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Biomedical subjects

R J Moffatt

Publications and source records attributed to R J Moffatt.

At least 37 records · Page 2Linked to original sources
PubMed1993

Lack of effects of indomethacin on estradiol feedback control of luteinizing hormone in ovariectomized ewes.

We tested the hypothesis that indomethacin, a potent inhibitor of prostaglandin synthesis, would modify estradiol's effects on tonic and surge concentrations of LH in chronically ovariectomized ewes during the anestrous season. Ewes (n = 21) were assigned randomly to one of four treatments: Vehicle+Blank (n = 5); Indomethacin+Blank (n = 6); Vehicle+Estradiol (n = 5); or Indomethacin+Estradiol (n = 5). On d=0 (hr = 0), ewes began to receive i.m. injections of either indomethacin (4 mg/kg body weight) or corn oil every 8 hr for 9 d. Blood samples were collected every 12 min for 6 hr beginning at -6 hr, +18 hr, and on day 8 (relative to initial injections of indomethacin or vehicle) to assess tonic patterns of secretion of LH. At +24 hr, ewes received blank- or estradiol-containing Silastic implants and were bled hourly for 48 hr. On day 9, ewes received 50 micrograms of GnRH i.v. and were bled hourly for 8 hr. Serum samples were assayed for LH. Indomethacin had no effect on the following parameters of LH secretion: 1) mean concentrations (ng/ml; 8.4 +/- .7 vs 8.9 +/- .8; P > .1), 2) pulse frequency/6 hr (4.5 +/- .4 vs 4.1 +/- .4; P > .1) or 3) pulse amplitude (ng/ml; 15.3 +/- 1.1 vs 14.9 +/- 1.2; P > 1). Estradiol elicited a surge of LH which began 18.9 +/- 1.7 hr after implant insertion, reached a mean peak concentration of 95.3 +/- 20.1 ng/ml, and did not differ with respect to indomethacin treatment (P > .1).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Basis of norgestomet action as a progestogen in cattle.

Norgestomet is the progestational component present in Syncro-Mate-B, which is used to synchronize estrus in cattle. In post-partum cows, luteal phases anticipated to be short following first ovulation are of normal length when cows are pretreated with norgestomet. Because Syncro-Mate-B is used experimentally as a progestogen to affect uterine function, these studies were conducted to investigate how norgestomet acts at the level of the uterus. Receptor binding assays and a sensitive estrogen bioassay in tissue culture were used to address the possibility that some effects of norgestomet might be mediated through interaction of this compound with steroid hormone receptors other than the progesterone receptor (rP). The source of receptors was high-speed cytosol, prepared from bovine uterine endometrium, which was obtained from cyclic cows. Results of single-point and complete competition analyses comparing norgestomet and progesterone indicated that norgestomet competed even more effectively than did progesterone for specific binding of [3H]progesterone to rP. Results of similar studies, which compared the abilities of norgestomet and diethylstilbestrol to compete with [3H]estradiol for binding by uterine endometrial estrogen receptors (rE), provided no evidence for norgestomet competitive binding to rE. In MCF-7 breast cancer cell bioassays, norgestomet showed weak estrogenic activity, but only at concentrations greater than 1 micromolar. Finally, norgestomet did not compete with [3H]triamcinolone acetonide when present in an 100-fold excess, and only competed with [3H]dexamethasone for binding by endometrial glucocorticoid receptors (rG) when present in the micromolar range. We conclude that, at the concentrations used in synchronizing estrus, norgestomet interacts with bovine endometrium as a progestogen and that its biological actions occur through binding of this compound to rP present in target tissues.

Animals↗
PubMed1993

Endocrine and endometrial secretory protein changes associated with uterine receptivity in sheep.

Crossbred ovariectomized ewes were treated with steroid therapies determined previously to be adequate (progesterone-primed) or inadequate (unprimed) for embryonic development in order to determine actual serum concentrations of replaced steroid hormones achieved by such treatments and to identify secreted endometrial proteins that might mediate uterine receptivity. Ewes received estradiol-17 beta on day 0, and on days 1-4, either vehicle (unprimed; N = 16) or progesterone (primed; N = 16) daily. All ewes then received "estrus estradiol" (at 8 hr-intervals), followed by "maintenance progesterone" (at 12 hr-intervals), to mimic endocrine profiles of intact ewes at and following estrus. Jugular blood samples were obtained at 4-hr intervals from 6 ewes/treatment on day 0-15 to determine serum progesterone, estradiol, and PGFM concentrations. Endometrium from two ewes/treatment on days 11-15 was cultured in vitro with [3H]leucine and radiolabeled proteins in media were analyzed electrophoretically. Results demonstrated that 1) treatments generated transient serum estradiol levels slightly greater than those reported in intact animals at estrus, 2) serum progesterone concentrations due to treatments were similar to those reported in the luteal phase of intact ewes, 3) progesterone-priming was specifically associated with a small, sustained (24-36 hr) elevation in serum PGFM, and that 4) priming was not associated with the presence or absence of major, secreted endometrial proteins that might act either as factors required for development or as embryotoxins. These results suggest that positive effects of progesterone-priming on embryo survival are not due to pharmacological doses of exogenously administered hormones, nor are due to changes in secretion of hormonally-regulated, major endometrial proteins.

Analysis of Variance↗
PubMed1993

Changes in oestrogen receptor protein, mRNA expression and localization in the endometrium of cyclic and pregnant gilts.

Conceptus secretion of oestrogen on Day 11 of gestation is involved with establishment of pregnancy in the pig. Changes in oestrogen receptor (ER) protein, mRNA and cellular localization in the endometrium were evaluated during the oestrous cycle and early pregnancy of the gilt. In nonpregnant gilts, concentration of nuclear ER in the endometrium increased from Days 0 to 12 followed by a decline on Day 15 of the oestrous cycle. In pregnant gilts, changes in endometrial nuclear ER during Days 10, 12, 15 and 18 were similar to that in cyclic pigs. Analysis of endometrial ER mRNA expression did not detect any difference between cyclic and pregnant pigs between Days 10 and 15 postoestrus. Expression of ER mRNA in endometrium of cyclic and pregnant gilts was greatest on Day 10 followed by a decline on Day 15. Endometrial ER mRNA increased on Day 18 of the oestrous cycle, but remained low during pregnancy. Immunocytochemical localization of ER in the endometria of cyclic and pregnant gilts indicated that there was intense staining for ER in stromal cells and moderate to strong staining in surface and glandular epithelial cells during oestrus (Day 0) and Day 18 of the oestrous cycle. However, stromal ER staining was absent from Days 5 to 15 of the oestrous cycle and continued to be suppressed on Day 18 of pregnancy. Immunocytochemical staining of ER in the surface and glandular epithelium was readily detectable from Days 0 to 12 of the oestrous cycle and during pregnancy. Intensity of staining for ER declined in surface epithelial cells on Day 15 in both cyclic and pregnant pigs whereas positive staining for ER in glandular epithelium was absent. Staining for ER on uterine surface epithelial cells increased during pro-estrus (Day 18) of cyclic gilts but remained similar to Day 15 in pregnant gilts. Changes in endometrial ER protein, mRNA and localization in surface epithelium are consistent with a physiological role for conceptus oestrogen secretion in uterine function and maternal recognition of pregnancy in the pig.

Animals↗
PubMed1993

Active immunization of ewes against prostaglandin F2 alpha to control ovarian function.

The hypothesis that pregnancy success could be improved in early postpartum ewes by prolonging the lifespan of the corpus luteum via active immunization against prostaglandin F2 alpha (PGF2 alpha) was tested. Further experiments in ewes immunized against PGF2 alpha investigated the effects of exogenous PGF2 alpha on the preovulatory follicle and the effects of PGF2 alpha and oestradiol benzoate on corpus luteum function. Four weeks pre-partum, 39 ewes bred to lamb during seasonal anoestrus received either 5 mg PGF2 alpha-ovalbumin conjugate (n = 20; immunized) or ovalbumin (n = 19; control) in Freund's complete adjuvant. Treatments were repeated on day 5 post-partum with reagents emulsified in Freund's incomplete adjuvant. On day 17 post-partum, ewes received 500 iu pregnant mares' serum gonadotrophin (PMSG) and 48 h later 50 micrograms gonadotrophin-releasing hormone (GnRH). Laparoscopy was performed 36 h after GnRH to assess ovarian activity and ewes with recent ovulations were inseminated into the uterus. No immunized ewes had ovulated, but ten had follicles that luteinized and secreted progesterone during the 8 weeks studied. Eighteen of 19 control ewes ovulated and 15 of 18 had increased progesterone concentration for at least 21 days. By day 70 post partum, progesterone had returned to basal values in all control ewes. In a second study, 24 immunized ewes bearing persistent corpora lutea, and for which the interval from the previous parturition was greater than 90 days, received 15 mg PGF2 alpha and 500 iu PMSG followed 48 h later by 50 micrograms GnRH. PGF2 alpha induced corpus luteum regression in all ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Concentrations of progesterone and oxytocin receptors in endometrium of postpartum cows expected to have a short or normal oestrous cycle.

Luteal lifespan is short after first postpartum ovulation in early-weaned beef cows unless cows are pretreated with a progestogen. Regression of the short-lived corpus luteum in the postpartum beef cow is due to a premature release of prostaglandin F2 alpha (PGF2 alpha) from the uterus. The premature release of PGF2 alpha may be mediated through lower concentrations of receptors for progesterone, higher concentrations of oxytocin receptors, or both, in the endometrium. Thirty-one beef cows were randomly assigned to four groups at parturition. Calves from cows assigned to the short cycle group (n = 6; control) and the short cycle/endometrium group (n = 10) were weaned at 30-32 days post partum. Cows in the normal cycle group (n = 5; control) and the normal cycle/endometrium group (n = 10) received norgestomet implants for 9 days beginning 21-23 days post partum and calves were weaned at implant insertion. Duration of oestrous cycle (x +/- SEM; P < 0.01) following first postpartum ovulation for the short cycle group was 11.5 +/- 1.9 days compared with 18.8 +/- 0.6 days for the normal cycle group. On day 5 following first postpartum ovulation, cows in the short cycle/endometrium and the normal cycle/endometrium groups were hysterectomized and endometrial tissue collected for measurement of progesterone and oxytocin receptors. Mean number of total progesterone receptors per cell was lower (P < 0.05) in the short cycle/endometrium group than in the normal cycle/endometrium group. Mean concentration of oxytocin receptors (fmol mg-1 protein) in the short cycle/endometrium group was higher (P < 0.05) than that in the normal cycle/endometrium group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Changes in progesterone and oestrogen receptor mRNA and protein and oxytocin receptors in endometrium of ewes after intrauterine injection of ovine trophoblast interferon.

This study determined whether twice-daily intrauterine injections of ovine conceptus secretory proteins (oCSP) containing type-I trophoblast interferon (25 micrograms/uterine horn) from day 11 to day 15 post-oestrus (oestrus = day 0) could alter the binding capacities of endometrial receptors for oxytocin, progesterone and oestrogen in cyclic ewes when compared with control ewes receiving serum protein (SP) injections. Injections of oCSP on days 11-15 post-oestrus decreased concentrations of oestrogen receptors (P < 0.06), oestrogen receptor mRNA (P < 0.05) and progesterone receptors (P < 0.08) in endometrium on day 16 when compared with SP-infused control ewes, which were undergoing corpus luteum regression on days 14-16. Injection of oCSP also decreased the number (P < 0.10) and affinity (P < 0.06) of oxytocin receptors. Inositol phosphate formation induced in the endometrium on day 16 by 100 nM oxytocin in vitro was highly correlated with the concentration (r > or = 0.93, P < 0.001) and Kd (r = -0.91, P < 0.01) of oxytocin receptors in SP-infused ewes, but was not as highly correlated with concentration (r < or = 0.83, P < 0.06) and Kd (r < or = 0.40, P > 0.40) of oxytocin receptors in oCSP-infused ewes. This indicates that oCSP disrupted the relationship between oxytocin receptor binding and oxytocin-induced activation of its second messenger system. These results indicate that antiluteolytic type-I trophoblast interferon may prevent oxytocin-induced luteolytic pulsatile secretion of prostaglandin F2 alpha during maternal recognition of pregnancy in sheep, by reducing the synthesis and affinity of endometrial oxytocin receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Effects of ivermectin on reproductive functions in ewes.

In response to producers' concerns about possible detrimental effects of ivermectin on ewes during the breeding season, an evaluation of its effects on endocrinological, physiological, and behavioral measures of reproductive performance was made. Twenty cycling ewes were randomly assigned on d 10 (d 0 = estrus) to receive a single recommended oral dose of 200 micrograms/kg of BW of ivermectin or a control volume of water. Twelve hours after treatment, ewes received a luteolytic injection of 5 mg of PGF2 alpha and were introduced to fertile rams. On d 10 after mating, laparoscopies were performed to assess ovulation rate, and on d 18 conceptuses were surgically recovered. Blood samples were collected during the 92-h interval beginning immediately before ivermectin and control treatments and were assayed for LH. It was determined that 1) interval from PGF2 alpha-induced luteal regression to a) onset of estrus (36.1 +/- 1.4 vs 36.3 +/- 1.4 h) and b) onset of the preovulatory surge of LH (38.2 +/- 2.6 vs 44.2 +/- 2.6 h), 2) magnitude of the surge of LH (275.6 +/- 38.9 vs 199.8 +/- 38.9 ng/mL), 3) duration of the surge of LH (9.4 +/- .4 vs 9.0 +/- .4 h), 4) area under the curve of the surge of LH (54,321 +/- 7,419 vs 38,138 +/- 7,419 arbitrary units), 5) ovulation rate (2.1 +/- .4 vs 2.0 +/- .3 ovulations/ewe), 6) pregnancy rate (8/10 vs 5/10 ewes pregnant), and 7) conceptuses per ewe (1.75 +/- .37 vs 1.60 +/- .33) did not differ (all P > .1) between ivermectin- and control-treated ewes, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Influence of carbohydrate ingestion on blood glucose and performance in runners.

Ten trained male runners performed a treadmill exercise test at 80% VO2max under two experimental conditions, carbohydrate (CHO, 7% carbohydrate) and placebo (P), to determine the effect of carbohydrate ingestion on endurance performance (treadmill run time), blood glucose concentration, respiratory exchange ratio (RER), and subjective ratings of perceived exertion (RPE). Treatment order was randomized and counterbalanced and test solutions were administered double-blind. Ingestion took place 5 min preexercise (250 ml) and at 15-min intervals during exercise (125 ml). Performance was enhanced by 29.4% (p < 0.05) during CHO (115 +/- 25 min) compared to P (92 +/- 27 min). Blood glucose concentration was significantly greater during CHO (5.6 +/- 0.9 mM) relative to P (5.0 +/- 0.7 mM). There was a significant increase in mean RER following CHO ingestion (.94 +/- .01) compared to P (.90 +/- .01). Average RPE was significantly less during CHO (14.5 +/- 2.3) relative to P (15.4 +/- 2.4). These data suggest that time to exhaustion of high-intensity treadmill exercise is delayed as a result of carbohydrate ingestion and that this effect is mediated by favorable alterations in blood glucose concentration and substrate utilization.

Blood Glucose↗
PubMed1992

Subclinical mastitis in ewes and its effect on lamb performance.

Two studies were conducted to 1) assess the effectiveness of the California mastitis test (CMT) relative to direct microscopic somatic cell count (DMSCC) and(or) somatic cell count (SCC) procedures for detecting subclinical mastitis in ewes, 2) determine the incidence of subclinical mastitis based on repeated or single sample measures and organisms associated with the inflammation, and 3) assess the relationship between milk quality measures and lamb performance. The relationship between DMSCC and SCC scores was significant (P less than .01); 90% of the variation in DMSCC scores was accounted for by SCC scores. In contrast, CMT scores accounted for only 26% of the variation in DMSCC and 30 to 34% of the variation in SCC scores. Incidence of inflammation varied from 17 to 50% of ewes tested, depending on the study and the method of assessment. Staphylococcus species were cultured from 14/41 samples tested, with cultures of Streptococcus species (3/41) and Micrococcus species (1/41) also present. The effect of subclinical mastitis in ewes on lamb performance was minimal when assessed by regressing lamb weights on subclinical mastitis and milk quality scores. In conclusion, growth performance of lambs in a management system where they had access to supplemental feed was not influenced by the quality of milk produced by ewes, or by the degree of subclinical mastitic inflammation present when they suckled.

Animals↗
PubMed1991

Cessation from cigarette smoking: changes in body weight, body composition, resting metabolism, and energy consumption.

This study examined the effect of cessation from smoking on body weight, body fat, resting metabolic rate (RMR), and caloric consumption. Twenty-six women aged 25 to 45 years (mean, 37.2 +/- 4.7) who smoked 20 or more cigarettes per day for the past 5 years served as volunteers. Twelve subjects abstained from smoking for a period of 60 days (EXSMOKERS). Six stopped smoking for 30 days, then resumed the habit for an additional 30 days (RESMOKERS). Eight subjects continued to smoke for the entire 60 days (SMOKERS). Additionally, 10 women who had never smoked served as nonsmoking controls (NONSMOKERS). Body weight was recorded weekly and body fat was calculated from body density as determined by hydrostatic weighing. RMR was assessed by open-circuit spirometry. Caloric intake was obtained from 3-day food records using a computerized nutrient data base. Group means for body weight, body fat, RMR, and caloric intake were compared using a repeated measures ANOVA with a Scheffe post hoc at day 0 (baseline), day 30, and day 60 of cessation from smoking. NONSMOKERS weighed significantly (P less than .05) more, but were no fatter than all smoker groups at day 0. Body weight significantly increased by 1.8 kg (EXSMOKERS) and 2.1 kg (RESMOKERS) at day 30 of cessation. By day 60 EXSMOKERS' body weight had increased an additional 1.8 kg to 61.6 +/- 6.4 kg, while return to smoking (RESMOKERS) resulted in a 3.1 kg loss of body weight to 57.9 +/- 7.9 kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Acute effects of resistance exercise on parameters of lipoprotein metabolism.

Ten healthy, trained males (25.4 +/- 3.1 yr) were studied before and after 90 min of resistance exercise to determine the acute effects of high volume (HV) and low volume (LV) sessions on alterations in lipid and lipoprotein concentrations as well as the activity of lecithin: cholesterol acyltransferase (LCAT). The HV session involved the use of 8-12 repetition maximum (RM) loads performed to exhaustion with 60 s rest intervals between sets, while the LV session involved the use of 1-5RM loads with 3 min rest intervals between sets. Fasting blood samples were drawn from an antecubital vein immediately before and after exercise as well as 24, 48, and 72 h post-exercise. Following adjustment for changes in plasma volume, significant changes were only found following the HV session. These included increases in HDL-C (11%) and HDL3-C (12%) 24 h post-exercise. Modifications in HDL-C were significantly different from both the LV and control sessions. In contrast, triglycerides and LCAT were significantly depressed 24 h post-exercise following the HV session when compared with immediate post-exercise values. There were no significant changes in either total cholesterol or HDL2-C at any time. The results of this study suggest that the potential of resistance exercise to affect acute modifications in the lipoprotein profile resides in the volume of exercise performed.

Adult↗
PubMed1990

Embryonic steroids and the establishment of pregnancy in pigs.

In the pig, establishment of pregnancy begins about 11-12 days after the start of oestrus. The ability of pig conceptuses to synthesize and release oestrogens during this period, as well as the ability of exogenous oestrogens to induce pseudo-pregnancy when administered from Day 11-15 of the oestrous cycle, provide evidence for an involvement of oestrogen in the maternal recognition of pregnancy in the sow. Oestrogen derived from the conceptus or from administration to cyclic gilts stimulates uterine secretion of calcium and specific polypeptides on Day 11-12. The specific roles for the uterine secretory response to oestrogen in the maintenance of pregnancy are unknown. However, it has been proposed that oestrogen prevents luteolysis in the sow through reorientation of endometrial prostaglandin release, i.e. into the uterine lumen rather than into the uterine vasculature. Oestrogen may interact with prolactin and/or conceptus secretory proteins to shift the direction of prostaglandin movement. Although conceptus oestrogen synthesis triggers a number of uterine secretory events on Day 11, a second sustained phase of oestrogen stimulation from Day 14 to 18 appears to be necessary for luteal maintenance beyond Day 25. Pig conceptuses synthesize and release large amounts of oestrogens between Days 14 and 18 of pregnancy. Conceptus oestrogens are clearly involved with the establishment of pregnancy. However, the conceptus also secretes a number of biologically active substances such as catechol oestrogens, prostaglandins and polypeptides which could interact with oestrogen to prevent luteolysis. The roles of these factors in control of vascular permeability, blood flow, placental attachment and immunological protection certainly indicate that, in addition to oestrogens, other factors are involved in the establishment of pregnancy in pigs.

Animals↗
PubMed1989

Physiological effects of walking and running with hand-held weights.

To study the effect of walking and running with hand-held weights on oxygen uptake (VO2), heart rate (HR), respiratory exchange ratio (RER), and ratings of perceived exertion (RPE), ten males (means age = 26.1 +/- 5.5 yrs) completed 4 submaximal treadmill tests during each of four test sessions, one week apart. Protocols consisted of carrying one of four randomly assigned hand-held weight configurations (0, 0.45, 1.36, 2.27 kg per hand) while walking or running for 5-min at each of four speeds (4.8, 6.4, 8.0, 9.6 km/hr) at 4% grade. Open circuit spirometry methods were utilized for the determination of steady rate VO2 and RER. Heart rate was recorded electrocardiographically throughout the test. Subjects maintained normal arm swing patterns. Carrying hand-held weights did not significantly increase VO2 (ml.kg-1.min-1) at either walking speed (4.8, 6.4 km/hr). At the two running speeds (8.0, 9.6 km/hr) VO2 was significantly greater when the heaviest load (2.27 kg) was compared to the three lighter loads (0, 0.45, 1.36 kg). The results of this study suggest that walking with hand-held weights of 2.27 kg or less while maintaining a normal arm swing is an insufficient stimulus for significantly increasing VO2 or HR. Running with hand-held weights can increase VO2, with 2.27 kg appearing to be the load threshold.

Adult↗
PubMed1988

Effects of cessation of smoking on serum lipids and high density lipoprotein-cholesterol.

This study examined the effect of cessation of smoking on serum lipid and lipoprotein levels. Twenty-six females who smoked a minimum of 20 cigarettes per day for the past 5 years served as volunteers. Twelve subjects abstained from smoking for a period of 60 days (ex-smokers). Six stopped smoking for 30 days then resumed smoking for an additional 30 days (re-smokers). Eight subjects continued to smoke for the entire 60 days (smokers). Additionally, 10 females who had never smoked served as non-smoking controls (non-smokers). Pre-cessation HDL-C levels for all smoker groups were 15-20% (P less than 0.05) below those of non-smokers. By day 30 of cessation HDL-C levels of ex-smokers and re-smokers significantly increased by 5.7 and 10.5 mg/dl, respectively, and were significantly higher than those of smokers. At day 60, HDL-C of ex-smokers increased another 6.8 mg/dl to 63.9 mg/dl while levels of re-smokers returned to pre-cessation levels (50.7 mg/dl). The findings of this study suggest that low levels of HDL-C associated with smoking in females do not appear to be cumulative and can be reversed in as little as 30 days.

Adult↗
PubMed1988

Sweat iron loss of male and female runners during exercise.

Male (n = 9) and female (n = 8) collegiate cross-country runners were studied during a training session to determine the amount of iron lost in the sweat. Sweat samples were collected from the arm using polyethylene bags. Total sweat loss was determined by weighing subjects before and after the runs. Average time of sweat collection was 42 min for males and 39 min for females. Sweat rate for the males (717.5 +/- 145.9 g/m2/h) was significantly greater than for the females (460.1 +/- 142.9 g/m2/h); however, the sweat rate per km was not significantly different. Females had a significantly greater sweat iron concentration (0.417 +/- 0.024 mg/l) than males (0.179 +/- 0.011 mg/l). Rate of sweat iron loss was not significantly different for females (0.276 +/- 0.140 mg/h) and males (0.21 +/- 0.13 mg/h). Sweat iron concentration was inversely related with sweat rate (r = -0.64). Our data suggest that although males lose more total sweat than females, the higher sweat iron concentration of females leads to similar rates of iron loss. For female runners, sweat iron loss coupled with a low dietary iron intake may result in a negative iron balance.

Adolescent↗
PubMed1987

Biochemical characterization and biosynthesis of the uterine milk proteins of the pregnant sheep uterus.

The uterine milk proteins (UTM-proteins), a pair of basic glycoproteins with similar isoelectric points and molecular weights (57,000 and 55,000), are secreted by the endometrium of the pregnant ewe. Peptide mapping of the two species of UTM-proteins demonstrated them to be structurally related. Furthermore, pulse-chase and continuous-labeling experiments indicated that both are produced from a common precursor of lower molecular weight. Purified UTM-proteins were found to be rich in basic amino acids, low in tyrosine, and apparently lacking in tryptophan. The proteins were about 5.6-5.7% carbohydrate by weight and bound the lectin, concanavalin A. UTM-proteins synthesized in vitro incorporated D-[3H]glucosamine. Analysis of [3H]glucosamine-labeled glycopeptides of Pronase-digested UTM-proteins by gel filtration indicated that most radioactivity is associated with one size class of oligosaccharide. UTM-proteins secreted by the endometrium in the presence of tunicamycin, an N-glycosylation inhibitor, were of lower molecular weight than those from control endometria, indicating that sugar chains are attached to the protein core via N-linkages to asparagine. UTM-proteins synthesized in culture incorporated [32P]orthophosphate, and tunicamycin inhibited this incorporation. Analysis of hydrolyzed UTM-proteins by paper chromatography indicated that much of the 32P was associated with mannose 6-phosphate. Because this moiety is the so-called lysosomal recognition marker and is present on uteroferrin, the acid phosphatase of porcine uterine secretions, we tested UTM-proteins for several enzymatic activities characteristic of lysosomes, but none was found. In conclusion, the UTM-proteins are related glycoproteins that, like porcine uteroferrin, contain mannose 6-phosphate, a result which suggests that secretion of glycoproteins with phosphorylated oligosaccharide chains may be a common feature of the progestational uterus.

Amino Acid Sequence↗