Neurobehavioral alterations in HIV-1 transgenic rats: evidence for dopaminergic dysfunction.

Clinical studies have provided evidence that the progression of HIV-1-associated neurocognitive disorders (HAND) involves alterations in dopamine (DA) systems. Drugs of abuse that act on the brain DA system, such as cocaine (Coc), may exacerbate HIV-1 infection and consequent behavioral and neurological manifestations. In the present study, we used the HIV-1 transgenic (Tg) rat, which constitutively expresses 7 of the 9 HIV-1 genes, to assess potential DA system alterations in three behavioral assays: prepulse inhibition (PPI) of the auditory startle response (ASR), novelty and habituation/retention, and sensitization to Coc across repeated administration. Adult female Sprague-Dawley rats were tested in each experiment. The HIV-1 Tg animals were hyperreactive to auditory startle stimuli and displayed a leftward shift in the temporal window for maximal PPI, suggesting an alteration in sensorimotor gating. All animals displayed an initial robust locomotor response to a novel environment which dissipated with repeated testing; however, the HIV-1 Tg rats, relative to controls, consistently showed a weaker novelty response across monthly-spaced assessments. The HIV-1 Tg animals also showed decreased intrasession habituation of motor activity across 3-day periods that emerged across monthly-spaced locomotor activity sessions; a pattern consistent with impaired long-term episodic memory. Furthermore, the HIV-1 Tg group displayed differential cocaine-induced sensitization, observed both in initiation across the 10-day cocaine treatment, and in expression following a cocaine rechallenge after a 7-day abstinence. Collectively, the present data implicate that the non-infectious HIV-1 Tg rat, which resembles the complete suppression of infection in HIV-1 positive individuals under CART, displays sustained, if not permanent, alterations in the brain DA system.

[Quality assessment in single-slice spiral brain CT examinations of patients with cerebrovascular accident]. / Evaluación de la calidad de los exámenes de tomografía computarizada de cerebro en la indicación de accidente cerebro-vascular agudo.

OBJECTIVES: Our objective was to apply quality criteria proposed by the European Commission (EC) Guidelines to the brain CT examinations for cerebrovascular accident (CVA) diagnosis at single-slice spiral CT scanners from five different hospitals in the Madrid area. MATERIAL AND METHODS: A sample of 100 brain CT examinations was collected and independently reviewed by five radiologists, to determine the degree of fulfilment of image quality criteria. Dose measurements were performed to estimate the values of the CT dose indexes (CTDIw, CTDIair), the dose length product (DLP), and the effective dose (E). RESULTS: Once the McNemar test was applied to the sample, the number of observers' readings was reduced to three. The quality criteria were, in general, fulfilled, since mean values of image quality score between 80% and 92% were deduced, with variation coefficients per centre in the range of 0.07-0.1. However, both visualization criteria 1.1.2 and 1.1.3 exhibited similar ranges of fulfilment (38% - 94%). The good compliance with critical reproduction criteria in the study reflected the capability of these CT scanners to create images of adequate quality, although optimisation should be achieved in some of the centres. Concerning radiation exposure, the mean values per centre of the dose quantities were in the range of 42-64 mGy for the weighted CTDI (CTDIw), 423-744 mGy x cm for DLP, and 1.1-1.9 mSv for E. CONCLUSIONS: The mean values at three centres were close to but above the reference value proposed by the EC Guidelines for CTDIw (60 mGy), and lower than the corresponding reference level for DLP (1050 mGy x cm). Dose optimisation techniques focused on the adjustment of the CTDIw-related examination parameters were proposed.

Evaluación de la calidad de los exámenes de tomografía computarizada de cerebro en la indicación de accidente cerebro vascular agudo / Quality assessment in single-slice spiral brain ct examinations of patients with cerebrovascular accident

Objetivos. El objetivo del trabajo ha sido aplicar los criterios de calidad propuestos en la Guía de la Comisión Europea sobre criterios de calidad en tomografía computarizada (TC) para exámenes de cerebro en la indicación de accidente cerebro-vascular (ACV) en cinco centros de la Comunidad de Madrid dotados de equipos de TC helicoidal de corte único. Material y métodos. Se ha recogido una muestra de 100 exámenes de cerebro que ha sido analizada independientemente por cinco radiólogos para establecer el grado de cumplimiento de los criterios de imagen propuestos. Se han efectuado medidas de dosis en los centros para estimar los valores de los índices de dosis de TC (CTDIw, CTDIair), el producto dosis-longitud (DLP) y la dosis efectiva (E). Resultados. Después de aplicar las pruebas de McNemar y de Friedman a las evaluaciones, se seleccionaron las correspondientes a tres observadores. En general se cumplieron los criterios de calidad en una proporción alta, con promedios del índice de calidad de imagen por centros entre el 80% y el 92%, y coeficientes de variación entre 0,07 y 0,1. Sin embargo, dos criterios de visualización (el 1.1.2 y el 1.1.3) se cumplieron en una proporción variable según los centros con un rango similar de cumplimiento medio (38%-94%). Los criterios de reproducción crítica se cumplieron en una mayor proporción que los de visualización, reflejando así la capacidad técnica de estos equipos para generar imágenes de calidad adecuada, aunque en algunos centros hay que optimizar los procedimientos. En cuanto a las dosis de radiación, los valores medios del CTDIw por centros estuvieron en el intervalo 42-64 mGy, los del DLP entre 423 y 744 mGy·cm y la dosis efectiva media entre 1,1 y 1,9 mSv. Conclusiones. Los valores medios del CTDIw en tres de los centros estuvieron ligeramente por encima del valor de referencia propuesto en la Guía Europea (60 mGy) y en todos por debajo del correspondiente para el DLP (1050 mGy·cm). Se han analizado y propuesto vías de optimización de la calidad de imagen y la dosis en cada centro

Objectives. Our objective was to apply quality criteria proposed by the European Commission (EC) Guidelines to the brain CT examinations for cerebrovascular accident (CVA) diagnosis at single-slice spiral CT scanners from five different hospitals in the Madrid area. Material and methods. A sample of 100 brain CT examinations was collected and independently reviewed by five radiologists, to determine the degree of fulfilment of image quality criteria. Dose measurements were performed to estimate the values of the CT dose indexes (CTDIw, CTDIair), the dose length product (DLP), and the effective dose (E). Results. Once the McNemar test was applied to the sample, the number of observers' readings was reduced to three. The quality criteria were, in general, fulfilled, since mean values of image quality score between 80% and 92% were deduced, with variation coefficients per centre in the range of 0.07-0.1. However, both visualization criteria 1.1.2 and 1.1.3 exhibited similar ranges of fulfilment (38% -- 94%). The good compliance with critical reproduction criteria in the study reflected the capability of these CT scanners to create images of adequate quality, although optimisation should be achieved in some of the centres. Concerning radiation exposure, the mean values per centre of the dose quantities were in the range of 42-64 mGy for the weighted CTDI (CTDIw), 423-744 mGy·cm for DLP, and 1.1-1.9 mSv for E. Conclusions. The mean values at three centres were close to but above the reference value proposed by the EC Guidelines for CTDIw (60 mGy), and lower than the corresponding reference level for DLP (1050 mGy·cm). Dose optimisation techniques focused on the adjustment of the CTDIw-related examination parameters were proposed

Image quality and dose evaluation in spiral chest CT examinations of patients with lung carcinoma.

A study was undertaken to assess the quality of general chest CT examinations for indication of lung carcinoma according to the criteria proposed in the European Commission (EC) Guidelines, and to investigate their usefulness in the optimization of this practice. The criteria were evaluated for a sample of 100 examinations from five radiology departments in the Madrid area featuring single slice helical CT scanners with special emphasis on radiation dose and image quality. To determine the degree of compliance with the image criteria considered, the examinations were independently evaluated twice by five radiologists from the participating centres. A subsequent selection of the observers was made according to the consistency and independence of their readings. Dose measurements carried out in parallel supplied data to estimate the values of the CT dose indices (CTDI), dose-length product (DLP) and effective dose (E). The results show good compliance with the image criteria used - between 93% and 98% on average at the different sites, with variable degrees of internal deviation. 10 out of a total of 16 criteria proposed in the EC guidelines were met by practically all the examinations in the sample. The average weighted CTDI (CTDI(w)) values per site were in the range of 13-19 mGy; those of DLP were between 263 mGy cm and 577 mGy cm, and those of effective dose between 4 mSv and 9 mSv. The highest mean DLP value was below but close to the reference value proposed in the EC Document (650 mGy cm). In general, a weak correlation or no correlation at all was found between image quality scores and patient dose (DLP).

A propósito de un caso de malposición de fabela / A case report malpositioned fabella

La fabela es un hueso sesamoideo situado en el compartimento femorotibial posteroexterno de la rodilla. Se presenta la radiografía simple de una fabela que fue interpretada como un cuerpo libre intraarticular. En la resonancia magnética (RM) se demostró que era la fabela, no en su localización habitual, hipertrofiada y con cambios osteoartrósicos (AU)

Objective evaluation of aided thresholds using auditory steady-state responses.

Auditory steady-state responses to amplitude-modulated tones with modulation frequencies between 80 and 105 Hz can be recorded when multiple stimuli are presented simultaneously through a soundfield speaker and amplified using a hearing aid. Responses were recorded at carrier frequencies of 500, 1000, 2000, and 4000 Hz in a group of 35 hearing-impaired children using hearing aids. The physiologic responses were recorded at intensities close to the behavioral thresholds for sounds in the aided condition, with average differences between the physiologic and behavioral thresholds of 17, 13, 13, and 16 dB for carrier frequencies 500, 1000, 2000, and 4000 Hz. The technique shows great promise as a way to assess aided thresholds objectively in subjects who cannot reliably respond on behavioral testing.

Frequency-specific audiometry using steady-state responses.

OBJECTIVE: To evaluate the audiometric usefulness of steady-state responses to multiple simultaneous tones, amplitude-modulated at 75 to 110 Hz. DESIGN: Steady-state responses to multiple tones amplitude-modulated at different rates between 75 and 110 Hz and presented simultaneously were recorded at different intensities in normal adults, well babies, normal adults with simulated hearing loss, and adolescents with known hearing losses. Response thresholds were compared with behavioral thresholds. RESULTS: In normal adults the thresholds for steady-state responses to tones of 0.5, 1, 2, and 4 kHz were 14 +/- 11, 12 +/- 11, 11 +/- 8, and 13 +/- 11 dB, respectively, above behavioral thresholds for air-conducted stimuli, and 11 +/- 5, 14 +/- 8, 9 +/- 8, and 10 +/- 10 dB above behavioral thresholds for bone-conducted stimuli. In well babies tested in a quiet environment, the thresholds were 45 +/- 13, 29 +/- 10, 26 +/- 8, and 29 +/- 10 dB SPL. In adolescents with known hearing losses, the steady-state responses thresholds predict behavioral thresholds with correlation coefficients (r) of 0.72, 0.70, 0.76, and 0.91 at 0.5, 1, 2, and 4 kHz, respectively. CONCLUSION: Steady-state responses to tone amplitude-modulated at 75 to 110 Hz can be used for frequency-specific objective audiometry. The multiple-stimulus technique allows thresholds to be estimated for eight different stimuli at the same time.

Recording auditory brainstem responses from infants.

Auditory brainstem responses (ABRs) can be reliably recorded from infants in the first few months of life. Since they are normally recognizable down to intensities that are 30 dB above normal hearing thresholds, ABRs elicited by clicks are useful in screening for hearing-impairment in infancy. The ABRs can also provide further diagnostic information about the hearing losses that are detected by screening: the threshold for the response represents a reasonable estimate of the severity of the hearing loss; bone-conduction studies can assess the extent of a conductive loss; and frequency-specific techniques can evaluate hearing thresholds at different frequencies. At present, ABRs are mainly used for screening infants who have been treated in neonatal intensive care units. Because the majority of infants with hearing impairment are not seen in these units, it might be worthwhile to use ABRs in a more widespread screening program.

Thresholds for short-latency auditory-evoked potentials to tones in notched noise in normal-hearing and hearing-impaired subjects.

The thresholds for the short-latency auditory evoked potentials (SLAEPs) to short-duration tones presented in notched-noise masking were evaluated in 20 normal-hearing and 20 hearing-impaired subjects. The differences (dB) between these thresholds (dB nHL) and the pure-tone behavioral thresholds (dB HL) across all 40 subjects were 11.6, 6.1, 6.3 and 0.8 dB for 500, 1,000, 2,000 and 4,000 Hz, respectively. These differences were significantly smaller for the hearing-impaired subjects than for the normal-hearing subjects. Ninety-eight percent of the SLAEP threshold estimations were within 30 dB of the subjects' pure-tone behavioral thresholds and 91% were within 20 dB.