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Biomedical subjects

B L Walker

Publications and source records attributed to B L Walker.

14 recordsLinked to original sources
PubMed1991

Soft tissue myofibroblastomas.

Five well-circumscribed solitary soft tissue tumors composed of myofibroblasts are described and termed myofibroblastomas. By light microscopy these lesions are characterized by short, intersecting, or crisscrossing fascicles of spindle cells, sometimes associated with foci of necrosis and/or mitotic activity with less than three mitoses per 10 high power fields. Myofibroblastomas show well-defined myofibroblastic differentiation ultrastructurally with peripheral myofilaments and vimentin, actin, and desmin immunocytochemistry positivity. The five tumors described occurred in patients of various age groups, including one congenital, and in a variety of soft tissue locations. It is important to recognize this benign soft tissue neoplasm to avoid confusion with other soft tissue tumors and to separate this lesion from other myofibromatosis. This study elucidates the spectrum of light microscopic, ultrastructural, and immunocytochemistry findings of soft tissue myofibroblastomas and establishes this soft tissue tumor as a specific clinico-pathologic entity.

Actins↗
PubMed1990

The fate of free autogenous fascial grafts in the rabbit.

Fascial grafts were taken from 34 New Zealand rabbits and implanted above and below the cranial periosteum in the same animal. They were placed as four-layered folded grafts and as single-layered grafts. When harvested from 6 to 14 months after transplantation, the multi-layered grafts and the single-layered grafts on bone had maintained their bulk but consisted histologically of only a retained collagen matrix with no viable cellular structure. The one-layered grafts on periosteum, however, retained their cellular make-up with normal vascularity and normal cellular structure when harvested at approximately the same intervals.

Animals↗
PubMed1979

Hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase response to litter size in suckling rats.

Rats were raised in litters of 3 or 14 from the 3rd postnatal day. Already, 2 days later on day 5, those raised in groups of three had elevated blood cholesterol and insulin levels and a very much lower hepatic 3-hydroxy-3-methyl-glutaryl-CoA (HMG) CoA) reductase activity, than the other group. When aged 40 days, hepatic HMG CoA reductase activity was higher in the group raised three rats per litter than in the large litter group.

Aging↗
PubMed1978

Effect of dietary vitamin C on adrenal cholesteryl ester content in the guinea pig.

Male guinea pigs fed a vitamin C-deficient diet for 3 weeks had lower concentrations of cholesteryl esters in their adrenals than did control animals fed the recommended intake of the vitamin. Not all esters were affected to the same degree, and the fatty acid profiles of the esters from control and deficient guinea pigs differed; there was proportionately more palmitic and linoleic acids and less docosatetraenoic acid [22:4 (n-6)] in the deficient guinea pig adrenal esters. [Fatty acids are designated as X:Y (n-Z), where X and Y are the numbers of carbon atoms and olefinic bonds in the acid and Z is the number of carbon atoms after the terminal olefinic bond.] A 100-fold excess of vitamin C in the diet also resulted in lower concentrations of adrenal cholesteryl esters than did the control diet, but they were not as low as in the deficient animals. Fatty acid profiles were similar for esters from control and excessively supplemented guinea pigs. Vitamin C deficiency apparently imposes a long term stress which results in a depletion of adrenal cholesteryl esters, possibly specific esters, to meet the requirements for glucocorticoid synthesis.

Adrenal Glands↗
PubMed1978

The circadian cycles of plasma corticosterone and adrenal cholesteryl esters in the normal and EFA-deficient female rat.

UNLABELLED: In female rats subjected to a 12 hr light-12 hr darkness schedule and fed a semipurified diet containing 10% corn oil, plasma corticosterone concentration showed a monophasic circadian cycle with minimum and maximum concentrations at the start of the light and dark periods, respectively. Adrenal total cholesteryl ester concentration was inversely related to plasma corticosterone, as were those of several of the individual esters; changes in cholesteryl ester concentration appeared to follow rather than precede changes in plasma corticosterone. There was preferential depletion of the cholesteryl esters of 18:1, 18:2omega6, and 20:4omega6 during glucocorticoid secretion. [ ABBREVIATIONS: EFA, essential fatty acid (s);X:YomegaZ, fatty acid with X carbon atoms and Y olefinic bonds with the terminal double bond Z carbon atoms from the methyl group.] In female rats fed hydrogenated coconut oil (EFA-deficient), a monophasic cycle for plasma corticosterone was also observed, but the peak was much broader than that recorded for rats fed corn oil, although minima and maxima occurred at similar times for the two groups. No significant cycle of adrenal total cholesteryl esters was evident in the deficient rats, but the 20:3omega9 and 22:3omega9 esters did decrease significantly during the period of high plasma corticosterone concentration. Preferential net decreases in adrenal cholesteryl esters during corticosteroidogenesis were more apparent in normal than in EFA-deficient rats.

Adrenal Glands↗
PubMed1978

The physical and neuromotor development of progeny of female rats fed graded levels of pyridoxine during lactation.

Female rats were maintained throughout gestation on a control diet containing 400% of the National Research Council (NRC) recommendation for pyridoxine and transferred to purified diets containing 400, 100, 75, 50, 25, or 0% of the NRC recommendations for B6 during lactation. Physical development of the offspring was assessed by measuring body weight and the occurrence of physical features, for example: eye opening, eruption of incisors, and growth of the hair to obscure the genitalia. Development of reflex reactions, neuromotor skills and coordination were also observed. Grooming was assessed as a measure of spontaneous activity. Retardation of growth, delay in the onset of reflexes such as palmar grasp, vibrissa placing, visual placing, and audicular startle, and a delay in the onset of advanced neuromotor coordination such as standing and grooming were observed in the pups of pyridoxine-restricted dams. Even progeny of dams, receiving 100% of the NRC recommendations of B6 during lactation exhibited inferior performance of skills requiring advanced neuromotor coordination such as standing, either supported or alone. These animals had weight gains comparable to neonates of maternal animals receiving 400% of the NRC recommendations for pyridoxine. The importance of factors other than growth in the assessment of nutritional requirements is demonstrated.

Animals↗
PubMed1978

Physical and neuromotor development of progeny of pyridoxine-restricted rats cross-fostered with control or isonutritional dams.

Female rats were fed diets containing graded levels of pyridoxine throughout gestation. At parturition, the pups were cross-fostered with a dam which had been fed the same diet as the biological mother throughout gestation (an isonutritional foster mother), or with one which had received a control diet containing 400% of the National Research Council recommendations for B6 throughout gestation (a control foster mother), or were left to suckle the biological mother. Physical, neuromotor, and reflexological development of the pups was assessed throughout the 3 week lactation period. There were no significant differences between pups nursed by their biological mothers and by isonutritional foster mothers. Growth, reflex acquisition, and neuromotor activities were impaired in pups subjected to pyridoxine restriction during gestation. Acquisition of a number of reflexes and time spent in neuromotor activities were responsive to cross-fostering with a control foster mother but the deficits were not completely eliminated. Growth was only slightly affected by cross-fostering and acquisition of audicular startle and negative geotaxis was not affected by the nature of the foster mother. The latter reflexes are apparently determined directly by the gestational nutrition of the fetus whereas other reflexes and neuromotor activities are influenced by long-term effects of pyridoxine restriction on the postnatal performance of the dam as a mother, in addition to being directly influenced by maternal diet during gestation.

Animals↗
PubMed1978

Cholesteryl ester depletion from the ovaries of superovulated female rats fed a normal or essential fatty acid deficient diet.

The cholesteryl ester content of the ovaries was determined in rats diets containing corn oil or hydrogenated coconut oil (essential fatty acid (EFA) deficient) and subjected to superovulation by injection of luteinizing hormone and follicle-stimulating hormone. Superovulation increased ovarian weight; the effect was greater in animals fed corn oil. Superovulation significantly decreased total ovarian cholesteryl ester concentration in animals fed corn oil, with disproportionately large decreases occurring in the esters of 20:1, 20:2, 22:5w6, and 22:6w3. Significant decreases were observed in these esters when the data were expressed on a unit mass of tissue basis or in relation to total ovarian mass. In superovulated, EFA-deficient rats, esters of 18:1, 20:1, 22:5w6, and 22:6w3 were significantly lower per unit mass of tissue but this was due, in all cases except that of 22:6w3, to the increased mass of ovarian tissue; there was no decrease in total esters per ovary weight during superovulation of deficient rats. The pattern and degree of selective changes in ovarian cholesteryl esters during superovulation were different from those previously reported for adrenal esters of stressed rats.

Animals↗
PubMed1976

Cardiopathogenicity of rapeseed oils and oil blends differing in erucic, linoleic, and linolenic acid content.

Male Wistar rats were fed semipurifed diets containing 20% fat for 25 weeks. Ten different oils or oil blends were employed, including rapessed oils, simulated rapeseed-type oils, and modified rapeseed-type oils. Safflower, soybean, and hydrogenated coconut oils served as control oils. Histopathological examination of the cardiac tissue was conducted at the end of the study and an incidenceseverity rating assigned to the lesions induced by each fat. Oils containing high levels of erucic acid (26-30%) induced the most severe cardiac necrosis, irrespective of the source of erucic acid (rapeseed oil or nasturtium oil). Increasing the linoleic: :linolenic acid ratio of the high erucic oils to that of soybean oil failed to reduce necrosis, but the absence of linolenic acid from a high erucic acid oil blend resulted in a markedly reduced lesion incidenceseverity rating, comparable to those obtained for low erucic acid rapessed oil and soybean oil which were similar. Lowest lesion incidence was obtained with safflower oil and hydrogenated coconut oil. We have postulated that linolenic acid plays a role in the etiology of cardiac necrosis observed when rats are fed diets containing low erucic acid rapeseed oils.

Animals↗
PubMed1976

A possible essential role for dietary linolenic acid in the development of the young rat.

Female rats were fed semi-purified diets containing 10% safflower oil or 10% soybean oil for six weeks prior to mating and through-out pregnancy and lactation. The progeny were weaned to the diet of the dam. Physical, neuromotor and reflex development was monitored in the progeny prior to weaning and learning ability of the mature progeny was assessed in a simple Y-maze test. Brain lipid analyses were conducted in the progeny at birth, 21 and 210 days of age. Inclusion of soybean oil in the diet resulted in higher levels of 22:6omega3 and lower levels of 22:5omega6 in the brain ethanolamine glycerophosphatides. The nature of the dietary fat exerted no effect on the physical development, onset of reflexologic responses or onset of neuromotor co-ordination in the pups. The soybean oil-fed animals spent more time in certain neuromotor activities possibly associated with explorative drive than did their safflower oil-fed counterparts. The performance of the mature soybean oil-fed progeny in the discrimination-learning test was superior to that of progeny fed safflower oil. The association of superior learning capacity with dietary soybean oil-induced incorporation of omega3 fatty acids into the brain glycerophosphatides is offered as support for an essential role for dietary linolenic acid for the young rat.

Animals↗