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Biomedical subjects

G Johnson

Publications and source records attributed to G Johnson.

At least 541 records · Page 30Linked to original sources
PubMed1980

An analysis of "long-term" follow-up results in patients with cervical intraepithelial neoplasia treated by cryotherapy.

Two thousand eight hundred thirty-nine patients who had been treated by cryotherapy for cervical intraepithelial neoplasia (CIN) in nine different institutions were followed longitudinally after three negative Papanicolaou smears to ascertain the risk of recurrence. The cumulative risk of developing CIN after successful cryotherapeutic management of CIN was 0.41% at year 5, 0.44% at year 10, and 0.44% at year 14. There was no significant difference in risk between patients originally treated for CIN 1, CIN 2, or CIN 3.

Carcinoma↗
PubMed1980

In vivo n.m.r. imaging in medicine: the Aberdeen approach, both physical and biological.

A novel magnetic field and radio frequency (1.7 MHz) pulse sequence is described for a whole body n.m.r. imaging machine under construction. Selective excitation is used to obtain signals from successive lines of proton spins(water) across the body to build up an image of a transverse section. The images display spin concentration and spin-lattice relaxation time, T1, separately. For a 50% change in T1 to be discerned in the human trunk, a spatial resolution of 2 cm3 is expected for a 2 min scan and 0.5 cm3 for a 30 min scan. Very preliminary images at the present incomplete stage of development show the geometrical accuracy and T1 discrimination: an in vivo image demonstrates some of the difficulties to be overcome. In vitro measurements of normal rabbit tissue samples have been made at 24 MHz to map the T1 distributions that can be expected from normal subjects. The transposition of this information from rabbit to man, and from 24 MHz to 2.5 MHz have been checked and the comparison shown to be meaningful. Of pathological samples, human breast tumour and human liver metastases offer a good contrast to their surrounding tissue, and an experimental investigation has shown that tissue immediately surrounding a tumour also has an elevated T1 value. A wide range of abnormalities that are associated with abnormal fluid formation in the body may be amenable to imaging by the n.m.r. technique. Potential hazards are believed to be small in the present generation of equipment.

Animals↗
PubMed1980

Emergent or elective operation for symptomatic abdominal aortic aneurysm.

The patient with the symptomatic abdominal aortic aneurysm (AAA) presents a management dilemma, ie, emergent, urgent, or elective operation. The mortality for 38 patients with a ruptured AAA prior to 1972 was 61%. That year, a policy of immediate operation was instituted for patients with symptoms that might be referable to a ruptured AAA. It is concluded that an immediate operation on the patient with a symptomatic but intact AAA resulted in an excessively high mortality. Thus, the indications for an immediate operation on these patients should be based on clinical judgment; attempting to differentiate between the patient with the ruptured and the patient with the intact aneurysm. Hemodynamic data (blood pressure hematocrit reading) suggesting a decrease in blood volume dictate an immediate operation. An urgent operation on the well-prepared patient should be performed on all patients with a symptomatic aneurysm in which the clinical and hemodynamic findings do not suggest that it has ruptured.

Aged↗
PubMed1980

The occurrence of hyperaldosteronism in infants with congestive heart failure.

Serum aldosterone and plasma renin were measured in 20 normal infants and 15 infants with congestive cardiac failure. Serum aldosterone was significantly increased (151 +/- 38 ng/dl mean +/- standard error of the mean) in patients before treatment when compared with aldosterone in normal infants (29 +/- 7 ng/dl). Increasing serum aldosterone was related to increasing plasma renin. The response to furosemide appeared to be inversely related to serum aldosterone concentrations. In four infants, administration of an aldosterone antagonist (spironolactone) resulted in improved diuresis and decreased serum aldosterone. Hyperaldosteronism is an important factor contributing to fluid and sodium retention in infants with heart failure.

Aldosterone↗
PubMed1980

Graves' disease and HLA: clinical and epidemiologic associations.

Correlation between clinical and epidemiological features of Graves' disease and HLA were sought in 175 patients, eighty-three of whom were typed for HLA DR antigens. The relative risks (x) conferred by HLA-B8 and DR3 were 3.1 and 5.7 respectively (P less than 0.0005 uncorrected). The disease occurred at an earlier age in HLA-DR3 positive patients compared to negative patients (P less than 0.005 in females greater than and less than 30-years-old). Eighty-four out of ninety-two patients could specify the season of onset of hyperthyroidism; an excess of HLA-B8 positive patients in the summer and a lack of these in the spring and autumn was found. No association between B8 and exophthalmos and/or soft tissue eye changes were observed. However, significant associations between exophthalmos and either exophthalmos and/or soft tissue changes were found with DR3 (x = 3.6 and 3.8 respectively). HLA-DR3 positive patients were found to be more resistant to radioiodine therapy than patients negative for these antigens. No heterogeneity in the distribution of HLA antigens was found when the following indices were examined: sex, goitre size, severity of disease, pretibial myxoedema, antecedent psychological disorder, consumption of oral contraceptives, family history of Graves' disease or thyroid antibody titre. HLA does not appear to distinguish subvariants of Graves' disease, rather it influences the susceptibility to disease and its persistence once it becomes clinically manifest.

Adult↗
PubMed1980

Immunoglobulin concentration and Gm allotypes in a family with thirty-three cases of myotonic dystrophy.

Serum IgG, IgA, and IgM concentrations were measued in 120 members of a family with 33 cases of Dystrophia myotonica (Dm) and 27 members who were "possibly affected". The Dm individuals had significantly lower serum concentrations of IgG and IgA (P<0.01), while the "possibly affected" did not differ from the matched pair controls. IgG subclass concentrations were measured and GM and Am types determined. The lower concentration of IgA in the affected individuals was not associated with a particular Am type. The concentration of IgG3 was barely lower in the effected than in the controls (P=0.05), but there were no differences for IgG1. When IgG3 concentratin was compared according to Gm haplotype, only the two affected individuals who were Gm gg had a statistically significant lower concentration than the 12 controls (P<0.02). Thus, there is no evidence that a particular subclass of IgG is being hypercatabolized in our Dm patients. A rare Gm haplotype, Gm(-, n, b) had entered the family with two brothers; it is not known whether this codes for an IgG1-IgG3 hybrid molecule or a normal IgG1 molecule with an unknown Gm allele or a gamma 1 deleted Gm haplotype.

Adolescent↗
PubMed1980

Management of brachial artery occlusion after cardiac catheterization.

Our management of patients with suspected brachial artery injury following cardiac catheterization and the results of operative management in 42 patients are reported. From this review the following suggestions or conclusions are made: 1) The absence of a distal radial pulse or a 30-mm Hg difference in forearm pressures four hours after brachial artery catheterization is indicative of a pathologic occlusion at the site of catheterization. 2) Adequate anticoagulation with heparin should be used during the observation period. 3) When indicated, reexploration of the brachial artery should be performed in the operating room using local anesthesia. 4) Resection of a segment of injured brachial artery with an end-to-end anastomosis using interrupted sutures gives good results. Attempts at "plastic" repair without resection were ususlly accompanied by reobstruction. 5) Arterial pressures in both arms, as monitored with a Doppler instrument before and after exercise, were of value in evaluating these patients pre- and postoperatively. 6) No preoperative arteriograms were required. 7) Restoration of adequate circulation was achieved in 97 per cent of patients operated on for brachial artery injury within 24 hours of cardiac catheterization and using the techniques described. 8) The good operative results and low morbidity suggest early repair for all confirmed brachial artery injuries.

Arterial Occlusive Diseases↗
PubMed1979

The effect of copper on erythrocyte deformability: a possible mechanism of hemolysis in acute copper intoxication.

Although the development of hemolytic anemia as a complication of acute copper intoxication is well documented, the precise mechanism by which copper produces accelerated erythrocyte destruction is unknown. Normal erythrocyte survival depends in part on the ability of the cell to deform and pass through narrow areas of microcirculation in the liver and especially in the spleen. In the present study, it is demonstrated that toxic concentrations of copper rapidly and markedly reduce erythrocyte deformability. This reduction in cell deformability is associated with a marked increase in membrane permeability and osmotic fragility of copper-treated cells. Further, the decrease in deformability occurs despite normal levels of cell ATP and the apparent absence of oxidative damage to the cell. These observations indicate that copper-mediated changes in the erythrocyte membrane may be responsible for reducing the flexibility of the cell. The loss of deformability could act to reduce erythrocyte survival and thus explain the hemolysis associated with copper intoxication in vivo.

Anemia, Hemolytic↗
PubMed1979

Polyploidy, plants, and electrophoresis.

Investigations of polyploidy using electrophoresis are at present severely limited by several areas of difficulty which limit all applications of this technique. The technical problems inherent in electrophoresis of plants, namely extraction of active extracts and maximizing resolution of electrophoretic variants through investigation of gel and especially assay conditions, have never been addressed explicitly. No rationale for initiating work on a new species is available. Analytical approaches to defining the conditions which limit resolution are rare. Gel-to-gel variation is poorly controlled, seldom monitored. The individual nature of electrophoretic investigations limits the comparability of data among labs. In short, "hit-and-miss" approaches predominate, and these limit investigation. Techniques are now available which one can hope will greatly improve the experimental situation.

Animal Population Groups↗