Ultrasound measurement of fetal growth inMacaca nemestrina

Application of ultrasonographic human estimated foetal weight formulas to cynomolgus monkeys (Macaca fascicularis) at 129-132 days of gestation: A comparative study of estimated and actual birthweight

BACKGROUND

Cynomolgus monkeys (Macaca fascicularis) are essential in biomedical research, including reproductive studies. However, the application of human estimated foetal weight (EFW) formulas using ultrasonography (USG) in these non-human primates is not well established.

OBJECTIVES

This study aims to evaluate the applicability of human EFW formulas for estimating foetal weight in cynomolgus monkeys at approximately 130 days of gestation.

METHODS

Our study involved nine pregnant cynomolgus monkeys. We measured foetal parameters, including biparietal diameter, head circumference, abdominal circumference and femur length using USG. The EFW was calculated using 11 human EFW formulas. The actual birthweight (ABW) was recorded following Cesarean section, the day after the EFW calculation. For comparing EFW and ABW, we employed statistical methods such as mean absolute percentage error (APE) and Bland-Altman analysis.

RESULTS

The ABW ranged between 200.36 and 291.33 g. Among the 11 formulas, the Combs formula showed the lowest APE (4.3%) and highest correlation with ABW (p < 0.001). Notably, EFW and ABW differences for the Combs formula were ≤5% in 66.7% and ≤10% in 100% of cases. The Bland-Altman analysis supported these results, showing that all cases fell within the limits of agreement.

CONCLUSIONS

The Combs formula is applicable for estimating the weight of cynomolgus monkey fetuses with USG at approximately 130 days of gestation. Our observations suggest that the Combs formula can be applied in the prenatal care and biomedical research of this species.

Serial ultrasonographic measurements of fetal parameters over three successive pregnancies in a captive Eastern black-and-white colobus monkey (Colobus guereza)

This study provides ultrasonographic fetal growth charts for the Eastern black-and-white colobus monkey (Colobus guereza). Throughout three consecutive gestations (-162 to -2 days to parturition) in a single dam, we opportunistically obtained ultrasonographic measurements for the following parameters: biparietal diameter, head circumference, humerus length, femur length, tibia length, radius length, thoracic width, kidney length, and crown-rump length. Biparietal diameter was the most consistently measured parameter. First detection of fetuses occurred between 96 and 162 days before parturition. This report demonstrates that voluntary transabdominal ultrasound can be well-tolerated in the colobus monkey using operant conditioning. These findings may be useful to assess fetal development and predict parturition dates in the absence of a known conception date in this species.

Congenital Zika virus infection as a silent pathology with loss of neurogenic output in the fetal brain

Zika virus (ZIKV) is a flavivirus with teratogenic effects on fetal brain, but the spectrum of ZIKV-induced brain injury is unknown, particularly when ultrasound imaging is normal. In a pregnant pigtail macaque (Macaca nemestrina) model of ZIKV infection, we demonstrate that ZIKV-induced injury to fetal brain is substantial, even in the absence of microcephaly, and may be challenging to detect in a clinical setting. A common and subtle injury pattern was identified, including (i) periventricular T2-hyperintense foci and loss of fetal noncortical brain volume, (ii) injury to the ependymal epithelium with underlying gliosis and (iii) loss of late fetal neuronal progenitor cells in the subventricular zone (temporal cortex) and subgranular zone (dentate gyrus, hippocampus) with dysmorphic granule neuron patterning. Attenuation of fetal neurogenic output demonstrates potentially considerable teratogenic effects of congenital ZIKV infection even without microcephaly. Our findings suggest that all children exposed to ZIKV in utero should receive long-term monitoring for neurocognitive deficits, regardless of head size at birth.

Ultrasonographic aspects of the Leontopithecus gestation (Lesson, 1840-Callitrichidae, Primates)

BACKGROUND

There is a concern about conservation of endangered species today. Among this species, the Leontopithecus (Lesson, 1840) is outstanding. Its population has been whirling reduced. So far the reproductive physiology of Leontopithecus has few studies, it is fundamental requisite to preserve this species. Obstetric sonography has become an essential method in reproductive management of primates.

METHOD

This method is very helpful to detect early pregnancy and evaluate some deficiency of fetal growth. In this study, 14 pregnancies were monitored using real-time abdominal sonography. During each evaluation, the number of fetus was recorded, gestational sac and heart beats were observed, and biparietal diameter was measured.

RESULTS

The results showed that abdominal sonography is a reliable method for observation of gross morphological changes during pre-natal development and to estimate gestational age. No statistically differences were observed between twins and singletons. This study is the first investigation of pre-natal growth in Leontopithecus.

Fetal brain lesions after subcutaneous inoculation of Zika virus in a pregnant nonhuman primate

We describe the development of fetal brain lesions after Zika virus (ZIKV) inoculation in a pregnant pigtail macaque. Periventricular lesions developed within 10 d and evolved asymmetrically in the occipital-parietal lobes. Fetal autopsy revealed ZIKV in the brain and significant cerebral white matter hypoplasia, periventricular white matter gliosis, and axonal and ependymal injury. Our observation of ZIKV-associated fetal brain lesions in a nonhuman primate provides a model for therapeutic evaluation.

Four decades of leading-edge research in the reproductive and developmental sciences: the Infant Primate Research Laboratory at the University of Washington National Primate Research Center

The Infant Primate Research Laboratory (IPRL) was established in 1970 at the University of Washington as a visionary project of Dr. Gene (Jim) P. Sackett. Supported by a collaboration between the Washington National Primate Research Center and the Center on Human Development and Disability, the IPRL operates under the principle that learning more about the causes of abnormal development in macaque monkeys will provide important insights into the origins and treatment of childhood neurodevelopmental disabilities. Over the past 40 years, a broad range of research projects have been conducted at the IPRL. Some have described the expression of normative behaviors in nursery-reared macaques while others have focused on important biomedical themes in child health and development. This article details the unique scientific history of the IPRL and the contributions produced by research conducted in the laboratory. Past and present investigations have explored the topics of early rearing effects, low-birth-weight, prematurity, birth injury, epilepsy, prenatal neurotoxicant exposure, viral infection (pediatric HIV), diarrheal disease, vaccine safety, and assisted reproductive technologies. Data from these studies have helped advance our understanding of both risk and resiliency in primate development. New directions of research at the IPRL include the production of transgenic primate models using our embryonic stem cell-based technology to better understand and treat heritable forms of human intellectual disabilities such as fragile X.

In vitro fertilization in the pigtailed macaque (Macaca nemestrina)

The objective of this study was to investigate the possibility of collecting oocytes and semen from pigtailed macaques (Macaca nemestrina) and to establish a protocol for the production of viable embryos that would be suitable for transfer into surrogate females. A total of 82 oocytes were collected from a total of four females (on 2 d with two females each). Semen was collected from the same male on both occasions with respective ejaculate volumes of 0.55 and 0.1 mL containing 2 x 10(9) and 6.6 x 10(8)sperm/mL. Following insemination and after 48 h in culture, 42 (51.2%) of the oocytes had cleaved. Of these, 21 were selected based on developmental stage and their morphology and cryopreserved. The remainder was kept in culture for an additional 5 d, at which time three had reached the expanded blastocyst stage. A total of five transfers were performed with frozen-thawed embryos; two of these resulted in pregnancies and the birth of infants. The results of this study demonstrated that oocytes can be retrieved from pigtailed macaques and that such oocytes can be inseminated and cultured in vitro to the blastocyst stage and give rise to viable offspring after transfer into surrogate females.

The use of CD 34(+) mobilized peripheral blood as a donor cell source does not improve chimerism after in utero hematopoietic stem cell transplantation in non-human primates

In utero hematopoietic stem cell transplantation is a therapeutic procedure that could potentially cure many developmental diseases affecting the immune and hematopoietic systems. In most clinical and experimental settings of fetal hematopoietic transplantation the level of donor cell engraftment has been low, suggesting that even in the fetus there are significant barriers to donor cell engraftment. In postnatal hematopoietic transplantation donor cells obtained from mobilized peripheral blood engraft more rapidly than cells derived from marrow. We tested the hypothesis that use of donor hematopoietic/stem cells obtained from mobilized peripheral blood would improve engraftment and the level of chimerism after in utero transplantation in non-human primates. Despite the potential competitive advantage from the use of CD 34(+) from mobilized peripheral blood, the level of chimerism was not appreciably different from a group of animals receiving marrow-derived CD 34(+) donor cells. Based on these results, it is unlikely that this single change in cell source will influence the clinical outcome of fetal hematopoietic transplantation.

Fetal Immune Suppression as Adjunctive Therapy for In Utero Hematopoietic Stem Cell Transplantation in Nonhuman Primates

In utero hematopoietic stem cell transplantation could potentially be used to treat many genetic diseases but rarely has been successful except in severe immunodeficiency syndromes. We explored two ways to potentially increase chimerism in a nonhuman primate model: (a) fetal immune suppression at the time of transplantation and (b) postnatal donor stem cell infusion. Fetal Macaca nemestrina treated with a combination of the corticosteroid betamethasone (0.9 mg/kg) and rabbit thymoglobulin (ATG; 50 mg/kg) were given haploidentical, marrow-derived, CD34+ -enriched donor cells. Animals treated postnatally received either donor-derived T cell-depleted or CD34+ -enriched marrow cells. Chimerism was determined by traditional and real-time polymerase chain reaction from marrow, marrow progenitors, peripheral blood, and mature peripheral blood progeny. After birth, the level of chimerism in the progenitor population was higher in the immune-suppressed animals relative to controls (11.3% +/- 2.7% and 5.1% +/- 1.5%, respectively; p = .057). Chimerism remained significantly elevated in both marrow (p = .02) and fluorescence-activated cell sorted and purified CD34+ cells (p = .01) relative to control animals at > or = 14 months of age. Peripheral blood chimerism, both at birth and long term, was similar in immune-suppressed and control animals. In the animals receiving postnatal donor cell infusions, there was an initial increase in progenitor chimerism; however, at 6-month follow-up, the level of chimerism was unchanged from the preinfusion values. Although fetal immune suppression was associated with an increase in the level of progenitor and marrow chimerism, the total contribution to marrow and the levels of mature donor progeny in the peripheral blood remained low. The level of long-term chimerism also was not improved with postnatal donor cell infusion.

In utero hematopoietic stem cell transplantation in nonhuman primates: the role of T cells

In utero transplantation of hematopoietic stem cells is a promising treatment for immune and hematologic diseases of fetuses and newborns. Unfortunately, there are limited data from nonhuman primates and humans describing optimal transplantation conditions. The purpose of this investigation was to determine the effect of T-cell number on engraftment and the level of chimerism after in utero transplantation in nonhuman primates. CD34(+) allogeneic adult bone marrow cells, obtained from the sire after G-CSF and stem cell factor administration, were transplanted into female fetal recipients. The average CD34(+) cell dose was 3.0 x 10(9)/kg (range, 9.9 x 10(8) to 4.4 x 10(9)) and the T-cell dose ranged from 2.6 x 10(5) to 1.1 x 10(8)/kg. Chimerism was determined in peripheral blood subsets (CD2, CD13, and CD20) and in progenitor cell populations by using polymerase chain reaction. Chimerism was noted in seven of eight live-born animals. The level of chimerism in the progenitor population was related to the fetal T-cell dose (r = 0.64, p < 0.02). At the lowest T-cell dose (2.6 x 10(5)/kg), no chimerism was detected. As the T-cell dose increased to 10(6-7)/kg, the level of chimerism increased. Adjusting the T-cell dose to 1.1 x 10(8)/kg resulted in fatal graft-versus-host disease (GVHD). The results of this study emphasize the importance of T cells in facilitating donor cell engraftment and in producing GVHD in fetal nonhuman primates. Some animals achieved levels of chimerism in the marrow hematopoietic progenitor cell population that would likely have clinical relevance. However, the levels of chimerism in peripheral blood were too low for therapeutic benefit. Further studies are needed to test methods that are likely to enhance donor cell engraftment and peripheral blood levels of donor cells.

Incorporating children's toxicokinetics into a risk framework

Children's responses to environmental toxicants will be affected by the way in which their systems absorb, distribute, metabolize, and excrete chemicals. These toxicokinetic factors vary during development, from in utero where maternal and placental processes play a large role, to the neonate in which emerging metabolism and clearance pathways are key determinants. Toxicokinetic differences between neonates and adults lead to the potential for internal dosimetry differences and increased or decreased risk, depending on the mechanisms for toxicity and clearance of a given chemical. This article raises a number of questions that need to be addressed when conducting a toxicokinetic analysis of in utero or childhood exposures. These questions are organized into a proposed framework for conducting the assessment that involves problem formulation (identification of early life stage toxicokinetic factors and chemical-specific factors that may raise questions/concerns for children); data analysis (development of analytic approach, construction of child/adult or child/animal dosimetry comparisons); and risk characterization (evaluation of how children's toxicokinetic analysis can be used to decrease uncertainties in the risk assessment). The proposed approach provides a range of analytical options, from qualitative to quantitative, for assessing children's dosimetry. Further, it provides background information on a variety of toxicokinetic factors that can vary as a function of developmental stage. For example, the ontology of metabolizing systems is described via reference to pediatric studies involving therapeutic drugs and evidence from in vitro enzyme studies. This type of resource information is intended to help the assessor begin to address the issues raised in this paper.

Weaning, body weight, and postpartum amenorrhea duration in pigtailed macaques (Macaca nemestrina)

Early permanent infant separation or weaning decreases the time interval between pregnancies and interbirth intervals for many female primates. At least part of the interpregnancy interval consists of postpartum amenorrhea, a period of non-menstruation lasting from the time of birth until the female begins to ovulate. This study investigated the effects of weaning age and dam's body weight on the duration of the interval between pregnancies, the duration of postpartum amenorrhea, and the number of cycles to conception in a year-round breeder. Female pigtailed macaques (Macaca nemestrina) have an observable perineal swelling that fluctuates throughout the menstrual cycle and provides a means of detecting ovulation. The perineal swelling records of socially housed pigtailed macaques were studied from July 1996 to September 1998. Postpartum amenorrhea data were obtained on 44 females who gave birth to normal, viable infants. As weaning age increased and dam's weight decreased, postpartum amenorrhea, and consequently the interval between pregnancies, increased in duration. The interpregnancy interval consisted almost entirely of the postpartum amenorrhea phase. Our finding that a higher dam's body weight decreased the length of postpartum amenorrhea duration lends support to the hypothesis that a minimum body weight is necessary for menstrual cycles to occur. Most females became pregnant on their first ovulation regardless of weaning age and whether or not they were carrying an infant. As the weaning age of the infant and the dam's weight increased, ovulation went from occurring after separation to occurring before separation.

Fetal, infant, and maternal toxicity of zidovudine (azidothymidine) administered throughout pregnancy in Macaca nemestrina

The toxicity of azidothymidine (AZT) was studied in monkey dams and fetuses that were exposed to the drug over the entire gestational period. Fourteen virus-free female macaques (Macaca nemestrina) were randomly assigned to AZT or control groups. AZT animals received the drug through a gastric catheter at a dose of 1.5 mg/kg every 4 hours, which produced plasma concentrations similar to those in humans taking 500 to 600 mg/day of AZT. Control animals received water placebo, also through gastric catheter. Some animals participated in both groups. All females were mated with the same male; 41 matings produced 20 pregnancies, of which 16 were carried to term (9 in AZT females; 7 in control females). The AZT animals developed an asymptomatic macrocytic anemia, but hematologic parameters returned to normal when AZT was discontinued. Total leukocyte count decreased during pregnancy and was further affected by AZT administration. AZT-exposed infants were mildly anemic at birth. AZT caused deficits in growth, rooting and snouting reflexes, and the ability to fixate and follow near stimuli visually, but the deficits disappeared over time. These data indicate that early exposure to AZT in utero should have no irreversible adverse effects on the fetus.

Estimation of gestational ages in the common marmoset (Callithrix jacchus) from published prenatal growth curves

This report compares estimated gestational ages from published cubic spline curves to gestational ages estimated retrospectively from delivery dates in 28 pregnancies from ten common marmosets (Callithrix jacchus). Both CRL- and BPD-based estimates of gestational age were closely correlated with delivery-based gestational age estimates. Of the three ultrasound machines used, the one with 16 shades of gray and a sequential linear array overestimated gestational age during early pregnancy, based on CRL measures. Measures from the other two machines (64 or 264 shades of gray; linear sector and annular array or electronic phase array) were similar and resulted in a correlation of the two estimates of gestational age of 0.94 and a mean difference between the two estimates of 0.16 days with 80% of CRL-based gestational age estimates being within +/- 5 days of the delivery-based estimate. The reliability of BPD-based estimates of gestational age was strongly related to pregnancy outcome. BPD-based estimates underestimated gestational age in poor outcome pregnancies (i.e., those in which infants died within 7 days of birth) but not in good outcome pregnancies. The combined CRL- and BPD-based estimates on poor outcome pregnancies suggest that there was less growth in BPD in late gestation for those pregnancies that resulted in nonviable offspring. For good outcome pregnancies, the correlation between BPD-based and delivery-based estimates of gestational age was 0.871 and the mean difference between the two estimates was -0.06 days with 83.3% of BPD-based estimates falling within +/- 5 days of delivery-based estimates.