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Biomedical subjects

S L Marks

Publications and source records attributed to S L Marks.

At least 37 records · Page 2Linked to original sources
PubMed1998

The principles and practical application of enteral nutrition.

The enteral route is the preferred method of nutritional support in patients with functional gastrointestinal tracts. Many techniques for obtaining enteral access are available, and the decision regarding which one to use depends on several issues, including the functional integrity of each part of the gastrointestinal tract, the duration of anticipated nutritional support, and the risk of aspiration and gastroesophageal reflux. Nasoesophageal tubes are useful for short-term supplementation; however, patients needing nutritional support for longer than 2 weeks may be better served with a more permanent tube. Blenderized pet food diets are recommended for nutritional support because these diets do not need to be supplemented with protein or micronutrients. Commercial human enteral formulas provide a useful alternative for patients with specific nutrient requirements or for feeding via nasoesophageal or jejunostomy tubes.

Animals↗
PubMed1998

Critical care cardiology.

Emergency management of the patient with cardiac disease is an important part of veterinary practice. Although the causes of cardiac disease may be diverse, the understanding of basic pathophysiology will enable the clinician to formulate a rational diagnostic and therapeutic plan. The veterinary clinician must be able to triage the emergency patient, assess the clinical condition, and provide appropriate therapy. Close monitoring of the critically ill patient is crucial to patient survival and will help tailor therapy.

Animals↗
PubMed1998

Clinical and morphologic features of mucopolysaccharidosis type II in a dog: naturally occurring model of Hunter syndrome.

A 5-year-old male Labrador Retriever had progressive incoordination, visual impairment, and exercise intolerance. Coarse facial features, macrodactylia, unilateral corneal dystrophy, generalized osteopenia, progressive neurologic deterioration, and a positive urine spot test for acid mucopolysaccharides suggested mucopolysaccharidosis. Intracytoplasmic vacuoles were most prevalent in epithelial cells, endothelial cells, and histiocytes of liver, kidney, thyroid gland, and spleen. Ultrastructural examination disclosed electron-lucent floccular to lamellar membrane-bound storage material characteristic of mucopolysaccharides. Periodic acid-Schiff-positive intracytoplasmic material was identified in multiple neurons in the medulla, pontine nucleus, cerebellum, and spinal gray matter horns. Biochemical assays identified a deficiency in iduronate-2-sulfatase (IDS) activity in cultured dermal fibroblasts compared with normal dogs. Hair root analysis for IDS showed that the dam was a carrier of X-linked Hunter syndrome and that a phenotypically normal male littermate of the affected dog was normal. This is the first report of Hunter syndrome or mucopolysaccharidosis type II in a dog.

Animals↗
PubMed1998

Time course of gastrointestinal tract permeability to chromium 51-labeled ethylenediaminetetraacetate in healthy dogs.

OBJECTIVES: To establish values for gastrointestinal tract permeation by chromium 51-labeled ethylenediaminetetraacetate (51Cr-labeled EDTA) in healthy adult dogs, and to evaluate the time course for 51Cr-labeled EDTA absorption over a 24-hour period after its administration, in an effort to define a shorter, more practical collection method. ANIMALS: 6 healthy adult mixed-breed dogs. PROCEDURE: After an 18-hour nonfeeding period, each dog was given a solution containing 50 microCi of 51Cr-labeled EDTA in deionized water (10 ml/kg of body weight) by stomach tube. Complete urine collection was done at 2, 4, 6, and 24 hours after 51Cr-labeled EDTA administration. Five-milliliter samples of urine were counted for 15 minutes in a gamma counter, and radioactivity in urine was expressed as a percentage of the orally administered dose. RESULTS: Median (range) 24-hour urinary recovery of 51Cr-labeled EDTA after 24 hours was 15.1 (12.7 to 20.3)%. Urine collected at 2, 4, and 6 hours contained 1.0 (0.2 to 3.5)%, 6.5 (2.2 to 8.7)%, and 10.0 (8.1 to 11.7)% of the administered 51Cr-labeled EDTA, respectively. Urine passed during the first 6 hours contained, on average, 67 (54 to 77)% of the total 24-hour urine recovery. CONCLUSIONS: 6-hour urinary recovery of 51Cr-EDTA provides a potential alternative to 24-hour recovery. This shorter collection period may more specifically reflect small intestinal permeability.

Animals↗
PubMed1997

Dietary modulation of methotrexate-induced enteritis in cats.

OBJECTIVE: To determine effects of purified and dry expanded (complex) diets on intestinal structure and function in healthy cats and in a feline model of methotrexate-induced enteritis. ANIMALS: 19 adult specific-pathogen-free cats. PROCEDURE: Cats were randomized in groups to receive a purified diet intragastrically or a complex diet orally to meet their daily metabolizable energy requirements. After 21 days, cats received either methotrexate (MTX; 10 mg/kg of body weight, i.v., n = 12) or saline solution i.v. (n = 7), and were anesthetized 72 hours later. Celiotomy was performed for aseptic removal of mesenteric lymph nodes, full-thickness biopsy of the gastrointestinal tract, and collection of aortic and portal venous blood samples for determination of arteriovenous amino acid concentrations across the intestine. RESULTS: MTX was associated with severe enterotoxicosis in cats receiving the purified diet, as manifested by diarrhea (4 of 6 cats) and vomiting (2 of 6 cats). One cat receiving the complex diet developed mild diarrhea, and none of these cats vomited. The purified diet was associated with marked villus blunting in the proximal and distal portions of the duodenum and increased bacterial translocation (3 of 6 cats), whereas none of the cats in the complex diet group developed bacterial translocation after MTX administration. For the cats given saline solution, bacterial translocation occurred in 1 of 4 cats receiving the complex diet versus 2 of 3 cats receiving the purified diet. CONCLUSIONS: Feeding of a complex diet containing intact protein as the nitrogen source abrogated the proximal small intestinal atrophy and bacterial translocation associated with feeding an amino acid-based purified diet. CLINICAL RELEVANCE: Use of purified diets containing free amino acids as the only nitrogen source cannot be endorsed in human and animal cancer patients receiving systemic chemotherapy.

Animal Feed↗
PubMed1996

Acute lymphoblastic leukemia, hypercalcemia, and pseudohyperkalemia in a dog.

A 5-month-old sexually intact male Chesapeake Bay Retriever was evaluated for lameness of 2 weeks' duration and lymphocytosis. Acute lymphoblastic leukemia was diagnosed on the basis of results of cytologic and cytochemical evaluation of a bone marrow aspirate. Serum biochemical abnormalities included hypercalcemia and hyperkalemia. Hypercalcemia was likely paraneoplastic; hyperkalemia was believed to be a result of release of potassium from large numbers of lymphocytes in vitro (pseudohyperkalemia). The dog was euthanatized, and necropsy revealed infiltration of the hepatic vasculature and sinusoids, renal parenchyma, mesenteric and peripheral lymph nodes, bone marrow, and iridial tissue with neoplastic cells. Unique features of this case include the young age of the dog and the hypercalcemia and hyperkalemia associated with acute lymphoblastic anemia.

Animals↗
PubMed1996

Effects of acepromazine maleate and phenoxybenzamine on urethral pressure profiles of anesthetized, healthy, sexually intact male cats.

OBJECTIVES: To evaluate the effects of 2 compounds with alpha adrenergic antagonist properties on the urethral pressures of anesthetized, healthy, sexually intact male cats, and to evaluate one of the compounds for effect on striated muscle. ANIMALS: 20 healthy, sexually intact male cats. PROCEDURE: Cats were anesthetized with halothane, and urethral pressure profilometry was performed before and after treatment. 125I-labeled alpha-bungarotoxin bound to nicotinic receptors of murine skeletal muscle was used in a competitive binding study with acepromazine maleate. RESULTS: Acepromazine maleate significantly decreased intraurethral pressures in the preprostatic (19%) and prostatic (21%) regions of the urethra. There was no effect on the postprostatic/penile segment. Acepromazine did not inhibit 125I-labeled alpha-bungarotoxin binding to nicotinic receptors in murine skeletal muscle. Phenoxybenzamine significantly decreased intraurethral pressures (14%) in the preprostatic region of the urethra only. CONCLUSIONS: Acepromazine maleate and phenoxybenzamine have effects on the smooth muscle of the urethra of healthy, male cats. Acepromazine has no effect on striated muscle. CLINICAL RELEVANCE: alpha-Adrenergic compounds may be used in the pharmacologic management of feline urinary tract disease.

Acepromazine↗
PubMed1995

Urethral pressure response to smooth and skeletal muscle relaxants in anesthetized, adult male cats with naturally acquired urethral obstruction.

The effects of the skeletal muscle-relaxing drug dantrolene sodium alone, and in combination with the alpha 1-adrenergic antagonist prazosin, on the urethral pressure profile were investigated in male cats with obstructive lower urinary tract disease. Decreases in mean segmental intraurethral pressure induced by dantrolene (n = 3) or dantrolene in combination with prazosin (n = 3) were evaluated statistically, using a paired design. Statistical analysis was applied to absolute (mm of Hg) pressure values. Intravenous administration of dantrolene alone (1 mg/kg of body weight, n = 3) significantly decreased pressure in the postprostatic/penile urethral segment, but did not decrease prostatic urethral pressures. Dantrolene in combination with prazosin (0.03 mg/kg IV) caused a 20% pressure decrease in the prostatic segment (P = 0.060). Preprostatic urethral pressure was not significantly affected by either treatment regimen in the small pool of cats studied. There was no difference in baseline pressures (mm of Hg) in the 3 intraurethral segments of these 6 recently obstructed male cats, compared with historic baseline pressures (mm of Hg) in the 3 intraurethral segments of 28 healthy male cats. These results indicate that dantrolene and prazosin may be effective in relaxing intraurethral skeletal and smooth musculature in male cats clinically afflicted with obstructive lower urinary tract disease. However, it is not certain that administration of muscle relaxants would facilitate urethral catheterization and removal of the obstruction in male cats with blockage of the lower urinary tract. Strikingly, results of this study suggest that urethral muscle spasm had a minor role in these cats.

Animals↗
PubMed1994

Conception by use of postmortem epididymal semen extraction in a dog.

A 9-year-old sexually intact male Boxer was euthanatized because of progressive, generalized seizures that were refractory to medical treatment. To try to preserve the breeding line, postmortem epididymal semen extraction was attempted. The testes were excised after the dog was euthanatized, and semen was extracted, frozen, and stored in liquid nitrogen. Approximately 3.5 months later, a suitable recipient was identified, and surgical intrauterine insemination was performed. Fifty-seven days after insemination, a viable pup was born.

Animals↗
PubMed1994

99mTc-pertechnetate imaging of thyroid tumors in dogs: 29 cases (1980-1992).

Thyroid gland scintigraphy was performed in 29 dogs with histologically confirmed thyroid tumors. Twenty dogs were female, and 9 were male. Median age was 10 years. Of the 29 dogs, 21 were initially examined because of cervical swelling or a cervical mass. Of the 29 tumors, 24 were thyroid adenocarcinomas, 1 was a C-cell carcinoma, 3 were undifferentiated carcinomas, and 1 was a thyroid adenoma. Serum triiodothyronine and thyroxine concentrations were determined in 25 dogs. Sixteen dogs were euthyroid, 6 were hyperthyroid, and 3 were hypothyroid. In all 29 dogs, results of scintigraphy were abnormal. The most common scintigraphic appearance (13 dogs) was a unilateral thyroid mass with increased radionuclide uptake, relative to that of the parotid salivary glands. There did not appear to be an association between distribution of radionuclide uptake and histologic diagnosis, although there appeared to be an association between distribution of uptake and histologic degree of capsular invasion. All 4 dogs with extensive capsular invasion and 11 of 17 dogs with limited capsular invasion had poorly circumscribed, heterogeneous uptake of pertechnetate by the tumor. All hyperthyroid dogs had intense uptake, and 5 of 6 hyperthyroid dogs had well-circumscribed, homogenous uptake. Scintigraphy did not appear to offer any additional benefit, compared with thoracic radiography, for detection of pulmonary metastases.

Adenocarcinoma↗
PubMed1994

Aspergillosis in an ostrich.

A 4-month-old sexually intact blue-neck ostrich was examined because of chronic respiratory tract disease and poor performance. The bird was coughing and dyspneic on physical examination. Thoracic radiographs were consistent with air sacculitis. Bronchoscopy was used to view and to biopsy plaques within the bronchus and lower airways. Aspergillus spp was identified in culture and in biopsy specimens examined microscopically. Aspergillosis was confirmed on postmortem examination. Bronchoscopy may aid in the early diagnosis and treatment of this disease.

Air Sacs↗
PubMed1994

Effect of succinylcholine, diazepam, and dantrolene on the urethral pressure profile of anesthetized, healthy, sexually intact male cats.

Effects of the neuromuscular blocking agent succinylcholine (n = 9), the centrally acting skeletal muscle relaxant diazepam (n = 11), and the directacting skeletal muscle relaxant dantrolene sodium (n = 8) on the urethral pressure profile were evaluated in anesthetized, healthy, sexually intact, adult male cats. Intravenous administration of succinylcholine (0.075 mg/kg of body weight) significantly decreased mean absolute pressure in the prostatic and post-prostatic/penile intraurethral segments by -9.5 and -6.5 mm of Hg, respectively (P = 0.0002 and P = 0.0006, respectively). Dantrolene (1.0 mg/kg, IV) significantly decreased mean prostatic and postprostatic/penile intraurethral segmental pressures by -3.5 and -2.8 mm of Hg, respectively (P = 0.005 and P = 0.0181, respectively). Diazepam (0.8 mg/kg, IV) did not significantly alter mean intraurethral segmental pressures. None of the drugs caused a change in segmental lengths of the urethra. These results indicate that skeletal muscle makes a substantial contribution to intraurethral tone in anesthetized, healthy, sexually intact male cats and that skeletal muscle relaxation may be successful in reducing prostatic and post-prostatic/penile urethral segmental tone in male cats. These results also suggest that dantrolene sodium may be valuable for the pharmacologic management of urethral disorders in male cats.

Anesthesia, General↗
PubMed1992

Clinical evaluation of etretinate for the treatment of canine solar-induced squamous cell carcinoma and preneoplastic lesions.

BACKGROUND: Tumors of the skin and subcutaneous tissue account for 30% of all canine neoplasms. Canine solar-induced squamous cell carcinoma (SCC) is the most frequently reported canine cutaneous neoplasm. OBJECTIVE: The purpose of this study was to provide preliminary observations on the safety and efficacy of etretinate for the treatment of solar-induced SCC and associated preneoplastic lesions in dogs. METHODS: Etretinate was administered to 10 dogs at 1 mg/kg twice daily for a minimum of 90 days. RESULTS: Clinically, two dogs showed complete resolution of their preneoplastic lesions, three dogs had partial responses, two dogs maintained stable disease, and three dogs showed progression of lesions after 90 days of etretinate administration. Three dogs showed histologic improvement, four dogs showed no changes, and three dogs showed evidence of progressing SCC. Treatment-related biochemical abnormalities included reversible hypertriglyceridemia and transient serum liver enzyme elevations in three dogs. CONCLUSION: These preliminary findings suggest that etretinate, at the dosage administered, may provide therapeutic efficacy for solar-induced preneoplastic lesions in the dog, particularly for those multifocal lesions not easily managed by local methods of therapy.

Animals↗