Radiographic analysis of vocal tract length and its relation to overall body size in two canid species.

Body size is an important determinant of resource and mate competition in many species. Competition is often mediated by conspicuous vocal displays, which may help to intimidate rivals and attract mates by providing honest cues to signaler size. Fitch proposed that vocal tract resonances (or formants) should provide particularly good, or honest, acoustic cues to signaler size because they are determined by the length of the vocal tract, which in turn, is hypothesized to scale reliably with overall body size. There is some empirical support for this hypothesis, but to date, many of the effects have been either mixed for males compared with females, weaker than expected in one or the other sex, or complicated by sampling issues. In this paper, we undertake a direct test of Fitch's hypothesis in two canid species using large samples that control for age- and sex-related variation. The samples involved radiographic images of 120 Portuguese water dogs Canis lupus familiaris and 121 Russian silver foxes Vulpes vulpes. Direct measurements were made of vocal tract length from X-ray images and compared against independent measures of body size. In adults of both species, and within both sexes, overall vocal tract length was strongly and significantly correlated with body size. Effects were strongest for the oral component of the vocal tract. By contrast, the length of the pharyngeal component was not as consistently related to body size. These outcomes are some of the clearest evidence to date in support of Fitch's hypothesis. At the same time, they highlight the potential for elements of both honest and deceptive body signaling to occur simultaneously via differential acoustic cues provided by the oral versus pharyngeal components of the vocal tract.

Habitual cave use and thermoregulation in chacma baboons (Papio hamadryas ursinus).

The willingness to utilise caves as shelters is held to have been important to early humans but dependent on pyrotechnology. Despite anecdotal evidence that non-human primates will also exploit caves there has as yet been no detailed account of such exploitation or of the reasons underlying it. Here we provide the first such data, on the frequency and patterning of the use of an underground cave system by baboons (Papio hamadryas)-and show that usage is determined, at least in part, by above-ground temperatures.

Proximate factors mediating "contact" calls in adult female baboons (Papio cynocephalus ursinus) and their infants.

"Contact" calls are widespread in social mammals and birds, but the proximate factors that motivate call production and mediate their contact function remain poorly specified. Field study of chacma baboons (Papio cynocephalus ursinus) revealed that contact barks in adult females were motivated by separation both from the group at large and from their dependent infants. A variety of social and ecological factors affect the probability of separation from either one or both. Results of simultaneous observations and a playback experiment indicate that the contact function of calling between mothers and infants was mediated by occasional maternal retrieval rather than coordinated call exchange. Mothers recognized the contact barks of their own infants and often were strongly motivated to locate them. However, mothers did not produce contact barks in reply unless they themselves were at risk of becoming separated from the group.

The meaning and function of grunt variants in baboons.

Wild baboons Papio cynocephalus ursinus, give tonal, harmonically rich vocalizations, termed grunts, in at least two distinct, behavioural contexts: when about to embark on a move across an open area ('move' grunts); and when approaching mothers and attempting to inspect or handle their young infants ('infant' grunts). Grunts in these two contexts elicit different responses from receivers and appear to be acoustically distinct (Owren et al. 1997 Journal of the Acoustical Society of America101 2951-2963). Differences in responses to grunts in the two contexts may, then, be due to acoustic differences, reflecting at least a rudimentary capacity for referential signalling. Alternatively, responses may differ simply due to differences in the contexts in which the grunts are being produced. We conducted playback experiments to test between these hypotheses. Experiments were designed to control systematically the effects of both context and acoustic features so as to evaluate the role of each in determining responses to grunts. In playback trials, subjects differentiated between putative move and infant grunts. Their responses based only on the acoustic features of grunts were functionally distinct and mirrored their behaviour to naturally occurring move and infant grunts. However, subjects' responses were in some cases also affected by the context in which grunts were presented, and by an interaction between the context and the acoustic features of the grunts. Furthermore, responses to grunts were affected by the relative rank difference between the caller and the subject. These results indicate that baboon grunts can function in rudimentary referential fashion, but that the context in which grunts are produced and the social identity of callers can also affect recipients' responses. Copyright 1999 The Association for the Study of Animal Behaviour.

The role of vocal tract filtering in identity cueing in rhesus monkey (Macaca mulatta) vocalizations.

The importance of individual identity and kinship has been demonstrated in the social behavior of many nonhuman primates, with some evidence suggesting that individually distinctive acoustic features are present in their vocalizations as well. In order to systematically test whether acoustic cues to identity are reliably present across the vocal repertoire of rhesus monkeys (Macaca mulatta), we examined coos, grunts, and noisy screams produced by adult females of two free-ranging groups. First, acoustic analyses were used to characterize spectral patterning, the fundamental frequency, and temporal characteristics of these three distinct call types. Vocalizations were then classified by caller identity, based on discriminant function analyses. Results showed that coos (rich, harmonically structured sounds) were markedly more distinctive by caller than were either grunts or noisy screams, and that spectral-patterning measures related to vocal tract filtering effects were the most reliable markers of individual identity. Grunts (pulsed, noisy calls) were classified at lower, but above-chance rates and spectral patterning cues were again critical in this sorting. Noisy screams (continuous, broadband noise bursts that could include a high-frequency, periodic component) could not be reliably sorted by caller. Playback experiments conducted with the screams showed no response differences when listening animals heard vocalizations produced by kin or nonkin individuals. This result was strikingly different from the corresponding outcome of a previous test with coo calls, but consistent with the acoustic analysis. Implications of these findings for vocal production mechanisms in nonhuman primates and previous studies of rhesus monkey vocalizations are discussed.

Evolution of social organization: a reappraisal for primates by using phylogenetic methods.

For many animal taxa, the extent to which phylogeny can account for the form of species' social systems has seldom been investigated formally. A quantitative phylogenetic analysis of social systems in the order Primates reveals that social organization may be strongly conserved in some lineages, even in the face of considerable ecological variability. This result has important implications for efforts to understand the evolution of animal societies and for attempts to reconstruct the social organization of early humans.

Coronary angioplasty performed with gradual and prolonged inflation using a perfusion balloon catheter: procedural success and restenosis rate.

The results of routine coronary angioplasty using gradual and prolonged balloon inflation with a perfusion balloon catheter were evaluated. One hundred forty patients were treated with inflation of the balloon to 6 atm over 3 minutes, with a median inflation time of 15 minutes. The procedural success rate (residual stenosis less than or equal to 50%) was 99%. In-hospital major complications occurred in five patients (3.6%), with one patient experiencing a periprocedural infarction, three patients requiring bypass surgery for abrupt closure, and one patient dying after elective bypass surgery following previous successful angioplasty of a culprit lesion. The restenosis rate in the 117 patients with angiographic follow-up (87% of those eligible) was 42%. Thus gradual and prolonged inflation using a perfusion balloon catheter resulted in a high procedural success rate and a restenosis rate similar to that reported in large studies of patients treated with standard angioplasty. These results warrant further study using a prospective randomized trial design.

Detection of restenosis after elective percutaneous transluminal coronary angioplasty using the exercise treadmill test.

To determine the value of a 6-month exercise treadmill test for detecting restenosis after elective percutaneous transluminal coronary angioplasty (PTCA), 303 consecutive patients with successful PTCA and without a recent myocardial infarction were studied. Among the 228 patients without interval cardiac events, early repeat revascularization or contraindications to treadmill testing, 209 (92%) underwent follow-up angiography, and 200 also had a follow-up treadmill test and formed the study population. Restenosis (greater than or equal to 75% luminal diameter stenosis) occurred in 50 patients (25%). Five variables were individually associated with a higher risk of restenosis: recurrent angina (p = 0.0002), exercise-induced angina (p = 0.0001), a positive treadmill test (p = 0.008), more exercise ST deviation (p = 0.04) and a lower maximum exercise heart rate (p = 0.05). However, only exercise-induced angina (p = 0.002), recurrent angina (p = 0.01) and a positive treadmill test (p = 0.04) were independent predictors of restenosis. Using these 3 variables, patient subsets could be identified with restenosis rates ranging from 11 to 83%. The exercise treadmill test added independent information to symptom status about the risk of restenosis after elective PTCA. Nevertheless, 20% of patients with restenosis had neither recurrent angina nor exercise-induced ischemia at follow-up. For more accurate detection of restenosis, the exercise treadmill test must be supplemented by a more definitive test.

Exercise treadmill testing is a poor predictor of anatomic restenosis after angioplasty for acute myocardial infarction.

This study evaluated whether an exercise treadmill test could predict restenosis in 289 patients 6 months after a successful emergency angioplasty of the infarct-related artery for acute myocardial infarction. After excluding those with interim interventions (64), medical events (36), or medical contraindications to follow-up testing (25), both a treadmill test and a cardiac catheterization were completed in 144 patients, 88% of those eligible for this assessment. Four patients with left bundle branch block or pacemaker rhythm at the time of treadmill testing were also excluded from analysis. Of six follow-up clinical and treadmill variables examined by multivariable logistic regression analysis, only exercise ST deviation was independently correlated with restenosis at follow-up (chi 2 = 5, p = 0.02). The clinical diagnosis of angina at follow-up, although marginally related to restenosis when considered by itself (p = 0.04), did not add significant information once ST deviation was known. The sensitivity of ST deviation of 0.10 mV or greater for detecting restenosis was only 24% (13 of 55 patients), and the specificity was 88% (75 of 85 patients). The sensitivity of exercise-induced ST deviation for detection of restenosis was not affected by extent or severity of wall motion abnormalities at follow-up, by the timing of thrombolytic therapy or of angioplasty, or by the presence of collateral blood flow at the time of acute angiography. A second multivariable analysis evaluating the association of the same variables with number of vessels with significant coronary disease at the 6-month catheterization found an association with both exercise ST deviation (p = 0.003) and exercise duration (p = 0.04). Angina symptoms and exercise treadmill test results in this population had limited value for predicting anatomic restenosis 6 months after emergency angioplasty for acute myocardial infarction.

Repeat percutaneous transluminal coronary angioplasty and predictors of recurrent restenosis.

One hundred seventeen consecutive patients undergoing repeat percutaneous transluminal coronary angioplasty (PTCA) were studied to assess procedural success and recurrent restenosis rates. Clinical, anatomic and procedural variables were examined as predictors of recurrent restenosis using stepwise logistic regression analysis. Primary success was achieved in 114 patients (97.5%). One patient (0.8%) died after acute occlusion. No other in-hospital complications were encountered. After a mean follow-up interval of 218 +/- 160 days, 72 of 114 successfully dilated patients (63%) remained angina free. There were no late deaths. Three patients (2.6%) experienced a late myocardial infarction. Follow-up arteriography was performed in 100 patients (88%), of whom 32% had recurrent restenosis (greater than 50% luminal diameter narrowing). On univariate analysis, the presence of 3 clinical variables at repeat PTCA was associated with significantly higher recurrent restenosis rates compared with their absence, that is, unstable angina (48 vs 20%, p = 0.003), diabetes (61 vs 26%, p = 0.003) and hypertension (46 vs 18%, p = 0.003). Patients with recurrent restenosis had a shorter interval between first and second PTCA compared with those who remained patent (136 +/- 116 vs 214 +/- 163 days, p = 0.018). Multivariate analysis confirmed unstable angina, diabetes and hypertension as independent predictors of recurrent restenosis. Repeat PTCA may be performed for restenosis with a high likelihood of success and low incidence of complications. The rate of recurrent restenosis is similar to that reported for initial angioplasty. Patients with unstable angina, diabetes and hypertension appear to be at higher risk for recurrent restenosis.

Late restenosis after emergent coronary angioplasty for acute myocardial infarction: comparison with elective coronary angioplasty.

The late restenosis rate after emergent percutaneous transluminal coronary angioplasty for acute myocardial infarction was assessed by performing outpatient follow-up cardiac catheterization in 79 (87%) of 91 consecutive patients who had been discharged from the hospital with a successful coronary angioplasty. The majority of patients (90%) received high dose intravenous thrombolytic therapy with streptokinase in addition to angioplasty. Similar follow-up data were obtained in 206 (90%) of 228 consecutive patients who had successful elective angioplasty during the same period. The interval from angioplasty to follow-up was 28 +/- 9 weeks for the myocardial infarction group and 30 +/- 11 weeks for the elective group. Baseline clinical variables were similar for both the myocardial infarction and elective groups except for a higher percentage of men in the infarction group (81 versus 63%, p = 0.001). The number of coronary lesions undergoing angioplasty and the incidence of intimal dissection were similar, but multivessel angioplasty was more common in the elective group (13 versus 4%, p = 0.02). The rate of in-hospital reocclusion was higher in the patients receiving angioplasty for myocardial infarction (13 versus 2%, p = 0.0001). At the time of late follow-up after hospital discharge, the patients with myocardial infarction were more often asymptomatic (79 versus 55%, p = 0.0001), and the rate of angiographic coronary restenosis was lower for the infarction group both overall (19 versus 35%, p = 0.006) and when multivessel angioplasty patients were excluded (19 versus 33%, p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)