PubMed Health⌕ Search

Biomedical subjects

A Kirksey

Publications and source records attributed to A Kirksey.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effects of maternal dietary restriction in vitamin B-6 on neocortex development in rats: B-6 vitamer concentrations, volume and cell estimates.

Influence of the time of maternal restriction in dietary vitamin B-6 on vitamer concentrations and morphological development of neocortex was examined. Rats were fed ad libitum a vitamin B-6-free diet supplemented with 0.0 or 0.6 mg pyridoxine X hydrochloride (PN X HCl)/kg diet during gestation followed by a control diet (7.0 mg PN X HCl/kg) during lactation or were supplemented with 0.6 or 7.0 mg PN X HCl/kg diet throughout gestation and lactation. During postweaning offspring received the maternal diets fed during lactation. Neocortices of offspring were examined at 30 d of age by liquid chromatography and light microscopy. Vitamin restriction during gestation and 30 d postnatal was the only vitamin B-6-restricted treatment of the three administered that altered B-6 vitamer levels in neocortex; all vitamers were depressed equally. Brain weight and volume of neocortex were not changed significantly by the maternal restrictions imposed. However, each restriction adversely affected neurogenesis and neuron longevity of the neocortex and when expressed as percent reduction from control, neuron longevity was affected more severely than neurogenesis.

Animals↗
PubMed1986

Effects of vitamin B6 intake on nutriture and growth of young infants.

Vitamin B6 is critical to normal development; however, the requirement for adequate nutriture of the human infant is based on limited experimental data. In this study vitamin B6 intakes of breast-fed (BF) and formula-fed (FF), healthy, term infants were related to levels of pyridoxal phosphate (PLP) in their plasma at 1, 2, 4, and 6 mo of age. Mothers of BF infants were supplemented with either 2.5 or 15.0 mg pyridoxine . hydrochloride (PN . HCl)/d. Growth was similar for FF and BF infants and was within normal ranges over the 6 mo period. Plasma PLP in cord blood was similar in BF and FF infants; however, at 1-5 d of age and at each subsequent age studied, levels of plasma PLP were significantly higher in FF infants than in BF. Lowest PLP values were for BF infants of mothers who received 2.5 mg PN . HCl/d. Mean plasma PLP decreased with age and was not correlated to vitamin B6 intakes except at 1 mo of age. At this age, vitamin B6 intake of BF infants whose mothers received 2.5 mg PN . HCl/d was only 0.1 mg B6/d. The consequences of this are uncertain; however, plasma PLP levels of the infants were low and reflected their intakes of vitamin B6.

Body Height↗
PubMed1986

Evaluation of test-weighing for the assessment of milk volume intake of formula-fed infants and its application to breast-fed infants.

Test-weighing (TW) was evaluated in formula-fed (FF) infants by comparison with direct measurement (DM) of formula intake during a 24 h period at 1, 2, 4 and 6 mo of age. Formula intakes estimated by TW ranged from 87 to 93% of those determined by DM over the 6-mo period. During the study period the number of feedings per day decreased but were not significantly different for FF and BF infants. Volume of intake per feeding by FF infants increased significantly during the 6-mo period whereas milk intakes of BF infants were not different at the four ages studied. These data indicated that when the number of daily feedings decreased with age, FF infants increased their volume of intake per feeding whereas BF infants did not adjust their intakes. Mean volume of milk intake at 4 and 6 mo, estimated by TW, was significantly greater in FF infants compared to breast-fed (BF) infants matched for age and size. Data from this study indicated clearly that when milk intakes of BF infants are compared to those of FF infants, both groups of infants should be test-weighed.

Aging↗
PubMed1986

Changes in specific nutrients in breast milk during extended lactation.

An increasing trend towards breast-feeding infants beyond 6 mo of age has been observed in this country. The present study was designed to examine the effect of extended lactation on the concentrations of vitamins B6 and C, free and total folacin, calcium, zinc, and magnesium. Forty mothers were studied from 7 months of lactation until they stopped breast-feeding. Subjects were requested to collect milk samples monthly at a morning feeding between 7 AM and 10 AM. Between 7 and 25 mo of lactation, levels of zinc, calcium, vitamin B6, and vitamin C tended to decrease, whereas levels of free and total folacin remained unchanged. Magnesium levels decreased only after 18 mo of lactation. The decrease in concentrations of zinc and calcium paralleled the decrease in feeding frequency. Changes observed in this study on the composition of human milk may reflect physiological changes in the mammary gland during weaning.

Adult↗
PubMed1986

Fatty acid composition of mature human milk of Egyptian and American women.

Fatty acid composition of mature human milk of rural Egyptian and American women was determined by gas-liquid chromatography. Milk of Egyptian women contained significantly higher percentages of capric, lauric, myristic, linoleic and arachidonic acids, saturated fatty acids (SFA), and polyunsaturated fatty acids (PUFA). Conversely, milk of American women contained higher percentages of stearic and oleic acids, total unsaturated fatty acids, and monounsaturated fatty acids. The PUFA:SFA ratio in Egyptian samples was 0.54 +/- 0.18 compared to 0.47 +/- 0.22 in American samples. Increased percentages of medium-chain SFA in Egyptian milk suggested increased mammary gland lipid synthesis. Analysis of Egyptian diets indicated high-carbohydrate and low-fat intakes may have resulted in limited availability and incorporation of dietary fatty acids into milk triglycerides. Thus, increased percentages of medium-chain SFA observed in Egyptian milk may reflect mammary gland synthesis in an attempt to maintain lipid concentrations in milk.

Adult↗
PubMed1985

Effects of different levels of vitamin B-6 supplementation on vitamin B-6 concentrations in human milk and vitamin B-6 intakes of breastfed infants.

Vitamin B-6 has been reported to vary in concentration in human milk in response to changes in maternal intake of the vitamin. This study examined the effects of such changes on the breastfed infants' intake of vitamin B-6. Lactating mothers received 0, 2.5, 10.0 or 20.0 mg pyridoxine X HCl (PN X HCl) for 3 consecutive days in addition to dietary sources. Dietary intakes of vitamin B-6 (mean = 1.8 +/- 0.2 mg/day) were similar among the four groups. Vitamin B-6 was determined in milk samples from each feeding and milk intakes of infants were estimated by test-weighing. Nonsupplemented mothers had lower vitamin B-6 in their milk (93 +/- 8 micrograms/L) and vitamin B-6 intake of their infants was lower (0.06 +/- 0.01 mg/day) compared to other groups. Maternal supplementation with 2.5, 10.0 or 20.0 mg PN X HCl was paralleled by vitamin B-6 levels in milk of 192 +/- 16, 247 +/- 25 and 413 +/- 45 micrograms/L, respectively, and by vitamin B-6 intakes of breastfed infants of 0.12 +/- 0.02, 0.22 +/- 0.02 and 0.28 +/- 0.03 mg/day, respectively. When maternal intakes of vitamin B-6 approximated 20.0 mg/day, breastfed infants were unlikely to receive the current RDA of 0.3 mg vitamin B-6/day.

Adult↗
PubMed1985

Effect of storage time and temperature on folacin and vitamin C levels in term and preterm human milk.

A survey of infant feeding practices indicated that 40% of the mothers who breast-fed their infants frequently expressed and stored their milk in the home refrigerator/freezer prior to feeding. Effects of different lengths of storage time on the levels of folacin and vitamin C in both term (T) and preterm (PT) human milk were examined. Folacin and vitamin C intakes of most mothers were such that the levels of these vitamins in milk appeared to have reached saturation. Folacin levels in T and PT milk were similar but were lower in both after three months of freezer storage compared to one week of storage. Vitamin C content in PT milk was significantly higher than that in T milk and did not change after three months of freezer storage, whereas the vitamin C level in T milk decreased significantly. After 24 hr refrigeration of T milk, vitamin C content was lower but the folacin level was similar to that observed prior to refrigeration. The findings indicated that T or PT human milk, stored for 3 months in the freezer, would provide the recommended allowance of vitamin C but not of folacin for infants.

Ascorbic Acid↗
PubMed1985

Effects of different levels of vitamin C intake on the vitamin C concentration in human milk and the vitamin C intakes of breast-fed infants.

The influence of maternal intake of vitamin C on the vitamin C concentration in human milk and on the vitamin C intakes of breast-fed infants has not been demonstrated conclusively. This study examined these influences of diet and supplementation in 25 lactating women administered 90 mg of ascorbic acid for 1 day followed by 250, 500 or 1000 mg/day for 2 days or unsupplemented for 1 day followed by either 0 or 90 mg ascorbic acid supplement for 2 days. Vitamin C content in milk and urine was determined by the 2,4-dinitrophenylhydrazine method. Vitamin C intakes of infants were calculated from milk volume, as determined by the test-weighing method and from vitamin C levels in milk samples obtained at each feeding. Total maternal intakes of vitamin C, which exceeded 1000 mg/day or 10-fold the RDA for lactation (100 mg/day), did not significantly influence the vitamin C content in milk or the vitamin C intakes of infants. However, maternal vitamin C intake was positively correlated (r = 0.7) with maternal urinary excretion. These differences in milk and urine response to vitamin C intake suggest a regulatory mechanism for vitamin C levels in milk.

Adult↗
PubMed1985

Vitamin B6, vitamin C and folacin levels in milk from mothers of term and preterm infants during the neonatal period.

Studies of the composition of milk from mothers who deliver prematurely have focused primarily on macronutrients and trace elements while its vitamin composition has received little attention. This study focused on vitamin B6, vitamin C and folacin in preterm (PT) and term (T) milk which are critical to early growth and development. Fifteen PT and twelve T mothers were studied for five 24-h periods during the first month of lactation. Vitamin C levels were higher in PT milk during the first week of lactation whereas folacin levels were similar to T milk. Vitamin B6 levels in PT milk were lower than in T milk throughout the first month postpartum. These findings suggested that the use of PT milk as the sole source of these nutrients is open to question and that during the neonatal period PT infants need supplements of certain micronutrients.

Adult↗
PubMed1985

Analysis of B-6 vitamers in human milk by reverse-phase liquid chromatography.

A simple, accurate reverse-phase high performance liquid chromatography (RPLC) method was introduced for the analysis of B-6 vitamers in human milk. The assay consisted of a phosphate buffer (pH 2.9) delivered isocratically through 5 micron ODS column packing, followed by post-column bisulfite derivatization to enhance the detection of PLP (and to a minor extent PL). The vitamers were detected using a fluorescence spectromonitor. Sample run time was less than 30 min. The sensitivity of the method was such that PL, PN, and PLP were detectable to 30 pmol/ml milk and PM and PMP to 5 pmol/ml milk. Total vitamin B-6 content in milk analyzed by RPLC correlated well with the microbiological assay. B-6 vitamer distribution in human milk was similar to values obtained from two different ion-exchange HPLC systems. The RPLC procedure is simpler and faster than the HPLC systems and is suggested for future use in analysis of B-6 vitamer concentrations in human milk.

Biological Assay↗
PubMed1984

Effect of maternal vitamin B-6 restriction on pyridoxal phosphate concentrations in developing regions of the central nervous system in rats.

The effect of maternal vitamin B-6 deficiency on concentrations of pyridoxal phosphate (PLP) within four different regions of the central nervous system (CNS) of progeny, the corpus striatum (CS), hypothalamus (H), cerebellum (C), total brain and first cervical segment (C-1) of the spinal cord was determined at 7, 15, 21 and 50 days of age. PLP concentrations in each CNS region, as well as in total brain at 15, 21 and 50 days postnatally, paralleled the level of vitamin B-6 in the deficient (0.6, 0.8, 1.0 mg pyridoxine . HCl per kilogram diet) and control diets (7.0 mg pyridoxine . HCl per kilogram diet). By 21 days of age, PLP concentrations had essentially plateaued in CNS regions of controls, whereas in the vitamin B-6-restricted groups, a significant catch-up in concentration was observed between 21 and 50 days of age in all CNS regions except C-1 of the spinal cord. Throughout postnatal development, PLP concentrations in the C-1 region of spinal cord and in hypothalamus appeared least affected by vitamin B-6 restriction and levels in CS and C were most affected. These findings suggested that the mechanism for intracellular trapping of B-6 vitamers may develop in a caudal to rostral direction within the CNS.

Animal Nutritional Physiological Phenomena↗
PubMed1983

Effect of maternal vitamin B-6 deficiency on specific regions of developing rat brain: amino acid metabolism.

Amino acid metabolism may be adversely affected by vitamin B-6 deficiency. The effects of a maternal deficiency of vitamin B-6 on concentrations of amino acids in substantia nigra (SN), caudate nucleus/putamen (C/P) and cortex (CORT) in progeny were studied. Female albino rats were fed diets containing either 0.6 (deficient) or 7.0 (control) mg pyridoxine x HCl (PN x HCl) per kilogram diet ad libitum throughout growth, gestation and lactation. Paralleling a significant decrease in body weight, pups in the deficient groups began to show gross neurological symptoms of the deficiency at approximately 11 days of age. Analysis of brain regions at 15 days of age showed that the deficiency resulted in decreased concentrations of alanine and serine in SN, C/P and CORT. Often these changes were more pronounced in one or two of the regions analyzed. At 1 and 3 hours after an intraperitoneal injection of 100 mg PN x HCl per kilogram body weight into deficient pups, concentrations of cystathionine, leucine, isoleucine, valine, alanine and serine in brain regions remained similar to preinjection values. However, within 3 hours postinjection, glycine concentrations had decreased and were similar to control levels in SN and C/P.

Amino Acids↗
PubMed1983

Effects of maternal vitamin B-6 deficiency on specific regions of developing rat brain: the extrapyramidal motor system.

Progeny of rats deficient in vitamin B-6 exhibit gross neurological symptoms during a critical period of brain development, which may be related to abnormalities of the extrapyramidal motor system. In this study concentrations of the neurotransmitters, gamma-aminobutyric acid (GABA) and dopamine (DA) and certain amino acids were determined in substantia nigra (SN) and caudate/putamen (C/P) in progeny of dams fed diets containing either deficient (D), 0.6 or control (C), 7.0 mg pyridoxine x HCl (PN x HCl) per kilogram diet throughout growth, gestation and lactation. These measurements in C/P were correlated with the number of synapses. Analysis of brains of pups at 15 days of age, which gross neurological symptoms were evident in group D, showed that concentrations of GABA were decreased in C/P, whereas aspartate (Asp), glutamate (Glu) and DA were not affected compared to C values. One hour postinjection of PN x HCl, D pups showed decreased Glu in C/P and increased Asp in SN and at 3 hours postinjection, GABA was increased in SN. Since some synapses in C/P were postulated to be from GABAergic striatal interneurons, fewer of these synapses in conjunction with decreased GABA in C/P may result in ineffective inhibition of the circuitry of C/P in vitamin B-6 deficiency.

Amino Acids↗
PubMed1981

Effects of vitamin B-6 deficiency during lactation on the vitamin B-6 content of milk, liver and muscle of rats.

Effects of a dietary deficiency of vitamin B-6 imposed during the lactation period on the level of this vitamin in milk, liver and muscle were assessed in rats. A control diet (vitamin B-6 free basal diet supplemented with 10 mg pyridoxine . HCl/kg) was fed to all rats just before and during the gestation period. On day 1 of lactation, dams were randomly assigned to three dietary treatment groups: deficient (vitamin B-6 free basal diet), control or restricted control (control diet restricted in quantity to that consumed by the deficient group). Levels of total vitamin B-6 in milk, liver and muscle were determined by microbiological assay on days 1, 6, 16 and 21 of lactation. On day 6, the concentration of vitamin B-6 in milk of deficient dams was less than 20% of control or restricted control values. The low level of vitamin B-6 in milk of the deficient group continued to be evident on days 16 and 21 whereas in control and restricted control groups the vitamin content increased on days 16 and 21 compared to the values on day 6. In contrast to the low level of vitamin B-6 content observed in milk on day 6 in the deficient group, the vitamin content in liver of this group was approximately 75% of control or restricted control values, and the vitamin content in muscle was not significantly altered by the deficiency. Hence, milk was effected sooner by the deficiency and was an earlier indicator of impending vitamin B-6 deficiency than was liver or muscle tissues.

Animals↗
PubMed1981

Effects of vitamin B-6 deficiency on morphological changes in dendritic trees of Purkinje cells in developing cerebellum of rats.

The effect of maternal vitamin B-6 deficiency on the morphological changes in the dendritic growth of Purkinje cells of progeny was studied at four different ages (12, 15, 21, and 50 days) of postnatal development. By day 10, rat pups in the deficient groups (0.6 or 1.0 mg pyridoxine . HCl/kg diet) began to show gross neurological symptoms of the deficiency and before weaning approximately 12% of the pups in the 0.6 group had died. At each age studied, body weights were less and brain-body weight ratios were greater in the deficient groups compared to control (7.0 mg pyridoxine . HCl/kg diet) groups. Morphological changes of the Purkinje cell dendritic field, as determined from camera lucida drawings of Golgi-Cox impregnated cells of the mid-sagittal vermis, indicated significantly smaller width, height and area in the deficient groups compared to the control. Stereological measurements showed that dendritic branching density was significantly less in the 0.6 group compared with the 1.0 and 7.0 groups. The total length of Purkinje cell dendrites per cell was significantly reduced in the deficient groups compared to the 7.0 group. Qualitative analyses of photomicrographs of Purkinje cells indicated more dendritic and somatic aberrations in the deficient groups than in the control. Dendritic trees were larger in size and more complex in the 7.0 group compared to the deficient groups. The findings indicate that maternal vitamin B-6 deficiency interferes with normal development of the Purkinje cell dendrites.

Animals↗
PubMed1980

Effectiveness of enteral and parenteral nutrition in the nutritional management of children with Wilms' tumors.

The effectiveness of enteral and parenteral feeding in supporting a satisfactory nutrition status and/or reversing protein-energy malnutrition was evaluated in nine children, ages 1 to 7 years (eight female), with Wilms' tumors. At the onset of treatment, eight patients received comprehensive enteral nutrition (CEN) which included intense nutritional counseling and oral supplements while one received total parenteral nutrition (TPN). Despite CEN, the initial, intense treatment period was associated with a decreased energy intake (64 +/- 27% Recommended Dietary Allowances), dramatic weight loss (22 +/- 7% by 26 +/- 17 days from the beginning of treatment), decreased skinfold thickness (< 10th percentile), and decreased albumin concentrations (< 3.2 g/dl). Four of those who initially received CEN subsequently required TPN. A total of five patients received TPN for a mean of 31 days (range 11 to 60); kcal averaged 105 +/- 9% Recommended Dietary Allowances during weight gain. At onset of TPN, the mean albumin, transferrin, total lymphocyte count were 3.02 +/- 0.45 g/dl, 155 +/- 40 mg/dl, and, 655 +/- 437/mm3, respectively; all children had abnormal anthropometric measurements and anergy to recall skin test antigens. TPN for 28 or more days supported weight gain (+ 2.44 kg), increased serum albumin (+ 0.58 +/- 0.47 g/dl) and transferrin (+ 76 +/- 34 mg/dl), and reversed anergy despite low total lymphocyte counts. During maintenance treatment, nutritional status was maintained or restored with CEN in the group who responded. These preliminary data document the severity of protein-energy malnutrition which accompanies initial, intense treatment of children with Wilms' tumors, the nutritional and immunological benefits of TPN during continuing intense treatment and the effectiveness of CEN in maintaining a satisfactory nutritional status during maintenance treatment.

Body Height↗