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Biomedical subjects

J A Jackson

Publications and source records attributed to J A Jackson.

At least 91 records · Page 5Linked to original sources
PubMed1991

Regulation of insulin-like growth factor-binding protein-1 synthesis and secretion by progestin and relaxin in long term cultures of human endometrial stromal cells.

The decidualized endometrium during the first trimester of pregnancy synthesizes and secretes a 32-kDa insulin-like growth factor-binding protein (termed hIGFBP-1) at high levels. IGFBP-1 is the major soluble protein product of this tissue and is principally localized to the differentiated endometrial stromal cell, the decidual cell. In the present study long term culture of stromal cells from the nonpregnant endometrium have been employed to elucidate the hormonal requirements for IGFBP-1 production. Immunoreactive IGFBP-1 was undetectable in control cultures. However, inclusion of medroxyprogesterone acetate (MPA) induced rates of 0.35 +/- 0.09 microgram/0.1 mg cell DNA.day (mean +/- SEM; n = 5) after 20-30 days. In these cultures cells exhibited morphological changes consistent with decidual cell differentiation. In all cultures removal of MPA after exposure for 10-16 days, with or without subsequent inclusion of relaxin (RLX), increased production of IGFBP-1 450- to 4600-fold to rates of 150-710 micrograms/0.1 mg cell DNA.day or 26-131 micrograms/10(6) cells.day on days 24-26. The rates tended to be higher with the inclusion of RLX and were sustained in contrast to cultures without RLX, where rates fell by day 30. Individual cultures responded differently to RLX when added from the initiation of culture, with either a response similar to MPA alone or a cyclical change in production, achieving maximal rates of 190-290 micrograms/0.1 mg cell DNA.day. Cultures in which RLX alone induced high IGFBP-1 high production were obtained from endometrium during the progesterone-dominated luteal phase. In cultures exhibiting high rates of immunoreactive IGFBP-1 production, the protein represented their major secretory protein product. This was confirmed by [35S]methionine incorporation and the presence of IGFBP-1 as the predominant protein in serum-free culture medium. The immunoreactive IGFBP-1 isolated from culture medium was found to be identical, by a number of criteria, with IGFBP-1 derived from decidual tissue. These results were consistent with a primary role of progestin exposure, whether in vivo or in vitro, in converting endometrial stromal cells to cells potentially able to exhibit the high rates of IGFBP-1 production typical of the decidualized endometrium of pregnancy.

Adult↗
PubMed1991

Role of sulfur and chloride in the dietary cation-anion balance equation for lactating dairy cattle.

Ten Holstein cows averaging 120 d in lactation were arranged in replicated 5 x 5 Latin squares with 3-wk periods to evaluate the role of sulfur (S) in the dietary cation-anion balance equation. Diets were based on corn silage in Exp. 1 and sorghum silage in Exp. 2. Supplemental S and chloride (Cl) from the double sulfate of potassium and magnesium and CaCl2 were used to manipulate dietary cation-anion balance from 0 to +30 meq when expressed as meq [(Na + K)-(Cl + S)]/100 g diet DM and from +19 to +49 meq when expressed as meq [(Na + K)-Cl]/100 g diet DM. Blood pH was not affected by cation-anion balance, although both S and Cl supplementation tended to lower pH. Blood HCO3- and urine pH decreased and plasma calcium (Ca) and urinary Ca excretion increased as anion was added to the diet. Milk fat production tended to be increased by the low S supplementation. Dietary Cl and S had similar effects on acid-base status. Therefore, we suggest that S be included with Cl in the dietary cation-anion balance equation for lactating dairy cows as follows: meq [(Na + K)-(Cl + S)]/100 g diet DM. Although response of acid-base status to S and Cl was similar, as more data comparing the acidogenicity of S vs Cl become available, it may be necessary to include a modifying coefficient for S in the equation to adjust for differences between S and Cl in acid-generating potential. This coefficient may be further dependent on the dietary source of S.

Acid-Base Equilibrium↗
PubMed1991

Endotoxin mastitis in cows milked four times daily.

As part of a project to identify the pathophysiological cause or causes of mastitic hypogalactia, midlactation cows were infused in two homolateral quarters with 10 micrograms of endotoxin while being milked four times daily to resolve better the temporal changes in mammary synthetic activity during endotoxin mastitis. Milk fat was decreased by the first milking (5 h) postinfusion and then recovered rapidly. In contrast, milk yield and the yields of protein and lactose were not significantly inhibited until the second milking, and these yields recovered slowly thereafter. The decline in milk yield by infused quarters was only 20% greater than the decline by uninfused quarters in this experiment. Mammary inflammation developed rapidly in infused quarters as milk serum albumin concentration was maximal at the first milking. Milk SCC and NAGase were also elevated at this time, and maximal levels occurred at milkings 2 to 4. Increased temperature, increased cortisol, and a mild anorexia were apparent at the first milking only. Endotoxin treatment had no effect on serum prolactin or glucose. These data suggest that the delayed hypogalactia is consequent to the mammary inflammation and systemic responses following endotoxin infusion. The results indicate that different pathophysiological events may inhibit synthesis of the different milk components.

Animals↗
PubMed1991

Influence of dietary sodium bicarbonate on the potassium metabolism of growing dairy calves.

We evaluated the influence of supplemental dietary NaHCO3 on K metabolism of young dairy calves. Thirty-two Holstein and Jersey male and female calves were blocked at 56 to 70 d after birth according to breed, sex, and age and assigned randomly to a 2 x 2 factorial arrangement of dietary treatments for 8 wk: .4% K with 0% NaHCO3, .4% K with 2% NaHCO3, .6% K with 0% NaHCO3, and .6% K with 2% NaHCO3. Feed intake was not affected by dietary KCl or NaHCO3 supplementation, but average daily gain increased with increased K and tended to be reduced by dietary NaHCO3. Plasma K was elevated by increased dietary K but generally was unaffected by NaHCO3. Urinary Ca excretion appeared to be reduced by NaHCO3; urine pH increased with supplemental NaHCO3. Results indicate 1) the K requirement of the growing calf is between .40 and .55% of diet DM, 2) because urinary K excretion was elevated by dietary NaHCO3, the K requirement may be increased when the diet is supplemented with NaHCO3, and 3) average daily gain and plasma K are sensitive indicators of dietary K in the growing calf.

Animals↗
PubMed1991

Effects of copper sources and dietary cation-anion balance on copper availability and acid-base status in dairy calves.

Twenty-four Holstein and Jersey calves (14 Holstein), 4 to 11 d of age, were assigned randomly to six treatments in a 2 x 3 factorial arrangement to examine the effects of Cu sources and dietary cation-anion balance on Cu availability and acid-base balance. Treatments were cationic basal diet (20 meq of dietary cation-anion balance on a DM basis), cationic basal diet supplemented with CuO, cationic basal diet supplemented with CuSO4, anionic basal diet (-10 meq), anionic basal diet supplemented with CuO, and anionic basal diet supplemented with CuSO4. Copper sources did not show any effect on growth of calves. The cationic diet increased calf growth compared with the anionic diet at wk 12 of the experiment. Blood pH was increased by the cationic diet in comparison with the anionic diet at wk 8 and 12. Blood pH also was increased by CuSO4 compared with CuO treatment in the early period of the treatment. Blood bicarbonate concentration was decreased by CuO and the anionic diet. Interactions between Cu sources and cation-anion balance were found for blood pH and bicarbonate concentration. Liver Cu concentration was increased by CuSO4 but not by CuO supplementation compared with control. Therefore, CuSO4 was found to be highly available, whereas CuO was a very poorly available source of Cu for young calves.

Acid-Base Equilibrium↗
PubMed1991

Reduced lactational performance following intravenous endotoxin administration to dairy cows.

Nonpregnant lactating cows were given 100 micrograms of endotoxin via the jugular vein to determine effects of intravenous endotoxin administration on mammary inflammation and lactational performance. At the first milking (11 h) posttreatment, milk yield was reduced 33%. Milk fat percentage was elevated at this time, but lactose concentration was decreased. Milk yield and composition returned to pretreatment levels within 2 d. Clinical mastitis was not induced by endotoxin treatment, but milk SCC, NAGase, serum albumin, and lactoferrin were increased by 50%. This increase was small compared with increases during mastitis and may have resulted from lower milk volume. These results support the hypothesis that part of the reduced lactational performance during endotoxin mastitis is mediated by systemic pathophysiological responses and indicate that intravenous endotoxin administration may be a useful model to study adverse effects of infectious disease on lactational performance.

Animals↗
PubMed1991

Suppression of milk production during endotoxin-induced mastitis.

Healthy, midlactation cows were given intramammary infusions of 10 micrograms of endotoxin in two homolateral quarters. Productive, inflammatory, and systemic responses were studied to investigate the pathophysiological effects of mastitis on lactational performance. Endotoxin suppressed milk yield in all quarters of treated cows. A more severe and prolonged suppression occurred in infused quarters compared with uninfused quarters. The fat percentage of milk from all quarters was increased with a greater increase occurring in infused quarters. The protein composition of milk was elevated, and the lactose concentration was depressed in infused quarters. Mammary inflammation--as measured by milk SCC, NAGase, serum albumin, and lactoferrin--was limited to infused quarters. Changes in milk NAGase closely paralleled changes in milk SCC. Daily feed intake was unaffected, and serum glucose levels did not decline following infusion. The lactose concentration of urine increased rapidly after infusion. Reduction in milk yield in all quarters, but varying changes in milk composition in infused versus uninfused quarters suggest that mastitic hypogalactia is mediated by multiple pathophysiological events and is not solely due to inflammatory damage to the mammary epithelium. Part of the reduced lactational performance may result from escape of milk components from the udder into the circulation.

Acetylglucosaminidase↗
PubMed1991

Hyperandrogenemia and virilization with simultaneous pituitary and adrenal adenomas.

We describe a postmenopausal woman who presented with virilizing hyperandrogenemia and was found to have an intrasellar tumor and a large left adrenal mass. Pathologic studies showed on undifferentiated hypophyseal adenoma with immunostaining for chromogranin only and a benign adrenocortical adenoma. In light of current understanding of the regulation of adrenal androgen secretion and adrenocortical mitogenesis, we postulate that this case may be explained by secretion of adrenal androgen-stimulating and mitogenic factors by the pituitary tumor.

Adenoma↗
PubMed1991

Disseminated histoplasmosis with bilateral adrenal enlargement: diagnosis by computed tomography-directed needle biopsy.

Disseminated histoplasmosis is a rare and potentially fatal disease caused by the dimorphic soil fungus Histoplasma capsulatum. We describe a 67-year-old man with diabetes who presented with a 6-month history of fever, weight loss, and mental deterioration; using computed tomography (CT), we found hepatosplenomegaly and bilateral adrenal masses. CT-directed adrenal biopsy showed yeast forms consistent with H capsulatum. Therapy with ketoconazole was accompanied by adrenal insufficiency (treated successfully with prednisone and fludrocortisone) and produced an excellent therapeutic response. We address the differential diagnosis of bilateral adrenal enlargement, and we discuss the clinical features, diagnosis, and treatment of disseminated histoplasmosis, a disease that includes parts of the Southwestern United States in its endemic region.

Adrenal Glands↗
PubMed1990

Osteoporosis in men: diagnosis, pathophysiology, and prevention.

Osteoporosis in men is a significant problem in clinical medicine and in society in general. Systematic consideration of the differential diagnosis of osteopenia and osteoporosis in men is appropriate in every affected patient. Dynamic bone histomorphometry has diagnostic usefulness in some patients and has provided important pathogenetic implications by study of bone remodeling and turnover. Review of the multifactorial pathophysiology of age-related bone loss in men suggests that routine maintenance of adequate calcium and vitamin D intake, exercise, early recognition and treatment of testosterone deficiency, and modification of other osteoporotic risk factors may have prophylactic value. Future basic research on the cellular biology of bone in health and disease and clinical trials assessing the effects of long-term prophylactic and treatment regimens on bone mass and fracture occurrence will expand the understanding of osteoporosis in men.

Anabolic Agents↗
PubMed1990

Fatal pulmonary thromboembolism after successful transsphenoidal hypophysectomy for Cushing's disease.

We have reported the case of a 30-year-old woman with Cushing's disease who died of massive pulmonary thromboembolism 5 weeks after successful transsphenoidal hypophysectomy. Glucocorticoid excess appears to cause a hypercoagulable state, and consideration of this thromboembolic propensity and its potential duration after cure is indicated in all patients with Cushing's syndrome during the perioperative period. At the present time, we recommend the routine perioperative use of intermittent pneumatic compression in all patients with Cushing's disease or Cushing's syndrome.

17-Hydroxycorticosteroids↗
PubMed1990

Physiological responses to intramammary or intravenous treatment with endotoxin in lactating dairy cows.

Twenty-one, middle to late lactation Holstein cows were assigned to one of three treatments in a completely randomized design to examine physiological changes associated with intramammary or intravenous administration of Escherichia coli endotoxin. Treatments were 1) Hank's balanced salt solution infusion in two contralateral quarters (control), 2) E. coli endotoxin infusion in two contralateral quarters, and 3) intravenous infusion of E. coli endotoxin. Blood was sampled and rectal temperature was measured at 30-min intervals. Endotoxin treatment was at 0900 h and sampling continued until 1700 h. Serum prolactin, cortisol, and 13,14-dihydro-15-keto-prostaglandin F2 alpha were measured. A pyretic response was observed in intravenous and intramammary treatment groups after endotoxin treatment. Response peak was higher (41.1 vs. 40.3 degrees C) and occurred later (6 vs. 4.5 h posttreatment) in the intramammary than the intravenous treatment group. Significant prolactin peaks were observed also in intravenous and intramammary endotoxin treatment groups. Prolactin peaked higher (288 vs. 112 ng/ml) and occurred sooner (1 vs. 4 h posttreatment) in the intravenous than in the intramammary treatment group. Cortisol followed a trend similar to prolactin. Cortisol peaked higher (100 vs. 82 ng/ml) and sooner (2.5 vs. 4.5 h posttreatment) in the intravenous than in the intramammary treatment group. Concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha increased rapidly posttreatment in the intravenous group only.

Abortion, Veterinary↗
PubMed1989

Marked elevation of serum dehydroepiandrosterone sulphate in Cushing's disease with macronodular adrenocortical hyperplasia.

A 30-year-old man presented with longstanding hypercortisolism and biochemical studies typical of pituitary-dependent Cushing's disease. After unsuccessful transsphenoidal surgery, plasma ACTH transiently became undetectable and adrenal computed tomography (CT) was consistent with macronodular hyperplasia. Serum dehydroepiandrosterone sulphate (DHEA-S) exceeded 10,000 ng/ml (normal 2,000-3,350 ng/ml). Despite either transient adrenal autonomy or variable adrenocortical ACTH hyperresponsiveness, urinary cortisol normalized within eight months following pituitary irradiation alone. Serum DHEA-S fell progressively but remained mildly elevated (4,000 ng/ml). Follow-up CT showed minimal residual adrenal nodularity. Given these findings and a review of the literature, we propose that chronic cosecretion of non-ACTH proopiomelanocortinderived peptides may have stimulated both hypersecretion of DHEA-S and adrenocortical macronodularity in this patient.

Adrenal Cortex Diseases↗