Determining the gluonic gravitational form factors of the proton

The proton is one of the main building blocks of all visible matter in the Universe¹. Among its intrinsic properties are its electric charge, mass and spin². These properties emerge from the complex dynamics of its fundamental constituents-quarks and gluons-described by the theory of quantum chromodynamics^3-5. The electric charge and spin of protons, which are shared among the quarks, have been investigated previously using electron scattering². An example is the highly precise measurement of the electric charge radius of the proton⁶. By contrast, little is known about the inner mass density of the proton, which is dominated by the energy carried by gluons. Gluons are hard to access using electron scattering because they do not carry an electromagnetic charge. Here we investigated the gravitational density of gluons using a small colour dipole, through the threshold photoproduction of the J/ψ particle. We determined the gluonic gravitational form factors of the proton^7,8 from our measurement. We used a variety of models^9-11 and determined, in all cases, a mass radius that is notably smaller than the electric charge radius. In some, but not all cases, depending on the model, the determined radius agrees well with first-principle predictions from lattice quantum chromodynamics¹². This work paves the way for a deeper understanding of the salient role of gluons in providing gravitational mass to visible matter.

Measurement of the Nucleon F_{2}^{n}/F_{2}^{p} Structure Function Ratio by the Jefferson Lab MARATHON Tritium/Helium-3 Deep Inelastic Scattering Experiment

The ratio of the nucleon F_{2} structure functions, F_{2}^{n}/F_{2}^{p}, is determined by the MARATHON experiment from measurements of deep inelastic scattering of electrons from ^{3}H and ^{3}He nuclei. The experiment was performed in the Hall A Facility of Jefferson Lab using two high-resolution spectrometers for electron detection, and a cryogenic target system which included a low-activity tritium cell. The data analysis used a novel technique exploiting the mirror symmetry of the two nuclei, which essentially eliminates many theoretical uncertainties in the extraction of the ratio. The results, which cover the Bjorken scaling variable range 0.19<x<0.83, represent a significant improvement compared to previous SLAC and Jefferson Lab measurements for the ratio. They are compared to recent theoretical calculations and empirical determinations of the F_{2}^{n}/F_{2}^{p} ratio.

Ruling out Color Transparency in Quasielastic ^{12}C(e,e^{'}p) up to Q^{2} of 14.2 (GeV/c)^{2}

Quasielastic ^{12}C(e,e^{'}p) scattering was measured at spacelike 4-momentum transfer squared Q^{2}=8, 9.4, 11.4, and 14.2  (GeV/c)^{2}, the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no Q^{2} dependence, up to proton momenta of 8.5  GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured Q^{2} scales in exclusive (e,e^{'}p) reactions. These results impose strict constraints on models of color transparency for protons.

Probing the Deuteron at Very Large Internal Momenta

We measure ^{2}H(e,e^{'}p)n cross sections at 4-momentum transfers of Q^{2}=4.5±0.5  (GeV/c)^{2} over a range of neutron recoil momenta p_{r}, reaching up to ∼1.0  GeV/c. We obtain data at fixed neutron recoil angles θ_{nq}=35°, 45°, and 75° with respect to the 3-momentum transfer q[over →]. The new data agree well with previous data, which reached p_{r}∼500  MeV/c. At θ_{nq}=35° and 45°, final state interactions, meson exchange currents, and isobar currents are suppressed and the plane wave impulse approximation provides the dominant cross section contribution. We compare the new data to recent theoretical calculations, where we observe a significant discrepancy for recoil momenta p_{r}>700  MeV/c.

Probing Few-Body Nuclear Dynamics via ^{3}H and ^{3}He (e,e^{'}p)pn Cross-Section Measurements

We report the first measurement of the (e,e^{'}p) three-body breakup reaction cross sections in helium-3 (^{3}He) and tritium (^{3}H) at large momentum transfer [⟨Q^{2}⟩≈1.9  (GeV/c)^{2}] and x_{B}>1 kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta 40≤p_{miss}≤500  MeV/c that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon. The measured cross sections are compared with state-of-the-art ab initio calculations. Overall good agreement, within ±20%, is observed between data and calculations for the full p_{miss} range for ^{3}H and for 100≤p_{miss}≤350  MeV/c for ^{3}He. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at p_{miss}>250  MeV/c and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of ^{3}He plus ^{3}H, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire p_{miss} range. This validates current models of the ground state of the three-nucleon system up to very high initial nucleon momenta of 500  MeV/c.

Revealing Color Forces with Transverse Polarized Electron Scattering

The Spin Asymmetries of the Nucleon Experiment measured two double spin asymmetries using a polarized proton target and polarized electron beam at two beam energies, 4.7 and 5.9 GeV. A large-acceptance open-configuration detector package identified scattered electrons at 40° and covered a wide range in Bjorken x (0.3<x<0.8). Proportional to an average color Lorentz force, the twist-3 matrix element, d[over ˜]_{2}^{p}, was extracted from the measured asymmetries at Q^{2} values ranging from 2.0 to 6.0  GeV^{2}. The data display the opposite sign compared to most quark models, including the lattice QCD result, and an unexpected scale dependence. Furthermore, when combined with the neutron data in the same Q^{2} range the results suggest a flavor independent average color Lorentz force.

Precision measurement of the neutron twist-3 matrix element d(2)(n): probing color forces

Double-spin asymmetries and absolute cross sections were measured at large Bjorken x  (0.25≤x≤0.90), in both the deep-inelastic and resonance regions, by scattering longitudinally polarized electrons at beam energies of 4.7 and 5.9 GeV from a transversely and longitudinally polarized (3)He target. In this dedicated experiment, the spin structure function g(2)((3)He) was determined with precision at large x, and the neutron twist-3 matrix element d(2)(n) was measured at ⟨Q(2)⟩ of 3.21 and 4.32  GeV(2)/c(2), with an absolute precision of about 10(-5). Our results are found to be in agreement with lattice QCD calculations and resolve the disagreement found with previous data at ⟨Q(2)⟩=5  GeV(2)/c(2). Combining d(2)(n) and a newly extracted twist-4 matrix element f(2)(n), the average neutron color electric and magnetic forces were extracted and found to be of opposite sign and about 30  MeV/fm in magnitude.

Probing the repulsive core of the nucleon-nucleon interaction via the (4)He(e,e'pN) triple-coincidence reaction

We studied simultaneously the (4)He(e,e'p), (4)He(e,e'pp), and (4)He(e,e'pn) reactions at Q(2)=2(GeV/c)(2) and x(B)>1, for an (e,e'p) missing-momentum range of 400 to 830  MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum, in a region where the nucleon-nucleon (NN) force is expected to change from predominantly tensor to repulsive. The abundance of neutron-proton pairs is reduced as the nucleon momentum increases beyond ∼500  MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum. Our data are compared with calculations of two-nucleon momentum distributions in (4)He and discussed in the context of probing the elusive repulsive component of the NN force.

Measurement of the neutron radius of 208Pb through parity violation in electron scattering

We report the first measurement of the parity-violating asymmetry A(PV) in the elastic scattering of polarized electrons from 208Pb. A(PV) is sensitive to the radius of the neutron distribution (R(n)). The result A(PV)=0.656±0.060(stat)±0.014(syst) ppm corresponds to a difference between the radii of the neutron and proton distributions R(n)-R(p)=0.33(-0.18)(+0.16) fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

Measurements of the proton elastic-form-factor ratio mu pG p E/G p M at low momentum transfer

High-precision measurements of the proton elastic form-factor ratio, mu pG p E/G p M, have been made at four-momentum transfer, Q2, values between 0.2 and 0.5 GeV2. The new data, while consistent with previous results, clearly show a ratio less than unity and significant differences from the central values of several recent phenomenological fits. By combining the new form-factor ratio data with an existing cross-section measurement, one finds that in this Q2 range the deviation from unity is primarily due to G p E being smaller than expected.

Pressure gradients along whole culms and leaf sheaths, and other aspects of humidity-induced gas transport in Phragmites australis

Emergent aquatic macrophytes growing in waterlogged anaerobic sediments overlain by deep water require particularly efficient ventilating systems. In Phragmites australis (Cav.) Trin. ex Steud, pressurized gas flows, generated by humidity-induced diffusion of air into leaf sheaths, enhance oxygen transport to below-ground parts and aid in the removal of respiratory CO2 and sediment-generated CO2 and methane. Although modelling and flow measurements have pointed to the probable involvement of all leaf sheaths in the flow process and the development of pressure gradients along the whole lengths of living culm and leaf sheaths, direct measurements of pressure gradients have never been reported. The aim of this study was to search for pressure gradient development in Phragmites culms and leaf sheaths and to determine their magnitudes and distribution. In addition, dynamic (with gas flow) and static pressures (no flow condition) and their relationship to flows, leaf sheath areas, and living-to-dead culm ratios were further investigated. Dynamic pressures (DeltaPd) recorded in the pith cavities of intact (non-excised) leafy culms, pneumatically isolated from the below-ground parts and venting through an artificial bore-hole near the base, revealed a curvilinear gradient of pressure 'asymptoting' towards the tips of the culms. Similarly, DeltaPd in upper and lower parts of leaf sheaths increased with distance from the base of the culm, with values in the upper parts always being greater. Curvilinear gradients of pressure were also found along pneumatically isolated individual leaf sheaths, but radial channels linking the leaf sheath aerenchyma with the pith cavity of the culm appeared to offer little resistance to flow. In keeping with predictions, static pressure differentials (DeltaPs) achieved in intact and excised culms and single leaf sheaths on intact culms proved to be relatively independent of leaf sheath area, whereas the potential for developing convective flows (pressure-driven flows) increased with increasing leaf sheath area. As measured by the ventilating coefficient [1-(DeltaPd/(DeltaPs)] the old dead (efflux) to living (influx) culm ratio of 1:12 compared with 1:25 raised ventilating efficiency from 31% to 71%, giving flows per tall culm into the rhizome system of c. 2.8 cm3 and 6.5 cm3 min-1, respectively. It was concluded that dynamic pressure gradients probably extend along the whole length of the leafy culms and leaf sheaths of Phragmites and that all leaf sheaths and all exposed points along the leaf sheaths can contribute convective gas-flow to the rhizome system.

Rhizome phyllosphere oxygenation in Phragmites and other species in relation to redox potential, convective gas flow, submergence and aeration pathways

Underground rhizomes of emergent aquatic macrophytes are important for perennation, vegetative spread, competition and anchorage. In four species we examined the potential for the development of oxidized phyllospheres around rhizome apical buds, similar to the protective oxygenated rhizospheres around roots. Redox potentials and polarographic measurements of radial oxygen loss were recorded using platinum cathodes around the apical buds. The aeration pathway from atmosphere to phyllosphere was investigated anatomically and by applied pressurized gas flow. Redox potentials increased by +400, +45, +200 and +340 mV around rhizome apices of Phragmites australis, Oryza rhizomatis, Carex rostrata and Glyceria maxima, respectively. Radial oxygen loss from rhizome apices of Phragmites was increased by convective gas flow through the rhizome and by shoot de-submergence, and decreased by resistances applied within the aeration pathway and by shoot submergence. We conclude that oxygen passes via internal gas-space connections between aerial shoot, rhizome and underground buds and into the phyllosphere regions via scale-leaf stomata and surfaces on the buds. We suggest that oxidized phyllospheres may protect rhizome apices against phytotoxins in waterlogged soils, just as oxidized rhizospheres protect roots.

Determination of the interconversion energy barrier of enantiomers by separation methods

Separation methods have become versatile tools for the determination of kinetic activation parameters and energy barriers to interconversion of isomers and enantiomers in the last 20 years. New computer-aided evaluation systems allow the on-line determination of these data after separating minute amount of pure compounds or mixture of isomers or enantiomers, respectively. Both dynamic interconversion during the separation process as well as static stopped-flow techniques have been applied to determine the kinetic activation parameters and interconversion energy barriers by separation methods. The use of (1) combinations of batchwise kinetic studies with enantioselective separations, (2) a continuous flow model, (3) a comparison of real chromatograms with simulated ones, (4) stopped-flow techniques, (5) stochastic methods, (6) approximation functions and (7) deconvolution methods, for the determination of interconversion energy barriers by separation methods is summarized in detail.

Rice and Phragmites: effects of organic acids on growth, root permeability, and radial oxygen loss to the rhizosphere

Young Phragmites plants were grown in two cocktails of monocarboxylic acids (C(1)-C(5)) at pH 6, where the concentration of each acid was innocuous and the total undissociated (potentially toxic) concentrations were 0.35 mmol/L and 0.42 mmol/L. Rice plants were subjected to 1.5 mmol/L acetic acid at pH 4.5 (undissociated concentration = 1.05 mmol/L). In Phragmites, each cocktail curtailed root growth especially and induced premature shoot senescence. In both species, after 3-5 d of treatment, radial oxygen loss (ROL) from apical regions of adventitious roots, and from Phragmites laterals, was reduced to very low values and associated with cell wall lignification and suberization in the surface cell layers. At later stages of treatment, rice responded to acetic acid in similar ways to Phragmites, with the development of intercellular and callus type occlusions in the gas space system, vascular blockages, and the failure of laterals to emerge. The results are relevant to the supply of oxygen from Phragmites roots to sediments for the phytopurification of waste waters, to the efflux of methane and carbon dioxide from wetlands, and to rice cultivation.

Pneumocystis carinii cytochrome b mutations are associated with atovaquone exposure in patients with AIDS

This retrospective cohort study was conducted to determine whether Pneumocystis carinii cytochrome b gene mutations in patients with AIDS and P. carinii pneumonia (PCP) are associated with atovaquone exposure. Portions of the P. carinii cytochrome b genes that were obtained from 60 patients with AIDS and PCP from 6 medical centers between 1995 and 1999 were amplified and sequenced by using polymerase chain reaction. Fifteen patients with previous atovaquone prophylaxis or treatment exposure were matched with 45 patients with no atovaquone exposure. Cytochrome b coenzyme Q binding site mutations were observed in 33% of isolates from patients exposed to atovaquone, compared with 6% from those who were not (P=.018). There was no difference in survival 1 month after treatment between patients with or without cytochrome b mutations (P=.14). Thus, cytochrome b mutations are significantly more common in patients with AIDS and PCP with atovaquone exposure, but the clinical significance of these mutations remains unknown.

The role of oxygen in submergence-induced petiole elongation in Rumex palustris: in situ measurements of oxygen in petioles of intact plants using micro-electrodes

In a study on the mechanism of stimulated petiole elongation in submerged plants, oxygen concentrations in petioles of the flood-tolerant plant Rumex palustris were measured with micro-electrodes. Short-term submergence lowered petiole partial oxygen pressure to c. 19 kPa whereas prolonged submergence under continuous illumination depressed oxygen levels to c. 8-12 kPa after 24 h. Oxygen levels in petioles depended on the presence of the lamina, even in submerged conditions, and on available light. In darkness, petiole oxygen levels in submerged plants dropped quickly to values as low as 0.5-4 kPa. It is hypothesized that prolonged submergence in the light is accompanied by a decrease in carbon dioxide in the petiole. Submergence-enhanced petiolar elongation rate was compared with emergent plants. Peak daily elongation rates occurred at the end of the dark period in emergent plants, but in the middle of the light period in submerged plants. We suggest that this shift in daily elongation pattern is induced by dependence of growth on photosynthetically derived oxygen in submerged plants. Implications of reduced oxygen for ethylene production are raised. Levels of 1- aminocyclopropane-1-carboxylic acid synthase and 1-aminocyclopropane-1-carboxylic acid oxidase and ethylene sensitivity are cited as potential factors in hypoxia-induced ethylene release.

Pneumocystis carinii mutations are associated with duration of sulfa or sulfone prophylaxis exposure in AIDS patients

This study was conducted to determine whether Pneumocystis carinii dyhydropteroate synthase (DHPS) gene mutations in AIDS patients with P. carinii pneumonia (PCP) are affected by duration of sulfa or sulfone prophylaxis and influence response to sulfa or sulfone therapy. The P. carinii DHPS genes from 97 AIDS patients with PCP between 1991 and 1999 from 4 medical centers were amplified, using polymerase chain reaction (PCR), and sequenced. Mutations were observed in 76% of isolates from patients exposed to sulfa or sulfone prophylaxis compared with 23% of isolates from patients not exposed (P=.001). Duration of prophylaxis increased the risk of mutations (relative risk [RR] for each exposure month, 1.06; P=.02). Twenty-eight percent of patients with mutations failed sulfa or sulfone treatment; mutations increased the risk of sulfa or sulfone treatment failure (RR, 2.1; P=0.01). Thus, an increased duration of sulfa or sulfone prophylaxis increases the chance of developing a P. carinii mutation. The majority of patients with mutations respond to sulfa or sulfone therapy.

Pneumocystis carinii mutations associated with sulfa and sulfone prophylaxis failures in immunocompromised patients

Recent studies have shown that mutations in two amino acid positions of the Pneumocystis carinii dihydropteroate synthase gene are significantly more common in immunocompromised patients with P. carinii pneumonia who fail sulfa or sulfone prophylaxis. This paper reviews the studies that suggest that these mutations may be responsible for some failures of prophylaxis in P. carinii.

Preoperative echocardiographic evaluation of patients referred for lung volume reduction surgery

BACKGROUND

The most efficient preoperative assessment for lung volume reduction surgery (LVRS) in patients with advanced emphysema is undefined. This study analyzed the preoperative assessment of patients by surface echocardiography (without and with dobutamine infusion), the results of which were used to exclude patients with significant pre-existing cardiac disease, a contraindication to LVRS, from the surgery.

SETTING

A university-based, tertiary care referral center.

METHODS

Patients with emphysema who met initial LVRS screening criteria underwent resting and stress surface echocardiography with Doppler imaging. Patients were evaluated prospectively for perioperative cardiac complications.

RESULTS

Between July 1994 and December 1996, 503 candidates for LVRS were evaluated. Of these, 207 patients (81.8%) who had echocardiography performed at our institution formed the primary study group. Images were adequate for the analysis of chamber sizes and function in 206 patients (99.5%) undergoing resting echocardiography, and the images were adequate for wall motion analysis in 172 of 174 patients (98.9%) undergoing functional testing. Right heart abnormalities were common (40.1%). Significant pulmonary hypertension (> 35 mm Hg) was uncommon (5 patients, 5.4%) among the 92 patients who subsequently underwent right heart catheterization. Occult ischemia, left ventricular dysfunction, and valvular abnormalities also were uncommon. Thus, although Doppler imaging estimates of right ventricular systolic pressure were imperfect, echocardiographic findings of normal right heart anatomy and function excluded significant pulmonary hypertension. Ninety patients (43%) eventually underwent LVRS (70 bilateral and 20 unilateral). A total of 13 perioperative cardiac events occurred in 10 patients, 6 of whom had undergone preoperative echocardiography. No patient suffered acute myocardial infarction or cardiac death.

CONCLUSIONS

Despite potential limitations due to severe obstructive lung disease, surface echocardiographic imaging is a feasible, noninvasive tool in this patient population to identify patients with evidence of cor pulmonale that suggests pulmonary hypertension. The routine use of surface resting and stress echocardiography for preoperative screening obviates the need for invasive right heart catheterization in many patients and results in a low incidence of significant perioperative cardiac complications.

Pharyngoesophageal reconstruction with the ulnar forearm flap

OBJECTIVE

To evaluate the use of a generous fasciocutaneous ulnar forearm free flap in pharyngoesophageal reconstruction.

DESIGN

Tertiary referral center.

SETTING

Private practice.

PATIENTS

From September 1, 1991, to October 30, 1996, 20 ulnar forearm free flaps were used to reconstruct the pharyngoesophagus in 19 patients after surgery for squamous cell carcinoma. There were 13 circumferential defects and 7 near-circumferential defects (<2 cm of mucosa remaining). The reconstructions were performed primarily (at the time of tumor resection) in 16 cases and secondarily in 4 cases.

INTERVENTION

A generous fasciocutaneous ulnar forearm flap with a minimum dimension of 9 x 22 cm was harvested to reconstruct the pharyngoesophagus. A 2-layer closure was performed in flap tailoring and proximal (pharynx to flap) and distal (flap to esophagus) anastomoses to minimize the risk of leakage. Also, portions of the flap were used to monitor flap viability, to cover cervical vessels, to obliterate dead space, and as skin coverage when the skin flaps were deficient.

RESULTS

Nineteen of the 20 flaps transferred were successful. Swallow function was restored in 18 cases, and voice was rehabilitated in all the patients using either tracheoesophageal puncture and a voice device or an electrolarynx device. There was 1 perioperative mortality. Three fistulas occurred, all of which healed with nonsurgical treatment. One stricture developed that required intermittent dilatation. The donor site morbidity was minor.

CONCLUSIONS

This versatile technique achieves excellent results with a decreased complication rate compared with other methods currently available in pharyngoesophageal reconstruction.

Illusions of control, underestimations, and accuracy: a control heuristic explanation

The illusions of control area is reviewed, and 5 conditions that influence control judgments are identified: skill-related factors, success or failure emphasis, need for the outcome, mood, and the intrusion of reality. It is proposed that individuals use a control heuristic that includes perceptions of intentionality and connection. Judgments of intentionality are based on foreseeability, ability to produce the effect, and valence of the outcome. Judgments of connection are based on the perceived association between the action and the outcome, which includes temporal, shared meaning, and predictive association. Effects of motives to overestimate, underestimate, and have accurate assessments of control are explained, using the concepts of hindsight bias, connection, and counterfactuals. In addition, the relation between the control heuristic and illusory correlation research and applications of the control heuristic to coping with chronic illness are explored.

Recommendations for training in performance and interpretation of stress echocardiography. Committee on Physician Training and Education of the American Society of Echocardiography

Stress echocardiography has emerged as a clinically useful procedure in the management of patients with ischemic heart disease and other conditions. However, the accuracy of this test relies on the ability of those who carry out the technical aspects of the test and depends critically on proper interpretation of the images. Appreciation of wall motion abnormalities is generally acknowledged as one of the most difficult skills to master in echocardiography. There is consensus that this is also one of the most difficult skills to teach. Appreciating stress-induced changes in wall motion, which sometimes are subtle, requires a significant commitment to initial training in this skill and its maintenance. This document provides recommendations for physician training in stress echocardiography.

Lateral arm microvascular flap in head and neck reconstruction

OBJECTIVES

To report our results of a study of 28 patients who underwent sequential reconstructions of the head and neck using the lateral arm flap. To discuss the situations where we have found the procedure useful, report the complication rates, and delineate the advantages and disadvantages of using this flap.

DESIGN

A clinical series of patients was followed up prospectively. The swallowing function of a subgroup that underwent oropharyngeal reconstruction was compared with that of a simultaneous control group that underwent reconstruction with the pectoralis major flap.

SETTING

University medical center.

PARTICIPANTS

Patients with malignant neoplasms of the head and neck who underwent resections and reconstruction with the lateral arm flap.

INTERVENTIONS

Twenty-eight patients underwent head and neck reconstruction using lateral arm flaps. In 17 patients, the lateral arm flaps were used for pharyngeal and posterior oral cavity defects. Thirteen of these patients underwent reinnervation. Nine combined palatal and midfacial defects were reconstructed, and 1 lateral facial defect was reconstructed. Most cases were advanced malignant neoplasms and represented a selected minority of similar resections performed at our institutions. Three maxillary reconstructions were performed secondarily. All other reconstructions were performed at the time of tumor ablation.

MAIN OUTCOME MEASURES

Data were collected regarding flap survival, return of sensation in flaps, complication rates, and the ability to feed orally.

RESULTS

All flaps survived in their entirety. Of 7.5 tested flaps acquired sensation. Of 14 patients with large oropharyngeal defects, 8 resumed early oral feeding and all survivors eventually obtained nutrition orally. The ability to swallow was superior to the results obtained in a retrospective analysis of a group reconstructed using pectoralis major flaps.

CONCLUSIONS

A unique feature of this flap is that it incorporates both thin skin from the proximal forearm and thicker skin from the upper arm. This is ideal for an oropharyngeal defect, where the thin malleable portion can be used in the posterior oral cavity or pharyngeal wall and the thicker portion in the tongue base. Either portion can be used alone as well. The availability of intermediate tissue bulk can also be advantageous for midfacial reconstruction. Sensation can be reliably reconstituted with this flap. We think that the lateral arm flap is versatile and has particularly low donor-site morbidity.

De novo chronic graft-versus-host disease presenting as hemolytic anemia following partially mismatched related donor bone marrow transplant

Chronic graft-versus-host disease (cGVHD) is a disease of immune dysregulation that resembles an autoimmune disease. It usually involves the skin, mucosal and serosal surfaces and, less commonly, the hematopoietic system. We report hemolytic anemia (HA) as the primary manifestation of de novo cGVHD in recipients of partially mismatched related donor transplants. Five of 40 eligible patients developed HA at a median of 168 days post-transplant. Recipients were mismatched for one to three major HLA antigens. Conditioning therapy consisted of total body irradiation, etoposide, Ara-C, cycle-phosphamide and steroids. GVHD prophylaxis included partial T cell depletion, using anti alpha/beta CD3 antibody (T10B9) and complement, in addition to post-transplant immunosuppression. At presentation, all patients were receiving cyclosporine with or without low-dose steroids. Along with a mean Hb of 7.1 g%, patients had an increased reticulocyte count, a mild raised lactic dehydrogenase and a positive Coombs' test (in 2/5 patients). Four patients had also demonstrated a decrease in platelet count. Treatment was initiated with high-dose steroids and intravenous gamma globulin and response was observed within 1 week. Awareness of this presentation of cGVHD and early therapeutic intervention can result in successful reversal of presumed immune-mediated red cell and platelet destruction.

Phragmites die-back: sulphide- and acetic acid-induced bud and root death, lignifications, and blockages within aeration and vascular systems

Phragmites rhizome cuttings, and plantlets raised from seed, were exposed to the phytotoxins acetic acid or dissolved sulphide in unstirred solution cultures to determine whether die-back symptoms found in field-grown plants, and attributed to phytotoxin damage, could be induced. Many of the die-back symptoms associated with field sites, namely stunted adventitious roots and laterals, bud death, callus blockages of the gas-pathways, and vascular blockages, were all reproduced, and were particularly acute at the higher concentrations of the phytotoxins: acetic acid (1.67 mm), sulphide (1.4 mm). The results accord with the hypothesis that phytotoxins may play a critical role in Phragmites australis die-back.

Breast cancer in New Zealand: trends, patterns, and data quality

AIMS

To determine if incidence of cancer of the female breast in New Zealand is changing by age, ethnic group, and geographic region, and if there are differences in rates for stage of tumour by urban and rural residence.

METHODS

Age-adjusted incidence rates for Maori and nonMaori were computed from all primary cancers of the breast registered in the National Cancer Registry, 1978-92. Analyses of time trends and geographic variations were conducted using standard statistical methods.

RESULTS

There were steady, but nonsignificant, increases in the Maori and nonMaori incidence rates between 1978-92 which represents important increases in case numbers. The age-specific rates increased sharply from age 20, levelled out at age 45 and slowly increased through 85 years and older. There was a significant trend over time for the rate of "not staged" cases which was due to an artifact. No statistically significant variations in the age-adjusted rates by area (14 area health board districts, 4 regional health authorities), or by stage of tumour in three urban-rural groups were found. Maori women showed less shift in incidence rates from regional to local stage of tumour than nonMaori. The proportion of tumours reported without stage increased in the period 1988-92. A large proportion of cases had nonspecific morphology codes.

CONCLUSIONS

There are small differences between rates of breast cancer in rural and urban residences in New Zealand, as compared to some other countries. The quality of the Cancer Registry as a basis for evaluating the planned breast cancer screening programme is adversely affected by the high proportion of cases found with no reported stage of tumour. The proportion of nonspecific morphologies in these data is also of concern. The recent passing of the Cancer Registry Act should ensure better reporting of morphologies.

Improved stenosis geometry by quantitative coronary arteriography after vigorous risk factor modification

This study is a randomized, controlled, blinded, arteriographic trial to determine the effects of a low-cholesterol, low-fat, vegetarian diet, stress management and moderate aerobic exercise on geometric dimensions, shape and fluid dynamic characteristics of coronary artery stenoses in humans. Complex changes of different primary stenosis dimensions in opposite directions or to different degrees cause stenosis shape change with profound effects on fluid dynamic severity, not accounted for by simple percent narrowing. Accordingly, all stenosis dimensions were analyzed, including proximal, minimal, distal diameter, integrated length, exit angles and exit effects, determining stenosis shape and a single integrated measure of stenosis severity, stenosis flow reserve reflecting functional severity. In the control group, complex shape change and a stenosis-molding characteristic of statistically significant progressing severity occurred with worsening of stenosis flow reserve. In the treated group, complex shape change and stenosis molding characteristic of significant regressing severity was observed with improved stenosis flow reserve, thereby documenting the multidimensional characteristics of regressing coronary artery disease in humans.

A biotin-containing compound N-(2-aminoethyl)biotinamide for intracellular labeling and neuronal tracing studies: comparison with biocytin

The hydrochloride salt of a new, small molecular weight (M.W. = 286) biotin-containing compound referred to as biotinamide (N-(2-aminoethyl)biotinamide) was compared with biocytin (M.W. = 372) for its use in intracellular labeling of neurons and in neuronal tracing experiments using avidin conjugates for histochemical detection. The DC resistance and current passing ability of electrodes filled with 1-2 M potassium chloride, potassium acetate or potassium methylsulfate and containing 1-4% of these compounds were compared. Although differences were observed due to the electrolyte, with KCl electrodes being the least resistant, no electrode differences could be attributed to the concentration or type of tracer. However, whereas biocytin could be electrophoresed with either positive or negative current with roughly similar facility, biotinamide was selectively ejected with positive current. This would be beneficial to electrophysiologists using hyperpolarizing current to stabilize the membrane potential of neurons prior to recording. In addition, biotinamide-HCl could be dissolved at concentrations of 2-4% in either 1 or 2 M salt without precipitation, whereas biocytin precipitated in some of these solutions. Both compounds were equally useful for neuronal tracing experiments with survival times of 2 days, but labeling was much weaker with longer survival times. There was also little difference in the ability to histochemically localize these compounds using avidin conjugates, including avidin-biotin-horseradish peroxidase complex. In conclusion, biotinamide shares many of the useful features of biocytin, but can be selectively electrophoresed with positive current and can be dissolved at higher concentrations with little detriment in the electrical properties of the recording electrode.

Increased rate of base substitution in a hamster mutator strain obtained during serial selection for gene amplification

The pattern of mutations produced by a mutator gene (obtained during serial selection for amplification of the dihydrofolate reductase [dhfr] locus) shows a pronounced shift from that found in wild-type cells. The rate of certain types of base substitutions (particularly transitions) is dramatically increased, while gene rearrangements constitute a lower proportion of mutations. These data suggest a lower fidelity of the replication process in the mutator strain.

Light-enhanced convective throughflow increases oxygenation in rhizomes and rhizosphere of Phragmites australis (Cav.) Trin. ex Steud

The convective throughflow of gases found recently in Phragmites australis increased with increasing fluxes of photosynthetically active radiation. Despite this, the oxygen in the venting gases remained lower than in air and the convection is thought to depend mainly on a humidity-induced diffusion of atmospheric gases across the leaf sheaths. When convection was prevented, and aeration was dependent entirely upon diffusion, no photosynthetic enhancement of rhizome and root aeration could be detected. In terms of oxygen transport, rapid rates of convection were much more effective than diffusion and substantially enhanced the entry of oxygen into the rhizome system. This resulted in large increases in the efflux of oxygen into the rhizospheres of basal laterals and apical and sub-apical regions of the adventitious roots. This effect was attributed to a greater diffusion of oxygen from rhizome to root. Substantial diurnal fluctuations in rhizome oxygen regimes and in root oxygen efflux occurred. It is estimated that because of convection and diffusion, up to 0.31 kg of oxygen d^-1 m^-1 may enter the rhizome system of vigorous stands of Phragmites during summer months. By comparison, diffusion alone could be expected to supply less than 0.01 kg d^-1 . Scanning electron micrographs of root-shoot junctions showed that the resistance to gaseous diffusion from rhizome to roots must be especially small in Phragmites.

Molecular basis of spontaneous mutation at the aprt locus of hamster cells

Mutations occurring spontaneously at the hamster aprt locus were examined at the base-pair level by amplifying target sequences using the polymerase chain reaction and then directly sequencing the double-stranded products. In a collection of 89 sequenced genes, all types of mutations were found, with transitions (mostly G.C to A.T) constituting the largest class (35%), transversions accounting for 27%, and small deletions/duplications for 25%. Simple base substitutions were distributed throughout the aprt structural gene with few sites having recurring mutations and G.C base-pairs being the predominant substitution target. Small deletions, on the other hand, were not distributed so evenly, being concentrated in a region of aprt rich in short direct and inverted repeat sequences. The base substitutions were predominantly missense, while about 10% produced nonsense codons. Splice junctions, and start and stop codons were also significant targets for mutation. No alterations were detected in three aprt-deficient strains after sequencing all exons and substantial upstream and downstream regions.

Non-invasive diagnosis of ischemic heart disease using stress thallium scintigraphy and digital exercise 2-dimensional echocardiography

The introduction of computer technology has overcome many of the technical difficulties in performing and interpreting echocardiograms obtained from exercising individuals and has made stress echocardiography a potentially practical examination. Additional data, however, are necessary to establish the accuracy of exercise echocardiography. The purpose of this study is to compare exercise echocardiography and planar thallium studies for accuracy in detecting coronary artery disease. The study was performed on 50 patients, 41 of whom underwent coronary angiography. For the remaining 9 patients accuracy was defined as concordance of clinical information, treadmill ECG results, thallium data and the exercise echocardiogram. If there was any discrepancy among these tests, the patient was not included in the analysis. The sensitivity of exercise 2D digital echocardiography was comparable to stress thallium (0.86 vs 0.85) and was better than treadmill test alone (0.66). There were no false positive tests with echocardiographic study, while 1 false positive thallium examination was detected. The diagnostic accuracy of stress echocardiography was 0.90, stress thallium 0.85 and treadmill test only 0.75. In conclusion, exercise echocardiography appears to give results comparable to stress planar thallium studies. In addition, the ultrasonic procedure has several advantages: it is totally non-invasive, does not require a reperfusion study 4 hours later, avoids radiation and is less expensive.

Oxitropium bromide, a new anticholinergic bronchodilator

Oxitropium bromide (OB) is a quaternary ammonium congener of hyoscine with anticholinergic properties. We studied its bronchodilating properties in 14 patients with chronic obstructive lung disease without features of asthma in whom theophylline and other bronchodilators were withheld. Five doses of OB(20, 40, 100, 200, and 400 micrograms) as well as 150 micrograms of isoproterenol (ISO) and placebo were administered by metered-dose inhaler on separate occasions in a double-blind fashion. Pulmonary function (flow volume loops and airways resistance), blood pressure, and pulse rate were measured at baseline and periodically for eight hours after drug administration. Onset of bronchodilator effect was within five minutes for OB (P less than .025). Duration of action of OB was at least eight hours (P less than .025). The dose response characteristics of OB were examined by correlating the log dose with the areas under the time-FEV1 curve (r = .97, P less than .01), the time-forced vital capacity curve (r = .98, P less than .01), and the time-SGAW curve (r = .83, P less than 0.1). For FEV1, doses of 40 to 400 micrograms were significantly better than placebo and 100 to 400 micrograms were better than ISO (P less than .01). For forced vital capacity, all doses of OB were better than placebo (P less than .05). For SGAW, the response to the 100- and 400-micrograms doses were significantly better than placebo and isoproterenol (P less than .05). There were no significant effects of OB on pulse, blood pressure, or electrocardiogram. No side effects were noted from the use of OB.(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of survival in progressive systemic sclerosis by multivariate analysis of clinical features

The records of 64 patients with progressive systemic sclerosis (PSS) were reviewed. More than 100 items from the patient's history, physical examination, and laboratory tests were encoded. A two-tailed Gehan's test was used to evaluate the effect of each variable on patient survival. Variables significant at the 0.05 level were then analyzed simultaneously, using the Cox regression model, in order to determine which clinical features are most predictive of survival in PSS. By Cox regression, the presence of an S3 gallop and advanced age at onset of PSS related negatively to survival. The relative risk of death for a patient with an S3 gallop was 5.44 (ratio of risk) times that for a patient without an S3 gallop, and the risk of death for a 70-year-old patient at disease onset was 20 times that of a 20-year-old patient at disease onset. In addition, when patient selection was taken into account, corticosteroid administration had a significant effect, and seemed to actually shorten survival. Although one of the factors, age at onset, is not modifiable, the presence of either variable should alert the clinician to the patient being at high risk for short survival. The application of this technique should also prove helpful in analyzing the efficacy of various proposed therapies.

Effects of KCN and Salicylhydroxamic Acid on the Root Respiration of Pea Seedlings

Polarography, using cylindrical platinum electrodes, proved suitable for measuring changes in the internal apical O(2) concentration of the primary root of pea (Pisum sativum L. cv Meteor) effected by KCN and/or salicylhydroxamic acid (SHAM) in the bathing medium. An electrical rootaeration analog was used to help evaluate some of the results. Concentrations of KCN </=0.05 millimolar had no significant effect. In response to 0.1 millimolar KCN, the O(2) concentration rose substantially for approximately 2 hours, then declined, and after 10 hours had frequently fallen below the pretreatment level. Such changes suggest an initial inhibition of cytochrome oxidase-mediated O(2) uptake followed by an induction of the alternative, cyanide-resistant respiratory pathway. These treatments proved nonlethal. Changes in O(2) concentration similar to those described for 0.1 millimolar KCN were observed in response to 1 and 10 millimolar KCN but these treatments were lethal and the root apex became soft and often appeared flooded. Roots survived and showed no significant responses when treated with SHAM at concentrations </=5 millimolar. However, when the alternative pathway had been (apparently) induced by 0.1 millimolar KCN, the addition of 5 millimolar SHAM to the bathing medium caused a substantial and persistent rise in the root apical O(2) concentration, suggesting that this (nonlethal) concentration of SHAM could indeed inhibit O(2) uptake via the cyanide-resistant pathway.It is concluded that while O(2) uptake normally occurs by the cytochrome pathway in the primary pea root, the alternative, cyanide-resistant pathway can be induced by 0.1 millimolar KCN.

Organization of the facial nucleus in the rat

The topographic organization of the facial nucleus motoneurons in the rat was investigated with the horseradish peroxidase retrograde tracing method using tetramethyl benzidine as a chromogen. Facial muscles were 'represented' on the facial nucleus in an orderly fashion. For example, the motoneurons supplying the rostral (nasolabial) muscles are laterally placed, whereas those supplying the caudal (auricular) muscles are medially placed. Notable findings in this study are: (i) the relatively unremarkable size of the nasolabial (vibrissal) muscle representation; there does not seem to be an increase in size of this part of the nucleus, commensurate with the specialized sensory functions of the vibrissal area of the face and (ii) the neurons supplying the posterior belly of the digastric are found in the suprafacial nucleus which lies about 1 mm dorsal to the main facial nucleus.

Permeability of interstitial space of muscle (rat diaphragm) to solutes of different molecular weights

The transport characteristics of muscle interstitial space were determined using an isolated rat diaphragm preparation. Permeability of the interstitial space for extracellular solutes is one-thirtieth to one-fiftieth that of an equivalent thickness of water. However, most of this low permeability can be accounted for by correcting for the tortuosity and relative volume of interstitial space. The estimated diffusivity of solutes (mol. wt. 100-70,000) in the interstitial space of muscle is only about one-half to one-fifth less than in water alone.