Preparation and use of interphase Xenopus egg extracts

In this unit, Xenopus eggs are isolated from hormonally primed female frogs, and then the extract is treated with cyclohexamide so it remains in interphase of the cell cycle. In the presence of sperm chromatin and ATP, membrane vesicles in the extract fuse to assemble nuclei, making the extract suitable for studies of DNA replication and nuclear transport.

An interactive software module for DPOAE signal estimation

This work presents a freely downloadable software module for the estimation of distortion product otoacoustic emission (DPOAE) signals based on a novel adaptive signal processing technique of measurement of signals under large amounts of noise. DPOAE signal estimation is an effective method of testing the human peripheral auditory function and is extensively used in newborn hearing screening. Current technology is based on the averaging of long strings of data and subsequent Fourier analysis, and suffers from the need for relatively long measurement time and acoustically insulated examination rooms. The method presented in this work features structural simplicity which renders it particularly attractive for implementation on both software and hardware platforms. As such, a fully functional software implementation of the proposed algorithm is developed and is made publicly available for free distribution to researchers in the area. The proposed technique offers a high degree of immunity with regard to background noise and parameter variations. Compared to conventional methods, the proposed method offers a shorter measurement time which is of significant value in clinical examinations. Performance of the proposed method is demonstrated with the aid of computer simulation and is verified in laboratory using recorded clinical data. Snapshots of the developed software environment analyzing both simulated and real clinical data are also presented.

Immunity to adeno-associated virus serotype 2 delivered transgenes imparted by genetic predisposition to autoimmunity

Adeno-associated virus (AAV) is widely considered a promising vector for therapeutic gene delivery. This promise is based on previous studies assessing AAVs safety and toxicity, ability to infect nondividing cells, elicit a limited immune response and provide long-term gene expression. However, we now find that earlier studies underappreciated the degree of AAV immunogenicity as well as the extent to which genetic background, through regulation of immune responsiveness, influences the duration of gene expression and thereby the effectiveness of AAV-mediated gene therapy. We evaluated antibody responses in 12 mouse strains to AAV serotype 2 (AAV2) and AAV2-expressed transgene products including green fluorescent protein (GFP), human alpha1-antitrypsin and murine interleukin-10. As expected, all immunocompetent mice administered AAV2 developed serologic evidence of immune responsiveness to the virus. However, a previously unidentified serologic prozone effect was observed suggesting that the concentrations of anti-AAV2 antibodies may have historically been subject to marked underestimation. Furthermore, strains with genetic predisposition to autoimmunity (eg, NOD, NZW, MRL-lpr) specifically imparted a functionally deleterious immune response to AAV-delivered transgene products. These findings suggest that more thorough studies of anti-AAV immunity should be performed, and that genetic predisposition to autoimmunity should be considered when assessing AAV efficacy and safety in humans.

Functional MRI changes during panic anticipation and imagery exposure

While undergoing fMRI, six patients with DSM IV diagnosis of panic disorder and six normal controls performed directed imagery of neutral, moderate and high anxiety situations based on an individually determined behavioral hierarchy. Brain activity was compared during high vs neutral anxiety blocks for each group of subjects using SPM99b. Panic patients showed increased activity in inferior frontal cortex, hippocampus and throughout the cingulate both anterior and posterior, extending into the orbitofrontal cortex and encompassing both hemispheres. These areas may constitute the important circuit in the psychopathology of panic disorder. We propose that this pattern of activity may enhance the encoding and retrieval of strong emotional events, facilitating the recapitulation of traumatic experiences and leading to panic disorder in vulnerable individuals.

Adeno-associated virus vector-mediated IL-10 gene delivery prevents type 1 diabetes in NOD mice

The development of spontaneous autoimmune diabetes in nonobese diabetic (NOD) mice provides for their use as a model of human type 1 diabetes. To test the feasibility of muscle-directed gene therapy to prevent type 1 diabetes, we developed recombinant adeno-associated virus (rAAV) vectors containing murine cDNAs for immunomodulatory cytokines IL-4 or IL-10. Skeletal muscle transduction of female NOD mice with IL-10, but not IL-4, completely abrogated diabetes. rAAV-IL-10 transduction attenuated the production of insulin autoantibodies, quantitatively reduced pancreatic insulitis, maintained islet insulin content, and altered splenocyte cytokine responses to mitogenic stimulation. The beneficial effects were host specific, as adoptive transfer of splenocytes from rAAV IL-10-treated animals rapidly imparted diabetes in naive hosts, and the cells contained no protective immunomodulatory capacity, as defined through adoptive cotransfer analyses. These results indicate the utility for rAAV, a vector with advantages for therapeutic gene delivery, to transfer immunoregulatory cytokines capable of preventing type 1 diabetes. In addition, these studies provide foundational support for the concept of using immunoregulatory agents delivered by rAAV to modulate a variety of disorders associated with deleterious immune responses, including allergic reactions, transplantation rejection, immunodeficiencies, and autoimmune disorders.

Effects of L-749,329, an ET(A)/ET(B) endothelin receptor antagonist, in a porcine coronary artery injury model of vascular restenosis

BACKGROUND

Previous studies in animal models of angioplasty have suggested a role in neointimal hyperplasia for endothelins (ETs), potent vasoconstricting peptides that also exert growth-promoting effects. The present studies were undertaken to test the hypothesis that endothelin receptor blockade can reduce neointimal thickening in injured porcine coronary arteries.

METHODS AND RESULTS

An ET(A)/ET(B) antagonist, L-749,329, was evaluated as an inhibitor of intimal thickening in a porcine balloon/stent model of coronary artery injury. L-749,329 competitively inhibited [(125)I]ET-1 binding to porcine ET(A) (IC(50) approximately 0.3 nmol/L) or ET(B) (IC(50) approximately 20 nmol/L) receptors and inhibited ET-1-stimulated signaling in cell culture. In anesthetized pigs, big ET-1-stimulated increases in systemic blood pressure were totally inhibited after intravenous infusion of L-749,329 (>/=0.2 mg. kg(-1). h(-1)). In vascular injury studies, pigs were treated with vehicle or L-749,329 (1 mg. kg(-1). h(-1)) beginning 2 days before and continuing 28 days after experimental angioplasty. Left anterior descending, left circumflex, and/or right coronary arteries were injured by inflation of an angioplasty balloon wrapped with a coiled metallic stent. After 28 days, mean neointimal thickness in the L-749,329-treated group was reduced by 9.0% compared with vehicle-treated controls, but this effect was not statistically significant (P=0.13).

CONCLUSIONS

Blockade of endothelin receptors for 28 days with only a mixed ET(A)/ET(B) receptor antagonist is insufficient to substantially inhibit intimal hyperplasia after balloon/stent coronary artery injury in the pig, in contrast to results with a selective ET(A) antagonist. The effects of selective or mixed ET(A)/ET(B) antagonists in diseased vessels remain to be determined in this model.

Identification of a new vertebrate nucleoporin, Nup188, with the use of a novel organelle trap assay

The study of the nuclear pore in vertebrates would benefit from a strategy to directly identify new nucleoporins and interactions between those nucleoporins. We have developed a novel two-step "organelle trap" assay involving affinity selection and in vitro pore assembly. In the first step, soluble proteins derived from Xenopus egg extracts are applied to a column containing a ligand of interest. The bound proteins are then tagged by biotinylation and eluted. In the second step, potential nucleoporins are selected for by virtue of their ability to assemble into annulate lamellae, a cytoplasmic mimic of nuclear pores. The incorporated proteins are then recognized by their biotin tag. Here we use the lectin wheat germ agglutinin (WGA) as ligand; WGA inhibits nuclear transport and has been shown to directly bind three known nucleoporins from Xenopus extract, Nup62, Nup98, and Nup214, all of which contain N-acetylglucosamine residues. Under reduced-stringency conditions, three additional proteins bind to WGA-Sepharose and are revealed by the organelle trap assay. We identified all three as partner nucleoporins. Two were discovered to be Xenopus Nup93 and Nup205. The third is a novel vertebrate nucleoporin, Nup188. This new vertebrate protein, Xenopus Nup188, exists in a complex with xNup93 and xNup205. The Nup93-Nup188-Nup205 complex does not bind directly to WGA but binds indirectly via the N-acetylglucosamine-modified nucleoporins. A gene encoding human Nup188 was also identified. The discovery of vertebrate Nup188, related to a yeast nucleoporin, and its novel protein-protein interactions illustrates the power of the two-step organelle trap assay and identifies new building blocks for constructing the nuclear pore.

Thiopurine methyltransferase polymorphic tandem repeat: genotype-phenotype correlation analysis

BACKGROUND

Thiopurine methyltransferase (TPMT) is a genetically polymorphic enzyme that catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine. Recently, a variable number tandem repeat (VNTR) within the TPMT promoter has been reported to "modulate" levels of this enzyme activity.

METHODS

We set out to perform genotype-phenotype correlation analysis for the polymorphic TPMT tandem repeat in 1211 clinical laboratory samples in which red blood cell (RBC) TPMT activity had been measured and to compare those results with data for 279 control DNA samples.

RESULTS

TPMT VNTR length varied from three to nine repeats ( *V3 to *V9), but the most common alleles were *V4 and *V5, with frequencies in the control samples of 0.54 and 0.36, respectively. The clinical laboratory samples were then stratified into those with "low," "intermediate," or "high" levels of RBC TPMT activity; that is, samples presumed to be homozygous for open reading frame (ORF)-based variant alleles, heterozygous for those alleles, or homozygous for the "wild-type" ORF sequence, respectively. TPMT VNTR genotype *V4/*V5 was associated with significantly higher RBC TPMT activity than were *V4/*V4 or *V5/*V5. Lowest activity levels were associated with genotypes that included an allele with more than 5 repeat elements. However, all of these effects were quantitatively small. Finally, there was linkage disequilibrium between VNTR allele *V5 and TPMT*3A, the most common ORF-based polymorphism associated with very low TPMT activity in white persons.

CONCLUSIONS

These observations suggest that, in addition to the striking effects of ORF-based single nucleotide polymorphisms on TPMT activity, the VNTR within the 5'-flanking region of the TPMT gene also may modulate levels of RBC TPMT activity.

Evidence of correction of open bite malocclusion using active vertical corrector treatment

This study used a cephalometric analysis that isolated tipping and bodily tooth movements of the upper and the lower incisors and measured vertical skeletal changes in the anterior region of the maxilla and mandible to evaluate the outcome of two-phase nonextraction treatment for open bite malocclusion. Twenty-nine subjects treated with an active vertical corrector (AVC) followed by fixed 022 orthodontic appliances were selected by one orthodontist from his private practice. All subjects lacked vertical incisor contact at the start of treatment and had adequate initial, end of phase 1, and deband lateral cephalograms. Each subject in the treated group was matched by age and sex with an untreated subject from the Broadbent Bolton Collection, Cleveland, OH. Data were collected for three time intervals; phase 1 treatment with the AVC (T1 to T2), phase 2 fixed-appliance treatment (T2 to T3), and over the total treatment period (T1 to T3). Analysis of the data showed no statistically significant (P < or = .002) changes between treated subjects and controls for any variables during the phase 1 (T1 to T2) or phase 2 (T2 to T3) treatment intervals. However, overbite was significantly improved compared with controls (P < or = .002) during the T1 to T3 time interval. It was concluded that two-phase treatment with the AVC followed by fixed orthodontic appliance treatment results in a statistically significant increase in incisor overbite. The observed increase in overbite was the result of small but clinically significant changes in relative mandibular vertical growth, bodily incisor movement toward the occlusal plane, and lingual tipping of the lower incisors.

Nutrition Practice Guidelines for Type 1 Diabetes Mellitus positively affect dietitian practices and patient outcomes. The Diabetes Care and Education Dietetic Practice Group

OBJECTIVES

Assess the acceptance and ease of use of Nutrition Practice Guidelines for Type 1 Diabetes Mellitus by dietitians in a variety of settings; determine if nutrition care activities of dietitians change when practice guidelines are available; measure changes in patient control of blood glucose level, measured as glycated hemoglobin (HbA1c); compare patient satisfaction with care and perceptions about quality of life.

DESIGN

Using the approach of outcomes research, volunteer dietitians were recruited and assigned randomly to a usual care group or a practice guidelines group. Patients with type 1 diabetes were enrolled by dietitians and followed up for a 3-month period. Outcome measures included dietitian care activities, changes in patient HbA1c levels, and patient satisfaction and perceptions about quality of life.

SUBJECTS/SETTINGS

Dietitians from across the United States who responded to a recruitment notice participated. Their work settings included diabetes referral centers, endocrinology clinics, primary care and community health clinics, hospitals, and a worksite clinic. They recruited patients from their setting for the study. Outcome data were available from dietitians providing care to 24 patients using the new practice guidelines and dietitians providing care to 30 patients using more traditional methods.

STATISTICAL ANALYSIS

chi 2 Test, t test, and analysis of covariance.

RESULTS

Dietitians in the practice guidelines group spent 63% more time with patients and were more likely to do an assessment and discuss results with patients than dietitians in the usual care group. Practice guidelines dietitians paid greater attention to glycemic control goals. Levels of HbA1c improved at 3 months in 21 (88%) of practice guidelines patients compared with 16 (53%) of usual care patients. Practice guidelines patients achieved greater reductions in HbA1c level than usual care patients (-1.00 vs -0.33). This difference was statistically significant and clinically meaningful.

CONCLUSIONS/APPLICATIONS

Dietitians responded positively to practice guidelines for type 1 diabetes. Use of guidelines resulted in changes in dietitian practices and produced greater improvements in patient blood glucose outcomes at 3 months compared with usual care. Practice guidelines did not significantly influence patient satisfaction with care of perceived quality of life.

Patients' attitudes about autonomy and confidentiality in genetic testing for breast-ovarian cancer susceptibility

The identification of BRCA1 and BRCA2, two breast-ovarian cancer susceptibility genes, has brought many ethical and social issues to the forefront. This paper presents the results of a survey assessing the attitudes of 238 unaffected first-degree relatives of women with breast or ovarian cancer regarding the ethical issues of autonomy and confidentiality as they relate to BRCA1/2 testing. Baseline knowledge about BRCA1/2 and ethnic and psychosocial characteristics of our study population were examined to determine their association with women's attitudes. The majority of women (86-87%) felt that health care providers should not disclose the results of genetic tests for breast-ovarian cancer susceptibility to insurance companies or employers without written consent; however, only 56-57% felt that written consent should be required for a spouse or immediate family to receive this information. Ninety-eight percent of the women surveyed agreed that genetic testing for breast-ovarian cancer risk should be voluntary. Likewise, most women (95%) agreed that a person should be able to have genetic testing against a doctor's recommendation and 88% of the women surveyed agreed that parents should be able to consent to genetic susceptibility testing on behalf of their minor children. African American women were less concerned than Caucasian women about the protection of confidentiality in families, they were more likely to agree that an individual should still have access to testing when their physicians recommended against it, and they were more supportive of parents' rights to consent to genetic predisposition testing on behalf of their minor children. Women with coping styles characterized by higher optimism were more likely to favor access to genetic testing when a physician recommended against it, and to support parents' rights to consent to testing of their minor children. Therefore, the setting and manner in which genetic counseling and testing are delivered must be appropriately tailored to reflect these attitudinal differences and preferences.

Haplotypes of angiotensinogen in essential hypertension

The M235T polymorphism of the angiotensinogen gene (AGT) has been associated with essential and pregnancy-induced hypertension. Generation of haplotypes can help to resolve whether the T235 allele itself predisposes to the development of hypertension or acts as a marker of an unknown causal molecular variant. We identified 10 diallelic polymorphisms at the AGT locus and genotyped both a series of 477 probands of hypertensive families and 364 controls, all French Caucasians, as well as a series of 92 hypertensives and 122 controls from Japan. Despite a large ethnic difference in gene frequency, a significant association of T235 with hypertension was observed both in Cancasians (.46 vs. .38, P = .004) and in Japanese (.91 vs. .76, P = .002). In both groups, the G-->A substitution located at position -6 upstream of the initial transcription site occurred at the same frequency and in complete linkage disequilibrium with the T235 allele. No other polymorphism was found to be consistently associated with hypertension. Five informative haplotypes subdividing the T235 allele were generated. Whereas two of them were associated with hypertension in Caucasians, none of these two haplotypes (H3 and H4) reached statistical significance in Japanese. The analysis of the AGT-GT repeat revealed marked linkage disequilibriums between each of the diallelic polymorphisms and some (GT)n alleles, with similar patterns in the two populations. The strong disequilibrium between M235 and (GT)16 explained the increased frequency of that particular allele in French controls compared with hypertensives (.42 vs. .36, P < .01). The haplotype combining the M235T and G-6A polymorphisms appears as the ancestral allele of the human AGT gene and as the one associated with hypertension.

A nucleotide substitution in the promoter of human angiotensinogen is associated with essential hypertension and affects basal transcription in vitro

In earlier studies, we provided statistical evidence that individual differences in the angiotensinogen gene, the precursor of the vasoactive hormone angiotensin II, constitute inherited predispositions to essential hypertension in humans. We have now identified a common variant in the proximal promoter, the presence of an adenine, instead of a guanine, 6 bp upstream from the initiation site of transcription, in significant association with the disorder. Tests of promoter activity and DNA binding studies with nuclear proteins suggest that this nucleotide substitution affects the basal transcription rate of the gene. These observations provide some biological insight about the possible mechanism of a genetic predisposition to essential hypertension; they may also have important evolutionary implications.

Temperature dependence of the mitochondrial inner membrane anion channel. The relationship between temperature and inhibition by protons

In this paper, we investigate the temperature and pH dependence of the mitochondrial inner membrane anion channel (IMAC) that is believed to be involved in mitochondrial volume homeostasis. At pH 7. 4, the flux of malonate is highly temperature-dependent with rates increasing from 1 nmol/min mg at 5 degrees C to 1900 nmol/min mg at 45 degrees C. The Arrhenius plot is nonlinear with the activation energy increasing from 21 kJ/mol (Q10 = 1.3) to 193 kJ/mol (Q10 = 13) as the temperature is decreased. This temperature dependence is unusual and not seen with solutes that are transported through the bilayer such as NH4OAc, malonamide, and KSCN (plus valinomycin) or even for cytochrome c oxidase-dependent uptake of potassium (plus valinomycin). The temperature dependence of IMAC is closely related to the inhibition of IMAC by protons. Thus, we find that the pIC50 for protons decreases from 9.3 (Hill coefficient = 1.0) at 5 degrees C to 7.1 (Hill coefficient = 2.5) at 45 degrees C. This behavior is explained on the basis of a new kinetic model for IMAC in which the net open probability is not only modulated by the binding of three protons but also by temperature via effects on the open probability of the unprotonated channel and the pK of one of the inhibitory protonation sites.

Cancer of the male breast: a review

A review of 20 cases of male breast cancer in 17 patients from 1959 to 1990 was performed. The median age at presentation was 53.3 years (range: 29 to 79). At the time of diagnosis, 30% (6) patients were stage I, 65% (13) stage II, and 5% (1) stage IV. Surgery was the initial form of therapy in all cases either as a radical mastectomy, modified radical mastectomy, or total mastectomy. The median disease-free survival was 4.8 years with a 5-year disease-free survival of 41%, and with a 5-year overall survival of 47%. Seven patients are alive with no evidence of disease, two are alive with disease, five have died of disease, and two died of other causes. Estrogen receptor (ER) and progesterone receptor (PR) assays were performed on the tumors of 10 patients, with 80% being ER positive and 70% PR positive. The median disease-free survival for ER positive patients was 6 months with a 5-year disease-free survival of 12.5%. The overall median survival for this group was 2.9 years with an overall 5-year survival of 25%. In this review there was a high percentage of patients who were ER positive. The positive receptor status had value in predicting decreased survival.

Effects of subtype-selective and balanced angiotensin II receptor antagonists in a porcine coronary artery model of vascular restenosis

BACKGROUND

Numerous studies have demonstrated the ability of angiotensin II (Ang II) receptor antagonists and angiotensin-converting enzyme (ACE) inhibitors to inhibit intimal hyperplasia after balloon dilation of noncoronary arteries in small-animal models, suggesting an important role for Ang II in the response to injury. Although ACE inhibitors have not been similarly effective in nonhuman coronary models or in human restenosis trials, questions remain regarding the efficacy ACE inhibitors against tissue ACE and the contributions of ACE-independent pathways of Ang II generation. Unlike ACE inhibitors, Ang II receptor antagonists have the potential to inhibit responses to Ang II independent of its biosynthetic origin.

METHODS AND RESULTS

In separate studies, three Ang II receptor antagonists, including AT1 selective (L-158,809), balanced AT1/AT2 (L-163,082), and AT2 selective (L-164,282) agents, were evaluated for their ability to inhibit vascular intimal thickening in a porcine coronary artery model of vascular injury. Preliminary studies in a rat carotid artery model revealed that constant infusion of L-158,809 (0.3 or 1.0 mg X kg-1 X d-1) reduced the neointimal cross-sectional area by up to 37% measured 14 days after balloon dilatation. In the porcine studies, animals were treated with vehicle or test compound beginning 2 days before and extending 28 days after experimental angioplasty. Left anterior descending, left circumflex, and/or right coronary arteries were injured by inflation of commercially available angioplasty balloons with placement of coiled metallic stents. Infusion of L-158,809 (1 mg X kg-1 X d-1), L-163,082 (1 mg X kg-1 X d-1), or L-164,282 (1.5 mg X kg-1 X d-1) in the study animals yielded plasma drug levels sufficient either to chronically block or, for L-164,282, to spare pressor responses to exogenous Ang II. Neither L-158,809, L-163,082, nor L-164,282 had statistically significant effects (P=.12, P=.75, and P=.48, respectively, compared with vehicle-treated controls) on neointimal thickness (normalized for degree of injury) measured by morphometric analysis at day 28 after angioplasty.

CONCLUSIONS

These findings indicate that chronic blockade of Ang II receptors by either site-selective or balanced AT1/AT2 antagonists is insufficient to inhibit intimal hyperplasia after experimental coronary vascular injury in the pig. The results further suggest that, unlike in the rat carotid artery, Ang II is not a major mediator of intimal thickening in the pig coronary artery.

Substrate specificity of Ty1 integrase

Integration of the Saccharomyces cerevisiae retrotransposon Ty1 requires the element-encoded integrase (IN) protein, which is a component of cytoplasmic virus-like particles (VLPs). Using purified recombinant Ty1 IN and an oligonucleotide integration assay based on Ty1 long terminal repeat sequences, we have compared IN activity on substrates having either wild-type or altered donor ends. IN showed a marked preference for blunt-end substrates terminating in an A:T pair over substrates ending in a G:C pair or a 3' dideoxyadenosine. VLP activity on representative substrates also showed preference for donor strands which have an adenosine terminus. Staggered-end substrates showed little activity when nucleotides were removed from the end of the wild-type donor strand, but removal of one nucleotide from the complementary strand did not significantly diminish activity. Removal of additional nucleotides from the complementary strand reduced activity to minimal detection levels. These results suggest that the sequence specificity of Ty1 IN is not stringent in vitro. The absence of Ty1 IN-mediated 3' dinucleotide cleavage, a characteristic of retroviral integrases, was demonstrated by using selected substrates. In addition to the forward reaction, both recombinant IN and VLP-associated IN carry out the reverse disintegration reaction with long terminal repeat-based dumbbell substrates. Disintegration activity exhibits sequence preferences similar to those observed for the forward reaction.

Preparation of oxide superconductor specimens for TEM examination

We have investigated a wide variety of oxide superconductors and report here on a number of techniques that can be effectively used to prepare transmission electron microscopy (TEM) specimens from these materials. Crushing, cleaving, ion milling, ultramicrotomy, and jet polishing all were successfully utilized, and details of each technique, as well as equipment used, are described. Selection among these methods depends both on the starting form of the material and the information required. Ion milling and crushing generally give the best results and have the widest applicability in our particular work, while crushing and cleaving involve the least equipment cost. In some cases, particularly with ion milling and jet polishing, small variations in the details of preparation have a dramatic effect on the success rate. We have found it to be a great advantage that the same techniques can be applied in a similar manner to a whole range of oxide materials, even (with some refinements and special precautions) to those that are extremely oxygen or moisture sensitive.

Balloon dilatation of the sphincter of Oddi facilitates passage of glass beads from the canine biliary tract

Laparoscopic management of common duct stones is increasing. The most widely used technique involves trans-cystic duct scope placement and stone extraction. Occasionally, stones cannot be retrieved and are allowed to pass spontaneously after manipulation of the sphincter of Oddi. This study examines a model of sphincter of Oddi dilatation in the dog to facilitate passage of glass beads simulating gallstones. In 24 dogs, glass beads of varying sizes (3-8 mm) were implanted in the gallbladder and allowed to pass spontaneously over 1 month. In three separate groups, these animals underwent (1) sham instrumentation of the sphincter of Oddi (control), (2) sphincter dilatation with balloon catheters, or (3) transduodenal sphincterotomy. At the end of 1 month, all the animals were autopsied, and the glass beads were retrieved. Histologic sections of the pancreas were examined for possible pancreatitis. The results of this study show that no animal experienced pancreatitis from sphincter manipulation or the passage of glass beads. The control animals who underwent sham manipulation of the sphincter passed 10% of their glass beads. In contrast, after sphincter dilatation, 52.5% of the 3-mm glass beads passed or 22% of all size beads. Animals with sphincterotomy passed a similar amount of glass beads as those with balloon dilatation. These studies suggest that balloon dilatation is as efficacious as sphincterotomy in facilitating the passage of glass beads from the canine biliary tract.