Bone mineral density in long-term survivors of childhood cancer.

Bone mineral density (BMD) of the lumbar spine was measured in 97 long-term survivors of childhood cancer 5-23 years after diagnosis using dual-energy X-ray absorptiometry (DXA). They had been treated for acute leukemia (n = 22), brain tumors (n = 16), lymphomas (n = 16), Wilms' tumor (n = 10), neuroblastoma (n = 7) and other cancers (n = 26). The correlations between BMD and the Z-scores for weight for height, height for age and weight for age at diagnosis and follow-up were evaluated with stepwise multiple regression. Correlations with cumulative corticosteroid and radiation dose were examined with Spearman's correlation coefficient. The number of nature of fractures were noted. A BMD Z-score of below -2 was present in 13 and a BMD Z-score of -1 to -2 in 31 children. In total, a low BMD was observed in 45% of children. Height for age at follow-up correlated significantly with BMD Z-score. Increasing doses of cranial irradiation (18-54 Gy) were associated with lower BMD (p = 0.001, Spearman). This was true also for 22 children with acute lymphoblastic leukemia (ALL) who had received 18-24 Gy cranial irradiation (p = 0.04, Spearman). Fractures occurred in 14 children following trauma. The difference in BMD Z-scores of children with and without fractures did not achieve statistical significance although the majority of the children with fractures had low BMD Z-scores. The significant inverse correlation between height for age at follow-up and BMD must be interpreted with the realization that DXA is not a volumetric measurement of BMD and that short stature is associated with a smaller skeletal mass.

Disproportionate distribution of field potentials across the toad's tectal visual map in response to diffuse light ON and OFF stimulations.

In toads Bufo marinus and Bufo bufo spinosus, field potentials (FPs) were recorded from the surface of the optic tectum at different sites of the visual map in response to a sudden diffuse darkening (OFF) and lightening (ON) of the visual field of the contralateral eye. The OFF and ON responses were differently pronounced or even failed to occur. The latency of the former was significantly less than the one of the latter. FP amplitudes of the OFF and ON responses were strongest in the representation of a horizonto-superior anterio-lateral portion of the visual field and weakest toward the posterior field of vision. This phenomenon suggests various interpretations for subsequent experiments.

Risk factors for the development of osteoporosis in a South African population. A prospective analysis.

Despite the vast number of risk factors that apparently predispose to the development of osteoporosis (OP), they have not been accurately identified and given relative priority. In order to analyse possible risk factors prospectively in a local patient population with overt OP (histomorphometrically confirmed and characterised) and compare it with an appropriately matched non-OP control group (with normal bone mass on dual-energy X-ray absorptiometry), a detailed general history, risk factor analysis, dietary history and anthropometric data were obtained from 56 OP and 125 non-OP subjects. In females a positive family history of OP (P = 0.002), a fair complexion (P = 0.009), lower body mass (P = 0.02) and height (P = 0.03), no breast-feeding of babies (P = 0.006), a history of smoking (P = 0.001) and fat distribution around the waist (P = 0.009) were identified as risk factors. In males lack of exercise (P = 0.008), a history of smoking (P = 0.01), lower body mass (P = 0.04) and height (P = 0.04), a preference for salty food (P = 0.02) and fat distribution around the waist (P = 0.002) appeared to predispose. Dietary calcium, phosphorus, protein and caffeine intakes were similar in OP and control subjects, but alcohol consumption was clearly higher in both OP males (P = 0.001) and females (P = 0.01).

Forebrain-mediated control of visually guided prey-catching in toads: investigation of striato-pretectal connections with intracellular recording/labeling methods.

Studies in anurans have shown that ablation of the whole telencephalon (or the caudal striatum) abolishes visual prey-catching behavior, whereas an additional lesion to the pretectum leads to hyperexcited, "disinhibited" prey-catching. This suggests a disinhibitory gating/arousal function mediated by two inhibitory projections: telencephalon to pretectum and pretectum to tectum. Since the latter projection has been physiologically investigated already in great detail, the present paper focuses on the former projection. Intracellular recordings from the pretectal region in response to electrical stimulation of the ipsilateralcaudal ventral striatum or the ipsilateral lateral forebrain bundle revealed cells that display pure inhibitory postsynaptic potentials with short latencies of 2-3 ms, indicative for monosynaptic striato-pretectal connection. But it must be emphasized that a relatively large number of pretectal neurons of this sample showed sequential excitatory/inhibitory postsynaptic potentials. The latter data are not in conflict, with the hypothesis, rather they open new perspectives for further investigations.

Responses of medullary neurons to moving visual stimuli in the common toad. II. An intracellular recording and cobalt-lysine labeling study.

Intracellular recording and labeling of cells from the toad's (Bufo bufo spinosus) medulla oblongata in response to moving visual (and tactual) stimuli yield the following results. (i) Various response types characterized by extracellular recording in medullary neurons were also identified intracellularly and thus assigned to properties of medullary cell somata. (ii) Focussing on monocular small-field and cyclic bursting properties, somata of such neurons were recorded most frequently in the medial reticular formation and in the branchiomotor column but less often in the lateral reticular formation. (iii) Visual object discrimination established in pretectal/tectal networks is increased in its acuity in 4 types of medullary small-field neurons. The excitatory and inhibitory inputs to these neurons evoked by moving visual objects suggest special convergence likely to increase the filter properties. (iv) Releasing conditions, temporal pattern, and refractoriness of cyclic bursting neurons resemble membrane characteristics of vertebrate and invertebrate neurons known to play a role in premotor/motor activity. (v) Integrating functions of medullary cells have an anatomical correlate in the extensive arborizations of their dendritic trees; 5 morphological types of medullary neurons have been distinguished.

The impairment of mobility and development in freshwater snails (Physa fontinalis and Lymnaea stagnalis) caused by herbicides.

1. The pulmonate freshwater snails Physa and Lymnaea and the earthworms Eisenia and Lumbricus can take up and concentrate a carbamate herbicide (chlorpropham). 2. The mobility of freshwater snails was diminished in the presence of the herbicides chlorpropham (carbamate), cycloate (thiocarbamate), pentanochlor (amide) and chloroxurone (urea derivate). 3. The egg-assemblies of Lymnaea stagnalis turned out to be suitable objects for testing the influences of herbicides upon embryonic development. 4. In the presence of chlorpropham, chloroxurone, cycloate, propanil, simazine and terbutryne, all applied in concentrations lower than in practical use, the period of egg-maturing was delayed and the total number of dead embryos increased. 5. Developing snail eggs were very sensitive towards triazine herbicides (simazine, terbutryne) reflecting in an ED50-value lower than 10(-7) M. 6. Similar herbicidal-induced effects suggested that the developing stages of snail embryos may be suitable models for the ecologically more important but experimentally less accessible earthworms.

Evidence that herbicides relaxing smooth and oblique-striated muscles affect the muscle cell membrane.

1. From the example of two herbicides [chlorpropham (CIPC) and terbutryn], it has been shown that such compounds inhibit spontaneously occurring, as well as pharmacologically (ACh, KCl, caffeine) or electrically (negative DC) evoked tonic and phasic activities in different smooth and oblique-striated muscles of snails [penis retractor muscle (PRM) of Helix], worms (torsos and muscle segments of Lumbricus and Eisenia) and mice (small intestine of Mus). In PRM preparations, experiments with the denervating drugs 6-OHDA, -5,6-DHT, and reserpine, or with the serotonergic receptor blocker methysergide, produced evidence that the herbicidal side-effect was not caused by action on the nervous system. 3. A relaxant effect on ACh-evoked contractions in the PRM was induced by drugs altering the Ca2+ equilibrium, for example, theophylline, papaverine, chlorpromazine, or trifluoperazine. 4. In addition, an extracellular Ca2+ deficiency or the presence of papaverine led to an enhancement of a CIPC-caused inhibition of ACh- or KCl-induced contractions. 5. The amplitudes of chemically evoked contractions in "skinned muscle cells" of Helix PRM or Lumbricus segments were influenced neither by CIPC nor by terbutryn. 6. CIPC was concentrated by the intact PRM and by a membrane containing PRM fraction, as well as by the worms' circular muscle system. 7. A fluorescent CIPC analogue, dansyl-3-chloroaniline, characterized by a similar inhibiting property on the induced contractions was detected at the border of PRM cells. 8. It is concluded that in the different muscle systems the side-effect of the herbicidal compounds is located in the outer muscle cell membrane where a Ca2+-dependent mechanism may be concerned.