Misidentification of clinical yeast isolates by using the updated Vitek Yeast Biochemical Card.

The Vitek Yeast Biochemical Card (YBC) is widely used as a rapid identification (RI) (within 48 h) system for clinical yeast isolates. We compared the RI results obtained by the YBC technique with matched results obtained with the API 20C system. The RI of germ tube-negative yeasts isolated from 222 clinical specimens was performed with the YBC system, and the results were compared with those of standard identifications obtained by using the API 20C system and morphology, with additional biochemical reactions performed as required. Commonly isolated yeasts (Candida albicans [n = 29], Candida tropicalis [n = 40], Torulopsis [Candida] glabrata [n = 28], Candida parapsilosis [n = 12], and Cryptococcus neoformans [n = 14]) were generally well identified (115 of 123 [93%] identified correctly, with only C. albicans, C. tropicalis, and C. neoformans mis- or unidentified more than once). The RI of less commonly isolated yeasts included in the YBC database, however, was less successful (54 of 99 [55%] correct). The YBC card failed to identify 42% (10 of 24) of Candida krusei isolates, 80% (4 of 5) of Candida lambica isolates, 88% (7 of 8) of Trichosporon beigelii isolates, and 83% (10 of 12) of Cryptococcus isolates (non-C. neoformans species). For most identification failures (79%; 42 of 53) there was no identification by the end of 48 h; the other identification failures (21%; 11 of 53) gave definite but incorrect identifications. Of eight rare clinical yeast isolates not included in the Vitek database, six were correctly, not identified, while two (25%) were falsely assigned a definite RI (one Hansenula fabianii isolate was identified as Rhodotorula glutinis, and one Hansenula isolate [non-Hansenula anomala] was identified as Hansenula anomala). While the Vitek YBC rapidly and adequately identifies common yeast isolates, it fails in the RI of more unusual organisms.     

Direct isolation of Candida spp. from blood cultures on the chromogenic medium CHROMagar Candida

CHROMagar Candida is a selective and differential chromogenic medium that has been shown to be useful for identification of Candida albicans, Candida krusei, Candida tropicalis, and perhaps Candida glabrata. Colony morphology and color have been well defined when CHROMagar Candida has been used to isolate yeast directly from clinical specimens, including stool, urine, respiratory, vaginal, oropharyngeal, and esophageal sources. Direct isolation of yeast on CHROMagar Candida from blood cultures has not been evaluated. We evaluated whether the color and colony characteristics produced by Candida spp. on CHROMagar Candida were altered when yeasts were isolated directly from blood cultures. Fifty clinical isolates of Candida were inoculated into aerobic and anaerobic blood culture bottles and incubated at 35 degrees C in an automated blood culture system. When growth was detected, an aliquot was removed and plated onto CHROMagar Candida. As a control, CHROMagar Candida plates were inoculated with the same isolate of yeast grown on Sabouraud dextrose agar simultaneously. No significant difference was detected in color or colony morphology between the blood and control isolates in any of the tested organisms. All C. albicans (n = 12), C. tropicalis (n = 12), C. glabrata (n = 9), and C. krusei (n = 5) isolates exhibited the expected species-specific colony characteristics and color, whether isolated directly from blood or from control cultures. CHROMagar Candida can be reliably used for direct isolation of yeast from blood cultures. Direct isolation could allow mycology laboratories to more rapidly identify Candida spp., enable clinicians to more quickly make antifungal agent selections, and potentially decrease patient morbidity and mortality.     

DNA adducts formed by ring-oxidation of the carcinogen 2-naphthylamine with prostaglandin H synthase in vitro and in the dog urothelium in vivo

The presence of relatively high levels of prostaglandin H synthase(PHS) in the dog urinary bladder and its ability to mediatethe activation of carcinogenic arylamines to DNA-bound productsin vitro suggests the involvement of this enzyme in arylamine-inducedbladder carcinogenesis. Since the PHS-dependent metabolism of2-naphthylamine (2-NA) had been shown to yield both ring- andN-oxidation products in vitro, we compared the reactivity of³H-labeled N-hydroxy-2-naphthylamine (N-OH-2-NA), 2-nitrosonaphthalene,and 2-amino-1-naphthol (2-AN) toward DNA and protein. In thePHS-incubation system, all three derivatives bound at high levelsto protein, but only N-OH-2-NA and 2-AN bound appreciably toDNA. Though ring-oxidation has usually been considered a detoxificationpathway, the covalent binding of [³H]2-AN to DNA was found tooccur readily under aerobic conditions and was enhanced at acidicpH. At pH 5 in air, the reactivity of [³H]2-AN with nucleicacids and protein was in the order: serum albumin > tRNA> poly G > poly C > DNA > poly A > rRNA >poly U. Enzymatic hydrolysis of DNA reacted with [³H]2-AN andsubsequent analysis by h.p.l.c. indicated the presence of severalcarcinogen-nucleoside adducts. The major product was characterizedas N⁴-(deoxyguanosin-N²-yl)-2-amino-1,4-naphthoquinoneimine;and two minor products were tentatively identified as N⁴-(deoxyadenosin-N⁶-yl)-2-amino-1,4-naphthoquinoneimineand a deoxyguanosin-N²-yl adduct of a naphthoquinoneimine dimer.These adducts accounted for 60% of the total DNA binding obtainedby incubation of [³H]2-NA with PHS in vitro and for 20% of the[³H]2-NA bound to dog urothelial DNA in vivo. The remainingadducts were identical to those previously reported as productsof the reaction of N-OH-2-NA with DNA. These results suggestthat a minor proportion of the DNA adducts found in vivo maybe formed by PHS-activation of 2-NA in the target tissue. Furthermore,the reactivity of 2-AN with cellular nucleophiles, presumablythrough formation of 2-imino-1-naphthoquinone or a protonated4-naphthocarbenium ion, indicates that ring-oxidation productsof arylamines and of other carcinogenic aryl compounds shouldbe evaluated as proximate carcinogenic metabolites.     

Characterization of and human serologic response to proteins in Helicobacter pylori broth culture supernatants with vacuolizing cytotoxin activity.

Helicobacter pylori infection is strongly associated with histologic gastritis and peptic ulcer disease. Broth culture supernatants from a subset of H. pylori strains induce vacuolization in cultured cells, a phenomenon that has been attributed to cytotoxin activity. Concentrated culture supernatants from 15 of 28 (53.6%) H. pylori strains tested induced vacuolization in HeLa cells in titers ranging from 1:10 to 1:180. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining of supernatants from these 28 strains and 2 control strains demonstrated an 82-kilodalton (kDa) protein band in 3 of 16 supernatants with vacuolizing activity, but in none of 14 supernatants without vacuolizing activity. By immunoblotting with human sera, a 128-kDa band was recognized in all 16 supernatants with vacuolizing activity, compared with 9 of 14 (64%) supernatants without vacuolizing activity (P = 0.014). Serologic recognition of the 128-kDa band in H. pylori culture supernatants was more prevalent among persons infected with vacuolizing H. pylori strains than among persons infected with nonvacuolizing strains, but the difference was not statistically significant (80 versus 45%; P = 0.079); human serologic recognition of the 82-kDa band was less common. The 128-kDa band was recognized by 100% of 31 serum samples from H. pylori-infected patients with duodenal ulcer disease, compared with 60.8% of 74 serum samples from H. pylori-infected persons without peptic ulcer disease (P = 0.0001). These data indicate that antigenic 128- and 82-kDa proteins are present in H. pylori broth culture supernatants with vacuolizing activity and that serologic responses to the 128-kDa protein are more prevalent among H. pylori-infected persons with duodenal ulceration than among infected persons without peptic ulceration.     

Group interventions and the limits of behavioral medicine

A wide range of interventions has been devised to address health hazards in the social and physical environment. The authors propose a 2-dimensional matrix to organize these interventions. The timing of interventions is divided into 4 stages: preventing exposure to hazard (proactive primary prevention), preventing symptoms from appearing (reactive primary prevention), preventing early symptoms from becoming chronic or leading to disease (secondary prevention), and managing the disease (tertiary prevention). The level at which the intervention is targeted is divided into 2 categories: micro (individual or family) and macro (more aggregate social level). Large-scale interventions such as media campaigns can target either individual health behaviors (microlevel) or the environment (macrolevel). This typology is illustrated with interventions designed to prevent or ameliorate the health consequences of adverse employment changes such as job loss. The analysis concludes that behavioral medicine and public health approaches are differentially suited to different intervention types.     

Differential effects of calcium channel antagonists (ω-conotoxin GVIA,nifedipine, verapamil) on the electrically-evoked release of [3H]acetylcholine from the myenteric plexus,phrenic nerve and neocortex of rats

Summary Electrically-evoked release of [³H]acetylcholine from autonomic neurons (myenteric plexus), motoneurons (phrenic nerve) and the central nevous system (neocortex) was investigated in the presence and absence of the calcium channel antagonists -conotoxin GVIA, nifedipine and verapamil, whereby the same species (rat) was used in all experiments. Release of [³H]acetylcholine was measured after incubation of the tissue with [³H]choline.-Conotoxin GVIA markedly reduced (70%) the evoked release of [³H]acetylcholine from the myenteric plexus of the small intestine (IC₅₀: 0.7 nmol/l) with a similar potency at 3 and 10 Hz stimulation. An increase in the extracellular calcium concentration attenuated the inhibitory effect of -conotoxin GVIA. Release of [³H]acetylcholine from the rat neocortex was also inhibited (90%) by -conotoxin GVIA, but the potency was 19-fold lower (IC₅₀: 13 nmol/l). However, the release of [³H]acetylcholine from the phrenic nerve was not reduced by -conotoxin GVIA (100 nmol/l) at 1.8 mmol/l calcium (normal concentration), whereas -conotoxin GVIA inhibited evoked [³H]acetylcholine release by 47% at 0.9 mmol/l calcium. Neither nifedipine (0.1 and 1 mol/l) nor verapamil (0.1, 1 and 10 mol/l) modified the evoked release of [3H]acetylcholine from the myenteric plexus and the phrenic nerve.Acetylcholine release from different neurons appears to be regulated by different types of calcium channels. N-type channels play the dominant role in regulating acetylcholine release from both the myenteric plexus and the neocortex, whereas acetylcholine release from motor nerves is regulated by calcium channel(s) not yet characterized. Send offprint requests to I. Wessler at the above address     

Brain activity and language assessment using event-related potentials: development of a clinical protocol

To test the validity of a new computerized task to assess children's receptive vocabulary, event-related potentials (ERPs) were recorded from 56 typically developing children ranging in age from 5 to 12 years. This ERP-computerized vocabulary task does not require a child to give a verbal or motor (i.e. pointing) response. Single pictures, from an existing standardized test of receptive vocabulary, were presented on a computer screen and simultaneously named either correctly (congruent) or incorrectly (incongruent) via a computer. As predicted, the N400 amplitude was found to be significantly higher to the incongruent picture-word pair (i.e. the child knew it was an incorrect pairing) than to the congruent picture-word pair (i.e. the child knew it was a correct pairing). This effect was found for each of the four age groups (5 to 6 years, 7 to 8 years, 9 to 10 years, 11 to 12 years). This task accurately estimated current receptive vocabulary in typically developing children. Although still in the development stage, it may eventually serve as an adjunct to a thorough neurological and neurodevelopmental assessment of some children presenting with moderate to severe cerebral palsy.     

Rizatriptan: a review of its efficacy in the management of migraine.

Rizatriptan is an orally active serotonin 5-HT1 receptor agonist selective for the 5-HT(1B/1D) subtypes. The efficacy of oral rizatriptan (5 or 10 mg) has been demonstrated in large (n = 309 to 1746) well designed comparative trials with placebo and oral sumatriptan. Two hours postdose, rizatriptan 5 or 10 mg was more effective than placebo at producing pain relief or a pain free status, relieving migraine-associated symptoms and normalising functional ability. In general, rizatriptan 10 mg appeared to be more effective than rizatriptan 5 mg. However, recurrence rates with rizatriptan 5 and 10 mg appeared to be similar to those with placebo. Patients were significantly more likely to achieve pain relief within 2 hours after receiving rizatriptan 5 mg than sumatriptan 25 mg and after rizatriptan 10 mg than sumatriptan 50 mg. This was also observed with rizatriptan 10 mg compared with sumatriptan 100 mg according to an age-adjusted and a prespecified per-protocol analysis. In general, rizatriptan was better than sumatriptan at relieving migraine-associated symptoms, particularly nausea, and in normalising functional ability depending on which doses were compared. The incidence of headache recurrence, time to onset of recurrence and the need for escape medication in nonresponders appeared to be similar between rizatriptan and sumatriptan. Over the 24 hours after the dose, rizatriptan 10 mg improved the quality of life of patients with migraine compared with placebo. Rizatriptan 10 mg also significantly improved work function compared with placebo and with sumatriptan 50 mg. Rizatriptan appears to be well tolerated with most adverse events being mild and transient. The most commonly experienced events included general digestive complaints, general neurological complaints, dizziness, somnolence, asthenia/fatigue and pain and pressure sensations. In clinical trials, the overall incidence of adverse events with rizatriptan 5 or 10 mg was similar to that with sumatriptan 25 or 50 mg but lower than that with sumatriptan 100 mg. Chest pain was reported by 1 to 3% of rizatriptan recipients and by 3 to 6% of patients receiving sumatriptan (25, 50 or 100 mg); clinically significant effects on ECG parameters, heart rate or blood pressure were not observed with rizatriptan. Conclusions: Rizatriptan produces pain relief and a pain free status, relieves associated symptoms of migraine, normalises functional ability and improves patient quality of life. Rizatriptan 10 mg appears to be more effective than rizatriptan 5 mg. In comparison with oral sumatriptan, rizatriptan may provide better relief from pain and nausea, with some evidence of a faster onset of action. Thus, rizatriptan 5 or 10 mg is likely to establish a place as an effective and well tolerated agent for the management of acute migraine.     

Sibrafiban

Sibrafiban is the orally administered, nonpeptide, double-prodrug of Ro 44-3888 which is a selective glycoprotein IIb/IIIa receptor antagonist. It is currently undergoing clinical trials for secondary prevention of cardiac events in patients stabilised after acute coronary syndromes. In a phase II dose-finding study (TIMI 12) in patients stabilised after a myocardial infarction (MI) or an episode of unstable angina, there was a dose-dependent inhibition of platelet aggregation which correlated closely with the plasma concentration of the total active drug. An ongoing phase III study (SYMPHONY) compares the effects of sibrafiban on cardiac events with that of aspirin in patients stabilised after a Q wave MI or an episode of unstable angina. This large trial uses twice daily dosage regimens to produce the plasma concentrations which were associated with less bleeding in the earlier dose-ranging trial. A long term (minimum duration 12 months) phase III study (2nd SYMPHONY) is under way to compare the effects of sibrafiban on cardiac events with those of aspirin in patients stabilised after an MI or an episode of unstable angina. The most common adverse events associated with sibrafiban include bleeding, with minor haemorrhages occurring more often than with aspirin.