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Biomedical subjects

J W Hansen

Publications and source records attributed to J W Hansen.

At least 55 records · Page 3Linked to original sources
PubMed1988

Calcium and phosphorus requirements in bone mineralization of preterm infants.

We studied postnatal bone mineralization, as measured by photon absorptiometry, in 36 preterm infants (birth weight less than 1600 gm) who were fed (1) a commercial premature formula containing 117 mg calcium and 58.8 mg phosphorus per 100 kcal, (2) the same formula containing a higher concentration of phosphorus (82 mg/100 kcal), (3) the same formula with higher concentrations of calcium (140 mg/100 kcal) and phosphorus (82 mg/100 kcal), or (4) their mother's milk. Serum calcium, phosphorus, protein, albumin, bicarbonate, 25-hydroxyvitamin D, and alkaline phosphatase levels were measured at the start of the study and every 2 weeks until the infants achieved a weight of 1900 gm. Birth weights and gestational ages were similar in all four groups. The human milk group had lower serum phosphate and bone mineral values than those in the three formula groups. Bone mineral content was similar in the three formula groups. However, only the formulas of the first and third groups allowed approximation of the intrauterine bone mineralization curve. Bone mineral content in infants fed human milk was below the intrauterine rate.

Bone and Bones↗
PubMed1988

Horse-baited insect trap and mobile insect sorting table used in a disease vector identification study.

A horse-baited trap and a mobile insect sorting table were used to conduct an arthropod survey for potential vectors of Potomac Horse Fever in southern Maryland and northern Virginia. The trap and table worked effectively for the live collection and sorting of haemophagous Diptera such as: Simulium spp., Stomoxys calcitrans, Musca autumnalis, Tabanus spp. and Chrysops spp. during the diurnal collections periods, and Culicoides spp. during the crepuscular periods. The trap was not as convenient for live collection of mosquito species during the nocturnal period. Modifications to the trap design was suggested for mosquito live trapping.

Animals↗
PubMed1985

Dynamics of calcium metabolism in infancy and childhood. I. Methodology and quantification in the infant.

The dynamics of calcium metabolism in the human infant were determined using stable isotopes of calcium as tracers. Two isotopes, one given intravenously and the other orally were used. Tracer time-dependent dilutions were measured with high accuracy and precision using thermal ionization mass spectrometry. Similar studies were performed in infant rhesus monkeys using radio tracers. Analysis of the isotope dilutions using a compartmental model method showed quite similar results for the infants of both species. These similarities support the validity both of using stable isotopes in human studies, and the use of the rhesus monkey as a model for human calcium dynamics. It was found that the classical steady state compartmental model was inadequate for use in the rapidly growing infant, and the model was modified to account for the expansion of the body fluid calcium compartment during the time of the study. Comparison with adult human calcium metabolic parameters showed that urinary calcium flows are much higher in the adult than in the newborn, relative to other calcium metabolic parameters. Other parameters of infant calcium metabolism are all consistent with the growth and more rapid metabolism usually seen in the young.

Absorption↗
PubMed1985

Nutritional balance studies: evaluation of a premature infant formula.

A 24 kcal/oz (81 kcal/100 ml) premature infant formula (Enfamil Premature Formula) with moderately high mineral content (117 mg Ca/100 ml and 58 mg P/100 ml) and a protein content of 3 g/100 kcal was evaluated in sixteen 3-day balance studies at 10 and 21 days of age in nine premature infants with birth weights from 1,200 to 1,400 g. Growth rates were similar to in utero rates, and the formula was well accepted and tolerated. Calcium retention (62.5%) was similar to in utero accretion, and phosphorus retention was only slightly lower. Nitrogen retention was high without the development of metabolic acidosis or abnormal serum urea nitrogen levels.

Calcium↗
PubMed1983

Comparison of three routes of administration of a water soluble anthelmintic: levamisole.

The plasma concentration of levamisole was determined by liquid chromatography in three groups of 20 heifers treated with levamisole by intramuscular administration, drenching and in drinking water respectively. Maximum concentrations were observed at three hours (1.10 +/- 0.16 microgram/ml) and six hours (0.64 +/- 0.06 microgram/ml) after intramuscular administration and drenching respectively. Large individual variations in plasma concentrations were observed following treatment in drinking water with four animals showing maximum concentrations below 0.1 microgram/ml. Variation in water intake therefore makes the latter method less reliable.

Administration, Oral↗
PubMed1982

Insulin receptors in the developing fetal lung.

Fetal lung insulin receptor numbers and affinities were studied in rat pregnancies from 15 to 22 days gestation. Insulin receptor binding capacities were found to increase six-fold from approximately 100 fmoles insulin bound/mg lung DNA at 15 days gestation to approximately 600 fmoles bound/mg DNA at 22 days gestation. However, the affinity constants of the receptors were unchanged during this same period (high affinity, 1.9 +/- 0.4 S.E. and low affinity, 0.03 +/- 0.01 S.E.). The results suggest that the lung may become increasingly more sensitive to insulin as development progresses.

Animals↗
PubMed1981

Dysplastic cutaneous osteomatosis. A unique case of true osteoma.

A unique cas of dermal calcification occurred in a 14-month-old femal infant. Results of all pertinent laboratory data obtained on this patient were within normal limits except for an elevation of the heat labile fraction of alkaline phosphatase. A skin biopsy specimen showed irregularly shaped deposits of calcified osteoid with osteoblasts. As yet, neither the cause nor the prognosis of this disease has been delineated.

Calcinosis↗
PubMed1981

Zinc determined in 10-microL serum or urine samples by flameless atomic absorption spectrometry.

We describe a precise flameless atomic absorption spectrometric method requiring only 10 microL of sample, which thus permits repeated measurements in the neonate. Standard curves covering the range of 0 to 30 mg of zinc per liter, with standards in various matrixes (albumin, glycerol, serum, or nitric acid) had slopes ranging from 0.49 to 1.17, relative to that for aqueous standards. We prepared low-zinc matrixes, which had slopes similar to that of serum, by dialyzing serum or a 50 g/L solution of albumin vs a buffered zinc-free dialysis fluid containing appropriate inorganic constituents. Use of thoroughly de-ionized water, reagent-grade chemicals, "ultrapure" nitric acid, specified disposable plastic ware, and appropriate pipet tip-rinsing techniques minimized extraneous contamination with zinc. Concentrations of zinc in serum calculated from a "rational-method" calibration algorithm fit to the standard curve agreed well with independent determinations by flame atomic absorption spectrometry.

Humans↗
PubMed1979

Laboratory infection of blackflies (Simuliidae) and midges (Chironomidae) by the mosquito mermithid, Romanomermis culicivorax.

Penetrating infective juveniles of Romanomermis culicivorax usually killed first-stage larvae of Chironomus maturus Johann., Chironomus sp., Simulium damnosum Theo., and S. venustum Say. Nematodes were melanized and died after they entered fourth stage larvae of 2 chironomid species, but no host reaction was evident after entry into fourth-stage blackfly larvae. In contrast, the nematodes initiated development in the latter hosts, which died before the nematodes completed their development.

Animals↗
PubMed1976

Variable efficacy of glucocorticoids in congenital adrenal hyperplasia.

We have examined the suppression of urinary pregnanetriol and 17-ketosteroids during treatment with cortisol, cortisone, prednisone, and dexamethasone in eight patients with congenital adrenal hyperplasia. A large individual variation in response to each agent was observed. In some individuals, cortisone is less effective than its generally accepted potency would indicate. At equivalent glucocorticoid dosage, dexamethasone was twice as effective as the other steroids in suppressing urinary 17-ketosteroids and pregnanetriol. The potency of dexamethasone in suppressing adrenal function was 80 times that of cortisol, about twice its generally accepted potency as a glucocorticoid or anti-inflammatory agent.

17-Ketosteroids↗
PubMed1975

Monthly gonadotropin cycles in premenarcheal girls.

Patterns of nocturnal excretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were investigated in 11 girls. Autoregressive digital filtering of low- and high-frequency variations was used to make patterns more apparent. Coincident FSH and LH surges, separated by an interval of 20 to 40 days, were seen in specimens from three of six postmenarcheal girls and three to five premenarcheal girls. This suggests that cyclic hypothalamic-pituitary-ovarian interactions occur before menarche.

Adolescent↗
PubMed1975

A new method simplifying collection of serial specimens for gonadotropin determinations.

Patterns of gonadotropin levels have been compared in specimens of serum, 24-h urine collections, and first morning urine voidings collected throughout a menstrual cycle from 8 sexually mature, young women. Quantities of gonadotropins in first morning voidings were found to provide a reliable estimate of 24-h excretion of these hormones and demonstrate the same patterns of change as do serum and 24-h urine specimens. Thus first morning voidings satisfactorily overcome logistical problems inherent is serial serum and 24-h urine sampling for studying gonadotropin excretion patterns.

Adolescent↗
PubMed1973

Direct measurement of osteolysis in man.

Precise, direct measurement of bone calcium release (v(o-)) has been accomplished using a continuous tracer administration (CTA) technique. Dietary calcium (96.97% (40)Ca) is replaced by (40)Ca (99.991% (40)Ca) and blood levels of the naturally occuring isotope (48)Ca are monitored by neutron activation analysis as a function of time. (48)Ca abundance falls as this isotope is excreted and only partially replaced by release from bone. After a suitable period, an asymptotic abundance of (48)Ca in serum, E, is approached which is the fraction of the turnover rate of the rapidly exchangeable calcium pools coming from the skeleton (E = v(o-)/v(t)). E is determined with a standard error of 2%, providing a precise, sensitive index of v(o-). 13 studies in three normal men and one postmenopausal woman receiving maintenance estrogen show large intersubject variations in parameters of calcium metabolism using both CTA and pulse tracer administration (PTA) plus balance techniques. Induced hypercalcemia results in a prolonged decrease in v(o-). Glucocorticoid therapy initially and consistently induces a marked hypercalciuria while effects on most other parameters of calcium kinetics are variable. In two men E fell when testosterone was added to glucocorticoid treatment, consistent with the known antiosteolytic effect of androgens, despite the short period of study.

Activation Analysis↗