Altered hepatic gene expression in fecal peritonitis: changes in transcription of gluconeogenic, beta-oxidative, and ureagenic genes.

Sepsis alters energy production and utilization by the liver. Changes in both metabolic pathways that produce substrate (gluconeogenesis or ketogenesis) for organism-wide consumption or provide an alternative source of fuel for the liver (beta-oxidation and amino acid metabolism) have been identified. In this study, we test the hypothesis that these changes occur via an alteration in the transcription of key enzymes within each pathway. Male Sprague-Dawley rats were made septic using cecal ligation and single puncture with sham operated animals serving as controls. Hepatic tissue was harvested at 0, 3, 6, 16, 24, 48, and 72 h had either total RNA or hepatic nuclei were isolated. Using Northern blot hybridization analysis, the steady-state levels of phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, carnitine palmitoyl transferase II, acetyl coenzyme A-acyltransferase, and ornithine transcarbamylase mRNAs were determined. Using transcript elongation analysis, the rate of transcription of each gene was investigated. Relative to control, steady-state mRNA levels and rates of transcription for all five genes were decreased by ligation and single puncture. These decreases were persistent, with only partial recovery of either mRNA levels or transcription rates at 72 h. These findings could explain in part the long-term alterations in gluconeogenesis, beta-oxidation, and ureagenesis observed in sepsis. More importantly, decreased transcription of certain genes seems to be a characteristic of sepsis-induced changes in hepatic function. Understanding the mechanisms that decrease transcription also may explain other aspects of sepsis in the liver and other organ systems.

Reciprocal expression of phosphoenolpyruvate carboxykinase and acute phase genes during acute inflammation.

Part of the hepatic response to injury is mediated by the expression of a gene family known as acute phase genes. Expression of acute phase genes is induced by the presence of cytokines in the circulation such as tumor necrosis factor alpha, interferon gamma, and interleukins-1 and -6. Simultaneous with the transcription of acute phase genes, there is a decrease in the expression of other genes such as albumin. In the present study, we report the decrease in transcription of the gene coding for phosphoenolpyruvate carboxykinase (PEPCK), a key regulatory enzyme in the gluconeogenic pathway, in rat liver during an acute inflammatory state induced by bacterial endotoxin. Steady-state mRNA levels of PEPCK decrease 3 h after endotoxin injection, returning to 70% of normal levels after 24 h. This decrease in PEPCK mRNA levels was due to a decline in the rate of transcription of the gene, most likely mediated by an increase in the circulating levels of insulin. However, expression of the PEPCK gene was not induced by an increase in the cellular levels of cAMP during inflammation. Such a lack of response to cAMP may be due to the inactivation of, or decrease in, the levels of the transcriptional factor(s) responsible for PEPCK transcription.

Hepatic gene expression and cytokine responses to sterile inflammation: comparison with cecal ligation and puncture sepsis in the rat.

Inflammatory stimulation of hepatic acute phase protein expression is, in part, modulated by tumor necrosis factor-alpha (TNFalpha), interleukin-1beta (IL-beta), and IL-6. These cytokines also may mediate some aspects of the persistent inflammation and metabolic dysregulation of sepsis. Cecal ligation and puncture (CLP) sepsis in male Sprague-Dawley rats inappropriately decreases hepatocellular transcription of phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G6Pase), carnitine palmitoyltransferase II (CPTII), acetyl CoA acyltransferase (ACA), and ornithine transcarbamylase (OTC). We hypothesize that 1) transcriptional reprogramming does not occur after simple inflammation induced by subcutaneous turpentine injection, 2) the pattern of acute phase gene expression after CLP differs from that following turpentine injection, and 3) the different responses reflect differences in the intrahepatic activity of TNFalpha/IL-1beta or IL-6. Gene expression, transcription factor activity, and cytokine abundance were determined after either a subcutaneous injection of turpentine or CLP. After turpentine injection, PEPCK, G6Pase, CPTII, ACA, and OTC expression were unchanged, different from previously reported data following CLP. Both turpentine injection and CLP increased expression of TNFalpha/IL-1beta-regulated alpha1-acid glycoprotein, and IL-6-regulated alpha2-macroglobulin and decreased expression of transthyretin (a negative acute phase protein). However, the magnitude and temporal pattern of expression differed. Turpentine injection increased the activity of the TNFalpha/IL-1beta-linked transcription factor NF-kappaB and the intrahepatic abundance of TNFalpha in a manner similar to that observed after CLP but only slightly altered the activity of the IL-6-linked transcription factor Stat-3 and intrahepatic IL-6 abundance. This differed significantly from observations after CLP. We conclude that CLP-induced alterations in hepatic gene expression may reflect differences in IL-6 activity.

Intraabdominal sepsis down-regulates transcription of sodium taurocholate cotransporter and multidrug resistance-associated protein in rats.

Hepatic dysfunction in sepsis is characterized by hyperbilirubinemia and intrahepatic cholestasis. We hypothesize that sepsis causes decreased hepatic transcription of the bile acid transporter sodium taurocholate cotransporter (Ntcp) and the organic anion transporter multidrug resistance-associated protein (Mrp2) and that interleukin (IL)-6 is important in the down-regulation of Ntcp and Mrp2 expression. Male Sprague-Dawley rats underwent induction of mild, nonlethal sepsis by cecal ligation and single puncture (CLP) or fulminant sepsis by cecal ligation and double puncture (2CLP). Hepatic transcription of Ntcp and Mrp2 rapidly decreased after CLP or 2CLP. Seventy-two hours later, transcription was 60% of baseline in CLP and 14% of baseline in 2CLP. Serum bilirubin was elevated from 24 h onward and cholestasis was observed on fixed liver specimens at 24, 48, and 72 h after 2CLP but not after CLP. Steady-state Ntcp and Mrp2 mRNA was decreased in IL-6-treated cultured hepatocytes and in normal rats given 1 mg/kg intravenous IL-6. We conclude that 1) Ntcp and Mrp2 transcription is down-regulated transiently after CLP and persistently after 2CLP; 2) 2CLP results in hyperbilirubinemia and cholestasis, in part due to persistently decreased transcription of Ntcp and Mrp2; and 3) altered Ntcp and Mrp2 transcription is mediated in part by IL-6.

Cecal ligation and double puncture impairs heat shock protein 70 (HSP-70) expression in the lungs of rats.

Induction of the heat shock response may improve outcome from pathophysiological disturbances. This improvement is associated with and believed to result from expression of heat shock protein (HSP)-70. Therefore, we examined the temporal expression of HSP-70 in an animal model of acute respiratory distress syndrome (ARDS) secondary to fecal peritonitis. Specifically, we hypothesize that sepsis in rats impairs pulmonary HSP-70 expression. ARDS was induced in adolescent rats via cecal ligation and double puncture (2CLP). Sham-operated animals served as controls. Lung tissue was collected 0, 3, 6, 16, 24, and 48 h after 2CLP and sham operation. Northern blot hybridization analysis was performed to detect steady-state HSP-70 messenger ribonucleic (mRNA) levels. HSP-70 protein levels were determined via immunoblotting and immunohistochemistry. Mortality after 2CLP was 50% at 24 h and 75% at 48 h. Northern blot hybridization analysis revealed no significant change in steady-state HSP-70 mRNA levels in lung at any time after 2CLP. HSP-70 steady-state mRNA levels increased after sham operation and was higher than values in 2CLP at 6, 16, and 24 h. HSP-70 protein levels did not change over time in either group. Thus, the expression of HSP-70 does not change after 2CLP. Although lack of an increase in protein levels may be adaptive after sham operation, it is not appropriate after 2CLP. Therefore, failed HSP-70 expression represents a form of pulmonary epithelial dysfunction that may contribute to lung injury in sepsis.

Substance abuse-related admissions to adult intensive care.

The frequency of adult surgical and medical intensive care unit (ICU) admissions related to substance abuse was determined at a large community, trauma, and tertiary referral hospital. Of 435 ICU admissions, 14 percent (95 percent confidence interval [CI], 5 to 23 percent) were tobacco related generating 16 percent of costs, 9 percent (95 percent CI, 0 to 18 percent) were alcohol related generating 13 percent of costs, and 5 percent (95 percent CI, 0 to 14 percent) were illicit drug related generating 10 percent of costs. In all, 28 percent (95 percent CI, 20 to 36 percent) of ICU admissions generating 39 percent of costs were substance abuse related. Substance abuse-related admissions were significantly longer and more costly than admissions not related to substance abuse (4.2 days vs 2.8 days, p = 0.004; $9,610 vs $5,890, p = 0.001). Frequency of substance abuse-related admission was linked with the patient's insurance status (Medicare, private insurance, uninsured). In the uninsured group, 44 percent of admissions were substance abuse related (95 percent CI, 35 to 52 percent), significantly higher than in the private insurance and Medicare groups, and generating 61 percent of all ICU costs in the uninsured group. Large fractions of adult ICU admissions and costs are substance abuse related, particularly in uninsured patients.

Molecular biology of circulatory shock. Part II. Expression of four groups of hepatic genes is enhanced after resuscitation from cardiogenic shock.

Despite an initially successful resuscitation from circulatory shock, multiple organ failure (MOF) develops in some patients. The marked biochemical alterations associated with shock and MOF include clinically important changes in gene expression, such as altered rates of albumin and procoagulant synthesis. To characterize the MOF-associated changes at the cellular level, sequential liver biopsies were obtained from a swine model of cardiogenic shock associated with MOF. Preshock and postresuscitation biopsies were used not only to create a complementary DNA (cDNA) library but also to screen, to confirm, and, in nine out of 12 cases, to specifically identify genes whose expression is enhanced at least fivefold after resuscitation. The twelve genes thus characterized can be separated according to function into distinct groups, including the acute-phase genes and the heat-shock genes. Expression of acute-phase genes is liver specific and is essential for systemic homeostasis; heat-shock gene expression is generic to all cells and important for intracellular homeostasis.

Physiology and metabolism in isolated viral septicemia. Further evidence of an organism-independent, host-dependent response.

The hypothesis has been advanced that the human systemic septic response is a function of the host and not of the type of infecting organism. Metabolic and physiologic data from five immunosuppressed transplant recipients with isolated cytomegaloviral sepsis and viremia were prospectively evaluated. Serial cultures obtained from lung, sputum, urine, wound, blood, and invasive lines were positive for virus and negative for bacterial or fungal pathogens. The results were compared with two data banks derived from either victims of multiple trauma without sepsis or surgical patients with early bacterial or fungal sepsis. Statistically significant differences between the patients and the nonseptic reference group were noted for cardiac index, total peripheral resistance, arteriovenous oxygen content difference, oxygen consumption, and levels of triglycerides, proline, phenylalanine, tyrosine, alpha-aminobutyrate, and alanine. No such differences were present for these data compared with the septic reference group. Physiologic data obtained just before death in three patients indicated a failure of oxygen transport. It appears that the systemic septic response to viral agents is indistinguishable by physiologic and metabolic criteria from that resulting from bacterial or fungal agents.

Anticonvulsant prophylaxis in neurological surgery.

Seizures complicate many neurosurgical diseases and, in many situations, their prevention is desirable. In an attempt to arrive at a rational approach to the purely prophylactic administration of anticonvulsants, existing data pertaining to four topics were examined: the danger posed by a single seizure, the incidence of seizures in a given disease state, the ability of anticonvulsant medication to prevent seizures, and the risks and benefits associated with pharmacological intervention. In general, where the risk of seizure exceeds 10 to 15% or where a single seizure may have disastrous consequences, anticonvulsant prophylaxis is recommended.

Traumatic subarachnoid-pleural fistula.

Subarachnoid-pleural fistula is a rare condition; only 18 cases have been reported. The 19th case of subarachnoid-pleural fistula, which followed a small caliber gunshot wound, is reported. Diagnosis was made via radionuclide scan, and primary operative repair was necessitated by the failure of conservative management. A review of the literature reveals several means of diagnosing this disorder, as well as a number of management alternatives.

Paranasal sinusitis: a common complication of nasotracheal intubation in neurosurgical patients.

Sinusitis secondary to nasotracheal intubation has not been reported to occur in neurosurgical patients. Over a 1-year period, 11 patients admitted to the Intensive Care/Trauma Unit at St. Paul Ramsey Medical Center developed this entity. The mean age of these patients was 36 +/- 4 years; 7 were trauma victims, 3 had each had a subarachnoid hemorrhage, and 1 had suffered hypertensive hemorrhage. The patients presented with fever of unknown origin (FUO) and evidence of persistent hypermetabolism without an obvious cause. In 8 cases, the diagnosis was not suspected until mucopurulent nasal discharge was noted. Three additional cases were evaluated for suspected sinusitis before the occurrence of discharge. The mean duration of intubation before the diagnosis of sinusitis was 7.8 +/- 1.5 days. The diagnosis was confirmed by sinus films with a Waters view in 7 cases or by computed tomographic scanning in 4 cases and by bacteriological cultures. Two cases involved only the maxillary sinus on the side of intubation; the rest were polysinusites. The organisms involved included gram-positive and gram-negative species; all were polymicrobial with a single organism predominant. Secondary pulmonary involvement was common, and 4 patients revealed a bacteremia consistent with the major sinus organism. One patient developed septic shock. Treatment involved either orotracheal intubation or tracheostomy. This was curative in all cases. It is concluded that neurosurgical patients nasally intubated are at risk for sinusitis, which can have untoward effects such as septicemia or pulmonary infection. A high degree of suspicion will permit early diagnosis and treatment.

Physiological and metabolic response to isolated closed-head injury. Part 2: Effects of steroids on metabolism. Potentiation of protein wasting and abnormalities of substrate utilization.

In order to determine the effects of steroid administration on the metabolic response to isolated closed-head injury, a longitudinal study was performed. Metabolic indices were prospectively evaluated for the first 5 days postinjury in six patients who received steroids and 10 patients who did not. Patients were carefully screened to eliminate those with associated injuries as well as those with abnormalities due to sepsis. Other than steroid administration, a uniform treatment regimen was used in both groups. Metabolic indices measured on postinjury Days 1, 3, and 5 were analyzed. In addition, data were compared to results in large data banks obtained both from overnight-fasted patients (fasted controls) and from polytrauma victims (stressed controls). Both treatment groups were comparable with respect to age, mean Glasgow Coma Scale scores on admission and on Day 5, and initial intracranial pressure. Metabolic data indicated significantly higher levels of nitrogen excretion and somatic protein mobilization in steroid-treated patients than in patients not receiving steroids. In both groups, glucose levels, the lactate/pyruvate ratio, and branched-chain amino acid levels (all metabolic indices that correlate well with level of stress) initially corresponded to values for stressed controls. By Day 5, values for these variables were similar to fasted controls for the group not receiving steroids. In patients receiving steroids, however, the data remained similar to those for stressed controls. It is concluded that steroids prolong the metabolic abnormalities associated with the initial phase of head injury. In view of inconclusive data regarding benefit from steroid administration, serious questions must be raised regarding the use of these catabolic agents in this setting.

Physiological and metabolic response to isolated closed-head injury. Part 1: Basal metabolic state: correlations of metabolic and physiological parameters with fasting and stressed controls.

Studies of the metabolic and physiological response to closed-head injury have intimated the presence of persistent hypermetabolism. To more fully define and evaluate the metabolic response to head trauma, a prospective study was conducted in patients with isolated closed-head injuries. Metabolic and cardiopulmonary data were obtained for a 7-day period. Patients with multiple injuries or infections, or those who received steroids, were excluded. The basic treatment regimen utilized hyperventilation, bed rest with head elevation, intracranial pressure monitoring, mild fluid restriction, and mannitol as needed. No exogenous nutritional support was given. Intrastudy trends and comparsion with data from unstressed fasting patients and stressed patients were noted. Mean Glasgow Coma Scale scores were 4.4 +/- 1.5 initially, but rose to a mean of 8.2 +/- 3.7 by Day 7. While the responses of cardiac index, CO2 production, lactate/pyruvate ratio, and arteriovenous O2 content difference (AVO2D) were initially elevated, these parameters declined over the course of 7 days. The AVO2D was equivalent to the fasting level by Day 5. Metabolic data, including most amino acid levels in plasma, showed an initial equivalence to stress control levels and a pattern similar to that in non-stressed control subjects by Day 7. Nitrogen and 3-methyl histidine excretion were persistently elevated for the full 7 days. Patients with isolated closed-head injury seemed to be initially hypermetabolic, but this process appeared to resolve by 1 week; the persistent nitrogen excretion may reflect equilibration of muscle mass to the existing level of activity (bed rest). After the first few days, nitrogen excretion may give an erroneous index of the level of metabolic stress and the type or amount of nutritional support needed.

Inflammatory responses and mediators.

The host response to injury is usually appropriate in degree and is self-limited. In more severe injury, the host response may persist inappropriately, leading to SIRS and MODS and possibly multiple organ failure. The initial response to injury is mediated primarily by norepinephrine, and is directed toward preservation of circulation to the heart and brain at the expense of other vascular beds. If fluid resuscitation is adequate and necrotic tissue is débrided, a hypermetabolic state ensues, mediated by epinephrine and directed toward supporting repair of injured tissue by leukocytes. Inflammatory cells are recruited to the site of injury and elaborate cytokines, which promote repair locally, but in severe injury may be systemically released and trigger remote inflammation. Cytokine biology presently is poorly understood, and simple anticytokine strategies have failed to improve survival of critically ill patients. Current therapy of SIRS and MODS is directed toward symptoms. Presently, it is unclear how an abnormal stress response arises. Cytokine spillover into the systemic circulation may occur. Selective transcriptional failure may be the cellular basis of organ dysfunction. Inappropriate production of peroxynitrite or its precursor, NO, is implicated in mediating cellular injury in SIRS and MODS.

Common nutritional issues in pediatric and adult critical care medicine.

This article discusses many of the nutritional topics important to the intensivist. Nutritional assessment, substrate immunonutrition, and disease specific issues are presented. Early introduction of enteral feeds and the use of nutritional modulation are emphasized.

Emergent airway management. Indications and methods in the face of confounding conditions.

Optimal airway management requires an experienced caregiver, attention to detail, and knowledge of the patient's physiology. A variety of pharmacologic agents have proved useful in obtaining a secure airway and minimizing risk to the patient. Depending on the skills of the caregiver, oral intubation has become the preferred means of airway control in most patients. Advances in technique, equipment, and pharmacology have greatly improved the art of airway management; however, there is no substitute for an experienced clinician.

The role of fiberoptic bronchoscopy in airway management of the critically ill patient.

Fiberoptic bronchoscopes (FOB) play a pivotal role in airway management in the operating room and critical care environments. This article examines the role of FOBs in modern airway management based on a review of recent literature and personal experience.

Airway management in the obstetric patient.

In summary, the need to manipulate the airway in the pregnant patient requires careful consideration and substantial planning. Anatomic and physiologic changes of pregnancy, coexisting conditions, and the potential for aspiration all carry a risk of morbidity and, indeed, mortality. Preparation, including early and repeated airway evaluations throughout pregnancy and labor, is encouraged. Knowledge of an emergency airway algorithm and a well thought-out plan for difficult intubations are imperative. Equipment must be available and in good condition. Finally, proper education and review for individuals involved in the delivery of care on the labor floor are mandatory. Although it is not always possible to control the manner in which these patients present, it is usually possible to control the environment into which they present.