Surviving Sepsis After Burn Campaign

INTRODUCTION

The Surviving Sepsis Campaign was developed to improve outcomes for all patients with sepsis. Despite sepsis being the primary cause of death after thermal injury, burns have always been excluded from the Surviving Sepsis efforts. To improve sepsis outcomes in burn patients, an international group of burn experts developed the Surviving Sepsis After Burn Campaign (SSABC) as a testable guideline to improve burn sepsis outcomes.

METHODS

The International Society for Burn Injuries (ISBI) reached out to regional or national burn organizations to recommend members to participate in the program. Two members of the ISBI developed specific "patient/population, intervention, comparison and outcome" (PICO) questions that paralleled the 2021 Surviving Sepsis Campaign [1]. SSABC participants were asked to search the current literature and rate its quality for each topic. At the Congress of the ISBI, in Guadalajara, Mexico, August 28, 2022, a majority of the participants met to create "statements" based on the literature. The "summary statements" were then sent to all members for comment with the hope of developing an 80% consensus. After four reviews, a consensus statement for each topic was created or "no consensus" was reported.

RESULTS

The committee developed sixty statements within fourteen topics that provide guidance for the early treatment of sepsis in burn patients. These statements should be used to improve the care of sepsis in burn patients. The statements should not be considered as "static" comments but should rather be used as guidelines for future testing of the best treatments for sepsis in burn patients. They should be updated on a regular basis.

CONCLUSION

Members of the burn community from the around the world have developed the Surviving Sepsis After Burn Campaign guidelines with the goal of improving the outcome of sepsis in burn patients.

Development and Validation of a Renal Replacement after Trauma Scoring Tool

BACKGROUND

Stress on the healthcare system requires careful allocation of resources such as renal replacement therapy (RRT). The COVID-19 pandemic generated difficulty securing access to RRT for trauma patients. We sought to develop a renal replacement after trauma (RAT) scoring tool to help identify trauma patients who may require RRT during their hospitalization.

STUDY DESIGN

The 2017 to 2020 TQIP database was divided into a derivation (2017 to 2018 data) and validation (2019 to 2020 data) set. A 3-step methodology was used. Adult trauma patients admitted from the emergency department to the operating room or ICU were included. Patients with chronic kidney disease, transfers from another hospital, and emergency department death were excluded. Multiple logistic regression models were created to determine the risk for RRT in trauma patients. The weighted average and relative impact of each independent predictor was used to derive a RAT score, which was validated using area under receiver operating characteristic curve (AUROC).

RESULTS

From 398,873 patients in the derivation and 409,037 patients in the validation set, 11 independent predictors of RRT were included in the RAT score derived with scores ranging from 0 to 11. The AUROC for the derivation set was 0.85. The rate of RRT increased to 1.1%, 3.3%, and 20% at scores of 6, 8, and 10, respectively. The validation set AUROC was 0.83.

CONCLUSIONS

RAT is a novel and validated scoring tool to help predict the need for RRT in trauma patients. With future improvements including baseline renal function and other variables, the RAT tool may help prepare for the allocation of RRT machines/staff during times of limited resources.

American Burn Association Guidelines on the Management of Acute Pain in the Adult Burn Patient: A Review of the Literature, a Compilation of Expert Opinion, and Next Steps

The ABA pain guidelines were developed 14 years ago and have not been revised despite evolution in the practice of burn care. A sub-committee of the American Burn Association's Committee on the Organization and Delivery of Burn Care was created to revise the adult pain guidelines. A MEDLINE search of English-language publications from 1968 to 2018 was conducted using the keywords "burn pain," "treatment," and "assessment." Selected references were also used from the greater pain literature. Studies were graded by two members of the committee using Oxford Centre for Evidence-based Medicine-Levels of Evidence. We then met as a group to determine expert consensus on a variety of topics related to treating pain in burn patients. Finally, we assessed gaps in the current knowledge and determined research questions that would aid in providing better recommendations for optimal pain management of the burn patient. The literature search produced 189 papers, 95 were found to be relevant to the assessment and treatment of burn pain. From the greater pain literature 151 references were included, totaling 246 papers being analyzed. Following this literature review, a meeting to establish expert consensus was held and 20 guidelines established in the areas of pain assessment, opioid medications, nonopioid medications, regional anesthesia, and nonpharmacologic treatments. There is increasing research on pain management modalities, but available studies are inadequate to create a true standard of care. We call for more burn specific research into modalities for burn pain control as well as research on multimodal pain control.

Updating the Burn Center Referral Criteria: Results From the 2018 eDelphi Consensus Study

Existing burn center referral criteria were developed several years ago, and subsequent innovations in burn care have occurred. Coupled with frequent errors in the estimation of extent of burn injury and depth by referring providers, patients are both over and under-triaged when the existing criteria are used to support patient care decisions. In the absence of compelling clinical trial data on appropriate burn patient triage, we convened a multidisciplinary panel of experts to execute an iterative eDelphi consensus process to facilitate a revision. The eDelphi process panel consisted of n = 61 burn stakeholders and experts and progressed through four rounds before reaching consensus on key clinical domains. The major findings are that 1) burn center consultation is strongly recommended for all patients with deep partial-thickness or deeper burns ≥ 10% TBSA burned, for full-thickness burns ≥ 5% TBSA burned, for children and older adults with specific dressing and medical needs, and for special burn circumstances including electrical, chemical, and radiation injuries; 2) smaller burns are ideally followed in burn center outpatient settings as soon as possible after injury, preferably without delays of a week or more; 3) frostbite, Stevens-Johnson syndrome/TENS, and necrotizing soft-tissue infection patients benefit from burn center treatment; and 4) telemedicine and technological solutions are of likely benefit in achieving this standard. Unlike the original criteria, the revised consensus-based guidelines create a framework promoting communication so that triage and treatment are specifically tailored to individual patient characteristics, injury severity, geography, and the capabilities of referring institutions.

Challenges to the Standardization of Trauma Data Collection in Burn, Traumatic Brain Injury, Spinal Cord Injury, and Other Trauma Populations: A Call for Common Data Elements for Acute and Longitudinal Trauma Databases

OBJECTIVE

Common data elements (CDEs) promote data sharing, standardization, and uniform data collection, which facilitate meta-analyses and comparisons of studies. Currently, there is no set of CDEs for all trauma populations, but their creation would allow researchers to leverage existing databases to maximize research on trauma outcomes. The purpose of this study is to assess the extent of common data collection among 5 trauma databases.

DESIGN

The data dictionaries of 5 trauma databases were examined to determine the extent of common data collection. Databases included 2 acute care databases (American Burn Association's National Burn Data Standard and American College of Surgeons' National Trauma Data Standard) and 3 longitudinal trauma databases (Burn, Traumatic Brain Injury, Spinal Cord Injury Model System National Databases). Data elements and data values were compared across the databases. Quantitative and qualitative variations in the data were identified to highlight meaningful differences between datasets.

SETTING

N/A.

PARTICIPANTS

N/A.

INTERVENTIONS

N/A.

MAIN OUTCOME MEASURES

N/A.

RESULTS

Of the 30 data elements examined, 14 (47%) were present in all 5 databases. Another 9 (30%) elements were present in 4 of the 5 databases. The number of elements present in each database ranged from 23 (77%) to 26 (86%). There were inconsistencies in the data values across the databases. Twelve of the 14 data elements present in all 5 databases exhibited differences in data values.

CONCLUSIONS

This study demonstrates inconsistencies in the documentation of data elements in 5 common trauma databases. These discrepancies are a barrier to database harmonization and to maximizing the use of these databases through linking, pooling, and comparing data. A collaborative effort is required to develop a standardized set of elements for trauma research.

The Associations of Gender With Social Participation of Burn Survivors: A Life Impact Burn Recovery Evaluation Profile Study

Burn injury can be debilitating and affect survivors' quality of life in a profound fashion. Burn injury may also lead to serious psychosocial challenges that have not been adequately studied and addressed. Specifically, there has been limited research into the associations of burn injury on community reintegration based on gender. This work analyzed data from 601 burn survivors who completed field testing of a new measure of social participation for burn survivors, the Life Impact Burn Recovery Evaluation (LIBRE) Profile. Differences in item responses between men and women were examined. Scores on the six LIBRE Profile scales were then compared between men and women using analysis of variance and adjusted linear multivariate regression modeling. Overall, men scored significantly better than women on four of the six LIBRE Profile scales: Sexual Relationships, Social Interactions, Work & Employment, and Romantic Relationships. Differences were not substantially reduced after adjustment for demographic characteristics and burn size. Men scored better than women in most of the areas measured by the LIBRE Profile. These gender differences are potentially important for managing burn patients during the post-injury recovery period.

Burn Resuscitation in the Austere Environment

Intravenous (IV) cannulation and sterile IV salt solutions may not be options in resource-limited settings (RLSs). This article presents recipes for fluid resuscitation in the aftermath of burns occurring in RLSs. Burns of 20% total body surface area (TBSA) can be resuscitated, and burns up to 40% TBSA can most likely be resuscitated, using oral resuscitation solutions (ORSs) with salt supplementation. Without IV therapy, fluid resuscitation for larger burns may only be possible with ORSs. Published global experience is limited, and the magnitude of burn injuries that successfully respond to World Health Organization ORSs is not well-described.

Redefining the outcomes to resources ratio for burn patient triage in a mass casualty

Recent disasters highlight the need for predisaster planning, including the need for accurate triage. Data-driven triage tables, such as that generated from the 2002 National Burn Repository, are vital to optimize resource use during a disaster. The study purpose was to generate a burn resource disaster triage table based on current burn-treatment outcomes. Data from the NBR after the year 2000 were audited. Records that missed age, burn size, or survival status were excluded from analysis. Duplicate records, readmissions, transfers, and nonburn injuries were eliminated. Resource use was divided into expectant (predicted mortality >90%), low (mortality 50-90%), medium (mortality 10-50%), high (mortality <10%, admission 14-21 days), very high (mortality <10%, admission <14 days), and outpatient. Tables were created for all patient admissions and with/without inhalation injury. Of the 286,293 records, 210,683 were from the year 2000 or later. Expectant status for those aged >70 years began at 50% burn; a 20- to 29-year-old never reached expectant status. Inhalation injury lowered the expectant category to a burn size of 40% in >70-year-olds, and at >90% in 20- to 29-year-olds. The 0- to 1.9-year old group without inhalation injury never reached expectant status; with inhalation injury, expectant status was reached at >80% burn. Changes in the triage tables suggest that burn care has changed in the past 10 years. Inhalation injury significantly alters triage in a burn disaster. Use of these updated tables for triage in a disaster may improve our ability to allocate resources.

Correlations between MRI white matter lesion location and executive function and episodic memory

OBJECTIVES

MRI white matter hyperintensity (WMH) volume is associated with cognitive impairment. We hypothesized that specific loci of WMH would correlate with cognition even after accounting for total WMH volume.

METHODS

Subjects were identified from a prospective community-based study: 40 had normal cognition, 94 had mild impairment (defined here as a Clinical Dementia Rating [CDR] score of 0.5 without dementia), and 11 had mild Alzheimer's dementia. Factor analysis of a 22-item neuropsychological battery yielded 4 factors (episodic memory, executive function, spatial skills, and general knowledge). MRI WMH segmentation and analysis was performed using FreeSurfer software.

RESULTS

Higher WMH volume was independently associated with lower executive function and episodic memory factor scores. Voxel-based general linear models showed loci where WMH was strongly inversely associated with specific cognitive factor scores (p < 0.001), controlling for age, education, sex, APOE genotype, and total WMH volume. For episodic memory, clusters were observed in bilateral temporal-occipital and right parietal periventricular white matter, and the left anterior limb of the internal capsule. For executive function, clusters were observed in bilateral inferior frontal white matter, bilateral temporal-occipital and right parietal periventricular white matter, and the anterior limb of the internal capsule bilaterally.

CONCLUSIONS

Specific WMH loci are closely associated with executive function and episodic memory, independent of total WMH volume. The anatomic locations suggest that WMH may cause cognitive impairment by affecting connections between cortex and subcortical structures, including the thalamus and striatum, or connections between the occipital lobe and frontal or parietal lobes.

The sodium channel band shapes the response to electric stimulation in retinal ganglion cells

To improve the quality of prosthetic vision, it is desirable to understand how targeted retinal neurons respond to stimulation. Unfortunately, the factors that shape the response of a single neuron to stimulation are not well understood. A dense band of voltage-gated sodium channels within the proximal axon of retinal ganglion cells is the site most sensitive to electric stimulation, suggesting that band properties are likely to influence the response to stimulation. Here, we examined how three band properties influence sensitivity using a morphologically realistic ganglion cell model in NEURON. Longer bands were more sensitive to short-duration pulses than shorter bands and increasing the distance between band and soma also increased sensitivity. Simulations using the known limits of band length and location resulted in a sensitivity difference of approximately 2. Additional simulations tested how changes to sodium channel conductance within the band influenced threshold and found that the sensitivity difference increased to a factor of nearly 3. This is close to the factor of 5 difference measured in physiological studies suggesting that band properties contribute significantly to the sensitivity differences found between different types of retinal neurons.

Association of increasing burn severity in mice with delayed mobilization of circulating angiogenic cells

OBJECTIVE

To perform a systematic exploration of the phenomenon of mobilization of circulating angiogenic cells (CACs) in an animal model. This phenomenon has been observed in patients with cutaneous burn wounds and may be an important mechanism for vasculogenesis in burn wound healing.

DESIGN

We used a murine model, in which burn depth can be varied precisely, and a validated culture method for quantifying circulating CACs.

SETTING

Michael D. Hendrix Burn Research Center, Baltimore, Maryland.

PARTICIPANTS

Male 129S1/SvImJ mice, aged 8 weeks, and 31 patients aged 19-59 years with burn injury on 1% to 64% of the body surface area and evidence of hemodynamic stability.

MAIN OUTCOME MEASURES

Burn wound histological features, including immunohistochemistry for blood vessels with CD31 and alpha-smooth muscle actin antibodies, blood flow measured with laser Doppler perfusion imaging, and mobilization of CACs into circulating blood measured with a validated culture technique.

RESULTS

Increasing burn depth resulted in a progressive delay in the time to mobilization of circulating CACs and reduced mobilization of CACs. This delay and reduction in CAC mobilization was associated with reduced perfusion and vascularization of the burn wound tissue. Analysis of CACs in the peripheral blood of the human patients, using a similar culture assay, confirmed results previously obtained by flow cytometry, that CAC levels peak early after the burn wound.

CONCLUSION

If CAC mobilization and wound perfusion are important determinants of clinical outcome, then strategies designed to augment angiogenic responses may improve outcome in patients with severe burn wounds.

The advanced health and disaster aid network: a light-weight wireless medical system for triage

Advances in semiconductor technology have resulted in the creation of miniature medical embedded systems that can wirelessly monitor the vital signs of patients. These lightweight medical systems can aid providers in large disasters who become overwhelmed with the large number of patients, limited resources, and insufficient information. In a mass casualty incident, small embedded medical systems facilitate patient care, resource allocation, and real-time communication in the advanced health and disaster aid network (AID-N). We present the design of electronic triage tags on lightweight, embedded systems with limited memory and computational power. These electronic triage tags use noninvasive, biomedical sensors (pulse oximeter, electrocardiogram, and blood pressure cuff) to continuously monitor the vital signs of a patient and deliver pertinent information to first responders. This electronic triage system facilitates the seamless collection and dissemination of data from the incident site to key members of the distributed emergency response community. The real-time collection of data through a mesh network in a mass casualty drill was shown to approximately triple the number of times patients that were triaged compared with the traditional paper triage system.

Effects of oxandrolone on outcome measures in the severely burned: a multicenter prospective randomized double-blind trial

Severe burns induce pathophysiologic problems, among them catabolism of lean mass, leading to protracted hospitalization and prolonged recovery. Oxandrolone is an anabolic agent shown to decrease lean mass catabolism and improve wound healing in the severely burned patients. We enrolled 81 adult subjects with burns 20% to 60% TBSA in a multicenter trial testing the effects of oxandrolone on length of hospital stay. Subjects were randomized between oxandrolone 10 mg every 12 hours or placebo. The study was stopped halfway through projected enrollment because of a significant difference between groups found on planned interim analysis. We found that length of stay was shorter in the oxandrolone group (31.6 +/- 3.1 days) than placebo (43.3 +/- 5.3 days; P < .05). This difference strengthened when deaths were excluded and hospital stay was indexed to burn size (1.24 +/- 0.15 days/% TBSA burned vs 0.87 +/- 0.05 days/% TBSA burned, P < .05). We conclude that treatment using oxandrolone should be considered for use in the severely burned while hepatic transaminases are monitored.

Long-term hyperexcitability in the hippocampus after experimental head trauma

Head injury is a causative factor in the development of temporal lobe epilepsy. However, whether a single episode of concussive head trauma causes a persistent increase in neuronal excitability in the limbic system has not been unequivocally determined. This study used the rodent fluid percussion injury (FPI) model, in combination with electrophysiological and histochemical techniques, to investigate the early (1 week) and long-term (1 month or longer) changes in the hippocampus after head trauma. Low-frequency, single-shock stimulation of the perforant path revealed an early granule cell hyperexcitability in head-injured animals that returned to control levels by 1 month. However, there was a persistent decrease in threshold to induction of seizure-like electrical activity in response to high-frequency tetanic stimulation in the hippocampus after head injury. Timm staining revealed both early- and long-term mossy fiber sprouting at low to moderate levels in the dentate gyrus of animals that experienced FPI. There was a long-lasting increase in the frequency of spontaneous inhibitory postsynaptic currents in dentate granule cells after FPI, and ionotropic glutamate receptor antagonists selectively decreased the spontaneous inhibitory postsynaptic current frequency in the head-injured animals. These results demonstrate that a single episode of experimental closed head trauma induces long-lasting alterations in the hippocampus. These persistent structural and functional alterations in inhibitory and excitatory circuits are likely to influence the development of hyperexcitable foci in posttraumatic limbic circuits.

Cytochrome P450 2E1 (CYP2E1)-dependent production of a 37-kDa acetaldehyde-protein adduct in the rat liver

Ethanol-inducible cytochrome P450 2E1 (CYP2E1) has been shown to be involved in the metabolism of both ethanol and acetaldehyde. Acetaldehyde, produced from ethanol metabolism, is highly reactive and can form various protein adducts. In this study, we investigated the role of CYP2E1 in the production of a 37-kDa acetaldehyde-protein adduct. Rats were pairfed an isocaloric control or an alcohol liquid diet with and without cotreatment of YH439, an inhibitor of CYP2E1 gene transcription, for 4 weeks. The soluble proteins from rat livers of each group were separated on SDS-polyacrylamide gels followed by immunoblot analysis using specific antibodies against the 37-kDa protein acetaldehyde adduct. In addition, catalytic activities of the enzymes involved in alcohol and acetaldehyde metabolism were measured and compared with the adduct level. Immunoblot analysis revealed that the 37-kDa adduct, absent in the pair-fed control, was evident in alcohol-fed rats but markedly reduced by YH439 treatment. Immunohistochemical analysis also showed that the 37-kDa adduct is predominantly localized in the pericentral region of the liver where CYP2E1 protein is mainly expressed. This staining disappeared in the pericentral region after YH439 treatment. The levels of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase isozymes were unchanged after YH439 treatment. However, the level of the 37-kDa protein adduct positively correlated with the hepatic content of P4502E1. These data indicate that the 37-kDa adduct could be produced by CYP2E1-mediated ethanol metabolism in addition to the ADH-dependent formation.

Coordinated regulation of two TRAIL-R2/KILLER/DR5 mRNA isoforms by DNA damaging agents, serum and 17beta-estradiol in human breast cancer cells

A search of the Genebank database revealed that there are two distinct gene sequences with the common name of TRAIL-R2/Killer/DR5. Using reverse transcription-polymerase chain reaction (RT-PCR), we confirmed the existence of two isoforms of TRAIL-R2/Killer/DR5 mRNA, which we have designated the long and short isoforms based on their electrophoretic mobility. We found that both the long and short mRNA isoforms are ubiquitously expressed in human tissues and cell lines. The long form generally predominates, but the proportion of the two isoforms varies depending on the tissue type. Treatment of MCF-7 human breast cancer cells with the DNA damaging drugs adriamycin, campthothecin, or etoposide causes a coordinated up-regulation of both isoforms. Treatment of the p53-mutant T-47D breast cancer cell line with adriamycin also results in up-regulation of both isoforms, suggesting that adriamycin up-regulates TRAIL-R2/Killer/DR5 expression independent of functional p53. The expression of both mRNA isoforms are increased in MCF-7 cells cultured in charcoal-stripped fetal bovine serum compared to normal serum, suggesting that sex steroid hormones may play a role in the negative regulation of their expression. This was confirmed in MCF-7 cells cultured in stripped serum supplemented with 17beta-estradiol, which also resulted in a decrease in the mRNA expression of both isoforms. These results demonstrate that the TRAIL-R2/Killer/DR5 gene gives rise to two distinct forms of mRNA, and that these two forms are coordinately regulated by DNA damage and 17beta-estradiol in human breast cancer cells. The functional significance of the two isoforms remains to be determined.

Determination of pyrolysis products of smoked methamphetamine mixed with tobacco by tandem mass spectrometry

This study examines the pyrolysis products of smoked methamphetamine mixed with tobacco that was trapped with a C8 adsorbent cartridge and then detected by gas chromatography-tandem mass spectrometry. According to the results, the mainstream smoke contains 2-methylpropyl-benzene, 2-chloropropyl-benzene, 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, 3-ethyl-phenol, methamphetamine, dimethylamphetamine, hydroquinone, 3-methyl-5-(1-methylethyl)-methylcarbamate phenol, N-methyl-N-(2-phenylethyl)-acetamide, 4-(3-hydroxy-1-butenyl)-3,5,5-trimethyl-2-cyclohexene-1-one, propanoic acid, N-acetylmethamphetamine, phenyl ester, and furfurylmethylamphetamine. In addition, the compounds in sidestream smoke are 2-propenyl benzene, phenylacetone, methamphetamine, dimethylamphetamine, benzyl methyl ketoxime, 3,4-dihydro-2-naphthalenone, N-folmyamphetamine, N-acetylamphetamine, bibenzyl, N-folmylmethamphetamine, N-acetylmethamphetamine, N-propionymethamphetamine, and furfurylmethylamphetamine. Moreover, the presence of methamphetamine promotes the oxidation of the tobacco components.

Critical role of arg433 in rat transketolase activity as probed by site-directed mutagenesis

It has been shown that one arginine per monomer at an unknown position is essential for enzyme activity of the homodimeric transketolase (TK) [Kremer, Egan and Sable (1980) J. Biol. Chem. 255, 2405-2410]. To identify the critical arginine, four highly conserved arginine residues of rat TK (Arg102, Arg350, Arg433 and Arg506) were replaced with alanine by site-directed mutagenesis. Wild-type and mutant TK proteins were produced in Escherichia coli and characterized. The Arg102-->Ala mutant exhibited similar catalytic activity to the wild-type enzyme, whereas Arg350-->Ala, Arg506-->Ala and Arg433-->Ala mutants exhibited 36.7, 37.0 and 6.1% of the wild-type activity respectively. Three recombinant proteins (wild-type, Arg350-->Ala and Arg433-->Ala) were purified to apparent homogeneity using Ni2+-affinity chromatography and further characterized. All these proteins were able to form homodimers (148 kDa), as shown by immunoblot analysis subsequent to non-denaturing gel electrophoresis. The Arg433-->Ala mutant protein was less stable than the wild-type and Arg350-->Ala proteins at 55 degrees C. Kinetic analyses revealed that both Vmax and Km values were markedly affected in the Arg433-->Ala mutant. The Km values for two substrates xylulose 5-phosphate and ribose 5-phosphate were 11.5- and 24.3-fold higher respectively. The kcat/Km values of the Arg433-->Ala mutant for the two substrates were less than 1% of those of the wild-type protein. Molecular modelling of the rat TK revealed that Arg433 of one monomer has three potential hydrogen-bond interactions with the catalytically important highly conserved loop of the other monomer. Thus, our biochemical analyses and modelling data suggest the critical role of the previously uncharacterized Arg433 in TK activity.

Pyruvate dehydrogenase E1 alpha isoform in rat testis: cDNA cloning, characterization, and biochemical comparison of the recombinant testis and liver enzymes

Previous data indicated a tissue-specific regulation of mitochondrial pyruvate dehydrogenase (PDH) complex, especially in the brain and testis. The lack of biochemical data on the rat testis PDH limits comparative analysis between testis and liver enzymes. Therefore, we have isolated a cDNA clone encoding rat testis PDH E1 alpha isoform, determined its nucleotide sequence, studied the tissue-specific expression, and characterized the recombinant protein produced in bacteria, compared to the liver counterpart. Our cDNA clone (2.2 kb) contained the identical open reading frame (from nt 974 to 2149) with that previously reported (Cullingford et al., 1993 Biochim Biophys Acta 1216:149-153) but contained a long 5' untranslated region, which has little identity to the other clone. Northern blot confirmed testis-specific expression of this isoform. Genomic DNA analyses by PCR amplification suggested this clone is a gene product distinct from its X-linked somatic counterpart. Our biochemical and kinetic analyses revealed that the purified recombinant rat testis PDH E1 (containing both E1 alpha and E1 beta subunits) was enzymatically active and phosphorylated in vitro by purified PDH-kinase p48 or p45, similar to the recombinant human liver enzyme. Our current data thus indicate that the differential regulation of testis PDH observed in the animal model may result from differential modulation of PDH-kinase or -phosphatase in this tissue rather than the presence of functionally different PDH E1 subunit.

Dihydrolipoamide dehydrogenase-binding protein of the human pyruvate dehydrogenase complex. DNA-derived amino acid sequence, expression, and reconstitution of the pyruvate dehydrogenase complex

Protein X, recently renamed dihydrolipoamide dehydrogenase-binding protein (E3BP), is required for anchoring dihydrolipoamide dehydrogenase (E3) to the dihydrolipoamide transacetylase (E2) core of the pyruvate dehydrogenase complexes of eukaryotes. DNA and deduced protein sequences for E3BP of the human pyruvate dehydrogenase complex are reported here. With the exception of only a single lipoyl domain, the protein has a segmented multi-domain structure analogous to that of the E2 component of the complex. The protein has 46% amino acid sequence identity in its amino-terminal region with the second lipoyl domain of E2, 38% identity in its central region with the putative peripheral subunit-binding domain of E2, and 50% identity in its carboxyl-terminal region with the catalytic inner core domain of E2. The similarity in the latter domain stands in contrast to E3BP of Saccharomyces cerevisiae, which is quite different from its homologous transacetylase in this region. The putative catalytic site histidine residue present in the inner core domains of all dihydrolipoamide acyltransferases is replaced by a serine residue in human E3BP; thus, catalysis of coenzyme A acetylation by this protein is unlikely. Coexpression of cDNAs for E3BP and E2 resulted in the formation of an E2.E3BP subcomplex that spontaneously reconstituted the pyruvate dehydrogenase complex in the presence of native E3 and recombinant pyruvate decarboxylase (E1).

The impact of implementation of neuromuscular blockade monitoring standards in a surgical intensive care unit

The purpose was to determine whether implementation of standards for peripheral nerve monitoring could decrease the incidence of neuromuscular dysfunction related to the administration of paralytic agents. Over a 2-year period, consecutive patients admitted to a surgical intensive care unit who received continuously-infused or >6 daily doses of neuromuscular blocking agents were subjected to train-of-four (TOF) monitoring of the adductor pollicis. Therapy was titrated to the maintenance of one to two twitches at all times. The incidence of prolonged (>12 h) paralysis after drug discontinuation was documented in these patients and compared to that in patients treated in the previous 12 months. The presence of electrolyte abnormalities, organ dysfunction, and concomitant medications was also recorded. Chi-square analysis with Yates correction was employed. Before implementation of routine TOF monitoring, there were five instances of paralytic-associated neuromuscular dysfunction (5/43). After implementation of the TOF protocol, no instances of paralytic-associated neuromuscular dysfunction occurred (0/90), despite the same incidence of risk factors (100%) (P < 0.05). A protocol for neuromuscular blockade monitoring is efficacious in preventing paralytic-associated neuromuscular dysfunction. This can be a cost-effective measure, minimizing the prolonged mechanical ventilation and intensive rehabilitation required secondary to unmonitored use of neuromuscular blocking agents.

Characterization of a cDNA clone for human NAD(+)-specific isocitrate dehydrogenase alpha-subunit and structural comparison with its isoenzymes from different species

A 0.6 kb cDNA fragment encoding the human NAD(+)-specific isocitrate dehydrogenase alpha-subunit (H-IDH alpha) was amplified by PCR using oligonucleotide primers synthesized on the basis of pig tryptic peptide sequences [Huang and Colman (1990) Biochemistry 29, 8266-8273]. With the amplified cDNA as a probe, cDNA clones for IDH alpha were isolated from a human heart lambda gt11 cDNA library. The deduced protein sequence of the largest cDNA clone (2628 bp) rendered a precursor protein of 366 amino acids (39,591 Da) and a mature protein of 339 amino acids (36,640 Da). The deduced H-IDH alpha protein sequence is highly similar to the partial peptide sequences of the pig enzyme. It is 55, 43 and 44% identical with yeast NAD(+)-specific IDH2, yeast NAD(+)-specific IDH1 and monkey NAD(+)-specific IDH gamma-subunit (IDH gamma) respectively. However, it has less similarity (about 30%) to NADP(+)-specific IDH from Escherichia coli and bovine mitochondria. These results indicate that the structure of IDH alpha closely resembles that of IDH2, the catalytic subunit of the yeast enzyme. Structural analysis of the deduced H-IDH alpha protein revealed that the amino acids responsible for the binding of isocitrate, Mg2+ and NAD+ are highly conserved. It also has two conserved motifs for the binding sites of ATP and ADP, but a canonical Ca(2+)-binding motif was not recognized. Unusual penta-(ATTTA) and tri-(TAA or ATT) nucleotides which are respectively believed to interact with RNA-binding proteins and be near the endonuclease cleavage sites were frequently recognized in its 3' untranslated region, indicating the possibility of an additional method of regulation of this enzyme. Northern-blot analysis suggests that one mRNA transcript (2.8 kb) exists in cultured HeLa cells. Genomic DNA Southern-blot analysis indicates that the IDH alpha gene is not closely related to that of the other IDH isoenzymes, and IDH alpha appears to be encoded by a single gene.

Late pulmonary sequela following burns: persistence of hyperprocalcitonemia using a 1-57 amino acid N-terminal flanking peptide assay

Seven patients were evaluated at a mean duration of 8.4 yr after sustaining inhalational injury associated with burns. At the time of re-examination, the patients were asymptomatic and had normal chest X-rays, and arterial blood gases. Three of the seven patients had abnormally elevated serum calcitonin levels. The spirometry (FEV1) measurements showed an inverse trend to that of the serum calcitonin levels. The elevated calcitonin levels had an abnormal predominance of the procalcitonin component as assessed by several region specific antisera. The serum calcitonin also showed a significant correlation with the hormone level which had been obtained at the time of prior discharge from the hospital (r = 0.91). Although there appears to be no or minimal chronic pulmonary sequela to inhalational injury in burns by pulmonary testing, we speculate that the hyperprocalcitonemia in some of the patients may reflect a long-term hyperplastic response of the bronchio-epithelial pulmonary neuroendocrine cells. The potential significance of this and other lung-associated endocrine markers is discussed.

Production of an enzymatically active E1 component of human pyruvate dehydrogenase complex in Escherichia coli: supporting role of E1 beta subunit in E1 activity

A co-expression plasmid containing the coding sequence of both the human liver pyruvate dehydrogenase (PDH) E1 alpha and E1 beta subunits was constructed. Functionally active PDH E1 protein was produced when this co-expression plasmid was introduced into the host Escherichia coli cell, BL21 (DE3)/plysS. In contrast, the production of E1 alpha alone resulted in a catalytically inactive protein, suggesting an important role of the E1 beta subunit in constituting enzyme activity. The PDH E1 protein produced in E. coli was capable of being phosphorylated by PDH-specific kinase. This co-expression system will provide a useful tool for studying the biochemical properties of human PDH E1.

A comparison of intraduodenally and intracolonically administered nutrients on the release of peptide-YY in the dog

The objective of this study was to compare the effects of various nutrients (fats, proteins, amino acids, and carbohydrates), given directly into the duodenum or the colon, on the release of peptide-YY (PYY) in conscious dogs. As reported previously, this study showed that plasma levels of PYY increased significantly (P less than 0.05) within 15 min in response to an oral mixed meal. Intraduodenal (ID) administration of a fatty acid (oleic acid; 100 mmol/L; 100 ml/h) stimulated a robust release of PYY, whereas ID administration of an amino acid mixture (phenylalanine plus tryptophan; 100 mmol/L each; 100 ml/h), glucose (1 g/kg), or a liver extract (10%; 100 ml/h) failed to elevate plasma levels of PYY. ID administration of glucose at 2 g/kg caused a mild but significant elevation in plasma PYY levels. Intracolonic administration of saline, a fatty acid, an amino acid mixture, glucose, or a liver extract significantly stimulated PYY release. This study suggests that as chyme moves from the stomach to the proximal bowel, fat is the primary constituent of food that stimulates the prompt release of PYY. However, unabsorbed nutrients can release PYY by a direct contact with the PYY-containing cells lining the intestinal lumen of the terminal ileum, colon, and rectum. Both mechanisms probably participate in the release of PYY.