Role of Ki-67 proliferation index in the assessment of patients with neuroendocrine neoplasias regarding the stage of disease.

BACKGROUND: Neuroendocrine neoplasias (NEN) of the gastroenteropancreatic (GEP) system frequently present with metastatic deposits. The proliferation marker Ki-67 is used for diagnosis and to assess the prognosis of disease. The aim of our study was to evaluate the usefulness of Ki-67 % in the assessment of NEN patients with regard to their disease stage in clinical practice. Additionally, a comparative analysis of Ki-67 levels among different sites of disease was performed. METHODS: This retrospective study included patients with GEP NEN referred to our center from 2010 to 2012. The NEN diagnosis was confirmed by standard histopathology. Ki-67 immunohistochemistry was done on paraffin-embedded sections using an automated Leica immunohistochemistry machine. NEN grading was carried out according to European Neuroendocrine Tumor Society recommendations (low grade [G1] to intermediate grade [G2], well to moderately differentiated neuroendocrine neoplasms; high-grade [G3], moderately to poorly differentiated neuroendocrine neoplasms). Results of tumor staging and grading were correlated. In a subgroup of cases, comparative analysis of Ki-67 levels in different sites of disease was carried out. RESULTS: One hundred sixty-one GEP NEN patients were included in the study. Metastatic disease was seen in 46.1 % (53/115) of G1 tumors, 77.8 % (28/36) of G2 tumors, and 100 % of (10/10) G3 tumors (p = 0.0002). When stratified according to primary tumor site, metastatic disease was documented in 42.9 % (36/84) of patients with pancreatic NEN and in 91.9 % (34/37) of those with small intestinal primary. Stage IV metastatic disease was present in 27.8 % (32/115) and 72.2 % (26/36) of the G1 and G2 tumors, respectively, and in 90 % (9/10) of the G3 tumors. Assessment of the Ki-67 index for a subset of cases at metastatic sites as well as the primary tumor site showed discrepancies in 35.3 % cases. In 7/9 (77.8 %) patients with liver metastases, Ki-67 % was higher in the liver lesions than in the primary tumor. CONCLUSIONS: Patients with GEP NEN exhibiting a high Ki-67 proliferation index present with metastatic disease in the vast majority of cases. Depending upon the primary tumor site, metastases are to be expected also in tumors with low Ki-67 %, although they are considered less aggressive. Different disease sites may express heterogeneous Ki-67 levels.

Antigen-specific cells in mouse bone marrow. I. Lasting effects of priming on immunocyte production by transferred marrow.

Graded numbers of marrow cells and 5 x 10(7) thymocytes were mixed in vitro and transplanted into X-irradiated (C3H x C57BL/10)F(1) mice. Upon injection of sheep or chicken erythrocytes, splenic plaque-forming cells secreting IgM (direct PFC) or IgG (indirect PFC) hemolytic antibody were enumerated at the time of peak responses. Anti-sheep and anti-chicken primary PFC responses elicited by nonimmune marrow cells differed sharply from each other under the conditions of limiting dilution assays. The frequencies of anti-chicken responses in recipients of different numbers of marrow cells conformed to the predictions of the Poisson model, while the frequencies of anti-sheep responses did not. Hence, the function of certain marrow-derived cells was expressed differentially during the two immune responses, to exclude that the same precursor units generated anti-sheep or anti-chicken PFC. The former precursor cells or units were functionally more heterogeneous than the latter. Immunization of marrow donors against sheep erythrocytes did not alter the population of cells engaged in anti-chicken responses, since limiting dilution assays with immune and nonimmune marrow cells gave identical results. However, anti-sheep immunization altered specifically the cell population engaged in anti-sheep responses, in two ways: (a) potentially immunocompetent marrow cells underwent antigen-dependent differentiation or maturation, to become functionally homogeneous. Consequently, the frequencies of PFC responses in limiting dilution assays conformed to the Poisson model; the changes occurred independently in class-restricted precursors of direct and indirect PFC. (b) marrow cells capable of inhibiting precursors of direct anti-sheep PFC arose in primed mice. The inhibition, which was specific, could have been effected directly by marrow cells or by a diffusable product such as IgG antibody. Results indicated that potentially immunocompetent cells of mouse marrow with distinct functions were antigen specific and antigen sensitive.

Immunologic memory cells of bone marrow origin. Increased burst size of specific immunocyte precursors.

Individual immunocompetent precursor cells of (C57BL/10 x C3H)F(1) mouse marrow generate, on transplantation, three to five times more antibody-forming cells localized in recipient spleens during secondary than during primary immune responses. The increased burst size is immunologically specific since antigens of horse and chicken erythrocytes and of Salmonella typhimurium do not cause this effect in marrow cells responsive to sheep red blood cells. Both sensitized and nonsensitized precursors require the helper function of thymus-derived cells and antigen for the final steps of differentiation and maturation. The burst size of primed precursor cells is the same after cooperative interactions with virgin or educated helper cells of thymic origin. The greater potential of these marrow precursors may be attributable to self-replication and migration before differentiation into antibody-forming descendants. In fact, the progeny cells of primed precursor units are distributed among a multiplicity of foci, whereas those of nonimmune precursors are clustered into one focus. The described properties of specifically primed marrow precursors are those underlying immunologic memory. It remains to be established whether memory cells are induced or selected by antigens and whether the thymus plays a role in this process.

Antigen-specific cells in mouse bone marrow. II. Fluctuation of the number and potential of immunocyte precursors after immunization.

Quantitative and qualitative changes of mouse bone marrow cells were studied by limiting dilution assays 2-3.5 months after immunization of donors with sheep erythrocytes or unrelated antigens (Salmonella typhimurium, horse and chicken erythrocytes). Irradiated (C3H x C57BL/10)F(1) mice were reconstituted with an excess of nonprimed thymocytes and small graded numbers of primed bone marrow cells. Direct and indirect plaque-forming cells (PFC) were induced by secondary stimulation with SRBC and enumerated on the 9th day after cell transplantation. Marrow precursors of PFC (P-PFC) cooperated with thymocytes in the production of direct and indirect PFC after SRBC priming. The limiting dilution plots, which were not compatible with predictions of the Poisson model before immunization, changed and conformed to this model afterwards, as if the population of P-PFC had become functionally more homogeneous. The concentration of marrow P-PFC increased up to the 3rd month after priming, and decreased during the 4th, varying over two logarithms of nucleated marrow cells. The fluctuation was simultaneous and of the same order of magnitude for precursors of direct and indirect PFC, which were class restricted. A third effect of immunization was detected at 3.5 months: individual precursor units generated 3-4 times more direct and indirect PFC than at earlier intervals. Qualitative and quantitative changes of marrow P-PFC participating in anti-sheep responses were specific, since antigens unrelated to SRBC failed to induce them. The data suggested that marrow-derived cells were the major carriers of immunologic memory, but that they functioned in cooperation with thymus-derived inducer cells during secondary anti-sheep responses.

Density gradient separation of marrow precursor cells restricted for antibody specificity.

Potentially immunocompetent cells of (C57BL/6 x DBA/2) F(1) mouse bone marrow are committed to antigenic determinants of sheep or burro erythrocytes prior to interaction with thymus-derived cells and participation in immune responses to administered antigens. At this stage of differentiation marrow cells of this particular mouse strain are not yet restricted for the immunoglobulin M or immunoglobulin G antibody class. By equilibrium centrifugation in discontinuous gradients of bovine serum albumin, precursors of cells that produce antibody to sheep erythrocytes migrate to denser regions, whereas the precursors of immunocytes that produce antibody to burro erythrocytes remain in the lower density regions. cursors for all specificities.

Density gradient separation of marrow cells restricted for antibody class.

Primitive cells of (C3H x C57BL/10)F(1) mouse bone marrow, participating with thymocytes in immune responses to sheep erythrocytes, are already committed to the immunoglobulin M or immunoglobulin G antibody class. By equilibrium centrifugation in discontinuous gradients of bovine serum albumin, cells responsible for production of IgM immunocytes migrate to the denser regions, whereas those responsible for IgG immunocytes remain in the lower density regions.

Fine-scale genetic structure of a long-lived reptile reflects recent habitat modification.

Anthropogenic habitat fragmentation--ubiquitous in modern ecosystems--has strong impacts on gene flow and genetic population structure. Reptiles may be particularly susceptible to the effects of fragmentation because of their extreme sensitivity to environmental conditions and limited dispersal. We investigate fine-scale spatial genetic structure, individual relatedness, and sex-biased dispersal in a large population of a long-lived reptile (tuatara, Sphenodon punctatus) on a recently fragmented island. We genotyped individuals from remnant forest, regenerating forest, and grassland pasture sites at seven microsatellite loci and found significant genetic structuring (R(ST)=0.012) across small distances (<500 m). Isolation by distance was not evident, but rather, genetic distance was weakly correlated with habitat similarity. Only individuals in forest fragments were correctly assignable to their site of origin, and individual pairwise relatedness in one fragment was significantly higher than expected. We did not detect sex-biased dispersal, but natural dispersal patterns may be confounded by fragmentation. Assignment tests showed that reforestation appears to have provided refuges for tuatara from disturbed areas. Our results suggest that fine-scale genetic structuring is driven by recent habitat modification and compounded by the sedentary lifestyle of these long-lived reptiles. Extreme longevity, large population size, simple social structure and random dispersal are not strong enough to counteract the genetic structure caused by a sedentary lifestyle. We suspect that fine-scale spatial genetic structuring could occur in any sedentary species with limited dispersal, making them more susceptible to the effects of fragmentation.

Mixed evidence for the potential of non-invasive transcutaneous vagal nerve stimulation to improve the extinction and retention of fear.

Extinction memories are fragile and their formation has been proposed to partially rely on vagus nerve activity. We tested whether stimulating the auricular branch of the vagus (transcutaneous VNS; tVNS) accelerates extinction and reduces spontaneous recovery of fear. Forty-two healthy students participated in a 3-day fear conditioning study, where we tested fear acquisition (day 1), fear extinction (day 2) and the retention of the extinction memory (day 3). During extinction, participants were randomly allocated to receive tVNS or sham stimulation concurrently with each CS presentation. During the acquisition and retention phases, all participants received sham stimulation. Indexes of fear included US-expectancy, startle blink EMG and skin conductance responses. Results showed successful acquisition and extinction of fear in all measures. tVNS facilitated the extinction of declarative fear (US expectancy ratings), but did not promote a stronger retention of the declarative extinction memory. No clear effects of tVNS on extinction and retention of extinction were found for the psychophysiological indexes. The present findings provide tentative indications that tVNS could be a promising tool to improve fear extinction and call for larger scale studies to replicate these effects.

Amnion-derived cells express intercellular adhesion molecule-1: regulation by cytokines.

We have examined the expression of the intercellular adhesion molecule-1 (ICAM-1) mRNA in primary and established amnion-derived cell cultures and regulation of this expression by tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta. TNF-alpha (50 ng/ml) and IL-1beta (1.0 ng/ml) induced 18- and 11-fold increases respectively in expression of the ICAM-1 mRNA in WISH cells (an amnion epithelium-derived cell line). The increase was detectable within one hour of treatment and peaked by two hours. The protein synthesis inhibitor, cycloheximide (10 microg/ml) did not inhibit this induction. Increased levels of ICAM-1 protein were detected in the cells within 4 h after initiation of treatment with either cytokine. By 16 h of treatment with IL-1beta or TNF-alpha ICAM-1 reached 40 and 73 pg/microg cellular protein, representing 6- and 11-fold stimulations respectively. In primary amnion cells, basal expression of ICAM-1 mRNA was undetectable. However, TNF-alpha (50 ng/ml) induced ICAM-1 mRNA within two hours, peak expression being reached between four and eight hours after initiation of treatment. The present report demonstrates for the first time that amnion derived cells can express ICAM-1 and, further, that this expression is regulated by pro-inflammatory cytokines. This has implications for the amnion as a possible source for soluble ICAM-1, for this gene product as a marker for preterm labour, and for participation of the amnion, additional to its reported secretory role, in inflammatory processes of the fetal membranes.

Effects of interleukin-4 on the expression and activity of prostaglandin endoperoxide H synthase-2 in amnion-derived WISH cells.

Increased prostaglandin biosynthesis during intrauterine infection may be a possible mechanism by which preterm labour is initiated. Inflammatory cytokines and growth factors are known to stimulate prostaglandin production through an increase in prostaglandin endoperoxide H synthase (PGHS)-2 synthesis and activity. Interleukin-4 (IL-4), an anti-inflammatory cytokine, can downregulate PGHS-2 expression and inhibit prostaglandin production. Therefore, the aims of the current study were to determine the effects of IL-4 on PGHS-1 and PGHS-2 expression in amion-derived WISH cells treated with inflammatory cytokines and growth factors. In WISH cells, near-maximal production of the PGHS-2 mRNA occurred using 5 ng/ml EGF, 1 ng/ml IL-1beta or 50 ng/ml TNF-alpha. Time-course experiments determined that the PGHS-2 mRNA was induced maximally by these stimuli by 1 h. Pretreatment of WISH cells with IL-4 reduced PGHS-2 mRNA levels at 1 h by 67% in cells treated with EGF, 62% in cells treated with IL-1beta and 54% in cells treated with TNF-alpha. Pretreatment with IL-4 more effectively inhibited PGHS-2 expression than simultaneous addition with EGF or IL-1beta but not TNF-alpha. Immunoblot analysis showed a correlation between inhibition of mRNA levels and levels of PGHS-2 protein, although stimulation of PGHS-2 protein production by EGF was undetectable. Levels of PGHS-1 protein and mRNA remained unchanged in all experiments. Increased production of prostaglandin E2 (PGE2) in response to TNF-alpha and IL-1beta treatment was attenuated by IL-4 pretreatment, by 52% and 72%, respectively. No attenuation of EGF-stimulated PGE2 levels was seen. We conclude that IL-4 inhibits PGHS-2 mRNA and protein production in cytokine-stimulated WISH cells, but does not affect EGF-stimulated PGE2 production, suggesting that EGF can induce prostaglandin biosynthesis by a mechanism other than through increased PGHS-2 expression.

Rapid lymphocyte immunoreactivity test utilizing [3H]uridine in vitro.

A microculture assay utilizing [3H]uridine incorporation was developed to test murine spleen lymphocyte immunoreactivity in vitro. Parameters of the culture technique which included cell density, doses of LPS, Con A, PHA, [3H]uridine levels, and length of culture time were investigated. Responses were detectable at 4 h for all 3 mitogens, with labeling ranging up to 180% of the control value. By 8 h there was a 200--350% increase in mitogen-induced incorporation of radioactivity. Similar increases were observed in a serum-free system. The responses were the result of increased incorporation of label by stimulated cultures rather than decreased labeling of non-mitogen treated cultures over time. The [3H]uridine incorporation was demonstrated to be the selective response of T or B cell populations when stimulated with appropriate lectins. This assay detects early RNA synthesis, as supported by experimental observations in which accumulation of radioactivity in stimulated lymphocytes was TCA precipitable, resistant to SDS treatment, and inhibited by actinomycin D.

Factors associated with infections among breast-fed babies and babies fed proprietary milks.

Correlation of first postnatal year infections among 251 babies was made with the infant feeding mode, socioeconomic status of family, maternal educational level, age, and maternal behavioral factors including smoking habit and number of siblings in the family. Initially, 127 mothers intended to breast-feed and 124 intended to formula-feed their infants. In the correlation matrix maternal education was the highest variable inversely correlated with infection; it was the first to enter in stepwise regression analysis and was highly significant (P less than .0001). Maternal weight gain during pregnancy and infant feeding mode were the next two variables, respectively, to be added during the stepwise regression but they were not significant in the presence of maternal education. The statistical significance of increased maternal education in inverse relation to infection persisted in the presence of the other two factors (P less than .0064). The t test showed no significant difference in the number of infections among the breast-fed and formula-fed babies within any of the three maternal education groups. It may be concluded that in the population studied, the infant feeding mode itself was not significantly related to the number of infections during the infant's first postnatal year when the education of the mother was taken into account.

Occult thyrotoxicosis: a correctable cause of "idiopathic" atrial fibrillation.

Serum total thyroxine, triiodothyronine and thyrotropin response to thyrotropin-releasing hormone were measured in 75 consecutive patients presenting to a cardiology clinic with atrial fibrillation with no obvious cardiovascular cause. A lack of response of serum thyrotropin to thyrotropin-releasing hormone, indicative of thyrotoxicosis, was found in 10 patients (13 percent), not all whom had raised serum thyroid hormone levels. These 10 patients were predominantly male, had no clinical signs of thyrotoxicosis and a relative excess of nonpalpable autonomous thyroid nodules demonstrated with scintigraphy. Eight of the 10 patients had reversion to stable sinus rhythm after treatment with iodine-131 or carbimazole, either spontaneously or after direct current cardioversion. It would appear that clinically occult thyrotoxicosis can be identified consistently only with the thyrotropin-releasing hormone test and is the cause of "idiopathic" atrial fibrillation in a significant proportion of patients.

Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) in amnion with term and preterm labour.

To evaluate the association between intercellular adhesion molecule-1 (ICAM-1) in the amnion and preterm labour and delivery, we have assessed ICAM-1 mRNA abundance by Northern analysis and protein levels by enzyme-linked immunosorbent assay (ELISA), in samples of this tissue after term and preterm delivery. The median ICAM-1 mRNA expression following preterm delivery (PTD, n=30) was 24 times greater (P< 0.05) than following elective caesarean section prior to labour at term (CST, n=14). ICAM-1 expression following vaginal delivery after spontaneous labour at term (SLT, n=11) was seven times greater than in the CST group (P< 0.05). The concentration of ICAM-1 protein in the PTD samples (n=31) was four-fold greater than (P< 0.05) in CST (n=14). It was also three-fold greater than in the SLT (n=15) samples (P< 0.05). The results were substantially the same when a preterm spontaneous labour group (PTL) (n=26), exclusive of deliveries complicated by pre-eclampsia (n=1) or intrauterine growth restriction (n=3), was compared to the CST and SLT groups. The ICAM-1 mRNA expression did not differ significantly (P=0.93) between PTL with (n=12) or without (n=14) indicators of intrauterine infection. The results were similar when ICAM-1 protein concentrations were compared (P=0.43) between these two groups. These findings indicate that ICAM-1 is expressed by the human amnion and that this expression is elevated with preterm labour and delivery.

Effectiveness of five days of therapy with cefuroxime axetil suspension for treatment of acute otitis media.

BACKGROUND: In recent years there has been considerable interest in reducing the duration of antibiotic treatment regimens in patients with common bacterial infections. We conducted two independent, investigator-blinded, multicenter, randomized clinical trials, one of which included microbiologic evaluation of middle ear fluid obtained by tympanocentesis, comparing the efficacy and safety of 5 or 10 days of treatment with cefuroxime axetil suspension (CAE) with that of 10 days of treatment with amoxicillin/clavulanate suspension (AMX/CL) in children with acute otitis media. METHODS: A total of 719 pediatric patients from the ages of 3 months to 12 years were enrolled in the 2 studies. Patients received CAE for either 5 or 10 days at 30 mg/kg/day in 2 divided doses (n = 242 and 235, respectively) or AMX/CL for 10 days at 40 mg/kg/day in 3 divided doses (n = 242). Patients in the CAE (5 days) group received placebo on Days 6 through 10. In the study that included tympanocentesis, bacteriologic assessments were based on middle ear fluid cultures obtained pretreatment and, when possible, after treatment in patients with an unsatisfactory clinical outcome. RESULTS: Organisms were isolated from the pretreatment middle ear fluid specimens of 177 of 244 (73%) patients undergoing tympanocentesis, with the primary pathogens being Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis (37, 35 and 12% of isolates, respectively). Pathogens were eradicated or presumed to be eradicated in 92% (24 of 26), 84% (32 of 38) and 95% (36 of 38) of bacteriologically evaluable patients treated with CAE for 5 or 10 days or with AMX/CL, respectively. A satisfactory clinical outcome (cure or improvement) occurred in 69% (101 of 147), 70% (121 of 173) and 74% (131 of 177) of clinically evaluable patients treated with CAE (5 days), CAE (10 days) or AMX/CL, respectively. Treatment with AMX/CL was associated with a significantly higher incidence of drug-related adverse events than was treatment with CAE for either 5 or 10 days (P < 0.001), primarily reflecting a higher incidence of drug-related gastrointestinal adverse events (34% vs. 17 and 12%, respectively; P < 0.001), particularly diarrhea. CONCLUSIONS: Treatment with CAE given twice daily for 5 days is equivalent to treatment for 10 days either with the same regimen of CAE or with AMX/CL given three times daily in pediatric patients with acute otitis media.

Stress prostatitis.

A group of 218 men complaining of symptoms of chronic prostatitis were identified. Symptoms included pelvic and genital pain with or without voiding or ejaculation, urinary frequency and/or urgency, and often a thin watery urethral discharge. Of the group 134 (60%) were followed carefully. With nothing but stress management therapy 110 patients (86%) reported that they were "better," "much better," or "cured." Physiologically, the therapy makes sound medical sense. It is suggested that the term "stress prostatitis" is an appropriate label for this condition.

Peyronie disease treated with ultrasound and hydrocortisone.

Thirty patients with Peyronie disease were treated with ultrasound using hydrocortisone ointment as the conducting vehicle. Twenty-five patients completed at least one course of treatment. Of those 25, 19 had at least some benefit with evidence that multiple courses of treatment were more beneficial than a single course. We conclude that ultrasound with hydrocortisone is beneficial in relieving pain, relieving deviation, and reducing the size of the fibrous plaque. It has the advantages of being noninvasive, repeatable, and without any side effects.

Postprostatectomy incontinence: George Washington University technique.

The original concept of external compression on the urethra to provide urinary continence in the male has undergone significant modifications since the original work of Berry fifteen years ago. The technique used at George Washington University is a successful extension of Berry's concept. This article presents a very precise description of the operation. There has been only one failure in 13 patients referred to us, therefore the technique is recommended as an excellent means of correcting postprostatectomy incontinence.

Clinical comparison of cefuroxime axetil suspension and amoxicillin/clavulanate suspension in the treatment of pediatric patients with acute otitis media with effusion.

Two independent, investigator-blinded, multicenter, randomized clinical trials, one of which included microbiologic evaluation of middle-ear fluid obtained by use of tympanocentesis, compared the efficacy and safety of two oral antibiotics, cefuroxime axetil suspension and amoxicillin/clavulanate suspension, in the treatment of children 3 months to 12 years old diagnosed with acute otitis media with effusion (AOME). Four hundred seventy-seven pediatric patients with signs and symptoms of AOME were enrolled at 20 centers and were randomly assigned to receive 10 days of treatment with either cefuroxime axetil suspension 30 mg/kg per day in two divided doses (n = 235) or amoxicillin/clavulanate suspension 40 mg/kg per day in three divided doses (n = 242). Patients were assessed for their response to treatment once during treatment (at 3 to 5 days) and twice after treatment (at 1 to 4 days and at 14 to 18 days). In the study that included tympanocentesis, bacteriologic assessments were based on middle-ear fluid cultures obtained pretreatment, and, when possible, posttreatment in patients with an unsatisfactory clinical outcome. Organisms were isolated from the pretreatment middle-ear fluid specimens of 120 (73%) of 164 patients undergoing tympanocentesis, with the primary pathogens being Streptococcus pneumoniae. Haemophilus influenzae, and Moraxella catarrhalis (27%, 24%, and 6% of isolates, respectively). Forty-four percent of the H influenzae isolates and 94% of the M catarrhalis isolates that were tested for beta-lactamase production were positive. A satisfactory clinical outcome (cure or improvement) was obtained in 70% of clinically assessable patients treated with cefuroxime axetil or amoxicillin/clavulanate, respectively (P = 0.40). With respect to the eradication of bacterial pathogens, in the study that included tympanocentesis a satisfactory outcome (cure or presumed cure) was obtained in 84% (32 of 38) and 95% (36 of 38) of bacteriologically assessable patients treated with cefuroxime axetil or amoxicillin/clavulanate, respectively (P = 0.26). Treatment with amoxicillin/clavulanate was associated with a significantly higher incidence of drug-related adverse events than was treatment with cefuroxime axetil (37% vs 16%; P < 0.001), primarily reflecting a higher incidence of drug-related gastrointestinal adverse events (34% vs 12%; P < 0.001), particularly diarrhea. Eight patients in the cefuroxime axetil group and 11 patients in the amoxicillin/clavulanate group withdrew from the studies because of drug-related adverse events. These results indicate that cefuroxime axetil suspension 15 mg/kg twice daily is as effective as amoxicillin/clavulanate suspension 13.3 mg/kg three times daily in the treatment of pediatric patients with AOME, but produces fewer gastrointestinal adverse events, particularly diarrhea.