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Biomedical subjects

J R Snyder

Publications and source records attributed to J R Snyder.

At least 73 records · Page 4Linked to original sources
PubMed1992

Mammary adenocarcinoma in four mares.

Mammary gland adenocarcinoma in 4 horses was characterized by firm swelling of the gland and serosanguineous discharge from the teat orifice. Two of the mares had ulcerative lesions of the mammary gland. Palpation of the affected gland typically elicited signs of pain. Diagnosis was assisted by cytologic evaluation of the fluid discharge, but definitive diagnosis was based on histologic examination. Treatment included mastectomy and lymphadenectomy.

Adenocarcinoma↗
PubMed1992

Abnormal conditions of the equine descending (small) colon: 102 cases (1979-1989).

The signalment, clinical and laboratory findings of surgical conditions, treatment, and outcome of 102 cases of descending colon disease in horses were reviewed. Abnormal conditions were categorized as enteroliths, impactions, strangulating lipomas, fecaliths, foreign body obstruction, volvulus, nephrosplenic entrapment, and other conditions. Eleven breed categories of horses were seen during this period. Arabians, ponies, and American miniature horses were more predisposed to descending colon disease than other breeds (P less than 0.05). Female horses and animals greater than 15 years old were more likely to be affected with descending colon disease, whereas horses less than 5 years old were less likely to be affected (P less than 0.05). More specifically, Arabians, Quarter Horses, and Thoroughbreds greater than 10 years old were breeds that were overrepresented when compared with the hospital population (P less than 0.05). Enteroliths were most commonly seen in horses between 5 and 10 years old (P less than 0.05) and were not seen in horses less than 2 years old. Enteroliths had a tendency to develop more commonly in Arabians and in female horses. Impactions affected horses greater than 15 years old (P less than 0.05) and had a greater tendency to affect ponies and American miniature horses. Female horses were more commonly affected by impaction than were males. Strangulating lipomas were commonly seen in horses greater than 15 years old (P less than 0.05) and more specifically female Quarter Horses (P less than 0.05). Fecaliths tended to be a disease of horses less than 1 year old or greater than 15 years old and affected males more commonly than females.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1992

Resection and anastomosis of the small colon in four horses.

Resection and anastomosis of the small colon was performed on 4 horses with vascular lesions (strangulating lipoma, mesenteric tear, dissecting haematoma) or functional obstruction (stricture) of this area of the bowel. The anastomoses were performed using a variety of suture materials in 2 layers. An appositional, full-thickness, simple, interrupted pattern was used in the first layer in all cases and oversewn with either a Cushing pattern (3 cases) or a Utrecht pattern (1 case). Post-operative complications associated with suture material and surgical technique were not seen. All horses were discharged from the hospital and all were alive more than one year after discharge.

Anastomosis, Surgical↗
PubMed1992

Ultrastructural mucosal injury after experimental ischemia of the ascending colon in horses.

The ultrastructural injury that develops sequentially in the ascending colon during experimentally induced ischemia was examined in 6 halothane-anesthetized horses. Colonic ischemia was created by 2 types of vascular occlusion 24 cm proximal and distal to the pelvic flexure. In all horses, transmural vascular compression was created. The colonic venous circulation was obstructed in 3 horses, whereas in the other 3 horses, arterial and venous circulation was obstructed. Two additional horses were anesthetized as controls for determination of any morphologic alterations associated with the experimental protocol. Full-thickness colonic biopsy specimens were obtained from the antimesenteric border of the pelvic flexure at 0, 0.25, 0.5, 1, 1.5, 1.75, 2, 2.25, 2.5, 3, 3.5, 4, 4.5, and 5 hours during occlusion, and were studied by light and transmission electron microscopy. Morphologic alterations did not develop in the colon of control horses. Mucosal congestion was observed by light microscopy in the colon of horses with experimentally induced ischemia, but congestion developed early in those with obstructed colonic venous circulation, compared with those having arterial and venous obstruction. Inter- and intracellular vacuolation and loss of staining initially resulted in groups of 3 to 5 superficial luminal epithelial cells. Alterations in the glandular epithelium lagged behind those in the superficial epithelium, but were observed in both groups by 2 hours of obstruction. These changes progressed to 100% sloughing of all epithelium by 4.5 to 5 hours. The initial cellular alterations, which were observed by transmission electron microscopy, developed at 0.25 hour in horses with colonic venous obstruction and was characterized by inter- and intracellular edema.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Definition of the gracilis musculocutaneous flap for distant transfer in cats.

Dissection, injection, and surgical studies in feline cadavers and in anesthetized cats were conducted to determine the feasibility of using the gracilis muscle as the basis for a free musculocutaneous flap. The vascular pedicle of the flap consisted of the femoral artery and vein. Mean length (1.6 +/- 0.2 cm) of the vascular pedicle and mean artery (1.33 +/- 0.19 mm) and vein (2.55 +/- 0.38 mm) diameters were satisfactory for microvascular transfer. Fluorometry revealed overlying cutaneous perfusion in the flaps on the basis of their muscle vascular pedicles. To ensure survival of the flap, the muscular branches of the femoral artery and vein supplying the gracilis muscle had to be carefully preserved during surgical elevation of the flap.

Anastomosis, Surgical↗
PubMed1992

Microvascular circulation of the descending colon in horses.

The microvascular circulation of the descending colon was studied in 5 adult horses, using microangiography and light microscopy combined with gross studies and scanning electron microscopy of vascular replicas. After heparinization, horses were euthanatized, and 3 segments of the descending colon and its mesentery containing 1 vascular arcade were removed from each horse. The fecal balls were gently massaged from the lumen, and the blood was flushed free of the circulation with isotonic NaCl. In 5 segments, the vascular system was injected with a modified radiopaque medium and evaluated radiographically. Specimens examined radiographically also were prepared for histologic examination, using standard methods. Ten segments were injected with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. Arcuate arteries gave rise to a descending colonic rete that surrounded the vein and supplied numerous descending colonic lymph nodes. The rete also supplied the mesocolon and the descending colonic tissue. Short filamentous vessels arising from the rete directly penetrated the mesenteric tenia to supply an intermuscular plexus between the longitudinal and circular muscle layers of the muscularis externa. Larger vessels arising from either side of the rete divided into the long- and short-terminal arteries that supplied an extensive submucosal plexus, which was continuous around the circumference. The submucosal plexus supplied the mucosa, the tunica muscularis, and the serosa. Vessels running centrifugally from the submucosal plexus formed an intermuscular plexus between the longitudinal and circular muscle layers of the muscularis externa. The intermuscular plexus at the mesenteric angle also was supplied by vessels branching from the short-terminal arteries as they penetrated the muscularis externa.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1992

Microvascular circulation of the small intestine in horses.

The microvascular anatomic features of the small intestine was described by correlating results of microangiography, light microscopy, gross studies, and scanning electron microscopy of vascular replicas in 14 horses. After heparinization, the horses were euthanatized, a length of jejunum was transected, and blood was flushed free of the circulation, using isotonic NaCl solution. In six horses, the circulatory system was perfused with a modified radiopaque medium and evaluated radiographically. These sections were then evaluated by standard histologic methods. Sections from 8 horses were perfused with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. The marginal arterial arcade gives rise to vessels that enter the jejunum at the mesenteric angle. These vessels penetrated either directly, by branching and entering on both sides of the mesenteric angle, or supplying only 1 side of the mesenteric angle. All these vessels continued in the submucosa branching extensively, forming a submucosal plexus. This submucosal plexus supplied the tunica muscularis, tunica serosa, and the mucosa. Vessels within the 2 muscle layers ran parallel to the muscle fibers and, consequently, perpendicular to each other. The arterial supply to the mucosa penetrated the muscularis mucosae and branched to supply 2 mucosal capillary networks. An eccentrically placed arteriole penetrated the base of the villus and spiralled to the tip where it "fountained" into a mesh-like capillary network, which descended peripherally in the villus to drain via 1 to 3, but most commonly 2 venules. Venules from adjacent villi united and drained via the submucosal veins.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1991

Mesenteric tears of the descending (small) colon as a postpartum complication in two mares.

Segmental ischemic necrosis of the descending colon associated with discrete tears of the mesocolon were diagnosed in 2 mares following foaling. After foaling, both mares had a slow onset of signs of abdominal pain and gradual deterioration of clinical status. Increases in peritoneal fluid total protein concentration and WBC count and a palpable impaction of the descending colon on examination per rectum were useful diagnostic aids. Surgical intervention was successful in one mare, but not in the other.

Anastomosis, Surgical↗
PubMed1991

Radiographic findings in young llamas with forelimb valgus deformities: 28 cases (1980-1988).

Twenty-eight llamas with a mean age of 6.2 months had bilateral forelimb valgus deformities. The range of valgus deformity, as measured on a craniocaudal radiographic view, was 6 to 25 degrees, with a similar degree of deviation in each limb. Morphologic abnormalities in the distal portion of the radius and ulna were more prominent in the ulna and included metaphyseal and epiphyseal flaring, physeal ectasia, and metaphyseal sclerosis. Distal radial epiphyseal ectasia, and metaphyseal sclerosis. Distal radial epiphyseal wedging was believed to be secondary to the ulnar deformity. Radial bowing with lateral and caudal concavity and unequal cortical thickness was evident. Epiphyseal and metaphyseal flaring with physeal ectasia was noticed in the distal portion of the third and fourth metacarpal bones. Carpal bones were unaffected.

Animals↗
PubMed1991

Deoxygenated and alkylated furanoses: Thorpe-Ingold effects on tautomeric equilibria and rates of anomerization.

2-Deoxy-D-glycero-tetrose, 3-deoxy-DL-glycero-tetrose, 3-deoxy-3,3-di-C-methyl-DL-glycero-tetrose, 3-C-methyl-DL-erythrose, 3-C-methyl-DL-threose, 2-deoxy-5-O-methyl-D-erythro-pentose and 3-deoxy-5-O-methyl-D-erythro-pentose have been prepared, in some cases with 13C-substitution at the anomeric carbon, and characterized by 1H-(300 and 620 MHz) and 13C-n.m.r. (75 MHz) spectroscopy. The proportions of cyclic (alpha and beta furanoses) and acyclic (aldehyde and hydrate) forms were determined in aqueous (2H2O) solution, and ring-opening (kopen) and ring-closing (kclose) rate constants were measured by 1H and 13C saturation-transfer n.m.r. spectroscopy at p2H 5.0 (acetate buffer) and 60 degrees. The degree of furanose ring substitution was found to significantly affect both the thermodynamics and kinetics of furanose anomerization. Increased substitution enhances the proportion of cyclic forms in solution by stimulating furanose kclose. In contrast, furanose kopen was less affected by the degree of substitution; however, kinetic studies of 2-deoxyfuranose anomerization implicate furanose ring conformation as a potential determinant of kopen.

Alkylation↗
PubMed1991

Extensive resection and anastomosis of the descending (small) colon in a mare following strangulation by a mesenteric lipoma.

A 17-year-old Quarter Horse, Arabian crossbred mare presented with a history of having had abdominal pain for 2 d. At surgery there was 2.6 m of descending colon strangulated within the pedicle of a mesenteric lipoma. The lipoma was resected and the descending colon appeared viable so was replaced, and the mare recovered from anaesthesia. Post-operatively, the mare failed to stabilise so was taken back to surgery. There was 2 m of infarcted descending colon which was resected and anastomosed. A drain and stainless steel stay sutures were incorporated into the ventral suture line. Post-operatively the ventral wound became infected but was resolved with therapy. The diagnosis, surgical and post-operative management and outcome are discussed.

Anastomosis, Surgical↗
PubMed1991

Altered ionic permeability in skeletal muscle from horses with hyperkalemic periodic paralysis.

A recently described disorder in certain registered Quarter horses bears many clinical similarities to the muscle disease identified as hyperkalemic periodic paralysis (HPP) in humans. Pathological changes in membrane permeability or Na(+)-K+ pump activity have been proposed to produce the muscle depolarization and inexcitability that characterize the condition in humans. Biopsies of external intercostal muscle from normal and affected horses were used to determine whether alterations in either permeability and/or pump activity could be linked to the pathology in horses. Affected horse muscle is approximately 16 mV more depolarized than normal muscle at rest, and the muscle membrane potential of HPP horses is less responsive to changes in extracellular K+. Calculation of the relative membrane permeabilities of Na+ and K+ (PNa/PK) indicates that this ratio is significantly increased in HPP muscle. The increase is probably due to an increase in PNa rather than to a decrease in PK, since addition of 10(-6) M tetrodotoxin produces an approximately 14-mV membrane hyperpolarization in HPP fibers but is without effect in normal fibers. The clinical similarities between HPP in horses and humans suggest a common genetic defect in the two species.

Aging↗
PubMed1991

Effects of a highly concentrated hypertonic saline-dextran volume expander on cardiopulmonary function in anesthetized normovolemic horses.

Conventional fluid resuscitation is unsatisfactory in a small percentage of equine emergency surgical cases because the large volumes of fluids required cannot be given rapidly enough to adequately stabilize the horse. In anesthetized horses, the volume expansion and cardiopulmonary effects of a small volume of highly concentrated hypertonic saline-dextran solution were evaluated as an alternative initial fluid choice. Seven halothane-anesthetized, laterally recumbent, spontaneously ventilating, normovolemic horses were treated with a 25% NaCl-24% dextran 70 solution (HSD) at a dosage of 1.0 ml/kg of body weight, IV, infused over 10 minutes, and the effects were measured for 120 minutes after infusion. Plasma volume expansion was rapid and significant (from 36.6 +/- 4.6 ml/kg to 44.9 +/- 4.8 ml/kg), and remained significantly expanded for the duration of the experiment. Packed cell volume, total blood hemoglobin, and plasma protein concentrations significantly decreased, confirming rapid and sustained volume expansion with hemodilution. Cardiac index and stroke index immediately increased and remained high for the entire study (from 69.6 +/- 15.3 ml/min/kg to 106.6 +/- 28.4 ml/min/kg, and from 1.88 +/- 0.49 ml/beat/kg to 2.50 +/- 0.72 ml/beat/kg, respectively). Systemic vascular resistance significantly decreased immediately after HSD infusion and remained decreased for the duration of the study (from 1.41 +/- 0.45 mm of Hg/ml/min/kg to 0.88 +/- 0.22 mm of Hg/ml/min/kg). Arterial and venous blood oxygen content decreased significantly because of hemodilution, but actual oxygen transport transiently increased at the 10-minute measurement before returning toward baseline.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1991

Microvascular circulation of the cecum in horses.

The microvascular circulation of the cecum was studied in 15 adult horses, using microangiography and light microscopy combined with gross studies and scanning electron microscopy of vascular replicas. After heparinization, the horses were euthanatized and the cecum was transected at the cecocolic junction. Blood was flushed free of the circulation with isotonic NaCl and the cecal lumen was slightly distended. In 6 horses, the vascular system was injected with a modified radiopaque medium and evaluated radiographically. Sections evaluated radiographically were also prepared for histologic examination by standard methods. Eight horses were injected with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. In 1 additional horse, the lateral and medial arteries were injected with different colored plastic for gross studies. The lateral and medial cecal arteries appear to supply the respective areas of the cecum with minimal mixing of the 2 circulations. The major vascular supply to the cecal apex appeared to be through the medial cecal artery. Both the lateral and medial cecal arteries gave rise to cecal retia, which formed a mesh-like network around the respective veins. Vessels from these retia supplied the cecal tissue and the cecal lymph nodes. The continuation of the retia was through long terminal arteries that coursed around the circumference in the submucosa, forming an extensive submucosal plexus. This plexus supplied both the mucosa, and the tunica muscularis and serosa. Vessels within the longitudinal and circular muscle layers of the muscularis externa ran parallel to the muscle fibers, and consequently, perpendicular to each other.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1991

Collaborative research: benefits and guidelines.

Several benefits of collaborative research and guidelines for strengthening collaborative mechanisms have been described here, but the impetus for research and development of competent research teams must come from health professionals themselves. The literature makes it apparent that allied health professionals need to devote a considerable amount of energy and resources to develop a knowledge base for the health-related professions, similar to those in medicine and the biological sciences. Research projects, particularly collaborative ones, can make significant contributions to the body of professional knowledge, the knowledge-generation process, the health care practitioner, and the patient. The results of research should not be judged successful until its ultimate goal (ie, impact on patients and practice) has been measured. In collaborative research, relationships should be based on systems thinking, making networking into a scientific approach--a true partnership approach--which is crucial in dealing with the problems of health care today.

Allied Health Occupations↗
PubMed1991

Exploring the molecular basis for variability among patients with Becker muscular dystrophy: dystrophin gene and protein studies.

Becker muscular dystrophy (BMD) often results from in-frame mutations of the dystrophin gene that allow production of an altered but partially functional protein. To address potential structure-function relationships for the various domains of dystrophin, we examined both the dystrophin gene and protein in 68 patients with abnormal dystrophin. Eighty-six percent of BMD patients with dystrophin of altered size have deletions or duplications, and the observed sizes of dystrophin fit well with predictions based on DNA data. Deletions within the amino-terminal domain I tended to result in low levels of dystrophin and a more severe phenotype. The phenotypes of patients with deletions or duplications in the central rod domain were more variable. This region can be divided into three portions based on differences in clinical presentations of patients. Deletions around exons 4553 were most common and generally caused typical BMD; however, phenotypic variability among patients with similar mutations suggests that epigenetic and/or environmental factors play an important role in determining the clinical progression. In contrast, deletions or duplications in the proximal portion of this domain tended to cause severe cramps and myalgia. Finally, loss of the middle of this region probably causes a very mild phenotype, as only one such patient was found and his only symptom was elevated serum creatine phosphokinase levels.

Adolescent↗