In cellulo examination of a beta-alpha hybrid construct of beta-hexosaminidase A subunits, reported to interact with the GM2 activator protein and hydrolyze GM2 ganglioside.

The hydrolysis in lysosomes of GM2 ganglioside to GM3 ganglioside requires the correct synthesis, intracellular assembly and transport of three separate gene products; i.e., the alpha and beta subunits of heterodimeric beta-hexosaminidase A, E.C. # 3.2.1.52 (encoded by the HEXA and HEXB genes, respectively), and the GM2-activator protein (GM2AP, encoded by the GM2A gene). Mutations in any one of these genes can result in one of three neurodegenerative diseases collectively known as GM2 gangliosidosis (HEXA, Tay-Sachs disease, MIM # 272800; HEXB, Sandhoff disease, MIM # 268800; and GM2A, AB-variant form, MIM # 272750). Elements of both of the hexosaminidase A subunits are needed to productively interact with the GM2 ganglioside-GM2AP complex in the lysosome. Some of these elements have been predicted from the crystal structures of hexosaminidase and the activator. Recently a hybrid of the two subunits has been constructed and reported to be capable of forming homodimers that can perform this reaction in vivo, which could greatly simplify vector-mediated gene transfer approaches for Tay-Sachs or Sandhoff diseases. A cDNA encoding a hybrid hexosaminidase subunit capable of dimerizing and hydrolyzing GM2 ganglioside could be incorporated into a single vector, whereas packaging both subunits of hexosaminidase A into vectors, such as adeno-associated virus, would be impractical due to size constraints. In this report we examine the previously published hybrid construct (H1) and a new more extensive hybrid (H2), with our documented in cellulo (live cell- based) assay utilizing a fluorescent GM2 ganglioside derivative. Unfortunately when Tay-Sachs cells were transfected with either the H1 or H2 hybrid construct and then were fed the GM2 derivative, no significant increase in its turnover was detected. In vitro assays with the isolated H1 or H2 homodimers confirmed that neither was capable of human GM2AP-dependent hydrolysis of GM2 ganglioside.

Why are they having infant colic? A nested case-control study.

We aimed to analyse infant (birth characteristics, feeding type, faecal enzyme activities) and environmental (maternal smoking, nutrition and psychological status, mother-child bonding, family structure, support for the mother, familial atopy) risk factors for infant colic and to follow infants with respect to physical growth, sleeping status up to 8 months of age in a nested case-control study. 660 mothers who delivered at Dr Zekai Tahir Burak Maternity Hospital, were enrolled within 3-72 h post delivery. Each infant with inconsolable persistent crying and four matched infants with no crying episodes were invited by phone to Hacettepe University Ihsan Dogramaci Children's Hospital at 30-45 days post partum. At 40-55 days, we examined the infants and gave mothers a questionnaire, including crying characteristics of the infants; 47 infants were diagnosed with colic and 142 as non-colic. When the infants were 7-8 months old, another interview was done. The colic group had higher proportions of less-educated (≤ 8 years) and smoking mothers, extended family and families with domestic violence than the non-colic group. The colic group of mothers had significantly higher rates of 'impaired bonding' in the Postpartum Bonding Questionnaire, higher scores on the Edinburgh Postnatal Depression Scale, higher scores for hostility subscales of the Brief Symptom Inventory and a more irregular sleep pattern than the non-colic group. No differences were revealed for faecal enzyme activities. At 7-8 months, the colic group was shorter than the non-colic group. Colic was associated with various perinatal factors (maternal education, smoking habits, cheese consumption, hostility scores and domestic violence) and having colic in infancy negatively affected the sleeping pattern and the height of the infant.

Beta-estradiol reduces lipid peroxidation and depth of injury in cold-induced brain injury model.

Estrogen has neuroprotective effects in neurodegenerative disorders and models of neuronal damage. The effectiveness of estradiol (EST) (1 mg/kg and 10 mg/kg doses) in cold-induced brain injury (CIB) model was evaluated and compared with standard dexamethasone treatment. Forty-eight male Wistar rats (250-300 g) were randomly divided into 6 groups: sham operated, CIB + no treatment, CIB + 1 mg/kg dexamethasone, CIB + 1 mg/kg EST, CIB + 10 mg/kg EST, CIB + vehicle (ethanol). Rats were placed on stereotaxic frame and a craniotomy of 5 mm diameter was performed on the parietal lob under general anesthesia (ketamine+xylazine). A metal probe of 5 mm diameter was cooled (2 min) in liquid nitrogen (-190 degrees C) and was applied on the craniotomy area for 3 min. The treatment was started immediately after the CIB. Twenty-four hours later the whole brain was isolated and study parameters were assessed. The parameters were tissue wet/dry weight ratio, lipid peroxidation, and histopathological examination of the depth of injury. Both 1 mg/kg dexamethasone and 1mg/kg EST treatment significantly reduced all the measured injury parameters, whereas 10 mg/kg EST had no effect on any of the parameters. This study shows that EST at lower concentrations is beneficial in this model of cold-induced brain injury. However, the effect of EST is dual and higher concentrations, in contrast, do not affect or even may be detrimental in brain injury.

T-786C polymorphism in promoter of eNOS gene as genetic risk factor in patients with erectile dysfunction in Turkish population.

OBJECTIVES: To investigate the effect of 2 endothelial nitric oxide synthase gene polymorphisms, namely, variable number of 27-bp tandem repeats in intron 4 and T-786C in the promoter region, on the susceptibility to erectile dysfunction (ED) in Turkish population. METHODS: A total of 72 patients with ED (mean age 54.3 +/- 9.2 years) diagnosed by Doppler ultrasonography and 71 healthy controls (mean age 55.4 +/- 8.2 years) were analyzed. Genotypes were determined through polymerase chain reaction with or without restriction endonuclease digestions. RESULTS: Genotype distribution for CC genotype of T-786C polymorphism in promoter was significantly different between patients with ED and controls, the genotype frequency being 31.9% and 12.7%, respectively (P = .019). The univariate odds ratio (OR) associated with CC alleles revealed 3 times increased risk for ED (OR = 3.2; 95% confidence interval [CI], 1.4-7.6; P = .006). The risk also holds when excluding patients with hypertension and diabetes mellitus (P = .012, OR = 3.1; 95% CI, 1.2-7.7) as well as obesity (P = .05, OR = 4; 95% CI, 1.05-15.3). Patients with CC genotype of promoter present earlier symptoms of ED (51.7%) compared with controls (10.7%) (P <.001). No significant correlation was observed with variable number of tandem repeats in intron 4 and with the type of vascular insufficiency. CONCLUSIONS: The CC genotype of T-786C polymorphism in the promoter of eNOS gene is associated with increased risk of ED in Turkish population. Earlier onset of ED with CC genotype suggests that CC allele is an independent risk factor for endothelial dysfunction in the absence of other risk factors (hypertension, diabetes mellitus, obesity). An impaired NO production because of CC alleles may account for pathophysiology of ED.

Intron 4 VNTR polymorphism of eNOS gene is protective for cardiac syndrome X.

Microvascular abnormalities caused by endothelial dysfunction seem to be responsible for the myocardial ischemia in patients with cardiac syndrome X (CSX). Nitric oxide is a key mediator of endothelial function and is synthesized by endothelial nitric oxide synthase (eNOS). We investigated if the 3 potential polymorphisms of the eNOS gene (VNTR in intron 4, T786C polymorphism in the promoter region, and G894T polymorphism in exon 7) are independent risk factors for CSX. Sixty-nine patients with CSX and 73 healthy controls were studied. Genotypes were determined through polymerase chain reaction with or without restriction endonuclease digestions. Genotype distribution was significantly different between patients with CSX and controls for intron 4aa (allele for 4 repeats of 27 bp), intron 4aa genotype frequency being 3.2% and 6.8%, respectively. The presence of intron 4a is 3.2 (odds ratio) times protective (95% confidence interval, 1.5-6.8) for the risk of CSX disease. The protective effect of intron 4a polymorphism also holds after adjustment for age and sex and when the study group is limited to those without hypertension and hyperlipidemia. No significant difference was observed in genotype distribution of G894T and T786C polymorphism between patients with CSX and controls. In conclusion, intron 4aa genotype of eNOS gene is protective for CSX. No association was found between promoter and exon 7 polymorphisms of eNOS gene and CSX.

Distribution of endothelial nitric oxide synthase gene polymorphisms in Turkish population.

Nitric oxide (NO) is the major mediator in the regulation of vascular homeostasis. It is synthesized by endothelium from arginine with the catalytic help of endothelial NO synthase (eNOS). Polymorphisms in the eNOS gene have been associated inconsistently with many vascular diseases. Conflicting results may arise from ethnic variations, notably in control-case studies. Therefore, to obtain reliable information and improve the design of such genetic association studies, we examined the distribution of genetic alleles of 3 clinically relevant eNOS polymorphisms (the variable number of tandem 27-base pair [bp] repeats in intron 4, T-786C in promoter, and G894T in exon 7) in 300 healthy Turkish individuals with a mean age of 50.07 (SD 12.15) years (range, 22-78 years; 50.7% men and 49.3% women). The haplotype frequency was estimated and associations between 3 polymorphisms were evaluated. We discussed the similarity and differences in the distribution of alleles with other populations. The allele frequencies were 45.3%, 48%, and 62.7% for GG of exon 7, TT of promoter, and bb of intron 4 (wild types), respectively. The most common haplotype combines the wild-type alleles (G-T-b) for all 3 polymorphisms (estimated frequency, 37.6%). The linkage analysis between each pairwise combination showed specific associations between T-786C polymorphism in promotor and G894T polymorphism in exon 7 (positive D' value, +0.3387). No significant correlation was found in the genotype distribution of the 3 polymorphisms with age, sex, and obesity. Our eNOS gene allele distributions resemble those of Caucasians and white populations. Our data showed ethnic differences with other populations in the allele distribution of eNOS gene besides conserved distribution of these polymorphisms in Turkish population. This study produced a reference control data for the 3 eNOS polymorphisms in Turkish population and will be helpful in planning eNOS association studies in vascular disease.

Protective role of 27bp repeat polymorphism in intron 4 of eNOS gene in lacunar infarction.

Association of the three potential endothelial nitric oxide synthase gene (eNOS) polymorphisms (T-786C in promoter region, G894T in exon 7 and tandem 27-bp repeats in intron 4) with an increased risk of lacunar infarction (LI) were investigated. Genotypes of 70 patients and 81 healthy controls were determined through PCR with or without RFLP. Flow-mediated dilatation (FMD) was performed to assess endothelial-dependent vasodilatation, whereas the endothelial-independent vasodilatation was assessed with nitroglycerin (NTG). Genotype distribution was significantly different between LI patients and controls for intron 4aa (alleles for four repeats), genotype frequency being 1.4% and 16.0%, respectively (odds ratio for additive effect, 0.47; 95% CI, 0.28-0.81; p=0.006). Haplotypes with the intron 4aa polymorphism were significantly higher in controls when compared with the LI group (p=0.001). Diminished FMD but normal NTG response confirmed that patients with LI have generalized endothelial dysfunction. Intron 4aa genotype of eNOS gene seems to be protective for isolated LI and the effect was potentiated by the absence of 786C polymorphism in any allele of the promoter region.

Identification of two novel arylsulfatase A mutations with a polymorphism as a cause of metachromatic leukodystrophy.

OBJECTIVE: Metachromatic leukodystrophy is a lysosomal storage disorder caused by the deficiency of arylsulfatase A or saposin B. Enzyme deficiency leads to the accumulation of sulfatide, which results in severe demyelination. METHODS: In this study, clinically suspected patients were diagnosed as metachromatic leukodystrophy by enzyme analysis using p-nitrocathecol sulfate as substrate. Eight exons and flanking regions of arylsulfatase A gene of patients were amplified by polymerase chain reaction and then subjected to single stranded conformational polymorphism analysis. Polymerase chain reaction products of suspicious exons in single stranded conformational polymorphism were purified from agarose gel and sequenced. RESULTS: DNA sequencing revealed two novel disease-causing missense mutations: the first one is 1568G-->A, 307Glu-->Lys in exon 5 which is together with a 2161C-->T, 391Thr-->Ser polymorphism in exon 7; and the second one is 1603G-->T, 318Trp-->Cys in exon 5. DISCUSSION: These two mutations are in highly conserved structural elements region of the arylsulfatase A protein. Thus, missense mutations 307Glu-->Lys in exon 5 and 318Trp-->Lys in exon 5 probably change the active site conformation by disrupting the sixth alpha helix and the twelfth beta-sheet structure of the arylsulfatase A protein, respectively, and cause deficiency in enzyme activity. This study provides the molecular basis for understanding the mechanism underlying metachromatic leukodystrophy.

Biochemical and molecular characterization of mutant hexosaminidase A in a Turkish family.

BACKGROUND: Tay-Sachs disease is a form of monosialoganglioside triaose (GM2) gangliosidosis that results from the mutations in the alpha-subunit gene of hexosaminidase A. In the B1 variant, the active site of the alpha-subunit of the enzyme is thought to be affected. In the present study, a patient who had previously been diagnosed as a B1 variant is further analyzed. The patient's parents and brother were also analyzed. METHODS: Single-stranded conformational polymorphism (SSCP) and DNA sequencing analysis were conducted in all cases. In addition, hexosaminidase A (Hex A) was isolated from leukocyte homogenates of the patient's parents and brother using DE 52 ion-exchange chromatography, and thermostability analyses of the isolated enzymes were performed. RESULTS: Hexosaminidase A of the parents was found to be more thermostable than normal Hex A. DNA sequencing analysis revealed a 12-bp deletion mutation in exon 10 of the Hex A gene. The patient was a homozygote and the parents were heterozygotes for the mutation, which could also be observed at the DNA double strands by SSCP analysis. These deleted bases are located within the catalytic domain of the alpha-subunit. CONCLUSIONS: The 12-bp deletion mutation in exon 10 of Hex A is responsible for the increased thermostability of the enzyme. Considering this mutation has previously been found in a Turkish Tay-Sachs patient, the patient in the present study may have another mutation on the Hex B gene that causes decreased thermostability of the enzyme. Thermal inactivation assay may not be sufficient for a correct diagnosis in such unusual cases.

Effects of hormone replacement therapy on plasma homocysteine and C-reactive protein levels.

In order to investigate the effect of hormone replacement therapy (HRT) on plasma homocysteine and C-reactive protein (CRP) levels 46 healthy postmenopausal women were prospectively enrolled. HRT, which was either 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate (MPA) or 0.625 mg/day CEE alone were administered. After 6 months, estrogen alone significantly increased serum CRP concentrations (p = 0.039), however, estrogen plus progesterone therapy did not significantly alter serum CRP levels. Both regimens significantly decreased plasma homocysteine levels (CEE group p = 0.034, CEE+MPA group p = 0.007). It was concluded that the reduction in plasma homocysteine levels with both regimens might contribute to the cardiovascular benefit of HRT and the CRP raising effect of estrogen might be partially prevented by the addition of progesterone.