Talkers alter vowel production in response to real-time formant perturbation even when instructed not to compensate.

Talkers show sensitivity to a range of perturbations of auditory feedback (e.g., manipulation of vocal amplitude, fundamental frequency and formant frequency). Here, 50 subjects spoke a monosyllable ("head"), and the formants in their speech were shifted in real time using a custom signal processing system that provided feedback over headphones. First and second formants were altered so that the auditory feedback matched subjects' production of "had." Three different instructions were tested: (1) control, in which subjects were naive about the feedback manipulation, (2) ignore headphones, in which subjects were told that their voice might sound different and to ignore what they heard in the headphones, and (3) avoid compensation, in which subjects were informed in detail about the manipulation and were told not to compensate. Despite explicit instruction to ignore the feedback changes, subjects produced a robust compensation in all conditions. There were no differences in the magnitudes of the first or second formant changes between groups. In general, subjects altered their vowel formant values in a direction opposite to the perturbation, as if to cancel its effects. These results suggest that compensation in the face of formant perturbation is relatively automatic, and the response is not easily modified by conscious strategy.

Animal communication: big talkers and small talk.

Vocal tract resonances, known as formants, are important perceptual cues for the identification of human speech and animal calls. A recent study shows that monkeys can also use formants to determine the age and size of the monkey producing a call.

Comparison of a nested polymerase chain reaction--restriction fragment length polymorphism method, the PATH antigen detection method, and microscopy for the detection and identification of malaria parasites.

A nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, the PATH antigen detection method, and light microscopy were compared for their capacity to detect and identify Plasmodium species. One hundred and thirty-six blood specimens obtained from patients suspected of having malaria were examined by each of the three methods. Forty-four specimens were positive for malaria using microscopy as the "gold standard". The sensitivity for nested PCR was 100%, and the specificity was 98%. For the detection of Plasmodium falciparum, the antigen detection method had a sensitivity of 100% and a specificity of 97%. Species identification obtained using PCR-RFLP was identical or superior to light microscopy in 42 cases (96%). Although the nested PCR-RFLP method was more sensitive and specific, the rapid turnaround time and high sensitivity of the antigen detection method makes it a useful adjunct to standard microscopy.

Birds disperse ixodid (Acari: Ixodidae) and Borrelia burgdorferi-infected ticks in Canada.

A total of 152 ixodid ticks (Acari: Ixodidae) consisting of nine species was collected from 82 passerine birds (33 species) in 14 locations in Canada from 1996 to 2000. The Lyme disease spirochete Borrelia burgdorferi Johnson, Schmidt, Hyde, Steigerwaldt & Brenner was cultured from the nymph of a blacklegged tick, Ixodes scapularis Say, that had been removed from a common yellowthroat, Geothlypis trichas L., from Bon Portage Island, Nova Scotia. As a result of bird movement, a nymphal I. scapularis removed from a Swainson's thrush, Catharus ustulatus incanus (Godfrey), at Slave Lake, Alberta, during spring migration becomes the new, most western and northern record of this tick species in Canada. Amblyomma longirostre Koch, Amblyomma sabanerae Stoll, and Ixodes baergi Cooley & Kohls are reported for the first time in Canada. Similarly, Amblyomma americanum L., Arnblyomma maculatum Koch, and ixodes muris Bishopp & Smith are reported for the first time on birds in Canada. After removal of an I. muris gravid female from a song sparrow, Melospiza melodia Wilson, at St. Andrews, New Brunswick, eggs were laid, which developed into larvae, and this new tick-host record demonstrates that birds have the potential to start a new tick population. We conclude that passerine birds disperse several species of ixodid ticks in Canada, and during spring migration translocate ticks from the United States, and Central and South America, some of which are infected with B. burgdorferi.

Postpericardiotomy syndrome: no evidence for a viral etiology.

BACKGROUND: Postpericardiotomy syndrome has been considered a disorder induced by viral infection. This conclusion is based on serologic criterions, but these may be unreliable following either cardiopulmonary bypass or transfusion therapy. Previous studies have not verified the proposed etiology either by isolation of viruses, or by detection of their genome. We sought, therefore, to clarify the role, if any, of viruses in this syndrome. METHODS AND RESULTS: We studied prospectively 149 children aged from 6 months to 16 years who were undergoing open heart surgery. Blood samples were collected from all prior to operation, and again 7 to 10 days post-operatively, and 47 were sampled at the time of development of symptoms of pericardial involvement. Serums were analyzed for the presence of IgM and IgG antibodies to cytomegalovirus, herpes simplex virus, and Epstein-Barr virus. The polymerase chain reaction was used for amplification when assessing the genome of the enteroviruses. Cultures for viruses were established on samples of stool, urine, and throat swabs collected 7 days post-operatively, and at the time of postpericardial symptoms. Pericardial fluid obtained from 5 patients with the syndrome was cultured for viruses, and tested for enterovirus genome. On the basis of clinical and echocardiographic findings, 34 children were determined to have definite evidence of the syndrome, 13 were considered to have possible evidence, and the results from these patients were compared to those from patients with no pericardial symptoms, the latter being matched for age and transfusion status. We isolated viruses from one or more sites in five patients with definite evidence (16%), from one (9%) of those with possible evidence, and from seven (19%) of the controls. All serums and pericardial samples were negative for enterovirus genome. IgM antibodies were found in only 5 patients, three with symptoms of pericardial involvement and two without. Rates of seroconversion to IgG for the viruses were lower in the patients with symptoms of pericardial involvement compared to controls, but were strongly influenced by transfusion status. CONCLUSION: Our study has provided no evidence to support a viral etiology for the postpericardiotomy syndrome.

DNA-Based diagnostic approaches for identification of Burkholderia cepacia complex, Burkholderia vietnamiensis, Burkholderia multivorans, Burkholderia stabilis, and Burkholderia cepacia genomovars I and III.

Bacteria of the Burkholderia cepacia complex consist of five discrete genomic species, including genomovars I and III and three new species: Burkholderia multivorans (formerly genomovar II), Burkholderia stabilis (formerly genomovar IV), and Burkholderia vietnamiensis (formerly genomovar V). Strains of all five genomovars are capable of causing opportunistic human infection, and microbiological identification of these closely related species is difficult. The 16S rRNA gene (16S rDNA) and recA gene of these bacteria were examined in order to develop rapid tests for genomovar identification. Restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S rDNA revealed sequence polymorphisms capable of identifying B. multivorans and B. vietnamiensis but insufficient to discriminate strains of B. cepacia genomovars I and III and B. stabilis. RFLP analysis of PCR-amplified recA demonstrated sufficient nucleotide sequence variation to enable separation of strains of all five B. cepacia complex genomovars. Complete recA nucleotide sequences were obtained for 20 strains representative of the diversity of the B. cepacia complex. Construction of a recA phylogenetic tree identified six distinct clusters (recA groups): B. multivorans, B. vietnamiensis, B. stabilis, genomovar I, and the subdivision of genomovar III isolates into two recA groups, III-A and III-B. Alignment of recA sequences enabled the design of PCR primers for the specific detection of each of the six latter recA groups. The recA gene was found on the largest chromosome within the genome of B. cepacia complex strains and, in contrast to the findings of a previous study, only a single copy of the gene was present. In conclusion, analysis of the recA gene of the B. cepacia complex provides a rapid and robust nucleotide sequence-based approach to identify and classify this taxonomically complex group of opportunistic pathogens.

Epithelioid angiosarcoma arising in a surgically constructed arteriovenous fistula: a rare complication of chronic immunosuppression in the setting of renal transplantation.

Immunosuppression in the setting of solid organ transplantation is associated with the development of a variety of malignant tumors, most commonly squamous carcinomas and non-Hodgkin's lymphomas. Sarcomas, apart from Kaposi's sarcoma, are relatively infrequent. We recently encountered a 71-year-old man with chronic renal failure, treated by allograft kidney transplantation, who developed a high-grade epithelioid angiosarcoma at the site of a nonfunctioning arteriovenous fistula, previously constructed for hemodialysis. At diagnosis, the patient had numerous satellite nodules of angiosarcoma involving the distal skin, soft tissues, and bones. After a below-elbow amputation, there was a rapid local recurrence at the amputation stump. Currently, the patient is alive with numerous pulmonary metastases, 6 months after amputation. A literature review identified three recently reported identical cases of epithelioid angiosarcoma arising in nonfunctioning arteriovenous fistulae. All three patients had been treated by kidney transplantation for renal failure, suggesting a possible causal association between these events. We performed polymerase chain reaction for human herpes virus 8, the recently recognized herpes virus proposed as a major etiologic agent of Kaposi's sarcoma, and possibly some conventional angiosarcomas, but we failed to identify any viral DNA within the tumor.

Diagnosis of cytomegalovirus infection in HIV-infected patients with respiratory disease.

BACKGROUND: The role of the cytomegalovirus (CMV) in the respiratory morbidity and mortality of HIV-infected patients remains unclear. This is due in part to difficulties in making an accurate and rapid diagnosis. There has been a limited number of studies, often with few or no AIDS patients, on the use of DNA-DNA in situ hybridization (ISH) and polymerase chain reaction to diagnose CMV respiratory infection directly on bronchoalveolar fluid samples. OBJECTIVES: To compare the centrifugation culture (CC), ISH, and nested-primer polymerase chain reaction (npPCR) techniques (npPCR) techniques on bronchoalveolar fluid for the diagnosis of respiratory CMV infection. STUDY DESIGN: Samples were obtained prospectively from a group of 35 HIV-infected homosexual men evaluated for pneumonia at a university hospital. Sensitivity, specificity, and predictive values of the three techniques were measured and compared, using the conventional roller tube cell culture (CRTC) as the gold standard. RESULTS: Sensitivity, specificity, positive and negative predictive values were as follows: 86%, 86%, 90%, and 80% for the CC; 5%, 100%, 100%, and 41% for ISH; and 86%, 57%, 75%, and 73% for npPCR. Of the six false positive samples by npPCR, two were positive by CC (none by ISH). If the latter were considered true positives, the specificity and positive predictive values of npPCR would increase to 67% and 83%, respectively. CONCLUSIONS: CC appeared to be the best of the three techniques compared in this study for diagnosis of respiratory CMV infection in HIV-infected patients. The sensitivity and predictive values of DNA-DNA ISH were very poor. Results with npPCR were acceptable, and this technique may be considered in situations when rapid diagnosis of CMV infection is necessary.

Molecular analysis provides evidence for human to human transmission of Staphylococcus aureus endocarditis in non-drug abusers.

Two cases of invasive Staphylococcus aureus are reported in which human to human transmission resulted in primary bacteremia and endocarditis. The identity of the organism was confirmed by phage typing, antibiograms, coagulase gene polymorphisms and ribotyping. This is the first documented case of such transmission not involving an intravenous drug abuser.

Characterization of Neisseria meningitidis by polymerase chain reaction and restriction endonuclease digestion of the porA gene.

Subtype classification based on the use of monoclonal antibodies to the class 1 outer membrane protein combined with techniques such as multilocus enzyme electrophoresis remains the standard method of characterizing isolates during outbreaks of invasive meningococcal disease. We developed a rapid typing method based on the restriction fragment length polymorphisms (RFLPs) within the polymerase chain reaction (PCR) product of the porA gene, which encodes the class 1 outer membrane protein, reflecting genotypic rather than phenotypic variability between strains. Forty-five isolates of invasive Neisseria meningitidis obtained from October 1990 to April 1992 were studied after randomization and coding. Included among these were isolates from a local outbreak that resulted in a mass vaccination program. PCR amplification for each isolate was followed by restriction digestion with the following enzymes in the indicated sequence: HaeIII, RsaI, HinfI, HpaII, and AluI. Eighteen different patterns were demonstrated on the basis of RFLPs, whereas only seven groups were identified after standard subtyping. The most common isolate identified by serosubtyping was serogroup C, serotype 2a, subtype P1.2 (C:2a:P1.2) (38%). Thirteen (76%) of these group C isolates shared a common RFLP pattern after digestion with the five restriction enzymes. We were able to further differentiate strains of C:2a:P1.2 with electrophoretic type 5 from electrophoretic types 1, 9, and 15 that occurred during an apparent outbreak. We were also able to characterize 15 isolates (33%) which could not be subtyped with monoclonal antibodies. Our method offers a convenient alternative to standard subtyping procedures and is particularly useful in outbreak situations in which rapid characterization of N. meningitidis is essential so that rational public health policy regarding preventative measures can be formulated.

Molecular typing of Staphylococcus aureus on the basis of coagulase gene polymorphisms.

Staphylocoagulase, a major phenotypic determinant of Staphylococcus aureus, exists in multiple allelic forms, in part because of the existence of gene variants within the 3'-end coding region. This region contains a series of repeating 81-bp DNA sequences which differ both in the number of tandem repeats and the location of AluI restriction sites among different isolates. Utilizing this finding, we developed a novel typing method for S. aureus based on polymerase chain reaction amplification of the variable region of the coagulase gene followed by AluI restriction enzyme digestion and analysis of restriction fragment length polymorphism (RFLP). Among 30 S. aureus isolates studied initially, a total of 10 distinct RFLP patterns were observed. There was excellent correlation of the RFLP patterns with typing of these isolates by multilocus enzyme electrophoresis at 20 chromosomal loci. This coagulase RFLP method was used to analyze an additional 39 S. aureus isolates and successfully traced the source of an outbreak of methicillin-resistant S. aureus infections at a local hospital.

Comparison of in vitro antimicrobial susceptibilities of Mycobacterium avium-M. intracellulare strains from patients with acquired immunodeficiency syndrome (AIDS), patients without AIDS, and animal sources.

Difloxacin, A-56620, cefazolin, cefotaxime, ceftizoxime, cephapirin, SK&F 88070, and spectinomycin were used to compare the in vitro susceptibilities of Mycobacterium avium-M. intracellular isolates from patients with acquired immunodeficiency syndrome (AIDS), patients without AIDS, and diseased animals. Against the isolates from humans without AIDS, the quinolone compounds difloxacin and A-56620 were found to be the most effective, each inhibiting 50% of strains at a concentration of 2 micrograms/ml. The remaining antimicrobial agents had MICs for 50% of strains tested of at least 32 micrograms/ml. Statistically significant differences were observed in the antibiogram patterns among the M. avium-M. intracellulare strains from each of the three sources.

Isoelectric focusing of ten strains of Giardia duodenalis.

Ten strains of human- and animal-source Giardia duodenalis were evaluated using an isoelectric focusing technique. Banding patterns obtained from total cell proteins of trophozoites demonstrated both similarities and differences between strains. This confirms the heterogeneity of this morphological group of Giardia sp. demonstrated by others. Heterogeneity was demonstrated among the strains retrieved from human and animal hosts and from hosts within the same geographical region.

In vitro susceptibilities of Mycobacterium tuberculosis to 10 antimicrobial agents.

After preliminary in vitro screening of 10 antimicrobial agents against Mycobacterium tuberculosis, the MICs of the 6 most promising agents against 27 clinical isolates were determined by agar dilution. The two quinolone compounds tested (difloxacin and A-56620) were the most active, each inhibiting 50% of the strains at concentrations of 4 micrograms/ml. M. tuberculosis strains previously shown to be resistant to isoniazid, streptomycin, rifampin, or ethambutol were as susceptible to these quinolone compounds as susceptible strains.