Direct Measurement of Resonances in

We have performed the first direct measurement of two resonances of the ^{7}Be(α,γ)^{11}C reaction with unknown strengths using an intense radioactive ^{7}Be beam and the DRAGON recoil separator. We report on the first measurement of the 1155 and 1110 keV resonance strengths of 1.73±0.25(stat)±0.40(syst) eV and 125_{-25}^{+27}(stat)±15(syst) meV, respectively. The present results have reduced the uncertainty in the ^{7}Be(α,γ)^{11}C reaction rate to ∼9.4%-10.7% over T=1.5-3 GK, which is relevant for nucleosynthesis in the neutrino-driven outflows of core-collapse supernovae (νp process). We find no effect of the new, constrained reaction rate on νp-process nucleosynthesis.

Radiative Capture on Nuclear Isomers: Direct Measurement of the

We present the first direct measurement of an astrophysical reaction using a radioactive beam of isomeric nuclei. In particular, we have measured the strength of the key 447-keV resonance in the ^{26m}Al(p,γ)^{27}Si reaction to be 432_{-226}^{+146} meV and find that this resonance dominates the thermally averaged reaction rate for temperatures between 0.3 and 2.5 GK. This work represents a critical development in resolving one of the longest standing issues in nuclear astrophysics research, relating to the measurement of proton capture reactions on excited quantum levels, and offers unique insight into the destruction of isomeric ^{26}Al in astrophysical plasmas.

Direct Measurement of the Key E_{c.m.}=456 keV Resonance in the Astrophysical

We have performed a direct measurement of the ^{19}Ne(p,γ)^{20}Na reaction in inverse kinematics using a beam of radioactive ^{19}Ne. The key astrophysical resonance in the ^{19}Ne+p system has been definitely measured for the first time at E_{c.m.}=456_{-2}^{+5} keV with an associated strength of 17_{-5}^{+7} meV. The present results are in agreement with resonance strength upper limits set by previous direct measurements, as well as resonance energies inferred from precision (^{3}He, t) charge exchange reactions. However, both the energy and strength of the 456 keV resonance disagree with a recent indirect study of the ^{19}Ne(d, n)^{20}Na reaction. In particular, the new ^{19}Ne(p,γ)^{20}Na reaction rate is found to be factors of ∼8 and ∼5 lower than the most recent evaluation over the temperature range of oxygen-neon novae and astrophysical x-ray bursts, respectively. Nevertheless, we find that the ^{19}Ne(p,γ)^{20}Na reaction is likely to proceed fast enough to significantly reduce the flux of ^{19}F in nova ejecta and does not create a bottleneck in the breakout from the hot CNO cycles into the rp process.

Direct Measurement of the Astrophysical

We have performed the first direct measurement of the ^{38}K(p,γ)^{39}Ca reaction using a beam of radioactive ^{38}K. A proposed ℓ=0 resonance in the ^{38}K+p system has been identified at 679(2) keV with an associated strength of 120_{-30}^{+50} meV. Upper limits of 1.16 (3.5) and 8.6 (26) meV at the 68% (95%) confidence level were also established for two further expected ℓ=0 resonances at 386 and 515 keV, respectively. The present results have reduced uncertainties in the ^{38}K(p,γ)^{39}Ca reaction rate at temperatures of 0.4 GK by more than 2 orders of magnitude and indicate that Ar and Ca may be ejected in observable quantities by oxygen-neon novae. However, based on the newly evaluated rate, the ^{38}K(p,γ)^{39}Ca path is unlikely to be responsible for the production of Ar and Ca in significantly enhanced quantities relative to solar abundances.

Measurement of radiative proton capture on 18F and implications for oxygen-neon novae.

The rate of the 18F(p,γ)19Ne reaction affects the final abundance of the γ-ray observable radioisotope 18F, produced in novae. However, no successful measurement of this reaction exists and the rate used is calculated from incomplete information on the contributing resonances. Of the two resonances thought to play a significant role, one has a radiative width estimated from the assumed analogue state in the mirror nucleus, 19F. The second does not have an analogue state assignment at all, resulting in an arbitrary radiative width being assumed. Here, we report the first successful direct measurement of the 18F(p,γ)^19Ne reaction. The strength of the 665 keV resonance (Ex=7.076 MeV) is found to be over an order of magnitude weaker than currently assumed in nova models. Reaction rate calculations show that this resonance therefore plays no significant role in the destruction of ^{18}F at any astrophysical energy.

Long-term randomized controlled trial of a novel nanopowder hemostatic agent (TC-325) for control of severe arterial upper gastrointestinal bleeding in a porcine model.

BACKGROUND AND STUDY AIM: Endoscopic therapy of brisk upper gastrointestinal bleeding remains challenging. A proprietary nanopowder (TC-325) has been proven to be effective in high pressure bleeding from external wounds. The efficacy and safety of TC-325 were assessed in a survival gastrointestinal bleeding animal model. METHOD: 10 animals were randomized to treatment or sham. All animals received intravenous antibiotics, H2-blockers and heparin (activated clotting time 2 × normal). In a sterile laparotomy the gastroepiploic vessels were dissected, inserted through a 1-cm gastrotomy, and freely exposed in the gastric lumen, and the exposed vessel lacerated by needle knife. The treatment group received TC-325 by a modified delivery catheter while the sham group received no endoscopic treatment. Time to hemostasis, and mortality at 60 minutes, 24 hours, 48 hours, and 7 days were noted. Necropsy was performed in all animals. RESULTS: Spurting arterial bleeding was achieved in all animals. No control animal showed hemostasis within the first hour compared with 100 % (5 / 5) in the treatment arm (mean 13.8 minutes, P < 0.0079). Durable hemostasis was achieved with no evidence of rebleeding after 1 and 24 hours in 80 % (4 / 5) of the treated animals compared with none in the control group ( P < 0.0098). None of the control animals survived more than 6 hours. Necropsy at 1 week in treated animals revealed healed gastrotomy without foreign body granuloma or embolization to the lung or brain. CONCLUSION: TC-325 is safe and highly effective in achieving hemostasis in an anticoagulated severe arterial gastrointestinal bleeding animal model.

Direct measurements of ²²Na(p,γ)²³Mg resonances and consequences for ²²Na production in classical novae.

The radionuclide 22Na is a potential astronomical observable that is expected to be produced in classical novae in quantities that depend on the thermonuclear rate of the 22Na(p,γ)23Mg reaction. We have measured the strengths of low-energy 22Na(p,γ)23Mg resonances directly and absolutely using a radioactive 22Na target. We find the strengths of resonances at Ep=213, 288, 454, and 610 keV to be higher than previous measurements by factors of 2.4-3.2, and we exclude important contributions to the rate from proposed resonances at Ep=198, 209, and 232 keV. The 22Na abundances expected in the ejecta of classical novae are reduced by a factor of ≈2.

Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction.

The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.

Measurement of the cascade transition via the first excited state of 16O in the 12C(alpha,gamma)16O reaction, and its S factor in stellar helium burning.

Radiative alpha-particle capture into the first excited, J(pi)=0+ state of 16O at 6.049 MeV excitation energy has rarely been discussed as contributing to the 12C(alpha,gamma)16O reaction cross section due to experimental difficulties in observing this transition. We report here measurements of this radiative capture in 12C(alpha,gamma)16O for center-of-mass energies of E=2.22 MeV to 5.42 MeV at the DRAGON recoil separator. To determine cross sections, the acceptance of the recoil separator has been simulated in GEANT as well as measured directly. The transition strength between resonances has been identified in R-matrix fits as resulting both from E2 contributions as well as E1 radiative capture. Details of the extrapolation of the total cross section to low energies are then discussed [S6.0(300)=25(-15)(+16) keV b] showing that this transition is likely the most important cascade contribution for 12C(alpha,gamma)16O.

Charge symmetry breaking in np-->dpi(0).

The forward-backward asymmetry in np-->dpi(0), which must be zero in the center-of-mass system if charge symmetry is respected, has been measured to be [17.2+/-8.0(stat)+/-5.5(syst)]x10(-4), at an incident neutron energy of 279.5 MeV. This observable is compared to recent chiral effective field theory calculations, with implications regarding the du quark mass difference.

21Na(p,gamma)22Mg reaction and oxygen-neon novae.

The 21Na(p,gamma)22Mg reaction is expected to play an important role in the nucleosynthesis of 22Na in oxygen-neon novae. The decay of 22Na leads to the emission of a characteristic 1.275 MeV gamma-ray line. This report provides the first direct measurement of the rate of this reaction using a radioactive 21Na beam, and discusses its astrophysical implications. The energy of the important state was measured to be E(c.m.)=205.7+/-0.5 keV with a resonance strength omegagamma=1.03+/-0.16(stat)+/-0.14(sys) meV.

Disposition, metabolism, and toxicity of methyl tertiary butyl ether, an oxygenate for reformulated gasoline.

Studies of the toxicology of methyl tertiary butyl ether (MTBE) were reviewed as a possible information base for evaluating the health effects of evaporative emissions from reformulated gasoline (RFG). The major metabolites of the oxidative demethylation of MTBE in vivo were methanol and tertiary butyl alcohol (TBA), whereas formaldehyde and TBA were the principal products of hepatic microsomal oxidation by cytochrome P-450. Pharmacokinetic studies in rats treated with intragastric MTBE in corn oil gave an initial disposition T1/2 for MTBE of 0.32 h. The decline in the serum drug versus time curve for MTBE in rats was accompanied by a progressive increase in serum methanol concentrations to levels more than 50-200 times those of the parent compound. Repeated exposure of MTBE vapor by inhalation in rats resulted in dose-dependent increases in MTBE in the blood, brain, and adipose tissue compartments. Blood concentrations of TBA were also dose dependent and provided an estimate of the total amount of MTBE distributed to peripheral drug metabolizing compartments. Perirenal fat/blood MTBE concentration ratios ranged from 9.7 to 11.6 after 15 wk of intermittent exposure. During an oxyfuels program in Fairbanks, AK, blood levels of occupationally exposed workers were 0.2-31.5 microgram/L MTBE and 1.6 to 72.2 microgram/L TBA with a mean TBA:MTBE blood concentration ratio of 4.2. In patients who received MTBE by percutaneous, transhepatic puncture for the dissolution of cholesterol gallstones, concentrations of MTBE in fat tissue reached 60 and 300 microgram/g at a treatment time when mean blood MTBE was less than 20 microgram/ml. The results of laboratory and clinical studies indicate that metabolites of MTBE may contribute to the nephropathy, neoplasms, and other pathological changes associated with repeated exposure to MTBE in experimental animals. It is concluded that such studies can provide a well-defined database for quantitative safety comparisons and health risk-benefit analyses of MTBE and other oxygenates in RFG.

A computer-based, problem-solving system of instruction in clinical pharmacology.

Advances in microcomputer technology provide new ways of incorporating PBL procedures in clinical pharmacology courses. Developments in graphics-user interfaces and analog/digital systems that display physiologic information directly on the monitor enable the computer to serve as a learning resource as laboratory classes did in the past. A model HyperCard-driven program describes four problem-oriented laboratory exercises that require interpretation and analysis of ECGs. The exercises that involve reading ECGs that were obtained before and after the onset of drug-induced changes in conduction and rhythm are designed to reinforce problem-solving skills in basic electrocardiography and give students a better understanding of the electrophysiologic basis for managing cardiac arrhythmias in clinical practice. For evaluating new programs in medical education, Schmidt describes three conditions that facilitate successful learning; (1) opportunity to use previously acquired knowledge in understanding new information, (2) applicability to future practice, and (3) ability to elaborate on the new information by interaction with other students. Advances that incorporate microcomputer technology and problem-solving learning would receive high scores by such criteria and are recommended by those who are developing courses in clinical pharmacology for medical students and others in the allied health sciences.

Changing patterns of ischaemic heart disease mortality in New Jersey 1968-1982, and the relationship with urbanization.

Geographical variations in the declining rates of ischaemic heart disease (IHD) mortality may provide clues about various environmental risk factors responsible as a mass influence on the population IHD rate. The rate of IHD decline in 18 of 21 NJ counties was 2 to 45% less than the USA national rate of decline. The overall decline of IHD mortality in New Jersey (NJ) counties lagged significantly (p less than 0.05 to p less than 0.0003) behind the national trend. Age-adjusted mortality rate (AAMR) for IHD in NJ's 21 counties were 4% to 56% higher than the US rates. The IHD mortality rate of 14 of 21 NJ, counties and the entire state were significantly (p less than 0.005 to p less than 0.000001) above the US rate. Highly urbanized, industrialized, and densely populated NJ counties had the highest IHD rates. In these highly urbanized, industrialized and overcrowded NJ counties the AAMR for IHD was significantly higher and the IHD decline was significantly lower than that in the US. There was a significant (p less than 0.02 to p less than 0.00001) inverse association between annual per capita income and IHD rates. These data suggest that a high degree of urbanization, extensive industrialization, high population density and low socioeconomic status were acting as mass influences on the NJ population IHD rate.

Lymphocytic (microscopic) colitis. Clinicopathologic study of 18 patients and comparison to collagenous colitis.

Lymphocytic colitis, formerly called microscopic colitis, is a clinicopathologic syndrome with chronic watery diarrhea and diffuse mucosal inflammatory changes with prominent intraepithelial lymphocytes. The 18 lymphocytic colitis patients studied presented with chronic watery diarrhea at a mean age of 53.8 +/- 17 years (+/- 1 SD). Roentgenographic, endoscopic, and culture data were not diagnostic. In patients tested, there was a high prevalence of arthritis (82%) and autoantibodies (50%) but no increase in frequency of histocompatibility antigens associated with well-defined autoimmune disease (DR3, B8). Lymphocytic colitis patients were compared to 21 patients with collagenous colitis. Similarities included age, symptomatology, and nondiagnostic radiographic and endoscopic studies. However, the sex distribution was statistically different, with an equal male-to-female ratio in lymphocytic colitis and female predominance (80%) in collagenous colitis. Other differences included dissimilar histocompatibility phenotypes and collagen band on biopsies of collagenous but not lymphocytic colitis. These findings suggest that lymphocytic and collagenous colitis may be related yet distinct disorders.

Effect of therapy on bleeding rates in gastrointestinal angiodysplasia.

Sixteen patients with gastrointestinal angiodysplasia requiring transfusion were treated with surgical resection, endoscopic electrocautery, or transfusion alone. Pre- and post-therapy transfusion requirements in each group were compared to gauge the efficacy of each therapy. No superiority of any treatment could be shown statistically. The majority of patients had multiple angiodysplastic lesions throughout the gastrointestinal tract, and, accordingly, complete resolution of bleeding after therapy occurred in fewer than one-half of the patients.

A decade of developments in diuretic drug therapy.

New diuretics introduced into clinical medicine during the past decade include potent new loop diuretics such as bumetanide and piretanide, the uricosuric indanyloxyacetic acid derivative indacrinone, and a new generation of sulfamoyl diuretics such as indapamide and xipamide, which are recommended primarily for the treatment of hypertension. Pharmacokinetic studies of individual diuretics have demonstrated that the diuretic and natriuretic responses to the newer agents generally follow the plasma drug concentration-time curves and urinary drug excretion rates. Therapeutic monitoring can therefore be achieved in most patients with edema or hypertension by close clinical observation and laboratory analysis of plasma electrolyte and creatinine concentrations and urinary electrolyte excretion rates. Interest in the mechanisms involved in the renal and extrarenal vascular actions of the newer diuretics has led to a better understanding of how changes in venous compliance, peripheral vascular resistance, and renal blood flow distribution may contribute to the overall therapeutic response to these agents, especially in patients with severe congestive heart failure, renal insufficiency with low glomerular filtration rates, and hypertension with cardiorenal complications. Adverse reactions to modern diuretics, which are mainly an extension of their renal pharmacodynamic effects, have proved to be minimal, provided that the dosage is adjusted to meet but not exceed individual patient requirements. However, the long-term consequences of prolonged periods of diuretic-induced alterations in plasma potassium levels, and metabolic effects that include elevated blood lipids, are still under investigation.

Diet and other risk factors for cancer of the pancreas.

The findings of a case - control study of cancer of the pancreas, which was conducted in the Baltimore metropolitan area, are reported. Two hundred one patients with pancreatic cancer were matched on age (+/- 5 years), race, and sex to hospital and non-hospital controls, the latter selected by random-digit-dialing (RDD). All subjects were interviewed regarding diet, beverage consumption, occupational and environmental exposures, and medical and surgical history. Significantly decreased risks were associated with consumption of raw fruits and vegetables and diet soda, and significantly increased risks were associated with consumption of white bread when cases were compared with hospital and RDD controls. A significantly reduced risk was associated with consumption of wine when cases were compared to RDD controls. Risk ratios for consumption of coffee were not significantly different from one, although there appeared to be a dose - response relationship in women. A moderate but statistically nonsignificant increase in relative odds was found for cigarette smoking, and cessation of smoking was associated with a marked reduction in risk. No significant associations were found with particular occupational exposures. Tonsillectomy was associated with a significantly reduced risk, a finding that has been observed for other cancers as well. The current evidence indicates that pancreatic cancer is likely to result from a complex interaction of factors and suggests that the study of its etiology requires a multidisciplinary approach involving both laboratory and epidemiologic components.

Endoscopic training in the academic GI program. Program Directors Workshop, March 29 and 30, 1984, Atlanta, Georgia. How the GI pathologist can interact best with the GI trainee.

Effective collaboration between endoscopists is essential if optimal results from gastrointestinal biopsy are to be achieved. Agreed upon ways to enhance communication should be established, such as special requisition forms and regular conferences to discuss biopsy findings. Endoscopists and pathologists should know about and feel free to discuss the other specialist's procedures and techniques. Furthermore, all procedures and techniques for obtaining, handling, and reaching diagnostic conclusions from biopsy specimens need to be carefully examined and optimized. Recommended approaches are presented.