Search PubMed⌕ Search

Biomedical subjects

R E Hoffman

Publications and source records attributed to R E Hoffman.

At least 37 records · Page 2Linked to original sources
PubMed1999

Increased protections during a measles outbreak of children previously vaccinated with a second dose of measles-mumps-rubella vaccine.

BACKGROUND: In 1989 a second dose of measles vaccine was recommended for US children to prevent school outbreaks of measles. Coverage of school age children with a second dose remains incomplete, and data on the effectiveness of this recommendation are limited. We investigated a measles outbreak in Mesa County, CO, in December, 1994, and evaluated the efficacy of preoutbreak immunizations at an elementary school (School A) where many students had received two doses. METHODS: All reported suspected cases of measles were investigated; cases that met a clinical case definition were tested by a measles IgM antibody assay. A confirmed case required laboratory confirmation or had to meet the clinical case definition and be epidemiologically linked to a confirmed case. Vaccination records of students at School A were reviewed. The effectiveness of one and two doses of measles vaccine was estimated using logistic regression. RESULTS: Sixty-two confirmed cases were reported, including 17 at School A. At School A the attack rate in unvaccinated children (7 of 16, 44%) was higher than in those with 1 dose (10 of 320, 3%) or 2 doses (0 of 289, 0%). Estimated vaccine effectiveness was 92% for 1 dose and 100% for 2 doses. Two doses were better than one dose in decreasing the likelihood of acquiring measles (P = 0.003). CONCLUSIONS: The lower attack rate among two dose recipients provides evidence that a two dose strategy can help prevent measles in schools. Administering the second dose at elementary school entry can help prevent the persistence of susceptible cohorts of children and is likely to be important in sustaining elimination of indigenous transmission of measles in the United States.

Adolescent↗
PubMed1999

New methods for studying hallucinated 'voices' in schizophrenia.

The mechanism of hallucinated speech or 'voices', a symptom commonly reported by schizophrenic patients, is poorly understood. We have undertaken two types of study to explore the hypothesis that this symptom arises from pathologically altered speech perception networks. The first consists of neural network computer simulations of narrative speech perception. We have shown that if these networks are partially disconnected or undergo a 'monamine' neuromodulatory disturbance, 'hallucinated speech' (speech percepts occurring in the absence of phonetic input) are simulated as well as specific speech perception impairments. The latter finding prompted us to conduct parallel studies of actual schizophrenic patients using a 'masked speech tracking' (MST) task. MST requires subjects to track narrative speech the phonetic clarity of which is reduced with superimposed multispeaker 'babble.' Hallucinators demonstrated speech perception impairments and experimentally induced perceptual 'illusions' which clearly differentiated them from non-hallucinators and normal controls. Our results support the hypothesis that 'voices' are spurious products of altered speech perception networks.

Adolescent↗
PubMed1999

Selective speech perception alterations in schizophrenic patients reporting hallucinated "voices".

OBJECTIVE: The authors tested a model of hallucinated "voices" based on a neural network computer simulation of disordered speech perception. METHOD: Twenty-four patients with schizophrenia spectrum disorders who reported hallucinated voices were compared with 21 patients with schizophrenia spectrum disorders who did not report voices and 26 normal subjects. Narrative speech perception was assessed through use of a masked speech tracking task with three levels of superimposed phonetic noise. A sentence repetition task was used to assess grammar-dependent verbal working memory, and an auditory continuous performance task was used to assess nonlanguage attention. RESULTS: Masked speech tracking task and sentence repetition performance by hallucinating patients was impaired relative to both nonhallucinating patients and normal subjects. Although both hallucinating and nonhallucinating patients demonstrated auditory attention impairments when compared to normal subjects, the two patient groups did not differ with respect to these variables. CONCLUSIONS: Results support the hypothesis that hallucinated voices in schizophrenia arise from disrupted speech perception and verbal working memory systems rather than from nonlanguage cognitive or attentional deficits.

Adult↗
PubMed1999

Elevation of human intraocular pressure at night under moderate illumination.

PURPOSE: An endogenous elevation of intraocular pressure (IOP) occurs at night in healthy young adults. The authors studied whether or not this IOP elevation can be detected under moderate illumination. METHODS: Twenty-five healthy volunteers, ages 18 to 25 years, were housed overnight in a sleep laboratory under a strictly controlled light-dark environment. Intraocular pressure was measured in the supine position every 2 hours, using a pneumatonometer. An 8-hour sleep period was assigned to each volunteer according to individual's accustomed sleep cycle. In the early part of this assigned period, sleep was encouraged with room lights off. Researchers performed IOP measurements at two time points with the aid of night vision goggles. In the middle to the late part of the assigned period, lights were turned on twice for a 1-hour interval. The light intensity was the same as before the bedtime. At the ending of each light period, IOP was measured under illumination. RESULTS: Average IOP was significantly higher in the assigned sleep period versus outside the period. The trough of mean IOP occurred just before the bedtime, and then IOP gradually increased and peaked at the end of the 8-hour assigned sleep period. The difference between the trough and peak IOP was 3.5 +/- 0.7 mm Hg (mean +/- SEM, n = 25). Within the assigned sleep period, the average IOP determined under illumination was significantly higher than the average IOP preceding the illumination. CONCLUSIONS: Elevation of IOP occurred during the assigned sleep period with two 1-hour light exposures of moderate intensity. Environmental light at night had no significant effect on the nocturnal IOP elevation in healthy young adults.

Adolescent↗
PubMed1999

Twenty-four-hour pattern of intraocular pressure in the aging population.

PURPOSE: To characterize the 24-hour pattern of intraocular pressure (IOP) in a sample of the aging human population. METHODS: Twenty-one healthy volunteers 50 to 69 years of age were housed in a sleep laboratory for 24 hours. Experimental conditions were strictly controlled with a 16-hour light period and an 8-hour dark period. Sleep was encouraged in the dark period. Intraocular pressure was measured using a pneumatonometer every 2 hours (total of 12 times). Measurements were taken in both the sitting position and the supine position during the light/wake period but only in the supine position during the dark period. RESULTS: When the sitting IOP data from the light/wake period and the supine IOP data from the dark period were considered, elevation and reduction of IOP occurred around the scheduled lights-off and lights-on transitions, respectively. Mean IOP in the dark period was significantly higher than mean IOP in the light/wake period. The trough appeared at the end of the light/wake period, and the peak appeared at the beginning of the dark period. The magnitude of trough-peak difference was 8.6+/-0.8 mm Hg (mean +/- SEM). Cosine fits of 24-hour IOP data showed a significant 24-hour rhythm. When IOP data from just the supine position were analyzed, the trough-peak IOP difference was 3.4+/-0.7 mm Hg, with similar clock times for the trough and the peak. Cosine fits of supine IOP data showed no statistically significant 24 hour rhythm. CONCLUSIONS: Nocturnal elevation of IOP occurred in this sample of the aging population. The trough of IOP appeared at the end of the light/wake period, and the peak appeared at the beginning of the dark period. The main factor in the nocturnal IOP elevation appeared to be the shift from daytime upright posture to supine posture at night.

Aged↗
PubMed1998

Reduced corticocortical connectivity can induce speech perception pathology and hallucinated 'voices'.

Reciprocal interactions between multiple cortical areas are required for higher-order cognitive processes in animals and humans. A growing body of evidence suggests that reduced cortical connectivity is associated with schizophrenia. We have used neural network computer simulations to characterize symptoms and cognitive pathology that could arise from connectivity reductions. When this pathology was reproduced in simulations of speech perception networks, spontaneous percepts analogous to hallucinated speech were induced due to the emergence of 'locked-in' or 'parasitic' states. We propose that these simulations provide a model for hallucinated 'voices' reported by actual schizophrenic patients. The 'hallucinogenic' model of speech perception also demonstrated subtle speech perception impairments. We have demonstrated similar impairments when assessing schizophrenic patients reporting 'voices', but not when assessing similarly diagnosed patients not reporting this symptom. The model also demonstrates how a 'hypodopaminergic' state can reverse cognitive pathology arising from connectivity disturbances.

Cerebral Cortex↗
PubMed1998

An outbreak of salmonellosis among children attending a reptile exhibit at a zoo.

OBJECTIVE: In January 1996, an outbreak of diarrhea caused by Salmonella Enteritidis occurred in children attending a Komodo dragon exhibit at a metropolitan zoo. We sought to determine the extent of the outbreak and mode of transmission. STUDY DESIGN: A case-control study was conducted. Controls were randomly selected from zoo membership lists and matched to patients by age group and date of exhibit visit. RESULTS: Of 65 patients identified, 39 had confirmed and 26 had suspected cases. The median age was 7 years (range, 3 months to 48 years); 55% were enrolled in the case-control study. No patients and two (4%) controls reported touching a dragon; however, 83% of patients but only 52% of controls touched the wooden barrier that surrounded the dragon pen (odds ratio = 4.0, 95% CI 1.2 to 13.9). Washing hands at the zoo after visiting the dragons was highly protective (OR = 0.14, 95% CI 0.03 to 0.7). Cultures from the patients, one dragon, and the exhibit barriers yielded Salmonella Enteritidis, phage type 8. On the basis of an attack rate of 4.3% among exhibit attendees under 13 years old on whom data were collected, we estimate that 315 additional cases of salmonellosis occurred among visitors in this age group. CONCLUSION: This large outbreak demonstrates the importance of environmental contamination in the transmission of Salmonella from reptiles, and the protective value of hand washing. Recommendations regarding reptile exhibits and reptilian pets should emphasize this indirect route.

Adolescent↗
PubMed1998

Indoor use of concrete saws and other gas-powered equipment. Analysis of reported carbon monoxide poisoning cases in Colorado.

Poisoning due to "non-automobile" gas-powered engines accounts for the largest proportion of occupational carbon monoxide (CO) poisonings in Colorado workers. The present analysis was undertaken to characterize the problem and develop prevention strategies. Cases of occupational CO poisoning were identified from Colorado's population-based surveillance system for unintentional CO poisonings. For cases poisoned by "non-automobile" gas-powered engines, medical records were obtained. Results showed that almost all of the poisonings from these engines occurred indoors or in an enclosed space. Concrete saws were the most frequent source of poisoning. When compared with operators of other equipment, concrete saw operators had shorter durations of exposure to CO but generally experienced more severe symptoms and signs of poisoning. These results underscore the hazard associated with the indoor use of any gas-powered equipment; however, operators of concrete saws may receive a higher dose of CO.

Air Pollution, Indoor↗
PubMed1998

"Lifeguard lung": endemic granulomatous pneumonitis in an indoor swimming pool.

OBJECTIVES: Two sequential outbreaks of respiratory disease among lifeguards at an indoor swimming pool with water spray features were investigated. METHODS: Questionnaires were administered to recreation center employees following each outbreak. Respondents reporting 2 or more pool-related symptoms were offered clinical evaluation, including bronchoscopy with bronchoalveolar lavage and transbronchial biopsy. Pool air and water were sampled for fungi, bacteria, amoebae, endotoxin, and respirable particulates. RESULTS: Thirty-three lifeguards had noncaseating granulomas on biopsy and/or bronchoalveolar lavage lymphocytosis. Attack rates for the outbreaks were 27% and 65%. Case patients had higher cumulative hours of work and tended to work more hours per week. Analyses indicated increased levels of endotoxin in pool air and water (relative to control pools) and gram-negative bacterial colonization of water sprays. Use of water spray features generated a 5.2-fold increase in the number of respirable particles and up to an 8-fold increase in air endotoxin levels. CONCLUSIONS: Lifeguards in this indoor swimming pool developed granulomatous lung disease associated with endotoxin-containing respirable bioaerosols from water spray features, which ventilation system improvements did not prevent.

Adolescent↗
PubMed1998

Nocturnal elevation of intraocular pressure in young adults.

PURPOSE: To distinguish 24-hour (circadian) and postural effects on intraocular pressure (IOP) in healthy young adults. METHODS: Thirty-three volunteers were housed in a sleep laboratory for 1 day under a strictly controlled 16-hour light and 8-hour dark environment. Sleep was encouraged in the dark period. Intraocular pressure was measured in each eye every 2 hours using a pneumatonometer. Researchers used night-vision goggles to perform IOP measurements in the dark, while the subject's light exposure was minimized. In the first group of 12 subjects, measurements were taken with subjects in the sitting position during the light-wake period and supine during the dark period. In the second group of 21 subjects, all IOP measurements were taken with the subjects supine. RESULTS: Average IOP was significantly higher in the dark period than in the light-wake period in both groups. The lowest IOP occurred in the last light-wake measurement, and the peak IOP occurred in the last dark measurement. The trough-peak difference in IOP was 8.2+/-1.4 mm Hg (mean +/- SEM) in the first group. Intraocular pressure changed sharply at the transitions between light and dark. In the second group, the trough-peak IOP difference was 3.8+/-0.9 mm Hg. Intraocular pressure changed gradually throughout the 24-hour period. In comparison with the sitting IOP in the first group, the supine IOP in the second group was significantly higher during the light-wake period. CONCLUSIONS: Circadian rhythms of IOP were shown in young adults, with the peaks occurring in the late dark period. A nocturnal IOP elevation can appear independent of body position change, but change of posture from upright to recumbent may contribute to the relative nocturnal IOP elevation.

Adolescent↗
PubMed1997

Pyrogenic reactions in patients undergoing cardiac catheterization associated with contaminated glass medicine cups.

Pyrogenic reactions are potentially life-threatening complications caused by bacterial endotoxin. After two cardiac catheterization patients developed rigors the same day, the procedures were halted and a case control study was conducted. To identify case patients (persons with rigors < or = 3 hr after catheterization during September 25-November 9, 1995), we reviewed medical records of all cardiac catheterization patients who had a blood culture or received intravenous meperidine. Twelve case patients and 40 randomly selected control patients were identified. No specific catheter was associated with case patients, but exposure to intracoronary-nitroglycerin (NTG) was (odds ratio = 12.0; 95% confidence interval 2.2, 75.6). NTG or indocyanine green dye was poured into glass medicine cups previously washed in an enzyme cleaner and then sterilized. The cleaner, used for an entire day, had elevated levels of gram-negative bacteria (> 10(4) colony forming units/mL) and endotoxin (434 endotoxin units [EU]/mL]); the reprocessed cups had no live bacteria but had elevated endotoxin levels (median 2,250 EU). Exposure to contaminated glass medicine cups probably resulted in pyrogenic reactions and contributed to death in two critically ill patients.

Aged↗
PubMed1997

Urban and rural traumatic brain injuries in Colorado.

PURPOSE: The purpose of this study was to compare and contrast the epidemiology of traumatic brain injury among urban and rural residents of Colorado. METHODS: Cases of traumatic brain injury (ICD 800, 801, 803, 804, 850-854) for 1991 and 1992 from the Colorado surveillance system of hospitalized and fatal traumatic brain injuries were used. Urban cases resided in counties designated by the U.S. Census Bureau as metropolitan statistical areas (MSA). Rural cases were divided into two groups: "rural, nonremote," if the country of residence was adjacent to an MSA county or if it had a population of 2500, and "rural, remote," if not. RESULTS: Average annual age-adjusted rates of hospitalized and fatal traumatic brain injury varied significantly from 97.8 per 100,000 population for the most urban group to 172.1 per 100,000 population for the residents of rural, remote counties. Similarly, total mortality ranged from 18.1 per 100,000 population among residents of the most urban counties to 33.8 among residents of rural, remote counties. Prehospital mortality ranged from 10.0 to 27.7 traumatic brain injuries per 100,000 population. CONCLUSIONS: These results provide justification for expanding efforts to prevent traumatic brain injury to include the small, but high-risk group of residents in rural areas.

Adolescent↗
PubMed1997

Recurrent personal memories during intoxication reported by patients with alcoholism.

BACKGROUND: Experimental studies have demonstrated that alcohol has state-dependent effects on learning and memory. We, therefore, sought to determine if alcohol intoxication triggers selective retrieval of memories which could alter patterns of alcohol use. METHODS: Eighteen alcoholic patients were studied as well as a comparison group of 12 patients who abused cocaine, a drug not associated with memory state-dependence. Patients underwent a semi-structured interview to elicit information about recurrent personal memories experienced when intoxicated. Recurrent memories experienced during craving were also studied as a comparison condition. RESULTS: The prevalence of recurrent personal memories during intoxication was reported to be much higher for alcoholic patients compared with the cocaine-abusing patients. These experiences occurred more frequently than during craving, generally reflected prior disturbing events and were often reported to promote continued drinking. CONCLUSIONS: The association of recurrently experienced personal memories with intoxication in alcoholic patients suggests, but does not establish, pharmacological state-dependence. Further studies of this memory phenomenon are indicated.

Adult↗
PubMed1997

Blood lead levels in radiator repair workers in Colorado.

A laboratory-based blood lead surveillance system in Colorado identified radiator repair workers as having the highest blood lead levels of all worker groups reported. A survey of 42 radiator repair shops in ten locales throughout Colorado was undertaken to estimate the prevalence of workers with elevated blood lead levels > 25 micrograms/dL. The survey was designed to test the sensitivity of the surveillance system and to assess working conditions and practices in the radiator repair industry in Colorado. Of 63 workers, 39 (62%) had blood lead levels > 25 micrograms/dL. The sensitivity of the surveillance system for detecting radiator repair workers with elevated blood lead levels was estimated at 11%. None of the radiator repair shops had adequate local exhaust ventilation. Work practice and engineering modifications are needed to reduce lead exposure in this industry.

Adult↗
PubMed1997

Synaptic elimination, neurodevelopment, and the mechanism of hallucinated "voices" in schizophrenia.

OBJECTIVE: After peaking during childhood, synaptic density in the human frontal cortex declines by 30%-40% during adolescence because of progressive elimination of synaptic connections. The characteristic age at onset of schizophrenia--late adolescence and early adulthood--suggests that the disorder could arise from irregularities involving this neurodevelopmental process. METHOD: A computer simulation of a speech perception neural network was developed. Connections within the working memory component of the network were eliminated on the basis of a "Darwinian rule" in order to model loss of synapses. As a comparison, neuronal cell death, also postulated as being linked to both neurodevelopment and schizophrenia, was simulated. The authors determined whether these alterations at low levels could enhance perceptual capacity and at high levels produce spontaneous speech percepts that simulate hallucinated speech or "voices." RESULTS: Eliminating up to 65% of working memory connections improved perceptual ability; beyond that point, network performance declined and speech hallucinations emerged. Simulating excitotoxic neuronal loss at low levels also improved network performance, but in excess it did not produce hallucinations. CONCLUSIONS: The model demonstrates perceptual advantages of selective synaptic elimination as well as selective neuronal loss, suggesting a functional explanation for these aspects of neurodevelopment. The model predicts that psychosis arises from a pathological extension of one of these neurodevelopmental trends, namely, synaptic elimination.

Auditory Perception↗
PubMed1997

Cognition, negative symptoms, and diagnosis: a comparison of schizophrenic, bipolar, and control samples.

Forty-six schizophrenic, 22 bipolar, and 26 normal control subjects were administered negative and positive symptoms scales and tests of cognitive function. Test performance was related to diagnosis and to positive and negative symptom ratings within the schizophrenic group. Bipolar patients were significantly superior in cognitive status when compared with all schizophrenic patients, but less so when compared only with those who did not have key negative symptoms (affective nonresponsivity and poverty of speech). The schizophrenic patients with negative symptoms displayed severe impairment, performing significantly worse than the control, bipolar, and other schizophrenic subjects. Negative symptoms thus are significantly implicated in the cognitive inferiority of schizophrenic to bipolar patients. Although the data suggest bipolar patients may also have cognitive deficiencies, these findings are inconclusive and require cross-validation.

Adult↗
PubMed1996

The cost of a food-borne outbreak of hepatitis A in Denver, Colo.

BACKGROUND: In 1992, a food-borne outbreak of hepatitis A associated with a catering facility in Denver, Colo, resulted in 43 secondary cases of hepatitis A and the potential exposure of approximately 5000 patrons. OBJECTIVES: To assess (1) disease control costs, including state and local health department personnel costs, provision and administration of immune globulin, and cost of extra hepatitis A serologic tests performed; (2) business losses; and (3) cost of the cases' illnesses. METHODS: Cost data were collected from hospitals, health maintenance organizations, health departments, laboratories, the caterer's insurance company, and the catering facility involved in the outbreak. RESULTS: The total costs assessed in the outbreak from a societal perspective were $809,706. Disease control costs were $689,314, which included $450,397 for 16,293 immune globulin injections and $105,699 for 2777 hours of health department personnel time. The cases' medical costs were $46,064, or 7% of the disease control costs. CONCLUSIONS: The cases' medical costs and productivity losses were only a minor component of the total cost of this outbreak. The high cost of food-borne outbreaks should be taken into account in economic analyses of the vaccination of food handlers with inactivated hepatitis A vaccine.

Colorado↗