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493 result(s) for "Schmidt, Heinrich"
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Identification of Key Enzymes for Pectin Synthesis in Seed Mucilage
Pectin is a vital component of the plant cell wall and provides the molecular glue that maintains cell-cell adhesion, among other functions. As the most complex wall polysaccharide, pectin is composed of several covalently linked domains, such as homogalacturonan (HG) and rhamnogalacturonan I (RG I). Pectin has widespread uses in the food industry and has emerging biomedical applications, but its synthesis remains poorly understood. For instance, the enzymes that catalyze RG I elongation remain unknown. Recently, a coexpression- and sequence-based MUCILAGE-RELATED (MUCI) reverse genetic screen uncovered hemicellulose biosynthetic enzymes in the Arabidopsis (Arabidopsis thaliana) seed coat. Here, we use an extension of this strategy to identify MUCI70 as the founding member of a glycosyltransferase family essential for the accumulation of seed mucilage, a gelatinous wall rich in unbranched RG I. Detailed biochemical and histological characterization of two muci70 mutants and two galacturonosyltransferase11 (gaut11) mutants identified MUCI70 and GAUT11 as required for two distinct RG I domains in seed mucilage. We demonstrate that, unlike MUCI70, GAUT11 catalyzes HG elongation in vitro and, thus, likely is required for the synthesis of an HG region important for RG I elongation. Analysis of a muci70 gaut11 double mutant confirmed that MUCI70 and GAUT11 are indispensable for the production and release of the bulk of mucilage RG I and for shaping the surface morphology of seeds. In addition, we uncover relationships between pectin and hemicelluloses and show that xylan is essential for the elongation of at least one RG I domain.
Chromatin-remodeling factor SMARCD2 regulates transcriptional networks controlling differentiation of neutrophil granulocytes
Christoph Klein and colleagues identify loss-of-function mutations in SMARCD2 ( BAF60b ) that lead to neutropenia, specific granule deficiency and myelodysplasia. They show that SMARCD2 controls differentiation of myeloid–erythroid progenitor cells through interaction with CEBPɛ and that reduced SMARCD2 levels cause transcription and chromatin alterations in acute myeloid leukemia cells. We identify SMARCD2 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily D, member 2), also known as BAF60b (BRG1/Brahma-associated factor 60b), as a critical regulator of myeloid differentiation in humans, mice, and zebrafish. Studying patients from three unrelated pedigrees characterized by neutropenia, specific granule deficiency, myelodysplasia with excess of blast cells, and various developmental aberrations, we identified three homozygous loss-of-function mutations in SMARCD2 . Using mice and zebrafish as model systems, we showed that SMARCD2 controls early steps in the differentiation of myeloid–erythroid progenitor cells. In vitro , SMARCD2 interacts with the transcription factor CEBPɛ and controls expression of neutrophil proteins stored in specific granules. Defective expression of SMARCD2 leads to transcriptional and chromatin changes in acute myeloid leukemia (AML) human promyelocytic cells. In summary, SMARCD2 is a key factor controlling myelopoiesis and is a potential tumor suppressor in leukemia.
Chromosome-level genome assemblies of Thai cassava ecotypes (Manihot esculenta & Manihot glaziovii)
Cassava is a vital staple crop, yet genomic resources for diverse ecotypes, particularly from key regions, remain limited. To address this, we generated high-quality genome assemblies for nine Thai M. esculenta cultivars and one wild relative, Manihot glaziovii . The sequencing strategy combined Oxford Nanopore long reads for initial assembly with Illumina short reads for polishing and quality assessment. For five of the genotypes, extensive RNA-Seq data from various tissues and developmental stages were also produced to guide gene annotation. We provide detailed technical validation of the ten genome assemblies, reporting on key metrics of contiguity (N50s from 28.9 to 35.2 Mb), completeness (Complete BUSCO scores from 95.69% to 99.21%), and base-level accuracy ( k -mer QV scores from 33.47 to 37.67). The final annotated assemblies and all raw sequencing data have been deposited in public archives and are readily accessible. These datasets represent a significant expansion of the genomic toolkit for Asian cassava, providing a foundational resource for future genetic discovery, comparative genomics, and advanced breeding applications.
Hypercalcaemia after treatment with denosumab in children: bisphosphonates as an option for therapy and prevention?
Background Pharmacologic options for treatment of osteolytic diseases especially in children are limited. Although not licensed for use, denosumab, a fully humanized antibody to RANKL, is used in children with good effects. Among others, one possible indication are giant cell tumors and aneurysmatic bone cysts. However, there are reports of severe hypercalcemia during weeks to months after termination of denosumab, that are rarely seen in adults. Methods We collected data of four patients, aged 6–17 years, who experienced severe hypercalcemia after completion of treatment with denosumab for unresectable giant cell tumors of bone or aneurysmal bone cysts and methods of their treatment. The detailed case information were described. Results One patient was treated with long-term, high-dose steroid therapy, leading to typical Cushing’s syndrome. Another patient was restarted on denosumab repeatedly due to relapses of hypercalcemia after every stop. Finally, in two patients, hypercalcemia ceased definitely after treatment with bisphosphonates. However, several applications were necessary to stabilize calcium levels. Conclusions There is a considerable risk of hypercalcemia as an adverse effect after denosumab treatment in children. Therapeutic and, preferably, preventive strategies are needed. Bisphosphonates seem to be an option for both, but effective proceedings still remain to be established.
MCT8 Deficiency in Infancy: Opportunities for Early Diagnosis and Screening
Background: Monocarboxylate-transporter-8-(MCT8) deficiency, or Allan–Herndon–Dudley syndrome (AHDS), is a rare X-linked disorder caused by pathogenic variants in the SLC16A2 gene, leading to impaired transport of thyroid hormones, primarily T3 and T4, across cell membranes. The resulting central hypothyroidism and peripheral hyperthyroidism cause neurodevelopmental impairment and thyrotoxicosis. Despite the availability of therapy options, e.g., with triiodothyroacetic acid (TRIAC), diagnosis is often delayed, partly due to normal TSH levels or incomplete genetic panels. MCT8 deficiency is not yet included in newborn-screening programs worldwide. Case Description: We present a case of an infant genetically diagnosed with MCT8 deficiency at 5 months of age after presenting with muscular hypotonia, lack of head control, and developmental delay. Thyroid function testing revealed a normal TSH, low free T4, and significantly elevated free T3 and free T3/T4 ratio. Treatment with TRIAC (Emcitate®) was initiated promptly, with close drug monitoring. Despite persistent motor deficits and dystonia, some developmental progress was observed, as well as reduction in hyperthyroidism. Discussion/Conclusions: This case underscores the importance of early free T3 and fT3/fT4 ratio testing in infants with unexplained developmental delay. Broader inclusion of SLC16A2 in genetic panels and consideration of newborn screening could improve early diagnosis and outcomes in this rare but treatable condition.
Cortisol response in children with cancer and fever during chemotherapy: A prospective, observational study using random serum cortisol levels
Background Glucocorticoids are crucial components of the treatment of leukemia and lymphoma. High doses can lead to suppression of the hypothalamic–pituitary–adrenal (HPA) axis and be causative for an impaired stress response during infection. This study aims to evaluate the cortisol response in pediatric oncologic patients during febrile episodes. Methods Totally, 75 children and adolescents (5 months—18 years) with fever during chemotherapy were consecutively enrolled in this study. In total, 47 patients received glucocorticoids as part of their treatment. Random serum cortisol and adrenocorticotropic hormone (ACTH) were analyzed in every patient. A low cortisol response (LCR) was defined as a cortisol level < 14.6 μg/dL. Results In total, 52 (69%) patients had a cortisol level < 14.6 μg/dL during fever. There was no significant difference between patients who received glucocorticoids and those who did not. Significantly lower cortisol levels were measured ≤7 days after last glucocorticoid intake compared to later time points. Nearly all patients treated with dexamethasone or prophylactic posaconazole demonstrated a LCR under stress (fever). Conclusion The incidence of an impaired HPA axis in pediatric cancer patients might be underestimated since 69% of the children in our study had a LCR during fever. Intake of dexamethasone, posaconazole and a time period of ≤7 days from the last glucocorticoid intake were additional risk factors for an LCR. However, we could not confirm that patients with a LCR fared worse than patients with a high cortisol response (HCR). Therefore, a different cortisol threshold may be necessary for defining an impaired HPA axis in febrile oncologic patients without concomitant symptoms of AI. The adrenal gland's response to stress is impaired in most pediatric cancer patients receiving chemotherapy, whether or not they are taking steroids. Intake of dexamethasone and posaconazole and a time period of ≤7 days from the last glucocorticoid intake were additional risk factors for an impaired adrenal response.
Long-Term Course of Hypothyroidism Detected through Neonatal TSH Screening in a Population-Based Cohort of Very Preterm Infants Born at Less than 32 Weeks of Gestation
After several decades of successful newborn screening (NBS) for congenital hypothyroidism, the optimal hypothyroidism NBS algorithm for very preterm infants is still controversial. Due to concerns about an elevated risk of a false-negative initial thyroid-stimulation hormone (TSH) screening, repeat NBS has been implemented for this group. While transient hypothyroidism is known to be more frequent among very preterm infants, the prevalence of permanent hypothyroidism is generally assumed to be the same as in more mature newborns. This study analyses screening and long-term follow-up data from the population-based cohort of 51 infants born from 1999–2017 at less than 32 weeks of gestation and diagnosed with hypothyroidism after NBS in the German Federal State of Bavaria (total number of infants screened 2,107,864). Severe permanent hypothyroidism was always detected at initial TSH screening unless there was a known confounding factor. Cases detected by repeat screening after a negative initial screen most frequently proved to be transient, less frequently mild permanent, or a definitive diagnosis was not possible because of inadequate re-evaluation of the thyroid axis. The prevalence of both permanent and transient hypothyroidism was elevated compared to a cohort of children from the same region born at a higher gestational age. The results seem to support the need for the repeated NBS of very preterm infants. However, as the recommendation to treat mild hypothyroidism is not based on high quality evidence, important issues for future research include treatment outcome studies or even a general review of whether this diagnosis meets the screening criteria. Meanwhile, involving a paediatric endocrinologist in treatment decisions is crucial for optimising the benefit of hypothyroidism screening for this particularly vulnerable group.
Continuous Glucose Monitoring in Children and Adolescents with Congenital Adrenal Hyperplasia
Patients with congenital adrenal hyperplasia require lifelong therapy with glucocorticoids to suppress androgen excess and substitute for deficient cortisol. An important aspect of care is the prevention of metabolic sequelae. In infants, potentially lethal nocturnal hypoglycaemia has been described. In adolescence, visceral obesity, hypertension, hyperinsulinism and insulin resistance come into focus. To date, systematic studies of glucose profiles are lacking. We conducted a monocentric prospective observational study to determine the glucose profiles under different treatment regimens. We used the latest generation FreeStyle Libre 3® sensor in blinded mode as a device for CGM. Furthermore, therapeutic/ auxological data were obtained. Our cohort of 10 children/ adolescents had a mean age of 11 years. Three patients showed morning fasting hyperglycaemia. Overall, 6 out of 10 patients had too little total values in the desired range of 70-120 mg/dl. Tissue glucose values above 140-180 mg/dl were found in 5 of 10 patients. All patients had an average value for glycosylated haemoglobin of 5.8 %. All pubertal adolescents with reverse circadian regimens had significantly higher glucose levels at night. Two adolescents showed asymptomatic nocturnal hypoglycaemia. A high number of subjects showed abnormalities in glucose metabolism. Two-thirds had elevated total 24h glucose values outside the age-appropriate reference values. Thus, this aspect may need to be addressed early in life by adjusting the doses, treatment regimen or dietary measures. Consequently, reverse circadian therapy regimens should be critically indicated and closely monitored due to the potential metabolic risk.
Extensive Natural Variation in Arabidopsis Seed Mucilage Structure
Hydrated Arabidopsis thaliana seeds are coated by a gelatinous layer called mucilage, which is mainly composed of cell wall polysaccharides. Since mucilage is rich in pectin, its architecture can be visualized with the ruthenium red (RR) dye. We screened the seeds of around 280 Arabidopsis natural accessions for variation in mucilage structure, and identified a large number of novel variants that differed from the Col-0 wild-type. Most of the accessions released smaller RR-stained capsules compared to the Col-0 reference. By biochemically characterizing the phenotypes of 25 of these accessions in greater detail, we discovered that distinct changes in polysaccharide structure resulted in gelatinous coatings with a deceptively similar appearance. Monosaccharide composition analysis of total mucilage extracts revealed a remarkable variation (from 50 to 200% of Col-0 levels) in the content of galactose and mannose, which are important subunits of heteromannan. In addition, most of the natural variants had altered Pontamine Fast Scarlet 4B staining of cellulose and significantly reduced birefringence of crystalline structures. This indicates that the production or organization of cellulose may be affected by the presence of different amounts of hemicellulose. Although, the accessions described in this study were primarily collected from Western Europe, they form five different phenotypic classes based on the combined results of our experiments. This suggests that polymorphisms at multiple loci are likely responsible for the observed mucilage structure. The transcription of MUCILAGE-RELATED10 (MUCI10), which encodes a key enzyme for galactoglucomannan synthesis, was severely reduced in multiple variants that phenocopied the muci10-1 insertion mutant. Although, we could not pinpoint any causal polymorphisms in this gene, constitutive expression of fluorescently-tagged MUCI10 proteins complemented the mucilage defects of a muci10-like accession. This leads us to hypothesize that some accessions might disrupt a transcriptional regulator of MUCI10. Therefore, this collection of publicly-available variants should provide insight into plant cell wall organization and facilitate the discovery of genes that regulate polysaccharide biosynthesis.
The effect of cardiovascular risk factors on the longitudinal evolution of the carotid intima medial thickness in children with type 1 diabetes mellitus
Background Type 1 diabetes mellitus is a generally accepted atherogenic risk factor. The aim of this prospective longitudinal study was to evaluate changes in carotid intima media thickness (cIMT) in children and adolescents with type 1 diabetes mellitus (T1DM) using standardized methods. Methods We re-evaluated cIMT in 70 (38 f) of initial 150 (80 f) patients with T1DM after 4 years. At re-evaluation, mean (± SD) age was 16.45 ± 2.59 y, mean diabetes duration was 9.2 ± 3.24 y and patients had a mean HbA1c of 8.14 ± 1.06%. Results Mean cIMT z-scores increased significantly during 4 years (0.58 ± 0.75, p < 0.001) as well as BMI-z-score (0.41 ± 0.81, p < 0.01), systolic blood pressure (0.77 ± 1.15, p < 0.01) and HbA1c (0.90 ± 1.07, < 0.001). In a linear regression model systolic blood pressure z-score at first measurement (0.02, CI: 0.01, 0.04) was a significant predictor for the mean effect on cIMT z-score. In a logistic regression model significant risk factors for an increase in IMT of ≥1.5 z-scores were BMI z-scores (OR: 3.02, CI:1.11, 10.14), diabetes duration (OR:1.32, CI:1.04, 1.77) and systolic blood pressure (OR: 1.14, CI: 1.04, 1.27) at first measurement each. Conclusions Longitudinal cIMT measurements revealed progression in subclinical atherosclerosis during a four year period in diabetic children and adolescents. Systolic blood pressure and BMI were related to cIMT increment. Control of these risk factors by lifestyle and medical intervention may prevent progression of cIMT in diabetic children.