Clay pica has no hematologic or metabolic correlate in chronic hemodialysis patients.

OBJECTIVE: Clay pica is a form of compulsive ingestion of non-nutritive substances frequently practiced by dialysis patients. Its consequences are unknown. In this study, we evaluated the effect of regular consumption of clay on hematologic and metabolic profiles in hemodialysis patients. DESIGN: A prospective, case-control study with use of structured questionnaire. SETTING: Free-standing hemodialysis units. PATIENTS: One hundred thirty-eight patients on hemodialysis for at least 12 months were interviewed. Thirteen of 138 (9.4%) confessed to clay pica. Ten randomly selected patients with no history of pica served as control. INTERVENTION: Average of all laboratory profiles and interdialytic weight gain (IDWG) over a 3-month period were recorded. Assay of the aluminum (Al), silica (Si), and iron (Fe) content of commercially purchased clay was performed. MAIN OUTCOME MEASURE: Comparison of laboratory profiles and IDWG between cases and control. Estimation of the daily consumption of Al, Fe, and Si from clay and their relationship to the laboratory profiles. RESULTS: There was no statistically significant difference in the levels of Al, albumin, calcium, ferritin, hematocrit, iron saturation, phosphorus, and IDWG between pica cases and control. Iron was significantly higher in pica patients (13.0 +/- 7.9 micromol/L v 7.5 +/- 2.5 micromol/L, P =.04), but potassium was higher among control than pica cases (4.9 +/- 0.7 mmol/L v 4.4 +/- 0.6 mmol/L, P =.07). Estimated metal exposure from daily clay consumption per patient were: Al (1-2 mg), Fe (11-23.5 mg), and Si (2-4.5 g). Multivariate logistic regression analysis failed to show any association between clay consumption and nutrition, anemia, or mineral metabolism (R(2) = 0.0, P =.79). CONCLUSION: Clay pica does not appear to be detrimental to the hematologic and metabolic milieu of hemodialysis patients. The practice should, however, be discouraged, because of potential for ingestion of unknown substances, and reported potential for gastrointestinal complications.

Further studies on cyclic erythropoiesis in mice.

When young adult female W/Wv mice are given 0.5 micro+Ci 89Sr/g body weight intravenously, their hematocrit values oscillate from nadirs of 26% to zeniths of 42% with a periodicity of 16 days [1]. The response of the W/Wv mouse to an assortment of radioactive and hematologic stresses have been examined in an effort to understand better the pathophysiology of cyclic erythropoiesis. When the dose of 89Sr is increased, the amplitude of cycling increases as nadirs are lowered, but periodicity is unchanged. When the dose of 89Sr is lowered to 0.3 microCi or less, cyclic erythropoiesis of substantial amplitude is observed only after five or six microoscillations. A single hematopoietic insult of 80 rad x-irradiation coupled with phlebotomy produces a transient form of cyclic erythropoiesis, namely, a series of dampened oscillations prior to recovery. Finally, we report that Wv/Wv mice exhibit a form of cyclic erythropoiesis in response to 0.5 microCi 89Sr/g body weight, in which the hematocrit values of successive nadirs gradually increase, and stabilize at about 100 days. 89Sr does not induce cyclic erythropoiesis in the +/+, W/+, or W/v/+ mice, the Hertwig strain of anemic mice, or in normal BDF1 mice.

Cyclic erythropoiesis in the S1/S1d mouse.

Previously we reported that when young adult female W/Wv mice are given 0.5 microCi strontium-89 per gram body weight IV, their hematocrit values oscillate from nadirs of 26% to zeniths of 42% with a periodicity of 16 days. We now report that a second strain of congenitally anemic female mice, the S1/ S1d , also exhibit large fluctuations in their hematocrit values following a dose of 0.5 microCi 89Sr/g body weight. The zeniths through which these mice cycled averaged 37% (range 35%-38%) and the nadirs averaged 13% (range 12%-14%). Reticulocytes fluctuated from highs averaging 40% (range 35%-45%) to lows that averaged 3% (range 1%-5%). The periodicity of cycling in these eight mice ranged from 16 to 19 days. The hematocrits of three out of five non-strontium-treated mice were found to cycle spontaneously in the absence of 89Sr-mediated hematopoietic insult, with nadirs averaging 22% and zeniths averaging 39%. Similarly, doses as small as 0.1 microCi 89Sr/g body weight coupled with antecedent phlebotomy induced cyclic erythropoiesis of substantial amplitude (average nadir 16% and average zenith of 39%). Splenectomy in the S1/ S1d mouse eliminates both spontaneous and 89Sr-induced cyclic erythropoiesis. If the spleen is removed prior to radiostrontium treatment, then cyclic erythropoiesis is not observed following a dose of 0.5 microCi 89Sr/g body weight.

Cyclic erythropoiesis in W/Wv mice following a single small dose of 89Sr.

Young adult female W/Wv mice were given 0.5 microCi 89Sr/g intravenously, a dose which produces no anemia and only mild transient thrombocytopenia in normal mice. In the W/Wv animals platelet counts fell from 10(6) to 3 x 10(5)/mm3, and hematocrits from 39% to 25% in two weeks. In the following 2 weeks, platelet counts rose to 7 x 10(5), stabilizing at this level. Average hematocrit values were observed to oscillate from a nadir of 26% to a zenith of 42%, with a periodicity of about 16 days. In a repeat experiment we found the average hematocrit fluctuation from 28 to 40%, amplitude of reticulocyte fluctuation 6 to 31%, periodicity of cycle 16 days. Several animals have been observed through as many as six complete cycles. Further study of cyclical erythropoiesis in the W/Wv mouse following hematopoietic injury produced by 89Sr may shed light on the causes of cyclical hematopoiesis observed occasionally in man and other animals.

The erythropoietic effect, in mice, of androgens combined with hypoxia.

Progressively higher levels of erythrocytosis were observed in female mice residing at simulated altitudes of 9, 12, and 18 thousand feet. Administration of testosterone enhanced red-cell production in female mice under all but the most severe hypoxic conditions. The spleen contributed to the extent of erythropoiesis produced by hypoxia and by the combination of hypoxia and androgen, but this extramedullary site of red-cell formation was not necessary for erythrocytosis to occur. As little as 0.1 mg of testosterone enanthate weekly had an erythropoietic effect in female mice residing at 12,000 feet. Normal male mice also responded to hypoxia, but did not demonstrate a further erythropoietic effect in response to the concurrent administration of androgen.

Reflectance spectroscopy: application of the Kubelka-Munk theory to the rates of photoprocesses of powders.

The Kubelka-Munk theory of reflectance spectroscopy is used to derive an approximate equation that describes the rate of the photoprocess of a powdered sample in terms of the remission function. The equation is compared with one obtained using the particle model theory of diffuse reflectance and with experimental data for the photochemical reaction of powdered K(3)[Fe(C(2)O(4))(3)]-3H(2)O.

Diffuse reflectance spectroscopy: a comparison of the theories.

The various theories of diffuse reflectance spectroscopy are compared mathematically, and it is concluded that the modified particle model theory is probably the most nearly correct. If so, the comparison shows that the simple, easily applied simplified particle model theory is approximately valid for relative index of refraction values of 1.5-2.5 and that the Kubelka-Munk remission function is approximately applicable in the traditional sense. Expressions were obtained for the Kubelka-Munk constants in terms of the fundamental optical parameters, and the depth of penetration of radiation into a powdered sample was investigated.