Maria Melchert

Mrs. Maria Melchert

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Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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14 November 2020 in Animals
Verified
Journal Article
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JHJohannes Herbel
Johannes Herbel
JAJoerg Aurich
Joerg Aurich
CGCamille Gautier
Camille Gautier
MMMaria Melchert
Maria Melchert
Christine AurichChristine Aurich
Christine Aurich
This study aimed to characterize the response of transport-naïve dogs to one and two-hour road transports based on cortisol in saliva and blood plasma, heart rate, heart rate variability (HRV), neutrophil to lymphocyte (N/L) ratio and behavior. Two persons familiar to the dogs were present during transports and control experiments. We hypothesized that transport elicits a stress response, which decreases with repeated transports. Beagle dogs were allocated to three groups (n = 6 each). Group 1 served as control in the stable in week 1 and was transported for one hour in weeks 2, 3 and 4. Groups 2 and 3 served as controls in a non-moving vehicle and in the stable, respectively, in week 2. All three groups were transported for two hours in week 6. Cortisol concentration increased during transports (p < 0.001), and this increase remained constant with repeated transports. Cortisol release during two-hour transports was not affected by transport experience. Cortisol concentration increased twofold in plasma and eightfold in saliva, indicating an increase in free cortisol. The N/L ratio increased during transport (p < 0.05). Heart rate increased at the beginning of transport while HRV decreased (p < 0.001). Heart rate and HRV neither differed among weeks nor between animals with different transport experience. During transports, but also in the stationary vehicle, dogs were mostly sitting, and time spent standing decreased during experiments (p < 0.001). Licking the mouth was the most frequent behavior during transports but not in the stationary vehicle (p < 0.01). In conclusion, a transport-induced stress response was evident in dogs. There was no habituation with repeated transports, and transported dogs may suffer from motion sickness.

4 September 2020 in Animals
Verified
Journal Article
Open access
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CNChristina Nagel
Christina Nagel
MMMaria Melchert
Maria Melchert
Christine AurichChristine Aurich
Christine Aurich
JAJoerg Aurich
Joerg Aurich
Equine fetomaternal monitoring is based on endocrine and cardiac parameters which may differ among small, medium-size, and full-size horses. Therefore, Shetland (n = 6), Haflinger (n = 8), and Warmblood pregnancies (n = 9) were studied during late gestation and at foaling. Weight of mares, foals and placenta, plasma progestin and cortisol concentration, heart rate and heart rate variability (HRV) were determined. Foal weight always approximated 10% of mare weight but relative placenta weight was highest in full-size mares (p < 0.05). Progestin (p < 0.001) and cortisol (p < 0.05) concentration was highest in full-size mares. Progestin concentration decreased towards parturition (p < 0.001) while cortisol concentration increased (p < 0.01). Maternal heart rate increased before foaling with the most pronounced increase in small mares (p < 0.001). The HRV increased during foaling and decreased when delivery was completed (p < 0.001). Changes were most pronounced in full-size mares (p < 0.001). Atrio-ventricular blocks regularly occurred in parturient full-size mares but only occasionally in medium-size and small mares (time p < 0.05, time × group p < 0.05). This may reflect breed differences in cardiovascular efficiency. Fetal heart rate decreased towards birth (p < 0.001) with the most pronounced decrease in full-size horses (p < 0.01). Fetal HRV showed no consistent changes before birth but increased when the foal was born (p < 0.001), this increase being most pronounced in full-size foals (p < 0.05). In conclusion, this study demonstrates both similarities and differences in peripartum endocrine and cardiac changes in horses of different size.

4 March 2021 in Pathogens
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Journal Article
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EDEsther Dirks
Esther Dirks
PHPhebe De Heus
Phebe De Heus
Anja JoachimAnja Joachim
Anja Joachim
JCJessika-M. Cavalleri
Jessika-M. Cavalleri
ISIlse Schwendenwein
Ilse Schwendenwein
Hans-Peter FuehrerHans-Peter Fuehrer
Hans-Peter Fuehrer
A 23-year-old pregnant warmblood mare from Güssing, Eastern Austria, presented with apathy, anemia, fever, tachycardia and tachypnoea, and a severely elevated serum amyloid A concentration. The horse had a poor body condition and showed thoracic and pericardial effusions, and later dependent edema and icteric mucous membranes. Blood smear and molecular analyses revealed an infection with Theileria equi. Upon treatment with imidocarb diproprionate, the mare improved clinically, parasites were undetectable in blood smears, and 19 days after hospitalization the horse was discharged from hospital. However, 89 days after first hospitalization, the mare again presented to the hospital with an abortion, and the spleen of the aborted fetus was also PCR-positive for T. equi. On the pasture, where the horse had grazed, different developmental stages of Dermacentor reticulatus ticks were collected and subjected to PCR, and one engorged specimen was positive for T. equi. All three amplicon sequences were identical (T. equi genotype E). It is suspected that T. equi may repeatedly be transmitted in the area where the infected mare had grazed, and it could be shown that transmission to the fetus had occurred. Due to the chronic nature of equine theileriosis and the possible health implications of infection, it is advised to include this disease in the panel of differential diagnoses in horses with relevant clinical signs, including horses without travel disease, and to be aware of iatrogenic transmission from inapparent carrier animals.

6 May 2021 in Animals
Verified
Journal Article
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Gustavo Desire Antunes GastalGustavo Desire Antunes Gastal
Gustavo Desire Antunes Gastal
DSDragos Scarlet
Dragos Scarlet
MMMaria Melchert
Maria Melchert
REReinhard Ertl
Reinhard Ertl
Christine AurichChristine Aurich
Christine Aurich
In embryos subjected to assisted reproductive techniques, epigenetic modifications may occur that can influence embryonic development and the establishment of pregnancy. In horses, the storage temperature during transport of fresh embryos before transfer is a major concern. The aim of this study was, therefore, to determine the effects of two storage temperatures (5 °C and 20 °C) on equine embryos, collected at day seven after ovulation and stored for 24 h, on: (i) morphological development; (ii) expression of candidate genes associated with embryo growth and development, maternal recognition of pregnancy, methylation and apoptosis, and (iii) gene-specific and global DNA methylation. Embryos (n = 80) were collected on day seven or day eight after ovulation and assigned to four groups: day seven control (E7F, fresh); day seven, stored for 24 h at 5 °C (E5C); day seven, stored for 24 h at 20 °C (E20C) and day eight control (E8F, fresh 24h time control). The embryos and the storage medium (EquiHold, holding medium, Minitube, Tiefenbach, Germany) from all treatment groups were analyzed for (i) medium temperature, pH, and lipid peroxidation (malondialdehyde; MDA) and (ii) embryo morphology, mRNA expression and DNA methylation (immunohistochemistry and gene-specific DNA methylation). The size of embryos stored at 5 °C was larger (p < 0.01), whereas embryos stored at 20 °C were smaller (p < 0.05) after 24 h. There were no changes in pH and MDA accumulation irrespective of the group. The mRNA expression of specific genes related to growth and development (POU5F1, SOX2, NANOG), maternal recognition of pregnancy (CYP19A1, PTGES2), DNA methylation (DNMT1, DNMT3A, DNMT3B) and apoptosis (BAX) in the E5C and E20C were either up or downregulated (p < 0.05) when compared to controls (E7F and E8F). The immune expression of 5mC and 5hmC was similar among treatment groups. Percentage of methylation in the CpG islands was lower in the specific genes ESR1, NANOG and DNMT1 (p < 0.001) in E20C embryos when compared to E8F (advanced embryo stage). Therefore, our study demonstrates for the first time the gene-specific and global DNA methylation status of fresh equine embryos collected on days seven and eight after ovulation. Although our results suggest some beneficial effects of storage at 20 °C in comparison to 5 °C, the short-term storage, regardless of temperature, modified gene expression and methylation of genes involved in embryo development and may compromise embryo viability and development after transfer.

26 April 2024 in Domestic Animal Endocrinology
Verified
Journal Article
Open access
MMMaria Melchert
Maria Melchert
JAJörg Aurich
Jörg Aurich
REReinhard Ertl
Reinhard Ertl
URUrsula Reichart
Ursula Reichart
IWIngrid Walter
Ingrid Walter
CAChristine Aurich
Christine Aurich
Mares resume ovarian activity rapidly after foaling. Besides follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the pituitary synthesizes prolactin and growth hormone which stimulate insulin-like growth factor (IGF) synthesis in the liver. We tested the hypothesis that follicular growth is initiated already antepartum, mares with early and delayed ovulation differ in IGF-1 release and that there is an additional IGF-1 synthesis in the placenta. Plasma concentrations of LH, FSH, IGF-1, IGF-2, activin and prolactin. IGF-1, IGF-2, prolactin and their receptors in placental tissues were analyzed at the mRNA and protein level. Follicular growth was determined from 15 days before to 15 days after foaling in 14 pregnancies. Mares ovulating within 15 days postpartum formed group OV (n=5) and mares not ovulating within 15 days group NOV (n=9). Before foaling, follicles with a diameter >1 cm were present in all mares and their number increased over time (p<0.05). Follicle growth after foaling was more pronounced in OV mares (day p<0.001, group p<0.05, day x group p<0.05) in parallel to an increase in LH concentration (p<0.001, day x group p<0.001) while FSH increased (p<0.001) similarly in both groups. Plasma concentrations of IGF-1 and prolactin peaked one day after foaling (p<0.001). The IGF-1 mRNA abundance was higher in the allantochorion but lower in the amnion of OV versus NOV mares (group p=0.01, localization x group p<0.01). The IGF-1 receptor mRNA was most abundant in the allantochorion (p<0.001) and IGF-1 protein was expressed in placental tissue without differences between groups. In conclusion, follicular growth in mares is initiated before foaling and placental IGF-1 may enhance resumption of ovulatory cycles.

7 April 2025 in Veterinary Record Case Reports
Verified
Journal Article
Open access
MMMaria Melchert
Maria Melchert
JAJörg Aurich
Jörg Aurich
SRSünne Römer
Sünne Römer
IWIngrid Walter
Ingrid Walter
CAChristine Aurich
Christine Aurich
Two prepartum female alpacas were referred to our institution with the presumed diagnosis of uterine torsion. In both cases, uterine torsion was not confirmed but bacterial placentitis with Escherichia coli as the aetiological agent was diagnosed. Transabdominal ultrasound confirmed the presence of a living fetus, with heart rates of 108 and 75 beats per minute, respectively. The allantoic fluid was hyperechogenic and the placenta partially detached. No signs of uterine torsion were evident. Treatment with antibiotics and NSAIDs was initiated. Female Alpaca #1 gave birth to a healthy cria on Day 5 of treatment. In female Alpaca #2, fetal heart rate had decreased on Day 2, was no longer detectable on Day 3 and 1 day later a dead cria was born. In both cases, the placenta was partially covered with purulent material. In conclusion, placentitis should be included as a differential diagnosis in prepartum alpacas and may be more frequent than previously assumed.