Chlamydia trachomatis Infection of Endocervical Epithelial Cells Enhances Early HIV Transmission Events

Chlamydia trachomatis causes a predominantly asymptomatic, but generally inflammatory, genital infection that is associated with an increased risk for HIV acquisition. Endocervical epithelial cells provide the major niche for this obligate intracellular bacterium in women, and the endocervix is also a tissue in which HIV transmission can occur. The mechanism by which CT infection enhances HIV susceptibility at this site, however, is not well understood. Utilizing the A2EN immortalized endocervical epithelial cell line grown on cell culture inserts, we evaluated the direct role that CT-infected epithelial cells play in facilitating HIV transmission events. We determined that CT infection significantly enhanced the apical-to-basolateral migration of cell-associated, but not cell-free, HIV_BaL, a CCR5-tropic strain of virus, across the endocervical epithelial barrier. We also established that basolateral supernatants from CT-infected A2EN cells significantly enhanced HIV replication in peripheral mononuclear cells and a CCR5+ T cell line. These results suggest that CT infection of endocervical epithelial cells could facilitate both HIV crossing the mucosal barrier and subsequent infection or replication in underlying target cells. Our studies provide a mechanism by which this common STI could potentially promote the establishment of founder virus populations and the maintenance of local HIV reservoirs in the endocervix. Development of an HIV/STI co-infection model also provides a tool to further explore the role of other sexually transmitted infections in enhancing HIV acquisition.     

Evolution,pollination, and systematics of the tribeNeottieae (Orchidaceae)

The various classifications of the orchid tribeNeottieae are reviewed and a new classification is proposed that divides the tribe into three subtribes,Neottiinae, Limodorinae, andCephalantherinae, based primarily on characters of the column (gynostemium). A cladistic analysis illustrates that these three subtribes are more closely related to one another than either is to any other group in subfam.Neottioideae, although there are very few apomorphic characters for the tribe. Pollination biology is also discussed showing links between breeding systems and distribution. There is also a possible role between column and labellum morphology and the emergence of a deceptive pollination syndrome from one of reward.     

In vitro interaction of mutagenic chromium (VI) with red blood cells

The interaction of mutagenic Cr(VI) with red blood cells has been studied by ESR spectroscopy. Signals of two Cr(V) species are observed almost immediately after contacting red cells with chromate(VI) aqueous solution at pH 7.4. The signal at go = 1.985, which decays within one hour, is attributed to a Cr(V) complex formed by glutathione due its reducing and chelating ability. The other signal at go = 1.979, which is distinctly more persistent, may indicate that some immobilization of the formed Cr(V) ions takes place on the macromolecular cell components, e.g. glycoproteins.     

Exercise hyperthermia as a factor limiting physical performance: temperature effect on muscle metabolism

The muscle contents of high-energy phosphates and their derivatives [ATP, ADP, AMP, creatine phosphate (CrP), and creatine], glycogen, some glycolytic intermediates, pyruvate, and lactate were compared in 11 dogs performing prolonged heavy exercise until exhaustion (at ambient temperature 20.0 +/- 1.0 degrees C) without and with trunk cooling using ice packs. Without cooling, dogs were able to run for 57 +/- 8 min, and their rectal (Tre) and muscle (Tm) temperatures increased to 41.8 +/- 0.2 and 43.0 +/- 0.2 degrees C, respectively. Compared with noncooling, duration of exercise with cooling was longer by approximately 45% while Tre and Tm at the time corresponding to the end of exercise without cooling were lower by 1.1 +/- 0.2 and 1.2 +/- 0.2 degrees C, respectively. The muscle contents of high-energy phosphates (ATP + CrP) decreased less, the rate of glycogen depletion was lower, and the increases in the contents of AMP, pyruvate, and lactate as well as in the muscle-to-blood lactate ratio were smaller. The muscle content of lactate was positively correlated with Tm. The data indicate that with higher body temperature equilibrium between high-energy phosphate breakdown and resynthesis was shifted to the lower values of ATP and CrP and glycolysis was accelerated. The results suggest that hyperthermia developing during prolonged muscular work exerts an adverse effect on muscle metabolism that may be relevant to limitation of endurance.     

Salt-dependent conformational transitions in the self-complementary deoxydodecanucleotide d(CGCAATTCGCG): Evidence for hairpin formation

Differential scanning calorimetry (DSC), temperature-dependent uv-absorption spectroscopy, and temperature-dependent CD were used to monitor and characterize the salt-dependent, thermally induced structural transitions in the deoxydodecanucleotide d(CGCGAATTCGCG). At the high oligomer concentrations required for DSC, the calorimetric scans revealed a single, monophasic transition curve at all salt concentrations. Based on previous nmr melting studies under similar conditions, we conclude that these monophasic transitions correspond to the cooperative duplex-to-single-strand conversion of the dodecamer. By contrast, at the lower oligomer concentrations used for the spectroscopic studies, the shapes of the uv and CD melting curves were found to depend on the concentration of the added salt. At high salt (≥0.1M Na⁺), a single, monophasic transition curve was observed. At lower salt (?0.01M Na⁺), the CD and uv melting curves exhibit biphasic behavior. Based on the concentration dependence, the enthalpy, and the cooperativity of each transition in the biphasic curve, we conclude that at low salt and low oligomer concentrations, the dodecamer melts in a sequential manner involving initial disruption of a duplex structure and subsequent disruption of a hairpin structure.     

Ultrastructural analysis of the human cerebral ventricular system

Summary The ultrastructural organization of the human fetal choroid plexus was assessed with scanning electron microscopy. The membranous modifications of choroidal ependymal cells differ remarkably between 11 and 20 weeks of intrauterine development and suggest a variable functional capacity at different times of ontogenesis. Based upon existing data coupled with the ultra-architectural organization of cilia, clavate and linear microvilli are seen with scanning electron microscopy, a multiple functional role is hypothesized for choroidal ependymal cells.supported by USPH grant NS 08171.career development awardee K04 GM 70001     

Effects of Phenylmercuric Acetate on Stomatal Movement and Transpiration of Excised Retula papyrifera Marsh. Leaves

Effects of 10⁻³m, 10⁻⁴m, and 10⁻⁵m phenylmercuric acetate (PMA) on stomatal movement and transpiration of excised Betula papyrifera leaves were investigated. Duco cement leaf prints and transpiration decline curves were used for the analysis of stomatal condition. PMA induced stomatal closure and decreased transpiration. Stomata of leaves treated with any of the 3 PMA concentrations closed earlier and at a higher relative water content than did stomata of untreated leaves. As determined from transpiration decline curves, PMA at 10⁻³m caused an increase in apparent “cuticular” transpiration. However, the increase appeared to result largely from some PMA-poisoned stomata which remained open for prolonged periods. Considerable PMA toxicity was observed, with 10⁻³m and 10⁻⁴m concentrations causing browning of leaves. PMA treatment caused a decrease in chlorophyll content, even at a low PMA concentration (10⁻⁵m) which influenced stomatal response only slightly and did not cause evident browning of leaves. The time and degree of stomatal opening varied with stomatal size. Large stomata tended to open earlier and close later than small stomata. Hence, in Betula papyrifera stomata of various size classes were considered as physiologically different populations.     

THE ROLE OF RESERVES IN LEAVES,BRANCHES, STEMS,AND ROOTS ON SHOOT GROWTH OF RED PINE

By defoliation, girdling, and various combinations of these before the growing season began, the role of foods in old needles, branches, main stems, and roots on shoot growth of 8-yr-old red pine (Pinus resinosa) trees was studied in northern Wisconsin. Defoliation and girdling, alone or in combination, reduced shoot growth but defoliation reduced shoot dry weight more than it reduced shoot elongation. Reductions in shoot growth due to treatment were in the following decreasing order: branch girdling + needle removal > girdling at stem base + needle removal > needle removal > branch girdling > base girdling. The old needles were the major source of food for shoot growth and accounted for four-fifths or more of all shoot growth. The combined reserves in the branches, main stem, and roots accounted for less than 15% of shoot growth. The contribution of reserves from tissues other than old leaves was in the following order: branches > main stem > roots. Defoliation weakened apical dominance relations. In defoliated trees, many secondary axes elongated more than the terminal leader, and secondary axes in lower whorls often grew more than those in upper ones. The data suggest an important role of nutritional factors in correlative growth inhibition.