High fertility using artificial insemination during deep anoestrus after induction and synchronisation of ovulatory activity by the "male effect" in lactating goats subjected to treatment with artificial long days and progestagens

The response to the male effect was studied in two Saanen and two Alpine flocks over 5 consecutive years. Adult male and female goats were exposed to artificial long days (16h light and 8h darkness, 16L:8D) in open barns for approximately 3 months (between December 1 and April 15) followed by a natural photoperiod. Goats were treated for 11 days with fluorogestone acetate (FGA) or progesterone (CIDR) immediately before joining. Bucks carrying marking harnesses with adapted aprons joined females 49-63 days after the end of the long-day treatment (between April 30 and June 5) and were left with them for 5 days. In experiment 1 (n=142), FGA- and CIDR-treated goats were inseminated at a time based on the detection of oestrus. Two insemination groups were distinguished by the occurrence of marking over a 48-h period. Earlier (group 1) and later (group 2) buck-marked goats received one single insemination 12-24h or 0-12h after marking, respectively. Unmarked goats were inseminated along with group 2. In experiment 2 (n=344), FGA-treated goats were inseminated 52 and 70 h (52 h:70 h group) or 52 and 75 h (52 h:75 h group) after joining. In experiment 3 (n=285), FGA-treated goats were inseminated 52 h (1-AI group) or 52 and 75 h (2-AI group) after joining. In all experiments, an external control group given the "classical" insemination program was analysed. Over the 5-year period, 92% of the goats exhibited an LH surge during days 1-4 after joining and 98% of them ovulated. Eighty-seven percent of the LH surges detected in milk occurred during the 33-57 h interval after joining, indicating that ovulation took place around 45-69 h. In experiment 1, 96% of the goats were marked 22-70 h after joining. Kidding rate (KR; 78%) was similar between insemination groups and between FGA- and CIDR-treated goats (p>0.05). Most of the goats (95%) were inseminated during the interval between 15h before and up to 4h after ovulation. KR was not affected by the time between detection of marking and insemination or between insemination and ovulation (p>0.05). In experiment 2, KR (75%) was similar in both insemination groups (p>0.05). In experiment 3, KR was higher (p<0.05) in the 1-AI (71%) than the 2-AI group (57%). In all experiments, KR of the control group (68-73%) was similar to that achieved in goats induced to ovulate by the male effect. Prolificity (2.1+/-0.7) was not affected by any of the factors examined (p>0.05). In conclusion, high fertility can be achieved during anoestrus when 1 or 2 inseminations are performed over a 24h period, determined by oestrus or by the introduction of the buck, if light-treated goats receive 11-day FGA or CIDR treatment and are then induced to ovulate by the male effect.     

Differential integration of Ca2+-calmodulin signal in intact ventricular myocytes at low and high affinity Ca2+-calmodulin targets

Cardiac myocyte intracellular calcium varies beat-to-beat and calmodulin (CaM) transduces Ca2+ signals to regulate many cellular processes (e.g. via CaM targets such as CaM-dependent kinase and calcineurin). However, little is known about the dynamics of how CaM targets process the Ca2+ signals to generate appropriate biological responses in the heart. We hypothesized that the different affinities of CaM targets for the Ca2+-bound CaM (Ca2+-CaM) shape their actions through dynamic and tonic interactions in response to the repetitive Ca2+ signals in myocytes. To test our hypothesis, we used two fluorescence resonance energy transfer-based biosensors, BsCaM-45 (Kd = approximately 45 nm) and BsCaM-2 (Kd = approximately 2 nm), to monitor the real time Ca2+-CaM dynamics at low and high affinity CaM targets in paced adult ventricular myocytes. Compared with BsCaM-2, BsCaM-45 tracks the beat-to-beat Ca2+-CaM alterations more closely following the Ca2+ oscillations at each myocyte contraction. When pacing frequency is raised from 0.1 to 1.0 Hz, the higher affinity BsCaM-2 demonstrates significant elevation of diastolic Ca2+-CaM binding compared with the lower affinity BsCaM-45. Biochemically detailed computational models of Ca2+-CaM biosensors in beating cardiac myocytes revealed that the different Ca2+-CaM binding affinities of BsCaM-2 and BsCaM-45 are sufficient to predict their differing kinetics and diastolic integration. Thus, data from both experiments and computational modeling suggest that CaM targets with low versus high Ca2+-CaM affinities (like CaM-dependent kinase versus calcineurin) respond differentially to the same Ca2+ signal (phasic versus integrating), presumably tuned appropriately for their respective and distinct Ca2+ signaling pathways.     

The role of bile acids in the reduction in lipopolysaccharide uptake by cultured rat Kupffer cells

The influence of bile salts on the binding and uptake of Salmonella abortus equi lipopolysaccharide by cultured Kupffer cells was studied. In control preparations, the percentage of cell-associated lipopolysaccharide increased with time and reached a plateau after about 2 h incubation at 37 degrees C. About 1.2 micrograms lipopolysaccharide was associated with 10(6) Kupffer cells at this time interval. In the presence of 0.3, 0.6 and 1 mumol bile salts/ml the cell-associated lipopolysaccharide was respectively, about 5%, 13% and 29% lower than in control cultures. In the presence of 1 mumol bile salts/ml, the association of lipopolysaccharide to cells at 0 degrees C was about 25% lower than in controls. Preincubation of Kupffer cells with 1 mumol bile salts/ml, with or without lipopolysaccharide, did not affect cell-associated lipopolysaccharide after removal of the bile salts. The rate of secretion of radioactivity by Kupffer cells was not influenced by the presence of bile salts during the uptake or the secretion periods. Bile acids proved to inactivate lipopolysaccharide. From these observations it was concluded that low concentrations of bile salts influence the binding and uptake of lipopolysaccharide by Kupffer cells. It was, therefore, considered likely that, in patients with obstructive jaundice, the high serum bile acid level accounts for spill-over of portal lipopolysaccharide into the systemic blood.     

Variation of a test’s sensitivity and specificity with disease prevalence

Background:

Anecdotal evidence suggests that the sensitivity and specificity of a diagnostic test may vary with disease prevalence. Our objective was to investigate the associations between disease prevalence and test sensitivity and specificity using studies of diagnostic accuracy.

Methods:

We used data from 23 meta-analyses, each of which included 10–39 studies (416 total). The median prevalence per review ranged from 1% to 77%. We evaluated the effects of prevalence on sensitivity and specificity using a bivariate random-effects model for each meta-analysis, with prevalence as a covariate. We estimated the overall effect of prevalence by pooling the effects using the inverse variance method.

Results:

Within a given review, a change in prevalence from the lowest to highest value resulted in a corresponding change in sensitivity or specificity from 0 to 40 percentage points. This effect was statistically significant (p < 0.05) for either sensitivity or specificity in 8 meta-analyses (35%). Overall, specificity tended to be lower with higher disease prevalence; there was no such systematic effect for sensitivity.

Interpretation:

The sensitivity and specificity of a test often vary with disease prevalence; this effect is likely to be the result of mechanisms, such as patient spectrum, that affect prevalence, sensitivity and specificity. Because it may be difficult to identify such mechanisms, clinicians should use prevalence as a guide when selecting studies that most closely match their situation.Diagnostic accuracy plays a central role in the evaluation of medical diagnostic tests. Test accuracy may be expressed as sensitivity and specificity, as positive and negative predictive values or as positive and negative likelihood ratios.¹ Some feel that the positive and negative predictive values of a test are more clinically relevant measures than sensitivity and specificity. However, predictive values directly depend on disease prevalence and can therefore not directly be translated from one situation to another.² In contrast, a test’s sensitivity and specificity are commonly believed not to vary with disease prevalence.^3–5Stability of sensitivity and specificity is an assumption that underlies the use of Bayes theorem in clinical diagnosis. Bayes theorem can be applied in clinical practice by using the likelihood ratio of a test and the probability of the disease before the test was done (pretest probability) to estimate the probability of disease after the test was done.² Because likelihood ratios are a function of sensitivity and specificity, it is assumed that the likelihood ratios also remain the same when prevalence varies.A number of studies have shown that sensitivity and specificity may not be as stable as thought.^6–10 We previously summarized the possible mechanisms through which differences in disease prevalence may lead to changes in a test’s sensitivity and specificity.¹⁰ Prevalence affects diagnostic accuracy because of clinical variability or through artifactual differences, as described in the theoretical framework in 6^,7 Artifactual differences can result from using additional exclusion criteria, verification bias or an imperfect reference standard. For example, using an imperfect reference standard may lead to an underestimate of diagnostic accuracy, but as prevalence increases, the extent to which this happens will vary.^8,9

Table 1:

Theoretical framework of how disease prevalence and test accuracy may be related¹⁰

Love Is Blind: Indiscriminate Female Mating Responses to Male Courtship Pheromones in Newts (Salamandridae)

Internal fertilization without copulation or prolonged physical contact is a rare reproductive mode among vertebrates. In many newts (Salamandridae), the male deposits a spermatophore on the substrate in the water, which the female subsequently takes up with her cloaca. Because such an insemination requires intense coordination of both sexes, male newts have evolved a courtship display, essentially consisting of sending pheromones under water by tail-fanning towards their potential partner. Behavioral experiments until now mostly focused on an attractant function, i.e. showing that olfactory cues are able to bring both sexes together. However, since males start their display only after an initial contact phase, courtship pheromones are expected to have an alternative function. Here we developed a series of intraspecific and interspecific two-female experiments with alpine newt (Ichthyosaura alpestris) and palmate newt (Lissotriton helveticus) females, comparing behavior in male courtship water and control water. We show that male olfactory cues emitted during tail-fanning are pheromones that can induce all typical features of natural female mating behavior. Interestingly, females exposed to male pheromones of their own species show indiscriminate mating responses to conspecific and heterospecific females, indicating that visual cues are subordinate to olfactory cues during courtship.     

Involvement of previous non-participants cannot fully compensate for lower participation in a second round of FIT-screening

Introduction: The effectiveness of colorectal cancer (CRC) screening programs depends on repeated participation. Little is known on later rounds in programs that use the fecal immunochemical test (FIT), in particular whether previous participants are likely to participate again, and if non-participants persist in declining. We compared overall participation in a second round to that in a first round, and evaluated differences in participation rates based on previous response. Methods: Asymptomatic persons aged 50–74 years were invited to a second round of a FIT-based CRC screening pilot. We assessed the participation rate overall and within second round subgroups of previous participants, previous non-participants, and first time invitees. We also assessed whether participation rates were similar for males and females and for age groups. Results: In the first screening round, 2871 of 5309 invitees returned the FIT (participation rate of 57%). This was higher than in the second in which 3187 of 5925 participated (54%; p = 0.0008). Second round participation rate was 85% (2034/2385) among previous participants, 18% (325/1826) among previous non-participants and 48% (828/1714) among first time invitees (p < .0001). Overall, males and persons aged under 55 were less likely to participate. Conclusions: Participation in a second round of FIT-screening was significantly lower than in the first round, largely due to a drop in participation in first round participants, and a relatively low response among first time invitees. This loss of uptake was partially compensated by a willingness to be screened in previous non-participants.