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Biomedical subjects

C S Miller

Publications and source records attributed to C S Miller.

105 records · Page 6Linked to original sources
PubMedDate not supplied

Visual responses of crayfish ocular motoneurons: an information theoretical analysis.

Motoneuron responses were elicited by global visual motion and stepwise displacements of an illuminated stripe. Stimulus protocols were identical to those used in previous behavioral studies of compensatory eyestalk reflexes. The firing rates and directional selectivity of the motoneuron responses were measured with respect to four stimulus dimensions (spatial frequency, contrast, angular displacement and velocity). The directional selectivity of the motoneuron response was correlated to the previously measured gain of the reflex for each stimulus dimension. The information theoretical analysis is based upon Kullback-Leibler (K-L) distances which measure the dissimilarity of responses to different stimuli. K-L distances for single neurons are strongly influenced by the mean rate difference of the responses to any pair of stimuli. Because of redundancy, the joint K-L distances of pairs of neurons were less than the sum of the K-L distances of the individual neurons. Furthermore, the joint K-L distances were only weakly influenced by correlations among coactivated neurons. For most of the stimulus dimensions, the K-L distances of single motoneurons were not sufficient to account for the stimulus discriminations exhibited by the eyestalk reflex which typically required the summed output of 2 to 5 motoneurons. Thus the behaviorally relevant information is encoded in the motoneuron ensemble. The minimum time required to discriminate the direction of motion (the encoding window) for a single motoneuron is about 380 to 480 ms (including a 175 ms response latency) for stepwise displacements and up to 1.0 s for global motion. During this period a motoneuron fires 2 to 3 impulses.

Action Potentials↗
PubMedDate not supplied

Chemical sensitivity attributed to pesticide exposure versus remodeling.

One hundred twelve individuals who reported onset of multiple chemical sensitivity following well-documented exposure to either (1) a cholinesterase-inhibiting organophosphate or carbamate pesticide or (2) remodeling of a building completed mail-out/mail-back questionnaires concerning their exposure, symptoms, sensitivity to ingestants and inhalants, utilization of health-care resources, and impact of their illness on lifestyle. It was hypothesized that if multiple chemical sensitivity resulted from neurotoxic exposure, then organophosphate-exposed respondents should report greater severity of illness resulting from the relatively greater neurotoxicity of this class of chemicals. Pesticide-exposed and remodeling-exposed multiple chemical sensitivity groups reported similar patterns of symptoms and identified similar inhalants and ingestants as triggers for their symptoms; these results suggested a common mechanism (biological and/or psychological) for their conditions. The pesticide-exposed group, however, reported significantly greater symptom severity than did the remodeling-exposed group, especially for neuromuscular, affective, airway, gastrointestinal, and cardiac symptoms. These findings provide evidence for (1) a possible biological basis for multiple chemical sensitivity and (2) a distinct pathophysiology or final common pathway for the condition that, while as yet undefined, appears to be shared by these two groups. Although subjective multisystem health complaints characterize both multiple chemical sensitivity and somatoform disorder, features of this multiple chemical sensitivity sample were inconsistent with somatoform disorder, i.e., onset after 30 y of age in 83%, the predominance of severe cognitive symptoms, and attributions of environmental causation. No group differences were found with respect to lifestyle impact. Eighty-one percent of respondents said they had been working full-time at the time they were exposed, yet at the time of the survey (on average, 7.7 y post exposure) only 12.5% were working full-time. The majority said they had quit their jobs, changed jobs, or changed careers because of their illness. Approximately 40% reported that they had consulted 10 or more medical practitioners. The persistent, disabling neuropsychological symptoms reported by these multiple chemical sensitivity groups are strikingly similar to those reported among individuals exposed occupationally to pesticides and solvents. These parallel findings suggest that the types and levels of exposures associated with extermination and remodeling may not be inconsequential, at least for a subset of the population. Further studies from a variety of perspectives, including human challenge studies and the development of animal models, are needed to define the pathophysiological and psychological mechanisms underlying this costly condition.

Adult↗
PubMedDate not supplied

Neuropsychiatric and somatic characteristics of young adults with and without self-reported chemical odor intolerance and chemical sensitivity.

The psychological, neuropsychiatric, and somatic characteristics of young adults who have different degrees of cacosmia (i.e., feeling "ill" from the odor of xenobiotic chemicals) and who have self-described "chemical sensitivity" were examined. A total of 800 college students completed the following: a self-rating scale for frequency of odor intolerance for 10 common substances, Simon Environmental Illness Symptom Survey, the SCL-90-R, Barsky Amplification Scale, Pearlin-Schooler Mastery Scale, Cheek-Buss and Kagan Shyness scales, Marlowe-Crowne Social Desirability Scale, and a health-symptom and physician-diagnosed checklist. Two pairs of groups were compared: (1) subjects in the top 16% (i.e., cacosmics) and bottom 15% (noncacosmics) of the sample with respect to odor intolerance scale scores; and (2) subjects from the entire sample who did (28%) or did not (72%) consider themselves to be "especially sensitive to certain chemicals.¿ Cacosmics and the chemically sensitive subjects scored significantly higher on measures of psychological distress and amplification of somatic symptoms, but there was little evidence of lifestyle change, as assessed by the Simon Survey. Compared with their respective comparison groups, cacosmic and chemically sensitive groups had significantly higher incidences of illnesses associated with chemicals, alcohol intake, opiate drug use, and caffeine use, even after controlling for the psychological measures and histories of atopic allergy. Subjects with and without neuropsychiatric symptoms were differentiated with respect to chemical odor intolerance, but subjects with and without atopic allergies and possible autoimmune diseases were differentiated with respect to chemical sensitivity. Females were more cacosmic than males. Cacosmia is defined by a population subset, with or without occupational xenobiotic exposures or disability, that has distress and symptom amplification and neuropsychiatric and somatic symptoms, none of which are explained fully by psychological measures. Prospective clinical studies are possible with such individuals. The data are also consistent with a time-dependent sensitization model for illness from low-level chemical exposures.

Adolescent↗
PubMedDate not supplied

Minimizing risk of infection using a carbon dioxide laser.

The carbon dioxide laser is a surgical device increasingly important to dentistry. The advantages of laser use in the treatment of oral disease have been well documented. Such benefits include bloodless incisions, accurate tissue destruction, reduced pain, minimal swelling, excellent hemostasis, and limited postoperative tissue morbidity. Little information exists currently regarding laser use in the management of medically complex patients, most notably patients with infectious diseases. This article reports the use of the carbon dioxide laser for reducing the risks of disease transmission in the surgical management of an human immunodeficiency virus (HIV) seropositive patient.

Adult↗
PubMedDate not supplied

Are we on the threshold of a new theory of disease? Toxicant-induced loss of tolerance and its relationship to addiction and abdiction.

'Toxicant-induced loss of tolerance' (or TILT) describes a two-step disease process in which (1) certain chemical exposures, e.g., indoor air contaminants, chemical spills, or pesticide applications, cause certain susceptible persons to lose their prior natural tolerance for common chemicals, foods, and drugs (initiation); (2) subsequently, previously tolerated exposures trigger symptoms. Responses may manifest as addictive or abdictive (avoidant) behaviors. In some affected individuals, overlapping responses to common chemical, food, and drug exposures, as well as habituation to recurrent exposures, may hide (mask) responses to particular triggers. Accumulating evidence suggests that this disease process might underlie a broad array of medical illnesses including chronic fatigue, fibromyalgia, migraine headaches, depression, asthma, the unexplained illnesses of Gulf War veterans, multiple chemical sensitivity, and attention deficit disorder.

Behavior↗
PubMedDate not supplied

A rat model of neurobehavioral sensitization to toluene.

Some individuals report that, following either a single high-level or repeated lower-level exposures to chemicals (initiation), subsequent exposure to very low concentrations of chemicals (triggering) produces a variety of adverse effects, including disruption of cognitive processes. Our objective was to model this two-step process in a laboratory animal. Two groups of 16 rats, eight male and eight female, received whole-body inhalation exposure to toluene, either at 80 ppm for 6 h/day for 4 weeks (Repeat group) or to 1600 ppm for 6 h/day on one day only (Acute group). Two other groups (Trigger group and Clean group) of 16 were sham-exposed. After 17 days without toluene exposure, the Acute, Repeat and Trigger groups began a series of daily toluene 'trigger' exposures (10 ppm for 1 h) followed immediately by testing on an operant repeated-acquisitions task requiring learning within and across sessions. The Clean group was sham-exposed prior to operant testing. Trigger or sham exposures and operant testing continued 5 days/week for 17 sessions. Analysis of variance revealed a variety of statistically significant (P < 0.05) differences between treatment groups. Furthermore, the patterns of differences between groups differed (P < 0.05) for female and male rats. For example, male rats of the Trigger group made the most responses, and female rats of the Repeat group responded most slowly. The observation of important changes in the operant behavior of female and male rats previously exposed to toluene, at relatively low concentrations (80 or 1600 ppm) and then later re-exposed at very low concentrations (10 ppm), is consistent with the experiences of humans reporting cognitive difficulties following acute or chronic exposures to chemicals.

Administration, Inhalation↗
PubMedDate not supplied

The Environmental Exposure and Sensitivity Inventory (EESI): a standardized approach for measuring chemical intolerances for research and clinical applications.

The lack of a generally accepted case definition for multiple chemical sensitivity (MCS) and the absence of a standardized approach for measuring salient aspects of chemical sensitivity that would permit cross-comparison of findings by different investigators have hindered progress in this area. Based upon findings from an earlier study of 112 persons with self-reported chemical sensitivity who attributed their chemical sensitivity to a well-defined exposure event, we developed an instrument with self-rating scales to assess Symptom Severity, Chemical (Inhalant) Intolerances, Other Intolerances (e.g., foods, medications, alcohol), Life Impact, and Masking (a measure of ongoing chemical exposures). When administered to four patient groups and controls, the scales showed good reliability and validity overall (n = 421) and in each group. Used together, the scales provided sensitivity of 92% and specificity of 95% in differentiating chemically sensitive persons from controls. Our results support use of these scales individually or collectively for a variety of applications including the selection of chemically sensitive subjects and controls for research, assessment of chemical sensitivity in various study populations, cross-comparison of groups studied by different investigators, pre- and post-assessment of therapeutic interventions, clinical evaluation of complex patients who report intolerances, and teaching medical residents and students how to evaluate patients for chemical sensitivity and MCS.

Environmental Exposure↗
PubMedDate not supplied

A controlled comparison of symptoms and chemical intolerances reported by Gulf War veterans, implant recipients and persons with multiple chemical sensitivity.

Using the Environmental Exposure and Sensitivity Inventory (EESI), a standardized instrument for measuring chemical sensitivity, we obtained and compared ratings of symptoms, chemical (inhalant) intolerances, other intolerances (e.g., drugs, caffeine, alcohol, skin contactants), lifeimpact, and masking (ongoing exposures) in five populations: multiple chemical sensitivity (MCS) patients who did (n = 96) or did not (n = 90) attribute onset of their illness to a specific exposure event, patients with implanted devices (n = 87), Gulf War veterans (n = 72), and controls (n = 76). For each patient group, mean scores on the first four scales were significantly greater than for controls. MCS patients reported avoiding more chemical exposures (were less masked) than the other groups. Across groups, for a given level of symptoms, as masking increased, mean scores on the Chemical Intolerance Scale decreased. In contrast, mean scores on the Other Intolerance Scale appeared to be less affected by masking. These findings suggest that some patients with antecedent chemical exposures, whether exogenous (chemical spill, pesticide application, indoor air contaminants) or endogenous (implant), develop new chemical, food, and drug intolerances. Reports of new caffeine, alcohol, medication, food, or other intolerances by patients may signal exposure-related illness. Masking may reduce individuals' awareness of chemical intolerances, and, to a lesser degree, other intolerances.

Adult↗
PubMedDate not supplied

Exacerbation of chemical sensitivity: a case study.

We report exacerbation of symptoms and chemical intolerances in three of four self-described chemically sensitive women following relocation to a newly constructed office building. Levels of total volatile organic compounds (TVOCs) in this building prior to occupancy were approximately 200 micrograms/m3 (toluene equivalent units) with a myriad of individual components present. By day 50 after occupancy, the concentration of TVOCs in the building dropped to approximately 50 micrograms/m3. Nevertheless, three women reported significant worsening of their symptoms with spreading of their sensitivities to previously tolerated chemical exposures. One woman relocated to another building, while the other two managed their symptoms by reducing time spent in the building or by using a room air cleaner. By day 600 following occupancy, although TVOCs had increased significantly (perhaps due to cleaning agents), there were fewer individual VOCs present in the air, and some of the women were able to tolerate the air in the building. We conclude that complex mixtures of VOCs at very low levels tolerated by the majority of building occupants may pose problems for persons who report pre-existing chemical sensitivities. TVOC measurements may not correlate with symptoms in these individuals. Reasonable accommodations by an employer can reduce problem exposures, making it possible for some affected individuals to continue productive employment.

Air Pollution, Indoor↗
PubMedDate not supplied

To collect or not to collect. The internal woe of the physician's office.

Physicians are obliged to provide health care services regardless of race, creed, color or the ability to pay, write Carol Miller and Harry Wolpoff, Esq. Yet, a medical group is a traditional business which requires cash payments to continue operations. Miller and Wolpoff discuss such issues as physician sensitivity to collections, patient responsibilities and staff training in creating an effective collection program for medical groups.

Contract Services↗
PubMedDate not supplied

Possible models for multiple chemical sensitivity: conceptual issues and role of the limbic system.

Conceivably, chemicals contacting olfactory nerve projections in the nose could either be transported into or relay electrical signals to the limbic region, leading to a vast array of symptoms. Likewise, thought processes and mood states may trigger or interrupt pre-existing limbic activity. At present, however, no evidence suggests that limbic activity triggered by environmental exposures can be entirely overcome by psychologic interventions. One important ramification of a limbic hypothesis, if true, is that no convenient biologic marker for multiple chemical sensitivity may exist at the present time. Ten years from now, we may finally confirm the existence of multiple chemical sensitivities (by careful, blinded challenges) but still have no single mechanism to explain it; that is, after all avenues of biochemical and immunologic inquiry have been exhausted, no single cause or marker for this disorder may be apparent. The theory that adaptation plays a role in MCS is based on the observed responses of patients in a deadapted state who have been housed in an environmental unit. Although adaptation is only an observation at this time, not a mechanism, biologic limits might regulate how much an organism can adapt. Such limits could be highly individual and vary by orders of magnitude. Certainly adaptation occurs at all levels of biologic systems, from enzyme systems to cells, tissues, organs, and even behavior (Fregly, 1969). Theoretically, a major insult or the accumulation of lower-level injuries within these systems could lead to a kind of "overload" or "saturation" effect with respect to adaptive capacity. This might cause an individual to have environmental responses, which, instead of being flexible and fluid, would become fragile and overly responsive. Many MCS patients report that years, and in some cases decades, after the onset of their problems, they have recovered only a portion of their former energies and tolerance for their environment. Their descriptions seem to suggest the loss of an intangible capacity to adapt, parts of which may be temporary and recoverable and other parts of which may not. Perhaps our patients have been telling us the diagnosis.

Adult↗
PubMedDate not supplied

White paper: Chemical sensitivity: history and phenomenology.

Nearly everyone has heard something about chemical sensitivity, either from personal experience with someone who has the condition or from the media. The television series Northern Exposure recently featured a chemically sensitive attorney who lived in a geodesic dome in Alaska, and L.A. Law depicted the struggles of a Persian Gulf veteran with chemical sensitivities who lost his case against the Veterans Administration, but may appeal later in the season. Television news programs and the printed media have showcased patients living spartan existences in remote areas or in aluminum foil-lined rooms. Our views of the illness no doubt are colored by our own personal experiences of it. While some discount or make jokes about chemical sensitivity or these patients, physicians who have seen a number of them are discovering that many appear to be credible individuals with prior good work records who say they became ill following an identifiable exposure to chemicals.

Government Agencies↗
PubMedDate not supplied

Obstetricians' prior malpractice experience and patients' satisfaction with care.

OBJECTIVE: To examine the relationship between prior physician malpractice experience and patients' satisfaction with care. DESIGN: Women were interviewed using a questionnaire that contained structured and open-ended questions. PARTICIPANTS: Mothers of all stillborn infants, infant deaths, and a random sampling of viable infants drawn from 1987 Florida Vital Statistics were sorted into four groups based on the malpractice claims experience of their obstetricians between 1983 and 1986. Interviews were completed with 963 of 1536 women, most by telephone, 53 by in-person interview. MAIN OUTCOME MEASURES: Mothers' responses to closed-ended and open-ended questions about their perceptions of the care they received during their pregnancy, labor, and delivery. RESULTS: Even though none of the women actually filed a claim, a consistent pattern of differences emerged when comparing women's perceptions of care received. Patients seeing physicians with the most frequent numbers of claims but without high payments were significantly more likely to complain that they felt rushed, never received explanations for tests, and were ignored. In response to the open-ended question, "What part of your care were you least satisfied with?" women seeing physicians in the High Frequency malpractice risk group offered twice as many complaints as those seeing physicians who had never been sued. Problems with physician-patient communication were the most commonly offered complaints. CONCLUSION: Physicians who have been sued frequently are more often the objects of complaints about the interpersonal care they provide even by their patients who do not sue.

Female↗