Effect of intraluminal distention on microvascular perfusion in the equine small colon

Ex vivo comparison of one-layer versus two-layer closures in end-to-end anastomoses in normal equine descending colon

OBJECTIVE

The aim of the study was to evaluate time to closure, bursting pressures and luminal diameters of a single and double-layer end-to-end anastomoses in normal equine descending colon.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Eight adult horses.

METHODS

Four segments of descending colon from each horse were randomly assigned to a control (n = 8, CON), one-layer (n = 12, group 1; continuous Lembert pattern), or two-layer group (n = 12, group 2; simple continuous oversewn with Cushing pattern). Anastomoses were performed, and time to closure and luminal diameter were measured. Bursting pressures were determined, and location of failure was recorded. Mixed analysis of variance (ANOVA) was employed.

RESULTS

Mean time to completion was decreased (p = .003) in group 1 (18.6 min ± 22.8 s) compared with group 2 (21.35 min ± 22.8 s). Luminal diameter was reduced (p < .0001) in group 2 (47 ± 2.46 mm) compared to group 1 (65 ± 2.77 mm). Location of failure was remote to the anastomosis in all but one segment; therefore, differences in anastomotic bursting pressures could not be determined.

CONCLUSION

Two-layer closures resulted in significant luminal reduction and took longer to complete than one-layer anastomoses.

CLINICAL SIGNIFICANCE

Use of one-layer closures may be advantageous primarily with respect to luminal diameter.

Metaloproteinases no tecido laminar do casco de equinos submetidos à obstrução intraluminal do cólon menor

RESUMO O objetivo deste estudo foi avaliar a expressão das MMP-2 e MMP-9 no tecido laminar do casco e o perfil leucocitário de equinos submetidos à obstrução intraluminal do cólon menor. Realizaram-se laparotomia e obstrução do cólon menor de oito equinos hígidos, utilizando-se uma bola inserida no lúmem intestinal. A bola foi inflada à pressão de 80mmHg e a obstrução foi mantida por quatro horas. Foram realizadas coletas sanguíneas antes da obstrução (M0), imediatamente após a desobstrução (M4) e a cada 12 horas após M4, até completar 72 horas (M12, M24, M36, M48, M60 e M72). As biópsias de casco foram realizadas em M0, M4 e M72, e as amostras foram submetidas à análise zimográfica. Foi observado aumento nos leucócitos em M12 e M24, decorrente do aumento de neutrófilos segmentados e bastonetes, os quais diminuíram a partir de M36. Segundo a técnica zimográfica, não se observaram alterações nos valores de MMP-2 e -9, possivelmente devido à baixa intensidade das lesões ocasionadas no cólon menor. Com isso, conclui-se que as alterações inflamatórias decorrentes da obstrução do cólon menor não foram suficientes para ocasionar alterações na expressão das MMP-2 e -9 no tecido laminar podal.

Expression of cyclooxygenase genes in the jejunum of horses during low-flow ischemia and reperfusion

OBJECTIVE

To determine expression of cyclooxygenase (COX) genes 1 and 2 (also called prostaglandin-endoperoxide synthases 1 and 2) and stability of housekeeping gene expression during low-flow ischemia and reperfusion in the jejunum of horses.

ANIMALS

5 healthy adult horses.

PROCEDURES

Horses were anesthetized, and two 30-cm segments of jejunum were surgically exteriorized. Blood flow was maintained at baseline (untreated) values in 1 (control) segment and was decreased to 20% of baseline (low-flow ischemia) for 75 minutes, followed by 75 minutes of reperfusion, in the other (experimental) segment. Biopsy samples were collected from experimental segments at baseline (T0), after 75 minutes of ischemia (T1), and after 75 minutes of reperfusion (T2); samples were collected from control segments at T0 and T2. Horses were euthanized 24 hours after induction of ischemia (T3), and additional samples were collected. Samples were evaluated histologically. Total RNA was extracted; expression of COX genes and stability of 8 housekeeping genes were determined via quantitative real-time PCR assays.

RESULTS

COX-1 and COX-2 genes were constitutively expressed in baseline samples. Low-flow ischemia resulted in significant upregulation of COX-2 gene expression at each subsequent time point, compared with baseline values. The most stably expressed reference genes were β-actin and hypoxanthine phosphoribosyltransferase, whereas glyceraldehyde 3-phosphate dehydrogenase and β-2 microglobulin were the least stably expressed.

CONCLUSIONS AND CLINICAL RELEVANCE

Low-flow ischemia resulted in upregulation of COX-2 gene expression in the jejunum of horses. Housekeeping genes traditionally used as internal standards may not be stable in this tissue during arterial low-flow ischemia and reperfusion.

Clinical evaluation of serum alcohol dehydrogenase activity in horses with acute intestinal obstruction

OBJECTIVES

To measure serum alcohol dehydrogenase (ADH) activity in horses with acute intestinal obstruction and to determine the diagnostic and prognostic utility of this analyte.

DESIGN

Prospective observational study.

SETTING

University Veterinary Hospital.

ANIMALS

Thirty healthy horses (control group) and 77 horses with acute intestinal obstruction, including 36 horses with nonstrangulating obstruction (23 with left ventral colon impaction and 13 with left dorsal displacement [G1], 22 with small intestinal strangulation [G2], and 19 with colon torsion [G3]).

INTERVENTIONS

Serum ADH activity was assayed spectrophotometerically in all horses. Serum lactate concentration and hepatic enzyme (aspartate aminotransferase, gamma-glutamyl transferase, glutamate dehydrogenase) activities were measured using an automatic analyzer.

MEASUREMENTS AND MAIN RESULTS

The median [interquartile range] serum ADH activity in healthy horses was 10.5 [8.7-11 U/L]. ADH activity was significantly increased (P<0.05) in G1=16.5 [13.8-18 U/L], G2=40 [20-74.9 U/L], and G3=63.2 [40-78 U/L] compared with healthy controls. Aspartate aminotransferase and glutamate dehydrogenase activities were also significantly increased in G3 in comparison with controls. ADH activity was correlated with serum lactate concentration in G1 and G3, respectively (P<0.01, r=0.55 and 0.8). Other liver enzymes did not show any significant correlation with lactate. ADH activity was directly related to the probability of strangulation; odds ratio=1.11. ADH activity >20 U/L had 80.6% specificity and 80.5% sensitivity for discriminating horses with strangulating obstruction. Twelve horses euthanized before surgery were excluded from the outcome analysis. Increasing ADH activity was associated with nonsurvival; odds ratio=1.03. ADH activity <80 U/L had 94.44% specificity and 66.67% sensitivity for survival.

CONCLUSION

Serum ADH activity may be a useful clinical parameter in detecting intestinal strangulation in horses and may provide some prognostic value in horses with acute intestinal obstruction.

Morphological abnormalities and apoptosis in lamellar tissue of equines after intestinal obstruction and treatment with hydrocortisone

Four experimental groups of equines were used in order to study morphological abnormalities and apoptosis in lamellar tissue. Group Cg (control) was composed of animals without any surgical procedure; group Ig (instrumented), animals that underwent enterotomy; group Tg (treated), animals that were subjected to intestinal obstruction and were treated with hydrocortisone; and group Ug (untreated), animals that were subjected to intestinal obstruction without treatment. The lamellar tissue was analyzed regarding the presence of tissue abnormalities and apoptosis. No morphological abnormalities were observed in animals of surgical groups, and no difference in apoptosis was observed between groups. It was concluded that intestinal obstruction allowed laminitis to develop, probably by systemic activation, and that the maneuvers performed in the enterotomy aggravated the process. Hydrocortisone did not aggravate the lesions of the lamellar tissue

Alterações ultraestruturais nas vilosidades do jejuno de equinos após distensão

O objetivo do presente estudo foi analisar as alterações ultraestruturais nas vilosidades do jejuno de seis equinos submetidos à distensão intraluminal com solução salina. A pressão intraluminal foi mantida em 25cm de água durante duas horas. As amostras de mucosa intestinal colhidas às: zero hora; duas horas de distensão; e duas horas e 12h de descompressão foram analisadas por meio de microscopia eletrônica de varredura. Avaliaram-se a área e o perímetro das vilosidades e sua densidade, usando-se um programa computacional de análise de imagens (Image J). A distensão luminal promoveu aumentos da área e do perímetro das vilosidades intestinais. Essa alteração ultraestrutural ocorreu somente 12h após a descompressão e considerou-se que a provável causa seria o edema promovido por aumento da permeabilidade vascular decorrente de um processo de isquemia e reperfusão da mucosa intestinal. Concluiu-se que a distensão intraluminal do jejuno equino promoveu, tardiamente, aumento das dimensões das vilosidades intestinais.

Perfil eletroforético do proteinograma sérico de eqüinos com obstrução experimental do cólon menor

Avaliaram-se as alterações do proteinograma sérico de eqüinos submetidos à isquemia e reperfusão do cólon menor por distensão intraluminal. Foram utilizados 10 animais submetidos à laparotomia pelo flanco, em posição quadrupedal, para a indução de obstrução no cólon menor durante um período de quatro horas. Cinco animais foram instrumentados, mas sem distensão (grupo controle - G1). Em cinco outros animais, foi realizada isquemia mural por distensão do cólon menor via manguito inflado com 40mmHg (grupo distendido - G2). Foram colhidas amostras de sangue antes da intervenção cirúrgica (M1), com 4 horas da colocação do manguito (M2) e com 3 horas (M3) e 12 horas (M4) de reperfusão. Após centrifugação e fracionamento das amostras, as proteínas de fase aguda foram separadas por eletroforese em gel de poliacrilamida contendo SDS-PAGE, e suas concentrações determinadas por densitometria computadorizada. Foram encontradas 19 proteínas no fracionamento eletroforético, com peso molecular variando de 185.000 a 14.000 Daltons (Da). Os pesos moleculares encontrados, correspondentes às proteínas mais conhecidas, foram ceruloplasmina, 130.000 Da; proteína C-reativa, 122.000 Da; transferrina, 85.000 Da; α1-antitripsina, 61.000 Da; haptoglobina, 47.000 Da; e glicoproteína ácida, 40.000 Da. Os resultados mostram que proteínas de fase aguda se alteram após o trauma cirúrgico.

Comparison of abomasal luminal gas pressure and volume and perfusion of the abomasum in dairy cows with left displaced abomasum or abomasal volvulus

OBJECTIVE

To compare abomasal luminal gas pressure and volume and perfusion of the abomasum in dairy cows with a left displaced abomasum (LDA) or abomasal volvulus (AV).

ANIMALS

40 lactating dairy cows (25 with an LDA and 15 with an AV).

PROCEDURE

Abomasal luminal gas pressure and volume and pulse oximetry values for the caudal portion of the dorsal ruminal sac and abomasal wall were measured during laparotomy. Abomasal perfusion was assessed on the basis of abomasal O2 saturation (pulse oximetry) before correction of the LDA or AV. Abomasal perfusion was also assessed after correction of the LDA or AV by measuring venous O2 saturation in the right gastroepiploic vein and calculating the abomasal oxygen-extraction ratio.

RESULTS

Abomasal luminal gas pressure and volume were higher in cattle with an AV than in cattle with an LDA. Abomasal O2 saturation was lower and abomasal oxygen-extraction ratio higher in cattle with an AV, compared with values in cattle with an LDA. In cows with an AV, lactate concentration in the gastroepiploic vein was greater than that in a jugular vein, whereas no difference in lactate concentrations was detected in cows with an LDA. Abomasal luminal gas pressure was positively correlated (r, 0.51) with plasma lactate concentration in the gastroepiploic vein and negatively correlated (r, -0.32) with abomasal O2 saturation determined by use of pulse oximetry.

CONCLUSIONS AND CLINICAL RELEVANCE

Abomasal perfusion decreases as luminal pressure increases in cattle with an AV or LDA.

Efeito da hidrocortisona sobre a lesão de reperfusão e reparação da mucosa após isquemia venosa experimental no jejuno de eqüinos

Os efeitos do succinato sódico de hidrocortisona (SSH) nas lesões de isquemia e reperfusão no jejuno foram estudados em 12 eqüinos submetidos a isquemia total arteriovenosa e venosa no jejuno. Após uma hora de isquemia, seis eqüinos receberam 4,0mg/kg/IV de SSH (grupo T) e os demais receberam placebo (grupo NT). Foram colhidas amostras para avaliação histomorfológica após uma e duas horas de isquemia e uma, duas e 12 horas de reperfusão, sendo as alterações quantificadas por meio de escores. Os escores para infiltração de neutrófilos, edema e hemorragia foram equivalentes entre os grupos T e NT. No segmento submetido a isquemia venosa o agravamento da lesão na mucosa durante a reperfusão foi significativo (P<0,05) apenas no grupo NT, indicando que o SSH atenuou a lesão de reperfusão no jejuno. Após 12 horas de reperfusão os escores para lesão na mucosa na isquemia arteriovenosa foram equivalentes entre os grupos T e NT. Na isquemia venosa os escores foram significativamente menores no grupo T (P<0,01), indicando que o tratamento com SSH acelerou a reparação das lesões. Estes resultados indicam que o SSH pode ser utilizado como tratamento adjuvante de afecções isquêmicas e de reperfusão no eqüino.