Search PubMed⌕ Search

Biomedical subjects

F H Morriss

Publications and source records attributed to F H Morriss.

At least 19 recordsLinked to original sources
PubMed1991

Evidence for a role of volatile amines in the development of neonatal hypergastrinemia.

We investigated the presence of volatile aliphatic amines by fluorescamine and gas chromatographic-head space analysis in human breast milk and amniotic fluid to assess their role in neonatal hypergastrinemia. These volatile nitrogenous amino acid metabolites have been previously demonstrated to stimulate gastrin release in in vivo and in vitro laboratory preparations. In the present study we demonstrated that these gastrin-stimulatory volatile amines were present in significant concentrations in breast milk during the first several weeks after parturition and in amniotic fluid. The individual amines that were identified in both human milk and amniotic fluid samples were methylamine, dimethylamine, ethylamine, trimethylamine, propylamine, isobutylamine, and butylamine. This study provides indirect evidence to support the possibility that the hypergastrinemia measured in the fetus/neonate during the period immediately before and after birth may be attributable, in part, to the ingestion of fluid containing high concentrations of gastrin-stimulating amines.

Amines↗
PubMed1986

Ontogeny of ovine fetal liver and kidney plasma membrane insulin receptors and fetal growth.

This investigation was performed to define certain characteristics of insulin-receptor interaction during the last 2 months of gestation in fetal sheep liver and kidney. Twenty-one sheep carrying a total of 46 fetuses were sacrificed at various gestational ages from 94 days to term; fetal and maternal livers and kidneys were analyzed by a radioreceptor assay for insulin binding characteristics. Specific binding of insulin to partially purified ovine fetal liver and kidney plasma membranes increased as gestation approached term, at which time specific binding was two- to fourfold greater to fetal than to maternal tissues. Associated with increased specific binding were late gestational increases in affinity of insulin for receptors in both fetal liver and kidney and an earlier increase in insulin receptor concentration in fetal kidney. These observations in fetal sheep liver and kidney are similar to reported observations in other species. However, the increase in specific binding of insulin to male fetal liver membranes was exponential; in contrast, there was no apparent increase in specific binding to female fetal liver membranes during the gestational interval surveyed. Both the weights and the vertebral column lengths of these fetuses were shown by multivariate analysis to be significantly affected by the interaction between specific binding of insulin and fetal sex. However, in 30 additional sheep fetuses we observed no difference between male and female fetuses in the increase with time in liver glycogen content. The lack of sex difference in this postreceptor event is consonant with the demonstrated dissociation between liver insulin receptors and glycogen synthesis in the late fetal rat. Our observations suggest that late gestational differences between male and female sheep fetuses in insulin specific binding to liver and, possibly, to other tissues such as cartilage, muscle, and/or fat, that are coupled to postreceptor events may account for differences in fetal growth between the sexes.

Animals↗
PubMed1986

Ontogenic development of gastrointestinal motility: IV. Duodenal contractions in preterm infants.

Duodenal motility was studied by intraluminal manometry in 27 healthy infants of 26 to 42 weeks, gestational age. The frequency of contractions, the number of contractions per burst, and the intraluminal peak pressure during contractions all increased during a narrow postconceptual period, 29 to 32 weeks, regardless of length of gestation before birth. Antenatal beta-methasone administration to the mothers of 11 additional infants of 26 to 32 weeks gestational age was associated with increased duodenal contraction rate, number of contractions per burst, and intraluminal peak pressure compared with infants of similar gestational age whose mothers did not receive beta-methasone. The maturational effect of beta-methasone on duodenal motility was most pronounced in infants whose gestational age at birth was 26 to 29 weeks. Seven infants of 31 weeks' or longer gestational duration who had a CNS abnormality or insult had fasting duodenal contraction rates that were less than one half of the rate for normal infants of similar gestational age. These observations suggest that neonatal duodenal motility undergoes marked maturational changes between 29 and 32 weeks after conception and that these changes may be inducible before 29 weeks by corticosteroid administration. An intact CNS appears to be required for full expression of the maturational changes.

Betamethasone↗
PubMed1986

Relationship of human milk pH during course of lactation to concentrations of citrate and fatty acids.

Human milk pH was measured in 309 samples obtained from 52 women who had delivered at term and lactated for as long as 10 months thereafter. The mean pH decreased from 7.45 for colostrum to a nadir of 7.04 during the second week of lactation. Thereafter, the pH of milk remained between 7.0 and 7.1 until 3 months postpartum and then increased gradually to 7.4 by 10 months. The change in hydrogen ion concentration in milk was associated with corresponding changes throughout lactation in the concentration of citrate but not with the concentration of lactose. Lactose concentration increased gradually for 3 weeks; the concentration of saturated medium-chain fatty acids increased more rapidly. One interpretation of these findings is that the hydrogen ions and citrate generated by mammary secretory cell metabolism are used after the second week of lactation for de novo synthesis of fatty acids more rapidly than they are synthesized. Milk samples from ruminants were found to have concentrations of hydrogen ions and citrate that are greater than and pH that is less than the respective measurements in human milk. The significance for the recipient infant of the predictable changes in human milk pH during lactation and of the higher pH of human milk throughout lactation relative to bovine milk is unknown. However, drug excretion into milk, milk enzyme activity, milk leukocyte function, and neonatal gastrointestinal function are affected by ambient pH and may be influenced by the pH of milk.

Animals↗
PubMed1985

Decreases in ovine fetal cartilage sulfate uptake and serum sulfate during gestation.

In vitro assays for [35S]sulfate uptake by ovine fetal costal cartilage were used to assess gestational changes in cartilage metabolism. Addition of 20% normal human serum to the incubation medium increased fetal cartilage [35S]sulfate incorporation into glycosaminoglycans. Both basal and human serum-stimulated uptakes of [35S]sulfate by fetal sheep cartilage decreased from midgestation to full term. The incremental response in [35S]sulfate uptake that was stimulated by human serum decreased as gestation proceeded to full-term. Fetal serum sulfate concentration decreased logarithmically during gestation, raising the possibility that cartilage sulfate uptake might become substrate limited as full term is approached. Perfusion of seven late gestation sheep fetuses for 7 days with Na2SO4 to achieve serum sulfate concentrations similar to those observed earlier in gestation resulted in a 33% increase in mean cartilage [35S]sulfate uptake compared with that of control twin fetuses, but uptake was not increased to values that occurred spontaneously earlier in gestation. These results suggest that the decreasing rate of [35S]sulfate uptake by fetal cartilage during the last half of gestation is associated only minimally with decreasing serum sulfate levels and is most consistent with intrinsic change in resting chondrocyte metabolism during gestation.

Animals↗
PubMed1985

Effects of ovine maternal hyperglycemia on fetal regional blood flows and metabolism.

Fetal combined ventricular output (CVO) and regional distribution of blood flow were measured in 12 ewes in late gestation by the radiolabeled microsphere method. Three sets of determinations were made in sequence beginning with a control study and repeating the measurements after the ewe had received intravenous glucose at 0.35 g X min-1 for 90 min and again after the ewe had received glucose at 0.85 g X min-1 for a second 90-min period. Maternal whole blood glucose concentrations were 2.98 +/- 0.18 (means +/- SE), 10.43 +/- 0.45, and 21.59 +/- 0.90 mM during the respective study periods. Fetal CVO did not change during maternal hyperglycemia; however, it was redistributed, with a decrease in umbilical blood flow to the placenta from 43.5% of CVO to 31.9 and 30.8%, respectively. The fetal carcass, heart, intestines, kidneys, liver, and adrenals each received increased percent CVO; these increases equaled the decrease in placental blood flow. Fetuses became hypoxemic and developed a mixed acidemia during induced maternal hyperglycemia, but oxygen delivery to the heart, brain, and kidneys was unchanged. These observations indicate that maternal hyperglycemia results in previously unsuspected fetal cardiovascular responses.

Animals↗
PubMed1985

Fetal cartilage xylosyltransferase activity and skeletal growth in sheep.

The activity of UDP-D-xylose:proteoglycan core protein beta-D-xylosyltransferase (EC 2.4.2.26), the enzyme that catalyzes the initiation of the polysaccharide chain linkage to the core protein of proteoglycans, was measured in costal cartilage from 20 fetal sheep of 65-138 days gestation. Activity of the enzyme was estimated from the transfer of [14C]xylose from UDP-[14C]xylose to silk as the acceptor protein. The specific activity decreased approximately 10-fold and was found to be highly correlated with the decremental rate of growth in length of the fetal vertebral column. These observations, together with the known gestational decrease in the in vitro rate of uptake of radiolabeled sulfate by ovine fetal cartilage, a subsequent step in proteoglycan synthesis, support the hypothesis that normal fetal skeletal growth is dependent during the last one-half of gestation on the activity of xylosyltransferase in cartilage.

Animals↗
PubMed1984

Contraplacental hypogastrinemic effect of gastrin infusion in sheep.

Infusion of gastrin, G-17I, at 0.4 microgram/min into either the maternal or fetal venous circulation of six late gestation sheep was associated with increases in serum gastrin concentration in the infused circulation and reciprocal decreases in the serum gastrin concentration in the other circulation (contraplacental) that perfused the placenta. Pentagastrin infusion at 0.4 microgram/min was associated with an increase in C-terminal specific gastrin immunoreactivity in both the infused and the contraplacental circulations. These observations suggest that biologically active fragments of gastrin, but not the intact molecule, may cross the ovine placenta. An alternative explanation for our results is that gastrin infusion into either the maternal or fetal circulation which perfuses the placenta may result in the release of an inhibitor (i.e., somatostatin) into the other circulation. Of broad importance, these observations indicate that although intact polypeptide hormones may not traverse the placenta, their concentrations in maternal and fetal sera may not be as independent as previously believed. Serum gastrin half-life values in late gestation sheep fetuses, lambs, and ewes were determined to be 13.7 +/- 1.9, 16.7 +/- 2.6, and 15.2 +/- 2.8 min, respectively. These similar values indicate that the relatively high serum gastrin concentrations observed in near-term sheep fetuses are not the result of prolonged half-life in the fetus.

Animals↗
PubMed1984

Infants of diabetic mothers. Fetal and neonatal pathophysiology.

Most of the clinical problems experienced by the IDM in the immediate neonatal period are manifestations of abnormal fetal developmental physiology that occur in response to an increased flux of glucose from mother to fetus. The principal fetal responses are hyperglycemia, hyperinsulinemia, increased metabolic rate, and hypoxemia. Those fetal responses very likely lead to a redistribution of cardiac output, increased release of norepinephrine, and blunted release of glucagon. More fat is stored in adipocytes; more glycogen is stored in the liver; the heart may develop asymmetric septal hypertrophy; and lung metabolism is altered to delay the appearance of mature surfactant. At birth, the macrosomic IDM develops hypoglycemia that has a multifactorial basis (hyperinsulinemia, hypoglucagonemia, and probably diminished gluconeogenic and cortisol production rates). The IDM may experience respiratory symptoms from one of three causes: IRDS, persistent pulmonary hypertension, or congestive heart failure. Hyperbilirubinemia may occur because of increased rate of hemolysis; hypocalcemia and hypomagnesemia are likely within the first 3 days in association with a sluggish PTH response; and abnormal levels of inhibitors of fibrinolysis and platelet prostaglandin E-like substances may stimulate abnormal thrombosis.

Blood Glucose↗
PubMed1983

Comparison of the gastrointestinal growth- promoting effects of rat colostrum and mature milk in newborn rats in vivo.

The purpose of this study was to compare the effects of rat colostrum and mature milk on newborn rat gastrointestinal growth under conditions that controlled the possible confounding effects of energy intake and mode of feeding. Newborn Sprague-Dawley rat pups were tubefed equicaloric amounts of rat colostrum or mature rat milk for 40 h before they were killed. Compared to littermates that were killed immediately after birth, both groups of fed rats demonstrated increases in the weights of stomach and intestine, but there was no organ weight difference detected between colostrum-fed and mature milk-fed rat pups. However, both the concentration of DNA and the rate of synthesis of DNA in the intestines were greater in rats fed colostrum than in those at birth or those mature milk. Although the pancreas exhibited no detectable increase in weight by 41 h, the DNA concentration and total DNA content increased and RNA/DNA ratio decreased in both fed groups, also without apparent difference between rats fed colostrum and those fed mature milk. The rate of 3H-thymidine incorporation into DNA in pancreas, however, was greater in colostrum-fed pups than in mature milk-fed pups. These differences at 40 h age in intestinal and pancreatic cell replication activity, but not organ weights, can be ascribed to feeding colostrum.

Animals↗
PubMed1983

Umbilical glucose and lactate extractions during maternal hyperglycemia in sheep.

Umbilical glucose and lactate extractions were determined in previously instrumented pregnant ewes into some of which D-glucose was infused to produce graded levels of maternal hyperglycemia as great as 20 mM. While fetal arterial glucose concentration continued to increase linearly as a function of maternal arterial glucose concentration during maternal hyperglycemia, the umbilical venoarterial difference in blood glucose concentration did not, and umbilical glucose extraction approached a plateau at approximately 0.063 mmol X min-1 X kg fetus-1 at maternal glucose concentrations greater than approximately 8 mM. The observed plateau in glucose extraction is consistent with saturation at high maternal glucose concentrations of the carrier mechanism for transport of glucose from the maternal to the fetal aspects of the trophoblast. The observed value of the plateau in umbilical extraction of glucose is slightly less than the maximum extraction predicted from previously published equations for this species, but the maternal blood glucose concentration at which the observed maximum occurred agrees closely with the value predicted by those equations. Umbilical lactate extraction, 0.031 +/- 0.021 mmol X min-1 X kg fetus-1, was independent of maternal arterial blood glucose and lactate concentrations and was independent of umbilical glucose extraction.

Animals↗
PubMed1982

Effect of maternal serum insulin on umbilical extraction of glucose and lactate in fed and fasted sheep.

In 18 chronically instrumented pregnant ewes in late gestation, umbilical extractions of glucose and lactate were determined before and during the continuous infusion of ovine insulin, 0.25 mU/kg . min, into one uterine artery. Studies were conducted in both well-nourished and fasting ewes. Exogenous insulin increased the umbilical extraction of glucose without altering the umbilical extraction of lactate over the range of concentrations of maternal blood glucose encountered in the fed and fasted states. Moreover, the efflux of lactate into the uterine venous circulation in two additional ewes was not altered by the administration of insulin. These studies support the hypothesis that maternal circulating insulin binds to insulin receptors on the microvillous brush border of the placenta to effect an increase in the carrier-mediated transfer of glucose rather than cause an intraplacental decrease in the catabolism of glucose to lactate. The results suggest that, as maternal levels of blood glucose and serum insulin spontaneously rise in concert over the physiologic range, both factors may contribute to the increasing umbilical extraction of glucose. Furthermore, these observations raise the possibility that decreased binding of insulin by placental insulin receptors, which is reported to occur in placentas from diabetic women, may be accompanied by a relatively decreased umbilical uptake of glucose for a given maternal concentration of glucose, but not of lactate.

Animals↗
PubMed1982

Ontogenic studies of gastrointestinal function. II. Lower esophageal sphincter maturation in neonatal beagle puppies.

The purpose of the present study was to investigate the postnatal development of lower esophageal sphincter (LES) competence in the beagle and to determine the role of gastrin in LES functional ontogeny. Eleven beagle puppies taken from two litters were studied. All puppies were allowed to suckle during the first 3 postnatal wk. In the 4th wk, all puppies were weaned, and by the 5th wk only solid chow was offered. Intraluminal manometric pressure determinations were obtained in unanesthetized, unsedated puppies using twin-lumen, 1.7 mm OD, 1 mm ID polyvinyl catheters. A 12-15 min baseline period of intraluminal pressure was monitored, after which the puppies received successive doses of 0.03, 0.1, 1.0, and 8.0 micrograms/kg pentagastrin (PG) SC spaced at 45-min intervals. Progressive increases in LES pressure both during basal periods and during gastric contractions and in gastric fundus (GF) pressures during gastric contractions occurred during the 1st 5 weeks of life. An increase in pressure gradient between the LES and GF during gastric contraction occurred from birth through 5 wk of age. There was no response to 0.1-8.0 micrograms/kg PG until postnatal days 5-6 when the LES pressure gradient in the basal state increased in response to each of these doses. There was also no significant response by the LES to PG during gastric contraction until days 11-12 when all doses of PG evoked enhancement of LES pressure. These studies suggest that an increase in LES-GF intraluminal pressure gradient develops during the initial 2 postnatal wk in this species and that this development does not involve the hormone gastrin. Later, however, the pressure gradient may depend upon both age and gastrin since a two-way analysis of variance indicated that not only is LES pressure affected by postnatal age and by PG dose, but that there is an interaction between postnatal age and PG dose which is significant. By the fifth wk, there was an apparent dose-response effect in which the lower two doses produced increased LES pressure and the larger two doses produced decreased LES pressures.

Animals↗