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Biomedical subjects

R McHugh

Publications and source records attributed to R McHugh.

31 records · Page 2Linked to original sources
PubMed1978

Second neoplasms following megavoltage radiation in a pediatric population.

Previous reports of radiation-related neoplasia have relied primarily upon patients treated by orthovoltage to low doses for benign disease. This survey is believed to be the first to assess the incidence of second neoplasms following megavoltage therapy. The source was the records of all long-term pediatric survivors (88 patients) who were treated with megavoltage radiation (cobalt 60) at the University of Minnesota. There was an average follow-up period of 14 years during which 7 second neoplasms were discovered (8%). Five were not associated with prior radiation. Both radiation-related neoplasms were associated with low doses and one was without significant morbidity. Two of the seven neoplasms were malignant; one was not associated with radiation while the other was associated with prolonged chemotherapy and low dose radiation (1%). The only fatal second neoplasm was not associated with radiation but developed 5 years after prolonged chlorambucil treatment. This review reveals the tendency of childhood cancer victims to develop other neoplasms regardless of radiation. The finding of neoplasia induction only at low radiation doses supports the Gray hypothesis of decreased tumor induction at high doses through increased cell killing.

Adolescent↗
PubMed1978

Electromyographic feedback and physical therapy for neuromuscular retraining in hemiplegia.

Electromyographic feedback was compared with physical therapy for its relative effectiveness in training motor activity in patients with hemiplegia. A cross over design was used, so that each patient served as his own control. Strong reinforcement for attentional direction and for successful response to established criteria was used with both modalities. Electromyography through auditory and visual display was found effective in improving electromyographic activity, but more limited in training effective function as measured by active range of motion. In some cases it was counterproductive. Using an instrumental modality permits attention to only a limited number of motor elements involved in a motion, and is even more limited with respect to the interplay of activation and inhibition of those components. The activity of physical therapy, using tactile, proprioceptive, visual and communicative modalities, has the capacity for attending and drawing attention to many motor elements, as well as to the complexities of activation of some components concomitantly with the inhibition of others during the training process. Electromyographic feedback was felt to be especially useful in its ability to enhance figure-background discrimination and bypass possible areas of sensory obtundation.

Aged↗
PubMed1977

Osmolality changes during hemodialysis. Natural history, clinical correlations, and influence of dialysate glucose and intravenous mannitol.

We studied the influence of both a high-glucose-concentration dialysate (717 mg/dl) and intravenous mannitol (1g/kg) on the serum osmolality changes in stable patients on chronic dialysis. During regular dialysis, serum osmolality fell 10 mosmol/kg H2O. This fall was reduced to 5.2 mosmol/kg H2O when the high-glucose-concentration dialysate was used, and to 4.3 mosmol/kg H2O when intravenous mannitol was used. When the two methods were combined, the serum osmolality fall was reduced to 1.7 mosmol/kg H2O. The clinical signs of disequilibrium declined (from 67% to 10%) in parallel with the decline in serum osmolality changes. This fall was independent of the ultrafiltration rate. A high-glucose-concentration dialysate and intravenous mannitol can each reduce the osmolality changes that occur during hemodialysis, but when used alone, intravenous mannitol is more effective of the two. The reduction of osmolality changes also leads to reduction of the mild clinical signs usually associated with disequilibrium.

Adolescent↗
PubMed1977

Estimation of relative risk from matched pairs in epidemiologic research.

The matched pairs design is often used in epidemiologic research, both in prospective and retrospective studies. The Kraus estimator of relative risk (1958) has been derived in a number of ways. The development presented here employs an unconditional likelihood function. The estimator is shown to be valid only when disease incidence is low and relative risk is constant over the levels of the covariate. Asymptotic variances are derived.

Epidemiologic Methods↗
PubMedDate not supplied

Validity and treatment dilution in Zelen's single consent design.

Employing randomization theory, this note examines the manner in which a clinical trial employing Zelen's randomized consent design yields an estimated treatment effect free of selection bias. We also examine the concept of 'treatment dilution' in this design.

Clinical Trials as Topic↗
PubMedDate not supplied

Epidemiologic study of prostatic cancer: preliminary report.

In a preliminary report on a small fraction of the projected subject population, some evidence in support of both sexual activity and venereal transmission hypotheses is accumulating. Prostatic cancer cases, in contrast to hospitalized and/or neighborhood controls, are beginning to show greater proportions of selected sexual activities compatible with venereal transmission of an infectious agent, such as number of sexual partners, use of prostitutes, prior venereal disease, and genital infections in the spouse. Patients with prostatic cancer also appear to have had higher fertility and more prostatic cancer in blood relatives than controls. Age at first intercourse and at first marriage are lower among the cancer patients than among the controls. Antibody titrations for herpesvirus and cytomegalic virus, although currently not revealing striking disparities in positivity, tend to show higher titers among the cancer cases.

Adult↗