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Biomedical subjects

K C Hayes

Publications and source records attributed to K C Hayes.

At least 163 records · Page 9Linked to original sources
PubMed1980

Composition of plasma and nascent very low density lipoprotein from perfused livers of hypercholesterolemic squirrel monkeys.

The composition of circulating very low density lipoprotein (VLDL) was compared with the composition and secretion of nascent VLDL from perfused livers of squirrel monkeys that were fed unsaturated or saturated fat diets to elicit different degrees of plasma hypercholesterolemia. All squirrel monkeys studied had cholesteryl ester-rich plasma VLDL, although greater enrichment occurred in hypercholesterolemic animals fed saturated fat. Livers from hypercholesterolemic animals were capable of secreting VLDL particles enriched in cholesteryl ester, suggesting hepatic origin for a portion of this circulating lipid moiety. Total VLDL lipid, but not protein output by perfused livers of hypercholesterolemic monkeys, was greater than that by livers from hypocholesterolemic animals. These results indicate that saturated fat-induced hypercholesterolemia is associated with changes in the composition of hepatic VLDL in the squirrel monkey.

Animals↗
PubMed1980

Multi-electrode recording of Hoffman reflexes.

A multi-electrode system has been used to simultaneously record the H-reflex and M response from various locations on the gastrocnemius and soleus. With certain positions of the stimulating electrode in the popliteal fossa, large amplitude M responses were recorded in gastroenemius at a time when only low amplitude H-reflexes were recorded from soleus. These result not only reinforce the importance of casreful selection of the stimulation site but go further and suggest a definite need for the simultaneous monitoring of gastrocnemius and soleus responses to avoid contamination of the soleus H-reflex or its excitability cycle by the unwanted and unsuspected gastrocnemius M response. Conventional practice of recording an H-relfex and its excitability cycle from a single pair of bipolar electrodes located over soleus is susceptible to confounding from the unwanted M response by alterations in the initial mechanical conditions and by the various afferent discharges evoked by a preceding contraction in gastrocnemius.

Animals↗
PubMed1980

Growth depression in taurine-depleted infant monkeys.

In order to determine the effect of taurine depletion in primates, two species were selected which differed in their taurine conjugtion of bile acids. Consequently, eight cebus (taurine conjugators) and nine cynomolgus monkeys (glycine conjugators) were raised from birth with soybean infant milk formula lacking taurine. Half the monkeys received a 500 ppm taurine supplement. After 5 months the taurine concentration of plasma, urine and several tissues was greatly reduced in the unsupplemented monkeys. The least depletion occurred in retinal tissue of both species and in bile acids of cebus, whereas cynomolgus monkeys increased the glycine conjugation of their bile acids 125%. Taurine depletion was associated with a significant growth depression (16.8%) in the unsupplemented monkeys, but retinal degeneration was not observed. Neither species demonstrated an appreciable capacity to synthesize taurine as measured by cysteinesulfinic acid decarboxylase activity in liver and brain. The data suggest that dietary taurine is essential for maximum growth, as measured by weight gain, of infant nonhuman primates fed a soy protein milk formula.

Animals↗
PubMed1980

Effect of folic acid supplementation on pregnancy in the squirrel monkey (Saimiri sciureus).

Supplementation of squirrel monkeys with folic acid improved hematologic and folate status, maternal weight gain during pregnancy, and infant birth weight. Thus the folate content in the stock diet (1.4 microgram/g) did not meet the requirement for pregnancy. Low plasma vitamin B12 values suggest that vitamin B12 in the stock diet (22 ng/g) also was not adequate. Changes with folic acid supplementation are similar to those for human subjects, indicating that the squirrel monkey is an appropriate model for folic acid deficiency in pregnancy in man.

Animals↗
PubMed1980

Vital statistics from a laboratory breeding colony of squirrel monkeys (Saimiri sciureus).

An analysis of 512 pregnancies that occurred over a 9-year period in a laboratory colony of squirrel monkeys (Saimiri sciureus) revealed yeat-to-year variation in pregnancy outcome and birth weight. Although births occurred through the year, 72% were between May and August. Male infants outnumbered females 1.31:1 and were heavier at birth. Birth weight was an important determinant of infant survival. Maternal age did not affect birth weight in this sample. Dams present in the colony for long periods tended to deliver smaller infants with a decreased potential for survival. Reproductive causes contributed to 48% of the maternal deaths. Homorrhage at or near the time of delivery was the principle cause of maternal reproductive mortality. Most neonatal deaths were attributable to accident, prematurity or trauma.

Abortion, Veterinary↗
PubMed1979

Effects of H-reflex conditioning upon the contralateral alpha motoneuron pool.

H-reflex recovery curves have been elicited by subliminal conditioning stimuli applied to the ipsilateral and contralateral posterior tibial nerves in 10 healthy female subjects. In both types of recovery curve there was clear evidence of a period of facilitation in the ipsilateral soleus motoneuron pool 75-250 msec after the conditioning stimulus. These results indicate the bilateral nature of the facilitation and show it to be most probably produced by stimulus-evoked inputs as opposed to twitch-evoked inputs. If the facilitation is produced by descending long-loop reflex influences, then complementary evidence is provided for previous electromyographic data showing the bilaterality of long-loop reflexes evoked by percutaneous electrical stimulation. It is impossible, however, at the present time, to rule out the possible involvement of cutaneous afferent discharges or other stimulus evoked inputs in the late facilitation.

Adult↗
PubMed1979

Assessment of the H-reflex excitability curve using a cubic spline function.

A procedure for modeling H-reflex recovery curve data is described. The procedure involves fitting a cubic spline function to the recorded data points in such a way that the goodness of fit is determined by the standard error of the mean of each point. The cubic spline function possesses numerous advantages over other subjective and objective procedures for extracting information from the excitability curve.

H-Reflex↗
PubMed1979

Folacin deficiency and requirement in the squirrel monkey (Saimiri sciuresus).

Acute folacin deficiency was studied in eight young squirrel monkeys (Saimiri sciureus). Half of the animals were fed a semipurified deficient diet (no added folic acid) and half were fed a control diet (0.84 mg of added folic acid per kilogram of dry diet). Monkeys fed the deficient diet lost weight and suffered from diarrhea and dehydration leading to the death of one of the animals after 6 weeks. Folacin deficiency also was studied in six older animals fed diets containing varying levels of added folic acid. Monkeys fed diets containing 0.14 or 0.27 mg of added folic acid per kilogram of dry diet slowly developed alopecia, a scaly dermatitis, and a mild macrocytic anemia. When these animals were fed the deficient diet, they lost weight rapidly, the alopecia and dermatitis worsened, excretion of formiminoglutamic acid in the urine increased, and a severe megaloblastic anemia with profound intramedullary hemolysis developed. Deficient monkeys had low plasma and red blood cell folacin values but maintained normal plasma vitamin B12 values. Repletion of the animals fed the deficient diet with injections of folic acid reversed both the hematological and physical deterioration. The folacin requirement for maintenance of body weight in these animals was 28 micrograms of total folacin per kilogram of body weight per day. More than 75 micrograms of total folacin per kilogram of body weight/day may be needed to assure growth and normal hematological parameters and bone marrow cytology.

Animals↗
PubMed1979

Tapetum disorganization in taurine-depleted cats.

A severe disorganization of the lattice arrangement of tapetal rods occurs in cats nutritionally deprived of taurine. This is the first reported example of a nutritionally related degeneration of tapetal cells. The tapetal cell degeneration, along with the previously noted photoreceptor degeneration in taurine-depleted cats, suggests that taurine plays a vital role in maintaining the structural integrity of some biological structures. The visual evoked potentials were severely reduced in taurine-depleted cats as were the electroretinogram responses, as previously noted, indicating that they are deficient in light processing. These results also emphasize the importance of dietary taurine for the maintenance of normal structure and function of the eye, at least in the cat.

Animals↗
PubMed1978

Taurine deficiency in the kitten subcellular distribution of taurine and [35S]taurine in brain.

Taurine concentration decreases rapidly in the tissues and physiological fluids of kittens fed a diet of partially purified casein which lacks taurine. We have studied the subcellular distribution in cerebrum of taurine and [35S]taurine administered intravenously to these animals. The taurine concentration of all the fractions isolated from the cerebrum of taurine-deficient kittens was approximately sevenfold less than that observed in the fractions of cerebrum isolated from control kittens. The [35S]taurine was approximately twofold greater in all the brain fractions isolated from the taurine-deficient kittens compared with those isolated from the control kittens. The percent distributions of taurine and [35S]taurine in the fractions isolated from the cerebrum of control and deficient kittens were identical. Thus, in the face of a severe diet-induced deficiency of taurine in kitten brain, there appears to be no conservation of taurine by any particular subcellular pool of taurine. These studies provide no evidence for differences in compartmentation of taurine in cerebrum of taurine-deficient kittens compared with control kittens.

Animals↗
PubMed1978

Visualization of primate high density lipoproteins isolated by density gradient ultracentrifugation.

High density lipoproteins (HDL) isolated by density gradient ultracentrifugation from the plasma of monkeys ingesting semipurified diets are barely visible. This creates difficulty in separating HDL from other lower density lipoproteins following centrifugation and necessitates collecting lared quantities of background density solution to insure complete recovery of the HDL fraction. A simple procedure is described involving the addition of beta-carotene to nonhuman primate plasma prior to centrifugation which results in the delineation of HDL as a discrete yellow-orange band without affecting certain physical properties of HDL or interfering with standard lipid and protein assays.

Animals↗