Structural insights into the pathogenicity of point mutations in human acyl-CoA dehydrogenase homotetramers

Acyl-CoA dehydrogenase deficiency (ACAD) is an inherited and potentially fatal disorder with variable clinical symptoms. The relationship between pathogenicity and deleterious point mutations is investigated here in ACAD structures of short (SCAD) and medium-chain (MCAD) types. Structures and dynamic features of native and mutant forms of enzymes models were compared. A total of 2.88 µs molecular dynamics simulations were performed at four different temperatures. Total energy, RMSD, protein ligand interactions and affinity, RMSF measures, secondary structure changes, and important interactions were studied. Mutations in the three main domains of ACADs are pathogenic, while those located at linker turns are not. Mutations affect mostly tetramer formations, secondary structures, and many contacts and interactions. In R206H (MCAD mutant) which is experimentally known to cause a huge turnover decrease, the lack of a single H-bond between substrate and FAD was observed. Secondary structures showed temperature-dependent changes, and SCAD activity was found to be highly correlated to the enzyme helix 3-10 content. Finally, RMSF patterns pointed to one important loop that maintains the substrate close to the active site and is a cause of substrate wobbling upon mutation. Despite similar structure, function, and cellular location, SCAD and MCAD may have different optimum temperatures that are related to the structure taken at that specific temperature. In conclusion, new insight has been provided on the effect of various SCAD and MCAD pathogenic mutations on the structure and dynamical features of the enzymes.

Solid waste production and its management in dental clinics in Gorgan, northern Iran

BACKGROUND

Waste produced in dental clinics has been the topic of investigations for many years. These waste materials have important health impacts and are hazardous to humans and the environment.

OBJECTIVE

To investigating solid waste production and its management in dental clinics in Gorgan, northern Iran.

METHODS

In this cross-sectional study, 45 of 143 public dental practices and 5 of 25 private dental practices were selected and studied. From each clinic, 3 samples were taken and analyzed at the end of successive working days (Tuesday and Wednesday). Samples were manually sorted into 50 components. The measured components were then classified on the basis of their characteristics, hazard potentials, and WHO classification.

RESULTS

The total annual amount of dental waste produced in public and private dental practices in Gorgan was 12 015.1 and 3135.0 kg, respectively. Production percentages of infectious, domestic, chemical and pharmaceutical, and toxic waste in public dental practices were 38.4%, 33.7%, 6.6%, and 0.6%, respectively. The percentages for private practices were 8.7%, 10.6%, 1.1%, and 0.1%, respectively.

CONCLUSION

Dental waste management in Gorgan is inadequate; dental waste is not properly segregated, collected, and disposed, as demanded by the WHO. Employees in dentist offices must be trained in correct handling of waste products and the associated risks.

Family screening for a novel ATP7B gene mutation, c.2335T>G, in the South of Iran

BACKGROUND

Wilson disease (WD) is a rare autosomal recessive disorder, which leads to copper metabolism, due to mutations in ATP7B gene. The gene responsible for WD consists of 21 exons that span a genomic region of about 80 kb and encodes a copper transporting P-type ATPase (ATP7B), a protein consisting of 1465 amino acids. Identifying mutation in ATP7B gene is important to find carrier individuals for proper counseling. A novel mutation in exon 8 of ATP7B gene, c.2335T>G (p.Trp779Gly), with severe neuropsychiatric condition in the South of Iran, was recently identified. The aim of this study was to screen 120 individuals from a large family using a simple amplification refractory mutation system PCR (ARMS-PCR) for carrier screening in the South of Iran.

MATERIALS AND METHODS

120 individuals from family relatives of an index case in the Nasr Abad, south of Iran, were studied for screening of the c.2335T>G mutation. One patient with homozygous mutation and one homozygous normal individual were used as controls in this experiment.

RESULTS

Altogether, 16 out of 120 (13.3%) individuals within this region had heterozygous mutation. One individual with homozygote mutation was also identified.

CONCLUSION

Identification of carriers in families with affected individuals is of great importance for counseling before marriage. The results of this study can be used for further counseling programs in this population.

Effect of antioxidants on stabilization of meat products fortified with n-3 fatty acids

The effects of an n-3 oil emulsion, with and without added antioxidants, on lipid oxidation in n-3 polyunsaturated fatty acid (PUFA)-fortified meat products were studied. An emulsion of n-3 PUFAs was prepared (25% algal oil, 2.5% whey protein isolates, 10mM sodium citrate, 0.2% potassium sorbate, 500ppm of 70% mixed tocopherols, 100μM EDTA, pH 3, pasteurized at 75°C for 30min) and incorporated into fresh ground turkey, and fresh pork sausage (20% fat) to achieve a concentration of 500mg n-3 PUFA/110g meat. An antioxidant combination containing rosemary (0.2% w/w; radical quencher), citrate (0.5% w/w; sequestrant) and erythorbate (1g/kg product; reductant) was prepared and incorporated into ground turkey patties (5cm dia, 1.5cm thick) or fresh pork sausages (5cm dia, 1.5cm thick). Meat products were stored at 4°C or -18°C and analyzed for color (L*, a*, b* values), lipid oxidation (TBARS and lipid hydroperoxides) and n-3 PUFA profile. a* Values of refrigerated ground turkey patties decreased with storage, and an antioxidant combination effect was observed after 4 days (P<0.05). For fresh pork sausages at 4°C, control+antioxidant (CON+ANTI), and n-3+antioxidant (n-3+ANTI) groups showed greater a* values than controls (CON) indicating that the antioxidant combination stabilized meat color. TBARS and lipid hydroperoxides of both n-3 PUFA-enhanced meat products increased with storage (P<0.05); there were no significant changes in TBARS or lipid hydroperoxides for treatments containing the antioxidant combination (P<0.05). The actual level of n-3 PUFA incorporation in both meat products was greater than 87%; n-3 PUFA concentrations did not change within any treatment during storage (P>0.05). These results provide support for including antioxidant protection in n-3 PUFA fortified meat products.

Double-blind comparison of fluoxetine and nortriptyline in the treatment of moderate to severe major depression

BACKGROUND

Depression is an international public health problem. Impairment in social and occupational functioning, increased comorbidity with other psychiatric and medical conditions, and an increased risk of mortality are a few of its consequences. Some psychiatrists have the impression that selective serotonin re-uptake inhibitors may not work as well as tricyclic anti-depressants in severe depression and/or melancholia. On the contrary, there is a general belief that selective serotonin re-uptake inhibitors are superior to the tricyclic anti-depressants in having fewer side-effects, particularly cardiovascular effects. The objective of this double-blind study was to compare the efficacy and safety of fluoxetine and nortriptyline in patients with moderate to severe major depression.

METHODS

A total of 48 adult outpatients who met the Diagnostic and Statistical Manual of Mental Disorders (DSM IV), forth edition for major depression, based on the structured clinical interview for DSM IV participated in the trial. Patients had a baseline Hamilton Rating Scale for Depression score of at least 20. In this double-blind, single-center trial, patients were randomly assigned to receive nortriptyline 150 mg/day (group 1) or fluoxetine 60 mg/day (group 2) for 6-weeks. The outcome of the two groups was assessed using Hamilton Depression Rating Scale, a side-effect checklist and a regular ECG assessment.

RESULTS

The results suggest that the efficacy of nortriptyline is superior to fluoxetine in this group of major depressed patients. No significant differences were observed between dropout rates in the two groups but anti-cholinergic side-effects were significantly more frequent with nortriptyline than with fluoxetine but there was no significant difference in cardiovascular effects in particular QTc prolongation.

CONCLUSION

The results of the current study suggest that nortriptyline was more effective than fluoxetine in the treatment of moderate to severe depression. A larger study is warranted.

Unraveling the 10 micron "silicate" feature of protostars: the detection of frozen interstellar ammonia

We present infrared spectra of four embedded protostars in the 750-1230 cm-1 (13.3-8.1 microns) range. For NGC 7538 IRS 9, a new band is reported at 1110 cm-1 (9.01 microns, and several others may be present near 785, 820, 900, 1030, and 1075 cm-1 (12.7, 12.2, 11.1, 9.71, and 9.30 microns). The band 1110 cm-1 is attributed to frozen NH3. Its position and width imply that the NH3 is frozen in a polar, H2O-rich interstellar ice component. The NH3/H2O ice ratio inferred for NGC 7538 IRS 9 is 0.1, making NH3 as important a component as CH3OH and CO2 in the polar ices along this line of sight. At these concentrations, hydrogen bonding between the NH3 and H2O can account for much of the enigmatic low-frequency wing on the 3240 cm-1 (3.09 microns) H2O interstellar ice band. The strength of the implied NH3 deformation fundamental at 1624 cm-1 (6.158 microns) can also account for the absorption at this position reported by ISO.