Epidural test dose and intravascular injection in obstetrics: sensitivity, specificity, and lowest effective dose.

The authors studied the sensitivity and specificity of several epidural test doses as markers of intravascular injection in laboring patients in a prospective double-blind, randomized study. Fifty-nine parturients were assigned randomly to receive an intravenous injection of either normal saline solution (3 mL, NS group) or 1.5% lidocaine with epinephrine 1:200,000 (1 mL, EPI-5 group; 2 mL, EPI-10 group; or 3 mL, EPI-15 group). The EPI-5 and EPI-10 doses were diluted to 3 mL volume with normal saline solution. All injections were given during uterine diastole. Maternal heart rate was monitored with a pulse oximeter. An observer who was unaware of the study treatment recorded the baseline and the peak maternal heart rate within the first minute after the injection and questioned the patient about tinnitus, dizziness, metallic taste, and palpitations. He then recorded his opinion as to whether the patient had received the saline or the test solution. Analysis of the maternal heart rate showed an average increase (baseline-to-peak criterion) of 8 +/- 10 beats/min (mean +/- SD) in the NS group. In the other groups, the increase was 21 +/- 8 (EPI-5 group), 31.5 +/- 13 (EPI-10 group), and 29 +/- 9 beats/min (EPI-15 group). A baseline-to-peak criterion of greater than 10 beats/min identified all intravascular injections in the EPI-15 (by design) and EPI-10 groups (15 of 15 and 14 of 14, respectively) with a sensitivity of 100%. Specificity was 73% (11 of 15 true negatives).(ABSTRACT TRUNCATED AT 250 WORDS)     

Bilateral pneumothoraces secondary to an isolated midline zone 1 cervical stab injury

Penetrating neck trauma, though rare, carries a high morbidity and mortality risk if not recognized promptly, due to the presence of vital neurovascular and airway elements within a closed compartment. We describe the unique presentation of a high zone 1 anterior midline cervical stab injury with bilateral large pneumothoraces and extensive pneumomediastinum. Understanding the respiratory mechanics and a high clinical suspicion will help to recognize such complications of tracheobronchial injuries and their timely management is key to salvage of these patients.     

Effect of S-methylisothiourea,an inducible nitric oxide synthase inhibitor,in joint pain and pathology in surgically induced model of osteoarthritis

The aim of the present study was to evaluate in vivo modulatory effect of S-methylisothiourea (SMT), a preferential inhibitor of inducible nitric oxide synthase (iNOS) on pain and pathology in the surgical model of osteoarthritis (OA) in rats. The OA was produced by the anterior cruciate ligament transection (ACLT) and medial meniscectomy (MMx) of right knee. SMT was administered 1 day prior to the production of OA and continued up to day 42 postoperation. Mechanical hyperalgesia, thermal hyperalgesia, tail flick latency after repeated flexion and extension of OA knee and knee diameter of right knee were determined at weekly intervals. Serum levels of IL-1β, TNF-α and nitrite concentration were determined at the end of the experiment. Glycosaminoglycan (GAG) content, collagen content and histopathological evaluation of articular cartilage were also determined at the end of the experiment. SMT reduced mechanical hyperalgesia and the serum levels of IL-1β, TNF-α and nitrite. Further, SMT reduced the loss of GAG from articular cartilage. Microscopically, SMT reduced the severity of the cartilage lesion. The results indicate the effectiveness of SMT in attenuating the pain and pathology of experimental OA phase by reducing the production of nitric oxide and interleukin-1β and tumor necrosis factor-α, which are known to play a major role in the pathophysiology of OA.     

Elderly patients recover more rapidly from desflurane than from isoflurane anesthesia.

STUDY OBJECTIVE: To compare the hemodynamic, emergence, and recovery characteristics of desflurane-nitrous oxide (N2O) anesthesia with those of isoflurane-N2O anesthesia in elderly patients. DESIGN: Randomized study. SETTING: Main operating room of a major U.S. teaching hospital. PATIENTS: Thirty-four ASA physical status II and III patients aged 65 or older undergoing surgical procedures of greater than 1 hour duration. INTERVENTIONS: Group 1 (17 patients) received desflurane in 60% N2O for their surgical procedure. Group 2 (17 patients) received isoflurane in 60% N2O. Thiamylal 2 mg/kg administered intravenously (IV) induced anesthesia, and succinylcholine 1.5 mg/kg i.v. facilitated intubation. Muscle relaxation was maintained with vecuronium. Titration of the anesthetics maintained hemodynamics to within 20% of the patients' preinduction values. MEASUREMENTS AND MAIN RESULTS: Measurement of hemodynamics occurred every 2 minutes prior to skin incision and every 5 minutes thereafter. The times for discontinuation of inhaled anesthetics to eye opening, hand grip on command, and recall of name and date of birth were measured in a standardized fashion for both groups. The time to discharge from the postanesthesia care unit (PACU) was determined by a blinded PACU nurse using standard published criteria. The two groups did not differ with respect to demographics, hemodynamic stability, and times to eye opening (5 +/- 3 minutes for desflurane vs. 8 +/- 4 minutes for isoflurane), hand grip on command (9 +/- 4 minutes vs. 12 +/- 1 minutes), and recall of name and date of birth (13 +/- 8 minutes vs. 12 +/- 7 minutes). The median duration of PACU stay was significantly shorter (p < 0.03) in the desflurane group (80 minutes) compared to the isoflurane group (128 minutes). CONCLUSIONS: Desflurane may benefit elderly patients by providing a more rapid recovery from anesthesia, leading to a shorter PACU stay.     

Organophosphonate-degrading PhnZ reveals an emerging family of HD domain mixed-valent diiron oxygenases

The founding members of the HD-domain protein superfamily are phosphohydrolases, and newly discovered members are generally annotated as such. However, myo-inositol oxygenase (MIOX) exemplifies a second, very different function that has evolved within the common scaffold of this superfamily. A recently discovered HD protein, PhnZ, catalyzes conversion of 2-amino-1-hydroxyethylphosphonate to glycine and phosphate, culminating a bacterial pathway for the utilization of environmentally abundant 2-aminoethylphosphonate. Using Mössbauer and EPR spectroscopies, X-ray crystallography, and activity measurements, we show here that, like MIOX, PhnZ employs a mixed-valent Fe^II/Fe^III cofactor for the O₂-dependent oxidative cleavage of its substrate. Phylogenetic analysis suggests that many more HD proteins may catalyze yet-unknown oxygenation reactions using this hitherto exceptional Fe^II/Fe^III cofactor. The results demonstrate that the catalytic repertoire of the HD superfamily extends well beyond phosphohydrolysis and suggest that the mechanism used by MIOX and PhnZ may be a common strategy for oxidative C-X bond cleavage.With the number of known protein sequences rising exponentially, assignment of functions to the ever-expanding proteome is a central, largely unmet challenge in the molecular life sciences. Assignment to a known superfamily based on sequence or structure is usually the first approach to predict the function of an uncharacterized protein and often provides valuable hints for further studies. However, nature uses divergent evolution to create new functions, leading to functional diversification within superfamilies that can be as modest as different substrate specificities or as profound as fundamentally different reaction types (1). Without any biochemical or biological information, functional predictions based solely on superfamily assignment can thus be misleading or incorrect (2).The HD domain superfamily, recognized by Aravind and Koonin in 1998 on the basis of sequence analysis (3), now contains more than 37,000 members occurring in a broad range of organisms in all three domains of life and in more than 240 distinct domain architectures (4). HD proteins possess a conserved α-helical core containing their characteristic H…HD…D sequence motif that binds a divalent metal ion (often Zn^II, Mg^II, or Mn^II) (5). HD proteins with a dinuclear metal cluster, in which two additional histidines from within the D…D region of the domain form a second metal binding site, have also been identified (6, 7). Only a limited number of HD proteins have been biochemically characterized; they almost exclusively catalyze phosphoester hydrolysis, which has led to the general assignment of HD proteins as phosphohydrolases (3, 5, 8–12). The wide phylogenetic distribution and diverse domain architectures of the HD proteins suggest, however, that additional activities might have evolved within the superfamily. Indeed, the enzyme myo-inositol oxygenase (MIOX) exemplifies a mechanistically very different catalytic function for an HD protein (13–15). In MIOX, the conserved H…HD…H…H…D motif binds two iron ions, and the enzyme uses an unprecedented mixed-valent Fe^II/Fe^III cofactor form to catalyze the four-electron (4e^–) oxidative C-C bond cleavage converting myo-inositol (MI; cyclohexan-1,2,3,5/4,6-hexa-ol) to d-glucuronate (13, 16, 17). The Fe^III site coordinates MI, serving as Lewis acid to activate the substrate, and the Fe^II site activates O₂ to produce a superoxo-Fe^III/Fe^III intermediate that initiates the reaction by abstracting a hydrogen atom from C1 of MI (6, 18).The recently discovered HD protein, PhnZ, catalyzes the 4e^– oxidative C-P bond cleavage of 2-amino-1-hydroxyethylphosphonate (OH-AEP) to glycine and phosphate (19) (Fig. 1). It is the second of two enzymes in a recently discovered pathway that degrades the most abundant environmental phosphonate compound, 2-aminoethylphosphonate (2-AEP) (20–23), and its reaction represents the third type of enzymatic C-P bond cleavage to be recognized (23–26). PhnZ was shown to require iron for activity, but the nature of the iron cofactor and its mechanism are unknown (19). The first enzyme in the pathway, the Fe^II- and α-ketoglutarate(αKG)-dependent oxygenase, PhnY, introduces the hydroxyl group on C1 of 2-AEP, activating the compound for subsequent C-P bond cleavage by PhnZ (19). The assignment of PhnZ to the HD domain superfamily, the conservation of the six residues that coordinate the cofactor in MIOX, the dependence of its catalytic activity on the presence of iron, and the analogy between the PhnZ-catalyzed oxidation and that catalyzed by MIOX all suggest that PhnZ might provide the second example of an HD protein using a mixed-valent diiron cofactor to catalyze an oxygenation (rather than a hydrolysis) reaction.Open in a separate windowFig. 1.Reaction catalyzed by PhnZ.Here, we demonstrate by Mössbauer and EPR spectroscopy that PhnZ harbors a diiron cluster and, like MIOX, markedly stabilizes the mixed-valent Fe^II/Fe^III state. The X-ray crystal structure of PhnZ confirms the presence of a diiron cofactor and shows that the substrate is bound to the site 2 Fe ion in a manner analogous to the binding mode of MI in MIOX. PhnZ is an oxygenase requiring O₂ for its reaction, as determined by activity assays and isotope-tracer experiments. Freeze-quench (FQ) EPR experiments demonstrate that the Fe^II/Fe^III state is competent to react rapidly with O₂ to effect the 4e⁻ oxidation of OH-AEP. Our results thus confirm that PhnZ is the second example of an HD protein using a Fe^II/Fe^III diiron cofactor for oxidative bond cleavage and imply that the mechanism used by MIOX and PhnZ might be a more widespread strategy for the oxidative cleavage of C-X bonds in yet unknown reactions. Indeed, phylogenetic analysis of the HD superfamily suggests that there are potentially many other HD domain mixed-valent diiron oxygenases (HD-MVDOs). These findings demonstrate that the catalytic repertoire of the HD superfamily extends well beyond phosphohydrolysis and illustrate once more how nature creates distinct catalytic functions within a common protein scaffold by divergent evolution.     

Alignment of computer-assisted total knee arthroplasty in patients with altered hip center

This study aimed to determine limb and component alignment after computer-assisted total knee arthroplasty in 30 patients (32 limbs) with an altered hip center due to a prior hip implant or deformed femoral head. There were no outliers greater than ±3° in the postoperative coronal alignment of the limb and the femoral component in relation to the altered hip center. Two limbs (8%) were more than ±3° for coronal alignment of the femoral component in relation to the anatomical hip center and 96% of limbs had less than 2° deviation in relation to the altered hip center. Computer-navigated total knee arthroplasty results in accurate restoration of lower limb and component alignment in patients with prior hip implants or deformed femoral heads where accurate restoration of alignment may be challenging due to altered hip center.     

Recent advances in the diagnosis of dermatophytosis

Dermatophytosis is a disease of global significance caused by pathogenic keratinolytic fungi called dermatophytes in both animals and humans. The recent taxonomy of dermatophytes classifies them into six pathogenic genera, namely Microsporum, Trichophyton, Epidermophyton, Nannizzia, Lophophyton and Arthroderma. It is because of the delayed diagnostic nature and low accuracy of dermatophyte detection by conventional methods that paved the path for the evolution of molecular diagnostic techniques, which provide the accurate and rapid diagnosis of dermatophytosis for an appropriate, timely antifungal therapy that prevents the nonspecific over-the-counter self-medication. This review focuses on the importance of rapid and accurate diagnosis of dermatophytosis, limitations of conventional methods, selection of targets in diagnosis, and factors affecting sensitivity and specificity of various molecular diagnostic technologies in the diagnosis of dermatophytosis. Generally, all the molecular techniques have a significant edge over the conventional methods of culture and microscopy in the dermatophytosis diagnosis. However, in mycology laboratory, the suitability of any molecular diagnostic technique in the diagnosis of dermatophytosis is driven by the requirement of time, economy, complexity, the range of species spectrum detected and the scale of diagnostic output required. Thus, various choices involved in the pursuit of a diagnosis of dermatophytosis are determined by the available conditions and the facilities in the laboratory.