Brief report: speed of information processing in children with insulin-dependent diabetes mellitus.

OBJECTIVE: To determine whether children with insulin-dependent diabetes mellitus (IDDM) process information more slowly than children who do not have diabetes. METHODS: We tested 31 children with early onset and longer duration of IDDM, 35 with later onset and briefer duration of IDDM, and 36 comparison children without diabetes. They were administered five tasks requiring rapid responding that assessed a range of cognitive processes. RESULTS: On most tasks, children in the three groups were quite similar in the accuracy and speed of performance. Furthermore, for children in the diabetic groups, disease-related variables were unrelated to accuracy and speed of performance. CONCLUSIONS: The results suggest that children with IDDM do not have a pervasive deficit in speed of information processing, although more circumscribed deficits in processing speed are possible.

Why does intermittent hydrostatic pressure enhance the mineralization process in fetal cartilage?

The purpose of this study was to determine which factor is the most likely one to have stimulated the mineralization process in the in vitro experiments of Klein-Nulend et al. (Arth. Rheum., 29, 1002-1009, 1986), in which fetal cartilaginous metatarsals were externally loaded with an intermittent hydrostatic pressure, by compressing the gas phase above the culture medium. Analytical calculations excluded the possibility that the tissue was stimulated by changes in dissolved gas concentration, pH or temperature of the culture medium through compression of the gas phase. The organ culture experiments were also mechanically analyzed using a poroelastic finite element (FE) model of a partly mineralized metatarsal with compressible solid and fluid constituents. The results showed that distortional strains occurred in the region where mineralization proceeded. The value of this strain was, however, very sensitive to the value of the intrinsic compressibility modulus of the solid matrix (Ks). For realistic values of Ks the distortional strain was probably too small (about 2 microstrain) to have stimulated the mineralization. If the distortional strain was not the factor to have enhanced the mineralization process, then the only candidate variable left is the hydrostatic pressure itself. We hypothesize that the pressure may have created the physical environment enhancing the mineralization process. When hydrostatic pressure is applied, the balance of the chemical potential of water across cell membranes may be disturbed, and restored again by diffusion of ions until equilibrium is reached again. The diffusion of ions may have contributed to the mineralization process.

Short-term memory and strategy use in children with insulin-dependent diabetes mellitus.

The present study was designed to examine recall and rehearsal in short-term memory among children with insulin-dependent diabetes mellitus (IDDM). Children with onset of IDDM before age 5 years, children with onset after 5 years, and children without IDDM were administered a measure of short-term memory that provides information about rehearsal as well as level of recall. Children with later onset of diabetes and children without IDDM were expected to recall more words and use more effective rehearsal strategies than children with early onset of diabetes. Results indicate that children diagnosed with IDDM early in life used similar rehearsal strategies but recalled fewer words than children with later onset of diabetes and children without IDDM. In addition, results provide evidence that children who are in poor control of their diabetes did not use strategies designed to increase recall as often, or as well as, children in better control of their diabetes.

Intermittent compression stimulates cartilage mineralization.

The effects of intermittent hydrostatic compressive force (ICF; 13 kPa applied at 0.3 Hz frequency), as a substitute for moderate loading in vivo, on ossifying bone organ cultures, were evaluated by means of (histo)-morphometry. In earlier studies, biochemical tests have shown an increased 45Ca intake and an increased alkaline phosphatase activity in bone organ cultures that received ICF, suggesting that ICF promoted matrix mineralization. The purpose of this study was to examine whether an effect of ICF on mineralization can be described by means of histomorphometrical analysis. Fetal mouse metatarsal bone rudiments were cultured for 5 days in serum-free medium, with (experimental) or without (control) ICF. Linear measurements taken during culture demonstrated that the dark zone in the center of the rudiment, representing mineralized hypertrophic cartilage, became significantly longer in the group that received ICF when compared with the control group. This finding was in conformation with the former studies. Histological sections of the rudiments, stained with Goldner's trichrome method were used to study changes at the cellular level and to describe the position and relative amount of mineralizing cartilage matrix (defined as Goldner-positive matrix [GPM]). Histomorphometry demonstrated that ICF treatment significantly increased the length of the hypertrophic cartilaginous zone and enhanced the amount of GPM between the mineralizing hypertrophic chondrocytes. However, the total length of the zone containing GPM was not increased, nor was the future bone collar, consisting of a thin osteoid seam, lengthened by ICF. These data indicate that the cellular processes involved in chrondrocyte hypertrophy were accelerated by ICF, as well as the extracellular processes leading to matrix mineralization. The study supports the earlier conclusion that embryonic bone rudiments are sensitive to mechanical stimulation and that moderate loading promotes their ossification in vitro.

Decreased mineralization and increased calcium release in isolated fetal mouse long bones under near weightlessness.

Mechanical loading plays an important role in the development and maintenance of skeletal tissues. Subnormal mechanical stress as a result of bed rest, immobilization, but also in spaceflight, results in a decreased bone mass and disuse osteoporosis, whereas supranormal loads upon extremities result in an increased bone mass. In this first in vitro experiment with complete fetal mouse cartilaginous long bones, cultured under microgravity conditions, we studied growth, glucose utilization, collagen synthesis, and mineral metabolism, during a 4-day culture period in space. There was no change in percent length increase and collagen synthesis under microgravity compared with in-flight 1x gravity. Glucose utilization and mineralization were decreased under microgravity. In addition, mineral resorption, as measured by 45Ca release, was increased. These data suggest that weightlessness has modulating effects on skeletal tissue cells. Loss of bone during spaceflight could be the result of both impaired mineralization as well as increased resorption.

Bone induction by demineralized bone particles: long-term observations of the implant-connective tissue interface.

Allogeneic demineralized bone (DB) powder was applied to subcutaneous pockets and cranial defects of rats and histological, histomorphometrical, and radiological evaluation was performed one to 52 weeks after implantation. In both type of implants cartilage formation was observed after 1 week between DB particles and in former vascular channels and cervices within the particles. Foci of bone formation were observed after 2 weeks in the center of the implant. Remineralization of DB particles only occurred in close contact with the new bone tissue by which they became incorporated, indicating that remineralization of DB is a continuation of a process which has started in live bone. At all times, the interface between implant and connective tissue of the host consisted of a layer of non-remineralized DB particles embedded in fibrous connective tissue. This rim was thinner at the dura-mater-side in the cranial implants, compared with the skin-side of the same implants as well as all sides of the subcutaneous implants. The rim became thinner with time but never disappeared completely. The outer contour of the mineralized implant sometimes ran right through a DB particle. A critical concentration of bone-inducing agent leaking from DB particles seems to be necessary for bone induction. We suggest that at the interface of the implant and loose connective tissue this concentration is never reached, which results in maintenance of the rim.

Intellective functioning and strategy use in children with insulin-dependent diabetes mellitus.

The cognitive development of children with either early or late onset insulin-dependent diabetes mellitus (IDDM) was investigated with tasks measuring intellectual ability, memory, and academic progress. In addition, children's perceptions of their competence and parents' perspectives on family functioning and their children's behavior were compared. It was found that children with IDDM scored within the normal range on standardized measures of intelligence and academic performance but evidenced some school difficulties, as reflected in subscale performance as well as in their need of remedial education services. Further, evidence was found to suggest deficiencies in children's use of strategies to organize and recall information, particularly for those with early onset of disease. Children's perceived self-competencies and parents' reports of family functioning were strikingly similar across groups. However, parents of those children whose illness began prior to age 5 reported their children to have poor attention spans and difficulty completing tasks.

Effects of childhood chronic illness on families.

This study examined the intellectual ability, academic performance, behavior, and social perceptions of children with a seizure disorder and their nonafflicted siblings. These data suggest the children are at risk for developmental lag and related problems. Impact of the illness on the family differentiated the sibling pair on many tasks and on parents' feelings towards their children. Although parents reported providing a normal environment for their children, the children reported their perceptions of the home environment to be further from the (population norm) than their parents. These results provide evidence for the whole family being affected by the chronic illness thus supporting social work's inherent holistic view. It also underscores the need for a secondary preventive approach with all families containing a child with a handicapping condition.