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Biomedical subjects

J E Sojka

Publications and source records attributed to J E Sojka.

At least 19 recordsLinked to original sources
PubMed2004

Effect of hypothyroidism on the blood lipid response to higher dietary fat intake in mares.

Blood lipid and lipoprotein concentrations were measured and compared between euthyroid and thyroidectomized mares on low-fat or high-fat diets to test the hypothesis that hypothyroidism alters the blood lipid response to higher dietary fat intake. Four healthy adult mares and four adult mares that had been thyroidectomized 3 to 6 mo earlier were placed on low-fat or high-fat diets according to a replicated 2 x 2 Latin square design consisting of two 5-wk feeding periods separated by a 2-wk washout interval. Plasma lipid concentrations were measured at 0, 3, 4, and 5 wk, and plasma lipase activities were measured at the end of each 5-wk feeding period. Compared with euthyroid mares (0.46 ng/mL [range 0.34 to 0.68 ng/mL T3], and 21.5 ng/mL [range 18.1 to 25.1 ng/mL T4], respectively), median serum concentrations of T3 and T4 were lower (P = 0.029 and P = 0.021, respectively) in thyroid-ectomized mares (0.26 ng/mL [range 0.23 to 0.26 ng/ mL T3], and undetectable T4). Serum T4 concentrations were below the limits of detection in thyroidectomized horses. Alterations in body weight over 5 wk did not differ between groups. Mean plasma very low density lipoprotein (VLDL) and triglyceride (TG) concentrations were higher (P = 0.045 and 0.034, respectively) in hypothyroid mares (55.42 +/- 35.05 mg/dL and 52.83 +/- 34.46 mg/dL, respectively) compared with euthyroid mares (28.28 +/- 13.76 mg/dL and 23.53 +/- 9.84 mg/dL, respectively). Mean plasma total cholesterol (TC) concentrations increased from 88.73 +/- 25.49 mg/dL at baseline to 103.93 +/- 24.42 mg/dL after 5 wk on the low-fat diet, but increased by a greater magnitude (P = 0.006 diet +/- time interaction) in mares that were on the high-fat diet (81.05 +/- 17.24 mg/dL and 123.84 +/- 32.27 mg/ dL, respectively). Mean plasma TC concentrations were higher (P = 0.099) in hypothyroid mares (116.16 +/- 32.89 mg/dL) than in euthyroid mares (89.56 +/- 14.45 mg/ dL). Higher post-heparin plasma lipoprotein lipase and hepatic lipase activities (P = 0.012 andP = 0.017, respectively) were detected in mares that were on the high-fat diet (2.66 +/- 0.91 micromol FA x mL(-1) x h(-1) and 2.95 +/- 0.49 micromol FA x mL(-1) x h(-1), respectively) vs. a low-fat diet (1.75 +/- 0.55 micromol FA x mL(-1) x h(-1) and 2.27 +/- 0.59 micromol FA x mL(-1) x h(-1), respectively). We conclude that plasma VLDL and TG concentrations are elevated in hypothyroid mares, but the blood lipid response to higher dietary fat intake is not influenced by hypothyroidism.

Animals↗
PubMed2001

Fistulation of the auditory tube diverticulum (guttural pouch) with a neodymium:yttrium-aluminum-garnet laser for treatment of chronic empyema in two horses.

Two horses with chronic empyema of the auditory tube diverticulum (guttural pouch) were refractory to medical treatment; empyema was bilateral in 1 horse and unilateral in the other. Both horses were treated by fistulation of the cartilage of the pharyngeal orifice by use of a neodymium:yttrium-aluminum-garnet laser in a noncontact manner. To maintain patency of the fistulae, indwelling catheters were placed into the openings created by the laser. For both horses, long-term follow-up did not reveal complications, and both owners were satisfied with results of the procedure. The authors recommend this procedure for horses that are unresponsive to medical treatment for chronic guttural pouch empyema.

Animals↗
PubMed2000

Treatment of granular cell tumor via complete right lung resection in a horse.

A 7-year-old warmblood mare was referred because of a respiratory tract disorder; pulmonary granular cell tumor was diagnosed. Pulmonary granular cell tumor is a locally invasive but rare type of tumor with low metastatic potential. The entire right lung was resected to ensure removal of all neoplastic tissue. The horse recovered well and has minimal difficulties functioning with one lung. Most of these tumors are diagnosed during postmortem examination. To our knowledge, this is the first report of pulmonary granular cell tumor treated by complete lung resection in a horse.

Analgesics, Opioid↗
PubMed2000

Use of ultrafiltration probes in sheep to collect interstitial fluid for measurement of calcium and magnesium.

Studies of calcium and magnesium changes in living animals usually involve blood, urine, and fecal samples. These samples provide only information on whole-body averages and give no indication of differences between tissues. Ultrafiltration probes were developed to sample interstitial fluid from muscle, bone, and subcutaneous tissue of sheep to provide a tool for investigating tissue differences in calcium and magnesium concentrations. The potential of the probes for mineral distribution studies was demonstrated in sheep by using infusion of a calcium gluconate solution.

Animals↗
PubMed1999

Effect of hypothyroidism on blood lipid concentrations in horses.

OBJECTIVE: To measure and compare concentrations of selected blood lipids before and after thyroidectomy in horses. ANIMALS: 5 healthy adult mares. PROCEDURE: Mares were confirmed to be euthyroid. Thyroidectomy was performed, and hypothyroidism was confirmed. Selected blood lipid variables were measured before hypothyroidism was induced and weekly for 4 weeks after induction. Plasma concentrations of very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), serum triglyceride (TG), total cholesterol (TC), and nonesterified fatty acid (NEFA) were measured. The composition of VLDL and LDL also was examined. RESULTS: Mean plasma concentrations of VLDL and LDL increased significantly after thyroidectomy. By 4 weeks after thyroidectomy, a ninefold increase in mean plasma concentration of VLDL and a threefold increase in LDL, compared with baseline values, were detected. After thyroidectomy, mean percentage of TG in VLDL increased significantly, whereas free cholesterol and cholesterol ester content decreased. Mean percentage of TG in LDL also increased by 3 to 4 weeks after thyroidectomy. Serum concentrations of TG and TC increased, whereas serum NEFA concentration decreased. CONCLUSIONS: Hypothyroidism significantly alters blood lipid concentrations of horses. After thyroidectomy, markedly high VLDL concentration, appearance of TG-rich VLDL, increased serum concentrations of TG and TC, and decreased blood concentration of NEFA were evident. CLINICAL RELEVANCE: Examination of blood lipid concentrations of horses may be useful for detecting naturally acquired hypothyroidism.

Animals↗
PubMed1999

Subconjunctivally implanted micro-osmotic pumps for continuous ocular treatment in horses.

OBJECTIVE: To evaluate the feasibility of using a subconjunctivally implanted micro-osmotic pump for continuous delivery of medication to the eyes of horses- during a 7-day period. ANIMALS: 4 healthy adult horses. PROCEDURE: With horses restrained in a standing position, micro-osmotic pumps were implanted subconjunctivally in each eye for 7 days. The treatment eye received an atropine-loaded micro-osmotic pump (100 microl of 1.5% atropine), and the contralateral eye received a sterile saline-loaded pump (100 microl of 0.9% NaCl) as a control treatment. Pupil size was measured at 12-hour intervals until values returned to baseline. RESULTS: The micro-osmotic pumps were tolerated and did not migrate or become dislodged. During the 7-day treatment period, pupils were significantly larger in the eyes implanted with atropine-loaded pumps, compared with saline-implanted control eyes. CONCLUSIONS AND CLINICAL RELEVANCE: Micro-osmotic pumps were implanted and removed easily from standing horses and were not associated with complications during the 7-day treatment period. Therefore, subconjunctivally implanted micro-osmotic pumps can potentially be used when treating ophthalmic disease in horses.

Animals↗
PubMed1995

Evaluation of endocrine function.

This article outlines strategies on how to approach equine endocrine disorders based on clinical signs and clinical pathologic data. In the 1987 Veterinary Clinics of North America: Equine Practice article on evaluating equine endocrine function, Beech stated that the numbers of hormonal assays available to use in horses was limited. Unfortunately, not much has changed since then. With the advent of convenient assay kits for many hormones and cofactors available in human medicine, it is possible to submit samples to laboratories for measurement of a wide range of endogenous substances. Caution must be used when interpreting the results in equine patients. Assay kits that have not been validated for use in horses may yield results that have no clinical meaning. Using veterinary endocrinology laboratories with equine experience is the best way to assure meaningful results from diagnostic testing (Table 1). If this is not possible, submitting age, breed, and sex-matched controls along with samples from the patient horse will provide some measure of a reference range. Normal values or reference ranges from species other than the horse cannot be used to interpret the results of equine samples.

Adrenal Glands↗
PubMed1995

Magnesium supplementation and osteoporosis.

Among other things, magnesium regulates active calcium transport. As a result, there has been a growing interest in the role of magnesium (Mg) in bone metabolism. A group of menopausal women were given magnesium hydroxide to assess the effects of magnesium on bone density. At the end of the 2-year study, magnesium therapy appears to have prevented fractures and resulted in a significant increase in bone density.

Bone Density↗
PubMed1993

The effect of starting time on dexamethasone suppression test results in horses.

This study was conducted to investigate the effect of starting time on dexamethasone suppression test results in horses. Eight adult horses were used throughout the trial. Baseline cortisol levels were established by collecting cortisol levels twice daily, at 8:00 A.M. and 8:00 P.M. for 4 consecutive days. Morning baseline cortisol levels were 46.3 +/- 5.94 ng/ml, and evening baseline cortisol levels were 32.8 +/- 5.59 ng/ml. Although lower, the evening cortisol levels were not statistically different (P = 0.154) from the morning levels. Dexamethasone suppression tests initiated at either 9:00 A.M. or 9:00 P.M. were performed by collected a control blood sample, administering either 0.044 mg/kg dexamethasone or its vehicle intravenously and then collecting additional blood samples at 6, 12, 24, 36, and 48 hr after treatment. Mean cortisol levels at hr 0, 6, 12, 24, 36, and 48 after a dexamethasone injection given at 9:00 A.M. were 55.6 +/- 3.08, 6.4 +/- 2.05, 0.73 +/- 0.48, 11.0 +/- 5.82, 12.6 +/- 4.30, and 40.5 +/- 5.38 ng/ml respectively. Mean cortisol levels at hr 0, 6, 12, 24, 36, and 48 hr after a dexamethasone injection given at 9:00 P.M. were 45.0 +/- 6.03, 4.5 +/- 1.28, 0.20 +/- 0.12, 4.5 +/- 2.49, 23.4 +/- 5.88, and 29.5 +/- 6.61 ng/ml respectively. There was no statistical difference in cortisol values between A.M. and P.M. initiated tests at any hour post dexamethasone administration. There was no decrease in cortisol level after administration of dexamethasone vehicle.

Analysis of Variance↗
PubMed1993

Serum triiodothyronine, total thyroxine, and free thyroxine concentrations in horses.

The objectives of this experiment were to determine serum concentrations of triiodothyronine (T3), thyroxine (T4), and free thyroxine (fT4) at rest, following thyroid-stimulating hormone (TSH) administration, and following phenylbutazone administration in healthy horses. This was done to determine which available laboratory test can best be used for diagnosis of hypothyroid conditions in horses. Serum T3, T4, and fT4 concentrations in serum samples obtained before and after TSH stimulation and following phenylbutazone administration for 7 days were determined. Baseline values ranged from 0.21 to 0.80 ng of T3/ml, 6.2 to 25.1 ng of T4/ml, and 0.07 to 0.47 ng of fT3/dl. After 5 IU of TSH was administered IV, serum T3 values increased to 6 times baseline values in 2 hours. Thyroxine values increased to 3 times baseline values at 4 hours and remained high at 6 hours. Free T4 values increased to 4 times baseline values at 4 hours and remained high at 6 hours. Administration of 4.4 mg of phenylbutazone/kg, every 12 hours for 7 days significantly decreased T4 and fT4 values, but did not significantly affect serum T3 concentrations. It was concluded that a TSH stimulation test should be performed when hypothyroidism is suspected. Measurement of serum fT4 concentrations, by the single-stage radioimmunoassay, does not provide any additional information about thyroid gland function over that gained by measuring T4 concentrations. Phenylbutazone given at a dosage of 4.4 mg/kg every 24 hours, for 7 days did significantly decrease resting T4 and fT4 concentrations, but did not significantly affect T3 concentrations in horses.

Analysis of Variance↗
PubMed1992

Effect of the somatostatin analogue octreotide on gastric fluid pH in ponies.

The effect of the somatostatin analogue, octreotide, on gastric fluid pH was investigated in 4 ponies. Gastric fluid pH was determined after SC administration of octreotide or physiologic saline solution (control). A baseline sample of fluid was obtained, the agent was given, and 8 additional samples were collected hourly. Administration of octreotide at all dosages tested (0.1, 0.5, 1.0, and 5.0 micrograms/kg of body weight) increased gastric pH to > 5.0. Baseline values were consistently < 2.7. Administration of octreotide at these same dosages induced gastric pH values > 4.0 for 2.4 +/- 1.2, 4.8 +/- 0.8, 5.7 +/- 1.3, and 5.4 +/- 2.6 (mean +/- SD) continuous hours, respectively. Treatment at all dosages increased the pH of gastric fluid, compared with control values. The duration of the increase in pH was significantly (P < 0.05) different than that of the control treatment, even for the lowest dosage, 0.1 microgram/kg.

Animals↗
PubMed1988

Effect of butorphanol, pentazocine, meperidine, or metoclopramide on intestinal motility in female ponies.

Effect of butorphanol, pentazocine, meperidine, and metoclopramide on jejunal and pelvic flexure myoelectric and mechanical activity in 4 female ponies was investigated. The agent to be tested or saline solution was administered IV at the start of a 6-hour recording trial. In the jejunum, duration between activity fronts of regular spiking activity, defined as the length of the migrating myoelectric complex (MMC), was measured. The average duration of the MMC during control trials was 150 +/- 46 minutes. The average duration of the MMC after meperidine, butorphanol, pentazocine, and metoclopramide administration was 295 +/- 70 minutes, 260 +/- 60 minutes, 275 +/- 60 minutes, and 163 +/- 64 minutes, respectively. Meperidine, butorphanol, or pentazocine significantly increased the MMC duration (P less than 0.05), and did not significantly alter the pelvic flexure activity. Seemingly, meperidine, butorphanol, and pentazocine inhibited cyclic myoelectric activity in the jejunum. Metoclopramide had no effect on jejunal or pelvic flexure motility.

Analgesics↗
PubMed1986

Pharmacokinetic adjustment of gentamicin dosing in horses with sepsis.

Serum gentamicin concentrations were measured and pharmacokinetic values were calculated for 12 equine patients receiving parenteral gentamicin therapy. Horses were selected for monitoring of gentamicin pharmacokinetics if they met several criteria of high risk for gentamicin-induced toxicosis. Two blood samples were obtained, one immediately before gentamicin dosing and one at 1 hour after dosing. Gentamicin serum concentrations were analyzed and dosage adjustments were made on the basis of calculated one-compartment pharmacokinetic values. Nine of the 12 horses required dosage adjustment to optimize therapeutic concentrations. Even for horses for which there was no evidence of decreased renal function, variation in the disposition of gentamicin was substantial. Because of the larger volume of distribution in foals, an initial dosage of 3 mg/kg every 12 hours was found to best approximate target concentrations. Therefore, published standard dosages were a poor means of achieving desired peak and trough concentrations in many animals. Seemingly, for optimal treatment of horses with sepsis, gentamicin dosage adjustments based on the patient's pharmacokinetic values is required.

Animals↗
PubMedDate not supplied

Surgical implantation of ultrafiltration probes in ovine bone and muscle.

It may be desirable to collect compounds directly from sites of interest if blood concentrations do not reflect tissue levels. Ultrafiltration and microdialysis probes may be used to do this, but the hollow fibers of these probes are quite fragile. For this reason, we developed a pull-through technique that allows their implantation into the ovine quadriceps muscle and femur. The sheep is placed under anesthesia in lateral recumbency. An incision is made midway between the patella and greater trochanter directly over the lateral femur. A hand drill is used to make a 4.5-mm hole into the medullary cavity through the lateral cortex of the distal femur. A second incision is then made over the greater trochanter. The drill bit is inserted into the trochanteric fossa and a hole is drilled distally through the medullary cavity of the femur to the level of the first hole. A looped 20-gauge wire is then inserted into the femur and removed through the distal hole. Suture is attached, and the wire is withdrawn, leaving the suture in place. The suture is tied to the ultrafiltration probe tubing, allowing the probe to be carefully drawn into position. For implantation into the muscle, a 10-gauge introducer is used. The introducer is placed through the quadriceps muscle and the probe is then threaded through it. This technique has been successfully performed on 18 sheep. All sheep tolerated the procedure well. Up to 2.0 mL/day of interstitial fluid was recovered from each site. The average lifetimes of the bone and muscle probes were 35 and 40 days, respectively.

Animals↗
PubMedDate not supplied

Ovariohysterectomy in six mares.

Six mares had ovariohysterectomy performed for chronic pyometra associated with cervical abnormalities, uterine neoplasia, or removal of a macerated fetus. Ovariohysterectomy was performed through a ventral midline incision with access to the ovarian and uterine vessels aided by traction on the uterus and retraction of abdominal viscera. Abdominal pain, the most common complication after surgery, occurred in four mares but resolved within 36 hours. Peritonitis occurred in two mares; one mare was subsequently euthanatized. Other complications that resolved with treatment included infection of the uterine stump (two mares), abdominal hemorrhage (one mare), diarrhea (one mare), and incisional infection (one mare). Complications after surgery can be reduced by removing as much of the uterus as possible, minimizing peritoneal contamination with uterine contents, and providing a secure closure of the caudal reproductive tract.

Animals↗