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Biomedical subjects

R K Ringer

Publications and source records attributed to R K Ringer.

At least 37 records · Page 2Linked to original sources
PubMed1982

Feeding supplemental iodine to mink: reproductive and histopathologic effects.

Adult mink were fed various concentrations of supplemental iodine, ranging from 10 to 320 ppm, for 1 or 7 mo before breeding. Long-term, low-level (10-20 ppm) iodine supplementation was beneficial for both reproduction and lactation. Supplemental iodine in excess of 80 ppm, however, resulted in a reduction in the number of females that whelped, a decrease in litter size, and an increase in kit mortality. Thyroid glands of kits whelped and nursed by dams fed more than 20 ppm supplemental iodine, both short-term and long-term, showed hypertrophy marked by follicular cell hyperplasia and a decreased amount of colloid. Similar histopathologic lesions were observed in the thyroids of adults that received 80 ppm or more supplemental iodine; also observed were numerous lesions in the gallbladder.

Animal Feed↗
PubMed1982

Excretion and placental and mammary transfer of hexachlorobenzene in the European ferret (Mustela putorius furo).

Female European ferrets (Mustela putorius furo) absorbed 98.5% of a single dietary exposure of hexachlorobenzene (HCB). The HCB was found to readily cross the placenta and to be excreted in the milk of pregnant/lactating ferrets. After consuming HCB-treated feed, ferrets raising offspring excreted 50% of the initial dose by 32 d, while unbred ferrets achieved this same degree of HCB elimination in 41 d. The percentages of HCB excreted via the urine and feces were approximately 5 and 45%, respectively, in both groups at the 50% stage of elimination. Adipose tissue was the most significant long-term repository for HCB in the ferret. The other tissues analyzed for [14C]HCB showed a general relationship of increased radioactivity with increased fat content of the tissue. The ferrets with nursing kits were able to significantly reduce their body burden of HCB when compared to unbred females. The developing ferret kits were subjected to HCB insult both in utero and via dam's milk. The ratio of milk to placental exposure in the growing offspring was calculated to be 31:1. Thus, in addition to any toxic effects HCB may have on the adult reproducing population, the placental and mammary transfer of HCB constitutes a potential threat to the developing and growing animal.

Animals↗
PubMed1982

Effects of supplemental dietary copper on growth, reproductive performance and kit survival of standard dark mink and the acute toxicity of copper to mink.

Natural dark mink kit were fed a diet supplemented with 0, 25, 50, 100 or 200 ppm Cu from CuSO4 . 5H2O for 153 or 357 d. The shorter term Cu supplementation had no significant beneficial or adverse effects on mink body weight gains or hemoglobin or hematocrit concentrations, although plasma Cu concentrations were slightly elevated in the mink fed added Cu. Liver Cu concentrations were significantly increased only in the mink fed 200 ppm Cu. Liver Zn and Fe concentrations were not affected by the added Cu. Darker fur was observed in pelted males fed the higher levels of Cu. The reproductive performance of mink on the longer term Cu supplementation was not adversely affected, although greater kit mortality and reduced "litter mass" were a result of the higher Cu concentrations. The acute (21-d) ip LD50 concentrations of Cu sulfate and Cu acetate in adult mink were 7.5 and 5.0 mg/kg, respectively.

Animal Nutritional Physiological Phenomena↗
PubMed1981

Vascular response of the chicken hindlimb to vasoactive agents, asphyxia, and exercise.

Previous studies in live chickens have measured heart rate, blood pressure, and cardiac output during drug administration or asphyxia and made assumptions concerning the peripheral vasculature. The present study employs a constant-flow, isolated hindlimb perfusion technique to measure directly changes in skeletal muscle vascular resistance induced either by local intra-arterial (i.a.) bolus, or continuous i.a. infusion, of various vasoactive substances. Prostaglandin E1 (0.5 microgram, bolus) produced arteriolar vasodilation lasting 10 min, as indicated by a fall ian perfusion pressure. Bolus injection of histamine (10 microgram diphosphate) or adenosine (5 and 10 microgram) produced vasodilation of less than 2-min duration. Theophylline infusion (5 microM infused at 1 mL/min, i.a.) blocked the effect of adenosine. Norepinephrine (1 microgram) produced vasoconstriction which was reduced 60% by systemic alpha-adrenergic blockade with phenoxybenzamine (7.5-10 mg/kg). Tracheal occlusion produced intense vasoconstriction which was reduced 70% by alpha-adrenergic blockade. Electrical stimulation of the peripheral end of the cut sciatic nerve (6 Hz) produced an immediate vasodilation lasting several minutes.

Acetylcholine↗
PubMed1981

Vascular and hematologic effects of hemorrhage in the chicken.

Chickens have been reported to have a rate of posthemorrhagic fluid mobilization twice that of mammals and lack a phase of shock irreversible to transfusion. In the present study we measured several hemodynamic and hematologic parameters in chickens subjected to sustained hemorrhagic hypotension. Total peripheral resistance was unaffected or fell slightly and skeletal muscle vascular resistance judged from changes in gastrocnemius resistance was not affected by hemorrhage. Blood compositional changes included a progressive hyperkalemia, hyperglycemia, and hemodilution as evidenced by linear falls in hematocrit, hemoglobin, and plasma total protein concentration. Plasma sodium and osmolality were unchanged, as were arterial pH and oxygen tension; however, there was a fall in carbon dioxide tension. These studies demonstrate that fluid mobilization in the chicken after hemorrhage does not require an increase in precapillary resistance and suggest that, because the chicken does not exhibit intense precapillary constriction, it is spared some of the deleterious effects of inadequate tissue perfusion. Thus, the findings tend to incriminate the peripheral action of the sympathetic nervous system as a major contributor to the development of irreversibility in other species.

Acid-Base Equilibrium↗
PubMed1981

Aortic pulse-wave velocity in chickens and ducks.

Previous researches have indicated that birds possess an inelastic arterial tree with a high aortic pulse-wave velocity. The present study establishes the pressure-radius and pressure-volume relationships of thoracic and abdominal aortic segments of chickens and mallards. Each segment was affixed to rigid tubing such that the length could not change. The segment was filled with saline at constant flow by an infusion/withdrawal pump to an intraluminal pressure of 300 mm Hg. The pressure-volume curves for the thoracic segments were sigmoidal with greatest compliance in the physiological pressure range. The abdominal segments were less compliant than thoracic segments. Incremental pulse-wave velocities in the physiological pressure range, calculated from the pressure-volume curves, were similar to those of mammals, i.e., 6 to 10 m/sec. Turkey aortic pulse-wave velocities in the physiological pressure range were calculated from pressure-volume curves in the literature as 8 to 12 m/sec. Thus, the pulse-wave velocities of turkeys, chickens, and ducks are similar to mammals.

Animals↗
PubMed1980

Polychlorinated biphenyls (Aroclors 1016 and 1242): effects on survival and reproduction in mink and ferrets.

Diets that contained various levels of supplemental Aroclor 1242 or Aroclor 1016 were fed to mink and ferrets to investigate the chronic toxicity of these PCBs in two closely related species. In mink, Aroclor 1242 was found to be more toxic than comparable or higher levels of Aroclor 1016. The Aroclor 1242 diets caused complete reproductive failure at levels as low as five ppm of the diet. Aroclor 1016 impaired reproduction less than Aroclor 1242. Although fewer females whelped and the four-week kit weights were less than the control animals, no outward signs of abnormalities beyond their smaller size were found in the kits whelped and nursed by dams fed Aroclor 1016. Ferrets were more resistant to the effects of either PCB mixture than were the mink, as noted by the lower mortality rate on the Aroclor 1242 diet and the almost normal level of reproduction on the Aroclor 1016 diet. Feeding Aroclor 1242 at 20 ppm resulted in complete reproductive failure, but was not fatal to adult ferrets. This finding is in sharp contrast to the 100% mortality of adult mink fed the same level. Although the chlorine content is similar in both compounds, Aroclor 1242 has a higher percentage of molecules with five or more chlorines per biphenyl. This difference in higher substituted biphenyl isomer content and/or the reduced levels of contaminants in the Aroclor 1016 mixture may be of major importance in evaluating the toxicity of these compounds.

Animals↗
PubMed1979

Toxic effects of dietary polybrominated biphenyls on mink.

Serial levels of fireMaster FF-1, a commercial mixture of polybrominated biphenyls (PBB), and tissues from chickens and a cow that had previously consumed PBB were fed to mink to ascertain the chronic effects of the commercial and "metabolized" form of this compound on mink. Diets that contained 6.25 ppm (or more) PBB were lethal to adult mink within 10 months. One to 2.5 ppm dietary PBB fed for 9 months had an adverse effect on litter size, kit weight at birth, and kit survival. The data suggest that the PBB derived from contaminated beef and poultry was more toxic than the original PBB. The clinical signs of PBB poisoning in mink were food rejection, weight loss, and unthrifty appearance, and fatty infiltration of the liver. Based on these findings, mink must be considered highly susceptible to PBB toxicity. PBB residue levels 60 times the amount in the diet were found in the adipose tissue of the PBB-treated animals.

Animals↗
PubMed1978

PBB fed to immature chickens: its effect on organ weights and function and on the cardiovascular system.

In a series of polybrominated biphenyl (PBB) feeding trials in White Leghorn cockerel chicks, the effects of PBB on various physiological parameters and organ weights were determined. These measurements included: growth, thyroid function, ECG, cardiac output, blood pressure, hematocrit, erythropoietin levels, and spleen, bursa of Fabricius, thyroid, testes, comb, liver weights. In addition, tissues were histologically examined. PBB, in the commercial grade form of hexabromobiphenyl, was administered continuously in the diet at levels ranging from 50 to 250 ppm. Pair-feeding studies were conducted to ascertain the effects of the drug per se since preliminary trials indicated that PBB administration resulted in decreased feed intake. Chronic administration resulted in depressed body weight as a result of decreased feed intake; decreased comb, testes, spleen, and bursa weights; increased liver and thyroid weight; hydropericardium and ascites; decreased hematological values due to depressed plasma erythropietin levels; decreased heart rate, packed cell volume, hemoglobin and cardiac output; decreased voltage amplitude of the ECG and a shift in the mean electrical axis. No significant differences were found in blood pressure (mean arterial and pulse pressure), stroke volume, or respiratory rate.

Animal Feed↗
PubMed1978

PBB fed to adult female chickens: its effect on egg production, reproduction, viability of offspring, and residues in tissues and eggs.

Two experiments with light breed laying chickens fed polybrominated biphenyl (PBB) as FireMaster FF-1. The first involved feeding PBB at dietary levels of 0.2, 1, 5, 25, 125, 625, and 3125 ppm, the second involved levels of 30, 45, 60, 90, and 120. Each group had 24 hens, and each experiment had a control group of 24 hens. PBB diets were fed for 5 weeks. Feed intake, production, reproduction, tissue residues and viability of offspring were monitored during that time and a subsequent 8 weeks. Production, hatchability, and viability of offspring were significantly affected by feeding PBB at 45 ppm. Marked inanition occurred at levels of 625 and 3125 ppm, and there was some loss of feed intake at 125 ppm. There was a return to normal production and hatchability in 3 to 4 weeks after PBB withdrawal of diets with levels of 125 ppm or less. Dose--response lines are presented for PBB in muscle, liver, kidney, adipose tissue, and eggs. Withdrawal curves for PBB from these tissues are also given.

Animal Feed↗
PubMed1977

Current status of PCB toxicity to mink, and effect on their reproduction.

Experiments were conducted from 1968 to 1974 to investigate reproductive complications and mortality in mink fed Great Lakes coho salmon and to ascertain the effects of polychlorinated biphenyls (PCB's) on this fur bearer. The results of mink feeding trials indicated that coho salmon, as such, were not responsible for the loss of reproduction in the adult, or the kit mortality. Mink diets that contained other species of Great Lakes fish caused similar reproductive complications, but to a lesser degree. Rancidity, mercury poisoning and chlorinated hydrocarbon pesticide contamination of the fish were all discounted as being responsible for the problem. The clinical signs and lesions noted in mink that died while receiving diets that contained Lake Michigan coho salmon were very similar to those observed in mink fed on rations that contained supplemental PCB's. These included anorexia, blood stools, fatty liver, kidney degeneration, and hemorrhagic gastric ulcers. Analyses of tissues from mink that died when fed 30% Lake Michigan coho salmon or 30 ppm supplemental PCB diets showed similar PCB residues. PCB toxicity experiments revealed that mink are very sensitive to these compounds and that the lethal dose varied inversely with the chlorine content of the PCB's although only Aroclor 1254 exerted a detrimental effect on reproduction when fed at a low level (2 ppm) for 8 months. The reproductive failure encountered in feeding mink Lake Michigan coho salmon and Aroclor 1254 was shown to be of a non-permanent nature.

Animal Feed↗
PubMed1977

The biological effects of polybrominated biphenyls in avian species.

Polybrominated biphenyl (PBB), structurally similar to polychlorinated biphenyl (PCB), affects feed intake, egg production, and hatchability of fertile eggs in chickens and quail. Subcutaneous edema of the neck and shoulder are common abnormalities of hatched chicks from PBB-fed dams. No characteristic teratogenicity is evident. Offspring hatched are less viable during their first 3 weeks of life. PBB does not produce thinner egg shells or lower egg weights. The ratio of PBB egg content to dietary level is 1.3-1.5:1.0. The biological half-life of PBB in eggs is calculated to be 17 days. Tissue residues are higher in males than females because egg production is a major excretory route for PBB. Polybrominated biphenyl feeding causes tissue changes in size, structure and/or function in the liver, thyroid, testes, comb, heart, spleen, bursa of Fabricus, and blood. Liver enlargement, porphyria and microsomal enzyme induction results from PBB administration. The spleen, bursa and comb are reduced in size, whereas the thyroid increases after PBB feeding. A characteristic of PBB and PCB toxicity is hydropericardium and general edema.

Animals↗
PubMed1976

Toxicity and tissue residues from diphenylhydantoin fed to chickens.

Within three experiments with broiler-type crossbred chickens, diphenlyhydantoin (DPH) was administered via the diet at levels ranging from 10 to 2500 mg./kg. Feed intake and body weight gain were adversely affected by levels of 100 mg./kg. or higher. A hemorrhagic syndrome occurred in 16 percent of the chickens fed 100-1000 mg./kg. and 33 percent of those fed 2500 mg./kg. Twenty percent of the chickens fed 1000 mg./kg. were anemic; none of those receiving 250 mg./kg. were anemic. Other toxic manifestations included neurological side effects of a lethargic stupor, excitability to a disturbance, or a characteristic condition referred to as "head under." Pair-feeding experiments revealed thatlowered feed intake was not responsible for any of the clinical signs. All of the toxicity signs were reversible in 3 to 4 weeks following withdrawal of DPH. Muscle samples contained 2.5 to 11.4 mcg. DPH/g. at drug levels of 1000 and 2500 mg. DPH/kg. diet. Dose-response curves revealed that plasma, adipose, kidney and liver had levels which were, respectively, 1.05, 1.51, 2.19, and 2.85 times those of muscle.

Adipose Tissue↗
PubMed1976

Semen volume and sperm concentration in the ferret (Mustela putorius).

Semen was obtained from 40 of 62 attempted electro-ejaculations of nine anesthetized male ferrets. The ejaculations were performed using a bi-polar rectal electrode and an electrical stimulus of about 4 V and 0.35 mA applied for approximately 4 seconds and repeated at 10-second intervals. The mean number of stimuli required to obtain an ejaculation was 12.3. The spermatozoa concentration per mm3 ranged from 0.07 x 10(6) to 1.98 x 10(6) with a mean of 0.62 x 10(6). The mean number of spermatozoa per ejaculate was 16.35 x 10(6) and the mean volume of semen per ejaculate was 0.026 ml.

Animals↗