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Biomedical subjects

M R Cullen

Publications and source records attributed to M R Cullen.

At least 91 records · Page 5Linked to original sources
PubMed1983

Depressed thyroid indexes associated with occupational exposure to inorganic lead.

The finding of low values for serum thyroxine and estimated free thyroxine in seven of 12 workers referred because of elevated blood lead levels (greater than 40 mg/L) prompted further investigation. In a cross-sectional study of workers at a small foundry, both measurements were found to regress negatively with blood lead level. In 12 of 47 subjects, both indexes were in the hypothyroid range. Serum thyrotropin and triiodothyronine levels in patients and study subjects with low indexes were all normal. Physical examinations failed to demonstrate the classic features of hypothyroidism. These data are compatible with a central depression of the thyroid axis or an alteration in thyroxine metabolism or binding to proteins. Irrespective of mechanism, the association between low thyroid indexes and elevated lead levels merits attention because of the large number of workers exposed to lead and the similarities between the clinical features of adult lead poisoning and hypothyroidism.

Adult↗
PubMed1981

Lipoid pneumonia caused by oil mist exposure from a steel rolling tandem mill.

Five of nine active tandem mill operators exposed at work to aerosolized hydrocarbon mist were referred for evaluation of respiratory complaints. The worker with the longest exposure had reduced lung volumes; he was admitted to the hospital for detailed study. Exercise studies revealed work load limited by ventilation and arterial oxygen desaturation. Flexible fiberoptic bronchoscopy with bronchoalveolar lavage and transbronchial biopsy revealed evidence of lipoid pneumonia. Assessment of the mill revealed levels of respirable oil mist by personal samplers throughout the area far below the currently accepted standard of 5 mg/M3. These findings confirm a 20-year-old hypothesis of J.G. Jones regarding the hazard of oil mist in this industrial setting.

Adult↗
PubMed1980

Ultrastructure of Merkel cells in the hard palate of the squirrel monkey (Saimiri sciureus).

The distribution and ultrastructure of Merkel cells in the hard palate was investigated in the squirrel monkey (Saimiri sciureus) after fixation by vascular perfusion. Merkel cells were clustered at the base of the epithelial rete pegs of the hard palate. They were characterized by concentrations of dense-cored granules and closely associated intraepithelial nerve endings. Numerous spiny processes extending from the Merkel cell were intercalated with adjacent keratinocytes, probably serving to detect and amplify movement of adjacent cells. These spiny processes contained a rigid core of parallel microfilaments which were interrelated with cytoplasmic filament bundles located beneath the cell membrane. Transitional cells containing dense-cored granules and well developed tonofibrils appear to be related to both Merkel cells and keratinocytes. The findings of this study suggest that Merkel cells are highly adapted for detection of movement in adjacent keratinocytes, as well as movement of the epithelium with respect to the underlying connective tissue.

Animals↗
PubMedDate not supplied

Bone marrow injury in lithographers exposed to glycol ethers and organic solvents used in multicolor offset and ultraviolet curing printng processes.

Prompted by referral of a printer with aplastic anemia, a study of possible marrow toxicity of workplace substances was undertaken. Dermal and respiratory exposures to dipropylene glycol monomethyl ether, ethylene glycol monoethyl ether, and a range of aliphatic, aromatic and halogenated hydrocarbons used for offset and ultraviolet cured multicolor printing were documented. Evaluation of seven co-workers revealed normal peripheral blood pictures, but bone marrow specimens demonstrated clear patterns of injury in three while the others had nonspecific signs of marrow effect. These changes could not be explained by known risk factors. The authors conclude that further evaluation of possible bone marrow toxicity resulting from exposure to glycol ethers and ultraviolet curing printing processes is warranted. More generally, we have provided data demonstrating that peripheral blood counts may be an insensitive tool for the study of hematologic toxins acting at the bone marrow level.

Adult↗
PubMedDate not supplied

Endocrine and reproductive dysfunction in men associated with occupational inorganic lead intoxication.

In an attempt to define a postulated effect of lead on male endocrine function, seven men with symptomatic occupational lead intoxication (maximum whole blood lead levels 66-139 micrograms/dl) underwent in-patient endocrine evaluation at the time of diagnosis. Defects in thyroid function, probably of central origin, were present in three patients. Six patients had subnormal glucocorticoid production measured by 24-hr urinary 17-hydroxycorticosteroids and plasma cortisol responses to vasopressin- and/or insulin-induced hypoglycemia. Although serum testosterone concentration was normal in six patients, five had defects in spermatogenesis, including two with oligospermia and two with azoospermia. Repeat examinations after chelation therapy showed only partial improvement. It is concluded that heavy occupational exposure to lead, sufficient to cause clinical poisoning, may be associated with diffuse disturbances of endocrine and reproductive functions in men which are not rapidly reversible with standard treatment. Since men without overt poisoning have not been studied, these results cannot yet be included as sequelae of low-dose exposures.

Adrenal Cortex Function Tests↗
PubMedDate not supplied

Birth weight, maternal age, and education: new observations from Connecticut and Virginia.

It has been well established that increased maternal education, income, and social status contribute to increased birth weight, as well as reduced risk for low or very low birth weight offspring. However, there remains controversy about the mechanism(s) for this effect, as well as the interactions between these factors, maternal age, and race. Presented here is the analysis of a large, recent sample of over 20,000 consecutive live births in 12 hospitals, about half in Connecticut and half in Virginia, including a maternal population that is educationally and racially diverse. Although information on potentially relevant details such as prenatal care, smoking, occupation, and neighborhood is lacking the data set, there is sufficient information to explore the previously noted strong effect of maternal education on birth weight, as well as the large racial difference in outcome at every educational level after adjustment for the effects of age, marital status, state of residence, and gender of the offspring. However, this relationship was not monotonic, and there were differences in the effect between the white and black families, with black women showing a linear and consistent benefit from education across the range, while whites show a sharp benefit from completion of primary education, less from subsequent schooling. A surprising result was the apparent negative impact of very advanced education (>16 years), with lowered birth weights and higher risk of low birth weight offspring in the women with post-college training. The data also shed some addition light on the effect of age and birth weight. Whites show established improvement in birth outcome to about age 30, with slight decline thereafter, whereas in blacks there was progressive decline in birth weight with rising age starting in adolescence, as previously demonstrated by Geronimus. An additional unexpected observation was a sizable difference between births in Connecticut (larger, fewer low birth weight) than Virginia, correcting for all other covariates. It is hypothesized that this may reflect differences in services used, prenatal care in particular given similarities in smoking rates and other predictors. Because of the non-representativeness of and the limited information available in the present study, the conclusions should be taken as hypotheses for further research rather than definitive.

Adolescent↗
PubMedDate not supplied

Controversies in asbestos-related lung cancer.

Despite clear agreement that asbestos exposure causes lung cancer and despite prodigious research efforts in clinical, epidemiologic, toxicologic and mineralogic aspects of the problem, wide disagreement exists in the scientific community on many crucial points. Put in the simplest way neither the biologically relevant measure of dose nor the full shape of the dose-response curve at either the high or (especially) low end is understood. Nor is the relationship between the carcinogenic potential of the fibers and their fibrogenic properties. In the long run, full resolution of these issues will probably require the unravelling of the basic mechanisms by which the fibers induce cancer; unfortunately, despite recent progress, this understanding is probably too far off to be of use in the solution to the very real, omnipresent clinical and public health cancer-control problems. Decisions will have to be made using data sets far less satisfactory. Hopefully, by pursuing some of the avenues suggested in the sections above, enough can be learned to facilitate more rational approaches to the problems at hand.

Asbestosis↗