Nanochannels Photoelectrochemical Biosensor.

Nanochannels have brought new opportunities for biosensor development. Herein, we present the novel concept of a nanochannels photoelectrochemical (PEC) biosensor based on the integration of a unique CuxO-nanopyramid-islands (NPIs) photocathode, an anodic aluminum oxide (AAO) membrane, and alkaline phosphatase (ALP) catalytic chemistry. The CuxO-NPIs photocathode possesses good performance, and further assembly with AAO yields a designed architecture composed of vertically aligned, highly ordered nanoarrays on top of the CuxO-NPIs film. After biocatalytic precipitation (BCP) was stimulated within the channels, the biosensor was used for the successful detection of ALP activity. This study has not only provided a novel paradigm for an unconventional nanochannels PEC biosensor, which can be used for general bioanalytical purposes, but also indicated that the new concept of nanochannel-semiconductor heterostructures is a step toward innovative biomedical applications.

Neurosubstrates and mechanisms underlying the extinction of associative motor memory.

Eyeblink conditioning is one of the most commonly used model systems to investigate the neural mechanisms underlying associative motor learning. It is well established that the acquisition and retention of conditioned eyeblink responses (CRs) involve neural plasticity in both the cerebellar cortex and deep cerebellar nuclei (DCN). Nevertheless, how learned CRs are extinguished remains relatively unclear. It has been suggested that extinguished CRs can recur spontaneously, can reappear by exposure to certain stimuli, and can be reacquired in fewer training trials than originally needed, indicating that associative motor memory is not merely erased by extinction training. Instead, the motor memory is preserved to some degree. Herein, we reviewed recent experimental findings demonstrating that the cerebellum subserves the preservation of learned CRs. In addition, several lines of evidence have suggested that forebrain structures (i.e., the medial prefrontal cortex and hippocampus) are involved in the CR extinction. We proposed possible mechanisms related to how preserved motor memory in the cerebellum is inhibited by the forebrain structures via the amygdalar complex.

Dietary steroids promote body weight growth and induce gametogenesis by increasing the expressions of genes related to cell proliferation of sea cucumber (Apostichopus japonicus).

Steroids play a vital role in animal survival, promoting growth and development when administered appropriate concentration exogenously. However, it remains unclear whether steroids can induce gonadal development and the underlying mechanism. This study assessed sea cucumber weights post-culturing, employing paraffin sections and RNA sequencing (RNA-seq) to explore gonadal changes and gene expression in response to exogenous steroid addition. Testosterone and cholesterol, dissolved in absolute ethanol, were incorporated into sea cucumber diets. After 30 days, testosterone and cholesterol significantly increased sea cucumber weights, with the total weight of experimental groups surpassing the control. The testosterone-fed group exhibited significantly higher eviscerated weight than the control group. In addition, dietary steroids influenced gonad morphology and upregulated genes related to cell proliferation，such as RPL35, PC, eLF-1, MPC2, ADCY10 and CYP2C18. Thees upregulated differentially expressed genes were significantly enriched in the organic system, metabolism, genetic information and environmental information categories. These findings imply that steroids may contribute to the growth and the process of genetic information translation and protein synthesis essential for gonadal development and gametogenesis.

Mediating effects of insomnia and resilience on COVID-19-related post-traumatic stress disorder and quality of life in adolescents.

The coronavirus disease-2019 (COVID-19) pandemic has impaired the quality of life (QoL) for many due to its extensive impacts. However, few studies have addressed the specific impact of COVID-19 on the mental health of adolescents, particularly post-traumatic stress disorder (PTSD). This study considered the impact of COVID-19-related PTSD on the QoL of adolescents in China, the mediating effects of insomnia, and the moderating effects of resilience. Participants included 50,666 adolescents aged 12-18 years selected using a comprehensive sampling method. We performed data collection from January 8th to January 18th, 2023, using the Children's Revised Impact of Event Scale, Pittsburgh Sleep Quality Index, Ten-item Connor-Davidson Resilience Scale, and Screening for and Promotion of Health-related QoL in Children and Adolescents Questionnaire for data collection. Male adolescents exhibited significantly lower levels of PTSD and insomnia compared to females and scored significantly higher in psychological resilience and overall QoL. Insomnia played a mediating role between PTSD and QoL. Psychological resilience moderated the impact of COVID-19-related stress on adolescents' QoL through its influence on insomnia. PTSD resulting from the COVID-19 pandemic affects the QoL of adolescents through the presence of insomnia. Psychological resilience plays a moderating role in this process. Cultivating psychological resilience in adolescents can effectively enhance their ability to cope with the impacts of sudden public events.

Lung adenocarcinoma metastatic to the ovary: a retrospective clinicopathological analysis of 17 cases and literature review.

Lung adenocarcinoma metastatic to the ovary is rarely detected in clinical practice, and only a few cases have been reported. Its clinicopathological features, molecular genetics, and prognosis have not been well characterised. The data of 17 patients diagnosed with this disease between 2013 and 2022 were analysed retrospectively. All patients were non-smokers, with a median age of 46 years (range 30-71 years). Unilateral ovarian involvement was more frequent than bilateral involvement (58.8% vs 41.2%). Lesions presented as solid ovarian or mixed cystic and solid masses, and nearly two-thirds of the tumours (11/17, 64.7%) had a diameter greater than 10 cm. Solid adenocarcinoma was the most common histological subtype (9/17, 52.9%), and three of the cases showed abundant intracellular mucin and signet ring cells. Acinar adenocarcinoma was the second most common type (6/17, 35.3%), usually of moderate to poor differentiation. The remaining two cases were identified as micropapillary adenocarcinoma and mucinous adenocarcinoma. Multinodular growth, necrosis, and lymphovascular invasion were observed in half of the cases, and most of them had a marked stromal response. The most prevalent molecular alteration was ALK-rearranged (8/17, 47.1%), followed by EGFR gene mutations (5/17, 29.4%). A total of 34 cases, comprising 17 from the cohort and 17 from the literature, were included in the survival analysis. Patients with ALK-rearranged genes demonstrated an 80.0% 2-year overall survival rate, whereas those without ALK rearrangement exhibited a lower rate of 33.7%. Although there appears to be a potentially better prognosis for patients with ALK-rearranged genes, further cases and an extended follow-up period are necessary to substantiate this observation.

Duodenal-jejunal bypass improves hypothalamic oxidative stress and inflammation in diabetic rats via glucagon-like peptide 1-mediated Nrf2/HO-1 signaling.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is often accompanied by impaired glucose utilization in the brain, leading to oxidative stress, neuronal cell injury and infla-mmation. Previous studies have shown that duodenal jejunal bypass (DJB) surgery significantly improves brain glucose metabolism in T2DM rats, the role and the metabolism of DJB in improving brain oxidative stress and inflammation condition in T2DM rats remain unclear. AIM: To investigate the role and metabolism of DJB in improving hypothalamic oxidative stress and inflammation condition in T2DM rats. METHODS: A T2DM rat model was induced via a high-glucose and high-fat diet, combined with a low-dose streptozotocin injection. T2DM rats were divided into DJB operation and Sham operation groups. DJB surgical intervention was carried out on T2DM rats. The differential expression of hypothalamic proteins was analyzed using quantitative proteomics analysis. Proteins related to oxidative stress, inflammation, and neuronal injury in the hypothalamus of T2DM rats were analyzed by flow cytometry, quantitative real-time PCR, Western blotting, and immunofluorescence. RESULTS: Quantitative proteomics analysis showed significant differences in proteins related to oxidative stress, inflammation, and neuronal injury in the hypothalamus of rats with T2DM-DJB after DJB surgery, compared to the T2DM-Sham groups of rats. Oxidative stress-related proteins (glucagon-like peptide 1 receptor, Nrf2, and HO-1) were significantly increased (P < 0.05) in the hypothalamus of rats with T2DM after DJB surgery. DJB surgery significantly reduced (P < 0.05) hypothalamic inflammation in T2DM rats by inhibiting the activation of NF-κB and decreasing the expression of interleukin (IL)-1ß and IL-6. DJB surgery significantly reduced (P < 0.05) the expression of factors related to neuronal injury (glial fibrillary acidic protein and Caspase-3) in the hypothalamus of T2DM rats and upregulated (P < 0.05) the expression of neuroprotective factors (C-fos, Ki67, Bcl-2, and BDNF), thereby reducing hypothalamic injury in T2DM rats. CONCLUSION: DJB surgery improve oxidative stress and inflammation in the hypothalamus of T2DM rats and reduce neuronal cell injury by activating the glucagon-like peptide 1 receptor-mediated Nrf2/HO-1 signaling pathway.

Synthesis and application of enantioenriched functionalized α-tetrasubstituted α-amino acids from biocatalytic desymmetrization of prochiral α-aminomalonamides.

Catalyzed by Rhodococcus erythropolis AJ270, an amidase-containing microbial whole cell catalyst in neutral phosphate buffer at 30 °C, a number of prochiral α-substituted α-aminomalonamides underwent highly efficient and enantioselective hydrolytic desymmetrization to afford functionalized α-tetrasubstituted α-amino acids in 74-98% chemical yields and 94.0 to >99.5% ee. The presence of a free α-amino (NH(2)) substituent in the substrates was deemed important to ensure high biocatalytic efficiency and enantioselectivity. The synthetic application of biocatalytic desymmetrization was demonstrated by practical chemical transformations of (R)-2-amino-2-carbamoylpent-4-enoic acid to α-substituted serine analogues and a bioactive diamino alcohol derivative.

Identification of DNA Repair-Related Genes Predicting Clinical Outcome for Thyroid Cancer.

Recent studies have demonstrated the utility and superiority of DNA repair-related genes as novel biomarkers for cancer diagnosis, prognosis, and therapy. Here, we aimed to screen the potential survival-related DNA repair-related genes in thyroid cancer (TC). TCGA datasets were utilized to analyze the differentially expressed DNA repair-related genes between TC and nontumor tissues. The K-M approach and univariate analysis were employed to screen survival-related genes. RT-PCR was employed to examine the expression of DNA repair-related genes in TC samples and matched noncancer samples. CCK-8 analyses were used to determine cellular proliferation. Herein, our team discovered that the expression of four DNA repair-related genes was remarkably upregulated in TC samples in contrast to noncancer samples. Survival assays identified 14 DNA repair-related genes. In our cohort, we observed that the expression of TAF13 and DCTN4 was distinctly elevated in TC specimens in contrast to nontumor specimens. Moreover, knockdown of TAF13 and DCTN4 was observed to inhibit the TC cellular proliferation. Overall, the upregulation of TAF13 and DCTN4 is related to decreased overall survival in TC patients. Therefore, the assessment of TAF13 and DCTN4 expression may be useful for predicting prognosis in these patients.

Enhancement of Copper Uptake of Yeast Through Systematic Optimization of Medium and the Cultivation Process of Saccharomyces cerevisiae.

Copper is an essential trace element for living organisms. Copper enriched by yeast of Saccharomyces cerevisiae is regarded as the biologically available organic copper supplement with great potentiality for application. However, the lower uptake ratio of copper ions makes the production of copper enriched by yeast uneconomically and environmentally unfriendly. In this study, S. cerevisiae Cu-5 with higher copper tolerance and intracellular copper accumulation was obtained by screening of our yeast strains collection. To increase the uptake ratio of copper ions, the medium composition and cultivation conditions for strain Cu-5 were optimized systematically. A medium comprised of glucose, yeast extract, (NH4)2SO4, and inorganic salts was determined, then a novel cultivation strategy including pH control at 5.5 and increasing amounts of yeast extract for a higher concentration of copper ion in the medium was developed. The uptake ratios of copper ions were more than 90% after combining 50 to 100 mg/L copper ions with 3.5 to 5.0 g/L yeast extract, which is the highest until now and is conducive to the cost-effective and environmentally friendly production of bioactive copper in yeast-enriched form.

Ventromedial Thalamus-Projecting DCN Neurons Modulate Associative Sensorimotor Responses in Mice.

The deep cerebellar nuclei (DCN) integrate various inputs to the cerebellum and form the final cerebellar outputs critical for associative sensorimotor learning. However, the functional relevance of distinct neuronal subpopulations within the DCN remains poorly understood. Here, we examined a subpopulation of mouse DCN neurons whose axons specifically project to the ventromedial (Vm) thalamus (DCNVm neurons), and found that these neurons represent a specific subset of DCN units whose activity varies with trace eyeblink conditioning (tEBC), a classical associative sensorimotor learning task. Upon conditioning, the activity of DCNVm neurons signaled the performance of conditioned eyeblink responses (CRs). Optogenetic activation and inhibition of the DCNVm neurons in well-trained mice amplified and diminished the CRs, respectively. Chemogenetic manipulation of the DCNVm neurons had no effects on non-associative motor coordination. Furthermore, optogenetic activation of the DCNVm neurons caused rapid elevated firing activity in the cingulate cortex, a brain area critical for bridging the time gap between sensory stimuli and motor execution during tEBC. Together, our data highlights DCNVm neurons' function and delineates their kinematic parameters that modulate the strength of associative sensorimotor responses.

[Expression of LYVE-1 and Prox-1 in non-small cell lung cancer and the relationship with lymph node metastasis].

OBJECTIVE: To investigate the expression of lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), the homeobox gene (Prox-1), in patients with non-small cell lung cancer (NSCLC), the relationship with microlymphatic vessel density, lymph node metastasis and their clinic pathological value. METHODS: Forty specimens of the NSCLC as experimental group and eleven pulmonary benign diseases as control group were studied. The expressions of LYVE-1, Prox-1 and CD31 protein in specimens of NSCLC and normal pulmonary tissue were studied with immunohistochemical (IHC) technique. Microlymphatic vessel density (MLVD) and microvessel density (MVD) were counted. Meanwhile, all specimens were also examined by conventional pathological method. Clinicopathological data of each patient were recorded and analyzed. RESULTS: (1) Among 40 cases of the center of NSCLC cancerous tissues, the MLVDs marked by LYVE-1 and Prox-1 were 4.22 +/- 1.25 and 1. 99 +/- 1.49 respectively, which were significantly lower than those of the pulmonary benign diseases tissues (P = 0.00). (2) The MLVDs marked by LYVE-1 and Prox-1 in NSCLC cancerous invasive edge were 10.89 +/- 2.06 and 6.63 +/- 1.99 respectively, which were significantly higher than those in the center of cancerous tissues and those of the pulmonary benign diseases tissues (P = 0.000). (3) The MLVDs marked by LYVE-1 and Prox-1 in cancerous invasive edge were not correlated with age, gender, site and dimension of lesion, types of histological and degree of differentiation, but correlated significantly with lymph node metastasis (P = 0.000) and PTNM stage (P = 0.000). Meanwhile, along with lymph node metastasis and increasing of PTNM stage, the expressions of LYVE-1 and Prox-1 protein and MLVDs have significantly increased, but the microvessel density marked by CD31 in cancerous invasive edge was not correlated significantly with lymph node metastasis (P = 0.450) and PTNM stage (P = 0.377). (4) Significant correlation between LYVE-1 and Prox-1 (r = 0.529, P = 0.000) expression was observed in NSCLC; moreover, no correlations between LYVE-1 and CD31, Prox-1 and CD31 (r = 0.034, P = 0.837; r = -0.075, P = 0.647) were The functional microlymphatic vessels correlated with lymphatic metastasis are mainly observed. CONCLUSION: located in the cancerous invasive edge rather than the center of cancerous tissues. LYVE-1 and Prox-1 might be acted as molecular phenotypes of lymphangioghesis in NSCLC and as important markers for evaluating lymphatic metastasis and prognosis in patients with NSCLC.

Neuronal Activity in the Cerebellum During the Sleep-Wakefulness Transition in Mice.

Cerebellar malfunction can lead to sleep disturbance such as excessive daytime sleepiness, suggesting that the cerebellum may be involved in regulating sleep and/or wakefulness. However, understanding the features of cerebellar regulation in sleep and wakefulness states requires a detailed characterization of neuronal activity within this area. By performing multiple-unit recordings in mice, we showed that Purkinje cells (PCs) in the cerebellar cortex exhibited increased firing activity prior to the transition from sleep to wakefulness. Notably, the increased PC activity resulted from the inputs of low-frequency non-PC units in the cerebellar cortex. Moreover, the increased PC activity was accompanied by decreased activity in neurons of the deep cerebellar nuclei at the non-rapid eye-movement sleep-wakefulness transition. Our results provide in vivo electrophysiological evidence that the cerebellum has the potential to actively regulate the sleep-wakefulness transition.

Spontaneous recovery of conditioned eyeblink responses is associated with transiently decreased cerebellar theta activity in guinea pigs.

Behavioral studies have demonstrated that extinguished conditioned eyeblink responses (CR) can spontaneously recover after extinction. However, the neural mechanisms underlying this process are still unclear. We have shown that spontaneous cerebellar theta activity was predictive of subsequent CR extinction. Here, we sought to further evaluate the association between spontaneous recovery and cerebellar theta activity in behaving guinea pigs. It was found that trace conditioning training significantly diminished the degree of spontaneous recovery during extinction sessions as compared to delay training. Moreover, by recording local field potential in the cerebellum of guinea pigs undergoing an eyeblink conditioning extinction task, we found that spontaneous recovery of delay-paradigm CRs was associated with transiently decreased CS-evoked theta activity in the cerebellum. These findings suggest that decreased CS-evoked cerebellar theta activity may contribute to the neural process that is important for the spontaneous recovery of extinguished motor memory. Future studies are needed to clarify the neural mechanism underlying changed cerebellar theta activity during altered behavioral contingencies.

A method for combining multiple-units readout of optogenetic control with natural stimulation-evoked eyeblink conditioning in freely-moving mice.

A growing pool of transgenic mice expressing Cre-recombinases, together with Cre-dependent opsin viruses, provide good tools to manipulate specific neural circuits related to eyeblink conditioning (EBC). However, currently available methods do not enable to get fast and precise readout of optogenetic control when the freely-moving mice are receiving EBC training. In the current study, we describe a laser diode (LD)-optical fiber (OF)-Tetrode assembly that allows for simultaneous multiple units recording and optical stimulation. Since the numbers of various cables that require to be connected are minimized, the LD-OF-Tetrode assembly can be combined with CS-US delivery apparatus for revealing the effects of optical stimulation on EBC in freely- moving mice. Moreover, this combination of techniques can be utilized to optogenetically intervene in hippocampal neuronal activities during the post-conditioning sleep in a closed-loop manner. This novel device thus enhances our ability to explore how specific neuronal assembly contributes to associative motor memory in vivo.

Effects of acute cooling/rewarming on membrane potential and K(+) currents in rat ventricular myocytes.

The effects of acute cooling/rewarming on cardiac K(+) currents and membrane potential were investigated. Membrane potential and current were assessed with whole-cell patch-clamp technique in current- and voltage-clamp modes. When the temperature of bath solution was decreased from 25 °C; to 4 °C, the transient outward current (I(to)) was completely abolished, the sustained outward K(+) current (I(ss)) at +60 mV and the inward rectifier K(+) current (I(K1)) at -120 mV were depressed by (48.5±14.1)% and (35.7±18.2)%, respectively, and the membrane potential became more positive. After the temperature of bath solution was raised from 4 °C; to 36 °C;, the membrane potential exhibited a transient hyperpolarization and then was maintained at a stable level. In some myocytes (36 out of 58), activation of the ATP-sensitive K(+) (K(ATP)) channels after rewarming was observed. The rewarming-induced change in the membrane potential was inhibited by the Na(+)/K(+)-ATPase inhibitor ouabain (100 µmol/L), and the rewarming-elicited activation of K(ATP) channels was inhibited by the protein kinase A inhibitor H-89 (100 µmol/L). Moreover, decrease of the temperature from 25 °C; to 4 °C; did not induce any significant change in cell volume when the cell membrane potential was clamped at 0 mV. However, significant cell shrinkage with spots was observed soon after rewarming-induced activation of K(ATP) channels. These data demonstrate that acute cooling/rewarming has a profound influence on the membrane potential and K(+) currents of ventricular myocytes, and suggest that activation of K(ATP) channels may play a role in cardiac cooling/rewarming injury.

[Expression of neuronal nitric oxide synthase in corpus cavernosum with diabetic erectile dysfunction: experiment with rabbits].

OBJECTIVE: To investigate the expression characteristics of neuronal nitric oxide synthase (nNOS) in the corpus cavernosum of diabetic erectile dysfunction (ED). METHODS: Fifty rabbits underwent single intravenous injection of alloxan (100 mg/kg). Blood glucose, system arterial pressure (SAP), and intracavemosal pressure (ICP) were measured 15, 30, and 45 days later. The rabbits with the blood glucose >10 mmol/L were used as diabetic models and those with the ICP lower than the normal control group by more than 25% were used as diabetic ED models. RT-PCR, immunohistochemistry, and Western-blotting were used to detect the expression of nNOS in the corpus cavemosum. RESULTS: Seven days after the alloxan injection the blood glucose levels of 35 rabbits (70%) were > 10 mmol/L. 40% rabbits (14/35) were were used as diabetic ED models. Compared with control group, the ICP 15, 30, and 45 days after alloxan injection were considerately decreased in diabetic ED rabbits (all P < 0.01), and there was no significant difference in SAP between the two groups (all P > 0.05). The relative values of nNOS mRNA expression 15, 30, and 45 days after alloxan injection of diabetic ED rabbits were 0.670 +/- 0.030, 0.451 +/- 0.012, and 0.206 +/- 0.023 respectively,all significantly lower than those of the control group (0.817 +/- 0.010, 0.814 +/- 0.020, and 0.802 +/- 0.007 respectively, all P < 0.05). Western blotting showed that the relative values of nNOS 15, 30, and 45 days after alloxan injection of the ED rabbits were 0.713 +/- 0.014, 0.424 +/- 0.007, and 0.337 +/- 0.009 respectively, all significantly lower than those of the control group (0.797 +/- 0.015, 0.706 +/- 0.020, and 0. 750 +/- 0.022 respectively, all P < 0.05). CONCLUSION: Decreased expression of nNOS in corpus cavernosum is one of possible pathway of diabetic ED.

Plasmon-enhanced Raman spectroscopic metrics for in situ quantitative and dynamic assays of cell apoptosis and necrosis.

Apoptosis and necrosis are distinct cell death processes related to many cellular pathways. In situ, quantitatively and dynamically monitoring such processes may provide vitally important information for cell studies. However, such a method still remains elusive, even though current immunochemical methodologies have developed extremely valuable tools. Herein, we demonstrate Raman spectroscopic metrics for validating and quantifying apoptotic and necrotic cells based on their distinct molecular vibrational fingerprints. It not only allows us to quantify apoptotic and necrotic cell populations in situ in adherent cell samples, but also to be capable of continuously monitoring the dynamical processes of apoptosis and necrosis at the same time in one sample. This method provides comparable results with the "gold standard" of flow cytometry, moreover, with several incomparable advantages. Our work offers a powerful new tool for cell apoptosis and necrosis assays and is expected to become a benchmark technology in biological and medical studies.

[Effects of wind speed on drying processes of fuelbeds composed of Mongolian oak broad-leaves.] / é£Žé€Ÿå¯¹è’™å¤æ Žé˜”å¶åºŠå±‚å¤±æ°´è¿‡ç¨‹çš„å½±å“.

Water desorption processes of fuel beds with Mongolian oak broad-leaves were observed under conditions with various wind speeds but nearly constant air temperature and humidity. The effects of wind speed on drying coefficients of fuel beds with various moisture contents were analyzed. Three phases of drying process, namely high initial moisture content (>75%) of phase 1, transition state of phase 2, and equilibrium phase III could be identified. During phase 1, water loss rate under higher wind speed was higher than that under lower wind speed. Water loss rate under higher wind speed was lower than that under lower wind speed during phase 2. During phase 3, water loss rates under different wind speeds were similar. The wind effects decreased with the decrease of fuel moisture. The drying coefficient of the Mongolian oak broad-leaves fuel beds was affected by wind speed and fuel bed compactness, and the interaction between these two factors. The coefficient increased with wind speed roughly in a monotonic cubic polynomial form.

[Amelioration of latent skin lesions in streptozotocin-induced diabetic rats by insulin].

OBJECTIVE: To explore the latent skin lesions in streptozotocin-induced diabetic rats and the mechanism of insulin prevention. METHODS: 81 male Sprague-Dawley (SD) rats were randomized into control (C, n = 27) and STZ-induced diabetic groups (n = 54), and then the diabetic rats were randomized into 2 groups: Group A group (n = 27) that was treated with insulin enough to control the high concentration of blood glucose strictly, and Group B group (n = 27) in which insulin was given too nut not sufficient to control the high blood glucose. Twenty-seven normal rats were used as controls. Four, eight, and twelve weeks after STZ-induction, skin specimens from the back were collected to undergo hematoxylin-eosin staining and histological examination. The skin glucose content was measured by Beckman's autoanalyzer. The skin advanced glycation end products (AGEs) concentration was assessed by fluorescence spectrophotometry and immunohistochemistry. The ultrastructure changes of skin microvessel were observed by electron microscopy. RESULTS: Twelve weeks after the establishment of the DM model the skin thickness of Group B was decreased, the features of multilayer epithelium structure disappeared in epidermis, and part of the collagen fibers in dermis became atrophic, swollen and degenerated, infiltration of inflammatory cells to different degrees was found, and subcutaneous fat showed progressive atrophy or disappeared. However, such changes were not detected in Group A. The skin glucose contents of Group B at different time points were all higher than those of Group A and Group (all P < 0.01) without a significant difference between Groups A and C. The fluorescence values of skin collagen extracts of Groups A and B were significantly higher than that of normal rats. The 8-week fluorescence value of skin collagen extracts of Groups B was 34 U/mg +/- 4 U/mg, significantly higher than that of Group A (29 U/mg +/- 3 U/mg, P < 0.05). The 12-week fluorescence value of skin collagen extracts of Groups B was 41 U/mg +/- 4 U/mg, significantly higher than that of Group A (32 U/mg +/- 4 U/mg, P < 0.05). The 8-week AGEs positive expression rate of Group B was 32% +/- 4%, significantly higher than that of Group A (25% +/- 5%, P < 0.05), and the 12-week AGEs positive expression rate of Group B was 39% +/- 5%, significantly higher than that of Group A (27% +/- 4%, P < 0.05). Degeneration of endothelial cells and thickening of basement membrane were more markedly in Group B than in Group A. CONCLUSION: Accumulation of AGEs in skin and high concentration of glucose are important causes of diabetic skin complications. Insulin application at the early stage postpones the course of diabetic skin lesions with the possible mechanisms of lowering the high glucose, inhibiting AGEs synthesis, and blocking the action of AGEs.