[A preliminary study on the efficacy and safety of a new type of trabeculotome tunnelling trabeculoplasty for open-angle glaucoma].

Objective: To compare the efficacy and safety of trabeculotome tunnelling trabeculoplasty and gonioscopy-assisted transluminal trabeculotomy (GATT) in the treatment of open-angle glaucoma. Methods: A prospective randomized controlled study. The patients with open-angle glaucoma diagnosed in the ophthalmology center of Beijing Tongren Hospital affiliated to Capital Medical University from January to July 2022 were collected and divided into GATT group (undergoing GATT) and 3T group (undergoing 3T operation) using a random number table. Intraocular pressure (IOP) was recorded for both groups at 1 day, 1 week, 1 month, and 3 months after the operation, and the types and quantities of anti-glaucoma drugs used, postoperative complications, and surgical success rate were compared. Normal distribution measurement data were analyzed using independent sample t-tests, non-normal distribution measurement data were analyzed using non-parametric tests, and counting data were analyzed using chi-square tests. Results: This study included 35 patients (43 eyes), consisting of 27 males and 8 females, with an average age of (43.0±14.3) years. There were 21 patients (23 eyes) in the GATT group and 19 patients (20 eyes) in the 3T group. The maximum IOP without anti-glaucoma drugs before surgery, the highest IOP with the maximum number of anti-glaucoma drugs, and the IOP at 3 months after surgery in the GATT group were (33.5±9.1), (22.2±6.1), and (16.0±3.1) mmHg (1 mmHg=0.133 kPa), respectively. The corresponding values for the 3T group were (35.2±7.8), (21.5±6.8), and (16.1±2.0) mmHg. After surgery, the IOP in both groups was lower than before surgery, with a statistically significant difference (P<0.05) and no significant difference between the two groups (P>0.05). In the 3 months following surgery, 13 eyes in the GATT group and 11 eyes in the 3T group received more than two types of anti-glaucoma drugs, with no significant difference between the two groups (P>0.05). Three months after surgery, the complete and conditional success rates of the GATT group were 14/18 and 16/18, respectively, and those of the 3T group were 12/15 and 13/15, respectively, with no significant difference between the two groups (P>0.05). The incidence of hyphema, ciliary detachment, and shallow anterior chamber 1 day after surgery was 91%(21/23), 35%(8/23), and 30%(7/23), respectively, in the GATT group and 55%(11/20), 5%(1/20), and 0 in the 3T group, with a statistically significant difference between the two groups (P<0.05). Conclusion: 3T and GATT have similar success rates in the treatment of open-angle glaucoma. However, compared with GATT, 3T has fewer complications and is considered to be safer. (This article was published ahead of print on the Online-First Publishing Platform for Excellent Scientific Researches of Chinese Medical Association Publishing House on February 28, 2023).

[A study on the correlation between occupational radiation exposure and risk of chronic metoblis disease].

Objective: To study the correlation between occupational radiation exposure and chronic metabolic diseases. Methods: The status of chronic metabolic diseases of medical workers were compared in 5 hospitals in Hangzhou. As representatives of chronic metabolic diseases, diabetes and metabolic syndrome (MS) were compared in association with duration of radiation exposure. Results: Long-term ionizing radiation (IR) exposure was led to increased blood pressure, fasting blood glucose (FBG) , dyslipidemia, gallbladder disease, and MS. The years of radiation exposure was associated with lens opacity, gallstone and MS in men and gallbladder polyps in women. Radiation working more than 10 years is one of the independent risk factors for increased FBG and MS. Moreover, the risk of FBG increase in the group of radiation working more than 10 years was 3.052 times of that the non-exposed group, and the risk of MS occurrence was 4.132 times that of the non-exposed group. Conclusion: Long-term exposure to IR increases the risk of chronic metabolic diseases.

Metastatic pattern and prognosis of gastrointestinal stromal tumor (GIST): a SEER-based analysis.

PURPOSE: This SEER-based study aimed to explore and analyze the relationship of metastasis of liver, lung and bone of GIST patients and their prognosis. METHODS: The data of GIST patients were from Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2015 and all the statistical analyses were conducted by statistical software package SPSS (Version 22.0). RESULTS: A total of 4224 GIST patients were identified, of which 388 (9.19%) patients with liver metastasis, 20 (0.47%) patients with bone metastasis and 32 (0.76%) patients with lung metastasis. There was no significant difference of risk of bone or lung metastasis between patients with and without liver metastasis (P = 0.935). The median overall survival of patients with liver, bone, or lung metastasis was, respectively, 49 months, 18 months, and 20 months, which were all shorter than that of patients without metastasis. The overall survival of patients with both liver and bone metastasis and those with metastasis of all three sites was not significantly different from that of patients with only liver metastasis. The multivariate analysis showed age of less than 65 years, female patients, married status and receiving surgery were all the beneficial factors for prognosis of GIST patients with liver metastasis. CONCLUSIONS: Patients with metastasis had a poorer prognosis than those without. Liver metastasis might have no relationship with bone or lung metastasis and liver might play a more dominant role than the other two sites in the prognosis of GIST patients with metastasis. So, more attention should be paid to liver status in diagnosis and treatment of GIST patients.

Pioglitazone attenuates lipopolysaccharide-induced depression-like behaviors, modulates NF-κB/IL-6/STAT3, CREB/BDNF pathways and central serotonergic neurotransmission in mice.

Immune activation and inflammation are closely associated with the development of depression. Pioglitazone (PIO), a peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist, has exhibited antidepressant-like effects in a couple of studies. However, the underlying mechanisms are far from being fully elucidated. The study aimed to investigate the effects of PIO on depression-like behaviors induced by lipopolysaccharide (LPS) and to explore the possible underlying mechanisms. The results showed that PIO pretreatment attenuated the depression-like behaviors in mice challenged with intracerebroventricular (i.c.v.) LPS administration. Moreover, Western blot analysis revealed the effects of PIO on inhibiting activation of the nuclear factor kappa B/interleukin 6/signal transducer and activator of transcription 3 (NF-κB/IL-6/STAT3) pathway, improving down-regulation of the cAMP response-element-binding protein/brain derived neurotrophic factor (CREB/BDNF) pathway, as well as regulating disturbed expression of proteins involved in central serotonergic neurotransmission following LPS administration. The beneficial effects of PIO, at both the behavioral and molecular level, were significantly inhibited by the PPAR-γ specific antagonist GW9662. In summary, our data reveals for the first time that the modulation of the NF-κB/IL-6/STAT3 and CREB/BDNF pathways, as well as the potential impact on central serotonergic neurotransmission, may be involved in the PPAR-γ-dependent effects of PIO on depression-like behaviors induced by LPS. Additionally, our findings may provide a novel therapeutic target for the treatment of depression-like behaviors in patients with inflammatory status.

IL-17 rs2275913 genetic variation contributes to the development of gastric cancer in a Chinese population.

The purpose of this hospital-based case-control study was to assess whether the interleukin (IL)-17 rs2275913 genetic variation can influence susceptibility to gastric cancer. Samples from a total of 202 gastric cancer patients and 237 controls were collected from the Linyi People's Hospital between March 2013 and March 2015. The IL-17 rs2275913 gene polymorphism was identified by polymerase chain reaction and restriction fragment length polymorphism. When compared with control subjects, gastric cancer patients were older in age (OR = 3.89, 95%CI = 2.55-5.95), male (OR = 2.08, 95%CI = 1.39-3.10), had a habit of alcohol consumption (OR = 1.71, 95%CI = 1.15-2.55), and were more likely to be infected with Helicobacter pylori (OR = 2.76, 95%CI = 1.83-4.16). We observed that the AA genotype of the IL-17 rs2275913 polymorphism resulted in a 2.32-fold risk of gastric cancer compared to the GG genotype (OR = 2.32, 95%CI = 1.20-4.54; P = 0.01). The AG combined with AA genotype of the IL-17 rs2275913 polymorphism had more risk of developing gastric cancer than the GG genotype (OR = 1.50, 95%CI = 1.01-2.23; P = 0.04). Moreover, the AA genotype of the IL-17 rs2275913 polymorphism was correlated with a higher risk of developing gastric cancer than the GG and AG genotypes combined (OR = 2.01, 95%CI = 1.08-3.79; P = 0.02). In conclusion, the results of our study suggest that the IL-17 rs2275913 polymorphism could contribute to the risk of gastric cancer.

Lenalidomide affect expression level of cereblon protein in multiple myeloma cell line RPMI8226.

We investigated the mechanisms of action of immuno-modulatory drug (lenalidomide) on the protein expression of cereblon (CRBN) and their therapeutic targets in the multiple myeloma cell line RPMI8226. The multiple myeloma cell line RPMI8226 was cultured and treated with different concentrations of lenalidomide and bortezomib to determine the proliferation inhibition rate, apoptosis rate, and protein expression of CRBN. The results revealed that both lenalidomide and bortezomib inhibited the proliferation of RPMI8226 and promoted cell apoptosis. However, the protein expression of CRBN decreased signifi-cantly after treatment with lenalidomide, while bortezomib had no effect on the expression of CRBN. We confirmed that CRBN may be a target of lenalidomide.

Effect of levitra on sustenance of erection (EROS): an open-label, prospective, multicenter, single-arm study to investigate erection duration measured by stopwatch with flexible dose vardenafil administered for 8 weeks in subjects with erectile dysfunction.

To investigate the change of erection duration measured by stopwatch with flexible dose vardenafil administered for 8 weeks in subjects with erectile dysfunction (ED). Effect of levitra on sustenance of erection was an open-label, prospective, multicenter and single-arm study designed to measure the duration of erection in men with ED receiving a flexible dose of vardenafil over an 8-week treatment period. Patients were instructed to take vardenafil 10 mg 60 min before attempting the intercourse. Vardenfil could be increased to 20 mg or decreased to 5 mg concerning patients' efficacy and safety. Following the initial screening, patients entered a 4-week treatment-free run-in phase and 8-week treatment period, during which they were instructed to attempt intercourse at least four times on four separate days. A total of 95 men were enrolled in 10 centers. After the 8 weeks treatment, the mean duration of erection leading to successful intercourse was statistically superior when patients were treated with vardenafil. After an 8-week treatment, the duration of erection leading to successful intercourse was 9.39 min. There were significant benefits with vardenafil in all domains of International Index of Erectile Function. Secondary efficacy end points included success rate of penetration, maintaining erection, ejaculation and satisfaction were superior when patients were treated with vardenafil. There was a significant correlation between duration of erection with other sexual factors. Also partner's sexual satisfaction was increased with vardenafil. Most adverse events were mild or moderate in severity. Vardenafil was safe and well tolerated. Vardenafil therapy provided a statistically superior duration of erection leading to successful intercourse in men with ED with female partner.

Genetic characteristics of Chinese isolates of the tapeworm Taenia pisiformis based on two mitochondrial genes.

Cysticercosis is caused by infections with embryonated eggs of the tapeworm Taenia pisiformis. Knowledge of the genetic characteristics of T. pisiformis could be applied to study the epidemiology and transmission of this parasite. In this study, 61 isolates of intraperitoneal cysticerci from eight geographically distinct regions in Sichuan province, China, were subjected to a molecular analysis in order to determine their intra-regional genetic characteristics. Partial sequences of the mitochondrial cytochrome c oxidase subunit I (cox1, 1427 bp) and NADH dehydrogenase 1 (nad1, 738 bp) were concatenated. Five haplotypes were identified, and 89.04% of total genetic variation was found in collections of T. pisiformis isolates from a single region. According to the phylogenetic reconstruction, the T. pisiformis isolates from eight regions did not form geographical clusters. Our study highlights the genetic characteristics of T. pisiformis with the aim of accelerating the genetic research and control of cysticercosis.

Protection against Taenia pisiformis larval infection induced by a recombinant oncosphere antigen vaccine.

Taenia pisiformis larvae cause significant health problems to rabbits. At present, it is not known whether the recombinant antigen from the T. pisiformis oncosphere is able to confer protective immunity against T. pisiformis larval infection. The full-length cDNA was cloned into a pET32a (+) vector, and the recombinant protein was then expressed in BL21 (DE3) cells. Vaccination with the purified rTpUbc2 coupled with QuilA was carried out in New Zealand rabbits to evaluate the immunoprotective effect against T. pisiformis infection. The full-length open reading frame of the TpUbc2 gene was 444 bp, and encoded a 16.63-kDa protein. Finally, rTpUbc2 was used to evaluate the ability to induce immunoprotective responses in rabbits. A 79.3-90.8% reduction (P < 0.01) in the recovery of larvae was observed in the experimental group compared to the control group. Specific anti-rTpUbc2 antibodies from immunized rabbits had significantly higher levels of IgG (P < 0.01) compared to the control group; however, no significant difference in IgA levels was found between groups (P > 0.05). Our data support the use of rTpUbc2 as a potential candidate to develop a vaccine against T. pisiformis larvae.

Efficacy and safety of the simultaneous administration of mirodenafil and an α-blocker in men with BPH-LUTS: a multicenter open-label prospective study.

We evaluated the clinical efficacy and safety of the coadministration of a PDE5 inhibitor and an α-adrenergic blocker in patients with both benign prostatic hyperplasia/lower urinary tract symptoms (BPH-LUTS) and ED using mirodenafil 50 mg (Mvixx) once daily (OD) in patients already receiving stable α-blocker therapy. This study was a prospective, multicenter, open-label trial. We selected 147 patients undergoing stable (longer than 4 weeks) α-blocker therapy for BPH-LUTS as recipients of the additive mirodenafil 50 mg OD for 8 weeks. The coprimary measures were the International Prostate Symptom Score (IPSS) and the International Index of Erectile Function (IIEF-5). The key secondary measures were peak flow rate (Qmax) and postvoiding residual (PVR) volume. Safety was assessed by evaluating cardiovascular parameters and the participant-reported treatment-emergent adverse events (TEAEs). The additional administration of mirodenafil 50 mg OD significantly improved IPSS results (18.70-14.30 at 4 weeks and 18.70-13.72 at 8 weeks; P<0.001). The IIEF-5 score was improved at 8 weeks (10.94-16.16; P<0.001). There was no significant change in systolic blood pressure/diastolic blood pressure (124.8 mm Hg/78.6 mm Hg-122.0 mm Hg/79.6 mm Hg; P=0.638) and heart rates (78.8 per min to 80.2 per min; P=0.452). The most common TEAEs were hot flashes (10.9%) and headache (8.1%). The combination of mirodenafil with an α-blocker did not significantly improve PVR; however, Qmax was improved at 8 weeks (14.51-16.80 ml s(-1); P=0.026). Mirodenafil 50 mg OD in combination with an α-blocker appeared to have few adverse effects, to improve BPH-LUTS and restore sexual function.

A randomized phase II of gemcitabine and sorafenib versus sorafenib alone in patients with metastatic pancreatic cancer.

PURPOSE: Patients with metastatic pancreatic cancer have limited therapeutic options. The role of the Ras-Raf-MAPK pathway and of vascular endothelial growth factor in pancreatic carcinogenesis provided the rational to evaluate the efficacy of sorafenib with or without gemcitabine in a randomized phase II study. METHODS: Patients with metastatic pancreatic cancer were randomized to sorafenib alone (arm A) or sorafenib with gemcitabine (arm B). RESULTS: Arm A was closed to accrual at interim analysis due to the lack of objective response. Median PFS and OS were 2.3 and 4.3 months respectively. There was one partial response among the 37 patients in arm B. Median PFS and OS were 2.9 and 6.5 months respectively. There were more grade 3 and 4 toxicities in arm B with the most common being neutropenia (17%), thrombocytopenia (8%), alkaline phosphatase elevation (14%), venous thromboembolism (8%), diarrhea, hypokalemia and ALT elevation (5%) each. Several associations were noted between single nucleotide polymorphisms in ribonucleotide reductase, Cox-2, vascular endothelial growth factor and survival in patients treated with gemcitabine and sorafenib. CONCLUSIONS: Neither sorafenib alone or sorafenib in combination with gemcitabine manifested promising activity in metastatic pancreatic cancer.

Comparison of cadaveric pericardial, dermal, vein, and synthetic grafts for tunica albuginea substitution using a rat model.

OBJECTIVE: To evaluate in an animal model the intermediate and long-term efficacy of cadaveric pericardium, dermis, vein and Gore-Tex per thousand as grafting materials for tunica albuginea substitution after plaque excision for Peyronie's disease. MATERIALS AND METHODS: The study comprised 100 male Sprague-Dawley rats (300-325 g) divided into five equal groups: group 1, sham-operated controls; and groups 2-5 which underwent wedge excision of the tunica albuginea and replacement with either cadaveric pericardium, dermis, vein or Gore-Tex grafts. Ten rats in each group had the cavernosal nerve stimulated electrically to assess erectile function at 4 months, and the remaining 10 rats at 6 months. After death the sampled tissues were fixed in 10% formalin, paraffin-embedded, and stained with Masson's trichrome and Verhoff's van Giesen for collagen and elastic fibres. RESULTS: Erectile function, assessed by cavernosal nerve stimulation, did not differ significantly in any of the groups (P > 0.05). The histological assessment of penile cross-sections showed minimal fibrosis surrounding the patch in the dermal and vein grafts, and moderate to severe fibrosis in the Gore-Tex graft at 4 and 6 months. In the pericardial graft there was a moderate degree of fibrosis at 4 months with only minimal fibrosis at 6 months. CONCLUSIONS: These results show that cadaveric pericardium allows complete penile expansion and is strong enough to withstand normal intracorporal pressures. There was minimal fibrosis in the pericardial, dermal and vein grafts, and moderate fibrosis in the Gore-Tex graft at 6 months. The pericardial graft is a satisfactory grafting material when used for tunica albuginea substitution, including the surgical management of Peyronie's disease.

Snakebite complicated with Vibrio vulnificus infection.

Snakebite may be complicated with bacteria infections, most of which are Gram-negative bacillus. Snakebite complicated with Vibrio vulnificus infection has not been reported previously. Vibrio vulnificus infection is characterized by a necrotizing wound infection similar to the local lesion of severe snakebite. In Vibrio infections, aggressive debridement with the administration of strong antibiotics as early as possible is the only effective treatment. We report a 79-y-o man who suffered from snakebite on the right palm with rapid progression of hemorrhagic bulla, necrotizing fasciitis, compartment syndrome, and septic shock. Vibrio vulnificuswas cultured from necrotic tissue after aggressive debridement and fasciotomy. The patient recovered from antibiotic treatment and several courses of reconstruction surgery. Severe bacteria infection, such as caused by Vibrio vulnificus, should be considered in snakebite cases refractory to antivenin dosage.

Fatal poisoning by butachlor and chlornitrofen ingested from a bottle marked as nitrofen.

Nitrofen has been banned in Taiwan since January 1, 1983 due to its tetrogenicity. A 78-y-o female consumed about 500 ml of herbicide, labeled as nitrofen, in a suicide attempt. Consciousness disturbance occurred immediately. After 9 h, bloody-tarry stool was noted. Hematemesis occurred 19 h later. Hepatotoxicity and nephrotoxicity also developed. Twitching of head and both upper extremities lasting 20-30 sec and up to 5 min developed on day 3. Sometimes an upward gaze with the face turned to the right or a convulsion of the right upper extremity was observed. EEG showed alpha coma, generalized slow spike-and-wave complexes, and isolated generalized sharp waves mainly in the left occipital area. On day 7, endotracheal intubation was performed due to apnea; she expired on day 9. The pesticide was found to contain butachlor and chlornitrofen. The Agricultural Committee prohibited the marketing of chlornitrofen due to its generation of tumors in animals. The combination of butachlor and chlornitrofen can result in consciousness disturbance, leucocytosis, gastrointestinal hemorrhage, rhabdomyolysis, hypocalcemia, hypoalbuminemia, elevated amylase, nephrotoxicity, hepatotoxicity, seizures and death. The cytotoxicity of butachlor may be related to the patient's death. Active components of pesticides should be checked if the clinical course of a poisoned patient is unusual to allow appropriate interventions.

Evaluation of nitric oxide synthase and arginase in the induction of a Peyronie's-like condition in the rat.

Peyronie's disease is an idiopathic, localized connective tissue disorder of the penis, involving the tunica albuginea of the corpus cavernosum and adjacent areolar space. Current proposals as to the origin of Peyronie's disease suggest that fibrosis and collagen changes of the tunica are the result of an inflammatory process following vascular trauma. Our laboratory and other investigators have recently proposed an animal model for the study of Peyronie's disease. When transforming growth factor-beta1 (TGF-beta1) was injected into the rat tunica albuginea, tissue fibrosis was observed at 6 weeks. Therefore, our aim was to assess arginase II, endothelial and inducible nitric oxide synthase isoforms, and nitrotyrosine levels--all factors involved in inflammatory reactions--in the cavernosal tissue of saline-injected and TGF-beta1-injected rats after 6 weeks in order to evaluate the roles these enzymes may play in the induction of a Peyronie's-like condition in the rat. To examine the expression of endothelial nitric oxide synthase (eNOS), iNOS, and arginase II protein, and mRNA in the corpus cavernosum, immunoblot analysis, and reverse transcriptase-polymerase chain reaction were performed. We also determined immunohistochemically the expression of nitrotyrosine, a marker of peroxynitrite formation, in the rat penis. After 6 weeks, iNOS protein and gene expression was up-regulated and eNOS protein and gene expression was down-regulated in the corpora cavernosa of the TGF-beta1-injected penises. Furthermore, arginase II protein expression as well as immunohistochemical localization of nitrotyrosine was significantly higher in the TGF-beta1-injected corpora cavernosa. These results suggest that iNOS is the key control element for peroxynitrite formation, arginase II expression, and eNOS down-regulation in the induction of a Peyronie's-like condition in the rat.

Efficacy of endoscopic isotonic saline-epinephrine injection for the management of active Mallory-Weiss tears.

Therapeutic endoscopy with isotonic saline-epinephrine (ISE) injection is a convenient and widely used procedure for hemostasis in upper gastrointestinal bleeding. We retrospectively evaluated 36 patients (from January 1996 to April 1999) who had been diagnosed with recent or active bleeding due to Mallory-Weiss tears in emergency endoscopic examination. The endoscopic hemostatic method with ISE injection was performed in 15 of 36 patients. The other 21 patients received conservative treatment with hemodynamic support. Patient's clinical data, laboratory data, transfusion requirements, endoscopic findings, and length of hospital stays were evaluated. Initial hemoglobin was significantly lower in the ISE group than the conservative treatment group (9.74 +/- 2.86 g/dL vs. 12.57 +/- 2.80 g/dL, respectively; p < 0.01). Mean transfusion requirements were significantly higher in the ISE group than the conservative treatment group (7.26 +/- 8.78 units vs. 2.85 +/- 6.21 units, respectively; p < 0.1). Patients in the ISE group were supposed to be having a more severe bleeding episode. Most patients achieved initial hemostasis in the ISE group and the conservative treatment group (93% and 95%, respectively). The rebleeding rate was also similar in both groups (1 in 15 in the ISE group and I in 21 in the conservative treatment group). There was no significant difference in length of hospital stay and rebleeding between these two groups (3.47 +/- 1.92 days vs. 2.47 +/- 1.47 days, respectively: p = 0.89). The endoscopic ISE injection is an inexpensive, simple, convenient therapeutic method and it can achieve initial hemostasis for active Mallory-Weiss tears.

Acute myocardial infarction caused by aortic dissection.

Clinical presentation of aortic dissection is similar to that of acute myocardial infarction (AMI). Clinical differential diagnoses from lethal chest pain in emergency department include AMI, aortic dissection, pulmonary embolism, tension pneumothorax, etc. Thrombolytic therapy for recanalization of thrombotic occluded coronary artery in AMI must be considered, but it is absolutely contraindicated for aortic dissection. However, AMI secondary to aortic dissection is a rare condition, which might be caused by compression of the coronary arteries by a hematoma or extension of the dissection into the coronary arterial wall. Surgery is the first choice for AMI secondary to aortic dissection caused by extension of dissection into the coronary arterial wall. We present a case of inferior wall AMI caused by type I aortic dissection with presentation of chest pain and hemiparaplegia of right lower limb.

Determination of catecholamines in pheochromocytoma cell (PC-12) culture medium by microdialysis-microbore liquid chromatography.

An in vitro microdialysis system was constructed for the measurement of catecholamines in pheochromocytoma cell culture medium. The novel microdialysis device is composed of a petri dish, a dialysis membrane and two transmission tubes. The dialysis membrane is located in the space of a petri dish such that it is immersed in the culture medium. Catecholamines contained in the culture medium diffused into a designed dialysis membrane with sufficient recovery (about 60%). Dialysates were collected by a sampling loop and introduced by an on-line injector to a microbore liquid chromatographic system for analysis of catecholamines. This assay yielded a detection limit of 0.2-0.5 pg/injection with acceptable intra- and inter-assay reproducibilities in 5 microl of dialysates. To evaluate the on-line microdialysis system, PC-12 cells were cultured in a petri dish within an incubator. The baseline concentration of dopamine in PC-12 cell culture medium was about 0.29 ng/ml which was elevated to 2.43 ng/ml after treatment with 0.5 mM potassium cyanide. In conclusion, the present microassay provides for the sensitive, direct measurement of catecholamines in culture medium while minimizing pretreatment procedures for sample preparation.

Charge conductivity in peptides: dynamic simulations of a bifunctional model supporting experimental data.

Our previous finding and the given mechanism of charge and electron transfer in polypeptides are here integrated in a bifunctional model involving electronic charge transfer coupled to special internal rotations. Present molecular dynamics simulations that describe these motions in the chain result in the mean first passage times for the hopping process of an individual step. This "rest and fire" mechanism is formulated in detail-i.e., individual amino acids are weakly coupled and must first undergo alignment to reach the special strong coupling. This bifunctional model contains the essential features demanded by our prior experiments. The molecular dynamics results yield a mean first passage time distribution peaked at about 140 fs, in close agreement with our direct femtosecond measurements. In logic gate language this is a strongly conducting ON state resulting from small firing energies, the system otherwise being a quiescent OFF state. The observed time scale of about 200 fs provides confirmation of our simulations of transport, a model of extreme transduction efficiency. It explains the high efficiency of charge transport observed in polypeptides. We contend that the moderate speed of weak coupling is required in our model by the bifunctionality of peptides. This bifunctional mechanism agrees with our data and contains valuable features for a general model of long-range conductivity, final reactivity, and binding at a long distance.