Biomedical subjects

S L Sanderson

Publications and source records attributed to S L Sanderson.

14 recordsLinked to original sources

PubMed2001

Crossflow filtration in suspension-feeding fishes.

Rows of comb-like or tufted gill rakers in the oral cavity of suspension-feeding fishes (for example, herring, anchovies and tilapia) have been thought to serve as (1) non-porous barriers that direct particle-laden water to the sticky oral roof, where particles are retained as water exits from the oral cavity, (2) conventional dead-end filters that sieve particles from water exiting between rakers, or (3) sticky filters that retain particles encountered by a hydrosol filtration mechanism. Here we present data from computational fluid dynamics and video endoscopy in suspension-feeding fish indicating that the rakers of three distantly related species function instead as a crossflow filter. Particles are concentrated inside the oral cavity as filtrate exits between the rakers, but particles are not retained on the rakers. Instead, the high-velocity crossflow along the rakers carries particles away from the raker surfaces and transports the particles towards the oesophagus. This crossflow prevents particles from clogging the gaps between the rakers, and solves the mystery of particle transport from the rakers to the oesophagus.

Animals↗

PubMed2001

Computational fluid dynamics in the oral cavity of ram suspension-feeding fishes.

We have modeled steady, three-dimensional flow with a no-slip boundary condition in cylindrical and conical oral cavities possessing vertical or slanted branchial slits. These numerical simulations illustrate the transport of food particles toward the esophagus, as well as the velocity profiles of water exiting the oral cavity via the branchial slits. The maximum and average velocities are highest for flow exiting the most posterior branchial slit. The highest volume flow rates also occur in the most posterior slit for the cylindrical simulations, but occur in the most anterior slit for the conical simulations. Along the midline, there is a pronounced bilaterally symmetrical vortex in the posterodorsal region of the cylindrical and conical oral cavities and a second bilaterally symmetrical vortex in the posteroventral region of the cylinder. Particles entrained in the vortices will recirculate in the posterior oral cavity, increasing the probability of encounter with sticky, mucus-covered surfaces such as the oral roof, gill arches, or gill rakers. The posterodorsal vortex could serve to concentrate particles near the entrances of the epibranchial organs. The ventral vortex could be involved in sequestering dense inorganic particles that sink toward the floor of the oral cavity. All vortices are absent in the conical simulation with vertical branchial slits, indicating that the slanted branchial slits between the gill arches are responsible for the formation of the vortex in the conical oral cavity. Experiments using in vivo flow visualization techniques are needed to determine whether ram suspension feeders, pump suspension feeders, and non-suspension-feeding fishes possess vortices in the posterior oral cavity that contribute to particle transport, food particle encounter with sticky surfaces, and inorganic particle rejection.

Animals↗

PubMed2001

Effects of dietary fat and L-carnitine on plasma and whole blood taurine concentrations and cardiac function in healthy dogs fed protein-restricted diets.

OBJECTIVE: To evaluate plasma taurine concentrations (PTC), whole blood taurine concentrations (WBTC), and echocardiographic findings in dogs fed 1 of 3 protein-restricted diets that varied in fat and L-carnitine content. ANIMALS: 17 healthy Beagles. DESIGN: Baseline PTC and WBTC were determined, and echocardiography was performed in all dogs consuming a maintenance diet. Dogs were then fed 1 of 3 protein-restricted diets for 48 months: a low-fat (LF) diet, a high-fat and L-carnitine supplemented (HF + C) diet, or a high-fat (HF) diet. All diets contained methionine and cystine concentrations at or above recommended Association of American Feed Control Officials (AAFCO) minimum requirements. Echocardiographic findings, PTC, and WBTC were evaluated every 6 months. RESULTS: The PTC and WBTC were not significantly different among the 3 groups after 12 months. All groups had significant decreases in WBTC from baseline concentrations, and the HF group also had a significant decrease in PTC. One dog with PT and WBT deficiency developed dilated cardiomyopathy (DCM). Taurine supplementation resulted in significant improvement in cardiac function. Another dog with decreased WBTC developed changes compatible with early DCM. CONCLUSIONS AND CLINICAL RELEVANCE: Results revealed that dogs fed protein-restricted diets can develop decreased taurine concentrations; therefore, protein-restricted diets should be supplemented with taurine. Dietary methionine and cystine concentrations at or above AAFCO recommended minimum requirements did not prevent decreased taurine concentrations. The possibility exists that AAFCO recommended minimum requirements are not adequate for dogs consuming protein-restricted diets. Our results also revealed that, similar to cats, dogs can develop DCM secondary to taurine deficiency, and taurine supplementation can result in substantial improvement in cardiac function.

Animals↗

PubMed1999

Analysis of 77,000 canine uroliths. Perspectives from the Minnesota Urolith Center.

Of the hundreds of minerals that are found in the earth, most canine uroliths are comprised of only six types: (1) magnesium ammonium phosphate, (2) calcium oxalate, (3) calcium phosphates, (4) ammonium urate and other salts or uric acid, (5) cystine, or (6) silica. Each type has characteristics that allow its identification. During the past two decades, the prevalence of calcium oxalate canine uroliths has dramatically increased, while struvite has decreased. The most effective treatment and prevention protocols are based on knowledge of the primary mineral type comprising the urolith.

Age Distribution↗

PubMed1999

Canine urate urolithiasis. Etiopathogenesis, diagnosis, and management.

Etiopathologic factors predisposing to urate lithogenesis in Dalmatian and non-Dalmatian dogs represent diverse pathologic and/or physiologic processes involving purine nucleotide and ammonia synthesis, biodegradation, and excretion. Predisposing factors for urate urolith formation include hyperuricemia, hyperammonemia, hyperuricosuria, hyperammonuria, aciduria, and genetic predisposition. Medical therapy of dogs forming urate uroliths should be directed at modifying these predisposing factors through dietary modification, administration of allopurinol, and/or surgical correction of portovascular anomalies if present. The precise mechanisms resulting in urate urolith formation in dogs have not been determined.

Animals↗

PubMed1999

Canine cystine urolithiasis. Cause, detection, treatment, and prevention.

Cystine uroliths are a sequela to cystinuria, an inherited renal tubular defect in reabsorption of cystine and some other amino acids. At the Minnesota Urolith Center, 67 breeds of dogs were identified, including English Bulldogs, Dachshunds, Mastiffs, and Newfoundlands. In some dogs, the severity of cystinuria may decline with advancing age. Current recommendations for dissolution of cystine uroliths include various combinations of diet modification, diuresis administration of 2-MPG, and alkalinization of urine.

Animals↗

PubMed1999

Voiding urohydropropulsion. Lessons from 5 years of experience.

Voiding urohydropropulsion is a nonsurgical method of removing uroliths from the urinary bladder. Any urocystolith of sufficient size to pass through the distended urethral lumen can be safely and effectively removed by this technique. Compared to cystotomy, voiding urohydropropulsion offers several advantages: urolith removal can be performed in minutes, anesthetic period is shorter, postprocedural dysuria and hematuria are less severe, and it provides greater success for complete removal of small urocystoliths. This technique is not suitable for removal of large urocystoliths or uroliths that become lodged in the urethral lumen.

Animals↗

PubMed1998

The effectiveness of taurine and levocarnitine in dogs with heart disease.

In this article, the current state of knowledge of the potential role of taurine and L-carnitine deficiency and supplementation in the genesis and management of cardiovascular disease in dogs is presented. There is limited direct evidence to support the recommendations found in this article or elsewhere in the literature. The temptation to "do something" for our patients can be overwhelming. Whether it be the administration of drugs or prescribing nutraceuticals or prescription diets, the veterinarian should strongly consider the source of the information, the strength of the evidence presented, the financial costs to the owner, and the potential risks and benefits to the patient.

Animals↗

PubMed1996

Medical management of iatrogenic rents in the wall of the feline urinary bladder.

Surgical closure may not be necessary to successfully manage all patients with ruptured urinary bladders. If the margins of the walls of tears in the bladder wall are not devitalized, and if they remain in close apposition via maintenance of the bladder lumen in a nondistended state for an appropriate period, these conditions may simulate those created by use of surgical sutures. This is not advocating an all-or-none choice. Because the clinical status of patients with ruptured urinary bladders can range from that characterized by only hematuria and dysuria to life-threatening postrenal uremia, a range of surgical and medical options should be considered.

Animals↗

PubMed1996

Diagnosis, medical treatment, and prognosis of feline urolithiasis.

Radiographic or ultrasonographic evaluation of the urinary tract is required to consistently detect feline uroliths. Evaluation of clinical, laboratory, and radiographic findings facilitate "guesstimation" of the mineral composition of uroliths. Therapy should not be initiated before appropriate samples have been collected for diagnosis. The objectives of medical management of uroliths are to arrest further growth and to promote urolith dissolution by correcting or controlling underlying abnormalities. For therapy to be effective, it must induce undersaturation of urine with calculogenic crystalloids by (1) increasing the solubility of crystalloids in urine, (2) increasing the volume of urine in which crystalloids are dissolved or suspended, and (3) reducing the quantity of calculogenic crystalloids in urine.

Animals↗

PubMed1991

Successful hyperlipemic pregnancy.

Women with hypertriglyceridemia are prone to gestational pancreatitis, a condition carrying substantial maternal and fetal risk. We describe a 33-year-old woman with familial hypertriglyceridemia who had recurrent hyperlipidemic abdominal crises during previous pregnancies despite dietary fat restrictions. A fifth pregnancy was carried to term without complications after aggressive dietary therapy and intermittent intravenous feeding, administered whenever her triglyceride levels exceeded an arbitrarily selected threshold concentration of 28 mmol/L. The efficacy of this approach may be explained by the published observation that low-fat (high-carbohydrate) isocaloric diets elevate serum triglyceride levels by the oral, but not the intravenous, route in normal individuals. Reduction of this patient's serum triglyceride concentrations by interrupting oral intake and administering intravenous glucose appeared to prevent late-pregnancy pancreatitis and culminated in uncomplicated full-term delivery.

Adult↗

PubMed1988

Variation in neuromuscular activity during prey capture by trophic specialists and generalists (Pisces: Labridae).

Members of the marine teleost family Labridae are among the most abundant and morphologically diverse fish on coral reefs. A quantitative analysis was conducted of the neuromuscular activity patterns controlling movement of the jaws during prey capture by 4 labrid species ranging from trophic specialists to trophic generalists. A total of more than 800 captures of 3 prey types was analyzed. All 4 species showed significant modulation of electromyographic parameters in response to different prey types. Significant variation was also found between replicate experiments on the same individuals. To obtain valid assessments of interspecific variability, statistical analyses must take into account this potentially high degree of intraspecific variability. By partitioning the variance in a nested analysis of variance, a lack of significant differences in electromyographic parameters between species became apparent. In contrast to the closely related Cichlidae, trophic diversification in the Labridae has not been accompanied by the acquisition of unique neuromuscular activity patterns for prey capture. The dramatic adaptive radiation that has occurred in these 2 families has involved different processes of evolutionary diversification. Neuromuscular stereotypy of labrids may be associated with the lack of structural flexibility in their 'coupled jaw'. Additional study is needed to establish the extent to which labrid radiation into various trophic niches is related to the evolution of specialized morphologies and foraging behaviors.

Animals↗

PubMedDate not supplied

Ultrasonic effects on Dacus dorsalis.

Larvae of Dacus dorsalis (Hendel), the oriental fruit fly, were exposed to cw ultrasound at frequencies of 43, 123 and 447 kHz, with eggs also exposed to 43 and 447 kHz. Mortality as a function of ultrasonic intensity and duration of exposure was determined. At 43 kHz, no eggs or larvae were found to survive 0.5 W/cm2 or 0.2 W/cm2, respectively. Also at higher frequencies the larvae were more sensitive to ultrasound than were the eggs. A dramatic increase of lethal intensity with frequency suggests cavitation as the mechanism by which mortality is induced.

Animals↗

PubMedDate not supplied

Evaluation of urinary carnitine and taurine excretion in 5 cystinuric dogs with carnitine and taurine deficiency.

Five client owned dogs with cystinuria were diagnosed with carnitine and taurine deficiency while participating in a clinical trial that used dietary management of their urolithiasis. Stored 24-hour urine samples collected from the cystinuric dogs before enrollment in the clinical diet trial were quantitatively evaluated for carnitine and taurine. These results were compared to those obtained from 18 healthy Beagles. Both groups of dogs were fed the same maintenance diet for a minimum of 2 weeks before 24-hour urine collection. The protocol used for 24-hour urine collections was the same for cystinuric dogs and healthy Beagles except that cystinuric dogs were catheterized at baseline, 8 hours, 12 hours, and at the end of the collection, whereas Beagles were catheterized at baseline, 8 hours, and at the end of the collection. Three of 5 dogs with cystinuria had increased renal excretion of carnitine. None of the cystinuric dogs had increased renal excretion of taurine, but cystinuric dogs excreted significantly less (P < .05) taurine in their urine than the healthy Beagles. Carnitinuria has not been recognized previously in either humans or dogs with cystinuria, and it may be 1 risk factor for developing carnitine deficiency. Cystinuric dogs in this study were not taurinuric; however, cystine is a precursor amino acid for taurine synthesis. Therefore, cystinuria may be 1 risk factor for developing taurine deficiency in dogs. We suggest that dogs with cystinuria be monitored for carnitine and taurine deficiency or supplemented with carnitine and taurine.

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