The significance of low first trimester serum progesterone in ongoing early pregnancies presenting as pregnancies of unknown location

OBJECTIVES

The primary objective of this study was to ascertain whether there is association between low initial serum progesterone, sonographic parameters and clinical outcomes in women presenting with pregnancies of unknown location (PUL), which are found to be ongoing at their follow up scans in the first trimester.

STUDY DESIGN

This was a non-interventional retrospective cohort study of 1056 patients spanning a 14-year period, conducted in the Early Pregnancy Unit (EPU) of an inner-city teaching hospital. Patients who had an ongoing singleton first trimester pregnancy after presenting with PUL were identified and categorised as having low progesterone if it was 32 nmol/l or lower. The crown-rump length (CRL), mean gestational sac diameter (MGSD) and gestational sac volume (GSV) were measured when the embryo was first seen, and the pregnancy outcome recorded.

RESULTS

Pregnancies with low progesterone tended to have smaller gestational sacs (GS) on follow up scan (p = 0.001) and the sac was smaller than expected for a given CRL (p = 0.000). There was no ultrasound parameter that was characteristic of low progesterone. The observation of a smaller than expected MGSD for a given CRL remained even when only pregnancies with normal outcomes were analysed. Clinical outcome data were available for 854 (80.9 %) women. Overall, 81.4 % (n = 34/43) of pregnancies with low progesterone resulted in livebirth, compared to 91.7 % (n = 744/811) livebirths in pregnancies with higher levels (p = 0.0454).

CONCLUSION

Pregnancies with low progesterone tend to have a smaller GS compared to those with a higher progesterone, and the GSs are smaller than expected for a given CRL. The current study shows that women with low progesterone at the start of pregnancy remain at higher risk of miscarriage, even when the pregnancy is initially found to be viable in the first trimester. These pregnancies also tend to be associated with the sonographic finding of a smaller GS than expected for a given gestational age, regardless of eventual outcome.

Detection of breastfeeding and weaning in modern human infants with carbon and nitrogen stable isotope ratios

Carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope ratios were longitudinally measured in fingernail and hair samples from mother-infant pairs where infants were exclusively breastfed (n = 5), breast- and formula-fed (n = 2), or exclusively formula-fed (n = 1) from birth. All exclusively breastfed infants had a dual enrichment in carbon ( approximately 1 per thousand) and nitrogen ( approximately 2-3 per thousand) when compared to maternal values. In contrast, breast- and formula-fed subjects had reduced enrichments compared to exclusively breastfed subjects, and the exclusively formula-fed infant showed no increase in delta(13)C or delta(15)N values. This finding of a carbon trophic level effect in breastfeeding infants suggests that (13)C-enrichments of approximately 1 per thousand in archaeological populations are not necessarily the result of the consumption of C(4)-based weaning foods such as maize or millet. During the weaning process, the delta(13)C results for breastfed infants declined to maternal levels more rapidly than the delta(15)N results. This suggests that delta(13)C values have the potential to track the introduction of solid foods into the diet, whereas delta(15)N values monitor the length of time of breast milk consumption. These findings can be used to refine the isotopic analysis of breastfeeding and weaning patterns in past and modern populations.

Cuspal deformation and fracture resistance of teeth with dentin adhesives and composites

This study investigated the effect of polymerization shrinkage of posterior composite (Herculite) on the dimensions and fracture strength of human maxillary premolars with a phosphonate-ester DBA (Bondlite) and a second DBA comprised of 4-META with MMA/TBB (Superbond). The individual role of etched enamel and nonetched dentin bonding was also studied with high-copper amalgam used as a control. Two sizes of preparation isthmus were designated for evaluation of the effect of the polymerization contraction on weakened teeth. The following conclusions were drawn. 1. Narrow intracoronal tooth preparations were significantly stronger than wider, expansive preparations. There was no difference among the narrow isthmus preparations restored with amalgam or acid etching and composite. 2. There was a significant expansion in tooth dimension when MOD cavities were restored with amalgam. 3. Teeth with narrow isthmus preparations using composite bonded with Bondlite adhesive to etched enamel demonstrated a significant contraction compared with Superbond DBA. 4. Composite restorations using Superbond DBA in wide MOD cavities significantly improved the fracture strength of maxillary premolars. 5. Superbond DBA with composite restorations benefited the tooth in dimensional change and fracture strength. 6. There was a positive correlation between the fracture strength and tooth dimension.

Effects of maturation and priming on audiogenic seizure thresholds in mice

The rise and fall of audiogenic seizure vulnerability were followed in three lines of mice selected for brain/body weight ratio and in the heterogeneous stock from which they were derived. Over a period of 12 to 24 days, susceptibility increased and then declined. Subjects retested after a 2-day interval were more susceptible, but this priming effect declined steadily. Differences in seizure threshold varied unsystematically among the lines. No sex differences in susceptibility were found. Mice who seized were heavier on the average than nonseizers of the same age and line. It is proposed that mice with a slower development rate are less susceptible to the stimulus used to evoke seizures. If so, rapid development may tend to lower the threshold of audiogenic seizures in mice.

The use of an intermediate resin in the acid-etch procedure: retentive strength, microleakage, and failure mode analysis

Three composite resin systems, one conventional (Concise) and two microfilled (IsoPast and Silar), used with and without an intermediate resin (Concise Enamel Bond), were evaluated with and without thermal stress for in vitro retentive strength and sealing ability to acid-etched human enamel. All three materials yielded significantly different shear strength values. The use of an intermediate resin significantly improved both the shear strength and resistance to microleakage of Silar, while no differences were observed for Concise and IsoPast. The thermocycling procedure did not generally or consistently affect the results. The failure mode of the three acid-etched composite resins was studied by evaluation of the failure surface and by describing the percentage of enamel, composite, and interface which were present. The use of an intermediate resin did not significantly influence the failure mode, and the correlation between the failure mode and retentive strength, although significant was low. The study confirmed the importance of adequate wetting action of a resin on the etched enamel to ensure proper bonding.

Development of susceptibility to audiogenic seizures in DBA/2J and Rb mice: toward a systematic nomenclature of audiogenic seizure levels

A systematic nomenclature of levels of audiogenic seizures has been proposed and applied to describe the developmental changes in susceptibility in Rb-1, Rb-2 and DBA/2J mice.

The ability of foods to stain two composite resins

In this bench study, coffee and soy sauce stained composite resin restorations to a significantly greater degree than did tea or cola beverage. Generally, the greatest degree of staining with all samples occurred during the first week of the study time. The stain penetration was superficial and was estimated to be 5 mu or less.

The fracture strength of amalgam overlying base materials

Conclusions reached within the constraints of this study showed the following: 1. Fracture strength of Class II amalgam restorations decreased as the thickness of the bases increased. 2. Fracture strengths of amalgam restorations based with different thicknesses of zinc phosphate cement underline with 0.5 mm Dycal were not different from each other. 3. The strength of the restorations varied with the type of base. Zinc phosphate cement is equal to no base and superior to zinc phosphate cement plus Dycal, which is equal to Dycal. Dycal is superior to Cavitec, which is the same as Cavitec plus Dycal. 4. The base materials did not fracture. The amalgam restorations were stronger over a base with a higher modulus of elasticity, indicating that modulus of elasticity of a base is more important than compressive strength in supporting an amalgam restoration. 5. There is no advantage (no improvement in resistance to fracture of the amalgam restoration) to be gained from placing zinc phosphate cement over Dycal. 6. When a calcium hydroxide liner is not needed, the cements with a higher modulus of elasticity, such as zinc phosphate cement and reinforced ZOE, will provide for stronger amalgam restorations than Cavitec and unreinforced ZOE.

Do dental students cheat?

In a questionnaire survey, dental students from all four classes at The University of Iowa College of Dentistry were asked if they had cheated during their first and second years. They were then asked if they believed that others cheated. Cheating was admitted to by 43 percent of the respondents, but 94 percent believed it was occurring. Plagiarism was delineated as a form of cheating; while fewer students admitted to its use, the reported occurrence should be of concern in technique courses. Responses were analyzed both by year in school and grade point average. Reasons for cheating were described; and some conditions conducive to cheating were found to be under the control of the instructor.

The admission interview: the validity question

This study reports on the validity of a structured, standardized admission interview for dentistry. An entire class of 86 fourth-year dental students at The University of Iowa was studied, and the relationships between information from the interview, faculty ratings, and numerous dental and predental academic data were compared. Many correlations were found to be significant, which permitted technical description of three aspects of validity: concurrent, content, and construct. Reliability of both the instrument and the interview method were shown to affect validity.

Alcohol intake in selected lines of mice: importance of sex and genotype

Mice selected by McClearn and Kakihana for differences in ethanol-induced sleep time were used as subjects. In Experiment 1, mice from the long-sleep (LS) and short-sleep (SS) lines were offered a choice of water or solution GS consisting of 3% glucose and .16% sodium saccharin (w/v); or a choice of water or solution GS + E that contained GS solution plus 4% ethanol (w/v). In Experiment 2, mice from the first experiment were provided with a three-way choice among water, solution GS, and solution GS + E. In both experiments, SS mice (alcohol-insensitive) consumed more GS + E than LS mice (alcohol-sensitive). In addition, female mice drank considerably more GS + E solution than male mice. Thus, consumption of sweetened ethanol in both a two-way choice (water and GS + E) and a three-way choice (water, GS, and GS + E) is dependent on both genotype and sex. High genetic sensitivity to ethanol was associated with low consumption, and vice versa. Although females consumed more alcohol than males, famales of these lines have not been previously found to show lower sensitivity to acute alcohol administration.

An admissions interview to measure "good" dentist attributes

This study reports on the validity of a structured, standardized interview designed for selecting applicants for dental schools. The interview provides a score on nongrade attributes in 14 dimensions and was based on characteristics of successful dentists. A class of 86 fourth-year dental students at the University of Iowa was interviewed. Sufficient validity was found to justify the use of the interview for admissions purposes for the 1978 class.

Learning performance varies with brain weight in heterogeneous mouse lines

Three lines of unselected heterogeneous stocks of mice were tested for learning and activity in active avoidance acquisition and extinction, water-maze discrimination learning and reversal learning, operant discrimination, and passive avoidance acquisition tasks. Ambulation in the open field was also measured. Small to moderate correlations (absolute values of .17 to .42) between brain weight and learning measures were obtained for all tasks except passive avoidance. A moderate correlation between brain weight and activity was found only in the open field (r = .39). Partialing out differences in operant level and body weight and learning performance. When ambulation in the open field was partialed out, however, all correlations between brain weight and learning performance decreased. Previous research has suggested a positive relation between brain weight and learning scores across mammalian orders and species. The results reported here extend this relation to within-species variation in brain size. The results also emphasize the limitations of estimating genetic associations between brain and behavior from comparisons between small numbers of inbred strains or selected lines.

Task-dependent genetic influences on behavioral response of mice (Mus musculus) to acetaldehyde

Acetaldehyde was employed as a pharmacological agent in behavioral tests designed to assess genetic influences upon response to the drug. When used as a poison in a conditioned taste aversion study, acetaldehyde was more effective at inducing aversions in DBA/2J mice than in C57BL/6J mice. In another experiment, however, C57 mice were more affected than were DBA mice by acetaldehyde effects on loss of righting reflex. Implications for postulated genetic control of ethanol preference and neurosensitivity are discussed.

Behavioral effects of salsolinol and ethanol on mice selected for sensitivity to alcohol-induced sleep time

Two lines of mice, selected for differential sensitivity to alcohol, were tested following intracisternal administration of salsolinol, a compound putatively formed following ethanol ingestion. Both lines showed dose-dependent decreases in activity following salsolinol. When injected with ethanol, alcohol-insensitive short-sleep (SS) mice increased in activity while alcohol-sensitive long-sleep (LS) mice showed no change. Measures of coordination, taken following ethanol, demonstrated that LS mice were more incapacitated than SS mice. Salsolinol effects are discussed with reference to possible adrenergic blocking actions. Genetic differences in sensitivity to the incoordinating effects of alcohol were found.

Citric acid consumption and the human dentition

The habitual and abusive use of fruits and foods containing citric acid can cause serious dissolution effects on human tooth enamel. Because these effects can occur so easily, this paper suggests that foods and fruits containing citric acid, as well as other acids, could be definite contributors to the many other forms of idiopathic erosion so often observed by the dentist. There is a need for continued research and study in this area.

Issues in the genetics of social behavior

The genetics of social behavior presents special difficulties because the phenotype is the product of an interaction between two or more individuals. Social interactions are of two kinds: (1) cooperative, in which the probabilities of transmission of the genes of all participants are similarly affected by the outcome, and (2) agonistic, in which the probabilities for the participants are affected in opposite directions. The latter are of particular interest for evolutionary theory. Three major types of designs for measuring social behavior in genetic experiments are available: (1) homogeneous sets, (2) standard tester, and (3) tester panel representing a reference population. The advantages and limitations of each method are discussed. Important areas for future development include the relationship of genetic and experiential factors in early life to social status as an adult and the extension of the genetic analysis of social behavior to natural populations.

Pyridoxal 5'-phosphate and the regulation of ornithine decarboxylase activity and stability

There are two forms of ornithine decarboxylase with respect to pyridoxal 5'-phosphate (pyridoxal-P) affinity in exponentially-growing Swiss 3T3 mouse fibroblasts: form I (Km approximately 10 muM) accounts for 30% of the total activity, and form II (Km approximately 0.4 muM) the remainder. Each form of the enzyme is in rapid equilibrium with ornithine and pyridoxal-P; neither form recognizes the Schiff base between ornithine and pyridoxal-P as a substrate. Total pyridoxal-P concentrations indicate that both forms may normally be at least partially active in vivo. Upon stimulation of 3T3 cells by pituitary growth factors, form I becomes undetectable within 4 h. As total activity increases over 10-fold during this time and continues to increase thereafter, a possible conversion of form I to form II could account for this increase only if the Km change reflects other changes in preexisting enzyme. The rates of cofactor dissociation are apparently the same for each form and neither rate changes with the growth state. Since rapid equilibrium kinetics apply, the forms apparently differ in their rate of cofactor association. The half-lives of the two forms in vivo are the same in unstimulated cells when measured concurrently. Also, the half-life of total activity decreases markedly upon stimulation as form II becomes dominant. These and other observations are not consistent with pyridoxal-P serving a major protective function for the enzyme in vivo.

Selection for spontaneous or priming-induced audiogenic seizure susceptibility in mice

Four lines of mice were selectively bred from a heterogeneous foundation stock for audiogenic seizure prone (SP), priming prone (PP), moderately priming prone (MPP), and seizure resistant (SR). Significant changes in proportions of animals showing the desired phenotypes were found after two generations of selection, indicating involvement of genetic components in these behavioral characteristics. Although response to selection for spontaneous seizure proneness was rapid, the results do not support a view that initial seizure risk is controlled by a single recessive gene. The effects of tympanic membrane perforation on development of seizure susceptibility in these four selected lines were investigated in Experiment 2. Results indicate that the method is highly effective in inducing seizure susceptibility in the PP mice and the SR mice, but not so effective for the SP and the MPP lines. These results suggest that spontaneous and priming-induced seizure susceptibility could be due to development of hyperreactivity in centripetal auditory structures brought about by reduction of auditory input. They also suggest that the phenotypic difference between the PP and the SR lines could be due to differences in their cochlear susceptibility to stimulation damage but that a qualitatively different mechanism is involved in the MPP line.

Salsolinol differentially affects mice selected for sensitivity to alcohol

Salsolinol, a compound putatively formed following alcohol ingestion, differentially decreased the activity of lines of mice after 18 generations of genetic selection for alcohol sensitivity. Low doses of salsolinol produced significantly lower activity levels in the alcohol-sensitive long-sleep (LS) line than in the alcohol-insensitive short-sleep (SS) line. A hypnotic dose of salsolinol induced significantly longer sleeptimes in the LS line than in the SS line. Results are interpreted as supporting the hypothesis that salsolinol-like substances may mediate some of the effects of alcohol on the central nervous system.

Effect of aminooxyacetic acid on audiogenic seizure priming in C57BL/6J and SJL/J mice

An attempt was made to determine the effects of genetic and temporal factors on the inhibitory action of aminooxyacetic acid on priming for audiogenic seizures. SJL/J and C57BL/6J mice were administered 20 mug/g of AOAA subcutaneously, employing either a 2 hr or 5 hr injection-prime interval, and either a 2 day or a 9 day prime-test interval. It was found that an inhibitory effect on priming occurred only in C57BL/6J mice; this effect was significant only for the 9 day groups, and was observed when wild running was used as the criterion for seizures, but not when clonic convulsion was the criterion. Effects of AOAA are discussed in relation to theories of seizure development through disuse supersensitivity, or by chemical actions on the GABA system.