoresis, samples were sequenced, and all patients were followed up for 30 months.

RESULTS

The frequency of heterozygote arginine/proline was 49 (30.6%) and 51(31.9%) in the patients and controls, respectively. Homozygote arginine/arginine had frequency of 29 (18.1%) in the patients while it was 15 (9.4%) in controls. Homozygote of proline/proline was two (1.3%) in the patients and 14 (8.8%) in controls. The sequencing results were consistent to PCR and electrophoresis results.

CONCLUSIONS

This is the first study in the region which shows relationship between genotype polymorphism, survival rate, and its prognosis value in breast cancer. The authors showed that homozygote proline/proline in controls was significantly higher compared with that in the patients. They may therefore, conclude that detection of allelic polymorphisms of codon 72 of the p53 gene including arginine/arginine could be a risk factor predisposition for breast cancer and valuable tool for determining prognosis, progress, and treatment purposes.

Effect of hydroalcoholic extract of Anethum graveolens leaves on the dentate gyrus of the hippocampus in the epileptic mice: a histopathological and immunohistochemical study

Anethum graveolens or Dill (local name: Shevid) belongs to the family of Apiaceae (Umbelliferae) and is used traditionally for the treatment of convulsion and diabetes in Iran. This study aimed to investigate the effect of hydroalcoholic extract of A. graveolens leaves on the histology of the dentate gyrus of the hippocampus in the epileptic mice kindled by Pentylenetetrazole (PTZ). In this experimental study, the epileptic BALB/c mice kindled by PTZ were randomly divided into four groups of 10 animals each. Three experimental groups received 250, 500 and 750 mg/kg/day of A. graveolens extract for 21 days. The control group received phosphate-buffered saline (PBS). After the treatment period, the mice were anesthetized, and their hippocampi were dissected for the histopathological analysis, and immunohistochemical analysis for caspase-3 activity. Histopathological examinations showed that the mean numbers of the healthy neuronal cells in the dentate gyrus of the mice received 500 mg/kg/day of A. graveolens extracts were significantly higher than those of the mice received 250 and 750 mg/kg/day of the extracts as well as the control group (P < 0.05 and P < 0.001, respectively). In addition, the results of immunohistochemical analysis revealed that in mice treated with 500 mg/kg/day of A. graveolens; the numbers of caspase-3-positive cells in the dentate gyrus were significantly lower than those of the two other test and the control groups. The findings of this study suggest that 500 mg/kg/day of the A. graveolens extract could have protective effect on the dentate gyrus of the hippocampus in the epileptic mice.

Prognostic Role of PTEN Gene Expression in Breast Cancer Patients from North-East Iran

Background: PTEN protein is one of the most important tumour suppressor factors which is detectable by immunohistochemistry. The goal of the present study was to investigate the prognostic role of PTEN gene expression in breast cancer patients. Materials and Methods: This descriptive-analytical study was conducted on 100 breast cancer patients referred to Sabzevar hospitals in the north-east of Iran between 2010 and 2011, who were followed up to 2015. PTEN gene expression in tissue samples was determined using specific monoclonal antibodies and data were analyzed using Chi-square test and Fisher’s exact test. Patient survival was analyzed after 4 years of follow-up using the Cox regression model. Results: PTEN gene expression was evident in 70 of 100 cnacer samples but was found at high levels in all non-cancer samples. There was an inverse significant relationship between PTEN gene expression and tumour stage or tumour grade (p<0.001). The expression of PTEN in invasive ductal tumours was lower than in non-invasive tumours. There was also an inverse significant relationship between the hazard of death and PTEN gene expression (p<0.001). In addition, there was an inverse significant relationship between tumour stage and hazard of death (p<0.001). Conclusion: These findings indicate that lack of PTEN gene expression can be a sign of a worse prognosis and poor survival in breast cancer cases.

Characterization and Prognostic Value of Mutations in Exons 5 and 6 of the p53 Gene in Patients with Colorectal Cancers in Central Iran

BACKGROUND/AIMS

We aimed to investigate the relation-ships among various mutations of the p53 gene and their protein products, histological characteristics, and disease prognosis of primary colorectal cancer in Isfahan, central Iran.

METHODS

Sixty-one patients with colorectal adenocarcinoma were enrolled in the study. Mutations of the p53 gene were detected by single-stranded conformation polymorphism and DNA sequencing. The protein stability was evaluated by immunohistochemistry. Patients were followed up to 48 months.

RESULTS

Twenty-one point mutations in exons 5 and 6 were detected in the tumor specimens of 14 patients (23%). Of those, 81% and 9.5% were missense and nonsense mutations, respectively. There were also two novel mutations in the intronic region between exons 5 and 6. In 11 mutated specimens, protein stability and protein accumulation were identified. There was a relationship between the type of mutation and protein accumulation in exons 5 and 6 of the p53 gene. The presence of the mutation was associated with an advanced stage of cancer (trend, p<0.009). Patients with mutated p53 genes had significantly lower survival rates than those with wild type p53 genes (p<0.01).

CONCLUSIONS

Mutations in exons 5 and 6 of the p53 gene are common genetic alterations in colorectal adenocarcinoma in central Iran and are associated with a poor prognosis of the disease.

The apoptotic effects of sirtuin1 inhibitor on the MCF-7 and MRC-5 cell lines

Sirtuin1 (SIRT1) is an enzyme that deacetylates histones and several nonhistone proteins including p53 during stress and plays an important role in the survival of tumor cells. Hereby, this study describes the potency of salermide as a SIRT1 inhibitor to induce apoptosis in the MCF-7 and MRC-5 cell lines. MCF7 and MRC-5 cell lines were cultured in RPMI-1640 and treated with or without salermide at concentration of 80.56 μmol/L, based on the half-maximal inhibitory concentration (IC50) index at different times (24, 48 and72 h). The IC50 value was established for the salermide in MCF-7. The percentage of apoptotic cells was measured by flow cytometry. Real-time quantitative RT-PCR was performed to estimate the mRNA expression of sirtuin1 in MCF-7 and MRC-5 with salermide at different times. ELISA and Bradford protein techniques were used to detect endogenous levels of total and acetylated p53 protein generated in MCF-7 and MRC-5 cells. Our findings indicated that salermide can induce apoptosis in MCF-7 significantly more effective than MRC-5 cells. We showed that the expression of SIRT1 was dramatically down-regulated by increasing the time of salermide treatment in MCF-7 but not MRC-5 and that the acetylated and total p53 protein levels were increased more in MCF-7 than MRC-5. Salermide, by decreasing the expression of sirtuin1 gene, can induce acetylation of P53 protein and consequently induce significant cell death in MCF-7 that was well tolerated in MRC-5.

The prognostic value of the P53 protein and the Ki67 marker in breast cancer patients

OBJECTIVE

To investigate and compare the prognostic value of P53 and Ki67 markers in patients with breast cancer in Sabzevar, north east of Iran.

METHODS

A descriptive analytical study was conducted on 80 patients with breast cancer who were admitted to the hospitals in Sabzevar in 2006 and they were followed up to 2010. The expression of ki67 and stability of p53 genes were determined by immunohistochemistry. To assess the disease prognosis, patients were followed up to 48 months. Data were analyzed using SPSS software version 11.5. Chi-square, Fisher's exact test, Kaplan-Miere and Log Rank tests were used for statistical purposes.

RESULTS

Eighty cancerous tissue samples were examined. The Ki67 marker was present in 37 (46.3%) cases and the P53 protein stability in 39 (48.8%) cases were observed. There was a significant relationship between ki67 gene expression and tumour stage (p = 0.001) or tumour type (P = 0.02). There was also a significant relationship between the survival rate and the tumor stage (P = 0.008). The Ki67 marker had significant relationship with the survival rate (P = 0.031), but over expression of P53 protein did not show such significance (P = 0.385).

CONCLUSION

The results showed that the Ki67 marker was more important than P53 protein in prognosis of the breast cancer patients.

Eye bleeding due to leech infestation in an ischemic heart- disease patient

A 49-year-old Iranian male with diagnosis of ischemic heart disease (IHD) and arterial hypertension (AH) was admitted at Emergency Ward of Vase'ee Hospital of Sabzevar, Iran. As well, the patient had red eye and left eye bleeding. On eye examination, leech infestation was found to be the cause of the eye bleeding. In the endemic regions in a patient presenting red eye and eye bleeding, leech infestation came up to be an important differential diagnosis. Therefore, to prevent leech infestation in endemic regions, local people are advised to be informed more effectively about the necessity to use safe, clean, and filtered drinking water, and a perfect scrutiny for leeches or other sources of infestation that should be undertaken before bathing.

A Rapid Method for Estimating of Noise Exposure in Work-places

BACKGROUND

Noise pollution is one of the important issues of pollutant in workplaces and is almost one of the harmful agents for workers. At present, instrumental based inspections for determining the index levels of noise in workshops is performed. This method is requiring a time consuming and ex-pensive in large scale inspection for workplaces. Classification of workplaces based on noise pollution is one of the necessaries for macro programming view of monitoring and controlling of noise. The Propose of this study was to submit a simply scientifically screening method for inspection of noise pollution in workplaces.

METHODS

In this experimental study, the results of instrument based and checklist based of noise in-vestigation was compared. For designing of proposed screening checklist and instrumental measuring based, 30 workplaces with more than 20 workers in Hamadan industrial area (west of Iran) were stud-ied. The suggested screening checklist containing a 3*10 matrix can use for recognition step of noise assessment in a large scale investigations.

RESULTS

Comparison of the results of the noise screening test with the outcome of a noise measurement by sound level meter, gave a sensitivity of 50% and specificity of 85%.

CONCLUSION

The screening test will be useable, if we only want to estimate the global noise pollution in workplaces.

Estimation of illuminance on the South facing surfaces for clear skies in iran

BACKGROUND

Daylight availability data are essential for designing effectively day lighted buildings. In respect to no available daylight availability data in Iran, illuminance data on the south facing vertical surfaces were estimated using a proper method.

METHODS

An illuminance measuring set was designed for measuring vertical illuminances for standard times over 15 days at one hour intervals from 9 a.m. to 3 p.m. at three measuring stations (Hamadan, Eshtehard and Kerman). Measuring data were used to confirm predicted by the IESNA method.

RESULTS

Measurement of respective illuminances on the south vertical surfaces resulted in minimum values of 10.5 KLx, mean values of 33.59 KLx and maximum values of 79.6 KLx.

CONCLUSION

In this study was developed a regression model between measured and calculated data of south facing vertical illuminance. This model, have a good linear correlation between measured and calculated values (r= 0.892).

Road traffic noise model

BACKGROUND

The recognition of road traffic noise as one of the main sources of environmental pollution has led to develop models that enable to predict noise level from fundamental variables. Traffic noise prediction models are required as aids for designing roads and highways. In addition, sometimes are used in the assessment of existing or envisaged changes in traffic noise conditions. In this paper a statistical modelling approach has been used for predicting road traffic noise in Iranian road conditions.

METHODS

The study was performed during 2005-2006 in Hamadan city, in the west of Iran. The data set consisted of 282 noise measurements. The entire data set was utilized to develop a new model for Iranian condition using regression analysis.

RESULTS

The developed model has twelve explanatory variables in order to achieve a proper fit for measured values of Leq (r2= 0.913).

CONCLUSION

The proposed road traffic noise model can be effectively used as a decision support tools for prediction of traffic noise index of Leq(30min), in Iran's cities.

The crystal structure of bacteriophage Q beta at 3.5 A resolution

BACKGROUND

The capsid protein subunits of small RNA bacteriophages form a T = 3 particle upon assembly and RNA encapsidation. Dimers of the capsid protein repress translation of the replicase gene product by binding to the ribosome binding site and this interaction is believed to initiate RNA encapsidation. We have determined the crystal structure of phage Q beta with the aim of clarifying which factors are the most important for particle assembly and RNA interaction in the small phages.

RESULTS

The crystal structure of bacteriophage Q beta determined at 3.5 A resolution shows that the capsid is stabilized by disulfide bonds on each side of the flexible loops that are situated around the fivefold and quasi-sixfold axes. As in other small RNA phages, the protein capsid is constructed from subunits which associate into dimers. A contiguous ten-stranded antiparallel beta sheet facing the RNA is formed in the dimer. The disulfide bonds lock the constituent dimers of the capsid covalently in the T = 3 lattice.

CONCLUSIONS

The unusual stability of the Q beta particle is due to the tight dimer interactions and the disulfide bonds linking each dimer covalently to the rest of the capsid. A comparison with the structure of the related phage MS2 shows that although the fold of the Q beta coat protein is very similar, the details of the protein-protein interactions are completely different. The most conserved region of the protein is at the surface, which, in MS2, is involved in RNA binding.

Crystal structures of MS2 capsids with mutations in the subunit FG loop

The loop between the F and G beta strands (FG loop) of the bacteriophage MS2 coat protein subunit forms inter-subunit contacts around the 5-fold and 3-fold (quasi 6-fold) axes of the T=3 protein shell. In capsids, the loop is found in two very different conformations, one in B subunits, which form the 5-fold contact, and one in A and C subunits, which form the quasi 6-fold contact. One proline residue, Pro78, is strictly conserved in the coat protein of all related bacteriophages, and in the case of MS2 this proline residue is preceded by a cis peptide bond in the B subunit. In order to probe the role of the FG loop in capsid assembly, we have determined the crystal structures of two MS2 capsids, formed by coat proteins with mutations at two positions in the FG loop, P78N or E76D. These mutants show conformational changes in the FG loops that explain the reduced temperature stability of the capsids. The P78N mutant has a normal trans peptide bond at position 78.

The refined structure of bacteriophage MS2 at 2.8 A resolution

Bacteriophage MS2 is an icosahedral virus with 180 copies of a coat protein forming a shell around a single-stranded RNA molecule. The coat protein subunits form a lattice with the triangulation number T = 3. The coat protein has a fold which is different from the fold of all other viral coat proteins so far known. It consists of a five-stranded beta sheet facing the inside of the particle, and a hairpin and two helices on the outside. The crystal structure has been refined at 2.8 A resolution. The final R-factor was 0.189 for reflections with F > 2 sigma, and the root-mean-square deviation from idealized bond lengths and bond angles was 0.015 A and 2.9 degrees, respectively. The three chemically identical conformers A, B and C are largely similar. The B conformer has a unique conformation in one loop, which is involved in 5-fold interactions, while the A and C conformers, which are involved in the quasi-6-fold contacts, are similar throughout the structure. One cis-proline has been identified in the B conformer but the corresponding prolines in A and C are of the trans isomer. This residue is conserved within small RNA coliphages and it is proposed that this isomerization enables a less elongated loop (FG) around the 5-fold axis, thus creating a channel. The extensive dimer contact supports the idea of dimers as initial building blocks. An assembly pathway is proposed where five dimers converge into a pentamer and 12 pentamers are linked together with free dimers creating a complete particle.