Heat shock protein 90α increases superoxide generation from neuronal nitric oxide synthases

Neuronal nitric oxide synthase (nNOS) generates superoxide, particularly at sub-optimal l-arginine (l-Arg) substrate concentrations. Heat shock protein 90 (Hsp90) was reported to inhibit superoxide generation from nNOS protein. However, commercially available Hsp90 product from bovine brain tissues with unspecified Hsp90α and Hsp90β contents and an undefined Hsp90 protein oligomeric state was utilized. These two Hsp90s can have opposite effect on superoxide production by NOS. Importantly, emerging evidence indicates that nNOS splice variants are involved in different biological functions by functioning distinctly in redox signaling. In the present work, purified recombinant human Hsp90α, in its native dimeric state, was used in electron paramagnetic resonance (EPR) spin trapping experiments to study the effects of Hsp90α on superoxide generation from nNOS splice variants nNOSμ and nNOSα. Human Hsp90α was found to significantly increase superoxide generation from nNOSμ and nNOSα proteins under l-Arg-depleted conditions and Hsp90α influenced superoxide production by nNOSμ and nNOSα at varying degrees. Imidazole suppressed the spin adduct signal, indicating that superoxide was produced at the heme site of nNOS in the presence of Hsp90α, whereas l-Arg repletion diminished superoxide production by the nNOS-Hsp90α. Moreover, NADPH consumption rate values exhibited a similar trend/difference as a function of Hsp90α and l-Arg. Together, these EPR spin trapping and NADPH oxidation kinetics results demonstrated noticeable Hsp90α-induced increases in superoxide production by nNOS and a distinguishable effect of Hsp90α on nNOSμ and nNOSα proteins.

In vivo electron paramagnetic resonance oximetry and applications in the brain

Molecular oxygen (O₂) is essential to brain function and mechanisms necessary to regulate variations in delivery or utilization of O₂ are crucial to support normal brain homeostasis, physiology and energy metabolism. Any imbalance in cerebral tissue partial pressure of O₂ (pO₂) levels may lead to pathophysiological complications including increased reactive O₂ species generation leading to oxidative stress when tissue O₂ level is too high or too low. Accordingly, the need for oximetry methods, which assess cerebral pO₂in vivo and in real time, is imperative to understand the role of O₂ in various metabolic and disease states, including the effects of treatment and therapy options. In this review, we provide a brief overview of the common in vivo oximetry methodologies for measuring cerebral pO₂. We discuss the advantages and limitations of oximetry methodologies to measure cerebral pO₂in vivo followed by a more in-depth review of electron paramagnetic resonance oximetry spectroscopy and imaging using several examples of current electron paramagnetic resonance oximetry applications in the brain.

Ozone Inhalation Impairs Coronary Artery Dilation via Intracellular Oxidative Stress: Evidence for Serum-Borne Factors as Drivers of Systemic Toxicity

Ambient ozone (O3) levels are associated with cardiovascular morbidity and mortality, but the underlying pathophysiological mechanisms driving extrapulmonary toxicity remain unclear. This study examined the coronary vascular bed of rats in terms of constrictive and dilatory responses to known agonists following a single O3 inhalation exposure. In addition, serum from exposed rats was used in ex vivo preparations to examine whether bioactivity and toxic effects of inhaled O3 could be conveyed to extrapulmonary systems via the circulation. We found that 24 h following inhalation of 1 ppm O3, isolated coronary vessels exhibited greater basal tone and constricted to a greater degree to serotonin stimulation. Vasodilation to acetylcholine (ACh) was markedly diminished in coronary arteries from O3-exposed rats, compared with filtered air-exposed controls. Dilation to ACh was restored by combined superoxide dismutase and catalase treatment, and also by NADPH oxidase inhibition. When dilute (10%) serum from exposed rats was perfused into the lumen of coronary arteries from unexposed, naïve rats, the O3-induced reduction in vasodilatory response to ACh was partially recapitulated. Furthermore, following O3 inhalation, serum exhibited a nitric oxide scavenging capacity, which may partially explain blunted ACh-mediated vasodilatory responses. Thus, bioactivity from inhalation exposures may be due to compositional changes of the circulation. These studies shed light on possible mechanisms of action that may explain O3-associated cardiac morbidity and mortality in humans.

Mechanisms of NFATc3 activation by increased superoxide and reduced hydrogen peroxide in pulmonary arterial smooth muscle

We recently demonstrated increased superoxide (O2(·-)) and decreased H2O2 levels in pulmonary arteries of chronic hypoxia-exposed wild-type and normoxic superoxide dismutase 1 (SOD1) knockout mice. We also showed that this reciprocal change in O2(·-) and H2O2 is associated with elevated activity of nuclear factor of activated T cells isoform c3 (NFATc3) in pulmonary arterial smooth muscle cells (PASMC). This suggests that an imbalance in reactive oxygen species levels is required for NFATc3 activation. However, how such imbalance activates NFATc3 is unknown. This study evaluated the importance of O2(·-) and H2O2 in the regulation of NFATc3 activity. We tested the hypothesis that an increase in O2(·-) enhances actin cytoskeleton dynamics and a decrease in H2O2 enhances intracellular Ca(2+) concentration, contributing to NFATc3 nuclear import and activation in PASMC. We demonstrate that, in PASMC, endothelin-1 increases O2(·-) while decreasing H2O2 production through the decrease in SOD1 activity without affecting SOD protein levels. We further demonstrate that O2(·-) promotes, while H2O2 inhibits, NFATc3 activation in PASMC. Additionally, increased O2(·-)-to-H2O2 ratio activates NFATc3, even in the absence of a Gq protein-coupled receptor agonist. Furthermore, O2(·-)-dependent actin polymerization and low intracellular H2O2 concentration-dependent increases in intracellular Ca(2+) concentration contribute to NFATc3 activation. Together, these studies define important and novel regulatory mechanisms of NFATc3 activation in PASMC by reactive oxygen species.

Digital multimedia instruction enhances teaching oral and maxillofacial suturing

OBJECTIVE

To develop digital multimedia instruction on intraoral suturing.

METHODS

A DVD was developed to describe instruments, materials, and techniques. Two groups of dental students were asked to close an incision in a simulated model. One used written materials only and another used additional DVD. The performance was evaluated using 10 grading criteria.

RESULT

Students who used the DVD performed better than students who did not.

CONCLUSION

This DVD could be used widely in teaching dental students.

The relationship between immunodominance, DM editing, and the kinetic stability of MHC class II:peptide complexes

Immunodominance refers to the restricted antigen specificity of T cells detected in the immune response after immunization with complex antigens. Despite the presence of many potential peptide epitopes within these immunogens, the elicited T-cell response apparently focuses on a very limited number of peptides. Over the last two decades, a number of distinct explanations have been put forth to explain this very restricted specificity of T cells, many of which suggest that endosomal antigen processing restricts the array of peptides available to recruit CD4 T cells. In this review, we present evidence from our laboratory that suggest that immunodominance in CD4 T-cell responses is primarily due to an intrinsic property of the peptide:class II complexes. The intrinsic kinetic stability of peptide:class II complexes controls DM editing within the antigen-presenting cells and thus the initial epitope density on priming dendritic cells. Additionally, we hypothesize that peptides that possess high kinetic stability interactions with class II molecules display persistence at the cell surface over time and will more efficiently promote T-cell signaling and differentiation than competing, lower-stability peptides contained within the antigen. We discuss this model in the context of the existing data in the field of immunodominance.

The kinetic stability of MHC class II:peptide complexes is a key parameter that dictates immunodominance

T cell priming to exogenous antigens reflects regulated antigen processing in dendritic cells, subsequent homing to lymph nodes, sustained interactions between T cells and antigen-bearing dendritic cells, and, ultimately, selective T cell activation and differentiation. In this study, we test the hypothesis that an intrinsic property of the class II:peptide complex is a key determinant that dictates the specificity of an emerging CD4 T cell response. We found that immunodominant peptides possess extremely long half-lives with class II molecules (t(1/2) > 150 hr), whereas cryptic peptides displayed half-lives of less than 10 hr. Furthermore, and most importantly, by using a peptide shuttle vector and four independent antigens, we demonstrate a direct, causative relationship between the half-life of peptide epitopes and their immunogenicity in vivo. Taken collectively, our results suggest the half-life of class II:peptide complexes is the primary parameter that dictates the ultimate hierarchy of the elicited T cell response.

Hemicorporectomy

In hemicorporectomy, or translumbar amputation, the bony pelvis, pelvic contents, lower extremities, and external genitalia are removed following disarticulation of the lumbar spine and transection of the spinal cord. Malignancies of the pelvic organs, skin, or musculoskeletal structures, usually locally advanced, may be indications for hemicorporectomy. The absence of systemic metastasis must be demonstrated before considering hemicorporectomy. Sacral decubitus ulcers and other complications of paraplegia represent the most frequent benign indications. Hemicorporectomy is a complex, multistep procedure with significant physiologic and psychologic implications. Postoperative morbidity and mortality rates are high, partly because of the complexity of the procedure itself and partly due to the underlying disease. Detailed planning, from preoperative evaluation to rehabilitation, is the key to a successful outcome. The procedure may be carried out in one stage or in multiple stages, depending on the clinical circumstances. Multidisciplinary collaboration of many health care professionals should be part of the planning process and must be carefully coordinated. Postoperative management requires particular attention to fluid replacement, temperature control, and pulmonary care. Posthospitalization rehabilitation includes the design and construction of a bucket prosthesis. Long-term management issues involve hypertension, weight gain, temperature control, stoma management, and skin care.

Anesthesia for office-based oral and maxillofacial surgery

This article is divided into two sections, each encompassing the various aspects of anesthesia used for dental procedures ranging from single tooth extraction to more complex reconstruction and tumor eradication. The various types of anesthesia used for each of these kinds of dental surgery are explored, and the effectiveness and cost efficiency of office-based anesthesia procedures are discussed.

Late follow-up and functional outcome after traumatic reproductive tract injuries in women

The aim of this study was to assess female reproductive tract injuries and late effects on sexual and reproductive function. This was a review of women presenting to a Level I trauma center with reproductive tract injuries over 12 years. Thirty-one women (average age, 30 years) were divided into coital (19) and noncoital (12) injury groups. One-third of coital trauma presented late, one-fourth was abuse related, and seven women presented in shock. All had vaginal lacerations, and 15 required repair. Follow-up in 6 of 19 (32%) women averaged 4.5 years. Noncoital injuries resulted primarily from vehicular trauma, and two-thirds had associated abdominal injuries. Interventions included: vaginal laceration irrigation/repair (4), salpingectomy (2), ovariectomy (2), repair uterine perforation (1), and emergency cesarean section (2). The average Injury Severity Score was 25, with two deaths. Follow-up in 6 of 10 (60%) survivors averaged 6.1 years. The combined group has had seven subsequent pregnancies, and two women have minor dyspareunia after pelvic fracture. Women with coital injuries may develop shock, requiring rapid resuscitation and operative repair. Noncoital injuries are often associated with multiple severe injuries and require operative intervention. Late sequelae are minimal in both groups, and even severe injuries do not preclude normal pregnancy and sexual function.

Relationship of tonsil size on an airway blockage maneuver in children during sedation

A previous report suggested that airway compromise without self-correction may occur in pediatric dental patients sedated with chloral hydrate (CH) and nitrous oxide (N2O) and may be interpreted as "deep" sedation. The purpose of this institutionally approved study was to determine 1) the association between the size of the tonsils and 2) the degree of expired carbon dioxide (CO2) and oxygen saturation (SaO2) changes to simulated airway obstruction using the Moore head-tilt maneuver for 30 sec or less. Thirty healthy children (ASA I), aged 22-40 months, were evaluated for tonsil size and sedated with CH (50 mg/kg) and hydroxyzine (2 mg/kg) and supplemented with N2O. Pulse oximetry and capnography were used to monitor the child. During the restorative phase when the patient appeared asleep, the head was rolled forward with the chin touching the chest for a period of 30 sec. Changes in SaO2 and CO2 waveform were observed during this period. The results indicated that seven children who had enlarged tonsils had blocked airways (as determined by capnography) lasting approximately 15 sec. The remaining children did not have enlarged tonsils and continued to exchange air appropriately. O2 levels did not change during this period. The results suggest that the likelihood of airway blockage increases with enlarged tonsils. In children without airway blockage, ventilation occurs unimpeded, and attempts to readjust the head may not occur. The association between airway blockage and patient responsiveness is discussed in relation to sedation levels.

Correlation of human bladder tumor histoculture proliferation and sensitivity to mitomycin C with tumor pathobiology

This study examined the in vitro proliferation and mitomycin C (MMC) sensitivity of patient bladder tumors as a function of the tumor pathobiology. Surgical specimens of transitional cell carcinoma of the bladder were maintained as histocultures on collagen gels. The thymidine labeling index (LI) was determined by autoradiography and the labeling for proliferating cell nuclear antigen (PCNA) by immunohistochemistry. There was a linear correlation between the thymidine LI and the PCNA LI, but the PCNA LI were quantitatively lower than the thymidine LI. The mean thymidine LI were 30.9, 32.4 and 51.5% for the grade I, II and III tumors, 33.6 and 56.3% for the superficial (Tis, Ta and T1) and invasive (T2-T4) tumors, and 28.9 and 50.9% for the diploid and aneuploid tumors. Analysis of variance indicates that these differences were statistically significant. These data indicate that the proliferation of tumor histocultures paralleled the tumor aggressiveness in vivo. The tumor sensitivity to MMC, measured by the inhibition of the thymidine LI of tumor cells, was studied in 31 tumors. At a 2 hour exposure, as is currently used in intravesical therapy, the MMC concentrations required for 50% inhibition of thymidine LI (IC50) showed a 120-fold intertumor variation (0.102 to 12.4 micrograms./ml.). The sensitivity to MMC inversely correlated with tumor aggressiveness. The IC50 increased with tumor LI (p < 0.05). The mean IC50 were 2.61 and 5.79 micrograms./ml. for superficial and invasive tumors (p < 0.05), 1.06, 3.05 and 4.49 micrograms./ml. for grade I, II and III tumors (p < 0.05), and 2.53 and 4.31 micrograms./ml. for diploid and aneuploid tumors (p = 0.14). These data indicate a large difference in sensitivity of human bladder tumors to MMC, with greater sensitivity for well-differentiated superficial tumors and lesser sensitivity for undifferentiated, invasive tumors.

Evaluation of a clinical recovery score after general anesthesia

A clinical recovery score (CRS) assessing recovery after general anesthesia was compared with the Digit-Symbol Substitution Test (DSST), Trieger Test (TT), a patient-completed visual analogue scale for alertness (VAS), and an independent observer's evaluation of recovery. The CRS included ratings of the following parameters: activity, respiration, circulation, consciousness, ambulation, color, and nausea and vomiting. Forty patients requiring the removal of three or four third molars participated in the study. All patients received the same general anesthetic technique. Each patient was evaluated by the five methods preoperatively, on admission to the recovery room, and at 15-min intervals until discharge. The four recovery tests (CRS, DSST, TT, VAS) were evaluated using chi 2 analysis to determine if there was any overall difference among the tests using the observer's determination of home readiness as the standard for discharge. The CRS was significantly more in agreement with the observer's determination than were the paper and pencil tests. The recovery tests were also evaluated with regard to instances of early dismissal or prolonged retention of the patient, again using the observer's determination as the "gold standard." The CRS was the only recovery test devoid of early dismissals. We conclude that the CRS provides a valid, simple measure of recovery that can be readily used in offices providing outpatient anesthesia and in studies measuring clinical recovery from anesthesia or sedation.

Comparison of the efficacy of esmolol and alfentanil to attenuate the hemodynamic responses to emergence and extubation

STUDY OBJECTIVE

To define the ability of esmolol and alfentanil to control the hemodynamic changes associated with extubation and emergence.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

General surgery operating rooms at a university hospital.

PATIENTS

Forty-two ASA physical status I and II patients without history of cardiac or pulmonary disease undergoing surgery not involving the cranium or thorax.

INTERVENTIONS

Patients were given either a bolus dose of normal saline followed by an infusion of normal saline, a bolus dose of alfentanil 5 micrograms/kg followed by an infusion of normal saline, or a bolus dose of esmolol 500 micrograms/kg followed by an infusion of esmolol 300 micrograms/kg/min.

MEASUREMENTS AND MAIN RESULTS

Emergency and extubation resulted in significant increases in heart rate (HR) and blood pressure (BP) in the placebo group. Alfentanil controlled the responses to emergence but prolonged the time to extubation (p < 0.05). Esmolol significantly controlled the responses to emergence and extubation (p < 0.05).

CONCLUSIONS

Emergence and extubation after inhalation general anesthesia result in significant increases in BP and HR in healthy patients. An esmolol bolus dose and subsequent infusion significantly attenuated these responses. A small bolus dose of alfentanil minimized the responses to emergence but prolonged the time to extubation and was no longer protective at that point.

Comparative trial of succinylcholine vs low dose atracurium-lidocaine combination for intubation in short outpatient procedures

Despite its many disadvantages, succinylcholine is the most commonly used drug for intubation of patients for short out-patient procedure. This double blind trial compared a low dose atracurium/lidocaine combination to succinylcholine for intubation in 40 ASA1 adult patients. Low dose atracurium/lidocaine provided clinical intubating conditions at two minutes and cardiovascular stability equivalent to succinylcholine with significantly less myalgia. Spontaneous respiration was slower after low dose atracurium/lidocaine relative to succinylcholine. Low dose atracurium/lidocaine may provide an acceptable alternative to succinylcholine for intubation in short outpatient procedures.

The effectiveness of flurazepam as night sedation prior to the removal of third molars

Anxiety prior to dental treatment is a well-recognized problem. Although oral sedation has been recommended the night before appointments to reduce this anxiety, there are no well-controlled studies to support this claim. The present double-blind cross-over study investigated the effect of 30 mg of flurazepam taken the night before the removal of impacted third molars. Preoperative anxiety, visuomotor performance and sleep patterns were investigated in 20 adult patients with similarly impacted third molars. While preoperative flurazepam led to a statistically significant improvement in sleep patterns, there was no reduction in pre-operative anxiety on the morning of surgery. In addition, the flurazepam-treated group demonstrated significantly impaired visuo-motor performance 60 min after intravenous sedation compared to this group where intravenous sedation was used only preceded by placebo. Patients had a significant preference for flurazepam over placebo as a night-time sedative.

Verapamil increases the toxicity of local anesthetics

The calcium channel blocker verapamil has, in addition to its other properties, been shown to be a local anesthetic. Its concurrent use in a patient undergoing regional anesthesia may, therefore, increase the potential risk for local anesthetic toxicity. To evaluate this possibility, the effect of verapamil on the median lethal dose (LD50) of lidocaine and bupivacaine in mice was determined. Immediate pretreatment with verapamil increased the mortality of mice given the LD50 dose of lidocaine to 74%, and in mice given the LD50 doses of bupivacaine, to 82%. In animals pretreated with verapamil and calcium chloride, the mortality associated with the administration of LD50 doses of lidocaine and bupivacaine decreased to 43% and 48%, respectively, thus returning the mortality rate back to the LD50 of the local anesthetics when administered alone. It seems that the combined administration of local anesthetic and verapamil results in a significant drug interaction: the resulting blockade of sodium and calcium channels apparently impairs membrane function to a greater degree than with either drug alone. Additional investigation is warranted, and caution should be exercised in giving verapamil to patients during regional anesthesia. Should an adverse drug interaction ensue, the administration of calcium may be beneficial.

A visual analogue scale in the assessment of dental anxiety

The purpose of this study is to determine the validity of the visual analogue scale (VAS) in the assessment of changing levels of dental anxiety, through correlation with the dental anxiety scale (DAS) and the state portion (A-state) of the statetrait anxiety inventory (STAI). Forty-five adult patients attending an oral surgery clinic for a routine dental extraction participated. Before any treatment, each patient completed the DAS, the STAI, and a 100mm VAS. The order of administration was randomly determined. Following completion of the dental extraction under local anesthesia and just before discharge, the patients were once more asked to complete the DAS, the A-State, and a VAS which were again randomly ordered. All three measures demonstrate a significant reduction in mean anxiety scores from presurgery to postsurgery. There are significant correlations among the three measures both pre- and postsurgery. The VAS appears to correlate well with both the DAS and the A-State under changing levels of anxiety.

Sulfur influences on rumen microorganisms in vitro and in sheep and calves

When continuously cultured ruminal microbes were given orchardgrass hay and sufficient sulfuric acid or hydrochloric acid to maintain a pH of 5.5, fermentation and numbers of protozoa were reduced compared with cultures whose pH was controlled with phosphoric acid. Likewise, when sulfur-deficient, purified diets were supplied to cultures, less methane (mmol X liter-1 X d-1), 3.2 vs 32.6, was produced and fewer cellulolytic bacteria (log10/ml), 5.8 vs 7.2 were present than when cultures were given the same diet supplemented with .3% elemental sulfur. The rumen of sheep fed the .04% sulfur diet had reduced digesta weights (1.69 vs 3.2 kg) compared with sheep fed the diet with .34% sulfur at the same intake. There also was reduced methanogenesis 12.3 vs 25.8 mmol X liter-1 X d-1) and reduced numbers of cellulolytic bacteria (7.4 vs 8.4 log10/ml) in sulfur-deficient sheep in comparison to sulfur-supplemented sheep. In growing calves, the same types of bacteria predominated in the rumen, but more facultative anaerobic bacteria were isolated from calves fed .04% sulfur than from calves fed diets with .34 to 1.72% sulfur. None of the dietary levels of sulfur appeared toxic. Regardless of treatment, volatile fatty acids were more predominant than lactic acid as end-products of fermentation of ruminal microbes in fermenters, sheep and calves. The greater methanogenesis and the greater cellulolytic bacterial numbers of sulfur-supplemented sheep compared with sulfur-deficient in vitro cultures, is interpreted to be the result of recycling of sulfur to the rumen in sheep where it is efficiently scavengered by ruminal bacteria.

Sodium-dependent hypertension produced by chronic central angiotensin II infusion

Experiments were performed to characterize the hypertension produced by chronic intracerebroventricular (ICV) infusion of angiotensin II (ANG II) in conscious rats. Infusion of ANG II into a lateral cerebral ventricle for 5 days (1 or 6 micrograms/h) produced dose-dependent increases in mean arterial pressure associated with increased water intake. No consistent changes in heart rate, urinary electrolyte excretion, or water balance were observed. Similarly, no alterations in plasma sodium and potassium concentration, plasma osmolality, or plasma ANG II levels were seen during ICV ANG II infusion. Controlling fluid intake at 40 ml/day did not alter the development of hypertension in this model. Hypertension was found to be sodium dependent, with high sodium intake augmenting the increase in arterial pressure in response to chronic ICV ANG II. Although plasma aldosterone concentrations were increased in some situations during ICV ANG II infusion, adrenalectomy failed to alter the course of hypertension. This study demonstrates that chronic selective stimulation of brain ANG II receptors by means of continuous ICV infusion of ANG II produces sodium-sensitive increases in arterial pressure associated with, but not dependent on, increased fluid intake. This form of hypertension cannot be attributed to sodium and water retention, elevations in plasma aldosterone, or leak of significant amounts of ANG II from cerebrospinal fluid into the peripheral circulation.