[A preliminary study on the tear matrix metalloproteinase 9 point-of-care assay using a domestic kit]

Objective: To compare the point-of-care assays for tear matrix metalloproteinase 9 (MMP-9) using domestic and InflammaDry kits, and to evaluate the feasibility of diagnosing dry eye with the domestic kit. Methods: It was a cross-sectional study. Thirty dry eye patients and 30 age-and sex-matched normal volunteers were continuously enrolled in this cross-sectional study from June 2022 to July 2022. Both domestic and InflammaDry kits were used to detect the tear MMP-9 levels. The positive rates were recorded for qualitative analysis, and the gray ratios of bands (the gray value of detection bands to that of control bands) were collected for quantitative analysis. The correlations of MMP-9 levels with age, ocular surface disease index, fluorescence tear break-up time, tear meniscus height, Schirmer's Ⅰ test score, corneal fluorescein staining score, and meibomian gland dropout were analyzed. The Mann-Whitney U test, paired Chi-square test, Kappa test, and Spearman's correlation coefficient were used for statistical analysis. Results: There were 14 males and 16 females (30 eyes) in the control group, and their age was (39.37±19.55) years. In the dry eye group, 11 males and 19 females (30 eyes), aged (46.87±17.85) years, had moderate to severe dry eye. The positive rates of MMP-9 in tear fluid were significantly different between dry eye patients (InflammaDry: 86.67%; domestic kit: 70.00%) and controls (InflammaDry: 16.67%, P<0.001; domestic kit: 6.67%, P<0.001). Although the sensitivity of the domestic kit was lower than that of the InflammaDry kit (70.0% vs. 86.7%, P=0.001), the specificity was higher (93.3% vs. 83.3%, P=0.001). In dry eye patients, the positive coincidence rate was 80.7% (21/26), the negative coincidence rate was 100% (4/4), and the total coincidence rate was 83.3% (25/30), with no significant difference between the two kits (McNemar test: χ²=3.20, P>0.05), and the results of both kits were consistent (Kappa=0.53, P=0.001). The Spearman's correlation coefficient showed the gray ratios using both kits were positively correlated with the corneal fluorescein staining score (InflammaDry: ρ=0.48, P<0.05; domestic kit: ρ=0.52, P=0.003). Conclusion: The performances of the domestic and InflammaDry kits are consistent in the point-of-care assay for tear MMP-9, and the domestic kit has lower sensitivity but higher specificity.

Effects of epigallocatechin gallate on lipid metabolism and its underlying molecular mechanism in broiler chickens

The objective of this study was to investigate the effects of epigallocatechin gallate (EGCG) on fat metabolism and to establish the molecular mechanism of these effects in broilers. Seventy-two 28-day-old male Ross 308 broiler chickens were divided into three groups with different levels of EGCG supplementation for 4 weeks: normal control (NC) group, L-EGCG (a low-level supplement of EGCG, 40 mg/kg body weight daily) and H-EGCG (a high-level supplement of EGCG, 80 mg/kg body weight daily). After 4 weeks of oral administration, EGCG significantly reduced the level of abdominal fat deposition in broilers. The serum triglycerides and low-density lipoprotein cholesterol of chickens in H-EGCG group were also significantly decreased compared with the NC group, and the high-density lipoprotein cholesterol was notably increased at the same time. Moreover, the vital role of the liver and abdominal adipose tissue in lipid metabolism of poultry animals was examined through gene expression and enzyme activities related to fat anabolism and catabolism in these organs. Our data show that EGCG supplementation for 2 weeks significantly downregulated the expression of fatty acid synthesis and fat deposition-related genes, and upregulated the expression of genes involved in fatty acid β-oxidation and lipolysis genes. Simultaneously, the activities of hepatic fatty acid synthesis enzymes (fatty acid synthase and acetyl CoA carboxylase) were significantly decreased, and the activity of carnitine palmitoyl transferase-1 was notably elevated. The results suggest that EGCG could alleviate fat deposition in broilers through inhibiting fat anabolism and stimulating lipid catabolism in broilers.

[Research progresses on signal transduction of neurotrophins]

Binding of neurotrophins and their receptors lead to dimerization and autophosphorylation of trks. Activated trkA initiates the Ras pathway and finally opens the transcriptions of immediate early genes and delayed response genes or participates directly in physiological responses. Target-derived neurotrophins bind to and induce phosphorylation of trk receptors at the axonal terminal. Active trk or NT-trk or other signal molecules can be retrogradely transported along the axon to transduct messages to neuronal nucleus. There are local autocrine and paracrine mechanisms besides target-derived NTs. Following nervous system injury, increased gene expressions of NTs and their receptors and increased retrograde axonal transport are helpful to survive and regenerate for injured neurons. Lacking NTs and their receptors will result in serious abnormal development of nervous system of mice.

Cytoarchitecture and dendroarchitecture of sympathoadrenal preganglionic neurons in rats--a study with CB-HRP

The cytoarchitecture and dendroarchitecture of sympathoadrenal preganglionic neurons (SAPN) that innervate the adrenal medulla have been studied in adult rats. Retrograde transport of choleragen subunit B horseradish peroxidase conjugate (CB-HRP) injected into the left adrenal medulla resulted in the labelling of SAPN in the ipsilateral intermediate zone from T1 to L1 segments. Four subnuclei of SAPN were distinguished and located in ILP, ILF, IC and ICPe of the spinal cord respectively. The dendritic trees of neurons in ILP exhibited dendritic patterns with extension oriented longitudinally and mediolaterally. The present findings provide detailed descriptions of the somatic structure and accompanying dendritic trees of SAPN. The observation also include anatomical evidence that two systems of circuits may exist in regulating the activities of SAPN; one is the classic core circuits system which mainly received the inputs from fibers in parallel direction with longitudinal dendrites in ILP and the other is the paralateral circuits system which chiefly received the inputs from fibers in perpendicular direction with radial dendrites in white matter.

Improvement of the tetramethyl benzidine reaction with ammonium molybdate as a stabilizer for light and electron microscopic ligand-HRP neurohistochemistry, immunocytochemistry and double-labelling

Ammonium heptamolybdate (AHM) was used as a stabilizing agent in the tetramethyl benzidine (TMB) reaction of choleragen subunit B conjugated horseradish peroxidase (CB-HRP) neurohistochemistry (TMB-AHM method). In comparison with Mesulam's TMB method employing sodium nitroprusside as a stabilizing agent (TMB-SNP method), the TMB-AHM procedure offers a similar sensitivity with regard to the visualization of CB-HRP labelled neurons and their extranuclear Golgi-phobic dendrites. However, it is less sensitive for the demonstration of anterogradely transported CB-HRP in axon terminals. At the nearly physiological pH value of the reaction medium (pH 6-8), it demonstrates better preservation of tissue and cell structures in the reacted sections. Under the electron microscope, the specific reaction product can be clearly distinguished and little damage of cellular and subcellular structures occurred. Preliminary application of TMB-AHM method to choleragen subunit B (CB) immunocytochemistry and double labelling technique which paired the neuronal tracing methods of HRP neurohistochemistry and CB immunocytochemistry, was also carried out with small modification.

[Ammonium molybdate as stabilizing agent in tetramethyl benzidine reaction of CB-HRP neurohistochemistry and its application to electron microscopy and immunocytochemistry]

Ammonium molybdate (AHM) was used as a stabilizing agent in the tetramethyl benzidine (TMB) reaction of choleragen subunit B conjugated horseradish peroxidase (CB-HRP) neurohistochemistry. In comparison with Mesulam's TMB method using sodium nitroprusside (SNP) as stabilizing agent, this new stabilizer offers similar sensitivity in regard to visualization of CB-HRP labelled neurons and their extranuclear Golgi-phobic dendrites. The nearly physiological pH (6-8) of the reaction medium demonstrates better preservation of tissue and cell structures of reacted sections and avoids non-specific needle-like crystal formation. Under the electron microscope, the histochemical reaction products can be clearly distinguished, without the usual shrinkage or distention of cellular and subcellular structures. This method was also applied with success to immunocytochemistry through small modifications.

Cholera toxin and wheat germ agglutinin conjugates as neuroanatomical probes: their uptake and clearance, transganglionic and retrograde transport and sensitivity

Horseradish peroxidase (HRP) conjugates of 6 different lectins and cholera toxin (CTHRP) were quantitatively compared with respect to: (a) their behavior at the injection site and (b) their ability to label, by means of transganglionic and retrograde axonal transport, axon terminals and neurons in the medulla of the rat subsequent to injections of each probe into the anterior two thirds of the tongue. HRP conjugates of wheat germ agglutinin (WGHRP) and CTHRP were more sensitive than any of the other lectin-HRP conjugates. Both were far superior to free-HRP (FHRP) in demonstrating these projections and CTHRP was the most sensitive transganglionic and retrograde probe. Additional experiments demonstrated that this superiority was not an artifact of the volume of material injected into the tongue nor of the injection site area or survival time selection. These experiments demonstrated further that CTHRP and WGHRP remain at the injection site approximately twice as long as FHRP and that their removal from or degradation in retrogradely labeled neurons requires approximately twice as much time as that required for FHRP. These observations, together with earlier studies from this laboratory, suggest the following conclusions: (1) CTHRP and WGHRP are superior in sensitivity to FHRP for studies of neuronal connectivity; and (2) HRP conjugates of ligands such as CTHRP and WGHRP are internalized, transported and/or degraded by mammalian neurons in a manner which differs from that of FHRP, a macromolecule for which neuronal plasma membrane 'receptors' are lacking.

Double superior venae cavae associated with aberrant subclavian artery--the atavistic and transitional nature of "proximal loss" aortic arch

A case of double superior venae cavae (Bvc) associated with bilateral azygos veins (Baz), aberrant subclavian artery (Sa) and other rare variations is recorded in a two-year-old Chinese girl with an unknown cause of death. A review of the literature since 1844 indicates that there has been no reported case of a right Sa associated with Bvc + Baz. The primitive arrangement of the thoracic large vessels in this case (Bvc + Baz and CHim type of aortic branches) substantiates the atavistic nature of Sa. The proximal loss pattern (PLdp) of the aortic arch with its associated Bvc + Baz was a primitive transitional link between the vascular arrangement of the Mesozoic reptilian and that of mammals or avians. According to this concept, there should be an occurrence of the PLdp variation (i.e. Sa) in all the mammals and avians and an occurrence of the 1-, 2- or 6-branch type of PLdp in human beings or in other animals.