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Biomedical subjects

M L Baker

Publications and source records attributed to M L Baker.

At least 55 records · Page 3Linked to original sources
PubMed1986

Angioscopically monitored saphenous vein valvulotomy.

Angioscopy was used during in situ saphenous vein bypass grafting in seven patients. We were able to visualize valve incision, immediately identify and correct incomplete valvulotomy, identify side branches as potential arteriovenous fistulas, and assess distal anastomotic integrity. We encountered no retained valve cusps after angioscopy, as verified by Doppler ultrasound and completion angiography. Angioscopy verified distal anastomotic integrity in all patients with distal vein grafts large enough to accept the angioscope. Angioscopy requires minimal time, is relatively easy to use, serves as an adjunct to Doppler ultrasound and completion angiography, and has future potential as a therapeutic tool.

Aged↗
PubMed1986

Laser angioplasty.

Explore the source record for details and available documents.

Arteriosclerosis↗
PubMed1985

Percutaneous angioscopy. Work in progress.

The cardiovascular applications of flexible fiber-optic technology are imminent because of recent advances in miniaturization. In the work described here, angioscopy, or vascular endoscopy, was performed in the cadaveric aorta and in the systemic and pulmonary circulations of the canine model and selected human patients. Subsequent to our development of percutaneous techniques, clinical trials have ranged from lower-extremity venoscopy to aortic-root arterioscopy. Angioscopy could be clinically useful because of relative or absolute contraindications to iodinated contrast material. The ability to see in color and three dimensions may afford some other advantages to angioscopy over conventional angiography.

Animals↗
PubMed1984

Anatomical studies of the spinocervical tract of the rat.

The retrograde transport of horseradish peroxidase (HRP) was used to identify and examine the cells of origin of the spinocervical tract (SCt) in the rat. Initially, precise data on the boundaries of the rat lateral cervical nucleus (LCn) were gathered after injecting HRP into the ventrobasal thalamus. These data indicated that the LCn of the rat is restricted to a region on the extreme lateral edge of the dorsalmost portion of the lateral funiculus (DLf) within spinal segment C2. Following small iontophoretic injections of HRP that were restricted to this area, labeled SCt neurons were found in the ipsilateral nucleus proprius at all levels of the spinal cord but were most numerous in the cervical enlargement. Lesion studies indicated that the overwhelming majority of SCt axons ascend to the LCn within the DLf. In an attempt to determine whether our injection techniques labeled a significant number of cells through axons of passage, HRP injections were made in the DLf ventral to the LCn. Such injections labeled, presumably through axons of passage, cells in several areas of the spinal cord gray matter, including a large number in the contralateral marginal zone. Injections in areas immediately rostral to the LCn labeled 20% or less of the total number of cells within the enlargements that were labeled by injections into the LCn. Thus, the majority of cells labeled by injections of HRP into the LCn were labeled through preterminal fibers or terminals themselves. The cells of origin of the SCt in the rat are similar in location to those in the cat but far fewer in number.

Animals↗
PubMed1983

Evaluation of radiation exposures to personnel in fluoroscopic X-ray facilities.

Personnel monitoring data reported in the literature at selected monitoring sites for personnel working in fluoroscopic X-ray facilities are analyzed. The results are used to attempt to more realistically estimate the potential organ doses for X-ray personnel wearing protective devices such as lead aprons and protective eyeglasses when these personnel wear only one dosimeter positioned outside the apron at the collar. The applicability of these results to current U.S. dose standards and the ICRP weighted dose equivalent concept is discussed.

Fluoroscopy↗
PubMed1981

Intraluminal pressure measurements during barium enema: full column vs. air contrast.

Intraluminal pressure measurements were made during enema examination of 10 patients undergoing full column studies and 10 patients receiving air-contrast studies. There was no significant difference between the pressure in the distal colon of the two groups. All pressures were less than those produced by Valsalva maneuver or straight leg raising, and were generally less than those previously found to be necessary to rupture the colon. The authors believe that the findings should dispel any fear that an air-contrast examination is more hazardous than a full column study. Perforations occurring during these procedures are more likely related to disease of the colon wall or local trauma.

Aged↗
PubMed1980

Effects of 5-thio-D-glucose on cellular adenosine triphosphate levels and deoxyribonucleic acid rejoining hy hypoxic and aerobic Chinese hamster cells.

Intracellular adenosine triphosphate (ATP) levels were measured in both hypoxic and aerobic cultures of V79 Chinese hamster cells treated with 5-thio-D-glucose (5-SH-D-Glc). This glucose analog, a known inhibitor of D-glucose transport and metabolism, reduced ATP in cell cultures allowed to become hypoxic by cell metabolism, but not in aerobic cultures treated similarly. Cells depleted of ATP were unable to rejoin x-ray-induced deoxyribonucleic acid (DNA) strand breaks as measured by the alkaline surcrose gradient sedimentation technique. Results show that 5-SH-D-Glc leads to reduced energy metabolism in cells dependent on glycolysis for ATP production. The inference for radiation therapy is that inhibition glucose metabolism selectively depletes energy reserves in hypoxic cells, rendering these cells more radiosensitive and leading to a more effective tumor treatment.

Adenosine Triphosphate↗
PubMed1978

Biological effects of diagnostic ultrasound: a review.

Biological effects from experimental ultrasound studies, such as chromosome aberrations and retardation of growth, have been recorded but mostly at levels far in excess of diagnostic intensity. The data surveyed in this review suggest that there is apparently little or no danger associated with diagnostic ultrasound exposure at clinical levels.

Animals↗
PubMed1976

Fast neutron and x-ray induced single strand DNA breaks in cultured mammalian cells.

The relative biologic effectiveness (RBE) of fast neutrons in the production of single strand DNA breaks is 1.6 as compared to that of 250 kVp x rays. Monolayers of L-929 cells were treated with dinitrophenol during irradiation to prevent the DNA strands from rejoining; the extent of DNA damage was measured by the alkaline sucrose sedimentation method. The RBE for DNA damage is essentially the same as the RBE measured by cell survival methods.

Animals↗
PubMed1976

A fast neutron source for cultured cell irradiation.

Because of recent interest in the use of neutrons for radiotherapy, there has been an increased interest in the radiology of neutrons. In this irradiated cell study, a 1.3 MeV accelerator produced beam currents over 100 muA on the water-cooled 3-mm thick beryllium disk target. The monolayer of irradiated cells was neutron-shielded by about 700 kg of paraffin. The neutron energy spectrum for the 9Be(d,n)10B reaction was obtained, with an average neutron energy calculated to be between 3.3 and 3.5 MeV, and an average linear energy transfer calculated at more than 30 keV/micron.

Cells, Cultured↗