Search PubMed⌕ Search

Biomedical subjects

J B Atkinson

Publications and source records attributed to J B Atkinson.

At least 127 records · Page 7Linked to original sources
PubMed1988

Mediastinal fibrosis complicating histoplasmosis.

Mediastinal fibrosis, the most serious late complication of remote infection by Histoplasma capsulatum, is a thick, dense fibrotic capsule which surrounds a small mediastinal focus of old caseous adenitis. The fibrotic process may accrue over prolonged periods and extend within the lumina of critical mediastinal structures to produce complete occlusion. We summarized clinical and radiographic data for 71 patients with mediastinal fibrosis; the criteria for inclusion were the clinical demonstration of occlusion of major central airways (trachea or mainstem bronchus) or major vessels (pulmonary arteries or veins) and the absence of other disease processes which might cause such obstruction. We selected 65 patients who met these criteria from the medical literature of the last 40 years and report 6 new cases from our experience. The majority of patients were diagnosed between ages 20 and 40. The most common symptoms included hemoptysis, dyspnea, and cough. An accentuated pulmonic component of the second heart sound, wheezing, and localized murmur were among the physical findings reported. Radiographic abnormalities consisted of mass lesions and atelectasis or infiltrates, but were often nonspecific. Chest radiography was deceptively normal in some patients, even in the presence of major central airway or vascular occlusion, especially when the focus was subcarinal. Computed tomography has particular promise to depict the mediastinal abnormalities in this process. Surgery had minimal therapeutic benefit. Because of incomplete followup, the mortality of 30% in this series surely does not represent the true overall mortality of mediastinal fibrosis.

Adolescent↗
PubMed1988

Heterogeneity of pathologic lesions in familial primary pulmonary hypertension.

We analyzed lung specimens from 23 affected members of 13 families with known familial primary pulmonary hypertension. In this heritable disease, the pathogenetic basis of disease should be distinct within families, and the pathologic lesions should reflect the underlying biologic mechanisms. Two pathologic types of primary pulmonary hypertension have been proposed to exist, "plexogenic" and "thromboembolic." The purpose of this study was to determine the nature and variety of pathologic lesions in families with familial primary pulmonary hypertension and to discover whether the pattern of pathologic lesions found supported the existence of two types of disease. We found marked heterogeneity of pathologic lesions within and among families, including frequent coexistence of thrombotic and plexiform lesions. We conclude that the lesions found in primary pulmonary hypertension are not specific but represent different manifestations of the same pathologic process. Thus, plexiform and thrombotic lesions of the pulmonary arterioles may not arise from distinctly different biologic processes but may simply be different manifestations of the same process. Further insights in primary pulmonary hypertension must come from study of the biologic aspects of the intimal lesion.

Fibrosis↗
PubMed1988

The pathology of mitral valve prolapse.

The gross criteria for diagnosing prolapsing mitral valve are: 1. interchordal hooding of the involved leaflets, 2. hooding or doming of leaflets towards the left atrium, 3. elongation of the involved leaflets resulting in an increase in valve area, 4. dilatation of the valve annulus in patients with severe mitral regurgitation. The posterior leaflet is most frequently affected. The involved leaflets, in general, are thickened, soft, greyish white and have a smooth atrial surface. Chordae tendineae are described as elongated, tortuous and attenuated or thinned. Deviations from normal chordal insertion have recently been observed which possibly appear to represent the underlying abnormality. Microscopic findings include significant thickening of the spongiosa and the fibrosa, changes in dense collagen fibers in the atrialis layer, occasionally, with fibrin platelet deposits. Histochemical characterization of changes in the spongiosa may also be helpful in the diagnosis. Ultrastructurally, there may be changes in collagen and elastic fibers as well as myxoid areas. On comparison of findings in surgically-removed mitral valves with those of control specimens from autopsy patients with no cardiac abnormalities, the length of the anterior and posterior leaflet as well as the annular ring diameter was larger in the valves with prolapse. Two-dimensional echocardiography accurately assessed leaflet length when compared to morphologic measurements, however, the annular diameter during systole or diastole was smaller. In patients with mitral regurgitation requiring surgery, mitral valve prolapse is the most common cause. Annular ring dilatation and chordae tendineae rupture appear to contribute substantially to incurrence of the mitral regurgitation. The heart weight is increased in the majority of patients with symptomatic mitral valve prolapse but normal, however, in those without symptoms. The most frequent complication of mitral valve prolapse is mitral regurgitation with or without congestive heart failure. Patients with redundant leaflets may be at high risk of sudden death. Young women with abnormal resting ECG, prolonged Q-T interval, family history of sudden death or complex ventricular arrhythmias may also be at a greater risk of sudden death. The incidence of infective endocarditis appears higher in those with redundant than in those with nonredundant valves. The incidence of cerebral ischemic events is low.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1988

The effect of verapamil cardioplegia on myocardial ultrastructure.

The calcium channel blocker, verapamil, was evaluated as an adjunct to cold cardioplegia in 16 randomized patients with unstable angina pectoris who received saphenous vein bypass grafts. Myocardial biopsies taken before cardioplegia showed various degrees of ischemic change as assessed by ultrastructural parameters (mitochondrial swelling, matrix clearance, and sarcotubular dilatation). After reperfusion, the majority of the patients had progressive changes of ischemia, with marked mitochondrial and sarcotubular swelling, depletion of glycogen, chromatin clumping, and myofibrillar disruption; amorphous mitochondrial densities were occasionally seen. The ultrastructural changes after cardioplegia were dependent primarily on the extent of preexisting ischemic damage and did not correlate with the use of verapamil. Verapamil did not protect the ischemic myocardium during cold cardioplegia as assessed ultrastructurally.

Biopsy↗
PubMed1987

Abnormal chordal insertion: a cause of mitral valve prolapse.

Although the morphology of mitral valve prolapse (MVP) has been described, abnormalities of chordal arrangement and insertion have not been emphasized. We retrospectively reviewed 23 surgically-excised MVP and 10 control mitral valves removed at necropsy. Two-dimensional echocardiograms (2DE) were available in 10 MVP and in six additional controls. 2DE accurately assessed the length of anterior leaflet (AL) and posterior leaflet (PL) of the mitral valve (3.2 +/- 0.7 cm and 2.2 +/- 0.6 cm, respectively) as compared to morphologic measurements (3.0 +/- 0.4 cm and 2.1 +/- 0.4 cm, respectively). However, annular diameter as assessed by echocardiography was significantly less (4.6 +/- 0.7 cm) than that derived by morphologic measurements of annular circumference (AC) (5.3 +/- 0.7 cm). The AL and PL lengths and the mitral anuli were significantly larger in patients with MVP as compared to controls (p less than 0.01) when assessed both by 2DE and by morphology. The ratio of the maximum distance of chordal separation/AC was 0.11 +/- 0.04 in MVP and 0.13 +/- 0.02 in controls (p less than 0.05). Chordal divisions were increased in MVP (4.2) compared to controls (3.1, p less than 0.01). The most striking morphologic feature of MVP was abnormal chordal insertion and a random, unpredictable pattern of chordal distribution. We postulate that abnormal chordal architecture may be responsible for unequal stress on the valve leaflets and may thus lead to MVP.

Adult↗
PubMed1987

Intermittent reperfusion extends myocardial preservation for transplantation.

A protocol was developed to compare prolonged heart preservation by hypothermic storage with prolonged hypothermic storage interrupted by a period of reperfusion. Hearts from adult mongrel dogs were excised after administration of 4 degrees C crystalloid cardioplegia. Group A hearts (N = 7) underwent 7.5 hours of ischemia at 4 degrees C followed by 1.5 hours of reperfusion and rewarming (A0). Group B hearts (N = 8) underwent 3 hours of ischemia at 4 degrees C, 1.5 hours of reperfusion and rewarming (B1), 3 additional hours of ischemia at 4 degrees C following repeat cardioplegia, and finally 1.5 hours of reperfusion and rewarming (B2). During reperfusion, hearts were defibrillated and left ventricular (LV) function was assessed by measuring isovolumic peak systolic pressure and maximum positive rate of rise of LV pressure (+dP/dtmax) with an intraventricular balloon. LV biopsy samples for adenosine triphosphate (ATP) assay were obtained before ischemia and after each rewarming period. One Group A heart could not be defibrillated and studied. All Group B hearts completed the protocol. LV function, as assessed by peak pressure and +dP/dtmax, at B1 and B2 exceeded values obtained at A0, but the differences were not statistically significant. The mean ATP level was 63.4 +/- 7.7% of baseline at B1 and 79.7 +/- 4.3% of baseline at B2 (p less than .03). The mean ATP level was 57.9 +/- 5.9% of baseline at A0 (p less than .007, B2 vs. A0). It is presumed that intermittent reperfusion allows repletion of substrate stores, which results in improved myocardial protection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1987

Use of a subclavian venous catheter for short- and long-term hemodialysis in children.

Vascular access for hemodialysis in children poses problems not encountered in adults because of the small size of the vessels available. The increasing use of peritoneal dialysis has created a large number of patients who need prompt access for hemodialysis for days to weeks during episodes of peritonitis. There are also occasional patients who have exhausted available fistula sites and still require hemodialysis. To address these problems, we designed a series of catheters for insertion in the subclavian vein. The catheters are stiffer than the Hickman type catheter to allow for higher flow rates without collapse. Seventy-five catheters were implanted in 58 patients with a mean age of 14 years. Twelve catheters were inserted in ten children for long-term (over 3 months) access; they have been in place for a mean of 259 days and used for a mean of 64 dialyses. In two children, the catheter has been the sole site for hemodialysis for over a year. Fifty-eight catheters were implanted in 43 patients for short-term hemodialysis. They were in place for a mean of 29 days and used for a mean of 13 dialyses. The major complications encountered were clotting of the catheter and migration out of position. Four catheters were removed because of infection. These new catheters provide effective hemodialysis for children as small as 7 kg with an acceptable morbidity rate and may be used for extended periods of time if necessary.

Adolescent↗
PubMed1987

Experimental evaluation of a new albumin-impregnated knitted dacron prosthesis.

The performance of a new albumin-impregnated, knitted vascular graft stored damp in saline was assessed by a comparative study in the canine aorta. Knitted grafts interposed into the descending thoracic aorta for 4 weeks included: albumin-coated and stored damp in saline (damp albuminated) (n = 6), albumin-coated and freeze-dried (dry albuminated) (n = 5), collagen-coated (n = 4), and uncoated (n = 4). The results of macroscopic and microscopic evaluation were subjected to one-way analysis of variance (Newman-Keuls). Damp albuminated grafts had significantly less transinterstitial blood loss than uncoated grafts (P less than 0.05). No significant differences in thrombogenicity, thrombus-free surface area, tissue ingrowth, or endothelial coverage existed between the damp albuminated and the uncoated grafts. However, significantly less thrombogenicity (P less than 0.05) and more endothelial cell coverage (P less than 0.05) were present in the damp albuminated grafts than in the collagen-coated grafts. No evidence for delayed graft hemorrhage or distal embolization was found in any group. The new damp albuminated graft is a minimally thrombogenic prosthesis combining low implantation porosity with relative ease of handling. It should function well as a low porosity graft for great vessel replacement.

Animals↗
PubMed1987

Erythropoietin control of terminal erythroid differentiation: maintenance of cell viability, production of hemoglobin, and development of the erythrocyte membrane.

Using the spleen cells of mice infected with the anemia-inducing strain of Friend leukemia virus, an in vitro model system of erythropoiesis has been developed in which a homogeneous population of murine proerythroblasts terminally differentiates in response to erythropoietin (EP). The biochemical events involved in EP's capacity to maintain viability, induce hemoglobin production, and promote the development of the specialized erythrocyte membrane were studied during the 48-72 hour period required for proerythroblasts to differentiate into reticulocytes. The results show that EP increases glucose uptake and the syntheses of RNA and protein in the first few hours after exposure of the erythroblasts to the hormone. A coordinated production of heme, alpha and beta globin occurs later and peaks at about 48 hours. This peak corresponds to the time at which the majority of cells are undergoing enucleation and becoming reticulocytes. The syntheses of the erythrocyte membrane and membrane skeletal proteins are not coordinated, and multiple patterns of synthesis are found with respect to the time of EP exposure. A number of proteins are lost from the membrane fraction while the characteristic proteins of the mature erythrocyte become prominent in the membrane fraction of erythroid cells as they develop from reticulocytes into erythrocytes.

Animals↗
PubMed1986

A comparison of staging methods for Hodgkin's disease in children.

Potential long-term complications of radiotherapy and chemotherapy in the pediatric patient with Hodgkin's disease necessitate accurate staging. To determine the accuracy of abdominal computed tomography (CT) and gallium citrate Ga 67 scans in staging Hodgkin's disease, we reviewed the charts of all children with Hodgkin's disease seen at Childrens Hospital of Los Angeles from 1975 to 1985. Patients with pathologically proved stage IV disease (ie, bone marrow involvement) and those who only underwent staging laparotomy were excluded. A total of 40 children underwent staging by laparotomy and staging by abdominal CT and/or 67Ga scan. The CT and 67Ga scans were reviewed by radiologists in a blinded manner and compared with the results of a formal staging laparotomy. Of the 38 patients whose disease was staged with 67Ga scan, disease in ten was understaged and in four overstaged, for a 37% incorrect staging rate. Of the 14 patients whose disease was staged by CT scan, disease in three was understaged and in one overstaged, for a 29% incorrect staging rate. In view of the inaccuracy of noninvasive studies and the impact of incorrect staging on treatment, we recommend that a staging laparotomy be performed in all children with Hodgkin's disease who are not proved to have stage IV disease.

Adolescent↗
PubMed1986

Inflammatory bowel disease in glycogen storage disease type Ib.

We have observed the development of chronic inflammatory bowel disease, indistinguishable from Crohn disease, in two boys with glycogen storage disease type Ib (GSD-Ib). A chance association of these diseases in two patients is unlikely. Studies of their neutrophils showed severe chronic neutropenia (mean absolute granulocyte counts of less than 500 cells/microliter) and markedly deficient chemotactic response (less than 5% of reference values) in the patients with GSD-Ib and normal neutrophil values in four patients with glycogen storage disease type Ia (GSD-Ia). Monocyte counts and responses to chemotactic stimulation were normal in both GSD-Ia and GSD-Ib. Chronic inflammatory bowel disease appears to be associated with GSD-Ib, and neutrophil abnormalities may be involved in the pathogenesis of the bowel inflammation.

Adolescent↗