Manuel R. Castresana

NF-κB is required for TNF-α-directed smooth muscle cell migration

Migration of vascular smooth muscle cells (VSMC) is a crucial event in the formation of vascular stenotic lesions. Tumor necrosis factor‐α (TNF‐α) is elaborated by VSMC in atherosclerosis and following angioplasty. We investigated the role of nuclear factor‐κB (NF‐κB) in human VSMC migration induced by TNF‐α. Adenoviral expression of a mutant form of the inhibitor of NF‐κB, IκB‐αM, suppressed TNF‐α‐triggered degradation of cellular IκB‐α, inhibited activation of NF‐κB, and attenuated TNF‐α‐induced migration. Further, IκB‐αM suppressed TNF‐α‐stimulated release of interleukin‐6 and ‐8 (IL‐6 and IL‐8). Neutralization of IL‐6 and IL‐8 with appropriate antibodies reduced TNF‐α‐induced VSMC migration. Addition of recombinant IL‐6 and IL‐8 stimulated migration. Collectively, our data provide initial evidence that TNF‐α‐mediated VSMC migration requires NF‐κB activation and is associated with induction of IL‐6 and IL‐8 which act in an autocrine manner.

Incidence and clinical significance of hemidiaphragmatic paresis in patients undergoing carotid endarterectomy during cervical plexus block anesthesia

This study was designed to investigate the incidence and clinical consequences of hemidiaphragmatic paresis in patients undergoing carotid endarterectomy using cervical plexus block anesthesia. In 28 patients, diaphragmatic motion was evaluated by fluoroscopy 20 min after cervical plexus block with 1% mepivacaine. In 61% of the patients abnormalities of diaphragmatic motion were detected. These motion anomalies were associated with a statistically significant elevation of PaCO2. Gender, age, and whether the block was on the left or right side did not appear to affect the incidence of motion abnormalities after cervical plexus block anesthesia.

A new technique for placement of nasoenteral feeding tubes using external magnetic guidance

OBJECTIVE To evaluate a new technique in which a hand-held external magnet is used to maneuver nasoenteral feeding tubes through the pylorus and into the duodenum. DESIGN Prospective case series. SETTING Critical care units and medical and surgical wards of a university-affiliated community hospital. PATIENTS Thirty-five patients were entered into the study after the attending physician requested assistance in tube placement. INTERVENTIONS A standard 12-Fr, 114-cm flexible nasoenteral feeding tube was modified by inserting a small magnet into the distal tip. The tube was inserted per nares into the stomach, using traditional technique. Next, an external magnet was placed over the right upper abdominal quadrant, at the midclavicular line to attract the tube tip along the lesser curvature of the stomach, through the pyloric sphincter, and into the duodenum. Portable abdominal radiography performed immediately after the procedure confirmed the anatomic location of the tube tip. MEASUREMENTS AND MAIN RESULTS Forty-two intubations were performed in 35 patients (in seven patients, the tube had to be reinserted due to inadvertent removal or surgery). In 37 (88%) of 42 intubations, the tube was passed through the pyloric sphincter and into the duodenum on the first attempt. The mean procedure time was 15 +/- 9 mins (range 10 to 45). There were no complications related to the procedure during the study period. CONCLUSIONS This report describes a novel technique of enteral feeding tube placement, using external magnetic guidance. Transpyloric placement was achieved in 88% of cases. This reliable and convenient bedside method for rapid placement of the tube into the duodenum allows prompt and safe initiation of enteral nutrition.

Human blood vessels release tumor necrosis factor-alpha from a smooth muscle cell source

OBJECTIVES In septic shock, the principal source of increased plasma concentrations of tumor necrosis factor alpha (TNF) is considered to be the macrophage. Release from the macrophage is stimulated by bacterial lipopolysaccharide (endotoxin). We tested the hypothesis that vascular tissue also responds to endotoxin by releasing TNF. DESIGN Prospective repeated measures analysis of timed-release curves. SETTING Anesthesia research laboratory in an academic medical center. SUBJECTS With Institutional Review Board approval and patient consent, segments of internal mammary artery and saphenous vein were obtained during coronary artery bypass surgery. INTERVENTIONS None MEASUREMENTS AND MAIN RESULTS Segments of saphenous veins were incubated for 24 hrs in the presence or absence of bacterial lipopolysaccharide. At 0.5, 1, 3, 6, and 24 hrs, medium was assayed for TNF. In other experiments, smooth muscle cells were cultured from saphenous veins, incubated with our without bacterial lipopolysaccharide, and a time-course of TNF release determined. Bacterial lipopolysaccharide (20 micrograms/mL) significantly stimulated release of TNF from venous tissue in a time-dependent manner. At 0.5 hrs, TNF was undetectable in untreated tissue and was 48 +/- 8 U/g wet tissue weight in the presence of bacterial lipopolysaccharide. At 3 hrs, TNF was 43 +/- 27 U/g wet tissue weight in untreated and 388 +/- 185 U/g wet tissue weight in treated (p < .01 vs. control) tissue. Segments of internal mammary artery responded in a similar manner. In smooth muscle cells cultured from saphenous vein and internal mammary artery, bacterial lipopolysaccharide triggered the release of TNF. At 3 hrs, the release of TNF in control cells was 0.2 +/- 0.15 U/mg cell protein and 17 +/- 2 U/mg in the presence of 20 micrograms/mL of bacterial lipopolysaccharide (p < .01 vs. control). CONCLUSIONS Human blood vessels, both artery and vein, produce TNF potentially from a smooth muscle cell source in response to bacterial lipopolysaccharide.

Response of human artery, vein, and cultured smooth muscle cells to atrial and C-type natriuretic peptides

OBJECTIVES We determined the response of intracellular cyclic GMP in human arteries and veins and in smooth muscle cells cultured from these vessels to C-type natriuretic peptide in comparison with atrial natriuretic peptide. DESIGN Repeated-measures analysis of concentration-response curves. SETTING Anesthesia research laboratory. SUBJECTS Vascular smooth muscle cells from human blood vessels obtained with Institutional Review Board approval and patient consent. MEASUREMENTS AND MAIN RESULTS Segments of internal mammary artery and saphenous vein were obtained from patients undergoing coronary artery bypass surgery. Smooth muscle cells were cultured from these vessels. Concentration-response curves of intracellular cyclic GMP were determined and analyzed by two-way analysis of variance with repeated measures. In segments of intact saphenous vein, C-type natriuretic peptide was significantly more effective than atrial natriuretic peptide (16-fold increase in cyclic GMP in response to 1 microM of C-type natriuretic peptide vs. six-fold increase in cyclic GMP in response to 1 microM of atrial natriuretic peptide, p < .05). In rings of intact internal mammary artery, 1 microM of atrial natriuretic peptide (26-fold increase in cyclic GMP over basal value) was more effective than 1 microM of c-type natriuretic peptide (three-fold increase in cyclic GMP over basal value, p < .05). In cultured cells from these vessels, the pattern of response to C-type natriuretic peptide and atrial natriuretic peptide was the same as in the intact vessels. CONCLUSIONS These results indicated that human smooth muscle cells in arteries and veins express both forms of natriuretic peptide receptors but that atrial natriuretic peptide acts primarily on the artery and C-type natriuretic peptide acts predominantly on the vein. Increased concentrations of C-type natriuretic peptide could contribute to venous pooling in septic shock.

An unusual case of malignant hyperthermia during desflurane anesthesia in an African-American patient.

Implications Malignant hyperthermia is an uncommon, heritable condition triggered by anesthesia and is followed by an increase in temperature that may be fatal without prompt treatment. It is rare with desflurane and in black individuals of African descent. We present a case of malignant hyperthermia in an African-American patient during desflurane anesthesia.

Inhibition of release of tumor necrosis factor-alpha from human vascular tissue and smooth muscle cells by glucocorticoids

OBJECTIVES Based on our previous study that bacterial lipopolysaccharide stimulates release of tumor necrosis factor (TNF)-alpha from human vascular tissue and smooth muscle cells, we tested the hypothesis that release of TNF could be inhibited by pretreatment with glucocorticoids. DESIGN Prospective, repeated-measures analysis of concentration-response relationships. SETTING Academic anesthesiology research laboratory. SUBJECTS Segments of internal mammary artery and saphenous vein were obtained during coronary artery bypass surgery. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Confluent human smooth muscle cells, cultured from saphenous vein and internal mammary artery, were exposed to 20 micrograms/mL of bacterial lipopolysaccharide following pretreatment for 18 hrs with either 0.1, 1.0, or 10.0 microM of dexamethasone. At 1, 3, 6, 18, and 24 hrs, the culture medium was removed and analyzed for biologically active TNF-alpha using the L929 cell cytotoxicity assay. Smooth muscle cells exposed to bacterial lipopolysaccharide but not treated with dexamethasone served as controls. In control internal mammary cells, bacterial lipopolysaccharide stimulated TNF-alpha release in a time-dependent manner to a peak of 36 +/- 2.3 U/mg of cell protein at 6 hrs, compared with 0.7 +/- 0.3 U/mg of cell protein in cells not exposed to lipopolysaccharide. Dexamethasone inhibited bacterial lipopolysaccharide-stimulated release at all time points in a concentration-dependent manner. For instance, at 6 hrs, TNF-alpha was 12 +/- 2.2, 6.9 +/- 1.7, and 2.3 +/- 0.9 U/mg of cell protein for cells pretreated with 0.1, 1.0, and 10.0 microM of dexamethasone, respectively (p < .05 vs. control). In separate experiments, segments of internal mammary artery and saphenous vein were obtained from five patients who received 1 g of methylprednisolone intravenously during induction of anesthesia, and from seven patients who did not receive methylprednisolone. Bacterial lipopolysaccharide induced release of TNF-alpha from vascular tissues of untreated patients in a time-dependent manner (e.g., 733 +/- 44 U/g of tissue at 6 hrs in saphenous vein). In contrast, in patients treated with methylprednisolone, bacterial lipopolysaccharide did not stimulate release from vascular tissues incubated for up to 24 hrs. CONCLUSIONS These results indicate that human vascular tissue, particularly the smooth muscle cell, may be a source of TNF-alpha and that glucocorticoids inhibit release stimulated by bacterial lipopolysaccharide.

Use of the Laryngeal Mask Airway During Thoracotomy in a Pediatric Patient with Cri-du-Chat Syndrome

Cri-du-chat syndrome, first described in 1963, is a genetic disorder caused by an abnormality of the Number 5 Group B chromosome (1). It is characterized by the presence of numerous congenital anomalies affecting multiple organ systems. A defect in the larynx is responsible for the characteristic cry that gives the name to the syndrome. We report a case in which the laryngeal mask airway (LMA) was utilized in a patient with cri-du-chat syndrome associated with an abnormal upper airway after traditional techniques of endotracheal intubation had failed. A 15-mo-old, 7.2-kg black male with cri-du-chat syndrome required general anesthesia for ligation of a patent ductus arteriosus (PDA). His past medical history included gastroesophageal reflux diagnosed shortly after birth that required a Nissen fundoplication repair at 27 days of age. On the morning of surgery for the PDA, routine noninvasive monitors were applied for blood pressure, electrocardiogram, 0, saturation, and temperature. Preparations were made in the event of a difficult intubation, i.e., fiberoptic bronchoscope and LMA. Anesthesia was then induced with oxygen and halothane by mask. Ventilation was easily accomplished by gentle manual bag compression, and a 22-g intravenous line was then inserted. Oral intubation with a 3.5and a 4-mm endotracheal tube (Portex, Keene, NH) was attempted several times by a pediatric anesthesiologist and a pediatric surgeon without success. As attempts progressed, bag-mask ventilation became progressively more difficult although adequate ventilation and oxygenation could be maintained. A decision was made to perform a fiberoptic intubation. However, this did not succeed because bleeding and edema impaired visualization of the anatomic structures. A Number 1 LMA (Intavent@; Gensia Pharmaceutical Inc., San Diego, CA) was then inserted without difficulty. Proper positioning was confirmed clinically by bilateral breath sounds, chest movement, presence of expired CO,, and a Sao, of 100%. Ventilation and oxygenation could then be easily maintained. Consequently, it was decided to proceed with the surgery. The patient was placed in the right lateral position, and ventilation and oxygenation were monitored for 5 min. Oxygen saturation remained 100% with a FIO~ of 50%. Anesthesia was maintained with isoflurane and fentanyl (4 pg/kg). After the thoracotomy incision was made, the patient was paralyzed with 0.06 mg/kg of vecuronium and mechanically ventilated with pressure control mode. Oxygen saturation and end-tidal Pco, remained 100% and 3 8 4 2 mm Hg, respectively, for the duration of the procedure. The patient was transferred to the postanesthesia care unit with the LMA in place. When the patient was fully awake, the LMA was removed without complications. The postoperative recovery was uneventful, and he was discharged from the hospital on the fifth postoperative day. Cri-du-chat syndrome is a rare genetic anomaly associated frequently with airway abnormalities, e.g., micrognathia, dysmorphism, and laryngeal structural defects (2,3). In our patient many of the classical findings of the syndrome were present. However, the fact that this patient underwent surgery at 27 days of age without apparent anesthetic complications, and the lack of documentation on the patient records of difficult intubation at that time, led us to initially attempt an inhalation induction followed by orotracheal intubation. After that failed, fiberoptic intubation was the most rational choice since the airway and oxygenation could be maintained, but visualization was difficult because of the trauma inflicted by the repetitive laryngoscopies. The next logical step would have been to awaken the patient and postpone the surgery, but, because bag-mask ventilation was becoming progressively more difficult, we chose to place a Number 1 LMA to improve ventilation. The facts that ventilation was improved and that fiberoptic intubation via the LMAcould be attempted if necessary prompted us to proceed with surgery. Because of the nature of this procedure, we chose to paralyze the patient with a short-acting muscle relaxant and to use controlled ventilation with peak inspiratory pressure below the LMA seal pressure of 20 cm H,O. This was sufficient to maintain adequate ventilation and oxygenation. The LMA has been used successfully for emergency airway management in adult and pediatric patients undergoing different surgical procedures (4-6). This is the first report of the use of the LMA in a patient with cri-du-chat syndrome undergoing PDA repair in which endotracheal intubation by conventional techniques failed. We believe that the clinical circumstances surrounding this case justified our decision to proceed with surgery with the LMA in place. However, it is important to emphasize that the lack of prospective studies evaluating the safety of the LMAduring thoracotomy and the potential risk of aspiration make its routine use during this type of procedure inadvisable at the present time. Manuel R. Castresana, MD Sturla Stefansson, MD Angel R. Cancel, MD Kelly J. Hague, CRNA Deprtiiieizt of Anestliesiokiggy Medical Center C J ~ Ceritrnl Georgia Mercer Uniuersit!y Sclzool of Medicine Mncon, G A 31201

Stimulation of β-adrenergic receptors inhibits the release of tumor necrosis factor-α from the isolated rat heart

OBJECTIVES: Beta-adrenergic receptor agonists such as isoproterenol inhibit production of tumor necrosis factor (TNF)-alpha in a number of cell types. Because the heart is a source of TNF-alpha, we hypothesized that isoproterenol would inhibit cardiac production of the cytokine. DESIGN: Analysis of cardiac release of TNF-alpha. SETTING: Medical research laboratory. SUBJECTS: Rats. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: With the approval of the Institutional Animal Care and Use Committee, rats were anesthetized and hearts were removed and perfused. After 30 mins, bacterial lipopolysaccharide (LPS) with or without isoproterenol was infused for 60 mins. At 30, 60, 90, 120, and 150 mins, coronary flow was measured and coronary effluent was analyzed for TNF-alpha. Cardiac production of TNF-alpha was expressed as pg/min. Cyclic adenosine monophosphate (AMP) in the coronary effluent was measured. TNF-alpha messenger RNA was determined in ventricular tissue. After 30 mins, TNF-alpha was undetectable in the coronary effluent However, 60 mins after the initiation of LPS infusion, TNF-alpha release was 875+/-255 pg/min and increased to 2164+/-721 pg/min at 150 mins. Simultaneous infusion of isoproterenol with LPS stimulated cyclic AMP release and inhibited TNF-alpha production. For instance, at 60 and 150 mins, TNF-alpha release was 75+/-38 and 58+/-29 pg/min, respectively (p < .05 vs. LPS alone). Simultaneous infusion of isoproterenol with LPS blocked the induction of TNF-alpha messenger RNA by LPS. Isoproterenol, begun 30 mins after the initiation of LPS infusion, still suppressed LPS-stimulated TNF-alpha release by 95% at 150 mins. Similar results were obtained with norepinephrine. CONCLUSIONS: Activation of beta-adrenergic receptors inhibits cardiac TNF-alpha release. This implies that cytokine production by the heart is inhibited by the sympathetic nervous system. In heart failure, the cardiac response to the sympathetic nervous system is impaired. This impairment may play a role in the high plasma levels of TNF-alpha found in heart failure.

Isoproterenol Inhibits Transcription of Cardiac Cytokine Genes Induced by Reactive Oxygen Intermediates

Background Cytokines such as tumor necrosis factor &agr; (TNF-&agr;) are produced by the myocardium in heart disease and might be stimulated by reactive oxygen. In some cell types, cyclic adenosine monophosphate (AMP) inhibits TNF-&agr; production. The authors tested the hypothesis that stimulation of cardiac &bgr;-adrenergic receptors would inhibit cytokine gene transcription induced by reactive oxygen. Methods Rat hearts were perfused with buffer containing hypoxanthine. Reactive oxygen intermediates were generated by infusion of xanthine oxidase. Myocardial mRNA encoding 11 cytokines was determined. TNF-&agr;, interleukin-6, and cyclic AMP were measured in the coronary effluent. Results In control hearts, of the screened RNA, only mRNA encoding interleukin-1&bgr;, -4, and -6 was detected. Stimulation with hypoxanthine–xanthine oxidase (HX–XO) induced detectable mRNA for TNF-&agr; and interleukin-5 and increased mRNA band density for interleukin-1&bgr;, -4, and -6. Simultaneous infusion of isoproterenol inhibited HX–XO-stimulated cytokine gene expression and caused release of cyclic AMP into the coronary effluent. In control hearts, TNF-&agr; was not detected in the coronary effluent. After HX–XO administration, TNF-&agr; was reliably detected at 60 min and interleukin-6 at 90 min. Simultaneous infusion of isoproterenol inhibited TNF-&agr; and interleukin-6 release. Inclusion of propranolol in the perfusion buffer blocked the isoproterenol-induced inhibition of HX–XO-stimulated TNF-&agr; release and release of cyclic AMP into the coronary effluent. In addition, elevating myocardial cyclic AMP with forskolin also blocked release of TNF-&agr; stimulated by HX–XO. Finally, delaying infusion of isoproterenol until 30 min after HX–XO administration still suppressed release of TNF-&agr;. Conclusions Reactive oxygen species activate cytokine gene transcription in the myocardium. The sympathetic nervous system, acting through &bgr;-receptors to elevate myocardial cyclic AMP, regulates cardiac cytokine production by inhibition of transcription.