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Biomedical subjects

M Billingham

Publications and source records attributed to M Billingham.

At least 55 records · Page 3Linked to original sources
PubMed1979

Cardiac abnormalities in myotonic dystrophy. Electrophysiologic and histopathologic studies.

Eight young adult male patients with myotonic dystrophy, mean age 26 years, underwent 24-hour Holter electrocardiographic monitoring and intracardiac electrophysiologic study. Right ventricular endomyocardial biopsies were performed at the end of the electrophysiologic study in five of them. The atrial to His[A-H] interval was 155 msec in one case and less than or equal to 55 msec in all patients. Twenty-four hour Holter electrocardiographic monitoring demonstrated more than 4 premature ventricular contractions per minute in two patients and marked cyclical sinus arrhythmia during sleep in two others. Electron microscopic analysis of the endomyocardial biopsy specimens disclosed no prominent sarcoplasmic reticulum abnormalities but prominent I bands compared to previously obtained controls. Myofibrillar degeneration was seen in all cases and was associated with abnormal mitochondria in two. Cardiac abnormalities can be detected very early in the evolution of myotonic dystrophy, even prior to the onset of cardiac symptoms. The reported abnormalities appear closely related to the pathologic process affecting other skeletal muscles.

Adolescent↗
PubMed1979

Cardiac damage produced by direct current countershock applied to the heart.

This study examined the pathophysiology of the myocaridal damage produced by direct current shock over a dose range of 10 to 90 watt-seconds, applied directly to the heart in 26 dosgs. The extent of injury produced was assessed with creatine kinase depletion and light and electron microscopy, and was correlated with in vivo imaging and tissue distributions of the isotopes technetium-99m pyrophosphate and thallium-201. Changes in intramyocardial temperature and regional myocardial blood flow were also measured. Uptake of technetium-99m pyrophosphate occurred exponentially with graded increases in shocks, and this agent was more sensitive than thallium-201 in detecting injury both on imaging and at tissue level. The threshold for significant injury was approximately 30 watt-seconds, and on electron microscopy a characteristic feature was marked dehiscence of the intercalated disks between the damaged myocytes. The use of different-size paddles did not appear to affect the total number of cells damaged. However, with large paddles the injury was more superficial and spread over a wider area. With short time intervals between successive shocks, a greater amount of injury occurred, in part because of a compounding of the thermal component of the damage. Hypothermia can reduce the degree of injury.

Animals↗
PubMed1977

Polymeric albumin in the urine of patients with nephrotic syndrome.

Dimer and polymer albumin was detected in the urine of a proportion of pantients with a nephrotic syndrome. Most of it was present as S-S bonded dimer and polymer; co-polymers, however, with IgG and alpha (1) anti-trypsin could be demonstrated. It is suggested that albumin polymerizes after it has passed the glomerular membrane. Albumin dimer was associated mainly with minimal change disease and early membranous glomerulopathy in patients, who in general responded well to therapy.

Albumins↗
PubMed1977

Successful retransplantation of the human heart.

Cardiac retransplantation has been performed in five patients at Stanford University Medical Center. Long-term survival and rehabilitation have been achieved in two cases. In the first case retransplantation was performed 57 days after the initial procedure because of persistent acute graft rejection. The second patient underwent retransplantation 27 months postoperatively because of documented accelerated graft atherosclerosis. The major indications for cardiac retransplantation consist of intractable acute rejection and late postoperative graft atherosclerosis. These complications should prompt consideration of cardiac retransplantation in carefully selected cases.

Adolescent↗
PubMed1976

Problems in assessing infarction size by epicardial mapping: preliminary studies with quinidine.

Some of the laboratory difficulties in assessing infarction size produced by intermittent coronary artery occlusion were demonstrated by using an epicardial mapping technique in anesthetized open-chest dogs. Intermittent occlusion of a left anterior descending coronary artery branch resulted in a marked elevation of the ST segment above the baseline in the areas of the myocardium supplied by this vessel. Repeated occlusions after administration of normal saline as a control produced less ST-segment elevation thn that noted during control occlusions; however, repeated occlusions after infusion of quinidine produced a further lessening in ST-segment elevation. The problems encountered in interpreting these results are emphasized. Long-term coronary occlusion studies were performed in order to correlate epicardial electrograms with histological findings of ischemia or myocardial necrosis. Our investigations show that epicardial mapping tended to underestimate the area of injury, and this limits the interpretation of drug intervention studies such as those in which quinidine is administered. Therefore, caution should be exerted when using epicardial mapping techniques to assess the effect of various pharmacological interventions on infarction size in open-chest dogs.

Animals↗
PubMed1974

Physiological distribution of digoxin in human heart.

Using the recipient's human heart removed at cardiac transplantation, the distribution of digoxin at both the cellular and subcellular level has been studied. In the presence of diffuse histological myocardial abnormalities tissue digoxin is decreased, but the subcellular distribution, presumably reflecting binding to a possible receptor site, is uniform. When the histological abnormality is focal then digoxin distribution is uniform.These results suggest that in the presence of myocardial ischaemia plasma digoxin concentrations may not reflect total myocardial levels accurately.

Adenosine Triphosphatases↗
PubMedDate not supplied

Phase I results of pullback atherectomy for hemodialysis access.

PURPOSE: Balloon angioplasty and directional atherectomy frequently have short-lived results for stenoses associated with hemodialysis. Results are reported for a phase I trial of the pullback atherectomy catheter (PAC) for treatment of hemodialysis access-related stenoses. PATIENTS AND METHODS: Six intragraft and six venous stenoses in nine patients were treated with the PAC. Two lesions were treated with adjunctive balloon angioplasty, and two were treated with adjunctive directional atherectomy. Clinical and angiographic follow-up were obtained for all patients. All specimens were examined histologically. RESULTS: Initial procedural success was achieved in 83% of stenoses (10 of 12). For intragraft stenoses, the 6-month primary patency was 60% (three of five) and the 6-month secondary patency was 80% (four of five). All six venous stenoses restenosed or thrombosed within 3 months. All specimens contained fibrous plaque or intimal hyperplasia. In addition, all six venous stenosis specimens contained media and two contained adventitia. Significant complications during treatment of venous stenoses included severe venous spasm in three and venous pseudoaneurysms in two. One PAC tip fracture occurred during treatment of an intragraft stenosis. CONCLUSION: Pullback atherectomy is potentially safe and effective for intragraft stenoses; however, it is not safe or effective for venous stenoses.

Adult↗
PubMedDate not supplied

Selective T-cell depletion with Ox-38 anti-CD4 monoclonal antibody prevents cardiac allograft rejection in rats.

New monoclonal antibodies directed to membrane molecules unique to lymphocyte subsets have provided the means to alter the immune response to alloantigens in a more selective fashion. This investigation demonstrates that monoclonal antibody-induced depletion of CD4 helper/inducer T lymphocytes before transplantation of a fully mismatched heart allograft allows permanent engraftment in rats without further immunosuppression. Five adult male ACI (RT1a) rats received cell-depleting doses of the mouse anti-rat CD4 monoclonal antibody, MRC Ox-38, for 1 month before undergoing heterotopic abdominal heart transplantation. No other immunosuppression was administered, and immunotherapy was discontinued the day of transplantation. After all five Lewis rat (RT1(1)) hearts were maintained free of rejection for more than 3 months, a second heterotopic transplant was performed, this time to the femoral vessels, using either fresh Lewis heart allografts (n = 3) or third-party, Brown-Norway (RT1n) hearts (n = 2). Histologic evaluation was performed 3 weeks later and revealed severe rejection of the femoral Brown-Norway grafts with no evidence of rejection in any of the femoral or original abdominal Lewis grafts. These results suggested that limited, pretransplant anti-CD4 immunotherapy allowed permanent engraftment of fully mismatched cardiac allografts in rats and conferred donor-specific unresponsiveness.

Abdomen↗