Endothelin-1 activates ETA receptors to cause reflex scratching in BALB/c mice.

BACKGROUND AND PURPOSE: Endothelin-1 (ET-1) is present in murine and human skin and causes itch (pruritus) when injected in humans. This behavioural study examined the scratch reflex evoked by ET-1 in mice. EXPERIMENTAL APPROACH: An automated detector was used to determine whether ET-1 causes reflex scratching, the behavioural correlate of itching, in BALB/c mice. Selective agonists and antagonists were used to probe the ET receptor(s) involved. KEY RESULTS: ET-1 evoked dose-related reflex scratching lasting up to 20 min following intradermal injection (0.1-100 ng; 0.04-40 pmol). The ED(50) for ET-1 induced scratching was 2.1 ng and desensitization occurred with cumulative dosing. High doses of the ET(B) receptor agonist IRL1620 (10 microg; 5.5 nmol), also caused scratching (ED(50) 1.3 microg, 0.7 nmol). The ET(A) receptor antagonist BQ123 significantly reduced scratching evoked by ET-1 and IRL 1620, suggesting that both agonists caused scratching via an ET(A) receptor-dependent mechanism. The ET(B) receptor antagonist BQ788 significantly reduced scratching evoked by IRL1620 but had no effect on scratching evoked by ET-1. This indicated that activation of ET(B) receptors by high doses of ET(B) agonist, but not ET-1, can trigger scratching. CONCLUSION AND IMPLICATIONS: ET-1 is a potent endogenous activator of reflex scratching (itch). Mechanisms for ET-induced scratching are considered, including direct action of ET-1 on pruriceptive nerve endings and indirect actions via release of endogenous mediators such as histamine from mast cells. ET-1 and ET(A) receptors, possibly also ET(B) receptors, are potential targets for developing specific anti-pruritic drugs to treat pruritic skin disorders such as atopic dermatitis.

Distribution and sources of surfzone bacteria at Huntington Beach before and after disinfection on an ocean outfall-- a frequency-domain analysis.

Fecal indicator bacteria (FIB) were measured approximately 5 days a week in ankle-depth water at 19 surfzone stations along Huntington Beach and Newport Beach, California, from 1998 to the end of 2003. These sampling periods span the time before and after treated sewage effluent, discharged into the coastal ocean from the local outfall, was disinfected. Bacterial samples were also taken in the vicinity of the outfall during the pre- and post-disinfection periods. Our analysis of the results from both data sets suggest that land-based sources, rather than the local outfall, were the source of the FIB responsible for the frequent closures and postings of local beaches in the summers of 2001 and 2002. Because the annual cycle is the dominant frequency in the fecal and total coliform data sets at most sampling stations, we infer that sources associated with local runoff were responsible for the majority of coliform contamination along wide stretches of the beach. The dominant fortnightly cycle in enterococci at many surfzone sampling stations suggests that the source for these relatively frequent bacteria contamination events in summer is related to the wetting and draining of the land due to the large tidal excursions found during spring tides. Along the most frequently closed section of the beach at stations 3N-15N, the fortnightly cycle is dominant in all FIBs. The strikingly different spatial and spectral patterns found in coliform and in enterococci suggest the presence of different sources, at least for large sections of beach. The presence of a relatively large enterococci fortnightly cycle along the beaches near Newport Harbor indicates that contamination sources similar to those found off Huntington Beach are present, though not at high enough levels to close the Newport beaches.

Temporal and spatial variability of fecal indicator bacteria in the surf zone off Huntington Beach, CA.

Fecal indicator bacteria concentrations measured in the surf zone off Huntington Beach, CA from July 1998-December 2001 were analyzed with respect to their spatial patterns along 23 km of beach, and temporal variability on time scales from hourly to fortnightly. The majority of samples had bacterial concentrations less than, or equal to, the minimum detection limit, but a small percentage exceeded the California recreational water standards. Areas where coliform bacteria exceeded standards were more prevalent north of the Santa Ana River, whereas enterococci exceedances covered a broad area both north and south of the river. Higher concentrations of bacteria were associated with spring tides. No temporal correspondence was found between these bacterial events and either the timing of cold water pulses near shore due to internal tides, or the presence of southerly swell in the surface wave field. All three fecal indicator bacteria exhibited a diel cycle, but enterococci rebounded to high nighttime values almost as soon as the sun went down, whereas coliform levels were highest near the nighttime low tide, which was also the lower low tide.

Protein engineering of cytochromes P-450.

The cytochromes P-450 are an immensely important superfamily of heme-containing enzymes. They catalyze the monooxygenation of an enormous range of substrates. In bacteria, cytochromes P-450 are known to catalyze the hydroxylation of environmentally significant substrates such as camphor, phenolic compounds and many herbicides. In eukaryotes, these enzymes perform key roles in the synthesis and interconversion of steroids, while in mammals hepatic cytochromes P-450 are vital for the detoxification of many drugs. As such, the cytochromes P-450 are of considerable interest in medicine and biotechnology and are obvious targets for protein engineering. The purpose of this article is to illustrate the ways in which protein engineering has been used to investigate and modify the properties of cytochromes P-450. Illustrative examples include: the manipulation of substrate selectivity and regiospecificity, the alteration of membrane binding properties, and probing the route of electron transfer.

Case-control and vector studies of nosocomial acquisition of Pseudomonas cepacia in adult patients with cystic fibrosis.

OBJECTIVE: To examine factors associated with nosocomial acquisition of Pseudomonas cepacia in adult patients with cystic fibrosis. DESIGN: A retrospective case-control study of 5 patients with nosocomial acquisition of P cepacia versus 20 matched controls who failed to develop P cepacia infection. Selective handwashing, air sampling, and respiratory equipment sampling also were performed. SETTING: A university hospital providing tertiary care to 95 adult cystic fibrosis patients. PATIENTS: All patients are adults with known cystic fibrosis. Case definition required multiple negative sputum cultures for P cepacia prior to and during admission, with a positive sputum culture prior to discharge. Controls had negative sputum cultures for P cepacia prior to and throughout hospitalization. Controls were matched for age, gender, disease severity, and frequency of hospitalizations. RESULTS: Factors associated with increased risk of nosocomial acquisition of P cepacia included receiving humidifier or nebulized treatments (60% versus 5%, p = .016, odds ratio = 28.5, 95% confidence interval = 1.93 to 420.58). Factors without significance included ward, room, teaching versus nonteaching status, use of steroids, sharing a hospital room with another cystic fibrosis patient, antibiotic use, presence of portocath in situ, or socializing with another individual with cystic fibrosis known to be P cepacia-positive. Air sampling studies failed to demonstrate aerosolization of P cepacia by coughing cystic fibrosis patients over a 1-hour sampling time. Handwashing studies failed to demonstrate P cepacia on hands of cystic fibrosis patients, nurses, or physiotherapists (before or after physiotherapy). Reservoirs from nebulizers consistently grew P cepacia following therapy. CONCLUSIONS: Respiratory equipment may be an important source of nosocomial acquisition of P cepacia in adult cystic fibrosis patients.

Enzyme rate assay for 5-fluorocytosine.

Modification of an enzyme assay for 5-fluorocytosine, from an end point to a rate analysis, has resulted in a method that can provide results within 10 minutes. The modification also rendered the assay less susceptible to interference from bilirubin and triglycerides. This obviated the need to correct 5-fluorocytosine results for icteric or moderately lipemic samples. The performance history of the enzyme rate method has shown that it is reliable, quick, cost-effective, and suitable for use in a clinical laboratory.

Laboratory diagnosis of Chlamydia trachomatis using two immunodiagnostic methods.

Seven hundred seventy-seven endocervical specimens collected from symptomatic and asymptomatic women in a low-prevalence population were examined for the presence of Chlamydia trachomatis by both enzyme immunoassay (EIA) and by direct immunofluorescence assay (DFA). Overall, 49 (6.2%) of specimens had positive results, however, only 26 had positive results by both assays. Concordant positivity was significantly higher in specimens from symptomatic women not taking antibiotics as compared with all other groups. Test discordance was not influenced by order of specimen collection, number of days of delay before the specimen was processed by EIA, cervical cytologic results, amount of mucopurulence, or presence of a particular bacterial species in simultaneously collected cervical swabs. The EIA optical density (OD) reading appeared to discriminate between the different test result groups more reliably than the number of elementary bodies seen on the DFA slide. Specimens with an OD reading greater than 0.300 and less than 0.060 can be interpreted with assurance as positive and negative, respectively. Caution may be necessary with specimens with intermediate values.

Detection and identification of group B streptococci by use of pigment production.

Pigment production by group B streptococci (GBS) is a useful test for identification of the organisms. The test is positive in 99.5% of beta-haemolytic strains. No false-positives are noted. Non-haemolytic strains do not produce pigment. Islam's media less agar can be used as a one-step broth detector of GBS in mixed cultures. This may have application for the detection of GBS in women in labour. When used as an identification system for GBS, serum-starch broth can be further modified by reduction of serum and starch concentrations by at least 80%.

Inhibition of human neutrophil bacteriocidal activity by extracellular substance from slime-producing Staphylococcus epidermidis.

The role of slime produced by Staphylococcus epidermidis as a virulence factor has been investigated by preincubating human neutrophils in fractions of extracellular material from cultures of slime-producing and non-slime-producing S. epidermidis. Extracellular product (molecular weight greater than 300,000) from slime-producing S. epidermidis did not affect neutrophil phagocytosis but did produce a generalized loss of bacteriocidal activity which was not found with non-slime-producing S. epidermidis, or broth.

Epidemiology and clinical features associated with Blastocystis hominis infection.

A retrospective chart review was performed on 100 patients infected with Blastocystis hominis (Bh) and 50 randomly selected age and sex matched controls to examine the clinical and epidemiologic features associated with this organism. The finding of greater than 5 Bh per oil immersion field (1,000 X) was significantly associated with acute presentation of symptoms but was not predictive of the presence of gastrointestinal symptoms. Of patients infected with Bh, 57.5% had recently travelled to the tropics or had consumed untreated water as compared to 12.2% of controls (p less than 0.001). Forty Bh-positive patients were assessed on more than one occasion. No significant differences appeared to exist in the clinical responses of those treated with Metronidazole (14/18; 77.8%) or with dietary management (6/6; 100%) as compared with those not receiving treatment (13/16:81.2%). Patients tended to become less symptomatic with time and in the absence of specific treatment, and therefore treatment with Metronidazole may not be warranted in light of the natural history of Bh infection.

Different effects of an adenosine A1 analogue and ischemic preconditioning in isolated rabbit hearts.

BACKGROUND: Ischemic preconditioning reduces infarct size, but its effects on postischemic function are variable. Adenosine, which is thought to play a role in ischemic preconditioning, reduces both infarct size and postischemic dysfunction. The purpose of this study was to compare the cardioprotective effects of ischemic preconditioning and an adenosine A1 receptor agonist on recovery of function and infarct size in isolated rabbit hearts. METHODS: Krebs buffer-perfused hearts (at least 7 per group) were subjected to 60 minutes of global ischemia (37 degrees C) and 60 minutes of reperfusion. Ventricular function was assessed by measuring left ventricular developed pressure, and infarct size (percentage of the left ventricle) was determined by tetrazolium staining. RESULTS: Control hearts exhibited 34% +/- 6% infarct size and 56% +/- 4% recovery of preischemic left ventricular developed pressure. Ischemic preconditioning reduced infarct size to 13% +/- 1% but had no effect on recovery of function (65% +/- 5%). Hearts treated with the adenosine A1 agonist R-phenylisopropyladenosine for 5 minutes immediately before ischemia exhibited both reduced infarct size (10% +/- 2%) and enhanced postischemic recovery of left ventricular developed pressure (86% +/- 3%). Termination of the R-phenylisopropyladenosine treatment before ischemia eliminated its beneficial effects. The adenosine A1 receptor antagonist DPCPX blocked both of the effects of R-phenylisopropyladenosine but did not block ischemic preconditioning. CONCLUSIONS: These results demonstrate fundamental differences between the cardioprotective effects of adenosine A1 receptor activation and ischemic preconditioning.

The toilet as a transmission vector of vancomycin-resistant enterococci.

An elderly woman, admitted to the intensive care unit of a large university teaching hospital, was found to be colonized with vancomycin-resistant enterococci leading to the temporary closure of the unit. She had acquired the organism nosocomially, most likely from an environmental source, which had been contaminated when the toilet of a former patient, also colonized with vancomycin-resistant enterococci, had become blocked and overflowed throughout his and the adjoining room. This is the first report of a hospital toilet as the transmission vector for vancomycin-resistant enterococci.

Sharps utilization and disposal in British Columbia physicians' offices.

To determine the pattern of sharps utilization and disposal in British Columbia physicians' offices, a questionnaire was mailed to all office-based physicians belonging to the British Columbia Medical Association (BCMA). 1,167 physicians (25%) responded. Over 166,000 sharps per month were used by responding physicians, a per physician use of 95 per month. 67% of physicians used a specific plastic container for sharps disposal and 22% used a recycled container. 40% of the used containers were returned to a hospital or laboratory for disposal; 29% contracted out to a waste removal company, 18% placed with regular office garbage and 4% taken directly to a landfill or incinerator. Most offices (64%) had access to an autoclave or chemclave but few physicians (2%) sterilized their sharps waste prior to disposal. The recommended options for discarding used sharps containers in the office setting are: return to a hospital or laboratory for processing with their infectious waste; removal by a waste disposal service; or sterilization followed by disposal with regular garbage.

Arcanobacterium hemolyticum infection: confused with scarlet fever and diphtheria.

Arcanobacterium hemolyticum infections are a common cause of pharyngitis and rash in the 10- to 30-year-old age group. Despite its prevalence, many emergency and primary care physicians may not be aware of the pathogenic potential of this organism. We present a case that illustrates the distinctive clinical spectrum of A. hemolyticum infections that may be confused with drug allergy, group A streptococcal scarlet fever, diphtheria, and even toxic shock syndrome. Recognition of this syndrome will reduce misdiagnoses and facilitate appropriate treatment.

Aminoglycoside usage in a university teaching hospital.

A retrospective chart review examined the use of aminoglycosides in a university teaching hospital over a six month period. The study found 273 patients received 323 courses of aminoglycoside therapy. Significant issues addressed include the frequent use of aminoglycosides as surgical prophylactic agents, the prescribing of drugs to patients at increased risk of toxicity and the infrequency of appropriate monitoring. Nephrotoxicity was noted in 7% of patients.

Compliance with guidelines for monitoring aminoglycoside therapy.

One hundred and twenty-one patients receiving 140 courses of aminoglycoside-therapy (76% gentamicin and 24% tobramycin) were retrospectively studied to assess the monitoring practices for these drugs. Compliance with specific items of the monitoring guidelines ranged from 16 to 93%. An education program regarding aminoglycoside monitoring, particularly the use of serum aminoglycoside concentrations, is necessary in the study institutions.

Variability in urine culture reporting by Canadian microbiology laboratories.

OBJECTIVE: To determine the ability of microbiology laboratories to perform and to report urine colony counts. DESIGN: Clinical Microbiology Proficiency Testing program participants received stabilized simulated urine samples. Laboratories were asked to perform the appropriate test and report results. PARTICIPANTS: One hundred and nine clinical microbiology laboratories in British Columbia, Alberta and Nova Scotia. OUTCOME MEASURES: Consistency of reporting was compared with standards for reporting results as described in the SI Manual in Health Care, 2nd edition. RESULTS: The study demonstrated a wide variation in units used for the reporting of results. Ninety-five (87.2%) laboratories reported quantitative urine results in a variety of unit styles. Of those laboratories providing results with units, 80 (84.2%) used one of 10 variations of SI reporting styles. Fifteen (16.8%) laboratories reported metric units in three different styles. Eleven (10.0%) laboratories reported semiquantitative values without stating units. The remaining three (2.8%) did not respond to the survey. CONCLUSIONS: Many clinical microbiology laboratories have not adopted a consistent form of SI units for reporting quantitative urine culture results. This lack of consistency could potentially lead to interpretation confusion.

External quality assessment of transporting infectious substances in Canada.

OBJECTIVE: To determine the degree of compliance with Transport Canada's Transportation of Dangerous Goods Regulations for transporting infectious substances in Canada. DESIGN: A three-phase study including observation of packages arriving at the British Columbia Centre for Disease Control (BCCDC) provincial laboratory; observation of requested samples of either an Escherichia coli culture or serum, not human immunodeficiency virus (HIV) or HbsAg positive, from laboratories; and a questionnaire concerning training and certification of packers in laboratories. RESULTS: During phase 1, 500 packages arriving at the BCCDC provincial laboratory were assessed. All arrived intact, with 384 (76.8%) in a firm outer package. Only 178 (35.6%) contained absorbent material. Six samples were known to contain human immunodefiency virus or hepatitis B; all were appropriately packaged. Of the remainder, 11 (2.2%) were considered overpackaged, 192 (38.4%) acceptably packaged and 191 (38.2%) inadequately packaged. In phase 2, 138 requested packages were assessed. All arrived intact, 132 (95.7%) in a firm outer package. Ninety-six (69.6%) contained absorbent material. Only six (4.3%) were considered inadequately packaged. In phase 3, 171 laboratories responded to a questionnaire. Fifty-nine were from small laboratories, 53 from intermediate laboratories and 23 from large laboratories. Most laboratories (55.4%) relied on in-house resources to train packers. Only 26 (15.3%) facilities had no certified packers, and 60.8% noted they had a formal copy of the regulations available in the laboratory. Laboratory characteristics associated with the likelihood of overpackaging included number of technologists (χ(2)=5.72; P=0.058), number of samples processed by laboratories (χ(2)=8.46; P=0.015) and being a private laboratory as opposed to being a hospital laboratory (Fisher Exact two-tailed 0.040). CONCLUSIONS: Canadian laboratories tend to package safely and within the acceptable range of regulation, although not within the precision of regulation. Most laboratories have trained and certified packers. The most common error is the use of outer packaging that is not firm. Larger laboratories tend to overpackage resulting in increased costs.

Spontaneous Yersinia enterocolitica septicemia in a patient with iron overload.

Yersinia enterocolitica septicemia is described in a patient with transfusional iron overload and a myelodysplastic syndrome. The organism was biotype 1 serotype 0:5,27 and carried a virulence-encoding plasmid. It was calcium-dependent, autoagglutinating and virulent to orally challenged mice, but not resistant to the bacteriocidal activity of serum. The patient had depressed neutrophil chemotaxis and bactericidal activity. In this case, both host and microbial factors were present to select out this particular bacteremic disease. Patients with iron overload states should be recognized as compromised hosts and potentially susceptible to spontaneous sepsis due to Y enterocolitica.