Rubinstein-Taybi syndrome medical guidelines

Children and adults with Rubinstein-Taybi Syndrome have specific medical conditions that occur with greater frequency than the general population. Based on the available information from the literature and clinical experience, recommendations for specific surveillance and interventions are made to guide those clinicians caring for individuals with Rubinstein-Taybi Syndrome. This is a first attempt at medical guidelines for individuals with RTS in the United States. On-going research is needed in many areas to guide decisions in medical care and allow for refinement of these medical guidelines.     

Hepatic microvascular development in relation to the morphogenesis of hepatocellular plates in neonatal rats

The development of hepatic microvascular heterogeneity after birth, and its temporal relationship to the development of parenchymal cell plates have received little attention. As a result, the morphogenesis of some of the parameters contributing to this heterogeneity in suckling and weaned rats was studied as a function of time between postpartum days 4 and 30 using in vivo light microscopic, electron microscopic, and immunocytochemical methods. During the early suckling period, the sinusoid network is highly anastomotic, with little evidence of zonation, and the parenchymal cell plates contain multiple cells and are irregularly arranged throughout the lobule. Sinusoidal endothelial fenestration is sparse at 4 days, but phagocytic Kupffer cell (KC) function already exists and exhibits zonal heterogeneity, with more cells located in the periportal zone. With increasing age, endothelial fenestrae increase and organize as sieve plates. Widened centrilobular radial sinusoids form through a loss ("drop-out") of intersinusoidal sinusoids (ISS). Concomitantly, the associated cell plates straighten and become one cell thick. Hepatocyte DNA synthesis and mitosis are higher in the periportal zone, which retains thickened cell plates and anastomotic sinusoids. The centrilobular sinusoids may widen to accommodate the increased volume of blood that results from the loss of ISS as well as the increased numbers of periportal sinusoids containing flow that feed these vessels. KC phagocytic activity increases during the suckling period concomitant with an increase of gut-derived endotoxin in the portal blood, which suggests that the KCs may be releasing mediators that affect sinusoid diameter, blood flow, endothelial fenestration, and perhaps parenchymal growth either directly or through the stimulation of growth factors.     

Positive illusory bias and the self-protective hypothesis in children with learning disabilities.

We tested the hypothesis that overestimations of performance by children with learning disabilities (LD) are self-protective and will dissipate following positive feedback. Twenty-three boys and 17 girls with LD (ages 10.6 to 13.5 years) and a control group of non-LD matched children (22 boys and 17 girls) provided a prediction of their performance on a spelling test prior to completing the test. Subsequently, they were randomly assigned to either a positive feedback or a no-feedback condition. Finally, they provided a second prediction of performance on an equivalent spelling test. In children with LD, there was a positive bias in their predictions of performance, and, following positive feedback, their predictions became accurate. In children without LD, there was no positive bias and no effect of feedback. The results provide further support for the presence of a positive illusory bias and for the self-protective hypothesis in children with LD.     

Learning in escape/avoidance tasks in female rats does not vary with reproductive condition

To determine whether the development of novel stimulus-response associations by the mother during the periparturient period is attributable to a general facilitation of learning produced by the hormonal milieu during that period, learning ability under various reproductive conditions was assessed in two tasks unrelated to the periparturitional situation. The two tasks, selected because they equalized the various groups for motivation and performance variables, were acquisition of a water-maze escape (including two reversals), and acquisition and retention of an unsignalled shuttlebox shock avoidance. The groups tested in the water maze were a midpregnant group, an immediately prepartum group, and an immediately postpartum group. In the shuttlebox, the same conditions (different rats) were compared, together with a nonpregnant estrus condition, and a nonpregnant diestrus condition. The results of both experiments indicate that although learning occurred, the characteristics of acquisition and retention were not influenced by reproductive condition.     

Rhabdoid tumor of the kidney with primitive neuroectodermal tumor of the central nervous system: Associated tumors with different histologic,cytogenetic, and molecular findings

Rhabdoid tumor of the kidney (RTK) is associated with tumors of the central nevous system (CNS) in approximately 15% of cases. We describe the clinical features, histologic and cytogenetic findings, and molecular analysis of renal and CNS tumors from the same patient. The histology of the renal tumor was consistent with rhabdoid tumor. The CNS tumor was a primitive neuroectodermal tumor (PNET). The karyotype of the RTK was normal male. The PNET of the brain demonstrated monosomy 22 as the only cytogenetic abnormality, similar to reported cases of malignant rhabdoid tumor of the brain, but dissimilar to nonrandom cytogenetic findings in other CNS PNETs. Molecular cytogenetic and DNA marker studies confirmed loss of chromosome 22 in this patient's brain tumor. DNA allelotyping showed retention of both parental chromosome 22 alleles in the RTK and loss of the maternal allele in the PNET. Evaluation of additional RTKs and brain tumors occurring in the same patient may provide insight into the origins and relationships of these enigmatic tumors.     

Trisomy 2, trisomy 20, and del(17p) as sole chromosomal abnormalities in three cases of hepatoblastoma

Short-term cultures of three hepatoblastomas were analyzed cytogenetically. Trisomy 2, trisomy 20, and a deletion of 17p were found as the sole abnormalities, yielding the karyotypes 47,XY, + 2; 47,XX, + 20; and 46,XX,del(17)(p12)/46,XX. This is the first reported case of deletion of 17p as the sole chromosomal abnormality in a hepatoblastoma and the first reported case of trisomy 20 without double minute chromosomes as a sole chromosomal abnormality in hepatoblastoma.     

Capillaries in aging rat olfactory bulb: A quantitative light and electron microscopic analysis

Olfactory bulbs from Charles River (Crl) rats from 3 to 36 months have been examined with light and electron microscopy. Total capillary length, surface, and volume, as well as number of endothelial cells, increases during the twofold increase in olfactory bulb volume from 3 to 18 months, but the relative density of these parameters shows no change during this time; from 18 to 36 months when neuronal cell body and dendrites are decreasing markedly in size, the relative density of capillaries shows only a modest decrease. Capillary lumen size and capillary wall thickness remain the same throughout life, but basal lamina thickness doubles from 3 to 24 months and then remains constant from 24 to 36 months. The incidence of several unusual ultrastructural features of the outer capillary basal lamina has been shown to increase with age.