Biomedical subjects
Publications and source records attributed to S A Clark.
Three cases are reported of a lethal multiple congenital anomaly syndrome. The infants had moderate limb shortening, joint contractures, polydactyly, and the two with male karyotypes had female external genitalia. Internal anomalies included unilobular lungs, hypoplasia of the anterior portion of the tongue, and renal hypoplasia.
Breast ultrasound imaging performed with an automated machine was carried out in 89 patients, and images obtained with a conventional ceramic single-focus 4-MHz transducer and a 7.5-MHz polyvinylidene fluoride (PVDF) transducer were compared. The 7.5-MHz PVDF transducer improved overall image quality in 77% of patients and had equal penetration in 83%. It yielded greatly increased diagnostic information in 43% of 81 masses and improved visualization of calcification in 57% of 14 lesions in which calcium was visible on mammograms.
We measured serum somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) concentrations in vitamin D-deficient (-D) rats from 3-7 weeks of age to evaluate the role of Sm-C/IGF-I in the growth effects of vitamin D. To exclude effects of alterations in food intake, feeding patterns, and plasma minerals, controls included the following groups: pair fed (PFC; n = 10), low calcium diet (LCa; n = 10), meal fed (MFC; n = 10), and ad libitum fed (AdLC; n = 5). The -D, LCa, and PFC groups had similarly depressed growth rates and Sm-C/IGF-I concentrations. The growth and Sm-C/IGF-I concentrations of the MFC group were less than those in the AdLC group, but greater than those in the -D, PFC, and LCa groups. In all groups Sm-C/IGF-I concentrations correlated well with food intake, indicating that calorie intake, and not vitamin D deficiency or hypocalcemia, was the primary factor in reducing Sm-C/IGF-I. In the final 4 days of the study, half of the -D rats were given 1,25-dihydroxyvitamin D3 (2 ng/g BW;-D/repleted), while half of the PFC rats were given excess food during the meal period (PFC/refed). The weight gain of -D/repleted rats surpassed that of the -D rats treated with vehicle (P less than 0.05); similarly, the weight gain of PFC/refed rats exceeded that of the PFC rats (P less than 0.01). In contrast, the food intake and Sm-C/IGF-I levels of PFC/refed rats were greater than those in PFC rats (P less than 0.01), while the -D/repleted rats did not have significantly altered food intake or Sm-C/IGF-I levels. We conclude 1) that alterations in Sm-C/IGF-I concentrations of young growing -D rats are not directly related to lack of vitamin D, but, rather, to poor nutrition resulting from reduced food intake; and 2) that serum Sm-C/IGF-I is not a primary mediator of growth in -D/repleted rats since improved weight gain resulting from 1,25-dihydroxyvitamin D3 treatment can occur, acutely, without changes in serum Sm-C/IGF-I concentrations.
The adrenocortical tissue which regenerates after adrenal enucleation, and contralateral uninephrectomy and adrenalectomy, resembles histologically zona fasciculata tissue which normally synthesises glucocorticoids. However, increases in blood pressure after enucleation (adrenal regeneration hypertension-ARH] were preceded by a rise in exchangeable body sodium similar to that found with mineralocorticoid-induced hypertension (e.g. DOC/salt rat model). Glucocorticoid involvement in ARH rats was tested, firstly by infusing dexamethasone into control and ARH rats to see whether ACTH suppression would lower blood pressure by reducing adrenocortical activity and, secondly, by infusing dexamethasone into rats with intact adrenals to see whether conditions for ARH (i.e. uninephrectomy and/or saline consumption) pre-disposed rats to the hypertensinogenic properties of glucocorticoids. Low-dose dexamethasone infusions (10 micrograms/day for 5 days) in ARH rats did not affect blood pressure but in control animals caused a significant (P less than 0.01) increase from 128 +/- 3 to 151 +/- 5 mmHg. Corticosterone, 18-hydroxycorticosterone and deoxycorticosterone plasma concentrations were suppressed in both groups by dexamethasone treatment; plasma renin concentrations were lower in ARH rats than in controls. Uninephrectomy or 1% NaCl as drinking fluid did not affect the blood pressure rise induced by sc infusion of 10 micrograms dexamethasone/day for 14 days in rats with intact adrenals. The temporal relationship between blood pressure changes and exchangeable body sodium in ARH rats resembles that in mineralocorticoid-induced hypertension. Glucocorticoid, unlike mineralocorticoid, induced hypertension is not affected by a reduction in renal mass or increased sodium intake.
Circulating 1,25(OH)2D3 was determined in female rats between ages 1 and 20 weeks and in male rats between ages 5 and 12 weeks while the rats consumed diets containing vitamin D (5 U/g diet) and calcium concentrations of either 0.04, 0.4 or 1.6% Ca. When consuming the 0.4% Ca diet female rats had mean (+/- SE, pg/ml) serum 1,25(OH)2D3 values of 45 +/- 7 at 2 weeks, 272 +/- 23 at 4 weeks, 221 +/- 18 at 5 weeks and 51 +/- 6 and 49 +/- 4 at 13 and 20 weeks, respectively. Circulating 1,25 (OH)2D3 levels in the males at 4.5, 8 and 12 weeks were insignificantly higher than the levels for the females at comparable ages. There were no significant changes in plasma calcium over the ages examined in either sex. In order to test the efficiency of regulation of circulating 1,25(OH)2D3, 3-week-old female rats were given the 0.04% Ca diet for 2 or 6 weeks. At ages 5 and 9 weeks, serum 1,25(OH)2D3 values were 640 +/- 82 and 604 +/- 39 pg/ml, respectively, and therefore at least 3-fold higher than the values in rats consuming the 0.4% Ca diet. Plasma Ca concentrations in the calcium-deprived rats were 8.7 +/- 0.2 and 6.5 +/- 0.1 at 5 and 9 weeks, respectively. When the 0.04% Ca diet was introduced at 5 weeks of age, plasma Ca fell only 0.5 mg/dl and plasma 1,25(OH)2D3 rose to 1265 +/- 48 pg/ml. In contrast, plasma 1,25(OH)2D3 rose to only 176 +/- 19 pg/ml and plasma Ca fell 0.5 mg/dl when 12-week-old rats were given the 0.04% Ca diet for 5 weeks. When suckling rats were given access to the 1.6% Ca diet and continued to consume this diet after weaning, circulating 1,25(OH)2D3 concentrations were approximately one half the value of the rats consuming the 0.4% Ca diet at 3,4,5 and 6 weeks. We conclude that rats have a biphasic serum 1,25(OH)2D3 curve between the ages of 2 and 16 weeks regardless of the dietary calcium content. Circulating plasma 1,25(OH)2D3 is regulated by dietary calcium as early as the third week of life, before weaning. We suggest that the high serum 1,25(OH)2D3 concentrations are due to increased 1 alpha-OHase activity. However, the factor(s) responsible for changes in the 1 alpha-OHase remain(s) unknown, since plasma Ca does not change, and since the plasma level of other regulators of 1,25(OH)2D3, such as phosphate and parathyroid hormone do not correlate with 1,25(OH)2D3.
A leiomyosarcoma of the urinary bladder occurred in a 17-year-old boy who was treated with a total dose of 67 g cyclophosphamide over a period of 5 years for Hodgkin's disease diagnosed at the age of 4. Cyclophosphamide was discontinued at the age of 9 because of gross hematuria, and intermittent hematuria recurred 8 years after (at the age of 17) the cessation of this drug. A large exophytic tumor found in the urinary bladder was diagnosed as leiomyosarcoma by light and electron microscopic studies. In addition, there were microscopic features of long-term cyclophosphamide toxicity throughout the bladder wall.
Autoradiographic and biochemical studies were used to demonstrate 1,25 (OH)2 vitamin D3 target cells in teeth. Incisor pulp of rats and molar pulp of humans were incubated in vitro with 3H-1,25 (OH)2 vitamin D3. Subsequent frozen-section autoradiography revealed a large population of cells in the pulp of both incisors and molars which selectively concentrated radioactivity in their nuclei. Extracts of incisor pulp from mature rats were found to bind 3H-1,25 (OH)2 vitamin D3 and this binding was displaceable with excess 1,25 (OH)2 vitamin D3. Sucrose density analysis revealed that the protein in tooth pulp which binds 1,25 (OH)2 vitamin D3 sediments at 3.2-3.5S. The 1,25 (OH)2 vitamin D3 receptor of intestine and kidney also sediments in this region, indicating that the 1,25 (OH)2 vitamin D3 binding protein of tooth pulp is similar to that found in other target organs. These autoradiographic and biochemical data indicate that pulpal cells of mature rat and human teeth contain receptors for 1,25 (OH)2 vitamin D3.
Target cells for 1,25(OH)2 vitamin D3 metabolites are identified in developing rodent teeth by the use of thaw-mount autoradiography. Following the injection of [26, 27-3H]-1,25(OH)2 vitamin D3 into 18-day- and 20-day-old fetal rats and neonatal mice, nuclear concentration of radioactivity is found in different cell types. In incisors of both animal groups, strong nuclear labeling is present predominantly in pulp cells, while relatively weakly labeled cells are found in the layers of odontoblasts, ameloblasts, and stratum intermedium. In molars, nuclear labeling is absent in fetal rats, but is present in 2-day-old neonates in pulp cells and cells in the layers of stratum intermedium of the first molars, but not in the second molars. The absence of labeled pulp cells in the progenitor regions of incisors and in molars of 20-day-old fetal rats, and differential ontogenic appearance of labeled pulp cells in molars, indicates that there is a critical period of receptor emergence. The finding that labeled pulp cells exist in the regions of incisors and molars where secretory odontoblasts are present suggests that nuclear uptake of 1,25(OH)2 vitamin D3 is related to cell maturation and differentiation, and topographically related to the formation of dentin. The results further suggest that, in contrast to bone, the predominant effect of 1,25(OH)2 vitamin D3 is not on tooth cells which are directly involved in the formation of calcified tissue, i.e., ameloblasts and odontoblasts, but rather on supporting tissues such as pulp cells and stratum intermedium.
In two patients with malignant germ cell tumors angiosarcoma developed through two apparently different mechanisms. In one case the angiosarcoma probably developed as a complication of therapeutic radiation, since radiation changes were demonstrated in tissue adjacent to the neoplasm and since the angiosarcoma was not associated with elements of germ cell tumor. The absence of associated germ cell elements does not support the development of the angiosarcoma from a teratoma. In the second case, however, it is likely that the angiosarcoma developed as a result of malignant change within teratomatous foci, since angiosarcomatous elements were intermingled with teratomatous elements and the patient's primary germ cell tumor contained malignant and atypical teratomatous elements as well as prominent vascular proliferation. Malignant change within teratomatous components of germ cell tumors is a phenomenon of increasing importance in this era of effective chemotherapy for germ cell tumors. The development of angiosarcoma as a potential complication of testicular carcinoma has not been reported previously.
Chlorothiazide (100 mg/kg body weight) was given by gavage daily to spontaneously hypertensive rats for 4 weeks. Another group of spontaneously hypertensive rats was given only tap water and served as control. Measurements of total exchangeable sodium, blood pressure and weight were performed for 2 weeks before and for 4 weeks during treatment. Before treatment, exchangeable sodium, blood pressure and weight were similar in the two groups of rats. Chlorothiazide significantly attenuated the blood pressure increase in spontaneously hypertensive rats, the effect being most marked during the first 2 1/2 weeks of treatment and less thereafter. Rats in the chlorothiazide-treated group gained weight more slowly than did those of the control group. Exchangeable sodium, expressed as mmol/kg body weight, did not differ significantly between the two groups at any stage. When exchangeable sodium was expressed as mmol/rat, there was a more gradual rise in the chlorothiazide-treated animals, in accordance with their slower gain in weight. There was no temporal association between the antihypertensive effect of chlorothiazide and changes in exchangeable sodium. Thus whereas chlorothiazide treatment of spontaneously hypertensive rats slows the increase of both weight and exchangeable sodium, other mechanisms are apparently responsible for the antihypertensive action of the drug.
Hydralazine was dissolved in 0.5% drinking saline (40 mg/1000 ml) labelled with isotope 22Na and given to spontaneously hypertensive rats for four weeks. Another group of rats were given isotope labelled saline only and served as control. Measurements of total exchangeable sodium, blood pressure, pulse rate and weight were performed before and repeatedly during treatment. Before treatment exchangeable sodium, blood pressure, pulse rate, and weight were no different between the groups. The antihypertensive effect of hydralazine was marked and maintained throughout the experiment. No significant changes were found in pulse rate. Both groups gained weight similarly. Exchangeable sodium increased at the same rate in both groups along with the weight increase. Thus, chronic hydralazine treatment effectively reduces blood pressure in spontaneously hypertensive rats without causing measurable sodium or fluid retention.
Eleven male patients had germ cell tumors of the testis (7), mediastinum (3), or retroperitoneum (1) in which non-germ cell malignancies developed. Such malignant non-germ cell elements were present in the primary excisions of five patients and were subsequently found in additional resected tissue in 10 of 11 patients. In the patients who had multiple pathology specimens examined, a progression from atypia to predominant non-germ cell malignancy was often found. The authors believe these malignant elements arose within teratomatous foci, since eight of nine cases had teratoma in the primary tumor, and teratoma was found in subsequently resected tissue in one additional case. Cisplatin therapy frequently "unmasked" the non-germ cell malignant elements by destroying the more chemosensitive germ cell cancers. The prognosis was worst for five patients who developed progressive embryonal rhabdomyosarcoma: two of these patients died of local spread of tumor, whereas a third died of metastatic sarcoma. Only one patient, who had total surgical excision of rhabdomyosarcoma, survived. Other forms of sarcoma that developed within germ cell tumors did not appear to adversely affect the prognosis beyond that of teratoma. It is currently recommended, when feasible, that patients with teratoma and sarcoma undergo total surgical excision. Further treatment with cisplatin regimens, after eradication of the germ cell component, has not been helpful. The role of other forms of chemotherapy remains speculative.
Tritium-labeled 1,25 (OH)2 vitamin D3, when injected into vitamin D-deficient adult and pregnant rats is concentrated and retained strongest in nuclei of cells in the outer root sheath of the hair, followed by the stratum granulosum, spinosum, and basale of the epidermis. In the hair follicle, in addition to the most heavily labeled outer root sheath, nuclear labeling exists also in cells of the hair bulb and of the inner root sheath, as well as in basal cells of the sebaceous gland. In contrast, cells of the dermal papilla and the connective tissue of the dermis are generally unlabeled, except for labeled cells in the outer connective tissue sheath at the infundibulum of vibrissae of 20-day fetal rats and a few scattered labeled cells in the dermis, probably macrophages. In the developing hair, in 18- and 20-day fetal rats, a distinct topographic pattern of labeled cells can be seen, which is characteristic of the different stages of hair follicle development. In the hair germ, heavily labeled cells appear first in the stratum spinosum. In the hair peg, they remain in this position in its juxtaepidermal portion; however, when a dermal papilla develops, heavily labeled cells assume a marginal position. This suggests a sequential epidermal-epidermal and mesenchymal-epidermal receptor induction. Injection of tritium labeled 25 (OH) vitamin D3 did not show nuclear concentration in these tissues and excess unlabeled 25 (OH) vitamin D3--unlike excess 1,25 (OH)2 vitamin D3--did not prevent nuclear uptake of tritium labeled 1,25 (OH)2 vitamin D3. The results indicate differential effects of 1,25 (OH)2 vitamin D3 on different structures in the epidermis and dermis.
Our objectives were to determine whether saralasin, like angiotensin II, raises blood pressure gradually when given by constant infusion and whether either agent alters the diurnal variation of arterial pressure. Eight female Wistar rats were infused intravenously with 5% dextrose for 2 days, then with saralasin at 10 micrograms . kg-1 . min-1 for 4 days, and finally with dextrose for 2 days. Six other rats were infused with angiotensin II (20 ng . kg-1 . min-1) instead of saralasin. Mean arterial pressure (MAP) was recorded continuously. Saralasin and angiotensin II gradually raised MAP in all rats, by 22.0 mmHg on the 4th day of saralasin and by 41.7 mmHg on the 4th day of angiotensin II. Both agents also increased the diurnal variation of blood pressure, MAP increasing 8.3-20.6 mmHg during the night and falling 6.7-19.1 mmHg during the day. Variability of arterial pressure was also increased by saralasin and in an earlier experiment by angiotensin II. We conclude that saralasin has a slow pressor action similar to that of angiotensin II but distinct in its timing both from the rapid agonist action of saralasin and from the acute vasoconstrictor action of angiotensin II. These effects of saralasin may compromise interpretation of experiments in which the drug is given by prolonged infusion to assess the role of angiotensin II.
The concentration of radioactivity is observed in the nuclei of pulpal cells of maxillary and mandibular incisors of 20-day-old fetal rats, following injection of [3H]-1,25 (OH)2 vitamin D3. Cells in the odontoblast and ameloblast layers are essentially free of nuclear labeling. The radioactively labeled pulpal cells exist throughout the length of the incisors with the exception of the progenitor areas. The results indicate the presence of receptors for 1,25 (OH)2 vitamin D3 in pulpal cells, and suggest the effects of the hormone on these cells.
To determine whether impaired insulin release from perifused rat islets of vitamin D-deficient (D-def) rats is a result of vitamin D-deficiency specifically or an associated decrease in food intake, we: 1) compared insulin release from islets of vitamin D-def rats with insulin release from islets of pair fed (pf) normal rats, and 2) measured the effects of 1,25(OH)2D3 treatment on food intake and insulin secretion from islets of D-def rats. Both vitamin D-def and pf normal rat islets showed significantly diminished insulin release in comparison with normal controls but were not different from each other. When D-def rats were repleted with 1,25(OH)2D3, food intake increased and insulin secretion improved during perifusion of rat islets. When D-def rats treated with 1,25(OH)2D3 were prevented from increasing their food intake in response to 1,25(OH)2D3 by pair feeding to a group of untreated D-def rats, insulin release from islets of treated rats was not significantly different from untreated D-def rats. To separate the effects of vitamin D deficiency from hypocalcemia, a group of vitamin D-def hypocalcemic rats was compared with a group of D-def normocalcemic rats. Normocalcemia did not reverse the defect in insulin release. In studies of cellular calcium uptake, both pf and D-def rat islets took up less calcium than normal islets but calcium uptake was not different between pf and D-def rat islets. Our studies suggest that vitamin D deficiency is associated with marked impairment of biphasic insulin release and that the decrease in food intake may account for this impairment at least in part.
Autoradiographic studies with 3H-labeled 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] demonstrate, in certain neurons of rat forebrain, hindbrain, and spinal cord, a nuclear retention and concentration of radioactivity, which can be prevented by treatment with 1,25(OH)2D3, but not with 25-hydroxyvitamin D3. These results indicate the presence of brain receptors in addition to pituitary receptors for 1,25(OH)2D3 and suggest a central modulation of calcium homeostasis and other central effects for this hormone. The existence of a brain-pituitary axis for certain 1,25(OH)2D3-mediated endocrine-autonomic effects is postulated.
Recent autoradiographic studies demonstrated that B-cells concentrate 1,25 (OH)2 D3 in their nuclei, suggesting a genomic action on B-cell function. This study was undertaken to investigate the effects of 1,25 (OH)2 D3 on insulin secretion in vitamin D-deficient rats. Mature vitamin D-deficient rats were injected with 1,25 (OH)2 D3 or the ethanol-isotonic saline vehicle. Administration of 1,25 (OH)2 D3 to 10 rats resulted in a 17 microunits/ml (113%) increase in insulin levels and 0.9 mg/dl (16%) increase in plasma calcium. No changes were found in insulin or calcium levels in 5 control rats given vehicle alone. A group of vitamin D-deficient rats with plasma calcium levels of 5.4 +/- 0.1 mg/dl had insulin levels that were the same as those observed in a group of vitamin D-deficient rats with plasma calcium levels of 6.3 +/- 0.1 mg/dl. The difference in calcium levels between these two groups is similar to the increase in plasma calcium found after 1,25 (OH)2 D3 administration. The results of these studies indicate that 1,25 (OH)2 D3 action on pancreatic B-cells affects insulin secretion. Since insulin increases synthesis of 1,25 (OH)2 D3, the existence of a feedback loop between B-cells and kidney proximal tubule cells is suggested.