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Biomedical subjects

J A Lemons

Publications and source records attributed to J A Lemons.

118 records · Page 7Linked to original sources
PubMed1976

Mammary blood flow and endocrine changes during parturition in the ewe.

The temporal relationship between changes in mammary blood flow (MBF) and changes in the concentration of plasma prolactin, progesterone, estradiol-17beta, and cortisol, was examined in chronic sheep preparations undergoing spontaneous labor (Group I) or labor induced by an infusion of dexamethasone (1 mg/24 h) to the fetus (Group II). In Group I, an increase in prolactin (45 to 489 ng/ml), a decrease in progesterone (15 to 4 ng/ml), and an increase in MBF (97 to 365 ml/min) occurred at about the same time, whereas increases in estradiol-17beta (80 to 211 pg/ml) and cortisol (9 to 39 ng/ml) followed the change in MBF. A similar pattern of changes in MBF and hormonal concentrations occurred over a shorter period when premature labor was induced in the animals in Group II. These findings suggest that changes in plasma prolactin and progesterone concentrations play an important role in the regulation of MBF at the time of parturition.

Animals↗
PubMed1975

Relationship of mammary blood flow to parturition in the ewe.

Mammary blood flow was measured in conscious, unanesthetized ewes with electromagnetic flow probes prior to spontaneous labor (four animals) or during the induction of premature labor (four animals) by administration of dexamethasone, 1 mg/24 h, to the fetus. In all animals an increase in mammary blood flow was noted prior to delivery. Dexamethasone administered to one mother in the same dose did not induce labor or produce an increase in mammary blood flow. These results suggest that the fetal adrenal gland influences maternal mammary blood flow prior to delivery.

Animals↗
PubMed1975

Sequential patterns of circulating luteinizing hormone and follicle-stimulating hormone in female sheep from early postnatal life through the first estrous cycles.

Patterns of circulating LH and FSH were examined during several 6-h periods in developing female sheep from 3 weeks of age through the first estrous cycles (30--40 weeks of age) and early pregnancy. With the onset of pulsatile LH secretion, beginning 11 weeks after birth, circulating LH increased to levels 2- to 5-fold greater than those observed in the adult. Thereafter, high and variable levels of circulating LH persisted through young adulthood when ovarian cyclicity including ovulation became manifest. Although prior to the initial estrus changes in frequency of LH release (number of LH discharges/6-h period) appeared to occur randomly from week to week, after first estrus, changes in frequency became predictable. During the early (day 1) and late (day 15) luteal phases of the first estrous cycles, when circulating progesterone was low (less than 0.6 ng/ml), the frequency of LH release was increased (5--7 discharges/6 h) while during the mid-luteal phase (day 7--12), when circulating progesterone was high (2--4 ng/ml), the frequency was diminished (0--2 discharges/6 h). Massive and sustained discharges of LH which resembled preovulatory surges were observed only shortly before first estrus. In contrast to the pulsatile release pattern of LH, concentrations of circulating FSH within the 6-h periods were relatively constant and within the range found in the adult. These findings lead to the following conclusions: a) changes in negative feedback control are not directly responsible for the onset of ovarian cyclicity in the sheep as indicated by the lack of differences in mean concentrations of circulating LH and FSH before and after first ovulation; b) the onset of the surge mode of gonadotropin secretion occurs only shortly before first ovulation; and c) progesterone may play an inhibitory role in regulating tonic LH secretion during the first estrous cycles.

Age Factors↗
PubMedDate not supplied

Bacterial/fungal growth in a combined parenteral nutrition solution.

Appropriately mixed, compatible solutions of glucose, amino acids and lipid have recently become available for clinical use. While a single hyperalimentation solution has several advantages over the conventional two-bottle technique, its effect on infusion-related septicemia is unknown. An in vitro, mock infusion system identical to that used in our new-born intensive care unit was set up to assess the relative growth rates of three microorganisms in several parenteral nutrition mixtures. Growth of Staphylococcus epidermidis, Escherichia coli and Candida albicans was measured in seven different alimentation solutions, including two combined solutions. Generally, microbial growth was the same or decreased in combined solutions as compared to fat alone although considerably greater than that observed in nonlipid containing solutions. In addition, the ability of these organisms to pass in-line terminal filters of pore size 0.22 and 1.2 microns was assessed.

Candida albicans↗
PubMedDate not supplied

Patent ductus arteriosus in neonates.

Patency of the ductus arteriosus is one of the more common problems of the neonate. Although the ductus arteriosus usually closes within the first days of life, persistent patency can complicate the clinical status of a newborn. The ductus arteriosus also may play a role in the pathophysiology of persistent pulmonary hypertension of the newborn and in some forms of congenital heart disease. Diagnosis of patent ductus arteriosus can be suspected clinically but should be verified by echocardiography before treatment. Accurate diagnosis, early intervention and proper treatment are necessary to decrease the immediate risks and minimize the potential for long-term complications.

Contraindications↗