Role of the follistatin gene in women with polycystic ovary syndrome

OBJECTIVE

To search for mutations in the coding exons of the follistatin gene of women diagnosed with polycystic ovary syndrome (PCOS).

DESIGN

Controlled clinical study.

SETTING

Tertiary institutional hospital.

PATIENT(S)

Thirty-four women diagnosed with PCOS and 15 healthy control women.

INTERVENTION(S)

Whole blood and serum samples were collected during the follicular phase of the menstrual cycle.

MAIN OUTCOME MEASURE(S)

Circulating total testosterone (T), sex hormone-binding globulin (SHBG), calculated free T (FT), androstenedione (A), dehydroepiandrosterone-sulfate (DHEAS), LH, FSH, E2, and basal and adenocorticotropic hormone (ACTH)-stimulated 17-hydroxyprogesterone (17-OHP) were determined. Insulin resistance was estimated from fasting glucose and insulin levels, using the homeostasis model assessment. The coding regions of the follistatin gene were studied by heteroduplex analysis after polymerase chain reaction amplification.

RESULT(S)

Women with PCOS presented with higher body-mass index, insulin resistance, T, FT, A, and ACTH-stimulated 17-OHP serum concentrations and lower SHBG serum levels, as compared with controls. No differences were observed among the groups in serum DHEAS, basal 17-OHP, E(2), LH, and FSH. No mutations were found in coding regions of the follistatin gene, with the exception of a G to A change at cDNA position 951, resulting in a silent mutation. This change was present in 2 (5.9%) of 34 patients and 1 (6.7%) of 15 controls.

CONCLUSION(S)

Mutations in the coding regions of the follistatin gene do not appear to be related to PCOS.

Role of the pentanucleotide (tttta)(n) polymorphism in the promoter of the CYP11a gene in the pathogenesis of hirsutism

OBJECTIVE

To determine if the (tttta)(n) repeat polymorphism in the promoter region of CYP11a gene is associated with hirsutism and hyperandrogenism in women from Spain.

DESIGN

Controlled clinical study.

SETTING

Tertiary-care institutional hospital.

PATIENT(S)

Ninety-two hirsute women and 33 healthy control women.

INTERVENTION(S)

Basal and adrenocorticotropin-stimulated serum samples and genomic DNA extracted and purified from whole-blood samples were obtained during the follicular phase of the menstrual cycle.

MAIN OUTCOME MEASURE(S)

CYP11a (tttta)(n) repeat-polymorphism genotype and serum ovarian and adrenal androgen levels.

RESULT(S)

None of the CYP11a (tttta)(n) polymorphic alleles was associated with hirsutism. The absence of the four-repeat-units allele (4R-- genotype), which has been reported by other authors to be associated with polycystic ovary syndrome (PCOS), was found in 22.4% of the women studied here and was equally distributed among patients and controls, independently of the presence of PCOS and/or ovarian or adrenal hyperandrogenism. No differences were observed in serum hormone concentrations in 4R-- individuals as compared with subjects with at least one four-repeat-units allele.

CONCLUSION(S)

The (tttta)(n) repeat polymorphism in the promoter region of CYP11a does not appear to play any significant role in the pathogenesis of hirsutism and hyperandrogenism in women from Spain.

Signaling through CD38 induces NK cell activation

Human CD38 is a signal transduction molecule, and, concurrently, an ectoenzyme catalyzing the synthesis and degradation of cyclic ADP-ribose (cADPR), a potent Ca2+ mobilizer. One facet of CD38 that has not yet been addressed is its role in NK cells. To this end, the events triggered by CD38 ligation with agonistic mAb were analyzed on freshly purified human NK cells. Ligation was followed by (i) a significant rise in the intracellular level of Ca2+, (ii) increased expression of HLA class II and CD25, and (iii) tyrosine phosphorylation of discrete cytoplasmic substrates. The phosphorylation cascade involved CD3-zeta and FcepsilonRIgamma chains, zeta-associated protein (ZAP)-70 and the proto-oncogene product c-Cbl. NK effector functions were then analyzed: CD38 signaling was able (iv) to induce release of IFN-gamma and, more prominently, of granulocyte macrophage colony stimulating factor, as assessed by measuring both mRNA and protein products; and, lastly, (v) to induce cytolytic effector functions on target cells after IL-2 activation, as shown both by cytotoxicity assays and ultrastructural changes. The tyrosine-phosphorylated substrates and all the effects mediated by CD38 were similar to those observed following triggering via CD16 (FcgammaRIIIA); moreover, Ca2+ mobilization via CD38 no longer operated in NK-derived cell lines lacking CD16. These results suggest that the activation signals transduced by CD38 in NK cells elicit relevant cellular events. The effects are similar to those elicited via CD16 and possibly rely on common signaling pathways.

Screening for mutations in the steroidogenic acute regulatory protein and steroidogenic factor-1 genes, and in CYP11A and dosage-sensitive sex reversal-adrenal hypoplasia gene on the X chromosome, gene-1 (DAX-1), in hyperandrogenic hirsute women

Abstract Abnormalities in adrenal and/or ovarian steroidogenesis are found in most patients with hirsutism. The rate-limiting step in the synthesis of steroids in the ovary and the adrenal is the conversion of cholesterol into pregnenolone by cholesterol side-chain cleavage enzyme (P450scc), encoded by the gene CYP11A, after cholesterol is introduced into the mitochondria by the steroidogenic acute regulatory protein (StAR). DAX-1 is a repressor of StAR gene expression, and steroidogenic factor-1 (SF-1) is a regulator of CYP11A, DAX-1, and StAR gene. Mutations in any of these factors resulting in gain of function, or loss of repression, of StAR or P450scc might contribute to the steroidogenic abnormalities present in hirsute patients. In the present study we have screened, using heteroduplex analysis, the genes encoding StAR and SF-1 as well as DAX-1 and CYP11A for mutations in genomic DNA from 19 women presenting with hirsutism and increased serum androgen levels. When variants were found, analysis was extended to a larger group of hyperandrogenic patients and nonaffected women. Two variants were identified in the SF-1 gene. A G-->C change in exon 6, resulting in an Arg(365)Pro mutation, was found in 1 of 45 patients, but not in controls. Also, a Gly(146)Ala missense mutation, resulting from a G-->C change in exon 4, was found in 2 of 48 patients and in 2 of 50 nonaffected individuals. We identified a C-->T base pair change at position -33 of the StAR gene. Three of 48 patients and 3 of 43 controls presented this variant. No mutations were found in coding regions of the StAR gene. Analysis of CYP11A-coding regions identified a G-->A change in exon 3, resulting in a Val(179)Ile missense mutation. This mutation was found in 1 of 29 patients studied and was not present in 50 controls. Finally, analysis of DAX-1 showed no variant in any of the women studied. In conclusion, mutations in StAR, SF-1, CYP11A, and DAX-1 are seldom found in hirsute patients and do not explain the steroidogenic abnormalities found in these women.

Native hydrogen bonds in a molten globule: the apoflavodoxin thermal intermediate

The structure and energetics of protein-folding intermediates are poorly understood. We have identified, in the thermal unfolding of the apoflavodoxin from Anabaena PCC 7119, an equilibrium intermediate with spectroscopic properties of a molten globule and substantial enthalpy and heat capacity of unfolding. The structure of the intermediate is probed by mutagenesis (and phi analysis) of polar residues involved in surface-exposed hydrogen bonds connecting secondary-structure elements in the native protein. All hydrogen bonds analysed are formed in the molten globule intermediate, either with native strength or debilitated. This suggests the overall intermediate's topology and surface tertiary interactions are close to native, and indicates that hydrogen bonding may contribute significantly to shape the conformation and energetics of folding intermediates.

Stabilization of apoflavodoxin by replacing hydrogen-bonded charged Asp or Glu residues by the neutral isosteric Asn or Gln

Knowledge of protein stability principles provides a means to increase protein stability in a rational way. Here we explore the feasibility of stabilizing proteins by replacing solvent-exposed hydrogen-bonded charged Asp or Glu residues by the neutral isosteric Asn or GLN: The rationale behind this is a previous observation that, in some cases, neutral hydrogen bonds may be more stable that charged ones. We identified, in the apoflavodoxin from Anabaena PCC 7119, three surface-exposed aspartate or glutamate residues involved in hydrogen bonding with a single partner and we mutated them to asparagine or glutamine, respectively. The effect of the mutations on apoflavodoxin stability was measured by both urea and temperature denaturation. We observed that the three mutant proteins are more stable than wild-type (on average 0.43 kcal/mol from urea denaturation and 2.8 degrees C from a two-state analysis of fluorescence thermal unfolding data). At high ionic strength, where potential electrostatic repulsions in the acidic apoflavodoxin should be masked, the three mutants are similarly more stable (on average 0.46 kcal/mol). To rule out further that the stabilization observed is due to removal of electrostatic repulsions in apoflavodoxin upon mutation, we analysed three control mutants and showed that, when the charged residue mutated to a neutral one is not hydrogen bonded, there is no general stabilizing effect. Replacing hydrogen-bonded charged Asp or Glu residues by Asn or Gln, respectively, could be a straightforward strategy to increase protein stability.

A comparative study of the thermal stability of plastocyanin, cytochrome c(6) and Photosystem I in thermophilic and mesophilic cyanobacteria

Cytochrome c(6) (Cyt) from the thermophilic cyanobacterium Phormidium laminosum has been purified and characterized. It is a mildly acidic protein, with physicochemical properties very similar to those of plastocyanin (Pc). This is in agreement with the functional interchangeability of the two metalloproteins as electron donors to Photosystem I (PS I). The kinetic analyses of the interaction of Pc and Cyt with Photosystem I show that both metalloproteins reduce PS I with similar efficiencies, according to an oriented collisional kinetic model involving repulsive electrostatic interactions. The thermostability study of the Phormidium Pc/PS I system compared with those from mesophilic cyanobacteria (Synechocystis, Anabaena and Pseudanabaena) reveals that Pc is the partner limiting the thermostability of the Phormidium couple. The cross-reactions between Pc and PS I from different organisms demonstrate not only that Phormidium Pc enhances the stability of the Pc/PS I system using PS I from mesophilic cyanobacteria, but also that Phormidium PS I possesses a higher thermostability than the other photosystems.

Isolation and identification of autochthonous microbiota from a granitic aquifer and its variation after the bottling process

The autochthonous microbiota from a granitic aquifer in Spain were studied. Several bacterial strains were isolated and identified. The major components of the microbiota were Pseudomonas-like strains, Flavobacterium, Acinetobacter, and Alcaligenes. The variation in the number of microorganisms after the bottling process was studied. The initial bacterial population increased over the first 5 days after bottling. This increase was higher in samples from polyvinyl chloride bottles. Sonication usually increased the total cell counts. As expected, most of the autochthonous microbiota were not detected in the viable cell counts.

High prevalence of the polycystic ovary syndrome and hirsutism in women with type 1 diabetes mellitus

The current recommendation for strict metabolic control of type 1 diabetes mellitus requires the administration of supraphysiological doses of insulin, which might result in insulin-mediated stimulation of androgen synthesis, as occurs in insulin-resistant states. At present, the prevalence of hyperandrogenic disorders in women with type 1 diabetes mellitus is unknown. Eighty-five women with type 1 diabetes mellitus were evaluated for symptoms and signs of hyperandrogenism. In 68 of the patients, several serum androgen and hormone concentrations were measured. The polycystic ovary syndrome (PCOS) was defined by the presence of menstrual dysfunction, together with clinical and/or biochemical evidence of hyperandrogenism, and exclusion of other etiologies. Eighteen healthy women, menstruating regularly, served as controls for the androgenic profiles. Thirty-three patients (38.8%) presented hyperandrogenic disorders (16 had PCOS, and 17 had hirsutism without menstrual dysfunction). Type 1 diabetic patients with PCOS presented increased serum total and free testosterone concentrations, and serum androstenedione levels, but had normal serum sex hormone-binding globulin and dehydroepiandrosterone-sulfate levels. Hirsute type 1 diabetic women without menstrual dysfunction presented normal serum androgen levels. There were no significant differences between hyperandrogenic and nonhyperandrogenic type 1 diabetes mellitus women in clinical variables such as the duration of diabetes, age at diagnosis of diabetes, conventional or intensive insulin therapy, mean daily insulin dosage, or metabolic control. In conclusion, women with type 1 diabetes mellitus have a high prevalence of hyperandrogenic disorders, including PCOS and hirsutism.

Clinical importance of minimal residual disease in childhood acute lymphoblastic leukemia

By using rapid flow cytometric techniques capable of detecting one leukemic cell in 10(4) normal cells, we prospectively studied minimal residual disease (MRD) in 195 children with newly diagnosed acute lymphoblastic leukemia (ALL) in clinical remission. Bone marrow aspirates (n = 629) were collected at the end of remission induction therapy and at 3 intervals thereafter. Detectable MRD (ie, > or = 0.01% leukemic mononuclear cells) at each time point was associated with a higher relapse rate (P < .001); patients with high levels of MRD at the end of the induction phase (> or = 1%) or at week 14 of continuation therapy (> or = 0.1%) had a particularly poor outcome. The predictive strength of MRD remained significant even after adjusting for adverse presenting features, excluding patients at very high or very low risk of relapse from the analysis, and considering levels of peripheral blood lymphoblasts at day 7 and day 10 of induction therapy. The incidence of relapse among patients with MRD at the end of the induction phase was 68% +/- 16% (SE) if they remained with MRD through week 14 of continuation therapy, compared with 7% +/- 7% if MRD became undetectable (P = .035). The persistence of MRD until week 32 was highly predictive of relapse (all 4 MRD(+) patients relapsed vs 2 of the 8 who converted to undetectable MRD status; P = .021). Sequential monitoring of MRD by the method described here provides highly significant, independent prognostic information in children with ALL. Recent improvements in this flow cytometric assay have made it applicable to more than 90% of all new patients. (Blood. 2000;96:2691-2696)

Treatment of hirsutism with ethinyl estradiol-desogestrel contraceptive pills has beneficial effects on the lipid profile and improves insulin sensitivity

OBJECTIVE

To evaluate the effects on the lipid pattern and insulin sensitivity of hirsute women of an oral contraceptive pill containing 30 microg of ethinyl estradiol and 150 microg of desogestrel.

DESIGN

Prospective clinical study.

SETTING

Tertiary care institutional hospital.

PATIENT(S)

16 hirsute women.

INTERVENTION(S)

Women were evaluated at baseline and after receiving six cycles of oral contraceptive therapy.

MAIN OUTCOME MEASURE(S)

Body mass index (BMI); hirsutism score (nine body areas); serum levels of total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, apolipoprotein B, lipoprotein(a), and serum adrenal and ovarian androgens; and fasting glucose and insulin concentrations.

RESULT(S)

The mean serum total, HDL, and LDL cholesterol levels increased after six cycles of oral contraceptive therapy. Levels of HDL cholesterol were < 50 mg/dL in 7 of the 16 patients at baseline; these levels normalized in 4 patients after treatment. Serum total and LDL cholesterol remained within the normal range in all patients before and after therapy. No significant changes were observed in serum triglyceride, apolipoprotein B and lipoprotein(a) concentrations. Fasting insulin levels and insulin resistance as analyzed by homeostasis model assessment were reduced significantly after therapy. No changes in BMI were observed. Administration of oral contraceptive pills signifiCantly reduced the hirsutism score and hyperandrogenemia.

CONCLUSION(S)

Oral contraceptive pills containing low-dose ethinyl estradiol and desogestrel are effective in controlling hyperandrogenism and hirsutism and ameliorate the abnormal metabolic profile of women with hirsutism.

A prospective study of the prevalence of the polycystic ovary syndrome in unselected Caucasian women from Spain

We prospectively estimated the prevalence of the polycystic ovary syndrome (PCOS), as defined by the NIH/NICHHD 1990 endocrine criteria, in a population of 154 Caucasian women of reproductive age reporting spontaneously for blood donation. Anthropometric data; the presence of hirsutism, acne, and androgenic alopecia; and the menstrual history were recorded by a single investigator. In 145 women, blood samples were also obtained for measurement of serum androgen levels. PCOS was defined by the presence of 1) oligomenorrhea, 2) clinical and/or biochemical hyperandrogenism, and 3) exclusion of hyperprolactinemia, thyroid disorders, and nonclassic 21-hydroxylase deficiency. Hirsutism was defined by a modified Ferriman-Gallwey score of 8 or more, acne was considered as a sign of hyperandrogenism when persistent after the second decade of life, and hyperandrogenemia was defined by an increase in circulating testosterone or dehydroepiandrosterone sulfate or an increase in the free androgen index above the 95th percentile of the control values derived from the nonhirsute, nonacneic women having regular menses who were not receiving hormonal therapy. PCOS was present in 10(6.5%), hirsutism was present in 11 (7.1%), and acne was present in 19 (12.3%) of the 154 women. Our results demonstrate a 6.5% prevalence of PCOS, as defined, in a minimally biased population of Caucasian women from Spain. The polycystic ovary syndrome, hirsutism, and acne are common endocrine disorders in women.

Serum prostate-specific antigen concentrations are not useful for monitoring the treatment of hirsutism with oral contraceptive pills

Prostate-specific antigen (PSA) is produced in several female tissues, under the regulation of steroid hormones. Serum PSA levels are increased in women with hirsutism, and they correlate with serum androgen levels. Therefore, as a marker of androgen excess, measurement of serum PSA may play a role in monitoring the treatment of hirsutism with contraceptive pills. Sixteen hirsute patients were included in the study. Clinical and biochemical variables, including serum PSA (using an ultrasensitive chemiluminescent immunoassay), total testosterone, sex hormone-binding globulin, androstenedione, dehydroepiandrosterone-sulfate, estradiol, and gonadotropin concentrations were recorded at baseline and after 3 and 6 cycles of treatment with a monophasic contraceptive pill containing ethynylestradiol and desogestrel. Twenty-seven healthy women served as controls for serum PSA level and for the serum androgen profile. Serum PSA levels were higher in hirsute patients, as compared with healthy women (mean +/- SEM: 0.014 +/- 0.003 vs. 0.006 +/- 0.001 microg/L, P < 0.02). Despite a marked decrease in serum androgens (total testosterone and androstenedione, calculated free testosterone and free androgen index; and dehydroepiandrosterone-sulfate) and in the hirsutism score, and a marked increase in sex hormone-binding globulin levels, serum PSA levels did not change and remained detectable in all the hirsute patients after 3 and 6 cycles of treatment with contraceptive pills. In conclusion, the increased serum PSA levels present in hirsute patients do not change during treatment with contraceptive pills and do not parallel the amelioration in hirsutism and the decrease in serum androgen concentrations that occur during this treatment. Thus, serum PSA measurements have no apparent role in the management of hirsute patients on oral contraceptive treatment, at least with the ultrasensitive assays currently available.

The role of the CAG repeat polymorphism in the androgen receptor gene and of skewed X-chromosome inactivation, in the pathogenesis of hirsutism

The human androgen receptor (AR) gene contains a variable number of CAG repeats within exon 1. Shorter AR alleles, by increasing transactivation, may result in augmented AR-mediated sensitivity of the hair follicle. We have evaluated whether the number of CAG repeats, or if skewed inactivation of X-chromosome, favoring the presence of shorter AR alleles, influence hirsutism in women with and without hyperandrogenemia. Twenty-eight women with idiopathic hirsutism (normal serum androgens), 34 women with hyperandrogenic hirsutism (increased serum androgens), and 15 healthy control women were analyzed by evaluating the number of CAG repeats in genomic DNA, as well as the methylation pattern (after DNA digestion with HpaII), which allows identification of which allele is inactive. Despite marked differences among the groups in serum androgens, which were markedly increased in women with hyperandrogenic hirsutism as compared with women with idiopathic hirsutism and to controls, there were no significant differences among the groups in the number of CAG repeats. Moreover, skewed X-chromosome inactivation was found in 10 subjects (3 with idiopathic hirsutism, 5 with hyperandrogenic hirsutism, and 2 controls; P = 0.746) of the 67 women (14.9%) who were heterozygous for the AR gene. In several of these subjects, it was the shorter allele that was preferentially inactivated. In conclusion, neither the CAG repeat polymorphism in the AR gene, nor skewed X-chromosome inactivation, seem to play a significant role in the pathogenesis of hirsutism.

Dissecting the energetics of the apoflavodoxin-FMN complex

Many flavoproteins are non-covalent complexes between FMN and an apoprotein. To understand better the stability of flavoproteins, we have studied the energetics of the complex between FMN and the apoflavodoxin from Anabaena PCC 7119 by a combination of site-directed mutagenesis, titration calorimetry, equilibrium binding constant determinations, and x-ray crystallography. Comparison of the strength of the wild type and mutant apoflavodoxin-FMN complexes and that of the complexes between wild type apoflavodoxin and shortened FMN analogues (riboflavin and lumiflavin) allows the dissection of the binding energy into contributions associated with the different parts of the FMN molecule. The estimated contribution of the phosphate is greatest, at 7 kcal mol(-1); that of the isoalloxazine is of around 5-6 kcal mol(-1) (mainly due to interaction with Trp-57 and Tyr-94 in the apoprotein) and the ribityl contributes least: around 1 kcal mol(-1). The stabilization of the complex is both enthalpic and entropic although the enthalpy contribution is dominant. Both the phosphate and the isoalloxazine significantly contribute to the enthalpy of binding. The ionic strength does not have a large effect on the stability of the FMN complex because, although it weakens the phosphate interactions, it strengthens the isoalloxazine-protein hydrophobic interactions. Phosphate up to 100 mM does not affect the strength of the riboflavin complex, which suggests the isoalloxazine and phosphate binding sites may be independent in terms of binding energy. Interestingly, we find crystallographic evidence of flexibility in one of the loops (57-62) involved in isoalloxazine binding.

[Vascular hemichorea: clinical-radiological correlation]

INTRODUCTION

Hemichorea is uncommon in acute cerebrovascular accidents. Its appearance is in relation to the contralateral involvement of the basal ganglia, particularly the striate ganglion. With current neuroimaging techniques it is possible to identify the lesions responsible for these abnormal movements. Magnetic resonance (MR) is the technique of choice for detection of small sized lesions.

OBJECTIVE

We have analysed our series of patients to try to relate the site of the lesion to the appearance of chorea.

PATIENTS AND METHODS

We made a retrospective study of the cases of hemichorea of vascular origin admitted between January 1993 and April 1999. In all cases, cerebral CAT and/or MR had been done to find the site of the lesion.

RESULTS

A total of 10 patients with an average age of 72.5 years (range: 55-85) was found. In eight of them (80%) lesions were found in the basal ganglia, half of which were of ischemic type and the other half hemorrhagic. The sites were: caudate nucleus in one case (10%), thalamus in two cases (20%) and capsulo-lenticular lesions in five cases (50%). All lesions were contralateral to the side of the body affected except in one case with a left thalamic haematoma and homolateral hemichorea.

CONCLUSIONS

The lesions found were very varied in site. In 20% of the cases they were not detected by conventional neuroimaging techniques. This fact supports the concept of a functional global network of the basal ganglia which may be interrupted at several points and lead to the same clinical findings.

The presence of the 21-hydroxylase deficiency carrier status in hirsute women: phenotype-genotype correlations

OBJECTIVE

To determine the role of heterozygosity for mutations in the 21-hydroxylase gene (CYP21) in the pathogenesis of hyperandrogenism.

DESIGN

Controlled clinical study.

SETTING

Tertiary care institutional hospital.

PATIENT(S)

Forty hirsute women and 13 healthy control women.

INTERVENTION(S)

The source of androgen excess was determined by the changes in serum testosterone levels in response to a single 3.75-mg i.m. dose of triptorelin.

MAIN OUTCOME MEASURE(S)

CYP21 molecular genetic analysis and serum 17-hydroxyprogesterone levels.

RESULT(S)

Eight patients and one control were heterozygous carriers of CYP21 mutations. Two patients with adrenal hyperandrogenism and one patient with ovarian hyperandrogenism, who carried the V281L mutation had an increased ACTH-stimulated 17-hydroxyprogesterone level (>4.1 ng/mL) that persisted during gonadal suppression. Another patient with adrenal hyperandrogenism carried the V281L mutation, and her ACTH-stimulated 17-hydroxyprogesterone level was elevated only during gonadal suppression. Four patients (three with idiopathic hirsutism, one with ovarian hyperandrogenism) and one control were carriers of CYP21 mutations typically associated with classic congenital adrenal hyperplasia but had normal basal and ACTH-stimulated 17-hydroxyprogesterone levels. Nine patients without CYP21 mutations had increased ACTH-stimulated 17-hydroxyprogesterone levels; these decreased to normal in six of the patients during gonadal suppression.

CONCLUSION(S)

The response of serum 17-hydroxyprogesterone to ACTH does not predict CYP21 carrier status. No clear concordance was found between the CYP21 genotype and the functional origin of androgen excess.

Electron-nuclear double resonance and hyperfine sublevel correlation spectroscopic studies of flavodoxin mutants from Anabaena sp. PCC 7119

The influence of the amino acid residues surrounding the flavin ring in the flavodoxin of the cyanobacterium Anabaena PCC 7119 on the electron spin density distribution of the flavin semiquinone was examined in mutants of the key residues Trp(57) and Tyr(94) at the FMN binding site. Neutral semiquinone radicals of the proteins were obtained by photoreduction and examined by electron-nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE) spectroscopies. Significant differences in electron density distribution were observed in the flavodoxin mutants Trp(57) --> Ala and Tyr(94) --> Ala. The results indicate that the presence of a bulky residue (either aromatic or aliphatic) at position 57, as compared with an alanine, decreases the electron spin density in the nuclei of the benzene flavin ring, whereas an aromatic residue at position 94 increases the electron spin density at positions N(5) and C(6) of the flavin ring. The influence of the FMN ribityl and phosphate on the flavin semiquinone was determined by reconstituting apoflavodoxin samples with riboflavin and with lumiflavin. The coupling parameters of the different nuclei of the isoalloxazine group, as detected by ENDOR and HYSCORE, were very similar to those of the native flavodoxin. This indicates that the protein conformation around the flavin ring and the electron density distribution in the semiquinone form are not influenced by the phosphate and the ribityl of FMN.

The CD3-gamma delta epsilon transducing module mediates CD38-induced protein-tyrosine kinase and mitogen-activated protein kinase activation in Jurkat T cells

We have examined the ability of the CD3-gamma delta epsilon and CD3-zeta signaling modules of the T cell receptor (TCR) to couple CD38 to intracellular signaling pathways. The results demonstrated that in TCR+ T cells that express the whole set of CD3 subunits CD38 ligation led to complete tyrosine phosphorylation of both CD3-zeta and CD3-epsilon polypeptide chains. In contrast, in TCR+ cells with a defective CD3-zeta association CD38 engagement caused tyrosine phosphorylation of CD3-epsilon but not of CD3-zeta. Despite these differences, in both cell types CD38 ligation resulted in protein-tyrosine kinase and mitogen-activated protein kinase activation. However, in cells expressing chimerical CD25-zeta or CD25-epsilon receptors or in a TCR-beta- Jurkat T cell line, CD38 ligation did not result in tyrosine phosphorylation of the chimeric receptors, or CD3 subunits, or protein-tyrosine kinase or mitogen-activated protein kinase activation. In summary, these results support a model in which CD38 transduces activating signals inside the cell by means of CD3-epsilon and CD3-zeta tyrosine phosphorylation. Moreover, these data identify the CD3-gamma delta epsilon signaling module as a necessary and sufficient component of the TCR/CD3 complex involved in T cell activation through CD38.

Energetics of a hydrogen bond (charged and neutral) and of a cation-pi interaction in apoflavodoxin

Anabaena apoflavodoxin contains a single histidine residue (H34) that interacts with two aromatic residues (F7 and Y47). The histidine and phenylalanine rings are almost coplanar and they can establish a cation-pi interaction when the histidine is protonated. The histidine and tyrosine side-chains are engaged in a hydrogen bond, which is their only contact. We analyse the energetics of these interactions using p Ka-shift analysis, double-mutant cycle analysis at two pH values, and X-ray crystallography. The H/F interaction is very weak when the histidine is neutral, but it is strengthened by 0.5 kcal mol-1on histidine protonation. Supporting this fact, the histidine p Kain a F7L mutant is 0.4 pH units lower than in wild-type. The strength of the H/Y hydrogen bond is 0.7 kcal mol-1when the histidine is charged, and it becomes stronger (1.3 kcal mol-1) when the histidine is neutral. This is consistent with our observation that the (H34)Nepsilon2-OH(Y47) distance is slightly shorter in the apoflavodoxin structure at pH 9.0 than in the previously reported structure at pH 6.0. It is also consistent with a histidine p Kavalue 0.6 pH units higher in a Y47F mutant than in the wild-type protein. We suggest that the higher stability of the neutral hydrogen bond could be due to a higher desolvation penalty of the charged hydrogen bond that would offset its more favourable enthalpy of formation. The relationship between hydrogen bond strength and the contribution of hydrogen bonds to protein stability is discussed.

[The validity of the classification criteria of the International Headache Society for migraine, episodic tension headache and chronic tension headache]

INTRODUCTION

We analysed the value of the diagnostic criteria of the International Headache Society (IHS) for the classification of the primary headaches in a headache clinic.

PATIENTS AND METHODS

The IHS criteria were applied to classify 208 headaches in 194 patients. Forty-two had migraine, 18 tension type headache and 76 chronic daily headaches (CDH).

RESULTS

The value of IHS criteria in order to distinguish migraine from tension type headache have a specificity of 94% and a predictive positive value of 99%. The predictive negative value is 63%. The more specific symptoms for migraine were severity, photophobia, phonofobia and vomits. IHS criteria for chronic tension type headache have a very low sensibility; only the 45% of these headaches meet criteria. If we applied the criteria of Silberstein et al we can see that, without the patient history, symptoms don't distinguish between chronic tension type headache, transformed migraine and new daily persistent headache. The most specific features for distinguishing the transformed migraine were worsening with activity, vomiting and pulsating. A 62% of the CDH have analgesic overuse.

CONCLUSIONS

IHS criteria distinguish accurately between migraine and tension type headache. Symptoms do not differenciate the different kinds of CDH.

Generation of antigen-specific cytotoxic T lymphocytes and regulation of cytokine production takes place in the absence of CD3zeta

The TCR-associated protein CD3zeta plays a major role in regulating the state of responsiveness to peptide-MHC complexes on the surface of antigen-presenting cells. In this paper the requirement of CD3zeta in the generation of cytotoxic T cells was compared with its requirement in cytokine gene activation in two mutant mice: ZKO mice with a disrupted CD3zeta gene and ZTG mice in which a truncated CD3zeta segment was expressed as a transgene on the ZKO background. Upon infection of ZTG mice with lymphocytic choriomeningitis virus (LCMV), antigen-specific cytotoxic T lymphocyte (CTL) responses were detected, identical to responses in wild-type mice. In addition, antigen-specific CTL responses to allogeneic class I and class II MHC in ZTG animals were indistinguishable from those in wild-type animals. However, CTL responses to the same major antigens were not detectable in ZKO mice. We conclude that the signal transduction pathways leading to CTL development and cytokine production can be triggered through TCR in the absence of functional CD3zeta, provided the remainder of the TCR-CD3 complex is expressed at high levels on the cell surface. Surprisingly, IFN-gamma production in response to LCMV followed the same kinetics in ZKO, ZTG and wild-type mice. However, in vitro studies showed that cytokine production in general was abnormally regulated in T lymphocytes from ZKO mice, in contrast to ZTG T cells. Taken together, these studies support the hypothesis that development of CTL can take place in the absence of functional CD3zeta. However, CTL development requires stronger TCR-initiated signal transduction events than induction of cytokine genes.

[Reference values for the central motor conduction time and silent period obtained by the transcranial magnetic stimulation]

INTRODUCTION

Normal values of reference to transcranial magnetic stimulation for the motor central conduction time (CCT) and silent period (SP) is recorded in 30 healthy control subjects over abductor pollicis brevis.

MATERIAL AND METHODS

We get for the CCT four measurements: two with low intensity of stimulus, 5% plus the motor threshold, with and without facilitation (CCT1 and CCT1 fac.); and two with high intensities of stimulus, elevating the magnetic stimulation intensity to 1.5 times the threshold (CCT2 and CCT2 fac.).

RESULTS AND CONCLUSIONS

The mean and standard deviation of each measurement are: CCT1: 9.34 +/- 1.19, CCT1 fac.: 7.12 +/- 1.1. CCT2: 8.84 +/- 1.05 and CCT2 fac.: 6.57 +/- 1.05. Given that the CCT and SP doesn't follow a normal distribution, the medium and the 5-95% percentiles for the normal values of reference are calculated; there are: CCT1: 7.15-11.32, CCT1 fac: 5.27-9.42. CCT2: 7.05-10.73 and CCT2 fac: 4.91-9.14. For the silent period gets only one measurement employing high intensities. These last measurement were recorded in two localizations: on vertex and on motor area, selecting the greater duration. Given the great individual variability of this period in normal population absolute and ratio for the difference duration of SP between both sides are calculated. The latency of the SP is 50.2 +/- 5.99, 95 percentiles 39.1-64.63, the duration 151 +/- 32.51, 95 percentiles 102.63-239.55. The total SP measured from the discharge of the stimulus to the end of the silent period is 201.71 +/- 33.27; 95 percentiles: 151.39-296.4. The comparison of both hemispheres would give us pathological security for the 99.99% of the population for more than 14.94 ms of absolute difference, and for less of the 79.81% of ratio difference. A summary of the discoveries of the silent period in different pathologies is contributed in the discussion.

Apoflavodoxin: structure, stability, and FMN binding

Flavodoxins are one domain alpha/beta electron transfer proteins that participate in photosynthetic reactions. All flavodoxins carry a molecule of flavin mononucleotide (FMN), non-covalently bound, that confers redox properties to the protein. There are two structurally distinct flavodoxins, short ones and long flavodoxins; the latter contain an extra loop with unknown function. We have undertaken the study of the stability and folding of the apoflavodoxin from Anabaena (a long flavodoxin) and the analysis of the interaction between the apoflavodoxin and FMN. Our studies indicate that apoflavodoxin folds in a few seconds to a form that is competent in FMN binding. The stability of this apoflavodoxin is low and its urea denaturation can be described by a two-state mechanism. The role of the different parts of the apoflavodoxin in the stability and structure of the whole protein is being investigated using mutagenesis and specific cleavage to generate apoflavodoxin fragments. The X-ray structure of apoflavodoxin is very similar to that of its complex with FMN, the main difference being the conformation of the two aromatic residues that sandwich FMN in the complex. In apoflavodoxin these groups interact with each other so closing the FMN binding site. Despite this fact, apoflavodoxin binds FMN tightly and rapidly, and the resulting holoflavodoxin displays a high conformational stability. We have found that one role of the aromatic residues that interact with FMN is to help to retain bound the reduced form of the cofactor whose complex with apoflavodoxin is otherwise too weak.