Objective To investigate the morphological changes in the sciatic nerve and the dorsal root ganglions (DRGs) and also gene expression in DRGs after non-freezing cold injury, and to explore the molecular mechanism of peripheral nerve cold injury and regeneration. Methods Twenty-four male Wistar rats were used. The sciatic nerve on one side was cooled to 4℃ for 2 h, and the sciatic nerve on the opposite side was exposed, but without cooling. Sciatic nerves and L4, L5 and L6 DRGs from both sides were harvested at the 1st, 2nd and 3rd week after cooling. Any pathological changes were observed using light and electron microscopy. Laser capture microdissection (LCM) was used to investigate the DRG neurons' gene expression. The array result was verified with RT-PCR for eight genes. Results Large fiber degeneration was obvious by the 7th day after cooling. Myelinated fiber regeneration had begun by the 14th day, so this time was chosen to explore the neurons' gene expression. Ninety-six genes and expressed sequence tags (ESTs) were up-regulated greater than 2 fold. Their proteins' functions were classified as adaptive response to external stimulus, apoptosis regulation, cell adhesion, immune and inflammation response,nerve regeneration, pain associated molecules, microtubule cytoskeleton, ion-channels, neurotransmitters and receptors, and neuropeptides. Conclusions A complex molecular mechanism is involved in cold injury and regeneration of the sciatic nerve, and many genes are involved. Large scale microarray analysis is a potent means to screen out related genes, thus suggesting future repair strategies.

BACKGROUND:Kidney deficiency and blood stasis syndrome are common traditional Chinese medicine syndromes observed in knee osteoarthritis,which serve as fundamental pathogenesis factors.There exists a significant connection between the two.Previous studies have demonstrated that kidney deficiency and blood stasis syndrome effectively contribute to knee joint cartilage degeneration and the progression of knee osteoarthritis.However,the mechanisms underlying the promotion of knee joint cartilage damage remain unclear and require further investigation. OBJECTIVE:To investigate the influence of kidney deficiency and blood stasis syndrome on the progression of knee osteoarthritis in Sprague-Dawley rats. METHODS:Sixteen Sprague-Dawley rats were randomly divided into two groups:a model observation group and a control group,with eight rats in each group.Animal models of kidney deficiency were induced by ovary removal in the model observation group,while the control group was given a sham procedure for ovarian removal.Two months after modeling,both groups underwent modified HULTH surgery to induce knee osteoarthritis.One week after modified HULTH surgery,the model observation group was subcutaneously given adrenaline hydrochloride to make blood stasis models,while the control group was subcutaneously given normal saline.At the 5th week after modified HULTH surgery,blood rheology,coagulation parameters,triiodothyronine,tetraiodothyronine,and estradiol levels were measured.Knee joint X-ray images were taken,and knee joint sections were stained with safranin O-fast green,hematoxylin-eosin,and immunohistochemistry. RESULTS AND CONCLUSION:Compared with the control group,the model observation group exhibited significant increases in whole blood viscosity at low,medium,and high shear rates,as well as increased plasma viscosity.Fibronectin levels in the coagulation parameters were significantly increased,while prothrombin time and activated partial thromboplastin time were significantly decreased.Triiodothyronine,tetraiodothyronine,and estradiol levels were all significantly decreased.Radiographic results showed that the model observation group exhibited more severe degree of knee joint space narrowing and surface roughness,with the appearance of high-density shadows.Hematoxylin-eosin and safranin O-fast green staining demonstrated more severe cartilage damage in the model observation group,with significantly higher OARSI and Mankin scores compared with the control group.Compared with the control group,immunohistochemistry results showed a significant reduction in the expression of extracellular matrix type II collagen and aggrecan protein in the cartilage of the model observation group rats.Moreover,there was a significant increase in the expression of matrix metalloproteinase 13 and aggrecanase 5,which are inflammatory factors.These results indicate that the Sprague-Dawley rat model of knee osteoarthritis with kidney deficiency and blood stasis was successfully established.Kidney deficiency and blood stasis syndrome further aggravate cartilage extracellular matrix degradation and cartilage degeneration by promoting the expression of inflammatory factors,thereby promoting the progression of knee osteoarthritis in rats.

Presynaptic dopaminergic PET imaging is a useful method for the diagnosis of parkinsonism. Based on the expert consensus on operation and clinical application of dopamine transporter brain PET imaging technology published in 2020, this paper further recommends the relevant elements of result interpretation of presynaptic dopaminergic PET imaging.