Fungal-derived cues promote ocular autoimmunity through a Dectin-2/Card9-mediated mechanism.

Uveitis (intraocular inflammation) is a leading cause of loss of vision. Although its aetiology is largely speculative, it is thought to arise from complex genetic-environmental interactions that break immune tolerance to generate eye-specific autoreactive T cells. Experimental autoimmune uveitis (EAU), induced by immunization with the ocular antigen, interphotoreceptor retinoid binding protein (IRBP), in combination with mycobacteria-containing complete Freund's adjuvant (CFA), has many clinical and histopathological features of human posterior uveitis. Studies in EAU have focused on defining pathogenic CD4+ T cell effector responses, such as those of T helper type 17 (Th17) cells, but the innate receptor pathways precipitating development of autoreactive, eye-specific T cells remain poorly defined. In this study, we found that fungal-derived antigens possess autoimmune uveitis-promoting function akin to CFA in conventional EAU. The capacity of commensal fungi such as Candida albicans or Saccharomyces cerevisae to promote IRBP-triggered EAU was mediated by Card9. Because Card9 is an essential signalling molecule of a subgroup of C-type lectin receptors (CLRs) important in host defence, we evaluated further the proximal Card9-activating CLRs. Using single receptor-deficient mice we identified Dectin-2, but not Mincle or Dectin-1, as a predominant mediator of fungal-promoted uveitis. Conversely, Dectin-2 activation by α-mannan reproduced the uveitic phenotype of EAU sufficiently, in a process mediated by the Card9-coupled signalling axis and interleukin (IL)-17 production. Taken together, this report relates the potential of the Dectin-2/Card9-coupled pathway in ocular autoimmunity. Not only does it contribute to understanding of how innate immune receptors orchestrate T cell-mediated autoimmunity, it also reveals a previously unappreciated ability of fungal-derived signals to promote autoimmunity.

Terminal ileum duplication: an unusual case of small bowel obstruction.

Duplications of the alimentary tract are uncommon congenital anomalies that usually present during infancy and early childhood. The case of an adolescent presenting with small bowel obstruction secondary to a duplication cyst is presented and the challenges in the management described.

Interphenylene 7-oxabicyclo[2.2.1]heptane thromboxane A2 antagonists. Semicarbazone omega-chains.

A series of chiral interphenylene 7-oxabicyclo[2.2.1]heptane semicarbazones 19-26 were prepared and evaluated for their in vitro thromboxane (TxA2) antagonistic activity and in vivo duration of action. The potency of 19-26 was found to highly dependent on the substitution pattern of the interphenylene ring and decreased in the order ortho greater than meta much greater than para. SQ 35,091 (25), [1S-(1 alpha,2 alpha,3 alpha,4 alpha)]-2-[[3-[[[(phenylamino) carbonyl]hydrazono]methyl]-7-oxabicyclo[2.2.1]hept-2-yl]methyl] benzenepropanoic acid, was identified as a potent and long-acting TxA2 antagonist. In human platelet rich plasma SQ 35,091 inhibited arachidonic acid (800 microM) and U-46,619 (10 microM) induced aggregation with I50 values of 3 and 12 nM, respectively. In contrast, no inhibition of ADP (20 microM) induced aggregation was observed at greater than 1000 microM. Receptor binding studies with [3H]-SQ 29,548 showed SQ 35,091 was a competitive antagonist with a Kd value of 1.0 +/- 0.1 nM in human platelet membranes. In vivo SQ 35,091 (0.2 mg/kg po) showed extended protection (T50 = 16 h) from U-46,619 (2 mg/kg iv) induced death in mice. These compounds have for the first time demonstrated that a metabolically stable interphenylene alpha-sidechain can be introduced into a prostanoid-like series of TxA2 antagonists with the maintainance of potent antagonistic activity.

Interphenylene 7-oxabicyclo[2.2.1]heptane oxazoles. Highly potent, selective, and long-acting thromboxane A2 receptor antagonists.

A series of interphenylene 7-oxabicyclo[2.2.1]heptane oxazoles (2) were prepared and evaluated for their thromboxane (TxA2) antagonistic activity in vitro and duration of action in vivo. Examination of the carboxyl side chain indicated that the interphenylene ring substitution pattern and, to a lesser extent, chain length were important factors in determining TxA2 antagonistic potency. For the carboxyl side chain, ortho substitution, a single methylene spacer between the interphenylene and oxabicycloheptane rings, and a propionic acid side-chain length were determined to be optimal. With respect to the oxazole side chain a wide range of amide substituents with diverse structures and lipophilicities were compatible with potent antagonistic activity. Finally, an acidic functional group on the alpha-chain and a hydrogen bond acceptor on the 4-position of the oxazole ring were critical for potent activity. From the analogs prepared 42 (BMS-180,291: [(+)-1S-(1 alpha, 2 alpha, 3 alpha, 4 alpha)-2-[[3-[4-[(n- pentylamino)carbonyl]-2-oxazolyl]-7-oxabicyclo[2.2.1]hept-2- yl]methyl]benzenepropanoic acid) was found to be a potent, selective, and orally-active TxA2 antagonist with a long duration of action and has been selected as a candidate for clinical development. In human platelet-rich plasma, 42 inhibited arachidonic acid (800 microM) and U-46,-619 (10 microM) induced aggregation with I50 values of 7 and 21 nM, respectively. Radioligand binding studies of 42 with [3H]-SQ 29,548 showed a Kd value of 4.0 +/- 1.0 nM in human platelet membranes. Both in vitro and in vivo studies indicated 42 was devoid of direct agonistic activity. In vivo 42 (0.2 mg/kg, po) showed extended protection (T50 = 14.4 h) from U-46,619 (2 mg/kg, iv) induced death in mice, and a single oral dose of 42 (3 mg/kg) abolished U46,619-induced platelet aggregation ex vivo in African green monkeys for > 24 h.

Clinical pharmacokinetics of the inhalational anaesthetics.

At present, the most widely used inhalational anaesthetics are the halogenated, inflammable vapours halothane, enflurane, isoflurane and the gas nitrous oxide. The anaesthetic effect of these agents is related to their tension or partial pressure in the brain, represented at equilibrium by the alveolar concentration. The minimum alveolar concentration for a specific agent is remarkably constant between individuals. The uptake and distribution of inhalational anaesthetics depends on inhaled concentration, pulmonary ventilation, solubility in blood, cardiac output and tissue uptake. Inhalational anaesthetics are mainly eliminated by pulmonary exhalation, but significant amounts of halothane are removed by hepatic metabolism. Inhalational agents currently in use have acceptable pharmacokinetic characteristics, and clinical acceptance depends on their potential for adverse effects. Induction of anaesthesia with halothane is rapid and relatively pleasant and it is the agent of choice for paediatric anaesthesia. Between 20 and 50% is metabolised, and the parent drug is a potent inhibitor of drug metabolism. Post-operatively enzyme induction may follow. The major disadvantages of halothane are myocardial depression, propensity to evoke cardiac arrhythmias and the rare but serious halothane hepatitis. Induction and recovery from enflurane anaesthesia is rapid. Metabolism accounts for 5 to 9% of the elimination. The metabolic product inorganic fluoride may in rare cases cause renal toxicity. Enflurane is a weak inhibitor of drug metabolism at anaesthetic concentrations. Enflurane depresses circulation more than halothane by reducing both myocardial contractility and systemic vascular resistance, but cardiac rhythm is stable. Enflurane anaesthesia may, unlike the other agents, induce epileptic activity. Enflurane is widely used as replacement for halothane in adults. Despite its low blood-gas solubility, the airway irritability of isoflurane precludes a faster induction of anaesthesia than with halothane. Isoflurane is almost resistant to biodegradation. Myocardial contractility is maintained during isoflurane anaesthesia and cardiac rhythm is stable except for the occurrence of tachycardia in some patients. Isoflurane is the inhalational agent of choice for neurosurgical operations. Sevoflurane is an experimental ether vapour: induction and recovery is fast and pleasant. It is metabolised to the same extent as enflurane and subnephrotoxic concentrations of inorganic fluoride may result. Sevoflurane has fewer respiratory and cardiovascular depressant effects than halothane and may be a future alternative for paediatric anaesthesia.(ABSTRACT TRUNCATED AT 400 WORDS)

Bioactivation and covalent binding of halothane to liver macromolecules.

In this manuscript we report our attempts to determine if 14C-halothane or its metabolites interact with DNA. Three bioactivation systems were used: in vitro microsomal incubations, isolated hepatocytes, and in vivo administration. Even though we used optimal conditions for bioactivation, no significant covalent binding of 14C to DNA was observed. Slight 14C activity above background (6 dpm/0.1 mg DNA) was observed in the microsomal incubations but is considered insignificant because it was not reduced when NADPH was omitted from the incubations. We are able to demonstrate covalent binding to nuclear lipids and proteins when rats were pretreated with phenobarbital and maintained in a hypoxic environment (14% O2). Similarly, these conditions markedly increased covalent binding of 14C from 14C-halothane to microsomal proteins and lipids. Isolated rat hepatocytes proved to be a viable system for studying the bioactivation of halothane. In this system it was also possible to demonstrate increased binding under N2 and/or phenobarbital pretreatment.

Halothane hepatotoxicity and the reduced derivative, 1,1,1-trifluoro-2-chloroethane.

Halothane (1,1,1-trifluoro-2-bromo-2-chloroethane) is a safe, clinically useful inhalation anesthetic. Rare, unpredictable cases of liver necrosis have been reported following its use. Although the mechanism of this reaction in man is unknown the most plausible is biotransformation to reactive intermediates compounds. The oxidative metabolism of halothane appears to be benign. There is early evidence that reductive (nonoxygen dependent) may be harmful. Since the bromine atom of halothane appears to possess weak bond energy, the reduced, debrominated derivative of halothane, 1,1,1-trifluoro-2-chloroethane, was synthesized and tested for hepatotoxicity in the rat. The derivative is unstable and thus was prepared anaerobically and trapped in propylene glycol solvent. Injection of small amounts of this compound into the portal vein of rats produces extensive liver necrosis. It is postulated that biotransformation of halothane via a reductive pathway could produce this reactive intermediate metabolite.

Improved results in the management of surgical candidates with lung cancer.

BACKGROUND: Perioperative mortality and morbidity after lung resection for carcinoma are generally reported to be 3% to 6% and 15% to 30%, respectively, and higher in the elderly and those with limited cardiopulmonary reserve. METHODS: To minimize this risk and extend the surgical option to more high-risk patients, we adopted a protocol in 1991 that included preoperative digitalis, subcutaneous heparin and venoocclusive stockings, aggressive perioperative pulmonary toilet, and video-directed limited resections for many patients with limited pulmonary reserve. In October 1996, we reviewed our results with 173 consecutive patients (median age, 60 years; range, 17 to 89 years) undergoing operation for suspected lung carcinoma. Forty-one patients were 70 years old or older, and 70 patients were considered high risk on the basis of advanced age (> or = 70 years), poor cardiac or pulmonary reserve, or serious medical comorbidity. Procedures included pneumonectomy (n = 31), lobectomy (n = 83), bilobectomy (n = 12), and limited resection (n = 45). Two patients had unresectable disease. RESULTS: Hospital mortality was 1.6% (3/173) and morbidity was experienced by 15% (26/173). Among the high-risk subgroup mortality was 4.2% (3/70) and morbidity was 20% (14/70; p < 0.03). For the older patients these values were 4.8% (2/41) and 17.9% (7/41), respectively. CONCLUSIONS: Morbidity and mortality from lung resections may be minimized with the perioperative management strategy outlined above. This would allow more high-risk patients to benefit from surgical resection, and do so with an acceptably low risk.

Fast pitch softball injuries.

The popularity of fast pitch softball in the US and throughout the world is well documented. Along with this popularity, there has been a concomitant increase in the number of injuries. Nearly 52% of cases qualify as major disabling injuries requiring 3 weeks or more of treatment and 2% require surgery. Interestingly, 75% of injuries occur during away games and approximately 31% of traumas occur during nonpositional and conditioning drills. Injuries range from contusions and tendinitis to ligamentous disorders and fractures. Although head and neck traumas account for 4 to 12% of cases, upper extremity traumas account for 23 to 47% of all injuries and up to 19% of cases involve the knee. Approximately 34 to 42% of injuries occur when the athlete collides with another individual or object. Other factors involved include the quality of playing surface, athlete's age and experience level, and the excessive physical demands associated with the sport. Nearly 24% of injuries involve base running and are due to poor judgement, sliding technique, current stationary base design, unorthodox joint and extremity position during ground impact and catching of cleats. The increasing prevalence of overtraining syndrome among athletes has been attributed to an unclear definition of an optimal training zone, poor communication between player and coach, and the limited ability of bone and connective tissue to quickly respond to match the demands of the sport. This has led routinely to arm, shoulder and lumbar instability, chronic nonsteroidal anti-inflammatory drug (NSAID) use and time loss injuries in 45% of pitching staff during a single season. Specific attention to a safer playing environment, coaching and player education, and sport-specific training and conditioning would reduce the risk, rate and severity of fast pitch traumas. Padding of walls, backstops, rails and dugout areas, as well as minimising use of indoor facilities, is suggested to decrease the number of collision injuries. Coaches should be cognisant of overtraining, vary day-to-day training routines to decrease repetitive musculoskeletal stress, focus on motor skills with equal emphasis on speed and efficiency of movement, and use drills that reinforce sport-specific, decision making processes to minimise mental mistakes. Conditioning programs that emphasise a combination of power, acceleration, flexibility, technical skill, functional capacity and injury prevention are recommended. Due to the limited body of knowledge presently available on this sport, a greater focus on injury surveillance would provide a clearer picture of injury causation and effective management procedures, leading toward safer participation and successful player development.

Acridine structure correlated with mutagenic activity in Salmonella.

The structural basis for direct mutagenicity of acridines was studied by testing 50 different analogs in the Ames Salmonella tester strains without the addition of mammalian activating enzymes. These experiments showed that the single most effective substituent for frameshift mutagenesis in strain TA1537 is an amino group at the "9" position, while an amino group at either the "3" or "1" position is less effective. Other substitutions at the "9" position demonstrate decreased frameshifting activity compared to 9-aminoacridine. Furthermore, all substituents in combination with the amino group of 9-aminoacridine also decrease frameshifting activity, except for the addition of another amino group at the "1" position or a methyl at the ring nitrogen. Nitro substituents at the "1" and "3" positions enhance 9-aminoacridine toxocity. All nitro substituents decrease typical acridine-frameshift mutagenesis for strain TA1537, but they induce mutagenic activity either in the other type of frameshift strain, TA1538, or in the base-pair substitution strain TA1535. These studies have provided important structure-function relationships for acridine mutagenicity and toxicity in Salmonella. Consequently, this biological system has provided a sensitive means for determining the structural requirements for mutagenic mechanisms.

Mutagenesis by photoaffinity labeling using selected azidofluorenes.

Several 2-azidofluorenes have been synthesized for use as photoaffinity labels inside bacteria. In the dark they were not mutagenic for any Salmonella typhimurium tested. When photolyzed inside the bacteria, all were mutagenic for strain TA1538 to varying degrees, and were considerably less mutagenic in the corresponding repair positive TA1978. None were mutagenic for strain TA1535 or TA1537, although most compounds were toxic for those strains when photolyzed.

Ethidium bromide enhancement of frameshift mutagenesis caused by photoactivatable ethidium analogs.

Ethidium azide analogs (3-amino-8-azido-ethidium monoazide and ethidium diazide) have been developed as photosensitive probes in order to analyze directly the reversible in vivo interactions of ethidium bromide. Our preliminary observations [11], relating the mutagenic potential of the monoazide analog of ethidium, have been extended and refined, using the highly purified ethidium azide analogs [5]. A number of physical-chemical studies indicate that the monoazide analog interaction with nucleic acids, prior to photolysis, resembles remarkably the interaction of the parent ethidium (unpublished). It was anticipated, therefore, that competition by ethidium for the ethidium monoazide mutagenic sites in Salmonella TA1538 would be observed when these drugs were used in combination. Previous results in fact showed a decreased production of frameshift mutants when ethidium bromide was added to the ethidium monoazide in the Ames assay [1]. However, more extensive investigations, reported here, have shown that this apparent competition was the result of neglecting the toxic effects of ethidium monoazide and its enhanced toxocity in the presence of ethidium bromide. Conversely, an enhancement of the azide mutagenesis and toxicity for both the mono- and diazide analogs was seen when ethidium bromide was used in combination with these analogs.

Azido analogs of acridine: photoaffinity probes for frameshift mutagenesis in Salmonella typhimurium.

In order to identify a photoaffinity probe for 9-aminoacridine frameshift mutagenesis, 20 azido analogs of acridine were synthesized and tested in Ames' Salmonella tester strains, TA1535, TA1537, TA1538 and their corresponding excision-repair-coefficient strains TA1975, TA1977 and TA1978, to determine their mutagenicity and toxicity relative to 9-aminoacridine. The substituent-mutagenicity patterns observed for these compounds agree very well with those obtained previously for non-azidoacridines. The results presented here show that the 2-azido-analog of 9-aminoacridine demonstrates biological activity similar to 9-aminoacridine prior to photolytic activation. With light activation, however, the 9-amino-2-azido derivative becomes more effective at producing frameshift mutations characteristic of 9-aminoacridine. Furthermore, this photolytic enhancement of mutagenesis appears to be due to the repairable lesion suggesting that covalent attachment of the drug occurs.

Hepatotoxicity and inhalation anesthetics: views in the era of isoflurane.

The halogenated inhalation anesthetics continue to be an important group of drugs in current anesthesia practice. The purpose of this article is to discuss current concepts of the mechanisms of halothane-induced hepatotoxicity and to attempt to answer the question: Do all halogenated inhalation anesthetics share halothane's propensity to hepatotoxicity?

Sevoflurane degradation product concentrations with soda lime during prolonged anesthesia.

STUDY OBJECTIVES: To evaluate the decomposition of sevoflurane in soda lime during prolonged sevoflurane anesthesia in humans. To evaluate for evidence of renal or hepatotoxicity as a result of exposure to these sevoflurane degradation compounds. DESIGN: Prospective evaluation in healthy volunteers. SETTING: Clinical research unit and postanesthesia care unit of a university hospital. PATIENTS: Six healthy male volunteers. INTERVENTIONS: Subjects were anesthetized with sevoflurane 1 to 1.2 minimum alveolar concentration for greater than 9 hours with a semiclosed circuit anesthetic technique (5-liter total flow) with fresh soda lime as the absorbent. MEASUREMENTS AND MAIN RESULTS: Laboratory tests of renal and hepatic function were performed before anesthesia and 1 and 5 days after anesthesia. During sevoflurane anesthesia, inhalation and exhalation circuit limb gas samples were obtained for degradation compound analysis. Only one degradation product, fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether (compound A), was detected. Inhalation concentration was maximal (7.6 +/- 1.0 ppm) at 2 hours and did not increase further after this time point. There were no differences in preanesthesia and postanesthesia tests of hepatic and renal function. CONCLUSIONS: Levels of the degradation compound (compound A) produced in semiclosed circuit sevoflurane anesthesia with soda lime are well below potential toxic levels and thus appear safe. When sevoflurane is administered under these conditions for prolonged anesthesia, concentrations of compound A do not continue to increase throughout anesthesia.

Searching for the Magic Johnson effect: AIDS, adolescents, and celebrity disclosure.

The objectives of this study were to measure changes in AIDS-related attitudes and behaviors in adolescents in the 13 months following Magic Johnson's disclosure that he was HIV positive, and to test whether gender, race, age, sexual experience, and pre-existing HIV-avoidant behaviors would emerge as significant dependent variables. Adolescent clinic attendees (N = 181) ages 12-19 in four cities completed a questionnaire assessing change in AIDS-related attitudes and behaviors since Johnson's announcement. Respondents were divided into low-risk and at-risk groups. Sixty percent of respondents reported that Magic Johnson's announcement had increased their awareness of AIDS, 65.4% reported increased self-efficacy in a sexual situation, 37.2% reported that they had changed their perceived AIDS risk, 37.8% described increased resistance to peer pressure for sexual intercourse. The low-risk group was more likely to report increased self-efficacy and resistance to peer pressure but no change in perceived risk or increased AIDS awareness. Significant relationships were found between gender and increased AIDS awareness, gender and increased resistance to peer pressure to engage in sexual intercourse, race and increased AIDS awareness, and more lifetime sex partners and increased self-efficacy.

Understanding mechanical ventilation: indications for and initiation of therapy.

The growing complexity of mechanical ventilators and the proliferation of new ventilator modes may confuse and intimidate clinicians who on occasion must manage a mechanical ventilator. The fundamental indications for and types of mechanical ventilation are reviewed, and guidelines for basic ventilator settings are provided. By understanding and applying these essentials, the clinician can provide effective mechanical ventilation to most patients who require it. A subsequent article published in this journal will review the related topics of patient monitoring during mechanical ventilation, complications of mechanical ventilation, and weaning from mechanical ventilation.

Understanding mechanical ventilation: patient monitoring, complications, and weaning.

Mechanical ventilation can provide life saving support to critically ill patients with respiratory failure. The implementation of appropriate monitoring techniques and an awareness of potential complications can increase the safety of mechanical ventilation. Several efficacious weaning methods can be utilized and none is clearly superior to the others. The improper use of any weaning technique can result in respiratory muscle fatigue delaying extubation. Determining patient suitability for extubation is an inexact science. The physical examination during a spontaneous breathing trial and the use of the rapid shallow breathing index can assist the clinician in the difficult decision as to the timing of extubation.

Fiberoptic bronchoscopic placement of self-expandable metallic airway stents for the treatment of tracheobronchial obstruction and fistulas.

Tracheobronchial stent use has been reported in the medical literature for more than 40 years. Silicone stents are the most widely used stents in therapy for varying tracheobronchial lesions at most centers. However, newer designs and modifications of stents are now available with delivery systems that have been designed to facilitate using fiberoptic bronchoscopy. We describe our initial experience placing 13 self-expandable metallic Wallstent stents, including the covered design, in a total of seven patients via a fiberoptic bronchoscope. All patients had benign or malignant obstructing lesions and one patient had an associated malignant tracheoesophageal fistula. The procedure was technically easy and was well tolerated. Following stenting there was a visible increase in airway diameter and a marked improvement in symptoms for all patients. Median survival after stent placement is currently 10 months.