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Biomedical subjects

D C Jackson

Publications and source records attributed to D C Jackson.

At least 163 records · Page 9Linked to original sources
PubMed1977

Late complications of abdominal aortic reconstructive surgery: roentgen evaluation.

During a 5-year period from 1969 to 1974, 53 (8.5%) of 631 patients developed late complications following abdominal aortic reconstructive surgery. Occlusion was the most frequent complication and occurred in 4%. Others included stenosis, false aneurysm, enteric fistula and infection. Late complications were demonstrated by roentgenographic methods. Angiography was the most valuable roentgen study. It is indicated in all patients suspected of having delayed complications except those with unstable life-threatening hemorrhage. Additional roentgenographic studies including the barium enema and barium meal may help make the diagnosis and exclude other entities. In any patient with an abdominal aortic graft and gastrointestinal bleeding, the diagnosis of an aorto-enteric fistula should be considered until otherwise proven.

Adult↗
PubMed1977

Temporal arteriography and immunofluorescence as diagnostic tools in temporal arteritis.

Nineteen patients with polymyalgia rheumatica and/or temporal arteritis were classified by degree of clinical and arteriographic abnormality, biopsy grade of arteriosclerosis, and giant cell arteritis (GCA). Temporal arteriograms were very sensitive in detecting abnormal arteries. However, the assumption of some previous studies, that certain angiographic abnormalities are synonymous with GCA, was not supported, since biopsies from distal sites in a Class I and a Class II arteriogram revealed only arteriosclerosis. Class III arteriograms correlated with proximal biopsies of GCA. Immunofluorescent staining was negative in all cases.

Aged↗
PubMed1976

Ventilation, gas exchange and metabolic scaling of a sea turtle.

Ventilation of green turtles (Chelonia mydas) was affected by the position in which the animal was placed: supine animals breathed slowly 0.07 breaths/min) and deeply (8.0 L/breath); prone animals breathed more rapidly (0.43 breaths/min) and more shallowly (3.5 L/breath). From the respiratory exchange ratio and other indicators it appears that green turtles hyperventilate during exercise and hypoventilate during recovery. O2 consumption of the resting sea turtle (0.024 L-kg-1-h-1) is similar to that of other large turtles. Maximal O2 consumption (0.25L-kg-1-h-1) is greater than that of other large turtles. Minimal O2 consumption scaled in proportion to the -0.17 power of the body mass of green turtles over the range of 0.030 to 141.5 kg. The maximal O2 consumption scaled in proportion to the -0.06 power of body mass for the same range of body masses.

Animals↗
PubMed1976

Cytotoxic T cells recognize very early, minor changes in ectromelia virus-infected target cells.

Target cells (P-815 mastocytoma cells) infected with ectromelia virus became susceptible to lysis by H-2 compatible specific effector T cells within one hour of exposure of the cells to virus. This is long before viral progeny are produced and shed from the cell. Polyacrylamide gel electrophoresis (PAGE) profiles of the plasma membranes from infected and uninfected P-815 cells pulsed with 35S-methionine for one or a few hours after infection with virus were very complex and showed no consistent differences. P-815 cells, infected with ectromelia virus in the presence of an inhibitor of protein synthesis, pactamycin, slowly became susceptible to cell mediate lysis when the pactamycin was removed. The number of polypeptide species synthesized under these conditions was reduced to only three, of molecular weights between 10,000-50,000 daltons. Specific, newly synthesized membrane components recognized by mouse convalescent sera were isolated by immune complexing and examined by PAGE. Six polypeptide bands were seen, the major one correlating with one observed in the pactamycin experiment. The results suggested that the convalescent serum recognized both viral and host cell coded antigens. The significance of these findings is discussed.

Animals↗
PubMed1976

Changes in the surface of virus-induced cells recognized by cytotoxic T cells. I. Minimal requirements for lysis of ectromelia-infected P-815 cells.

P-815 mastocytoma cells developed susceptibility to immune T-cell-mediated cytolysis shortly after infection by ectromelia virus. Intracellular viral replication and late protein synthesis seem to bu unnecessary events. Interference with early protein synthesis, however, inhibits the development of susceptibility to lysis. The important intracellular events necessary for subsequent cytolysis appear to occur within 1 hour of infection. Virus rendered non-infectious by ultraviolet irradiation but not by gamma irradiation is able to induce these changes. By determining the minimum and essential events of the infectious process which result in T-cell-mediated cytolysis, the task of establishing the molecular changes occurring in the target cell surface membrane necessary for immune T-cell recognition should be simplified.

Animals↗
PubMed1976

Changes in the surface of virus-infected cells recognized by cytotoxic T cells. II. A requirement for glycoprotein synthesis in virus-infected target cells.

Infection of cells with either ectromelia or lymphocytic choriomeningitis (LCM) virus in the presence of 2-deoxy-D-glucose (2-DOG) inhibited by up to 70% the extent to which the infected cells become susceptible to virus-specific cell-mediated lysis. The concentration of 2-DOG used had little effect on the extent of total protein synthesis (incorporation of [35S] methionine) but inhibited (up to 25%) glycoprotein synthesis, as measured by incorporation of [3H] fucose. This suggested that glycoprotein synthesis was a necessary event for infected cells to become susceptible to T-cell mediated lysis. The profiles (polyacrylamide gel electrophoresis) of newly synthesized, cellular glycoproteins from unifected and ectromelia-infected cells in the presence and absence of 2-DOG were compared and found to be very complex, with only minor changes. However, when convalescent serum from infected mice was used to isolate newly synthesized components from the cell surface shortly after infection, it showed four main species ranging in size from 25,000 to 70,000 daltons. 2-DOG inhibited production of these by 70%, thus corresponding to the biological data. The nature of the new glycoproteins seen in infected cells and whether they are in fact the structures recognized by effector T cells remain to be determined.

Antigens↗
PubMed1976

Importance of pulmonary ventilation in respiratory control in the bullfrog.

Pulmonary and cutaneous O2 consumption (Vo2) and CO2 production (Vco2) were measured simultaneously in bullfrogs Rana catesbeiana at 20 degrees C. The lungs were responsible for 77.3-91.0% of the total Vo2 and 28.5-74.9% of the total VCO2. The distribution of the total exchange between the lungs and skin depended on metabolic rate; frogs with higher rates relied more heavily on the pulmonary mode for both Vo2 and Vco2. When prevented from ventilating their lungs in an O2-rich environment, bullfrogs developed severe respiratory acidosis, demonstrating the importance of lung exchange in normal acid-base balance. When frogs were totally submerged in an O2-saturated medium, skin Vco2 increased linearly to a steady-state value which approximated the preapneic total Vco2. In these same animals, arterial Pco2 increased proportionately to the increase in skin Vco2, indicating that skin diffusion capacity for CO2 was unaffected. We conclude that the control of breathing in the bullfrog in response to changes in metabolic rate relies predominantly on changes in lung ventilation while the skin plays a more passive role.

Animals↗
PubMed1976

Effects of temperature transients on gas exchange and acid-base status of turtles.

Pulmonary ventilation (VE), O2 consumption (VO2), and CO2 production (VCO2) were measured continuously on each of 10 turtles, Pseudemys scripta elegans, at 20 degrees C, during and for 1 h after heating to 30 degrees C and during and for 1 h after cooling to 20 degrees C. In seven of the animals, arterial blood was sampled at the three temperature plateaus. Ventilatory ratios (VE/VO2 and VE/VCO2) and metabolic rate adjusted promptly to temperature change, stabilizing at values similar to those observed previously in turtles following 1 day or more at each temperature. Likewise, mean blood pH and PCO2 values conformed both in absolute values and in temperature-dependence to data previously obtained from animals exposed to the various temperatures for longer time periods or from turtle blood thermally equilibrated in vitro. Total plasma [CO2] did not change significantly, suggesting that steady-state CO2 exchange prevailed throughout the experiment. In accordance with this, R(VCO2/VO2) did not change significantly during the 20-30 degrees C transition; however, R rose during the 30-20 degrees C transition, suggesting possible hyperventilation at this stage. We conclude that the respiratory control of blood acid-base status adjusts rapidly to temperature change in the turtle and its adjustment minimizes disturbance to CO2 balance.

Acid-Base Equilibrium↗
PubMed1976

Angiographically induced renal failure and its radiographic detection.

Decreased renal function following arteriography is much more common than is currently realized. Steps to detect this failure are necessary, especially in high risk patients, so that stressful situations such as surgery can be avoided. A recently performed prospective random study of 100 patients undergoing angiography demonstrated a 10% incidence of renal failure. Those patients most at risk had preexisting renal disease as indicated by an elevated serum creatinine and/or cardiovascular disease severe enough to require digoxin, diuretics, or nitroglycerin. No cases of renal failure occurred in the absence of one or both of these processes. The likelihood of postangiographic renal failure was unrelated to the quantity of contrast as measured either by total volume or per kilogram body weight.

Acute Kidney Injury↗
PubMed1976

Aortoenteric and paraprosthetic-enteric fistulas: radiologic findings.

Ten cases of graft-intestinal fistulas occurred in 712 patients who had undergone abdominal aortic reconstructive surgery. Radiographic abnormalities were demonstrated in eight--three by conventional barium gastrointestinal examinations and five by angiography. A high index of suspicion of the condition and an aggressive radiologic workup are recommended.

Aged↗
PubMed1975

Experimental Closure of Arteriovenous Fistula by Transcatheter Electrocoagulation.

Introduction of a small electric current by way of a catheter-placed electrode can completely occlude experimentally produced arteriovenous fistula. The occlusion appears permanent and without morbidity in experimental animals. This technique might be clinically useful in obliterating an arteriovenous fistula and controlling gastrointestinal hemorrhage.

Angiography↗
PubMed1975

The current status of angiography in gastrointestinal bleeding.

Endoscopy, barium studies and angiography are all valuable diagnostic procedures in gastrointestinal bleeding. They are not mutually exclusive procedures but the correct sequence of investigation varies. Correct localization can be achieved in 84% of cases of massive gastrointestinal bleeding by their combined use. Vasoconstrictive therapy is also possible in severely ill patients and other poor surgical risk candidates.

Adult↗