Decreased expression of β(1)- and β(2)-adrenoceptors in human diabetic atrial appendage

BACKGROUND: Using the streptozotocin-induced diabetic rat model, we have recently showed that the expression and function of β(1)-adrenoreceptor were decreased in the diabetic rat heart. However, the effect of diabetes on expression of β-adrenoreceptors in human cardiac tissue remains undefined. Therefore, the focus of the present study was to investigate the effect of diabetes on mRNA encoding β(1)- and β(2)-ARs in human atrial tissues. METHODS: Right atrial appendages from five diabetic (mean age 65 ± 4.5; 4 female, 1 male) and five nondiabetic patients (mean age 56.2 ± 2.8; 4 male, 1 female) undergoing coronary artery bypass grafting were collected and assayed using reverse transcriptase-polymerase chain reaction (RT-PCR) for their mRNA content. No patient from these two groups suffered from acute myocardial infarction and/or failure. All diabetic patients received insulin for at least two years and had been diagnosed as diabetics for at least five years. RESULTS: When compared with levels in nondiabetics, steady state levels of mRNA encoding β(1)-adrenoreceptor decreased by 69.2 ± 7.6 % in diabetic patients while β(2)-adrenoreceptor mRNA decreased by 32.2 ± 5.5 % (p < 0.001). CONCLUSIONS: Our findings show a decreased expression of β(1)- and β(2)-adrenoreceptors in human diabetic atrial appendage

Controlled mobility in stochastic and dynamic wireless networks

We consider the use of controlled mobility in wireless networks where messages arriving randomly in time and space are collected by mobile receivers (collectors). The collectors are responsible for receiving these messages via wireless transmission by dynamically adjusting their position in the network. Our goal is to utilize a combination of wireless transmission and controlled mobility to improve the throughput and delay performance in such networks. First, we consider a system with a single collector. We show that the necessary and sufficient stability condition for such a system is given by ρ<1 where ρ is the expected system load. We derive lower bounds for the expected message waiting time in the system and develop policies that are stable for all loads ρ<1 and have asymptotically optimal delay scaling. We show that the combination of mobility and wireless transmission results in a delay scaling of Θ([1 over 1−ρ]) with the system load ρ, in contrast to the Θ([1 over (1−ρ)[superscript 2]]) delay scaling in the corresponding system without wireless transmission, where the collector visits each message location. Next, we consider the system with multiple collectors. In the case where simultaneous transmissions to different collectors do not interfere with each other, we show that both the stability condition and the delay scaling extend from the single collector case. In the case where simultaneous transmissions to different collectors interfere with each other, we characterize the stability region of the system and show that a frame-based version of the well-known Max-Weight policy stabilizes the system asymptotically in the frame length.National Science Foundation (U.S.) (Grant CNS-0915988)United States. Army Research Office. Multidisciplinary University Research Initiative (Grant W911NF-08-1-0238

Tandem synthesis of alternating polyesters from renewable resources

The vast majority of commodity materials are obtained from petrochemical feedstocks. These resources will plausibly be depleted within the next 100 years, and the peak in global oil production is estimated to occur within the next few decades. In this regard, biomass represents an abundant carbon-neutral renewable resource for the production of polymers. Here we report a new strategy, based on tandem catalysis, to obtain renewable materials. Commercially available complexes are found to be efficient catalysts for alternating polyesters from the cyclization of dicarboxylic acids followed by alternating copolymerization of the resulting anhydrides with epoxides. This operationally simple method is an attractive strategy for the production of new biodegradable polyesters

Predicting Academic Performance: A Systematic Literature Review

The ability to predict student performance in a course or program creates opportunities to improve educational outcomes. With effective performance prediction approaches, instructors can allocate resources and instruction more accurately. Research in this area seeks to identify features that can be used to make predictions, to identify algorithms that can improve predictions, and to quantify aspects of student performance. Moreover, research in predicting student performance seeks to determine interrelated features and to identify the underlying reasons why certain features work better than others. This working group report presents a systematic literature review of work in the area of predicting student performance. Our analysis shows a clearly increasing amount of research in this area, as well as an increasing variety of techniques used. At the same time, the review uncovered a number of issues with research quality that drives a need for the community to provide more detailed reporting of methods and results and to increase efforts to validate and replicate work.Peer reviewe

The bc 1 complexes of Rhodobacter sphaeroides and Rhodobacter capsulatus

Photosynthetic bacteria offer excellent experimental opportunities to explore both the structure and function of the ubiquinol-cytochrome c oxidoreductase ( bc 1 complex). In both Rhodobacter sphaeroides and Rhodobacter capsulatus , the bc 1 complex functions in both the aerobic respiratory chain and as an essential component of the photosynthetic electron transport chain. Because the bc 1 complex in these organisms can be functionally coupled to the photosynthetic reaction center, flash photolysis can be used to study electron flow through the enzyme and to examine the effects of various amino acid substitutions. During the past several years, numerous mutations have been generated in the cytochrome b subunit, in the Rieske iron-sulfur subunit, and in the cytochrome c 1 subunit. Both site-directed and random mutagenesis procedures have been utilized. Studies of these mutations have identified amino acid residues that are metal ligands, as well as those residues that are at or near either the quinol oxidase (Q o ) site or the quinol reductase (Q i ) site. The postulate that these two Q-sites are located on opposite sides of the membrane is supported by these studies. Current research is directed at exploring the details of the catalytic mechanism, the nature of the subunit interactions, and the assembly of this enzyme.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44795/1/10863_2004_Article_BF00762582.pd

Quadruple test parameters in art pregnancies

İstanbul Bilim Üniversitesi, Tıp Fakültesi.Aim: Quadruple test is used for Down's syndrome screening in the second trimester of pregnancy. The aim of this study was to investigate differences in quadruple test parameters between pregnancies achieved by assisted reproductive treatments (ART) and spontaneous conception. Materials and methods: We retrospectively compared levels of alfa-fetoprotein (AFP), unconjugated Estriol (uE3), inhibin-A and hCG and also screen positive test results. Results: Levels of all quadruple test parameters were statistically significantly increased in ART pregnancies when compared to spontaneous pregnancies, AFP was 1.4 +/- 0.74 and 1.16 +/- 0.53, (p = 0.001), uE3 was 1.10 +/- 0.37 and 1.00 +/- 0.28, (p = 0.004), hCG was 1.56 +/- 1.04 and 1.26 +/- 0.76, (p = 0.001), inhibin A was 1.38 +/- 0.76 and 1.08 +/- 0.57, (p = 0.001), screen positive tests were nearly doubled (4.8% and 8.4%). Conclusions: Increased screen positive test results and quadruple test parameters in ART pregnancies may lead to unnecessary amniocentesis

Childhood malignant meningioma

Childhood meningiomas, besides their rarity, grow fast, recur frequently and have a dismal prognosis when compared with adult tumors. A five year old patient presenting with headache, emesis and left hemiparesia was admitted to our hospital in 1990. On computerized tomography a 85x80x87 mm mass in the right frontoparietal region surrounded by significant edema, having a wide base on the falx causing 2 cm shift to left was found. The patient was operated on in our clinic with a diagnosis of multilobuled giant intracranial meningioma. The tumor showing frequent recurrence and sarcomatous changes is presented and discussed. Although the CT findings in this case suggest malignancy the behavior of the meningiomas is usually determined by histologic nature. In cases where frequent recurrence is seen the period between recurrences diminishes in time. Therefore CT controls are important in diagnosing recurrence. Total excision in early stage may increase the chance of survival

Brucellosis imitating discal hernia

Three hundred patients with low back pain who presented at the Neurosurgery Department of Dokuz Eylul University Hospital between April 1991-September 1992 and sera analyzed for brucella agglutination. Brucella agglutination tests were positive in eight patients. They showed discal hernia symptoms and their lumbar CTs showed herniated discs. One of these patients was operated on and the others were treated conservatively. After the conservative treatment, clinical and radiological findings were resolved completely in all patients