In vitro effects of bethanechol on specimens of intestinal smooth muscle obtained from the duodenum and jejunum of healthy dairy cows

OBJECTIVE: To describe the in vitro effects of bethanechol on contractility of smooth muscle preparations from the small intestines of healthy cows and define the muscarinic receptor subtypes involved in mediating contraction. SAMPLE POPULATION: Tissue samples from the duodenum and jejunum collected immediately after slaughter of 40 healthy cows. PROCEDURES: Cumulative concentration-response curves were determined for the muscarinic receptor agonist bethanechol with or without prior incubation with subtype-specific receptor antagonists in an organ bath. Effects of bethanechol and antagonists and the influence of intestinal location on basal tone, maximal amplitude (A(max)), and area under the curve (AUC) were evaluated. RESULTS: Bethanechol induced a significant, concentration-dependent increase in all preparations and variables. The effect of bethanechol was more pronounced in jejunal than in duodenal samples and in circular than in longitudinal preparations. Significant inhibition of the effects of bethanechol was observed after prior incubation with muscarinic receptor subtype M(3) antagonists (more commonly for basal tone than for A(max) and AUC). The M(2) receptor antagonists partly inhibited the response to bethanechol, especially for basal tone. The M(3) receptor antagonists were generally more potent than the M(2) receptor antagonists. In a protection experiment, an M(3) receptor antagonist was less potent than when used in combination with an M(2) receptor antagonist. Receptor antagonists for M(1) and M(4) did not affect contractility variables. CONCLUSIONS AND CLINICAL RELEVANCE: Bethanechol acting on muscarinic receptor sub-types M(2) and M(3) may be of clinical use as a prokinetic drug for motility disorders of the duodenum and jejunum in dairy cows.     

Isolation and structural elucidation of (13Z,13'Z,3R,3'R,6'R)-lutein from marigold flowers, kale, and human plasma

(13Z,13'Z,3R,3'R,6'R)-Lutein has been isolated and purified from extracts of marigold flowers, fresh raw kale (Brassica oleracea var. Acephala), and human plasma and fully characterized by (1)H and (13)C NMR, UV/vis, and MS. While the concentration of (13Z, 13'Z)-lutein in kale and human plasma compared to (all-E,3R,3'R, 6'R)-lutein was found to be quite low, this compound was readily isolated by fractional crystallization of lutein from marigold extracts. Thus, the mother liquors from two consecutive crystallizations of lutein from a saponified extract of marigold flowers were enriched in (13Z,13'Z)-lutein (8.7% of total carotenoids) and employed for the isolation of this compound by HPLC. The identity of the di-Z-lutein in kale and human plasma has been established by comparison of the HPLC-UV/vis-MS profiles of the purified compounds with those of a fully characterized sample, isolated from marigolds. 3-Hydroxy-beta,epsilon-caroten-3'-one and 3'-epilutein have also been identified in extracts from marigolds.     

Spontaneous in vitro contractile activity of specimens from the abomasal wall of healthy cows and comparison among dairy breeds

OBJECTIVE: To characterize and compare in vitro contractility patterns of sections of abomasal wall harvested from cattle of 3 dairy breeds. SAMPLE POPULATION: Longitudinal and circular smooth muscle preparations harvested from the antrum and body of the abomasum of 30 recently slaughtered Holstein-Friesian, Brown Swiss, and Simmental X Red Holstein cows. PROCEDURE: Spontaneous isometric contractions of specimens in tissue baths of modified Krebs solution were recorded during a 4-hour period. Maximal amplitude, frequency of contractions, and change of basal tension were used to characterize contractility. Statistical analyses were used to test for differences among time periods, among breeds, between specimen locations, and between fiber orientations. RESULTS: Myoactivity patterns of abomasal smooth muscle preparations are highly variable and differ on the basis of location and fiber orientation. Frequency of contractions differed significantly among time periods for longitudinally oriented specimens with decreasing frequencies of contractions over time. Maximal amplitude of the longitudinally oriented specimens from the antrum increased significantly, whereas maximal amplitude of the circularly oriented specimens from the antrum decreased significantly. Values did not differ significantly among breeds. CONCLUSIONS AND CLINICAL RELEVANCE: Patterns of spontaneous contractility of abomasal wall specimens are not homogeneous. During a 4-hour recording period, maximal amplitude and frequency of contractions of specimens varied significantly with respect to orientation and location; however, spontaneous contractile myoactivity did not differ significantly among breeds. Therefore, breed predisposition for displaced abomasum is not correlated with spontaneous activity of smooth muscle specimens.     

Myoelectric activity of the spiral colon in dairy cows

OBJECTIVE: To describe myoelectric activity of the spiral colon in healthy cows. ANIMALS: 7 lactating Simmental X Red-Holstein crossbred cows. PROCEDURE: Cows were implanted with 7 pairs of bipolar silver electrodes (4 in the spiral colon and 1 each in the cecum, distal part of the ileum, and proximal loop of the ascending colon [PLAC]). Myo-electric activity was recorded during 4 days for each cow. Patterns were analyzed, using computer-based methods. RESULTS: Myoelectric activity of the spiral colon was closely associated with motility of the ileum and PLAC and showed the typical organization of migrating myoelectric complexes (MMC). The MMC in the bovine spiral colon (bcMMC) had a mean +/- SD duration of 188.6 +/- 30.8 minutes and was divided into 4 phases. Phases I and II lasted 11.3 +/- 1.4 and 159.4 +/- 33.3 minutes, respectively. Phase III (duration, 5.4 +/- 1.2 minutes) was characterized by 5.2 +/- 0.9 regular spindles (35.4 +/- 5.4 seconds) and 1 final elongated spindle (137.2 +/- 56.4 seconds). Phase III most commonly (73.8 +/- 16.1%) was followed by phase IV (duration, 173 +/- 3.6 minutes). Propagation velocity of phase III was 4.4 +/- 0.5 cm/min, and 13.6% of bcMMC were incompletely propagated through the spiral colon. CONCLUSIONS: Myoelectric activity of the bovine spiral colon is composed of a recurring cyclic pattern similar to MMC of the small intestine. Data of colonic myoelectric activity in healthy cows will serve as a basis for studies on cecal dilatation and dislocation in cattle.     

Multicentric canine lymphoma in a 12-year-old keeshond: chemotherapy options

A 12-year-old, spayed female keeshond presenting with lethargy, anorexia, weight loss, and vomiting was diagnosed with multicentric lymphoma. Lymphoma usually responds well to multiagent chemotherapy. Efficacy, cost, toxicity, and duration of treatment determine a treatment protocol. Outcomes are compared on the basis of remission, survival time, and treatment-related toxicity.     

Comparison of fecal culture and F57 real-time polymerase chain reaction for the detection of Mycobacterium avium subspecies paratuberculosis in Swiss cattle herds with a history of paratuberculosis

Background

Bovine paratuberculosis is an incurable chronic granulomatous enteritis caused by Mycobacterium avium subspecies paratuberculosis (MAP). The prevalence of MAP in the Swiss cattle population is hard to estimate, since only a few cases of clinical paratuberculosis are reported to the Swiss Federal Food Safety and Veterinary Office each year.Fecal samples from 1,339 cattle (855 animals from 12 dairy herds, 484 animals from 11 suckling cow herds, all herds with a history of sporadic paratuberculosis) were investigated by culture and real-time polymerase chain reaction (PCR) for shedding of MAP.

Results

By culture, MAP was detected in 62 of 445 fecal pools (13.9%), whereas PCR detected MAP in 9 of 445 pools (2.0%). All 186 samples of the 62 culture-positive pools were reanalyzed individually. By culture, MAP was grown from 59 individual samples (31.7%), whereas PCR detected MAP in 12 individual samples (6.5%), all of which came from animals showing symptoms of paratuberculosis during the study. Overall, MAP was detected in 10 out of 12 dairy herds (83.3%) and in 8 out of 11 suckling cow herds (72.7%).

Conclusions

There is a serious clinically inapparent MAP reservoir in the Swiss cattle population. PCR cannot replace culture to identify individual MAP shedders but is suitable to identify MAP-infected herds, given that the amount of MAP shed in feces is increasing in diseased animals or in animals in the phase of transition to clinical disease.     

Antigen bias in T cell cross-priming

Activated CD8+ T cells detect virally infected cells and tumor cells by recognition of major histocompatibility complex class I-bound peptides derived from degraded, endogenously produced proteins. In contrast, CD8+ T cell activation often occurs through interaction with specialized antigen-presenting cells displaying peptides acquired from an exogenous cellular source, a process termed cross-priming. Here, we observed a marked inefficiency in exogenous presentation of epitopes derived from signal sequences in mouse models. These data indicate that certain virus- and tumor-associated antigens may not be detected by CD8+ T cells because of impaired cross-priming. Such differences in the ability to cross-present antigens should form important considerations in vaccine design.     

Induction of T helper type 2 immunity by a point mutation in the LAT adaptor

The transmembrane protein LAT (linker for activation of T cells) couples the T cell receptor (TCR) to downstream signaling effectors. Mice homozygous for a mutation of a single LAT tyrosine residue showed impeded T cell development. However, later they accumulated polyclonal helper T (TH) cells that chronically produced type 2 cytokines in large amounts. This exaggerated TH2 differentiation caused tissue eosinophilia and massive maturation of plasma cells secreting to immunoglobulins of the E and G1 isotypes. This paradoxical phenotype establishes an unanticipated inhibitory function for LAT that is critical for the differentiation and homeostasis of TH cells.