A global survey of host, aquatic, and soil microbiomes reveals shared abundance and genomic features between bacterial and fungal generalists

Environmental change, coupled with alteration in human lifestyles, is profoundly impacting the microbial communities critical to the health of the Earth and its inhabitants. To identify bacteria and fungi that are resistant and susceptible to habitat change, we analyze thousands of genera detected in 1,580 host, soil, and aquatic samples. This large-scale analysis identifies 48 bacterial and 4 fungal genera that are abundant across the three biomes, demonstrating fitness in diverse environmental conditions. Samples containing these generalists have significantly higher alpha diversity. These generalists play a significant role in shaping cross-kingdom community structure, boasting larger genomes with more secondary metabolism and antimicrobial resistance genes. Conversely, 30 bacterial and 19 fungal genera are only found in a single habitat, suggesting a limited ability to adapt to different and changing environments. These findings contribute to our understanding of microbial niche breadth and its consequences for global biodiversity loss.

Genome-scale metabolic modeling of Aspergillus fumigatus strains reveals growth dependencies on the lung microbiome

Aspergillus fumigatus, an opportunistic human pathogen, frequently infects the lungs of people with cystic fibrosis and is one of the most common causes of infectious-disease death in immunocompromised patients. Here, we construct 252 strain-specific, genome-scale metabolic models of this important fungal pathogen to study and better understand the metabolic component of its pathogenic versatility. The models show that 23.1% of A. fumigatus metabolic reactions are not conserved across strains and are mainly associated with amino acid, nucleotide, and nitrogen metabolism. Profiles of non-conserved reactions and growth-supporting reaction fluxes are sufficient to differentiate strains, for example by environmental or clinical origin. In addition, shotgun metagenomics analysis of sputum from 40 cystic fibrosis patients (15 females, 25 males) before and after diagnosis with an A. fumigatus colonization suggests that the fungus shapes the lung microbiome towards a more beneficial fungal growth environment associated with aromatic amino acid availability and the shikimate pathway. Our findings are starting points for the development of drugs or microbiome intervention strategies targeting fungal metabolic needs for survival and colonization in the non-native environment of the human lung.

Disruption of the Aspergillus fumigatus RNA interference machinery alters the conidial transcriptome

The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve growth potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we first investigated the genetic variation in RNAi-associated genes in a collection of 217 environmental and 83 clinical genomes, where we found that RNAi components are conserved even in clinical strains. Using endogenously expressed inverted-repeat transgenes complementary to a conditionally essential gene (pabA) or a nonessential gene (pksP), we determined that a subset of the RNAi componentry is active in inverted-repeat transgene silencing in conidia and mycelium. Analysis of mRNA-seq data from RNAi double-knockout strains linked the A. fumigatus dicer-like enzymes (DclA/B) and RNA-dependent RNA polymerases (RrpA/B) to regulation of conidial ribosome biogenesis genes; however, surprisingly few endogenous small RNAs were identified in conidia that could explain this broad change. Although RNAi was not clearly linked to growth or stress response defects in the RNAi knockouts, serial passaging of RNAi knockout strains for six generations resulted in lineages with diminished spore production over time, indicating that loss of RNAi can exert a fitness cost on the fungus. Cumulatively, A. fumigatus RNAi appears to play an active role in defense against double-stranded RNA species alongside a previously unappreciated housekeeping function in regulation of conidial ribosomal biogenesis genes.

Aspergillus fumigatus pan-genome analysis identifies genetic variants associated with human infection

Aspergillus fumigatus is an environmental saprobe and opportunistic human fungal pathogen. Despite an estimated annual occurrence of more than 300,000 cases of invasive disease worldwide, a comprehensive survey of the genomic diversity present in A. fumigatus-including the relationship between clinical and environmental isolates and how this genetic diversity contributes to virulence and antifungal drug resistance-has been lacking. In this study we define the pan-genome of A. fumigatus using a collection of 300 globally sampled genomes (83 clinical and 217 environmental isolates). We found that 7,563 of the 10,907 unique orthogroups (69%) are core and present in all isolates and the remaining 3,344 show presence/absence of variation, representing 16-22% of the genome of each isolate. Using this large genomic dataset of environmental and clinical samples, we found an enrichment for clinical isolates in a genetic cluster whose genomes also contain more accessory genes, including genes coding for transmembrane transporters and proteins with iron-binding activity, and genes involved in both carbohydrate and amino-acid metabolism. Finally, we leverage the power of genome-wide association studies to identify genomic variation associated with clinical isolates and triazole resistance as well as characterize genetic variation in known virulence factors. This characterization of the genomic diversity of A. fumigatus allows us to move away from a single reference genome that does not necessarily represent the species as a whole and better understand its pathogenic versatility, ultimately leading to better management of these infections.

Low rate of azole resistance in cases of avian aspergillosis in Germany

Aspergillosis is the most common fungal disease of the avian respiratory tract. Due to delayed diagnosis and treatment failure, the outcome of these infections is often poor. We investigate 159 cases of avian aspergillosis among captive birds in Germany to define clinical features as well as the frequency of in vitro triazole resistance. Adult birds were more likely to present with clinical signs compared to juvenile birds, and dyspnoea was the most common clinical sign, present in 53% of birds. Molecular species identification indicated that all infections were caused by Aspergillus fumigatus. Only one of 159 independent isolates was azole resistant.

Candida auris in Germany and Previous Exposure to Foreign Healthcare

The emerging yeast Candida auris has disseminated worldwide. We report on 7 cases identified in Germany during 2015–2017. In 6 of these cases, C. auris was isolated from patients previously hospitalized abroad. Whole-genome sequencing and epidemiologic analyses revealed that all patients in Germany were infected with different strains.

Escherichia coli O78 isolated from septicemic lambs shows high pathogenicity in a zebrafish model

The pathogenicity of Escherichia coli O78 strain K46, originally isolated from an outbreak of septicemia in neonatal lambs, was investigated in zebrafish embryo and murine models of infection. Its biofilm potential, cellulose production, and the expression of type 1 pili and curli fimbriae were measured by in vitro assays. The strain was highly pathogenic in the zebrafish embryo model of infection, where it killed all embryos within 24 h post inoculation (hpi) at doses as low as 1000 colony forming units. Zebrafish embryos inoculated with similar doses of commensal E. coli strains showed no signs of disease, and cleared the bacteria within 24 h. E. coli K46 colonized the murine gut at the same level as the uropathogenic E. coli (UPEC) reference strain CFT073 in CBA/J mice after oral inoculation, but infected the murine bladder significantly less than CFT073 after transurethral inoculation. Type 1 pili were clearly expressed by E. coli K46, while curli fimbriae and cellulose production were weakly expressed. The ability to produce biofilm varied in different growth media, but overall E. coli K46 was a poorer biofilm producer compared to the reference strain E. coli UTI89. In conclusion, the zebrafish lethality model provides further evidence that E. coli K46 is highly pathogenic and might be useful in future studies to identify bacterial virulence factors.

Urinary tract infections: current and emerging management strategies

Acute cystitis is one of the most commonly encountered bacterial infections and is responsible for substantial morbidity and high medical costs in the United States and across the globe. Though generally considered to be self-limiting and easily treated with antibiotics, urinary tract infections (UTIs) are often incompletely resolved by antibiotic therapy and frequently recur. This is in part due to the ability of uropathogenic bacteria to invade, replicate, and persist within host epithelial cells. The biological complexity of these infections combined with a dramatic rise in antibiotic-resistant pathogens highlight the need for alternative therapies. In this review we examine current management strategies for UTIs, as well as emerging treatments, including novel compounds that block bacterial interactions with the urothelium and vaccines focused on preventing both acute and recurrent infections.

Supplementation with a combination of beta-hydroxy-beta-methylbutyrate (HMB), arginine, and glutamine is safe and could improve hematological parameters

BACKGROUND

Combining the amino acids arginine and glutamine with the leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) has been shown to reverse lean tissue loss in cancer and acquired immunodeficiency syndrome (AIDS) patients. Although each of these nutrients has been shown to be safe, the safety of this mixture has not been reported. Three double-blind studies examined the safety of the combination of HMB, arginine and glutamine on blood chemistries, hematology, emotional profile, and adverse events.

METHODS

Study 1 was conducted in healthy adult males (n = 34), study 2 was in HIV patients with AIDS-associated weight loss (n = 43), and study 3 was in cancer patients with wasting (n = 32). Volunteers were assigned to either a placebo or a mixture of 3 g HMB, 14 g arginine, and 14 g glutamine per day.

RESULTS

Across the 3 studies, HMB, arginine, and glutamine supplementation was not associated with any adverse indicators of health. The only significant changes noted were positive indicators of health status. HMB, arginine, and glutamine supplementation was associated with an improvement in emotional profile (p = .05), a decreased feeling of weakness (p = .03), and increased red blood cells, hemoglobin, hematocrit, lymphocytes, and eosinophils (p < .05) when compared with placebo-supplemented subjects. Blood creatinine levels were not changed. However, blood urea nitrogen increased (p = .01) with HMB, arginine, and glutamine supplementation, which was possibly caused by the additional nitrogen consumed or to the fact that ureagenesis is influenced by arginine and glutamine supplementation.

CONCLUSION

These results show that HMB, arginine, and glutamine can be safely used to treat muscle wasting associated with AIDS and cancer.

Improved survival with early fluid resuscitation following hemorrhagic shock

Recent studies have questioned the benefits of early fluid resuscitation in hemorrhagic shock. The purpose of the current study is to evaluate the effects of early fluid resuscitation (HSE) (15 minutes), delayed fluid resuscitation (HSD) (60 minutes), and no fluid resuscitation (HSU) on cytokine levels, hepatic resting membrane potential (Em), renal function, and mortality. Eighty male Sprague-Dawley rats (350-450 g) were hemorrhaged 35% of their total blood volume and then received 40, 80, or 100 ml of crystalloid per kilogram as intravenous fluids (IVFs). The implementation of HSE resulted in stabilization of the Em (-29 mV), which was significantly different from that seen with HSD or HSU (-24 and -29 mV, respectively). The timing of resuscitation did not affect the elevation of tumor necrosis factor (TNFalpha) levels. The interleukin-6 (IL-6) levels for the HSE group were 81, 101, and 274 pg/ml for 40, 80, and 100 ml/kg, respectively. In contrast, HSD group IL-6 levels were 440, 566, and 632 pg/ml for 40, 80, and 100 ml/kg (p < 0.0001). IL-6 levels for the HSU group was 427 pg/ml, which was significantly different from that of the HSE group (p < 0.05). Urine output was present in 58% of the HSE rats but only 24% in the HSD rats and 0% of the HSU rats. Mortality was 11% for HSE, 58% for HSD, and 50% for HSU rats. Despite the recent studies questioning the benefits of early fluid resuscitation, these data show marked improvement in hepatic stability, the presence of urine output, decreased IL-6 levels, and significantly lower mortality when IVFs were given early after hemorrhagic shock. Furthermore, excessive fluid resuscitation (100 ml/kg) resulted in an increased inflammatory cytokine level and mortality and may account for the controversy.

Matrix metalloproteinase inhibition protects hepatic integrity in hemorrhagic shock

Hemorrhagic shock increases cytokines, such as tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6), and compromises hepatic function and integrity. The production of TNF-alpha involves a cascade reaction regulated by the enzyme TNF-alpha convertase. The purpose of this study was to examine the effects of matrix metalloproteinase inhibitor (MMPI) (British Biotech 1101) in vivo on hepatic integrity in a rat model of hemorrhagic shock. Sprague-Dawley rats (n = 26) were divided as follows: hemorrhagic shock (group 1) and hemorrhagic shock plus MMPI (group 2). TNF-alpha, IL-6, and hepatic membrane potentials (Em) were obtained. The administration of MMPI significantly decreased TNF-alpha levels (P <0.001) and stabilized the membrane potential at -30 mV as compared to the depolarized membrane potential at -20 mV for hemorrhagic shock without MMPI. IL-6 levels were not affected by the MMPI. This study demonstrates that MMPI decreases TNF-alpha levels and protects hepatic integrity in hemorrhagic shock, as evidenced by the stabilization of the membrane potential, independent of the mean arterial pressure. The hepatic protection is closely related to the decrease in TNF-alpha levels seen in the portal circulation.

Hepatic integrity dependent on matrix metalloproteinase inhibition, not tumor necrosis factor alpha or different bleeding rates

Discrepancies in the levels of proinflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha) following hemorrhagic shock (HS) may be due to the inconsistent rates of bleeding. The purpose of this study was to investigate the effects of rapid versus slow bleeding rates on TNF-alpha levels and if inhibition of TNF-alpha convertase by a matrix metalloproteinase inhibitor (MMPI) affects hepatic integrity in animals exposed to 35% HS. Sprague-Dawley male rats (n = 24, 300-350 g) were divided into four groups: HS 15 (produced over 15 min), HS 30 (produced over 30 min), and HS with MMPI (2.5 mg/kg British Biotech 1101: HS15 + MMPI, HS30 + MMPI). Mean arterial blood pressure (MAP), serum TNF-alpha,levels, and hepatic resting membrane potentials (E(m)) were obtained. A Student t test was performed. TNF-alpha levels for HS 15, HS15 + MMPI, HS 30, and HS 30 + MMPI were 474, 40, 32, and 50 pg/ml, respectively. The hepatic resting membrane potentials for HS 15, HS15 + MMPI, HS 30, and HS 30 + MMPI were -26, -30, -23, and -31 mV, respectively. In conclusion, circulating TNF-alpha levels are affected by the rate of bleeding in hemorrhagic shock. However, despite the differences in the magnitude of TNF-alpha in untreated animals, hepatic integrity was compromised. Interestingly, MMPI, an inhibitor of TNF-alpha convertase, stabilizes the membrane potential in both types of hemorrhagic shock.

Gastric bypass procedures

Surgical therapy to help the severely overweight has been performed for the past 40 years. As with every therapeutic modality, there have been changes, refinements and improvement as this therapy has evolved. Although the basic concept of gastric bypass remains intact, numerous variations are being performed at this time. Recent data compiled by the International Bariatric Surgery Registry have demonstrated that surgeons are moving from simple gastroplasty procedures, favouring the more complex gastric bypass procedures as the surgical treatment of choice for the morbidly obese patient. This review will discuss the evolution of the gastric bypass procedures, and the reasons for and results of the changes. Gastric bypass may represent the best surgical approach for the treatment of morbid obesity.

Early isotonic saline resuscitation from uncontrolled hemorrhage in rats

BACKGROUND

Attempts to modify traditional fluid resuscitation have been based on animal models that evaluate several variables including anesthesia. This study presents the effects of early saline resuscitation from severe uncontrolled hemorrhage unanesthetized rats.

METHODS

Sixty-three female Sprague-Dawley rats were equally divided into three groups: group A, nonresuscitated; and groups B and C, resuscitated ;with isotonic saline (40 and 80 mL/kg, respectively). Hemodynamics, blood loss, survival time, and mortality were recorded for 360 minutes after the hemorrhage, which was initiated by 75% resection of the tail.

RESULTS

In group C, 80 mL/kg of saline significantly lowered mortality (24% vs 76% and 71% for groups A and B, respectively) with concomitant increases in mean survival time (241 +/- 103 min vs 146 +/- 108 and 175 +/- 92 min for groups A and B, respectively). There were no statistically significant differences in blood loss, hematocrit, or hemodynamic parameters among the groups.

CONCLUSIONS

Early and adequate isotonic saline resuscitation of unanesthetized rats improved outcome despite continuing hemorrhage. The significantly lower mortality rate and increased survival time were not a result of transiently improved arterial pressure and did not correlate with blood loss. No significant bleeding increases were noted in the resuscitated groups.

Hypercortisolemia increases plasma interleukin-10 concentrations during human endotoxemia--a clinical research center study

Hypercortisolemia directly before the administration of endotoxin (LPS) to normal humans completely prevents the release of the proinflammatory cytokine tumor necrosis factor, whereas hypercortisolemia 12 h to 7 days before the injection of LPS is associated with enhanced tumor necrosis factor release. To determine the effect of elevated cortisol levels on the secretion of the antiinflammatory cytokine interleukin-10 (IL-10), 23 healthy men were given iv LPS (lot EC-5; 2 ng/kg) alone or in combination with a continuous iv infusion of hydrocortisone (3 micrograms/kg.min) for 6 h immediately before or 6, 12, or 144 h before LPS injection. LPS induced a monophasic increase in plasma IL-10 concentrations that peaked after 2 h (162 +/- 27 pg/mL; P < 0.0001). In subjects who were infused with hydrocortisone directly before LPS administration, IL-10 concentrations were much higher (1784 +/- 331 pg/mL; P < 0.0001 vs. LPS only), whereas hypercortisolemia 6, 12, or 144 h before LPS injection did not influence LPS-induced IL-10 levels. In human whole blood in vitro, hydrocortisone caused a dose-dependent reduction of LPS-induced IL-10 levels. Further, hydrocortisone reversed the increase in IL-10 concentrations by epinephrine in LPS-stimulated whole blood. Stimulation of IL-10 release may contribute to the antiinflammatory properties of glucocorticoids.

Cell damage after shock

Hypoperfusion of tissue results in cell membrane dysfunction. Normally, the cell membrane serves to preserve the milieu interior through the maintenance of a negative charge or membrane potential. Maintenance of a negative membrane potential across the cell membrane serves as a semipermeable barrier, preserving the balance of intra- and extracellular electrolytes and water.

Influence of hypercortisolemia on soluble tumor necrosis factor receptor II and interleukin-1 receptor antagonist responses to endotoxin in human beings

BACKGROUND

We have previously reported that the antecedent administration of glucocorticoids altered both the hormonal and proinflammatory cytokine responses to lipopolysaccharide (LPS) when administered to human volunteers. In that study, subjects with vastly exaggerated levels of tumor necrosis factor (TNF) and interleukin (IL)-6 12 and 144 hours after cortisol infusion exhibited hemodynamic and hormonal responses no different from those of untreated subjects after endotoxin. The current study examined levels of the antiinflammatory cytokines interleukin-1 receptor antagonist (IL-1ra) and soluble receptors to tumor necrosis factor (sTNF-R) in the same setting of the previous report.

METHODS

Hydrocortisone succinate was infused into healthy volunteers. LPS was then injected immediately or was delayed by 6, 12, or 144 hours (C, C-6, C-12, and C-144, respectively). Subjects receiving LPS alone served as controls. Plasma was analyzed to determine levels of TNF, sTNF-R and IL-1ra by enzyme-linked immunosorbent assay before administration of LPS and at 30-minute intervals after administration of LPS for 6 hours.

RESULTS

Levels of sTNF-R increased after LPS administration in all groups (p < 0.05 versus baseline) with a significantly higher level recorded in the subjects having received hydrocortisone 144 hours before (C-144, p < 0.05 versus all other groups). TNF levels remained undetectable in association with immediate infusion of LPS (C) and the relatively short delay group (C6). This cytokine peaked 90 minutes after LPS in all other groups, with a significantly higher peak in the C-144 subjects when compared with controls. IL-1ra levels rose in all groups but to a lesser extent in the C group (p < 0.05).

CONCLUSIONS

These data confirm that glucocorticoids influence the production of both sTNF-R and IL-1ra. The potential for an exaggerated response of sTNF-R exists for an extended period of time after exposure to glucocorticoids.

Isotonic saline resuscitation in uncontrolled hemorrhage under various anesthetic conditions

OBJECTIVE

The authors evaluated the effect of early fluid resuscitation with isotonic saline (NaCl, 0.9%) on uncontrolled hemorrhage in rats under different anesthetic conditions. SUMMARY/BACKGROUND DATA: Recently, it has been suggested that administration of fluids to patients during uncontrolled hemorrhage may produce adverse effects, and a postponement of resuscitation until surgical control of bleeding was recommended. Past clinical trials were inconclusive, and the results of recent experimental studies were affected by use of vasoactive anesthetics.

METHODS

One hundred thirty-five female Sprague-Dawley rats were randomly divided into three groups: group 1--unanesthetized; group 2--anesthetized with sodium pentobarbital; and group 3--anesthetized with a mixture of droperidol and ketamine. Uncontrolled hemorrhage was initiated with a 75% tail resection, and each group was further subdivided into three subgroups for the following treatment: (A) no resuscitation; (B) 40 mL/kg of isotonic saline; or (C) 80 mL/kg of isotonic saline, administered 15 minutes after the initiation of hemorrhage. Blood loss volume and survival time were recorded, and animals were observed up to 360 minutes.

RESULTS

At 6 hours, nonresuscitated animals of all groups exhibited the highest mortality rates (93%, 73%, 100% in groups 1, 2, and 3, respectively). Resuscitation significantly improved the survival; lowest mortality rates were observed after resuscitation with 80 mL/kg in groups 1 and 3 (33%) and 40 mL/kg in group 2 (40%). Fluid infusion increased hemorrhage rates in all anesthetized rats. No such increases in bleeding were observed in group 1.

CONCLUSIONS

Resuscitation with isotonic saline improved mortality in uncontrolled hemorrhage, even with concomitant increases in hemorrhage rates, under all three anesthetic conditions tested. Unanesthetized rats bled less than the animals under anesthesia and did not exhibit an increased blood loss in response to fluid infusion.

The effects of isotonic saline volume resuscitation in uncontrolled hemorrhage

In the present study, the effects of early isotonic fluid resuscitation on uncontrolled hemorrhage in rats under pentobarbital anesthesia were assessed. Forty-five female Sprague-Dawley rats, weighing between 230 and 295 grams, were anesthetized and cannulated. Uncontrolled hemorrhage was initiated by a 75 percent tail resection, and the rats were randomly divided into three groups: group 1, no resuscitation; groups 2 and 3, saline solution administration over a four minute interval (40 and 80 milliliters per kilogram, respectively), 15 minutes after the initial hemorrhage. Changes in blood pressure, blood loss and mortality rates were recorded and the rats were observed for up to 360 minutes. The mortality rates were 73, 40 and 53 percent for groups 1, 2 and 3, respectively. The corresponding average survival times for these groups were 135, 195 and 178 minutes. The difference between groups 1 and 2 were above the 95 percent confidence level using the chi-square test (mortality) and the Student's t test. The average total blood loss in groups 2 and 3 was 31.7 and 41.4 milliliters per kilogram of body weight; when compared with group 1 (24.6 milliliters per kilogram), the difference between the two latter groups (1 and 3) was statistically significant with a p < 0.001. These results suggest that early infusion of isotonic fluid improves survival time and reduces short term mortality in uncontrolled hemorrhage regardless of the associated increases in blood loss.

Glucocorticoid therapy alters hormonal and cytokine responses to endotoxin in man

Previous experimental data have demonstrated that steroid pretreatment regulates endotoxin-elicited cytokine production. The timing of such hypercortisolemia also appears to be a major determinant of both the systemic and the cytokine response to infectious stimuli. Our study was undertaken to further study the in vivo influence of glucocorticoid infusion concurrent with and before endotoxin exposure in man. A total of 23 normal human subjects were given endotoxin (LPS) alone or pretreated with hydrocortisone infusion for 6 h immediately before and concomitant to LPS administration; or rendered hypercortisolemic for a 6-h period waiting 6, 12, or 144 h before LPS administration. LPS administration was followed by significant elevations in temperature (1.9 +/- 0.3 degrees C), pulse (29 +/- 6 bpm), and resting energy expenditure (26.2 +/- 0.4 kcal/kg/day) as well as epinephrine (236 +/- 59 pg/ml), cortisol (296 +/- 29), and C-reactive protein (4.2 +/- .03 mg/dl) as compared with base-line values. Levels of TNF and IL-6 that were not detectable before LPS administration, peaked, respectively, at 90 and 120 min after LPS (155 +/- 4 pg/ml, 12 +/- 1 U/ml). Glucocorticoids when given immediately before and concomitant with LPS significantly attenuated the temperature (0.8 +/- 0.01 degrees C) and pulse rate response (10 +/- 3 bpm) seen after LPS alone as well as suppressing peak levels of epinephrine (78 +/- 14 pg/ml) and C-reactive protein (undetected). TNF remained undetectable in this group although the IL-6 response (14 +/- 1 U/ml) was unchanged. With a 6-h interval between hydrocortisone infusion and LPS challenge, changes in temperature, pulse, resting energy expenditure, and hormone levels were similar to those seen after LPS alone whereas TNF remained undetectable and IL-6 levels were similar to subjects receiving LPS alone. Subjects receiving LPS after 12 or 144 h after hydrocortisone infusion displayed hemodynamic and hormonal responses similar to the LPS alone group, yet mounted significantly greater circulating levels of both IL-6 (117 +/- 14 U/ml, 160 +/- 51 U/ml at 12 and 144 h) and TNF (609 +/- 173, 671 +/- 132 pg/ml at 12 and 144 h) to those observed after LPS alone. We conclude that antecedent periods of hypercortisolemia participate in regulation of the hemodynamic, hormonal, and cytokine responses to endotoxin and that a complex temporal relationship between hypercortisolemia and LPS induced cytokine and systemic responses exists.

Glucocorticoid therapy alters hormonal and cytokine responses to endotoxin in man

Previous experimental data have demonstrated that steroid pretreatment regulates endotoxin-elicited cytokine production. The timing of such hypercortisolemia also appears to be a major determinant of both the systemic and the cytokine response to infectious stimuli. Our study was undertaken to further study the in vivo influence of glucocorticoid infusion concurrent with and before endotoxin exposure in man. A total of 23 normal human subjects were given endotoxin (LPS) alone or pretreated with hydrocortisone infusion for 6 h immediately before and concomitant to LPS administration; or rendered hypercortisolemic for a 6-h period waiting 6, 12, or 144 h before LPS administration. LPS administration was followed by significant elevations in temperature (1.9 +/- 0.3 degrees C), pulse (29 +/- 6 bpm), and resting energy expenditure (26.2 +/- 0.4 kcal/kg/day) as well as epinephrine (236 +/- 59 pg/ml), cortisol (296 +/- 29), and C-reactive protein (4.2 +/- .03 mg/dl) as compared with base-line values. Levels of TNF and IL-6 that were not detectable before LPS administration, peaked, respectively, at 90 and 120 min after LPS (155 +/- 4 pg/ml, 12 +/- 1 U/ml). Glucocorticoids when given immediately before and concomitant with LPS significantly attenuated the temperature (0.8 +/- 0.01 degrees C) and pulse rate response (10 +/- 3 bpm) seen after LPS alone as well as suppressing peak levels of epinephrine (78 +/- 14 pg/ml) and C-reactive protein (undetected). TNF remained undetectable in this group although the IL-6 response (14 +/- 1 U/ml) was unchanged. With a 6-h interval between hydrocortisone infusion and LPS challenge, changes in temperature, pulse, resting energy expenditure, and hormone levels were similar to those seen after LPS alone whereas TNF remained undetectable and IL-6 levels were similar to subjects receiving LPS alone. Subjects receiving LPS after 12 or 144 h after hydrocortisone infusion displayed hemodynamic and hormonal responses similar to the LPS alone group, yet mounted significantly greater circulating levels of both IL-6 (117 +/- 14 U/ml, 160 +/- 51 U/ml at 12 and 144 h) and TNF (609 +/- 173, 671 +/- 132 pg/ml at 12 and 144 h) to those observed after LPS alone. We conclude that antecedent periods of hypercortisolemia participate in regulation of the hemodynamic, hormonal, and cytokine responses to endotoxin and that a complex temporal relationship between hypercortisolemia and LPS induced cytokine and systemic responses exists.

Effect of cyclosporine on adrenocortical response to injury and infection

The effects of cyclosporine administration on the adrenocortical response to the severe stress of burn wound sepsis were studied in Wistar rats. Animals were treated with cyclosporine (10 mg/kg/day) or saline by gavage for 10 days, then subjected to 30% scald burns with wound inoculation with Pseudomonas. Animals were sacrificed on Postburn Days (PBDs) 1, 4, and 7 for determination of serum corticosterone and ACTH levels and adrenal weights and histology. Adrenal glands from animals sacrificed on PBD 7 were also analyzed for DNA, RNA, and protein content. Cyclosporine treatment without injury had no significant effect on body weight gain, adrenal mass, or baseline ACTH or corticosterone levels. During sepsis, cyclosporine-treated animals demonstrated a significantly diminished adrenocortical response compared to those given only saline. Serum corticosterone levels in the cyclosporine group were 45, 53, and 62% lower on PBDs 1, 4, and 7, respectively, than in saline-treated controls (P < 0.01 on each day). ACTH levels were 43 and 36% lower in cyclosporine-treated animals on PBDs 4 and 7, respectively, compared to the saline-treated group (P < 0.05 on each day). Adrenal hyperplasia occurred in both groups by PBD 7, but increases in adrenal mass and in histologic changes associated with hyperplasia (lipid depletion, vascular dilation) were less pronounced in cyclosporine-treated animals compared to those receiving saline, while adrenal composition remained similar between the two groups. Thus, cyclosporine administration is associated with an attenuated adrenocortical response to the stress of sepsis due to diminished circulating levels of ACTH.

Effect of sepsis on intracellular sodium activity, sodium concentration, and water content in thermal injured rat

The effects of sepsis on intracellular Na+ activity, Na+ concentration, and H2O partition in skeletal muscle were investigated in a burn rat model. Studies were performed on either postburn day 3 or day 7 during evolving burn wound sepsis. Data are compared among 3 groups of rats: burned and infected (BI), burned not infected (B), and sham burn (C). After 3 days postburn both Na+ activity and concentration decreased in the BI group as compared with B and C groups. By postburn day 7, the BI group developed septic shock and had increased intracellular Na+ activity and concentration. The resting membrane potentials of skeletal muscle cells depolarized. The finding of an increased cell membrane relative permeability of Na+ to K+ could account for the increase in Na+ influx into cells. In addition, intracellular and total muscle H2O contents decreased and extracellular H2O increased. Hypernatremia, hyperchloremia, and hyperosmolality were also observed in the BI group. However, the fact that there was no significant difference between B and C groups indicates that the late derangements were due to septic shock rather than simple burn injury. Thus, the deleterious effects of the evolving burn wound sepsis on Na+ homeostasis might be due to the detrimental effect of increased intracellular Na+ activity on mitochondrial respiratory control with subsequent impairment of cellular functions.

Effect of combined cortisol-endotoxin administration on peripheral blood leukocyte counts and phenotype in normal humans

We studied the role of lipopolysaccharide and the associated hypercortisolemic response as mediators of leukocyte changes associated with endotoxemia. Normal human subjects were given continuous, 12-hour, intravenous infusions of cortisol. After 6 hours of cortisol infusion, lipopolysaccharide (20 U/kg) was administered in an intravenous bolus. Plasma cortisol and blood leukocyte counts and lymphocyte subset proportions were evaluated every hour throughout the 12-hour study period. After 6 hours of cortisol infusion, lymphocyte counts and proportions of CD4+ helper/inducer T cells had declined significantly. The fact that these cells did not decline further in response to lipopolysaccharide and continued cortisol infusion suggests that lipopolysaccharide-induced lymphocyte changes are cortisol dependent. In contrast, the granulocytosis normally observed after lipopolysaccharide administration was unaffected by cortisol infusion. Finally, the monocyte counts and proportions of B cells (HLA-DR+ or CD20+ cells) responded to cortisol infusion and LPS in a pattern distinct from that of lipopolysaccharide alone. These results indicate that lipopolysaccharide-induced hypercortisolemia plays a role in immune modulation during endotoxemia.

Splanchnic vasoconstriction and bacterial translocation after thermal injury

Gut barrier failure and bacterial translocation (BT) after thermal injury may result from splanchnic vasoconstriction and intestinal ischemia. The role of the renin-angiotensin system in intestinal blood flow and BT after thermal injury was studied by pretreatment with the angiotensin-converting enzyme (ACE) inhibitor enalapril in Wistar rats before sham or 30% scald burn. Adequacy of ACE inhibition was documented by the absence of a hypertensive response to angiotensin I, and intestinal blood flow was determined using 51Cr-labeled microspheres. Small bowel blood flow was decreased by 46% at 4-h postburn (P less than 0.05) in untreated burned animals despite maintenance of normal cardiac index but returned to baseline levels by 24 h after injury. Enalapril pretreatment resulted in maintenance of small bowel blood flow after thermal injury and was associated with a significantly reduced incidence of BT (20% vs. 75% in untreated burned animals, P less than 0.01). These findings further implicate intestinal ischemia in the etiology of gut barrier dysfunction after thermal injury, mediated in part by activation of the renin-angiotensin system.

Comparison between effects of interleukin-1 alpha administration and sublethal endotoxemia in primates

Interleukin (IL)-1 is an early mediator of host response to inflammation, although its contribution to individual components of the acute phase reaction is still unclear. To evaluate how the hemodynamic, metabolic, and hormonal responses to sublethal endotoxemia compare with IL-1 administration, baboons received intravenously either lipopolysaccharide (LPS) or 0.1, 10, or 100 micrograms/kg IL-1 alpha. LPS induced an early tachycardia and a fall in mean arterial pressure, as well as lacticacidemia and hypoaminoacidemia. Similar hemodynamic and metabolic changes were seen with 10 or 100 micrograms/kg of IL-1 alpha. An increase in adrenocorticotropic hormone and fall in serum iron were induced by IL-1 alpha but not by LPS. Plasma tumor necrosis factor-alpha (TNF-alpha) was not measurable after IL-1 alpha administration, whereas LPS induced a monophasic TNF-alpha response. IL-6 levels were significantly greater after LPS than IL-1 alpha administration. Histopathological lesions, similar in LPS- and 100 micrograms/kg IL-1 alpha-treated groups, were present only in the adrenal cortex. We conclude that many, but not all, of the effects of sublethal endotoxemia can be replicated by IL-1 alpha administration, and these responses are dose dependent.

Differential pathophysiology of bacterial translocation after thermal injury and sepsis

Bacterial translocation (BT) occurs transiently after thermal injury and may result from an ischemic intestinal insult. To evaluate continued intestinal ischemia in the ongoing BT associated with sepsis after injury, rats were randomized to (1) 30% burn injury with Pseudomonas wound infection (BI), (2) BI + fluid resuscitation (BI + Fluid), (3) BI after allopurinol pretreatment to inhibit xanthine oxidase (BI + Allo), or (4) BI after azapropazone pretreatment to inhibit neutrophil degranulation (BI + Aza). On postburn days (PBD) 1, 4, and 7, animals were studied for evidence of BT and intestinal lipid peroxidation. BI + Fluid, BI + Allo, and BI + Aza significantly (p less than 0.05) reduced rates of BT and ileal lipid peroxidation acutely after thermal injury (PBD 1) compared to BI. All four groups had equally high rates of BT associated with the onset of sepsis (PBDs 4 and 7), without evidence of further intestinal lipid peroxidation. These data indicate that the chronic gut barrier failure associated with sepsis after injury occurs independently of continued intestinal ischemia.

Bacterial overgrowth and intestinal atrophy in the etiology of gut barrier failure in the rat

Bacterial translocation occurs in animal models of shock, trauma, sepsis, and parenteral or elemental enteral alimentation. Bowel atrophy and cecal bacterial overgrowth have both been implicated in the pathophysiology of bacterial translocation in many of these models. To further define the etiology of bacterial translocation resulting from dietary manipulations, rats were fed a elemental/defined-formula diet (DFD) for 2 weeks ad libitum and then randomized to either intestinal decontamination with a nonabsorbable antibiotic (neomycin) or no antibiotic treatment. Neomycin treatment significantly (p less than 0.01) reduced the incidence of bacterial translocation after DFD, in association with a significant reduction in the number of cecal gram-negative bacteria. Neither loss of bowel mass after DFD nor bowel composition was affected by oral neomycin. Bacterial translocation after DFD would thus appear to be the result of cecal bacterial overgrowth rather than a loss of a physical intestinal barrier due to atrophy.

Pathophysiologic glucocorticoid levels and survival of translocating bacteria

Burn wound sepsis in rats results in sustained corticosterone elevations and the prolonged presence of translocated bacteria in the mesenteric lymph nodes (MLNs). To determine if survival of bacteria in the MLNs may be influenced by pathophysiologic corticosterone levels, MLNs were quantitatively analyzed from rats randomized to the following groups: burn wound sepsis (BI); BI with adrenocortical response attenuated by cyclosporine (cyclosporine/BI); or cyclosporine/BI with corticosterone replacement (cyclosporine/BI + P). Although rates of bacterial translocation were similar, corticosterone levels were significantly different among the three groups and correlated with the number of lymphocytes and the number of enteric bacteria present per gram of MLN. Thus, pathophysiologic elevations of corticosterone levels during sepsis may exert an effect that allows survival of translocated bacteria in the MLNs of rats, perhaps due to glucocorticoid-associated alterations in regional immunity.

Unknown primary squamous cell carcinoma metastatic to the neck

We analyzed retrospectively 157 cases of metastatic neck squamous cell carcinoma from unknown primary sites, treated with surgery, radiotherapy, excisional biopsy, and combined modalities. Median follow-up was 74 months, and overall actuarial survival was 55% at 5 years. The surgery-treated group, despite a higher rate of manifesting primary tumors, had significantly better survival at 5 years compared with those receiving radiation therapy, of whom 23% had residual disease after treatment. Primary tumors were discovered during follow-up in 16% overall. Different treatments yielded comparable results in lower-staged neck disease (NX, N1, N2a), while surgery appeared more effective in controlling advanced disease (N2b, N3a). Factors that affected survival include neck stage, connective tissue invasion, and presence of recurrent or residual disease after treatment.

Additive effects of thermal injury and infection on the small bowel

Thermal injury is associated with functional alterations of multiple organ systems, including the gastrointestinal tract. To study the effects of ongoing infection after thermal injury on bowel mass, composition, and blood flow, male Wistar rats were randomized to receive either 30% scald burn, 30% scald burn with Pseudomonas aeruginosa wound inoculation, sham burn, or sham burn with pair feeding to burned and infected animals. On days 3 and 7 after injury, intestinal blood flow was measured with 51Cr-labeled microspheres, and intestinal mass and composition were analyzed. Burned and infected animals demonstrated a chronic loss of small bowel mass not seen in burned animals without infection by day 7 after injury. Compositional alterations of the small bowels of burned and infected animals included protein wasting similar to but occurring earlier than that seen with anorexia alone and significantly decreased deoxyribonucleic acid and ribonucleic acid content, whereas tissue water content remained unchanged. These chronic intestinal alterations in the burned and infected group could not be explained by ongoing ischemia because intestinal blood flow in these animals was not significantly altered at either time point, implying mediation by other pathophysiologic mechanisms.

Harry M. Vars award. Glutamine or fiber supplementation of a defined formula diet: impact on bacterial translocation, tissue composition, and response to endotoxin

Despite provision of adequate calories, defined formula diets in rats lead to bacterial translocation (BT), fatty infiltration of the liver, and an increased susceptibility to endotoxin. These deleterious effects may be due in part to a loss of intestinal barrier integrity resulting from bowel atrophy. Defined formula diets lack both glutamine and fiber, substances which may help maintain intestinal mass. To determine whether supplementation of defined formula diets with either glutamine or fiber might prevent bowel atrophy and, thus, BT, hepatic steatosis, and the altered response to endotoxin, Wistar rats were fed (1) defined formula diet ad libitum (DFD), (2) (DFD + 2% (w/v) glutamine, (GLUT), or (3) DFD + 2% (w/v) psyllium (FIBER). Rats given standard food isocalorically pair-fed to DFD were used as controls. Nutritional status was assessed by daily weight gain, as well as the ability to maintain serum albumin, hematocrit and white blood counts. After 2 weeks of these feeding regimens, animals were sacrificed, and organ weights and composition were determined, with rates of bacterial translocation determined by mesenteric lymph node, abdominal viscera, and cecal cultures. Additional animals receiving the same experimental diets were subsequently challenged with endotoxin and observed for mortality with rates of post-endotoxin BT and the responses of acute phase proteins and cytokines measured. All dietary regimens resulted in equivalent weight gain and other nutritional parameters. Both glutamine and fiber supplementation maintained small bowel mass, but only GLUT preserved normal jejunal mucosal architecture. Neither fiber nor glutamine supplementation prevented cecal bacterial overgrowth or BT, resulting from the DFD.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibiotic prophylaxis diminishes bacterial translocation but not mortality in experimental burn wound sepsis

Pseudomonas (PSA) burn wound sepsis results in prolonged bacterial translocation (BT) of enteric organisms such as E. coli to the mesenteric lymph nodes (MLN) and organs in rats. Intestinal decontamination with oral antibiotics may improve mortality after burn injury, perhaps due to decreased BT. To determine the effect of oral antibiotic prophylaxis effective against E. coli but not PSA on BT and subsequent mortality in a model of PSA burn wound sepsis, rats were given a 30% scald burn and wound inoculation with 10(8) PSA followed by randomization to either ampicillin (50 mg/kg/d) or saline gavage. Cultures of MLN, organs, blood, and cecal contents were obtained on days 1, 4, and 7 after injury, with additional animals observed for 14-day mortality. Although oral antibiotic prophylaxis resulted in increased cecal colony counts, the incidence of BT was unchanged. The number of organisms present in both the MLN and organs, however, was significantly reduced with prophylaxis, indicating cecal overgrowth by non-translocating bacteria. Reduction of the number of translocating organisms did not result in improved mean survival time after injury, suggesting that mortality from PSA burn wound sepsis occurs independently of bacterial translocation.

Bacterial translocation and intestinal atrophy after thermal injury and burn wound sepsis

Bacterial translocation (BT) occurs after thermal injury in rodents in association with intestinal barrier loss. Infection complicating thermal injury may also affect the intestine producing bowel atrophy. To study these relationships, Wistar rats received either 30% scald followed by wound inoculation with Pseudomonas; 30% scald with pair feeding to infected animals; or sham injury as controls. On days 1, 4, and 7 after injury animals were killed with examination of the bowel and culture of the mesenteric lymph nodes (MLN), livers, spleens, and blood. All burned animals demonstrated BT to the MLN on day 1 after injury, but only burn-infected animals had continued BT on days 4 and 7, with progression of BT to the abdominal organs and blood. Burn injury and infection also resulted in significant atrophy of small bowel mucosa temporally associated with continued BT. Thus injury complicated by infection results in prolonged and enhanced bacterial translocation, perhaps due to failure to maintain the mucosal barrier.