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Biomedical subjects

J C Norman

Publications and source records attributed to J C Norman.

At least 19 recordsLinked to original sources
PubMed1991

Laser assisted balloon angioplasty in peripheral vascular surgery: a preliminary report.

Laser/balloon thermal angioplasty has proven to be a valuable adjunct in our management of peripheral vascular disease. The initial trials have produced a 77% success rate, a 3% incidence of complications, and no morbidity. Patient acceptance has been high and the return to prior activities in less than 1 week is an appreciated advantage. Laser/balloon angioplasty expands the armamentarium of the vascular surgeon and makes possible broader applications of standard vascular surgical techniques.

Aged↗
PubMed1991

A unique inlet [the ascending aorta] for extra-anatomic bypass of infected arterial prostheses.

Infection is the most dreaded complication associated with implantation of a prosthetic arterial graft. The reported incidence of primary graft infection varies from 1.3% to 6.0%, with a mortality rate from this complication as high as 75%. Although remote bypass followed by complete removal of the infected prosthesis has proven to be a satisfactory method of treatment, in certain instances remote bypass alone is not feasible and other modes of surgical treatment must be employed. Such conservative methods of management of infected aorto-iliac-femoral prosthesis sometimes irradicate infection. The only certain cure, however, is obtained by totally removing the graft. And the success of extra-anatomic axillofemoral techniques has led to its extended use. The addition of a cross-limb on an axillo-unilateral femoral graft to form an axillobilateral femoral graft was described by Sauvage and Wood, reasoning that the higher flow rate in the axillary limb of the axillobilateral femoral graft would result in an improved patency rate compared with that of axillounilateral femoral grafts. Additionally, both medial (obturator foramen) and lateral extra-anatomic remote bypass of infected femoral prosthesis have been used, successfully. The current case illustrates the complexity of management, once sepsis occurs. It further focuses on groin, retroperitoneal and bilateral axillo-femoral tract infection with prolonged (apparently innocuous) graft exposure and finally points out the utility of the ascending aorta as an alternative extra-anatomic inlet to perfuse the lower extremities.

Aged↗
PubMed1991

Acute mycotic aneurysm of the ascending aorta following aortocoronary bypass: successful repair.

Acute mycotic aneurysms of the ascending aorta following aortocoronary bypass are exceedingly rare. To our knowledge, there have been few reports of successful management. The central location of this lesion places it apart from acute or chronic mycotic aneurysms in general and enhances its lethality. The availability of ascending and arch aortography, computerized chest tomography and the techniques of peripheral cardiopulmonary bypass, deep hypothermia and reversible circulatory arrest for prolonged periods of time permit successful management. The purpose of this report is to (1) illustrate such a problem; (2) describe its successful management; (3) review the etiology of mycotic aneurysms, historically and contemporarily; and (4) to differentiate early, acute mycotic aneurysms of the ascending aorta following aortocoronary bypass (usually lethal) from similar late chronic processes (readily reparable).

Acute Disease↗
PubMed1990

A new radioimmunoassay for the thymic peptide thymulin, and its application for measuring thymulin in blood samples.

A new, specific and sensitive radioimmunoassay, using a polyclonal antiserum raised in rabbits, is described for quantitating plasma thymulin. As little as 300 fg thymulin can be measured in one assay tube. The method has been used to measure thymulin in human blood (umbilical vessel blood, 2191 +/- 123 fg/ml; children and adults up to the age of 20 years, 1499 +/- 119 fg/ml; and adults between 21-65 years, 371 +/- 18 fg/ml). There is a highly significant decrease within these three groups (P less than 0.001 by one way analysis of variance). Also plasma thymulin levels were determined in rats (601 +/- 127 fg/ml) and in pooled plasma samples from mice (638 +/- 56 fg/ml). No thymulin was detected in plasma obtained from nude rats, nude mice and thymectomised mice. These results show that the radioimmunoassay described here is a useful quantitative tool for measuring plasma thymulin that will have applications in basic, applied and clinical research.

Animals↗
PubMed1988

Relationships between polyamine, deoxyribonucleic acid and oestrogen receptor binding site concentrations in human breast tumours.

Concentrations of polyamines, DNA and oestrogen receptor (ER) binding sites have been estimated in 23 malignant and 2 benign breast tumours. Polyamine and DNA concentrations, expressed per unit wet weight of tissue, were significantly higher in ER-poor (less than 10 fmol/mg cytosol protein) than in ER-rich tumours. Spermidine/spermine ratios were similar in ER-poor and ER-rich tumours. There was a relationship between polyamine and DNA levels and when polyamine concentrations were expressed per unit weight of DNA those in ER-poor tumours did not differ from those in ER-rich tumours. Possible reasons for these findings are discussed.

Breast Neoplasms↗
PubMed1985

Pleuropulmonary and skeletal lymphangiomatosis with chylothorax and chylopericardium.

Congenital lymphangiomatosis of lung and bone, with or without chylothorax, is a rare but often fatal systemic lymphatic malformation. In those who survive infancy and early childhood, parietal pleurectomy with excision of lymphatic lakes and ligation of the thoracic duct can be successful. Two patients with lymphangiomatosis are described, 1 with chylothorax and chylopericardium with generalized skeletal lesions and the other with pleuropulmonary lesions and chylothorax. Both were successfully treated with parietal pleurectomy, excision of lymphatic lakes, and ligation of lymphatics, including the thoracic duct. To our knowledge, the triad of generalized skeletal lymphangiomatosis, chylopericardium, and chylothorax has not been previously reported.

Adolescent↗
PubMed1985

Mechanical circulatory assistance: established (IABP) and evolving (LVAD). A narrative summary.

Comparisons of the physiologic bases of intraaortic balloon and extracorporeal or implantable left ventricular assist device or partial artificial heart pumping in experimental and clinical setting are made. The concepts and first principles common and unique to both of these forms of mechanical circulatory support are presented with emphasis on the similarities and important differences. Intraaortic balloon counterpulsation is examined as an intravascular, volume displacement device in series with the systemic circulations. Left ventricular assist devices are analyzed as extravascular in-series or parallel volume-capturing/ejecting devices and as true blood pumps which can be implanted. The interrelated mechanisms of synchronous, diversion/counterpulsation/diastolic augmentation are discussed in relation to quantitative indices of myocardial ischemia, myocardial oxygen supply/demand ratios, the Sarnoff theorem and the Laplace relationship, vis à vis ventricular unloading/impedance reductions. Some of the many clinical settings of IABP are mentioned, along with hydraulic considerations which allow non-invasive determination of stroke volume during clinical IABP mechanical circulatory support. Cardiogenic shock/left ventricular failure/low cardiac output are defined in terms of failure to generate pressure and displace volume and deficits of ejection fraction and stroke volume. Vasodilator therapy (nitroprusside), IABP, and LVAD are then viewed as escalating methods of reversing these deficits. Finally, pressure volume loops of the human left ventricle are compared with those of LVADs, experimentally and clinically, to indicate that LVADs can function and support the circulation during all low output states including ventricular fibrillation and standstill. Representative hemodynamic traces (Fig. 5 and 6) obtained during clinical LVAD trials in man are included to illustrate these theoretical and practical considerations. The use of LVADs in any instance of IABP inadequacy is implicit and inferred.

Assisted Circulation↗
PubMed1979

Comparative study of erythromycin, amoxicillin and ampicillin antimicrobial activity against human respiratory tract pathogens.

An in vitro test system was used to compare the antimicrobial activity of erythromycin, amoxicillin and ampicillin against respiratory tract pathogens isolated from man. The minimum inhibitory concentrations (MICs) of fresh clinical isolates of Streptoccus pyogenes, Streptocuccus pneumoniae, Staphylococcus aureus and Haemophilus influenzae to the macrolide and penicillins ranged between 0.01 and 0.9 microgram/ml. The microbes were exposed to each antibiotic for approximately 3 h at 1x,2x and 5x the relevant MIC. Irreversible surface defects and intracellular lesions were resolved by scanning and transmission electron microscopy in all antibiotic-treated bacterial species, irrespective of the antimicrobial used. In each case, inhibition of growth was recorded by turbometric assay; no significant difference was observed among the declining slopes of post-dosing growth curves for either erythromycin-, amoxicillin- or ampicillin-treated pathogens. The experimental observations show that the onset of antimicrobial activity and the bactericidal effectiveness of equipotent concentrations of erythromycin, amoxicillin and ampicillin were comparable in this study. The results complement previous clinical, bacteriologic and ultrastructure studies in vivo and demonstrate the contribution of the combined in vivo/in vitro study design for better understanding of antimicrobial activity in human respiratory tract infections.

Amoxicillin↗
PubMed1979

Efficacy of nitroprusside therapy in postcardiotomy low-output syndrome necessitating intra-aortic balloon counterpulsation.

Serial hemodynamic measurements were obtained before, during, and after nitroprusside therapy over a 24 hour period in 19 patients requiring intra-aortic balloon pumping (IABP) for successful weaning from cardiopulmonary bypass. Nitroprusside, administered in doses ranging from 0.5 to 5 micrograms/kg/min, effected significant reductions in mean aortic pressure and systemic vascular resistance within 20 to 30 minutes. Mean aortic pressure decreased from 108 +/- 22 mm Hg to 85 +/- 27 mm Hg (p less than 0.005). Systemic vascular resistance decreased from 2,705 +/- 1,072 to 1,942 +/- 823 dynes sec cm-5 (p less than 0.005). 2n response to nitroprusside-induced decreases in left venticular afterload, cardiac indes increased from 1.83 +/- 0.58 to 2.04 +/- 0.54 L/min/m2 (p less than 0.025). Pulmonary capillary wedge pressure (PCW), right atrial pressure, right and left ventricular minute work indices, and the rate-pressure products did not change, indicating that nitroprusside administration during IABP further increased cardiac output without increasing ventricular filling pressure, ventricular work, or indices of myocardial oxygen consumption. The data suggest that nitroprusside, in conjunction with volume loading to optimal preload levels (PCW = 15 to 18 mm Hg), augments ventricular performance in postcardiotomy low-output syndrome by lowering impedance to left ventricular ejection through a direct dilator effect on vascular smooth muscle, without a direct effect on cardiac muscle. Thus it is a valuable pharmacologic adjunct during mechanical (IABP) support of the failing circulation.

Blood Pressure↗