Laboratory evaluations of methylated soy oil and monoterpenes as mosquito larvicides

The larvicidal toxicities of methylated soy oil (MSO) and surfactant combinations were compared to 2 commercially available oil larvicides (Golden Bear Oil 1111 and Bonide) in standard laboratory bioassays of 4th-stage larvae of Culex pipiens Linn. The dose lethal to 50% of the test organisms (LD50) and the dose lethal to 95% of the test organisms (LD95) values are presented as microliters (microl) per beaker (treatment surface area of 54 cm2). The 2 surfactant-MSO mixtures differed significantly in their toxicity to Cx. pipiens larvae; 2% Pyroter CPI-40 in MSO was more toxic than 2% Pluronic L121 in MSO (LD50 = 3.8 microl per 54 cm2 and 11.3 microl per 54 cm2, respectively). The 2 most active larvicides were Golden Bear Oil (LD50 = 3.6 microl per 54 cm2) and the 2% Pyroter-MSO mixture. These 2 were not significantly different from each other. Bonide (LD50 = 6.2 microl per 54 cm2) and the Pluronic L121-MSO mixture (LD50 = 11.3 microl per 54 cm2) were less toxic than Golden Bear Oil and the MSO-Pryroter mixture and they were significantly different from each other. Bioassays with 4th-stage larvae of Anopheles stephensi Liston showed that toxicity of the Pyroter-MSO formulations increased about 2-fold from 18 degrees C to 24 degrees C (LD50 = 20.5 microl per 54 cm2 and 11.8 microl per 54 cm2, respectively). The laboratory bioassays suggest that MSO mixed with surfactants are potential mosquito larvicides. We also evaluated the influence of the 2 surfactants on the toxicity of 3 monoterpenes. The larvicidal activity of citral and limonene increased with the addition of surfactants, but neither surfactant enhanced the toxicity of cineole. All 3 monoterpenes, with and without surfactants, were considered poor candidates as surface larvicides because of their high volatilities.

Extracellular targeting of choline-binding proteins in Streptococcus pneumoniae by a zinc metalloprotease

A genetic-based search for surface proteins of Streptococcus pneumoniae involved in adhesion identified a putative zinc metalloprotease (ZmpB). ZmpB shared high amino acid sequence similarities with IgA1 proteases of Gram-positive bacteria, but ZmpB had neither IgA1 nor IgA2 protease activity. Analysis of a family of surface-expressed proteins, the choline-binding proteins (Cbp's), in a zmpB-deficient mutant demonstrated a global loss of surface expression of CbpA, CbpE, CbpF and CbpJ. CbpA was detected within the cytoplasm. The zmpB-deficient mutant also failed to lyse with penicillin, a sign of lack of function of the Cbp LytA. Immunodetection studies revealed that the autolysin (LytA), normally located on the cell wall, was trapped in the cytoplasm colocalized with DNA and the transformation protein CinA. Trafficking of CinA and RecA to the cell membrane during genetic competence was also not observed in the zmpB-deficient mutant. These results suggest a protease dependent regulatory mechanism governing the translocation of CinA and the Cbp's LytA and CbpA of S. pneumoniae.

Uncontrolled oxygen administration and respiratory failure in acute asthma

STUDY OBJECTIVES

To determine if 100% oxygen administration adversely influences gas exchange in acutely ill asthmatic subjects.

DESIGN

Prospective preinterventional and postinterventional comparison.

SETTING

University hospital emergency department.

PATIENTS

Thirty-seven asthmatic subjects seeking care for symptomatic exacerbations.

INTERVENTIONS

Twenty minutes of 100% oxygen administration by face mask.

MEASUREMENTS AND RESULTS

Arterial blood gases and FEV(1) were measured before and during the last minute of oxygen administration. On presentation, the subjects had moderately severe airway obstruction (FEV(1), 49.1 +/- 3.6% of predicted); hypocarbia (PaCO(2), 36.8 +/- 1.1 mm Hg); hypoxemia (PaO(2), 70.2 +/- 2.5 mm Hg); and respiratory alkalosis (pH, 7.43 +/- 0.01). During oxygen breathing, 25 patients (67.6%) experienced elevations in PaCO(2) ranging from 1 to 10 mm Hg (mean, 4.1 +/- 0.6 mm Hg; p = 0.0003). The increase was considered to be a physiologic manifestation of the Haldane effect (ie, < or = 2 mm Hg) in 10 subjects, but in the remaining 15 subjects (40.5% of the total studied), the elevation represented worsening gas exchange. In seven of these patients (46.7%), hypercapnic respiratory failure developed (PaCO(2) before oxygen, 39.6 +/- 0.6; during oxygen, 44.7 +/- 0.7 mm Hg; p = 0.005), and in six patients (40%), it worsened (PaCO(2) before oxygen, 46.8 +/- 1.9; during oxygen, 52.0 +/- 3.1 mm Hg; p = 0.03). In general, the tendency toward hypercarbia was the greatest in the participants with the most severe airway obstructions.

CONCLUSIONS

Our data demonstrate that the administration of 100% oxygen to acutely ill asthmatics may adversely influence carbon dioxide elimination.

Signal transduction by a death signal peptide: uncovering the mechanism of bacterial killing by penicillin

The binding of bactericidal antibiotics like penicillins, cephalosporins, and glycopeptides to their bacterial targets stops bacterial growth but does not directly cause cell death. A second process arising from the bacteria itself is necessary to trigger endogenous suicidal enzymes that dissolve the cell wall during autolysis. The signal and the trigger pathway for this event are completely unknown. Using S. pneumoniae as a model, we demonstrate that signal transduction via the two-component system VncR/S triggers multiple death pathways. We show that the signal sensed by VncR/S is a secreted peptide, Pep27, that initiates the cell death program. These data depict a novel model for the control of bacterial cell death.

Isolation and characterization of vancomycin-tolerant Streptococcus pneumoniae from the cerebrospinal fluid of a patient who developed recrudescent meningitis

The emergence of tolerance to vancomycin has recently been reported in Streptococcus pneumoniae, the most common cause of bacterial meningitis. A vancomycin- and cephalosporin-tolerant strain of S. pneumoniae, the Tupelo strain, was isolated from the cerebrospinal fluid of a patient who then developed recrudescence of meningitis despite treatment with vancomycin and a third-generation cephalosporin. The Tupelo strain evidenced no lysis in the exponential or stationary phase of growth when exposed to vancomycin and only minimal loss of viability. Further characterization revealed normal autolysin expression, localization, and triggering by detergents, indicating that the defect leading to tolerance in the Tupelo strain is in the control pathway for triggering of autolysis. Because tolerance is a precursor phenotype to resistance and may lead to clinical failure of antibiotic therapy, these observations may have important implications for vancomycin use in infections caused by S. pneumoniae.

Modification of the Kock's pouch for bladder replacement

AIM

To describe a modification of the Kock's pouch and present our clinical experience in its application.

METHOD

After isolating an adequate ileal segment, the bowel is split by a longitudinal incision, with both ends remaining unopened for about 3-4 cm in length. Previously anastomozed ureters are inserted into the proximal end so that a nipple valve is created. The distal unsplit end serves for a direct anastomosis with the urethra. During the past 9 years, this surgery was performed in 41 patients who underwent radical cystectomy due to invasive carcinoma. Seventeen patients died for unknown reasons or were lost to follow-up. The remaining 24 were included in the follow-up for a period of 7 months to 6 years post surgery.

RESULTS

Half of the patients included in the follow-up urinated spontaneously, with post void residuals less than 120 mL and no need for catheterization. Four patients did not urinate spontaneously and needed continuos catheterization, whereas 8 patients had post void residuals of 150-200 mL and needed catheterization once a day or once a week. None of the patients had a stricture at the site of ureteroileal anastomosis.

CONCLUSION

We believe that our modification of the Kock's pouch makes the uretero-intestinal anastomosis much easier to perform; both ureters are inserted into the unsplit bowel end, thus preventing reflux; anastomosis with the urethra is performed under visual control; and direct anastomosis of widely opened distal end of the bowel reduces the possibility of scar stenosis.

Pathogenesis of pneumococcal pneumonia

Pneumococcal pneumonia is the most severe of the common community-acquired pulmonary infections. The recent release of the complete DNA sequence reveals the entire capability of the bacteria and the current challenge is to map gene products to the mechanics of disease. This process will reveal antibiotic targets and protein vaccine candidates crossing serotype boundaries. Choline is a major constituent of surfactant and it is also a required nutrient for the pneumococcus. It appears that choline incorporated into the cell wall can bind the bacteria to the receptor for platelet activating factor, the gateway to invasion. The choline also serves as an antenna to which multifunctional proteins dock, thereby decorating the bacterial surface. This set of 12 choline binding proteins is subject to phase variation of expression resulting in display of different combinations of proteins that adapt the bacteria to survival on the mucosa versus the blood stream. These changes affect protective antigens, adhesions, and lytic proteins tying together the major elements of pneumococcal physiology: natural DNA transformation, adherence and invasion of host cells, and autolysis. Taking these components and building an understanding of disease is challenging. Clearly, the toxin pneumolysin is a major mediator of cell damage in the lung. Inflammation is also incited by cell wall components. The signal transduction pathways that explain pneumococcal inflammation are more complex than those for gram-negative endotoxin.

Pneumolysin, a protein toxin of Streptococcus pneumoniae, induces nitric oxide production from macrophages

Nitric oxide (NO) production by inducible NO synthase (iNOS) during inflammation is an essential element of antimicrobial immunity but can also contribute to host-induced tissue damage. Under conditions of bacterial sepsis, large amounts of NO are produced, causing hypotension, a critical pathological feature of septic shock. In sepsis caused by gram-positive organisms, the bacterial factors contributing to host NO production are poorly characterized. We show that a soluble toxin of Streptococcus pneumoniae, pneumolysin (Pln), is a key component initiating NO production from macrophages. In contrast to wild-type bacteria, a mutant of S. pneumoniae lacking Pln failed to elicit NO production from murine macrophages. Purified recombinant Pln induced NO production at low concentrations and independently of exogenous gamma interferon (IFN-gamma) priming of RAW 264.7 macrophages. However, IFN-gamma was essential for Pln-induced NO production, since primary macrophages from mice lacking the IFN-gamma receptor or interferon regulatory factor 1, a transcription factor essential for iNOS expression, failed to produce NO when stimulated with Pln. In addition, Pln acts as an agonist of tumor necrosis factor alpha and interleukin 6 production in macrophages. The properties of Pln, previously identified as a pore-forming hemolysin, also include a role as a general inflammatory agonist.

Identification of two sources of carbon monoxide in comet Hale-Bopp

The composition of ices in comets may reflect that of the molecular cloud in which the Sun formed, or it may show evidence of chemical processing in the pre-planetary accretion disk around the proto-Sun. As carbon monoxide (CO) is ubiquitous in molecular clouds, its abundance with respect to water could help to determine the degree to which pre-cometary material was processed, although variations in CO abundance may also be influenced by the distance from the Sun at which comets formed. Observations have not hitherto provided an unambiguous measure of CO in the cometary ice (native CO). Evidence for an extended source of CO associated with comet Halley was provided by the Giotto spacecraft, but alternative interpretations exist. Here we report observations of comet Hale-Bopp which show that about half of the CO in the comet comes directly from ice stored in the nucleus. The abundance of this CO with respect to water (12 per cent) is smaller than in quiescent regions of molecular clouds, but is consistent with that measured in proto-stellar envelopes, suggesting that the ices underwent some processing before their inclusion into Hale-Bopp. The remaining CO arises in the coma, probably through thermal destruction of more complex molecules.

Emergence of vancomycin tolerance in Streptococcus pneumoniae

Streptococcus pneumoniae, the pneumococcus, is the most common cause of sepsis and meningitis. Multiple-antibiotic-resistant strains are widespread, and vancomycin is the antibiotic of last resort. Emergence of vancomycin resistance in this community-acquired bacterium would be catastrophic. Antibiotic tolerance, the ability of bacteria to survive but not grow in the presence of antibiotics, is a precursor phenotype to resistance. Here we show that loss of function of the VncS histidine kinase of a two-component sensor-regulator system in S. pneumoniae produced tolerance to vancomycin and other classes of antibiotic. Bacterial two-component systems monitor environmental parameters through a sensor histidine-kinase/phosphatase, which phosphorylates/dephosphorylates a response regulator that in turn mediates changes in gene expression. These results indicate that signal transduction is critical for the bactericidal activity of antibiotics. Experimental meningitis caused by the vncS mutant failed to respond to vancomycin. Clinical isolates tolerant to vancomycin were identified and DNA sequencing revealed nucleotide alterations in vncS. We conclude that broad antibiotic tolerance of S. pneumoniae has emerged in the community by a molecular mechanism that eliminates sensitivity to the current cornerstone of therapy, vancomycin.

Neuroprotection by a caspase inhibitor in acute bacterial meningitis

Half of the survivors of bacterial meningitis experience motor deficits, seizures, hearing loss or cognitive impairment, despite adequate bacterial killing by antibiotics. We demonstrate that the broad-spectrum caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl-ketone (z-VAD-fmk) prevented hippocampal neuronal cell death and white blood cell influx into the cerebrospinal fluid compartment in experimental pneumococcal meningitis. Hippocampal neuronal death was due to apoptosis derived from the inflammatory response in the cerebrospinal fluid. Apoptosis was induced in vitro in human neurons by inflamed cerebrospinal fluid and was blocked by z-VAD-fmk. As apoptosis drives neuronal loss in pneumococcal meningitis, caspase inhibitors might provide a new therapeutic option directed specifically at reducing brain damage.

Identification of a Streptococcus pneumoniae gene locus encoding proteins of an ABC phosphate transporter and a two-component regulatory system

The Escherichia coli Pst system belongs to the family of ABC transporters. It is part of a phosphate (PHO) regulon which is regulated by extracellular phosphate. Under conditions of phosphate limitation, the response regulator PhoB is phosphorylated by the histidine kinase PhoR and binds to promoters that share a consensus PHO box. Under conditions of phosphate excess, PhoR, Pst, and PhoU downregulate the PHO regulon. Screening of a library of pneumococcal mutants with defects in exported proteins revealed a putative two-component regulatory system, PnpR-PnpS, and a downstream ABC transporter, similar to the Pst system in E. coli including a gene encoding a PhoU protein. Similar to E. coli, mutagenesis of the ATP-binding cassette gene, pstB, resulted in decreased uptake of phosphate. The effects of the loss of the pneumococcal Pst system extended to decreased transformation and lysis. Withdrawal of phosphate led to transformation deficiency in the parent strain R6x but not to penicillin tolerance, suggesting that reduced bacterial death was independent of phosphate. None of these phenotypes was observed in the pneumococcal loss-of-function mutant phoU. By using a lacZ reporter construct, it was demonstrated that expression of the two-component regulatory system PnpR-PnpS was not influenced by different concentrations of phosphate. These results suggest a more complex role of the Pst system in pneumococcal physiology than in that of E. coli.

Penicillin tolerance genes of Streptococcus pneumoniae: the ABC-type manganese permease complex Psa

Downregulation of the major autolysin in Streptococcus pneumoniae leads to penicillin tolerance, a feature that is characterized by the ability to survive but not grow in the presence of antibiotic. Screening a library of mutants in pneumococcal surface proteins for the ability to survive 10x minimum inhibitory concentration (MIC) of penicillin revealed over 10 candidate tolerance genes. One such mutant contained an insertion in the known gene psaA, which is part of the psa locus. This locus encodes an ABC-type Mn permease complex. Sequence analysis of adjacent DNA extended the known genetic organization of the locus to include two new open reading frames (ORFs), psaB, which encodes an ATP-binding protein, and psaC, which encodes a hydrophobic transmembrane protein. Mutagenesis of psaB, psaC, psaA and downstream psaD resulted in penicillin tolerance. Defective adhesion and reduced transformation efficiency, as reported previously for a psaA- mutant, were phenotypes shared by psaB-, psaC- and psaD- knockout mutants. Western blot analysis demonstrated that the set of mutants expressed RecA, but none of them showed translation of the autolysin gene, which is located downstream of recA. The addition of manganese (Mn) failed to correct the abnormal physiology. These results suggest that this ABC-type Mn permease complex has a pleiotropic effect on pneumococcal physiology including adherence and autolysis. These are the first genes suggested as being involved in triggering autolysin. The results raise the possibility that loss of function of PsaA, by vaccine-induced antibody for instance, may promote penicillin tolerance.

Effect of long-term salmeterol treatment on exercise-induced asthma

BACKGROUND

With long-term administration of salmeterol, the extent of protection afforded by the drug against experimental precipitants of asthma such as methacholine and adenosine may decrease. Whether this effect extends to a clinically relevant stimulus such as exercise is unknown.

METHODS

We performed a random-order, double-blind, crossover trial in 20 patients with exercise-induced asthma. Each patient received inhaled salmeterol or placebo twice daily for a month, with a one-week washout period between treatments. The patients performed cycle ergometry while breathing frigid air 30 minutes after the morning dose and 9 hours later on the 1st, 14th, and 29th study days. The primary end point was the extent of the decrease in forced expiratory volume in 1 second (FEV1) 10 minutes after exertion.

RESULTS

With placebo, significant airway narrowing developed at all times (mean [+/-SE] decrease from base line in FEV1, 19+/-2 percent in the morning and 18+/-2 percent in the evening). The morning dose of salmeterol attenuated the degree of bronchoconstriction at all times (decrease in FEV1 on day 1, 5+/-2 percent; on day 14, 10+/-3 percent; and on day 29, 9+/-3 percent; P=0.10). Its ability to act throughout the day, however, decreased with long-term administration (decrease in FEV1 from morning to evening on day 1, 6+/-2 percent; on day 14, 15+/-3 percent; and on day 29, 14+/-3 percent; P=0.003).

CONCLUSIONS

Protection against exercise-induced asthma is maintained with long-term administration of salmeterol, but the length of time that the drug remains active after a single dose decreases.

In situ hybridization on blood smears for diagnosis of chicken anemia virus in broiler breeder flocks

Chicken anemia virus (CAV) infection was suspected in progeny from broiler breeder hens raised in a location that was geographically different from where most pullets were raised for one Georgia production company. These breeder pullets were raised in new or relatively new houses. Progeny from these pullets experienced a 10-fold increase in average daily mortality over progeny from flocks raised in established breeder houses. Lesions in the broilers included severe necrotizing dermatitis, pale bone marrow, and small thymus glands. Infection with CAV was confirmed in the breeders by enzyme-linked immunosorbent assay, indirect immunofluorescence, and in situ hybridization on peripheral blood smears. The in situ hybridization identified three broiler breeder flocks that were actively infected with CAV and were probably the source of infection in broiler flocks.

Seasonal abundance and distribution of mosquitoes at a rural waste tire site in Illinois

The species composition, abundance, and distribution of mosquito larvae in tires were determined on 3 dates at a relatively large rural tire dump (about 300,000 tires) in southeastern IL (Jasper County). Several observations at this site differed from those in previous reports about mosquitoes in tireyards, including 1) a relatively high percentage of tires positive for Aedes triseriatus larvae in an open-field area, 2) a greater abundance of Culex pipiens than Cx. restuans in late-season collections, 3) a seasonal change in the distribution of Aedes atropalpus larvae in tires from open field and edge of woods areas, and 4) the presence of Ae. albopictus as a major late-season species. Ae. albopictus adults were captured in sod-baited gravid traps along the edge of a wooded riparian area 200 m from the tire pile.

In situ hybridization for detection of chicken anaemia virus in peripheral blood smears

Blood smears, obtained from chickens known to be infected with or free from chicken anaemia virus (CAV), were tested to detect CAV DNA by in situ hybridization (ISH). A double-stranded, 1485 base-pair (bp) DNA probe was prepared employing polymerase chain reaction (PCR). The probe was labelled with digoxigenin or biotin by nick translation. In situ hybridization employing simple specimen preparation, using both digoxigenin- and biotin-labelled probes, provided a rapid and inexpensive method for diagnosis of CAV infection. Infection with CAV was detected by ISH prior to seroconversion by indirect immunofluorescence assay.

Trisomy 8 is a characteristic finding in pleuropulmonary blastoma

The cytogenetic findings in pleuropulmonary blastoma (PPB) have not been widely studied and reported and are of interest in view of the implications that PPB has for additional tumors in the patient and the patient's relatives. Using standard tumor cytogenetic methodology, we investigated three cases of PPB encountered in our institution over a 5-year period. Trisomy 8 was the only karyotypic abnormality in a localized type 2 PPB and was present with other abnormalities in another type 2 PPB and a massive type 3 PPB. Review of the literature yielded three additional karyotyped PPBs; all had trisomy 8 as part of the abnormalities detected. Trisomy 8 appears to be a characteristic of PPB and may be related to the development of PPB and related tumors.

[Classical and current aspects of purulent meningitis]

Even today acute purulent meningitis is a life-threatening disease requiring immediate diagnosis and therapy. Despite the availability of bactericidal antibiotics, the mortality has not changed within the last 20 years. A therapeutic approach interfering specifically with the pathogenesis of inflammation is necessary in order to prevent long-term neurological sequelae and death associated with bacterial meningitis. In this paper we discuss the present level of understanding of antibiotics and adjunctive therapy, especially with regard to the molecular pathophysiological events occurring during a CNS infection.

Antiretroviral monotherapy in early stage human immunodeficiency virus disease has no detectable effect on virus load in peripheral blood and lymph nodes

Initiation of antiretroviral monotherapy early in the course of infection with human immunodeficiency virus may result in a temporary slowing in the rate of disease progression; however, little is known about the virologic effects of early therapy. Virus load was measured in peripheral blood and lymph nodes from 16 antiretroviral-naive patients with a mean CD4 T lymphocyte count of 659 cells/microliter at baseline and after 8 weeks of either no treatment or zidovudine therapy. CD4 T lymphocyte counts and all virologic parameters examined remained unchanged regardless of zidovudine treatment status. Histopathology and virus distribution within lymph nodes remained constant between baseline and week 8 in each patient, indicating that the virologic and histologic parameters examined in a single lymph node are representative of a systemic process. Early antiretroviral monotherapy with zidovudine had no effect on virologic parameters in this group of patients with relatively high CD4 T lymphocyte counts and low measures of virus load at baseline.

An outcomes study of cochlear implants in deaf patients. Audiologic, economic, and quality-of-life changes

OBJECTIVES

To investigate and quantitate the changes in economic, emotional, and health-related quality of life after cochlear implantation.

SUBJECTS

Nine patients between the ages of 18 and 60 years who qualified for surgery.

METHODS

Patients underwent assessment using four socioeconomic indicator scales administered preoperatively, and at 6 months, 1 year, 2 years, 30 months, and 3 years postoperatively. All patients continued to use their cochlear implants during the 3-year follow-up period.

RESULTS

Uniform and systematic improvement in quality of life and psychologic well-being, and a steady increase in mean personal income for the group that underwent implantation, supporting the contention that cochlear implantation is a beneficial surgical procedure for profoundly deaf patients.