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M C Moore

Publications and source records attributed to M C Moore.

At least 73 records · Page 4Linked to original sources
PubMed1991

Application of organization-activation theory to alternative male reproductive strategies: a review.

Many species have extreme within-sex morphological and behavioral polymorphisms, most commonly different male phenotypes that practice different reproductive strategies. Although much is known about the role of hormones in sexual differentiation, little is known about what role hormones might play in within-sex differentiation. The relative plasticity hypothesis is derived from the classical organization-activation model of hormone action. It distinguishes between two types of polymorphic systems: a fixed system in which individual males assume one phenotype for their adult lives and a plastic system in which individual males can change phenotypes at least once. By analogy to sexual differentiation, the relative plasticity hypothesis generally predicts that organizational influences of hormones will be more important in fixed systems and activational influences of hormones will be more important in plastic systems. A review of our knowledge of the role of hormones in differentiation of within-sex polymorphisms indicates that the relative plasticity hypothesis accounts for otherwise diverse and contradictory results. This further supports the hypothesis that the organizational-activational model of hormone action derived from sexual differentiation generalizes to within-sex polymorphisms. However, studies of the effects of hormone manipulations on within-sex differentiation are rare but are desperately needed to further our understanding of this problem. Further studies of discontinuous behavioral variation characteristic of polymorphic species may further our understanding of the physiological basis of within-sex behavior variation in all species.

Animals↗
PubMed1991

Antibody to hepatitis C virus in blood donors found positive for other agents. II. Anti-HIV-1.

Stored serum samples from 24 blood donors confirmed positive for anti-HIV-1 were tested for antibody to hepatitis C virus (HCV). Those repeatedly reactive using the anti-HCV ELISA screening test were retested by the HCV recombinant immunoblot (RIBA). Risk-factors for the contraction of HIV infection that had been elicited at formal counselling sessions were evaluated in relation to HCV/HIV modes of infection. The only two donors confirmed to be anti-HCV positive both admitted to intravenous drug use.

Blood Donors↗
PubMed1991

Sources of carbon for hepatic glycogen synthesis in the conscious dog.

To identify the source(s) of carbon for the indirect pathway of hepatic glycogen synthesis, we studied nine 42-h fasted conscious dogs given a continuous intraduodenal infusion of glucose, labeled with [1-13C]glucose and [3-3H]glucose, at 8 mg.kg-1.min-1 for 240 min. Glycogen formation by the direct pathway was measured by 13C-NMR. Net hepatic balances of glucose, gluconeogenic amino acids, lactate, and glycerol were determined using the arteriovenous difference technique. During the steady-state period (the final hour of the infusion), 81% of the glucose infused was absorbed as glucose. Net gut output of lactate and alanine accounted for 5% and 3% of the glucose infused, respectively. The cumulative net hepatic uptakes were: glucose, 15.5 +/- 3.8 g; gluconeogenic amino acids, 32.2 +/- 2.2 mmol (2.9 +/- 0.2 g of glucose equivalents); and glycerol, 6.1 +/- 0.9 mmol (0.6 +/- 0.1 g of glucose equivalents). The liver produced a net of 29.2 +/- 9.6 mmol of lactate (2.6 +/- 0.8 g of glucose equivalents). Net hepatic glycogen synthesis totaled 9.3 +/- 2.5 g (1.8 +/- 0.4 g/100 g liver), with the direct pathway being responsible for 57 +/- 10%. Thus, net hepatic glucose uptake was sufficient to account for all glycogen formed by both the direct and indirect pathways. Total net hepatic uptake of gluconeogenic precursors (gluconeogenic amino acids, glycerol, and lactate) was able to account for only 20% of net glycogen synthesis by the indirect pathway. In a net sense, our data are consistent with an intrahepatic origin for most of the three-carbon precursors used for indirect glycogen synthesis.

Amino Acids↗
PubMed1991

Magnitude of negative arterial-portal glucose gradient alters net hepatic glucose balance in conscious dogs.

To examine the relationship between the magnitude of the negative arterial-portal glucose gradient and net hepatic glucose uptake, two groups of 42-h fasted, conscious dogs were infused with somatostatin, to suppress endogenous insulin and glucagon secretion, and the hormones were replaced intraportally to create hyperinsulinemia (3- to 4-fold basal) and basal glucagon levels. The hepatic glucose load to the liver was doubled and different negative arterial-portal glucose gradients were established by altering the ratio between portal and peripheral vein glucose infusions. In protocol 1 (n = 6) net hepatic glucose uptake was 42.2 +/- 6.7, 35.0 +/- 3.9, and 33.3 +/- 4.4 mumol.kg-1.min-1 at arterial-portal plasma glucose gradients of -4.1 +/- 0.9, -1.8 +/- 0.4, and -0.8 +/- 0.1 mM, respectively. In protocol 2 (n = 6) net hepatic glucose uptake was 26.1 +/- 2.8 and 12.2 +/- 1.7 mumol.kg-1.min-1 at arterial-portal plasma glucose gradients of -0.9 +/- 0.2 and -0.4 +/- 0.1 mM, respectively. No changes in the hepatic insulin or glucose loads were evident within a given protocol. Although net hepatic glucose uptake was lower in protocol 2 when compared with protocol 1 (26.1 +/- 2.8 vs. 33.3 +/- 4.4 mumol.kg-1.min-1) in the presence of a similar arterial-portal plasma glucose gradient (-0.9 vs. -0.8 mM) the difference could be attributed to the hepatic glucose load being lower in protocol 2 (i.e., hepatic fractional glucose extraction was not significantly different) primarily as a result of lower hepatic blood flow. In conclusion, in the presence of fixed hepatic glucose and insulin loads, the magnitude of the negative arterial-portal glucose gradient can modify net hepatic glucose uptake in vivo.

Animals↗
PubMed1988

Testosterone control of territorial behavior: tonic-release implants fully restore seasonal and short-term aggressive responses in free-living castrated lizards.

Two aspects of hormonal control of aggressive territorial behavior in male mountain spiny lizards Sceloporus jarrovi were studied. First, testosterone (T) implants were given to free-living castrated males during the breeding season. These implants fully restored breeding season levels of aggressive and sexual behavior. Earlier studies showed that identical implants given to free-living males during the nonbreeding season did not induce full breeding season levels of aggression. The full effectiveness of these implants during the breeding season indicates that the lack of effectiveness in the nonbreeding season was not due (1) to the need to replace additional gonadal factors or (2) to ineffectiveness of tonic delivery by the implants. It is more likely that males are less sensitive to T during the nonbreeding season or that other cues present in the breeding season environment synergize with T to induce full levels of aggression. Thus, seasonal changes in aggressive behavior in male S. jarrovi cannot be explained simply as a direct response to changes in circulating levels of T; other environmental factors play a necessary role as well. In the second phase of the study, changes in aggressive behavior of free-living T-implanted castrates were monitored following staged encounters with other males. Despite their inability to alter secretion rates of T, the T-implanted castrates still showed a rapid postencounter increase in aggressive displays that was identical to controls. Previous results showed that this dramatic postencounter increase in aggressive behavior is not accompanied by simultaneous changes in circulating T. Together, these results now allow the hypothesis that this rapid behavioral change in aggressive behavior is caused by simultaneous changes in circulating T levels to be confidently rejected.

Aggression↗
PubMed1988

Professional negligence.

In the last 5 years there has been an extraordinary increase in negligence actions against South Australian ophthalmologists. This paper considers the reasons, in particular those changes in the interpretation of the law which have made doctors vulnerable. Medical practice needs to be modified if doctors, especially surgeons, are to protect themselves, but the appropriate changes may not be in patients' best interests. The law of negligence is said to be on the brink of collapse and the Australian situation offers an interesting contrast to New Zealand's no-fault accident insurance scheme.

Attitude↗
PubMed1987

Effects of testosterone manipulations on nonbreeding season territorial aggression in free-living male lizards, Sceloporus jarrovi.

Seasonal changes in testosterone levels in male mountain spiny lizards (Sceloporus jarrovi) are correlated tightly with seasonal changes in intensity of aggressive territorial defense. Testosterone levels are lowest in the winter when males aggregate, are moderately elevated during the summer when males show low-intensity territorial defense, and are highest during the fall breeding season when males show high-intensity territorial defense. In this study, we tested the hypothesis that changes in testosterone levels cause these seasonal changes in territorial behavior. We experimentally increased and decreased circulating testosterone levels in free-living males during the summer, when they display non-breeding season territoriality. Artificially increasing testosterone levels to levels equivalent to the breeding season significantly increased some, but not all, measures of territorial aggression. Levels of aggression attained, however, were still well below those typical of breeding season males. This implies that the transition to full breeding season levels of aggression is caused only partly by an increase in testosterone levels. Castration of males during the summer had no effect on several measures of territorial aggression. Thus the activation of nonbreeding season territoriality, which precedes testicular recrudescence by several months, is relatively unaffected by testosterone levels. Taken together these results suggest that the same behavior, in this case territorial aggression, may be controlled by different mechanisms in different seasons.

Aggression↗
PubMed1987

Circulating steroid hormones during rapid aggressive responses of territorial male mountain spiny lizards, Sceloporus jarrovi.

Levels of aggression and circulating steroid hormones were monitored simultaneously in free-living male lizards following a staged territorial aggressive encounter with another male. In the first 15 min following the aggressive encounter, the frequency of territorial patroling and the frequency of agonistic and advertisement displays increased four- to fivefold in resident males. In most cases these increases persisted for at least 90 min after withdrawal of the intruder male and probably persisted for the entire day of the encounter. Blood samples collected at 15-min intervals revealed no changes in circulating levels of testosterone or corticosterone while this behavioral change was occurring. Thus, the increase in aggressive behavior that follows a male-male territorial encounter in this species does not appear to be mediated by simultaneous changes in circulating levels of these hormones. Interspecific comparisons suggest that interspecific variation in steroid hormone involvement in rapid aggressive responses may depend on the mating system and the extent of male parental care.

Aggression↗
PubMed1987

Developmental maturation of D-glucose active transport system in rat intestine.

Developmental changes in the D-glucose-active transport system were examined in jejunum of rats of different age groups (3, 5, 7, 11, 13, 17, 25 and 90 days old) using the intestinal sheet technique. Transport of D-glucose by the active system was determined by subtracting the passive component, as determined by uptake of L-3H-glucose from the total uptake. The transport rate of 0.1 and 1 mM D-glucose in 13- and 90-day-old rats was linear with time for 12 min of incubation, but decreased thereafter. Kinetic parameters of the active transport system of D-glucose were determined by examining the transport of D-glucose after 12 min of incubation as a function of concentration. Vmax of the active transport system was highest in 3-day-old rats and decreased with age reaching the adult value by day 7 after birth. Kt of the active transport system was the same in 3- 5- and 7-day-old rats, but increased progressively with age reaching the adult value by day 25 after birth. These data demonstrate that transport of D-glucose by the active system is highest during the early days of life, but decreases thereafter. It also suggests that this enhancement is most probably due to greater activity and/or number, and affinity of the transporting carriers of D-glucose.

Aging↗
PubMed1987

Intestinal glucose transport in suckling rats fed artificial milk with and without added epidermal growth factor.

Epidermal growth factor (EGF), a potent mitogen present in milk, is postulated to play an important physiologic role in the ontogeny of the intestine. An artificial rat milk, free of EGF, was developed and fed to newborn rats in an effort to evaluate the physiologic role of EGF on intestinal glucose transport. Comparisons were made between mother-fed (group 1) and artificially fed pups (group 2). Group 1 was divided into two subgroups to received either the EGF vehicle (group 1-A) or twice daily subcutaneous injections (0.1 micrograms/g body weight/day) of EGF (group 1-B). Group 2 was divided into four subgroups: formula without EGF (group 2-A), formula with 62 ng/ml of EGF (group 2-B), formula with 200 ng/ml EGF (group 2-C), and formula without EGF but added anti-EGF IgG (40 ng/ml) plus subcutaneous injections of 1 micrograms anti-EGF twice daily (group 2-D). Treatment regimens were initiated on day 3 and assays performed on day 11 of life. Glucose transport was measured using gut "sheet" preparations in all but group 2-C, which utilized brush border membrane preparations. Group 1-B showed a significant (p less than 0.03) increase in gut length (47.5 +/- 1.2 versus 42 +/- 0.9 cm) and an increase (p less than 0.03) in both Vmax (10.2 +/- 0.5 versus 7.2 +/- 0.3 nM/mg tissue) and Km (2.74 +/- 0.49 versus 1.20 +/- 0.19 mM) compared to group 1-A.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Evolution of mechanisms controlling mating behavior.

The proximate mechanisms underlying mating behavior in naturally occurring species can be fundamentally different from those in more commonly studied laboratory and domesticated forms. In naturally occurring species, reproductive strategies are much more diverse, and mechanisms controlling behavior are correspondingly diverse. A variety of hormonal, environmental, and social cues can be used to activate mating behavior. Which cues are used by particular species depends on differences in environmental and physiological constraints imposed by particular reproductive strategies. Study of this diversity of mechanisms promises to identify specific selective forces that have shaped their evolution. This evolutionary perspective leads to widely applicable generalizations and provides a useful context within which to conceptualize differences between species, populations, and individuals.

Animals↗
PubMed1986

Elevated testosterone levels during nonbreeding-season territoriality in a fall-breeding lizard, Sceloporus jarrovi.

In many vertebrates, seasonal activation of sexual and territorial behaviors coincides with seasonal gonadal activation and is caused by the increase in sex steroid hormones. Both male and female Sceloporus jarrovi are territorial, but in this species territorial behavior is seasonally activated in late April, months before seasonal gonadal maturation, which occurs in August prior to the fall mating season. Measurements of seasonal changes in circulating levels of the sex steroid hormones testosterone, progesterone, and estradiol indicated that testosterone levels in both sexes are elevated when territorial behavior is expressed, even during the period of nonbreeding-season territoriality during the summer. This suggests that a nonbreeding season behavior is activated by a sex steroid hormone in this species.

Animals↗
PubMed1986

Sex steroid hormones in natural populations of a sexual whiptail lizard Cnemidophorus inornatus, a direct evolutionary ancestor of a unisexual parthenogen.

The lizard genus Cnemidophorus consists of both sexual species and unisexual, all-female species. We characterized changes in circulating levels of gonadal sex steroid hormones in males and females in one of the sexual species, C. inornatus, to compare them to previously measured levels in a unisexual, parthenogenetic species, C. uniparens. Reproductively active male C. inornatus have high levels of dihydrotestosterone and somewhat lower levels of testosterone. These levels are highest immediately after females become sexually receptive and decrease later at the onset of testicular regression. Female C. inornatus have high levels of estradiol and low levels of progesterone during the previtellogenic and vitellogenic phases of the ovarian cycle. During the postovulatory phase, they have low levels of estradiol and high levels of progesterone. We could not detect circulating levels of androgen at any phase of the ovarian cycle. The patterns of hormone secretion in the female C. inornatus are virtually identical to those of its direct evolutionary descendant, C. uniparens. This confirms our previous conclusion that the evolution of the parthenogenetic mode of reproduction and expression of male-like pseudosexual behavior that are characteristic of the unisexual C. uniparens has not been accomplished by evolutionary modifications in the pattern of sex steroid hormone secretion. Rather it is the response to this pattern of secretion that has been modified.

Animals↗
PubMed1986

Enteral-tube feeding as adjunct therapy in malnourished patients with cystic fibrosis: a clinical study and literature review.

Eight children (aged 8 mo to 13 yr) with cystic fibrosis (CF) and growth failure were given home nocturnal nasogastric feeding of an elemental diet for 3 mo and re-evaluated 3 mo after cessation of tube feeding. An increase in energy intake (p less than 0.05) resulted in increased serum transferrin (p less than 0.005), retinol-binding protein (p less than 0.05), and clinical scores (p less than 0.05) during the study. Height and growth velocity increased by 60% (p less than 0.05), and weight growth velocity increased by 63%. Arm-muscle circumference, triceps skinfolds, serum albumin, vitamin A, vitamin E, zinc, and copper did not change significantly during tube feeding. Nocturnal feeding were safe and effective in promoting growth; however, most children with severe lung disease did not sustain the gains after cessation of tube feeding. Our findings indicate that continued nutritional support is needed to maintain the growth in malnourished children with severe lung disease.

Adolescent↗