Intraoperative management of a hybrid extracorporeal membrane oxygenation circuit for lung transplantation

BACKGROUND

The use of extracorporeal circulation (ECC) for intraoperative cardiopulmonary support during lung transplantation has been increasing in the recent years. Our group previously described a novel hybrid extracorporeal membrane oxygenation (ECMO) circuit for use in lung transplantation.

TECHNIQUE

Our approach for intraoperative management of our novel hybrid ECMO circuit for lung transplantation is driven by two main goals: The first is to deliver management that ensures an appropriate balance between the native and ECMO cardiac outputs in order to provide a stable environment that promotes attenuation of ischemic-reperfusion injury during implantation. The second is to provide a stable hemodynamic environment that results in an appropriate global perfusion guided by multiple monitors and an organ systems-based approach during implantation.

COMMENTS

Our novel technique for intraoperative management of this circuit during lung transplantation is described.

Thoracoabdominal Aortic Aneurysm Repair: Reducing the Incidence of Paraplegia

Paraplegia is a major complication associated with repair of thoracoabdominal aortic aneurysms (TAAA). A number of therapies have been tried over the years, none of which has been successful. Recently, regional lumbar epidural cooling has been tried in an attempt to prolong the safe ischemic time during aortic cross- clamping. In approximately 90 patients in whom the authors have tried this technique, there was no de crease in the incidence of paraplegia in patients with type II TAAAs. This is perhaps not unanticipated be cause the paraplegia is related to a number of factors including the duration of the aortic cross-clamping, the adequacy of collateral circulation, embolization during the procedure, and perhaps thrombosis in situ. Given the multimodal cause of paraplegia, perhaps it is naive to think that a single therapy would be of benefit. Additional studies are necessary to explore the mecha nisms and to prove efficacy or lack of benefit of any techniques designed to decrease the incidence of paraplegia in patients undergoing TAAA repair.

Potential for populations of Aedes j. japonicus to transmit Rift Valley fever virus in the USA

Aedes japonicus japonicus was introduced into the northeastern USA in 1998 and has since spread to more than 25 states. Because this species has been shown to be a competent laboratory vector of several viruses, readily feeds on large mammals, and has become a pest in several areas, there is concern that it might serve as a vector of Rift Valley fever virus (RVFV) should that virus be introduced into North America. Infection with RVFV causes mortality in > 90% of young domestic ungulates (e.g., calves, kids, and lambs), as well as causing a febrile illness and occasional deaths in humans. Therefore, we evaluated Ae. j. japonicus captured in North Carolina and in Maryland for their ability to serve as potential vectors for RVFV. After feeding on infected adult hamsters, these mosquitoes were tested for infection, dissemination, and the ability to transmit RVFV after incubation at 26 degrees C for 7-28 days. Both the Maryland and North Carolina populations of Ae. j. japonicus were highly efficient laboratory vectors of RVFV, with infection rates > 90% and dissemination rates > 84% for those mosquitoes that fed on hamsters with viremias > or = 10(8.5) plaque-forming units/ml. Thus, Ae. j. japonicus should be targeted for immediate control should RVFV be introduced into an area where this mosquito is now present.

LX4211, a dual SGLT1/SGLT2 inhibitor, improved glycemic control in patients with type 2 diabetes in a randomized, placebo-controlled trial

Thirty-six patients with type 2 diabetes mellitus (T2DM) were randomized 1:1:1 to receive a once-daily oral dose of placebo or 150 or 300 mg of the dual SGLT1/SGLT2 inhibitor LX4211 for 28 days. Relative to placebo, LX4211 enhanced urinary glucose excretion by inhibiting SGLT2-mediated renal glucose reabsorption; markedly and significantly improved multiple measures of glycemic control, including fasting plasma glucose, oral glucose tolerance, and HbA(1c); and significantly lowered serum triglycerides. LX4211 also mediated trends for lower weight, lower blood pressure, and higher glucagon-like peptide-1 levels. In a follow-up single-dose study in 12 patients with T2DM, LX4211 (300 mg) significantly increased glucagon-like peptide-1 and peptide YY levels relative to pretreatment values, probably by delaying SGLT1-mediated intestinal glucose absorption. In both studies, LX4211 was well tolerated without evidence of increased gastrointestinal side effects. These data support further study of LX4211-mediated dual SGLT1/SGLT2 inhibition as a novel mechanism of action in the treatment of T2DM.

Updated distribution records for Anopheles vagus (Diptera: Culicidae) in the Republic of Philippines, and considerations regarding its secondary vector roles in Southeast Asia

Distribution records for Anopheles (Cellia) vagus in the Republic of the Philippines were updated, including recent collection and museum records from Luzon and Visayas Provinces. Larval habitats (e.g. rice paddies, irrigation and drainage ditches), associated species, and the vector potential of this species were also noted.

Influence of coronary artery disease on outcomes after liver transplantation

Patients with coronary artery disease (CAD) who undergo liver transplantation (OLT) have been previously identified as a high-risk group. Since that identification, the management of CAD has undergone significant changes as has the cardiovascular screening and selection of patients for OLT. We retrospectively identified 42 patients with known CAD who underwent OLT to compare outcomes with a control group of 42 patients without CAD who were matched for gender, age, and primary liver disease. Mortality rates were higher in the CAD than the control group at 1 year (5 vs 1) and 3 years (11 vs 3; P < .05) although lower than previously reported (at 3 years, 26% vs 50%). New cardiovascular morbidity was also more frequent among the CAD than control group at 1 year (11 vs 3; P < .05) and 3 years (16 vs 4; P < .05). Although outcomes for patients with CAD undergoing OLT are improved from historical levels, they are still worse than those in patients without CAD despite current management and selection strategies.

Effect of lidocaine on endothelin-1-mediated airway smooth muscle contraction in the rat trachea

BACKGROUND

Endothelin-1 (ET-1) is a 21-amino acid peptide that induces airway smooth muscle (ASM) constriction by activating G-protein-coupled endothelin receptors A (ETA) and B (ETB), thereby increasing intracellular calcium ([Ca(2+)]i). Lidocaine can cause direct ASM relaxation by decreasing [Ca(2+)]i. This study investigated the direct relaxant effects of lidocaine on ET-1-induced contraction in rat tracheas.

METHODS

Mid-tracheal rings (2-3 mm diameter) were excised and attached to a force transducer suspended in Krebs-Henseliet solution. Carbachol concentration-response curves (10 nM and 100 microM) were generated to determine maximal contractility (C(max)). ET-1 (3 nM to 200 nM) responses to lidocaine (100 nM, 10 microM, and 1 mM) were measured in the presence and absence of extracellular calcium. Contractile responses to ET-1 are presented as percentage of Cmax (% Cmax). Data were analyzed using analysis of variance and unpaired t-tests with Welsh correction.

RESULTS

No significant effect on ET-1-induced constriction was noted in the presence of low concentrations of lidocaine (100 nM and 1 muM), with and without extracellular calcium. At a concentration of 1 mM, lidocaine decreased the response to 100 nM and 200 nM ET-1 by 26% in the presence of extracellular calcium and by 37 and 44%, respectively, in the absence of calcium.

CONCLUSION

The attenuating effect of lidocaine (1 mM) on ET-1-induced ASM contraction is not exclusively dependent on the blockade of intracellular calcium entry.

A pilot study on continuous femoral perineural catheter for analgesia after total knee arthroplasty: the effect on physical rehabilitation and outcomes

Two techniques of postoperative analgesia for primary total knee arthroplasty were compared retrospectively. Twenty-four patients received a femoral nerve catheter with continuous infusion of ropivacaine (FNC group), whereas 26 patients received intravenous (IV) opioids (IV opioid group). Pain and rehabilitation scores and hospital length of stay (LOS) were compared. On the first postoperative day, both groups reported similar pain scores. After 4 sessions of twice-daily rehabilitation, the FNC group used less IV patient-controlled opioids (29.1% vs 84.5%, P = .0001) and demonstrated better performance with knee flexion and mobility. Hospital LOS was significantly less in the FNC group (3.6 vs 4.2 days, P = .034). Femoral nerve catheters with continuous infusion of ropivacaine provide satisfactory analgesia, improve rehabilitation, and shorten hospital LOS.

Inhaled nitric oxide for acute right-ventricular dysfunction after extrapleural pneumonectomy

Increased pulmonary vascular pressure and decreased right-ventricular performance may occur following pneumonectomy. Inhaled nitric oxide decreases right-ventricular afterload and improves cardiac index by selectively decreasing pulmonary vascular resistance without causing systemic hypotension. We report the use of inhaled nitric oxide in a patient with acute right-ventricular dysfunction after extrapleural pneumonectomy.

Is there a role for inhaled nitric oxide as a rescue therapy in respiratory failure associated with hematologic malignancies?

Inhaled nitric oxide has been demonstrated to improve oxygenation in critically ill patients requiring mechanical ventilation. We therefore performed a retrospective review to determine the outcome of patients with hematological malignancies and acute respiratory failure who received inhaled nitric oxide (INO) in a multidisciplinary intensive care unit of a single tertiary referral medical center. Thirteen patients with hematological malignancies who required endotracheal intubation and mechanical ventilation and received INO for acute respiratory failure between January 1998 and December 2002 were identified. Mean +/- standard deviation (SD) age was 47.6 (+/-13.2) years. The mean +/- SD Acute Physiology and Chronic Health Evaluation (APACHE) III score on the day of ICU admission was 94.1 +/- 33.7 with a mean (SD) predicted probability of ICU death of 42.4% (+/-28.6). Mean APACHE III score on the day of initiating INO was 107.6 (+/-34.4) with a predicted mortality in the intensive care unit of 72.7% (+/-23.3). Mean PaO(2) to FiO(2) (PF) ratios (+/-SD) prior to, and immediately after, the initiation of INO were 62.6 (+/-28.2) and 111 (+/-65.1), respectively (P < 0.001). The median duration of INO therapy was 41.8 h (interquartile range, 6.3-98.2). Patients with hematological malignancies and acute respiratory failure to whom INO was administered had clinical deterioration since ICU admission. Despite a marked initial improvement in arterial oxygen tension, all patients ultimately died in the intensive care unit, 8 of them within 48 h of initiating INO. Therefore, despite initial improvement in oxygenation, we did not observe any survival benefit to INO in this setting.

Occurrence and relative abundance of mosquitoes in stormwater retention facilities in North Carolina, U.S.A

Throughout the 2004 mosquito season, 52 stormwater retention facilities were sampled to characterize the seasonal occurrence and relative abundance of mosquito species in relation to the structural complexity and biological diversity of the facilities. The three different types of facilities included standard wet ponds (n=20), innovative ponds (n=14), and wetland ponds (n=18). All retention structures were sampled at the beginning, middle and end of the mosquito season so that seasonal changes in mosquito production could be characterized. Overall samplings, mosquitoes were collected from 34% of the retention structures. Fourteen species representing 7 genera were collected, but only 5 species were commonly collected in all three types of stormwater management facilities. In general, the seasonal prevalence and relative abundance of mosquito species did not vary among three types of retention structures. A significant association (P < 0.01) between the presence of mosquito larvae or pupae and the absence of mosquitofish was found for innovative and wetland stormwater retention facilities but not for standard retention facilities (P > 0.05).

Airway management after failure to intubate by direct laryngoscopy: outcomes in a large teaching hospital

PURPOSE

The purpose of this single-centre database review was to establish the incidence of failure to intubate by direct laryngoscopy, to measure morbidity and mortality associated with this event, and to examine the use and efficacy of alternative airway devices.

METHODS

Difficult intubation via direct laryngoscopy at Mayo Clinic Rochester is recorded in an electronic database using a functional classification: 0 = no difficulty; 1 = mild to moderate difficulty; and 2 = severe difficulty often requiring a change in intubation technique. Using this database, the total number of intubations was determined for a selected review period and the incidence of failure to intubate by direct laryngoscopy was established. Abstraction of chart data allowed for determination of associated morbidity and mortality, success of alternative airway devices, and case cancellation rate.

RESULTS

During the period from August 1, 2001 through December 31, 2002, 37,482 patients underwent general anesthesia with attempted direct laryngoscopy. One hundred sixty-one patients (0.43%) could not be intubated by direct laryngoscopy alone. Morbidity associated with difficult intubation included soft tissue/dental damage (n = 8), intraoperative cardiac arrest (n = 1), and possible aspiration (n = 1). Three patients required intensive care unit admission. There was no associated mortality. The most commonly used alternative airway device was the flexible fibreoptic scope. Five case cancellations resulted from failure to intubate with alternative devices.

CONCLUSION

The rate of unexpected failure to intubate by direct laryngoscopy is essentially unchanged from earlier studies. While morbidity was low, continued education and early use of alternative difficult airway devices may further limit complications associated with this event.

Morbidity and mortality of deep sedation in outpatient bone marrow biopsy

Deep sedation is being provided at an increasing rate for patients undergoing bone marrow biopsy and aspiration (BMBA). The aim of this study was to establish the safety of deep sedation used for adults undergoing BMBA. A nonrandomized database analysis and retrospective review of patient records from January 1997 to December 2000 was performed; 5,811 patients were identified as having undergone their first outpatient BMBA. Outcome measures included 30-day mortality and same-day hospital admission; surrogate measures included need for a surgical procedure or receipt of red blood cells within the 48 hr following the BMBA. Patients who received intravenously administered midazolam, fentanyl, and propofol for maintenance of deep sedation plus infiltration of a local anesthetic (n = 2,604; 45%) comprised the deep sedation group; those who received infiltration of a local anesthetic but no intravenous sedation or analgesia (n = 3,207; 55%) comprised the local anesthesia group. Patients in the deep sedation group compared to those in the local anesthesia group were less likely to die within 30 days (0.69% vs. 1.34%, P = 0.018) and less likely to receive red blood cells (1.27% vs. 2.25%, P = 0.006). No other differences between the groups were found. Although the study was retrospective and nonrandomized, the results suggest that the use of deep sedation for outpatient BMBA is as safe as using local anesthesia.

Practice variability in management of acute respiratory distress syndrome: bringing evidence and clinician education to the bedside using a web-based teaching tool

BACKGROUND

Clinical practice often lags behind publication of evidence-based research and national consensus guidelines.

OBJECTIVE

To assess practice variability in the clinical management of acute respiratory distress syndrome (ARDS) and test an evidence-based, online clinician-education tool designed to improve intensive-care clinicians' understanding of current evidence about ARDS management.

METHODS

We surveyed 117 intensive care clinicians (16 critical care physician specialists, 28 resident physicians, 50 critical care nurses, and 23 respiratory therapists) with an online questionnaire in our tertiary academic institution. Fifty of the original respondents (12 residents, 26 critical care nurses, and 12 respiratory therapists) also responded to a repeat survey that included context-sensitive hypertext links to a summary of critically appraised primary articles regarding ARDS management, to determine if the responses changed after the clinicians had read the evidence-based summary information.

RESULTS

Critical care physician specialists were most likely to choose the low-tidal-volume (low-VT) ventilation strategy and protocol-based ventilator weaning and were least likely to choose neuromuscular blockade or parenteral nutrition (p < 0.05). In a paired comparison, individual respondents were more likely to choose treatment options that are based on stronger evidence (low-VT, daily interruption in sedation, and protocol weaning [p < 0.01]). We also reviewed the medical records of 100 patients who were mechanically ventilated for > 48 h, during the 6 months before and after the survey, from which we identified 45 ARDS patients. Following the clinician-education intervention, ARDS patients were less likely to receive potentially injurious high-VT ventilation (mean day-3 VT 10.3 +/- 2.3 mL/kg before vs 8.9 +/- 1.7 mL/kg after, p = 0.02).

CONCLUSION

Web-based teaching tools are useful to educate intensive-care practitioners and to promote evidence-based practice.

Galectin-3-mediated adherence of Proteus mirabilis to Madin-Darby canine kidney cells

Proteus mirabilis is an important cause of urinary tract infections (UTIs) and can result in acute pyelonephritis. Proteus mirabilis expresses several, morphologically distinct, fimbrial species, and previous studies have shown that the nonagglutinating fimbriae (NAF) mediate bacterial adherence to a number of cell lines, including Madin-Darby canine kidney (MDCK) cells. Immunoblot overlay analysis of the plasma membrane fraction from MDCK cells with purified NAF revealed a 34-kDa band, which has been analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Database search identified galectin-3 as a potential protein candidate. Immunocytochemical assay of MDCK cells with a galectin-3-specific monoclonal antibody, anti-Mac-2, confirmed its presence on the plasma membrane extracellular surface. Preincubation of P. mirabilis with anti-Mac-2 monoclonal antibodies, specific for galectin-3, resulted in the inhibition of bacterial binding to MDCK cells. These data suggest a role for galectin-3, interacting with appropriately glycosylated surface receptors and P. mirabilis fimbriae, as a mediator of bacterial adherence in vitro.

The use of the intubating laryngeal mask endotracheal tube with intubating devices

IMPLICATIONS

Despite adequate visualization of the vocal cords using specialized airway devices, anatomical factors and the physical characteristics of the tube may cause difficulty when performing endotracheal intubation. The endotracheal tube designed for use with the intubating laryngeal mask airway may facilitate intubation in these circumstances.

Identification of selective inhibitors of cyclin dependent kinase 4

A new structural type of kinase inhibitor, containing a benzocarbazole nucleus, has been identified. Members of the series are selective for inhibition of the cyclin dependent kinase family of enzymes. Although the cdks are highly homologous, representatives of the series showed intra-cdk selectivities, especially for cdk4. SAR studies elucidated the important features of the molecules for inhibition.

The synthesis of an exhaustively stereodiversified library of cis-1,5 enediols by silyl-tethered ring-closing metathesis

[reaction: see text] This report describes the parallel synthesis of all 16 stereoisomers of the cis-1,5 enediol module 1. Compounds 1 derive from 2 by silicon-tethered ring-closing metathesis. Such libraries of stereodiversified ligands provide a unique approach to ligand discovery that employs exhaustive searching of conformational space.

Evaluation of 1-octen-3-ol, carbon dioxide, and light as attractants for mosquitoes associated with two distinct habitats in North Carolina

Field studies were conducted in North Carolina to determine the responses of mosquitoes found in salt marsh and inland creek flood plain areas to 1-octen-3-ol (octenol), carbon dioxide (CO2), and light in various combinations with Centers for Disease Control (CDC) light traps. Over 56,000 adult mosquito specimens of 12 species in 4 genera were collected in the salt marsh. They exhibited a general response pattern of octenol + CO2 + light > CO2 + light = octenol + CO2 > octenol + light > octenol alone. Significantly, more Aedes sollicitans, Ae. taeniorhynchus, Anopheles bradleyi, and Culex salinarius were attracted to octenol + CO2 + light than to CO2 + light. Over 19,000 specimens of 24 species in 7 genera were collected in the inland creek flood plain. Although the response patterns to the attractants were similar to those in the salt marsh area, there was no significant difference between octenol + CO2 + light and CO2 + light. Aedes vexans, An. crucians, and An. punctipennis were attracted nearly equally to these two attractant combinations. These studies demonstrate that responses to combinations of these attractants are species specific. However, different combinations of attractants can significantly increase the collection of targeted species important in arbovirus transmission. The use of these combinations would be very beneficial in mosquito-borne virus surveillance studies. The use of octenol by itself or in conjunction with light was found the least useful for collecting mosquitoes in both habitats.

The binding of Proteus mirabilis nonagglutinating fimbriae to ganglio-series asialoglycolipids and lactosyl ceramide

Proteus mirabilis is a common opportunistic Gram-negative uropathogen that infects the upper urinary tract. We have examined the role of the nonagglutinating fimbriae (NAF) of P. mirabilis in mediating bacterial adhesion to cell surface receptors. Purified NAF of P. mirabilis were demonstrated to bind to a number of glycolipids, including asialo-GM1, asialo-GM2, and lactosyl ceramide (LacCer) in solid-phase binding assays and in thin layer chromatography (TLC) overlay assays. Furthermore, preincubation of the biotinylated NAF (Bt-NAF) with anti-NAF monoclonal antibodies resulted in inhibition of NAF binding to immobilized asialo-GM1, asialo-GM2, and LacCer. In adherence assays, P. mirabilis binding to Madin-Darby canine kidney (MDCK) cells was inhibited by murine anti-asialo-GM1 monoclonal antibodies H2G10 to about 50% of the binding level in the absence of the antibody, specific for the terminal beta-galactopyranosyl residue of asialo-GM1 (Harrison et al. 1998). The results of this study suggest that NAF of P. mirabilis recognize a GalNAc beta 1-4Gal moiety present in the ganglio-series of asialoglycolipids, and that the terminal beta-galactopyranosyl-containing glycoconjugates play a role in NAF-mediated adherence of P. mirabilis to MDCK cells. Similarly to other bacteria, P. mirabilis NAF was also shown to express the LacCer specificity.

Inhaled nitric oxide reduces pulmonary artery pressures in portopulmonary hypertension

Pulmonary artery hypertension in association with liver failure (portopulmonary hypertension [PPHTN]) is a significant barrier to liver transplantation because patients with this condition have a very high mortality when transplantation is undertaken. Inhaled nitric oxide (NO), a potent pulmonary vasodilator, reduces pulmonary artery pressure (PAP) in some patients with primary pulmonary hypertension, but its effect in patients with PPHTN is controversial. We investigated the hemodynamic effects of inhaled NO in 6 patients with PPHTN. Five of 6 patients responded to NO inhalation with decreases in PAP and pulmonary vascular resistance of greater than 10%; these decreases were statistically significant at NO concentrations of 10 and 30 ppm. Cardiac output did not significantly change. We conclude that inhalation of NO reduces PAPs in some patients with PPHTN.

Preclinical antitumor efficacy of analogs of XK469: sodium-(2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]propionate

A series of quinoxaline analogs of the herbicide Assure was found to have selective cytotoxicity for solid tumors of mice in a disk-diffusion-soft-agar-colony-formation-assay compared to L1210 leukemia. Four agents without selective cytotoxicity and 14 agents with selective cytotoxicity were evaluated in vivo for activity against a solid tumor. The four agents without selective cytotoxicity in the disk-assay were inactive in vivo (T/C > 42%). Thirteen of the fourteen agents with selectivity in the disk-assay were active in vivo (T/C < 42%). Five of the agents had curative activity. These five agents had a halogen (F, Cl, Br) in the 7-position (whereas Assure had a CI in the 6 position). All agents with curative activity were either a carboxylic acid, or a derivative thereof, whereas Assure is the ethyl ester of the carboxylic acid. All other structural features were identical between Assure and the curative agents. Assure had no selective cytotoxicity for solid tumors in the disk-assay, and was devoid of antitumor activity. The analog XK469 is in clinical development.

North Carolina mosquito records. I. Uncommon Aedes and Anopheles (Diptera: Culicidae)

New distribution records are provided for 10 mosquito species that are rare or uncommon in North Carolina: Aedes aegypti, Ae. cinereus, Ae. dupreei, Ae. fulvus pallens, Ae. hendersoni, Ae. mitchellae, Ae. thibaulti, Ae. tormentor, Ae. trivittatus, and Anopheles atropos. Biological notes are provided for habitats, behavior, and, in some cases, color patterns. Comments are also made about 6 additional species that are rare or uncommon in North Carolina.

A kinetics approach to the characterization of an IgM specific for the glycolipid asialo-GM1

The unique features of protein recognition of membrane-anchored glycolipids were investigated by surface plasmon resonance (SPR) monitoring of antibody interactions with glycolipids contained in liposomes. Several positive hybridomas belonging to the IgM and IgG classes were identified when tested for binding to the glycosphingolipid asialo-GM1 (Gal beta1-3GalNAcl beta1-4Gal beta1-4Glc beta1-1-Ceramide). Preliminary screening by enzyme immunoassay and thin layer chromatography (TLC) followed by immunostaining indicated that only those of the IgM type showed specificity for this glycosphingolipid. One of the IgMs, H2G10, was purified and further characterized using a SPR technique that involved antibody binding to liposomal asialo-GM1. This method generated kinetic and affinity constants for the interaction and confirmed the specificity of H2G10 for the terminal galactose of asialo-GM1. Interestingly, inhibition of antibody binding to asialo-GM1 liposomes by the asialo-GM1 tetrasaccharide reduced the total amount of bound antibody but increased the affinity of the antigen-antibody interaction due to an inverse relationship between tetrasaccharide concentration and the H2G10 dissociation rate constant. We believe that this effect is due to the selective inhibition of lower valency binding by the tetrasaccharide which, in turn, promotes higher avidity antibody-carbohydrate interactions. The observation that slower dissociation rate constants were also observed at high antigen to antibody ratios supports this interpretation. These results highlight the insight that kinetic data can provide in efforts to promote and inhibit high avidity interactions such as those involving proteins and carbohydrates.

The expression of nonagglutinating fimbriae and its role in Proteus mirabilis adherence to epithelial cells

Proteus mirabilis is a common causative agent of human urinary tract infections, especially in catheterized patients and in those patients with structural abnormalities of the urinary tract. In addition to the production of hemolysin and urease, fimbriae-mediated adherence to uroepithelial cells and kidney epithelium may be essential for virulence of P. mirabilis. A single P. mirabilis strain is capable of expressing several morphologically distinct fimbrial species, which can each be favoured by specific in vitro growth conditions. The fimbrial species reported to date include mannose-resistant/Proteus-like fimbriae, ambient temperature fimbriae, P. mirabilis fimbriae, and nonagglutinating fimbriae (NAF). Here, using intact bacteria or purified NAF as immunogens, we have generated the first reported NAF-specific monoclonal antibodies (mAbs). Bacteria expressing NAF as their only fimbrial species adhered strongly to a number of cell lines in vitro, including uroepithelial cell lines. Binding of P. mirabilis was markedly reduced following preincubation with NAF-specific mAbs and Fab fragments. The presence of NAF with highly conserved N-terminal sequences on all P. mirabilis strains so far examined, combined with the ability of both anti-NAF mAbs and purified NAF molecules to inhibit P. mirabilis adherence in vitro, suggests that NAF may contribute to the pathogenesis of P. mirabilis.

Ticks (Acari: Ixodida) uncommonly found biting humans in North Carolina

Collection records are presented that document human-biting by Otobius megnini, Amblyomma maculatum, Haemaphysalis leporispalustris, Ixodes cookei, Ixodes dentatus, and Rhipicephalus sanguineus in North Carolina. These species are either extremely rare in North Carolina or they are normally considered non-human feeders. The record of Otobius megnini represents the first collection of this species in North Carolina in over 50 years. It is proposed that immature Rhipicephalus sanguineus feed on humans much more than previously suspected and that they represent a threat for the transmission of pathogens to humans.

Identifying Psorophora horrida females in North Carolina (Diptera:Culicidae)

Morphological characters to separate Psorophora horrida (Dyar and Knab) and Psorophora ferox (Von Humboldt) females are identified and defined. In addition to the 3 characters used to separate these 2 species in published keys, an additional 6 characters were found. Of the total of 9 characters identified, 6 are reliable at the 100% level, based on North Carolina specimens. These additional characters will assist greatly in identifying Ps, horrida specimens. Variation or hindtarsomere 4 of Ps. horrida, consisting of dark-scaled patterns, were also noted. Characters for separating Psorophora cyanescens (Coq.) and Psorophora mathesoni Belkin and Heinemann from Ps. ferox and Ps. horrida are discussed.

The HeLa cell receptor for enterovirus 70 is decay-accelerating factor (CD55)

Enterovirus 70 (EV70) is a recently emerged human pathogen belonging to the family Picornaviridae. The ability of EV70 to infect a wide variety of nonprimate cell lines in vitro is unique among human enteroviruses. The importance of virus receptors as determinants of viral host range and tropism led us to study the host cell receptor for this unusual picornavirus. We produced a monoclonal antibody (MAb), EVR1, which bound to the surface of HeLa cells and protected them against infection by EV70 but not by poliovirus or by coxsackievirus B3. This antibody also inhibited the binding of [35S]EV70 to HeLa cells. MAb EVR1 did not bind to monkey kidney (LLC-MK2) cells, nor did it protect these cells against virus infection. In Western immunoassays and in immunoprecipitations, MAb EVR1 identified a HeLa cell glycoprotein of approximately 75 kDa that is attached to the cell membrane by a glycosyl-phosphatidylinositol (GPI) anchor. Decay-accelerating factor (DAF, CD55) is a 70- to 75-kDa GPI-anchored membrane protein that is involved in the regulation of complement and has also been shown to function as a receptor for several enteroviruses. MAb EVR1 bound to Chinese hamster ovary (CHO) cells constitutively expressing human DAF. Anti-DAF MAbs inhibited EV70 binding to HeLa cells and protected them against EV70 infection. Transient expression of human DAF in murine NIH 3T3 cells resulted in binding of labelled EV70 and stably, transformed NIH 3T3 cells expressing DAF were able to support virus replication. These data indicate that the HeLa cell receptor for EV70 is DAF.

Production and characterization of monoclonal antibodies to Actinobacillus pleuropneumoniae serotype 5b

Monoclonal antibodies specific for capsular polysaccharide (CPS) and lipopolysaccharide (LPS) of A. pleuropneumoniae serotype 5b were generated by hybridoma cells and selected by indirect ELISA of culture supernatants with purified and structurally defined LPS and CPS preparations and their synthetic conjugates. It was shown in this study that at least one monoclonal antibody, 3B4, presented 100% specificity and recognized all A. pleuropneumoniae serotype 5 field strains tested in a dot-ELISA assay.

Opioids and benzodiazepines

Most patients in the intensive care unit experience pain and anxiety, which are treated most commonly with an opioid or a benzodiazepine. These compounds are effective and have a well-established safety record. With the exception of associated respiratory depression, they have a relatively wide therapeutic window. New approaches and formulations for opioids and benzodiazepines are being used with continued success in the clinical setting.

Isolation of potosi virus from Aedes albopictus in North Carolina

A total of 4,169 adult mosquitoes were aspirated from 3 tire disposal sites in North Carolina for virus assays. Aedes albopictus was the dominant species, with a relative abundance of approximately 99%. Potosi virus was isolated from one pool of 68 female Ae. albopictus. Priorities for future Potosi virus research and the implications of the North Carolina isolate are discussed.

The clinical spectrum of critical illness polyneuropathy

OBJECTIVE

To describe the entity of critical illness polyneuropathy and review our experience with six cases.

DESIGN

We present case reports of six patients with polyneuropathy associated with critical illness, who received medical care at the Mayo Clinic between 1992 and 1994, and discuss similar cases from the literature.

RESULTS

Critical illness may damage peripheral nerves. In previous studies, sepsis and multiorgan failure have been found to trigger a peripheral neuropathy. Of our six patients with critical illness polyneuropathy, all had a preceding severe bacterial infection or septic shock. In one patient who had long-term administration of vecuronium bromide and had received massive intravenous doses of corticosteroids, sural nerve and quadriceps muscle biopsy specimens were available; they revealed axonal neuropathy and notable myopathic changes, respectively. The outcome was good in patients who survived the critical illness.

CONCLUSION

Polyneuropathy in critically ill patients may be a cause of severe generalized limb weakness and occurs in the setting of a sepsis syndrome. The long-term outcome is good in patients who recover from the underlying critical illness. Compression neuropathies may be a cause of permanent sequelae.

Managing risk to minimize liability

Agencies undoubtedly face increased chances of investigation, yet risk management may be as simple as keeping good records and following standard operating procedures. One pilot program exemplifies how this can reduce an agency's liability exposure.

Simple computer measurement of pulmonary VCO2 per breath

Measurements of the volume of CO2 exhaled per breath (VCO2/br) are preferable to end-tidal PCO2, when the exhaled flow and CO2 waveforms may be changing during unsteady states, such as during alterations in positive end-expiratory pressure or alterations in cardiac output. We describe computer algorithms that determine VCO2/br from digital measurements of exhaled flow (including discontinuous signals common in anesthesia circuits) and CO2 concentration at the airway opening. Fractional concentration of CO2 is normally corrected for dynamic response and transport delay (TD), measured in a separate procedure. Instead, we determine an on-line adjusted TD during baseline ventilation. In six anesthetized dogs, we compared the determination of VCO2/br with a value measured in a simultaneous collection of expired gas. Over a wide range of tidal volume (180-700 ml), respiratory rate (3-30 min-1), and positive end-expiratory pressure (0-14 cmH2O), VCO2/br was more accurate with use of the adjusted TD than the measured TD (P less than 0.05).

Significance of circumsporozoite-specific antibody in the natural transmission of Plasmodium falciparum, Plasmodium vivax, and Plasmodium malariae in an aboriginal (Orang Asli) population of central peninsula Malaysia

Two hundred and seventy-five Orang Asli volunteers living in nine villages in the Pos Legap Valley of Perak State, peninsular Malaysia, participated in a prospective study designed to characterize the epidemiological, parasitological, and entomological characteristics of Plasmodium falciparum, P. vivax, and P. malariae malaria transmission. Prevalence rates for the three plasmodial species at initiation of the study ranged from 56% in the 0-4-year-old age group to 0% in individuals over the age of 40. Entomological surveys were conducted, enabling us to determine mosquito salivary gland-positive rates and entomological inoculation rates of 1.2 infectious mosquito bites per person per month for P. falciparum, 2.4 for P. vivax, and 0.3 for P. malariae. Cumulative incidence rates over the 16 weeks of the study, following radical cure of all volunteers, were 22.5% for P. falciparum, 12.7% for P. vivax, and 1.5% for P. malariae. The median baseline antibody titer against the immunodominant repetitive B cell epitope of P. falciparum or P. vivax circumsporozoite protein was significantly higher for volunteers who did not become parasitemic. Volunteers were selected for further study if they had evidence of being challenged with P. falciparum sporozoites during the study, based on a two-fold or greater increase in antibody titer against the immunodominant repetitive B cell epitope of the circumsporozoite protein. Resistance to infection was seen in six of 10 individuals who had high (greater than 25 OD units) baseline ELISA titers, compared with only three of 24 individuals who had low baseline ELISA titers (chi 2 P less than 0.02). A similar analysis for P. vivax did not show a significant correlation.