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Biomedical subjects

R E Hoffman

Publications and source records attributed to R E Hoffman.

At least 91 records · Page 5Linked to original sources
PubMed1987

Computer simulations of neural information processing and the schizophrenia-mania dichotomy.

Recent developments in artificial intelligence use computer simulations of complex neural systems to model associative memory and gestalt-seeking during cognition. Perturbations imposed on such computer simulations caused catastrophic breakdowns of neural functioning. The resulting cognitive disturbances assumed two forms, one "schizophreniclike" and the other "maniclike." The former was induced by memory overload and resulted in misperceptions, loose associations, and also parasitic processing states that pathologically controlled the flow of associations. The latter was caused by increased randomness of neural activity, which induced "jumps" from one gestalt to another. The relationship between this differential model of psychotic disturbances and other studies of schizophrenia and mania were explored.

Arousal↗
PubMed1986

2,3,7,8-Tetrachlorodibenzo-p-dioxin levels in adipose tissue of exposed and control persons in Missouri. An interim report.

The compound 2,3,7,8-tetrachlorodibenzo-p-dioxin, commonly known as dioxin, was measured in the adipose tissue of 39 persons with a history of residential, recreational, or occupational exposure in Missouri and in 57 persons in a control group. All participants had detectable levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin in their adipose tissue, but the exposed group had significantly higher levels. Levels of six of the exposed persons were more than five times greater than the level of the highest control. Measuring 2,3,7,8-tetrachlorodibenzo-p-dioxin in adipose tissue provides a much improved index of exposure, an important advance for research studies evaluating the possible health effects of this compound.

Adipose Tissue↗
PubMed1986

Health effects of long-term exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

In 1971, sludge wastes contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin were mixed with waste oil and sprayed on a dirt road at the Quail Run Mobile Home Park in Gray Summit, Mo. We performed a comprehensive examination of 154 exposed and 155 unexposed persons in the area. There were no consistent differences between the two groups on medical history, physical examination, serum and urinary chemistry studies, and neurologic tests. Results of liver function tests suggested possible subclinical effects. The exposed group had an increased frequency of anergy (11.8% vs 1.1%) and relative anergy (35.3% vs 11.8%). The exposed group also had non-statistically significant increased frequencies of abnormal T-cell subset test results (10.4% vs 6.8%), a T4/T8 ratio of less than 1.0 (8.1% vs 6.4%), and an abnormality in the functional T-cell test results (12.6% vs 8.5%). These findings suggest that long-term exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin is associated with depressed cell-mediated immunity, although the effects have not resulted in an excess of clinical illness in the exposed group. Further studies are indicated to elucidate the pathophysiology and clinical significance of these immunologic findings.

Adolescent↗
PubMed1986

A comparative study of manic vs schizophrenic speech disorganization.

Recent studies have indicated that thought disorder occurs among manics at least to the same degree as among schizophrenics. The present study assumes that thought disorder can be considered as an abnormality of language whereby listeners are unable to organize speech into a single, coherent "whole." A model of language processing is presented that predicts that the incoherence of manic speech is due to shifts from one coherent discourse structure to another, while the ability of schizophrenic speakers to construct any discourse structure is deficient. A discourse analysis was applied to normal, manic, and schizophrenic speech samples. The two hypotheses were supported. The implications of these findings in light of other investigations of mania and schizophrenia are discussed.

Adult↗
PubMed1986

Tree structures, the work of listening, and schizophrenic discourse: a reply to Beveridge and Brown.

A. W. Beveridge and K. Brown (Brain and Language, 24, 174-181) have criticized a study reported by R. Hoffman, L. Kirstein, S. Stopek, and D. Cicchetti (Brain and Language, 15, 207-233), which examined processing tasks imposed upon listeners by schizophrenic speech. The authors argue that our discourse analysis was not sufficiently objective since different discourse structures can at times be generated on the basis of a particular deviant speech segment. However, the analysis which we described does not purport to yield an "objective" structure of schizophrenic texts but rather attempts to reflect representations that individual listeners generate in processing speech; our model only requires that different interpretations of a particular segment generate different discourse structures. Deficiencies in hierarchical structure associated with schizophrenic speech increase processing requirements for listeners and may cause interpretive variability. Incoherence scores generated on the basis of our analysis were used to estimate the amount of extra "work of listening" that particular speech segments require. Because these incoherence scores were blindly and reliably determined, they can be used to make statistical inferences about the prevalence of structural deficiencies of schizophrenic speech compared to the speech of controls.

Humans↗
PubMed1985

Message disruptions during syntactic processing in schizophrenia.

Twenty-four schizophrenics and 24 nonschizophrenic psychiatric patients were given the Hunt test, which requires the subject to use syntactic strategies to synthesize an extended multisentence text on the basis of a controlled set of input propositions. This syntactic processing task induced many more meaning misrepresentations of input propositions in the schizophrenic group compared to the control group. These group differences could not be accounted for by confounding variables such as level of psychopathology, medication, and verbal skills. An error analysis indicated that schizophrenics were highly likely to produce meaning errors when the rewritten proposition assumed a passive syntactic form. Conceptually complex sequences of propositions also resulted in a high frequency of message errors among schizophrenics; this second factor did not account, however, for the high association of errors and passive rewrites. These data are interpreted as indicating that schizophrenics suffer from a multilevel language-production disturbance that includes higher-level message errors that are reflexively induced by lower-level syntactic processing disturbances.

Adolescent↗
PubMed1984

Perfluorinated organic liquids and emulsions as biocompatible NMR imaging agents for 19F and dissolved oxygen.

Emulsions of fluorocarbons are finding considerable use in physiology for intravascular oxygen transport. Their wide clinical application as blood substitutes, anti-shock, and anti-ischemic agents seems imminent. Whole body NMR imaging is rapidly gaining clinical application and may one day almost completely supplant X-ray imaging. All of the 19F compounds used in biocompatible fluorocarbon emulsions give 19F signals identical to those in the corresponding neat liquid. In concentrations of 10% w/v they are readily imaged. The paramagnetic oxygen molecule reduces T1 in such a way as to make possible whole body imaging of oxygen. T1 typically decreases from 1-4 to 0.3-0.5 seconds and is an inverse linear function of oxygen tension. Spin-lattice relaxation times versus oxygen tensions from 0 to 600 torr have been obtained for F-decalin, F-tributylamine, and F-44E. The usefulness of these 19F effects in clinical NMR imaging depends upon the sensitivity of the method and the tolerable dose. The 19F signal may find use in monitoring 19F compounds as vapors or gases dissolved in plasma or in perfluorocarbons in neat liquid or particle form.

Animals↗
PubMed1984

Risk factors for victimization during the 1980 riot at the Penitentiary of New Mexico.

The New Mexico Penitentiary riot of February 2, 1980, resulted in death for 33 inmates at the hands of their fellow prisoners, and the hospitalization of 62 inmates for treatment of drug overdose or trauma. A case-control study of dead and hospitalized inmates was conducted to determine risk factors for victimization. Twelve (12.5%) of the 96 inmates housed in the protective custody unit were killed, compared with an overall penitentiary death rate of 2.9% (p = 0.0003). These 12 individuals were similar to the general inmate population with respect to age, race, years of education, crimes, time served, and prison rule infractions committed. In contrast, the 21 homicide victims housed in other areas were younger and had committed significantly greater numbers of rule infractions during incarceration. Prisoners hospitalized for drug overdose, but not those hospitalized for traumatic injuries, could be differentiated from the remaining prison population by increased convictions for homicide and higher prison infraction rates. Inmates in protective custody were targeted selectively for death; other subgroups of victims of violence appear to share characteristics often associated with perpetrators of violence.

Adult↗
PubMed1984

The use of epidemiologic data in the courts.

It is difficult to make generalizations concerning the type of epidemiologic data currently preferred in the courts because trial judges' decisions are infrequently published, appellate judges' decisions are not always accompanied by an opinion, and there is often disparity between the opinions and standards of different courts. In this paper I have chosen cases either for their legal significance or their illustrative nature. The cases essentially represent numerator data, and therefore, I cannot determine definite trends in the courtroom use of epidemiologic data. When trying to determine if a causal relationship exists between an exposure and illness, epidemiologists attempt to examine the statistical strength, consistency, specificity, temporal sequence, dose-response characteristics, and biologic plausibility of the association. In contrast, a widely used legal standard of proof of association is "reasonable probability." However, the interpretation of "reasonable probability" is evolving. And just as epidemiologists may be pushed to the limit of their methods in trying to determine if and at what level a health risk exists, so the courts have had to forge new legal paths in considering whether epidemiologic evidence is sufficient to establish a causal relation between exposure to a substance and ill health. Furthermore, it is not certain what standard of significance the courts will require in the future. In 1975 in Reserve Mining Company vs. EPA, and Ethyl Corporation vs. EPA, the theoretical existence of risk was adequate to move the Appeals Courts to take precautionary action. But when considering a standard for safe levels of an occupational toxin, the Supreme Court has rejected a theoretical risk as significant (in Industrial Union vs. American Petroleum Institute) and instead, has required factual evidence of a dose-response relationship (as in American Textile Manufacturer's Institute vs. Donovan) because it did not want to extrapolate the risk of low levels of exposure from data based on high levels of exposure. Since demonstration of a dose-response relationship, although rarely obtained easily, is one of the criteria used by epidemiologists to infer a causal relationship, there can be no doubt that such evidence will strengthen any attempt to prove future damages from low level exposure to toxins. In addition, I predict evidence of attributable risk or attributable fraction will be useful in determining the extent of potential losses and, therefore, the value of future damages.(ABSTRACT TRUNCATED AT 400 WORDS)

Epidemiology↗
PubMed1981

Imported measles. A potential control problem.

From Dec 23, 1978, through Jan 31, 1979, an outbreak of five laboratory-confirmed cases and four clinical cases of measles occurred in a Vietnamese refugee population living in a single housing complex in Albuquerque, NM. The index cases were in two refugee siblings in whom measles was incubating on arrival in the United States. Despite spread through three subsequent generations of disease transmission within the Vietnamese population, there was no additional spread into the general Albuquerque population. Responsible factors included the age distribution of susceptible persons, the social isolation of the refugee population, and the physical structure of the housing complex. There is a need to identify the problem of imported measles in "ethnic islands" in need of vaccination.

Asian↗
PubMed1981

Increased incidence and prevalence of multiple sclerosis in Los Alamos County, New Mexico.

The incidence and prevalence of multiple sclerosis (MS) in Los Alamos County, New Mexico, were investigated because the number of reported cases appeared to have increased. The point prevalence on November 1, 1979, was 75.7 per 100,000, and average annual incidence rates for the period 1960-1969 and 1970-1979 were 3.4 and 3.7 per 100,000, respectively. The rates of MS in Los Alamos County were greater than expected from previous epidemiologic surveys of North America. The unusual ethnic composition and high socioeconomic level of the population probably contributed to the increases.

Adult↗
PubMed1981

The advent of human diploid cell rabies vaccine: impact on vaccine utilization in New Mexico.

Three months' experience with the newly licensed human diploid cell rabies vaccine in the New Mexico comprehensive consultation-biologics system was reviewed. Comparison with the same period in 1978 and 1979 showed no increase in vaccine utilization despite the advent of this simpler-to-use, safer rabies vaccine. Anti-rabies treatments appear to be minimally influenced by new vaccine technology when a comprehensive consultation system is available to support and guide the private physician.

Diploidy↗