[Debridement combined with negative-pressure wound therapy and local flap for treating a case of stingray sting]

On January 10, 2018, a 35-year-old male patient with a 3 day stingray stinger injury in his left thigh was admitted to Xuzhou Central Hospital. At the time of admission, the patient's left thigh was red, swollen, and painful. On the day of admission, the patient underwent emergency operation in the outpatient operating room for local debridement to remove the infected and necrotic tissue. After the routine dressing change and the wound got better, surgical debridement and negative-pressure wound therapy were performed, and finally local flap was used to repair the wound. On the 14th day after the flap repair operation, the suture was removed and the patient was discharged. After half a year follow-up, the appearance of the operation area recovered well. This case suggests that the timely and correct pre-hospital treatment, thorough and timely debridement, and systemic antibiotic application are important means to reduce further injury of toxin. The local flap can achieve satisfactory result on wound healing after the wound bed is prepared by negative-pressure wound therapy.

Knockdown of microRNA-103a-3p inhibits the malignancy of thyroid cancer cells through Hippo signaling pathway by upregulating LATS1

MicroRNA (miR)-103a-3p has been shown to be involved in the development and progression of several types of cancer. However, the role of miR-103a-3p in thyroid cancer remains unclear. This study investigated the effects of miR-103a-3p on the biological characteristics of thyroid cancer cells and related mechanisms. In the present study, we found that the expression of miR-103a-3p was increased in thyroid cancer tissues compared to that in non-cancerous tissues. Additionally, the expression of miR-103a-3p in thyroid cancer cell lines (TPC-1, SW579, BHT101, K1) was markedly higher than that in the human thyroid cell line (Nthy-ori3-1). Silencing of miR-103a-3p obviously inhibited proliferation, migration, and invasion and promoted apoptosis of BHT101 cells. miR-103a-3p upregulation promoted the proliferation, migration, and invasion and inhibited apoptosis of K1 cells. Mechanistically, LATS1 was identified as a functional target of miR-103a-3p, and miR-103a-3p negatively regulated LATS1 expression. miR-103a-3p knockdown (or upregulation) partially reversed the effects of LATS1 knockdown (or overexpression) on proliferation, apoptosis, migration, and invasion of thyroid cancer cells. LATS1 knockdown inhibited the phosphorylation of YAP in BHT101 cells and promoted the nuclear translocation of YAP. Whereas, miR-103a-3p downregulation reversed the inhibitory effect of LATS1 knockdown on the Hippo signaling pathway. Moreover, overexpression of LATS1 induced YAP phosphorylation in K1 cells and inhibits nuclear translocation of YAP, and the upregulation of miR-103a-3p reversed this effect. The knockdown of miR-103a-3p inhibited tumor growth and progression in vivo. Taken together, knockdown of miR-103a-3p inhibits proliferation, migration, and invasion and promotes apoptosis of thyroid cancer cells through the Hippo signaling pathway by upregulating LATS1.

Bi-needle technique versus transforaminal endoscopic spine system technique for percutaneous endoscopic lumbar discectomy in treating intervertebral disc calcification: a propensity score matched cohort analysis

OBJECTIVE

The aim of this study was to evaluate the clinical results of a Bi-needle technique and conventional transforaminal endoscopic spine system (TESSYS) technique for percutaneous endoscopic lumbar discectomy (PELD) in treating patients with intervertebral disc calcification (IDC).

BACKGROUND

PELD has gained acceptance for treating patients with IDC. The Bi-needle technique was designed to improve the efficiency and safety of PELD.

METHOD

Bi-needle and TESSYS group within each cohort were balanced using 1:1 propensity score matching. Finally, 32 patients with IDC treated by Bi-needle technique from December 2015 to September 2017 were enrolled and 25 patients treated by TESSYS technique from the same spine surgery center between January 2013 and October 2017 were enrolled as controls.

RESULTS

Propensity score matching generated 22 Bi-needle and 22 TESSYS patients. There were no significant differences in visual analog scale and lumbar Japanese Orthopaedic Association scores between Bi-needle and TESSYS group. Operative time and rate of complications in the Bi-needle was significantly better than the TESSYS group (p < 0.01).

CONCLUSIONS

Both surgical methods achieved good clinical outcomes. However, compared with the TESSSY technique, operative time of the Bi-needle technique is shorter, and rate of complications is lower.

Thoracic de-kyphosis for revision surgery of a failure case of endoscopic discectomy: a case report and literature review

BACKGROUND

Indications and clinical outcomes of percutaneous endoscopic thoracic discectomy(PETD) in treating thoracic disc herniation is rarely reported and still controversial. We reported an unsatisfied recovery of thoracic disc herniation with PETD, treated by a second posterior thoracic laminectomy and Ponte osteotomy.

CASE DESCRIPTION

A male presented with lower extremity weakness and stagger caused by T3/4 intervertebral disc herniation. The upper thoracic curve was in excessive kyphosis with T2-5 Cobb angle of 34.3 degrees. The preoperative ODI score was 34 and Roelzs's JOA score was 14. Percutaneous transforaminal endoscopic thoracic discectomy (PETD) from a posterior lateral approach was performed. At five-month follow-up, his thoracic back pain and staggering gait did not improve. The postoperative T2-5 Cobb angle was 32.1 degrees, the ODI score was 24 and Roelzs's JOA score was 14. A second posterior thoracic decompression this time with fixation was performed, but no disc herniation was detected. A Ponte osteotomy was performed to correct the kyphosis. One month after the second surgery, muscle strength of the lower limbs was improving with the T2-5 Cobb angle decreased to 19.4 degrees, the ODI score decreased to 10 and Roelzs's JOA score increase to 16. Six month later, the ODI score decreased to 0 and Roelzs's JOA score improved to 18. In review of the literature, PETD doesn't guarantee the patient a satisfactory neurological recovery for kyphotic thoracic disc herniation. Posterior decompression with Ponte osteotomy may be beneficial to release the tension and decompression of the spinal cord tension.

CONCLUSIONS

Thoracic disc herniation with kyphosis angle >20 degrees (T2-5), percutaneous endoscopic thoracic discectomy is not likely to get good neurologic results. Posterior laminectomy with ponte osteotomy might be beneficial for these patients to induce dorsal drifting of the spinal cord from anterior herniation.

Risk factors for late-onset hypogonadism

The European Male Aging Study (EMAS) has recently defined strict diagnostic criteria for late-onset hypogonadism (LOH) including the levels of serum total testosterone (TT), free testosterone (FT) and three sexual symptoms. However, there is no report on risk factors for LOH using these criteria. In this study, we investigated risk factors for LOH based on these criteria. We recruited 277 men (aged 36-80 years) who completed both a health check-up and two questionnaires (a health and lifestyle questionnaire, and a sexual function questionnaire). Data on parameters, such as systolic blood pressure (SBP), glucose, triglyceride (TG) and high-density lipoprotein (HDL), were obtained from medical records of the hospital in Shantou. TT and sex hormone-binding globulin (SHBG) were measured by chemiluminescent immunoassay, and FT was calculated. TT, FT, age, waist circumference, SBP and glucose showed significant differences between LOH-positive and LOH-negative individuals. Univariate regression analyses showed that age, waist circumference, SBP, glucose and health status were risk factors for LOH. Pearson's correlation analysis revealed that TT was inversely correlated with waist circumference, glucose and SBP, and FT was inversely correlated with age, SBP and health status. In conclusion, age, waist circumference, SBP, glucose and health status were risk factors for LOH.

[The dynamic change of cytokines associated with the speccificimmunotherapy and its clinical significance]

Objective:This project aimed to study the dynamic change of the cytokines associated with specific immunotherapy(SIT) pre- and post-SIT.Searching for immune regulatory indicators would used in SIT.Method:One hundred cases who had accepted SIT were enrolled in the project.Data of serum specific IgE and cytokines were statistically analyzed.In the three periods,pre-SIT,17 weeks post-SIT,57 weeks post-SIT,the levels of the eight kinds of cytokines(IL-4,IL-5,IL-8,IL-10,IL-13,IL-17,IFN-γ and TNF-α)were detected,and the dynamic change of the nasal symptoms score were analyzed.Result:The six kinds of cytokines(IL-5,IL-8,IL-10,IL-13,IL-17 and TNF-α)had no significant difference before and after SIT.The level of house dust mite sIgE level was positively correlated with serum IL-5 when the SIT pre-treatment and 57weeks (P<0.05).Pre-treatment and in 17 weeks after treatment,serum IL-5,IL-17 content difference and reduce the magnitude of nasal symptom scores were positively correlated (P<0.01).In 17 weeks of treatment and 57 weeks of treatment,difference of serum IL-10,IL-13,TNF-α levelsand the difference of nasal symptom scores were negatively correlated(P<0.01).Pre- treatment and 57 weeks,difference of serum IL-13,IL-17,TNF-α and the difference of nasal symptom scores were positively correlated (P<0.05),serum IL-10 levels of difference between the nose ministry of magnitude lower symptom scores were negatively correlated (P<0.01).Conclusion:The cytokines (IL-4,IL-5,IL-8,IL-10,IL-13,IL-17,IFN-γ and TNF-α) associated with the SIT play an important role in allergy and can objectively reflect the immune status during SIT.

Polymorphisms of AluI and Hin1I loci of the IGF-1R gene and their genetic effects on growth traits in Bian chickens

Growth traits are important economic traits in broiler chicken production. AluI and Hin1I loci are two restriction sites, which are respectively located in exons 2 and 3 of the IGF-1R gene. These two loci are significantly related to the growth traits in Jinghai Yellow chickens. In this study, a correlation analysis was performed between these two loci and the growth traits of Bian chickens. The results showed a G376A mutation at the AluI site and a C919A mutation at the Hin1I site, which respectively resulted in three genotypes AA, AB, and BB in exon 2 and three genotypes CC, CD, and DD in exon 3. Correlation analysis showed that the female Bian chickens with the AA genotype of the AluI locus had higher body weights than those with the AB genotype (P < 0.05) at 8, 14, 16, and 18 weeks; individuals with CD genotype of Hin1I locus had higher body weights at 6, 8, 10, 12, and 14 weeks compared to the CC genotype (P < 0.05 or P < 0.01). Combined genotypes analysis showed that at the age of 8, 14, 16, and 18 weeks, the body weight of AACC genotype combination was higher than that of the ABCC genotype combination (P < 0.05); at the age of 6, 8, 12, 14, 16, and 18 weeks, the AACD genotype combination had higher (P < 0.05 or P < 0.01) body weight than that of the ABCC genotype.

[Effect of specific immunotherapy on the psychological health level and quality of life in patients with allergic rhinitis]

Objective: To study the effect of specific immunotherapy on the psychological health level and quality of life in patients with allergic rhinitis(AR).Method:Selected 97 cases diagnosed as moderate to severe persistent AR patients, were treated with specific immunotherapy for one year. All patients received the evaluation with symptom check list 90(SCL-90) and rhinoconjunctivitis quality of life questionnaire(RQLQ) before specific immunotherapy, six, and 12 months after specific immunotherapy.Result:The total scores, scores of somatization, obsessive, anxiety, depression and phobia in SCL-90 of AR patients after 12 months treatment were significantly lower than that before treatment（P < 0.05）. Total score of quality of life and subitem score in RQLQ of AR patients after 12 months treatment were obviously lower than that before treatment (P < 0.05）.Conclusion:Specific immunotherapy can effectively alleviate the clinical symptoms and improve psychological health level and quality of life of AR patients.

Improved efficacy of warm-white light-emitting diode luminaires

We present a novel approach to address one of the technical hurdles the current light-emitting diode (LED) lighting field faces: the packaged efficacy of warm-white LEDs is 20%-30% lower than that of cool-white LEDs depending on the color rendering index. With a differentiated luminaire design in combination with a new class of nano materials, we have greatly improved the efficacy of warm white by 15% at the luminaire system level, which translates to less energy being required to achieve the same light output, and thus offers a more energy-efficient solution. Reliability test of the luminaire shows no performance degradation within the tested period of more than 3000 h. A modeling has been developed to predict the optical performance of luminaires incorporating the nano materials, which agrees well with the experimental data and serves as a powerful tool for designing luminaires with targeted performance.

Cortical kynurenic acid bi-directionally modulates prefrontal glutamate levels as assessed by microdialysis and rapid electrochemistry

Using two in vivo methods, microdialysis and rapid in situ electrochemistry, this study examined the modulation of extracellular glutamate levels by endogenously produced kynurenic acid (KYNA) in the prefrontal cortex (PFC) of awake rats. Measured by microdialysis, i.p. administration of KYNA's bioprecursor L-kynurenine dose-dependently elevated extracellular KYNA and reduced extracellular glutamate (nadir after 50 mg/kg kynurenine: 60% decrease from baseline values). This dose-dependent decrease in glutamate levels was also seen using a glutamate-sensitive microelectrode array (MEA) (31% decrease following 50 mg/kg kynurenine). The kynurenine-induced reduction in glutamate was blocked (microdialysis) or attenuated (MEA) by co-administration of galantamine (3 mg/kg i.p.), a drug that competes with KYNA at an allosteric potentiating site of the alpha 7 nicotinic acetylcholine receptor. In separate experiments, extracellular glutamate levels were measured by MEA following the local perfusion (45 min) of the PFC with kynurenine (2.5 microM) or the selective KYNA biosynthesis inhibitor S-ethylsulfonylbenzoylalanine (S-ESBA; 5 mM). In agreement with previous microdialysis studies, local kynurenine application produced a reversible reduction in glutamate (nadir: -29%), whereas perfusion with S-ESBA increased glutamate levels reversibly (maximum: +38%). Collectively, these results demonstrate that fluctuations in the biosynthesis of KYNA in the PFC bi-directionally modulate extracellular glutamate levels, and that qualitatively very similar data are obtained by microdialysis and MEA. Since KYNA levels are elevated in the PFC of individuals with schizophrenia, and since prefrontal glutamatergic and nicotinic transmission mediate cognitive flexibility, normalization of KYNA levels in the PFC may constitute an effective treatment strategy for alleviating cognitive deficits in schizophrenia.

Overexpression of clusterin correlates with tumor progression, metastasis in gastric cancer: a study on tissue microarrays

Clusterin (CLU) is expressed in a wide variety of human tissues and fluids. Overexpression of cytoplasmic clusterin (sCLU) has been implicated in cancer development and progression. The aim of the present study is to evaluate the association of sCLU overexpression with clinicopathological features of human gastric carcinomas (GC).We constructed a gastric cancer tissue microarray containing 173 primary gastric carcinomas and 70 paired non-neoplastic mucosa specimens. The expression of sCLU was studied by immunohistochemistry. The correlations between sCLU expression and clinicopathological features, p53 abnormality, as well as Ki67 activation were analyzed. Overexpressions of sCLU was detected in 28.5% (n=165) of primary GCs by immunohistochemical staining, but not in non-neoplastic mucosa. Clinical association study found that overexpression of sCLU was significantly correlated with lymph-node metastasis (p < 0.001), tumor invasion (p < 0.001) and TNM stage (p < 0.001). In Kaplan-Meier survival analysis, overexpression of sCLU was significantly correlated with unfavorable survival in advanced GCs (p < 0.03). Furthermore, the association of sCLU with abnormal expression of p53 was ascertained. These results suggested that overexpression of sCLU was involved in the progression of GC and it's oncogenic function might be associated with p53 abnormality. Overexpression of sCLU seems to be related with patient's shorter survival in late stage GC.

Increased cortical kynurenate content in schizophrenia

BACKGROUND

Metabolites of the kynurenine pathway of tryptophan degradation may play a role in the pathogenesis of several human brain diseases. One of the key metabolites in this pathway, kynurenine, is either transaminated to form the glutamate receptor antagonist, kynurenate, or hydroxylated to 3-hydroxykynurenine, which in turn is further degraded to the excitotoxic N-methyl-D-aspartate receptor agonist quinolinate. Because a hypoglutamatergic tone may be involved in the pathophysiology of schizophrenia, it is conceivable that alterations in kynurenine pathway metabolism may play a role in the disease.

METHODS

The tissue levels of kynurenine, kynurenate, and 3-hydroxykynurenine were measured in brain tissue specimens obtained from the Maryland Brain Collection. All three metabolites were determined in the same samples from three cortical brain regions (Brodmann areas 9, 10, and 19), obtained from 30 schizophrenic and 31 matched control subjects.

RESULTS

Kynurenate levels were significantly increased in schizophrenic cases in Brodmann area 9 (2.9 +/- 2.2 vs. 1.9 +/- 1.3 pmol/mg protein, p <.05), but not in Brodmann areas 10 and 19. Kynurenine levels were elevated in schizophrenic cases in Brodmann areas 9 (35.2 +/- 28.0 vs. 22.4 +/- 14.3 pmol/mg protein; p <.05) and 19 (40.3 +/- 23.4 vs. 30.9 +/- 10.8; p <.05). No significant differences in 3-hydroxykynurenine content were observed between the two groups. In both groups, significant (p <.05) correlations were found in all three brain areas between kynurenine and kynurenate, but not between kynurenine and 3-hydroxykynurenine (p >.05). In rats, chronic (6-months) treatment with haloperidol did not cause an increase in kynurenate levels in the frontal cortex, indicating that the elevation observed in schizophrenia is not due to antipsychotic medication.

CONCLUSIONS

The data demonstrate an impairment of brain kynurenine pathway metabolism in schizophrenia, resulting in elevated kynurenate levels and suggesting a possible concomitant reduction in glutamate receptor function.

Some metabotropic glutamate receptor ligands reduce kynurenate synthesis in rats by intracellular inhibition of kynurenine aminotransferase II

Some metabotropic glutamate receptor (mGluR) ligands, such as quisqualate, L-(+)-2-amino-4-phosphonobutyric acid (L-AP4), 4-carboxy-3-hydroxyphenylglycine (4C3HPG), and L-serine-O:-phosphate (L-SOP), reduced the formation of the endogenous excitatory amino acid receptor antagonist kynurenate in brain and liver slices. The use of novel, subtype-selective mGluR agonists and antagonists excluded a role for any known mGluR subtype in this effect. The reduction of kynurenate formation was no longer observed when slices were incubated with the active mGluR ligands in the absence of extracellular Na(+). trans-Pyrrolidine-2,4-dicarboxylate (trans-PDC), a broad-spectrum ligand of Na(+)-dependent glutamate transporters, was also able to reduce kynurenate formation. Quisqualate, 4C3HPG, L-AP4, and L-SOP did not further reduce kynurenate formation in the presence of trans-PDC, suggesting that the two classes of drugs may share the same mechanism of action. Hence, we hypothesized that the active mGluR ligands are transported inside the cell and act intracellularly to reduce kynurenate synthesis. We examined this possibility by assessing the direct effect of mGluR ligands on the activity of kynurenine aminotransferases (KATs) I and II, the enzymes that transaminate kynurenine to kynurenate. In brain tissue homogenates, KAT II (but not KAT I) activity was inhibited by quisqualate, 4C3HPG, L-AP4, L-SOP, and trans-PDC. Drugs that were unable to reduce kynurenate formation in tissue slices were inactive. We conclude that some mGluR ligands act intracellularly, inhibiting KAT II activity and therefore reducing kynurenate formation. This effect should be taken into consideration when novel mGluR ligands are developed for the treatment of neurological and psychiatric diseases.

Dopaminergic control of kynurenate levels and N-methyl-D-aspartate toxicity in the developing rat striatum

This study was designed to examine the effects of d-amphetamine (D-AMPH) and D1- and D2-selective dopaminergic drugs on the concentration of the broad-spectrum excitatory amino acid receptor antagonist kynurenic acid (KYNA) in the striatum of developing and adult rats. At all ages, KYNA levels were significantly reduced 1 h after the systemic administration of D-AMPH (5 mg/kg). SKF 38393 (5 mg/kg) and quinpirole (2 mg/kg) also caused a rapid decrease in striatal KYNA, but only in postnatal day (PND) 7 and 14 rats. All these effects were readily prevented by specific dopamine receptor antagonists. The possible functional significance of the reduction in KYNA levels was tested in PND 14 animals. When pretreated with D-AMPH (5 mg/kg), these rats showed markedly increased vulnerability to an intrastriatal injection of the excitotoxin NMDA. These data suggest that KYNA plays a role as a mediator of dopamine-glutamate interactions in the rat striatum.

Kynurenergic manipulations influence excitatory synaptic function and excitotoxic vulnerability in the rat hippocampus in vivo

Competing enzymatic mechanisms degrade the tryptophan metabolite L-kynurenine to kynurenate, an inhibitory and neuroprotective compound, and to the neurotoxins 3-hydroxykynurenine and quinolinate. Kynurenine 3-hydroxylase inhibitors such as PNU 156561 shift metabolism towards enhanced kynurenate production, and this effect may underlie the recently discovered anticonvulsant and neuroprotective efficacy of these drugs. Using electrophysiological and neurotoxicological endpoints, we now used PNU 156561 as a tool to examine the functional interplay of kynurenate, 3-hydroxykynurenine and quinolinate in the rat hippocampus in vivo. First, population spike amplitude in area CA1 and the extent of quinolinate-induced excitotoxic neurodegeneration were studied in animals receiving acute or prolonged intravenous infusions of L-kynurenine, PNU 156561, (L-kynurenine+PNU 156561) or kynurenate. Only the latter two treatments, but not L-kynurenine or PNU 156561 alone, caused substantial inhibition of evoked responses in area CA1, and only prolonged (3h) infusion of (L-kynurenine+PNU 156561) or kynurenate was neuroprotective. Biochemical analyses in separate animals revealed that the levels of kynurenate attained in both blood and brain (hippocampus) were essentially identical in rats receiving extended infusions of L-kynurenine alone or (L-kynurenine+PNU 156561) (4 and 7microM, respectively, after an infusion of 90 or 180min). However, addition of the kynurenine 3-hydroxylase inhibitor resulted in a significant decrement in the formation of 3-hydroxykynurenine and quinolinate in both blood and brain. These data suggest that the ratio between kynurenate and 3-hydroxykynurenine and/or quinolinate in the brain is a critical determinant of neuronal excitability and viability. The anticonvulsant and neuroprotective potency of kynurenine 3-hydroxylase inhibitors may therefore be due to the drugs' dual action on both branches of the kynurenine pathway of tryptophan degradation.

Modulation and function of kynurenic acid in the immature rat brain

Using in vivo and in vitro paradigms, the regulation and function of the brain metabolite kynurenic acid (KYNA) was examined in rats on postnatal days (PND) 7 and 14. As shown previously in adult rats, glucose removal and d-amphetamine (d-Amph) administration caused decreases in KYNA formation, while exposure to pyruvate up-regulated KYNA synthesis. The effect of glucose deprivation was substantially blunted in immature animals. In PND 14 rats, d-Amph pre-treatment exacerbated the excitotoxic effects of an intrastriatal N-methyl-D-aspartate (NMDA) injection. This potentiation was prevented by m-nitrobenzoylalanine, a kynurenine 3-hydroxylase inhibitor that also antagonized the KYNA reduction caused by d-Amph. These and additional experiments with the competitive NMDA receptor antagonist CGP 40116 indicate the existence of a functionally significant, novel high-affinity receptor for KYNA in the brain.

In situ produced 7-chlorokynurenate provides protection against quinolinate- and malonate-induced neurotoxicity in the rat striatum

Excitotoxic mechanisms may play a critical role in the pathophysiology of several neurological and psychiatric diseases. Excitatory amino acid receptor antagonists are therefore of great therapeutic interest, but untoward side effects often prevent their clinical use. Targeting the glycine coagonist site of the (NMDA) receptor may bypass these shortcomings. The present study was designed to evaluate the neuroprotective characteristics of l-4-chlorokynurenine (4-Cl-KYN), a synthetic compound which is enzymatically converted to the selective glycine/NMDA receptor antagonist 7-chlorokynurenate (7-Cl-KYNA). Using slow (2 h) intrastriatal infusions of the excitotoxins quinolinate (QUIN; 120 nmol) or malonate (6.8 micromol) as the experimental paradigm, the neuroprotective potency of 4-Cl-KYN was first compared with that of exogenous 7-Cl-KYNA, using glutamate decarboxylase activity as a lesion marker. One hundred and thirty-five nanomoles of the prodrug 4-Cl-KYN or 27 nmol 7-Cl-KYNA, the former used in a pre- and cotreatment regimen, were required to block QUIN or, less efficiently, malonate toxicity. In separate animals, the metabolic fate of this neuroprotective dose of 4-Cl-KYN was examined in vivo. In control striata, the treatment gave rise to 170 +/- 25 pmol 7-Cl-KYNA/mg protein, approximately six times less than an infusion of 27 nmol exogenous 7-Cl-KYNA, indicating greatly superior efficacy of the focally produced antagonist. Notably, the conversion of 4-Cl-KYN to 7-Cl-KYNA increased by 82% in the presence of QUIN. 4-Cl-KYN was also metabolized to 4-chloro-3-hydroxyanthranilate, an established, powerful inhibitor of QUIN synthesis. This unique pharmacological profile and the fact that the prodrug, unlike 7-Cl-KYNA, readily penetrates the blood-brain barrier suggest that 4-Cl-KYN may be exceptionally useful as an anti-excitotoxic agent.

Systemic administration of 4-chlorokynurenine prevents quinolinate neurotoxicity in the rat hippocampus

The synthetic compound 4-chlorokynurenine has been shown to be enzymatically transaminated to the selective glycine(B) receptor antagonist 7-chlorokynurenate. Since 4-chlorokynurenine, in contrast to 7-chlorokynurenate, readily penetrates the blood-brain barrier, the present study evaluated its neuroprotective properties after systemic administration in rats. Intrahippocampal injection of the NMDA receptor agonist quinolinate (15 nmol/l microl) was used as the neurotoxic paradigm. Serum and hippocampal tissue measurements confirmed that 4-chlorokynurenine serves as an effective pro-drug of 7-chlorokynurenate both in the periphery and in the brain. These studies and complementary hippocampal microdialysis experiments compared the effects of single and repeated injections of 4-chlorokynurenine (50 or 200 mg/kg, intraperitoneal (i.p.), 10 min prior to an intrahippocampal quinolinate injection; or 50 mg/kg, i.p., 10 min before and 30, 120 and 360 min after quinolinate). With the multiple-dosing regimen, extracellular 7-chlorokynurenate levels in the hippocampus reached a maximum of approximately 750 nM 7 h after quinolinate and gradually decreased with a half-life of about 3 h. In contrast, a single injection of 200 mg/kg 4-chlorokynurenine resulted in a considerably shorter rise in extracellular 7-chlorokynurenate without yielding higher peak levels. In separate animals, repeated treatment with 50 mg/kg 4-chlorokynurenine, but not a single injection of 200 mg/kg of the pro-drug, provided total protection against quinolinate-induced excitotoxicity. These data suggest that a prolonged and functionally relevant blockade of hippocampal glycine(B) receptors can be achieved after the systemic administration of 4-chlorokynurenine.

2-Oxoacids regulate kynurenic acid production in the rat brain: studies in vitro and in vivo

This study was designed to examine the role of 2-oxoacids in the enzymatic transamination of L-kynurenine to the excitatory amino acid receptor antagonist, kynurenate, in the rat brain. In brain tissue slices incubated in Krebs-Ringer buffer with a physiological concentration of L-kynurenine, pyruvate, and several other straight- and branched-chain 2-oxoacids, substantially restored basal kynurenate production in a dose-dependent manner without increasing the intracellular concentration of L-kynurenine. All 2-oxoacids tested also reversed or attenuated the hypoglycemia-induced decrease in kynurenate synthesis, but only pyruvate and oxaloacetate also substantially restored intracellular L-kynurenine accumulation. Thus, 2-oxoacids increase kynurenate formation in the brain primarily by functioning as co-substrates of the transamination reaction. This was supported further by the fact that the nonspecific kynurenine aminotransferase inhibitors (aminooxy)acetic acid and dichlorovinylcysteine prevented the effect of pyruvate on kynurenate production in a dose-dependent manner. Moreover, all 2-oxoacids tested attenuated or prevented the effects of veratridine, quisqualate, or L-alpha-aminoadipate, which reduce the transamination of L-kynurenine to kynurenate. Finally, dose-dependent increases in extracellular kynurenate levels in response to an intracerebral perfusion with pyruvate or alpha-ketoisocaproate were demonstrated by in vivo microdialysis. Taken together, these data show that 2-oxoacids can directly augment the de novo production of kynurenate in several areas of the rat brain. 2-Oxoacids may therefore provide a novel pharmacological approach for the manipulation of excitatory amino acid receptor function and dysfunction.

Focal microinjection of gamma-acetylenic GABA into the rat entorhinal cortex: behavioral and electroencephalographic abnormalities and preferential neuron loss in layer III

Neuron loss in layer III of the entorhinal cortex (EC) occurs in patients with temporal lobe epilepsy and in several animal models of the disease and may play a role in the development of spontaneously recurring seizures. This damage can be reproduced in rats by a focal microinjection of the indirect excitotoxin aminooxyacetic acid into the EC (Neurosci. Lett., 147: 185, 1992). We have now examined a similar but approximately 20 times more potent toxin, gamma-acetylenic GABA (GAG), for its ability to produce seizures and neurodegeneration in the rat EC. EEG activity was recorded continuously for 48 h after a focal injection of 4 micrograms GAG into the rat EC. Seizure episodes, spiking, and other irregularities occurred with a latency of 150 min. Behavioral abnormalities were observed in all animals and were always accompanied by EEG seizures. The behavioral changes subsided gradually, but EEG seizures continued up to 24 h after GAG treatment. Nissl and silver-stained tissue sections obtained 2-3 days after the injection of 4 micrograms GAG revealed neuron loss which preferentially affected the medial part of layer III of the EC, and caused a modest lesion in the hilar region of the ventral hippocampus. The neurodegenerative potency of GAG, in contrast to the effects of aminooxyacetic acid, was not influenced by the depth of anesthesia during surgery. A slight increase in the dose of GAG (to 5 micrograms) resulted in more severe behavioral seizures, causing generalized convulsions with salivation and loss of righting posture in 3 of 13 rats. These animals also showed a marked enlargement of the lesioned area, with substantial neuronal loss occurring in layer III of the EC, in the hilus of the dentate gyrus, and occasionally also in homotopic structures of the contralateral hemisphere. Seizure activity and lesions induced by 4 micrograms GAG were prevented by the NMDA receptor antagonist Dizolcipine (MK-801) (4 mg/kg, i.p., 10 min before and 12 h after GAG). These data support the notion of a close correlation between the occurrence of seizures and neuronal loss in layer III of the EC. Taken together, the study suggests that intraentorhinal injections of GAG may provide an advantageous model for the study of epileptogenic and epileptic mechanisms.

Systemic d-amphetamine administration causes a reduction of kynurenic acid levels in rat brain

Tissue levels of the endogenous excitatory amino acid receptor antagonist kynurenic acid (KYNA) and of its bioprecursor L-kynurenine were measured in rats of different ages after d-amphetamine administration. In adult animals, extracellular KYNA concentrations were also determined in vivo by hippocampal microdialysis. In the adult brain, d-amphetamine caused a transient, dose-dependent decrease in tissue content and extracellular levels of KYNA, reaching a nadir of approximately 70% of control values after 1 h at 5 mg/kg. Quantitatively similar decrements were observed in four different brain regions. Seven, 14 and 28-day-old pups were particularly sensitive to the drug, showing a reduction in forebrain KYNA levels to 25%, 40% and 35% of control values, respectively, 1 h after the administration of 5 mg/kg d-amphetamine. Notably, no changes in brain L-kynurenine levels and in liver L-kynurenine and KYNA concentrations were found after d-amphetamine administration. Thus, endogenous monoamines released by d-amphetamine may interfere with the transamination of L-kynurenine to KYNA specifically in the brain. These results suggest that d-amphetamine increases excitatory amino acid receptor function temporarily by reducing the levels of endogenous KYNA.

[Gene expression and distribution in mouse abdominal cavity mediated by adenovirus]

Infection and expression of recombinant human adenovirus in mouse abdominal cavity was reported. After adenovirus vector Ad/RSV-beta-gal harboring the E. coli lacZ marker gene was injected into mice abdominal cavity, the peritoneal surface of jejunum, ileum, colon, uterus, liver, spleen, stomach, bladder, abdominal wall, diaphragm and testis was found large patches of lacZ-positive cells. But the adenovirus vector was not able to penetrate the peritoneum, as demonstrated by histochemical staining. Another adenovirus vector Ad/RSV-tk harboring the HSV-tk gene was injected into mouse abdominal cavity and the mouse was treated with ACV. No acute toxic reaction was observed. Based on these data, the feasibility of gene therapy of malignant tumor within abdominal cavity with adenovirus mediated TK/GCV system was discussed.

Enzyme-catalyzed production of the neuroprotective NMDA receptor antagonist 7-chlorokynurenic acid in the rat brain in vivo

NMDA receptors play a critical role in neurotransmission and are also involved in the occurrence of excitotoxic nerve cell death. Synthetic halogenated analogs of the endogenous broad spectrum excitatory amino acid receptor blocker kynurenic acid are among the most potent and selective antagonists of the glycine co-agonist site of the NMDA receptor complex. Pharmacological blockade of this site provides neuroprotection in animal models of cerebral ischemia, epilepsy and neurodegenerative disorders, and does not appear to be associated with some of the undesirable side effects linked to classic competitive and non-competitive NMDA receptor antagonists. Here we demonstrate the neuroprotective quantities of 7-chloro-kynurenic acid (7-Cl-KYNA), one of the most selective and well-studied glycine site antagonists, can be synthesized in the brain from its bioprecursor L-4-chlorokynurenine (4-Cl-KYN). Intracerebral infusion of 4-Cl-KYN dose-dependently reduced quinolinate neurotoxicity in the rat hippocampus after enzymatic conversion to 7-Cl-KYNA by kynurenine aminotransferase. In accordance with previous studies demonstrating that kynurenine aminotransferase is preferentially localized in astrocytes, both the enzymatic formation of 7-Cl-KYNA and the neuroprotective potency of 4-Cl-KYN were substantially reduced following an intrahippocampal injection of the gliotoxin fluorocitrate. In situ produced 7-Cl-KYNA offers a novel neuroprotective strategy for targeting the glycine/NMDA site while avoiding excessive receptor blockade and reducing the clinical risks associated with conventional NMDA receptor antagonism.

Facilitated brain uptake of 4-chlorokynurenine and conversion to 7-chlorokynurenic acid

7-Chlorokynurenic acid (7-Cl-KYNA) and 5,7-dichlorokynurenic acid (5,7-Cl2-KYNA) are of therapeutic interest as potent glycine/N-methyl-D-aspartate NMDA) receptor antagonists, but are excluded from brain by the blood-brain barrier. We examined whether these compounds could be delivered to brain through their respective precursors, L-4-chlorokynurenine (4-Cl-KYN) and L-4,6-dichlorokynurenine (4,6-Cl2-KYN), which are amino acids. 4-Cl-KYN was shown to be rapidly shuttled into the brain by the large neutral amino acid transporter of the blood-brain barrier (K(m) = 105 +/- 14 microM, Vmax = 16.9 +/- 2.3 nmol min-1 g-1) and to be converted intracerebrally to 7-Cl-KYNA. 4,6-Cl2-KYN also expressed affinity for the transporter, but four-fold less than that of 4-Cl-KYN. In summary, the results show that because of their facilitated uptake 4-Cl-KYN and 4,6-Cl2KYN might be useful prodrugs for brain delivery of glycine-NMDA receptor antagonists.