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Biomedical subjects

P Succop

Publications and source records attributed to P Succop.

At least 37 records · Page 2Linked to original sources
PubMed1995

Effect of three levels of vitamin D intake in preterm infants receiving high mineral-containing milk.

Very low-birth weight (VLBW) infants fed high-calcium and high-phosphorus (10.74 and 6.93 mmol/MJ; 180 and 90 mg/100 kcal, respectively) infant formulas were randomized to one of three levels of vitamin D intake to approximate 200, 400, and 800 IU/day. Sixty-two infants completed the study (24 to 29 days), with actual mean daily vitamin D intakes of 161, 361, and 766 IU, respectively. Outcomes were not different by group: gains in body weight, length and head circumference, serum calcium, magnesium, phosphorus, alkaline phosphatase, osteocalcin, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and urine calcium:creatinine and magnesium:creatinine ratios. There were no radiographic fractures and/or rickets. A subset of 19 infants was followed between 173 and 380 days to determine descriptively if there was any delayed effect of earlier manipulation of vitamin D intake. They were fed standard infant formulas with a vitamin D content of 400 to 420 IU/L. No significant differences were present among the three groups, and data were combined. Serum 25-hydroxyvitamin D increased (p < 0.05), osteocalcin decreased (p < 0.05), and 1,25-dihydroxyvitamin D decreased (p = 0.06) at follow-up. Thus, for VLBZW infants fed high-calcium and high-phosphorus milk, an average daily vitamin D intake as low as 160 IU maintains normal and stable vitamin D status and normal physical growth, biochemical and hormonal indexes of bone mineral metabolism, and skeletal radiographs versus randomized infants receiving about 400 or 800 IU of vitamin D per day. On follow-up, vitamin D status remained normal for > or = 6 months while infants received < 400 IU of vitamin D per day.

Animals↗
PubMed1994

Clean-up of lead in household carpet and floor dust.

Methods to remove lead-containing dust were tested on carpets from homes of children with high blood lead and on new carpets artificially contaminated in the laboratory. The household carpets could not be cleaned effectively by repetitive vacuuming with HEPA-filtered cleaners. The lead concentration in the removed dust remained about the same from the initial cleaning (1 min/m2) to the final cleaning (total cleaning time of 10 min/m2). The lead loading on the surface of the carpets often increased during cleaning because vacuuming brought lead from deeper in the carpet to the surface. Over 95% of the total dust was removed from bare wooden floors by dry vacuuming (5 min/m2). For linoleum, more than 75% was removed by vacuuming for 5 min/m2. However, little was removed in vacuuming after the initial two minutes and about 20% was removed in a final wet-washing step. HEPA-vacuuming of the laboratory-contaminated carpets revealed that two of the commercially available vacuum cleaners tested were essentially equivalent and each removed significantly more dust than a third vacuum during a total cleaning time of 10 min/m2. Cleaning for 6 min/m2 was necessary to remove more than 70% of the embedded dust by the two more efficient vacuums. Cleaning efficiencies were about the same for short pile and sculptured carpets. It was concluded that it may be more practical to replace rather than clean carpets. HEPA-vacuum cleaning of carpets was shown to increase lead dust on the surface under some conditions.

Dust↗
PubMed1992

Sequential serum aluminum and urine aluminum: creatinine ratio and tissue aluminum loading in infants with fractures/rickets.

Aluminum toxicity is associated with the development of bone disorders, including fractures, osteopenia, and osteomalacia. Fifty-one infants with a mean (+/- SEM) birth weight of 1007 +/- 34 g, gestational age of 28.5 +/- 0.3 weeks, and serial radiographic documentation at 3, 6, 9, and 12 months for the presence (n = 16) or absence (n = 35) of fractures and/or rickets were studied at the same intervals to determine the serial changes in serum aluminum concentrations and urine aluminum-creatinine ratios. Autopsy bone samples were used to determine the presence of tissue aluminum. Serum aluminum concentrations from 46 infants were stable and similar between groups, with mean values between 15 and 22 micrograms/L. Urine aluminum-creatinine (micrograms per milligram) ratios from 14 infants were higher in infants with fractures and/or rickets (0.26 +/- 0.06 vs 0.12 +/- 0.04) at onset, and rate of decrease in aluminum-creatinine ratio was faster in infants without fractures and/or rickets. All but three infants were tolerating complete enteral feeding at all sampling points. One infant who received aluminum-containing antacid had marked increase in serum aluminum to 83 micrograms/L while urine aluminum-creatinine ratio increased from 0.09 to a peak of 8.53. Vertebrae from three infants at autopsy (full enteral feeding was tolerated for 37 and 41 days in two infants, respectively) showed aluminum deposition in the zone of provisional calcification and along the newly formed trabecula.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1991

Effect of work load and respirator wear on postural stability, heart rate, and perceived exertion.

The effects on postural stability (sway) were investigated for different work loads under conditions of wearing a full facepiece respirator and not wearing any respiratory protection device. Fifteen subjects accomplished light (40 W), moderate (85 W), and heavy (125 W) work loads under the two conditions. Measurements of postural sway were made immediately after each load by using a multicomponent, strain gage-type force platform. Changes in each subject's movement pattern of the center of pressure were quantitated and compared to their initial baseline sway tests. Each subject's heart rate and perceived exertion were also recorded during each condition. A statistically significant effect (p = 0.007) caused by work load was observed for total length of sway with or without a respirator. An interaction approaching statistical significance (p = 0.056) between work load and respirator use was found. This indicated that sway increased more quickly and in a more consistently linear fashion with increasing work load under the respirator condition (p = 0.02) compared to the nonrespirator condition. The results from the respirator condition showed linear increases in postural sway length across the entire range of work loads, but sway length in the nonrespirator condition showed an increase only at 125-W work loads. The greater increase in sway during the postural balance test could be attributable to the increasing work load-induced proprioceptive fatigue effect on the nervous system's ability to process signals from proprioception systems incongruent with body sway. The heart rate was significantly higher during respirator wear (an increase in heart rate averaging 5.62 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Sequential concentrations of copper and ceruloplasmin in serum from preterm infants with rickets and fractures.

Concentrations of copper (Cu) and ceruloplasmin in serum were measured serially in 49 preterm infants with mean (+/- SEM) birth weights of 979 +/- 33 g and gestational ages of 28.4 +/- 0.3 weeks at three, six, nine, and 12 months postpartum. Serial radiographic studies showed 17 infants with (group A) and 32 infants without (group B) rickets or fractures. Cu and ceruloplasmin concentrations in serum also were measured in 21 healthy term infants (group C) with birth weights 3668 +/- 98 g at three, six, and 12 months postpartum. Analyses of covariance of serial changes in these serum variables--taking into account such potential covariates as differences in gestational age, birth weight, initial weight and length, changes in weight and length during the study, the duration of parenteral nutrition, and increased enteral copper intake--showed both groups of preterm infants had significantly lower concentrations of Cu in serum up to age six months and ceruloplasmin up to age three months (P less than 0.001) when compared with term infants. By one year of age, Cu and ceruloplasmin concentrations in serum in all groups had increased significantly (P less than 0.001), into the adult range, and were not significantly different among groups. These data document a maturational lag in copper metabolism in small, preterm infants. Changes in concentrations of Cu and ceruloplasmin in serum were significantly correlated (r = 0.92, P less than 0.001) but were not significantly different between preterm infants with and without rickets or fractures at each age.

Aging↗
PubMed1990

Urinary hydroxyproline in infants with and without fractures/rickets.

Molar ratios of peptide-bound and free hydroxyproline:creatinine (OHPr:Cr) in urine were measured at 3, 6, 9, and 12 months of age in two groups of very-low-birthweight (VLBW less than or equal to 1500 g) infants. Group A (15 infants) had radiographically confirmed fractures and (or) rickets (F/R); Group B (17 infants) did not. The urinary peptide-bound OHPr:Cr ratio varied widely within groups and was greatest at three months in both groups: A = 0.81 +/- 0.45 and B = 0.55 +/- 0.32 (mean +/- SD). The ratio decreased with increasing postnatal age for each group but was not statistically different between groups throughout the study. The urinary free OHPr:Cr ratio also was greatest at age three months (A = 0.32 +/- 0.15 and B = 0.53 +/- 0.46), rapidly decreasing afterwards, and was not statistically different between groups throughout the study. We conclude that, in VLBW infants, bone turnover as indicated by the urinary peptide-bound OHPr:Cr ratio is highest during early infancy; however, the wide range of values for this ratio suggests that its use alone is not sufficient for detection of F/R in VLBW infants. The rapid decrease in free OHPr:Cr ratio is presumably related to the maturation of renal tubular function.

Body Height↗
PubMed1989

Serum alkaline phosphatase and serum zinc concentrations in preterm infants with rickets and fractures.

This study aimed to determine the longitudinal changes in serum zinc concentrations and the relationship between serum alkaline phosphatase (AP) activity and serum zinc concentrations in small preterm infants. The total serum AP and serum zinc concentrations were determined serially at 3, 6, 9, and 12 months in 72 infants with mean (+/- SEM) birth weights of 1000 +/- 29 g and gestational ages of 28.6 +/- 0.3 weeks. Twenty-four of 72 infants had radiographic evidence of rickets and/or fractures (R/F). In infants with R/F, group mean (+/- SEM) serum AP (371 +/- 42 U/L) and serum zinc (12.5 +/- 1.0 mumol/L) concentrations were significantly higher at 3 months compared with infants in the non-R/F group (193 +/- 12 U/L and 9.6 +/- 0.3 mumol/L, respectively). During the study, the serum AP concentrations decreased, and the serum zinc concentrations increased; both stabilized after 6 months. The serum AP concentrations were not related to the serum zinc concentrations. We speculate that in preterm infants, an increased bone turnover and a release of tissue (bone) zinc may contribute to the higher group mean serum AP and serum zinc concentrations at the time of diagnoses in infants with R/F compared with those infants without R/F.

Alkaline Phosphatase↗
PubMed1989

Serum vitamin D metabolites in very low birth weight infants with and without rickets and fractures.

Seventy-one very low birth weight (less than or equal to 1500 gm) infants were studied to determine the sequential changes in serum vitamin D metabolite concentrations between infants with and without radiographically documented rickets, fractures, or both (R/F). Usual intake of vitamin D included 20 IU/kg/day from parenteral nutrition or 400 IU/day supplementation with enteral feeding. Radiographs of both forearms and serum samples were obtained at 3, 6, 9, and 12 months. Twenty-two infants had R/F. At 3 months, significantly lower mean (+/- SEM) serum phosphorus levels (4.5 +/- 0.4 vs 6.1 +/- 0.2 mg/dl), higher 1,25-dihydroxyvitamin D (1,25-[OH]2D) concentrations (96 +/- 5 vs 77 +/- 4 pg/ml), and higher free 1,25-(OH)2D index (1,25-[OH]2D:vitamin D binding protein ratio; 5.2 +/- 0.3 x 10(5) vs 4.0 +/- 0.2 x 10(5] were found in the R/F group. These values returned to normal and were similar between groups on subsequent measurements. Serum calcium, magnesium, and 25-hydroxyvitamin D (25-OHD) concentrations were normal and similar between groups. In both groups, serum vitamin D binding concentrations increased initially but remained stable and normal beyond 6 months. We conclude that in very low birth weight infants with R/F, the vitamin D status (as indicated by serum 25-OHD concentrations) is normal, and that lowered serum phosphorus levels, higher serum 1,25-(OH)2D levels, and a higher free 1,25-(OH)2D index support the thesis that mineral deficiency (especially of phosphorus) may be important in the pathogenesis of R/F in small preterm infants.

Calcifediol↗
PubMed1989

Minimal vitamin D and high calcium and phosphorus needs of preterm infants receiving parenteral nutrition.

Preterm infants (birth weight, 1,089 +/- 91 g; gestational age, 28.9 +/- 0.7 weeks; mean +/- SEM) with mixed medical and surgical indications for parenteral nutrition (PN) were observed to determine the adequacy of infusates with fixed, low-dose vitamin D (25 IU/dl) and two combinations of calcium and phosphorus. The duration of low-dose vitamin D PN ranged from 5 to 52 days, with a median of 27 days. Twelve infants were randomly assigned to low (standard) Ca and P doses (5 mM each; 20 mg/dl of Ca and 15.5 mg/dl of P) and 13 high Ca and P doses (15 mM each; 60 mg/dl of Ca and 46.5 mg/dl of P). The maximum daily vitamin D intake was similar for both groups (31 +/- 1.3 versus 33 +/- 1.2 IU/kg). Vitamin D status in either group, as indicated by serum 25-hydroxyvitamin D (25-OHD) concentrations, was normal. There was no significant difference in observed changes of serial measurements of serum calcium, magnesium, phosphorus, alkaline phosphatase, creatinine (Cr), 25-OHD, and vitamin D-binding protein concentrations or urinary Ca:Cr and Mg:Cr ratios. In the low-dose Ca and P group, the serum P level was consistently less than 4 mg/dl in five infants, serum 1,25-dihydroxyvitamin D concentrations were higher, and tubular reabsorption of phosphorus was consistently greater than 95% and significantly higher than in the high-dose Ca and P groups. Severe bone demineralization apparent on X-ray occurred in two infants, with a fractured distal left ulna in one of the two infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium, Dietary↗
PubMed1988

Sequential bone mineral content in small preterm infants with and without fractures and rickets.

Seventy-four infants with birth weights 1009 +/- 28 grams and gestational age 28.6 +/- 0.3 weeks (M +/- SEM) were studied prospectively to test the hypotheses that bone mineral content (BMC) measured by photon absorptiometry, would be: (1) lower in very low birth weight (VLBW) infants with radiographic evidence of fractures and/or rickets (F/R), and (2) will continue to be lower over the first year when compared to VLBW infants without F/R. BMC and bone width (BW) of the distal one-third of left radius and ulna were measured at 5 weeks (n = 8), 14 weeks (n = 61), 26 weeks (n = 58), 40 weeks (n = 59), and 1 year (n = 52). Standardized radiographs of both forearms, and weight, length, and head circumference were also determined at each study age. Investigators and technicians involved in the photon absorptiometry measurements were unaware of the radiographic findings and vice versa. Twenty-three of 74 infants were found to have F/R. BMC of studied infants remained markedly below our previously determined range of "intrauterine bone mineralization," even at 26 weeks after birth. There was no significant difference in BMC or BW between infants with and without F/R, either at the time of confirmation of F/R or during early follow-up; however, BMC was lower at greater than or equal to 6 months and BW was lower at greater than or equal to 9 months in infants with F/R. We suggest that the extremely low BMC measurements in early infancy predispose all VLBW infants to fractures and rickets.

Birth Weight↗
PubMed1988

Urinary sodium excretion in young infants: role of gestational and postnatal ages.

Fractional urinary sodium excretion (FENa) and urinary sodium excretion (UNaE) were determined 88 times in 42 healthy, appropriate weight-for-gestational age infants. Gestational ages (GA) were 28-41 weeks; birthweights were 930-4135 g. Nineteen preterm infants were studied serially a total of 59 times between 1 and 55 days after birth. During the first 4 days after birth, multiple hierarchical regression analyses showed that FENa and UNaE were inversely related to GA (P less than 0.001). Postnatal age (PN) was not significantly related to FENa or UNaE. However the effect of GA on FENa and UNaE was not significantly greater than the effect due to postnatal age (PA) (P = 0.31 and P = 0.80, respectively). UNaE (1.6 +/- 0.2 mmol/kg per day) was significantly greater than sodium intake (1.1 +/- 0.2 mmol/kg per day) at 2.6 +/- 0.2 days (P less than 0.05). Longitudinal studies extending beyond 4 days indicated that GA and PA had interactive effects on FENa and UNaE; hence the contribution for a given GA was dependent on PA (and vice versa). Sodium intake remained stable (average 1.8 mmol/kg per day) beyond 7 days after birth and was consistently greater than UNAE (P less than 0.01). It is suggested that in healthy preterm infants beyond 2 weeks PA, a sodium intake of 2-3 mol/kg per day may be adequate to meet the renal sodium losses.

Aging↗
PubMed1986

Response to aluminum in parenteral nutrition during infancy.

The response to aluminum loading from parenteral nutrition (PN) solutions was determined in 20 infants with gestational ages 29 to 41 weeks and birth weights 880 to 3630 gm. Mean duration of PN was 43 days (range 5 to 175 days). Ten infants received a high Al load (from an experimental high calcium- and phosphorus-containing PN solution, with a measured Al content of 306 +/- 26 micrograms/L (mean +/- SE), n = 11), for up to 6 weeks. Ten infants received a lower Al load (from standard Ca-P solutions, measured Al content 144 +/- 16 micrograms/L, n = 11). Five infants received PN with a low Al load for longer than 6 weeks. The mean urine Al/creatinine (Cr) ratio (micrograms/mg) increased threefold, from 0.3 +/- 0.09 to 0.97 +/- 0.17 during PN in the entire group (P less than 0.001), and was significantly higher in infants who received greater Al loading (P less than 0.001). There was no significant difference between preterm and term infants in the rate of change in urine Al/Cr during the study. Urine Al was calculated to account for less than 50% of Al load. During the study, serum Al concentrations ranged from 6 to 318 micrograms/L (median 37 micrograms/L, compared with the median 18 micrograms/L for normal infants and children). Serum Al concentrations were not significantly changed during the study, or between infants in high or lower Al loading groups. Vertebrae from autopsy of two infants who received the lower Al containing PN for 71 and 152 days, respectively, stained positive for Al at the bone mineralization front. Thus, currently used PN solutions are contaminated with Al, urine Al concentration is higher with higher Al loading, and is not different in term and preterm infants. We suggest that renal elimination of Al in infants is incomplete, as assessed by lower urine Al excretion versus load, elevated serum Al concentration, and bone deposition of Al.

Aluminum↗
PubMed1985

Condition and type of housing as an indicator of potential environmental lead exposure and pediatric blood lead levels.

Environmental evaluations in a prospective behavioral study of children with blood lead levels up to about 50 micrograms/dl were performed by an intensive environmental survey and by exterior visual evaluation of housing quality. Serial blood lead values for infants in the study were compared to exterior housing type and quality, which itself was also compared with results of the intensive environmental evaluation. Five housing condition and type categories were defined: public housing; private housing (satisfactory, deteriorated, and dilapidated); and rehabilitated private housing. In this interim report on the first subset of available data, the housing categories were found to differ in paint and environment dust lead levels, with public and rehabilitated housing having lowest values. Blood lead concentrations of children differed across housing categories as early as 6 months of age, with children residing in public housing having lowest levels, followed by those in rehabilitated housing. The spread in mean blood lead concentrations among the housing quality categories increased with increasing age of the children. Housing category accounted for over one-half of the blood lead variability in 18-month-old children.

Dust↗
PubMed1985

The influence of social and environmental factors on dust lead, hand lead, and blood lead levels in young children.

The roles of environmental and behavioral factors in determining blood levels were studied in a cohort of young children living in an urban environment. The subjects were observed at 3-month intervals from birth to 24 months of age. Repeated measurements were made of the children's blood lead levels, environmental levels of lead in house dust, and in the dust found on the children's hands. A qualitative rating of the residence and of the socioeconomic status of the family was obtained. Interviews and direct observation of parent and child at home were used to evaluate various aspects of caretaker-child interactions. Data analysis consisted of a comparison of results obtained by simple correlational analysis, multiple regression analysis, and structural equations analysis. The results demonstrated that structural equation modeling offers a useful approach to unraveling the complex interactions present in the data set. In this preliminary analysis, the suspected relationship between the levels of lead in house dust and on hands and the blood lead level was clearly demonstrated. Furthermore, the analyses indicated an important interplay between environmental sources and social factors in the determination of hand lead and blood lead levels in very young children.

Child, Preschool↗
PubMed1985

Dose-effect and dose-response relationships of blood lead to erythrocytic protoporphyrin in young children.

Dose-effect and dose-response relationships were analyzed for blood lead concentration (PbB) vs blood protoporphyrin concentration using multiple data points from 165 children, ages 3-36 months. Protoporphyrin concentrations were measured using a front-face fluorometer designed to measure zinc protoporphyrin (ZPP) and an extraction method designed to measure total protoporphyrin as the free base (FEP). Estimations were made of the threshold for PbB effects on FEP and ZPP, as well as the slopes of the PbB-FEP and PbB-ZPP interactions. There was essentially no difference in thresholds estimated using ZPP vs FEP as the effect parameter. There was no apparent effect of age on threshold. However, the slope for PbB vs ZPP was less steep than the slope for PbB vs FEP. Moreover, the average ratio FEP:ZPP was markedly elevated at 3 months (1.84:1) and decreased slowly, attaining unity at 33 months. The possible reasons for this discrepancy are discussed, as well as the implications for interpretation of lead screening program data.

Aging↗
PubMed1984

Relationship between hematopoietic parameters and behavioral measures in lead-exposed rats.

The effects of low level lead (Pb) exposure on learning tasks in developing rats were investigated and the results correlated with individual hematopoietic indices. Pups received exposure via the dams milk; dams were exposed to either 0-, 545-, or 1090-ppm Pb during the lactation period. At Day 30 of age, half of the high Pb group was placed on distilled water; the remaining groups continued on the same exposure regimens as their dams. On Days 20, 30, and 90, blood samples for all rats were obtained via cardiac puncture. Each sample was analyzed for Pb concentration, free erythrocyte protoporphyrin (FEPs), hematocrit, and hemoglobin. Beginning at Day 90, all rats were tested on a battery of tasks designed to investigate the following questions: (1) to what degree lead exposure interferes with reversal learning; (2) whether changing of task requirements adversely affects acquisition of a new task; (3) to what extent task difficulty contributes to lead-induced deficits; and (4) whether lead exposure affects the capacity to retain information over short or long periods of time. The actual testing paradigms included spatial discrimination with reversal, visual discrimination with reversal, and visual discrimination task with delay. No significant differences were observed among any of the groups on any of the tasks. Correlation of individual learning scores with individual measures of hematopoietic function also failed to reach significance. These findings indicate that at low exposure levels, lead has little appreciable effect on learning and memory function as measured by these tasks.

Animals↗