Flow-regulated lymphatic vasculature development and signaling

The role of blood flow in regulating signaling pathways and gene expression in the blood vasculature is well known. Recent studies have identified equally important roles of flow-mediated signaling in the lymphatic circulation including control of lymphatic vascular growth, remodeling, regeneration and maintenance of the lymphatic fate. In this review, we summarize these advances focusing on the role of fluid dynamics in control of lymphatic vasculature formation

The value of luteinizing hormone basal values and sex hormone-binding globulin for early diagnosis of rapidly progressive central precocious puberty

ObjectiveThis study aimed to investigate the diagnostic value of luteinizing hormone (LH) basal values and sex hormone-binding globulin (SHBG) for rapidly progressive central precocious puberty (RP-CPP).MethodsA total of 121 girls presenting with secondary sexual characteristics were selected from the Department of Pediatric Endocrinology, Lianyungang Clinical Medical College of Nanjing Medical University, from May 2021 to June 2023. The children were followed up for 6 months and were divided into three groups: RP-CPP group (n=40), slowly progressive central precocious puberty (SP-CPP) group (n=40), and premature thelarche (PT) group (n=41). The differences in LH basal values and SHBG among girls in the three groups were compared. ROC curves were drawn to analyze the value of LH basal values and SHBG in identifying RP-CPP.ResultsSignificant differences were observed in age, height, predicted adult height (PAH), weight, body mass index (BMI), bone age (BA), BA-chronological age (CA), LH basal, LH peak, FSH basal, LH peak/FSH peak, estradiol (E2), testosterone, and SHBG levels between the RP-CPP group and the SP-CPP and PT groups (P < 0.05). The LH basal value in the RP-CPP group was higher than that in the SP-CPP group and the PT group, while SHBG levels were lower than in the latter two groups, and these differences were statistically significant (P < 0.05). When the LH basal value was ≥0.58 IU/L and SHBG was ≤58.79 nmol/L, the sensitivity for diagnosing RP-CPP was 77.5% and 67.5%, and the specificity was 66.7% and 74.1%.ConclusionDetection of basal LH and SHBG levels allows for early diagnosis of the progression of central precocious puberty

Ignition characteristics of dual-fuel methane-n-hexane-oxygen-diluent mixtures in a rapid compression machine and a shock tube

Ignition delay times of methane-n-hexane-oxygen-dulent mixtures were studied experimentally and numerically in a wide temperature range (640–2335 K) using both a rapid compression machine (RCM) and a shock tube (ST). The RCM results demonstrated a two-stage ignition and negative temperature coefficient (NTC) behavior. Increasing n-hexane concentration, pressure and equivalence ratio shortened the ignition delay time. For the ST experiments, the addition of 10% n-hexane (relative to methane) can reduce the ignition delay time dramatically. However, no further reduction effect can be achieved with increasing addition of n-hexane from 10% to 20%. In addition, increasing equivalence ratio reduces the effect of n-hexane addition on ignition delay time. Three detailed chemical mechanisms, CaltechMech, GalwayMech and LLNLMech, were evaluated based on a quantitative error analysis. LLNLMech and CaltechMech demonstrated the best performance in the RCM and ST temperature ranges, respectively. Chemical kinetic analyses showed that the addition of n-hexane to methane provides some chemical pathways not available for methane oxidation which result in the production of active radicals and eventually accelerate the ignition of the methane-oxygen mixtures. The crucial intermediate species for the ignition process are H_2O_2 and H under RCM and ST conditions, respectively

Syndecan-4 controls lymphatic vasculature remodeling during embryonic development

The role of fluid shear stress in vasculature development and remodeling is well appreciated. However, the mechanisms regulating these effects remain elusive. We show that abnormal flow sensing in lymphatic endothelial cells (LECs) caused by Sdc4 or Pecam1 deletion in mice results in impaired lymphatic vessel remodeling, including abnormal valve morphogenesis. Ablation of either gene leads to the formation of irregular, enlarged and excessively branched lymphatic vessels. In both cases, lymphatic valve-forming endothelial cells are randomly oriented, resulting in the formation of abnormal valves. These abnormalities are much more pronounced in Sdc4(-/-); Pecam1(-/-) double-knockout mice, which develop severe edema. In vitro, SDC4 knockdown human LECs fail to align under flow and exhibit high expression of the planar cell polarity protein VANGL2. Reducing VANGL2 levels in SDC4 knockdown LECs restores their alignment under flow, while VANGL2 overexpression in wild-type LECs mimics the flow alignment abnormalities seen in SDC4 knockdown LECs. SDC4 thus controls flow-induced LEC polarization via regulation of VANGL2 expression.info:eu-repo/semantics/publishe

Synthesis, characterization and growing mechanism of monodisperse Fe3O4 microspheres

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