Peroxisome proliferator-activated receptors: new players in the field of reproduction

Peroxisome proliferator-activated receptors (PPAR) are members of the nuclear hormone receptor superfamily. Synthetic ligands to one family member, PPARgamma, are currently widely used as treatment for chronic diseases such as diabetes type II and other insulin resistances, e.g. as seen in polycystic ovary syndrome (PCOS). Moreover, novel approaches employing knock-out mice demonstrated that PPARgamma seems to play a key role in placental and fetal development. This review describes recent insights into the role of PPARs in human reproduction with specific reference to infertility, placental maturation and fetal development as well as disturbed pregnancy. Further, we highlight the current knowledge on synthetic ligands to PPARgamma used as a treatment in women with PCOS.     

Conversion of cucumber linoleate 13-lipoxygenase to a 9-lipoxygenating species by site-directed mutagenesis

Multiple lipoxygenase sequence alignments and structural modeling of the enzyme/substrate interaction of the cucumber lipid body lipoxygenase suggested histidine 608 as the primary determinant of positional specificity. Replacement of this amino acid by a less-space-filling valine altered the positional specificity of this linoleate 13-lipoxygenase in favor of 9-lipoxygenation. These alterations may be explained by the fact that H608V mutation may demask the positively charged guanidino group of R758, which, in turn, may force an inverse head-to-tail orientation of the fatty acid substrate. The R758L+H608V double mutant exhibited a strongly reduced reaction rate and a random positional specificity. Trilinolein, which lacks free carboxylic groups, was oxygenated to the corresponding (13S)-hydro(pero)xy derivatives by both the wild-type enzyme and the linoleate 9-lipoxygenating H608V mutant. These data indicate the complete conversion of a linoleate 13-lipoxygenase to a 9-lipoxygenating species by a single point mutation. It is hypothesized that H608V exchange may alter the orientation of the substrate at the active site and/or its steric configuration in such a way that a stereospecific dioxygen insertion at C-9 may exclusively take place.     

Electrocardiographic evidence of myocardial salvage after thrombolysis in acute myocardial infarction.

There is a need for a simple clinical measurement that will indicate the extent of myocardial salvage after successful thrombolysis. This study examined whether coronary artery reperfusion reduced the infarct size as assessed electrocardiographically after thrombolytic treatment. The sum of the (sigma) ST segment area in leads showing ST segment elevation in the 12 lead electrocardiogram at presentation was used as an index of potential myocardial injury (initial ischaemic index). The evolved infarct size at 48 h was assessed by a QRS scoring system. Two groups of patients, both admitted with anterior myocardial infarction within 6 h of onset, were studied. Group 1 (n = 35) received analgesia only and group 2 (n = 33) received thrombolytic treatment either by the intracoronary (streptokinase, n = 13) or intravenous route (anistreplase, n = 20). Reperfusion was assessed angiographically. The mean (SD) potential infarct size assessed by the initial ischaemic index was similar in both groups (group 1, sigma ST area = 115 (60) mm2 and group 2 = 126 (77 mm2). The QRS score representing evolved infarct size was significantly lower in the treated group (4.1 (2.5] than in group 1 (7.8 (2.6]. The 95% confidence intervals for QRS scores based on the admission sigma ST area from patients with successful reperfusion were applied to a third set of patients (n = 22) to test the ability of the admission ST area (myocardial injury) to predict the QRS score accurately. While patients with successful reperfusion had significantly lower QRS scores than those who did not (4.5 (3.1) versus 9.3 (3.4)), the wide confidence intervals caused by inter-individual variability precluded an accurate prediction of the QRS score in an individual from the sigma ST area at time of presentation. There was no difference in infarct size in patients treated early (</= 3 h) (QRS score 4.2(2.8)) or later (3-6 h) (4.1(2.1)). This study provides evidence that sequential electrocardiographic changes are reduced in patients with anterior infarction who achieve reperfusion after thrombolytic treatment and that this benefit is shown with treatment given up to six hours after infarct onset. None the less, the relation between the initial ischaemic index and the evolved QRS score has wide confidence intervals, reflecting inter-individual variability, and does not allow the prediction of a QRS score in an individual patient.     

Patients with rheumatoid arthritis treated with methotrexate (MTX): concentrations of steady-state erythrocyte MTX correlate to plasma concentrations and clinical efficacy

To investigate the accumulation of methotrexate (MTX) in circulating erythrocytes and the association with pharmacokinetic variables, weekly dose, and clinical efficacy in 2 cohorts of patients with chronic active rheumatoid arthritis (RA) undergoing MTX monotherapy. METHODS: Seventy-six patients with RA were included in this open prospective study: 40 were included before initiation of MTX therapy. Laboratory analyses, intracellular MTX concentrations in erythrocytes (Ery-MTX), and clinical examinations including toxicity data were performed prospectively for 52 weeks. Plasma concentrations of MTX were measured and area under the plasma concentration versus time curve (AUC) was estimated along with other pharmacokinetic variables in a population based software model.RESULTS: Ery-MTX rose after initiation of therapy and reached a steady state after 6-8 weeks. The correlation between steady-state Ery-MTX and dose was poor (r(2) = 0.16), whereas steady-state Ery-MTX levels correlated strongly with the estimated AUC (r(2) = 0.51, log-transformed variables). Both steady-state Ery-MTX levels and estimated AUC were significantly higher in patients responding to MTX therapy than in patients classified as nonresponders according to American College of Rheumatology core criteria and were similar to patients on longterm MTX therapy. CONCLUSION: Our results indicate that clinical efficacy and Ery-MTX may have a causal relation and that measurement of Ery-MTX or estimation of AUC in a software model provides useful guidelines to the clinician when starting MTX therapy in patients with RA. The latter can be performed immediately after initiation of therapy.     

Submaximal invasive exercise testing and quantitative lung scanning in the evaluation for tolerance of lung resection

Lung resection in patients with cardiopulmonary dysfunction is associated with increased risk. We studied 52 elderly male patients with airflow obstruction and a lung mass. Studies were performed at rest with routine ventilatory tests and lung scan quantitation of right-left lung function. Cycle ergometry exercise was then performed at 2 submaximal work loads (25 and 40 watts). Data were obtained using systemic and pulmonary artery catheterization for blood pressures, thermal dilution cardiac output, and blood gases. Twenty-nine patients underwent lung resection and seven failed to tolerate the procedure (death within 60 days or prolonged ventilator dependence). Those parameters most clearly separating the group tolerating surgery (n = 22) from the intolerant group (n = 7) were obtained during exercise and included: cardiac index (tolerant 5.5 +/- 1.3 vs intolerant 3.9 +/- 0.3 L/min/m2, p less than .01), O2 delivery (p less than .01) and calculated VO2 ml/kg/min (tolerant 11.3 +/- 2.1 vs intolerant 7.8 +/- 1.5 ml/kg/min, p less than .001). Pulmonary vascular pressures and calculated resistance did not predict intolerance. Calculated VO2 at 40 watts did not separate those patients who had survivable complications from those who did not (p much greater than .05). Multivariate analysis suggests that exercise VO2 is an important predictor of tolerance of lung resection because it reflects the effects of cardiac function and O2 transport. In our patients with COPD, submaximal exercise testing predicted intolerance of lung resection better than calculation using quantitative lung scanning. Exercise testing may accomplish this goal by uncovering deficits in O2 transport.     

Electrocardiographic prediction of coronary artery patency after thrombolytic treatment in acute myocardial infarction: use of the ST segment as a non-invasive marker

The predictive value of the measurement of changes in ST segment elevation was assessed as a non-invasive marker of coronary artery reperfusion after thrombolytic treatment. Forty five patients with acute myocardial infarction (23 anterior, 22 inferior) of less than six hours' duration were given thrombolytic treatment by either the intravenous (n = 28) or the intracoronary route (n = 17). A proportional value for the shift in ST segment, termed the fractional change, was calculated both from 12 lead electrocardiograms and from the Holter tape for each patient. Coronary artery patency in an initial group of 22 patients (training group) was associated with a fractional change value of greater than or equal to 0.5 (100% specific, 88% sensitive by Holter analysis; 100% specific, 94% sensitive by 12 lead electrocardiogram). This rule performed well when it was applied to a test group of 17 patients (100% specific, 93% sensitive by Holter analysis; and 67% specific, 93% sensitive by 12 lead electrocardiogram). Linear discriminant analysis was then used to determine which features gave the best separation of those in whom there was reperfusion and those in whom there was not. This gave 100% specificity and 100% sensitivity when applied to the training group for either the 12 lead electrocardiogram or Holter monitoring. When it was applied to the test group, the sensitivity was maintained at 100%, but the specificity dropped to 33% irrespective of whether the basis of the test was Holter monitoring or the 12 lead electrocardiogram. These results suggest that a fractional change of >/= 0.5 calculated from a single lead showing myocardial injury is a useful non-invasive marker of reperfusion. The technique can be applied to either 12 lead electrocardiograms or Holter monitoring. The use of a more complex classification increased the sensitivity of the test at the expense of its specificity.     

A duplicated copy of DMRT1 in the sex-determining region of the Y chromosome of the medaka,Oryzias latipes

The genes that determine the development of the male or female sex are known in Caenorhabditis elegans, Drosophila, and most mammals. In many other organisms the existence of sex-determining factors has been shown by genetic evidence but the genes are unknown. We have found that in the fish medaka the Y chromosome-specific region spans only about 280 kb. It contains a duplicated copy of the autosomal DMRT1 gene, named DMRT1Y. This is the only functional gene in this chromosome segment and maps precisely to the male sex-determining locus. The gene is expressed during male embryonic and larval development and in the Sertoli cells of the adult testes. These features make DMRT1Y a candidate for the medaka male sex-determining gene.