Biomedical subjects

T R Simon

Publications and source records attributed to T R Simon.

59 records · Page 4Linked to original sources

PubMedDate not supplied

Correlates of exclusive or combined use of cigarettes and smokeless tobacco among male adolescents.

Past studies which examined correlates of smokeless tobacco or cigarette use have investigated use of one tobacco product regardless of use of the other product. Thus, the etiology of exclusive use of the two tobacco products is not clear. The present study investigated the relationship of problem-prone-related variables to exclusive versus overlapping use of smokeless tobacco and cigarettes. Two samples of southern California male students (eighth-grade and high school) were divided into groups according to their tobacco use status: neither product, cigarettes only, smokeless tobacco only, or both tobacco products. Generally, triers and monthly users of both tobacco products reported a higher risk-taking preference, greater susceptibility to peer social influence to use tobacco products, and greater likelihood to have tried marijuana and alcohol than did subjects who were not users of either tobacco product. Adolescents who used either product, but not both, reported similar scores on most of the variables examined, which fell in between combined or nonuse categories. These results suggest that the number of tobacco products used, not the specific product, is associated with problem-prone attributes.

Adolescent↗

PubMedDate not supplied

Prospective correlates of exclusive or combined adolescent use of cigarettes and smokeless tobacco: a replication-extension.

This one-year prospective study provides an extension of a previous cross-sectional investigation. The previous study found that the number of tobacco products used (i.e., smokeless tobacco, cigarettes), not type of tobacco product, was associated with higher scores on problem-prone variables. In the present study, a sample of 842 southern California seventh-grade adolescents who had not tried either cigarettes or smokeless tobacco were identified and surveyed one year later. Onset of tobacco use was examined as an outcome variable predicted by scores on four psychosocial and two alcohol use variables in seventh grade. Unlike the previous study, females were included in the current study, and the potential moderating effect of gender on the pattern of predictors was examined. Overall, these findings indicate that onset of cigarette smoking or use of both tobacco products is associated with alcohol use, risk taking, and low self-esteem. This study provides modest support for the previous investigation. In addition, two of the predictor variables were found to interact with gender. Risk-taking was found to have a stronger association with initiation of tobacco use for females than males. Susceptibility to social influence to use tobacco was found to be associated with initiation of tobacco use for males only.

Adolescent↗

PubMedDate not supplied

Neurotoxicity in single photon emission computed tomography brain scans of patients reporting chemical sensitivities.

The subset of patients reporting chemical sensitivity with neurocognitive complaints usually exhibits specific abnormalities of brain metabolism consistent with neurotoxicity, on imaging with single photon emission computed tomography (SPECT). These recurrent neurotoxic patterns are characterized by a mismatch in tracer uptake between early- and late-phase imaging, multiple hot and cold foci throughout the cortex, temporal asymmetry and increased tracer uptake into the soft tissues and, sometimes, the basal ganglia. Previous studies confirm these neurotoxic findings in patients with neurotoxic chemical exposures and breast implants. Affective processes such as depression do not, alone, show this pattern. These abnormalities in SPECT images correlate with documented neurocognitive impairment. Controlled challenges to ambient chemicals can induce profound neurotoxic changes seen on SPECT imaging in chemically sensitive patients. Detoxification treatment techniques frequently produce significant improvement on brain SPECT brain imaging in these patients. Neurotoxicity appears to be characteristic in many cases of chemical sensitivity.

Brain↗

PubMedDate not supplied

Single photon emission computed tomography of the brain in patients with chemical sensitivities.

Chemical sensitivities display a recurrent pattern on scintigraphic examinations of the brain. The pattern can include mismatching between early and late imaging, multiple hot and cold foci distributed throughout the cortex without regard to lobar distribution (salt and pepper pattern), temporal asymmetries, and sometimes increased activity in the basal ganglia. This study used Desert Shield/Desert Storm veterans who present with abnormal neurological and psychological symptoms as a model to exhibit abnormalities by brain scintigraphy. These are typical of those seen in patients with documented exposure to neurotoxic compounds who develop a clinical syndrome that has been termed "chemical sensitivity." Exposure to cocaine, alcohol, and other substances of abuse can result in abnormal scintigrams of the brain using tracers such as [technetium-99m]hexamethylpropyleneoxime. This study used techniques combining regional cerebral blood flow data with delayed distributional data after the intracellular conversion of the tracer into a hydrophilic molecule. In addition to delayed image abnormalities, a mismatch occurs in the regional activity between the two image sets of the veterans. This degree of mismatch was not seen in control subjects who were screened for avoidance of neurotoxic agents. Patterns identified from examinations performed on patients with known exposure to petroleum distillates, pesticides and other materials linked with neurotoxicity were identified in some veterans of the Desert Shield/Desert Storm operation. A single case of repeated examinations on a veteran showed a reversion of these patterns toward normal after therapy. This reversion followed independent assessments of clinical improvement.

Adult↗

PubMedDate not supplied

Cartilage space width in slipped capital femoral epiphysis: the relationship to cartilage necrosis.

The radiolucent cartilage space of eighty-three patients with unilateral or bilateral slipped capital femoral epiphysis was measured by a standardized technique. In the majority of patients, whether unilateral or bilateral involvement, there was bilateral narrowing of the cartilage space. In the unaffected hip of unilaterally involved patients, there was a progressive narrowing as skeletal maturity was attained. A concomitant anatomical study of cadaver hips, removed at autopsy from adolescent patients, showed a progressive narrowing of the cartilage as the proximal femur matured. Black females showed most narrowing (minimum cartilage space width), had the narrowest final cartilage space widths, and took the longest to attain this final width. While other racial, sexual and therapeutic groups failed to demonstrate statistically significant differences, the general trend was for females, Blacks, and patients treated by osteotomy to have more joint space narrowing. However, rewidening occurred in most of these affected joint spaces, in contrast to the progressive linear decrease observed in unaffected hips and anatomical specimens. On the basis of this study, we feel that cartilage space narrowing may be anticipated in the post-operative period in most patients treated for slipped capital femoral epiphysis. This narrowing appears to improve with time. Narrowing of greater than one-half the original width, in association with pain and limitation of joint function, probably represents "cartilage necrosis," or pathologic joint space narrowing. Unless the narrowing remains less than one-half to two-thirds of the initial cartilage space for more than twenty-four to thirty-six months, probably no specific surgical treatment should be undertaken, other than observation and protected weight bearing during any painful phase. Plotting the roentgenographic cartilage space width during the three month to thirty-six month phase may be useful in monitoring and predicting the outcome.

Adolescent↗