Predictive characteristics of male fertility in alpacas with special reference to seminal NGF

Recent studies document the LH-releasing pathway of nerve growth factor (NGF) in male camelids and that the LH response to seminal NGF is associated with elevated plasma testosterone concentration. Results provide rationale for the hypothesis that NGF in semen is associated with male fertility. In Experiment 1, the association between the amount of NGF in the ejaculate and characteristics of the male reproductive system was examined in alpacas. The concentration of NGF was measured by radioimmunoassay in semen samples collected from male alpacas (n = 47) and correlated with sperm morphology and motility, and measurements of the male reproductive anatomy. Most ejaculates had NGF concentrations that, based on previous studies, triggered ovulation in female camelids, however, we only found a positive correlation between NGF concentration with sperm concentration, thread formation and total NGF, and a negative correlation with pH. In Experiment 2, a retrospective analysis was carried out to determine if breeding performance during the previous season was related to recent concentrations of seminal NGF in male alpacas (n = 22). Birth rates tended to be correlated with sperm concentration and total amount of NGF in the ejaculate (P = 0.09). Experiment 3 was a prospective study to determine the relationship between seminal NGF (n = 8 male alpacas) and ovulation and pregnancy rates in a breeding trial. No association was detected between seminal NGF concentration and ovulation rate, pregnancy rate, or LH response in the female. We conclude that among the breeding males used in our study, the abundance of seminal NGF was correlated with sperm concentration and thread formation, however, it was not predictive of male fertility in alpacas. Examination of males not previously selected as breeding stock may be expected to include a broader range of seminal NGF and provide a more comprehensive understanding of the relationship between seminal NGF and male fertility.

Development and Biodistribution of a Nerve Growth Factor Radioactive Conjugate for PET Imaging

PURPOSE

The purpose of these studies was to develop a nerve growth factor (NGF) radiometal-chelator conjugate to determine the biodistribution and brain uptake of NGF by positron emission tomography/computerized tomography (PET-CT).

PROCEDURES

Purified NGF from llama seminal plasma was conjugated with FITC, and the chelator NOTA or DFO. NGF conjugates were evaluated for bioactivity. NOTA- and DFO-conjugated NGF were radiolabeled with gallium-68 or zirconium-89 ([68 Ga]GaCl3, half-life = 68 min; [89Zr]Zr(oxalate)4, half-life = 3.3 days). [89Zr]Zr-NGF was evaluated for biodistribution (0.5, 1, or 24 h), PET imaging (60 min), and brain autoradiography in mice.

RESULTS

Cell-based in vitro assays confirmed that the NGF conjugates maintained NGF receptor-binding and biological activity. Zirconium-89 and gallium-68 radiolabeling showed a high efficiency; however, only[89Zr]Zr-NGF was stable in vitro. Biodistribution studies showed that, as with most small proteins < 70 kDa, [89Zr]Zr-NGF uptake was predominantly in the kidney and was cleared rapidly with almost complete elimination of NGF at 24 h. Dynamic PET imaging from 0-60 min showed a similar pattern to ex vivo biodistribution with some transient liver uptake. Interestingly, although absolute brain uptake was very low, at 24 h after treatment, cerebral cortex uptake was higher than any other brain area examined and blood.

CONCLUSIONS

We conclude that conjugation of DFO to NGF through a thiourea linkage allows effective radiolabeling with zirconium-89 while maintaining NGF bioactivity. Following intravenous administration, the radiolabeled NGF targets non-neuronal tissues (e.g., kidney, liver), and although absolute brain uptake was very low, the brain uptake that was observed was restricted to the cortex.

A Randomized Trial of Lipid Metabolism Modulation with Fenofibrate for Acute Coronavirus Disease 2019

Background Abnormal cellular lipid metabolism appears to underlie SARS-CoV-2 cytotoxicity and may involve inhibition of peroxisome proliferator activated receptor alpha (PPARα). Fenofibrate, a PPAR-α activator, modulates cellular lipid metabolism. Fenofibric acid has also been shown to affect the dimerization of angiotensin-converting enzyme 2, the cellular receptor for SARS-CoV-2. Fenofibrate and fenofibric acid have been shown to inhibit SARS-CoV-2 replication in cell culture systems in vitro . Methods We randomly assigned 701 participants with COVID-19 within 14 days of symptom onset to 145 mg of fenofibrate (nanocrystal formulation with dose adjustment for renal function or dose-equivalent preparations of micronized fenofibrate or fenofibric acid) vs. placebo for 10 days, in a double-blinded fashion. The primary endpoint was a ranked severity score in which participants were ranked across hierarchical tiers incorporating time to death, duration of mechanical ventilation, oxygenation parameters, subsequent hospitalizations and symptom severity and duration. ClinicalTrials.gov registration: NCT04517396. Findings: Mean age of participants was 49 ± 16 years, 330 (47%) were female, mean BMI was 28 ± 6 kg/m 2 , and 102 (15%) had diabetes mellitus. A total of 41 deaths occurred. Compared with placebo, fenofibrate administration had no effect on the primary endpoint. The median (interquartile range [IQR]) rank in the placebo arm was 347 (172, 453) vs. 345 (175, 453) in the fenofibrate arm (P = 0.819). There was no difference in various secondary and exploratory endpoints, including all-cause death, across randomization arms. These results were highly consistent across pre-specified sensitivity and subgroup analyses. Conclusion Among patients with COVID-19, fenofibrate has no significant effect on various clinically relevant outcomes.

A novel oncogenic role for the miRNA-506-514 cluster in initiating melanocyte transformation and promoting melanoma growth

Malignant melanoma is the most aggressive form of skin cancer and its incidence has doubled in the last two decades. It represents only 4% of skin cancer cases per year, but causes as many as 74% of skin cancer deaths. Early detection of malignant melanoma is associated with survival rates of up to 90%, but later detection (stage III to stage IV) is associated with survival rates of only 10%. Dysregulation of microRNA (miRNA) expression has been linked to tumor development and progression by functioning either as a tumor suppressor, an oncogene or a metastasis regulator in multiple cancer types. To understand the role of miRNA in the pathogenesis of malignant melanoma and identify biomarkers of metastasis, miRNA expression profiles in skin punches from 33 metastatic melanoma patients and 14 normal healthy donors were compared. We identified a cluster of 14 miRNAs on the X chromosome, termed the miR-506-514 cluster, which was consistently overexpressed in nearly all melanomas tested (30-60 fold, P<0.001), regardless of mutations in N-ras or B-raf. Inhibition of the expression of this cluster as a whole, or one of its sub-clusters (Sub-cluster A) consisting of six mature miRNAs, led to significant inhibition of cell growth, induction of apoptosis, decreased invasiveness and decreased colony formation in soft agar across multiple melanoma cell lines. Sub-cluster A of the miR-506-514 cluster was critical for maintaining the cancer phenotype, but the overexpression of the full cluster was necessary for melanocyte transformation. Our results provide new insights into the functional role of this miRNA cluster in melanoma, and suggest new approaches to treat or diagnose this disease.

Role of exogenous inositol and phosphatidylinositol in glycosylphosphatidylinositol anchor synthesis of GP49 by Giardia lamblia

Although Giardia lamblia trophozoites are unable to carry out de novo phospholipid synthesis, they can assemble complex glycophospholipids from simple lipids and fatty acids acquired from the host. Previously, we have reported that G. lamblia synthesizes GP49, an invariant surface antigen with a glycosylphosphatidylinositol (GPI) anchor. It is therefore possible that myo-inositol (Ins), phosphatidylinositol (PI) and other GPI precursors are obtained from the dietary products of the human small intestine, where the trophozoites colonize. In this report, we have investigated the role of exogenous Ins and PI on GPI anchor synthesis by G. lamblia. The results demonstrate that [(3)H]Ins and PI internalized by trophozoites, metabolically transformed into GlcN(acyl)-PI and downstream GPI molecules. Further investigations suggest that G. lamblia expresses cytidine monophosphate (CMP)-dependent (Mg(2+)-stimulated) and independent (Mn(2+)-stimulated) inositol headgroup exchange enzymes, which are responsible for exchanging free Ins with cellular PI. We observed that 3-deoxy-3-fluoro-D-myo-inositol (3-F-Ins) and 1-deoxy-1-F-scyllo-Ins (1-F-scyllo-Ins), which are considered potent inhibitors of Mn(2+)-stimulated headgroup exchange enzyme, inhibited the incorporation of [(3)H]Ins into PI and GPI molecules significantly, suggesting that CMP-independent (Mn(2+)-stimulated) exchange enzyme may be important for these reactions. However, 3-F-Ins and 1-F-scyllo-Ins were not effective in blocking the incorporation of exogenously supplied [(3)H]PI into GPI glycolipids. Thus, it can be concluded that G. lamblia can use exogenously supplied [(3)H]PI and [(3)H]Ins to synthesize GPI glycolipids of GP49; while PI is directly incorporated into GPI molecules, free Ins is first converted into PI by headgroup exchange enzymes, and this newly formed PI participates in GPI anchor synthesis.

The basic helix-loop-helix transcription factor Mist1 functions as a transcriptional repressor of myoD

A good model system to examine aspects of positive and negative transcriptional regulation is the muscle-specific regulatory factor, MyoD, which is a basic helix-loop-helix (bHLH) transcription factor. Although MyoD has the ability to induce skeletal muscle terminal differentiation in a variety of non-muscle cell types, MyoD activity itself is highly regulated through protein-protein interactions involving several different co-factors. Here we describe the characterization of a novel bHLH protein, Mist1, and how it influences MyoD function. We show that Mist1 accumulates in myogenic stem cells (myoblasts) and then decreases as myoblasts differentiate into myotubes. Mist1 functions as a negative regulator of MyoD activity, preventing muscle differentiation and the concomitant expression of muscle-specific genes. Mist1-induced inhibition occurs through a combination of mechanisms, including the formation of inactive MyoD-Mist1 heterodimers and occupancy of specific E-box target sites by Mist1 homodimers. Mist1 lacks a classic transcription activation domain and instead possesses an N-terminal repressor region capable of inhibiting heterologous activators. Thus, Mist1 may represent a new class of repressor molecules that play a role in controlling the transcriptional activity of MyoD, ensuring that expanding myoblast populations remain undifferentiated during early embryonic muscle formation.