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Biomedical subjects

C M Ryan

Publications and source records attributed to C M Ryan.

At least 91 records · Page 5Linked to original sources
PubMed1988

Cacosmia and neurobehavioral dysfunction associated with occupational exposure to mixtures of organic solvents.

This study examined the interrelationships among occupational exposure to mixtures of organic solvents, neurobehavioral functioning, and complaints of cacosmia. The latter was defined as nausea, headaches, and subjective distress in individuals exposed to neutral environmental odors. The authors administered a battery of cognitive tests to men with and without a history of solvent exposure and found exposed workers to be impaired across a wide range of cognitive domains. Multiple regression analyses of exposed workers demonstrated a highly significant relationship between a history of cacosmia and performance decrements on measures of learning and memory.

Cognition Disorders↗
PubMed1988

Neurobehavioral complications of type I diabetes. Examination of possible risk factors.

There is increasing interest in the possibility that diabetes mellitus may be associated with a series of neurobehavioral, or neuropsychological, changes; i.e., learning, memory, problem solving, mental and motor speed, and eye-hand coordination may sometimes be disrupted in diabetic children and adults, and this disruption may be a consequence of certain disease-related variables. To date, four neurobehavioral risk factors have been identified. For children and adolescents, the most potent risk factors appear to be age at diagnosis and the occurrence of schoolroom-related problems. Children who develop diabetes early in life are more likely to show serious cognitive impairments on virtually all measures. In addition, diabetic children with school attendance problems tend to score lower than expected on verbal IQ tests and school achievement tests. For adults, the most carefully studied risk factor is degree of metabolic control. Adults in poor control are far more likely to manifest subtle changes on measures of mental efficiency. This may be particularly evident on tasks that require the development and deployment of sophisticated information-processing strategies. A fourth variable--severe episodes of hypoglycemia--is known to disrupt functioning in diabetic subjects of any age, although it has not yet been studied systematically in large-scale studies. Indeed, because virtually all extant studies have been based on limited neurobehavioral and biomedical assessments of relatively few volunteer subjects, this list of risk factors must be considered tentative at best.

Adolescent↗
PubMed1987

Assessment of neuropsychological dysfunction in the workplace: normative data from the Pittsburgh Occupational Exposures Test Battery.

Neuropsychologists are being increasingly called upon to assess the neurobehavioral status of adults who have been exposed to toxic chemicals or heavy metals in the workplace. Unfortunately, the evaluation of blue-collar workers has been hampered by the absence of a brief yet comprehensive battery of sensitive neuropsychological tests that have been administered to a large cohort of demographically similar adults with no prior history of occupational exposure. In this paper we describe the development of the Pittsburgh Occupational Exposures Test Battery. We detail the procedures used to collect appropriate age-scaled norms from 182 blue-collar males, and delineate the factor structure of the test battery. We also examine the interrelationships among test scores and certain demographic variables, and discuss the epidemiologic and clinical relevance of these data.

Adult↗
PubMed1987

Low level lead exposure and neuropsychological functioning in blue collar males.

To examine the interrelationships between normal aging, occupational lead exposure, and cognitive functioning, a comprehensive battery of neuropsychological tests was administered to 288 randomly-selected lead-exposed workers and 181 demographically-similar nonexposed controls. Contrary to previous reports, those workers with current blood-lead levels in the low to moderate range (less than 50 micrograms/dl) were found to perform as well as controls on measures of learning, memory, attention, visuospatial ability, and general intelligence. They differed from controls only on one measure of psychomotor speed and manual dexterity, the Grooved Pegboard Test, and these between-group differences were restricted to the older lead workers. It is likely that these results are secondary to lead-mediated neuromuscular damage. There is little support for the view that older adults with current blood lead levels in the low to moderate range are at risk for developing significant CNS dysfunction, even though they may have had a past history of excessively high blood lead levels.

Adult↗
PubMed1985

Patterns of alcohol use and physically aggressive behavior in men.

Research on the relationship between alcohol use and aggressive behavior has typically focused on arrested felons and has contained minimal data on alcohol use, the symptoms of alcoholism and potential explanatory variables. The present study examined this relationship in a community-based population of blue-collar workers (N = 484 men). Current alcohol consumption was not related to either the number of fights that subjects were involved in since age 18 or physical marital conflict. However, a pathological pattern of consumption and a recent diagnosis (within the previous 3 yr) of alcohol misuse or alcohol dependence were related to physical marital conflict. Furthermore, these relationships remained significant after sociodemographic factors, and hostility and marital satisfaction were controlled for. Thus, these results on aggressive behavior confirm previous findings from research on criminal violence.

Adult↗
PubMed1983

Critical review of international standards for respiratory protective equipment - II. Gas and vapor removal efficiency and fit testing.

The purpose of a Respiratory Protective Equipment (R.P.E.) standard is to assure that a minimum level of performance is reached by the respirator. Standards from a number of countries and standards organizations require that certain specifications are met in construction and that respirators be evaluated by specific performance tests. This is the second of three critical review papers related to respirator standards. We here summarize in tabular form, compare and critically review how the different countries or standards organizations test respirators designed for protection against gases and vapors for leakage due to improper fitting of the respirator facepiece and gas and vapor removal efficiency of the cartridge/canister. Two general aspects as they relate to removal capacity testing are discussed. The first issue deals with the selection of test gases and vapors that best represent the sorptive behavior of a class or group of compounds. The second issue deals with the extrapolation of laboratory testing under rigidly specified conditions to conditions of actual use. Fit testing varies from country to country. The fit testing conditions specified in the various standards are summarized along with a discussion of test material selection, the test panel selection, and the range of controlled test activities.

Air Pollutants, Occupational↗
PubMed1983

Critical review of international standards for respiratory protective equipment - III. Practical performance tests.

This paper, the third in a series of papers devoted to review of international standards for Respiratory Protective Equipment (R.P.E.), summarizes in tabular form, compares, and critically reviews standards of different countries or organizations pertaining to practical performance tests (Man Tests). There are similarities, differences and omissions in the national standards that deserve attention. Of the countries or organizations that require Man Tests on particulate and/or gas and vapor respirators, none described in detail the tests to be performed. For example, CEN requires that Man Tests be conducted on gas/vapor respirators under realistic conditions to determine imperfections that cannot otherwise be determined by other performance tests, but does not stipulate the testing procedure. With respect to fresh-air hose, compressed-air line and self-contained breathing apparatus R.P.E., only Great Britain and CEN present specific Man-testing requirements in detail. Man Tests for all types of R.P.E. have a specific purpose: to determine any imperfections in, or malfunction of the apparatus under simulated work conditions. One major difference, however, is in the kind of work simulation activities required. In the testing of fresh-air hose and compressed-air line respirators, for instance, CEN describes in great detail, a variety of activities to be conducted. Great Britain merely states that the subjects shall work in practical conditions. Another important disparity relates to the conditions under which the test is to be performed. For example, CEN requires a heavy-duty test and a cooled chamber test, as well as tests under normal and low temperature conditions. Great Britain, on the other hand, requires only the latter two tests. Still other differences lie in the kinds of medical surveillance required during testing and the evaluation criteria used for assessment.

Air Pollutants, Occupational↗
PubMed1983

Neuropsychology of alcoholism. Etiology, phenomenology, process, and outcome.

A number of empirical and conceptual issues are addressed in an effort to explain the diversity of neuropsychological deficits demonstrated by chronic alcoholics. In addition to consumption characteristics and the neurotoxic effects of ethanol, evidence is marshalled to implicate nutritional deficiency, hepatic disease, congeners in the beverage, and cognitive regression as also being contributory to the manifest impairments. Moreover, predrinking disturbances are considered that may be responsible in part for the neuropsychological deficits observed in chronic alcoholics. Our understanding of the neuropsychological concomitants of alcoholism can be increased by the adoption of a life-span approach to alcohol effects, localizing the system or region of maximal cerebral damage and relating these findings to treatment intervention. The extent to which adaptive capacity in alcoholics and social drinkers is predicted by neuropsychological test performance is of utmost importance, especially since nonalcoholic social drinkers also demonstrate a number of impairments.

Alcoholism↗
PubMedDate not supplied

Why is learning and memory dysfunction in Type 2 diabetes limited to older adults?

Review of the literature on the cognitive correlates and consequences of Type 2 diabetes reveals two very intriguing findings. Not only are verbal learning and memory skills most likely to be disrupted as compared to other cognitive skills (e.g. attention, executive function; psychomotor efficiency), but these mnestic deficits appear to be restricted to individuals with diabetes who are older than 60-65 years of age. Middle-aged adults with either Type 2 or Type 1 diabetes are apparently protected insofar as researchers have only infrequently reported learning and memory impairments in that age group. Why do older adults have such an increased risk of diabetes-associated memory dysfunction? In our view, this phenomenon is a consequence of a synergistic interaction between diabetes-related metabolic derangements and the structural and functional changes occurring in the central nervous system (CNS) that are part of the normal ageing process. To critically evaluate that possibility, we summarise what is known about learning and memory dysfunction in the adult with diabetes, examine the extent to which chronic hyperglycaemia may adversely affect the integrity of the CNS, and selectively review the literature on age-associated changes in brain morphology and cognitive function, paying special attention to the threshold theory of cognitive impairment.

Adult↗
PubMedDate not supplied

A stable long-term hepatocyte culture system for studies of physiologic processes: cytokine stimulation of the acute phase response in rat and human hepatocytes.

Prior studies on the in vitro hepatic acute phase response have involved either hepatoma cell lines or conventional short-term cultures of primary hepatocytes. No data are available on the response of primary hepatocytes in stable long-term culture systems. In this study, the acute phase response of rat and human hepatocytes in a new long-term culture system was examined in response to interleukin-6 (IL-6), interleukin-1 beta (IL-1 beta), and tumor necrosis factor alpha (TNF-alpha). The cultured cells were sandwiched between two layers of collagen in a (double-gel) configuration which has been shown to preserve both hepatocyte function and morphology over prolonged periods of time. The stability of this culture configuration enabled us to investigate, for the first time, the temporal aspects of the response in addition to the effects of the mediators on protein secretion. Exposure of rat hepatocytes to IL-6 after culture for 16 days resulted in a 2-fold reduction of albumin secretion and a 15-fold increase in the secretion rates of fibrinogen and alpha 2-macroglobulin. In all instances, the peak response occurred at 48 h after IL-6 exposure, and all protein secretion rates returned to pretreatment values within 5 days posttreatment. Changes in the mRNA levels of these proteins in response to IL-6 corresponded with those changes seen with the secreted products, indicating pretranslational regulation. Administration of IL-1 beta to rat hepatocyte produced a similar decline of albumin secretion and a 5-fold increase of fibrinogen secretion, whereas alpha 2-macroglobulin secretion remained undisturbed.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute-Phase Reaction↗
PubMedDate not supplied

An effective technique of scrotal harvest.

In male patients with extensive burns, the scrotum is often spared and is potentially a very useful donor site. We describe a technique that simplifies scrotal harvest and facilitates the procurement of clinically useful amounts of split-thickness skin.

Adolescent↗
PubMedDate not supplied

A quantitative model of invasive Pseudomonas infection in burn injury.

To evaluate newer therapies for wound infections, it becomes necessary to quantify bacteria that invade from the infected wounds into the adjacent tissues. For example, antibody-targeted photolysis targets the invasive Pseudomonas with antibodies carrying photochemical dyes. A full-thickness burn wound was infected with Pseudomonas aeruginosa with a modification of previous methods. In mice, a skin fold was elevated, and two preheated brass blocks at 92 degrees to 95 degrees C were applied for 5 seconds, producing a 5% total body surface area injury with discrete margins. The eschars were immediately inoculated with Pseudomonas. Survival at 10 days was 100% with burn injury alone and 60% with infected burns. Pseudomonas (10(8)/gm) were recovered from the unburned muscle by 24 hours. The method produced uniform and reproducible quantitative bacteriology within the muscle immediately beneath the burn injury (SL < 0.05). Quantitative comparisons can be used to determine the effectiveness of newer modalities to control Pseudomonas burn wound infections.

Animals↗
PubMedDate not supplied

Modified Stryker frame for intraoperative positioning of the patient with burns.

Positioning large patients with burns for prone burn procedures can be very difficult, requiring operating room personnel to use a gang-lift technique. We have used the upper portion of a Stryker frame mounted to a standard operating room table base in more than 200 burn procedures in adults to move patients from the supine to the prone position, and back, without complication.

Burns↗
PubMedDate not supplied

Management of severe toxic epidermal necrolysis in children.

Toxic epidermal necrolysis (TEN) is a severe form of erythema multiforme that results in extensive epidermal sloughing; the condition is associated with a mortality of up to 70%. From 1991 to 1998, 10 children with severe toxic epidermal necrolysis were referred to a regional pediatric burn facility. Wounds were managed with strategy involving prevention of wound desiccation and superinfection, including the frequent use of biologic wound coverings. Children unable to guard their airway because of extensive oropharyngeal involvement were prophylactically intubated. Enteral nutrition was stressed. Steroids were not used and antibiotics were administered to managed specific foci of infection only. The 2 boys and 8 girls had an average age of 7.2+/-1.8 years (range 6 months to 15 years) and sloughed surface area of 76+/-6% of the body surface (range 50 to 95%). Antibiotics (3 children), anticonvulsants (3 children), nonsteroidals (2 children), and viral syndrome or unknown agents (2 children) were felt to have triggered the syndrome. Six children (60%) required intubation for an average of 9.7+/-1.8 days (range 2 to 14 days). Buccal mucosal involvement occurred in 9 (90%) and ocular involvement in 9 (90%). Although infectious complications were common (2 pneumonias, 2 urinary infections, 1 bacteremia, 2 central line infections, and 2 candidemias), all children survived after lengths of stay in the burn unit averaging 19+/-3 (range 6 to 40) days. The most common long-term morbidity was keratitis sicca (2 children, 20%), finger nail deformities (3 children, 30%), and variegated skin pigment changes (5 children, 50%). Although having both a cutaneous and visceral wound that predispose them to infectious complications, most children with TEN will survive if managed with a strategy emphasizing biologic wound closure, intensive nutritional support, and early detection and treatment of septic foci. Burn units have the resource set required to manage severe TEN and early referral of such children may have a favorable impact on survival.

Adolescent↗