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J A Berry

Publications and source records attributed to J A Berry.

At least 19 recordsLinked to original sources
PubMed2006

Non-steady state effects in diurnal 180 discrimination by Picea sitchensis branches in the field.

We report diurnal variations in 18O discrimination (18 delta) during photosynthesis (18 delta A) and respiration (18 delta R) of Picea sitchensis branches measured in branch chambers in the field. These observations were compared with predicted 18 delta (18 delta pred) based on concurrent measurements of branch gas exchange to evaluate steady state and non-steady state (NSS) models of foliage water 18O enrichment for predicting the impact of this ecosystem on the Delta 18O of atmospheric CO2. The non-steady state approach substantially improved the agreement between 18 delta pred and observed 18 delta (18 delta obs) compared with the assumption of isotopic steady state (ISS) for the Delta 18O signature of foliage water. In addition, we found direct observational evidence for NSS effects: extremely high apparent 18 delta values at dusk, dawn and during nocturnal respiration. Our experiments also show the importance of bidirectional foliage gas exchange at night (isotopic equilibration in addition to the net flux). Taken together, neglecting these effects leads to an underestimation of daily net canopy isofluxes from this forest by up to 30%. We expect NSS effects to be most pronounced in species with high specific leaf water content such as conifers and when stomata are open at night or when there is high relative humidity, and we suggest modifications to ecosystem and global models of delta 18O of CO2.

Circadian Rhythm↗
PubMed2001

Analysis of intracytoplasmic sperm injection procedures related to delayed insemination and ejaculated, epididymal and testicular spermatozoa.

In all, 1210 treatment cycles were divided into three categories for retrospective analysis according to the period of delay between oocyte retrieval (occurring at a fixed time after human chorionic gonadotrophin) and intracytoplasmic sperm injection (ICSI) of <3 h, 3-5 h, >5 h (referred to as 'delayed ICSI'). Three stages from oocyte to the birth of a live baby were identified for statistical analysis, (i) fertilization (2PN zygotes), (ii) cleavage of 2PN zygotes, (iii) transferred embryo to live birth. Stages 1, 2 and 3 were analysed statistically for the three time periods. Chi-square analysis showed no significant effect of delayed ICSI on fertilization (chi(2) = 3.615, P = 0.65), and embryo transfer to birth (chi(2) = 1.840, P = 0.399). The effect on cleavage was significant (chi(2) = 9.625, P = 0.008). However, shorter incubation times produced results which were better than the traditional longer ones. The success rate at the cleavage stage was so high that the marginal advantage had very little effect on the overall process. This study of a substantial patient sample establishes that ICSI on a peri-ovulatory oocyte (<3 h after oocyte retrieval) does not compromise outcome parameters, and that longer periods of incubation (>5 h) do not offer a statistically significant advantage.

Journal Article↗
PubMed2001

Introduction.

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

Appropriateness of routine postoperative chest radiography after tracheotomy.

OBJECTIVE: To determine the appropriateness of postoperative chest radiography after adult tracheotomy. DESIGN: Retrospective case series. SETTING: Tertiary care academic medical center. PATIENTS: The records of 379 consecutive adult patients who underwent tracheotomy by the Otolaryngology-Head and Neck Surgery Service from January 1992 to December 1996 were available for review and met inclusion criteria. All patients underwent postoperative chest radiography. MAIN OUTCOME MEASURES: Frequency of postoperative tracheotomy-associated complications, most significantly pneumothorax. RESULTS: The patients had no pneumothorax on postoperative chest films. Minor complications, which were found in 7.1% of the patients, included small bleeds, wound infection, and subcutaneous emphysema. Tracheostomy-associated death occurred in 2 patients (0.5%). CONCLUSIONS: Routine postoperative chest radiography is unnecessary after adult tracheotomy. Chest radiography may be indicated by clinically suspicious signs or symptoms.

Adolescent↗
PubMed2000

In vitro resistance to bacterial biofilm formation on coated fluoroplastic tympanostomy tubes.

Bacterial biofilm formation has been implicated in persistent posttympanostomy otorrhea and irreversible tube contamination. The use of a tympanostomy tube with a resistance to biofilm formation by the most common organisms associated with persistent infection may decrease the incidence of chronic otorrhea and the need for tube removal. In this investigation, scanning electron microscopy was used to compare a phosphorylcholine-coated fluoroplastic tympanostomy tube to plain fluoroplastic and silver oxide-impregnated fluoroplastic for resistance to biofilm formation after in vitro incubation with Staphylococcus aureus or Pseudomonas aeruginosa. Only a biofilm from Pseudomonas formed on the untreated fluoroplastic tubes, whereas the silver oxide-impregnated tubes developed biofilms from both S aureus and P aeruginosa. In contrast, the coated fluoroplastic tube showed resistance to both staphylococcal and pseudomonal biofilm adhesion. This is the first study to demonstrate the effect of a surface treatment of fluoroplastic as a method to inhibit biofilm formation by both S aureus and P aeruginosa. This reinforces our previous studies showing that surface-adherence properties such as charge or slickness or both may be more beneficial than antibacterial treatments in preventing film adhesion.

Biofilms↗
PubMed1998

Delineation of the regions of interleukin-2 (IL-2) receptor beta chain important for association of Jak1 and Jak3. Jak1-independent functional recruitment of Jak3 to Il-2Rbeta.

Interleukin-2 (IL-2) induces heterodimerization of the IL-2 receptor beta (IL-2Rbeta) and gammac chains of its receptor and activates the Janus family tyrosine kinases, Jak1 and Jak3. Whereas Jak1 associates with IL-2Rbeta, Jak3 associates primarily with gammac but also with IL-2Rbeta. We analyzed four IL-2Rbeta mutations that diminish IL-2-induced proliferation and found that each also decreased IL-2-induced signal transducer and activator of transcription (STAT) activation. For this reason, and because the mutations were in the IL-2Rbeta membrane-proximal region, we investigated and found that each mutation diminished IL-2Rbeta association with both Jak1 and Jak3. This suggested that these Jaks might interact with the same region of IL-2Rbeta; however, certain IL-2Rbeta internal deletions and C-terminal truncations differentially affected the association of Jak1 and Jak3. Interestingly, just as Jak1-IL-2Rbeta association is Jak3-independent and functionally important, we show that Jak3-IL-2Rbeta association is Jak1-independent and implicate this association as being important for IL-2-induced Stat5 activation. Moreover, Jak1 and Jak3 could associate only in the presence of IL-2Rbeta, suggesting that these kinases can simultaneously bind to IL-2Rbeta. Thus, our data not only demonstrate that somewhat more distal as well as membrane-proximal cytoplasmic regions of a type I cytokine receptor are important for Jak kinase association but also suggest that two IL-2Rbeta-Jak kinase interactions are important for IL-2 signaling.

Animals↗
PubMed1995

Ubiquinone redox behavior in plant mitochondria during electron transport.

The redox poise of the ubiquinone pool during electron transfer in isolated soybean mitochondria has been compared using two different procedures: the rapid organic extraction of ubiquinone followed by quantification of the oxidized and reduced forms using high-pressure liquid chromatography and an electrochemical technique that measures ubiquinone reduction voltametrically. The goal of these studies was to rigorously test the use of the voltametric technique to monitor the redox status of ubiquinone during the course of mitochondrial electron transfer. The linear relationship between the two methods confirms the reliability of the data obtained with the voltametric technique; however, redox inactive pools of ubiquinone were detected with the HPLC technique. We also quantified the absolute amounts of the ubiquinone homologues ubiquinone-9 and ubiquinone-10 in mitochondria isolated from different soybean tissues and compared their behavior during electron transfer in the presence and absence of pyruvate, an allosteric effector of the cyanide-resistant electron transfer pathway. Both homologues belong to a common redox-active pool in the inner mitochondrial membrane. The results indicate that ubiquinone can be a limiting component of electron transfer through the cyanide-resistant pathway, particularly in roots where its concentration is much lower than in cotyledons.

Chromatography, High Pressure Liquid↗
PubMed1994

Oxygen-18 kinetic isotope effects in the dopamine beta-monooxygenase reaction: evidence for a new chemical mechanism in non-heme metallomonooxygenases.

Previous studies of dopamine beta-monooxygenase (D beta M) have implicated the formation of a substrate-derived benzylic radical via a hydrogen atom abstraction mechanism [Miller & Klinman (1985) Biochemistry 24, 2114]. We now address the nature of the oxygen species catalyzing C-H bond cleavage through the measurement of oxygen-18 isotope effects as a function of substrate structure. Using deuterium isotope effects, together with experimental O-18 isotope effects with protonated and deuterated substrates, it has been possible to calculate intrinsic O-18 isotope effects. Since the D beta M mechanism includes many steps which may involve changes in bond order at dioxygen, e.g., the reversible binding of O2 to the active-site copper and its reductive activation to a copper-hydroperoxide species, the intrinsic O-18 isotope effect is expected to be the product of two terms: (1) an overall equilibrium O-18 isotope effect on steps leading from O2 binding to the formation of the intermediate which catalyzes C-H bond cleavage and (2) a kinetic O-18 isotope effect on the C-H bond cleavage step. Thus, the magnitude of a single O-18 isotope effect measurement cannot reveal the nature of the bonding at oxygen during substrate activation. In the present study we have measured the change in O-18 isotope effect as a function of substrate structure and reactivity, finding values of 18(V/K) which decrease from 1.0281 +/- 0.001 to 1.0216 +/- 0.0003 as the rate of the C-H bond cleavage step decreases from 680 to 2 s-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1992

Evaluation of a personal computer-based quantitative coronary analysis system for rapid assessment of coronary stenoses.

Quantitative coronary analysis (QCA) is a technique that is rarely used because of the complexity and expense of existing systems. We studied a new personal computer-based QCA system that is capable of both geometric and densitometric analysis and compared it to a previously validated QCA system. Both systems performed extremely well in phantom analysis with 11 phantoms filmed in both 5-inch and 7-inch magnifications (R greater than 0.97 and SEE less than 0.33 mm for all modes). In 28 abnormal coronary angiograms analyzed at end diastole, stenosis and reference diameter correlations between the two systems were excellent (R = 0.90 and 0.96 and SEE = 0.43 and 0.33 mm for densitometric and geometric modes, respectively). Intraobserver and interobserver correlation was also excellent for both analysis modes. The new QCA system was able to perform analysis in approximately one third the time required by previously validated system and was much less expensive. We conclude that personal computer-based coronary analysis is an accurate, quick, and relatively inexpensive means for performing QCA that may help to make this technique feasible for nonresearch settings.

Constriction, Pathologic↗
PubMed1992

Measurements of the Engagement of Cyanide-Resistant Respiration in the Crassulacean Acid Metabolism Plant Kalanchoë daigremontiana with the Use of On-Line Oxygen Isotope Discrimination.

Discrimination against (18)O during dark respiration in tissues of Kalanchoë daigremontiana, Medicago sativa, and Glycine max was measured using an on-line system that enabled direct measurements of the oxygen fractionation of samples in a gas-phase leaf disk electrode unit. Discrimination factors for cytochrome pathway respiration were 18.6 to 19.8%(o) for all tissues. However, discrimination in cyanide-resistant respiration was significantly higher in green tissues (30.4-31.2%(o)) compared with nongreen tissues (25.3-25.9%(o)). Using these discrimination factors, the partitioning of electron transport to these pathways was calculated from measurements of discrimination in the absence of inhibitors. Changes in flux through the alternative pathway were measured during the light and dark phases of Crassulacean acid metabolism in leaf disks of K. daigremontiana. The flux of electrons through the alternative pathway was higher during deacidification than during the other phases of Crassulacean acid metabolism. The increase in alternative pathway electron flux accounted for all of the increased respiration in the light phase. Despite this increase, simultaneous measurements of malate concentration and respiratory flux confirm that only a small proportion of the total malate decarboxylation occurs in the mitochondria.

Journal Article↗
PubMed1991

Surface topography for patient repositioning.

For many years, this group has been interested in the measurement of patient surface contours in order to prepare radiotherapy compensators. Recently, these surface measurements have been made using optical ranging techniques (Medical Physics 16:425; 1989). A laser line is projected onto the patient surface and the video image of the line is digitized and used to calculate the coordinates of each point on the line. This surface information can be used not only for the calculation of compensators but can also be used to verify patient position from simulation to treatment and from one treatment to another. Because the calculation of surface coordinates takes approximately 30 seconds, the technique has been modified to allow the comparison of setup position in real time. In the new system, a series of narrow fan beams is projected to intersect the patient surface. At simulation, the reference video image of the lines is digitized and stored. At treatment setup, repeat video images are digitized and compared with the reference in real time. Operator adjustments to patient position are immediately shown on the composite image, and a congruency value is calculated to help in this process of alignment. Uses and accuracy of the technique will be discussed.

Humans↗
PubMed1991

Scintillation proximity assay: competitive binding studies with [125I]endothelin-1 in human placenta and porcine lung.

Scintillation proximity assay (SPA) technology has been used to investigate the competitive binding of [125I]endothelin-1 (ET-1) by ET-1, endothelin-2 (ET-2), endothelin-3 (ET-3), sarafotoxin 6b (SFTX-b), and big endothelin (big ET) to endothelin receptors in human placenta and porcine lung. Specific binding of [125I]ET-1 to high-affinity receptors was detected in membranes coupled to wheat germ agglutinin (WGA)-coated beads impregnated with scintillant (fluomicrospheres). The binding characteristics of ET-1 were similar in both of the tissues studied. In contrast, the receptor-binding properties of ET-2, ET-3, and SFTX-b were different in human placental and porcine lung membranes. This suggests that different endothelin receptor populations exist in these tissues. In addition, the binding characteristics of ET-3 and SFTX-b differed markedly to those of ET-1 and ET-2 in both tissues. This may be due to the four amino acid residue substitution in the N-terminal loop of both ET-3 and SFTX-b. We have also demonstrated that the ET-1 precursor, big ET, competitively inhibits [125I]ET-1 binding in these tissues, but is 100-fold less potent than ET-1.

Animals↗
PubMed1990

The use of digitized port films in assessing new treatment modalities.

An inexpensive computer-based imaging system has been used to compare simulator and portal radiographs. The films were digitized, normalized, and then overlaid for measurement. In a test group of patients, a new treatment protocol for pelvis irradiation was evaluated using this technique. For 90% of the patients, the average error was found to be smaller than 5 mm, and there were no field placement errors greater than 1 cm.

Female↗
PubMed1989

Topography of photosynthetic activity of leaves obtained from video images of chlorophyll fluorescence.

The distribution of photosynthetic activity over the area of a leaf and its change with time was determined (at low partial pressure of O(2)) by recording images of chlorophyll fluorescence during saturating light flashes. Simultaneously, the gas exchange was being measured. Reductions of local fluorescence intensity quantitatively displayed the extent of nonphotochemical quenching; quench coefficients, q(N), were computed pixel by pixel. Because rates of photosynthetic electron transport are positively correlated with (1 - q(N)), computed images of (1 - q(N)) represented topographies of photosynthetic activity. Following application of abscisic acid to the heterobaric leaves of Xanthium strumarium L., clearly delineated regions varying in nonphotochemical quenching appeared that coincided with areoles formed by minor veins and indicated stomatal closure in groups.

Journal Article↗
PubMed1989

Low and High Temperature Limits to PSII : A Survey Using trans-Parinaric Acid, Delayed Light Emission, and F(o) Chlorophyll Fluorescence.

Many studies have shown that membrane lipids of chilling-sensitive plants begin lateral phase separation (i.e. a minor component begins freezing) at chilling temperatures and that chilling-sensitive plants are often of tropical origin. We tested the hypothesis that membranes of tropical plants begin lateral phase separation at chilling temperatures, and that plants lower the temperature of lateral phase separation as they invade cooler habitats. To do so we studied plant species in one family confined to the tropics (Piperaceae) and in three families with both tropical and temperate representatives (Fabaceae [Leguminosae], Malvaceae, and Solanaceae). We determined lateral phase separation temperatures by measuring the temperature dependence of fluorescence from trans-parinaric acid inserted into liposomes prepared from isolated membrane phospholipids. In all families we detected lateral phase separations at significantly higher temperatures, on average, in species of tropical origin. To test for associated physiological effects we measured the temperature dependence of delayed light emission (DLE) by discs cut from the same leaves used for lipid analysis. We found that the temperature of maximum DLE upon chilling was strongly correlated with lateral phase separation temperatures, but was on average approximately 4 degrees C lower. We also tested the hypothesis that photosystem II (PSII) (the most thermolabile component of photosynthesis) of tropical plants tolerates higher temperatures than PSII of temperate plants, using DLE and F(o) chlorophyll fluorescence upon heating to measure the temperature at which PSII thermally denatured. We found little difference between the two groups in PSII denaturation temperature. We also found that the temperature of maximum DLA upon heating was not significantly different from the critical temperature for F(o) fluorescence. Our results indicate that plants lowered their membrane freezing temperatures as they radiated from their tropical origins. One interpretation is that the tendency for membranes to begin freezing at chilling temperatures is the primitive condition, which plants corrected as they invaded colder habitats. An alternative is that membranes which freeze at temperatures only slightly lower than the minimum growth temperature confer an advantage.

Journal Article↗