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Biomedical subjects

J B Atkinson

Publications and source records attributed to J B Atkinson.

At least 109 records · Page 6Linked to original sources
PubMed1991

Pulmonary sequestration: diagnosis with color Doppler sonography and a new theory of associated hydrothorax.

The diagnosis of pulmonary sequestration has traditionally relied on angiographic demonstration of a systemic artery to the sequestered lung tissue. Rarely, extralobar sequestration can be associated with tension hydrothorax, which in the past has invariably led to fetal hydrops and death. The authors report the cases of three infants who had initially undergone color and spectral Doppler analysis; in two of them, extralobar sequestrations were associated with congenital hydrothorax. All three patients underwent surgical resection and histopathologic evaluation of their sequestrations. On the basis of the findings, the authors believe that torsion of the sequestration occludes the efferent venous and lymphatic channels, initiating the accumulation of pleural fluid and subsequent hydrops through systemic venous obstruction. Color Doppler made possible the identification of minute feeding vessels, obviating further diagnostic studies.

Bronchopulmonary Sequestration↗
PubMed1990

Nifedipine reduces atherogenesis in cholesterol-fed heterozygous WHHL rabbits.

We have developed a new model to study the interaction between diet and genetics in atherogenesis, the cholesterol-fed heterozygous WHHL rabbit. To determine the effects of calcium blockers on atherosclerosis in this model, two groups of heterozygous WHHL rabbits were fed 0.25% cholesterol and 2% peanut oil with (n = 6) and without (n = 6) oral nifedipine (40 mg/kg/day) for 16 weeks. Body weights, serum cholesterol, triglycerides and calcium, and blood pressures were not significantly different between the 2 groups during the study period. Heterozygous WHHL rabbits in the nifedipine group had less aortic surface area with sudanophilic lesions (23 +/- 15% vs. 62 +/- 18%, P less than 0.01) and fewer segments of coronary arteries with lesions (19 +/- 9% vs. 35 +/- 8%, P less than 0.02). Total aortic cholesterol, phospholipid, and calcium were also reduced in nifedipine-treated rabbits compared with untreated animals. We conclude that nifedipine reduced atherosclerosis in this model. Although the mechanism is unknown, it is apparent that nifedipine acts independently of changes in plasma lipids and blood pressure.

Animals↗
PubMed1990

Vascular access in the neonate following extracorporeal membrane oxygenation.

An infant maintained on extracorporeal membrane oxygenation (ECMO) has unlimited vascular access. When the infant is returned to conventional ventilator therapy, the need for vascular access persists for days to weeks. Providing alternative central venous access may be problematic, particularly while the infant is still heparinized during the first 12 hours after decannulation. In this study, secondary central venous catheters (CVC) were placed, at the time of decannulation, into the internal jugular vein from which the venous bypass cannula is removed. Fifty-four of 90 infants supported with ECMO had secondary CVCs placed (60%) and vascular access maintained for 2 to 122 days (mean, 17.5 days). Four catheters were removed for culture-proved line sepsis (7.4%). Neck wounds were reexplored for bleeding, while on bypass, in 2 of 4 patients in the sepsis group. There were no deaths related to catheter sepsis. Catheter-related septic infants had been on bypass for 50 to 88 hours (mean, 72.7 hours) as compared with 11 to 312 hours (mean, 104 hours) for the entire ECMO group, P = NS. This experience (942 catheter-days) suggests that secondary CVC placement into the vein used for bypass is safe with infectious complications comparable to catheters placed through primary wounds. Infants requiring neck explorations for bleeding while on bypass are not candidates for secondary CVC placement.

Catheterization, Central Venous↗
PubMed1990

Stimulation of wound bursting strength during protein malnutrition.

Nutrition is one of the most important factors affecting wound healing. Patients who have significant protein malnutrition and require emergency surgery are frequently encountered. Conventional nutritional preparation for surgery, with intravenous hyperalimentation, requires 10 to 14 days to demonstrate advantageous reversal of catabolism. Growth hormone is known to have an anabolic effect in malnourished animals. The purpose of this investigation was to study the ability of growth hormone, administered from the time of celiotomy, to improve wound strength in protein-malnourished animals and compare its efficacy with preoperative nutritional repletion. Rats were divided into four groups: Group I--normal control rats, group II--malnourished rats, group III--malnourished rats treated with growth hormone for 5 postoperative days, and group IV--malnourished rats refed normal chow for 3 days before operation. Controlled laparotomy wounds were closed with monofilament nylon which was removed at the time wound bursting strength was tested. Bursting strengths at the sixth day postoperative were as follows (means +/- SD): (table; see text) Wound strength of malnourished animals was significantly less than that of controls, (P less than 0.001). Wound bursting strength of groups III and IV was significantly improved over that of malnourished animals (group II), P less than 0.001. The bursting strength of group IV was significantly higher than that of group III. Growth hormone administration following celiotomy is nearly as effective in improving wound healing as preoperative nutritional repletion. These results suggest that growth hormone may be clinically applicable in preventing wound complications in malnourished patients requiring urgent or emergency laparotomy.

Abdomen↗
PubMed1990

Plaque morphology and pathologic changes in arteries from patients dying after coronary balloon angioplasty.

Morphologic correlates of pathologic success or failure were studied at autopsy in 28 patients with 40 coronary arteries that had been subjected to balloon angioplasty. The presence of the following histologic features was evaluated: plaque concentricity or eccentricity, calcification, fibrous or fibropultaceous plaque, medial disruption, luminal thrombus and inflammation. Angioplasty was considered successful (residual cross-sectional luminal area greater than 25%) on pathologic examination in 14 arteries and unsuccessful in 26 arteries. Eccentric plaques were more likely to be successfully dilated than were concentric lesions (p less than 0.05). Six (50%) of 12 fibropultaceous plaques were successfully dilated compared with only 8 (29%) of 28 fibrous plaques. Moderate to severe calcification did not preclude morphologic success. Medial stretching or dissection, or both, was more often associated with a successful result. Thus, plaque morphology may be an important determinant of pathologic outcome after coronary angioplasty.

Aged↗
PubMed1990

The effect of perioperative exogenous growth hormone on wound bursting strength in normal and malnourished rats.

Patients with significant malnutrition secondary to underlying disease may require major surgical intervention on an urgent basis. Nutritional restoration using enteral or intravenous alimentation requires a delay of 10 to 14 days and is frequently not practical. With the availability of human growth hormone (GH) produced by recombinant DNA technology, this study was undertaken to evaluate the effect of exogenous GH on wound tensile strength in a rat model. Fifty-four animals were divided into three groups: group I, normal nourished control; group II, malnourished; group III, malnourished, rat GH treated (1 mg GH administered 3 days preoperative and 5 days postoperative celiotomy). Wound tensile strength was measured at 6 days postoperatively. Wound strengths in malnourished rats were significantly less than in normal controls (P less than .001). With the administration of growth hormone in group III, wound strength was significantly improved when slightly improved over normally nourished controls (P less than .05). A dose response curve demonstrated progressive improvement in wound tensile strength from 0.01 mg/d to 1.0 mg/d. Thus growth hormone administration to malnourished animals significantly enhances wound strength. With the availability of recombinant produced human GH these observations may be clinically applicable.

Abdominal Injuries↗
PubMed1990

Long-term follow-up of brachial artery ligation in children.

Ligation of the brachial artery in the antecubital fossa in children can be performed without limb loss, but the effect on subsequent limb growth is unknown. From 1969 to 1974, brachial artery ligation for insertion of a Scribner shunt was performed in 27 patients with a mean age of 8.4 years (range, 3 to 15 years). We examined 11 patients, all with functional renal transplants, a mean of 15.8 years (range, 13 to 18 years) after ligation. Nine patients had unilateral ligation and two had bilateral ligation. The patients were examined for arm length and circumference, resting blood pressure at the wrist, neurologic function of the arm, and exercise tolerance. A significant difference in resting arterial pressures in the ligated extremity was uniformly noted (mean systolic pressure 106 mmHg versus 123 mmHg in 7 patients, p less than 0.01). Although no patient specifically complained of problems with the ligated side, six of nine patients with unilateral ligation experienced arm discomfort on stress testing. There was no significant difference in limb circumference or length between the ligated and unligated extremity. Ligation of the brachial artery in growing children with renal disease caused diminished resting pressure and mildly decreased exercise tolerance but did not lead to limb loss or subsequent growth abnormalities.

Adolescent↗
PubMed1989

Cholesterol-fed heterozygous Watanabe heritable hyperlipidemic rabbits: a new model for atherosclerosis.

Homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits are used widely to study atherosclerosis, but the WHHL heterozygous rabbit has received little attention. To study their potential as a model for atherosclerosis, heterozygous WHHL and New Zealand white (NZW) rabbits were fed diets containing 0%, 0.5% and 1.0% cholesterol. Plasma lipids were analyzed at 0, 4, 8, 12, 16 and 24 weeks, and animals were killed at 12 and 24 weeks. Plasma cholesterol levels were significantly higher in cholesterol-fed WHHL heterozygotes at 8 weeks compared with NZW rabbits, but no differences were apparent at other times. Atherosclerotic plaques in the aortas of cholesterol-fed WHHL heterozygous rabbits differed from those in NZW rabbits, in that the WHHL had complicated lesions with necrosis, cholesterol clefts, fibrous caps and calcification, similar to that found in humans and homozygous WHHL rabbits. In contrast, NZW rabbits had predominantly foam cell lesions. Heterozygous WHHL rabbits also had less extensive extravascular foam cell deposits. Our results suggest that the cholesterol-fed heterozygous WHHL rabbit may provide a promising model for studying the pathogenesis of atherosclerosis.

Animals↗
PubMed1989

A simplified method for autoregulation of blood flow in the extracorporeal membrane oxygenation circuit.

The ability of autoregulate blood flow in the extracorporeal membrane oxygenation (ECMO) circuit is critical to prevent cavitation and air embolism. Conventional circuits have used a spring-loaded mechanical switching device that interrupts the flow of power to the roller head when falling venous return collapses the venous bladder. This device has been less than desirable due to being poorly adjustable, subject to sporadic flow in periods of hypovolemia, and not commercially available. An improved alternative is reported using a commercially available pressure monitor and computerized switching device, which, when attached to the venous reservoir or bladder, has the ability to autoregulate blood flow in the ECMO circuit by smoothly regulating the roller head velocity. Experience with this system in the laboratory employing a swine model, and in 35 infants, is reported without device-related complications.

Equipment Design↗
PubMed1989

Congestive heart failure due to coronary artery disease without myocardial infarction: clinicopathologic description of an unusual cardiomyopathy.

Cardiomyopathies (CMs) can be classified as idiopathic dilated, hypertrophic, restrictive/obliterative, and so-called "ischemic cardiomyopathy." We have observed a subgroup of patients with congestive heart failure, dilated hearts, and severe coronary artery disease in the absence of myocardial infarction and therefore not fulfilling the criteria for ischemic CM. To better elucidate this group, which we called "coronary" CM, 54 consecutive necropsy patients who had congestive heart failure were retrospectively studied. Nineteen patients had idiopathic dilated CM, 26 had ischemic CM, and nine had coronary CM. The mean age of the patients with coronary CM and ischemic CM was significantly greater than that of the patients with idiopathic dilated CM (62 +/- 10 and 64 +/- 10 years versus 47 +/- 19 years, respectively). The duration of congestive heart failure was longest in the coronary CM group (4.1 +/- 3.4 years); half of these patients died suddenly or from arrhythmias. Hearts from patients with coronary CM had marked biventricular dilatation and severe coronary artery disease (mean number of coronary arteries with more than 75% narrowing, 2.2). No acute or healed infarcts were grossly visible, but interstitial and focal perivascular fibrosis were present in the myocardium of all coronary CM hearts. Although coronary CM may comprise a subset of so-called "ischemic cardiomyopathy," these cases may also represent idiopathic dilated CM with coincidental coronary artery disease.

Aged↗
PubMed1989

Long-term assessment of a damp-stored, albumin-coated, knitted vascular graft.

In a previous study the authors reported greater endothelialization and thrombus-free surface area in albumin-coated grafts compared with collagen-coated grafts after 1 month's aortic interposition. Another study was undertaken to determine whether these differences persisted after a 6-month implantation period. A 6 cm segment of either an albumin-coated [n = 6] or a collagen-coated [n = 4] graft was implanted into a canine descending thoracic aorta for 6 months. Light micrographs from multiple sections of each explanted graft were scored from 1 to 4, least to most, for tissue ingrowth, perigraft inflammation, and capsular thickness. Using computer planimetry, luminal thrombus free surface area and endothelial coverage were calculated from gross and electron photomicrographs, respectively. The results were averaged and expressed as mean +/- standard error (SEM). After 6 months, no significant differences were noted between the albumin-coated grafts and the collagen-coated grafts, both of which were durable and served equally well as scaffolds for vascular remodeling and tissue incorporation. The authors conclude that the safety, ease of handling, low porosity, low thrombogenicity, and durability of the albuminated grafts warrant their clinical trial.

Albumins↗
PubMed1989

Continuous infusion of low-dose urokinase in the treatment of central venous catheter thrombosis in infants and children.

Thrombotic occlusion is a frequent complication associated with the use of central venous catheters. The purpose of this study was to evaluate the efficacy of a continuous infusion of low-dose urokinase (200 U/kg/h) in clearing catheters that had not cleared after two bolus doses of urokinase in a pediatric oncology population. Fifty-eight incidents of catheter-related occlusions (49 Hickman-type catheters/nine implantable ports) as documented by radiographic dye study occurred in 227 pediatric oncology patients with 254 central venous catheters during a 1-year period. Fourteen of 58 catheters failed to clear after two bolus instillations of urokinase (5,000 U and 10,000 U). Thirteen catheters were treated for 24 hours with urokinase, 200 U/kg/h, and one catheter with urokinase, 100 U/kg/h for 24 hours. Twelve catheters were used for study. Coagulation studies were monitored preinfusion, 12 hours into the infusion, and postinfusion. Patency was reestablished in 11/12 catheters (92%) with a mean infusion time of 28.7 hours. No coagulation abnormalities or clinical bleeding associated with the urokinase infusion occurred. Only one patient exhibited a prolonged partial thromboplastin time (greater than 150 seconds); this was associated with a heparin effect. These data indicate that low-dose urokinase may be a safe and effective means to clear occluded central venous catheters in children.

Blood Coagulation↗
PubMed1989

Perioperative factors affecting the outcome following repair of biliary atresia.

The records of all patients with biliary atresia seen at the Childrens Hospital of Los Angeles during a 14-year period were reviewed. Of the 41 patients who could be evaluated, 32 were treated with trimethoprim and sulfamethoxazole prophylaxis, five were given other agents, and four received no prophylaxis after surgery. At least one episode of cholangitis occurred in nine patients. With one exception, all patients destined to have cholangitis did so within 9 months of surgery. Of the nine patients, five were receiving prophylaxis at the time the disease developed, but two were no longer receiving any prophylaxis. The other two patients in whom cholangitis developed never received antibiotic prophylaxis. In the 24 patients who had a Kasai type of portoenterostomy, cholangitis developed in three of the five (60%) with a Roux-en-Y limb length less than 40 cm and in two of the 19 (10.5%) with limb lengths greater than 40 cm (P less than .02). When performed earlier than 61 days after birth, surgery resulted in adequate bile flow in 64.7% (11/17) of patients who could be evaluated as compared with 31.8% (7/22) for surgery at 61 days or later (P less than .05). Of the patients with adequate biliary drainage 11 had no apparent liver disease, but only two of the patients with poor drainage were free of clinical liver disease. The conclusion from this series is that a combination of timely surgery, intestinal conduit at least 40 cm in length, and subsequent long-term antibiotic prophylaxis favors the best bile flow and reduces the occurrence of cholangitis, resulting in the best outcome.

Biliary Atresia↗
PubMed1989

Percutaneous insertion of subclavian venous catheters in infants and children.

All attempts at subclavian venous catheterization by the Pediatric Surgery Service done during a one and one-half year period at the Children's Hospital of Los Angeles were prospectively studied. Catheterization was attempted in 107 patients with a mean age of 9.8 years. Cannulation of the vein was successful 89 times (71 per cent) with the major complications being arterial puncture (8.0 per cent), pneumothorax (2.4 per cent) and abnormal position (12.8 per cent). Fluoroscopy was a valuable adjunct when used, resulting in an 86 per cent success rate. The serious complication rate was similar between left and right-sided attempts, but more catheters were abnormally positioned during right-sided attempts (15.7 versus 5.2 per cent). Percutaneous insertion of subclavian venous catheters can be accomplished in infants and children with low morbidity. Cannulation of the left subclavian vein can be accomplished with a similar success rate and a lower malposition rate than the right side. Fluoroscopy is a useful tool to assist in the correct placement of the catheter.

Adolescent↗
PubMed1988

A comparison of morphologic and angiographic findings in long-term internal mammary artery and saphenous vein bypass grafts.

Internal mammary artery grafts are currently considered the conduits of choice for myocardial revascularization. Comparisons of long-term morphologic changes in internal mammary artery grafts and saphenous vein grafts and correlation with premortem angiography have not been reported. Eighteen internal mammary artery and 15 saphenous vein grafts that had been in place for 12 to 118 months (mean 56) in 18 patients were removed either surgically or at necropsy and examined histologically. Premortem angiograms were performed within 1 month of histologic study in 15 of these patients. Fibrointimal proliferation was more frequent in internal mammary artery than in saphenous vein grafts 8 [( 44%] of 18 versus 4 [27%] of 15; p = NS). In contrast, atherosclerosis was common in saphenous vein grafts but was extremely rare in internal mammary artery grafts (10 of 15 versus 1 of 18; p = 0.01). A good correlation was noted between the degree of narrowing estimated by angiographic and histologic measurements in both internal mammary artery grafts (d = 0.90) and saphenous vein grafts (d = 0.71). Accelerated atherosclerosis did not occur in internal mammary artery grafts, but was common in saphenous vein grafts. Fibrointimal proliferation was commonly associated with graft narrowing in internal mammary artery grafts and may be an important factor in late graft closure. This study also confirms that internal mammary artery grafts have greater longevity compared with saphenous vein grafts.

Adult↗
PubMed1988

An evaluation of the role of surgery in metastatic neuroblastoma.

The role of surgery was evaluated in 320 patients with metastatic neuroblastoma (Children's Cancer Study Group [CCSG] stage IV, excluding IV-S) enrolled in two CCSG treatment protocols between June 1978 and November 1982. The regimens consisted of combination chemotherapy, radiation therapy, and surgery. Two hundred seventy-seven surgical procedures were performed in 214 of the 320 eligible patients. Surgical intervention at the primary site was performed at initiation of therapy in 86 patients. There was a slight survival advantage when complete resection of the primary tumor was achieved (P = .09). Delayed surgery was performed in 89 patients. Gross complete resection of primary tumor was feasible in 57 of these patients (64.0%). However, survival analysis showed that resolution of metastases had a more important impact on subsequent length of survival than resectability at the delayed procedure (P = .005).

Adolescent↗