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Biomedical subjects

J A Kern

Publications and source records attributed to J A Kern.

At least 37 records · Page 2Linked to original sources
PubMed2001

A technique for adequate coverage of the proximal suture line during abdominal aortic aneurysm repair.

The proximal suture line is a vulnerable area after abdominal aortic aneurysm repairs. This area has been implicated in various postoperative complications, such as pseudoaneurysm formation, graft-enteric fistula, and suture line disruption. We present a technique that provides safe and adequate coverage of this suture line by using the aneurysm sac. This technique is derived from the z-plasty technique used for scar revision. The technique is illustrated with detailed line drawings. None of the patients in whom we used this technique have had any complications related to the proximal suture line.

Aortic Aneurysm, Abdominal↗
PubMed2001

An adenosine A2A agonist, ATL-146e, reduces paralysis and apoptosis during rabbit spinal cord reperfusion.

BACKGROUND: We hypothesized that systemic ATL-146e, an adenosine A(2A) agonist, would decrease spinal cord reperfusion inflammatory stress and inhibit apoptosis and that these effects would correlate with improved neurologic functional outcome. METHODS: Thirty rabbits underwent cross-clamping of the infrarenal aorta for 45 minutes. One group of animals (n = 14) received 0.06 microg/kg per minute of ATL-146e infused intravenously for 3 hours, beginning 15 minutes before reperfusion. A second group of animals (n = 16) underwent spinal cord ischemia with saline vehicle alone and served as ischemic controls. Animals (n = 9, 11) from each group survived for 48 hours and assessed for neurologic impairment with the Tarlov (0-5) scoring system. Four animals from each group were humanely killed at the end of the 3-hour treatment period, and the remainder killed after 48 hours' survival. In all animals, lumbar spinal cord tissue specimens were frozen for subsequent Western blot analysis of heat shock protein 70 (HSP 70), and for the p85 fragment of poly (ADP-ribose) polymerase (PARP). Neuronal viability indices were determined at 48 hours with hematoxylin and eosin staining. RESULTS: There was improvement in neurologic function in rabbits receiving ATL-146e (P <.001) compared with ischemic controls. At the end of the 3-hour treatment period there was a 46% (P <.05) decrease in HSP 70 expression in the ATL-146e group compared with the control group, but no difference in PARP expression. At 48 hours, there was no difference between control and ATL-146e groups in HSP 70 expression, but there was a 65% (P <.05) reduction in PARP in the spinal cords of animals that had received ATL-146e. There was a significant improvement in neuronal viability indices in animals receiving ATL-146e compared with ischemic controls (P <.05). CONCLUSIONS: Systemic ATL-146e infusion during reperfusion after spinal cord ischemia results in preservation of hindlimb motor function. There is evidence of decreased spinal cord inflammatory stress immediately after treatment with ATL-146e as indicated by reduced HSP 70 induction. Treatment with ATL-146e is associated with a reduction in neuronal apoptosis as suggested by a substantial decrease in the fragmentation of PARP at 48 hours. These results suggest that inflammation during reperfusion and subsequent apoptosis contribute to paralysis after restoration of blood flow to the ischemic spinal cord.

Animals↗
PubMed2000

Massive cerebral embolization: successful treatment with retrograde perfusion.

Stroke is an unpredictable and morbid complication of cardiac operations. We report a patient who suffered massive bilateral cerebral embolization during aortic cannulation for coronary bypass. This was treated successfully with hypothermic circulatory arrest and high flow retrograde cerebral perfusion. The patient suffered only minimal neurologic impairment and improved rapidly. She was discharged home on postoperative day 7 neurologically intact.

Aged↗
PubMed2000

Retrograde perfusion with a sodium channel antagonist provides ischemic spinal cord protection.

BACKGROUND: Neuronal voltage-dependent sodium channel antagonists have been shown to provide neuroprotection in focal and global cerebral ischemic models. We hypothesized that retrograde spinal cord venous perfusion with phenytoin, a neuronal voltage-dependent sodium channel antagonist, would provide protection during prolonged spinal cord ischemia. METHODS: In a rabbit model, spinal cord ischemia was induced for 45 minutes. Six groups of animals were studied. Controls (group I, n = 8) received no intervention during aortic cross-clamping. Group II (n = 8) received systemic phenytoin (100 mg). Group III (n = 4) received systemic phenytoin (200 mg). Group IV (n = 8) received retrograde infusion of room temperature saline (22 degrees C) only. Group V (n = 8) and group VI (n = 9) received retrograde infusion of 50 mg and 100 mg of phenytoin, respectively, (infusion rate: 0.8 mL x kg(-1) x min(-1) during the ischemic period). Mean arterial blood pressure was monitored continuously. Animals were allowed to recover for 24 hours before assessment of neurologic function using the Tarlov scale. RESULTS: Tarlov scores (0 = complete paraplegia, 1 = slight lower limb movement, 2 = sits with assistance, 3 = sits alone, 4 = weak hop, 5 = normal hop) were as follows (mean +/- SEM): group I, 0.50 +/- 0.50; group II, 0.25 +/- 0.46; group IV, 1.63 +/- 0.56; group V, 4.13 +/- 0.23; and group VI, 4.22 +/- 0.22 (p < 0.0001 V, VI versus I, II, IV by analysis of variance). No differences in mean arterial blood pressure were observed. All animals in group III became profoundly hypotensive and died before the conclusion of the 45-minute ischemic time. CONCLUSIONS: Retrograde venous perfusion of the spinal cord with phenytoin, a voltage-sensitive sodium channel blocker, is safe and provides significant protection during prolonged spinal cord ischemia.

Animals↗
PubMed2000

Aprotinin improves pulmonary function during reperfusion in an isolated lung model.

BACKGROUND: We hypothesized that the use of aprotinin would ameliorate the reperfusion injury observed after lung transplantation because of a reduction in the inflammatory response. METHODS: We used an isolated, whole blood-perfused, ventilated rabbit lung model to study the effects of aprotinin during reperfusion. The control animals (group A, n = 8) underwent lung harvest after pulmonary arterial prostaglandin E1 injection and Euro-Collins preservation flush before saline storage for 18 hours at 4 degrees C. The experimental groups received either a low dose (3,000 KIU/mL; group B, n = 8) or a high dose (10,000 KIU/mL; group C, n = 8) of aprotinin added to the pulmonary flush before storage. Each lung was reperfused at 37 degrees C at a rate of 60 mL/min. RESULTS: The arterial partial pressure of oxygen values of group B (low-dose aprotinin) were significantly higher than those of group A (control) after 10 minutes of reperfusion (69.19 +/- 5.69 mm Hg versus 264.30 +/- 48.59 mm Hg, respectively, p = 0.001). Similar results were recorded at 20 and at 30 minutes of reperfusion. Similarly, after 10 minutes of reperfusion, the differences between groups A and C were 69.19 +/- 5.69 mm Hg versus 235.91 +/- 28.63 mm Hg, respectively (p = 0.001). CONCLUSIONS: The addition of aprotinin to the Euro-Collins pulmonary flush significantly improves arterial oxygenation in the early reperfusion period. The enhanced oxygenation suggests that aprotinin may offer protection against early reperfusion injury.

Animals↗
PubMed2000

Hypothermic retrograde venous perfusion with adenosine cools the spinal cord and reduces the risk of paraplegia after thoracic aortic clamping.

OBJECTIVE: We evaluated the utility of retrograde venous perfusion to cool the spinal cord and protect neurologic function during aortic clamping. We hypothesized that hypothermic adenosine would preserve the spinal cord during ischemia. METHODS: Six swine (group I) underwent thoracic aortic occlusion for 30 minutes at normothermia. Group II animals underwent spinal cooling by retrograde perfusion of the paravertebral veins with hypothermic (4 degrees C) saline solution during aortic occlusion. The spinal cords of group III animals were cooled with a hypothermic adenosine solution in a similar fashion. Intrathecal temperature was monitored and somatosensory evoked potentials assessed the functional status of spinal pathways. RESULTS: Spinal cooling without systemic hypothermia significantly improved neurologic Tarlov scores in group III (4.8 +/- 0.2) and group II (3.8 +/- 0.4) when compared with group I scores (1.3 +/- 0.6) (P <.001). Furthermore, 5 of the 6 animals in group III displayed completely normal neurologic function, whereas only one animal in group II and no animals in group I did (P =.005). Somatosensory evoked potentials were lost 10.6 +/- 1.4 minutes after ischemia in group I. In contrast, spinal cooling caused rapid cessation of neural transmission with loss of somatosensory evoked potentials at 6.9 +/- 1.2 minutes in group II and 7.0 +/- 0.8 minutes in group III (P =.06). Somatosensory evoked potential amplitudes returned to 85% of baseline in group III and 90% of baseline in group II compared with only 10% of baseline in group I (P =.01). CONCLUSIONS: We conclude that retrograde cooling of the spinal cord is possible and protects against ischemic injury and that adenosine enhances this effect. The efficacy of this method may be at least partly attributed to a more rapid reduction in metabolic and electrical activity of the spinal cord during ischemia.

Adenosine↗
PubMed2000

Continuous spinal anesthetic technique for endovascular aortic stent graft surgery.

Endovascular aortic stent grafts were first introduced in clinical trials in 1991. Endovascular aortic stent grafts are now being used to repair thoracic and abdominal aneurysms in patients not eligible for open repair because of severe medical coexisting diseases. Previously described anesthetic techniques in the literature for aortic stent graft placement include general anesthesia, epidural anesthesia, combined single-shot spinal and epidural anesthesia, and direct local anesthesia. We report the use of a continuous spinal anesthetic technique as a viable anesthetic option for patients with severe coexisting medical diseases undergoing abdominal aortic stent graft placement.

Aged↗
PubMed2000

The safety of combined cardiac and vascular operations: how much is too much?

OBJECTIVE: The purpose of this study was to identify factors correlating with a poor outcome following combined cardiac and vascular procedures. METHODS: We reviewed 45 consecutive patients undergoing combined cardiac and vascular operations. These included cardiac/CEA (n=27), cardiac/AAA (n=13), cardiac/AAA/one other vascular reconstruction (n=4), and cardiac/renal artery bypass (n=1). Group I included all patients with no morbidity or mortality (n=41) and Group II included patients who died or suffered significant morbidity (stroke, renal failure) (n=4). RESULTS: Overall mortality was 4.4% (2/45). These two patients underwent cardiac surgery combined with two additional vascular procedures (cardiac/AAA/other). In patients undergoing cardiac/CEA or cardiac/AAA, there were no deaths and one stroke (contralateral to CEA). Group II had significantly decreased ejection fraction (39%+/-6% vs 52%+/-1%) and an increased number of procedures (2.75 vs 2.04). CONCLUSIONS: Combined cardiac surgery and vascular reconstruction can be performed safely. However, multiple vascular reconstructions or the presence of decreased ejection fraction increased operative risk.

Aged↗
PubMed2000

Intensive care is cost-effective in carotid endarterectomy.

The purpose of this study was to analyze the utilization, cost profile, and predictors of intensive care unit (ICU) services after carotid endarterectomy. A retrospective medical record review of all patients undergoing isolated carotid endarterectomy by a vascular surgery service at one university hospital during a 12-month period was performed. Eighty-four patients undergoing 91 carotid endarterectomies were identified for review. All carotid endarterectomy patients at the authors' institution were routinely admitted to an ICU postoperatively. Sixty-five of the 91 patients (71.4%) required ICU interventions, the majority of which were intravenous antihypertensive therapy. There were no deaths in the group. There was one non-fatal stroke (1.1%), and one non-fatal myocardial infarction (1.1%). There were three reoperations (3.3%): two for hematoma and one for a change in neurological status. One patient required reintubation. Five of the six major adverse events after carotid endarterectomy occurred within 12 hours postoperatively. No preoperative factors predicted a significant risk for complications following carotid endarterectomy. There is no reliable predictor that carotid endarterectomy patients will require postoperative interventions or develop adverse outcomes. Mandatory intensive care immediately after carotid endarterectomy upholds high safety standards, avoids the uncertainty of preoperative ICU planning, and avoids the high cost of a recovery room stay to determine the need for intensive care. In addition, costs may be further reduced as the ICU length of stay may be decreased if there are no necessary interventions or complications after 12 hours of intensive care.

Aged↗
PubMed2000

Lower extremity arteriography with use of iodinated contrast material or gadodiamide to supplement CO2 angiography in patients with renal insufficiency.

PURPOSE: To determine if the use of nonionic contrast material, as compared to the use of gadodiamide to supplement carbon dioxide angiography in patients with peripheral vascular disease (PVD) and chronic renal insufficiency (CRI), results in significant worsening of renal function. MATERIALS AND METHODS: Lower extremity angiographic procedures (diagnostic and diagnostic/intervention) were performed in 40 patients with CRI (baseline serum creatinine [Cr] > 1.5 mg/dL) using CO2 alone or CO2 supplemented with the use of either nonionic contrast material or gadodiamide (up to 0.4 mmol/kg). Serum creatinine levels were obtained before the procedure and at 48 hours after the procedure. The peak Cr level was also determined for patients with a significant (> 0.5 mg/dL) Cr elevation. RESULTS: Forty-two lower extremity angiographic procedures (19 diagnostic and 23 diagnostic/interventions) were performed in 40 consecutive patients from August 1997 to October 1998, with a mean preprocedure Cr of 2.2 mg/dL and a mean postprocedure Cr of 2.4 mg/dL. Twenty-five of the 40 patients (63%) had diabetes mellitus. Fifteen procedures, including six interventions, were performed utilizing CO2 and nonionic contrast material in 15 patients. Six of these 15 patients (40%) demonstrated a Cr increase > 0.5 mg/dL at 48 hours. Seven procedures, including two interventions, were performed with CO2 alone in seven patients. No patients in this group demonstrated an increase in serum creatinine of greater than 0.5 mg/dL at 48 hours. Twenty procedures, including 15 interventions, were performed with CO2 and gadodiamide in 18 patients. In one of these 20 procedures (5%) there was an increase in Cr > 0.5 mg/dL at 48 hours The difference in worsening renal function for the nonionic contrast group (six of 15) compared with the CO2/gadodiamide group (one of 20) was statistically significant (P = .03). When comparing the use of CO2 and nonionic contrast material versus CO2 alone and with gadodiamide (six of 15 versus one of 27), the difference is also statistically significant (P < .01). The average volume of supplemental contrast material was similar in the nonionic contrast material and gadodiamide groups, as was the average volume of supplemental nonionic contrast material in the six patients with an increased Cr. CONCLUSION: The use of small volumes of nonionic contrast material to supplement CO2 angiography in patients with PVD and CRI can be associated with a significant increased risk of worsening renal function when compared to angiography performed with CO2 alone or CO2 and gadodiamide.

Aged↗
PubMed2000

Epidermal growth factor augments postpneumonectomy lung growth.

OBJECTIVE: Epidermal growth factor has been shown to play an important role in prenatal and postnatal lung development, but little is known about its effects on adult lung growth. We hypothesized that postpneumonectomy compensatory lung growth can be augmented by the administration of epidermal growth factor. METHODS: Adult Sprague-Dawley rats were divided into 3 groups. Sham left thoracotomy was performed in the first group (group C), left pneumonectomy in the second group (group P), and left pneumonectomy with administration of epidermal growth factor (0.2 microgram/g body weight intraperitoneally, at 72-hour intervals) in the third group (group E). The right lung growth was studied in each group 1, 3, 5, 10, and 21 days after the operation. Lung weights (in grams) and volumes (in milliliters) were expressed as a ratio to the total body weight (in kilograms) (lung weight and volume indices). Epidermal growth factor receptor was quantitated by using Western blotting. RESULTS: Using analysis of variance and contrast analysis, we noted a significant increase in lung weight index in group E versus group P rats at 3 days (3.08 vs 2.75; P =.034) and 21 days (4.62 vs 3.61; P =.006). Lung volume index was significantly increased in group E versus group P rats at 5 (16.98 vs 15.09), 10 (24.48 vs 18.81), and 21 (28.54 vs 21.01) days (P <.001). Epidermal growth factor receptor was noted to be up-regulated in the lungs of animals that received exogenous epidermal growth factor. CONCLUSIONS: This study demonstrates that administration of exogenous epidermal growth factor has a significant effect on postpneumonectomy lung growth. This process may be mediated by an up-regulation of growth factor receptor expression in the contralateral lung.

Analysis of Variance↗
PubMed2000

Retrograde venous perfusion with hypothermic saline and adenosine for protection of the ischemic spinal cord.

PURPOSE: Spinal cord injury and the resultant postoperative paraplegia are devastating complications of thoracic aortic surgery, for which no widely accepted protective interventions exist. We hypothesized that retrograde venous perfusion-cooling of the spinal cord with a hypothermic saline and adenosine solution would protect it from ischemic injury caused by thoracic aortic occlusion. METHODS: Adult domestic swine of either sex (weight range, 20 to 30 kg) were intubated and ventilated. A left thoracotomy was performed. The accessory hemiazygous vein was divided, and a catheter was inserted distally. The aorta was clamped at the left subclavian artery. The venous catheter was not used in the animals in the control group (n = 7); in the animals in the experimental group (n = 7), a cold (4 degrees C) saline and adenosine solution was infused into the accessory hemiazygous vein. After 30 minutes, the clamp and catheter were removed, and the chest was closed. A blinded observer evaluated the animals' hind-leg motor activity 24 hours later. The Tarlov scale was used: 0, complete paralysis; 1, minimal movement; 2, stands with assistance; 3, stands alone; 4, weak walk; 5, normal gait. The animals' rectal temperatures were measured at the end of the experiment, and blood pressure was measured throughout. Two other groups were studied to assess the effect of the intervention on spinal cord temperature. RESULTS: The animals in the control group had a mean Tarlov score of 1.7 +/- 0.6; the animals in the experimental group had a mean Tarlov score of 4.9 +/- 0.1 (P <.01). The animals in the experimental group had a significantly greater drop in spinal cord temperature than those in the control group (4. 05 +/- 0.6 degrees C vs 0.58 +/- 0.12 degrees C; P <.01). No significant difference in rectal temperatures was found, nor did any arrhythmias or hypotensive episodes occur in either group. Perfusion of the spinal cord was confirmed with angiography by using this approach. CONCLUSION: Retrograde venous perfusion-cooling of the spinal cord with a hypothermic saline and adenosine solution protects the cord from ischemic injury caused by clamping of the thoracic aorta.

Adenosine↗
PubMed2000

Does the additive risk of mitral valve repair in patients with ischemic cardiomyopathy prohibit surgical intervention?

OBJECTIVE: To assess the surgical risk of additional mitral valve repairs in patients with ischemic cardiomyopathy. SUMMARY BACKGROUND DATA: Severe mitral regurgitation in patients with ischemic cardiomyopathy increases the death rate and symptomatic status. The 1-year survival rate for medical therapy in this subset of patients is less than 20%. Transplantation is usually not feasible because of donor shortage and death while on the waiting list. METHODS: To assess additive risk, a retrospective chart review from 1993 to 1998 was performed comparing patients with ischemic cardiomyopathy (ejection fraction [EF] <25%) and severe mitral regurgitation undergoing mitral valve repair and coronary artery bypass graft operations with patients with an EF of <25% undergoing coronary artery bypass graft alone. These groups were also compared with 140 patients receiving heart transplants since 1993 (group 3). RESULTS: The overall hospital death rate for group 1 was 6.3%. The one death occurred 2 weeks after surgery secondary to sepsis. This was not significantly different from the death rate of 4.1% in group 2. In group 1, there were two deaths at 1 year (87% survival rate), one related to heart failure. One patient was New York Heart Association (NYHA) class IV at 1 year; the remainder of patients were NYHA class I-II. These results were not significantly different than the 8% death rate noted with transplantation. There was no change in EF and minimal residual mitral regurgitation in group 1 based on postoperative transesophageal echocardiography, whereas group 2 had an average 11.7% improvement in EF. CONCLUSIONS: Previously, severe mitral regurgitation in the setting of ischemic cardiomyopathy has been associated with poor survival. In these authors' experience, repairing the mitral valve along with coronary artery bypass grafting does not increase the surgical risk, yields improvement in symptomatic status, and compares favorably to coronary artery bypass grafting alone and cardiac transplantation. However, the lack of change in EF in these patients probably represents an overestimation of the EF before surgery secondary to severe mitral regurgitation.

Cardiomyopathy, Dilated↗
PubMed2000

Autonomous decision-making: a data mining approach.

The researchers and practitioners of today create models, algorithms, functions, and other constructs defined in abstract spaces. The research of the future will likely be data driven. Symbolic and numeric data that are becoming available in large volumes will define the need for new data analysis techniques and tools. Data mining is an emerging area of computational intelligence that offers new theories, techniques, and tools for analysis of large data sets. In this paper, a novel approach for autonomous decision-making is developed based on the rough set theory of data mining. The approach has been tested on a medical data set for patients with lung abnormalities referred to as solitary pulmonary nodules (SPNs). The two independent algorithms developed in this paper either generate an accurate diagnosis or make no decision. The methodolgy discussed in the paper depart from the developments in data mining as well as current medical literature, thus creating a variable approach for autonomous decision-making.

Algorithms↗
PubMed2000

Attenuation of lung reperfusion injury after transplantation using an inhibitor of nuclear factor-kappaB.

A central role for nuclear factor-kappaB (NF-kappaB) in the induction of lung inflammatory injury is emerging. We hypothesized that NF-kappaB is a critical early regulator of the inflammatory response in lung ischemia-reperfusion injury, and inhibition of NF-kappaB activation reduces this injury and improves pulmonary graft function. With use of a porcine transplantation model, left lungs were harvested and stored in cold Euro-Collins preservation solution for 6 h before transplantation. Activation of NF-kappaB occurred 30 min and 1 h after transplant and declined to near baseline levels after 4 h. Pyrrolidine dithiocarbamate (PDTC), a potent inhibitor of NF-kappaB, given to the lung graft during organ preservation (40 mmol/l) effectively inhibited NF-kappaB activation and significantly improved lung function. Compared with control lungs 4 h after transplant, PDTC-treated lungs displayed significantly higher oxygenation, lower PCO(2), reduced mean pulmonary arterial pressure, and reduced edema and cellular infiltration. These results demonstrate that NF-kappaB is rapidly activated and is associated with poor pulmonary graft function in transplant reperfusion injury, and targeting of NF-kappaB may be a promising therapy to reduce this injury and improve lung function.

Animals↗
PubMed2000

Neuregulin-1 and human epidermal growth factor receptors 2 and 3 play a role in human lung development in vitro.

The human epidermal growth factor receptor (HER) family consists of four distinct receptors: HER1 (epidermal growth factor receptor), HER2, HER3, and HER4. Their specific activating ligands are collectively known as neuregulins (NRG). We hypothesized that one member of the NRG family, NRG-1, and the HER family would play a role in fetal lung development. To test this hypothesis, we defined NRG-1 and HER gene expression in mid-trimester human fetal lung tissue. HER2 and HER3 messenger RNA and protein were detected in the fetal lung, but HER4 expression was not detected. Immunohistochemical staining of fetal lung tissue localized HER2 and HER3 protein to the developing lung epithelium. NRG-1 expression was not found in freshly isolated human fetal lung, but it was observed in fetal lung explants after 2 d of explant culture. Immunohistochemistry of cultured human fetal lung explants revealed that NRG-1 protein was also expressed in pulmonary epithelial cells. Exposing human fetal lung to recombinant NRG-1 activated the HER receptor complex as measured by approximately 4-fold increases in receptor phosphotyrosine content. In addition, NRG-1 increased explant epithelial cell volume density approximately 2-fold (P < 0. 03); increased epithelial cell proliferation approximately 2-fold, as determined by bromodeoxyuridine labeling (P = 0.002); and reduced surfactant protein-A (SP-A) levels by 53% (P < 0.05). These data are consistent with an autocrine regulatory process mediated by NRG-1 activation of HER2/HER3 heterodimers expressed on developing human fetal lung epithelial cells. Receptor activation results in increased lung epithelial cell proliferation and volume density, and decreased SP-A production, a marker of type II pneumocyte differentiation.

Autocrine Communication↗