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Biomedical subjects

M Pittman

Publications and source records attributed to M Pittman.

At least 19 recordsLinked to original sources
PubMed2002

Deuterium-deuterium fusion dynamics in low-density molecular-cluster jets irradiated by intense ultrafast laser pulses.

Following the interaction of superintense, short pulse lasers and plasmas, ions can be accelerated to velocities sufficient to drive nuclear fusion reactions, in particular, by the process of Coulomb explosion of clusters [T. Ditmire, Nature (London) 398, 491 (1999)]]. We show here how short bursts of neutrons can be produced using a jet of low-density deuterated methane clusters. Ion velocity distributions were simultaneously measured by a Thomson parabola mass spectrometer, demonstrating deuteron energies up to 120 keV. We show that, in such conditions, nuclear fusion will occur not only in the hot plasma core, but also in the cold outer region by collision processes.

Journal Article↗
PubMed2001

Saturated amplification of a collisionally pumped optical-field-ionization soft X-ray laser at 41.8 nm.

We report the first saturated amplification of an optical-field-ionization soft x-ray laser. The amplifying medium is generated by focusing a circularly polarized 330-mJ, 35-fs, 10-Hz Ti:sapphire laser system in a few-mm cell filled with xenon. A gain of 67 cm(-1) on the 4d(9)5p-4d(9)5d transition at 41.8 nm in Pd-like xenon and a gain-length product of 15 have been inferred at saturation. This source delivers about 5 x 10(9) photons per pulse. The influence of the pumping energy and the laser polarization on the lasing output are also presented.

Journal Article↗
PubMed1994

CEO summit. Building the new health care delivery alliance, Part III. Roundtable discussion.

In cooperation with McManis Associates, Hospitals & Health Networks recently convened a CEO summit on physician/hospital integration activities. In the third report of a three-part series on the summit, leading health care executives discuss investor capital needs, strategic information management needs, and the management competencies required for capitated managed care success.

Comprehensive Health Care↗
PubMed1994

CEO Summit. Building the new health care delivery alliance, Part II. Roundtable discussion.

In cooperation with McManis Associates, Hospitals & Health Networks recently convened a CEO summit on physician/hospital integration activities. The summit was designed and facilitated by the senior staff of McManis Associates. Part I, which appeared in the May 5 issue, focused on the lessons being learned by those providers on the front lines of integration. This report focuses on aligning incentives and achieving cost-effectiveness.

Chief Executive Officers, Hospital↗
PubMed1994

Voices of reform. The AHA: policy, advocacy and the tools for reform.

In three thoughtful essays, with an introduction by president Dick Davidson, executives at the AHA discuss the policy and political aspects of the reform process, and the organization's reform vision, including the development of tools for its membership.

American Hospital Association↗
PubMed1993

Primum non nocere: a pharmacologically inert pertussis toxoid alone should be the next pertussis vaccine.

The objective of a vaccine for pertussis is to prevent the paroxysmal cough with its complications. Prevention of the paroxysmal cough should prevent transmission of B. pertussis. Clinical studies indicate that a critical level of antitoxin confers protection against pertussis and that the long-lived protective immunity that follows pertussis is best explained by the presence of antitoxin. Vaccine-induced protective immunity can be mediated by a critical level of antitoxin alone. In addition to preventing pertussis with vaccines, we predict this level of antitoxin will also exert epidemiologic control (herd immunity) by inhibition of colonization with B. pertussis and by prevention of the paroxysmal cough which will reduce transmission of this pathogen. Lastly, a pertussis toxoid need not have detectable pharmacologic activity to exert its protective actions: residual activity could exert a deleterious effect on glucose metabolism and exert immunomodulating effects. Accordingly the new pertussis vaccine should contain inactivated pertussis toxoid alone and there is no need to include other components. Several candidates could serve as a satisfactory pertussis toxoid. The admonition to physicians given by Hippocrates, Primum non nocere (first of all do no harm), should be heeded by those responsible for the development and use of the new pertussis vaccine.

Adult↗
PubMed1991

History of the development of pertussis vaccine.

Bordetella pertussis and the disease whooping cough have mysterious unique features among bacterial infectious diseases. Numerous studies gradually provided information that permitted the development of a pertussis vaccine and the assessment of its potency relative to human efficacy. The advances in the understanding of B. pertussis, its pathogenicity and immunity that led to the development of a pertussis vaccine are presented.

Animals↗
PubMed1986

Neurotoxicity of Bordetella pertussis.

Pertussis is a unique disease in which the harmful effects are mediated by an exotoxin that effects stimulation of the adrenergic system which is neuronally controlled. The interdependence of the growth of bacteria and toxin production, and the local colonization of the bacteria that precedes the clinical symptom of the disease reflect the nature of the disease. Pertussis toxin enzymatically alters the function of numerous regulatory cells that is demonstrable, after an interval of time, by a specific stimulus. The toxin also may act rapidly and effect action at a target tissue. The latter appears to be associated with the rapid adverse events after vaccination whereas both may occur in the disease. The pathophysiologic responses associated with specific clinical symptoms have not been clearly defined. Responses to be evaluated relative to encephalopathy are increased vascular permeability, hypoglycemia and enhanced activity of neuronal glutamate and aspartate. The intensity of responses is related to the amount of pertussis toxin available, genetic susceptibility, ethnic and allotype, and external factors. The reason for the non-linear dose response shown by the critical level between the sublethal and the lethal infection in mice is unclear. Bacterial adenylate cyclase may be a candidate. Much remains to be elucidated about the enzymatic pathways that effect the many disparate events, the identity of the neurons that effect the clinical symptoms and their CNS location, the identity of the neuronal transmitters and the pathoneuronal pharmacodynamics.

Adenylate Cyclase Toxin↗
PubMed1982

Mitral and aortic valve orifice area in normal subjects and in patients with congestive cardiomyopathy: determination by two dimensional echocardiography.

Previous determinations of normal valve orifice areas have been mainly from postmortem studies. In this study mitral and aortic valve orifice area were determined from two dimensional echocardiograms in 20 normal subjects and 20 patients with congestive cardiomyopathy. Mitral valve orifice area was larger than quoted in standard textbooks. Both mitral and aortic valve orifice area were reduced in patients with cardiomyopathy. Valve opening was assessed relative to left ventricular and aortic root size. The ratio of mitral valve orifice area to left ventricular cross-sectional area was markedly reduced in patients with cardiomyopathy compared with normal subjects. The ratio of aortic valve orifice area to aortic root size also was reduced in patients with cardiomyopathy. Anterior mitral leaflet E point-septal separation was similar to that in previous reports contrasting normal subjects with patients with myopathy. Among patients with cardiomyopathy, mitral E point-septal separation was primarily a function of left ventricular size and was not significantly correlated with fractional shortening or ejection fraction within this group having uniformly poor systolic function.

Adolescent↗
PubMed1980

Bordetella pertussis respiratory tract infection in the mouse: pathophysiological responses.

The influence of living Bordetella pertussis on the induction and duration of pathophysiological reactions in mice infected intranasally with graded doses of culture was studied. Lethally infected mice showed loss of body weight, spleen atrophy, pronounced hypothermia and hypoglycemia, and highly elevated levels of leukocytes and serum immunoreactive insulin. Sublethally infected mice showed normal weight gain, practically normal temperature, spleen enlargement, lesser pronounced hypoglycemia, lower but significantly elevated levels of leukocytes and serum immunoreactive insulin, and histamine sensitization. Intensity of each reaction was related to the degree of lung infectivity. Hypothermia and leukocytosis were highly correlated. Concentration of serum immunoreactive insulin was closely related to the level of leukocytosis but not to the level of glucose. The strain and age of mice significantly affected the degree and duration of the reactions. The results suggest that the intranasally infected mouse may provide a useful model for investigations on whooping cough.

Aging↗