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Biomedical subjects

R E Hoffman

Publications and source records attributed to R E Hoffman.

At least 55 records · Page 3Linked to original sources
PubMed1996

Working memory, attention, and communication disturbances in schizophrenia.

The authors hypothesized that schizophrenic communication disturbances reflect specific cognitive deficits in the areas of working memory and attention. They examined the cognitive correlates of communication disturbances, as measured by linguistic reference performance, in schizophrenic (n = 48), bipolar (n = 24), and nonpsychiatric control (n = 23) individuals. Reference performance ratings in the schizophrenic patients were associated with scores on tests of working memory and attention and were not related to performance on concept formation or verbal fluency tests. In contrast, in the bipolar and nonpsychiatric individuals, reference performance was associated with concept formation and verbal fluency test scores but was not related to performance on tests of working memory. Implications with respect to the processes underlying schizophrenic communication disturbances are discussed.

Adult↗
PubMed1996

Liquid ventilation in premature lambs: uptake, biodistribution and elimination of perfluorodecalin liquid.

Perfluorochemical (PFC) liquids are biologically inert and nonbiotransformable substances that, when used as breathing medium, may be transported across the lung epithelium in small quantities, distributed throughout the body, and ultimately vapourized through the lungs and transpired through the skin. To further evaluate the uptake, biodistribution and elimination of a PFC liquid (perfluorodecalin) in the neonatal population, arterial blood, tissue and expired gas samples were obtained from preterm lambs (105-114 days gestation). Two groups of premature lambs were studied: Group I (n = 4) lambs were liquid ventilated from birth for 1 h and killed without exposure to gas ventilation (GV) and Group II (n = 5) lambs were liquid ventilated for 1 h followed by up to 2 h of GV. Samples were analysed by electron-capture gas chromatography and data were expressed in nl of PFC/ml of blood or gas and nl of PFC/gm tissue. During liquid ventilation and subsequent GV, PFC blood levels significantly increased (P < 0.001) from baseline control levels (0.007 +/- 0.001 SE nl PFC/ml blood) to a high of 2.95 +/- 1.03 SE nl PFC/ml blood. Perfluorochemical levels measured in expired gas (Group II) demonstrated a rapid decrease as a function of time of GV. Tissue levels of PFC indicated that uptake of PFC in Group I was significantly different (P < 0.001) than baseline levels and organ dependent; the highest levels were in the lungs (221 +/- 26.2 SE nl PFC/g tissue) and the lowest in the liver (2.24 +/- 1.6 SE nl PFC/g tissue). Comparison of tissue levels of PFC between groups indicated a 34.8% mean decrease across organs in Group II compared with Group I. These data indicate that PFC uptake and elimination is organ dependent and that PFC liquids can be eliminated through the lungs upon return to GV. Sustained PFC blood levels may be related to residual PFC in the organs and lung as well as regional variation in ventilation-perfusion matching upon return to GV.

Analysis of Variance↗
PubMed1996

Naltrexone as a treatment for repetitive self-injurious behaviour:an open-label trial.

BACKGROUND: Repetitive self-injurious behavior (SIB) is a dangerous and often treatment-refractory syndrome encountered frequently in clinical practice. The authors sought to determine if oral naltrexone could decrease SIB in a sample of adult psychiatric patients. METHOD: Seven female patients with SIB accompanied by analgesia and dysphoria reduction were administered oral naltrexone (50 mg/day) in an open-label trial. All patients demonstrated persistent and clinically significant SIB prior to receiving the drug. Mean follow-up period was 10.7 weeks. RESULTS: SIB in six of seven patients ceased entirely during naltrexone treatment. Two patients who discontinued naltrexone briefly experienced the rapid resumption of SIB, which again ceased after resumption of naltrexone therapy. One patient exhibited superficial cutting on two occasions while receiving naltrexone, a rate that reflected a significant reduction of SIB. CONCLUSION: These preliminary observations are consistent with the hypothesis that the endogenous opioid system is involved in cases of SIB that are accompanied by analgesia and dysphoria reduction. Additional placebo-controlled studies that explore the effectiveness of naltrexone in treating patients with this syndrome are warranted.

Adolescent↗
PubMed1995

Comparison of partner notification at anonymous and confidential HIV test sites in Colorado.

We compared health department-initiated partner notification at a single anonymous human immunodeficiency virus (HIV) test site in Denver to 13 confidential HIV test sites throughout Colorado over an 18-month period. The average number of named, notified, and counseled in-state partners was from 30 to 50% greater among confidential site index cases than anonymous site index cases, and the seropositivity rate in newly tested partners of confidential site index cases was more than twice the rate in partners of anonymous test site index cases. When analyses were restricted to gay/bisexual male index cases, the results were the same as for the total group. We recommend that state and local health departments collect data to evaluate and improve the delivery of partner notification services.

AIDS Serodiagnosis↗
PubMed1995

Can digit symbol-verbal fluency comparisons facilitate detection of pseudodementia? A preliminary study.

Depressive psychomotor retardation may impair performance on timed tests. By comparison word association measures of verbal fluency are reportedly unaffected by depression. Comparisons of a brief psychomotor test with a measure of verbal fluency may therefore prove useful when there is a concern that depression may be undermining adaptive functioning, assuming both measures display: (1) broad-spectrum sensitivity to brain impairment, (2) differential vulnerability to depression, and (3) moderate correlation in nondepressed persons. Digit Symbol (DS) and the "FAS" measure of verbal fluency are sensitive to genuine dementia, satisfying the first criterion. We found that depressed schizophrenics performed at significantly lower levels on DS, but not on FAS, than nondepressed schizophrenics. The two groups differed significantly on a discrepancy score derived by subtracting FAS from DS scores; normals obtained discrepancy scores highly similar to those of nondepressed schizophrenics. As the normals had higher DS and FAS scores, this discrepancy-score similarity suggests that this index may have wide application. The third criterion is satisfied by the findings of a 0.64 correlation between DS and FAS scores adjusted for age (DS and FAS) as well as gender and educational attainment (FAS) in nondepressed samples. Implications for further research and clinical applications are discussed.

Adult↗
PubMed1995

Relationship of helmet use and head injuries among motorcycle crash victims in El Paso County, Colorado, 1989-1990.

A case-control study was conducted in El Paso County, Colorado to estimate differences in risk of head injury among persons in motorcycle crashes who were or were not wearing helmets. There were 71 cases, motorcyclists with head injuries from crashes, and 417 controls, motorcyclists in crashes without head injuries. Motorcyclists not wearing helmets were 2.4 times as likely to sustain head injuries (95% confidence limits: 1.23, 4.70) than motorcyclists wearing helmets. This odds ratio was adjusted for age and crash characteristics, using logistic regression. Alcohol intoxication and severity of motorcycle damage were also associated with significantly elevated odds ratios related to sustaining a head injury.

Accidents, Traffic↗
PubMed1995

Nonlinear sequence-dependent structure of nigral dopamine neuron interspike interval firing patterns.

Firing patterns of 15 dopamine neurons in the rat substantia nigra were studied. These cells alternated between two firing modes, single-spike and bursting, which interwove to produce irregular, aperiodic interspike interval (ISI) patterns. When examined by linear autocorrelation analysis, these patterns appeared to reflect a primarily stochastic or random process. However, dynamical analysis revealed that the sequential behavior of a majority of these cells expressed "higher-dimensional" nonlinear deterministic structure. Dimensionality refers to the number of degrees of freedom or complexity of a time series. Bursting was statistically associated with some aspects of nonlinear ISI sequence dependence. Controlling for the effects of nonstationarity substantially increased overall predictability of ISI sequences. We hypothesize that the nonlinear deterministic structure of ISI firing patterns reflects the neuron's response to coordinated synaptic inputs emerging from neural circuit interactions.

Action Potentials↗
PubMed1995

Utilization and effectiveness of methylprednisolone in a population-based sample of spinal cord injured persons.

The announcement and publication of the second National Acute Spinal Cord Injury Study (NASCIS II) project's findings regarding the role of high dose methylprednisolone in improving neurological outcomes following acute traumatic spinal cord injury generated widespread excitement and interest. To determine the association between this interest and actual use and implementation of the protocol, Colorado's comprehensive population-based spinal cord injury surveillance data were examined. The medical records of 218 SCI survivors injured between May 1, 1990 and December 31, 1991, and of 145 persons spinal cord injured 2 years later, during 1993, were reviewed to determine the rapidity and extent of NASCIS II implementation by Colorado's hospitals, factors associated with use and non-use of the protocol, changing usage trends over time, and the short term neurological outcomes of patients who received the protocol. Clear documentation of the protocol's usage was present for only 46% of the reported patients' medical records in 1990-91, and 61% in 1993. Small, emergency triage facilities were significantly more likely to use the protocol than larger acute care hospitals, and patients with initially incomplete injuries were less likely to receive the drug. There were no significant differences in neurological outcomes, using the Frankel classification system, between those who received the protocol and those who did not. The limitations and implications of these findings are discussed.

Humans↗
PubMed1995

Unintentional carbon monoxide poisoning in Colorado, 1986 through 1991.

Unintentional carbon monoxide poisonings were identified through death certificates, by hyperbaric chambers, and by laboratories required to report carboxyhemoglobin levels greater than 12%. From 1986 to 1991, 981 cases were reported, including 174 deaths. Deaths most often resulted from fire-related carbon monoxide intoxication (36.2%), followed by motor vehicle exhaust (34.5%), and furnaces (10.3%). Among nonfatal cases, furnaces were the leading source of carbon monoxide exposure (44.3%), followed by motor vehicle exhaust (22.8%). The importance of furnaces and other home heating devices in carbon monoxide intoxication may be underappreciated if only mortality data are examined. Surveillance of carbon monoxide-related morbidity is a useful adjunct to mortality surveillance in guiding prevention efforts.

Accidents↗
PubMed1994

Occupational exposure to human immunodeficiency virus (HIV)-infected blood in Denver, Colorado, police officers.

The authors undertook a study of Denver, Colorado, police department officers to measure their risk of exposure to blood and human immunodeficiency virus (HIV) by type of work assignment and to document how exposures occurred. From December 1989 through March 1991, 137 officers reported an exposure to either blood or saliva, and 42 exposures to blood were independently documented. The overall rate of exposure to HIV-infected blood for medium and high risk assignments was 0.10 per 10,000 person-days. Thirty-two source persons underwent voluntary testing for HIV antibodies, and five (15.6%) were seropositive. Two thirds of the 42 blood exposures occurred in circumstances in which 1) there was little or no time for the officer to put on protective gloves and clothing because the officer was restraining or being assaulted by a suspect or 2) gloves would have not been protective because of penetration by needles. The authors conclude that Denver police officers rarely have percutaneous or mucosal exposures to blood, but when they do, the risk of exposure to HIV-infected blood is quite high. A health department can provide to police officers a number of services: evaluation of an incident involving contact with blood or body fluids to determine whether there was potential for disease transmission; information about modes of transmission and prevention of bloodborne diseases; serologic testing of source persons; HIV counseling for exposed officers and source persons; documentation for worker's compensation claims; and consultation regarding the use of zidovudine for postexposure prophylaxis.

Adolescent↗
PubMed1994

Corticocortical connectivity, autonomous networks, and schizophrenia.

Dr. David hypothesizes that increased, not decreased, corticocortical connectivity causes schizophrenia. He cites studies suggesting excessive semantic priming and cross-hemispheric interference in this disorder to support his hypothesis. These findings, David suggests, reflect excessive transmission of information between neurons or within neural systems. However, considerable caution should be exercised in making neuroanatomic inferences on the basis of cognitive studies alone. There is an increasing consensus that information is represented by the brain as patterns of neural activation, where the same neuron or group of neurons participates in many different representations. Our simulations, which reflect this consensus, suggest that persistent or intrusive activation patterns do not emerge from too many neural connections, but from too few. This condition causes subgroups of neurons to disregard information processing by other neurons and to produce autonomously their own output, which interferes with the functioning of the system as a whole. Direct neuroanatomic or neurochemical studies of the cerebral cortex are needed to fully assess hypotheses regarding abnormal corticocortical connectivity in schizophrenia.

Brain Mapping↗
PubMed1994

Semantic organization of hallucinated "voices" in schizophrenia.

The authors found that the different hallucinated "voices" of four schizophrenic subjects reported over 1-3 weeks expressed semantic content that was at least as persistent as clauses sampled from single 5-7-minute conversational discourses of four comparison speakers. The high degree of semantic recurrence of voices from one day to the next may contribute to the mistaken belief that these experiences derive from a particular nonself agent or speaker.

Adult↗
PubMed1994

Risk factors for delayed immunization against measles, mumps, and rubella in Colorado two-year-olds.

OBJECTIVES: 1) To examine a wide range of potential risk factors for delayed childhood immunization against measles, mumps, and rubella and 2) to determine the parental response to proposed solutions regarding the problem of delayed childhood immunization. DESIGN: A case-control study in which subjects had (controls) or had not (cases) received measles, mumps, and rubella vaccine (MMR) by 2 years of age. Parents of subjects were also surveyed to find out whether they thought selected proposals to improve immunization rates would be successful. RESULTS: Maternal education of high school or less at the time of the child's birth, more than or equal to two moves between birth and age 2, maternal age < 21 years of age at the time of the child's birth, more than or equal to two older siblings, participation in The Special Supplemental Food Program for Women, Infants, and Children (WIC), participation in the federal food stamp program, and incorrect knowledge of the recommended age for MMR significantly elevated the odds ratio (OR) for delayed immunization. At least two older siblings (OR = 3.2), maternal age < 21 years of age at the time of the child's birth (OR = 2.8), and incorrect knowledge of the recommended age for MMR (OR = 2.7) remained significant risk factors in a multivariate logistic regression model. Insurance status and cost factors were not significant risk factors for delayed immunization. Parents though that reminders for immunization and a central record system would have made obtaining immunizations easier. CONCLUSIONS: Based on our findings of the importance of immunization knowledge and demographic characteristics as risk factors for delayed immunization, we suggest that a message (the recommended age for immunizations) and a target group for that message (families who move frequently, have older children, and are headed by younger parents) be evaluated as an intervention to improve immunization rates.

Adult↗
PubMed1993

Assessment of blood lead levels in children living in a historic mining and smelting community.

Lead poisoning in childhood is an important public health problem, and thus, it is important to determine how children are exposed to lead. In 1987, the authors conducted an exposure assessment and blood lead screening for children aged 6-71 months living in Leadville, Colorado. High levels of lead had been found in the soil as a result of both past mining and smelting activities and natural mineralization. Blood was collected from each child for lead analysis, and behavioral characteristics were identified through an interview with a parent or guardian. Three sources of exposure to lead were associated with blood lead levels: lead in a core sample taken from the backyard of the family's home, lead brought home on the clothes of a miner, and lead from soldering in the home. Two pathways of exposure were associated with blood lead levels: the child swallowing things other than food, and taking food or a bottle outside to play. Multivariate regression using these variables found effect modification by age. For children aged 6-36 months, only sources of exposure were independent predictors of blood lead levels, while in children aged 37-71 months, a pathway of exposure in addition to sources of exposure independently predicted blood lead levels.

Child↗
PubMed1993

Use of polymerase chain reaction in an epidemiologic investigation of Pontiac fever.

In June 1992, 13 (38%) of 34 resort guests experienced illness that met a symptom-based case definition of Pontiac fever. Each ill guest reported using an indoor hot tub compared with 6 (29%) of 21 nonill guests (P < .001). Water samples from the indoor hot tub were culture-negative for legionellae using standard techniques, coculture with amebae, and intraperitoneal inoculation of guinea pigs. However, polymerase chain reaction (PCR) testing of the water samples indicated the presence of Legionella pneumophila. Direct fluorescent antibody testing identified the organism as serogroup 6. Seroconversion to L. pneumophila serogroup 6 occurred in 7 (64%) of 11 ill guests and none of 5 nonill guests (P = .03). These results suggest that in certain circumstances, culture of environmental samples should be supplemented with additional tests such as PCR. These results are also consistent with the concept that Pontiac fever can be caused by nonviable legionellae.

Animals↗
PubMed1993

Parallel distributed processing and the emergence of schizophrenic symptoms.

Computer simulations of parallel distributed processing (PDP) neural networks have increased our understanding of brain functioning. This article reviews how PDP concepts can contribute to our understanding of schizophrenic symptoms. Psychotic states induced by phencyclidine and the adult form of metachromatic leukodystrophy, as well as neurometabolic studies, suggest that schizophrenia reflects a breakdown in communication between cortical areas. A computer simulation of this type of brain pathology has suggested two neurocognitive consequences: some cortical circuits will become functionally autonomous, and a subset of these circuits will yield "parasitic foci" that slavishly reproduce the same cognitive output. Delusions of control, paranoid delusions of the idee fixe type, thought broadcasting, "voices," and certain deficit symptoms are postulated outcomes of parasitic foci located at different levels of language processing. A neurodevelopmental model of impaired corticocortical communication is described, and this model's implications for further study are outlined.

Attention↗