Selection of endurance capabilities and the trade-off between pressure and volume in the evolution of the human heart

Chimpanzees and gorillas, when not inactive, engage primarily in short bursts of resistance physical activity (RPA), such as climbing and fighting, that creates pressure stress on the cardiovascular system. In contrast, to initially hunt and gather and later to farm, it is thought that preindustrial human survival was dependent on lifelong moderate-intensity endurance physical activity (EPA), which creates a cardiovascular volume stress. Although derived musculoskeletal and thermoregulatory adaptations for EPA in humans have been documented, it is unknown if selection acted similarly on the heart. To test this hypothesis, we compared left ventricular (LV) structure and function across semiwild sanctuary chimpanzees, gorillas, and a sample of humans exposed to markedly different physical activity patterns. We show the human LV possesses derived features that help augment cardiac output (CO) thereby enabling EPA. However, the human LV also demonstrates phenotypic plasticity and, hence, variability, across a wide range of habitual physical activity. We show that the human LV’s propensity to remodel differentially in response to chronic pressure or volume stimuli associated with intense RPA and EPA as well as physical inactivity represents an evolutionary trade-off with potential implications for contemporary cardiovascular health. Specifically, the human LV trades off pressure adaptations for volume capabilities and converges on a chimpanzee-like phenotype in response to physical inactivity or sustained pressure loading. Consequently, the derived LV and lifelong low blood pressure (BP) appear to be partly sustained by regular moderate-intensity EPA whose decline in postindustrial societies likely contributes to the modern epidemic of hypertensive heart disease

Factors affecting tear production and intraocular pressure in anesthetized chimpanzees (Pan troglodytes)

Measurements of intraocular pressure (IOP) and tear production are key components of ophthalmic examination. Chimpanzees (Pan troglodytes) were anesthetized using either tiletamine-zolazepam (TZ; 2 mg/kg) combined with medetomidine (TZM; 0.02 mg/kg), or, TZ alone (6mg/kg). Tear production was lower (P = 0.03) with TZM (5.63 ± 6.22 mm/min; n = 16) than with TZ (11.13 ± 4.63 mm/min; n = 8). Mean IOP, measured using rebound tonometry in an upright body position (n = 8) was 18.74 ± 3.01 mm Hg, with no differences between right and left eyes. However, positioning chimpanzees in left lateral recumbency (n = 27) resulted in higher IOP in the dependent (left) eye (24.77 ± 4.49 mm Hg) compared to the nondependent (right) eye (22.27 ± 4.65 mm Hg) of the same animal (P < 0.0001). These data indicate medetomidine anesthesia markedly lowers tear production in chimpanzees, and that body position should be taken into consideration when performing rebound tonometry

The influence of anesthesia with and without medetomidine on cardiac structure and function in sanctuary captive chimpanzees (pan troglodytes)

Dependent on timing of assessment, anesthetic agents and specifically medetomidinenegatively impact cardiac function in great apes. The aim of this study was todetermine the influence of tiletamine-zolazepam with and without medetomidine oncardiac structure and function in healthy chimpanzees ( Pan troglodytes ) during aperiod of relative blood pressure stability. Twenty-four chimpanzees living in an Africanwildlife sanctuary undergoing routine health assessments were stratified by age, sexand body mass and randomized to be anesthetized using either tiletamine-zolazepam(6 mg/kg; TZ; n=13; seven males and six females) or a combination of tiletamine-zolazepam (2 mg/kg) and medetomidine (0.02 mg/kg; TZM; n= 11; five males and sixfemales). During the health checks, regular heart rate and blood pressure readingswere taken and a standardized echocardiogram was performed 20-30 minutes post-induction. Data were compared between the two anesthetic groups using independentsamples T or Mann Whitney U tests. Whileheart rate (Mean ± S.D; TZ: 76 ± 10 bpm;TZM: 65 ± 14 bpm, P = 0.027), cardiac output (TZ: 3.0 ± 0.7 L/min; TZM: 2.4 ±0.7 L/min, P = 0.032) and mitral A wave velocities (TZ: 0.51 ± 0.16 cm/s; TZM:0.36 ± 0.10 cm/s, P = 0.013) were lower in the TZM group, there were no statisticallysignificant differences in cardiac structure or the remaining functional variablesbetween groups. Furthermore, there were no statistical differences in systolic (TZ114.6 ± 14.9 mmHg; TZM: 123.0 ± 28.1 mmHg; P = 0.289) or diastolic bloodpressure (TZ: 81.8 ± 22.3 mmHg, TZM: 83.8 ± 20.1 mmHg; P = 0.827) between thegroups during the echocardiogram. This study has shown that during a period ofrelative blood pressure stability there are few differences in measures of cardiacstructure and function between protocols using tiletamine-zolazepam with or withoutmedetomidine in healthy chimpanzees

The influence of anesthetic with and without medetomidine on cardiac structure and function in sanctuary captive chimpanzees (Pan troglodytes)

Dependent on timing of assessment, anesthetic agents and specifically medetomidine negatively affect cardiac function in great apes. The aim of this study was to determine the influence of tiletamine–zolazepam (TZ) with and without medetomidine on cardiac structure and function in healthy chimpanzees (Pan troglodytes) during a period of relative blood pressure stability. Twenty-four chimpanzees living in an African wildlife sanctuary undergoing routine health assessments were stratified by age, sex, and body mass and randomized to be anesthetized using either TZ (6 mg/kg; n = 13; seven males and six females) or a combination of TZ (2 mg/kg) and medetomidine (TZM; 0.02 mg/kg; n = 11; five males and six females). During health checks, regular heart rate and blood pressure readings were taken and a standardized echocardiogram was performed 20–30 min after induction. Data were compared between the two anesthetic groups using independent-samples t or Mann–Whitney U tests. Although heart rate (mean ± SD; TZ: 76 ± 10 bpm; TZM: 65 ± 14 bpm, P = 0.027), cardiac output (TZ: 3.0 ± 0.7 L/min; TZM: 2.4 ± 0.7 L/min, P = 0.032), and mitral A-wave velocities (TZ: 0.51 ± 0.16 cm/s; TZM: 0.36 ± 0.10 cm/s, P = 0.013) were lower in the TZM group, there were no statistically significant differences in cardiac structure or the remaining functional variables between groups. Furthermore, there were no statistical differences in systolic (TZ 114.6 ± 14.9 mmHg; TZM: 123.0 ± 28.1 mmHg; P = 0.289) or diastolic blood pressure (TZ: 81.8 ± 22.3 mmHg, TZM: 83.8 ± 20.1 mmHg; P = 0.827) between the groups during the echocardiogram. This study has shown that during a period of relative blood pressure stability, during the first 20–30 min after induction there are few differences in measures of cardiac structure and function between protocols using TZ with or without medetomidine in healthy chimpanzees

Ferlavirus-related deaths in a collection of viperid snakes

Between June and October 2013 26 snakes of six viperid species kept in two adjoining rooms died (n = 16) or were euthanized on medical (1) or welfare grounds (9). Two were from the main zoo collection, but the other 24 had been imported and quarantined for a minimum of six months. Four of those that died and the single snake euthanized on medical grounds showed minor signs of respiratory disease prior to death and five were weak, lethargic and/or poor feeders. Frequent post mortem findings among all snakes were poor body condition (18) and respiratory disease (13). Seventeen cases were examined histologically and pneumonia, sometimes with air sacculitis and/or tracheitis, was present in 15 individuals. Lung samples from 24 snakes were ferlavirus polymerase chain reaction (PCR) positive, and one of the two snakes for which only liver was available was also positive. The negative liver samples was from a snake that died of sepsis following anaesthesia for surgical removal of a spindle cell sarcoma. Correlation with ante mortem PCR testing of glottal and cloacal swabs in five cases was poor (sensitivity = 40%). Immunohistochemistry (IHC) for ferlaviruses on the tissues of 13 PCR-positive cases showed positive labelling in seven only. Tissues samples from 22 ferlavirus PCR-positive snakes were examined for Chlamydia species by PCR and nine were positive, although DNA sequencing only confirmed two out of three tested as C.pneumoniae. Immunohistochemistry for C.pneumoniae of seven cases (two Chlamydiales PCR positive, one of which was sequenced as C.pneumoniae, plus five negative) confirmed the Chlamydia PCR results.These two Chlamydiales PCR and IHC positive snakes were ferlavirus PCR positive, but IHC negative suggesting that, even though a ferlavirus was the predominant cause of the outbreak, in a few cases death may have been due to chlamydiosis with ferlavirus present, but not acting as the primary pathogen

Cardiac structure and function characterized across age groups and between sexes in healthy wild-born captive chimpanzees (Pan troglodytes) living in sanctuaries

Objective: To comprehensively characterize cardiac structure and function, from infancy to adulthood, in male and female wild-born captive chimpanzees (Pan troglodytes) living in sanctuaries. Animals: 290 wild-born captive chimpanzees. Procedures: Physical and echocardiographic examinations were performed on anesthetized chimpanzees in 3 sanctuaries in Africa between October 2013 and May 2017. Results were evaluated across age groups and between sexes, and potential differences were assessed with multiple 1-way independent Kruskal-Wallis tests. Results: Results indicated that left ventricular diastolic and systolic function declined at a younger age in males than in females. Although differences in right ventricular diastolic function were not identified among age groups, right ventricular systolic function was lower in adult chimpanzees (> 12 years old), compared with subadult (8 to 12 years old) and juvenile (5 to 7 years old) chimpanzees. In addition, male subadult and adult chimpanzees had larger cardiac wall dimensions and chamber volumes than did their female counterparts. Conclusions and Clinical Relevance: Results of the present study provided useful reference intervals for cardiac structure and function in captive chimpanzees categorized on the basis of age and sex; however, further research is warranted to examine isolated and combined impacts of blood pressure, age, body weight, and anaesthetic agents on cardiac structure and function in chimpanzees

Heart rate and and indirect blood pressure responses to four different anesthetic protocols in wild-born captive chimpanzees (Pan Troglodytes)

Limited data are available on hemodynamic responses to anesthetic protocols in wild-born chimpanzees (Pan troglodytes). Accordingly, this study characterized the heart rate (HR) and blood pressure responses to four anesthetic protocols in 176 clinically healthy, wild-born chimpanzees undergoing routine health assessments. Animals were anesthetized with medetomidine–ketamine (MK) (n = 101), tiletamine–zolazepam (TZ) (n = 30), tiletamine–zolazepam–medetomidine (TZM) (n = 24), or medetomidine–ketamine (maintained with isoflurane) (MKI) (n = 21). During each procedure, HR, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were regularly recorded. Data were grouped according to anesthetic protocol, and mean HR, SBP, and DBP were calculated. Differences between mean HR, SBP, and DBP for each anesthetic protocol were assessed using the Kruskall–Wallis test and a Dunn multiple comparisons post hoc analysis. To assess the hemodynamic time course response to each anesthetic protocol, group mean data (±95% confidence interval [CI]) were plotted against time postanesthetic induction. Mean HR (beats/min [CI]) was significantly higher in TZ (86 [80–92]) compared to MKI (69 [61–78]) and MK (62 [60–64]) and in TZM (73 [68–78]) compared to MK. The average SBP and DBP values (mm Hg [CI]) were significantly higher in MK (130 [126–134] and 94 [91–97]) compared to TZ (104 [96–112] and 58 [53–93]) and MKI (113 [103–123] and 78 [69–87]) and in TZM (128 [120–135] and 88 [83–93]) compared to TZ. Time course data were markedly different between protocols, with MKI showing the greatest decline over time. Both the anesthetic protocol adopted and the timing of measurement after injection influence hemodynamic recordings in wild-born chimpanzees and need to be considered when monitoring or assessing cardiovascular health

Body mass and growth rates in captive chimpanzees (Pan troglodytes) cared for in African wildlife sanctuaries, zoological institutions and research facilities: Body mass in captive chimpanzees

Captive chimpanzees (Pan troglodytes) mature earlier in body mass and have a greater growth rate compared to wild individuals. However, relatively little is known about how growth parameters compare between chimpanzees living in different captive environments. To investigate, body mass was measured in 298 African sanctuary chimpanzees, and was acquired from 1030 zoological and 442 research chimpanzees, using data repositories. An ANCOVA, adjusting for age, was performed to assess same-sex body mass differences between adult sanctuary, zoological and research populations. Piecewise linear regression was performed to estimate sex-specific growth rates and the age at maturation, which were compared between sexes and across populations using extra-sum-of-squares F tests. Adult body mass was greater in the zoological and research populations compared to the sanctuary chimpanzees, in both sexes. Male and female sanctuary chimpanzees were estimated to have a slower rate of growth compared with their zoological and research counterparts. Additionally, male sanctuary chimpanzees were estimated to have an older age at maturation for body mass compared with zoological and research males, whereas the age at maturation was similar across female populations. For both the zoological and research populations, the estimated growth rate was greater in males compared to females. Together, these data contribute to current understanding of growth and maturation in this species and suggests marked differences between the growth patterns of chimpanzees living in different captive environments