The use of metallic implants in the study of facial growth in children: method and application

On the basis of experience gained over a number of years, an account is given of the technique for insertion of the implants, the radiographic method, and the graphic procedure for preparation of growth tracings. Small pins of hard tantalum are hammered into the bone under local analgesia with a pencil-shaped instrument, in the tip of which the implant is placed. No surgical exposure is necessary. Because of remodeling resorption of the bone and eruption of the teeth, the implants can be placed only in certain places in the maxilla and mandible. In implant studies it is necessary to observe a high level of reproducibility in positioning the head in the cephalostat. An X -ray cephalostat with a built-in image intensifier has been designed which enables the position to be monitored by televison. In the graphic procedure, drawings of the arches from dental casts are incorporated in tracings of profile radiographs; the paths of eruption of the teeth and development or the arches can then be examined with the metallic implants as references.     

The use of a temperature-profiled position transducer for the study of low-temperature growth in Gramineae

A device is described for measuring linear extension of grass leaves during controlled cooling and heating of the growing region. The instrument was employed to investigate the sensitivity to temperature of the expanding third and fourth leaves of Lolium temulentum L. seedlings. Using a stepped temperature profile it was established that there was no lag in the response of growth rate to rapid changes in temperature below 16°C. If cooling was continued to the point where growth ceased (1°C) but no further, then rates of growth on rewarming were enhanced over the chilling range and reverted to the original rate at 20°C. Cooling to successively lower subzero temperatures before rewarming abolished the hysteretic enhancement, progressively raised the temperature at which growth resumed and decreased the rate of extension until, at-5.3°C, no recovery occurred. The temperature sensitivity of growth, measured as Q₁₀, was essentially constant when cooling from 20°C to 5°C, with 5°C-grown leaf tissue exhibiting a higher mean Q₁₀ than tissue developed at 20°C. The possible physiological significance of these data is discussed.Abbreviations LVDT linear variable displacement transformer - Pe, Fx temperatures at which growth ceases during cooling and resumes during rewarming     

Bone structural data for the Denver longitudinal growth study

The Denver Longitudinal Growth Study is one of the most comprehensive longitudinal studies of growth carried out to date. Measurements of long bone lengths, cross-sectional diaphyseal properties, and articular breadths were taken from archived radiographs of 20 study subjects measured at an average of 36 time points from early infancy to late adolescence. Anthropometric dimensions for these individuals were also obtained from study archives. These data are now available in an online data set: 10.5061/dryad.xsj3tx9gq .     

Comparison of Tanner-Whitehouse and Greulich-Pyle methods in a large scale Danish Survey

In Denmark no systematic investigation of skeletal development had been made prior to this investigation which involved 1009 school children aged 7–18 years in a transverse examination. The skeletal age was estimated according to the American atlas of Greulich-Pyle. The English system of Tanner-Whitehouse was also applied. In this latter method the stage of development of 20 selected bones in the hand and wrist is rated on a scale of 8 (in one case 9) possible stages. Each bone is awarded points according to its stage of development. These points are totalled for the 20 bones and reference to a table gives the skeletal age. The problem with this system is that the later stages of carpal bone development cannot be reliably placed on the scale. Their point system is calculated in such a way that a difference of one stage in rating of a single carpal bone in older children would give rise to a difference of up to two years in the skeletal age estimation. For younger children the method is, however, quite reliable. The investigation has shown that Greulich-Pyle's atlas can be applied to Danish children of 7-18 years of age provided that a correction of six months is made. A variable error of about four months was found when using Greulich-Pyle compared to about two months with Tanner-Whitehouse.     

Altitude and infant growth in Bolivia: A longitudinal study

The growth of 79 healthy, well-nourished lowland (400 M) and highland (3600 M) Bolivian infants was analyzed in a longitudinal study through the first postnatal year. Compared to low altitude infants, the high altitude infants were found, by analysis of covariance controlling for size at the previous exam, to be significantly shorter at birth, 1 and 6 months, while they were significantly lighter only at birth and 1 year. Recumbent length gain was slower in the high altitude infants in the early months of life, while weight gain did not differ between altitudes. The observed lower weights at high altitude throughout the first year appear to be due to a persistence of lower weights seen at birth and not to postnatal growth retardation. Significantly greater triceps and subscapular skin-fold thickness measurements were found in the highland group, despite their smaller length and weight. The possible causes and implications of the greater fat accumulation in the highland infants are discussed.     

The use of a hydroxylapatite-filter steroid receptor assay method in the study of the modulation of androgen receptor interaction

Receptors for androgen, estrogen, and glucocorticoid can be assayed by hydroxylapatite adsorption of the radioactive steroid-receptor complex and washing of the adducts on membrane filters mounted on a multiple filter holder. The method is economical, very rapid and sensitive. This new receptor assay method was used to study the modulation of androgen receptor of rat ventral prostate by metal ions, thiols, and ligand structure. The interaction of androgen with the naked receptor is inhibited by 10 microM ZnCl2, CdSO4, or CuSO4 but this inhibition is competed by androgen and is reversed by DTT. The androgen-receptor complex is less sensitive to divalent metal ions but Zn2+, at 3 mM, appears to alter the conformation of the receptor and promote the release of androgen. Certain phenanthrene derivatives exhibited striking structural specificities in their ability to compete with radioactive androgen for binding to the prostate receptor. The results suggest that the receptor has binding preference toward individual ring structure in the steroid.     

Genetic influences on growth traits of BMI: a longitudinal study of adult twins

Objective: To investigate the interplay between genetic factors influencing baseline level and changes in BMI in adulthood. Methods and Procedures: A longitudinal twin study of the cohort of Finnish twins (N = 10,556 twin individuals) aged 20–46 years at baseline was conducted and followed up 15 years. Data on weight and height were obtained from mailed surveys in 1975, 1981, and 1990. Results: Latent growth models revealed a substantial genetic influence on BMI level at baseline in males and females (heritability (h²) 80% (95% confidence interval 0.79–0.80) for males and h² = 82% (0.81, 0.84) for females) and a moderate‐to‐high influence on rate of change in BMI (h² = 58% (0.50, 0.69) for males and h² = 64% (0.58, 0.69) for females). Only very weak evidence for genetic pleiotropy was observed; the genetic correlation between baseline and rate of change in BMI was very modest (−0.070 (–0.13, −0.068) for males and 0.04 (0.00, 0.08) for females. Discussion: Our population‐based results provide a basis for identifying genetic variants for change in BMI, in particular weight gain. Furthermore, they demonstrate for the first time that such genetic variants for change in BMI are likely to be different from those affecting level of BMI.     

The phased division of the freshwater dinoflagellate Ceratium hirundinella and its use as a method of assessing growth in natural populations

SUMMARY. The nocturnal phasing and partial synchrony of cell division in Ceratium hirundinella was investigated on four occasions for dense planktonic populations in a small productive lake (Esthwaite Water). The population growth rates deduced from the proportion of cells dividing per day are compared with the rates of increase of cell density in the lake. The maximum proportion of Ceratium cells found dividing at any time was 5.8 ± 1.0%, and the time of optimum division was 03.00 hours G.M.T. The daily rate of division during the main phase of population increases was similar to that deduced from the overall population increments at that time, although during the week of collection the increase had apparently ceased temporarily. On the other three occasions, either increase of cell numbers had ceased or the population was declining, but a continued low rate of division ( c . 3% day⁻¹) was found.
The nocturnal division of Ceratium in Esthwaite Water is compared with the division phasing of dinaflagellates described from elsewhere. Some general problems associated with the derivation of estimates of population growth rate from division frequency are also considered.     

The use of a metabolically structured model in the study of growth, nitrification, and denitrification by Thiosphaera pantotropha

Thiosphaera pantotropha is capable of aerobic heterotrophic nitrification and both aerobic and anaerobic denitrification. These phenomena have been studied in acetate-limited aerobic and anaerobic continuous cultures supplied with ammonia and nitrate. The internal reaction rates were defined, based on biochemical knowledge. The observable external conversion rates are related through a linear equation on the basis of the specified internal reaction rates. The linear equation is a Pirt relation extended for microbial systems with multiple electron donors (acetate and ammonia) and electron acceptors (oxygen and nitrate). The coefficients in this equation were estimated from the continuous culture measurements, and are composed of parameters involved in ATP production and consumption by the microorganism. It is shown that with realistic values for these parameters, the metabolically structured model describes the aerobic as well as the anaerobic experiments.