Genetic associations with viral respiratory illnesses and asthma control in children

BACKGROUND

Viral respiratory infections can cause acute wheezing illnesses in children and exacerbations of asthma.

OBJECTIVE

We sought to identify variation in genes with known antiviral and pro-inflammatory functions to identify specific associations with more severe viral respiratory illnesses and the risk of virus-induced exacerbations during the peak fall season.

METHODS

The associations between genetic variation at 326 SNPs in 63 candidate genes and 10 phenotypes related to viral respiratory infection and asthma control were examined in 226 children enrolled in the RhinoGen study. Replication of asthma control phenotypes was performed in 2128 children in the Copenhagen Prospective Study on Asthma in Childhood (COPSAC). Significant associations in RhinoGen were further validated using virus-induced wheezing illness and asthma phenotypes in an independent sample of 122 children enrolled in the Childhood Origins of Asthma (COAST) birth cohort study.

RESULTS

A significant excess of P values smaller than 0.05 was observed in the analysis of the 10 RhinoGen phenotypes. Polymorphisms in 12 genes were significantly associated with variation in the four phenotypes showing a significant enrichment of small P values. Six of those genes (STAT4, JAK2, MX1, VDR, DDX58, and EIF2AK2) also showed significant associations with asthma exacerbations in the COPSAC study or with asthma or virus-induced wheezing phenotypes in the COAST study.

CONCLUSIONS

We identified genetic factors contributing to individual differences in childhood viral respiratory illnesses and virus-induced exacerbations of asthma. Defining mechanisms of these associations may provide insight into the pathogenesis of viral respiratory infections and virus-induced exacerbations of asthma.

Genome-wide association study of body mass index in 23 000 individuals with and without asthma

BACKGROUND

Both asthma and obesity are complex disorders that are influenced by environmental and genetic factors. Shared genetic factors between asthma and obesity have been proposed to partly explain epidemiological findings of co-morbidity between these conditions.

OBJECTIVE

To identify genetic variants that are associated with body mass index (BMI) in asthmatic children and adults, and to evaluate if there are differences between the genetics of BMI in asthmatics and healthy individuals.

METHODS

In total, 19 studies contributed with genome-wide analysis study (GWAS) data from more than 23 000 individuals with predominantly European descent, of whom 8165 are asthmatics.

RESULTS

We report associations between several DENND1B variants (P = 2.2 × 10(-7) for rs4915551) on chromosome 1q31 and BMI from a meta-analysis of GWAS data using 2691 asthmatic children (screening data). The top DENND1B single nucleotide polymorphisms(SNPs) were next evaluated in seven independent replication data sets comprising 2014 asthmatics, and rs4915551 was nominally replicated (P < 0.05) in two of the seven studies and of borderline significance in one (P = 0.059). However, strong evidence of effect heterogeneity was observed and overall, the association between rs4915551 and BMI was not significant in the total replication data set, P = 0.71. Using a random effects model, BMI was overall estimated to increase by 0.30 kg/m(2) (P = 0.01 for combined screening and replication data sets, N = 4705) per additional G allele of this DENND1BSNP. FTO was confirmed as an important gene for adult and childhood BMI regardless of asthma status.

CONCLUSIONS AND CLINICAL RELEVANCE

DENND1B was recently identified as an asthma susceptibility gene in a GWAS on children, and here, we find evidence that DENND1B variants may also be associated with BMI in asthmatic children. However, the association was overall not replicated in the independent data sets and the heterogeneous effect of DENND1B points to complex associations with the studied diseases that deserve further study.

Applications of Nonlinear Optical Thin Films

Many approaches to fabrication of nonlinear optical and electro-optical thin-film materials are currently under investigation including: epitaxial inorganic films; polycrystalline inorganic materials; organic nonlinear moieties poled in polymer hosts; and poled amorphous inorganic materials. For each of these approaches there are a variety of characteristics and constraints that impact the ultimate uses. These are discussed in the context of signal processing and transmission applications such as optical interconnects and integrated optics. Almost universally, integration with the Si materials and processing that dominates current computer technology, or with the III-V materials that dominate optoelectronics technology, are major factors in the attractiveness of a technology direction. A relatively recent development is the observation of a strong nonlinearity in fused silica, χ(2) ∼ 1 pm/V, poled by modest temperature and electric-field stress. Temperature-dependent dynamic and spectroscopic measurements suggest that mobile-ion species such as Na+, as well as non-bridging oxygen bond re-orientation under a strong field, play a role in the nonlinearity.

Dasatinib sensitizes KRAS mutant colorectal tumors to cetuximab

KRAS mutation is a predictive biomarker for resistance to cetuximab (Erbitux®) in metastatic colorectal cancer (mCRC). This study sought to determine if KRAS mutant CRC lines could be sensitized to cetuximab using dasatinib (BMS-354825, sprycel®) a potent, orally bioavailable inhibitor of several tyrosine kinases, including the Src Family Kinases. We analyzed 16 CRC lines for: 1) KRAS mutation status, 2) dependence on mutant KRAS signaling, 3) expression level of EGFR and SFKs. From these analyses, we selected three KRAS mutant (LS180, LoVo, and HCT116) cell lines, and two KRAS wild type cell lines (SW48 and CaCo2). In vitro, using Poly-D-Lysine/laminin plates, KRAS mutant cell lines were resistant to cetuximab whereas parental controls showed sensitivity to cetuximab. Treatment with cetuximab and dasatinib showed a greater anti-proliferative effect on KRAS mutant line as compared to either agent alone both in vitro and in vivo. To investigate potential mechanisms for this anti-proliferative response in the combinatorial therapy we performed Human Phospho-kinase Antibody Array analysis measuring the relative phosphorylation levels of phosphorylation of 39 intracellular proteins in untreated, cetuximab, dasatinib or the combinatorial treatment in LS180, LoVo and HCT116 cells. The results of this experiment showed a decrease in a broad spectrum of kinases centered on the β-catenin pathway, the classical MAPK pathway, AKT/mTOR pathway and the family of STAT transcription factors when compared to the untreated control or monotherapy treatments. Next we analyzed tumor growth with cetuximab, dasatinib or the combination in vivo. KRAS mutant xenografts showed resistance to cetuximab therapy, whereas KRAS wild type demonstrated an anti-tumor response when treated with cetuximab. KRAS mutant tumors exhibited minimal response to dasatinib monotherapy. However, as in vitro, KRAS mutant lines exhibited a response to the combination of cetuximab and dasatinib. Combinatorial treatment of KRAS mutant xenografts resulted in decreased cell proliferation as measured by Ki67 and higher rates of apoptosis as measured by TUNEL. The data presented herein indicate that dasatinib can sensitize KRAS mutant CRC tumors to cetuximab and may do so by altering the activity of several key-signaling pathways. Further, these results suggest that signaling via the EGFR and SFKs may be necessary for cell proliferation and survival of KRAS mutant CRC tumors. This data strengthen the rationale for clinical trials in this genetic setting combining cetuximab and dasatinib.

Premorbid proneness to distress and episodic memory impairment in Alzheimer's disease

BACKGROUND

Chronic stress has been associated with impaired episodic memory, but the association of premorbidly experienced distress with memory function in Alzheimer's disease is unknown.

OBJECTIVE

To investigate the link between proneness to distress and Alzheimer's disease.

METHODS

Participants were 363 persons with clinically diagnosed Alzheimer's disease. At baseline, a knowledgeable informant rated each person's premorbid personality (that is, before dementia onset) along five dimensions, one of which was the tendency to experience psychological distress. Participants underwent structured clinical evaluations at baseline and then annually for up to four years. Each evaluation included 17 cognitive tests from which previously established measures of episodic memory, visuoconstruction, repetition, and naming were derived.

RESULTS

In a series of random effects models adjusted for age, sex, and education, premorbid distress proneness was associated with baseline impairment in episodic memory but not with impairment in other cognitive domains, or with change in any cognitive domain. No other trait was related to baseline function or rate of decline in any cognitive domain.

CONCLUSIONS

The results suggest that premorbid proneness to experience psychological distress is related to level of impairment in episodic memory in persons with Alzheimer's disease, but neither distress proneness nor other personality traits are related to disease progression.

Targeting acute ischemic stroke with a calcium-sensitive opener of maxi-K potassium channels

During ischemic stroke, neurons at risk are exposed to pathologically high levels of intracellular calcium (Ca++), initiating a fatal biochemical cascade. To protect these neurons, we have developed openers of large-conductance, Ca++-activated (maxi-K or BK) potassium channels, thereby augmenting an endogenous mechanism for regulating Ca++ entry and membrane potential. The novel fluoro-oxindoles BMS-204352 and racemic compound 1 are potent, effective and uniquely Ca++-sensitive openers of maxi-K channels. In rat models of permanent large-vessel stroke, BMS-204352 provided significant levels of cortical neuroprotection when administered two hours after the onset of occlusion, but had no effects on blood pressure or cerebral blood flow. This novel approach may restrict Ca++ entry in neurons at risk while having minimal side effects.

The microbiology of necrotizing soft tissue infections

OBJECTIVE

A large number of necrotizing soft tissue infections (NSTI) treated at a single institution over an 8-year period were analyzed with respect to microbial pathogens recovered, treatment administered, and outcome. Based on this analysis, optimal empiric antibiotic coverage is proposed.

METHODS

A retrospective chart review of all patients with documented NSTI was conducted. Microbiologic variables were tested for impact on outcome using Fisher's exact test and multivariate analysis by logistic regression.

RESULTS

Review of the charts of 198 patients with documented NSTI revealed 182 patients with sufficient microbiologic information for analysis. These 182 patients grew an average of 4.4 microbes from original wound cultures, although a single pathogen was responsible in 28 patients. Eighty-five patients had combined aerobic and anaerobic growth, the most common organisms being, in order, Bacteroides species, aerobic streptococci, staphylococci, enterococci, Escherichia coli, and other gram-negative rods. Clostridial growth was common but did not affect mortality unless associated with pure clostridial myonecrosis. Mortality was affected by the presence of bacteremia, delayed or inadequate surgery, and degree of organ system dysfunction on admission.

CONCLUSIONS

NSTI are frequently polymicrobial and initial antibiotic coverage with a broad-spectrum regimen is warranted. The initial regimen should include agents effective against aerobic gram-positive cocci, gram-negative rods, and a variety of anaerobes. The most common organisms not covered by initial therapy were enterococci. All wounds should be cultured at initial debridement, as changes in antibiotic coverage are frequent once isolates are recovered.

Hyperbaric oxygen therapy for trauma: crush injury, compartment syndrome, and other acute traumatic peripheral ischemias

In the future, the indications for HBO therapy in acute peripheral ischemic injuries will likely be based on objective criteria rather than, as at present, on clinical diagnoses alone. This chapter offers objective criteria for using HBO in crush injuries and compartment syndromes. The pathophysiology of ATPI are well defined. Hyperbaric oxygen mediates the effects of ATPI through four mechanisms: hyperoxygenation, vasoconstriction, reperfusion, and host factors. The cost benefits of using HBO will be substantial, since complications from ATPI are very expensive. As objective criteria replace the presently used subjective criteria, hyperbaric oxygen therapy will become an integral part of trauma management of these injuries.

Cervical necrotizing fasciitis of odontogenic origin: a case report and review of 12 cases

PURPOSE

This article reviews the demographics, presentation, cause, clinical findings, and treatment of 12 cases of cervical necrotizing fasciitis of odontogenic origin.

PATIENTS AND METHODS

A retrospective chart review of 12 cases treated between 1987 and 1997 was done.

RESULTS

Most cases resulted from an abscessed mandibular molar. The most common significant medical conditions in the patient's history were diabetes, hypertension, obesity, and substance abuse. All patients were treated surgically within 24 hours of admission. Hyperbaric oxygen (HBO) was used as adjunctive treatment in all cases. The average length of hospital stay was 31 days. All patients recovered.

CONCLUSION

Early surgical intervention and the use of HBO decreases morbidity and improves the clinical outcome.

The accuracy of diagnostic laparoscopy in trauma patients: a prospective, controlled study

BACKGROUND

Numerous studies advocate the use of diagnostic laparoscopy (DL) for abdominal trauma, but none have documented its ability to diagnose specific injuries. This study tests the hypothesis that DL can accurately identify all significant intra-abdominal injuries in trauma patients.

METHODS

Of trauma patients requiring laparotomy for presumed injuries, 47 underwent DL followed by laparotomy. Injuries noted at laparoscopy were compared with those found at laparotomy.

RESULTS

Of these, 14 patients had no significant injuries necessitating operative intervention noted at laparoscopy and celiotomy. The remaining 33 patients harbored 93 significant injuries at laparotomy, of which only 57.0% were found by DL. DL possessed poor sensitivity (<50%) for injuries to hollow viscera. Despite DL's poor performance in finding specific injuries, it possessed excellent sensitivity (96.2%), and specificity (100%) for determining the need for therapeutic celiotomy.

CONCLUSIONS

DL offers no clear advantage over diagnostic peritoneal lavage and computed tomography in blunt trauma. Its utility lies in assessment of the need for laparotomy in patients with penetrating wounds. Currently, DL cannot consistently identify all abdominal injuries, disqualifying it as a therapeutic tool in abdominal trauma.

Chronic carbon monoxide exposure: a clinical syndrome detected by neuropsychological tests

Chronic exposure to carbon monoxide produces a clinical syndrome that is often overlooked because of obscure symptomatology, a range of presentations, and lack of awareness of the problem. To help physicians recognize and treat the chronic carbon monoxide exposure syndrome, the authors present its objective symptomatology, an approach to diagnosis emphasizing neuropsychological tests, a treatment protocol, and theoretical considerations for the mechanism of hyperbaric oxygen's therapeutic action. For elucidation, eight patients treated in the hyperbaric chamber at a tertiary care facility are described. Diagnosis can be facilitated by recognizing the syndrome based on the patient's history, as well as physical and neuropsychological examinations, with emphasis on identifying potential sources of carbon monoxide exposure. The evaluation and treatment protocols presented, though still experimental, show promise for improving functional, cognitive, and psychiatric capacities.

Near extinction of a large, widely distributed fish

Are extinctions of marine vertebrates as rare and unlikely as current data indicate? Long-term research surveys on the continental shelf between the Grand Banks of Newfoundland and southern New England reveal that one of the largest skates in the northwest Atlantic, the barndoor skate (Raja laevis), is close to extinction. Forty-five years ago, research surveys on St. Pierre Bank (off southern Newfoundland) recorded barndoor skates in 10% of their tows; in the last 20 years, none has been caught, and this pattern of decline is similar throughout the range of the species.

Outpatient management of HIV-infected adults. The varied challenges for primary care

Care of persons infected with HIV presents many challenges to primary care physicians. In addition to keeping current on the rapidly advancing medical aspects of the disease, physicians also must be prepared to recognize the complex psychosocial issues that confront their patients. In this article, Dr Myers reviews essential aspects of primary care for HIV-infected adults.

Confirmation of the pulse oximetry gap in carbon monoxide poisoning

STUDY OBJECTIVES

To demonstrate the degree to which pulse oximetry overestimates actual oxyhemoglobin (O2Hb) saturation in patients with carbon monoxide (CO) poisoning. This phenomenon has been reported in fewer than 20 humans in the English medical literature.

METHODS

A retrospective chart review of 191 patients evaluated for CO poisoning at a regional hyperbaric center identified 124 patients 10 years of age and older who had had both arterial blood gas and pulse oximetry measurements and who had received either high-flow oxygen through a nonrebreather mask or 100% inspired oxygen through an endotracheal tube. Blood gas measurements, including direct spectrophotometric determination of O2Hb and carboxyhemoglobin (COHb) saturation values, were compared with finger-probe pulse oximetry readings.

RESULTS

Measured O2Hb saturation (mean +/- SD, 88.7 +/- 10.2%; range, 51.4% to 99.0%) decreased linearly and predictably with rising COHb levels (10.7 +/- 10.4%; range, .2% to 46.4%). Pulse oximetry saturation (99.2% +/- 1.3%; range, 92% to 100%) remained elevated across the range of COHb levels and failed to detect decreased O2Hb saturation. The pulse oximetry gap, defined as the difference between pulse oximetry saturation and actual O2Hb saturation (10.5% +/- 9.7%; range, 0% to 40.6%), approximated the COHb level.

CONCLUSION

There is a linear decline in O2Hb saturation as COHb saturation increases. This decline is not detected by pulse oximetry, which therefore overestimates O2Hb saturation in patients with increased COHb levels. The pulse oximetry gap increases with higher levels of COHb and approximates the COHb level. In patients with possible CO poisoning, pulse oximetry must be considered unreliable and interpreted with caution until the COHb level has been measured.

Necrotizing soft tissue infections. Risk factors for mortality and strategies for management

OBJECTIVE

The authors evaluate in a retrospective fashion the factors influencing outcome in a large group of patients presenting with necrotizing soft tissue infections, and, based on this analysis, propose a plan for optimal care of such patients.

SUMMARY BACKGROUND DATA

In many smaller series of patients with necrotizing soft tissue infections, similar analyses of risk factors for mortality have been performed, producing conflicting conclusions regarding optimal care. In particular, debate exists regarding the impact of concurrent physiologic derangements, type and extent of infection, and the role of hyperbaric oxygen in treatment.

METHODS

A retrospective chart review of 198 consecutive patients with documented necrotizing soft tissue infections, treated at a single institution during an 8-year period, was conducted. Using a model for logistic regression analysis, characteristics of each patient and his/her clinical course were tested for impact on outcome.

RESULTS

The mortality rate among the 198 patients was 25.3%. The most common sites of origin of infection were the perineum (Fournier's disease; 36% of cases) and the foot (in diabetics; 15.2%). By logistic regression analysis, risk factors for death included age, female gender, extent of infection, delay in first debridement, elevated serum creatinine level, elevated blood lactate level, and degree of organ system dysfunction at admission. Diabetes mellitus did not predispose patients to death, except in conjunction with renal dysfunction or peripheral vascular disease. Myonecrosis, noted in 41.4% of the patients who underwent surgery, did not influence mortality.

CONCLUSIONS

Necrotizing soft tissue infections represent a group of highly lethal infections best treated by early and repeated extensive debridement and broad-spectrum antibiotics. Hyperbaric oxygen appears to offer the advantage of early wound closure. Certain markers predict those individuals at increased risk for multiple-organ failure and death and therefore assist in deciding allocation of intensive care resources.

An augmented Clark model for stability of populations

A simple modification of a frequently employed age-structured model for population dynamics is presented. This augmented formulation allows the assessment of the impact of age-dependent harvest mortality on population stability. The characteristic frequencies of the predicted oscillations are discussed. The period of oscillation is almost independent of survival and the exact functional form of the recruitment function, and it is not equal to twice the mean age of mature animals, as suggested earlier. It is shown that increased survival before reproduction has a destabilizing influence for populations exhibiting an overcompensatory recruitment function.

Population Dynamics of Exploited Fish Stocks at Low Population Levels

Models of population dynamics in which per capita reproductive success declines at low population levels (variously known as depensation, the Allee effect, and inverse density-dependence) predict that populations can have multiple equilibria and may suddenly shift from one equilibrium to another. If such depensatory dynamics exist, reduced mortality may be insufficient to allow recovery of a population after abundance has been severely reduced by harvesting. Estimates of spawner abundance and number of surviving progeny for 128 fish stocks indicated only 3 stocks with significant depensation. Estimates of the statistical power of the tests strengthen the conclusion that depensatory dynamics are not apparent for fish populations at the levels studied.

A preliminary report on hyperbaric oxygen in the relief of migraine headache

Oxygen inhalation was early advocated as a treatment for migraine headache. It has been theorized that the efficacy of raising blood oxygen levels in vascular headache is mediated by vasoconstriction and metabolic effects. Hyperbaric oxygen can provide a much greater level of blood oxygenation than can provide a much greater level of blood oxygenation than normobaric oxygen, and in recent studies it has been used in the treatment of cluster headache. The purpose of this study was to compare the effects of hyperbaric oxygen and normobaric oxygen in migraine. Twenty migraineurs were divided randomly into two groups and studied in a hyperbaric chamber during a typical headache attack. Global headache severity was measured by a verbal descriptor scale before and after exposure to oxygen. One group received 100% oxygen at 1 atmosphere of pressure (normobaric) while the other received 100% oxygen at 2 atmospheres of pressure (hyperbaric). One of the 10 patients in the normobaric group achieved significant relief of headache symptoms, while 9 of 10 in the hyperbaric group found relief. Based on a chi-square test, this difference is significant at the P < .005 level. Those patients who did not find significant relief from normobaric oxygen were given hyperbaric oxygen as above. All nine found significant relief. The results suggest that hyperbaric (but not normobaric) oxygen may be useful in the abortive management of migraine headache. Possibilities for the mechanism of this effect, in addition to vasoconstriction, include an increase in the rate of energy-producing and neurotransmitter-related metabolic reactions in the brain which require molecular oxygen.

Regional hemodynamics in 1-day-delayed rodent island flaps

We have studied the recovery of microvascular function in ischemic epigastric skin flaps by characterizing the regional hemodynamics in the axial and random portions of double- and single-pedicle island skin flaps in the rat. Blood flows were measured with radiolabeled microspheres 1 day after bipedicle flaps were elevated and at 4 hr, 72 hr, and 1 week after ligation of one of the pedicles. These hemodynamic measurements were correlated with assessments of angiogenesis and skin necrosis performed by lectin histochemistry and histopathology. Twenty-four hours after the skin flap elevation, the mean blood flow was 0.26 ml.min-1.g-1. After the ligation of one pedicle, the blood flow in the axial portion of the skin flap was unchanged at 4 hr (0.22 ml.min-1.g-1), declined insignificantly at 72 hr (0.15 ml.min-1.g-1), and remained normal at 1 week. In the random portion of the skin flap very little collateral blood flow was present at 4 hr (0.06 ml.min-1.g-1) and 72 hr (0.09 ml.min-1.g-1). Blood flow in the random skin flap returned to normal by 1 week (0.27 ml.min-1.g-1). Reelevation of the skin flap at 1 week caused an insignificant decline (10%) in total blood flow to the skin flap. Skin necrosis was detected histologically at 72 hr only in the lateral portion of the random skin flap, where blood flow was less than 0.03 ml.min-1.g-1. Increased areas of lectin binding to vascular endothelium were seen in the subdermal layers of the skin flap by 1 week, presumably due to angiogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Toxityping rat brain calcium channels with omega-toxins from spider and cone snail venoms

Different types of voltage-sensitive Ca2+ channels in the brain can be defined by specific ligands: L-type Ca2+ channels are uniquely sensitive to dihydropyridines, and N-type Ca2+ channels are selectively blocked by the Conus peptide omega-CTX-GVIA. Cloning data have revealed additional calcium channel types in mammalian brain for which selective ligands would be desirable. We describe binding experiments involving three newer ligands that block dihydropyridine- and omega-CTX-GVIA-resistant Ca channels: omega-Aga-IIIA and omega-Aga-IVA from venom of the spider Agelenopsis aperta and omega-CTX-MVIIC from Conus magus. [125I]omega-Aga-IVA binds with high affinity (IC50 = approximately 50 nM) to receptors in rat brain which may correspond to P-like calcium channels. A second high-affinity site (IC50 = approximately 1 nM) is defined by [125I]omega-CTX-MVIIC, proposed here to be on an "O"-type calcium channel. [125I]omega-Aga-IIIA targets homologous binding sites present on multiple Ca channel types. The IIIA sites overlap with the binding sites for [125I]omega-CTX-GVIA and [125I]omega-CTX-MVIIC. The IIIA sites do not overlap with the site defined by omega-Aga-IVA. Thus toxin ligands may be highly specific for a particular Ca channel (i.e., GVIA for the N-type channel) or exhibit broader specificity (i.e., omega-Aga-IIIA, which appears to bind L-, N-, P-, and O-type Ca2+ channels).

Hyperbaric oxygen treatment for experimental cyclophosphamide-induced hemorrhagic cystitis

Acrolein is a toxic metabolite of cyclophosphamide that causes hemorrhagic cystitis in 2 to 40% of treated patients. Hyperbaric oxygen (HBO) is used to treat poorly healing wounds in conditions such as Fournier's gangrene and radiation-induced cystitis. The present study was designed to evaluate the effects of HBO on acute acrolein-induced hemorrhagic cystitis in a rat model. Rats were divided into 4 groups. Group I served as a control and received only HBO prior to sacrifice. Group II received acrolein only, while groups III and IV received acrolein as well as HBO therapy. Hyperbaric oxygen (100% oxygen, 2.8 atmospheres, 90 minutes) was delivered twice a day for 4 days, with group III receiving a fifth HBO treatment just before acrolein and group IV receiving the fifth HBO treatment just after acrolein. After therapy, the amount of urothelial injury was determined morphometrically. Group II untreated rat bladders had only 33% of the urothelium intact after acrolein injury, whereas groups III and IV rat bladders had 93% (p < 0.01) and 55% (p < 0.01) intact urothelium, respectively, after treatment with HBO. The timing of the HBO treatment appeared to be a critical factor, with less injury occurring if the fifth HBO treatment immediately preceded acrolein. These results suggest that HBO may be useful as prophylaxis and treatment of cyclophosphamide-induced hemorrhagic cystitis.

Hyperoxia and prolongation of aminoglycoside-induced postantibiotic effect in Pseudomonas aeruginosa: role of reactive oxygen species

Hyperoxia prolongs the postantibiotic effect (PAE) of the aminoglycoside tobramycin in Pseudomonas aeruginosa. We tested the hypothesis that the PAE is prolonged because hyperoxia increases free radical flux while tobramycin inhibits the induction of antioxidant defenses. Exposure of P. aeruginosa to hyperoxia (100% O2) for 1 h increased superoxide dismutase, catalase, and glutathione levels. In the presence of tobramycin (1x the MIC), the induction of antioxidant defenses by hyperoxia was nearly abrogated. Neither preexposure of P. aeruginosa to hyperoxia nor supplementation with the antioxidants copper(II) (diisopropylsalicylate)2 (superoxide dismutase-like), catalase, or dimethyl sulfoxide abolished prolongation of the PAE of tobramycin induced by hyperoxia.

Regulation of protein degradation in normal and transformed human bronchial epithelial cells in culture

Protein degradation rates are decreased in some transformed cells of mesenchymal origin. We have tested the generality of this phenomenon and evaluated the role of the lysosomes in this down-regulation. To this end we have compared the induction of lysosomal protein degradation among normal, transformed (BEAS-2B), and transformed tumorigenic (BZR, Calu-1) human bronchial epithelial cells in culture. Serum and/or nutrient deprivation, cell confluency, and Ca2+ were used to modulate lysosomal protein degradation. Protein degradation and synthesis were determined by the release or incorporation of [14C]valine in the cells. Autophagic degradation of cytoplasm by lysosomes was evaluated by ultrastructural morphometry. Basal protein degradation was lower (27%) in two of the transformed cell lines (BEAS-2B and BZR). Incorporation of [14C]valine label was raised approximately 4-fold in the transformed cells. Nutrient deprivation stimulated protein degradation equally (2-fold) in transformed and normal cells. Postconfluency increased (1.5-fold) basal protein degradation in Calu-1 cells and a marked enhancement (4-fold) of degradation occurred during nutrient deprivation. Culture of normal human bronchial epithelial cells in high Ca2+ caused phenotypic changes and increased (30%) the degradation of protein induced by nutrient deprivation. In Calu-1, high Ca2+ caused only phenotypic changes. The volume density (Vd) of autophagic vacuoles and dense bodies in the transformed cells was lower under basal conditions but increased markedly during nutrient deprivation. A marked accumulation of lysosomes also occurred in transformed cells during postconfluency. We conclude that cell transformation lowers basal protein degradation in some human epithelial cells. Lysosomal proteolysis of transformed cells is not down-regulated and can be markedly enhanced during nutritional deprivation by the autophagic degradation pathway.

Oxygen tensions and infections: modulation of microbial growth, activity of antimicrobial agents, and immunologic responses

Oxygen tensions play an important role in the outcome of infections. Oxygen is cidal or static for microorganisms that lack defenses against oxidants. Hyperoxia and hyperbaric oxygen exert antimicrobial effects by increasing the intracellular flux of reactive oxygen species. In bacteria, such species cause DNA strand breaks, degradation of RNA, inhibition of amino acid biosynthesis, and inactivation of membrane transport proteins. Oxygen tensions also affect the activity of antimicrobial agents. In general, hyperoxia potentiates while anaerobiosis decreases the activity of many antimicrobial drugs. With regard to host defenses, hyperoxia elevates oxygen tensions in infected tissues to levels that facilitate oxygen-dependent killing by leukocytes. Prolonged hyperoxia inhibits DNA synthesis in lymphocytes and impairs chemotactic activity, adherence, phagocytic capacity, and generation of the oxidative burst in polymorphonuclear leukocytes and macrophages.

Non-obstructive colonic dilatation in the trauma patient: an analysis of six patients

Non-obstructive colonic dilatation was diagnosed in six of 13,641 patients admitted to a Level I trauma centre over a 70-month period (incidence, less than 0.05 per cent). Four were older than 60 years, and five required long-term support on a ventilator. Successful treatment depends on expeditious decompression of the dilated colon. Fibreoptic colonoscopy is the recommended method.

Hyperbaric oxygenation decreases blood flows in normal and septic rats

The purpose of the study reported here was to characterize the effects of acute exposure to 100% oxygen at a pressure of 202.6 kPa on hemodynamics and organ blood flow in antibiotic-controlled bacterial sepsis. An abscess containing known numbers and strains of live Escherichia coli and Bacteroides fragilis was established in the peritoneal cavity of rats. Sham-operated rats were used as controls. Cardiac output, fractional blood flow distribution, and blood flow were calculated from data obtained using the radiolabeled microsphere technique. Myocardial and renal blood flows were decreased (20-30%) in both experimental groups during hyperbaric oxygen (HBO) exposure. Renal blood flow remained diminished for at least 20 min after rats were removed from the hyperbaric chamber. Adrenal gland perfusion in abscess-containing rats was reduced both during and after HBO exposure. Skeletal muscle blood flow (quadriceps and gastrocnemius muscles) was reduced by one third in both experimental groups 20 min after acute exposure to HBO. The results of this study indicate that changes in organ perfusion induced by HBO are similar in abscess-containing and normal rats. We conclude that HBO does not alter the regulation of blood flow in antibiotic-controlled sepsis.

Large second-order nonlinearity in poled fused silica

A large second-order nonlinearity [chi((2)) 1 pm/V 0.2 chi((2)) (22) for LiNbO(3)] is induced in the near-surface ( 4 microm) region of commercial fused-silica optical flats by a temperature (250-325 degrees C) and electric-field (E ~ 5 x 10(4) V/cm) poling process. Once formed, the nonlinearity, which is roughly 10(3)-10(4) times larger than that found in fiber second-harmonic experiments, is extremely stable at room temperature and laboratory ambient. The nonlinearity can be cycled by repeated depoling (temperature only) and repoling (temperature and electric field) processes without history effects. Possible mechanisms, including nonlinear moieties and electric-field-induced second-order nonlinearities, are discussed.

alpha-Conotoxins, small peptide probes of nicotinic acetylcholine receptors

alpha-Conotoxins, a family of small peptides from the venoms of the Conus marine moluscs, are selective, snake alpha-neurotoxin-competitive antagonists of the nicotinic acetylcholine receptor. A new alpha-conotoxin, SIA, has been purified, sequenced, and synthesized. Cross-linking with bivalent reagents and photoaffinity labeling of the acetylcholine receptor with alpha-conotoxin yield covalent adducts. Surprisingly, cross-linking to other subunits is considerably more efficient than to the alpha subunit. The relative efficiency of photoactivatable cross-linking to different subunits of the receptor is a function of placement of the photoactivatable group on the toxin. Since the structures of alpha-conotoxins can be solved by 2D NMR [see Pardi et al. (1989) Biochemistry 28, 5494-5508; Kobayashi et al. (1989) Biochemistry 28, 4853-4860], this family of toxins should provide a set of new ligands for probing the acetylcholine receptor with considerable precision.

A neuropsychological screening battery for emergency assessment of carbon-monoxide-poisoned patients

The Carbon Monoxide Neuropsychological Screening Battery (CONSB) was developed to improve the neurological assessment of CO-poisoned patients in an emergency setting. Traditional assessment methods (clinical examination and carboxyhemoglobin [CoHb] levels) readily can identify unconscious, severely involved patients; however, many CO-intoxicated patients with cerebral impairment who also require aggressive hyperbaric oxygen therapy are assessed inadequately by such methods. Administration of the CONSB to 66 CO-poisoned patients and 66 volunteer controls revealed significant differences in performance between the two groups. It was concluded that the CONSB enhanced the accuracy of the evaluation of cerebrally impaired CO-poisoned patients. Failure to assess the cerebral functioning of patients exposed to CO and to identify those who require aggressive oxygen therapy could have neurological sequelae.

Hyperoxia prolongs the aminoglycoside-induced postantibiotic effect in Pseudomonas aeruginosa

The objective of this study was to determine whether hyperoxia enhances aminoglycoside activity against Pseudomonas aeruginosa. The existence of tobramycin-oxygen synergy was determined by using the in vitro postantibiotic effect (PAE). P. aeruginosa strains were incubated for 1 h in medium containing tobramycin at four times the MIC in the following gas mixtures: normoxia (21% O2), hyperoxia (100% O2, 101.3 kPa), or hyperbaric oxygen (100% O2, 274.5 kPa). Tobramycin was removed after 1 h and bacteria were incubated under normoxic conditions; growth rates were measured for 5 h. Exposure of three P. aeruginosa strains to hyperoxia prolonged the PAE of tobramycin approximately twofold compared with the PAE after exposure to normoxia (P less than 0.05). Exposure of P. aeruginosa ATCC 27853 to tobramycin and hyperbaric oxygen prolonged the time required for bacteria to increase 1 log10 CFU/ml compared with the time after exposure for this increase to occur in tobramycin-treated, normoxic or hyperoxic groups (P less than 0.02). Pulse-chase labeling of bacteria with L-[35S]methionine, immediately after removal of tobramycin, showed that protein synthesis rates were decreased compared with those in controls (P = 0.0001). Moreover, in tobramycin-treated groups, hyperoxia and hyperbaric oxygen induced 2- and 16-fold decreases, respectively, in protein synthesis rates compared with normoxia; these results did not achieve statistical significance. In the absence of tobramycin, hyperoxia increased bacterial growth (134%; P less than 0.01) and protein synthesis (24%; not significant) compared with normoxia. Hyperbaric oxygen, however, delayed the growth recovery of bacteria (P less than 0.05). We conclude that hyperoxia enhances the bacteriostatic effects of tobramycin in a synergistic manner.+

Pathophysiology of sea nettle (Chrysaora quinquecirrha), envenomation in a rat model and the effects of hyperbaric oxygen and verapamil treatment

The effect of lethal sea nettle envenomation on the morphology and blood flow in various rat organs was characterized and the influence of two antidotes (hyperbaric oxygen and verapamil) was compared. Either antidote slightly prolonged survival, but the protective effects were not statistically significant. The venom caused no histologic alterations in brain, heart, or lungs but induced hepatic and renal necrosis. Hepatocytes in mid-zonal regions and renal tubular epithelium were the cell types predominantly affected. Hyperbaric oxygen and verapamil did not decrease the hepatic injury. The venom did not influence central hemodynamics until preterminally and it diminished blood flow to brain, but not to liver or kidney. Hyperbaric oxygenation protected against venom-induced decreases in blood flow to the brain. These results add toxic hepatic and renal necrosis and cerebral ischemia to the pathophysiology of envenomation in this model.

Bite wound infections of the lower extremity

Animal bite wounds of the lower extremity are considered high-risk wounds for infection, especially in the medically compromised individual. Management should be aggressive. Copious irrigation and debridement of the wound clearly proves to be of greater value in the prevention of infection than the indiscriminate use of so-called "prophylactic" antibiotic agents. Frankly infected wounds must also be managed aggressively, incorporating the use of antibiotics to eradicate the infection. Empiric use of an agent containing clavulanic acid or sulbactam is suggested until results are obtained from the bacterial culture and sensitivity. Tetanus prophylaxis should be considered for every bite wound, whereas rabies prophylaxis is warranted in selected cases.

The effects of hyperbaric oxygen on free flaps in rats

The effects of hyperbaric oxygen on survival were investigated in free flaps and island flaps. Skin flaps transplanted following 18, 21, and 24 hours of preservation at 24 degrees C demonstrated survival rates of 20%, 10%, and 0%, respectively. Treatment with hyperbaric 100% oxygen improved the survival rates to 66%, 67%, and 40%. A preservation time of 21 to 24 hours at room temperature appears to be the threshold of irreversible ischemic damage. In acute island flaps, flap survival was improved significantly from 35% to 53% and 64% of the random flap area by preoperative or postoperative treatment, respectively. Prolonged preoperative and postoperative treatment improved survival to 66%.

Hyperoxia and the antimicrobial susceptibility of Escherichia coli and Pseudomonas aeruginosa

We have tested the ability of hyperoxia (98% O2-2% CO2 at 2.8 atmospheres absolute [ca. 284.6 kPa]) to enhance killing of Escherichia coli (serotype O18 or ATCC 25922) by nitrofurantoin, sulfamethoxazole, trimethoprim, gentamicin, and tobramycin. We have also looked for interactions between hyperoxia and the aminoglycosides against Pseudomonas aeruginosa ATCC 27853. Hyperoxia significantly enhanced bacteriostatic activity of nitrofurantoin and trimethoprim as measured by MIC testing. The possibility exists that these effects might be due to the method required to tests MICs under hyperoxic conditions rather than to the effect of hyperoxia itself. In addition, hyperoxia enhanced killing of bacteria by trimethoprim as measured by MBC testing. Hyperoxia decreased numbers of E. coli by 1.3 log10 and P. aeruginosa by 2.7 log10 in cation-supplemented Mueller-Hinton broth medium. The bacteriostatic effects of hyperoxia did not affect MICs of gentamicin or tobramycin. The lack of interaction between hyperoxia and gentamicin or tobramycin was confirmed by determining the number of viable bacteria remaining after 24 h of exposure to hyperoxia by using a pour plate method. We conclude that hyperoxia potentiates the antimicrobial activity of the reduction-oxidation-cycling antibiotic tested (nitrofurantoin) and of one of the antimetabolites tested (trimethoprim). Hyperoxia does not enhance the bactericidal effects of gentamicin and tobramycin, which require oxidative metabolism for transport into bacterial cells.

Hyperbaric oxygen for methylene chloride poisoning: report on two cases

Two cases of methylene chloride poisoning treated with hyperbaric oxygen are presented and discussed. Both patients were found unconscious in an occupational setting. Carboxyhemoglobin level determination and neuropsychological evaluation confirmed a diagnosis of carbon monoxide intoxication subsequent to methylene chloride exposure. The serial carboxyhemoglobin levels and Carbon Monoxide Neuropsychological Screening Battery scores obtained from these patients suggest that toxicity from methylene chloride-derived carbon monoxide responds well to treatment with hyperbaric oxygen.

Volume monitor for mechanical ventilation in the hyperbaric chamber

Treatment of critically ill patients requiring ventilatory support and hemodynamic monitoring in the hyperbaric medicine department is a frequent occurrence. We provide mechanical ventilation principally with the Penlon Oxford ventilator; however, its simple design lacks volume, rate, and disconnect monitors. Therefore, we combined the ventilator with the Ohmeda volume monitor, a pulmonary function monitor for adult and pediatric use that gives reliable, accurate measurements of tidal volume, rate, and minute ventilation. The Ohmeda unit is easily adaptable to the Penlon ventilator, and may also be used to monitor respiratory function in the spontaneously breathing patient. To our knowledge, this is the only battery-driven monitor on the market that provides rate, volume, apnea, and minute ventilation within the same unit. It should be used as an adjunct to the Penlon Oxford ventilator in the hyperbaric chamber.

Splanchnic blood flows in a rat model of antibiotic-controlled intra-abdominal abscess during normoxia and hyperoxia

We have characterized splanchnic blood flows in a rat model of antibiotic-controlled, intra-abdominal abscess (ACIA) in normoxic and hyperoxic environments. Abscesses (1.5 ml average volume) were established by implanting a fecal-agar pellet containing known numbers and strains of live Escherichia coli and Bacteroides fragilis into the peritoneal cavity of rats via a midline incision. Sham-operated rats (SR) served as controls. Cannulas (PE-50) were placed into the left ventricle of both SR and ACIA rats for injection of tracer microspheres (MS) and into the tail artery for a reference withdrawal site. Blood flow measurements were made in conscious unrestrained rats before, during, and after hyperoxic exposure by using MS labelled with either 51Cr or 85Sr or 141Ce. No change in cardiac output (CO), heart rate (HR), or mean arterial pressure (MAP) was seen between ACIA and SR groups. The administration of hyperoxia diminished the fractional distribution of CO to the liver (portal), stomach, cecum, colon, and pancreas in both groups. The percent CO to the liver (arterial), small intestine, and spleen did not change in either group. The blood flow to all splanchnic organs, except liver (arterial), was diminished during hyperoxia in both groups and recovered after hyperoxia. In conclusion, central hemodynamics and splanchnic blood flows are not altered by the presence of a large intra-abdominal abscess controlled by antibiotics. Splanchnic blood flows are diminished by hyperoxia.

Stimulation of autophagic protein degradation by nutrient deprivation in a differentiated murine teratocarcinoma (F9 12-1a) cell line

We have evaluated the participation of the lysosomal degradation pathway in the increased protein degradation induced by nutrient deprivation in transformed cells. To this end we used a clone, 12-1a, derived from a murine teratocarcinoma cell line (F9 12-1) induced to differentiate by culture in retinoic acid. Culture of 12-1a cells, prelabeled with L-[U-14C]valine, in nutrient-deprived medium (Hanks' balanced salt solution plus Ca++) stimulated the protein degradation rate from 0.9% hr to 1.4% hr. Morphometric analysis demonstrated that during nutrient deprivation, the volume density of lysosomes increased 3-fold; the numerical density of lysosomes increased 2-fold; the mean area of lysosomal profiles increased 1.7-fold (1.40 microns2 vs 0.81 microns2). The volume density and numerical density of the dense bodies tended to decrease by approximately 60% without any change in the mean volume of the dense bodies. These data indicate that nutrient deprivation increases protein degradation in transformed cells by increasing the sequestration of cytoplasm into the lysosomes. The decrease in the number of dense bodies indicates that these structures (also termed residual bodies) are functional in transformed cells and merge with the lysosomes to provide more degradative enzymes to enhance proteolysis. This study provides direct evidence that serum factors and nutrients play a crucial role in modulation of lysosomal protein degradation in transformed cells.

Are arterial blood gases of value in treatment decisions for carbon monoxide poisoning?

Traditionally, the carboxyhemoglobin (HbCO) level has been used to estimate the severity of carbon monoxide (CO) poisoning. Through extensive clinical experience, we have found this to be an inaccurate correlation; thus, other variables such as pHa or psychometric abnormalities have been assessed to determine severity from CO poisoning. In a 5-yr experience with 247 patients, on admission 114 had an arterial blood gas and HbCO determinations, and 88 also had psychometric testing. The data were evaluated to determine any relationship between pH and HbCO level; a weak correlation (r approximately equal to -0.3) was discovered. A comparison of psychometric testing with HbCO level showed a much stronger statistical relationship. The definition of HbCO poisoning severity may be better determined by psychometric testing than by the HbCO level because psychometric testing measures actual neurologic disability. The weak correlation between both psychometric testing and the HbCO level with pHa reinforces the clinical impression that patients with acidosis, alkalosis, or normal blood gases could have equally severe neurologic symptomatology at HbCO levels ranging from 1% to 62%.