Surgical techniques to prevent delayed gastric emptying after pancreaticoduodenectomy

BACKGROUND

Delayed gastric emptying (DGE) is one of the most common complications after pancreaticoduodenectomy (PD). DGE represents impaired gastric motility without significant mechanical obstruction and is associated with an increased length of hospital stay, increased healthcare costs, and a high readmission rate. We reviewed published studies on various technical modifications to reduce the incidence of DGE.

DATA SOURCES

Studies were identified by searching PubMed for relevant articles published up to December 2022. The following search terms were used: "pancreaticoduodenectomy", "pancreaticojejunostomy", "pancreaticogastrostomy", "gastric emptying", "gastroparesis" and "postoperative complications". The search was limited to English publications. Additional articles were identified by a manual search of references from key articles.

RESULTS

In recent years, various surgical procedures and techniques have been explored to reduce the incidence of DGE. Pyloric resection, Billroth II reconstruction, Braun's enteroenterostomy, and antecolic reconstruction may be associated with a decreased incidence of DGE, but more high-powered studies are needed in the future. Neither laparoscopic nor robotic surgery has demonstrated superiority in preventing DGE, and the use of staplers is controversial regarding whether they can reduce the incidence of DGE.

CONCLUSIONS

Despite many innovations in surgical techniques, there is no surgical procedure that is superior to others to reduce DGE. Further larger prospective randomized studies are needed.

Hypoxia-inducible factor 1α/IL-6 axis in activated hepatic stellate cells aggravates liver fibrosis

Hepatic stellate cells (HSCs) upregulate hypoxia inducible factor 1 alpha (HIF-1α) expression in response to fibrosis-induced hypoxia. The mechanism by which HIF-1α promotes liver fibrosis in HSCs is not fully understood. In this study, we found that increased expression of α-SMA, HIF-1α and IL-6, as well as colocalization of α-SMA and HIF-1α, and HIF-1α and IL-6, were observed in liver fibrotic tissues of patients and a mouse model. HIF-1α expression induced IL-6 secretion in activated HSCs and the increase could be abolished by HIF-1α suppression or HIF1A gene knockdown. HIF-1α directly bound to the hypoxia response element (HRE) region in HSC IL6/Il6 promoters. Additionally, culturing naïve CD4 T cells with supernatant from HSCs in which HIF-1α is highly expressed increased IL-17A expression, and the expression could be abolished by HIF1A knockdown in LX2. In turn, the IL-17A-enriched supernatant induced IL-6 secretion in HSCs. Together, these results show that HIF-1α upregulates IL-6 expression in HSCs and induces IL-17A secretion through directly binding to the HRE of IL6 promoter.

Weather Translation via Weather-Cue Transferring

In this article, the weather translation task is proposed, which aims to transfer the weather type of the image from one category to another. Weather translation is a complicated image weather editing task that changes the weather cue of an image across multiple weather types, and it is related to image restoration, image editing, and photographic style transfer tasks. Although lots of approaches have been developed for traditional image translation and restoration tasks, only few of them are capable of handling the multicategory weather types problem with a single network due to the rich categories and highly complicated semantic structures of weather images. Especially, it is difficult to change the weather cue while preserving the weather-invariant area. To solve these issues, we developed a weather-cue guided multidomain translation approach based on StarGAN v2, termed WeatherGAN. In the proposed model, the core generator is redesigned to transfer the weather cue according to the target weather type. The weather segmentation module is first introduced to acquire the weather semantic structure of images in a weakly supervised multitask manner. In addition, a weather clues module is presented to reprocess the weather segmentation into a weather-specific clues map, which identifies the weather-invariant and weather-cue areas clearly. Extensive studies and evaluations show that our approach outperforms the state of the art. The data and source code will be publicly available soon after the manuscript is accepted.

Beneficial effects of Wuzhi Capsule on tacrolimus blood concentrations in liver transplant patients with different donor-recipient CYP3A5 genotypes

WHAT IS KNOWN AND OBJECTIVE

Tacrolimus (Tac) is an immunosuppressant that is widely used to prevent allograft rejection in patients after liver transplantation. Its metabolism mainly depends on the cytochrome P450 3A5 (CYP3A5), which has genetic polymorphisms. Recently, a Chinese herbal medicine known as Wuzhi Capsule (WZC) was shown to increase Tac blood concentrations by inhibiting the activity of CYP3A in animal studies in rats. To date, it remains unexplored whether WZC can be efficiently used to enhance the blood concentration of Tac in liver transplant patients with different donor-recipient CYP3A5 genotypes.

METHODS

A total of 185 liver transplant patients were enrolled and two-way ANOVA was carried out, then they were divided into four groups according to the combinations of donor-recipient CYP3A5 phenotypes. WZC was given to patients when the dose of Tac was ≥4 mg, and the dose-adjusted C₀ (C₀ /D) of Tac measured twice in succession was ≤1 ng/ml/mg. The blood trough concentration of Tac (C₀ ), C₀ /D, and dose- and body weight-adjusted C₀ (C₀ /D/W) was analysed on days 7 and 14 after liver transplantation.

RESULTS

The genotypes of donor and recipient or WZC had significant effects on C0, C0/D and C0/D/W. There were significant differences in the Tac blood concentrations between the groups. The recipient expression (*1)/donor expression (*1) (R+/D+) group had the lowest C₀ , C₀ /D and C₀ /D/W among the four groups. Furthermore, a larger proportion of patients in the CYP3A5 expression groups required Tac dose adjustment to achieve a therapeutic effect and were given Tac with WZC. Notably, the use of WZC significantly increased the blood concentrations of Tac in the CYP3A5 expression groups and greater increases in the C₀ /D and C₀ /D/W were significantly associated with higher doses of WZC in the CYP3A5 expression groups. What is more, WZC reduced the hospitalization cost of patients to a certain extent.

WHAT IS NEW AND CONCLUSION

WZC significantly increased the C₀ , C₀ /D and C₀ /D/W in the CYP3A5 expression groups and reduced the hospitalization expenses of patients to a certain extent. What is more, greater increases in the C₀ /D and C₀ /D/W were significantly associated with higher doses of WZC.

Hepatic epithelioid hemangioendothelioma: Update on diagnosis and therapy

With an estimated incidence of only 1-2 cases in every 1 million people, hepatic epithelioid hemangioendothelioma (HEHE) is a rare vascular endothelial cell tumor occurring in the liver and consisting of epithelioid and histiocyte-like vascular endothelial cells in mucus or a fibrotic matrix. HEHE is characterized as a low-to-moderate grade malignant tumor and is classified into three types: solitary, multiple, and diffuse. Both the etiology and characteristic clinical manifestations of HEHE are unclear. However, HEHE has a characteristic appearance on imaging including ultrasound, magnetic resonance imaging, and positron emission tomography/computerized tomography. Still, its diagnosis depends mainly on pathological findings, with immunohistochemical detection of endothelial markers cluster of differentiation 31 (CD31), CD34, CD10, vimentin, and factor VIII antigen as the basis of diagnosis. Hepatectomy and/or liver transplantation are the first choice for treatment, but various chemotherapeutic drugs are reportedly effective, providing a promising treatment option. In this review, we summarize the literature related to the diagnosis and treatment of HEHE, which provides future perspectives for the clinical management of HEHE.

Fast-growing epithelioid hemangioendothelioma of the liver: A case report

RATIONALE

Hepatic epithelioid hemangioendothelioma (HEH) is a rare vascular tumor of the liver with malignant potential. It can be of solitary type, multifocal type, or diffuse type. Although there are some characteristic features on radiologic imaging, the definitive diagnosis of HEH is based on histopathology. The surgical treatment of HEH includes liver resection and transplant.

PATIENT CONCERNS

A middle-aged woman presented with easy fatiguability and anorexia for 1 month was found to have multifocal lesions on radiological imaging.

DIAGNOSIS

HEH was diagnosed by needle biopsy. It can be seen from imaging that this case is a multifocal form. The largest lesion increased from 3 to 3.3 cm within 2 months, with an increase of 9.45%; no other relevant literatures have been reported.

INTERVENTIONS

The possibility of liver transplantation was suggested to the patient. However, the patient refused transplantation and was successfully treated by radical right hepatectomy and resection of the left lobe lesion.

OUTCOMES

She remained disease-free throughout a year follow-up period.

CONCLUSION

HEH is a rare disease with characteristic radiological and pathological features. Although liver transplantation is the preferred treatment for multifocal HEH, surgical excision represents one alternative when the lesions can be guaranteed to be completely excised.

A Protocol for Transverse Cardiac Slicing and Optical Mapping in Murine Heart

Thin living tissue slices have recently emerged as a new tissue model for cardiac electrophysiological research. Slices can be produced from human cardiac tissue, in addition to small and large mammalian hearts, representing a powerful in vitro model system for preclinical and translational heart research. In the present protocol, we describe a detailed mouse heart transverse slicing and optical imaging methodology. The use of this technology for high-throughput optical imaging allows study of electrophysiology of murine hearts in an organotypic pseudo two-dimensional model. The slices are cut at right angles to the long axis of the heart, permitting robust interrogation of transmembrane potential (Vm) and calcium transients (CaT) throughout the entire heart with exceptional regional precision. This approach enables the use of a series of slices prepared from the ventricles to measure Vm and CaT with high temporal and spatial resolution, allowing (i) comparison of successive slices which form a stack representing the original geometry of the heart; (ii) profiling of transmural and regional gradients in Vm and CaT in the ventricle; (iii) characterization of transmural and regional profiles of action potential and CaT alternans under stress (e.g., high frequency pacing or β-adrenergic stimulation) or pathological conditions (e.g., hypertrophy). Thus, the protocol described here provides a powerful platform for innovative research on electrical and calcium handling heterogeneity within the heart. It can be also combined with optogenetic technology to carry out optical stimulation; aiding studies of cellular Vm and CaT in a cell type specific manner.

Mixed adenoneuroendocrine carcinoma of the extrahepatic bile duct: a case report

Background

The concept of mixed adenoneuroendocrine carcinoma (MANEC) was introduced in the 2010 World Health Organization classification of digestive neuroendocrine neoplasms. Bile duct invasion by MANEC is exceptionally rare. We herein report a case of MANEC with invasion of multiple bile ducts.

Case presentation: A 60-year-old man presented with a 7-day history of upper abdominal pain, and a mass in the cystic duct was suspected based on computed tomography findings. The patient underwent resection of the extrahepatic bile ducts with concomitant radical lymphadenectomy and Roux-en-Y cholangiojejunostomy. Large cell neuroendocrine carcinoma was detected in a component of the resected tumor. According to the pathological and immunohistochemical features of the tumor, the final histopathological diagnosis was a biliary MANEC, tumor stage T2N0M1 (Stage IIIC). The patient recovered uneventfully and was discharged from the hospital 10 days after surgery.

Conclusions

We have described a rare case of extrahepatic MANEC invading multiple bile ducts, with particular emphasis on the physician’s awareness of MANEC and its optimal treatment. MANEC arising from extrahepatic bile ducts is rare, and surgical resection is the most effective treatment method.

Hem-o-lok clip found in the common bile duct 3 years after laparoscopic cholecystectomy and surgical exploration

Endoscopic retrograde cholangiopancreatography (ERCP) with stone extraction is a common and preferred choice for gallstone disease. Laparoscopic common bile duct exploration (LCBDE) and laparoscopic cholecystectomy (LC) are being increasingly used for managing choledocholithiasis and cholecystolithiasis. We report a case of a Hem-o-lok clip that was dropped into the common bile duct (CBD) after LC and surgical common bile duct exploration (CBDE). An 84-year-old man presented with right upper quadrant pain and jaundice for 2 months, and chills and hyperpyrexia for 1 day. The patient had received ERCP and surgical CBDE at a local hospital 3 years previously. The patient first received ERCP and endoscopic nasobiliary drainage (ENBD). When laboratory tests were normal, the patient then received LCBDE. During exploration, stones and a Hem-o-lok clip in the CBD were removed. The patient made good progress after LCBDE + T-tube placement and was discharged from hospital. The findings from this case suggest the following: 1) an appropriate therapy method should be considered for certain gallstone diseases, especially for choledocholithiasis and cholecystolithiasis; and 2) a Hem-o-lok clip should be carefully used during laparoscopic or robot-assisted surgery and the Hem-o-lok clip should not be in close proximity to the incision on the CBD.

A case of adrenocortical carcinoma accompanying secondary acute adrenal hypofunction postoperation

Background

Adrenocortical carcinoma (ACC) is a rare, heterogeneous malignancy with a poor prognosis. ACCs are classified as functioning and non-functioning. The pathogenesis of ACC remains elusive, and diagnosis of ACC is currently based on pathology. In the absence of other effective approaches, surgical resection is the preferred treatment option.

Case presentation

Here, we report a case of ACC in the retroperitoneum. The patient underwent radical adrenalectomy and remained disease-free throughout a 6-month follow-up.

Conclusions

Radical surgical resection is an efficient therapy for ACC, and hydrocortisone can be used to alleviate symptoms of secondary acute adrenal hypofunction.

Occurrence of signet-ring cell carcinoma with cholangiocarcinoma 25 years after choledochal cyst excision: A case report

RATIONALE

Choledochal cysts are a risk factor for the development of cholangiocarcinoma. Hence, complete surgical excision is the preferred treatment in most cases. However, cholangiocarcinoma still can develop from the remnant biliary system after surgical excision. Signet-ring cell carcinoma is a rare type of cancer of the biliary system, and the occurrence of signet-ring cell carcinoma after surgical excision of choledochal cysts has not been reported in the English literature to date.

PATIENT CONCERNS

We report a case of a 32-year-old woman who presented with a 1-month history of abdominal pain,obstructive jaundice, itching, and fever. The patient had undergone choledochal cyst excision and Roux-en-Y hepatico-jejunostomy 25 years previously and had now developed signet-ring cell carcinoma along with cholangiocarcinoma at the anastomotic site. DIAGNOSES:: signet-ring cell carcinoma along with cholangiocarcinoma.

INTERVENTIONS

Interventions included laparotomy with evacuation,blood transfusion,and other adjuvant therapy.

OUTCOMES

The patient died five months later.

LESSONS

Surgery is the best treatment for CCCs, and the surgeon should try to remove as much as of the bile duct cyst as possible.

Crystal structure of 2-acetylpyrrole S-methylthiosemicarbazonium hydroiodide, C8H13IN4S

C8H13IN4S, monoclinic, P21/n (no. 14), a = 5.9563(4) Å, b = 12.8592(8) Å, c = 16.1795(10) Å, β = 99.450(1)°, V = 1222.42(14) Å3, Z = 4, R gt(F) = 0.0228, wR ref(F 2) = 0.0535, T = 296 K.

Periostin levels correlate with disease severity and chronicity in patients with atopic dermatitis

BACKGROUND

Recent findings indicate that periostin, an extracellular matrix protein induced by T helper 2 cytokines, plays a critical role in the pathogenesis of atopic dermatitis (AD).

OBJECTIVES

To determine whether serum periostin level is associated with clinical phenotype in adult patients with AD.

METHODS

An enzyme-linked immunosorbent assay was performed to determine serum periostin levels in 257 adult patients with AD, 66 patients with psoriasis vulgaris (PV) as a disease control and 25 healthy controls. Serum periostin levels were analysed together with clinical characteristics and laboratory parameters, including thymus and activation-regulated chemokine (TARC), lactate dehydrogenase (LDH), blood eosinophil count and total IgE. Immunohistochemical analysis evaluated the expression of periostin in association with various clinical phenotypes of AD. The effect of treatment on serum periostin level was also assessed.

RESULTS

Serum periostin was significantly higher in patients with AD than in patients with PV and healthy controls. Periostin level was found to be positively correlated with disease severity, TARC level, LDH level and eosinophil count, but not with IgE level. Higher serum periostin level was observed in patients with extrinsic AD compared with patients with intrinsic AD; the positive correlation of disease severity disappeared in patients with intrinsic AD. Robust expression of periostin was detected in the dermis of patients with AD with erythroderma, lichenification and, to a lesser extent, scaly erythema. Serial measurement of serum periostin revealed decreased levels of periostin after treatment for AD.

CONCLUSIONS

Periostin may play a critical role in disease severity and chronicity in the pathogenesis of AD.

Identification of Hic-5 as a novel regulatory factor for integrin αIIbβ3 activation and platelet aggregation in mice

BACKGROUND

Integrin αIIbβ3 plays key roles in platelet aggregation and subsequent thrombus formation. Hydrogen peroxide-inducible clone-5 (Hic-5), a member of the paxillin family, serves as a focal adhesion adaptor protein associated with αIIbβ3 at its cytoplasmic strand.

OBJECTIVES

Hic-5 function in αIIbβ3 activation and subsequent platelet aggregation remains unknown. To address this question, platelets from Hic-5(-/-) mice were analyzed.

METHODS AND RESULTS

Hic-5(-/-) mice displayed a significant hemostatic defect and resistance to thromboembolism, which were explained in part by weaker thrombin-induced aggregation in Hic-5(-/-) platelets. Mechanistically, Hic-5(-/-) platelets showed limited activation of αIIbβ3 upon thrombin treatment. Morphological alteration in Hic-5(-/-) platelets after thrombin stimulation on fibrinogen plates was also limited. As a direct consequence, the quantity of actin co-immunoprecipitating with the activated αIIbβ3 was smaller in Hic-5(-/-) platelets than in wild-type platelets.

CONCLUSION

We identified Hic-5 as a novel and specific regulatory factor for thrombin-induced αIIbβ3 activation and subsequent platelet aggregation in mice.

[Long-term outcome after extracorporeal shock wave lithotripsy for gallstones]

We retrospectively reviewed 289 cases followed for a long time after extracorporeal shock wave lithotripy (ESWL) for gallstones. Follow-up periods ranged from 0.5 years to 9.2 years, with a median of 4.1 years. The complete resolution rate was 45.6%. A solitary gallstone, non-calcified gallstones on CT, and Tsuchiya's sonographic type Ia and Ib gallstones were found to be statistically significant variable for resolution of the disease. With a maximum follow-up period of 9 years, the cumulative recurrence rate was 30.7%. Among the 156 patients whose gallstones did not resolve, 70 were symptomatic and the other 86 were asymptomatic. Thirty-eight of the symptomatic patients (54.3%) became symptom-free, while 23 asymptomatic patients (29.1%) became symptomatic. The cumulative rate of occurrence of colic attacks and/or acute cholecystitis was significantly higher in the cases with lithotripsy fragments 4 mm or more in size than in the cases wih fragments 3 mm or less in size (51.8% vs. 16.7%; p < 0.05). ESWL was followed by surgery in 23.1% because symptoms developed or became aggravated after ESWL in 58.3% of them. Gallbladder cancer was discovered in one case. Patients undergoing ESWL should be followed by focusing on postoperative recurrence, symptoms, and gallbladder cancer.

[Usefulness of DIC-CT in choledocholithiasis]

In order to assess the efficacy of helical CT in drip-infusion cholangiography (DIC-CT) for diagnosis of choledocholithiasis, 82 patients with biliary diseases, including 25 patients with a definite diagnosis of choledocholithiasis obtained by direct cholangiography, were investigated by DIC-CT and EUS. Comparative investigation showed that, of the 25 cases, 94.7% could be imaged by DIC-CT and 87.5% by EUS, with respective sensitivities of 94.7% and 87.5%. The specificities in both cases were 100% and accuracies were 97.8% with DIC-CT and 96% with EUS respectively. Therefore, in diagnosis the choledocholithiasis, DIC-CT displays similar diagnostic efficiency as EUS or ERC, and can be recognized as the non-invasive and useful procedure for pre-operative diagnosis of cholecystolithiasis.

Bladder origin neuroblastoma detected by mass screening

Pelvic neuroblastoma is relatively rare and most are a presacral mass. We present a case of asymptomatic neuroblastoma arising from the dome of the bladder wall, detected by a mass screening program. Only 1 case of neuroblastoma originating from the bladder has been previously reported. Both the reported case and our present case arose from the dome of the bladder wall. The differential diagnosis for bladder tumor in children is discussed; although uncommon, neuroblastoma should be considered a probable choice, especially for tumors arising from the dome of the bladder wall.

[Immunomodulation by TYB-2285 of Dermatophagoides farinae (Df) antigen-induced IFN-gamma and IL-4 production in lymphocytes from children with bronchial asthma]

Effect of TYB-2285 and its metabolites on immune responses by peripheral blood mononuclear cells (PBMC) from children with bronchial asthma was investigated. TYB-2285 and its metabolites have immunosuppressive activity for the proliferation by Df-stimulated patients' lymphocytes. Concanavalin A (Con A)-activated peripheral blood mononuclear cells (PBMC) from the patients were not affected by the same treatment. The results indicate that TYB-2285 and its metabolites are capable of suppressing antigen-induced 3H-thymidine (3H-TdR) uptake but not the response induced by Con A. Interferon-gamma (IFN-gamma) production by Df-stimulated PBMC from patients with active asthma, which was lower than that of normal lymphocytes, were reversed beyond the levels of that in normal subjects. Thus reduced production of IFN-gamma by Df-stimulated patients' lymphocytes was increased by TYB-2285 and its metabolites in a dose-dependent manner. This phenomenon was not observed in lymphocytes from normal subjects. Furthermore, TYB-2285 inhibited IL-4 production induced by Df antigen in asthmatic patients' lymphocytes. Taken, together, TYB-2285 could work as a weak immunosuppressant to modify lymphocytes' responses to allergen in patients with bronchial asthma. These data underscore the potential benefit for the patients with bronchial asthma.

[Correlation of interleukin-2 (IL-2) responsiveness by egg white-stimulated lymphocytes with hen egg oral provocation test in atopic children]

One hundred and twenty five cases of atopic children such as atopic dermatitis and bronchial asthma were orally provocated with rare hen egg every 20 minutes one by one upto the whole amount. In one week observation 75 cases showed any symptoms of allergy including eruption and exacerbation of atopic eczema in an immediate, late, and/or delayed responses. Frequency of positive egg white-induce IL-2 responsiveness test in patients with positive oral provocation was 90.7% (68 out of 75 cases; sensitivity). That of negative test in patients with negative provocation was 84.0% (42 out of 50 cases; specificity). In contrast, specificity of IgE RAST for egg white were 88.0% comparable to the value of antigen-specific IL-2 responsiveness (AIR) test, but the specificity was lower value (37.3%) for screening the etiological antigens as compared to that of AIR test. High frequency of positive egg white-induced IL-2 responsiveness test was observed over an immediate, late and delayed responses, while low frequency of positive IgE RAST for hen egg was observed largely in patients showing delayed but not immediate response. The results indicate that IgE RAST in this study reflects IgE-mediated immediate type hypersensitivity, whereas AIR test reflects, in addition to immediate responses, late and delayed type hypersensitivity. The combined results suggest that AIR test in hen egg allergy is a useful method in vitro for both screening and determining etiological allergens, and might be able to substitute for provocation test in vivo for which many times, labours, expenses, and patients' risks are required, and to cover IgE RAST which fails to determine etiological allergens in 62.7% of patients with positive oral provocation.

Pattern of cytokine production by T cells from adolescents with asthma in remission, after stimulation with Dermatophagoides farinae antigen

Children with asthma usually become asymptomatic by the time they reach age 20 y. To clarify the immunologic mechanisms responsible for this phenomenon, we studied patients in remission and others who still had frequent asthma attacks. Patients were grouped by clinical status, and three variables were measured: serum levels of IgE, production of IL4 and interferon (IFN)-gamma, and the activation of T cells induced by Dermatophagoides farinae (Df) antigen. Df-induced activation of T cells (as measured by antigen-induced IL2 responsiveness) or IL2 synthesis itself was induced in patients with active asthma but not in normal subjects. These responses were much weaker in patients in remission. When stimulated by Df antigen in vitro, lymphocytes from patients with active asthma produced much more IL4 than did the cells from normal subjects, and cells from patients in remission produced only a small amount. In contrast, under similar conditions lymphocytes from patients with active asthma produced less IFN-gamma than did the cells from normal subjects. Production of IFN-gamma stimulated by Df antigen was high in patients in remission but not in normal subjects. Thus, upregulated IFN-gamma production after exposure to Df antigen might reduce IL4 secretion, which would suppress IgE production and would improve clinical status. Df antigen may suppress Df-induced allergic responses in patients with asthma in remission.

Rapid activation of insulin-like growth factor binding protein-5 gene transcription during myoblast differentiation

Insulin-like growth factor binding proteins (IGFBPs) comprise a family of secreted proteins that bind insulin-like growth factors-I and -II (IGF-I and -II) with high affinity and potentially modulate their biological effects. We have demonstrated previously that IGFBP-5, the most conserved of the six known IGFBPs, is expressed in muscle cells in the developing embryo and during the terminal differentiation of several myogenic cell lines. In this study we show that an IGF-I analog that binds minimally to IGFBPs potently enhances the differentiation of the stringently controlled inducible C2 myoblast (C2l) cell line and identify IGFBP-5 as the sole IGFBP secreted during C2l differentiation. We find that induction of IGFBP-5 mRNA and protein is coincident with the onset of myogenin gene expression and occurs secondary to the rapid activation of IGFBP-5 gene transcription. By transient gene transfer experiments we demonstrate that a 1004 base pair segment of the IGFBP-5 promoter is very active in directing expression of the reporter gene luciferase in C2l myoblasts. A promoter fragment containing only 156 nucleotides of 5'-flanking DNA retained more than 70% of maximal activity and mediated at least part of the differentiation-dependent rise in IGFBP-5 gene transcription. Within this active segment are several potential binding sites for muscle-enriched transcription factors. Our results show that induction of IGFBP-5 expression is an early event in the myogenic differentiation of the C2l cell line and suggest that one function of this IGFBP is to modulate IGF-induced differentiation. C2l cells are thus an excellent in vitro model for elucidating the developmental factors that control IGFBP-5 gene transcription and action in skeletal muscle.

Structure and function of the mouse insulin-like growth factor binding protein 5 gene promoter

The actions of insulin-like growth factors I and II (IGF-I and -II) are modulated by interactions with one or more of a family of secreted IGF binding proteins (IGFBPs). IGFBP-5, the most conserved of the six known IGFBPs, is a 252-amino-acid protein that has been shown both to potentiate and inhibit IGF action. In previous studies, we have cloned and characterized the mouse IGFBP-5 gene and demonstrated that it is expressed in a hierarchical pattern in different adult mouse tissues and during rodent embryonic development. In this report, we describe the initial analysis of the IGFBP-5 gene promoter. By transient gene transfer studies, we show the orientation-specific activity of DNA fragments containing from 31 to 4,100 bp from the 5'-flanking region of the mouse IGFBP-5 gene in directing expression of the heterologous reporter gene luciferase in Hep G2 cells. DNA fragments with only 156 bp of 5'-flanking sequence mediated over 60% of maximal promoter activity, and a segment containing the TATA box and the first 120 bp of exon 1 still conferred some promoter function. Within the highly active 156-bp region, we identified a 37-bp segment from -70 to -34 that exhibited specific binding in DNase I footprinting and gel-mobility shift experiments with Hep G2 nuclear protein extracts. The footprinted region, which is almost completely conserved in the rat and human IGFBP-5 genes, was responsible for at least 70% of the activity of the intact promoter, as evidenced by the deleterious consequences of small internal deletions within this sequence on promoter function.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of human IgG subclass production by cytokines: human IgG subclass production enhanced differentially by interleukin-6

Peripheral blood mononuclear cells (PBMC) stimulated with pokeweed mitogen (PWM) produced increased IgG when cultured with interleukin-6 (IL-6). IgG subclass analysis showed that the presence of IL-6 during the last half of the culture period enhanced IgG1 and IgG4 production. Enhancement of IgG2 synthesis required the presence of IL-6 solely during the last half of the culture period, whereas enhancement paradoxically was blocked by its presence during the first half. The IgG3-enhancing effect of IL-6 was observed only when IL-6 was present throughout the culture period. The critical role of IL-6 was supported by the inhibition of IgG subclass synthesis by anti-IL-6 antibody. PBMC depleted of cells bearing surface IgG of a particular subclass did not synthesize that subclass. This non-responsiveness, which was not reversed even by an addition of IL-6, indicates that the main action of IL-6 is on the differentiation of committed B cells. In addition, IL-6 triggered T cells to produce significant helper activity. These results indicate that IL-6 enhances IgG subclass production differentially and that its critical role in IgG subclass synthesis is in part mediated by T cells, as well as by its direct action on B cells. These findings should be useful for analysing such immune disorders as IgG subclass deficiencies and autoimmune diseases.

Monoclonal proliferation of Epstein-Barr virus-infected T-cells in a patient with virus-associated haemophagocytic syndrome

Virus-associated haemophagocytic syndrome (VAHS) is a non-neoplastic, generalized histiocytic proliferation disorder showing marked haemophagocytosis associated with systemic viral infection. We describe the case of a 1-year-old girl with Epstein-Barr virus (EBV)-related VAHS, in whom Southern blot analysis showed monoclonal proliferation of bone marrow cells with the EBV genome; detected with the Xho-1 fragment of the latent infection membrane protein genome. EBV serology showed anti-Epstein-Barr virus nuclear associated antigen (EBNA), anti-viral capsid antigen (VCA)-IgG, anti-VCA-IgA elevation and positive EBNA of Sheep red blood cells (SRBC)-rosette-forming bone marrow cells in the late period of her clinical course, indicative of EBV infection. DNA analysis of her bone marrow cells showed monoclonal rearrangement of the T-cell receptor-beta and -gamma chain genes but not of the immunoglobulin heavy chain genes. Those results suggest that EBV may infect T-cells, after which the cells proliferate monoclonally. Repeated administration of epipodophyllotoxin VP-16-213 induced remission, but adrenocortical steroid, vincristine, and cyclophosphamide had no effect on the patient's condition. Ours is a first case report of VAHS showing monoclonal proliferation of EBV-infected T-cells.

Identification of two clusters of mouse insulin-like growth factor binding protein genes on chromosomes 1 and 11

The genes for insulin-like growth factor binding proteins (IGFBPs) encode secreted proteins that bind insulin-like growth factors I and II with high affinity and modulate their biological activities. In this report we have used interspecific backcross mapping and gene cloning to define the chromosomal locations of 4 mouse Igfbp genes. Igfbp1 and 3 are found in the proximal part of chromosome 1. In the human genome these two loci map within 20 kb of one another on chromosome 7p14-p12, and the genes are organized in a tail-to-tail configuration. Mouse Igfbp2 and 5 colocalize to a proximal region of chromosome 1 that is syntenic with human chromosome 2q33-q36, and the two genes are 5 kb apart in a tail-to-tail orientation. These results suggest an evolutionary scheme in which a primordial IGFBP gene duplicated to form a cluster that was later replicated to create second linkage group.

Organization, expression, and chromosomal location of the mouse insulin-like growth factor binding protein 5 gene

Insulin-like growth factor binding proteins (IGFBPs) constitute a family of at least six secreted proteins that bind insulin-like growth factors I and II (IGF-I and -II) and are capable of modifying IGF actions on target cells. We previously have purified an approximately 29-kDa IGFBP that is secreted by myoblasts during their terminal differentiation, have identified the protein as mouse IGFBP-5, and have cloned its cDNA (James et al., 1993). In this study, we have characterized the mouse IGFBP-5 gene, established its pattern of expression in the adult mouse, and defined its chromosomal location. The 17-kb gene was isolated on overlapping cosmid and lambda clones, and the four exons encoding the 5914-bp mRNA were sequenced. The 5' end of the gene was mapped by solution-hybridization ribonuclease protection assay to two discrete sites in exon 1 that were separated by 21 bp. The relative use of each transcription start site was found to vary among different mouse tissues. By interspecies backcross mapping using progeny derived from matings of [(C57BL/6J X Mus spretus)F1 x C57BL/6J] mice, the IGFBP-5 gene was localized to the proximal region of chromosome 1 in tight linkage with fibronectin 1 (0 recombinants in 168 mice analyzed). Since this part of chromosome 1 shares homology with human chromosome 2q, and since fibronectin has been mapped to 2q34-q36, it is likely that human IGFBP-5 will reside on 2q as well. Characterization of the mouse IGFBP-5 gene now provides a starting point for studying the roles and regulation of this protein in development.

[Analysis and regulation of interferon-gamma production by peripheral blood lymphocytes from patients with bronchial asthma]

As with normal lymphocytes, small amounts of interferon-gamma (IFN-gamma) were spontaneously produced by lymphocytes from patients with bronchial asthma, and this bronchial asthma, and this production was markedly enhanced by concanavalin A (Con A) stimulation. Distinct from normal lymphocytes, however, IFN-gamma synthesis from patients' lymphocytes decreased in a dose dependent manner on stimulation with Dermatophagoides farinae (Df) antigen. IFN-gamma-producing cells are defined as being of the CD4+ 45RO+ T cell subset, which failed to produce IFN-gamma in Df-stimulated patients' lymphocytes. As the decreased production of IFN-gamma by antigenic stimulation was exclusively induced by Df antigen, but not by ovalbumin (OVA) or Japanese cedar (JC) antigen, it is concluded that Df antigen specifically suppressed IFN-gamma production in patients' lymphocytes. The IFN-gamma synthesis from normal lymphocytes was suppressed by the addition of IL-4 in a dose dependent manner. Moreover, anti-IL-4 antibody dose dependently enhanced IFN-gamma production from Df-stimulated patients' lymphocytes but not from unstimulated lymphocytes. These results indicate that IFN-gamma production by patients' lymphocytes is suppressed by the endogenous IL-4. Reduced IFN-gamma production in patients' lymphocytes on stimulation with Df antigen may lead to the overproduction of IgE in vivo.

[Analysis of immunosuppressive activity of lecithin-bound iodine (LBI) on antigen-induced IL2 responsiveness in peripheral blood lymphocytes from patients with allergic diseases]

The effect of lecithin-bound iodine (LBI) on antigen-induced IL2 responsiveness, useful in in vitro test for the detection of etiological antigen and disease activity in allergic diseases, was investigated. In peripheral blood mononuclear cells (PBMC) from asthmatic children, LBI suppressed Dermatophagoides farinae (Df)-induced IL2 responsiveness in a dose dependent manner, in a range of 0.01 to 100 micrograms/ml. Similarly, LBI also suppressed ovalbumin (OVA)-induced IL2 responsiveness in PBMC from patients with atopic dermatitis, sensitized with OVA, in concentration of 0.1 to 100 micrograms/ml. Moreover, purified protein derivative (PPD)-induced IL2 responsiveness was equally inhibited by LBI, at doses of between 0.1 and 100 micrograms/ml. However, LBI could not overcome the responses induced by concanavalin A (Con A) until it reached unphysiological concentrations of as high as 100 micrograms/ml. The fact that antigen-induced IL2 responsiveness was suppressed by LBI at concentrations comparable to blood levels of LBI in individuals medicated suggests that LBI is a weak immunosuppressant. IL2-responding T cells were more sensitive to LBI than antigen-presenting cells in Df-induced IL2 responsiveness, although LBI suppressed both cell populations. Taken together, LBI could work as a weak immunosuppressant to inhibit lymphocyte responses to allergen and to improve clinical status in allergic diseases, including bronchial asthma caused by Df and atopic dermatitis provoked by OVA.

[Immunological aspects of asthmatic children in remission]

Allergen-activated T cells secrete several kinds of bioactive lymphokines such as IL2, IL3, IL4, IL5 and IFN-gamma. They function as helpers in IgE production involved in immediate type hypersensitivity and/or effector cells in delayed type hypersensitivity in allergic patients. The acquisition of interleukin 2 (IL2) responsiveness by specific antigen-stimulated cells is generally an essential event for the induction of specific immunological phenomena. To investigate the immunological changes in asthmatic children in remission, the induction of IL2-responsiveness and production by Df (Dermatophagoides farinae)-stimulated patient lymphocytes, and Df-induced IFN-gamma production by patient lymphocytes were evaluated. The patients were divided into 3 groups. The remission group (I) consisted of those patients who had had no or only a few asthmatic attacks for more than 2 years without medication. The group of active asthma were divided into 2 groups according to attack frequency and severity (II, partial remission; III, active asthma). IL2 responsiveness and production by Df-stimulated lymphocytes from group II and III were increased. As symptoms improved, the extent of the response subsided to a level comparable to that of normal individuals (group III). IFN-gamma production by Df-stimulated lymphocytes from patients with active asthma was lower than that of normal lymphocytes. In contrast, lymphocytes from patients in complete remission group (I) induced far greater IFN-gamma generation than those from normal and group II and III patients in a Df antigen-dependent manner, which might downregulate Df-induced hyperreactivity for Df-mediated allergic response.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcriptional activation of the insulin-like growth factor-II gene during myoblast differentiation

Insulin-like growth factor-II (IGF-II) is a secreted 67-amino acid peptide that functions principally as a prenatal growth regulator in mammals. To date, the mechanisms involved in the stimulation of IGF-II expression in the embryo and its attenuation after birth are unknown. Recent studies have shown that IGF-II mRNA and protein are induced during the terminal stages of muscle development in vitro, and that IGF-II may act as an autocrine differentiation agent for skeletal myoblasts. We now have investigated the regulation of IGF-II gene expression in muscle cells. Steady state levels of IGF-II mRNA increased by more than 30-fold during terminal differentiation of the C2 mouse myoblast cell line. Transcription run-on experiments using isolated muscle cell nuclei and direct analysis of nuclear RNA each demonstrated a greater than 10-fold rise in nascent IGF-II mRNA during cellular differentiation, and ribonuclease protection experiments showed that more than 95% of IGF-II mRNAs initiated in noncoding exon 3, implying that transcriptional activation occurs principally through promoter 3, the most 3' of the three mouse IGF-II gene promoters. Analysis of chromatin structure around the IGF-II gene in C2 cells revealed four major and four minor DNase-I-hypersensitive sites, but did not provide insight into the mechanisms of gene activation, since all sites were present in proliferating and differentiating cells. Gene transfer experiments showed that promoter 3 was at least 50-fold more active than promoter 1 or 2 in C2 cells, but the functional assessment of nearly 26 kilobases of additional DNA within the IGF-II locus by an "enhancer trap" approach did not delineate any chromosomal regions capable of mediating differentiation-specific gene activation. Our results demonstrate that muscle cells encode mechanisms for activating IGF-II gene transcription and suggest that these cells may be excellent models for identifying the developmentally regulated factors that control IGF-II gene expression.

Amino acid substitutions in the intracellular part of the growth hormone receptor in a patient with the Laron syndrome

By complementary DNA cloning we have identified two amino acid substitutions in the intracellular region of the human GH receptor in a child with growth failure and clinical features of the Laron syndrome. At the second position of codon 422 a G to T transversion changes a cysteine residue to phenylalanine, whereas at the first nucleotide of codon 561 an alteration from C to A leads to the substitution of threonine for proline. Direct analysis of exon 10 of the GH receptor gene showed that both nucleotide substitutions reside on the same chromosome and were inherited from the patient's mother. Evaluation of DNA from 10 additional prospectively recruited children with growth failure and a clinical picture similar to the index case did not reveal any nucleotide alterations in codons 422, 560, or 561. These observations represent the first demonstration of variation within the intracytoplasmic part of the human GH receptor and indicate that mutations occurring at multiple locations within the receptor gene may lead to the same clinical phenotype.

[A study of Epstein-Barr virus-associated hemophagocytic syndrome successfully treated with VP16 and analysis of T cell receptor chain genes of the bone marrow cells]

Virus-associated hemophagocytic syndrome (VAHS) is a nonneoplastic, generalized histiocytic proliferation disorder with marked hemophagocytosis associated with a systemic viral infection. We describe a female child with EBV-related VAHS, in whom Southern blot analysis showed monoclonal proliferation of bone marrow cells having EBV genome as detected with Xho-1 fragment of latent infection membrane protein (LMP) genome. The EBV serology showed anti-EBNA, anti-VCA-IgG, anti-VCA-IgA elevation and positive EBNA of SRBC-rosette forming bone marrow cells in late period of her clinical course, which indicated primary infection or secondary alteration of EBV immunity. The DNA analysis of the bone marrow cells also demonstrated monoclonal rearrangement of T cell receptor-beta and -gamma chain genes. Thus our study suggests that EBV might infect T cells and the T cells might proliferate monoclonally. Repeated administration of VP16 was capable of inducing remission of the disease, although adrenocortical steroid, vincristine and cyclophosphamide were administrated unsuccessfully. This is the first case of VAHS in which the monoclonal proliferation of EBV-infected T cells was demonstrated.

[Surgical treatment of PDA in the elderly patient accompanied with aneurysm of the main pulmonary artery]

A case of the elder PDA with aneurysm of the main pulmonary artery is reported. The patient was a 59-year-old female who had been suffering from severe heart failure. The PDA was closed directly from inside of the pulmonary artery using balloon catheter under usual cardiopulmonary bypass with limited circulatory arrest, and the aneurysm was repaired by aneurysmorrhaphy. The postoperative course was uneventful and she was discharged after 34 postoperative days. The pathological finding of the aneurysm of the main pulmonary artery is a cystic mucoid degeneration like a finding of Marfan syndrome. The etiology of the aneurysm of the main pulmonary artery seems to be extended Ao-PA shunt besides somewhat congenital change of the pulmonary artery.

Effects of alpha-adrenoceptor antagonists on electrical and mechanical responses of the isolated dog mesenteric vein to perivascular nerve stimulation and exogenous noradrenaline

The effects of four different alpha-adrenoceptor antagonists (prazosin, phentolamine, yohimbine, and nipradilol) on the electrical and mechanical responses of smooth muscle cells of the dog isolated mesenteric vein to perivascular nerve stimulation and exogenous noradrenaline were investigated. Perivascular nerve stimulation generated an excitatory junction potential (e.j.p.), a spike potential and a slow depolarization. The latter component was blocked by yohimbine or phentolamine at doses over 10(-7) M, while the former two components were suppressed by 10(-6)-10(-5) M yohimbine, but not by prazosin, nipradilol or phentolamine (up to 10(-5) M). Nerve-mediated muscle contractions were suppressed by these alpha-adrenoceptor antagonists in a concentration-dependent manner, at doses over 10(-7) M. The order of potency was yohimbine greater than nipradilol = phentolamine greater than prazosin. Exogenously applied noradrenaline (10(-6) M) depolarized the smooth muscle membrane and generated slow waves. The slow waves were blocked by all of these alpha-adrenoceptor antagonists (10(-5) M), while the depolarizations were inhibited by yohimbine (greater than 10(-7) M) or phentolamine (10(-5) M), but not by nipradilol or prazosin (up to 10(-5) M). Contractions produced by exogenously applied noradrenaline (10(-6) M) were inhibited by the alpha-adrenoceptor antagonists; yohimbine or phentolamine (10(-6)-10(-5) M) showed complete inhibition and prazosin or nipradilol (up to 10(-5) M) partial inhibition. Contractions produced by high-potassium or current-stimulation were suppressed by high-concentrations (10(-6)-10(-5) M) of these alpha-adrenoceptor antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Direct and indirect effects of histamine on the smooth muscle cells of the guinea-pig main pulmonary artery

Electrophysiological studies of the effects of histamine on the smooth muscles in the guinea-pig main pulmonary artery revealed that this amine produced muscle contraction with an associated depolarization of the membrane. Application of cimetidine potentiated and that of mepyramine suppressed these histamine-induced responses. In the presence of mepyramine, histamine produced membrane hyperpolarization. Contractions produced by perivascular nerve stimulation were potentiated by histamine, and additional application of cimetidine further potentiated while addition of mepyramine suppressed the histamine-induced enhancement. The amplitude of excitatory junction potentials was increased by application of histamine plus cimetidine and was decreased by histamine plus mepyramine. Excitatory effects of histamine on the electrical and mechanical responses were reduced by application of tetrodotoxin, prazosin, phentolamine or guanethidine. In the presence of these drugs, histamine produced depolarization with an associated increase in membrane resistance and, in high concentrations, produced spike potentials. Electrical and mechanical responses of the smooth muscles to exogenously applied noradrenaline were potentiated by pretreatment with histamine and cimetidine, and were suppressed by histamine and mepyramine. These observations indicate that the guinea-pig main pulmonary artery possesses two types of histamine receptor, H1- and H2-receptors, in the smooth muscles and in the perivascular adrenergic nerves. Stimulation of H1 or H2-receptor produces excitatory or inhibitory effects, respectively, on the smooth muscles and on the adrenergic nerves. Contraction of the muscle tissues produced by histamine is brought about by a direct effect on the smooth muscles and by increased release of transmitters, as a result of excitation of perivascular nerves.

The effects of 3,4-dihydro-8-(2-hydroxy-3-isopropylaminopropoxy)-3-nitroxy-2H-1-benzopyran (K-351) and its denitrated derivative on smooth muscle cells of the dog coronary artery

1 Effects of 3,4-dihydro-8-(2-hydroxy-3-isopropylaminopropoxy)-3-nitroxy-2H-1-benzopyran (K-351) and its derivative, 3,4-dihydro-8-(2-hydroxy-3-isopropylaminopropoxy)-3-hydroxy-2H-1-benzopyran (K-351 (N-)) on the electrical and mechanical properties of smooth muscles of the dog coronary and mesenteric arteries were investigated, and the findings were compared with data obtained with nitroglycerin. 2 In both proximal and distal regions of the coronary arteries, K-351 and nitroglycerin reduced the resting tone and suppressed the contractions produced by high-potassium solution or by current passage to the same extent, with no remarkable change in the electrical properties of the smooth muscle membrane. 3 In the proximal regions of the descending coronary artery, low and high concentrations of noradrenaline (NA) produced relaxation and contraction of the muscle, respectively. In the distal region, NA consistently relaxed the muscle with concentrations up to 10(-5) M. In both regions, the contraction or relaxation was suppressed by phentolamine or propranolol, respectively. 4 K-351 suppressed the NA-induced contraction. K-351(N-) potentiated the NA-induced contraction and suppressed the relaxation, but these actions were weaker than those of propranolol. Nitroglycerin suppressed the NA-induced contraction and the potency was weaker than that of K-351. 5 In the mesenteric artery, K-351 depressed excitatory junction potentials, spikes and contractions evoked by perivascular nerve stimulation, while K-351(N-) potentiated or depressed mechanical responses, with no change in the electrical responses. Nitroglycerin also depressed the mechanical responses evoked by perivascular nerve stimulation with no change in the electrical responses. 6 These results suggest that K-351 has a blocking action on postjunctional adrenoceptors, and also dilator actions similar to the actions of nitroglycerin on the dog coronary artery, while K-351 (N-) possesses a weak beta-adrenoceptor blocking action.

Electrical components contributing to the nerve-mediated contractions in the smooth muscles of the rabbit ear artery

Adrenergic transmissions were investigated by recording electrical and mechanical responses of the smooth muscle cells in the rabbit ear artery. Perivascular nerve stimulation generated an excitatory junction potential (e.j.p.) and a slow depolarization. The latter but not the former was suppressed by prazosin or phentolamine. Both the e.j.p. and slow depolarization were suppressed by tetrodotoxin (TTX) or guanethidine. Facilitation processes of e.j.p.s produced by repetitive stimulation of the nerves were not modified by prazosin, phentolamine, or yohimbine. Increasing the stimulus frequency increased the amplitude of e.j.p.s and slow depolarizations and, at high frequencies (greater than 5 Hz) generated a spike potential. Nicardipine (10(-7) M) blocked the spike potential and reduced the e.j.p. amplitude, but did not affect the slow depolarization. Amplitude of muscle contractions produced by transmural nerve stimulation increased with increase in the stimulus frequency. The nerve-mediated contractions produced by high-frequency stimulation (10 Hz) were reduced to 49% of the control value by prazosin (10(-6) M), to 79% by nicardipine (10(-7) M), to 34% by prazosin (10(-6) M) plus nicardipine (10(-7) M), and to 1.2% by TTX (3 X 10(-7) M). Exogenously applied noradrenaline depolarized the smooth muscle membrane and produced the muscle contraction. These effects of noradrenaline were antagonized by prazosin or phentolamine. Thus, in the rabbit ear artery, perivascular nerve stimulation produced three types of electrical responses, i.e., e.j.p., spike potential, and slow depolarization. The latter but not the former two was produced through activation of alpha 1-adrenoceptors. Nerve-mediated muscle contractions were the results of stimulation of alpha 1-adrenoceptors, generation of spike potentials, and of e.j.p.s.

Induction of action potentials in fish red muscle by denervation

The effects of denervation on the electrical membrane properties of fish red muscle were investigated. Forty to fifty hours after denervation, miniature endplate potentials disappeared abruptly and field stimulation of the nerve within the muscle failed to evoke endplate potentials, indicating that transmission failure occurred at this time. The membrane resistance of the red muscle fibre increased after denervation. Normally innervated fish red muscles do not generate action potentials in response to either nerve or direct muscle stimulation. However, approximately 3 weeks after nerve sectioning, action potentials could be induced in the muscles. The action potential was sodium-dependent, and was sensitive to tetrodotoxin. Actinomycin D injected in the early phase after operation suppressed the induction of the action potential. These results indicate that RNA synthesis is preliminary to the induction of the action potential mechanism, and that this mechanism is under neural control.

Effects of 3,4-dihydro-8-(2-hydroxy-3-isopropylaminopropoxy)-3-nitroxy-2H-1-benzopyran (K-351) on smooth muscle cells and neuromuscular transmission in the canine mesenteric artery

1 The effects of K-351 on the electrical and mechanical responses were investigated in the canine mesenteric artery by isometric tension recording and the use of intracellular microelectrodes. The results were compared to the responses observed with other alpha-adrenoceptor blocking agents. 2 K-351 (greater than 3 X 10(-7)M) consistently inhibited the contraction evoked by perivascular nerve stimulation; however, K-351 had no effect on the contraction evoked by direct muscle stimulation, after pretreatment with 3 X 10(-7)M tetrodotoxin. 3 Phentolamine enhanced and prazosin had no effect on the amplitude of contraction evoked by perivascular nerve stimulation at a high frequency (over 1.0 Hz). Pretreatment with phentolamine inhibited the contraction evoked by lower frequencies of perivascular nerve stimulation (below 0.5 Hz). 4 The potency for the inhibition of the response to perivascular nerve stimulation was in the order of K-351 greater than phentolamine greater than prazosin, while the contractions induced by exogenously applied noradrenaline (5 X 10(-7)M) were inhibited in the order: prazosin greater than phentolamine greater than K-351. 5 K-351 (less than 3 X 10(-5)M) did not modify the resting membrane potential or the membrane resistance, as estimated from the change in the amplitude of electrotonic potentials in the smooth muscle cell membranes. 6 K-351 (greater than 3 X 10(-7)M) inhibited the amplitude of the first e.j.p. and e.j.ps after completion of the facilitation process following stimulation at frequencies over 0.25 Hz. 7 K-351 (less than 3 X 10(-5)M) did not modify the compound action potentials recorded from peripheral nerve bundles distributed on the mesenteric artery. 8 Phentolamine (greater than 1 X 10(-8)M) inhibited the first e.j.p. but this agent either inhibited or enhanced the amplitude of e.j.p. after completion of the facilitation process produced by repetitive stimulation below or over 1.0 Hz stimulus frequencies, respectively. Prazosin (1 X 10(-6)M) had no effect on e.j.ps evoked by perivascular nerve stimulation, at any stimulus frequency applied. 9 These results indicate that K-351 inhibits the extra-junctional adrenoceptor with a slightly weaker potency than prazosin or phentolamine, but that this agent has a potent action as an intra-junctional adrenoceptor blocking agent. Phentolamine acts mainly on the extra-junctional adrenoceptors and also has weak actions on intra-junctional adrenoceptors, as a blocking agent. This agent also inhibits the presynaptic alpha 2-adrenoceptor. Prazosin inhibits only the extra-junctional alpha 1-adrenoceptor.