John Klock

Dr. John Klock

orcid

Research Focus & Metrics

Academic Career Length

53Years (1974-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 1996 in Journal of Chromatography A
Verified
Journal Article
Closed access
CSChristopher M Starr
Christopher M Starr
RMR Irene Masada
R Irene Masada
CHChuck Hague
Chuck Hague
ESElisa Skop
Elisa Skop
JKJohn Klock
John Klock

1 February 1976 in Cancer
Verified
Journal Article
Closed access
PDF file
JKJohn Klock
John Klock
RORichard L. Oken
Richard L. Oken

1 January 1975 in Clinical Toxicology
Verified
Journal Article
Closed access
PDF file
JKJohn Klock
John Klock
UBUdo Boerner
Udo Boerner
CBCharles E. Becker
Charles E. Becker
(1975). Coma, Hyperthermia, and Bleeding Associated with Massive LSD Overdose a Report of Eight Cases. Clinical Toxicology: Vol. 8, No. 2, pp. 191-203. doi: 10.3109/15563657508988063


1 November 1977 in Journal of Clinical Investigation
Verified
Journal Article
Open access
PDF file
JKJohn Klock
John Klock
TSThomas P. Stossel
Thomas P. Stossel
Granulocytes collected by reversible adhesion to nylon wool fiber (NWF) function relatively well in standard in vitro tests; however, they have an abnormally shortened survival time in the circulation. Assuming that this rapid disappearance represents clearance and that recognition by phagocytes is important for such clearance, we used an autologous in vitro cell:cell recognition assay to determine whether phagocytes can detect cellular changes induced by exposure of normal granulocytes to NWF. Human granulocytes incubated with NWF 1 h at 37°C, eluted with 20% acid citrate dextrose plasma, and washed stimulated the hexose monophosphate shunt activity of normal granulocytes an average of twofold (193±40% of controls), indicating a recognition response. NWF-induced granulocyte recognition was not dependent on plasma factors or activated complement components but was dependent on the time that the granulocyte was on the NWF and was maximal by 60 min of exposure. After elution from NWF, granulocytes demonstrated resting glucose oxidation rates only slightly higher than normal; however, during the first 20 min of exposure to NWF, granulocytes increased their rate of 14CO2 production from [1-14C]glucose three- to five-fold. Therefore, experiments were performed to determine whether toxic oxygen metabolites produced by NWF-adherent cells might contribute to recognition. The results showed that (a) normal granulocytes exposed to NWF in the presence of scavengers of superoxide anion (superoxide dismutase) or free radicals (ascorbate, mannitol, or benzoate) and washed before assay did not stimulate glucose oxidation of indicator granulocytes; and (b) NWF granulocytes prepared from cells unable to generate high levels of toxic oxygen metabolites, i.e. cells prepared anaerobically or from a patient with chronic granulomatous disease, also failed to stimulate indicator granulocytes. Human granulocytes placed in contact with NWF show an oxidative burst and become recognizable to other phagocytes. Free radical scavengers are effective in minimizing this recognition conferred on NWF-procured granulocytes.

1 January 2013 in Proceedings of Meetings on Acoustics
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Conference Paper
Closed access
JWJames Wiskin
James Wiskin
DBDavid Borup
David Borup
SJSteven Johnson
Steven Johnson
MAMichael Andre
Michael Andre
JGJames Greenleaf
James Greenleaf
JKJohn Klock
John Klock
Research in quantitative whole breast ultrasound imaging has been developing rapidly. Recently we published results from 2D transmission inverse scattering algorithms, based on optimization, incorporating diffraction, refraction, and limited multiple scattering effects, using data collected from an early prototype, which showed the feasibility of high resolution quantitative imaging of the breast tissue speed and attenuation, and concomitant refraction corrected reflection imaging. However, artifact problems in speed and attenuation result from the 2D algorithms, and the data characteristics. The reflection algorithm uses the speed map to model refractive effects of rays, so these artifacts are unacceptable. The 3D inverse scattering algorithm presented here, using data from a new prototype, overcomes most of these artifacts. We then use a 3D refraction corrected 360 degree compounded reflection algorithm for high resolution speckle free reflection images. We discuss the transmission and reflection algorithms and the advanced scanner used to collect the data, as well as initial clinical results from the Mayo Clinic, Breast Cancer Imaging Center, Orange County, and the University California, San Diego. We show examples of fibroadenomas, calcifications, cancers (IDC), in dense, fatty and average breast tissue, and compare these with hand-held ultrasound, MRI and mammography, where available.