Erythemal UV radiation across Nigeria: where do we stand?

The deleterious effects of solar ultraviolet (UV) radiation on humans are of public health concern which demands constant global monitoring and intervention. This study analysed the latitudinal variations in mean daily and multi-year erythemal ultraviolet radiation (EUVR) across 7 states in Nigeria using satellite data from the Total Ozone Mapping Spectrophotometer (TOMS) and Ozone Mapping Instrument (OMI). The latitudes studied were 13° N, 8° N, 6° N and 4° N respectively, using 37 years of data obtained from phases: 1979-1988, 1989-1998, 1999-2008 and 2009-2020. The data obtained were statistically analysed using Ms Excel and MATLAB. The results of this study show that the mean daily EUVR at the selected latitudes ranges from 32.97 to 390 (mW/m2). The results show that Borno State located at latitude 13° N had the highest EUVR, while Rivers State recorded the least EUVR at latitude 4° N. Comparative analysis of all the locations studied indicates latitudinal and longitudinal variations because the eastern axis recorded higher values than its western counterpart on the same latitude. Box and whisker plots in this study summarized the latitudinal variance in the mean multi-year EUVR in each phase. Box and whisker plots from 2009-2020 showed that there was a drastic reduction in mean multi-year EUVR in this phase unlike in the other phases. The findings of this study when compared to the UV index show that the 37 years mean EUVR obtained across Nigeria ranged from 8-10 which is on the "very high" category. This study recommends the implementation of WHO suggestions in preventing the biological effects of solar UV radiation. Furthermore, the Nigerian government should curb ignorance among its citizens by heightening public awareness of the effects of EUVR.

Reevaluation of submerged vital roots.

A total of eight vital roots were submerged and retained under complete dentures in two patients. Within two to three years, each patient experienced problems of pain, re-exposure, and inflammation, resulting in the removal of the roots. Histologic evaluation showed evidence of chronic inflammation of the pulpal tissue. Because of alveolar resorption and perhaps super-eruption of the submerged roots, the likelihood of exposure and abscess is a distinct disadvantage to the procedure. Therefore, some doubt remains as to the long-term success with this technique.

Endothelial cell activity in experimental hypertension. Effects of hemodynamic factors.

The cause of the increased endothelial cell proliferative activity found in experimental hypertension in the rat is not clear. In this experiment the part played by altered vascular hemodynamics was explored in a model in which part of the aorta was subjected to a high blood pressure and the other not. Hypertension was produced by the application of a tight ligature to the aorta between the levels of the two renal arteries, the mechanism being interference with the blood supply to the more distally placed kidney. Because the aorta is constricted, the segment above the ligature is subjected to high blood pressure and the segment below it to lowered pressure, although both segments are exposed to humoral factors such as renin and angiotensin II. Aortic endothelial cells were labeled with tritiated thymidine and cell replication and cell density studies carried out using en face monolayer preparations of endothelium. It was found that endothelial cell replication was considerably increased at 7 days following induction of hypertension in segments of aorta above the ligature but not in the segment below the ligature. The increased activity was short-lived and had returned to normal levels at 4 weeks. Cell density was increased above the ligature at both 1 and 4 weeks following induction of hypertension. The changes are consistent with the idea that the increased cell replication and consequent increased cell density above the ligature were initiated by the increased stretching of the aortic wall attending the development of hypertension.

Aortic endothelial cell activity in high renin and normal renin models of hypertension in the rat.

To determine whether renin or angiotensin might have an effect on endothelial cell activity, we studied cell replication and cell density in two models of hypertension in the rat. The first was a model in which the plasma renin activity was high during the three time periods studied (1, 2, and 4 weeks after renal artery constriction) and the second, a model with elevated plasma renin activity only during the initial period (1 weeks). Aortic endothelial cells were labeled with tritiated thymidine period to killing, and en face endothelial cell monolayers were prepared. The ratio of labeled cells to total cells (thymidine index) and the ratio of total number of cells to number of fields observed (cell density) were calculated for the whole aorta, segments of the aorta, and zones within the segments. In both hypertensive models, an elevation of the thymidine index (indicative of increased endothelial cell replication) was observed at 1 week but not at subsequent times when the levels had returned to those of the controls. Cell density was increased at all time periods studied and like the thymidine index showed no significant differences between the two hypertensive models. Although renin or angiotensin (or other humoral factors) could have been responsible for the increased thymidine index after 1 weeks, it is considered that hypertension itself it a more likely cause, taking into account the decreased indices at later time periods when one model has high renin levels and the other does not. The increased cell density at all time periods studied in both models is regarded as an adaptive reaction to the increased blood pressure.

Satellite laboratory services: a blending of form and function.

In March, 1980, Holzer Clinic, Ltd., a 45-physician multispecialty group practice located in southeastern Ohio, started its own clinic laboratory operation at a facility some four miles from the clinic building. To the clinic, this significant event signaled a major departure in operations, concept and philosophy.