Design and conduct of occupational epidemiology studies: III. Design aspects of case-control studies

Currently available approaches for the design of occupational case-control studies are reviewed. An accompanying paper reviews methods of analysis. We commence by drawing a distinction between cohort-based and registry-based studies. Methods for selecting cases and controls are then reviewed, including cumulative incidence and incidence density sampling, matching, sources of controls, and issues in control selection. Finally, the advantages and disadvantages of the case-control approach are summarized.     

Assessment of echographic regression criteria in ruthenium-irradiated melanoma

Steady flattening of the tumor, increasing reflectivity and decreasing vascularity are echographic signs of successful irradiation treatment. The specific example of an irradiated choroidal melanoma shows that the absence of echographic changes by no means excludes tumor destruction. Because of a dense vitreous body hemorrhage, the melanoma could only be evaluated echographically. Since the echogram lacked evidence of regression, the tumor was locally resected 5 months later. Histology, however, revealed an amorphous mass of dead tissue pervaded by intact vessels. Apparently a successfully irradiated melanoma may generate an echo typical of vital melanoma tissue. The authors therefore draw the conclusion that only a steady tumor growth, as substantiated by an echogram, may be considered an unambiguous sign of tumor vitality.     

Uveal melanoma radiation. 125I brachytherapy versus helium ion irradiation

The optimum radiation therapy for uveal melanoma is uncertain. Both helium ion irradiation and 125I brachytherapy have been used to treat this neoplasm. This investigation analyzed the control and complication rates of uveal melanomas treated with helium ions of 125I plaques. In both a retrospective and a prospective dynamically balanced study, the control rates appeared to be similar. There were more posterior segment complications after 125I plaques and more anterior segment complications, including neovascular glaucoma, after helium ion irradiation. The follow-up period is too short to draw definitive conclusions on the radiation complications. Overall, approximately 89% of eyes were retained and less than 4% of treated eyes were removed because of failure to control the tumor.     

Effects of vasodilator drugs on venous tone in conscious rats

The dose-response effects of vasodilator drugs, nitroglycerin, sodium nitroprusside and hydralazine, on mean arterial pressure (MAP) and mean circulatory filling pressure (MCFP), an index of body venous tone, were investigated in conscious, unrestrained, intact rats as well as in rats treated with the ganglionic blocker, hexamethonium. The effects of these drugs were compared with those of the vehicle, normal saline, in control rats. In intact rats, i.v. infusion of nitroglycerin did not alter MAP while i.v. infusions of nitroprusside or hydralazine caused dose-dependent decreases in MAP. After ganglionic blockade, all three drugs decreased MAP. In intact rats, nitroglycerin and sodium nitroprusside did not affect MCFP but hydralazine increased MCFP. After treatment with hexamethonium, all three drugs decreased MCFP. The decreases in MCFP caused by nitroglycerin and nitroprusside, but not that by hydralazine, were significantly greater than the corresponding changes in control rats. Thus, in intact rats, the direct venodilator actions of nitroprusside and nitroglycerin were masked by endogenous sympathetic tone. When sympathetic nerve activity was attenuated, both nitroprusside and nitroglycerin have venodilator effects. Hydralazine, on the other hand, had insignificant venodilator effect both in the presence and absence of sympathetic reflexes.     

Does a common pathophysiological basis exist in the association of ulcerative colitis and Takayasu's aortitis? Report of a case.

A case of a young Japanese woman with long-standing ulcerative colitis complicated by preinfarction angina due to Takayasu's aortitis is presented. Successful emergency aorto-coronary bypass operation was performed. Whether the association of these two diseases can be explained by a common mechanism is discussed.     

St. Jude Medical valve replacement: clinical experience with 1,039 patients

St. Jude Medical valve replacement was performed in 1,039 patients; 320 had aortic (AVR), 543 mitral (MVR), and 176 had double valve replacement (DVR). There were 44(4.2%) early deaths. Follow-up extended in 995 patients from 10 to 130 months, with a cumulative period of 2,730 patients-years. The overall survival rates of AVR, MVR, and DVR patients at 10 years were 60.5%, 89.6%, 90.3% respectively. The linearized incidences of valve thrombosis, thromboembolism, anticoagulation-related hemorrhage, prosthetic valve endocarditis, and significant hemolysis were as follows: 0.11%/pt-yr, 1.33%/pt-yr, 0.04%/pt-yr, 0.18%/pt-yr, and 0.11%/pt-yr, respectively. There were no structural failure after 10 years follow-up. Reoperation (explant and re-replacement or suture repair) was required in 10 patients. Seven of them had periprosthetic leakage, 2 had valve thrombosis, and one underwent reoperation because of a technical error. Actuarially over 98% of patients were free of valve-related mortality at 10 years. St. Jude Medical valve is an excellent alternative for use in the surgical treatment of valvular heart disease.     

Attempt at predicting paraphrenic outcome in young, first admitted schizophrenic patients

A sample of 110 consecutive first admission young schizophrenic patients treated between 1964 and 1967 was rediagnosed in 1981. Among 92 survivors, 27 could be labelled as paraphrenics. From information available at inception 97 variables were coded covering such areas as personality, previous disturbances, age and type of onset, and symptoms around admission. Sixty-three out of 97 variables were hypothesized to differentiate, at admission, future paraphrenics from the rest of the sample. Paraphrenics were found to have had less contact disturbance, better self-esteem, less neurotic symptoms in adolescence and childhood, and less complaints of unhappiness when growing up. They had more regressive and paranoid symptoms at admission, were older at onset of the disease, which was more acute, more often connected with precipitating events, and confusion. Certain non-regressive symptoms such as brooding, anhedonia and concentration difficulties were less common. A discriminant analysis yielded a proportion of correct predictions = 0.64 (p less than 0.05). The results are in accordance with the theory of more favourable energetic and organizational capacity in paranoid schizophrenics as compared with non-paranoids.