Search PubMed⌕ Search

Biomedical subjects

H A Thomas

Publications and source records attributed to H A Thomas.

At least 37 records · Page 2Linked to original sources
PubMed1992

CT evidence for the "osseous pinch" mechanism of traumatic aortic injury.

OBJECTIVE: Our prior experiments suggested that traumatic laceration of the aorta induced by rapid deceleration results from pinching of the aorta between the spine and the anterior bony complex (manubrium, clavicle, and first rib). This study examines that hypothesis with in vivo CT data. MATERIALS AND METHODS: In 22 patients with angiographically and surgically proved lacerations of the proximal descending aorta, chest CT scans were obtained before (18) or after (four) surgical repair. The point of impact of the anterior bony complex with the anterior surface of the thoracic spine during compression of the thorax was predicted by simulated rotation of the first rib based on calculations made from the CT scans. RESULTS: In all 22 patients, the projected site of impact of the anterior bony complex with the spine corresponded to the actual injured aortic segment as determined with angiography. CONCLUSION: Our data further support the proposed "osseous pinch" mechanism of injury to explain traumatic tears of the aorta.

Aorta, Thoracic↗
PubMed1991

Regulation of Cl/HCO3 exchange in gastric parietal cells.

Microspectrofluorimetry of the fluorescent indicators 2',7'-bis-(2-carboxyethyl)-5(and-6)carboxyfluorescein and 6-methoxy-N-(3-sulfopropyl)-quinolinium was used to measure intracellular pH (pHi), intracellular Cl (Cli), and transmembrane fluxes of HCO3 and Cl in single parietal cells (PC) in isolated rabbit gastric glands incubated in HCO3/CO2-buffered solutions. Steady-state pHi was 7.2 in both resting (50 microM cimetidine) and stimulated (100 microM histamine) PCs. Transmembrane anion (HCO3 or Cl) flux rates during Cl removal from or readdition to the perfusate were the same in resting and stimulated PCs. These rates increased at alkaline pHi, though this pHi dependence was small in the physiological range. Maximum velocity (Vmax) for Cl influx or HCO3 efflux was 80-110 mM/min at pHi 7.6-7.8, and the Km for extracellular concentrations of Cl (Clo) was 25 mM; in the physiological range (pHi 7.1-7.3), Vmax for anion fluxes was approximately 50 mM/min. Steady-state Cli in the unstimulated PC was 62 +/- 5 mM, but on histamine stimulation, Cli decreased rapidly to 25 mM and then increased back to a steady-state level of 44 mM. HCO3 fluxes due to Cl removal or readdition were completely blocked by 0.5 mM 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid (H2DIDS), but Cl fluxes were only inhibited by 80%. H2DIDS did not inhibit the decrease in Cli that occurred with histamine treatment. Diphenylamine carboxylate (0.5 mM) inhibited Cl flux by only 50% and caused no additional inhibition of Cl flux when used in conjunction with H2DIDS. Transmembrane anion fluxes during solution Cl removal or readdition occurred 80% through the anion exchanger at the basal membrane and 20% through other pathway(s), presumably the Cl channel in the apical membrane. We conclude that the increase in transport activity via the Cl/HCO3 exchanger that occurs during histamine-induced increases in HCl secretion is due mostly to the decrease in Cli. In the resting cell with Cli = 62 mM, Clo = 120 mM, pHi = 7.2, and extracellular pH = 7.4, the anion exchanger is poised near its thermodynamic equilibrium. During histamine stimulation Cli drops from 62 mM to 44 mM, the thermodynamic equilibrium of the anion exchanger at the basolateral membrane is disturbed, and the anion exchanger then exchanges cellular HCO3 for extracellular Cl. Cli serves a crucial regulatory role in stimulus-secretion coupling in the PC.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1990

Factors influencing the treatment of intra-abdominal abscesses.

Forty-eight consecutive patients with 68 intra-abdominal abscesses who had operative or radiologic attempts at drainage were analyzed. Patients who had radiologic drainage were older and had simple abscesses more often. Simple abscesses were treated successfully in a high percentage of patients using both operation and radiologic drainage. Mortality was higher for patients with complex abscesses, and most of these patients required operative treatment. Successful abscess resolution was eventually achieved in 79 percent of patients.

Abdomen↗
PubMed1989

Identification of a 185-kDa band 3-related polypeptide in oxyntic cells.

Polyclonal antibodies to the purified mouse erythrocyte anion exchange protein (band 3) and to a conserved COOH-terminal peptide of mouse band 3 (alpha-Ct) recognized a single major 185-kDa polypeptide in immunoblots of a membrane fraction prepared from rabbit gastric glands. Competition studies revealed that the epitopes shared between the rabbit gastric 185-kDa antigen and the approximately 100-kDa mouse erythrocyte band 3 protein are restricted to the COOH-terminal domain of band 3, which is known to contain the catalytic site for anion exchange activity. Immunofluorescence microscopy was used to demonstrate that this band 3-related polypeptide is associated with the plasma membrane in a subpopulation of gastric gland cells composed exclusively of oxyntic cells, as judged by the coincidence of immunofluorescence with alpha-Ct and with a monoclonal antibody to the gastric H+-K+-ATPase. This alpha-Ct-reactive antigen was further localized to the cytoplasmic face of the basolateral membrane of oxyntic cells, which correlates well with the physiologically determined site of anion exchange activity. These data demonstrate the presence in gastric oxyntic cells of a novel member of the family of proteins related to the erythrocyte anion exchanger. The possibility that the 185-kDa polypeptide is an anion exchanger is discussed.

Adenosine Triphosphatases↗
PubMed1989

Role of CT in diagnosis of major arterial injury after blunt thoracic trauma.

The role of computed tomography (CT) in the diagnosis of blunt thoracic vascular injury is controversial. Several recent reports have advocated the use of CT to exclude aortic and major branch injuries in hemodynamically stable patients with blunt trauma. This approach potentially avoids invasive angiography and unnecessary treatment delays in multiply injured patients but risks missed aortic transections if the CT or its interpretation is not accurate. We prospectively evaluated 153 consecutive trauma patients in whom we suspected blunt aortic injury between September 1985 and August 1988. All hemodynamically stable patients underwent contrast-enhanced chest CT followed by immediate aortic arch angiography. Forty-nine unstable patients underwent immediate angiography without chest CT, and 11 (22%) had major thoracic arterial injuries. Data from the remaining 104 stable patients indicate that the sensitivity of chest CT for diagnosis of major thoracic injury is 55%; specificity, 65%. If the chest CT had been used as a screening modality to perform aortic angiography, two transected aortas and three major aortic branch injuries would have been missed. We conclude that chest CT has no screening role in the evaluation of blunt trauma patients with possible major vascular injury.

Adolescent↗
PubMed1987

Selective hepatic arterial embolization as an adjunct to hepatic resection.

We have presented a case in which the arterial supply to the proposed area of hepatic resection was angiographically embolized. Operative blood loss was only 600 ml, in comparison to mean blood loss in reported series of major hepatic resections as high as 2,500 ml. Further trials of this technique in larger numbers of patients seem to be indicated.

Adult↗
PubMed1985

Annular pancreas.

Explore the source record for details and available documents.

Adolescent↗
PubMed1984

Some uncommon lower mediastinal densities: a pictorial essay.

Despite CT and NMR, plain radiography still plays a major role in the diagnosis of mediastinal disease. In this article, the value and limitations of conventional techniques in the diagnosis of some unusual lesions of the lower mediastinum are demonstrated.

Adult↗
PubMed1982

Mechanism of vertebral fracture in the F/FB-111 ejection experience.

A review of the accident investigation reports of all non-fatal F/FB-111 ejections which occurred from 19 October 1967 to 26 March 1980 was conducted. The available spinal radiographs of the ejectees were also reviewed. The overall rate of vertebral compression fractures among the survived ejectees in a properly functioning module is 29.5% (23 of 78). The general mechanism of vertebral injury is a combined mechanism involving both axial compression and flexion. There is no evidence to indicate a hyperextension injury mechanism during retraction, nor is there evidence to support the presumed efficacy of the crossed-arms bracing procedure recommended for landing impact in modifying the vertebral injury rate. It appears that a significant reduction in the rate of vertebral fractures among F/FB-111 ejectees will require decreasing the acceleration stresses imposed on the crewmembers during landing impact.

Acceleration↗