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Biomedical subjects

G Jackson

Publications and source records attributed to G Jackson.

At least 217 records · Page 12Linked to original sources
PubMed1991

Raised exercise diastolic blood pressure as indicator of ischaemic left ventricular dysfunction.

91 (16.8%) of 541 consecutive patients investigated for chest pain or after recent uncomplicated myocardial infarction had a rise in diastolic blood pressure (DBP) of more than 15 mm Hg during a symptom-limited treadmill test. 63 also had electrocardiographic evidence of ischaemia, but 28 did not have 1 mm ST segment depression, of whom 24 had angiographic evidence of more than 70% stenosis of two or more major coronary arteries. 55 of these 91 patients underwent coronary artery bypass surgery; repeat angiography in 22 at 12 months showed an improved left ventricular ejection fraction in 18 who had a normal postoperative DBP response, but no change in ejection fraction in the 4 who still had an abnormal rise in DBP on exercise. Exercise-induced ischaemia may cause a reversible fall in cardiac output that sometimes leads to reflex vasoconstriction and a rise in DBP before a fall in systolic blood pressure or ECG evidence of ST segment depression. An abnormal DBP response to exercise may identify some patients at high risk of myocardial infarction who might otherwise have false-negative exercise tests.

Angioplasty, Balloon, Coronary↗
PubMed1991

Long-term results after lateral cranial base surgery.

The surgical management of patients with slow-growing benign temporal bone neoplasms has been criticized because of its significant morbidity and mortality compared with results after radiation therapy, but long-term control by irradiation remains unproved. Long-term surgical results have not been studied previously. One hundred twenty-nine skull base operations were performed in 126 patients at the Otology Group, Nashville, Tenn., from January 1970 through May 1987. Fifty-eight patients responded to questionnaires focusing on recovery from loss of cranial nerves. All patients regained some degree of facial function (class V or better), no alimentary tubes or tracheotomies were in use, and no patients had debilitating aspiration. Long-term compensation from the cranial nerve deficits of lateral skull base surgery can be expected in most patients and should not be used as an argument for irradiation in patients with a long life expectancy at time of diagnosis.

Adolescent↗
PubMed1991

A novel process for preparing an acellular pertussis vaccine composed of non-pyrogenic toxoids of pertussis toxin and filamentous hemagglutinin.

A novel process for preparing non-pyrogenic toxoids of pertussis toxin (PT) and filamentous hemagglutinin (FHA) is described. The process consists of chromatographies on perlite then on hydroxylapatite. Purification yields for PT and FHA are 62 and 68%, respectively. The purification process takes advantage of the novel use of perlite (a filter aid) for the simultaneous purification of PT and FHA. The hydroxylapatite, in addition to removing the remaining contaminants, also concentrates the antigens. The resulting PT and FHA are approximately 95% pure, and are non-pyrogenic as judged by the rabbit pyrogen test. The purification process is simple, inexpensive, and does not use blood components or toxic substances. The mild conditions in which the PT and FHA are purified ensure the recovery of native protein. The purified PT and FHA are detoxified in the presence of glycerol using glutaraldehyde and formaldehyde, respectively, to produce antigenic components of an acellular pertussis vaccine. The final PT and FHA toxoids are immunogenic in guinea-pigs and have been shown to be protective in the mouse intracerebral challenge test.

Bordetella pertussis↗
PubMed1991

The continuity equation tested in a bileaflet aortic prosthesis.

The continuity equation is valid for a population of aortic valves, but its accuracy in individual valves is uncertain. In bileaflet prostheses, obstruction to forward flow is small and individual variability in opening behaviour is minimal. In these valves, the area of the effective orifice should be close to that measured by the manufacturer. A total of 57 patients aged 58 +/- 11 years were studied at a mean of 3.6 months after implantation with a CarboMedics aortic prosthesis. Nine had additional implants in the mitral position and all prostheses were clinically normal. Peak subaortic and transaortic velocities were averaged over 5 beats. The area of the effective orifice was significantly different between the four diameters (P less than 0.00001), and the correlation between the effective and measured area of the orifice was moderate (rs = 0.73, P less than 0.00003). The 95% range for the differences between individual pairs of values, however, was 0.16 +/- 0.61 cm2. Discrepancies probably arose in the estimation of subaortic cross-sectional area and subaortic velocity. Thus, the continuity equation may be inaccurate in an individual prosthetic valve when functioning normally.

Aged↗
PubMed1991

The role of captopril as single therapy in hypertension and angina pectoris.

Eighteen hypertensive patients with a resting diastolic blood pressure between 100 and 120 mmHg who also had angina and proven coronary arterial disease entered a dose titration study to evaluate the efficacy of captopril as a single therapy in hypertension and coexisting stable angina. Captopril was administered for 2 weeks at 25 or 50 mg three times daily and the patients evaluated subjectively and by maximal symptom limited treadmill exercise testing. In comparison to placebo captopril 25 mg and 50 mg dosage increased time to 1 mm ST depression from 188.2 +/- 24.4 sec on placebo to 337.6 +/- 29.5 and 364.2 +/- 36.2 sec respectively (P less than 0.01). The maximum ST segment depression was reduced from 2.5 +/- 0.25 mm on placebo to 1.4 +/- 0.22 mm on captopril 25 mg and 1.2 +/- 0.30 mm on captopril 50 mg (P less than 0.01). Exercise duration increased from 310.3 +/- 21.4 sec on placebo to 438.3 +/- 27.3 sec on captopril 25 mg and to 460.9 +/- 26.5 sec on captopril 50 mg (P less than 0.01). The resting systolic blood pressure decreased from 184.1 +/- 4.7 mmHg on placebo to 159 +/- 4.2 mmHg on captopril 25 mg and to 150.9 +/- 4.6 mmHg on captopril 50 mg (less than 0.01). Similarly, diastolic blood pressure decreased from 111.6 +/- 2.1 mmHg on placebo to 93.8 +/- 1.3 mmHg on captopril 25 mg and to 90.0 +/- 1.7 mmHg on captopril 50 mg (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Acute and chronic effects of once-daily isosorbide-5-mononitrate on the exercise capacity of patients with angina pectoris treated with a beta-blocking drug.

Forty-four patients with stable effort angina pectoris were included in a double-blind, randomised, placebo-controlled, parallel group study to compare the effect of two slow-release forms of isosorbide-5-mononitrate ('Ismo-Retard' 40 mg and 'Imdur' 60 mg) on exercise capacity when given as an adjunctive treatment to beta adrenoreceptor blocking therapy. In a symptom-limited exercise test performed three hours after the first dose, Ismo-retard increased the total duration of exercise by 92 seconds (confidence interval (CI) 5.1-116.9) p less than 0.006, and the time of onset to anginal pain by 117 seconds (CI 27.8, 156.1) p less than 0.004. A similar improvement in total duration of exercise (by 87 seconds) was noted three hours following 15 consecutive once-daily doses (CI 16.8-128) p less than 0.02, and in the time of onset to anginal pain by 101 seconds (CI 19.8-139.6) p less than 0.01. For Imdur the corresponding results were 53 seconds (CI 12.7-56.3), 84 seconds (CI 15.4-103.7), p less than .02, 54 seconds (CI 1.4-78.4) and 85 seconds (CI 6.9-120.5) respectively. These results would suggest that both active treatments were effective anti-anginal agents.

Adrenergic beta-Antagonists↗
PubMed1991

Evaluation of a comprehensive algorithm for blunt and penetrating thoracic and abdominal trauma.

The objective was to develop a single branched-chain decision tree for both blunt and penetrating thoracic and abdominal trauma and to test its feasibility to track clinical decisions. The algorithm consisted of 14 specific patient management loops and 31 decision nodes. During a 4-month period, the management decisions and clinical course of 434 trauma patients were prospectively observed. Thirty-four patients had no signs of life on arrival to the emergency department (ED) and were excluded from the statistical evaluation; the remaining 400 patients constituted the study group. The mean Injury Severity Score (ISS), Penetrating Abdominal Trauma Index (PATI), and Trauma Score (TS) scores in the series were 21 +/- 10, 34 +/- 12, and 13 +/- 3. The overall patient mortality of the study group was 17 per cent; it was 61 per cent in those patients with major deviations from the algorithm and 6 per cent in patients who complied with the algorithm. The ISS, PATI, and TS scores were 29 +/- 9, 32 +/- 12, and 13 +/- 2 in patients with deviations and 20 +/- 10, 37 +/- 12, and 14 +/- 2 in patients who complied with the algorithm. Of the 37 patients who died with major deviations from the algorithm, the deviation was directly contributory to death in 21 cases (57%) and probably contributory in another 14 cases (38%). There were 108 patients with ISS scores between 20 and 50. In this group, mortality was 55 per cent when a major deviation occurred and 5 per cent without major deviations from the algorithm. The authors conclude that the survival of trauma patients may be improved by following the specific management criteria outlined by the algorithm.

Abdominal Injuries↗
PubMed1991

The relationship between ARDS, pulmonary infiltration, fluid balance, and hemodynamics in critically ill surgical patients.

Hypervolemia from fluid overload with resultant pulmonary edema is thought to be a frequent cause of Adult Respiratory Distress Syndrome (ARDS). However, ARDS may also occur as a result of the hypovolemic shock of surgery or trauma. To develop an appropriate rationale for fluid therapy in high-risk surgical patients, the relationship between fluid balance, hemodynamics, the onset of ARDS by physiologic criteria (shunt greater than or equal to 20%, and/or PaO2/FiO2 ratio less than 250) and the onset of pulmonary infiltration (PI) associated with ARDS were examined. Fifty patients were prospectively followed from admission throughout their hospitalizations; 38 (76%) had trauma and 12 (24%) were postoperative. Cardiac index, central venous pressure (CVP), wedge pressure (WP), and shunt (Qsp) were measured. All chest x rays were read by one staff radiologist who was blinded to the patients' identities. PI was graded from "0" to "4" (0 = no PI, 4 = maximum PI). The first x ray reading of "2" or greater was used as the time of onset of PI. ARDS by physiologic criteria occurred in 29 of 50 (58%) patients; 27 of these 29 (94%) also developed +2 or greater PI. The mean onset times of ARDS and of +2 PI were 40 +/- 41 hours and 40 +/- 38 hours, respectively. The ARDS patients had a significantly smaller net positive fluid balance than the non-ARDS patients over the first 40 hours after admission (+6,831 ml +/- 4,909 ml vs 12,440 ml +/- 7,817 ml, (P less than 0.01)).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Evaluation of a blunt and penetrating trauma algorithm for truncal injury.

The authors objective was to develop and test a single branch-chain decision tree for blunt and penetrating truncal injury. Over the 4-month study period there were 979 patients evaluated in the emergency department; 674 of these patients were admitted to the hospital. Thirty-four (5%) of the 674 admitted patients died of truncal injury. The study group consisted of 239 of the most severely injured patients; 41 of these (17%) died. Of the 44 patients managed with major deviations from the algorithm, 27 (61%) died. Only 14 of the 195 patients (7%) whose management complied with the algorithm died. The authors conclude that following the specific management criteria outlined by the algorithm may improve the survival of severely traumatized patients.

Abdominal Injuries↗