Search PubMed⌕ Search

Biomedical subjects

G S Adams

Publications and source records attributed to G S Adams.

29 records · Page 2Linked to original sources

Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition.

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

Journal Article↗

Observation of exotic meson production in the reaction pi- p --> eta'pi- p at 18 GeV/c.

An amplitude analysis of an exclusive sample of 5765 events from the reaction pi- p-->eta'pi- p at 18 GeV/c is described. The eta'pi- production is dominated by natural parity exchange and by three partial waves: those with J(PC) = 1(-+), 2(++), and 4(++). A mass-dependent analysis of the partial-wave amplitudes indicates the production of the a2(1320) meson as well as the a4(2040) meson, observed for the first time decaying to eta'pi-. The dominant, exotic (non- qq) 1(-+) partial wave is shown to be resonant with a mass of 1.597+/-0.010(+0.045)(-0.010) GeV/c2 and a width of 0.340+/-0.040+/-0.050 GeV/c2. This exotic state, the pi1(1600), is produced with a t dependence which is different from that of the a2(1320) meson, indicating differences between the production mechanisms for the two states.

Journal Article↗

The ep -->e'p eta reaction at and above the S11(1535) baryon resonance.

New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

Journal Article↗

Phase II trial of interferon-alpha in locally recurrent or metastatic squamous cell carcinoma of the head and neck: immunological and clinical correlates.

The objective of this study was to study the antitumor, host toxicity, and immunomodulatory effects of recombinant interferon-alpha 2b (IFN) in patients with recurrent or metastatic squamous cell carcinoma of the head and neck (SCCHN). Seventy-one patients with recurrent or metastatic SCCHN were entered into a phase II noncomparative randomized trial of IFN at two dosage schedules. Eligible patients with histologically proven SCCHN were randomized to receive low-dose IFN, 6 x 10(6) U/m2 daily x 3 every 4 weeks or high-dose IFN, 12 x 10(6) U/m2, 3 x/week. Pretreatment levels of natural killer (NK) activity, CD3, CD4, CD5, CD8, CD16, CD19, CD56, DR, and the CD4/CD8 ratio were evaluated for any relationship with survival. The toxicity encountered in patients receiving low-dose IFN was for the most part mild to moderate. With high-dose IFN, toxicity was greater with significantly more episodes of grade 3 and 4 toxicity encountered. Dosage reduction was required in the majority of patients receiving high-dose IFN. Of the four lethal complications, only one was thought to be possibly associated with therapy. Of the 32 evaluable patients receiving low-dose IFN, there were 1 complete response, 1 stable disease, 24 patients with progressive disease, and 6 unevaluable. Of the 29 evaluable patients taking high-dose IFN, there were 2 complete responses, 7 with stable disease, 16 with progressive disease, and 4 patients were unevaluable. Median survival in the two arms was similar (6.2 months). Because it was postulated that a more prolonged exposure to IFN might be needed for it to be effective, patients receiving > or = 6 weeks of therapy were evaluated. Median survival in that subset was 10 and 12 months for patients receiving low- and high-dose IFN, respectively. None of the immune parameters tested was a significant predictor of survival when evaluated in all cases entered into study regardless of therapy duration. No difference in baseline NK activity was noted between patients who received < 6 or > or = 6 weeks of IFN (p = 0.90). However, among the 35 patients who received > or = 6 weeks of therapy, a high baseline NK activity was a significant predictor of the duration of survival (p = 0.04). IFN was well tolerated in patients with recurrent or metastatic SCCHN. The higher incidence of toxicity encountered in the high-dose arm could be ameliorated by reducing the dose 50%. In patients receiving 6 or more weeks of therapy, elevated baseline NK activity was associated with increases in survival, suggesting that IFN may play an immunomodulatory role. Although the overall response rates were low, disease stabilization was noted, suggesting an antiproliferative, noncytotoxic role of IFN in this group of heavily pretreated patients.

Adult↗

Utilization of mevalonate by aorta for the synthesis of medium-chain n-fatty acids (C8, C10) and acylglycerols.

[2-14C]Mevalonate was incorporated into acylglycerols by bovine aorta. The majority of the radioactivity was found in diacylglycerols. Hydrolysis, followed by analysis by thin-layer chromatography, paper chromatography, gas chromatography, and gas chromatography-mass spectrometry showed that the radioactivity was greatest in the medium-chain n-fatty acids, caprylic (C8) and capric (C10) acids. Triacylglycerols and diacylglycerols have important functions in the maintenance of the metabolic integrity of organs and their constituent cells. Therefore, medium-chain fatty acids may play significant roles, such as solubilization and transport of cholesterol and regulation of metabolism, as constituents of diacylglycerols. The results suggest that the trans-methylglutaconate shunt of mevalonate metabolism functions in the aorta.

Animals↗

In vivo right heart thrombus. Precursor of life-threatening pulmonary embolism.

This report describes three cases of massive mobile right heart thrombus and reviews the available literature to better define the pathophysiology, natural history and most appropriate therapy of the syndrome. The clinical presentation of most patients has been severe cardiopulmonary dysfunction and the diagnosis has been made by echocardiographic study. The most likely source of these cardiac thrombi is the large systemic veins. The associated mortality risk is very high. Therapy has, heretofore, been individualized. Embolectomy has been most favored, with a survival rate of 80 percent. The role of thrombolytic therapy remains to be delineated. Therapy should, however, be initiated rapidly because of the precipitous nature of the mortality risk.

Aged↗