DNA intercalation without flipping in the specific ThaI–DNA complex

The PD-(D/E)XK type II restriction endonuclease ThaI cuts the target sequence CG/CG with blunt ends. Here, we report the 1.3 Å resolution structure of the enzyme in complex with substrate DNA and a sodium or calcium ion taking the place of a catalytic magnesium ion. The structure identifies Glu54, Asp82 and Lys93 as the active site residues. This agrees with earlier bioinformatic predictions and implies that the PD and (D/E)XK motifs in the sequence are incidental. DNA recognition is very unusual: the two Met47 residues of the ThaI dimer intercalate symmetrically into the CG steps of the target sequence. They approach the DNA from the minor groove side and penetrate the base stack entirely. The DNA accommodates the intercalating residues without nucleotide flipping by a doubling of the CG step rise to twice its usual value, which is accompanied by drastic unwinding. Displacement of the Met47 side chains from the base pair midlines toward the downstream CG steps leads to large and compensating tilts of the first and second CG steps. DNA intercalation by ThaI is unlike intercalation by HincII, HinP1I or proteins that bend or repair DNA.     

Influence of phase I duration on phase II VO2 kinetics parameter estimates in older and young adults

Older adults (O) may have a longer phase I pulmonary O(2) uptake kinetics (Vo(2)(p)) than young adults (Y); this may affect parameter estimates of phase II Vo(2)(p). Therefore, we sought to: 1) experimentally estimate the duration of phase I Vo(2)(p) (EE phase I) in O and Y subjects during moderate-intensity exercise transitions; 2) examine the effects of selected phase I durations (i.e., different start times for modeling phase II) on parameter estimates of the phase II Vo(2)(p) response; and 3) thereby determine whether slower phase II kinetics in O subjects represent a physiological difference or a by-product of fitting strategy. Vo(2)(p) was measured breath-by-breath in 19 O (68 ± 6 yr; mean ± SD) and 19 Y (24 ± 5 yr) using a volume turbine and mass spectrometer. Phase I Vo(2)(p) was longer in O (31 ± 4 s) than Y (20 ± 7 s) (P < 0.05). In O, phase II τVo(2)(p) was larger (P < 0.05) when fitting started at 15 s (49 ± 12 s) compared with fits starting at the individual EE phase I (43 ± 12 s), 25 s (42 ± 10 s), 35 s (42 ± 12 s), and 45 s (45 ± 15 s). In Y, τVo(2)(p) was not affected by the time at which phase II Vo(2)(p) fitting started (τVo(2)(p) = 31 ± 7 s, 29 ± 9 s, 30 ± 10 s, 32 ± 11 s, and 30 ± 8 s for fittings starting at 15 s, 25 s, 35 s, 45 s, and EE phase I, respectively). Fitting from EE phase I, 25 s, or 35 s resulted in the smallest CI τVo(2)(p) in both O and Y. Thus, fitting phase II Vo(2)(p) from (but not constrained to) 25 s or 35 s provides consistent estimates of Vo(2)(p) kinetics parameters in Y and O, despite the longer phase I Vo(2)(p) in O.     

Management of thyroid diseases during pregnancy

The management of thyroid disorders during pregnancy is one of the most frequently disputed problems in modern endocrinology. It is widely known that thyroid dysfunction may result in subfertility, and, if inadequately treated during pregnancy, may cause obstetrical complications and influence fetal development. The 2007 Endocrine Society Practice Guideline endorsed with the participation of the Latino America Thyroid Association, the American Thyroid Association, the Asia and Oceania Thyroid Association and the European Thyroid Association, greatly contributed towards uniformity of the management of thyroid disorders during pregnancy and postpartum. Despite the tremendous progress in knowledge on the mutual influence of pregnancy and thyroid in health and disease, there are still important areas of uncertainty. There have been at least a few important studies published in the last 3 years, which influenced the thyroidal care of the expecting mother. It should also be remembered that guidelines may not always be universally applied in all populations with different ethnical, socio-economical, nutritional (including iodine intake) background or exposed to different iodine prophylaxis models. The Task Force for development of guidelines for thyroid dysfunction management in pregnant women was established in 2008. The expert group has recognized the following tasks: development of the coherent model of the management of thyroid dysfunction in pregnant women, identification of the group of women at risk of thyroid dysfunction, who may require endocrine care in the preconception period, during pregnancy and postpartum - that is in other words, the development of Polish recommendations for targeted thyroid disorder case finding during pregnancy, and the development of Polish trimester-specific reference values of thyroid hormones. Comprehensive Polish guidelines developed by the Task Force are to systematize the management of the thyroid disorders in pregnant women in Poland.     

A case of Cushing's syndrome in pregnancy

Cushing's syndrome (also known as hypercortisolemia) is rare in pregnant women due to the menstrual disturbances and infertility in women with hypercortisolism. A diagnosis of pathological hypercortisolism in pregnant women is often difficult as some symptoms of the disease may be associated with a complicated pregnancy. Hypercortisolemia leads to serious complications for mother and foetus, and is associated with premature labour and high foetal mortality. Hormonal and radiological diagnostics in pregnancy are limited. The results of hormonal measurements and dynamic tests are difficult to interpret due to the physiological changes in the hypothalamo-pituitaryadrenal axis connected with pregnancy. The optimal time and method of treatment should be chosen cautiously case by case because of the possibility of maternal and foetal complications. In this paper, we present a case of Cushing's syndrome secondary to adrenal adenoma in which the diagnosis was made in the 22(nd) week of pregnancy. Due to the advanced gestational status and mild symptoms of hypercortisolism, only symptomatic treatment was introduced. The patient was under continuous obstetric and endocrinological care. At 35 weeks of gestation, the pregnancy was terminated by emergency caesarean section because of premature detachment of the placenta. A male infant weighing 2,450 g was delivered; neither adrenal insufficiency in the child nor hypercortisolemia complications in the mother were observed.     

Structure and binding specificity of the receiver domain of sensor histidine kinase CKI1 from Arabidopsis thaliana

Multistep phosphorelay (MSP) signaling mediates responses to a variety of important stimuli in plants. In Arabidopsis MSP, the signal is transferred from sensor histidine kinase (HK) via histidine phosphotransfer proteins (AHP1–AHP5) to nuclear response regulators. In contrast to ancestral two‐component signaling in bacteria, protein interactions in plant MSP are supposed to be rather nonspecific. Here, we show that the C‐terminal receiver domain of HK CKI1 (CKI1_RD) is responsible for the recognition of CKI1 downstream signaling partners, and specifically interacts with AHP2, AHP3 and AHP5 with different affinities. We studied the effects of Mg²⁺, the co‐factor necessary for signal transduction via MSP, and phosphorylation‐mimicking BeF₃^? on CKI1_RD in solution, and determined the crystal structure of free CKI1_RD and CKI1_RD in a complex with Mg²⁺. We found that the structure of CKI1_RD shares similarities with the only known structure of plant HK, ETR1_RD, with the main differences being in loop L3. Magnesium binding induces the rearrangement of some residues around the active site of CKI1_RD, as was determined by both X‐ray crystallography and NMR spectroscopy. Collectively, these results provide initial insights into the nature of molecular mechanisms determining the specificity of MSP signaling and MSP catalysis in plants.     

Biventricular pacing in the early postoperative period after cardiac surgery

Cardiac resynchronization therapy is not commonly used in the early postoperative period in patients undergoing cardiac surgery who have left ventricular (LV) dysfunction and a history of heart failure. We performed a prospective randomized clinical trial to compare atrial synchronous right ventricular (DDD RV) and biventricular (DDD BIV) pacing within 72 hours after cardiac surgery in patients with an EF ≤35 %, a QRS interval longer than 120 msec and who had LV dyssynchrony detected by real-time three-dimensional echocardiography (RT3DE). Epicardial pacing was provided by a modified Medtronic INSYNC III pacemaker. An LV epicardial pacing lead was implanted on the latest activated segment of the LV based on RT3DE. The study included 18 patients with ischemic heart disease, with or without valvular heart disease (14 men, 4 women, average age 71 years). Patients undergoing DDD BIV pacing had a statistically significant greater CO and CI (CO 6.7±1.8 l/min, CI 3.4±0.7 l/min/m(2)) than patients undergoing DDD RV pacing (CO 5.5±1.4 l/min, CI 2.8±0.7 l/min/m(2)), p<0.001. DDD BIV pacing in the early postoperative period after cardiac surgery corrects LV dyssynchrony and has better hemodynamic results than DDD RV pacing.