[Overview of technical advances in the diagnosis of pulp and periapical diseases]

Pulp and periapical diseases are common and frequently occurring diseases of which diagnosis and treatment must be dealt with by the dental clinicians. The diagnostic techniques of these diseases include evaluation of pulp vitality, measurement of pulp blood circulation and analysis and judgment of root canal anatomy. With the continuous emergence of digital and imaging technologies, the correct application of these technologies in clinic will help clinicians improve their abilities in diagnosis and treatment of related diseases. The present article summarizes and reviews the progress of assistant technology for diagnosing dental pulp and periapical diseases in recent years and puts forward some suggestions for its application.

[Association analysis between extracurricular physical activity and dyslipidemia among primary, middle and high school students in Guangzhou]

Objective: To investigate the prevalence of dyslipidemia, and to explore the association between extracurricular physical activity and dyslipidemia among primary, middle and high school students in Guangzhou. Methods: This cross-sectional study selected primary and middle school students in Guangzhou by the stratified cluster sampling method from March to December 2019. Physical examination and blood lipid test were performed. Information about students' basic characteristics and extracurricular physical activity was collected by questionnaire. Multivariate logistic regression analysis was used to determine the association between extracurricular physical activity and dyslipidemia in this cohort. Results: A total of 7 797 participants (mean aged (12.2±2.9) years) were included (4 194 (53.79%) boys and 3 603 (46.21%) girls]. The detection rates of high total cholesterol, high triglycerides, low high-density lipoprotein cholesterol, high low-density lipoprotein cholesterol and dyslipidemia were 12.49% (974/7 797), 6.44% (502/7 797), 6.62% (516/7 797), 11.31% (882/7 797) and 23.83% (1 858/7 797), respectively. Dyslipidemia rate was lower in the junior school students (21.39% (675/3 156)) than in primary school students (25.96% (896/3 451)) and high-school students (24.12% (287/1 190)) (P<0.001). The dyslipidemia rates of boys and girls were similar (23.15% (971/4 194) vs. 24.62% (887/3 603), P>0.05). Dyslipidemia rate was lower in students with extracurricular physical activity than in students without extracurricular physical activity (22.50% (923/4 102) vs. 25.30% (935/3 695), P<0.05). Multivariate logistic regression analysis showed that extracurricular physical activity was associated with lower risk of dyslipidemia (OR=0.88, 95%CI=0.79-0.99, P=0.033). Among all types of extracurricular physical activities, participating in extracurricular large ball game was associated with 28% lower risk among junior school students (OR=0.72, 95%CI=0.57-0.91, P=0.006). Conclusion: The prevalence of dyslipidemia is high among primary, middle and high school students in Guangzhou. Extracurricular physical activity is associated with reduced risk of dyslipidemia in this cohort.

[Research and application of new techniques for early diagnosis of caries]

The present review paper summarizes the available technical methods for early detection and diagnosis of dental caries lesions, as well as their clinical application range, advantages and disadvantages. Although there are many detection systems supported by new technologies and equipments in clinical practice, current evidence suggests that careful clinical visual and inspection tests, in combination with imagological examination, are still the gold standard for the detection and diagnosis of dental caries.

[Research progress in non-carious cervical lesions]

Non-carious cervical lesion is a common dental disease, which not only affects the aesthetic and function of the teeth, but also leads to dentin sensitivity, pulpitis and other consequences. The main causes of lesions are abrasion, abfraction, acid erosion and so on. The treatment design should depend on the etiology, defect size, location, symptoms and presence or absence of gingival recession.

[The application of extended high frequency audiometry in detecting the early hearing loss for polycystic ovarian syndrome]

Objective:To preliminarily explore the clinical significance of extended high frequency audiometry in evaluating the early hearing loss in patients with polycystic ovarian syndrome（PCOS）. The results were statistically analyzed. Method:The hearing threshold of forty young women diagnosed as PCOS and 20 healthy controls were obtained by using conventional audiometry（0.25-8.00 kHz） and extended high frequency（10-20 kHz） pure tone audiometry. Result:The hearing thresholds of the two groups were similar at conventional frequencies of 0.25，0.50，1.00，2.00 and 4.00 kHz（P>0.05）. The hearing threshold of PCOS group at 8-20 kHz frequency was significantly higher than that of the control group, and the difference was statistically significant（P<0.05）. The expanded high-frequency detectable rate was lower in PCOS group than that in control group, especially at 16 and 18 kHz （P<0.05） and the differences were statistically significant. Conclusion:The early hearing impairment of PCOS patients starts from the extended high frequency, which is more sensitive than the conventional pure tone audiometry in the early hearing impairment assessment of PCOS patients.

[Diffusion tensor imaging of the central auditory system in the elderly]

Objective:To evaluate the changes in the central auditory system of presbycusis by applying auditury brainstem response (ABR) and diffusion tensor imaging (DTI). Method:A total of twenty-five elderly subjects with expressed presbycusis, eight elderly subjects with normal hearing and fifteen healthy volunteers as young controls were enrolled in the study. Each participant was examined using ABR and DTI. ABR measures were obtained from all the subjects. The fractional anisotropy (FA) was measured at two brain regions of the auditory pathway-the inferior colliculus (IC) and Heschl's gyrus. Result:Higher FA values were recorded at the left side of the Heschl's gyrus in all three groups (P<0.05). There were no significant differences between the left and right side of the ABR results and FA values of inferior colliculus in the three groups (P>0.05). Aging increased ABR peak latencies, yet did not change the Ⅰ-Ⅴ interpeak latency interval. Comparing with the elderly subjects with normal hearing group, the wave Ⅴ latencies of the presbycusis group were prolonged (P<0.05). Comparing with the healthy control group, the FA values of the IC were reduced in both of the elderly subjects with normal hearing group and the presbycusis group (P<0.05). No statistically differences were observed between the presbycusis group and the elderly subjects with normal hearing group in the FA values of the IC (P>0.05). Significant differences between all groups were found in the FA values of the Heschl's gyrus, with higher values in the elderly subjects with normal hearing group than in the presbycusis group and even higher values in the healthy control group than in the elderly subjects with normal hearing group (P<0.05). Conclusion:The results indicated that the age-related microstructural changes exist in the central part of the auditory system, which are more obvious in the patients with presbycusis.

[Analysis of deafness-related gene mutations in 23 nonsyndromic hearing impairment families in Guangxi Zhuang Autonomous Region]

Objective:To investigate the genetic characteristics of the mutations responsible for nonsyndromic hearing loss in Guangxi Zhuang Autonomous Region, and analyze the deafness-related gene mutations in nonsyndromic hearing impairment families in this region.Method:In 23 nonsyndromic hearing impairment families,66 patients or their families were enrolled as family history group and 167 patients or their families without family histiory as control group, respectively. Deafness gene mutations were determined with deafness-related gene mutations detection kits. The mutation rates among the deafness probands, the hearing impairment patients and their audibility relatives were analyzied. Whole length sequences of the deafness-related gene were detected if there was mutation by the kits, to explore Guangxi region-specific mutation-sites.Result:Common deafness-related gene mutation rate in family history group(31.82%) was higher than that in control group(11.38%), including those that in GJB2 homozygous(21.21%), SLC26A4 homozygous (9.09%), both were higher than the control group (GJB2 homozygous 5.99%, SLC26A4 homozygous 3.59%) . The rate of common deafness-related gene mutations in the deafness probands was 34.78%, in the hearing impairment patients was 30.56%, in their audibility relatives was 29.63%, all of which were higher than those in the control group. We found three rarely seen mutations, SLC26A4 IVS11+47T>C, 1548insC and GJB2 109 A>G, by detecting the whole-length sequences of the deafness-related gene.Conclusion:The results indicated that GJB2 and SLC26A4 were the most frequent mutant genes in Guangxi region. Analysis of the individual family were helpful to linkage the mutations and the deafness.

[Transnasal endoscopic surgery of communicating neoplasm outside cerebral dura mater and orbital fasciae]

Objective:This paper is intend to observe the feasibility of surgical approach with which communicating neoplasm outside cerebral dura mater and orbital fasciae was removed by transnasal endoscopic surgery.Method:Nine patients suffered from communicating neoplasm in the area of naso-orbital-cranio complex were treated with transnasal endoscopic surgery. The size of skull base bone defect was from 1.25 cm×1.13 cm to 3.25 cm×2.69 cm. No eye enucleation was done. No reconstructions of skull base and medial wall of orbital cavity were done. Iodoform gauze was packed in paranasal sinuses fourteen days. Patients with malignant tumor were treated radiation therapy and chemical therapy after surgical treatment. The degree of resection, complications of intracranial and orbital cavities, survival condition were the focus of this study.Result:The tumor were completely removed and all operations were successfully completed by trasnasal endoscopic surgery. Only one patient was required blood transfusion due to seriously bleeding from tumor during the operation. There was no orbital, intracranial, and vascular complications. The defect of bone at skull base and lamina papyracea were automatic reconstructed. Three patients have showed recurrence of neoplasm, and two of them died during two years of following up time.Conclusion:Transnasal endoscopic surgery is a safe, reliable and effective approach to treat communicating neoplasm in the area of naso-orbital-cranio complex, of which main part of tumor exists in the sinunasal cavity.

[Analysis of the SLC26A4 mutation from 230 deafness patients in Guangxi region]

Objective:To investigate the mutation characteristics of SLC26A4 gene from 230 hearing loss patients in Guangxi region.Method:Two hundred thirty patients with hearing loss were enrolled in the study. Eight mutation sites in SLC26A4 gene were tested; the types of gene mutation and the inner ear CT features of the mutationpositive patients were analyzed.Result:Among 230 deafness patients,the total mutation rate of SLC26A4 gene is 2.61%(6/230). The types of gene mutation include SLC26A4 IVS7-2A> G heterozygous in 2 case(0.87%).1226G> A homozygous in 1 cases(0.43%),IVS7-2A>G，IVS11+47T>C and 1548insC mutations in 2 cases(0.87%).Conclusion:The mutation rate of SLC26A4 gene in Guangxi region is lower than the national average level. The main mutation type in Guangxi region is SLC26A4 IVS7 2A>G. In this study, two gene mutations (SLC26A4 IVS11+47T> C and 1548insC) are firstly found, suggesting that some rare mutation types of SLC26A4 may exist in patients living in Guangxi region.

Functionalized bio-artifact fabricated via selective slurry extrusion. Part 2: Fabrication of ceramic dental crown

Functionalized ceramic dental crown was successfully fabricated through selective slurry extrusion (SSE) based technique of solid freeform fabrication (also known as rapid prototyping). After sintering, the decomposed tourmaline powders were embedded in ZrO2 matrix. The far infrared emission properties of the ceramic dental crown were improved due to the increase of the numbers of infrared active bonds from tourmaline. This new dental restoration process presents potential to provide dental patients with functionalized artificial teeth, which benefits the body health by the way of emitting far infrared rays in ambient temperatures.

Preliminary study of the presence and association of bacteria and archaea in teeth with apical periodontitis

AIM

To investigate, by reverse transcription polymerase chain reaction (RT-PCR), the presence and association of bacteria and archaea in primary and secondary root canal infections.

METHODOLOGY

A total of 77 root canal samples from 77 Chinese patients, 42 with necrotic pulp tissues (primary infection) and 35 with failed prior conventional root canal treatment (secondary infection), aseptically exposed at the first patient visit, were studied. Total RNA was isolated directly from each sample, and 16S rRNA gene-based RT-PCR assays were used to determine the presence of bacteria and archaea, respectively.

RESULTS

Bacteria were detected in 39/42 (93%) of root canal samples from teeth with primary infections, and archaea in 16/42 (38%). In the cases diagnosed as secondary root-infected canals, bacteria were detected in 30/35 (86%), whilst archaea were detected in 6/35 (17%) of cases. Amongst the canals, which were positive for bacteria, archaea were always found in combination with bacteria. The incidence of symptomatic cases positive for both bacteria and archaea (16/22, 73%) were significantly higher than those positive for bacteria alone (21/47, 45%) (P < 0.05).

CONCLUSIONS

This study confirms the presence of archaea in root canal infections and further implicates them in an association with clinical symptoms. The nature of this association requires further study.

Prevalence and molecular diversity of Archaea in subgingival pockets of periodontitis patients

INTRODUCTION

The aim of this study was to investigate the prevalence and molecular diversity of Archaea in the subgingival crevices of patients with chronic periodontitis.

METHODS

Subgingival plaque was collected from 41 patients with chronic periodontitis and 15 healthy subjects. The prevalence of Archaea in those plaque samples was tested by polymerase chain reaction with two broad-range archaeal primer sets. Amplicons from eight Archaea-positive plaque samples were cloned and sequenced for molecular diversity analysis using one of these two primer sets and a novel third primer set.

RESULTS

Archaea were detected in the subgingival plaque of patients with chronic periodontitis at a prevalence of 70.7-73.2%, but were not detected in healthy subjects. Using one primer set, all sequences of the archaeal amplicons were identified as Methanobrevibacter oralis-like species. With another primer set, the amplicons were also found to be identical to the uncultured M. oralis-like species except one phylotype was found to belong to the class Thermoplasmata.

CONCLUSION

Archaea might be correlated with periodontal diseases. The diversity of Archaea associated with periodontitis was limited. Almost all sequenced amplicons fell into the genus Methanobrevibacter of the Euryarcheota phylum. M. oralis-like species was the predominant but non-exclusive archaeon in the subgingival dental plaque of patients with periodontitis.

Association of uncultivated oral phylotypes AU126 and X112 with periodontitis

OBJECTIVE

To discuss the relationship between uncultivated pathogenic bacteria and periodontitis.

SUBJECTS AND METHODS

Specific polymerase chain reaction (PCR) primers were designed for phylotypes AU126 and X112; PCRs were applied to determine the prevalence of these phylotypes in 35 patients with chronic periodontitis, 26 patients with plaque-induced gingivitis and 20 healthy control subjects.

RESULTS

The specificity of each primer is validated on the basis of the results from sequence analysis of PCR products. AU126 and X112 were detected in the subgingival plaque samples in all the three groups. The prevalence of AU126 in subgingival plaque in chronic periodontitis (77.1%) and plaque-induced gingivitis (61.5%) is relatively higher than that in the healthy subjects (10.0%), and the difference is statistically significant (P < 0.01). The prevalence of X112 in subgingival plaque in periodontitis patients (85.7%) is higher than that in healthy subjects (30.0%), the difference (P < 0.01) being equally statistically significant. The difference between the chronic periodontitis group and the plaque-induced gingivitis group (50.0%) is statistically significant (P < 0.05).

CONCLUSIONS

It might be assumed that the novel uncultivated AU126 phylotype could possibly be related to chronic periodontitis and plaque-induced gingivitis, and that X112 might play a role in the progress of lesion from gingivitis to periodontitis.

[Research on the effect of amalgam restorations on human nervous system]

OBJECTIVE

To understand the influence of amalgam restorations on human nervous system.

METHODS

WHO NCTB and neurobehavioral questionnaire were used to make an epidemiologic investigation of people with amalgam restorations,and compared them with the control groups.

RESULTS

The scores of people whose teeth were filled with amalgam within 20 years were much higher than those beyond 20 years in digit span test and digit symbol test. In the latter group there were more people who thought they occurred 'memory descending' than the former. It indicated that there was some intra-relation between long-term amalgam contacting and memory descending. But in 19-29 and 30-39 age groups, the test group scored higher than the control group significantly in digit span test, and in digit symbol test the test group also had a score much higher than the control group in 30-39 age groups. This indicated that amalgam had no effect on memory. In pursuit aiming test II the error number of the test group was higher than that of the control group, and people who had amalgam restorations over 20 years occurring 'motion unflexible' were more than those within 20 years. But in the same time, in 30-39,40-49 age groups the test groups scored higher than the control groups in right number and sum number index,so we were not sure that amalgam do any harm to motor nerve.

CONCLUSION

It can not be determined that amalgam restorations have any effect on human nervous system currently.

[Radiofrequency treatment of hemangioma of nasal cavity under nasal endoscopy]

OBJECTIVE

To further understand the advantage of radiofrequency treatment of hemangioma of nasal cavity under nasal endoscopy.

METHOD

Fifteen cases with hemangioma of nasal cavity were treated with radiofrequency under nasal endoscopy.

RESULT

The hemangioma of fifteen cases could be removed completely. The complication was absent. None of them recurred in six months to four years following up.

CONCLUSION

This method has many advantages such as clear operation visual field, less hemorrhage and postoperative pain, no facial scar. The radiofrequency under endoscopy is valuable in treatment for hemangioma of nasal cavity.

[Separation and identification of polyclonal antibodies against type II fimbriae of actinomyces viscosus 5951]

OBJECTIVE

This study was aimed to prepare the polyclonal antibodies against type II fimbriae of actinomyces viscosus 5951.

METHODS

Purified type II fimbriae of actinomyces viscosus 5951 were obtained by physical and chemical ways. Then antibodies against type II fimbriae were prepared through immunity of poly ways and tested by double immunodiffusion.

RESULTS

The molecular quality of type II fimbriae was 34ku.Concentration of antibodies against type II fimbriae reached 1:64 after immunity of poly ways.

CONCLUSION

The molecular quality of type II fimbriae was 34ku.The titre of the antibodies was 1:64, and had mild cross reaction with type I fimbriae.

Alleviation of pre-exposure to low-dose 16O8+ ion on mouse testicular histological damage induced by subsequent high-dose irradiation

The testes of the B6C3F1 hybrid strain mice were irradiated with 0.05 Gy of 16O8+ ion as the pre-exposure dose (D1), and were then irradiated with 2 Gy of 16O8+ ion as challenging radiation dose (D2) at 4 h after per-exposure. Testicular morphology was observed by light microscope at 35th day after radiation. The results showed that irradiation of mouse testes with 2 Gy of 16O8+ ion significantly impaired, mainly reduction of tubule diameter and decrease or loss of germ cells in various developing stages, especially spermatogenic elements. Pre-exposure to a low-dose (0.05 Gy) of 16O8+ ion significantly alleviated above mentioned damage on testicular morphology induced by subsequent a high-dose (2 Gy) radiation.

[A preliminary study on fimbriae subunits and molecular weight of actinomyces viscosus 5951]

OBJECTIVE:To preliminarily analyse the subunits and molecular weight of fimbriae of actinomyces viscosus 5951.METHODS:To do the immunoblotting test of the only II fimbriae type of mutant strain of T14V.RESULTS:It showed that there was only one 31ku band,which indicated that the fimbriae of actinomyces viscosus 5951 was composed of the same subunits of 31ku molecular weight. CONCLUSION:According to the previous reports and results of present study,the molecular weight of fimbriae of actinomyces viscosus 5951 was speculated to be 124ku and the fimbriae was composed of 4 same subunits.

Chromosomal aberrations induced by 12C6+ heavy ion irradiation in spermatogonia and spermatocytes of mice

The testes of Kun-Ming strain mice were radiated with different doses of 12C6+ ion or 60Co gamma-ray. Chromosomal aberrations induced in spermatogonia and spermatocytes were analyzed by the air-drying method. The relative biological effectiveness (RBE) of 12C6+ ion was calculated with respect to 60Co gamma-ray for the induction of chromosomal aberrations. The 12C6+ ion and 60Co gamma-ray dose-response relationships for chromosomal aberrations were plotted by linear quadratic models. The results showed that there was an increase in frequency of chromosomal aberrations in all the treated groups compared to controls. The RBE values were 1.67 for aberrations of spermatogonia and 1.66 for aberrations of spermatocytes for a dose of 2.0 Gy. Moreover, a different distribution of the various types of aberrations has been found for 12C6+ ion and 60Co gamma-ray irradiations. The dose-response relationships for 12C6+ ion and 60Co gamma-ray exhibited negative curvature in both spermatogonia and spermatocytes groups: the frequencies of aberrations increased sharply at low doses and exhibited less sharp increases for higher doses, which may be related to an interaction between the chromosomal damage and a block in cell cycle. Our results may provide useful information for the assessment of genetic risks of humans exposed to heavy ions.

Effects of pre-exposure of mouse testis with low-dose (16)O8+ ions or 60Co gamma-rays on sperm shape abnormalities, lipid peroxidation and superoxide dismutase (SOD) activity induced by subsequent high-dose irradiation

PURPOSE

To investigate the effects of pre-exposure of mouse testis with low-doses of (16)O8+ ions or 60Co gamma-rays on sperm shape abnormalities, lipid peroxidation and superoxide dismutase (SOD) activity induced by subsequent high-dose irradiation.

MATERIALS AND METHODS

Testes of the B6C3F1 hybrid strain mice were pre-irradiated with 0.05 Gy of (16)O8+ ions or 60Co gamma-rays and then after 4 h given a test irradiation with 2 Gy of the same radiation type. SOD activity and thiobarbituric acid reactive substances (TBARS) in the testes were determined by spectrophotometric and TBA methods respectively at 4 h after irradiation. Testis weight, sperm count and sperm morphology were analysed at day 35 after irradiation.

RESULTS

Compared with controls, there was a significant increase in SOD activity and a significant decrease in TBARS level of pretreated testes. Testis weight loss, sperm count reduction and sperm abnormalities were significantly lower in the pretreated testes. The bioeffects of a 2 Gy dose of (16)O8+ ions relative to 60Co gamma-rays were 1.84 +/- 0.28 for testis weight, 1.22 +/- 0.25 for sperm count and 1.29 +/- 0.10 for sperm abnormalities.

CONCLUSIONS

These data suggest that pre-exposure of testes with a low dose of heavy ions or gamma-rays renders the organ more resistant to subsequent high-dose irradiation. The increase of SOD activity and the decrease of lipid peroxidation levels induced by low-dose ionizing irradiation may be involved in this resistance. The effects with heavy ion irradiation were greater than with gamma-rays.

Mutations clustered in exon 5 of the p53 gene in primary nasopharyngeal carcinomas from southeastern Asia

Mutations in the p53 tumor suppressor gene play an important role in the development of many common human malignancies. In nasopharyngeal carcinomas (NPC), p53 gene mutations were not detected in primary tumors, with one exception for a primary tumor displaying a p53 mutation at codon 280, whereas p53 mutations were identified in some metastatic and nude mouse-passaged NPC specimens. In the present report, 41 NPC primary tumors of the undifferentiated carcinoma nasopharyngeal type (UCNT; 21 from Hong Kong and 20 from Guangxi, southeastern China) were studied. Four point mutations that result in amino acid substitutions were identified by PCR amplification of exons 2-9 and direct DNA sequencing, combined with PCR-single-strand conformation polymorphism analysis. The 4 mutations detected were clustered within the DNA stretch from codon 175 to 177. Our data, taken together with those of others, suggest that mutation in p53 may occur in NPC at various points during tumorigenesis. Alternative mechanisms of p53 inactivation in NPC are also possible.

[Applied DNA-DNA hybridization in determination of oral Streptococcus.]

Quantitative measurement of DNA-DNA hybridization is a new technique for determination of unknown bacteria.It is more valuable how to identify strains which is rare difference on phenotypic characteristics.It is important to resolve bactericial taxionmy and identify new strain.Four strain of Streptiococcus are determined by hybridization of DNA.Some technique problems are discussed.Such as purification,precision of DNA and temperature as well as time of DNA hybridization and standard of judgment.

[Anaerobes in infected canals: a preliminary study]

Anaerobes of 17 infected canals with periapical periodontitis were studied. Most of root flora were not only anaerobes but also aerobes. Anaerobes were predominant in chronic periapical periodontitis. Major anaerobes isolated from canals were peptostreptococcus, B. melaninogenicus and B. oralis. The chi-square results indicated that the peptostreptococcus were significantly related to apical radiolucency and B. melaninogenicus were significantly related to percussion or foul smell. Animal experiment results showed that rats inoculated with mixed flora developed many abscesses. But the monoinfected rats had infiltration of PMNs, dilation and hypermia of vessels. B. melaninogenicus, B. oralis and mixed flora had liquefied gelatin and indicated these bacteria had collagenase which could dissolve collagen fibers and significantly related to destroy of collagen fibers and bone in periapical tissues.

Characterization of a new CCK antagonist, L364,718: in vitro and in vivo studies

In this study we examined a novel, orally effective, nonpeptidal cholecystokinin (CCK) antagonist, 3S(-)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepine-3-yl) -1H-indole-2-carboxamide (L364,718) on CCK-induced amylase release. We used isolated rat pancreatic acini and incubated them with CCK-8 with or without various CCK receptor antagonists. L364,718 (3-100 nM), proglumide (1-10 mM), and the proglumide derivative CR1409 (1-30 microM) each caused a progressive rightward shift in the CCK-8 dose-response curve without a change in maximal amylase secretion. Plotting the data according to the method of Schild indicated competitive inhibition. The Kis for L364,718, CR1409, and proglumide were 0.25 nM, 0.15 microM, and 0.5 mM, respectively. Thus L364,718 was 600-fold more potent than CR1409 and 2,000,000-fold more potent than proglumide in inhibiting CCK-8-induced amylase release. Inhibition of 125I-Bolton-Hunter-CCK-8 binding to acini by these receptor antagonists had a similar rank potency. L364,718 was tested against other pancreatic exocrine secretagogues and was effective against agonists that only act through the CCK receptor. In rats, diversion of pancreatic juice from the duodenum stimulated pancreatic amylase output and elevated plasma CCK levels. The stimulated amylase secretion was blocked by intravenous administration of L364,718. Furthermore, extracted plasma CCK from rats with diversion of pancreatic juice from the duodenum stimulated amylase release from pancreatic acini, and this stimulation was blocked by addition of L364,718.(ABSTRACT TRUNCATED AT 250 WORDS)