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Biomedical subjects

D J Ford

Publications and source records attributed to D J Ford.

36 records · Page 2Linked to original sources
PubMed1984

Differential peripheral nerve block by local anesthetics in the cat.

Controversy still surrounds the differential susceptibility of nerve fibers to local anesthetic conduction block. In order to help resolve this controversy, we developed an in vivo model of peripheral nerve blockade in the cat that closely reproduced the clinical state. Using this model, differential rate of nerve blockade of A-alpha, A-delta, and C fibers by 2-chloroprocaine, lidocaine, bupivacaine, and etidocaine was observed and quantitated. C fibers were blocked first by 2-chloroprocaine, lidocaine and bupivacaine. Etidocaine blocked A-delta fibers first. A-alpha fibers always were blocked last. Of the four local anesthetics tested, 2-chloroprocaine produced the greatest differential rate of block of the nerve fibers, and etidocaine produced the least.

Action Potentials↗
PubMed1984

Effects of hypersensitivity to a halothane metabolite on halothane-induced liver damage.

The effect of immunologic hypersensitivity to a metabolite of halothane (trifluoroacetate) on the halothane-hypoxia-induction model was tested in mice and rats. Male Fisher 344 rats (200 g) were immunized with ovalbumin-trifluoroacetate (OVA-TFA) and the time course of the delayed hypersensitivity response determined. The animals had a peak response between 4 and 6 weeks after immunization. Rats were immunized with OVA-TFA, OVA, or saline 5 weeks before being anesthetized. Ten days before anesthesia, the animals were started on 0.1% phenobarbital in the drinking water. The animals were anesthetized with 1% halothane and 14% oxygen for 2 h. Hypersensitivity to TFA had no effect on the liver damage in either the mouse or the rat. These results do not rule out an immunologic vector in halothane hepatitis but make the involvement of TFA unlikely.

Animals↗
PubMed1984

Comparison of insulated and uninsulated needles for locating peripheral nerves with a peripheral nerve stimulator.

This study was designed to compare the use of insulated and uninsulated needles with a peripheral nerve stimulator for locating a peripheral nerve in an anesthetized cat. The needles were mounted on a one-dimensional manipulator and both the saphenous and sciatic nerves were located. The tip of the insulated needle was consistently placed on the sciatic nerve. The tip of the uninsulated needle was placed 0.1-0.9 cm past the sciatic nerve. Injecting saline to assess the position of the tip of the needle relative to the sciatic nerve did not detect the needle being past the nerve. With the saphenous nerve preparation, both the needle and nerve were visible through the tissue. Using an insulated needle, the minimum current required to stimulate the nerve occurred when the tip of the needle touched the saphenous nerve. Using an uninsulated needle, the minimum current occurred when the tip was 0.1-0.8 cm past the nerve. The conclusion is that insulated needles more precisely locate the peripheral nerve than uninsulated needles.

Animals↗
PubMed1984

Duration and toxicity of bupivacaine for topical anesthesia of the airway in the cat.

To assess bupivacaine as a topical anesthetic of the airway, 0.5 ml of 1, 2, and 4% bupivacaine was sprayed down the trachea of lightly anesthetized cats and the duration of anesthesia, systemic toxicity, and local toxicity was compared to that produced by 4% lidocaine. Two percent bupivacaine suppressed the cough reflex longer than 4% lidocaine with no increase in either local or systemic toxicity. Four percent bupivacaine produced arrhythmias in 5 of 10 cats in two groups and apnea in 4 of 6 cats. This study indicates that 2% would be an appropriate concentration to assess bupivacaine as a topical anesthetic of the airway in humans.

Anesthesia, Local↗
PubMed1983

The effect on rats of practical diets containing different protein and energy levels.

Rats of 3 strains were fed diets of natural ingredients in 4 different laboratories. The diets contained different levels of protein and energy within ranges comparable to those found in existing laboratory diets. Energy level over the range examined appeared to exert greatest influence on bodyweight gain, but had no effect on food intake. The diet with the highest amino acid content was consumed in smaller amounts than the other diets. Food utilization was less efficient in the lower energy diets. Fat deposition was reduced in animals fed the lowest energy diet. It is concluded that energy level of the diet exerts an effect on the rate of bodyweight gain in rats, but that for longer-term studies a reduced energy level may be beneficial by leading to smaller fat deposits with consequent increase in longevity.

Animal Feed↗
PubMed1983

The effect on mice of practical diets containing different protein and energy levels.

Mice of 2 strains were fed diets of natural ingredients in 3 different laboratories. The diets, which were fed before and after pelleting, contained levels of protein and energy within the ranges comparable to those found in existing laboratory diets and were the same formulation as those fed to rats in a previous paper. The diet with the lowest energy level supported the lowest rate of bodyweight gain, as it had with rats. Little effect was noticed on food consumption, conversion efficiency or water intake. Animals fed the pelleted diets gained bodyweight faster and there were indications of greater food and water consumption and also food conversion efficiency. It was concluded that food intake was improved with the pelleted diets resulting in the other increases.

Animal Feed↗
PubMed1983

Pilot study on disposition and pain relief after i.m. administration of meperidine during the day or night.

Two groups (four patients each) of sickle cell anemia patients with severe pain were studied. One group comprised patients admitted to emergency unit in the morning (5:40 to 9:15) and the other patients admitted in the evening (18:53 to 22:50). All patients received intramuscular meperidine (1.5 mg/kg). Pain intensity and pain relief were followed for 4 h; blood samples were taken up to 6 h after drug administration. Significant differences in drug disposition were found between the day and night groups, as the elimination half-life was 46% shorter during the night and the total serum clearance was 70% greater during the night. Whereas a positive correlation was found between drug concentration and pain relief for the day group, no such correlation was found for th night group. Even though peak concentrations were higher during the night, analgesia was lower. This pilot study suggests that much higher meperidine doses might be required during the night to achieve equieffective analgesia.

Adult↗
PubMed1979

Immunological properties of peptic fragments of bovine serum albumin.

The effect of peptic degradation on the immunological and antigenic properties of bovine serum albumin (BSA) was investigated. Molecular fragments obtained after various times of digestion (3-360 min) were studied. Enzymatic digestion resulted in a rapid loss of serologically defined antigenic determinants. The immunogenicity of the fragments as measured by the level of reaginic and total anti-BSA antibody response in BDF1 mice was also diminished. Pre-treatment of mice with fragments exhibiting a low density of B-cell interacting determinants before immunization with BSA, resulted in significant suppression of both the primary and secondary antibody response. The most effective immunosuppressive fragments were obtained following removal of peptides which bound to anti-BSA antibodies. The suppression was shown to be antigen specific. It was concluded that separate determinants on the BSA molecule were responsible for the immunogenic and suppressive properties of the antigen.

Animals↗
PubMed1978

Composition of the milk of the common marmoset (Callithrix jacchus) and milk substitutes used in hand-rearing programmes, with special reference to fatty acids.

Analyses of marmoset (Callithrix jacchus) milk were carried out to determine values for crude protein, lactose, total lipids, major minerals, and osmotic pressure. Mean values were (g/100 ml): protein, 3.6; lactose, 7.5; total lipids, 7.7; minerals (mg/100 ml): sodium, 21.4; potassium, 54.3; calcium, 92.2; phosphorus, 22.8; magnesium, 5.0; chloride, 52.2; osmotic pressure, 354 mosm/kg water. Similar analyses were conducted on 2 milk substitutes used in hand-rearing programmes. Fatty acid analyses were carried out on natural milk, the milk substitutes, and the marmoset diet. For hand-rearing C. jacchus it is recommended that a human milk substitute is modified by increasing the levels of protein, carbohydrate, and total lipids, and that a small amount of fish oil is added.

Animal Feed↗
PubMed1977

Influence of diet pellet hardness and particle size on food utilization by mice, rats and hamsters.

Increasing hardness of diet pellets reduced food wastage by each species. Also, less wastage occurred when pellets made from finely ground materials were given, an effect that was not related to hardness. The hardest diet reduced growth of the mice by reducing true food consumption and a poorer food conversion efficiency (true food consumption/growth) was obtained. Apparent food consumption increased with the softness of the diet and food utilization (apparent food consumption/growth) of the softest diets was less efficient than those of the others. Grinding of the raw materials prior to pelleting had no effect on food conversion, but food utilization was less efficient because of the greater wastage of pellets from coarsely ground materials and consequent apparent food comsumption.

Animal Feed↗
PubMed1977

Effect of autoclaving and physical structure of diets on their utilization by mice.

A pelleted and 2 expanded rodent diets were autoclaved at 121 degrees C for 20 minutes, and fed to DBA/1 and LACA strains of mice. Reproduction was not significantly different on any diet and autoclaving had no effect other than increasing the intervals between litters. However, apparent food consumption was greater and efficiency of food utilization (expressed as young weaned/diet consumed) was poorer in mice fed pelleted diets. Diet had no significant effect on growth, but food wastage and consequently apparent food consumption were less and food utilization more efficient when expanded diets were fed. In addition, true food consumption was lower and food conversion more efficient. Autoclaving had little effect on expanded diets but caused a significant reduction in wastage and in apparent and true consumption of the pelleted diet, perhaps because of increased hardness.

Animal Feed↗
PubMed1976

The effect of methods of sterilization on the nutritive value of protein in a commercial rat diet.

1. The effect on protein quality of treating a commercial rat diet by autoclaving at various temperatures for different periods of time, or by irradiation with 2-5 or 10 Mrd, was studied. True digestibility (TD) and biological value (BV) were measured and the available and total amino acids in the diets were estimated using microbiological and chemical methods. 2. Autoclaving at 121 degrees for 60 min reduced BV, TD and net protein utilization (NPU) more than autoclaving at 134 degrees for 3 min. Availability of amino acids was reduced by both treatments but to a greater extent by autoclaving at 121 degrees for 60 min. Total amino acids were essentially unaffected. Irradiation had no effect on BV, TD, NPU or total amino acids, and the availability of amino acids was also unaffected, with the exception of lysine which was slightly reduced. 3. When the diet was autoclaved at 115 or 121 degrees for 15, 30 or 60 min, or at 134 degrees for 3 min the availability of the amino acids was reduced with increasing time and temperature of treatment. Treatment at 134 degrees for 3 min had an effect on available amino acids similar to treatment at 121 degrees for 15 or 30 min. 4. Ethylene oxide fumigation of the diet caused reduced availability of histidine, methionine and tryptophan but had negligble effect on arginine, leucine and lysine. 5. It is concluded that from a practical point of view irradiation causes least damage to proteins in rodent diets. If such diets are to be autoclaved they should be supplemented with complete protein to counteract amino acid destruction.

Amino Acids↗