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Biomedical subjects

M L Manning

Publications and source records attributed to M L Manning.

At least 19 recordsLinked to original sources
PubMed2001

Serratia marcescens transmission in a pediatric intensive care unit: a multifactorial occurrence.

BACKGROUND: Fourteen patients in the pediatric cardiac intensive care unit (CICU) had > or =1 positive culture for a single strain of Serratia marcescens from April through December 1995 (study period). OBJECTIVES: To identify risk factors for S marcescens infection or colonization in a pediatric CICU. METHODS: Retrospective case-control study. Assessment of CICU infection control practices and patient exposure to CICU health care workers (HCWs). Epidemiologic-directed cultures of the environment and HCWs' hands were obtained. SETTING: Pediatric CICU. PATIENTS: Fourteen patients in the pediatric CICU had > or =1 positive culture for a single strain of S marcescens from April through December 1995 (study period). CICU patients who did not have S marcescens infection or colonization during the study period were randomly selected as controls. RESULTS: A case patient was more likely than a noncase patient to have exposure to a single HCW (odds ratio [OR], 19.5; 95% CI, 2.6-416; P<.003); however, this association was not adequately explained by epidemiologic or microbiologic studies. Interviews suggested that during the outbreak period, handwashing frequency among HCWs might have been reduced because of severe hand dermatitis. CONCLUSIONS: A combination of factors, including breaks in aseptic technique, reduced frequency of handwashing among HCWs before and between caring for patients, decreased attention to infection control practices, and environmental contamination may have indirectly contributed to this S marcescens infections outbreak.

Adolescent↗
PubMed2000

Nosocomial respiratory syncytial virus infections: the cost-effectiveness and cost-benefit of infection control.

OBJECTIVE: To determine the cost-effectiveness and cost-benefit of an infection control program to reduce nosocomial respiratory syncytial virus (RSV) transmission in a large pediatric hospital. DESIGN: RSV nosocomial infection (NI) was studied for 8 years, before and after intervention with a targeted infection control program. The cost-effectiveness of the intervention was calculated, and cost-benefit was estimated by a case-control comparison. SETTING: Children's Hospital of Philadelphia, a 304-bed pediatric hospital. PATIENTS: All inpatients with RSV infection, both community- and hospital-acquired. INTERVENTION: Consisted of early recognition of patients with respiratory symptoms, confirmation of RSV infection by laboratory testing, establishing cohorts of patients and nursing staff, gown and glove barrier precautions, and monitoring and education of staff. OUTCOME MEASURES: The incidence density of RSV NI before and after the intervention was calculated as the rate per 1000 patient days-at-risk for infection. Intervention costs included laboratory testing, isolation, and administration of the program. The cost of RSV NI was estimated by comparing hospital charges for 30 cases and matched uninfected controls. RESULTS: A total of 148 patients acquired NI (88 before and 60 after the intervention). The Mantel-Haenszel stratified relative risk for NI in the period before the infection control program, compared with the postintervention period, was.61 (95% confidence interval:.53-.69). By applying the preintervention stratum-specific rates of infection to the days-at-risk in the postintervention period, an estimated 100 NIs would have been expected, which in comparison to the 60 NIs observed, yielded an estimated program effectiveness of 10 RSV NIs prevented per season. The total cost of the program per season was $15 627 or $1,563/NI prevented. In comparison, the mean cost to the hospital was $9,419/case of RSV NI, resulting in a cost-benefit ratio of 1:6. CONCLUSIONS: A targeted infection control intervention was cost-effective in reducing the rate of RSV NI. For every dollar spent on the program, approximately $6 was saved.

Case-Control Studies↗
PubMed2000

The judicious use of antibiotic agents in common childhood respiratory illness.

Increased bacterial resistance is caused most frequently by the widespread use of antimicrobial agents. Antimicrobial agents are often used inappropriately to treat common respiratory illnesses in children. This article discusses the judicious use of antimicrobials in the common cold, otitis media, acute sinusitis, pharyngitis, and bronchitis.

Acute Disease↗
PubMed1997

Patient density, nurse-to-patient ratio and nosocomial infection risk in a pediatric cardiac intensive care unit.

BACKGROUND: An investigation of a Serratia marcescens outbreak in a pediatric cardiac intensive care unit (CICU) suggested that understaffing or overcrowding might have been underlying risk factors. OBJECTIVE: To assess the effect of fluctuations in CICU nurse staffing levels and patient census on CICU nosocomial infection rate (NIR). METHODS: The monthly CICU nursing hours, patient days and nosocomial infections were obtained from retrospective review of administrative, patient and microbiology records during December, 1994, through December, 1995 (study period). The NIR and nursing hours:patient day ratio were then calculated. The correlations between NIR vs. nursing hours, patient days and nursing hours:patient day ratio were determined. RESULTS: The median monthly CICU NIR was 6.9 (range, 0 to 15.2) infections per 1000 patient days; the median number of hours worked per month by CICU registered nurses was 7754 (range, 7133 to 8452) hours; the median number of patient days treated per month was 507 (range, 381 to 590) patient days; and the median monthly nursing hours:patient day ratio was 15.2:1 (range, 13.2:1 to 19.9:1). The strongest linear correlation was observed between the monthly NIR and patient days (r = 0.89, P = 0.0001). There was an inverse correlation between the monthly NIR and nursing hours:patient day ratio (r = -0.77, P = 0.003). CONCLUSIONS: The NIR was most strongly correlated with patient census but also was strongly associated with the nursing hours:patient day ratio. These factors may influence the infection rate because of breaks in health care worker aseptic technique or decreased hand washing. Increased patient census alone may increase the risk of cross-transmission of nosocomial infections. As hospitals proceed with cost containment efforts the effect of fluctuations in patient census and nurse staffing on patient outcomes needs evaluation.

Child↗
PubMed1997

Time-till-breakdown and scalp electrical potential maps of long-range apparent motion.

A series of psychophysical and electrophysiological experiments is reported using the apparent motion (AM) breakdown effect. Breakdown describes an effect in AM in which, during continuous viewing, the percept of smooth of a single stimulus alternates with the percept of two discrete alternating stimuli. Visual evoked potentials (VEPs) were recorded during periods of motion or breakdown ("nonmotion") in horizontal and vertical displays. VEPs were compared with synthetic VEPs ("composite-flash") produced by adding VEPs to each element of the display recorded in isolation. Subtraction of VEPs was used in an attempt to compare the electrical responses with the processing of information relating to the form of the stimulus, subthreshold motion processing, and suprathreshold motion processing. The results, presented as scalp electrical potential distribution maps, were interpreted as consistent with a central adaptation process underlying the breakdown effect. The results also indicated that the hemispheric asymmetries in AM VEPs described by Manning, Finlay, and Fenelon (1988) were most likely due to the position of the stimuli in the visual field, rather than as a lateralization of motion processes per se. The results also provided evidence that the subthreshold and suprathreshold motion responses to the display were the product of different populations of motion units.

Adult↗
PubMed1995

Immunity induced by primary human cytomegalovirus infection protects against secondary infection among women of childbearing age.

To determine if immunity to human cytomegalovirus (HCMV) protects women from acquiring HCMV from their children, a blinded, randomized protocol was used to monitor seronegative women who received placebo or Towne vaccine (approximately 500 pfu) and seropositive women. Each group was similar for mean maternal (33 years) and child age (18 months) and duration of viral shedding by the child (15 months). Among 19 placebo recipients, 9 developed primary infection; 8 of 19 vaccines but only 3 of 42 naturally seropositive subjects had evidence of acquiring HCMV from their child. Wild type infection and Towne vaccine induced similar mean lymphoproliferative responses to HCMV antigens, but one dose of Towne vaccine produced mean neutralizing titers 10- to 20-fold lower than those after wild type infection. Thus, a vaccine that induces immune responses equal to those induced by wild type virus may protect healthy women from acquiring HCMV from their children.

Adult↗
PubMed1993

Delayed type hypersensitivity to human cytomegalovirus.

A skin test for immunity to human cytomegalovirus (HCMV) is described in which skin induration is measured after intradermal injection of antigen derived from heat-inactivated Towne strain HCMV or of envelope prepared from the virus. Randomly selected healthy young adult males and females were prescreened for evidence of past infection with HCMV using serologic tests. Each individual was inoculated with heat inactivated whole virion HCMV antigen prepared from serum-free supernatants of HCMV-infected MRC-5 cells, non-infected MRC-5 cell lysates, and Candida extract. HCMV seropositive individuals developed positive skin reactions to both the Candida extract and the HCMV test antigen. No response was observed at the MRC-5 cell lysate inoculation site. The envelope antigen also elicited a response in seropositive individuals. Seronegative individuals who were negative to the HCMV intradermal antigen at the start of the study developed a positive response 1 week after subcutaneous immunization with live attenuated Towne strain HCMV. This response also correlated with the onset of in vitro proliferation responses to HCMV antigens by peripheral blood lymphocytes obtained from the immunized individuals. Furthermore, skin test and lymphocyte proliferation responses remained positive when tested up to 93 days post-immunization. In guinea pig experiments with HCMV, those animals immunized with purified HCMV or a virus envelope preparation developed strong skin reactions to intradermal injection of each of those antigens. In contrast, no reaction was observed in immune animals, either to viral capsid antigen or uninfected cell-lysate antigen, and no reactions were observed to any HCMV antigen in non-immune animals.

Animals↗
PubMed1992

Detection duration thresholds and evoked potential measures of stereosensitivity.

Visual evoked potentials have been proposed by some researchers to be more useful than behavioral techniques to evaluate stereo performance in children and certain clinical populations. Stimulus duration detection thresholds, visual evoked potentials, and scalp electrical potential distribution maps to dynamic random dot stereograms were studied. A high degree of correspondence was found between visual evoked potential amplitudes and behaviorally determined detection thresholds. Upper field stimuli had higher detection thresholds and generated lower-amplitude visual evoked potential responses than did centrally presented stimuli. For the most eccentrically presented stimuli, lower detection thresholds were found for stimuli presented in the right visual field than the left visual field. This finding was consistent with the pattern of VEP responses to be lateralized, with higher-amplitude responses recorded over left-hemisphere sites. The study examined a proposal that the major negative component of the stereoscopic visual evoked potential originates in cortical area V1. The results failed to support the proposal and were consistent with the main negative component of the VEP being generated in V2, rather than V1.

Adult↗
PubMed1991

Time-till-breakdown and VEP measures of short-range apparent motion.

Varying short-range apparent motion (AM) stimulus displacements from 2.7 to 21.6 min it was found that VEP amplitudes varied as a function of the limits for short-range AM described using time-till-breakdown as a behavioural measure of AM strength. This VEP amplitude difference was, however, in the reverse direction to that predicted as the "motion" condition elicited lower VEP amplitude responses than the "non-motion" conditions (which did not significantly differ from each other). This direction of VEP amplitude difference was supported by an intensive study of a single subject. The "breakdown effect" enabled VEPs to be gathered during periods in which the subjective experience was of either coherent lateral motion, or breakdown (incoherent motion) without changing any stimulus parameter. The VEP component identified in expt 2, as predicted, was of lower amplitude during motion with respect to periods of breakdown. The results of these experiments are discussed in terms of describing motion and breakdown in short-range AM displays as "coherent" and "incoherent" motion, rather than as "motion" and "non-motion".

Adult↗
PubMed1991

Patterns of neuropsychological impairment after severe blunt head injury.

A consecutive series of 100 subjects with severe blunt head injuries was followed up 6 years after trauma. Neuropsychological test performances of 82 subjects and of a noninjured control group were analyzed by two principal components analyses (PCAs). Each PCA extracted 15 factors relating to a range of cognitive impairments, as well as neuropsychological features consistent with posttraumatic personality changes. Measures identified by the PCAs were applied to 85 head-injured subjects in the series to examine the incidence of impairment in four neuropsychological areas: disorders of learning and memory, neuropsychological features consistent with posttraumatic personality change, slowness in rate of information processing, and a range of basic neuropsychological skills. Overall, impairments occurred in 70% of the series. Disorders of learning and memory were the most common type of deficit (56.5%), with disturbances in basic neuropsychological skills the least frequent (16.5%). Variability among subjects with respect to the types and combinations of neuropsychological impairments was a characteristic feature of this clinical group, but the largest proportion (one-third) demonstrated isolated impairments. The implications of the incidence and selectivity of neuropsychological impairments are discussed.

Adolescent↗
PubMed1991

Differential motion thresholds to sinusoidal gratings at two eccentricities.

Differential motion thresholds were measured at eccentricities of 9 degrees and 16.6 degrees using computer-generated sinusoidal gratings. Three spatial frequencies (0.51, 0.25, and 0.13 cycles/deg) were examined at reference velocities of 2, 4, 8, 16, 32, and 48 deg/sec. Minimum differential velocity thresholds were between 20 and 30% of the reference velocities for the three spatial frequencies at both eccentricities. Increasing eccentricity produced an increase in the velocity at which minimum velocity discrimination occurred. Temporal frequency tuning was between 4 and 8 Hz, regardless of eccentricity.

Acceleration↗
PubMed1989

Difficulties in the definition of 'stereoscotoma' using temporal detection of thresholds of dynamic random dot stereograms.

Temporal detection thresholds are reported from two subjects to dynamic random dot stereograms (DRDSs) of both crossed and uncrossed disparity. The stimuli were 1 degree square, of 0.25 degrees disparity and were presented at 81 positions in a 9 degree square central region. In both subjects crossed disparity stimuli were detected at shorter durations. One subject displayed particularly acute stereoscopic vision and presented a pattern of temporal thresholds increasing gradually with eccentricity. The other subject displayed evidence, particularly in response to uncrossed stimuli, of a 'stereo-scotoma' which was not evident in monocular testing or ophthalmologic examination. Criteria used to define 'stereo-scotoma' are discussed. It was concluded that, although left-right field differences may be found with a large subject sample, individual factors may be more important in the distribution of stereo sensitivity throughout the portion of visual field tested.

Adult↗
PubMed1989

Motion components of VEPs to the waggon wheel effect.

Visual evoked potentials (VEPs) from eight subjects are presented from scalp sites O1, O2, T5, T6, P3 and P4. A spoked wheel was illuminated by a constantly flashing strobe. By adjusting the real angular speed of the wheel the subjective impression was given of; a stationary wheel, a wheel spinning slowly or spinning rapidly clockwise. Two visually identified components, a negativity and a positivity, were found to be of larger amplitude in response to motion. The results were interpreted as consistent with a model of AM proposing motion information to be processed within the visual system.

Evoked Potentials, Visual↗
PubMed1988

Visual evoked potentials to stimuli in apparent motion.

Following an extensive single subject pilot study 12 Ss viewed a continuously cycling (3 Hz), two stimulus, apparent motion (AM) display. The "AM breakdown effect" was utilised to gather visual evoked potentials (VEPs) from sites O1, O2, T5, T6, P3, and P4 during periods in which the display elicited either: the percept of motion; or the percept of two discrete alternating stimuli. VEPs displayed components of larger amplitude during motion periods in all right (but no left) hemisphere sites during periods 60-82 msec post left field stimulus onset (positive component) and 100-126 msec post right field stimulus onset (negative component). Results were interpreted as indicating initial extraction of motion information within the occipital lobe, with further motion processing taking place in temporal and parietal lobes.

Adult↗
PubMed1987

Effects of movement in the background field on long-range apparent motion.

Two experiments are reported using time-till-breakdown as a measure of apparent motion (AM) in untrained subjects. In Experiment 1 centrally viewed dynamic random dot stereograms and non-disparate stimuli in dynamic random dot fields yielded higher optimal frequencies than did a standard binocular condition. In Experiment 2 a higher optimal frequency was observed for disparate dynamic random dot stimuli compared with both standard binocular and non disparate stimuli presented on a static random dot field. Interaction between short- and long-range AM processes is considered in the interpretation of the findings.

Depth Perception↗
PubMed1987

Detection threshold differences to crossed and uncrossed disparities.

Using a sample of 85 subjects measurements were made of minimum stimulus durations necessary for detection of crossed and uncrossed disparity stimuli which were presented in five positions in the visual field: centre, lower, upper, right, and left field. The results indicated large detection duration differences between the two disparity conditions, with a marked superiority for crossed disparity detection at all positions. A left-right visual field anisotropy was demonstrated for crossed disparity stimuli.

Depth Perception↗