Biomedical subjects

P Hackl

Publications and source records attributed to P Hackl.

15 recordsLinked to original sources

PubMed1997

Urinary excretion of pyridinium crosslinks and N-terminal crosslinked peptide in preterm and term infants.

Urinary excretion of pyridinium crosslinks of collagen, pyridinoline, deoxypyridinoline, and N-terminal crosslinked peptide are now widely used as biochemical markers of bone resorption. In the present cross-sectional study we measured the urinary excretion of total pyridinoline and total deoxypyridinoline by HPLC and N-terminal crosslinked peptide by ELISA in 43 preterm and term newborns in the first 2 months of life. The infants had no history of endocrine or metabolic diseases, bone, chronic heart, or pulmonary diseases. The results were compared by parametric covariance analysis, the HPLC and ELISA results by the Bland-Altman plot. Preterm infants had a statistically higher level of pyridinium crosslinks and N-terminal crosslinked peptide in urine (P < 0.05) than term infants. The very low birthweight infants (gestational age 26-32 weeks) had the highest levels of pyridinoline, deoxypyridinoline and N-terminal crosslinked peptide. Levels of both pyridinium crosslinks and N-terminal crosslinked peptide were independent of sex (P > 0.05). The Bland-Altman plot showed a good agreement between the levels of pyridinium crosslinks and N-terminal crosslinked peptide. Measurement of pyridinium crosslinks and N-terminal crosslinked peptide excretion in small infants gives information about skeletal growth and individual bone turnover, which is dependent on gestational age and birthweight. HPLC and ELISA are reliable methods for the measurement of pyridinium crosslinks and N-terminal crosslinked peptide, respectively.

Biomarkers↗

PubMed1997

Effects of soap and detergents on skin surface pH, stratum corneum hydration and fat content in infants.

BACKGROUND: In adults the influence of cleansing preparations on the pH, fat content and hydration of the skin is well documented. Studies in newborn and small infants have not been reported. OBJECTIVE: Our study aimed at examining whether similar effects can be ascertained in infants. METHODS: Infants without skin disease, aged 2 weeks to 16 months, entered an open, controlled and randomized study. Ten infants each had skin washed with tap water (control group), liquid detergent (pH 5.5), compact detergent (pH 5.5) or alkaline soap (pH 9.5). The pH, fat content and hydration were measured before and 10 min after cleansing. Findings were statistically evaluated by parametric covariance analysis. RESULTS: The skin pH increased from an average of 6.60 after cleansing in all groups. The smallest increase (+0.19) was observed in the control group, the largest (+0.45) after washing with alkaline soap. After treatment with liquid or compact detergent, the increase of the pH was only 0.09 higher than for the control group. In comparison to the compact and liquid detergents, the alkaline soap group had a significantly higher increase in pH. The fat content (mean starting value: 4.34 micrograms/cm2) decreased after washing in all groups; the smallest effect was observed in the control group (decrease of 0.93 micrograms/cm2), the highest for the alkaline soap group (decrease of 4.81 micrograms/cm2). In comparison to the compact and liquid detergents, the alkaline soap group had a higher decrease in fat content. This difference was significant for compact detergents. No statistically significant differences were observed for hydration before versus after washing. CONCLUSION: Each cleansing agent, even normal tap water, influences the skin surface. The increase of the skin pH irritates the physiological protective 'acid mantle', changes the composition of the cutaneous bacterial flora and the activity of enzymes in the upper epidermis, which have an acid pH optimum. The dissolution of fat from the skin surface may influence the hydration status leading to a dry and squamous skin.

Detergents↗

PubMed1995

Optimal and practicable designs for measuring plaque pH-profiles.

The shape of the plaque pH-profile after consumption of a food item determines the food's potential caries risk. This and related facts have caused an increased interest in measurements of plaque pH-profiles during the last decade. A standard design for these measurements is to take equally spaced observations over a certain period of time. The theory of optimal experimental design gives methods for positioning the measurements of a pH-profile in an optimized way. The objective is to minimize the effort given a desired precision of the estimated profile characteristic or to maximize the precision given the number of measurements. We show that a reduction in the number of measurements up to 50 per cent or a respective improvement in precision of the estimates as compared to standardly applied designs is possible. This implies less inconvenience for the subjects and better compliance with the needs of investigation. Our study is intended to demonstrate the applicability of the theory of optimal experimental design which has the potential to improve the efficiency of medical research.

Dental Caries Susceptibility↗

PubMed1990