Use of the BD PHOENIX Automated Microbiology System for direct identification and susceptibility testing of gram-negative rods from positive blood cultures in a three-phase trial

The present study describes the use of the automated BACTEC 9240 blood culture system, the Serum Separator Tube (SST), and the BD PHOENIX Automated Microbiology System in combination for the direct identification and antimicrobial susceptibility testing (AST) of gram-negative rods (GNRs) from positive blood cultures (BCs) without subculture. The study was conducted in three phases: (i) the recovery yield of Escherichia coli ATCC 25922 was determined with the SST between 0 and 8 h after spiked BC bottles turned positive; (ii) the identifications and susceptibility testing results obtained with the PHOENIX system for nine American Type Culture Collection strains of GNRs processed by the SST procedure and for colonies from agar medium were compared; and (iii) the procedure with the BACTEC system, SSTs, and the PHOENIX system was applied to positive cultures of blood from 309 patients during a 3-month period. The SST procedure with E. coli yielded sufficient numbers of cells to perform direct inoculation at any time between 0 and 8 h after a BC bottle turned positive. By using the identities obtained from pure cultures with the PHOENIX system and other biochemical identification systems as reference methods, the agreement between the reference methods and the PHOENIX system tested directly by using cultures of blood from patients was 92.9%. The 7.1% discrepant results were due to 6.5% incorrect identifications with the PHOENIX system with BC samples and 0.6% incorrect identifications with the PHOENIX system with samples from agar cultures. By AST the overall categorical accuracy was 99.0%, with 0.1% very major errors, 0.1% major errors, and 0.8% minor errors. In conclusion, use of the combination of the BACTEC system, SSTs, and the PHOENIX system has the potential to allow the agar isolation step to be skipped and the procedures for rapid direct identification and susceptibility testing of GNRs from positive BCs to be improved both in hospital-based and in central non-hospital-based laboratories.     

Corynebacterium riegelii sp. nov., an Unusual Species Isolated from Female Patients with Urinary Tract Infections

Four strains of an unknown coryneform bacterium were isolated in pure culture from females with urinary tract infections. Strong urease activity and the ability to slowly ferment maltose but not glucose were the most significant phenotypic features of this catalase-positive, nonmotile, nonlipophilic, rod-shaped bacterium which served to distinguish it from all other presently defined coryneform bacteria. Chemotaxonomic investigations demonstrated that the unknown bacterium belonged to the genus Corynebacterium. Comparative 16S rRNA gene sequence analysis revealed that the isolates were genealogically identical and represented a new subline within the genus Corynebacterium, for which the designation Corynebacterium riegelii sp. nov. is proposed. The type strain of Corynebacterium riegelii is CCUG 38180 (DSM 44326, CIP 105310).     

Genetic and functional characterization of an antiserum to the lipid A-specific triggering receptor on murine B lymphocytes.

The inheritance of responsiveness to lipopolysaccharide (LPS), and of a marker recognized in LPS-reactive cells by a heterologous antiserum, was studied in crosses between C3H/HeJ (nonresponder) and C3H/Tif (high responder) mice. F1 hybrid mice show codominant expression of these traits: (a) LPS-reactive cells are only hlaf as frequent in the hybrids as in the high responder parent; (b) the serologically defined marker is expressed in half as many cells in the hybrids as in the high responder parent. In backcross generations, both LPS responsiveness and this serological marker segregated into high, intermediate, and nonresponders. LPS or free lipid A, but not two other B cell mitogens (lipoprotein, and purified protein derivative of tuberculin), compete with the antiserum for binding to the B cell surface membrane, and are capable of completely inhibiting such binding without interfering with the binding of a-ti-Ig antibodies or complexes to Fc receptors. The addition of an IgG fraction of the antiserum to B cell cultures results in exponetial growth of the cells and in maturation to antibody secretion. This mitogenic activity is dose-depedent and absorbable on spleen cells from LPS high responder mice. Taken together, these observations suggest that this antiserum contains antibodies to the lipid A-specific triggering receptor on B lymphocytes.     

High and low frequency transcutaneous electrical nerve stimulation inhibits nociceptive responses induced by CO2 laser stimulation in humans

The aim of the study was to evaluate the effects of transcutaneous electric nerve stimulation (TENS) on CO(2) laser evoked potentials (LEPs) in 16 normal subjects. The volar side of the forearm was stimulated by 10 Hz TENS in eight subjects and by 100 Hz TENS in the remainder; the skin of the forearm was stimulated by CO(2) laser and the LEPs were recorded in basal conditions and soon after and 15 min after TENS. Both low and high frequency TENS significantly reduced the subjective rating of heat stimuli and the LEPs amplitude, although high frequency TENS appeared more efficacious. TENS seemed to exert a mild inhibition of the perception and processing of pain induced by laser Adelta fibres activation; the implications of these effects in the clinical employment of TENS remain to be clarified.     

Binocular interactions in the cat's dorsal lateral geniculate nucleus. I. Spatial-frequency analysis of responses of X, Y, and W cells to nondominant-eye stimulation

1. X, Y, and W cells in the A and C layers of the cat's dorsal lateral geniculate nucleus (LGN) were tested for responses to stimulation of the nondominant eye. The main purpose was to determine the incidence of nondominant-eye excitation and inhibition among different classes of cells and to examine the spatial-frequency tuning of responses to the nondominant eye. 2. Of 198 cells that were tested with drifting sine-wave gratings presented to the nondominant eye, 109 (55%) showed statistically significant responses. Four types of responses were observed: an increase in the mean discharge rate (F0 excitation), a decrease in the mean discharge rate (F0 inhibition), an increased modulation at the fundamental frequency of the grating (F1 excitation), and a decreased modulation at the fundamental frequency of the grating (F1 inhibition). Overall, 29% of the cells responded with inhibition, 24% responded with excitation, and 2% showed both excitation and inhibition, depending upon the spatial frequency and/or the harmonic response component. The relative incidence of excitation and inhibition was similar for X, Y, and W cells, for cells with on-center and off-center receptive fields, for cells with different receptive-field eccentricities, and for cells in each LGN layer. In addition, within layers A and A1, responses were similar for cells at different distances from the laminar borders. 3. Spatial-frequency response functions indicated that cells could have band-pass or low-pass spatial-frequency tuning through the nondominant eye. Band-pass cells tended to be narrowly tuned (less than or equal to 1 octave), and low-pass cells responded to a broader range of spatial frequencies. These properties were similar for X, Y, and W cells. Spatial resolution tended to be low (less than or equal to 0.8 c/deg for most cells), although a few cells responded to the highest spatial frequency tested (5.4 c/deg). Likewise, optimal spatial frequency was low (less than or equal to 0.2 c/deg) for most cells. These properties were similar for X and Y cells, and there was a weak tendency for X and Y cells to have higher optimal spatial frequencies and spatial resolutions than W cells. 4. In terms of absolute change in activity, responses to drifting gratings were weak. However, cells that were inhibited generally showed 20-60% decreases in activity to the optimal spatial frequency, and cells that were excited generally showed 40-100% increases. Response amplitudes were similar for X, Y, and W cells.(ABSTRACT TRUNCATED AT 400 WORDS)     

Relative contributions of burst and tonic responses to the receptive field properties of lateral geniculate neurons in the cat.

1. In an anesthetized, paralyzed in vivo preparation, we recorded extracellular responses of 61 geniculate neurons (2 W, 25 X, 33 Y, and 1 mixed) to drifting sine-wave gratings of various spatial frequency, temporal frequency, and contrast. Our goal was to study the differential contributions to these visual responses of bursting caused by voltage dependent, low-threshold (LT) Ca2+ spikes and of purely tonic responses unrelated to LT spikes. Cells responding with LT spikes are said to be in the burst firing mode and those responding in a purely tonic fashion to be in the relay or tonic firing mode. We separated the total visual response into LT burst and tonic components by use of the empirical criteria set forth in our intracellular study described in the previous paper (Lu et al. 1992). A response component was considered to be an LT burst if its action potentials displayed interspike intervals < or = 4 ms and if the first spike in the burst episode occurred after a silent period of > or = 100 ms (or > or = 50 ms when the neuron responds to visual stimuli at temporal rates > or = 8 Hz). All other activity is considered to be part of the tonic response. 2. In addition to LT bursts, we recognized another type of burst response, the high-threshold (HT) burst. These also have clusters of action potentials with interspike intervals < or = 4 ms. However, HT bursts, unlike LT bursts, lack a preburst silent period. HT bursts are part of the tonic response component and merely reflect the gradual decrease in interspike intervals that occurs as the cell becomes more depolarized and thus more responsive. Thus interspike interval is a necessary but insufficient criterion to identify LT bursts. 3. Visually evoked LT bursts were recorded among W, X, and Y cells. When evoked, LT bursts occurred in phase with drifting sine-wave grating stimuli at a rate never exceeding one per stimulus cycle. In response to individual cycles of the visual stimulus, LT bursts could comprise the total response, a tonic component could comprise the total response, or an LT burst and tonic component could be mixed. When a stimulus evoked a mixture of LT bursts and tonic response components, LT bursts were always the first response. 4. Of the 61 cells tested with grating stimuli, 47 exhibited LT bursts and 14 did not. Those that did exhibited varying amounts of burstiness.(ABSTRACT TRUNCATED AT 400 WORDS)     

Identical allelic losses in mature teratoma and other histologic components of malignant mixed germ cell tumors of the testis

Teratomas of the testis in post-pubertal patients are histologically diverse tumors that often coexist with other types of germ cell tumors. Using laser capture microdissection and loss of heterozygosity analysis, we investigated the clonality of mature teratoma and its relationship to other components of malignant mixed germ cell tumors to gain potential insight into the histogenetic relationship of teratoma with other germ cell tumor components. All 16 patients had mature teratoma as one component of their mixed germ cell tumors. The other histological subtypes included immature teratoma, seminoma, embryonal carcinoma, yolk sac tumor, and choriocarcinoma. Laser-assisted microdissection was performed on the formalin-fixed, paraffin-embedded tissue. Polymerase chain reaction was used to amplify genomic DNA at specific loci on chromosome 1p36.2 (D1S508), 2q22-32 (D2S156), 9p21-22 (D9S162), 11p13 (D11S903), 12q22-23 (D12S1051), and 18q21 (D18S46). Fourteen of 16 (88%) cases showed allelic loss in one or more components of the mixed germ cell tumors. Fourteen of 16 mature teratomas showed allelic loss in at least one of six microsatellite polymorphic markers analyzed. The frequency of allelic loss in mature teratoma was 50% (7 of 14) with D1S508, 33% (5 of 15) with D2S156, 58% (7 of 12) with D9S162, 43% (6 of 14) with D11S903, 20% (3 of 15) with D12S1051, and 33% (5 of 15) with D18S46. Completely concordant allelic loss patterns between mature teratoma and all of the other germ cell tumor components were seen in 10 of 14 tumors in which mature teratoma showed loss of heterozygosity. Our data support the common clonal origin of mature teratoma with other components of malignant mixed germ cell tumors of the testis.     

CD10 is expressed in a subset of chromophobe renal cell carcinomas.

CD10 has been considered a useful marker in the diagnosis of renal carcinomas, because of its expression in clear cell and papillary renal cell carcinomas and its absence in chromophobe renal cell carcinomas. On the other hand, chromophobe renal cell carcinoma expresses parvalbumin, which is absent in clear cell and papillary renal cell carcinomas. To further address the relevance of these markers, we studied the expression of CD10 and parvalbumin in 42 samples of chromophobe renal cell carcinoma (seven of which had aggressive features, including invasion beyond the renal capsule, renal vein invasion, metastases, or sarcomatoid transformation), 75 clear cell renal cell carcinomas (eight metastatic) and 51 papillary renal cell carcinomas (two metastatic). CD10 was found in 100% of clear cell renal cell carcinomas, 63% of papillary renal cell carcinomas and in all metastatic cases of both types. At variance with previous studies, we found CD10 expression in from 30 to 90% of the neoplastic cells, in 11 of 42 (26%) chromophobe renal cell carcinomas. The CD10-positive cases included five of the seven (71%) chromophobe renal cell carcinoma with aggressive features. Statistical analysis showed significant association of CD10-positive tumors with clinicopathologic aggressiveness (P=0.003) and mitotic figures (P=0.04). Parvalbumin was strongly expressed in all primary and metastatic chromophobe renal cell carcinomas. Western blot analysis was utilized to confirm the expression of both CD10 and parvalbumin in chromophobe renal cell carcinomas.