Integrated label-free erbium-doped fiber laser biosensing system for detection of single cell Staphylococcus aureus

A critical challenge to realize ultra-high sensitivity with optical fiber interferometers for label free biosensing is to achieve high quality factors (Q-factor) in liquid. In this work a high Q-factor of 10⁵, which significantly improves the detection resolution is described based on a structure of single mode -core-only -single mode fiber (SCS) with its multimode (or Mach-Zehnder) interference effect as a filter that is integrated into an erbium-doped fiber laser (EDFL) system for excitation. In the case study, the section of core-only fiber is functionalized with porcine immunoglobulin G (IgG) antibodies, which could selectively bind to bacterial pathogen of Staphylococcus aureus (S. aureus). The developed microfiber-based biosensing platform called SCS-based EDFL biosensors can effectively detect concentrations of S. aureus from 10 to 10⁵ CFU/mL, with a responsivity of 0.426 nm wavelength shift in the measured spectrum for S. aureus concentration of 10 CFU/mL. The limit of detection (LoD) is estimated as 7.3 CFU/mL based on the measurement of S. aureus with minimum concentration of 10 CFU/mL. In addition, when a lower concentration of 1 CFU/mL is applied to the biosensor, a wavelength shift of 0.12 nm is observed in 10% of samples (1/10), indicating actual LoD of 1 CFU/mL for the proposed biosensor. Attributed to its good sensitivity, stability, reproducibility and specificity, the proposed EDFL based biosensing platform has great potentials for diagnostics.

[Analysis of safety and efficacy of laparoscopic surgery for gallbladder carcinoma]

Objective: To examine the efficacy and safety of laparoscopic surgery for gallbladder carcinoma. Methods: The data of 197 gallbladder carcinoma patients admitted at Peking Union Medical College Hospital between January 2012 and September 2022 were analyzed retrospectively. There were 86 males and 111 females,with age of (64.4±9.8)years(range:35 to 89 years). Patients were divided into laparoscopic group(n=53) and open group(n=144) according to different surgical methods. The general information of the two groups were matched by propensity score matching,and the clinical data and prognosis were compared between the two groups. Categorical variables were analyzed using χ2 test or Fisher's exact test,as appropriate. Continuous variables with and without normal distribution were analyzed using t-test and Mann-Whitney U test,respectively. Kaplan-Meier curves with Log-rank test were used to analyze the cumulative survival rates. Results: Forty-eight pairs of patients were matched successfully. There was no difference in general information,cholecystolithiasis,partial hepatectomy,and tumor stage between two groups(all P>0.05). The laparoscopic group had shorter operation time(t=-3.987,P<0.01),less bleeding(Z=-4.862,P<0.01),shorter total(Z=-5.009,P<0.01) and postoperative(Z=-5.412,P<0.01) hospital stay. Seventeen patients had postoperative complications. According to the Clavien-Dindo system,there were 4,11,1,and 1 patient with grade Ⅰ,Ⅱ,Ⅲa,and Ⅲb,respectively. All complications were improved after active treatment. After a median follow-up of 24(36) months(range:3 to 130 months),56 patients(58.3%) survived without tumor,7 patients(7.3%) survived with tumor,and 33 patients(34.4%) died. According to the Kaplan-Meier curves,there was no significant difference between laparoscopic and open groups in disease free(χ2=0.399,P=0.528) and overall(χ2=0.672,P=0.412) survival rates. Conclusions: The laparoscopic surgery is safe and effective in selected patients with gallbladder carcinoma. It can reduce surgical trauma and enhance patient recovery without increasing complication. Its prognosis is similar to that of open surgery.

[Application of enhanced recovery after surgery in perioperative management of patients with gallbladder carcinoma]

Objective: To investigate the efficacy and safety of enhanced recovery after surgery (ERAS) in perioperative management of patients with gallbladder carcinoma. Methods: The data of the patients with gallbladder carcinoma admitted at Peking Union Medical College Hospital between January 2017 and December 2021 were analyzed retrospectively. There were 69 males(42.1%) and 95 females(57.9%),with age of (64.0±10.3) years(range:37 to 89 years). Patients were divided into ERAS group(n=53) and normal group(n=111) according to whether they were treated with ERAS measures during the perioperative period.The basic characteristics of the two groups were matched by propensity score matching,and then the perioperative information was compared between the two groups. Categorical variables were presented as absolute numbers or frequencies. Differences between study groups were analyzed using χ² test, Fisher's exact test, t-test, or Mann-Whitney U test, as appropriate. Results: Each group had 45 patients after propensity score matching with well-balanced basic characteristics. There was no difference in basic characteristics, operation time,bleeding,complication,and hospitalization expenses between two groups(all P>0.05). Compared with the normal group,time of ambulation (M(IQR)) (1(1) day vs. 2(2) days;Z=-3.839,P<0.01),postoperative anal exhaust time (2(1) days vs. 3(1) days;Z=-3.013,P=0.003),feeding time(2(1) days vs. 2(1) days;Z=-3.647,P<0.01),postoperative (5(2) days vs. 7(4) days;Z=-3.984,P<0.01) and total(8(4) days vs. 13(6) days;Z=-3.605,P<0.01) hospitalization time were shorter in ERAS group. Postoperative complications occurred in 12 patients. According to the Clavien-Dindo classification,6,4,and 2 patients were classified as grade Ⅰ,Ⅱ,and Ⅲa,respectively. Conclusion: The ERAS measures is safe and effective for perioperative management of patients with gallbladder carcinoma, enhancing patient recovery and shortening hospitalization time without increasing complication or hospitalization cost.

[Metrological Analysis of the Projects in the Field of Forensic Science Funded by the National Natural Science Foundation of China between 2000 and 2019]

Abstract

Objective To understand the trend of funding in the field of forensic science by analyzing the projects funded by the National Natural Science Foundation of China （NSFC）. Methods Based on the data of funded projects in the field of forensic science published on NSFC website in the twenty years from 2000 to 2019, the trend of project number and fund, project type, discipline type, funded institution and personnel were analyzed with metrological methods. The funding theme was analyzed through multi-methods. Results In the twenty years, NSFC funded 352 projects in the field of forensic science, including 9 project types, 47 institutions and 213 persons. General programs （184 projects）, forensic toxicology, pathology, and toxicology analysis （H2301, 188 projects）, and the Academy of Forensic Science （37 projects） had the most funded projects. NSFC funded 174.69 million yuan in the field of forensic science. The Excellent Young Scientists Fund （3.50 million yuan/project）, forensic toxicology, pathology, and toxicology analysis （H2301, 78.64 million yuan）, and Xi'an Jiaotong University （23.78 million yuan） had the most funding. The differences in the number and funding of subsidized projects between the first ten years and the last ten years had statistical significance （P<0.05）. The main targets of funding were toxicology research, evidence-related research, estimation-related research, brain injury research, et al. The field of research mainly funded from 2010 to 2019 was interdisciplinary research. Conclusion Since 2010, the number of project, funding of project, the number of institutions and persons funded by NSFC in the field of forensic science showed an increasing trend. The types of disciplines, types of projects and themes of projects are more diverse, which will promote the long-term development of basic forensic research in China.

[Clinical study on factor Ⅷ inhibitor in children with hemophilia A]

目的

探讨血友病A（HA）患儿凝血因子Ⅷ（FⅧ）抑制物产生的相关因素及抑制物产生前后出血与关节病表现的差异。

方法

对2015年1月至2018年8月河南省血友病管理中心登记收治的381例16岁以下HA患儿进行回顾性分析。

结果

381例HA患儿中，轻型116例（30.4%），中间型196例（51.4%），重型69例（18.1%）。FⅧ抑制物阳性患者54例（14.2%），高滴度、低滴度分别为22、32例。血友病家族史与FⅧ抑制物阳性相关[P<0.001，OR=3.299（95%CI 1.743~5.983）]；高强度暴露与FⅧ抑制物的产生相关[P=0.002，OR=2.587（95%CI 1.414~4.731）]。高强度暴露与高滴度FⅧ抑制物产生相关[P=0.001，OR=8.689（95%CI 2.464~30.638）]。54例HA患者产生抑制物后，总体关节年出血率、创伤性年出血率增加（z=−3.440，P=0.001；z=−2.232，P=0.026），而非关节年出血率、自发性年出血率与抑制物产生前比较差异无统计学意义（z=−1.342，P=0.180；z=−1.414，P=0.157）。关节超声评分较产生抑制物前差异无统计学意义（z=−0.632，P=0.527）。

结论

血友病家族史、高强度暴露可增加HA患儿发生FⅧ抑制物的风险，且高强度暴露可增加HA患者出现高滴度抑制物的风险。

Cloning and expression analysis of the follicle-stimulating hormone receptor (FSHR) gene in the reproductive axis of female yaks (Bos grunniens)

Follicle-stimulating hormone receptor (FSHR) plays a central role in promoting follicle maturation through the follicle-stimulating hormone (FSH)-mediated cAMP pathway in animals. The objectives of the present study were to clone the FSHR gene of yaks (Bos grunniens) and compare differences in FSHR mRNA expression in the reproductive axis between yaks and cattle. Hypothalamus, anterior pituitary, oviduct, ovary, and uterus tissue samples were collected from adult female yaks (n = 5) and cattle (n = 5) during the follicular phase. Using reverse transcriptase-polymerase chain reaction (RT-PCR), we found that the FSHR coding region of the yak is 2088 bp and encodes 695 amino acids. Its amino acid sequence showed 99.38%-72.22% similarity to the homologous genes of cattle, goats, sheep, cats, donkeys, horses, humans, chickens, monkeys, mice, rats, and wild boar. Real-time PCR analysis revealed that the FSHR gene was expressed in all tissues examined. Expression of the FSHR gene in the yak was higher in the uterus than other tissues (P < 0.05) but, in cattle, was higher in the ovary than other tissues (P < 0.05). The FSHR gene expression level in the cattle ovary was significantly higher than that in the yak ovary (P < 0.01). These results indicate that the FSHR gene is relatively conserved in the course of animal evolution. The variation in sequence and expression level of FSHR between the two species might be associated with the difference in their reproduction.

Evaluation and Countermeasures of the Implementation of Forensic Clinical Identification Standards Based on the Perspective of Accreditation

Abstract

The new Standardization Law, implemented in 2018, has added a standard post-implementation evaluation system, aiming to continuously improve the quality of standards through post-implementation evaluation. Standards in the forensic science field are closely related to accreditation activities. Forensic science standards are not only the criteria on which accreditation activities are carried out, but also one of the key contents of the inspection of forensic science institutions in accreditation activities. Since 2018, the certification and accreditation policies in the forensic science field have also been changed, which has brought impacts on the construction of a standard system based on accreditation.This paper analyzes the standard data from China National Accreditation Center from Conformity Assessment on forensic clinical identification accreditation assessment. It points out that the current coverage of laboratory accreditation activities is limited, the development in different provinces is unbalanced, and there is overlap and crossover in the standards in use. It is emphasized that the construction of the national forensic science standardization technical committee, the improvement of the forensic science standard system, the establishment of the standard implementation evaluation index system, and promotion of the coordination of standards, and the certifications and accreditations should be accelerated, in order to continue to promote the standardization and accreditation activities in the field of forensic science.

[Clinical characteristics of abdominal solitary fibrous tumor: an analysis of 18 cases]

Objective: To summarize the clinical manifestations, pathological features, diagnosis, and treatment of abdominal solitary fibrous tumor (SFT). Methods: The data of clinical manifestations, pathological features, diagnosis, and treatment of 18 patients with abdominal SFT admitted to Department of General Surgery, Peking Union Medical College Hospital between January 2000 and December 2016 were retrospectively reviewed. Results: Abdominal mass was first presented in 14 patients. The blood routine, liver, kidney, and coagulation function were normal in all the patients. Tumor markers were abnormal in 4 cases. Most SFT showed hypoechoic mass with regular shape under ultrasound. CT findings differed among the cases. All the 18 patients underwent surgical treatment, and the diagnosis was proved by the postoperative histopathology. SFT differed in general morphology. The positive rate of Ki-67, smooth muscle actin (SMA), CD34, and S-100 was high under immunohistochemistry. Conclusions: Early diagnosis of abdominal SFT is difficult, leading to a low preoperative diagnosis rate. Complete removal of the tumor is the only reliable method of radical treatment.

[The efficiency of different biliary cannulation in endoscopic retrograde cholangiopancreatography: a meta-analysis]

Objective: To compare the success rates of wire-guided biliary cannulation (WGC) and conventional cannulation (CC) and their effect on the outcome of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). Methods: All randomized controlled trials (RCTs) were collected by searching CNKI, WanFang Data, CBM, PubMed, Embase and Cochrane Library.The assessment of methodological quality and data extraction of the included studies were performed independently by two reviewers. Meta-analysis was conducted with RevMan 5.2 software. Results: Ten RCTs, with a total of 3 262 patients enrolled, were retrieved.Meta-analysis demonstrated that WGC had a higher success rate(RR=1.04, 95%CI 1.01-1.06, P<0.01)and a lower risk of PEP after cannulation (RR=0.54, 95%CI 0.41-0.71, P<0.01). The main reason for the lower risk of PEP was due to lower proportion of mild PEP patients after WGC(RR=0.52, 95%CI 0.36-0.73, P<0.01), while the incidence of modest and severe PEP was comparable in the two groups(modest group: RR=0.84, 95%CI 0.43-1.64, P=0.61; severe group: RR=0.53, 95%CI 0.22-1.31, P=0.17). Conclusion: WGC may increase the success rate of cannulation and reduce the incidence of PEP because of less complications of mild PEP.

Impact of phase on collision between vortex solitons in three-dimensional cubic-quintic complex Ginzburg-Landau equation

We present a systematic analysis for three generic collisional outcomes between stable dissipative vortices with intrinsic vorticity S = 0, 1, or 2 upon variation of relative phase in the three-dimensional (3D) cubic-quintic complex Ginzburg-Landau equation. The first type outcome is merger of the vortices into a single one, of which velocity can be effectively controlled by relative phase. With the increase of the collision momentum, the following is creation of an extra vortex, and its velocity also increases with growth of relative phase. However, at largest collision momentum, the variety of relative phase cannot change the third type collisional outcomes, quasielastic interaction. In addition, the dynamic range of the outcome of creating an extra vortex decreases with the reduction of cubic-gain. The above features have potential applications in optical switching and logic gates based on interaction of optical solitons.

Continuous emission of fundamental solitons from vortices in dissipative media by a radial-azimuthal potential

We report novel dynamical regimes of dissipative vortices supported by a radial-azimuthal potential (RAP) in the 2D complex Ginzburg-Landau (CGL) equation with the cubic-quintic nonlinearity. First, the stable solutions of vortices with intrinsic vorticity S = 1 and 2 are obtained in the CGL equation without potential. The RAP is a model of an active optical medium with respective expanding anti-waveguiding structures with m (integer) annularly periodic modulation. If the potential is strong enough, m jets fundamental of solitons are continuously emitted from the vortices. The influence of m, diffusivity term (viscosity) β, and cubic-gain coefficient ε on the dynamic region is studied. For a weak potential, the shape of vortices are stretched into the polygon, such as square for m = 4. But for a stronger potential, the vortices will be broke into m fundamental solitons.

Phase controlling of collisions between solitons in the two-dimensional complex Ginzburg-Landau equation without viscosity

We present a systematic analysis of the outcome of soliton collisions upon variation of the relative phase φ of the solitons, in the two-dimensional cubic-quintic complex Ginzburg-Landau equation in the absence of viscosity. Three generic outcomes are identified: merger of the solitons into a single one, creation of an extra soliton, and quasielastic interaction. The velocities of the merger soliton and the extra soliton can be effectively controlled by φ. In addition, the range of the outcome of creating an extra soliton decreases to zero with the reduction of gain or the increasing of loss. The above features have potential applications in optical switching and logic gates based on interaction of optical solitons.

Continuous generation of "light bullets" in dissipative media by an annularly periodic potential

We report novel dynamical regimes of "light bullets" supported by an annularly periodic potential in the three-dimensional (3D) complex Ginzburg-Landau equation with the cubic-quintic nonlinearity. This is a model of an active optical medium with respective expanding anti-waveguiding structures with m≥2 (integer) annularly periodic modulation. If the potentials are strong enough, they give rise to continuous generation of m jets light bullet by an initial light bullet initially placed at the center. The influence of m and diffusivity term (viscosity) β on the corresponding strength of potential is studied. In the case of m = 0 (conical geometry), these are concentric waves expanding in the radial direction.

Role of HERG-like K(+) currents in opossum esophageal circular smooth muscle

An inwardly rectifying K(+) conductance closely resembling the human ether-a-go-go-related gene (HERG) current was identified in single smooth muscle cells of opossum esophageal circular muscle. When cells were voltage clamped at 0 mV, in isotonic K(+) solution (140 mM), step hyperpolarizations to -120 mV in 10-mV increments resulted in large inward currents that activated rapidly and then declined slowly (inactivated) during the test pulse in a time- and voltage- dependent fashion. The HERG K(+) channel blockers E-4031 (1 microM), cisapride (1 microM), and La(3+) (100 microM) strongly inhibited these currents as did millimolar concentrations of Ba(2+). Immunoflourescence staining with anti-HERG antibody in single cells resulted in punctate staining at the sarcolemma. At membrane potentials near the resting membrane potential (-50 to -70 mV), this K(+) conductance did not inactivate completely. In conventional microelectrode recordings, both E-4031 and cisapride depolarized tissue strips by 10 mV and also induced phasic contractions. In combination, these results provide direct experimental evidence for expression of HERG-like K(+) currents in gastrointestinal smooth muscle cells and suggest that HERG plays an important role in modulating the resting membrane potential.

Monochloramine directly modulates Ca(2+)-activated K(+) channels in rabbit colonic muscularis mucosae

BACKGROUND & AIMS

Mesenteric ischemia, infection, and inflammatory bowel disease may eventuate in severe colitis, complicated by toxic megacolon with impending intestinal perforation. Monochloramine (NH(2)Cl) is a membrane-permeant oxidant generated during colitis by the large amount of ambient luminal NH(3) in the colon. Reactive oxygen metabolites can modulate smooth muscle ion channels and thereby affect colonic motility, which is markedly impaired in colitis.

METHODS

Effects of NH(2)Cl on ionic currents in the innermost smooth muscle layer of the colon, the tunica muscularis mucosae, were examined using the patch clamp technique. Membrane potential in whole tissue strips was measured using high-resistance microelectrodes.

RESULTS

Whole cell voltage clamp experiments showed that NH(2)Cl (3-30 micromol/L) enhanced outward currents in a dose-dependent manner, increasing currents more than 8-fold at a test potential of +30 mV. Tail current analysis showed that the currents enhanced by NH(2)Cl were K(+) currents. Inhibition by tetraethylammonium and iberiotoxin suggested that these currents represented activation of large-conductance, Ca(2+)-activated K(+) channels. The membrane-impermeant oxidant taurine monochloramine, however, had no effect on whole cell currents. Single-channel studies in inside-out patches showed that NH(2)Cl increased open probability of a 257-pS channel in symmetrical (140 mmol/L) K(+). In the presence of NH(2)Cl, the steady-state voltage dependence of activation was shifted by -22 mV to the left with no change in the single-channel amplitude. The sulfhydryl alkylating agent N-ethylmaleimide prevented NH(2)Cl-induced channel activation. NH(2)Cl also hyperpolarized intact muscle strips, an effect blocked by iberiotoxin.

CONCLUSIONS

NH(2)Cl, at concentrations expected to be found during colitis, may contribute to smooth muscle dysfunction by a direct oxidant effect on maxi K(+) channels.

Substance P inhibits pancreatic exocrine secretion via a neural mechanism

We investigated the effects of the sensory neuropeptide substance P (SP) on amylase and fluid secretion in the isolated vascularly perfused rat pancreas. SP inhibited CCK-induced amylase release and secretin-induced juice flow via the pancreatic duct in a dose-related fashion. Threshold inhibition occurred following addition of 10(-10) M SP to the perfusate, and maximal inhibition was seen with 10(-8) M SP. The effects of SP were partially blocked by both the neurokinin-1 (NK1) and neurokinin-2 (NK2) receptor antagonists. Atropine and TTX blocked SP-induced effects on both amylase secretion (26 and 63% blockade, respectively) and pancreatic juice flow (21 and 79% blockade, respectively). Excitation of pancreatic sensory nerves using capsaicin (in the absence of SP) inhibited both amylase and pancreatic juice flow via activation of the NK1 receptor. We conclude that SP inhibits exocrine secretion via an indirect neural mechanism.

Evidence for NO. redox form of nitric oxide as nitrergic inhibitory neurotransmitter in gut

A nitric oxide (NO)-like product of the L-arginine NO synthase pathway has been shown to be a major inhibitory neurotransmitter that is involved in the slow component of the inhibitory junction potential (IJP) elicited by stimulation of nonadrenergic, noncholinergic nerves. However, the exact nature of the nitrergic transmitter, the role of cGMP, and the involvement of a potassium or a chloride conductance in the slow IJP remain unresolved. We examined the effects of soluble guanylate cyclase inhibitors LY-83583 and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), potassium-channel blockers and putative chloride-channel blockers diphenylamine-2-carboxylate (DPC) and niflumic acid (NFA) on the hyperpolarization elicited by an NO. donor, diethylenetriamine/NO adduct (DNO), NO in solution, and an NO+ donor, sodium nitroprusside (SNP), in the guinea pig ileal circular muscle. Effects of these blockers on purinergic (fast) and nitrergic (slow) IJP were also examined. DNO-induced hyperpolarization and nitrergic slow IJP were suppressed by LY-83583 or ODQ and DPC or NFA but not by the potassium-channel blocker apamin. In contrast, hyperpolarization caused by SNP or solubilized NO gas and purinergic fast IJP were antagonized by apamin but not by inhibitors of guanylate cyclase or chloride channels. These results demonstrate biological differences in the actions of different redox states of NO and suggest that NO. is the nitrergic inhibitory neurotransmitter.

Neuronal constitutive nitric oxide synthase is involved in murine enteric inhibitory neurotransmission

Mice lacking neuronal nitric oxide synthase gene (ncNOS) were used to determine the enzymatic source of nitric oxide (NO) and its relationship with other putative inhibitory neurotransmitters. Inhibitory junction potentials (IJP) of circular smooth muscle of gastric fundus were studied. The IJP in the wild-type mice consists of overlapping components, the fast and slow IJPs. NOS inhibitor L-NA or VIP receptor antagonist VIP(10-28), blocks the slow IJP but not the fast IJP. The fast UP is blocked by alpha-beta methylene ATP tachyphylaxis, by reactive blue 2, and by apamin. The IJP in the ncNOS-deficient [ncNOS(-)] mutant is of short duration and is abolished by blockers of the fast IJP, but is unaffected by blockers of the slow UP. Exogenous VIP produces membrane hyperpolarization in strips from wild-type but not ncNOS(-) mice. The hyperpolarizing action of VIP is resistant to nifedipine but is sensitive to omega-conotoxin GVIA.

IN CONCLUSION

(a) NO derived from ncNOS is an inhibitory neurotransmitter rather than a postjunctional mediator; (b) VIP is a prejunctional neurotransmitter that causes release of evanescent NO; and (c) ATP acts in parallel with the VIP/NO pathway.

[Experimental study on compatible application of heat-clearing and detoxifying drugs with blood circulation improving drugs]

The article describes the effectiveness of compatible application of heat-clearing and detoxifying drugs with blood circulation improving drugs to the animal model with endotoxemia and nonspecific inflammation. The compatible application reduces PGE2, endotoxin blood concentration and reduced viscosity of whole blood, decreases Evans blue extravasation volume and pes swelling percentage, increases serum cortisol content and enhances fibrinolytic activity. The experimental result shows that in most cases these two drugs work better when used in combination which implies that compatible application is more effective in detoxification, antiinflammation and inflammation recovery.

Nitric oxide involvement in the peptide VIP-associated inhibitory junction potential in the guinea-pig ileum

1. Intracellular membrane potential recordings were made from circular smooth muscle cells of the guinea-pig ileum in the presence of atropine (1 microM) and nifedipine (0.1 microM) at 30 degrees C. 2. Electrical field stimulation with one or four pulses produced a fast inhibitory junction potential (IJP) which lasted around 1 s. It was abolished by tetrodotoxin (1 microM), apamin (0.3 microM), and alpha, beta-methylene ATP tachyphylaxis. 3. Nitric oxide synthase inhibitor N-nitro-L-arginine (L-NNA; 200 microM) had no effect on the resting membrane potential or the fast IJP. 4. Electrical field stimulation in the presence of apamin and substance P desensitization produced a slow IJP which was abolished by tetrodotoxin (1 microM). 5. L-NNA significantly reduced the amplitude of the slow IJP (P < 0.01). The antagonistic effect of L-NNA was reversed by L-arginine but not by D-arginine. 6. Injections of alpha, beta-methylene ATP, nitric oxide (NO), and vasoactive intestinal polypeptide (VIP) into the recording chamber caused tetrodotoxin-resistant hyperpolarizations of the smooth muscle membrane. Substance P desensitization did not modify the amplitudes of the hyperpolarizing response to ATP or NO, but increased the VIP hyperpolarization by 150% (P < 0.01). 7. L-NNA did not modify the amplitude of hyperpolarization due to ATP or NO; however, it antagonized VIP-induced hyperpolarization (P < 0.01). 8. These studies show that in the guinea-pig ileum circular muscle: (a) NO is not involved in the fast IJP which is mediated by ATP; (b) NO is involved in the slow IJP which is mediated by VIP and NO acting in series, and (c) the hyperpolarizing effects of VIP and the slow IJP are normally masked by overlapping depolarization due to concomitant release of substance P by the peptide VIP.

Both ATP and the peptide VIP are inhibitory neurotransmitters in guinea-pig ileum circular muscle

1. Intracellular membrane potential recordings were made from circular smooth muscle cells of the guinea-pig ileum in the presence of atropine (1 microM) and nifedipine (0.1 microM) at 30 degrees C. 2. Perfusion with adenosine triphospate (ATP, 100 microM) and vasoactive intestinal peptide (VIP, 2 microM) resulted in membrane hyperpolarizations of 6.4 +/- 0.3 and 6.8 +/- 0.3 mV, respectively. Picospritzes of ATP (10 mM in pipette) and VIP (100 microM in pipette) resulted in membrane hyperpolarizations of 6.9 +/- 0.4 and 6.3 +/- 0.4 mV, respectively. 3. The ATP-induced hyperpolarizations were antagonized by alpha, beta-methylene ATP desensitization (100 microM for 30 min) and the ATP antagonist Reactive Blue 2 (200 microM), but were unaffected by the VIP antagonist VIP 10-28 (1 microM). 4. The VIP-induced hyperpolarizations were antagonized by VIP 10-28, but unaffected by alpha, beta-methylene ATP desensitization and Reactive Blue 2. 5. A single pulse of transmural nerve stimulation (2 ms, 15 mA) resulted in an inhibitory junction potential (IJP) that reached a maximal amplitude of 12.9 +/- 0.5 mV at 378 +/- 20 ms from the stimulus. This fast IJP was abolished by apamin (2 microM) or tetrodotoxin (1 microM), antagonized by alpha, beta-methylene ATP desensitization or Reactive Blue 2, but unaffected by VIP 10-28. 6. In the presence of apamin (1 microM), four pulses of transmural stimulation (2 ms, 20 Hz, 15 mA) resulted in an IJP that reached a maximal amplitude of 4.8 +/- 0.2 mV at 1.4 +/- 0.1 s from the stimulus. This slow IJP was antagonized by tetrodotoxin (1 microM) or VIP 10-28 (1 microM), augmented by Reactive Blue 2 (200 microM), and unaffected by alpha, beta-methylene ATP desensitization. 7. These findings provide evidence that both ATP and VIP are inhibitory neurotransmitters in the circular muscle layer of the ileum and that ATP may be the neurotransmitter responsible for the fast IJP and VIP the neurotransmitter responsible for the slow IJP.

Chloride-mediated inhibitory junction potentials in opossum esophageal circular smooth muscle

Intracellular recordings were made from circular smooth muscle cells of the opossum esophagus. Inhibitory junction potentials (IJPs) 8.3 +/- 0.7 mV in amplitude were observed in response to a single pulse (1 ms, 15 mA) of transmural nerve stimulation. Potassium channel blockers apamin (1 microM), tetraethylammonium (10 mM), 4-aminopyridine (250 microM), and cesium chloride (10 mM) did not reduce IJP amplitude. Conditioning hyperpolarizations to the equilibrium potential for potassium were associated with a significant increase in IJP amplitude. A small increase in membrane resistance was observed during the IJP. Changes in external potassium concentration had no significant effect on IJP amplitude acutely. However, prolonged perfusion with potassium-free Krebs solution resulted in a marked decrease in IJP amplitude as did prolonged perfusion with ouabain (0.1 mM). Low-chloride solution (12.4 mM) resulted acutely in an increase in IJP amplitude. Prolonged low-chloride perfusion resulted in a significant decrease in IJP amplitude. The anion exchange chloride channel inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (600 microM) significantly reduced IJP amplitude. These findings suggest that the IJP observed in opossum esophageal circular smooth muscle in response to a single pulse of stimulation is due to a decrease in membrane chloride conductance. The ability of prolonged application of Na-K pump inhibitors to abolish the IJP appears to be due to known secondary effects of these agents in depleting intracellular chloride.

Chloride-mediated junction potentials in circular muscle of the guinea pig ileum

Junction potentials were recorded from circular muscle cells of the guinea pig ileum at various sites oral and anal to a transmural stimulus in the presence of atropine, apamin, and substance P antagonism (desensitization) at 30 degrees C. A short train of pulses produced an inhibitory junction potential (slow IJP), which preceded an excitatory junction potential (slow EJP). The slow IJP was observed up to 56.4 +/- 2.9 mm oral and 65.4 +/- 2.2 mm anal to the stimulus. The slow EJP was observed up to 50.4 +/- 1.9 mm oral and 58.3 +/- 2.1 mm anal to the stimulus. Hexamethonium (400 microM) decreased the amplitudes of the slow IJP and slow EJP at all sites. After hexamethonium, the slow IJP was observed up to 37.3 +/- 2.3 mm oral and 39.8 +/- 2.1 mm anal to the stimulus and the slow EJP was 44.2 +/- 2.5 mm oral and 43.3 +/- 2.6 mm anal to the stimulus. The slow IJP and slow EJP were associated with an increase and decrease in membrane resistance, respectively. Conditioning depolarizations of the circular muscle cells reduced the amplitudes of the slow IJP and slow EJP. Both were abolished at a membrane potential of approximately -25 mV. Conditioning hyperpolarizations increased the amplitude of both the slow IJP and slow EJP. Ionic substitution experiments with low external chloride solution (12.4 mM) resulted in an immediate increase in slow IJP and slow EJP amplitudes, whereas more prolonged perfusion resulted in a significant decrease in slow IJP and slow EJP amplitudes. 4,4'-Diisothiocyanostilbene-2,2'-disulfonic acid (400 microM) resulted in decreases in slow IJP and slow EJP amplitudes. These results suggest that the slow IJP and slow EJP are due to a decrease and increase in membrane chloride conductance, respectively. The noncholinergic neural pathways responsible for the slow IJP and slow EJP extend approximately 40 mm orally and anally along the longitudinal axis of the guinea pig ileum.

The nature of noncholinergic membrane potential responses to transmural stimulation in guinea pig ileum

The effect of substance P antagonism on membrane potential responses to transmural nerve stimulation in the presence of atropine was examined in circular smooth muscle of the guinea pig ileum. Intracellular recordings of membrane potential responses recorded 3-5 mm oral to the transmural stimulus consisted of an inhibitory junction potential followed by two distinct depolarizations referred to as early and late excitatory junction potentials. Substance P antagonism was achieved by desensitization with high doses of substance P or use of the antagonist Spantide (Sigma Chemical Co., St. Louis, MO). Substance P antagonism had no effect on the amplitude of the inhibitory junction potential, caused an increase in the latter portion of the early excitatory junction potential, and abolished the late excitatory junction potential. The excitatory junction potential potentiated by substance P receptor antagonism was associated with a decrease in membrane resistance, increased in amplitude with conditioning hyperpolarizations to the estimated equilibrium potential for K+, and was blocked by the Cl-/HCO3- exchange inhibitor DIDS or prolonged perfusion with low-chloride solution. These studies suggest that a noncholinergic, non-substance P neurotransmitter is released from enteric motoneurons that produces excitation through an increase in smooth muscle chloride conductance.

Noncholinergic membrane potential responses to transmural nerve stimulation in the guinea pig ileum

We sought to characterize the projections of nonmuscarinic intramural inhibitory and excitatory neural input to the circular muscle layer of the small intestine. Intracellular membrane potential recordings were made in smooth muscle cells from the distal ileum of 22 guinea pigs. Intramural nerve stimulation (4 pulses, 15 mA, 20 Hz, 2 ms) was delivered by two electrodes located at varying distances from the recording electrode along the longitudinal axis of the intestine. The membrane potential responses immediately oral to the stimulus consisted of an abrupt-onset inhibitory junction potential (IJP) followed by two distinct depolarizations, an early excitatory junction potential (EJP) and a late EJP. The early IJP and early and late EJPs were observed as far as 53 +/- 5, 56 +/- 6, and 39 +/- 5 mm oral to the stimulus, respectively. The responses immediately anal to the stimulus consisted of an initial IJP followed by a prolonged hyperpolarization, which was sometimes interrupted by a superimposed EJP. The early IJP, EJP, and late IJP were observed as far as 77 +/- 12, 66 +/- 10, and 37 +/- 13 mm anal to the stimulus, respectively. All excitatory events greater than 5-10 mm oral or anal to the stimulus were blocked by hexamethonium. Hexamethonium slightly antagonized the early IJP oral to the stimulus but had no effect on the early IJP anal to the stimulus. The late IJP was not affected by hexamethonium. These studies are the first to describe a late IJP, which is observed only at sites anal to the stimulus, and a late EJP, which is observed only at sites oral to the stimulus. The neural pathways involved in these late synaptic events (late EJP and IJP) as well as the previously described early synaptic events (early EJP and IJP) are discussed.