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.

The polycystic ovary syndrome associated with morbid obesity may resolve after weight loss induced by bariatric surgery

CONTEXT

The polycystic ovary syndrome (PCOS) is frequently associated with obesity. However, there are very few data about PCOS in morbid obesity, especially with regard to its evolution after bariatric surgery.

OBJECTIVE

The objective of this study was to evaluate the response of PCOS to the sustained and marked weight loss achieved by bariatric surgery in morbidly obese women.

DESIGN

This was a longitudinal prospective nonrandomized evaluation.

SETTINGS

The study was performed at an academic hospital.

PATIENTS

Thirty-six consecutive premenopausal women submitted to bariatric surgery were screened for PCOS, which was present in 17.

INTERVENTIONS

Bariatric surgery was performed.

MAIN OUTCOME MEASURES

Hyperandrogenism, menstrual function, and insulin resistance were estimated before and at least 6 months after bariatric surgery in 12 patients with PCOS.

RESULTS

Weight loss (41 +/- 9 kg after 12 +/- 5 months) was paralleled by decreases in the hirsutism score (from 9.5 +/- 6.8 to 4.9 +/- 4.2; P = 0.001), total (69 +/- 32 to 42 +/- 19 ng/dl; P < 0.02) and free testosterone (from 1.6 +/- 0.7 to 0.6 +/- 0.3 ng/dl; P < 0.005), androstenedione (from 4.1 +/- 1.5 to 3.0 +/- 0.9 ng/ml; P < 0.02), and dehydroepiandrosterone sulfate (from 2000 +/- 1125 to 1353 +/- 759 ng/ml; P < 0.005); amelioration of insulin resistance estimated by homeostasis model assessment (from 6.0 +/- 3.0 to 1.6 +/- 1.0; P < 0.001); and restoration of regular menstrual cycles and/or ovulation in all patients.

CONCLUSIONS

The PCOS is a frequent finding in women with morbid obesity and may resolve after weight loss induced by bariatric surgery.

Histidine-aromatic interactions in barnase. Elevation of histidine pKa and contribution to protein stability

Aromatic side-chains are found in the vicinity of histidine residues in many proteins and protein complexes. We have studied the interaction between a histidine residue (His18) and aromatic residues at position 94 in barnase. Three different techniques have been applied to show that Trp94 interacts more strongly with the protonated form of His18. The aromatic-histidine interaction stabilizes the protonated form of histidine by 0.8 to 1 kcal mol-1 relative to the unprotonated and, thereby, increases its pKa value. This was shown indirectly from the pH dependence of the stability of the wild-type protein and the mutant Trp94----Leu; and directly from the difference in pKa of His18 between wild-type barnase and the same mutant protein, and from double-mutant cycles that measure the total interaction energy of Trp94 with His18 at both low and high pH. When Trp94 is replaced by other aromatic amino acids, the strength of the interaction decreases in the series His-Trp greater than His-Tyr greater than His-Phe. The interaction is not masked by high salt concentrations. The raising of the pKa value of His18 by interaction with Trp94 is shown to be consistent with solution studies with model compounds. The histidine-aromatic interaction could have implications in binding and catalysis for modulation of the histidine pKa value.

Alpha-helix stability in proteins. I. Empirical correlations concerning substitution of side-chains at the N and C-caps and the replacement of alanine by glycine or serine at solvent-exposed surfaces

The importance of amino acid side-chains in helix stability has been investigated by making a series of mutations at the N-caps, C-caps and internal positions of the solvent-exposed faces of the two alpha-helices of barnase. There is a strong positional and context dependence of the effect of a particular amino acid on stability. Correlations have been found that provide insight into the physical basis of helix stabilization. The relative effects of Ala and Gly (or Ser) may be rationalized on the basis of solvent-accessible surface areas: burial of hydrophobic surface stabilizes the protein as does exposure to solvent of unpaired hydrogen bond donors or acceptors in the protein. There is a good correlation between the relative stabilizing effects of Ala and Gly at internal positions with the total change in solvent-accessible hydrophobic surface area of the folded protein on mutation of Ala----Gly. The relationship may be extended to the N and C-caps by including an extra term in hydrophilic surface area for the solvent exposure of the non-intramolecularly hydrogen-bonded main-chain CO, NH or protein side-chain hydrogen bonding groups. The requirement for solvent exposure of the C-cap main-chain CO groups may account for the strong preference for residues having positive phi and psi angles at this position, since this alpha L-conformation results in the largest solvent exposure of the C-terminal CO groups. Glycine in an alpha L-conformation results in the greatest exposure of these CO groups. Further, the side-chains of His, Asn, Arg and Lys may, with positive phi and psi-angles, form a hydrogen bond with the backbone CO of residue in position C -3 (residues are numbered relative to the C-cap). The preferences at the C-cap are Gly much greater than His greater than Asn greater than Arg greater than Lys greater than Ala approximately Ser approximately greater than Asp. The preferences at the N-cap are determined by hydrogen bonding of side-chains or solvent to the exposed backbone NH groups and are: Thr approximately Asp approximately Ser greater than Gly approximately Asn greater than Gln approximately Glu approximately His greater than Ala greater than Val much greater than Pro. These general trends may be obscured when mutation allows another side-chain to become a surrogate cap.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of alanine versus glycine in alpha-helices on protein stability

The rational design of proteins requires knowledge of the helix-forming propensities (s-values) of the different amino acids. There is, however, considerable controversy about the relative values for alanine and glycine. We find from experiments on mutants of barnase that the relative effect of Ala versus Gly on helix stability depends crucially on the position in the helix (whether they are at the ends (caps) or are internal) and the context (the influence of their neighbours). Glycine is greatly preferred at the N and C caps. At internal positions, Ala stabilizes the helix relative to Gly by 0.4 to 2 kcal mol-1. The variation results from a combination of burial of hydrophobic surface on folding and interference with hydrogen bonding of the protein with solvent. There is a good empirical correlation between the relative stabilizing effects of Ala and Gly with the total change in solvent-accessible hydrophobic surface area of the folded protein on mutation of Gly to Ala. It is not valid to assign to each amino acid a unique s-value that is generally applicable to all positions in all helices in all proteins.

Flavodoxins: sequence, folding, binding, function and beyond

Flavodoxins are electron-transfer proteins involved in a variety of photosynthetic and non-photosynthetic reactions in bacteria, whereas, in eukaryotes, a descendant of the flavodoxin gene helps build multidomain proteins. The redox activity of flavodoxin derives from its bound flavin mononucleotide cofactor (FMN), whose intrinsic properties are profoundly modified by the host apoprotein. This review covers the very exciting last decade of flavodoxin research, in which the folding pathway, the structure and stability of the apoprotein, the mechanism of FMN recognition, the interactions that stabilize the functional complex and tailor the redox potentials, and many details of the binding and electron transfer to partner proteins have been revealed. The next decade should witness an even deeper understanding of the flavodoxin molecule and a greater comprehension of its many physiological roles. The fact that flavodoxin is essential for the survival of some human pathogens could make it a drug target on its own.

Prognostic value of motor evoked potential obtained by transcranial magnetic brain stimulation in motor function recovery in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

The early prognostic application of transcranial magnetic brain stimulation (TMS) for assessing motor and functional recovery in ischemic stroke patients has yielded contradictory results. We performed a prospective study of patients with acute ischemic stroke and motor deficit to evaluate the early prognostic value of TMS in motor and functional recovery.

METHODS

Fifty patients with different degrees of hemiparesis were studied in the first week after ischemic stroke and evaluated by clinical scales (Medical Research Council Scale, Canadian Neurological Scale, Barthel Index), with clinical follow-up over 6 months. TMS (Magstim 200) was performed at the same time, recording the motor evoked potential (MEP) in the thenar eminence muscles, with facilitation by voluntary contraction.

RESULTS

Of the total group of 50 patients, MEP was absent in 20 and present in 30 (17 with normal and 13 with delayed central conduction time [CCT]). The patients with MEP showed better motor and functional recovery than those without. The MEP provided information on patient recovery, regardless of the initial strength and/or Barthel values. The degree of recovery was better in those patients with normal CCT than in those with delayed CCT.

CONCLUSIONS

MEP obtained by TMS in patients with hemiparesis after acute ischemic stroke is useful as an early prognostic indicator of motor and functional recovery. This technique would allow the early identification of those patients who will have a good recovery, particularly among those with severe initial paresis.

The role of the renin-angiotensin-aldosterone system in cardiovascular homeostasis in normal human subjects

To examine the role of angiotensin II in the maintenance of blood pressure and the control of aldosterone secretion in man, eight normal subjects were studied on a tilt table in sodium replete and sodium depleted states prior to and subsequent to the intravenous infusion of an angiotensin converting enzyme inhibitor (CEI). In both the sodium replete or sodium depleted state, upright tilting resulted in an increase in heart rate and a narrowing of pulse pressure. None of the sodium replete or depleted subjects fainted. Tilting was accompanied by a rise in plasma renin activity with an associated rise in plasma aldosterone concentration. When converting enzyme inhibitor was administered, which blocked the generation of angiotensin II, sodium replete subjects were able to compensate for an upright tilt, despite the absence of angiotensin II, without significant hemodynamic change when compared to control state. In sodium depleted subjects, after the administration of converting enzyme inhibitor, there was a sharp and significant decrease in systolic and diastolic blood pressure associated with a significant rise in heart rate. All but one sodium depleted subject fainted within seven minutes. Both plasma aldosterone concentration and plasma renin activity rose on tilting in both sodium replete and sodium depleted subjects. After the administration of converting enzyme inhibitor, plasma aldosterone failed to rise in association with a rise in plasma renin activity. In supine subjects, after the administration of converting enzyme inhibitor, plasma renin activity rose but plasma aldosterone concentration fell. In sodium depleted subjects, after the administration of CEI, aldosterone fell to a level significantly lower than that in supine controls and to a level no different from the supine sodium replete subject. These results indicate that angiotensin II is essential for blood pressure maintenance in sodium depleted individuals, that angiotensin II exerts a direct feedback control on renin secretion, and that angiotensin II is the primary stimulus to aldosterone secretion in response to both sodium depletion and to posture.

Serum interleukin-18 concentrations are increased in the polycystic ovary syndrome: relationship to insulin resistance and to obesity

Low-grade chronic inflammation is involved in the pathogenesis of the metabolic syndrome and atherosclerosis, and serum levels of inflammatory cytokines are useful cardiovascular risk markers. We have studied serum IL-18 concentrations in women with polycystic ovary syndrome (PCOS), focusing on its relationship with obesity and indexes of insulin resistance. Sixty consecutive women with PCOS and 34 healthy women were recruited. Serum levels of IL-18 and lipid and hormone profiles were measured. The insulin sensitivity index was calculated from glucose and insulin concentrations during an oral glucose tolerance test. Data were submitted to a multivariate general linear model introducing age as a covariate. Serum IL-18 levels were increased in PCOS patients compared with controls (P = 0.031) and in obese women compared with lean women (P = 0.018). No interaction between PCOS and obesity was found, suggesting that the influence of PCOS on serum IL-18 concentrations studied here was not different in lean women compared with obese women and that the influence of obesity on serum IL-18 concentrations was the same in the PCOS and control groups. Serum IL-18 levels correlated, after logarithmic transformation, with body mass index (r = 0.38; P < 0.0002), waist-to-hip ratio (r = 0.33; P < 0.001), and total testosterone levels (r = 0.24; P < 0.02), and inversely with the insulin sensitivity index (r = -0.23; P < 0.03). In conclusion, PCOS and obesity induce an increase in serum IL-18 levels, which are also associated with several indexes of global and visceral adiposity and with insulin resistance.

Abnormal T cell development in CD3-zeta-/- mutant mice and identification of a novel T cell population in the intestine

The T cell antigen receptor (TCR)-associated invariable membrane proteins (CD3-gamma, -delta, -epsilon and -zeta) are critical to the assembly and cell surface expression of the TCR/CD3 complex and to signal transduction upon engagement of TCR with antigen. Disruption of the CD3-zeta gene by homologous recombination resulted in a structurally abnormal thymus which primarily contained CD4- CD8- and TCR/CD3very lowCD4+CD8+ cells. Spleen and lymph nodes of CD3-zeta-/- mutant mice contained a normal number and ratio of CD4+ and CD8+ single positive cells that were TCR/CD3very low. These splenocytes did not respond to antibody cross-linking or mitogenic triggering. The V beta genes of CD4-CD8- and CD4+CD8+ thymocytes and splenic T cells were productively rearranged. These data demonstrated that (i) in the absence of the CD3-zeta chain, the CD4- CD8- thymocytes could differentiate to CD4+CD8+ TCR/CD3very low thymocytes, (ii) that thymic selection might have occurred, (iii) but that the transition to CD4+CD8- and CD4-CD8+ cells took place at a very low rate. Most strikingly, intraepithelial lymphocytes (IELs) isolated from the small intestine or the colon expressed normal levels of TCR/CD3 complexes on their surface which contained Fc epsilon RI gamma homodimers. In contrast to CD3-zeta containing IELs, these cells failed to proliferate after triggering with antibody cross-linking or mitogen. In comparison to thymus-derived peripheral T cells in the spleen and lymph nodes, the preferential expression of normal levels of TCR/CD3 in intestinal IELs suggested they mature via an independent extrathymic pathway.

Circular dichroism studies of barnase and its mutants: characterization of the contribution of aromatic side chains

The circular dichroism spectrum of barnase has been analyzed by examining the spectra of a series of mutants in which every single aromatic residue has been replaced. The spectrum of wild-type barnase is quite atypical for a protein of the alpha + beta class, with very low intensities and a minimum in the far-UV at 231 nm. The minimum at 231 nm is associated with the presence of Trp-94. Many other mutations involving aromatic residues have an effect on the spectral features in the far-UV. The major features in the near-UV spectra arise from essentially additive contributions of the three tryptophan residues Trp-35, Trp-71, and Trp-94. Tyrosine contributions are less prominent, with Tyr-78 and Tyr-97 contributing the most to the CD spectrum. The close charge-aromatic interaction between Trp-94 and His-18, which is important for the fluorescence properties of the protein, contributes little to the CD spectrum, as does the close aromatic-aromatic interaction between Tyr-13 and Tyr-17. However, the observed near-UV spectrum of wild-type barnase could not be simulated by the sum of the contributions of aromatic residues defined by difference spectra of protein variants carrying aromatic residues. Aromatic residues play an important role in determining the circular dichroism spectrum of proteins not only in the near-UV but also in the far-UV region.

Association of the polycystic ovary syndrome with genomic variants related to insulin resistance, type 2 diabetes mellitus, and obesity

We have evaluated the possible association of polycystic ovary syndrome (PCOS) with 15 genomic variants previously described to influence insulin resistance, obesity, and/or type 2 diabetes mellitus. Seventy-two PCOS patients and 42 healthy controls were genotyped for 15 variants in the genes encoding for paraoxonase (three variants), plasma cell differentiation antigen glycoprotein, human sorbin and SH3 domain containing 1, plasminogen activator inhibitor-1, peroxisome proliferator-activated receptor-gamma2, protein tyrosine phosphatase 1B (two variants), adiponectin (two variants), IGF1, IGF2, IGF1 receptor, and IGF2 receptor. Compared with controls, PCOS patients were more frequently homozygous for the -108T variant in paraoxonase (36.6% vs. 9.5%; P = 0.002) and homozygous for G alleles of the ApaI variant in IGF2 (62.9% vs. 38.1%; P = 0.018). Paraoxonase is a serum antioxidant enzyme and, because -108T alleles result in decreased paraoxonase expression, this increase in oxidative stress might result in insulin resistance. G alleles of the ApaI variant in IGF2 may increase IGF2 expression, and IGF2 stimulates adrenal and ovarian androgen secretion. In conclusion, the paraoxonase -108 C-->T variant and the ApaI polymorphism in the IGF2 gene are associated with PCOS and might contribute to increased oxidative stress, insulin resistance, and hyperandrogenism in this prevalent disorder.

Histidine residues at the N- and C-termini of alpha-helices: perturbed pKas and protein stability

A single histidine residue has been placed at either the N-terminus or the C-terminus of each of the two alpha-helices of barnase. The pKa of that histidine residue in each of the four mutants has been determined by 1H NMR. The pKas of the two residues at the C-terminus are, on average, 0.5 unit higher, and those of the residues at the N-terminus are 0.8 unit lower, than the pKa of histidines in unfolded barnase at low ionic strength. The conformational stability of the mutant proteins at different values of pH has been measured by urea denaturation. C-Terminal histidine mutants are approximately 0.6 kcal mol-1 more stable when the introduced histidine is protonated, both at low and high ionic strength. N-Terminal mutants with a protonated histidine residue are approximately 1.1 kcal mol-1 less stable at low ionic strength and 0.5 kcal mol-1 less stable at high ionic strength (1 M NaCl). The low-field 1H NMR spectra of the mutant proteins at low pH suggest that the C-terminal histidines form hydrogen bonds with the protein while the N-terminal histidines do not form the same. The perturbations of pKa and stability result from a combination of different electrostatic environments and hydrogen-bonding patterns at either ends of helices. The value of 0.6 kcal mol-1 represents a lower limit to the favorable electrostatic interaction between the alpha-helix dipole and a protonated histidine residue at the C-terminal end of the helix.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid hormone replacement therapy in primary hypothyroidism: a randomized trial comparing L-thyroxine plus liothyronine with L-thyroxine alone

BACKGROUND

Substituting part of the dose of l-thyroxine with small but supraphysiologic doses of liothyronine in hypothyroid patients has yielded conflicting results.

OBJECTIVE

To evaluate combinations of L-thyroxine plus liothyronine in hypothyroid patients that match the proportions present in normal secretions of the human thyroid gland.

DESIGN

Randomized, double-blind, crossover trial.

SETTING

Academic research hospital.

PARTICIPANTS

28 women with overt primary hypothyroidism.

INTERVENTION

Crossover trial comparing treatment with l-thyroxine, 100 microg/d (standard treatment), versus treatment with L-thyroxine, 75 microg/d, plus liothyronine, 5 microg/d (combination treatment), for 8-week periods. All patients also received L-thyroxine, 87.5 microg/d, plus liothyronine, 7.5 microg/d (add-on combination treatment), for a final 8-week add-on period.

MEASUREMENTS

Primary outcomes included serum thyroid hormone levels, results of quality-of-life and psychometric tests, and patients' preference. Multiple biological thyroid hormone end points were studied as secondary outcomes.

RESULTS

Compared with standard treatment, combination treatment led to lower free thyroxine levels (decrease, 3.9 pmol/L [95% CI, 2.5 to 5.3 pmol/L]), slightly higher serum levels of thyroid-stimulating hormone (increase, 0.62 mU/L [CI, 0.01 to 1.23 mU/L]), and unchanged free triiodothyronine levels. No improvement was observed in the other primary and secondary end points after combination treatment, with the exception of the Digit Span Test, in which the mean backward score and the mean total score increased slightly (0.6 digit [CI, 0.1 to 1.0 digit] and 0.8 digit [CI, 0.2 to 1.4 digits], respectively). The add-on combination treatment resulted in overreplacement. Levels of thyroid-stimulating hormone decreased by 0.85 mU/L (CI, 0.27 to 1.43 mU/L) and serum free triiodothyronine levels increased by 0.8 pmol/L (CI, 0.1 to 1.5 pmol/L) compared with standard treatment; 10 patients had levels of thyroid-stimulating hormone that were below the normal range. Twelve patients preferred combination treatment, 6 patients preferred the add-on combination treatment, 2 patients preferred standard treatment, and 6 patients had no preference (P = 0.015).

LIMITATIONS

Treatment with L-thyroxine, 87.5 microg/d, plus liothyronine, 7.5 microg/d, was an add-on regimen and was not randomized.

CONCLUSIONS

Physiologic combinations of L-thyroxine plus liothyronine do not offer any objective advantage over l-thyroxine alone, yet patients prefer combination treatment.

Fluorescence spectrum of barnase: contributions of three tryptophan residues and a histidine-related pH dependence

Fluorescence spectra of wild-type barnase and mutants in which tryptophan and histidine residues have been substituted have been analyzed to give the individual contributions of the three tryptophan residues. The spectrum is dominated by the contribution of Trp-35. The fluorescence intensity varies with pH according to an ionization of a pKa of 7.75. This pKa is close to that previously determined by NMR titration of the C2-H resonances of His-18 as a function of pH (Sali et al., 1989). This histidine residue is close to Trp-94. The pH dependence of the spectrum is abolished when either His-18 or Trp-94 is mutated, and so appears to be caused by the His-18/Trp-94 interaction. The spectral response of this interaction can serve as a probe of the folding pathway and of electrostatic effects within the protein. Changes in the fluorescence spectra on substitution of Trp-94 and His-18 suggest that there is net energy transfer from Trp-71 to Trp-94.

The tryptophan/histidine interaction in alpha-helices

Contacts between aromatic and charged residues are often found in proteins. Mutational studies have shown that a tryptophan/charged histidine pair can stabilise a protein by more than 1 kcal mol(-1). We have used circular dichroism and nuclear magnetic resonance to study the helical content of several peptides in which a tryptophan/histidine pair was placed at i, i + 3 or i, i + 4 in either the N to C or the C to N orientation. Our data indicate that the WH i, i + 4 geometry is the most stabilising one (when the histidine is protonated) and gives rise to the highest helical content. Little preference is observed among the three other orientations. The energy of the WH+ i, i + 4 interaction (calculated with AGADIR and SCINT) is about 1 kcal mol(-1). A statistical analysis of the occurrence of tryptophan/histidine pairs in alpha-helices of natural proteins reveals that, although the WH i, i + 4 pairs are not more abundant than the others, in most of the WH i, i + 4 pairs the two side-chains are in contact, but not in the other three orientations. These results suggest that the conformational stability of proteins could be increased by means of solvent-exposed intrahelical i, i + 4 tryptophan-histidine bridges and that these bridges could be useful to tailor the stability of helical peptides at physiological pH.

Obesity, and not insulin resistance, is the major determinant of serum inflammatory cardiovascular risk markers in pre-menopausal women

AIMS/HYPOTHESIS

Increased serum inflammatory markers have been found in obesity and insulin-resistant states, and could play a causative role in insulin resistance, atherosclerosis and cardiovascular disease. The polycystic ovary syndrome represents a human model of insulin resistance because both lean and obese polycystic ovary syndrome patients are insulin-resistant compared with non-hyperandrogenic women. We evaluated whether obesity, insulin resistance, or both, are related to the increased concentrations of inflammatory markers in pre-menopausal women.

METHODS

We compared 35 patients with polycystic ovary syndrome and 28 healthy women, paired for BMI, prevalence of obesity and smoking. Measurements included serum inflammatory markers, BMI, waist-to-hip ratio, blood pressure, serum glucose, insulin, lipid and hormone concentrations, and insulin sensitivity index.

RESULTS

The insulin sensitivity index was reduced in polycystic ovary syndrome patients compared with controls. However, no differences were observed between both groups in C-reactive protein, interleukin 6, tumour necrosis factor-alpha, soluble type 2 tumour necrosis factor receptor, and soluble intercellular cell adhesion molecule-1. When considering patients and controls as a whole, C-reactive protein and interleukin 6, were increased in obese subjects compared with lean women. Inverse correlations existed between insulin sensitivity index and C-reactive protein, interleukin 6, tumour necrosis factor-alpha, soluble type 2 tumour necrosis factor receptor, and soluble intercellular cell adhesion molecule-1. Only the weak correlation with C-reactive protein persisted after controlling for BMI.

CONCLUSION/INTERPRETATION

Obesity, and not insulin resistance, is the major determinant of serum inflammatory cardiovascular risk markers in pre-menopausal women.

Structure of the T-cell antigen receptor: evidence for two CD3 epsilon subunits in the T-cell receptor-CD3 complex

The T-cell antigen receptor (TCR) consists of heterodimeric glycoproteins (TCR alpha beta or gamma delta) that demonstrate homology with immunoglobulins. Noncovalently associated with the alpha beta (or gamma delta) heterodimer are at least five nonvariant proteins (CD3-gamma, -delta, -epsilon, -zeta, and -eta), which together comprise the TCR-CD3 complex. The stoichiometry of the antigen receptor has been assumed to be either alpha beta gamma delta epsilon zeta zeta or alpha beta gamma delta epsilon zeta eta. In this paper we provide several lines of evidence that support the notion that the mature TCR-CD3 complex on the cell surface contains two CD3-epsilon polypeptide chains. Transfection of two murine T cell-T cell hybridomas with the human DNA encoding CD3-epsilon protein demonstrated that both murine and human CD3-epsilon chains were present within the same TCR-CD3 complex. Analysis of thymocytes isolated from transgenic mice that expressed high copy numbers of the human CD3-epsilon gene showed that the heterologous human CD3-epsilon subunits were coexpressed with murine CD3-epsilon in the same TCR-CD3 complex. Since CD3-epsilon was shown to form disulfide-linked homodimers both in human and murine T cells, the two CD3-epsilon subunits present in the TCR-CD3 complex were in direct contact with one another. The presence of two CD3-epsilon polypeptide chains in close proximity to one another in the TCR-CD3 complex may have important implications for its assembly and its signal transduction mechanisms.

Quality of life and psychometric functionality in patients with differentiated thyroid carcinoma

We studied the psychological performance and the quality of life in patients with differentiated thyroid carcinoma, either during treatment with chronic suppressive doses of levothyroxine, or during the withdrawal of levothyroxine needed to perform whole-body scanning with radioactive iodine, with those of appropriate healthy controls. Eighteen women with differentiated thyroid carcinoma and 18 euthyroid age-matched healthy women were recruited. Patients were studied the day before levothyroxine withdrawal (when in chronic mild or subclinical hyperthyroidism), 4-7 days later (when most patients had normal serum free thyroxine and free triiodothyronine levels), and the day before scanning (when in profound hypothyroidism). Controls were studied at one time point. When compared with controls, patients presented with impairment of several indexes during chronic suppressive levothyroxine therapy (total score, emotional, sleep, energy and social of the Nottingham Health Profile; mental health, general health and social function of the SF-36, and total score on Wais Digit Span; P<0.05 for all comparisons). Also, quality of life indexes (19 of 21 scores), cognitive tests (6 of 12 scores), and affective and physical symptoms visual mental scales (18 of 19) worsened during profound hypothyroidism (P<0.05 for all comparisons). Quality of life and cognitive performance were almost comparable with those of euthyroid controls when most patients had normal free thyroxine and triiodothyronine levels. In conclusion, quality of life and psychometric functionality in patients with differentiated thyroid carcinoma is not only affected by withdrawal of levothyroxine but also by long-term treatment with supraphysiological doses of levothyroxine.

CD38 is functionally dependent on the TCR/CD3 complex in human T cells

One of the functions of surface CD38 is the induction of phosphorylation of discrete cytoplasmic substrates and mobilization of cytoplasmic calcium (Ca2+). The present work addresses the issue of whether the signaling mediated via CD38 operates through an independent pathway or, alternatively, is linked to the TCR/CD3 signaling machinery. We studied the signals elicited through CD38 by the specific agonistic IB4 monoclonal antibody (mAb) by monitoring the levels of cytoplasmic Ca2+ and the induced phenotypic and functional variations in T cell growth. IB4 mAb presented the unique ability to increase cytoplasmic Ca2+ levels, which correlated with the phosphorylation of the PLC-gamma1. These effects were blocked by phorbol 12-myristate 13-acetate (PMA) and were dependent on the presence of a functional TCR/CD3 surface complex, no effects being recorded on mutant Jurkat cells lacking part of the CD3 structures. CD38 signaling appeared to share with TCR/CD3 the ability to induce apoptotic cell death in Jurkat T cells, an event paralleled by specific up-regulation of the Fas molecule and inhibited by cyclosporin A. CD28, a costimulatory molecule, is synergized by increasing CD38-induced apoptotic cell death. The results indicate the existence of a strong functional interdependence between CD38 and TCR/CD3.

Differential stabilization of the three FMN redox forms by tyrosine 94 and tryptophan 57 in flavodoxin from Anabaena and its influence on the redox potentials

Flavodoxins are electron transfer proteins that carry a noncovalently bound flavin mononucleotide molecule as the redox-active center. The redox potentials of the flavin nucleotide are profoundly altered upon interaction with the protein. In Anabaena flavodoxin, as in many flavodoxins, the flavin is sandwiched between two aromatic residues (Trp57 and Tyr94) thought to be implicated in the alteration of the redox potentials. We have individually replaced these two residues by each of the other aromatic residues, by alanine and by leucine. For each mutant, we have determined the redox potentials and the binding energies of the oxidized FMN--apoflavodoxin complexes. From these data, the binding energies of the semireduced and reduced complexes have been calculated. Comparison of the binding energies of wild-type and mutant flavodoxins at the three redox states suggests that the interaction between Tyr94 and FMN stabilizes the apoflavodoxin--FMN complex in all redox states. The oxidized and semireduced complexes are, however, more strongly stabilized than the reduced complex, making the semiquinone/hydroquinone midpoint potential more negative in flavodoxin than in unbound FMN. Trp57 also stabilizes all redox forms of FMN, thus cooperating with Tyr94 in strong FMN binding. On the other hand, Trp57 seems to slightly destabilize the semireduced complex relative to the oxidized one. Finally, we have observed that reduction of mutants lacking Trp57 is slow relative to that of wild-type or mutants lacking Tyr94, which suggests that Trp57 could play a role in the kinetics of flavodoxin redox reactions.