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Biomedical subjects

G A Miller

Publications and source records attributed to G A Miller.

At least 163 records · Page 9Linked to original sources
PubMed1983

Closed-system venography in the evaluation of angiodysplastic lesions of the extremities.

Closed-system venography is a minimally invasive, well tolerated method for diagnosing and delineating extremity angiodysplastic lesions. This method involves passive filling of the vascular tree after compressive exsanguination of an extremity and extrinsic occlusion of its arterial supply and venous drainage, thereby creating a static, closed system. Closed-system venography was done in 17 patients, where it correctly identified 11 of 12 surgically confirmed vascular abnormalities. There were no false-positive examinations. Whereas ateriography remains the examination of choice in studying arteriovenous malformations, closed-system venography has demonstrated a superior ability to diagnose and define lesions of capillary and venous origin.

Adolescent↗
PubMed1982

Ten-year experience of 359 epicardial pacemaker systems: complications and results.

In the last ten years (1970-1980) 457 patients underwent permanent pacemaker insertion in the Brompton Hospital. Our practice has been somewhat atypical in that the majority of these patients had epicardial leads, initially using a Cordis intramural sutured electrode (85 patients), and subsequently a Medtronic sutureless electrode (274 patients). Our initial experience with these electrodes was satisfactory, but more recently it has become apparent that the long-term morbidity and complication rate is high. The respective complication rates being 25% and 18% for sutured and sutureless epicardial electrodes. In this study, lead complications were defined as those requiring lead replacement, and problems most commonly encountered were high voltage threshold, infection, and lead fracture. Unless there are specific indications for epicardial pacing it is now our policy to treat patients requiring permanent pacing with endocardial systems. Our complication rate with this technique (90 patients) is significantly lower (9%).

Adolescent↗
PubMed1982

An evaluation of serum sources used in the separation of T- and B-lymphocytes by nylon-wool columns.

Gamma-globulin-free (GG-) newborn-calf, mouse and horse, as well as newborn-calf and calf serums were evaluated as substitutes for fetal bovine serum in the classical nylon-wool procedure used for the separation of T- and B-lymphocytes. The efficacy of the cell separation was evaluated by non-specific esterase staining and cytotoxicity tests for cell surface Thy 1.2 antigen and surface immunoglobulins. The results of these studies indicate that GG- newborn-calf, mouse and horse but not newborn-calf or calf serum could be substituted for fetal bovine serum. The results of these studies also indicate that the ratio of adherent to non-adherent cells is a useful indicator of the efficacy of the cell separation. A ratio of non-adherent to adherent less than 1.0 is indicative of a successful separation.

Animals↗
PubMed1982

Comparison of acridine orange, methylene blue, and Gram stains for blood cultures.

Direct microscopic screening of blood cultures by Gram stain or methylene blue stain is time consuming and frequently insensitive. Therefore, we evaluated a fluorescent-staining procedure that uses acridine orange (AO) at pH 3.5 and compared it with the methylene blue and Gram stain procedures. All smears were prepared within 24 h of receiving the culture, fixed with methanol, and examined without the results of the companion smears being known. AO-stained smears were examined with incident-light fluorescence at 600 x magnification and confirmed at 1,500x magnification. All bottles macroscopically positive within 24 h were excluded from the study. Of 2,946 cultures entered into the study, 204 (6.9%) were positive within 3 days. The sensitivity and specificity of AO based on these culture results were 52 and 98%, respectively, compared with 38% sensitivity and 99% specificity by methylene blue and Gram stains. The AO staining procedure is a simple, sensitive, screening technique for the early detection of positive blood cultures.

Acridine Orange↗
PubMed1982

The relationship between the strength of the human heart beat and the interval between beats.

In 15 patients undergoing cardiac catheterization and pacing tests, the left ventricular (LV) pressure and its maximum rate of rise (LV dP/dt max) were measured with catheter-tip manometers. Atrial or ventricular pacing at a single steady frequency (the priming frequency) was followed by a test pulse at a varying interval (test pulse interval). In 14 subjects in whom it was examined, the contractile response after the test pulse increased with test pulse interval to reach a maximum plateau value--the optimum contractile response (OCR). In five cases, further prolongation of the test pulse interval decreased the contractile response. The optimum test pulse interval occurred at 800-900 msec. An increase in the priming frequency before the introduction of the test pulse caused a progressive increase in OCR, in contrast to the minor effects on LV dP/dt max of the control beats. Similar results were recorded in four other patients in whom contractile response was assessed from the rate of rise of right ventricular pressure. These results indicate that with tachycardia, the interval between beats is insufficient to allow maximum contractile performance (presumed to be activated by calcium ions) to develop. The true effect of increasing heart rate is only revealed by the relationship between OCR and the preceding frequency of contraction.

Adult↗
PubMed1981

Percutaneous left ventricular angiography.

Recurrence of persistence of heart failure in patients after mitral and aortic valve replacement is a difficult diagnostic problem. Clinical evaluation and noninvasive tests cannot always distinguish poor left ventricular function from paraprosthetic leak or persistent pulmonary vascular disease. Full evaluation by cardiac catheterisation may then be necessary but is difficult because of the inaccessibility of the left ventricle. Under these circumstances, left ventriculography by direct transapical puncture is an alternative to crossing the prosthesis by a catheter and may be the only way of obtaining diagnostic information. We describe our experience of left ventriculography by percutaneous transapical passage of a flexible angiographic catheter (as distinct from a rigid angiographic needle) in 15 such patients (on 16 occasions). Non-fatal complications occurred in three patients. The information thus obtained allowed a clinical decision to be made and distinguished the inoperable from the operable group. Surgery was subsequently performed in seven patients with beneficial results.

Adult↗
PubMed1981

The maintenance of B-cell and T-cell function in frozen and stored human lymphocytes.

The objective of this study was to identify and test a convenient means for long-term storage of lymphocytes taken from clinically characterized patients without losing B- or T-cell function. Accordingly, peripheral blood lymphocytes were frozen and stored, and portions of each sample were subsequently assayed for T-cell blastogenic response and B-cell Jerne plaquing at various time intervals after freezing. A comparison of the cell counts of fresh and frozen cultures indicated that cell were recovered after freezing. Furthermore, these cells showed no significant differences in (i) cell viability; (ii) blastogenic response to antigens of Actinomyces maeslandii, Bacteroides melaninogenicus, Fusobacterium nucleatum, and tetanus toxoid; (iii) blastogenic response to phytohemagglutinin and pokeweed mitogen; and (iv) polyclonal B-cell response to pokeweed mitogen as measured by the direct Jerne plaque assay. The retained blastogenic and plaquing responses seen in frozen cultures indicated the maintenance of both T-cell and B-cell function, respectively. This is the first reported demonstration of Jerne plaquing of normal human lymphocytes after freezing. It appears that freezing techniques provide a means for repeating and extending both T- and B-cell assays using frozen stored portions of the same cell samples.

Antibody-Producing Cells↗
PubMed1981

Normal neutrophil function in human renal allograft recipients receiving Minnesota anti-lymphoblast globulin (MAG).

Equine anti-human lymphoblast globulin (MAG) used in combination with other immunosuppressive agents did not impair chemotaxis, phagocytosis, nitroblue tetrazolium (NBT) reduction or halogenation by peripheral blood neutrophils (PMN) from seven human recipients of cadaver renal allografts. MAG was given to the allograft recipients following transplantation, and the dosage was determined each day by quantitation of peripheral blood T and B lymphocytes. No deposition of immunoglobulin or complement on the recipient's PMN was detected by indirect immunofluorescence. Chemotaxis of PMN was determined in blind-well chambers, and phagocytosis of opsonized zymosan was quantitated by spectrophotometric measurement of solubilized formazan, and halogenation was measured by quantitating the incorporation of 125I into PMN that had phagocytosed opsonized zymosan. Chemotaxis, phagocytosis, NBT reduction, and halogenation by neutrophils from patients receiving MAG, prednisone and azathioprine were not impaired.

Adult↗
PubMed1981

Polyclonal B-cell activation induced by extracts of Gram-negative bacteria isolated from periodontally diseased sites.

The objective of this research was to determine whether gram-negative bacteria frequently isolated from periodontally diseased sites contained polyclonal B-cell activators. Polyclonal B-cell activation, which results in nonspecific activation of multiple B-cell clones was analyzed by a hemolysis-in-gel assay designed to detect a broad range of antibody specificities. Extracts from numerous bacterial strains, including Bacteroides gingivalis, Bacteroides melaninogenicus subsp. melaninogenicus, B. melaninogenicus subsp. intermedius, Fusobacterium nucleatum, Selenomonas sputigena, Capnocytophaga ochracea, and Actinobacillus actinomycetemcomitans, were tested. Extracts of the above organisms were found to stimulate polyclonal antibody responses in cultures of normal human peripheral blood lymphocytes, although the magnitude of stimulation varied among the extracts. Optimal antibody-forming cell responses were found at stimulator doses between 5 and 1,000 micrograms/ml. We conclude that the resident gram-negative subgingival flora associated with periodontal lesions possesses potent polyclonal B-cell activators. These activators may contribute to disease pathogenesis by inducing B lymphocytes to produce antibody, osteolytic factors, or both and possibly other mediators of inflammation.

Actinobacillus↗