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Biomedical subjects

T Pizzari

Publications and source records attributed to T Pizzari.

8 recordsLinked to original sources
PubMed2004

Effect of physiotherapy attendance on outcome after anterior cruciate ligament reconstruction: a pilot study.

BACKGROUND: In many centres patients are routinely referred for physiotherapy after anterior cruciate ligament (ACL) reconstruction. However, to date the role and amount of supervised physiotherapy required has not been clearly established. OBJECTIVE: To establish whether there was any difference in outcome between a group of patients who attended physiotherapy regularly after ACL reconstruction and a group who attended only infrequently. METHODS: Ten patients who had attended physiotherapy infrequently (mean 1.9 visits) during the first six months after ACL reconstructive surgery were matched for age, sex, graft type, and activity level and occupation before injury with 10 patients who had attended physiotherapy regularly (mean 26.5 visits). Outcome was assessed at 12 months using the Cincinnati knee rating system and the IKDC form. RESULTS: Compared with the regular physiotherapy group, patients in the minimal physiotherapy group had fewer symptoms (mean Cincinnati symptom score 46.2 v 43.4, p = 0.045). There was also a trend towards higher overall Cincinnati knee scores in the minimal physiotherapy group (mean 93.7 v 87.3, p = 0.06) but no difference in IKDC ratings. CONCLUSION: These preliminary results indicate that some patients who choose to attend physiotherapy on a very limited basis after ACL reconstruction can achieve satisfactory, if not better, outcomes than patients who attend physiotherapy regularly.

Adult↗
PubMed2004

Nontransitivity of paternity in a bird.

In many animals reproductive success is determined after insemination by the interaction of male and female processes. While sperm competition is reasonably well understood in some taxa, other processes, such as cryptic female choice and differential early embryo mortality resulting from genetic incompatibilities, are less well understood. The relative importance of these different factors contributing to reproductive success is difficult to assess. Here we control for male-mediated effects (which are often considerable and can mask more subtle processes) through the artificial insemination of known numbers of sperm in the domestic fowl to reveal that male reproductive success is nontransitive across females: the success of a particular male depends on the background against which his sperm compete for fertilization. Two potential processes could account for this effect: cryptic female choice (sperm choice) or differential early embryo mortality. Regardless of the mechanism, nontransitivity of male reproductive success has important evolutionary consequences, including the maintenance of variation in male fitness.

Analysis of Variance↗
PubMed2002

The sexually-selected sperm hypothesis: sex-biased inheritance and sexual antagonism.

When females are inseminated by more than one male (polyandry) sexual selection continues after insemination in the form of sperm competition and cryptic female choice. The sexually-selected sperm hypothesis proposes that, under the risk of sperm competition, additive variation in male traits determining fertilising efficiency will select for female propensity to be polyandrous in order to increase the probability of producing sons with superior fertilising efficiency. Two factors complicate this prediction: sex-biased transmission of male fertilising efficiency traits and sexual antagonism of sex-limited traits, fostered by sex-biased inheritance. Here, we (i) review the evidence that male traits contributing towards fertilising efficiency are heritable through sex-biased mechanisms, and (ii) explore the evolutionary implications for male and female reproductive strategies caused by both sex-biased transmission and sexual antagonism of fertilising efficiency traits. Many male fertilising efficiency traits are heritable through sex-biased mechanisms and may not necessarily increase female fitness. The predictions of the sexually-selected sperm hypothesis change dramatically under these different mechanisms of inheritance of fertilising efficiency traits, and different fitness pay-offs derived by females from the expression of such traits. Both sex-biased control of fertilising efficiency and sexual antagonism may also be important in explaining the maintenance of the genetic variance and selection potential of fertilising efficiency. We propose that a useful approach to test the sexually-selected sperm hypothesis is to combine studies which identify behavioural and physiological mechanisms explaining variation in reproductive success with artificial selection experiments to infer the underlying evolutionary patterns.

Animals↗
PubMed2002

Pre- and post-insemination episodes of sexual selection in the fowl, Gallus g. domesticus.

Although much attention has been recently directed to sexual selection arising after insemination from sexual promiscuity, little is known about the mechanisms determining reproductive success after insemination, and the way these mechanisms interact with each other and with selective mechanisms occurring before insemination: mate choice and mate acquisition. Here, we briefly review the findings of an on-going study investigating the mechanisms generating variation in reproductive success at both a pre- and a post-insemination stage in the domestic fowl. Female preference consistently favours socially dominant males before and after insemination. However, although social status mediates the number of sperm that a male inseminates into a female, dominant males may inseminate sperm of lower fertilising quality than their subordinates. We argue that mitochondrial genes may contribute to determine sperm quality, and speculate that the maternal control of mitochondrial genes may prevent sexual selection from operating on males, thus explaining both the lack of a positive correlation between social dominance and sperm quality and the maintenance of variation in male quality in the fowl.

Animals↗
PubMed2001

Indirect partner choice through manipulation of male behaviour by female fowl, Gallus gallus domesticus.

The direct and indirect consequences of female copulatory behaviour for copulation success have seldom been quantified. In feral fowl, most copulations were forced by males and copulation success was determined by two factors. First, female differential resistance and solicitation directly affected copulation success and were displayed non-randomly with respect to male social status. Second, another female copulatory behaviour, the distress call, had an indirect effect on both copulation success and the quality of copulation partners. Distress calls triggered male attention to a copulation, which increased the probability of higher-ranking males than the copulating male disrupting the copulation and inseminating the calling female. Females preferentially uttered distress calls when mounted by low-ranking males. Both copulation resistance and distress calling influenced copulation success, but only distress calling increased the probability of copulation disruption by other males. Consistent with the effect of direct selection, differential distress calling indirectly biased copulation success in favour of dominant males. Female fowl may thus ameliorate the effect of male sexual coercion by manipulating male behaviour.

Animals↗
PubMed2000

Female feral fowl eject sperm of subdominant males.

Paternity is often determined by competition between the ejaculates of different males. Males can also use particular behaviours or structures to manipulate how females use sperm. However, the ability of females to bias sperm utilization in favour of preferred males independently of male manipulation has not been demonstrated. Females are predicted to respond differentially to the sperm of different males when the reproductive interests of the sexes differ and when females are coerced into copulating. Here we show that in female feral fowl most copulations are coerced, and that females consistently bias sperm retention in favour of the preferred male phenotype. Females prefer to copulate with dominant males, but when sexually coerced by subordinate males, they manipulate the behaviour of dominant males to reduce the likelihood of insemination. If this fails, females differentially eject ejaculates according to male status in the absence of any male manipulation and preferentially retain the sperm of dominant males.

Animals↗
PubMed1999

Measurement of anterior-to-posterior translation of the glenohumeral joint using the KT-1000.

STUDY DESIGN: Single-group repeated measures. OBJECTIVES: To adapt an existing arthrometer to allow simple quantification of glenohumeral translation and to assess the arthrometer's reliability. BACKGROUND: The measurement of glenohumeral translation is an integral part of the clinical examination of the shoulder. However, no objective and reliable measure for glenohumeral translation has been reported. METHODS AND MEASURES: The KT-1000 Knee Ligament Arthrometer was used to measure the amount of anterior-to-posterior (AP) translation of the humeral head at the glenohumeral joints of 28 (16 women and 12 men) nonimpaired undergraduate university students (age 22.1 +/- 2.9 years). Two assessments were made (20 minutes apart), by a single tester, of the dominant and nondominant shoulders of each participant. RESULTS: Anterior-to-posterior translation varied from 10 to 32 mm (20.9 +/- 4.9). The test-retest reliability of the KT-1000 when measuring the nondominant shoulders was good (ICC [intraclass correlation coefficient] 0.76), and it was moderate (ICC = 0.67) when measuring the dominant shoulders. The reliability findings were influenced by large amounts of random error. Analysis by ANOVA showed that compared to women (dominant shoulder, 22.6 +/- 4.6 mm; nondominant, 23.8 +/- 4.2 mm), men showed significantly less glenohumeral translation (dominant, 17.1 +/- 3.7 mm; nondominant, 18.3 +/- 3.7 mm). CONCLUSIONS: The KT-1000 arthrometer has the potential to provide therapists with a clinically viable method of measuring glenohumeral translation.

Adult↗