Coronary revascularization in lung transplant recipients with concomitant coronary artery disease.

Coronary artery disease (CAD) is not uncommon among lung transplant candidates. Several small, single-center series have suggested that short-term outcomes are acceptable in selected patients who undergo coronary revascularization prior to, or concomitant with, lung transplantation. Our objective was to evaluate perioperative and intermediate-term outcomes in this patient population at our institution. We performed a retrospective, observational cohort analysis of 898 lung transplant recipients between 1997 and 2010. Pediatric, multivisceral, lobar or repeat transplantations were excluded, resulting in 791 patients for comparative analysis, of which 49 (median age 62, 79.6% bilateral transplant) underwent concurrent coronary artery bypass and 38 (median age 64, 63.2% bilateral transplant) received preoperative percutaneous coronary intervention (PCI). Perioperative mortality, overall unadjusted survival and adjusted hazard ratio for cumulative risk of death were similar among both revascularization groups as well as controls. The rate of postoperative major adverse cardiac events was also similar among groups; however, concurrent coronary artery bypass was associated with longer postoperative length of stay, more time in the intensive care unit and more postoperative days requiring ventilator support. These results suggest that patients with CAD need not be excluded from lung transplantation. Preferential consideration should be given to preoperative PCI when feasible.

Fat, oil and grease deposits in sewers: characterisation of deposits and formation mechanisms.

Fat, oil and grease deposits (FOG) in sewers are a major problem and can cause sewer overflows, resulting in environmental damage and health risks. Often simplistically portrayed as cooling of fats, recent research has suggested that saponification may be involved in FOG formation. However there are still questions about the mechanisms effecting transformations in sewers and the role and source of metal cations involved in saponification. This study characterises FOG deposits from pumping stations, sewers and sewage works from different water hardness zones across the UK. The sites all had previous problems with FOG and most catchments contained catering and food preparation establishments. The FOG deposits were highly variable with moisture content ranging from 15 to 95% and oil content from 0 to 548 mg/g. Generally the pumping stations had lower moisture content and higher fat content, followed by the sewers then the sewage works. The water in contact with the FOG had high levels of oil (mean of about 800 mg/L) and this may indicate poor kitchen FOG management practices. FOG fatty acid profiles showed a transformation from unsaturated to saturated forms compared to typical cooking oils. This seems to relate to ageing in the sewer network or the mechanism of formation, as samples from pumping stations had higher proportions of C18:1 compared to C16. This may be due to microbial transformations by bacteria such as Clostridium sp. in a similar process to adipocere formation. There was an association between water hardness and increased Ca levels in FOG along with harder deposits and higher melting points. A link between FOG properties and water hardness has not been previously reported for field samples. This may also be due to microbial processes, such as biocalcification. By developing the understanding of these mechanisms it may be possible to more effectively control FOG deposits, especially when combined with promotion of behavioural change.

Fate, effects and potential environmental risks of ethylene glycol: a review.

The fate, effects, and potential environmental risks of ethylene glycol (EG) in the environment were examined. EG undergoes rapid biodegradation in aerobic and anaerobic environments (approximately 100% removal of EG within 24 h to 28 days). In air, EG reacts with photo-chemically produced hydroxyl radicals with a resulting atmospheric half-life of 2 days. Acute toxicity values (LC(50)s and EC(50)s) were generally >10,000 mg/l for fish and aquatic invertebrates. The data collectively show that EG is not persistent in air, surface water, soil, or groundwater, is practically non-toxic to aquatic organisms, and does not bioaccumulate in aquatic organisms. Potential long-term, quasi-steady state regional concentrations of EG estimated with a multi-media model for air, water, soil, and sediment were all less than predicted no effect concentrations (PNECs).

Coherent manipulation of semiconductor quantum bits with terahertz radiation.

Quantum bits (qubits) are the fundamental building blocks of quantum information processors, such as quantum computers. A qubit comprises a pair of well characterized quantum states that can in principle be manipulated quickly compared to the time it takes them to decohere by coupling to their environment. Much remains to be understood about the manipulation and decoherence of semiconductor qubits. Here we show that hydrogen-atom-like motional states of electrons bound to donor impurities in currently available semiconductors can serve as model qubits. We use intense pulses of terahertz radiation to induce coherent, damped Rabi oscillations in the population of two low-lying states of donor impurities in GaAs. Our observations demonstrate that a quantum-confined extrinsic electron in a semiconductor can be coherently manipulated like an atomic electron, even while sharing space with approximately 10(5) atoms in its semiconductor host. We anticipate that this model system will be useful for measuring intrinsic decoherence processes, and for testing both simple and complex manipulations of semiconductor qubits.

HMG-I/Y, a new c-Myc target gene and potential oncogene.

The HMG-I/Y gene encodes the HMG-I and HMG-Y proteins, which function as architectural chromatin binding proteins important in the transcriptional regulation of several genes. Although increased expression of the HMG-I/Y proteins is associated with cellular proliferation, neoplastic transformation, and several human cancers, the role of these proteins in the pathogenesis of malignancy remains unclear. To better understand the role of these proteins in cell growth and transformation, we have been studying the regulation and function of HMG-I/Y. The HMG-I/Y promoter was cloned, sequenced, and subjected to mutagenesis analysis. A c-Myc-Max consensus DNA binding site was identified as an element important in the serum stimulation of HMG-I/Y. The oncoprotein c-Myc and its protein partner Max bind to this site in vitro and activate transcription in transfection experiments. HMG-I/Y expression is stimulated by c-Myc in a Myc-estradiol receptor cell line in the presence of the protein synthesis inhibitor cycloheximide, indicating that HMG-I/Y is a direct c-Myc target gene. HMG-I/Y induction is decreased in Myc-deficient fibroblasts. HMG-I/Y protein expression is also increased in Burkitt's lymphoma cell lines, which are known to have increased c-Myc protein. Like Myc, increased expression of HMG-I protein leads to the neoplastic transformation of both Rat 1a fibroblasts and CB33 cells. In addition, Rat 1a cells overexpressing HMG-I protein form tumors in nude mice. Decreasing HMG-I/Y proteins using an antisense construct abrogates transformation in Burkitt's lymphoma cells. These findings indicate that HMG-I/Y is a c-Myc target gene involved in neoplastic transformation and a member of a new class of potential oncogenes.

Effects of opioids on driving ability.

Driving has been regarded as an activity of daily living that is important in maintaining a person's independence in the community, access to employment, and social activities. Many patients, however, using opioid medications on a regular basis (Chronic Opioid Analgesic Therapy: COAT) to ameliorate their intractable pain have been restricted from driving out of concern that skills would be impaired and driving safety compromised by these medications. Yet there are no driving studies which have explored the effects of using opioid analgesics for an extended period of time. This pilot study was designed to determine the effects of medically prescribed, stable opioid use on the driving abilities of patients with persistent, nonmalignant pain. Sixteen patients with chronic nonmalignant pain on COAT, who met criteria for participation in the study, underwent a comprehensive off-road driving evaluation using measures which have been shown to be sensitive in predicting on-road driving performance. The evaluation consisted of a pre-driver evaluation (PDE), a simulator evaluation (SDE), and behavioral observation during simulator performance. Patients in the COAT group were compared to a historical control group of 327 cerebrally compromised patients (CComp) who had undergone the same evaluation and then passed an on-road, behind-the-wheel evaluation (BTW Pass; n = 162) or failed (BTW Fail; n = 165). Results revealed that COAT patients generally outperformed the CComp patients as a group by equaling or exceeding PDE and SDE scores of the BTW Fail patients as well as the BTW Pass patients on all measures that differentiated the groups. Notably, COAT patients had a relatively poorer performance than CComp patients on specific neuropsychometric tests in the PDE; however, the differences were not statistically significant and did not imply a systematic pattern of scores that reflected domain-specific deficits. Behaviorally, COAT patients were generally superior to CComp patients, also; however, COAT patients had greater difficulty in following instructions and as well as a tendency toward impulsivity, like the BTW fail group. While there was general support for the notion that COAT did not significantly impair the perception, cognition, coordination, and behavior measured in off-road tests that have been regarded as requisite for on-road driving, methodological problems may limit the generalizability of results and recommendations are made for research beyond a pilot study.

LH responses to chicken luteinizing hormone-releasing hormone I and II in laying, incubating, and out of lay turkey hens.

An experiment was conducted to assess the relative in vivo and in vitro activities of chicken LH-RH-I and -II in laying, incubating and out-of-lay turkey hens. The highest plasma concentrations of LH were measured in laying turkey hens, whereas hypophyseal concentrations were highest in incubating hens (I) and lowest in the laying hens at the end of the laying period (EL). Hypophyseal and plasma concentrations of LH decreased with aging in laying hens (L) and the greater decrease occurred in the hypophyses. An in vitro hypophyseal acute challenge with 2-min pulses of cLHRH I or II (10(-7) M) using a perifusion technique resulted in an increase in the release of LH in out-of-lay (OL) and incubating (I) hens, but not in laying (L) hens. Although both peptides elicited comparable responses in I hens, cLHRH II was more effective in OL hens. This difference was attributable to a greater amplitude of the response, whose duration was unchanged. Hypophyseal desensitization to a subsequent stimulation was observed in OL hens when the interval between stimulations was 30 min, but this did not occur at 60- or 120-min intervals. In vivo, the injection of cLHRH I or II, at doses of 10(-8) and 10(-10) M/kg B.W. stimulated increases in the plasma concentrations of LH, which were initiated within 1 min of injection in OL and I hens but from 5 to 20 min postinjection in L hens. The responses were dose-related and greater immediate responses were measured with cLHRH I than with cLHRH II. Also, after the injection of cLHRH II at the 10(-8) M/kg B.W. dose, the shape of the LH response consisted of an initial increase, followed by a more sustained phase during which LH concentrations were either stable (I hens) or continued to increase (L and OL hens) from 20 to 60 min after injection. In contrast, the injection of cLHRH I at doses of 10(-8) or 10(-10) M/kg or cLHRH II at a dose of 10(-10) M/kg in I and OL hens, produced a peak of LH concentrations in plasma within 5 min and thereafter declined gradually. The difference in the in vivo responses to LHRH I and II could not be attributed to a greater potency of cLHRH II, but to a more prolonged action. In summary, the responses to both forms of chicken LH-RH varies markedly with the stage of the reproductive cycle (L, I, and OL) and differs between the in vivo and in vitro situations. Although cLHRH II may be more active than cLHRH I, controversy still surrounds its precise physiological role.

Measuring the biodegradability of nonylphenol ether carboxylates, octylphenol ether carboxylates, and nonylphenol.

We examined the biodegradability of several metabolites of C8- and C9-alkylphenol ethoxylates, including nonylphenoxyacetic acid (NPEC1), nonylphenoxyethoxyacetic acid (NPEC2), octylphenoxyacetic acid (OPEC1), octylphenoxyethoxyacetic acid (OPEC2), and nonylphenol (NP). Using OECD method 301B (modified Sturm method), OPEC1 and OPEC2 are readily biodegradable: both compounds exceeded 60% of theoretical CO2 formation (ThCO2) by day 28, and required less than 10 days to go from 10% to 60% ThCO2. Also using method 301B, NPEC1 and NPEC2 exceeded 60% ThCO2 at day 28, but did not meet the 10 day window. Using OECD method 301F, the manometric respirometry method that measures oxygen consumption, approximately 62% of NP was biodegraded in 28 days, but required more than 10 days to go from 10% to 60% biodegradation. While the validity of the "10-day window" is currently being debated within OECD, the data show that the common metabolites of C8- and C9-APEs are rapidly degraded in the test systems used, which strongly suggests that they would not accumulate or persist in the environment.

Motion artifact seen on slot-scanning direct digital mammography.

OBJECTIVE: Our goal was to determine the appearance of motion artifact when imaging an anthropomorphic breast phantom using a digital slot-scanning system compared with a screen-film system. MATERIALS AND METHODS: Digital and screen-film images were obtained during both brief and continuous manually induced motion of an anthropomorphic phantom in four directions. Continuous motion was further characterized using a syringe pump to induce motion artifact. RESULTS: On screen-film images, brief motion caused degradation of the entire image, simulating a double exposure. Conversely, on digital images using a slot-scanning system, brief motion caused degradation of only a small portion of the image. Continuous motion resulted in smearing of phantom details with both systems, although the smearing was more strongly influenced by the direction of motion when the slot-scanning system was used. With the slot-scanning system, motion in the direction of the detector sweep resulted in elongated distortion, whereas motion in the opposite direction resulted in foreshortening; diagonal smearing was seen with perpendicular phantom motion. The magnitude of distortion for continuous motion at a set velocity was substantially less with the slot-scanning system. CONCLUSION: Motion artifact with a slot-scanning direct digital mammography unit differs significantly from that seen with a conventional screen-film unit and, despite a relatively long overall exposure, may prove to be less of a problem than with conventional units because any given part of an object is exposed only briefly.

Early diagnosis and treatment of laryngeal injuries from prolonged intubation in adults.

Prolonged endotracheal intubation can cause injuries to 1 or more regions of the larynx, making safe extubation impossible and leading to tracheostomy in many patients. Unfortunately, a considerable number of these patients do not benefit from early laryngeal evaluation, which may reveal potentially treatable soft, obstructive tissue before it undergoes irreversible fibrosis. Between July 1992 and December 1995, we performed immediate direct telelaryngoscopy on 142 adults who required tracheostomy because of failed extubation. When present, obstructive tissue was removed with microsurgical techniques. One hundred twenty-nine (90%) patients were decannulated within 3 weeks. The 2 main reasons for failure of early decannulation were intractable granulation (in patients with insulin-dependent diabetes) and coexisting tracheal stenosis. Immediate telelaryngoscopy is recommended in all patients who require tracheostomy because of failed extubation. Flexible laryngoscopy is not adequate for thorough assessment of laryngeal damage from prolonged intubation.

Adverse effects of thyroid hormones.

The adverse health effects of thyrotoxicosis have been carefully documented and most practitioners are familiar with the clinical consequences for the patient. Until recently, many patients experienced the adverse effects of excessive thyroxine dosages. Which can now be avoided by the application of highly sensitive immunometric assays for monitoring serum thyrotrophin (thyroid-stimulating hormone; TSH) levels. However, sensitive monitoring of serum thyrotrophin levels has led to the frequent recognition of biochemical subclinical hyperthyroidism (isolated suppression of thyrotrophin). Because of the increased recognition of this condition, the adverse effects of thyroxine therapy can be divided into those associated with subclinical hyperthyroidism and those associated with the euthyroid state. Investigation of the potential clinical consequences of thyrotrophin-suppressing dosages of thyroxine has dominated studies over the last decade, with less attention being given to euthyroid patients. It appears that the adverse effects of thyroxine are considerably more common when serum thyrotrophin has been suppressed. They are usually manifested in older patients as increased bone mineral loss in postmenopausal women and as cardiac effects in patients with intrinsic heart disease. These patients may have subtle behavioural alterations and other clinically silent organ effects that occur infrequently. Children who are euthyroid while taking thyroxine occasionally develop pseudotumour cerebri shortly after starting hormone replacement for hypothyroidism. Otherwise, thyroxine dosages that render patients euthyroid, as evidenced by thyrotrophin values that are within the normal range, rarely cause adverse effects. Thus, avoidance of dosages that cause thyrotrophin suppression, when not clinically indicated, is the primary approach to the management of these adverse effects.

The human HNP36 gene is localized to chromosome 11q13 and produces alternative transcripts that are not mutated in multiple endocrine neoplasia, type 1 (MEN I) syndrome.

Multiple endocrine neoplasia, type 1 (MEN I), is an autosomal dominant syndrome of selected endocrine neoplasms whose causative gene, a suspected tumor suppressor, has been localized to chromosome 11q13, but has not been identified. Recently, the HNP36 cDNA was identified as a novel growth factor responsive gene of undetermined biological function that is expressed in the pituitary and parathyroid glands. In studies seeking the function of the HNP36 gene product, the gene was localized by fluorescence in situ hybridization within the 11q13 segment. Further analysis of radiation-reduced hybrid DNAs and chromosome 11-specific YAC clones established that the HNP36 gene is within 80 kb of D11S913, a marker tightly linked to the MEN1 gene. Consequently, the HNP36 gene was studied as a candidate for the MEN1 gene. The human HNP36 gene was cloned and determined to consist of 12 exons. Expression of the HNP36 gene from pituitary and parathyroid tissue and four patient tumors or lymphoblasts was confirmed by RT-PCR amplification of the coding sequences, and HNP36 transcripts were analyzed for mutations. All tissues expressed three HNP36 gene transcripts that result from alternative splicing and appear to encode related, but distinct, proteins. However, DNA sequence determination of the RT-PCR products from MEN I-associated tumors found no deletions and identified a single nucleotide difference that may be a polymorphism. Thus, mutations in the coding segments of the HNP36 gene are not the cause of the MEN I syndrome. Nevertheless, the assignment of the HNP36 gene to 11q13 and identification of new potential gene products provides a novel growth-regulated genetic candidate for other disorders whose genes map to this locus.

Brain herniation into the middle ear and mastoid: concepts in diagnosis and surgical management.

OBJECTIVE: To review the occurrence characteristics of and clinical repair experience with brain herniation in to the middle ear and mastoid from 1970-1995. STUDY DESIGN: Retrospective chart/case review. SETTING: Private Otology/Neurotology referral practice. PATIENTS: Thirty-five patients with temporal bone brain herniation diagnosed and treated from 1970-1995. INTERVENTION: Diagnosis confirmed by CT and/or MRI. Treatment was surgical. MAIN OUTCOME MEASURES: Success of surgical repair of the problem in a large experience with follow-up of up to 180 months (mean, 48.7 months). RESULTS: Diagnosis is most effectively made by both (computed tomography (CT) and magnetic resonance imaging (MRI). In this series diagnosis was accurate in 89% with MRI. Primary repair was successful in all but three patients, two of whom required a second repair. One was unreconstructable. CONCLUSIONS: Temporal bone encephaloceles occur after ear surgery and in chronic otitis media. Prompt and effective surgical repair is successful and integral to complication avoidance.

MR imaging of skeletal muscle metastases.

OBJECTIVE: The purpose of this article is to describe the MR imaging appearance of skeletal muscle metastases. CONCLUSION: Skeletal muscle metastasis must be considered in patients with a known primary carcinoma who present with a painful muscle mass. Muscle metastasis may be the initial presentation of carcinoma. The MR imaging appearance, although not specific, may provide clues to the diagnosis.

Renal compensation for cecal loss in Gambel's quail (Callipepla gambelii).

Some studies have implicated the avian digestive cecae as important sites of water and solute reclamation working in concert with the lower intestine and the kidneys as part of an integrated osmoregulatory system. In Gambel's quail (Callipepla gambelii), we studied compensatory adjustments in renal function on days 6-7 and 16-17 following ligation of cecae. Plasma osmolality (Posm) varied significantly between groups with sham-operated birds (Cs), with an average (Posm) of 348 mOsm/kg H2O and quail with ligated cecae (Cx) having a (Posm) of 355 mOsm/kg H2O. We detected no change in the rate of glomerular filtration (GFR) between experimental and control groups either shortly after cecectomy or after 16-17 d following surgery. Regression analysis of GFR and urine flow rate (V) showed that Cx birds had a significantly lower V at a given GFR than did controls, evidence that Cx quail absorbed more fluid in their renal tubules. Increased fluid reabsorption was apparently driven by an enhanced reabsorption of sodium. Indeed, sodium excretion was lower in Cx quail as compared to sham-operated birds. On days 6-7, Cx quail drank more water than Cs birds, but by days 16-17 drinking rates were similar. At the end of the experiments, Cx quail showed a proliferation of microvilli along the apical membrane of the rectum, an adjustment consistent with the idea that the rectum alters its absorption capacity to adjust for the loss of cecal function.

Balloon angioplasty with intraluminal stenting as the initial treatment modality in aorto-iliac occlusive disease.

PURPOSE: We retrospectively evaluated balloon angioplasty with intraluminal stenting to define applicability, early results, cost, and length of stay. METHODS: Seventy-three patients underwent 94 aorto-iliac angioplasties with intraluminal stents from October 1991 through July 1993. All had disabling claudication or rest ischemia. RESULTS: Mean follow-up was 10.2 months and was 90.4% complete. Ninety percent of procedures were immediately successful. There were no deaths within 30 days of surgery. Complications occurred in 13%. The ankle:brachial indices improved in all groups. Functional class improved in all groups. In class 4, limb salvage or a benefit on level of amputation was universal. Length of stay ranged 33% to 82% less than when aorto-iliac or aortofemoral bypass were undertaken (diagnosis-related group 39.25). Hospital charges for stent procedures ranged 25% to 66% less than for aorto-iliac or aortofemoral bypass (diagnosis-related group 39.25). CONCLUSION: The procedure is widely applicable, with an apparent initial advantage in mortality, morbidity, charges, and length of stay. Durability is unproven.

Relationships between broodiness expression laying persistency and concentrations of hormones during the first productive period in turkey hens (Meleagris gallopavo).

The changes in egg production, in broodiness index and in plasma concentrations of LH, prolactin, oestradiol and progesterone were monitored throughout the first period of laying in turkey hens. The hens were subsequently classified according to their ability to express broodiness (33%) and their laying persistency; 25% were out-of-lay by the end of the experiment. A high percentage (67%) of the hens that went out-of-lay had previously been identified as broody. Altogether, a significant (p < 0.05) physiological stage effect was found when comparing prolactin, oestradiol and progesterone data obtained from short and long laying persistency hens and this stage effect was also significant for oestradiol and progesterone data obtained from broody and non-broody hens. Otherwise, plasma LH concentrations decreased slightly but significantly throughout the laying year in all hens but no significant differences between physiological states were observed, although the decrease was more pronounced in the hens that went out-of-lay. Plasma progesterone concentrations remained stable throughout in laying hens but decreased significantly in broody and/or out-of-lay hens. Plasma prolactin concentrations were maximal between the 5th and 12th week of egg production and the levels observed in laying hens that did not become broody or had a long laying persistency were twice those measured in broody and/or out-of-lay hens. In the meantime, plasma oestradiol concentrations were lower and stable in laying hens, whereas they were higher during the first half of the productive period in broody and short laying persistency hens. These results suggest that, under our experimental conditions, the hormonal profiles of prolactin and oestradiol for a given hen during the first 10 weeks of the laying cycle may provide predictive information for future changes in its physiological status. The inverse relationship that was observed here between high early plasma concentrations of oestradiol and laying persistency is original. In addition, the relationship between the ability to express broodiness and high and low early plasma concentrations of oestradiol and prolactin, respectively, in hens submitted to preventive broody treatment has not been reported previously. Furthermore, it seems clear that high initial concentrations in prolactin, far from exerting any deleterious effects on egg production are closely associated with a longer persistency of egg laying.

Comparison of the basal and luteinising hormone-releasing hormone induced luteinising hormone release by perifused hypophyses from turkey hens (Meleagris gallopavo) at different physiological stages.

1. An experiment was performed to investigate the weight of the ovary, the oviduct, the pituitary gland, the plasma concentrations of luteinising hormone (LH), progesterone, oestradiol and the responsiveness of the pituitary gland in vitro to doses of Luteinising Hormone-Releasing Hormone (LH-RH) ranging from 10(-10) to 10(-5) M in laying (L), incubating (I) and out-of-lay (OL) turkey hens. 2. Pituitary weights did not differ between the groups but the weights of the ovary and oviduct and the plasma concentrations of progesterone and oestradiol were lower in I and OL than in L hens. The plasma concentrations of LH were lower in I than in L hens. 3. In vitro, the basal release of LH was similar in L and I hens, but significantly higher in OL hens. A slow and linear increase in basal LH release by the glands from I and OL hens was observed throughout the experiment. 4. No clear dose-response relationship was found in any of the reproductive states with respect to LH release in vitro following LH-RH stimulation, probably as a result of partial cell desensitisation. On the other hand, the amount of LH released over basal level in responses to stimulation with different doses of LH-RH were not significantly different between L and I hens, but they were between 5- to 10-fold higher in OL hens, except at the lowest dose. 5. These findings confirm that there is no correlation between circulating LH in turkey hens and the capacity of the hypophysis to release LH in vitro passively or in response to LH-RH. Therefore, the low circulating concentrations of LH in I and OL turkey hens cannot be accounted for by decreased adenohypophyseal responsiveness to LH-RH. They may indicate a low level of hypothalamic secretion of LH-RH and/or to the existence of an inhibitory mechanism on LH secretion in vivo in both OL and I hens.

Inaccuracy of nitrogen balance determinations in thermal injury with calculated total urinary nitrogen.

Many burn centers use nitrogen balance studies to estimate the adequacy of nutritional support. Nitrogen loss includes the sum of urinary urea nitrogen, nonurea urinary nitrogen, and losses from skin, wound, and stool. Urinary urea nitrogen is often used to calculate total urinary nitrogen by multiplying the urinary urea nitrogen by a factor of 1.25 to account for nonurea urinary nitrogen. This formula is appropriate when applied to a nonstressed individual who has fasted overnight but is not appropriate for patients who have undergone surgery or experienced trauma. We have undertaken this study to assess the predictability of this formula in patients with thermal injuries. Twenty-seven patients with major thermal injuries had random 24-hour urine collections, which were analyzed for both urinary urea nitrogen and total urinary nitrogen. In these patients with burns we found that urinary urea nitrogen represented approximately 65% of the directly measured total urinary nitrogen rather than 80% as assumed by the formula. This increase in the nonurea nitrogen loss is greater than that found after surgery or trauma. Individual measurements may underestimate losses by 20% to 60%. Directly measured total urinary nitrogen should replace calculated total urinary nitrogen as the index of urine nitrogen losses for nitrogen balance studies in patients with burns.