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Biomedical subjects

R E Hoffman

Publications and source records attributed to R E Hoffman.

At least 73 records · Page 4Linked to original sources
PubMed1993

Neurodynamics and schizophrenia research: editors' introduction.

The term, "neurodynamics," refers to interactions of large numbers of neurons that, in the short term, transform input information derived from their environments into meaningful outputs and, in the long term, use this information to alter their own architectures. This general concept may be useful in framing and investigating research questions that could advance our understanding of the nature, course, and treatment of schizophrenia. The mechanism of action of neuroleptics, the anatomic localization of schizophrenia, the stability of associated brain disturbances over time, and the distinction of state versus trait variables are briefly discussed as examples of issues whose understanding may be enhanced by a neurodynamic perspective.

Brain↗
PubMed1993

Language therapy for schizophrenic patients with persistent 'voices'.

One of us has hypothesised that the 'voices' of schizophrenic patients reflect altered preconscious planning of discourse that can produce involuntary 'inner speech' as well as incoherent overt speech. Some schizophrenic patients reporting voices do not, however, have disorganised speech. We hypothesise that these 'counterexample' patients compensate for impairments of discourse planning by reducing language complexity and relying on highly rehearsed topics. A 'language therapy' designed to challenge and enhance novel discourse planning was administered to four such patients; three had significant albeit temporary reductions in the severity of their voices. These clinical findings provide further evidence that alterations of discourse planning may underlie hallucinated voices.

Adult↗
PubMed1993

Building-related asthma in Denver office workers.

OBJECTIVES: Reported cases of building-related asthma and hypersensitivity pneumonitis among workers in a Denver office building prompted an epidemiologic investigation. METHODS: A cross-sectional, self-administered survey of employees in the office building of the reported cases was compared with that of employees in a comparison building. RESULTS: A significant excess of respiratory disease existed among 512 Denver workers (case building) compared with 281 office workers in a suburban agency (control building). Denver employees had a higher prevalence of respiratory symptoms, and the prevalence of physician-diagnosed asthma with onset or exacerbation since building occupancy was 4.9 times greater for Denver employees than for suburban employees. Asthma was not associated with any particular ventilation system in the building. Water incursion from a below-grade wall may have contributed to the problem, but the etiology is unknown. CONCLUSIONS: This investigation provided evidence of office building-related asthma. Individual cases may be sentinel events for other cases of work-related asthma or hypersensitivity pneumonitis and may indicate a need for public health investigation of remediable causes.

Adult↗
PubMed1991

The Duphar Lecture: on the etiology of alien, nonself attributes of schizophrenic 'voices'.

The etiology of schizophrenic hallucinations of 'voices' remains unknown. The following is a discussion of a hypothesis linking these hallucinatory phenomena to a disruption in discourse planning. The relationship between normal imagery and hallucination is discussed. The concept of 'alien intentionality' is introduced, and a theoretical argument is presented which links this phenomenon with the exteriorization of internal images. Statistical data linking discourse planning disruptions and schizophrenic data are reviewed, and a description of the treatment of a hallucinating schizophrenic via a novel type of speech therapy is described.

Auditory Perceptual Disorders↗
PubMed1991

EEG coherence of prefrontal areas in normal and schizophrenic males during perceptual activation.

Multiple studies have demonstrated prefrontal dysfunction among schizophrenics. The prefrontal cortex does not function in isolation, but instead relies on extensive connections with other brain areas. Functional relationships between cortical areas were assessed by calculating the coherences between different scalp electroencephalogram (EEG) signals recorded from 13 unmedicated male patients with schizophrenia and 9 normal male subjects. Alpha-band coherences linked to prefrontal areas in schizophrenic patients were about the same as those of normal controls when subjects were cognitively "at rest," but they were reduced for certain electrode pairs in the former group when performing the degraded-stimulus continuous performance test. Most of these findings were not accounted for by changes in alpha power, suggesting that "cortical circuits" extending beyond prefrontal areas may be disrupted in schizophrenia.

Adult↗
PubMed1991

A measles outbreak at a college with a prematriculation immunization requirement.

BACKGROUND: In early 1988 an outbreak of 84 measles cases occurred at a college in Colorado in which over 98 percent of students had documentation of adequate measles immunity (physician diagnosed measles, receipt of live measles vaccine on or after the first birthday, or serologic evidence of immunity) due to an immunization requirement in effect since 1986. METHODS: To examine potential risk factors for measles vaccine failure, we conducted a retrospective cohort study among students living in campus dormitories using student health service vaccination records. RESULTS: Overall, 70 (83 percent) cases had been vaccinated at greater than or equal to 12 months of age. Students living in campus dormitories were at increased risk for measles compared to students living off-campus (RR = 3.0, 95% CI = 2.0, 4.7). Students vaccinated at 12-14 months of age were at increased risk compared to those vaccinated at greater than or equal to 15 months (RR = 3.1, 95% CI = 1.7, 5.7). Time since vaccination was not a risk factor for vaccine failure. Measles vaccine effectiveness was calculated to be 94% (95% CI = 86, 98) for vaccination at greater than or equal to 15 months. CONCLUSIONS: As in secondary schools, measles outbreaks can occur among highly vaccinated college populations. Implementation of recent recommendations to require two doses of measles vaccine for college entrants should help reduce measles outbreaks in college populations.

Adolescent↗
PubMed1990

The use of hygiene, cohorting, and antimicrobial therapy to control an outbreak of shigellosis.

Shigellae are easily transmitted in day-care centers to children and adult staff by contamination of diaper-changing surfaces and fomites or directly from person to person. Appropriate antimicrobial therapy may shorten the duration of diarrhea caused by shigellae and eliminate the organism from the feces. Current recommendations of the American Academy of Pediatrics and the American Public Health Association are that infected children be isolated until three and two, respectively, consecutive stool cultures are negative. We utilized a disease control strategy based on use of antibiotics to control diarrheal symptoms and reduce infectiousness, cohorting of asymptomatic infected children in the center, and scrupulous attention to hygiene and environmental cleanliness. This strategy was effective in stopping transmission, was more practical than some of the measures now recommended by the American Academy of Pediatrics and the American Public Health Association, and was well accepted by parents and center staff. The strategy should be evaluated in other day-care settings.

Adult↗
PubMed1990

Effects of long-term psychiatric hospitalization for young, treatment-refractory patients.

Although short-term hospitalization has been shown to be effective in helping severely impaired psychiatric patients improve, such improvement is for some only temporary. Young, treatment-refractory patients who have failed to respond to previous brief hospitalization and outpatient treatments may benefit more from longer-term hospitalization. The authors report on a three-and-a-half-year follow-up study of 55 young adult and adolescent treatment-refractory inpatients after long-term hospitalization. Significant improvements in recidivism, quality of life, and overall functioning were found between discharge and the follow-up assessment. The authors conclude that potential benefits of long-term hospitalization for this subgroup warrant further empirical study.

Adolescent↗
PubMed1989

Diminished thymosin alpha-1 levels in persons exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

There is evidence from animal studies that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) impairs immune responses, with the thymus being a principal target organ. The purpose of this study was to evaluate thymic function, through measurement of thymic hormone levels, in persons exposed to TCDD. We examined thymosin alpha-1 (Thya-1) levels in sera from a group of 94 persons who were presumed to be exposed to TCDD from living, working, or recreating in a contaminated residential area. We compared these results, along with results from in vitro and in vivo tests of immune function, with those from a group of 105 unexposed persons who were similar with regard to age, sex, and race. The exposed group had a significantly lower mean Thya-1 serum level (977.3 +/- 304.1 pg/ml vs. 1148.7 +/- 482.1 pg/ml, p less than .01 by t-test). We also found a statistically significant trend of decreasing Thya-1 levels with increasing number of years of residence in the TCDD-contaminated area. However, Thya-1 levels were not associated with other measures of immune function in the TCDD-exposed group. Thus, while the principal findings suggest that long-term TCDD exposure may be associated with diminished secretion of Thya-1, the lack of an association with an increased prevalence of clinically diagnosed immune suppression in these TCDD-exposed persons makes the biologic significance of the findings unclear. Further studies are needed to more fully evaluate possible long-term TCDD-induced effects on the thymus and human immune function.

Age Factors↗
PubMed1989

Cortical pruning and the development of schizophrenia: a computer model.

Schizophrenic patients tend to demonstrate reduced cerebral metabolism in frontal areas. Studies of human brain development reveal that synapses in the cerebral cortex are progressively reduced throughout childhood and adolescence, with parallel reductions in cerebral metabolism. This relationship is not surprising, since synaptic density is a primary factor determining regional metabolic requirements. The elimination of synapses in prefrontal cortex continues for a particularly long period of time, extending well into adolescence. Thus, reduced frontal metabolism in schizophrenic patients could be due to a developmental process--namely, elimination of synapses--gone too far. Animal studies indicate that developmentally induced reductions in synaptic density are due to the pruning of axonal collaterals rather than the death of neurons, which raises a critical question: Does excessive axonal pruning have specific pathological effects on cortical information processing? To answer this question, computer simulations of neural information processing systems were subjected to axonal pruning which reduced synaptic density. If pruning was conducted overzealously, cognitive pathology was induced that could, in humans, lead to the conscious experience of hallucinations, delusions, and Schneiderian symptoms.

Adolescent↗
PubMed1989

Comparison of AIDS and HIV antibody surveillance data in Colorado.

We compared cumulative surveillance data for AIDS (May 1982-December 1986) and persons with positive HIV antibody tests (July 1985-December 1986) to examine the adequacy of each surveillance system in directing public health disease control activities. Neither AIDS nor HIV antibody surveillance data alone described the total extent of HIV infection. The geographic distribution of persons with positive HIV antibody tests was more widespread than the distribution of AIDS cases for all demographic and transmission categories. Ideally, preventive efforts should be based on a comprehensive surveillance system that indicates all persons who are infectious with HIV.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Experimental evaluation of perfluorophenanthrene as a high specific gravity vitreous substitute: a preliminary report.

Perfluorophenanthrene, a liquid fluorocarbon with a specific gravity approximately twice that of water, potentially offers certain advantages as a vitreous substitute in vitreoretinal surgery. To determine its efficacy and safety we first purified it by chemical methods used in the preparation of experimental blood substitutes to a level at which it was not at all or only minimally toxic to culture-grown retinoblastoma cells. Nineteen of 22 vitrectomized eyes of white New Zealand rabbits injected with this purified perfluorophenanthrene showed satisfactory clinical tolerance. Light and electron microscopy showed minimal or no toxic effects in the 19 eyes, although uptake of perfluorophenanthrene by some preretinal cells was observed 28 days after implantation. Postoperative light-adapted electroretinography recordings of eight of the injected eyes showed no significant change. Perfluorophenanthrene injected into the anterior chamber of the rabbit eyes had toxic effects on the cornea. If further experimentations confirm our findings, perfluorophenanthrene may be a suitable transparent high-density liquid for temporary use in surgery to repair retinal detachments.

Animals↗
PubMed1988

Reproductive outcomes of mothers with potential exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Animal laboratory studies have demonstrated that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has fetotoxic and teratogenic effects at low doses. TCDD contamination of soil in nine residential areas of eastern Missouri began in 1971 when several horse arenas and dirt roads were sprayed for dust control with a mixture that contained waste oil and dioxin. The authors conducted an epidemiologic investigation to determine if adverse human reproductive outcomes are associated with exposure to soil contaminated with dioxin. The authors attempted to identify all births during the period of January 1, 1972 through December 31, 1982 that had potential exposure to dioxin, based on proximity of the maternal address to a location of known TCDD contamination. This group totaled 410 births. A matched set of 820 unexposed births was selected as a comparison group after being matched for maternal age and race, year of birth, hospital of birth, and plurality. The exposed group had increased risk ratios for infant, fetal, and perinatal death; low birth weight; and several subcategories of birth defects. None of these increased risk ratios for the exposed group were statistically significant. These results do not provide evidence that TCDD exposure has a substantial impact on the reproductive outcomes investigated. If TCDD does produce effects on reproductive health, a larger study and/or better measures of exposure may be needed to discover them.

Abnormalities, Drug-Induced↗